Chromosome Segregation: The orderly segregation of CHROMOSOMES during MEIOSIS or MITOSIS.Chromosomes: In a prokaryotic cell or in the nucleus of a eukaryotic cell, a structure consisting of or containing DNA which carries the genetic information essential to the cell. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Kinetochores: Large multiprotein complexes that bind the centromeres of the chromosomes to the microtubules of the mitotic spindle during metaphase in the cell cycle.Chromosome Mapping: Any method used for determining the location of and relative distances between genes on a chromosome.Mitosis: A type of CELL NUCLEUS division by means of which the two daughter nuclei normally receive identical complements of the number of CHROMOSOMES of the somatic cells of the species.Spindle Apparatus: A microtubule structure that forms during CELL DIVISION. It consists of two SPINDLE POLES, and sets of MICROTUBULES that may include the astral microtubules, the polar microtubules, and the kinetochore microtubules.Centromere: The clear constricted portion of the chromosome at which the chromatids are joined and by which the chromosome is attached to the spindle during cell division.Chromosomes, Fungal: Structures within the nucleus of fungal cells consisting of or containing DNA, which carry genetic information essential to the cell.Meiosis: A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.Chromosomal Proteins, Non-Histone: Nucleoproteins, which in contrast to HISTONES, are acid insoluble. They are involved in chromosomal functions; e.g. they bind selectively to DNA, stimulate transcription resulting in tissue-specific RNA synthesis and undergo specific changes in response to various hormones or phytomitogens.Chromosomes, Bacterial: Structures within the nucleus of bacterial cells consisting of or containing DNA, which carry genetic information essential to the cell.X Chromosome: The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species.Aurora Kinases: A family of highly conserved serine-threonine kinases that are involved in the regulation of MITOSIS. They are involved in many aspects of cell division, including centrosome duplication, SPINDLE APPARATUS formation, chromosome alignment, attachment to the spindle, checkpoint activation, and CYTOKINESIS.Cell Cycle Proteins: Proteins that control the CELL DIVISION CYCLE. This family of proteins includes a wide variety of classes, including CYCLIN-DEPENDENT KINASES, mitogen-activated kinases, CYCLINS, and PHOSPHOPROTEIN PHOSPHATASES as well as their putative substrates such as chromatin-associated proteins, CYTOSKELETAL PROTEINS, and TRANSCRIPTION FACTORS.Anaphase: The phase of cell nucleus division following METAPHASE, in which the CHROMATIDS separate and migrate to opposite poles of the spindle.Chromosome Banding: Staining of bands, or chromosome segments, allowing the precise identification of individual chromosomes or parts of chromosomes. Applications include the determination of chromosome rearrangements in malformation syndromes and cancer, the chemistry of chromosome segments, chromosome changes during evolution, and, in conjunction with cell hybridization studies, chromosome mapping.Chromosome Pairing: The alignment of CHROMOSOMES at homologous sequences.Chromatids: Either of the two longitudinally adjacent threads formed when a eukaryotic chromosome replicates prior to mitosis. The chromatids are held together at the centromere. Sister chromatids are derived from the same chromosome. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Chromosome Aberrations: Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.Chromosomes, Human: Very long DNA molecules and associated proteins, HISTONES, and non-histone chromosomal proteins (CHROMOSOMAL PROTEINS, NON-HISTONE). Normally 46 chromosomes, including two sex chromosomes are found in the nucleus of human cells. They carry the hereditary information of the individual.Sex Chromosomes: The homologous chromosomes that are dissimilar in the heterogametic sex. There are the X CHROMOSOME, the Y CHROMOSOME, and the W, Z chromosomes (in animals in which the female is the heterogametic sex (the silkworm moth Bombyx mori, for example)). In such cases the W chromosome is the female-determining and the male is ZZ. (From King & Stansfield, A Dictionary of Genetics, 4th ed)Metaphase: The phase of cell nucleus division following PROMETAPHASE, in which the CHROMOSOMES line up across the equatorial plane of the SPINDLE APPARATUS prior to separation.Microtubules: Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.Chromosomes, Human, Pair 1: A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.Aurora Kinase B: An aurora kinase that is a component of the chromosomal passenger protein complex and is involved in the regulation of MITOSIS. It mediates proper CHROMOSOME SEGREGATION and contractile ring function during CYTOKINESIS.Aneuploidy: The chromosomal constitution of cells which deviate from the normal by the addition or subtraction of CHROMOSOMES, chromosome pairs, or chromosome fragments. In a normally diploid cell (DIPLOIDY) the loss of a chromosome pair is termed nullisomy (symbol: 2N-2), the loss of a single chromosome is MONOSOMY (symbol: 2N-1), the addition of a chromosome pair is tetrasomy (symbol: 2N+2), the addition of a single chromosome is TRISOMY (symbol: 2N+1).Nondisjunction, Genetic: The failure of homologous CHROMOSOMES or CHROMATIDS to segregate during MITOSIS or MEIOSIS with the result that one daughter cell has both of a pair of parental chromosomes or chromatids and the other has none.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Schizosaccharomyces: A genus of ascomycetous fungi of the family Schizosaccharomycetaceae, order Schizosaccharomycetales.Chromosomes, Plant: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of PLANTS.Schizosaccharomyces pombe Proteins: Proteins obtained from the species Schizosaccharomyces pombe. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.Chromosomes, Human, Pair 7: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Saccharomyces cerevisiae Proteins: Proteins obtained from the species SACCHAROMYCES CEREVISIAE. The function of specific proteins from this organism are the subject of intense scientific interest and have been used to derive basic understanding of the functioning similar proteins in higher eukaryotes.Chromosome Deletion: Actual loss of portion of a chromosome.Chromosomes, Human, Pair 11: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 17: A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.Mad2 Proteins: Mad2 is a component of the spindle-assembly checkpoint apparatus. It binds to and inhibits the Cdc20 activator subunit of the anaphase-promoting complex, preventing the onset of anaphase until all chromosomes are properly aligned at the metaphase plate. Mad2 is required for proper microtubule capture at KINETOCHORES.Chromosomes, Mammalian: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of MAMMALS.Saccharomyces cerevisiae: A species of the genus SACCHAROMYCES, family Saccharomycetaceae, order Saccharomycetales, known as "baker's" or "brewer's" yeast. The dried form is used as a dietary supplement.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Chromosomes, Human, Pair 6: A specific pair GROUP C CHROMSOMES of the human chromosome classification.Chromosomes, Human, Pair 21: A specific pair of GROUP G CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 9: A specific pair of GROUP C CHROMSOMES of the human chromosome classification.In Situ Hybridization, Fluorescence: A type of IN SITU HYBRIDIZATION in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei.Nuclear Proteins: Proteins found in the nucleus of a cell. Do not confuse with NUCLEOPROTEINS which are proteins conjugated with nucleic acids, that are not necessarily present in the nucleus.M Phase Cell Cycle Checkpoints: The cellular signaling system that halts the progression of cells through MITOSIS or MEIOSIS if a defect that will affect CHROMOSOME SEGREGATION is detected.Recombination, Genetic: Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.Chromosomes, Human, 6-12 and X: The medium-sized, submetacentric human chromosomes, called group C in the human chromosome classification. This group consists of chromosome pairs 6, 7, 8, 9, 10, 11, and 12 and the X chromosome.Protein-Serine-Threonine Kinases: A group of enzymes that catalyzes the phosphorylation of serine or threonine residues in proteins, with ATP or other nucleotides as phosphate donors.Chromosomal Instability: An increased tendency to acquire CHROMOSOME ABERRATIONS when various processes involved in chromosome replication, repair, or segregation are dysfunctional.Centrosome: The cell center, consisting of a pair of CENTRIOLES surrounded by a cloud of amorphous material called the pericentriolar region. During interphase, the centrosome nucleates microtubule outgrowth. The centrosome duplicates and, during mitosis, separates to form the two poles of the mitotic spindle (MITOTIC SPINDLE APPARATUS).Separase: Separase is a caspase-like cysteine protease, which plays a central role in triggering ANAPHASE by cleaving the SCC1/RAD21 subunit of the cohesin complex. Cohesin holds the sister CHROMATIDS together during METAPHASE and its cleavage results in chromosome segregation.Microtubule-Associated Proteins: High molecular weight proteins found in the MICROTUBULES of the cytoskeletal system. Under certain conditions they are required for TUBULIN assembly into the microtubules and stabilize the assembled microtubules.Chromosomes, Human, Pair 13: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 22: A specific pair of GROUP G CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 2: A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.Cytokinesis: The process by which the CYTOPLASM of a cell is divided.Chromosomes, Human, Pair 16: A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.Karyotyping: Mapping of the KARYOTYPE of a cell.Chromosome Positioning: The mechanisms of eukaryotic CELLS that place or keep the CHROMOSOMES in a particular SUBNUCLEAR SPACE.Kinesin: A microtubule-associated mechanical adenosine triphosphatase, that uses the energy of ATP hydrolysis to move organelles along microtubules toward the plus end of the microtubule. The protein is found in squid axoplasm, optic lobes, and in bovine brain. Bovine kinesin is a heterotetramer composed of two heavy (120 kDa) and two light (62 kDa) chains. EC 3.6.1.-.Chromosomes, Human, Pair 10: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 4: A specific pair of GROUP B CHROMOSOMES of the human chromosome classification.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Chromosomes, Human, Y: The human male sex chromosome, being the differential sex chromosome carried by half the male gametes and none of the female gametes in humans.Genetic Linkage: The co-inheritance of two or more non-allelic GENES due to their being located more or less closely on the same CHROMOSOME.Chromosome Structures: Structures which are contained in or part of CHROMOSOMES.Chromosomes, Human, Pair 8: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 19: A specific pair of GROUP F CHROMOSOMES of the human chromosome classification.Chromosome Disorders: Clinical conditions caused by an abnormal chromosome constitution in which there is extra or missing chromosome material (either a whole chromosome or a chromosome segment). (from Thompson et al., Genetics in Medicine, 5th ed, p429)Prophase: The first phase of cell nucleus division, in which the CHROMOSOMES become visible, the CELL NUCLEUS starts to lose its identity, the SPINDLE APPARATUS appears, and the CENTRIOLES migrate toward opposite poles.Chromosomes, Human, X: The human female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in humans.Chromosomes, Human, 1-3: The large, metacentric human chromosomes, called group A in the human chromosome classification. This group consists of chromosome pairs 1, 2, and 3.Chromosomes, Artificial, Bacterial: DNA constructs that are composed of, at least, a REPLICATION ORIGIN, for successful replication, propagation to and maintenance as an extra chromosome in bacteria. In addition, they can carry large amounts (about 200 kilobases) of other sequence for a variety of bioengineering purposes.Chromosome Painting: A technique for visualizing CHROMOSOME ABERRATIONS using fluorescently labeled DNA probes which are hybridized to chromosomal DNA. Multiple fluorochromes may be attached to the probes. Upon hybridization, this produces a multicolored, or painted, effect with a unique color at each site of hybridization. This technique may also be used to identify cross-species homology by labeling probes from one species for hybridization with chromosomes from another species.Chromosomes, Human, Pair 5: One of the two pairs of human chromosomes in the group B class (CHROMOSOMES, HUMAN, 4-5).Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Chromosomes, Human, Pair 12: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Genetic Markers: A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.Fungal Proteins: Proteins found in any species of fungus.Chromosomes, Human, Pair 15: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Chromosomes, Human, Pair 14: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.Prometaphase: The phase of cell nucleus division following PROPHASE, when the breakdown of the NUCLEAR ENVELOPE occurs and the MITOTIC SPINDLE APPARATUS enters the nuclear region and attaches to the KINETOCHORES.Cell Cycle: The complex series of phenomena, occurring between the end of one CELL DIVISION and the end of the next, by which cellular material is duplicated and then divided between two daughter cells. The cell cycle includes INTERPHASE, which includes G0 PHASE; G1 PHASE; S PHASE; and G2 PHASE, and CELL DIVISION PHASE.Chromosomes, Human, Pair 18: A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.DNA-Binding Proteins: Proteins which bind to DNA. The family includes proteins which bind to both double- and single-stranded DNA and also includes specific DNA binding proteins in serum which can be used as markers for malignant diseases.Multiprotein Complexes: Macromolecular complexes formed from the association of defined protein subunits.Chromosomes, Human, 13-15: The medium-sized, acrocentric human chromosomes, called group D in the human chromosome classification. This group consists of chromosome pairs 13, 14, and 15.Chromosomes, Human, Pair 20: A specific pair of GROUP F CHROMOSOMES of the human chromosome classification.Chromosomes, Artificial, Yeast: Chromosomes in which fragments of exogenous DNA ranging in length up to several hundred kilobase pairs have been cloned into yeast through ligation to vector sequences. These artificial chromosomes are used extensively in molecular biology for the construction of comprehensive genomic libraries of higher organisms.Chromosomes, Insect: Structures within the CELL NUCLEUS of insect cells containing DNA.Chromosomes, Human, 16-18: The short, submetacentric human chromosomes, called group E in the human chromosome classification. This group consists of chromosome pairs 16, 17, and 18.Sister Chromatid Exchange: An exchange of segments between the sister chromatids of a chromosome, either between the sister chromatids of a meiotic tetrad or between the sister chromatids of a duplicated somatic chromosome. Its frequency is increased by ultraviolet and ionizing radiation and other mutagenic agents and is particularly high in BLOOM SYNDROME.DNA Replication: The process by which a DNA molecule is duplicated.Crosses, Genetic: Deliberate breeding of two different individuals that results in offspring that carry part of the genetic material of each parent. The parent organisms must be genetically compatible and may be from different varieties or closely related species.Models, Genetic: Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Chromosome Breakage: A type of chromosomal aberration involving DNA BREAKS. Chromosome breakage can result in CHROMOSOMAL TRANSLOCATION; CHROMOSOME INVERSION; or SEQUENCE DELETION.Chromatin: The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Histones: Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each.HeLa Cells: The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.Chromosomes, Human, 21-22 and Y: The short, acrocentric human chromosomes, called group G in the human chromosome classification. This group consists of chromosome pairs 21 and 22 and the Y chromosome.Chromosome Inversion: An aberration in which a chromosomal segment is deleted and reinserted in the same place but turned 180 degrees from its original orientation, so that the gene sequence for the segment is reversed with respect to that of the rest of the chromosome.Translocation, Genetic: A type of chromosome aberration characterized by CHROMOSOME BREAKAGE and transfer of the broken-off portion to another location, often to a different chromosome.DNA, Fungal: Deoxyribonucleic acid that makes up the genetic material of fungi.Cell Nucleus Division: The process by which the CELL NUCLEUS is divided.Meiotic Prophase I: The prophase of the first division of MEIOSIS (in which homologous CHROMOSOME SEGREGATION occurs). It is divided into five stages: leptonema, zygonema, PACHYNEMA, diplonema, and diakinesis.RNA Interference: A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.Genes, Fungal: The functional hereditary units of FUNGI.Crossing Over, Genetic: The reciprocal exchange of segments at corresponding positions along pairs of homologous CHROMOSOMES by symmetrical breakage and crosswise rejoining forming cross-over sites (HOLLIDAY JUNCTIONS) that are resolved during CHROMOSOME SEGREGATION. Crossing-over typically occurs during MEIOSIS but it may also occur in the absence of meiosis, for example, with bacterial chromosomes, organelle chromosomes, or somatic cell nuclear chromosomes.Drosophila melanogaster: A species of fruit fly much used in genetics because of the large size of its chromosomes.Ring Chromosomes: Aberrant chromosomes with no ends, i.e., circular.Securin: Securin is involved in the control of the metaphase-anaphase transition during MITOSIS. It promotes the onset of anaphase by blocking SEPARASE function and preventing proteolysis of cohesin and separation of sister CHROMATIDS. Overexpression of securin is associated with NEOPLASTIC CELL TRANSFORMATION and tumor formation.Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Chromosomes, Human, 4-5: The large, submetacentric human chromosomes, called group B in the human chromosome classification. This group consists of chromosome pairs 4 and 5.Caenorhabditis elegans: A species of nematode that is widely used in biological, biochemical, and genetic studies.Adenosine Triphosphatases: A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.Gene Deletion: A genetic rearrangement through loss of segments of DNA or RNA, bringing sequences which are normally separated into close proximity. This deletion may be detected using cytogenetic techniques and can also be inferred from the phenotype, indicating a deletion at one specific locus.Spermatocytes: Male germ cells derived from SPERMATOGONIA. The euploid primary spermatocytes undergo MEIOSIS and give rise to the haploid secondary spermatocytes which in turn give rise to SPERMATIDS.Cell Nucleus: Within a eukaryotic cell, a membrane-limited body which contains chromosomes and one or more nucleoli (CELL NUCLEOLUS). The nuclear membrane consists of a double unit-type membrane which is perforated by a number of pores; the outermost membrane is continuous with the ENDOPLASMIC RETICULUM. A cell may contain more than one nucleus. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Hybrid Cells: Any cell, other than a ZYGOTE, that contains elements (such as NUCLEI and CYTOPLASM) from two or more different cells, usually produced by artificial CELL FUSION.Cell Division: The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.Polyploidy: The chromosomal constitution of a cell containing multiples of the normal number of CHROMOSOMES; includes triploidy (symbol: 3N), tetraploidy (symbol: 4N), etc.Pedigree: The record of descent or ancestry, particularly of a particular condition or trait, indicating individual family members, their relationships, and their status with respect to the trait or condition.Synaptonemal Complex: The three-part structure of ribbon-like proteinaceous material that serves to align and join the paired homologous CHROMOSOMES. It is formed during the ZYGOTENE STAGE of the first meiotic division. It is a prerequisite for CROSSING OVER.Drosophila Proteins: Proteins that originate from insect species belonging to the genus DROSOPHILA. The proteins from the most intensely studied species of Drosophila, DROSOPHILA MELANOGASTER, are the subject of much interest in the area of MORPHOGENESIS and development.DNA Topoisomerases, Type II: DNA TOPOISOMERASES that catalyze ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. These enzymes bring about relaxation of the supercoiled DNA and resolution of a knotted circular DNA duplex.Cdc20 Proteins: Highly conserved proteins that specifically bind to and activate the anaphase-promoting complex-cyclosome, promoting ubiquitination and proteolysis of cell-cycle-regulatory proteins. Cdc20 is essential for anaphase-promoting complex activity, initiation of anaphase, and cyclin proteolysis during mitosis.Telomere: A terminal section of a chromosome which has a specialized structure and which is involved in chromosomal replication and stability. Its length is believed to be a few hundred base pairs.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Caenorhabditis elegans Proteins: Proteins from the nematode species CAENORHABDITIS ELEGANS. The proteins from this species are the subject of scientific interest in the area of multicellular organism MORPHOGENESIS.Genomic Instability: An increased tendency of the GENOME to acquire MUTATIONS when various processes involved in maintaining and replicating the genome are dysfunctional.Ubiquitin-Protein Ligase Complexes: Complexes of enzymes that catalyze the covalent attachment of UBIQUITIN to other proteins by forming a peptide bond between the C-terminal GLYCINE of UBIQUITIN and the alpha-amino groups of LYSINE residues in the protein. The complexes play an important role in mediating the selective-degradation of short-lived and abnormal proteins. The complex of enzymes can be broken down into three components that involve activation of ubiquitin (UBIQUITIN-ACTIVATING ENZYMES), conjugation of ubiquitin to the ligase complex (UBIQUITIN-CONJUGATING ENZYMES), and ligation of ubiquitin to the substrate protein (UBIQUITIN-PROTEIN LIGASES).Nocodazole: Nocodazole is an antineoplastic agent which exerts its effect by depolymerizing microtubules.Potoroidae: A family of rat kangaroos found in and around Australia. Genera include Potorous and Bettongia.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Ploidies: The degree of replication of the chromosome set in the karyotype.Genes, Lethal: Genes whose loss of function or gain of function MUTATION leads to the death of the carrier prior to maturity. They may be essential genes (GENES, ESSENTIAL) required for viability, or genes which cause a block of function of an essential gene at a time when the essential gene function is required for viability.Thiabendazole: 2-Substituted benzimidazole first introduced in 1962. It is active against a variety of nematodes and is the drug of choice for STRONGYLOIDIASIS. It has CENTRAL NERVOUS SYSTEM side effects and hepatototoxic potential. (From Smith and Reynard, Textbook of Pharmacology, 1992, p919)Saccharomycetales: An order of fungi in the phylum Ascomycota that multiply by budding. They include the telomorphic ascomycetous yeasts which are found in a very wide range of habitats.Tubulin: A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from SPERM FLAGELLUM; CILIA; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120,000 and a sedimentation coefficient of 5.8S. It binds to COLCHICINE; VINCRISTINE; and VINBLASTINE.DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).X Chromosome Inactivation: A dosage compensation process occurring at an early embryonic stage in mammalian development whereby, at random, one X CHROMOSOME of the pair is repressed in the somatic cells of females.Plasmids: Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.Drosophila: A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.Anaphase-Promoting Complex-Cyclosome: An E3 ubiquitin ligase primarily involved in regulation of the metaphase-to-anaphase transition during MITOSIS through ubiquitination of specific CELL CYCLE PROTEINS. Enzyme activity is tightly regulated through subunits and cofactors, which modulate activation, inhibition, and substrate specificity. The anaphase-promoting complex, or APC-C, is also involved in tissue differentiation in the PLACENTA, CRYSTALLINE LENS, and SKELETAL MUSCLE, and in regulation of postmitotic NEURONAL PLASTICITY and excitability.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Oocytes: Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.DNA, Catenated: CIRCULAR DNA that is interlaced together as links in a chain. It is used as an assay for the activity of DNA TOPOISOMERASES. Catenated DNA is attached loop to loop in contrast to CONCATENATED DNA which is attached end to end.Aurora Kinase A: An aurora kinase that localizes to the CENTROSOME during MITOSIS and is involved in centrosome regulation and formation of the MITOTIC SPINDLE. Aurora A overexpression in many malignant tumor types suggests that it may be directly involved in NEOPLASTIC CELL TRANSFORMATION.Heterochromatin: The portion of chromosome material that remains condensed and is transcriptionally inactive during INTERPHASE.Spores, Fungal: Reproductive bodies produced by fungi.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Caulobacter: A genus of gram-negative, aerobic, rod- or vibroid-shaped or fusiform bacteria that commonly produce a stalk. They are found in fresh water and soil and divide by binary transverse fission.Chromosomes, Human, 19-20: The short, metacentric human chromosomes, called group F in the human chromosome classification. This group consists of chromosome pairs 19 and 20.Replication Origin: A unique DNA sequence of a replicon at which DNA REPLICATION is initiated and proceeds bidirectionally or unidirectionally. It contains the sites where the first separation of the complementary strands occurs, a primer RNA is synthesized, and the switch from primer RNA to DNA synthesis takes place. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)Interphase: The interval between two successive CELL DIVISIONS during which the CHROMOSOMES are not individually distinguishable. It is composed of the G phases (G1 PHASE; G0 PHASE; G2 PHASE) and S PHASE (when DNA replication occurs).Genes, cdc: Genes that code for proteins that regulate the CELL DIVISION CYCLE. These genes form a regulatory network that culminates in the onset of MITOSIS by activating the p34cdc2 protein (PROTEIN P34CDC2).Bacterial Proteins: Proteins found in any species of bacterium.Diploidy: The chromosomal constitution of cells, in which each type of CHROMOSOME is represented twice. Symbol: 2N or 2X.Pachytene Stage: The stage in the first meiotic prophase, following ZYGOTENE STAGE, when CROSSING OVER between homologous CHROMOSOMES begins.Aurora Kinase C: Aurora kinase C is a chromosomal passenger protein that interacts with aurora kinase B in the regulation of MITOSIS. It is found primarily in GERM CELLS in the TESTIS, and may mediate CHROMOSOME SEGREGATION during SPERMATOGENESIS.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.DNA Breaks, Double-Stranded: Interruptions in the sugar-phosphate backbone of DNA, across both strands adjacently.Heterozygote: An individual having different alleles at one or more loci regarding a specific character.Microsatellite Repeats: A variety of simple repeat sequences that are distributed throughout the GENOME. They are characterized by a short repeat unit of 2-8 basepairs that is repeated up to 100 times. They are also known as short tandem repeats (STRs).Lod Score: The total relative probability, expressed on a logarithmic scale, that a linkage relationship exists among selected loci. Lod is an acronym for "logarithmic odds."Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Microtubule-Organizing Center: An amorphous region of electron dense material in the cytoplasm from which the MICROTUBULES polymerization is nucleated. The pericentriolar region of the CENTROSOME which surrounds the CENTRIOLES is an example.Dyneins: A family of multisubunit cytoskeletal motor proteins that use the energy of ATP hydrolysis to power a variety of cellular functions. Dyneins fall into two major classes based upon structural and functional criteria.Polar Bodies: Minute cells produced during development of an OOCYTE as it undergoes MEIOSIS. A polar body contains one of the nuclei derived from the first or second meiotic CELL DIVISION. Polar bodies have practically no CYTOPLASM. They are eventually discarded by the oocyte. (from King & Stansfield, A Dictionary of Genetics, 4th ed)Centromere Protein B: A DNA-binding protein that interacts with a 17-base pair sequence known as the CENP-B box motif. The protein is localized constitutively to the CENTROMERE and plays an important role in its maintenance.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Caulobacter crescentus: A species of gram-negative, aerobic bacteria that consist of slender vibroid cells.Genes, Dominant: Genes that influence the PHENOTYPE both in the homozygous and the heterozygous state.Phosphorylation: The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.CDC2 Protein Kinase: Phosphoprotein with protein kinase activity that functions in the G2/M phase transition of the CELL CYCLE. It is the catalytic subunit of the MATURATION-PROMOTING FACTOR and complexes with both CYCLIN A and CYCLIN B in mammalian cells. The maximal activity of cyclin-dependent kinase 1 is achieved when it is fully dephosphorylated.DNA, Satellite: Highly repetitive DNA sequences found in HETEROCHROMATIN, mainly near centromeres. They are composed of simple sequences (very short) (see MINISATELLITE REPEATS) repeated in tandem many times to form large blocks of sequence. Additionally, following the accumulation of mutations, these blocks of repeats have been repeated in tandem themselves. The degree of repetition is on the order of 1000 to 10 million at each locus. Loci are few, usually one or two per chromosome. They were called satellites since in density gradients, they often sediment as distinct, satellite bands separate from the bulk of genomic DNA owing to a distinct BASE COMPOSITION.Gene Expression Regulation, Fungal: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in fungi.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.Protein Kinases: A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.Brachiaria: A plant genus of the family POACEAE originating from the savanna of eastern Africa. It is widely grown for livestock forage.Repressor Proteins: Proteins which maintain the transcriptional quiescence of specific GENES or OPERONS. Classical repressor proteins are DNA-binding proteins that are normally bound to the OPERATOR REGION of an operon, or the ENHANCER SEQUENCES of a gene until a signal occurs that causes their release.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Escherichia coli Proteins: Proteins obtained from ESCHERICHIA COLI.Cyclin B: A cyclin subtype that is transported into the CELL NUCLEUS at the end of the G2 PHASE. It stimulates the G2/M phase transition by activating CDC2 PROTEIN KINASE.Genes, Insect: The functional hereditary units of INSECTS.DNA, Cruciform: A cross-shaped DNA structure that can be observed under the electron microscope. It is formed by the incomplete exchange of strands between two double-stranded helices or by complementary INVERTED REPEAT SEQUENCES that refold into hairpin loops on opposite strands across from each other.Cell Nucleolus: Within most types of eukaryotic CELL NUCLEUS, a distinct region, not delimited by a membrane, in which some species of rRNA (RNA, RIBOSOMAL) are synthesized and assembled into ribonucleoprotein subunits of ribosomes. In the nucleolus rRNA is transcribed from a nucleolar organizer, i.e., a group of tandemly repeated chromosomal genes which encode rRNA and which are transcribed by RNA polymerase I. (Singleton & Sainsbury, Dictionary of Microbiology & Molecular Biology, 2d ed)Embryo, Nonmammalian: The developmental entity of a fertilized egg (ZYGOTE) in animal species other than MAMMALS. For chickens, use CHICK EMBRYO.DNA Helicases: Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. In addition DNA helicases are DNA-dependent ATPases that harness the free energy of ATP hydrolysis to translocate DNA strands.Suppression, Genetic: Mutation process that restores the wild-type PHENOTYPE in an organism possessing a mutationally altered GENOTYPE. The second "suppressor" mutation may be on a different gene, on the same gene but located at a distance from the site of the primary mutation, or in extrachromosomal genes (EXTRACHROMOSOMAL INHERITANCE).Repetitive Sequences, Nucleic Acid: Sequences of DNA or RNA that occur in multiple copies. There are several types: INTERSPERSED REPETITIVE SEQUENCES are copies of transposable elements (DNA TRANSPOSABLE ELEMENTS or RETROELEMENTS) dispersed throughout the genome. TERMINAL REPEAT SEQUENCES flank both ends of another sequence, for example, the long terminal repeats (LTRs) on RETROVIRUSES. Variations may be direct repeats, those occurring in the same direction, or inverted repeats, those opposite to each other in direction. TANDEM REPEAT SEQUENCES are copies which lie adjacent to each other, direct or inverted (INVERTED REPEAT SEQUENCES).Hypertelorism: Abnormal increase in the interorbital distance due to overdevelopment of the lesser wings of the sphenoid.Recombinases: A broad category of enzymes that are involved in the process of GENETIC RECOMBINATION.

Mutations at phosphorylation sites of Xenopus microtubule-associated protein 4 affect its microtubule-binding ability and chromosome movement during mitosis. (1/2093)

Microtubule-associated proteins (MAPs) bind to and stabilize microtubules (MTs) both in vitro and in vivo and are thought to regulate MT dynamics during the cell cycle. It is known that p220, a major MAP of Xenopus, is phosphorylated by p34(cdc2) kinase as well as MAP kinase in mitotic cells, and that the phosphorylated p220 loses its MT-binding and -stabilizing abilities in vitro. We cloned a full-length cDNA encoding p220, which identified p220 as a Xenopus homologue of MAP4 (XMAP4). To examine the physiological relevance of XMAP4 phosphorylation in vivo, Xenopus A6 cells were transfected with cDNAs encoding wild-type or various XMAP4 mutants fused with a green fluorescent protein. Mutations of serine and threonine residues at p34(cdc2) kinase-specific phosphorylation sites to alanine interfered with mitosis-associated reduction in MT affinity of XMAP4, and their overexpression affected chromosome movement during anaphase A. These findings indicated that phosphorylation of XMAP4 (probably by p34(cdc2) kinase) is responsible for the decrease in its MT-binding and -stabilizing abilities during mitosis, which are important for chromosome movement during anaphase A.  (+info)

Gene knockouts reveal separate functions for two cytoplasmic dyneins in Tetrahymena thermophila. (2/2093)

In many organisms, there are multiple isoforms of cytoplasmic dynein heavy chains, and division of labor among the isoforms would provide a mechanism to regulate dynein function. The targeted disruption of somatic genes in Tetrahymena thermophila presents the opportunity to determine the contributions of individual dynein isoforms in a single cell that expresses multiple dynein heavy chain genes. Substantial portions of two Tetrahymena cytoplasmic dynein heavy chain genes were cloned, and their motor domains were sequenced. Tetrahymena DYH1 encodes the ubiquitous cytoplasmic dynein Dyh1, and DYH2 encodes a second cytoplasmic dynein isoform, Dyh2. The disruption of DYH1, but not DYH2, resulted in cells with two detectable defects: 1) phagocytic activity was inhibited, and 2) the cells failed to distribute their chromosomes correctly during micronuclear mitosis. In contrast, the disruption of DYH2 resulted in a loss of regulation of cell size and cell shape and in the apparent inability of the cells to repair their cortical cytoskeletons. We conclude that the two dyneins perform separate tasks in Tetrahymena.  (+info)

Regulation of Saccharomyces cerevisiae kinetochores by the type 1 phosphatase Glc7p. (3/2093)

We have investigated the role of protein phosphorylation in regulation of Saccharomyces cerevisiae kinetochores. By use of phosphatase inhibitors and a type 1 protein phosphatase mutant (glc7-10), we show that the microtubule binding activity, but not the centromeric DNA-binding activity, of the kinetochore complex is regulated by a balance between a protein kinase and the type 1 protein phosphatase (PP1) encoded by the GLC7 gene. glc7-10 mutant cells exhibit low kinetochore-microtubule binding activity in vitro and a high frequency of chromosome loss in vivo. Specifically, the Ndc10p component of the centromere DNA-binding CBF3 complex is altered by the glc7-10 mutation; Ndc10p is hyperphosphorylated in glc7-10 extracts. Furthermore, addition of recombinant Ndc10p reconstitutes the microtubule-binding activity of a glc7-10 extract to wild-type levels. Finally, the glc7-10-induced mitotic arrest is abolished in spindle checkpoint mutants, suggesting that defects in kinetochore-microtubule interactions caused by hyperphosphorylation of kinetochore proteins activate the spindle checkpoint.  (+info)

Genetic linkage of IgA deficiency to the major histocompatibility complex: evidence for allele segregation distortion, parent-of-origin penetrance differences, and the role of anti-IgA antibodies in disease predisposition. (4/2093)

Immunoglobulin A (IgA) deficiency (IgAD) is characterized by a defect of terminal lymphocyte differentiation, leading to a lack of IgA in serum and mucosal secretions. Familial clustering, variable population prevalence in different ethnic groups, and a predominant inheritance pattern suggest a strong genetic predisposition to IgAD. The genetic susceptibility to IgAD is shared with a less prevalent, but more profound, defect called "common variable immunodeficiency" (CVID). Here we show an increased allele sharing at 6p21 in affected members of 83 multiplex IgAD/CVID pedigrees and demonstrate, using transmission/diseqilibrium tests, family-based associations indicating the presence of a predisposing locus, designated "IGAD1," in the proximal part of the major histocompatibility complex (MHC). The recurrence risk of IgAD was found to depend on the sex of parents transmitting the defect: affected mothers were more likely to produce offspring with IgAD than were affected fathers. Carrier mothers but not carrier fathers transmitted IGAD1 alleles more frequently to the affected offspring than would be expected under random segregation. The differential parent-of-origin penetrance is proposed to reflect a maternal effect mediated by the production of anti-IgA antibodies tentatively linked to IGAD1. This is supported by higher frequency of anti-IgA-positive females transmitting the disorder to children, in comparison with female IgAD nontransmitters, and by linkage data in the former group. Such pathogenic mechanisms may be shared by other MHC-linked complex traits associated with the production of specific autoantibodies, parental effects, and a particular MHC haplotype.  (+info)

Comparisons of genomic structures and chromosomal locations of the mouse aldose reductase and aldose reductase-like genes. (5/2093)

Aldose reductase (AR), best known as the first enzyme in the polyol pathway of sugar metabolism, has been implicated in a wide variety of physiological functions and in the etiology of diabetic complications. We have determined the structures and chromosomal locations of the mouse AR gene (Aldor1) and of two genes highly homologous to Aldor1: the fibroblast growth factor regulated protein gene (Fgfrp) and the androgen regulated vas deferens protein gene (Avdp). The number of introns and their locations in the mouse Aldor1 gene are identical to those of rat and human AR genes and also to those of Fgfrp and Avdp. Mouse Aldor1 gene was found to be located near the Cald1 (Caldesmon) and Ptn (Pleiotropin) loci at the proximal end of chromosome 6. The closely related genes Fgfrp and Avdp were also mapped in this region of the chromosome, suggesting that these three genes may have arisen by a gene duplication event.  (+info)

Transchromosomal mouse embryonic stem cell lines and chimeric mice that contain freely segregating segments of human chromosome 21. (6/2093)

At least 8% of all human conceptions have major chromosome abnormalities and the frequency of chromosomal syndromes in newborns is >0.5%. Despite these disorders making a large contribution to human morbidity and mortality, we have little understanding of their aetiology and little molecular data on the importance of gene dosage to mammalian cells. Trisomy 21, which results in Down syndrome (DS), is the most frequent aneuploidy in humans (1 in 600 live births, up to 1 in 150 pregnancies world-wide) and is the most common known genetic cause of mental retardation. To investigate the molecular genetics of DS, we report here the creation of mice that carry different human chromosome 21 (Hsa21) fragments as a freely segregating extra chromosome. To produce these 'transchromosomal' animals, we placed a selectable marker into Hsa21 and transferred the chromosome from a human somatic cell line into mouse embryonic stem (ES) cells using irradiation microcell-mediated chromosome transfer (XMMCT). 'Transchromosomal' ES cells containing different Hsa21 regions ranging in size from approximately 50 to approximately 0.2 Mb have been used to create chimeric mice. These mice maintain Hsa21 sequences and express Hsa21 genes in multiple tissues. This novel use of the XMMCT protocol is applicable to investigations requiring the transfer of large chromosomal regions into ES or other cells and, in particular, the modelling of DS and other human aneuploidy syndromes.  (+info)

Centrosome amplification and a defective G2-M cell cycle checkpoint induce genetic instability in BRCA1 exon 11 isoform-deficient cells. (7/2093)

Germline mutations of the Brca1 tumor suppressor gene predispose women to breast and ovarian cancers. To study mechanisms underlying BRCA1-related tumorigenesis, we derived mouse embryonic fibroblast cells carrying a targeted deletion of exon 11 of the Brca1 gene. We show that the mutant cells maintain an intact G1-S cell cycle checkpoint and proliferate poorly. However, a defective G2-M checkpoint in these cells is accompanied by extensive chromosomal abnormalities. Mutant fibroblasts contain multiple, functional centrosomes, which lead to unequal chromosome segregation, abnormal nuclear division, and aneuploidy. These data uncover an essential role of BRCA1 in maintaining genetic stability through the regulation of centrosome duplication and the G2-M checkpoint and provide a molecular basis for the role of BRCA1 in tumorigenesis.  (+info)

Phosphorylation of histone H3 is required for proper chromosome condensation and segregation. (8/2093)

Phosphorylation of histone H3 at serine 10 occurs during mitosis in diverse eukaryotes and correlates closely with mitotic and meiotic chromosome condensation. To better understand the function of H3 phosphorylation in vivo, we created strains of Tetrahymena in which a mutant H3 gene (S10A) was the only gene encoding the major H3 protein. Although both micronuclei and macronuclei contain H3 in typical nucleosomal structures, defects in nuclear divisions were restricted to mitotically dividing micronuclei; macronuclei, which are amitotic, showed no defects. Strains lacking phosphorylated H3 showed abnormal chromosome segregation, resulting in extensive chromosome loss during mitosis. During meiosis, micronuclei underwent abnormal chromosome condensation and failed to faithfully transmit chromosomes. These results demonstrate that H3 serine 10 phosphorylation is causally linked to chromosome condensation and segregation in vivo and is required for proper chromosome dynamics.  (+info)

*Spindle apparatus

... aligning chromosomes at the cell equator and poising them for segregation to daughter cells. Once every chromosome is bi- ... The precise orientation of this complex is required to ensure accurate chromosome segregation and to specify the cell division ... Maresca TJ, Freedman BS, Heald R (2005). "Histone H1 is essential for mitotic chromosome architecture and segregation in ... a process that produces gametes with half the number of chromosomes of the parent cell. Besides chromosomes, the spindle ...

*Homologous chromosome

There are severe repercussions when chromosomes do not segregate properly. Faulty segregation can lead to fertility problems, ... The additional 23rd pair is the sex chromosomes, X and Y. If this pair is made up of an X and Y chromosome, then the pair of ... It reduces the chromosome number in a germ cell by half by first separating the homologous chromosomes in meiosis I and then ... Homologous chromosomes are chromosomes which contain the same genes in the same order along their chromosomal arms. There are ...

*Aurora B kinase

... metaphase chromosome alignment, kinetochore disjunction, and chromosome segregation". The Journal of Cell Biology. 153 (4): 865 ... The Aurora kinases associate with microtubules during chromosome movement and segregation. Aurora kinase B localizes to ... is required for progression to anaphase I and segregation of homologous chromosomes. In mitotic vertebrate B lymphocytes, the ... "Depletion of centromeric MCAK leads to chromosome congression and segregation defects due to improper kinetochore attachments ...

*Chromosome segregation

After the first chromosome segregation in meiosis I is complete, there is further chromosome segregation during the second ... Both proper initial segregation of chromosomes in prophase I and the next chromosome segregation during equational division in ... Improper chromosome segregation can result in aneuploid gametes having either too few or too many chromosomes. The second stage ... This segregation process occurs during both mitosis and meiosis. During mitosis chromosome segregation occurs routinely as a ...

*Mitosis

In late anaphase, chromosomes also reach their overall maximal condensation level, to help chromosome segregation and the re- ... In this stage, chromosomes are long, thin and thread-like. Each chromosome has two chromatids. The two chromatids are joined at ... Draviam VM, Xie S, Sorger PK (April 2004). "Chromosome segregation and genomic stability". Current Opinion in Genetics & ... Santaguida, Stefano; Amon, Angelika (2015-08-01). "Short- and long-term effects of chromosome mis-segregation and aneuploidy". ...

*Chromatin bridge

Jallepalli PV, Lengauer C (2001). "Chromosome segregation and cancer: cutting through the mystery". Nature Reviews Cancer. 1 (2 ... As previously stated, the disruptions in the chromosome may lead to single chromosome mutations, including deletion, ... a process that ensures that replicated chromosomes are intact before chromosomes are segregated during cell division. In ... This occurs because loss of these genes causes an increase in chromosome fusions, either in an end-to-end manner or through ...

*ParABS system

Murray, H; Ferreira, H; Errington, J (Sep 2006). "The bacterial chromosome segregation protein Spo0J spreads along DNA from ... the parABS system is a broadly conserved molecular mechanism for plasmid partitioning and chromosome segregation in bacteria. ... "A spindle-like apparatus guides bacterial chromosome segregation". Nature Cell Biology. 12 (8): 791-8. doi:10.1038/ncb2083. PMC ... Surtees, JA; Funnell, BE (2003). "Plasmid and chromosome traffic control: how ParA and ParB drive partition". Current topics in ...

*Frank Uhlmann

"Frank Uhlmann: Mechanism and control of chromosome segregation". The Crick Institute. Archived from the original on 2015-05-24 ... Nasmyth, K; Peters, J. M.; Uhlmann, F (2000). "Splitting the chromosome: Cutting the ties that bind sister chromatids". Science ... "A simple biophysical model emulates budding yeast chromosome condensation". eLife. 4. doi:10.7554/eLife.05565. PMC 4413874 . ...

*Chromatin remodeling

... chromosome segregation as well as development and pluripotency. Aberrations in chromatin remodeling proteins are found to be ... DNA repair and chromosome segregation, and therefore exerts tumor-suppressor function. Mutations in such chromatin remodelers ... including chromosome assembly and segregation, DNA replication and repair, embryonic development and pluripotency, and cell- ... Loss of heterozygosity in coding region of p300 (chromosome 22q13) is present in large number of glioblastomas. Further, HATs ...

*Aneugen

Chromosome segregation Clastogen Non-disjunction Plante, N. (2003). Molecular toxicology. Taylor & Francis. pp. 63-65. ISBN 978 ... Exposure to fenvalerate raised sex chromosome disomy 1.9-fold and disomy of chromosome 18 by 2.6-fold (Xia et al., 2004). ... and also increased sex chromosome disomy by 1.7-fold and chromosome 18 disomy by 2.2-fold. Humans are exposed to perfluorinated ... An aneugen is a substance that causes a daughter cell to have an abnormal number of chromosomes or aneuploidy. A substance's ...

*ORC6

Prasanth SG, Prasanth KV, Stillman B (2002). "Orc6 involved in DNA replication, chromosome segregation, and cytokinesis". ... interfering RNA demonstrated that this protein plays an essential role in coordinating chromosome replication and segregation ...

*Molecular motor

Dworkin J, Losick R (October 2002). "Does RNA polymerase help drive chromosome segregation in bacteria?". Proc. Natl. Acad. Sci ... SMC proteins responsible for chromosome condensation in eukaryotic cells. Viral DNA packaging motors inject viral genomic DNA ... Peterson C (1994). "The SMC family: novel motor proteins for chromosome condensation?". Cell. 79 (3): 389-92. doi:10.1016/0092- ...

*BUB1

Klebig C, Korinth D, Meraldi P (Jun 2009). "Bub1 regulates chromosome segregation in a kinetochore-independent manner". The ... "PP2A is required for centromeric localization of Sgo1 and proper chromosome segregation". Developmental Cell. 10 (5): 575-85. ... The protein is bound to kinetochores and plays a key role in the establishment of the mitotic spindle checkpoint and chromosome ... The protein kinase Bub1 possesses versatile and distinct functions during the cell cycle, mainly in the SAC and chromosome ...

*Cdc14

... the segregation of chromosomes continue and both the phases of meiotic segregations take place on prolonged meiosis I spindle. ... "The Cdc14 phosphatase and the FEAR network control meiotic spindle disassembly and chromosome segregation". Developmental Cell ... "Stabilization of microtubule dynamics at anaphase onset promotes chromosome segregation". Nature. 433: 171-176. doi:10.1038/ ... The chromosomes also segregate abnormally. The abnormality arises due to delay in dissembling of spindle during Anaphase I. ...

*Single-cell DNA template strand sequencing

Falconer, Ester; Lansdorp, Peter M. (August 2013). "Strand-seq: A unifying tool for studies of chromosome segregation". ... Pulse-chase experiments have been used for determining the segregation patterns of chromosomes in addition to studying other ... aneuploid chromosomes and modes of sister chromatid segregation. It can also aid in assembling early-build genomes and ... "The Majority of Multipotent Epidermal Stem Cells Do Not Protect Their Genome by Asymmetrical Chromosome Segregation". Stem ...

*Sic1

Then the metaphase spindle assembles and chromosome segregation can occur. The transcription of Sic1 starts during telophase, ...

*KIF2C

This protein acts to regulate microtubule dynamics in cells and is important for anaphase chromosome segregation and may be ... "Mitotic Centromere-associated Kinesin Is Important for Anaphase Chromosome Segregation". J. Cell Biol. 142 (3): 787-801. doi: ... proteins of this family are microtubule-dependent molecular motors that transport organelles within cells and move chromosomes ...

*Iron response element

"Deregulated human Cdc14A phosphatase disrupts centrosome separation and chromosome segregation". Nature Cell Biology. 4 (4): ...

*Wilms' tumor

"Defective Chromosome Segregation and Telomere Dysfunction in Aggressive Wilms' Tumors". Clinical Cancer Research. 13 (22): 6593 ... A gene on the X chromosome, WTX, is inactivated in up to 30% of Wilms tumor cases, according to research published in 2007. ... Tumor-specific loss-of-heterozygosity (LOH) for chromosomes 1p and 16q identifies a subset of Wilms tumor patients who have a ... "An X Chromosome Gene, WTX, is Commonly Inactivated in Wilms Tumor". Science. 315 (5812): 642-5. Bibcode:2007Sci...315..642R. ...

*Shugoshin N terminal protein domain

Macy B, Wang M, Yu HG (2009). "The many faces of shugoshin, the "guardian spirit," in chromosome segregation". Cell Cycle. 8 (1 ... Shugoshin is a crucial target of Bub1 kinase that plays a central role in the cohesion of chromosomes during cell division. The ... Just as its name suggests, the Shugoshin protein guides chromosome cohesion during cell division. It does this by preventing ... and it degrades when they separate preventing cell cycle arrest and chromosome loss.Human shugoshin is diffusible and mediates ...

*BUB1B

This gene encodes a kinase involved in spindle checkpoint function and chromosome segregation. The protein has been localized ... "A role for the Adenomatous Polyposis Coli protein in chromosome segregation". Nat. Cell Biol. 3 (4): 429-32. doi:10.1038/ ... delaying the onset of anaphase and ensuring proper chromosome segregation. Impaired spindle checkpoint function has been found ... Guo Y, Kim C, Ahmad S, Zhang J, Mao Y (July 2012). "CENP-E--dependent BubR1 autophosphorylation enhances chromosome alignment ...

*EZH2

During cell division, heterochromatin formation is required for proper chromosome segregation. PRC2/EED-EZH2 complex may also ... X-chromosome inactivation and transcriptional regulation. In mammalian chromosomes, histone lysine methylation can either ... H3K27me3 is also important in driving X-inactivation, the silencing of one X-chromosome in females during development. During X ...

*BUB3

... serves in oocyte meiosis as the regulator of chromosome segregation. Defects in BUB3 in the cell cycle can contribute to ... 2001). "A role for the Adenomatous Polyposis Coli protein in chromosome segregation". Nat. Cell Biol. 3 (4): 429-32. doi: ... "Bub3 Is a Spindle Assembly Checkpoint Protein Regulating Chromosome Segregation during Mouse Oocyte Meiosis". PLoS ONE. 4 (11 ... For correct segregation of the cells it is necessary for all mitotic spindles to attach correctly to the kinetochore of each ...

*CDC14A

Kaiser BK, Zimmerman ZA, Charbonneau H, Jackson PK (2003). "Disruption of centrosome structure, chromosome segregation, and ... 2002). "Deregulated human Cdc14A phosphatase disrupts centrosome separation and chromosome segregation". Nat. Cell Biol. 4 (4 ...

*Adenomatous polyposis coli

"A role for the Adenomatous Polyposis Coli protein in chromosome segregation". Nature Cell Biology. 3 (4): 429-32. doi:10.1038/ ... The human APC gene is located on the long (q) arm of chromosome 5 in band q22.2 (5q22.2). The APC gene has been shown to ... This protein also helps ensure that the chromosome number in cells produced through cell division is correct. The APC protein ... Mutations in APC lead to loss of β-catenin regulation, altered cell migration and chromosome instability[citation needed]. ...

*Mitochondrial DNA

The genome of the mitochondrion of the cucumber (Cucumis sativus) consists of three circular chromosomes (lengths 1556, 84 and ... "mtDNA Segregation in Heteroplasmic Tissues Is Common In Vivo and Modulated by Haplotype Differences and Developmental Stage". ... Segregation of the Leaked Paternal mtDNA Followed by the Prevention of Subsequent Paternal Leakage". Genetics. 148 (2): 851-57 ... "A reduction of mitochondrial DNA molecules during embryogenesis explains the rapid segregation of genotypes". Nature Genetics. ...

*NDC80

This surveillance mechanism assures correct segregation of chromosomes during cell division by detecting unaligned chromosomes ... Zheng L, Chen Y, Riley DJ, Chen PL, Lee WH (May 2000). "Retinoblastoma protein enhances the fidelity of chromosome segregation ... Zheng L, Chen Y, Lee WH (Aug 1999). "Hec1p, an evolutionarily conserved coiled-coil protein, modulates chromosome segregation ... "Phosphorylation of the mitotic regulator protein Hec1 by Nek2 kinase is essential for faithful chromosome segregation". The ...
In the pre-implantation embryo, aneuploidy resulting from chromosome segregation error is considered responsible for pregnancy loss. However, only a few studies have examined the relationship between chromosome segregation errors during early cleavage and development. Here, we evaluated this relationship by live-cell imaging using the histone H2B-mCherry probe and subsequent single blastocyst transfer using mouse embryos obtained by in vitro fertilization. We showed that some embryos exhibiting early chromosomal segregation error and formation of micronuclei retained their developmental potential; however, the error affected the blastocyst/arrest ratio. Further, single-cell sequencing after live-cell imaging revealed that all embryos exhibiting micronuclei formation during 1st mitosis showed aneuploidy at the 2-cell stage. These results suggest that early chromosome segregation error causing micronuclei formation affects ploidy and development to blastocyst but does not necessarily cause developmental
Errors in chromosome segregation occurring during human oogenesis and early embryogenesis are very common. Meiotic chromosome development during oogenesis is subdivided into three distinct phases. The crucial events, including meiotic chromosome pairing and recombination, take place from around 11 weeks until birth. Oogenesis is then arrested until ovulation, when the first meiotic division takes place, with the second meiotic division not completed until after fertilization. It is generally accepted that most aneuploid fetal conditions, such as trisomy 21 Down syndrome, are due to maternal chromosome segregation errors. The underlying reasons are not yet fully understood. It is also clear that superimposed on the maternal meiotic chromosome segregation errors, there are a large number of mitotic errors taking place post-zygotically during the first few cell divisions in the embryo. In this chapter, we summarise current knowledge of errors in chromosome segregation during oogenesis and early ...
程金妹.,李建.,汤济鑫.,郝晓霞.,王志鹏.,...&刘以训.(2017).Merotelic Kinetochore Attachment in Oocyte Meiosis II Causes Sister Chromatids Segregation Errors in Aged Mice.Cell Cycle,16(15),1404-1413 ...
Many cancers display both structural (s-CIN) and numerical (w-CIN) chromosomal instabilities. Defective chromosome segregation during mitosis has been shown to cause DNA damage that induces structural rearrangements of chromosomes (s-CIN). In contrast, whether DNA damage can disrupt mitotic processes to generate whole chromosomal instability (w-CIN) is unknown. Here we show that activation of the DNA damage response (DDR) during mitosis selectively stabilizes kinetochore-microtubule (k-MT) attachments to chromosomes through Aurora-A and Plk1 kinases, thereby increasing the frequency of lagging chromosomes during anaphase. Inhibition of DDR proteins, ATM or Chk2, abolishes the effect of DNA damage on k-MTs and chromosome segregation, whereas activation of the DDR in the absence of DNA damage is sufficient to induce chromosome segregation errors. Finally, inhibiting the DDR during mitosis in cancer cells with persistent DNA damage suppresses inherent chromosome segregation defects. Thus, DDR ...
Aneuploidy is poorly tolerated by cells and can have catastrophic consequences, including infertility and death, for offspring. Normally, chromosomes partner during meiosis in such a way as to guarantee their correct segregation into daughter cells and prevent aneuploidy. If their connections to one another and to the spindle network are improperly regulated, however, cells can have missing or extra chromosomes as a result. In some species, nonhomologous chromosomes that have no pairing partners in meiosis can have coordinated movements and behaviors that result in their correct delivery into daughter cells. We are interested in how chromosome movements are coordinated to ensure correct chromosome segregation into daughter cells during meiosis. To study this, we look at these strange cases of chromosome segregation, as they could reveal a lot about the coordination of chromosome movements in all species.
Studies of chromosome organization in bacterial cells show that the chromosome is an exquisitely organized and dynamic structure (reviewed recently in Thanbichler et al., 2005). Chromosome segregation in bacteria does not occur all at once but in sequential phases (Lau et al., 2003; Viollier et al., 2004; Bates and Kleckner, 2005; Nielsen et al., 2006). After replication at mid-cell, the origin region (oriC) is rapidly segregated outward. The speed at which this occurs (reviewed in Gordon and Wright, 2000) rules out passive models for bacterial chromosome segregation, which proposed that outward cellular growth could drive the movement of a fixed chromosome. As the loci of the chromosome are replicated, they are moved outward to the poles in a sequential fashion (Lau et al., 2003; Viollier et al., 2004; Bates and Kleckner, 2005; Nielsen et al., 2006). In Escherichia coli, there may be a period of sister chromosome cohesion between duplication and subsequent segregation, although its length is ...
The improper partitioning of chromosomes is responsible for a many human maladies. Errors in mitotic chromosome segregation contribute to the development of cancer while errors in meiosis are the leading cause of birth defects and infertility. Proper chromosome segregation requires the co-ordination of chromosome behavior with other cellular events, and the assembly of a functional machine to move the chromosomes to the right place at the right time in the cell cycle. The research in our laboratory is focused on both the regulatory and mechanical aspects of chromosome behavior. Our projects primarily use the yeast, Saccharomyces cerevisiae, as a model to elucidate conserved aspects of eukaryotic chromosome biology. Our goal is to elucidate fundamentals of chromosome behavior that will provide insights into the origins of chromosome segregation errors in humans.. Our laboratory is involved in two major projects. Slk19 is a bi-functional protein. Slk19 is a member of the FEAR signaling pathway ...
Mitotic chromosome malsegregation produces aneuploidy and genome instability. An increasing number of studies have shown that abnormalities such as aneuploidy and whole-chromosome loss of heterozygosity are commonly present in tumor cells. This suggests that chromosome instability and aneuploidy may play a critical role in tumor development and progression ( Sen, 2000).. The integrity of the cell and of its genome and the correct accomplishment of cellular processes depend on the existence of control points in the cell cycle. These control mechanisms, called `checkpoints, inhibit the transition to the next cell cycle phase if the events of the previous phase have not been correctly executed. A mitotic checkpoint has been identified that controls the metaphase to anaphase transition. A large number of studies have demonstrated that in vertebrates the kinetochore plays an active role in the mitotic checkpoint pathway and that microtubule accumulation at the kinetochore and/or tension that ...
Research done in Prof. Sharon Bickels lab has demonstrated that oxidative damage causes a premature loss of sister chromatid cohesion and an increase in chromosome segregation errors in Drosophila oocytes during meiosis. In women, the probability of miscarriage or Down Syndrome increases dramatically with age. Studies of maternal age effect indicate that errors in female meiosis contribute significantly to this age-related effect. The research done by the Bickel lab demonstrates that if oxidative damage contributes to maternal age effect then reducing oxidative damage could be a strategy for reducing chromosome segregation errors during meiosis.. Professor Sharon Bickel, MCB graduate student Adrienne Perkins, Class of 2013 undergraduate researcher Thomas Das and second year MCB graduate student Lauren Panzera contributed to this work. These findings were published in the Proceeding of the National Academy of Sciences: http://www.pnas.org/content/early/2016/10/12/1612047113.full ...
Author Summary Proper chromosome segregation is essential for normal cell proliferation. Segregation errors lead to aneuploidy, a direct cause of birth defects and a hallmark of cancer. The kinetochore (centromeric DNA and associated proteins) is one of the key determinants for faithful chromosome transmission. Misregulation of kinetochore proteins such as HJURP has been observed in various cancers, however the biological relevance of this observation is not well understood. We determined that altered dosage of HJURP and its budding yeast homolog SCM3 leads to defects in chromosome segregation in yeast and human cells. We identified the centromeric DNA-interacting domain of Scm3p and determined that association of Scm3p devoid of Cse4p leads to chromosome segregation defects. Our findings suggest that stringent regulation of Scm3p/HJURP, Cse4p, and histone H4 is critical for maintenance of genome stability.
Cells possessing the incorrect number of chromosomes (referred to as aneuploid) can arise as a result of chromosome mis-segregation. Prevention of aneuploidy is especially important in germ cells, as these cells pass genetic information to the next generation, but also in pluripotent cells as these give rise to all tissues and cells of the offspring, including germ cells. Aneuploid conceptions have a detrimental effect on pregnancy outcomes, are surprisingly common in humans (estimated 10-30%), and are a leading cause of miscarriage and developmental disorders. In both meiosis and mitosis, accurate chromosome segregation relies on the correct orientation of sister chromatids during metaphase, which ensures bipolar spindle attachment. Newly replicated sister chromatids are able to align properly on the spindle due to cohesion holding them together. The protein complex responsible for sister chromatid cohesion (SCC) is called cohesin, and has specific subunits depending on its particular role. The ...
Errors in meiotic chromosome segregation are the leading cause of spontaneous abortions and birth defects. In humans, chromosomes that fail to experience crossovers (or exchanges..
Chromosome segregation and cell division are essential, highly ordered processes that depend on numerous protein complexes. Results from recent RNA interference screens indicate that the identity and composition of these protein complexes is incompletely understood. Using gene tagging on bacterial artificial chromosomes, protein localization, and tandem-affinity purification-mass spectrometry, the MitoCheck consortium has analyzed about 100 human protein complexes, many of which had not or had only incompletely been characterized. This work has led to the discovery of previously unknown, evolutionarily conserved subunits of the anaphase-promoting complex and the gamma-tubulin ring complex--large complexes that are essential for spindle assembly and chromosome segregation. The approaches we describe here are generally applicable to high-throughput follow-up analyses of phenotypic screens in mammalian cells ...
Chromosomal instability (CIN) is a major trait of cancer cells and a potent driver of tumor progression. However, the molecular mechanisms underlying CIN still remain elusive. We found that a number of CIN+ cell lines have impairments in the integrity of the conserved inner centromere-shugoshin (ICS) network, which coordinates sister chromatid cohesion and kinetochore-microtubule attachment. These defects are caused mostly by the loss of histone H3 lysine 9 trimethylation at centromeres and sometimes by a reduction in chromatin-associated cohesin; both pathways separately sustain centromeric shugoshin stability. Artificial restoration of the ICS network suppresses chromosome segregation errors in a wide range of CIN+ cells, including RB- and BRCA1-deficient cells. Thus, dysfunction of the ICS network might be a key mechanism underlying CIN in human tumorigenesis. ...
Our data are consistent with a positive role of SDS22 for PP1 at the kinetochore and its function in antagonizing Aurora B, which has been established before in yeast and mammalian cells (Peggie et al, 2002; Pedelini et al, 2007; Bharucha et al, 2008; Posch et al, 2010; Wurzenberger et al, 2012). We confirm that SDS22 depletion leads to increased Aurora B activity at the kinetochore accompanied by chromosome segregation defects, which is consistent with compromised PP1 function. In addition, we demonstrate that PP1 in fact directly dephosphorylates T232 of Aurora B.. However, our findings speak against a direct role of SDS22 that would involve quantitative localization of SDS22 at the kinetochore, for example a function as a substrate adapter or even as a recruitment factor of PP1 to the kinetochore as proposed before (Posch et al, 2010). Using the SDS22‐GFP reporter at near endogenous levels, we do not detect SDS22 at the kinetochore, nor do we detect any loss of PP1 from the kinetochore upon ...
Many cancers have extremely high rates of chromosomal instability (CIN). Some cancers have chromosome segregation errors in every cell division, which would be detrimental to the growth of normal cells. Little is known about how cancers are able to thrive with high levels of CIN. We aim to determine how cells evolve to cope with CIN by creating a model system for persistent chromosomal instability in budding yeast. What types of mutations allow cells to adapt to a constantly shifting genomic content? What are the direct effects of CIN and aneuploidy on the health and viability of cells?. ...
The research interests of the participating groups are listed below. Follow the links for more detailed information.. Gustav Ammerer: Signal transduction and transcriptional regulation in yeast. Oliver Bell: Editing the epigenome: plasticity and memory of chromatin structure. Frederic Berger: Histone variants in chromatin structure. Christopher Campbell: Chromosome dynamics. Alexander Dammermann: Centriole assembly and function. Daniel Gerlich: Cytoskeletal and membrane dynamics in cell division. Juraj Gregan: Chromosome segregation during mitosis and meiosis. Verena Jantsch-Plunger: Faithful chromosome segregation in C. elegans meiosis. Franz Klein: Deconstructing the meiotic (yeast) chromosome. Josef Loidl: Meiotic chromosome pairing and recombination. Ortrun Mittelsten Scheid: Epigenetic changes in plants ...
Control of sister chromatid cohesion/separation is critical to ensure faithful chromosome segregation during mitosis and meiosis. Failures in this mechanism during mitosis often lead to aneuploidy and chromosome instability, a major cause of cancer, while failures during meiosis promote miscarriage, birth defects, and infertility in humans. A key protagonist in this control is the cohesin complex, which are composed essentially by four subunits, two of them, called Smc1 and Smc3 (Structural maintenance of chromosomes), are members of a highly conserved protein family also found in prokaryotes and are implicated in various functions related to DNA dynamics, dose compensation, chromosome condensation, recombination, etc. The other two subunits are specific to eukaryotes and, depending on the organism, are termed Scc1/Rad21 or Scc3/STAG, the former mainly for yeast and the latter in higher eukaryotes. In addition to their function in chromatid cohesion during chromosome segregation, our previous ...
DNA replication, transcription, repair, epigenetic inheritance, and chromosome segregation are all processes critical for maintaining cellular viability. In euk...
Rho GTPases are overexpressed and hyperactivated in many cancers, including breast cancer. Rho proteins, as well as their regulators and effectors, have been implicated in mitosis, and their altered expression promotes mitotic defects and aneuploidy. Previously, we demonstrated that p190B Rho GTPase activating protein (RhoGAP) deficiency inhibits ErbB2-induced mammary tumor formation in mice. Here we describe a novel role for p190B as a regulator of mitosis. We found that p190B localized to centrosomes during interphase and mitosis, and that it is differentially phosphorylated during mitosis. Knockdown of p190B expression in MCF-7 and Hela cells increased the incidence of aberrant microtubule-kinetochore attachments at metaphase, lagging chromosomes at anaphase, and micronucleation, all of which are indicative of aneuploidy. Cell cycle analysis of p190B deficient MCF-7 cells revealed a significant increase in apoptotic cells with a concomitant decrease in cells in G1 and S phase, suggesting that p190B
Results: We show that the SMC4 subunit of condensin is encoded by the essential gluon locus in Drosophila. DmSMC4 contains all the conserved domains present in other members of the structural-maintenance-of-chromosomes protein family. DmSMC4 is both nuclear and cytoplasmic during interphase, concentrates on chromatin during prophase, and localizes to the axial chromosome core at metaphase and anaphase. During decondensation in telophase, most of the DmSMC4 leaves the chromosomes. An examination of gluon mutations indicates that SMC4 is required for chromosome condensation and segregation during different developmental stages. A detailed analysis of mitotic chromosome structure in mutant cells indicates that although the longitudinal axis can be shortened normally, sister chromatid resolution is strikingly disrupted. This phenotype then leads to severe chromosome segregation defects, chromosome breakage, and apoptosis ...
Journal of Cell Science is pleased to be a part of the new and exciting Review Commons initiative, launched by EMBO and ASAPbio. Streamlining the publishing process, Review Commons enables high-quality peer review to take place before journal submission. Papers submitted to Review Commons will be assessed independently of any journal, focusing solely on the papers scientific rigor and merit.. ...
Mutations in CDCA7 and HELLS that respectively encode a CXXC-type zinc finger protein and an SNF2 family chromatin remodeler cause immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome types 3 and 4. Here, we demonstrate that the classical nonhomologous end joining (C-NHEJ) proteins Ku80 and Ku70, as well as HELLS, coimmunoprecipitated with CDCA7. The coimmunoprecipitation of the repair proteins was sensitive to nuclease treatment and an ICF3 mutation in CDCA7 that impairs its chromatin binding. The functional importance of these interactions was strongly suggested by the compromised C-NHEJ activity and significant delay in Ku80 accumulation at DNA damage sites in CDCA7- and HELLS-deficient HEK293 cells. Consistent with the repair defect, these cells displayed increased apoptosis, abnormal chromosome segregation, aneuploidy, centrosome amplification, and significant accumulation of γH2AX signals. Although less prominent, cells with mutations in the other ICF genes ...
Mutations in CDCA7 and HELLS that respectively encode a CXXC-type zinc finger protein and an SNF2 family chromatin remodeler cause immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome types 3 and 4. Here, we demonstrate that the classical nonhomologous end joining (C-NHEJ) proteins Ku80 and Ku70, as well as HELLS, coimmunoprecipitated with CDCA7. The coimmunoprecipitation of the repair proteins was sensitive to nuclease treatment and an ICF3 mutation in CDCA7 that impairs its chromatin binding. The functional importance of these interactions was strongly suggested by the compromised C-NHEJ activity and significant delay in Ku80 accumulation at DNA damage sites in CDCA7- and HELLS-deficient HEK293 cells. Consistent with the repair defect, these cells displayed increased apoptosis, abnormal chromosome segregation, aneuploidy, centrosome amplification, and significant accumulation of γH2AX signals. Although less prominent, cells with mutations in the other ICF genes ...
Mutations in CDCA7 and HELLS that respectively encode a CXXC-type zinc finger protein and an SNF2 family chromatin remodeler cause immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome types 3 and 4. Here, we demonstrate that the classical nonhomologous end joining (C-NHEJ) proteins Ku80 and Ku70, as well as HELLS, coimmunoprecipitated with CDCA7. The coimmunoprecipitation of the repair proteins was sensitive to nuclease treatment and an ICF3 mutation in CDCA7 that impairs its chromatin binding. The functional importance of these interactions was strongly suggested by the compromised C-NHEJ activity and significant delay in Ku80 accumulation at DNA damage sites in CDCA7- and HELLS-deficient HEK293 cells. Consistent with the repair defect, these cells displayed increased apoptosis, abnormal chromosome segregation, aneuploidy, centrosome amplification, and significant accumulation of γH2AX signals. Although less prominent, cells with mutations in the other ICF genes ...
If you have a question about this talk, please contact Ross Waller.. Host: Mark Carrington. Abstract not available. This talk is part of the Parasitology Seminars series.. ...
An intricate network of proteins ensures the faithful transmission of genetic information through cell generations. The Structural Maintenance of Chromosomes (SMC) protein complex family plays a pivotal role in maintaining genome stability. Initially, the three eukaryotic SMC complexes, cohesin, condensin and Smc5/6 complex (Smc5/6) were identified for their functions in chromosome cohesion, condensation and recombination. Later, it was shown that SMC complexes also control replication and transcription. Another important group of proteins involved in the maintenance of genome stability are the topoisomerases. These enzymes control DNA topology to ensure faithful replication, transcription and chromosome segregation ...
Michael Goldberg is a Professor in the Department of Molecular Biology and Genetics. Dr. Goldberg is a member of the Graduate Field of Genetics, Genomics and Development and the Graduate Field of Biochemistry, Molecular, and Cell Biology. The Goldberg lab studies the molecular mechanisms which ensure accurate chromosome segregation and other chromosome behaviors.
NIMA in A. nidulans has known functions in G2-M checkpoint control, as does at least one of its mammalian orthologs, Nek2. Nek2 phosphorylates the kinetochore-associated mitotic regulator protein Hec1 and is therefore crucial for faithful chromosome segregation to daughter cells (13) . Our data suggest that Nek1 may be important for sensing, responding to, or repairing DNA damage and thereby for regulating apoptosis and cellular proliferation after injury. When Nek1 is mutated or when its up-regulation is otherwise insufficient, cells are more likely to die aberrantly or fail to proliferate when they normally should. Some cells surviving the insult would also be more likely to pass subtle mutations on to their daughters, which could then accumulate activating oncogenic or inactivating tumor suppressor mutations. Up-regulation of Nek1 may be a defensive response to cellular and DNA injury, a response to prevent excessive or unscheduled apoptosis. If so, we predict that Nek1 might be overexpressed ...
(PhysOrg.com) -- The effort to classify life into various groups has been a bumpy ride. Prior to the 1900s, living things were usually pegged as either plants or animals – period. By the middle of the 20th century, ...
Classical simulations are described of the fully relaxed surface lattice structures of the five lowest-index planes of α-Al20 3 and the resulting crystal morphology. The surface coverage by yttrium and magnesium as a function of temperature is evaluated on the basis of a non-Arrhenius isotherm and calculated heats of surface segregation. The calculated morphology, surface coverages and heats of segregation are compared with experiment. A quantum simulation of a relaxed {0001} surface is presented and the surface structure and energy compared with the classical results. Estimates are made of the adsorption energy of HF at the {0001} surface. ...
Diagnostic screening allows medical practitioners to identify diseases caused by defective chromosomes, genes or proteins. This screening can occur pre-natally (before birth), pre-symptomatically (before symptoms develop) or be used to confirm a suspected diagnosis. ...
Self-Placing Concrete segregation set of tests - Béton Auto-Plaçant ensemble dessais de ségrégation (). The Forney Column Segregation Test Set contains everything needed to determine the potential segregation of coarse aggregate in SCC mixtures tes
Most people have a passing knowledge of the food they eat, and perhaps how it gets digested. As with all human body systems, however, details of the digestive or gastrointestinal (GI) tract-including the incredibly rich microbial flora found at the last portion of the small intestine and the entire large intestine-are an amazing testimony to creation.. Indeed, on a given day the bacterial population within the human colon usually doubles at least once. This means the common Escherichia coli (E. coli) must replicate (duplicate) its circular chromosome in just 20 short minutes.. The replication of millions of base pairs of DNA is a daunting task in such a small area. The E. coli chromosome must spin at the equivalent of 300 revolutions per second as it makes a second chromosome for upcoming cell division.. A host of unique and diverse bacteria inhabit the large intestine-over 400 bacterial species-and most of them are anaerobic (living in the absence of free oxygen) and are concerned with the ...
The road to modern segregation has been a long one. Theres been 350 years of segregation in our country that was perpetuated by the government as well as
Hutchins JR, Toyoda Y, Hegemann B, Poser I, Hériché JK, Sykora MM, Augsburg M, Hudecz O, Buschhorn BA, Bulkescher J, Conrad C, Comartin D, Schleiffer A, Sarov M, Pozniakovsky A, Slabicki MM, Schloissnig S, Steinmacher I, Leuschner M, Ssykor A, Lawo S, Pelletier L, Stark H, Nasmyth K, Ellenberg J, Durbin R, Buchholz F, Mechtler K, Hyman AA, Peters JM. (2010). Systematic analysis of human protein complexes identifies chromosome segregation proteins. Science 328(5978):593-599. doi: 10.1126/science. ...
Segregation in a cross between strains carrying a transposed segment.In this example, two haploid parental strains harbor a particular genomic region (black) on
The Axon framework is a Java implementation of the Command and Query Responsibility Segregation. InfoQ talked with its creator, Allard Buijze, to find out more.
Errors in chromosome segregation in mammalian oocytes lead to aneuploid eggs that are developmentally compromised. In mitotic cells, mitotic centromere associated kinesin (MCAK; KIF2C) prevents chromosome segregation errors by detaching incorrect microtubule-kinetochore interactions. Here, we examine whether MCAK is involved in spindle function in mouse oocyte meiosis I, and whether MCAK is necessary to prevent chromosome segregation errors. We find that MCAK is recruited to centromeres, kinetochores and chromosome arms in mid-meiosis I, and that MCAK depletion, or inhibition using a dominant-negative construct, causes chromosome misalignment. However, the majority of oocytes complete meiosis I and the resulting eggs retain the correct number of chromosomes. Moreover, MCAK-depleted oocytes can recover from mono-orientation of homologous kinetochores in mid-meiosis I to segregate chromosomes correctly. Thus, MCAK contributes to chromosome alignment in meiosis I, but is not necessary for ...
Heterochromatin protein 1 is associated with centromeric heterochromatin in Drosophila, mice, and humans. Loss of function mutations in the gene encoding heterochromatin protein 1 in Drosophila, Suppressor of variegation2-5, decrease the mosaic repression observed for euchromatic genes that have been juxtaposed to centromeric heterochromatin. These heterochromatin protein 1 mutations not only suppress this position-effect variegation, but also cause recessive embryonic lethality. In this study, we analyze the latter phenotype in the hope of gaining insight into heterochromatin function. In our analyses of four alleles of Suppressor of variegation2-5, the lethality was found to be associated with defects in chromosome morphology and segregation. While some of these defects are seen throughout embryonic development, both the frequency and severity of the defects are greatest between cycles 10 and 14 when zygotic transcription of the Suppressor of variegation2-5 gene apparently begins. By this time ...
Lagging chromosomes during anaphase are an easily assayed and therefore commonly reported mitotic defect. However, in most cases, the mechanisms that give rise to lagging chromosomes are unknown. Lagging chromosomes can be caused by asbestos fibers (Hersterberg and Barrett, 1985), elevated ras p21 expression (Hagag et al., 1990), carcinogens such as diethylstilbestrol (Schiffmann and De Boni, 1991), and inherited genetic conditions such as Roberts syndrome (Jabs et al., 1991). Chromosomes, chromatids, and chromosome fragments that do not segregate properly often end up spatially separated from the bulk of the chromosomes and will reform a separate nuclear envelope after mitosis is completed. This results in a cell containing micronuclei. Sometimes these cells are described as multinucleate. Severe chromosome segregation defects will in turn inhibit cytokinesis giving rise to truly multinucleate cells (Schultz and Onfelt, 1994). The mechanism by which these diverse agents disrupt anaphase ...
The microtubule-based mitotic spindle segregates chromosomes during cell division. During chromosome segregation, the centromeric regions of chromosomes build kinetochores that establish end-coupled attachments to spindle microtubules. Here, we used the Caenorhabditis elegans embryo as a model system to examine the crosstalk between two kinetochore protein complexes implicated in temporally distinct stages of attachment formation. The kinetochore dynein module, which mediates initial lateral microtubule capture, inhibited microtubule binding by the Ndc80 complex, which ultimately forms the end-coupled attachments that segregate chromosomes. The kinetochore dynein module directly regulated Ndc80, independently of phosphorylation by Aurora B kinase, and this regulation was required for accurate segregation. Thus, the conversion from initial dynein-mediated, lateral attachments to correctly oriented, Ndc80-mediated end-coupled attachments is actively controlled. ...
Accurate segregation of meiotic chromosomes requires that sister-chromatids remain physically associated from the time of their synthesis during S phase until they segregate toward opposite poles at anaphase II. In Drosophila melanogaster meiosis, physical association of sister chromatids, known as sister-chromatid cohesion, requires the protein product of the orientation disruptor (ord) gene. Genetic and cytological analyses of ord mutants indicate that sister chromatids separate precociously in the absence of ORD activity, resulting in random chromosome segregation during both meiotic divisions. To understand the molecular basis of ORD activity more fully, we localized ORD protein in Drosophila spermatocytes using immunofluorescence and demonstrate that ORD associates with centromeres of meiotic chromosomes from early G2 through anaphase II. Maintenance of ORD at centromeres until anaphase II requires functional MEI-S332 protein, as centromeric ORD signal disappears during anaphase I in ...
The IPL1 gene is required for high-fidelity chromosome segregation in the budding yeast Saccharomyces cerevisiae. Conditional ipl1ts mutants missegregate chromosomes severely at 37 degrees C. Here, we report that IPL1 encodes an essential putative protein kinase whose function is required during the later part of each cell cycle. At 26 degrees C, the permissive growth temperature, ipl1 mutant cells are defective in the recovery from a transient G2/M-phase arrest caused by the antimicrotubule drug nocodazole. In an effort to identify additional gene products that participate with the Ipl1 protein kinase in regulating chromosome segregation in yeast, a truncated version of the previously identified DIS2S1/GLC7 gene was isolated as a dosage-dependent suppressor of ipl1ts mutations. DIS2S1/GLC7 is predicted to encode a catalytic subunit (PP1C) of type 1 protein phosphatase. Overexpression of the full-length DIS2S1/GLC7 gene results in chromosome missegregation in wild-type cells and exacerbates the ...
Mitosis is a key event in the life of a cell, where duplicated chromosomes are separated into the daughter cells. Defects associated with chromosome segregation can lead to aneuploidy, a hallmark of cancer. Chromosome segregation is achieved by the mitotic spindle, which is composed of microtubules (MTs), motors and microtubule associated protein (MAPs). Motors such as kinesins generate forces within the spindle while MAPs perform functions such as organize the spindle pole and maintain the bipolar spindle. Both motors and MAPs contribute to spindle mechanics. Here I used the relatively simple fission yeast to address how defects in spindle mechanics affect chromosome segregation. The metaphase spindle is maintained at a constant length by an antagonistic force-balance model yet how the regulation of metaphase spindle length contribute to subsequent chromosome segregation remains unexplored. To test the force-balance model, I applied gene deletion and fast microfluidic temperature-control with live-cell
Lack of KLP38B function leads to a variety of mitotic defects, including aneuploid and polyploid cells, asymmetric metaphase and anaphase figures with abnormal arrangements of chromatin, and a high frequency of CMFs resembling the array of monooriented chromosomes around monopoles in newt lung cells (5) and several other Drosophila mitotic mutants (18, 19, 22, 46). Cells where chromosomes remain in a circular array around a single centrosomal mass (as in Fig. 2 C) would be unlikely to undergo cytokinesis, contributing to the observed high incidence of true polyploids. Ohkura et al. also observed elevated frequencies of 4N and 8N cells in KLP38B mutants, which they attributed to failure of cytokinesis (36). However, Ohkura et al. did not observe the variety of other mitotic defects found in our study, perhaps because they characterized two hypomorphic alleles, whereas strong loss of function or null alleles were included in our study. We propose that KLP38B protein bound to condensed chromatin ...
Sister chromatid cohesion, which is established during the S phase of the eukaryotic cell cycle and persists until the onset of anaphase, is essential for the maintenance of genomic integrity. Cohesion requires the multi-protein complex cohesin, as well as a number of accessory proteins including Pds5/BIMD/Spo76. In the budding yeast Saccharomyces cerevisiae Pds5 is an essential protein that localises to chromosomes in a cohesin-dependent manner. Here we describe the characterisation in the fission yeast Schizosaccharomyces pombe of pds5(+), a novel, non-essential orthologue of S. cerevisiae PDS5. The S. pombe Pds5 protein was localised to punctate nuclear foci in a manner that was dependent on the Rad21 cohesin component. This, together with additional genetic evidence, points towards an involvement of S. pombe Pds5 in sister chromatid cohesion. S. pombe pds5 mutants were hypersensitive to DNA damage and to mitotic metaphase delay, but this sensitivity was apparently not due to precocious loss of
Accurate chromosome segregation in mitosis is required to maintain genetic stability. hZwint-1 [human Zw10 (Zeste white 10)-interacting protein 1] is a kinetochore protein known to interact with the kinetochore checkpoint protein hZw10. hZw10, along with its partners Rod (Roughdeal) and hZwilch, form a complex which recruits dynein-dynactin and Mad1-Mad2 complexes to the kinetochore and are essential components of the mitotic checkpoint. hZwint-1 localizes to the kinetochore in prophase, before hZw10 localization, and remains at the kinetochore until anaphase, after hZw10 has dissociated. This difference in localization timing may reflect a role for hZwint-1 as a structural kinetochore protein. In addition to hZw10, we have found that hZwint-1 interacts with components of the conserved Ndc80 and Mis12 complexes in yeast two-hybrid and GST (glutathione transferase) pull-down assays. Furthermore, hZwint-1 was found to have stable FRAP (fluorescence recovery after photobleaching) dynamics similar ...
In humans, early embryo development is a complex process that consists of sequential events: oocyte maturation, fertilization, embryonic growth and implantation. Disruption of these highly regulated processes results in reproductive failure and infertility. This study characterizes and describes embryonic aneuploidy, mitochondrial content level and endometrial microbial environment related to reproductive competence, in particular instances in which failure results. To examine the molecular underpinnings of mammalian gamete and early embryo chromosome segregation, we established a comprehensive chromosomal screening (CCS) method for mice poly bodies, oocytes and embryos by the application of whole genome amplification (WGA) and next generation sequencing (NGS). First, we validated this approach using single mouse embryonic fibroblasts engineered to have stable trisomy 16. We further validated this method by identifying reciprocal chromosome segregation errors in the products of meiosis I (gamete and
Looking for chromosome congression? Find out information about chromosome congression. congression Explanation of chromosome congression
It will be capable of destabilising defective non-bipolar attachments and as this kind of functions as an errorcorrection component that assures faithful segregation of sister chromatids. Merotelic chromosome attachments Merotely is surely an attachment state during which a single kinetochore attaches to microtubules from each poles. Merotelic attachments happen usually in early mitosis and when left uncorrected they induce anaphase lagging chromosomes and may lead to aneuploidy . The vast majority of merotelic attachments are resolved in prometaphase and latest scientific studies identified a serious function for Aurora-B in this correction operation. Aurora-B gets enriched at centromeres of merotelically attached kinetochores wherever it promotes kinetochoremicrotubule turnover more than likely via regulation of MCAK. Aurora-B influences the function of MCAK at several amounts. To start with, Aurora-B action is needed for your concentration of MCAK on centromeres ...
Neoplastic cells are genetically unstable. Strategies that target pathways affecting genome instability can be exploited to disrupt tumor cell growth potentially with limited consequences to normal cells. Chromosomal instability (CIN) is one type of genome instability characterized by mitotic defects that increase the rate of chromosome mis-segregation. CIN is frequently caused by extra centrosomes that transiently disrupt normal bipolar spindle geometry needed for accurate chromosome segregation. Tumor cells survive with extra centrosomes because of biochemical pathways that cluster centrosomes and promote chromosome segregation on bipolar spindles. Recent work shows that targeted inhibition of these pathways prevents centrosome clustering and forces chromosomes to segregate to multiple daughter cells, an event triggering apoptosis that we refer to as anaphase catastrophe. Anaphase catastrophe specifically kills tumor cells with more than two centrosomes. This death program can occur after ...
Aneuploidy is the leading cause of pregnancy loss and birth defects in humans. At least 5% of all recognized pregnancies are aneuploid. Maternal meiosis is especially error-prone and the rate of chromosome missegregation increases exponentially with advancing maternal age. Despite its clinical significance, the mechanisms underlying maternal age-dependent segregation errors are not understood. One hypothesis is that cohesion deteriorates with advancing maternal age and homologous chromosomes that do not maintain chaismata segregate randomly during meiosis. With Drosophila as a model organism, I have used techniques developed in our laboratory to experimentally age oocytes. To accelerate loss of cohesion with age, I utilized mutant flies with slightly compromised meiotic cohesion. A standard genetic test was utilized to assess errors in meiotic chromosome segregation after oocytes were subjected to the aging regimen. My objective was to determine whether aging of oocytes with slightly compromised ...
Egg infertility is a predisposition to miscarriages, infertility, and trisomic pregnancies caused by increased frequency of chromosome segregation errors in the eggs of women of advanced maternal age (AMA). Egg infertility is now a significant public health issue, with 1 in 5 US women now attempting her first pregnancy after age 35. Increased rates of egg infertility temporally coincide with rising levels of FSH that occur with age. By age 42, up to 87% of embryos are aneuploid, and 40-50% of women experience egg infertility. An Introductory Editorial will present an overview of causative factors and potential therapeutic strategies to prevent egg aneuploidy and infertility. Papers in series will be comprised of data drawn from studies performed both in animals and in humans. Part I will discuss endocrine and other molecular changes implicated in the pathogenesis of AMA oocyte aneuploidy and infertility. Section 1 will discuss defects that emerge with age in controlling the fidelity of meiotic oocyte
Many cancers have extremely high rates of chromosomal instability (CIN). Some cancers have chromosome segregation errors in every cell division, which would be detrimental to the growth of normal cells. Little is known about how cancers are able to thrive with high levels of CIN. We aim to determine how cells evolve to cope with CIN by creating a model system for persistent chromosomal instability in budding yeast. What types of mutations allow cells to adapt to a constantly shifting genomic content? What are the direct effects of CIN and aneuploidy on the health and viability of cells? close ...
Meiosis is the process of specialized divisions that produce haploid gametes from diploid cells. Meiotic chromosome distribution is a critical event in sexual reproduction. Failure of chromosome segregation during meiosis results in progeny that are aneuploid, possessing chromosomes above or below the 2N number of the diploid genome. Such failures have many important consequences, not least of which is the high rate of aneuploid oocyte production in mammals, a central cause of human infertility, miscarriages, and birth defects (Bennabi et al., 2016). Beaven et al. examined the role of Drosophila melanogaster 14-3-3 proteins in meiotic chromosome segregation and found that they promote accurate assembly of meiotic spindles through spatial regulation of claret nondisjunctional (Ncd), a minus end-directed kinesin-14 family motor protein that mediates sliding of antiparallel microtubules and cross-links parallel microtubules (Fink et al., 2009). This inhibition is relieved locally through ...
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated ...
Altered expressions and/or mutations of cell cycle regulators result in the development of cancer (1 , 34) . Disruption of mitotic checkpoints can result in abnormal nuclei, missegregated chromosomes, and aneuploidy (35 , 36) . Among the most notable abnormalities commonly found in tumor cells are chromosomal rearrangements and changes in chromosome number (4, 5, 6) . This property of cancer cells is important, especially for our understanding of the regulatory mechanisms that control the progression of malignancy. In colorectal tumors without microsatellite instability, for example, a defect in chromosome segregation results in gains or losses in excess of 10− 2/chromosome/segregation (6) . Although the precise mechanisms by which duplicated chromosomes are equally segregated during mitosis are largely unknown, the centrosome is believed to play an important role(s) in the formation of bipolar spindles. Mutations in fly aurora and yeast IPL1 are responsible for a chromosomal segregation ...
Defective segregation of chromosomes during cell division causes aneuploidy and is a characteristic feature of cancer cells. Cells therefore utilize multiple mechanisms to ensure faithful segregation and prevent aneuploidy, including phospho-regulation of proteins responsible for separating replicated chromosomes during mitosis. These mechanisms depend on the essential, conserved protein kinase Mps1. The goal of my work is to identify the downstream effectors of Mps1 in chromosome segregation and to illuminate the mechanisms of Mps1 function. This work will combine novel biochemical and cell biological approaches with emerging structural analysis methods to improve fundamental understanding of phospho-regulation of chromosome segregation.. ...
Protein kinase which plays an important role in mitotic cell cycle progression. Required for chromosome segregation at metaphase-anaphase transition, robust mitotic spindle formation and cytokinesis. Phosphorylates ATF4, CIR1, PTN, RAD26L, RBBP6, RPS7, RPS6KB1, TRIP4, STAT3 and histones H1 and H3. Phosphorylates KIF11 to promote mitotic spindle formation. Involved in G2/M phase cell cycle arrest induced by DNA damage. Inhibition of activity results in apoptosis. May contribute to tumorigenesis by suppressing p53/TP53-induced cancer cell senescence ...
Tight regulation of histone relative stoichiometry and overall levels is fundamental to the preservation of genome integrity in all eukaryotes. Abnormal histone levels induce defects in mitotic chromosome segregation, chromatin structure, and transcription and lead to loss of viability (Meeks-Wagner and Hartwell 1986; Han et al. 1987; Clark-Adams et al. 1988; Kim et al. 1988; Norris et al. 1988). Defects in chromatin structure caused by inactivation of nucleosome assembly factors cause high rates of chromosomal rearrangements and spontaneous DNA damage and elicit checkpoint activation (Myung et al. 2003; Ye et al. 2003; Ramey et al. 2004).. This study provides genetic and biochemical evidence that Trf4 and Trf5 make a redundant contribution to genome stability in yeast through control of histone mRNA levels during S phase. We show that the mRNAs coding for the four core histones, but not other cell cycle-regulated transcripts tested, accumulate to abnormally high levels in S phase in a trf4-ts ...
Research conducted in the lab of Associate Professor Jakob Nilsson now provides novel insight into how the cell secures accuracy in this process. Postdoc Gang Zhang investigated how the BubR1 protein functions in the cell, particularly its role at a structure on chromosomes called kinetochores. He found that BubR1 binds to kinetochores in two different ways and that this affects its function. "This was a surprising result as previous work had always anticipated only one way that BubR1 binds kinetochores" explains Gang Zhang. In collaboration with Blanca Lopez Mendez from the CPR Biophysics facility the molecular basis of the two BubR1 populations was established by combining biophysical measurements and advanced imaging techniques. Using this information it was possible to investigate the function of the two different pools of BubR1 and show that one pool helps establish the connection between kinetochores and microtubules and the other pool controls when the chromosomes should split into the ...
London, Nitobe; Biggins, Sue (2014). Signalling dynamics in the spindle checkpoint response. NATURE REVIEWS MOLECULAR CELL BIOLOGY. 15 (11): 735-747. Sarangapani, Krishna K.; Duro, Eris; Deng, Yi; et al. (2014). Sister kinetochores are mechanically fused during meiosis I in yeast. SCIENCE. 346(6206): 248-251. Biggins, Sue (2013). The Composition, Functions, and Regulation of the Budding Yeast Kinetochore. GENETICS. 194(4): 817-846. Gonen, Shane; Akiyoshi, Bungo; Iadanza, Matthew G.; et al. (2012). The structure of purified kinetochores reveals multiple microtubule-attachment sites. NATURE STRUCTURAL & MOLECULAR BIOLOGY. 19( 9): 925-929. ...
The putative chromatin remodeling enzyme Plk1-interacting checkpoint helicase (PICH) was uncovered as an interaction partner and substrate of the mitotic kinase Plk1. is required for prevention of chromatin bridge formation but not for UFB resolution, and quantitative analyses of UFB and chromatin bridge frequencies suggest that PIK-293 these structures are of different etiologies. We also show that this ATPase activity of PICH is required for temporal and spatial control of PICH localization to chromatin and that Plk1 likely controls PICH localization through phosphorylation of proteins unique from PICH itself. This work strengthens the view that PICH is an important, Plk1-regulated enzyme, whose ATPase activity is essential for maintenance of genome integrity. Although not required for the spindle assembly checkpoint, PICH is clearly important for faithful chromosome segregation. Electronic supplementary material The online version of this article (doi:10.1007/s00412-012-0370-0) contains ...
Essential roles of Drosophila inner centromere protein (INCENP) and aurora B in histone H3 phosphorylation, metaphase chromosome alignment, kinetochore disjunction, and chromosome segregation ...
Eukaryotic cell division uses morphologically different forms of mitosis, referred to as open, partially open and closed mitosis, for accurate chromosome segregation and proper partitioning of other cellular components such as endomembranes and cell
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Monolayers of Xenopus tissue culture cells (XTC) were grown in 66% Leibovitz L-15 media containing 10% fetal calf serum, 1mM sodium pyruvate and antibiotics at ~21°C. Mitotic chromosomes were purified from XTC cells after a 16 hour block in 10µg/ml vinblastine (Sigma-Aldrich). Chromosomes were purified as previously described with minor modifications (Wordeman et al., 1991). Experiments were preformed essentially as described (Mitchison and Kirschner, 1985). Purified mitotic chromosomes were diluted in reactions containing 10 µM tubulin in BRB80 buffer plus 1mM GTP. Reactions were incubated at 37°C for 15 minutes in a water bath and were fixed with 10mM EGS (ethyleneglycol-bis-succinimidyl-succinate) dissolved in BRB80 for 10 minutes at 37°C. Reactions were layered onto a 30% glycerol cushion prepared in BRB80 and chromosome-microtubule complexes were pelleted through the cushion onto poly-l-lysine coated coverlslips. Coverslips were post fixed with ice-cold methanol for 5 minutes at 4°C, ...
Chromosome instability (CIN) is an inherent enabling characteristic of cancer important for tumor initiation and progression and is observed in a majority of tumors (1⇓-3). It has been proposed that alterations resulting in genome instability happen early during tumor formation, allowing the accumulation of errors during DNA replication, repair, and chromosome segregation, thereby increasing the likelihood that a cell will acquire multiple genetic changes necessary for tumor progression (4). CIN is possibly the major contributor to intratumoral heterogeneity-that is, the presence of genetically distinct populations of cells within a single tumor that impacts treatment strategy, drug resistance, and tumor evolution (5⇓⇓-8). For these reasons, defining genes and pathways that drive CIN and understanding the mechanisms that underlie genome stability will contribute not only to an understanding of tumor etiology and progression but will also be relevant for guiding therapeutic strategies. The ...
Binary fission can refer to cell division in bacteria. Bacteria replicate their chromosomes prior to division, but I dont think that state can be called diploid because the chromosomes are identical. Diploid organisms can be carrying different alleles on each pair of sister chromosomes, but this is not the case for a duplicated bacterial chromosome before cell division. Therefore in my opinion your statement is not necessarily true, at least for bacteria ...
You are cordially invited to the EMBO Workshop on Chromosome Segregation and Aneuploidy, to be held on June 22-26, 2013, on the estate of Nyenrode Castle in Breukelen, The Netherlands ...
Hirano, M., Anderson, D. E., Erickson, H. P., Hirano, T. (2001) Bimodal activation of SMC ATPase by intra- and inter-molecular interactions. Embo Journal, 20 (12). pp. 3238-3250. ISSN 0261-4189 Hirano, T. (2000) Chromosome cohesion, condensation, and separation. Annual Review of Biochemistry, 69. pp. 115-144. ISSN 0066-4154 Hirano, T. (2004) Chromosome shaping by two condensins. Cell Cycle, 3 (1). pp. 26-8. ISSN 1538-4101 (Print) Hirano, T. (2005) Condensins: organizing and segregating the genome. Curr Biol, 15 (7). R265-75. ISSN 0960-9822 (Print) Hirano, T. (2005) SMC proteins and chromosome mechanics: from bacteria to humans. Philos Trans R Soc Lond B Biol Sci, 360 (1455). pp. 507-14. ISSN 0962-8436 (Print) Hirano, T., Kobayashi, R., Hirano, M. (1997) Condensins, chromosome condensation protein complexes containing XCAP-C, XCAP-E and a Xenopus homolog of the Drosophila Barren protein. Cell, 89 (4). pp. 511-21. ISSN 0092-8674 (Print) ...
an animal cell consists of 46 post-mitotic chromosomes in each of its somatic cells. explain how many chromosomes must, Hire Biology Expert, Ask Academics Expert, Assignment Help, Homework Help, Textbooks Solutions
The CRIAW Papers comprises a continuining series of publications: original research papers advancing the knowledge and understanding of womens experience.. Occupational segregation is a fact of life for Canadian women in the labour force in 9181, a fact that has been part of the collective experience of Canadian women as far back as we can analyse. Similar patterns of occupational segregation by gender have been observed in Great Britain and the United States. This pattern of female employmen, however, cannot be assumed to be characteristic of all nations, now even of all industrialized or industrializing nations. While a degree of occupational segregation by gender is observed in most nations, there is considerable cross cultural variation in the pattern. Click here for a FREE copy. ...
Association, Cancer, Chromosome, Chromosome Segregation, Coding, Cytokinesis, Esophageal Cancer, Kinase, Segregation, Serine, Single Nucleotide Polymorphisms, Threonine, Threonine Kinase
n. 1. отделение, выделение, изоляция. segregation of gifted children - выделение ( в особые группы ) одарённых детей. segregation of hardened criminals - изоляция друг от друга /раздельное содержание/ закоренелых преступников. 2..
Gaudenz Danuser: Super-Resolution Tracking of Weak Fluorescent Markers in 3D: Application in Dissecting Mechanics of Chromosome Segregation using Fluorescence Imaging and Molecular Genetics in Yeast. 61-64 ...
I ran across this the other day and thought the AO community would like to know.... Certain attachments are blocked when received by Outlook 2002. Although this can be a good thing, some people have a need to receive those attachments. I found this Microsoft article that solves this dilemma. http://support.microsoft.com/support/kb/articles/Q290/4/97.ASP?LN=EN-US&SD=gn&FR=0&qry=Blocked%20attachments&rnk=2&src=DHCS_MSPSS_gn_SRCH&SPR=OFFXP If the above link does not work try this:
We model the radial segregation patterns that form in a thin rotating drum partially filled with beads of two sizes. We predict that the waviness (or amplitude-to-wavelength ratio, denoted w) of a pattern should be subjected ...
When SV40-infected cells are placed into hypertonic medium, newly synthesized DNA accumulates as form C catenated dimers. These molecules consist of two supercoiled monomer circles of SV40 DNA interlocked by one or more topological inter-twinings and are seen as transiently labeled inter-mediates du …
About Jesse Owens - Jesse Owens grew up during the time of Jim Crow laws, but segregation never slowed him down. After setting world records for track
TY - JOUR. T1 - Aurora B-INCENP localization at centromeres/inner kinetochores is required for chromosome bi-orientation in budding yeast. AU - García-Rodríguez, Luis J.. AU - Kasciukovic, Taciana. AU - Denninger, Viola. AU - Tanaka, Tomoyuki. N1 - Funding: ERC (322682) and Wellcome Trust (096535/Z/11/Z).. PY - 2019/5/6. Y1 - 2019/5/6. N2 - For proper chromosome segregation in mitosis, sister kinetochores must interact with microtubules from opposite spindle poles (chromosome bi-orientation) [1, 2]. To promote bi-orientation, Aurora B kinase disrupts aberrant kinetochore-microtubule interactions [3-6]. It has long been debated how Aurora B halts this action when bi-orientation is established and tension is applied across sister kinetochores. A popular explanation for it is that, upon bi-orientation, sister kinetochores are pulled in opposite directions, stretching the outer kinetochores [7, 8] and moving Aurora B substrates away from Aurora-B-localizing sites at centromeres (spatial separation ...
Aurora B kinase is essential for faithful chromosome segregation during mitosis. During (pro)metaphase, Aurora B is concentrated at the inner centromere by the kinases Haspin and Bub1. However, how Haspin and Bub1 collaborate to control Aurora B activity at centromeres remains unclear. Here, we show that either Haspin or Bub1 activity is sufficient to recruit Aurora B to a distinct chromosomal locus. Moreover, we identified a small, Bub1 kinase-dependent Aurora B pool that supported faithful chromosome segregation in otherwise unchallenged cells. Joined inhibition of Haspin and Bub1 activities fully abolished Aurora B accumulation at centromeres. While this impaired the correction of erroneous KT-MT attachments, it did not compromise the mitotic checkpoint, nor the phosphorylation of the Aurora B kinetochore substrates Hec1, Dsn1, and Knl1. This suggests that Aurora B substrates at the kinetochore are not phosphorylated by centromere-localized pools of Aurora B, and calls for a reevaluation of ...
The centromere-specific histone variant CENP-A (CID in Drosophila) is a structural and functional foundation for kinetochore formation and chromosome segregation. Here, we show that overexpressed CID is mislocalized into normally non-centromeric regions in Drosophila tissue culture cells and animals. Analysis of mitoses in living and fixed cells reveals that mitotic delays, anaphase bridges, chromosome fragmentation, and cell and organismal lethality are all direct consequences of CID mislocalization. In addition, proteins that are normally restricted to endogenous kinetochores assemble at a subset of ectopic CID incorporation regions. The presence of microtubule motors and binding proteins, spindle attachments, and aberrant chromosome morphologies demonstrate that these ectopic kinetochores are functional. We conclude that CID mislocalization promotes formation of ectopic centromeres and multicentric chromosomes, which causes chromosome missegregation, aneuploidy, and growth defects. Thus, CENP-A
The accurate distribution of genetic information to daughter cells during cell division relies on the physical attachment of chromosomes to spindle microtubules mediated by kinetochores. Kinetochores are large protein assemblies deposited at specific chromosomal loci known as centromeres [1], [2], [3]. Defective centromere function results in chromosome segregation errors that can contribute to genomic instability implicated in cancer [4]. Hence, understanding the molecular mechanisms that promote kinetochore establishment and maintenance at centromeres is of prime importance.. The location of most eukaryotic centromeres is determined by the assembly of specialized chromatin composed of nucleosomes in which canonical histone H3 is replaced by the centromere‐specific H3 variant CENP‐A in vertebrates and Cnp1 (CENP‐ACnp1) in Schizosaccharomyces pombe [3], [5]. Thus, the establishment and maintenance of kinetochores requires CENP‐A to be recruited to and deposited at centromeres. In S. ...
The blockbuster chemotherapy drug paclitaxel is widely presumed to cause cell death in tumors as a consequence of mitotic arrest, as it does at concentrations routinely used in cell culture. However, we determine here that paclitaxel levels in primary breast tumors are well below those required to elicit sustained mitotic arrest. Instead, cells in these lower concentrations of drug proceed through mitosis without substantial delay and divide their chromosomes on multipolar spindles, resulting in chromosome missegregation and cell death. Consistent with these cell culture data, most mitotic cells in primary human breast cancers contain multipolar spindles after paclitaxel treatment. Contrary to the previous hypothesis, we find that mitotic arrest is dispensable for tumor regression in patients. These results demonstrate that mitotic arrest is not responsible for the efficacy of paclitaxel, which occurs because of chromosome missegregation on highly abnormal, multipolar spindles. This mechanistic ...
Author Summary Proper chromosome segregation is essential during the production of eggs and sperm. Chromosome missegregation during meiosis results in the lethality of the offspring or in children carrying extra copies of a given chromosome (for example, Down syndrome). Recombination results in homologous chromosomes becoming physically interlocked in a manner that is normally sufficient to ensure proper segregation. Chromosomes that fail to undergo recombination require additional mechanisms to ensure their proper segregation. In Drosophila melanogaster oocytes we show that chromosomes that fail to recombine undergo dynamic movements on the meiotic spindle prior to their proper segregation. Although previous studies had shown that non-recombinant chromosomes move to opposite sides of the developing meiotic spindle, we show that these chromosomes can cross the spindle and re-associate with their homologs to attempt reorientation. Additionally, we observed threads connecting separated non-recombinant
Kinetochores in multicellular eukaryotes are usually associated with heterochromatin. Whether this heterochromatin simply promotes the cohesion necessary for accurate chromosome segregation at cell division or whether it also has a role in kinetochore assembly is unclear. Schizosaccharomyces pombe is an important experimental system for investigating centromere function, but all of the previous work with this species has exploited a single strain or its derivatives. The laboratory strain and...
Each mitotic chromosome is constituted by two sister chromatids whose correct segregation to the daughter cells is ensured by amphitelic attachment, in which the two sister kinetochores (KTs) are attached to microtubules (MTs) from opposite mitotic spindle poles. KT mis-attachments can occur in early mitosis and cause chromosome mis-segregation and aneuploidy if not corrected. These mis-attachments include monotelic (one attached and one unattached sister KT), syntelic (both sister KTs attached to the same spindle pole), and merotelic (a single KT attached to MTs from opposite spindle poles) attachments. A biochemical pathway named the Spindle Assembly Checkpoint (SAC) is responsible for delaying anaphase onset to allow correction of KT mis-attachments. SAC activation is believed to occur due to KT localization of certain SAC proteins and/or lack of tension, but only monotelic attachment has been proven to activate the SAC. To determine if and how other KT mis-attachments may activate the SAC, ...
The centromere is a functional chromosome domain that is essential for faithful chromosome segregation during cell division and that can be reliably identified by the presence of the centromere-specific histone H3 variant CenH3. In monocentric chromosomes, the centromere is characterized by a single CenH3-containing region within a morphologically distinct primary constriction. This region usually spans up to a few Mbp composed mainly of centromere-specific satellite DNA common to all chromosomes of a given species. In holocentric chromosomes, there is no primary constriction; the centromere is composed of many CenH3 loci distributed along the entire length of a chromosome. Using correlative fluorescence light microscopy and high-resolution electron microscopy, we show that pea (Pisum sativum) chromosomes exhibit remarkably long primary constrictions that contain 3-5 explicit CenH3-containing regions, a novelty in centromere organization. In addition, we estimate that the size of the chromosome ...
In humans, reproduction is considered a relatively inefficient process, when compared with other mammalian species and the chance of achieving a spontaneous pregnancy after timed intercourse is at the most 20-30%. Chromosome segregation errors are a well-known inherent feature of cell division in human preimplantation embryos produced by in vitro ... read more fertilization (IVF). The occurrence of such errors, which results in embryos containing chromosomally abnormal (aneuploid) cells, is believed to be the main cause for the reported inefficiency of human reproduction, as it may lead to pre-clinical pregnancy losses. In this thesis we start by evaluating the impact of ovarian stimulation administrated to patients undergoing IVF on the development of IVF-derived human embryos. We conclude that although the use of ovarian stimulation is considered relatively safe, further studies are needed to increase the knowledge on this subject and reduce potential effects on embryo development and ...
To preserve genome integrity, the two sister chromatids of each mitotic chromosome must be distributed equally between daughter cells. Movement of sister chromatids to opposite poles of a dividing cell requires attachment to spindle microtubules of opposing orientation. Errors in the attachment process can lead to chromosome missegregation and aneuploidy (i.e. an aberrant number of chromosomes). Aneuploid karyotypes are the major cause of spontaneous miscarriages in humans [1] and often observed in cancer genomes [2]. A multi-complex protein interface between mitotic chromosomes and the spindle apparatus called the kinetochore is responsible for both the establishment and regulation of the microtubule attachment process [3]. The kinetochore consists of approximately 30 core structural proteins that are arranged into several functional subcomplexes. Structural kinetochore proteins constitute the physical link between chromosomes and spindle microtubules. They also act as a signalling platform by ...
Mechanism and Control of Meiotic Recombination. We study homologous recombination and chromosome structural changes that occur during meiosis, using budding yeast as a model system. Recombination, and in particular the crossover products of recombination, are essential for proper chromosome segregation during meiosis. Chromosome mis-segregation caused by defects in meiotic recombination leads to chromosome imbalance in gametes, and these chromosome imbalances are a leading cause of infertility and birth defects in modern human populations. We aim to describe the molecular steps of meiotic recombination, and how they are regulated in parallel with changes in chromosome structure and with cell cycle transitions that occur during meiosis. Because meiosis is an excellent model system to study homologous recombination, our findings also have provided insight into mechanisms by which DNA damage is repaired and genome integrity is maintained during the mitotic cell cycle.. Meiotic recombination ...
Meiosis is a special division during which a cell undergoes two sequential rounds of chromosome segregation with no intervening DNA replication, to generate gamete cells with half the original chromosomal complement. During the first meiotic division (meiosis I), recombination among homologous chromosomes generates novel genetic combinations that play an important role in evolution and breeding. Crossovers persist as cytologically visible chiasmata until homologues segregate in metaphase I and are important for ensuring balanced segregation of homologues [1]. Thus the evolutionarily important effects of recombination and allele shuffling are intimately tied to the physical workings of meiotic chromosome segregation and the maintenance of genome integrity over generations.. Meiotic recombination is an elaborate process, involving numerous steps that take place over the course of many hours (e.g. [2]). Recombination is essentially a DNA repair process that relies on initial programmed double ...
Cao Y-K, Zhong Z-S, Chen D-Y, Zhang G-X, Schatten H, Sun Q-Y. 2005. Cell cycle-dependent localization and possible roles of the small GTPase Ran in mouse oocyte maturation, fertilization and early cleavage. Reproduction 130:431-440. Clift D, Schuh M. 2015. A three-step MTOC fragmentation mechanism facilitate bipolar spindle assembly in mouse oocytes. Nat Commun 6:7217, 10.1038/ncomm8217. Eichenlaub-Ritter U, Winterscheidt U, Vogt E, Shen Y, Tinneberg HR, Sorensen R. 2007. 2-methoxyestradiol induces spindle aberrations, chromosome congression failure, and nondisjunction in mouse oocytes. Biol Reprod 76:784-793. Holubcová Z, Blayney M, Elder K, Schuh M. 2015. Error-prone chromosome-mediated spindle assembly favors chromosome segregation defects in human oocytes. Science 348:1143-1147. Ibanez E, Albertini DF, Overstrom EW. 2003. Demecolcine-induced oocyte enucleation for somatic cell cloning: coordination between cell-cycle egress, kinetics of cortical cytoskeletal interactions, and second polar ...
During the process of cell division, the spindle checkpoint prevents separation of the duplicated chromosomes until each chromosome is properly attached to the spindle apparatus. In order to preserve the cells identity and proper function, it is necessary to maintain the appropriate number of chromosomes after each cell division. An error in generating daughter cells with fewer or greater number of chromosomes than expected (a situation termed aneuploidy), may lead in best case to cell death, or alternatively it may generate catastrophic phenotypic results. Examples include: In cancer cells, aneuploidy is a frequent event, indicating that these cells present a defect in the machinery involved in chromosome segregation, as well as in the mechanism ensuring that segregation is correctly performed. In humans, Down syndrome appears in children carrying in their cells one extra copy of chromosome 21, as a result of a defect in chromosome segregation during meiosis in one of the progenitors. This ...
Aurora B family kinases play an essential role in chromosome segregation and cytokinesis. Recent work suggests that the kinase activity is required for bipolar chromosome orientation, kinetochore assembly, spindle checkpoint and microtubule dynamics. Aurora B also has additional functions in chromosome condensation and cohesion.
Figure 1. -Schematic diagram of mitotic recombination occurring in eye precursor cells with the ey-GAL4/UAS-FLP/GMR-hid (EGUF/hid) method. At the far left, a G2 premitotic photoreceptor precursor cell is depicted that is undergoing FLP-mediated mitotic recombination between nonidentical (homologous) chromosome arms. Premitotic photoreceptor precursors that undergo an even number of this type of recombination event follow the pathway indicated by the downward arrow and do not give rise to homozygous progeny cells. Premitotic photoreceptor precursors that undergo an odd number of these recombination events follow the pathway indicated by the upward arrow and have a 50% chance of giving rise to either heterozygous or homozygous progeny cells depending on the chromosome segregation pattern at cell division. "Silent" G2 recombination events between identical (sister) chromosome arms as well as G1 recombination events between homologous chromosomes will also be occurring, but are inconsequential with ...
The putative chromatin remodeling enzyme Plk1-interacting checkpoint helicase (PICH) was uncovered as an interaction partner and substrate of the mitotic kinase Plk1. is required for prevention of chromatin bridge formation but not for UFB resolution, and quantitative analyses of UFB and chromatin bridge frequencies suggest that PIK-293 these structures are of different etiologies. We also show that this ATPase activity of PICH is required for temporal and spatial control of PICH localization to chromatin and that Plk1 likely controls PICH localization through phosphorylation of proteins unique from PICH itself. This work strengthens the view that PICH is an important, Plk1-regulated enzyme, whose ATPase activity is essential for maintenance of genome integrity. Although not required for the spindle assembly checkpoint, PICH is clearly important for faithful chromosome segregation. Electronic supplementary material The online version of this article (doi:10.1007/s00412-012-0370-0) contains ...
In the mitotic cell cycle, it is only when all chromosomes have appropriately established bipolar attachment to the mitotic spindle that the metaphase-to-anaphase transition can occur (Chen, 2004; Yu and Tang, 2005). Because kinetochores capture microtubules in a stochastic manner, three types of erroneous kinetochore attachments, including monotelic (only one of the sister kinetochores is attached to one spindle pole), syntelic (both sister kinetochores are attached to the same spindle pole), and merotelic (one kinetochore is attached to two opposing spindle poles) attachment, frequently occur (Gregan et al., 2011). Thus, there must be a surveillance mechanism that prevents the precocious separation of sister chromatids until all the improper kinetochore attachments are corrected, ensuring the fidelity of chromosome segregation (Meraldi and Sorger, 2005; Yu and Tang, 2005). The spindle assembly checkpoint (SAC) is such a mechanism that delays anaphase onset when any kinetochore is not properly ...
Segregation of homologous maternal and paternal centromeres to opposite poles during meiosis I depends on post-replicative crossing over between homologous non-sister chromatids, which creates chiasmata and therefore bivalent chromosomes. Destruction of sister chromatid cohesion along chromosome arms due to proteolytic cleavage of cohesins Rec8 subunit by separase resolves chiasmata and thereby triggers the first meiotic division. This produces univalent chromosomes, the chromatids of which are held together by centromeric cohesin that has been protected from separase by shugoshin (Sgo1/MEI-S332) proteins. Here we show in both fission and budding yeast that Sgo1 recruits to centromeres a specific form of protein phosphatase 2A (PP2A). Its inactivation causes loss of centromeric cohesin at anaphase I and random segregation of sister centromeres at the second meiotic division. Artificial recruitment of PP2A to chromosome arms prevents Rec8 phosphorylation and hinders resolution of chiasmata. Our data are
... It has been suggested (M. P. Maguire, MGN 51:86-87, 1977) that maintenance of dyad integrity between anaphase I and anaphase II may depend upon the same mechanism as that which seems responsible for chiasma maintenance during the period between loss of the synaptonemal complex and anaphase I, namely sister chromatid cohesiveness. As observed cytologically at anaphase I in normal material, dyads are composed of four, usually highly condensed, chromatid arms which tend to diverge from tightly paired sister centromere regions. During interkinesis there is some decondensation of these arms followed by their recondensation during prophase II. During early prophase II in good preparations the four arms of each dyad can be traced. If sister chromatids tend to cohere until anaphase II, except where they were separated at anaphase I as a result of crossing over, dyads would be expected to vary in their prophase II ...
In eukaryotic cells, accurate chromosome segregation requires the spindle assembly checkpoint, a surveillance system monitoring kinetochore attachment to microtubules of the mitotic spindle (Lara-Gonzalez et al., 2012; Musacchio, 2015). The spindle checkpoint kinase MPS1 binds to unattached kinetochores and phosphorylates kinetochore proteins, thus directing the accumulation of spindle checkpoint proteins of the MAD and BUB families (Musacchio, 2015; Ciliberto and Hauf, 2017). A subset of the MAD and BUB proteins then assemble into the mitotic checkpoint complex (MCC; Musacchio, 2015). The mitotic checkpoint complex then diffuses away from the kinetochore to inhibit the ubiquitin E3 ligase anaphase promoting complex/cyclosome (APC/C), thus preventing mitotic exit (Sivakumar and Gorbsky, 2015). The two crucial targets ubiquitylated by the APC/C to promote mitotic exit are securin, the inhibitor of separase, and most important for this work, cyclin B, the activating subunit of a cyclin-dependent ...
Separase is a highly conserved cysteine protease required for proper chromosome segregation, and several other aspects of anaphase during both meiotic and mitotic stages of cell division (Peters et al. 2008). Separase proteolytic activity is inhibited during interphase and early mitosis by its pseudosubstrate inhibitor, securin (Nasmyth 2002). The protease activity of separase is critical for the cleavage of kleisin subunits of the cohesin complex (Uhlmann et al. 2000; Hauf et al. 2001). Cohesin holds sister chromatids together prior to their proper attachment to spindles and alignment on the metaphase plate preceding anaphase (Nasmyth and Haering 2009). Separase has also been implicated in various cell cycle regulatory functions. In budding yeast, separase stabilizes the anaphase spindle by cleaving the spindle and kinetochore-associated protein Slk19 (Sullivan et al. 2001). It is also involved in the release of the essential mitotic phosphatase Cdc14 in budding yeast (Sullivan and Uhlmann ...
TY - JOUR. T1 - Involvement of the spliceosomal U4 small nuclear RNA in heterochromatic gene silencing at fission yeast centromeres. AU - Chinen, Madoka. AU - Morita, Misato. AU - Fukumura, Kazuhiro. AU - Tani, Tokio. PY - 2010/2/19. Y1 - 2010/2/19. N2 - prp13-1 is one of the mutants isolated in a screen for defective pre-mRNA splicing at a nonpermissive temperature in fission yeast Schizosaccharomyces pombe. We cloned the prp13+ gene and found that it encodes U4 small nuclear RNA (snRNA) involved in the assembly of the spliceosome. The prp13-1 mutant produced elongated cells, a phenotype similar to cell division cycle mutants, and displays a high incidence of lagging chromosomes on anaphase spindles. The mutant is hypersensitive to the microtubule-destabilizing drug thiabendazole, supporting that prp13-1 has a defect in chromosomal segregation. We found that the prp13-1 mutation resulted in expression of the ura4 + gene inserted in the pericentromeric heterochromatin region and reduced ...
In prophase I of meiosis I, each chromosome is aligned with its homologous partner and pairs completely. In prophase I, the DNA has already undergone replication so each chromosome consists of two identical chromatids connected by a common centromere.[9] During the zygotene stage of prophase I, the homologous chromosomes pair up with each other.[9] This pairing occurs by a synapsis process where the synaptonemal complex - a protein scaffold - is assembled and joins the homologous chromosomes along their lengths.[6] Cohesin crosslinking occurs between the homologous chromosomes and helps them resist being pulled apart until anaphase.[7] Genetic crossing over occurs during the pachytene stage of prophase I.[9] In this process, genes are exchanged by the breaking and union of homologous portions of the chromosomes lengths.[6] Structures called chiasmata are the site of the exchange. Chiasmata physically link the homologous chromosomes once crossing over occurs and throughout the process of ...

Chromosome segregation error during early cleavage in mouse pre-implantation embryo does not necessarily cause developmental...Chromosome segregation error during early cleavage in mouse pre-implantation embryo does not necessarily cause developmental...

However, only a few studies have examined the relationship between chromosome segregation errors during early cleavage and ... These results suggest that early chromosome segregation error causing micronuclei formation affects ploidy and development to ... aneuploidy resulting from chromosome segregation error is considered responsible for pregnancy loss. ... We showed that some embryos exhibiting early chromosomal segregation error and formation of micronuclei retained their ...
more infohttps://www.nature.com/articles/s41598-020-57817-x?error=cookies_not_supported&code=57ca2f61-0b4b-43ab-bb1c-550e92b4b490

Cellular Apoptosis Susceptibility Protein
     Summary Report | CureHunterCellular Apoptosis Susceptibility Protein Summary Report | CureHunter

07/01/2012 - "The chromosome segregation 1-like (CSE1L) protein is highly expressed in most cancers and has been shown to be ... 01/01/2012 - "Here we report that chromosome segregation 1-like (CSE1L) protein is a microvesicle membrane protein and is a ... CAPTS gene product; CAS Export Factor; CSE1L Protein; Chromosome Segregation 1 Like Protein; Importin-alpha Export Receptor CAS ...
more infohttp://www.curehunter.com/public/keywordSummaryD029563-Cellular-Apoptosis-Susceptibility-Protein.do

Anti-Cellular Apoptosis Susceptibility抗体(ab96755)|Abcam中国Anti-Cellular Apoptosis Susceptibility抗体(ab96755)|Abcam中国

Chromosome segregation 1 Like antibody. *Chromosome segregation 1 like protein antibody. *Chromosome segregation 1-like protein ... CSE 1 chromosome segregation 1 like antibody. *CSE 1 chromosome segregation 1 like protein antibody ... CSE1 chromosome segregation 1 like (yeast) antibody. *CSE1 chromosome segregation 1 like antibody ...
more infohttp://www.abcam.cn/Cellular-Apoptosis-Susceptibility-antibody-ab96755.html

chromosome segregation: decreased | SGDchromosome segregation: decreased | SGD

The Saccharomyces Genome Database (SGD) provides comprehensive integrated biological information for the budding yeast Saccharomyces cerevisiae.
more infohttps://www.yeastgenome.org/phenotype/decreased_chromosome_segregation

Chromosome Segregation and StructureChromosome Segregation and Structure

Chromosome Segregation; Centrosomes and Centrioles; Ploidy, Chromosome Segregation Errors, and Disease; Asymmetric Cell ... Organizing Chromosomes during Segregation. Noncanonical Biogenesis of Centrioles and Basal Bodies. Catarina Nabais, Sónia Gomes ... Impact of Centrosome Aberrations on Chromosome Segregation and Tissue Architecture in Cancer. Erich A. Nigg, Dominik Schnerch, ... The 82nd Cold Spring Harbor Symposium focused on Chromosome Segregation & Structure and addressed the enormous progress in our ...
more infohttps://www.cshlpress.com/default.tpl?action=full&cart=1573296023688040192&--eqskudatarq=1228&typ=ps&newtitle=Chromosome%20Segregation%20and%20Structure

Chromosome Segregation and StructureChromosome Segregation and Structure

Chromosome Segregation; Centrosomes and Centrioles; Ploidy, Chromosome Segregation Errors, and Disease; Asymmetric Cell ... Organizing Chromosomes during Segregation. Noncanonical Biogenesis of Centrioles and Basal Bodies. Catarina Nabais, Sónia Gomes ... Impact of Centrosome Aberrations on Chromosome Segregation and Tissue Architecture in Cancer. Erich A. Nigg, Dominik Schnerch, ... The 82nd Cold Spring Harbor Symposium focused on Chromosome Segregation & Structure and addressed the enormous progress in our ...
more infohttps://www.cshlpress.com/default.tpl?action=full&cart=1573267734682276231&--eqskudatarq=1228&typ=ps&newtitle=Chromosome%20Segregation%20and%20Structure

Chromosome Segregation and Structure
	Chromosome Segregation and Structure

Chromosome Segregation; Centrosomes and Centrioles; Ploidy, Chromosome Segregation Errors, and Disease; Asymmetric Cell ... Organizing Chromosomes during Segregation. Noncanonical Biogenesis of Centrioles and Basal Bodies. Catarina Nabais, Sónia Gomes ... Impact of Centrosome Aberrations on Chromosome Segregation and Tissue Architecture in Cancer. Erich A. Nigg, Dominik Schnerch, ... The 82nd Cold Spring Harbor Symposium focused on Chromosome Segregation & Structure and addressed the enormous progress in our ...
more infohttps://cshlpress.com/default.tpl?action=full&cart=1550364274162328170&--eqskudatarq=1228

Chromosome Segregation and Structure
	Chromosome Segregation and Structure

Chromosome Segregation; Centrosomes and Centrioles; Ploidy, Chromosome Segregation Errors, and Disease; Asymmetric Cell ... Organizing Chromosomes during Segregation. Noncanonical Biogenesis of Centrioles and Basal Bodies. Catarina Nabais, Sónia Gomes ... Impact of Centrosome Aberrations on Chromosome Segregation and Tissue Architecture in Cancer. Erich A. Nigg, Dominik Schnerch, ... The 82nd Cold Spring Harbor Symposium focused on Chromosome Segregation & Structure and addressed the enormous progress in our ...
more infohttps://cshlpress.com/default.tpl?action=full&cart=157900864640290473&--eqskudatarq=1229&typ=ps&newtitle=Chromosome%20Segregation%20and%20Structure

Small GTPase Controls Chromosome Segregation | Science SignalingSmall GTPase Controls Chromosome Segregation | Science Signaling

Knockdown of Gie in Drosophila cells also blocked normal sister chromosome segregation but did not block the progression of ... Named Gie1 and Gie2 (GTPases indispensible for equal segregation of chromosomes), the new members share about 30% amino acid ... Novel small GTPase subfamily capable of associating with tubulin is required for chromosome segregation. J. Cell Sci. 117, 4705 ... may localize to the spindle mid-zone and mid-body to control chromosome segregation. ...
more infohttp://stke.sciencemag.org/content/2004/251/tw337

Small GTPase Controls Chromosome Segregation | Science SignalingSmall GTPase Controls Chromosome Segregation | Science Signaling

Thank you for your interest in spreading the word about Science Signaling.. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.. ...
more infohttps://stke.sciencemag.org/content/2004/251/tw337/tab-article-info

Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis.  - PubMed - NCBIAcentrosomal spindle assembly and chromosome segregation during oocyte meiosis. - PubMed - NCBI

In most animal species, chromosome segregation during female meiosis occurs on spindles assembled in the absence of the major ... Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis.. Dumont J1, Desai A. ... During anaphase I, dissolution of chromosome arm cohesion leads to reductional segregation of homologs. Sister chromatids are ... The nature of the link between microtubules and chromosomes, and whether microtubule assembly and/or sliding promote chromosome ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/22480579?dopt=Abstract

New insight into chromosome segregation: Centromere-independent kinetochore assembly - ScienceBlog.comNew insight into chromosome segregation: Centromere-independent kinetochore assembly - ScienceBlog.com

Home Blog Entry New insight into chromosome segregation: Centromere-independent kinetochore assembly ... New insight into chromosome segregation: Centromere-independent kinetochore assembly. April 28, 2011. ... provides fascinating new insight into the complex of proteins that orchestrates the proper segregation of human chromosomes ... Duplicated chromosomes are attached together at a region called the centromere. The centromere plays an important role in the ...
more infohttps://scienceblog.com/44826/new-insight-into-chromosome-segregation-centromere-independent-kinetochore-assembly/

Discovery of a novel chromosome segregation mechanism during cell division | EurekAlert! Science NewsDiscovery of a novel chromosome segregation mechanism during cell division | EurekAlert! Science News

Abnormal segregation can cause cell death or diseases like Down syndrome and cancer. Filamentous spindle fibers must bind to ... For the spindle fiber to be correctly joined, the chromosome must have heterochromatin. However, the mechanism for forming this ... chromosomes need to be evenly segregated. This equal distribution is important to accurately pass genetic information to the ... The chromosome centromere is an essential area for chromosome movement and accurate segregation in which a kinetochore ...
more infohttps://www.eurekalert.org/pub_releases/2017-03/ku-doa032217.php

Spindle asymmetry drives non-Mendelian chromosome segregationSpindle asymmetry drives non-Mendelian chromosome segregation

Cortical CDC42 depends on polarization directed by chromosomes, which are positioned near the cortex to allow the asymmetric ... from the cell cortex regulated microtubule tyrosination to induce spindle asymmetry and that non-Mendelian segregation depended ...
more infohttps://insights.ovid.com/pubmed?PMID=29097549

Live Cell Imaging of Chromosome Segregation During Mitosis | ProtocolLive Cell Imaging of Chromosome Segregation During Mitosis | Protocol

This protocol describes an easy and convenient method to label and visualize live chromosomes in mitotic cells using Histone2B- ... Cell cycle control checkpoints that ensure accurate chromosome segregation prevent aneuploidy and cell transformation 1,2,3. In ... Live Cell Imaging of Chromosome Segregation During Mitosis. Prajakta Varadkar1, Kazuyo Takeda2, Brenton McCright1 ... Varadkar, P., Takeda, K., McCright, B. Live Cell Imaging of Chromosome Segregation During Mitosis. J. Vis. Exp. (133), e57389, ...
more infohttps://www.jove.com/video/57389/live-cell-imaging-of-chromosome-segregation-during-mitosis

Chromosome segregation - WikipediaChromosome segregation - Wikipedia

After the first chromosome segregation in meiosis I is complete, there is further chromosome segregation during the second ... Both proper initial segregation of chromosomes in prophase I and the next chromosome segregation during equational division in ... Improper chromosome segregation can result in aneuploid gametes having either too few or too many chromosomes. The second stage ... This segregation process occurs during both mitosis and meiosis. During mitosis chromosome segregation occurs routinely as a ...
more infohttps://en.wikipedia.org/wiki/Chromosome_segregation

Chromosome Segregation and Kinetochore research - Istituto Europeo di OncologiaChromosome Segregation and Kinetochore research - Istituto Europeo di Oncologia

Hence, the segregation of the genome is coordinated in time and space.. To study chromosome segregation we implement a multi- ... generating offspring with a correct number of chromosomes. Errors made during chromosome segregation e.g., due to a lack or ... As chromosome segregation and the proteins involved are evolutionary conserved we study them in the yeast Saccharomyces ... To identify new proteins involved in chromosome segregation we perform protein affinity purifications and yeast two-hybrid ...
more infohttps://www.ieo.it/it/ricerca/Ricerca-di-base/Dipartimento-di-Oncologia-Sperimentale/Chromosome-Segregation-and-Kinetochore-research-Unit/

Antagonistic spindle motors and MAPs regulate metaphase spindle length and chromosome segregation.  - PubMed - NCBIAntagonistic spindle motors and MAPs regulate metaphase spindle length and chromosome segregation. - PubMed - NCBI

B) Plot shows frequency comparison of chromosome behavior between klp5Δ and klp5Δ:ase1Δ at 23°C. No chromosome mis-segregation ... normal chromosome segregation compared to ~50% for klp6Δ alone (p,10−9).. (D) Plot shows frequency comparison of chromosome ... normal chromosome segregation.. (C) Plot shows frequency comparison of chromosome behavior between klp6Δ and cut7.24ts:klp6Δ at ... showed chromosome segregation defects. To test the force-balance model of spindle length control and its effect on chromosome ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/24239120?dopt=Abstract

Genetic Analysis of Hybrid Cells Using Isozyme Markers as Monitors of Chromosome Segregation | SpringerLinkGenetic Analysis of Hybrid Cells Using Isozyme Markers as Monitors of Chromosome Segregation | SpringerLink

Genetic Analysis of Hybrid Cells Using Isozyme Markers as Monitors of Chromosome Segregation. ... and adenylate kinase are syntenic on mouse chromosome 4 and human chromosome 1p, Proc. Natl. Acad. Sci. USA 75:2382-2386.PubMed ... Genetic Analysis of Hybrid Cells Using Isozyme Markers as Monitors of Chromosome Segregation. In: Shay J.W. (eds) Techniques in ... McKusick, V. A., and Ruddle, F. H., 1977, The status of the gene map of human chromosomes, Science 196:390-405.PubMedCrossRef ...
more infohttps://link.springer.com/chapter/10.1007/978-1-4684-4271-7_35

Chromosome segregation control by Escherichia coli ObgE GTPase - Foti - 2007 - Molecular Microbiology - Wiley Online LibraryChromosome segregation control by Escherichia coli ObgE GTPase - Foti - 2007 - Molecular Microbiology - Wiley Online Library

Our results are consistent with a role for ObgE in chromosome partitioning, with defects in chromosome segregation observed ... A reasonable hypothesis is that ObgE is required to license chromosome segregation and, in its absence, chromosomes are ... The mechanism of bacterial chromosome segregation is still mysterious, although the demonstration of segregation defects ... loss of sister cohesion triggers global chromosome movement and mediates chromosome segregation. Cell 121: 899-911. *CrossRef ...
more infohttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-2958.2007.05811.x/full

Mitotic Centromere-associated Kinesin Is Important for Anaphase Chromosome Segregation | JCBMitotic Centromere-associated Kinesin Is Important for Anaphase Chromosome Segregation | JCB

... as more is known about the basic mechanisms of cell cycle regulation and chromosome segregation, certain lagging chromosome ... Mitotic Centromere-associated Kinesin Is Important for Anaphase Chromosome Segregation. Todd Maney, Andrew W. Hunter, Mike ... Effect of endogenous MCAK depletion on chromosome segregation. Mitotic cells triple-labeled with anti-MCAK (A, D, G, J, M); ... 1994) Video time-lapse study of mitosis in binucleate V79 cells: chromosome segregation and cleavage. Mutagenesis 9:117-123, ...
more infohttp://jcb.rupress.org/content/142/3/787

Naturally Occurring Differences in CENH3 Affect Chromosome Segregation in Zygotic Mitosis of HybridsNaturally Occurring Differences in CENH3 Affect Chromosome Segregation in Zygotic Mitosis of Hybrids

However, when crossed to the wild type, hybrid progeny suffered from extensive mis-segregation. Genotypes include simple ... aneuploids, novel genetic rearrangements, and in extreme cases haploids where all the chromosomes from one parent are lost. ...
more infohttps://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004970

Cdk5rap2 regulates centrosome function and chromosome segregation in neuronal progenitors | DevelopmentCdk5rap2 regulates centrosome function and chromosome segregation in neuronal progenitors | Development

Cdk5rap2 regulates centrosome function and chromosome segregation in neuronal progenitors Message Subject (Your Name) has sent ... Cdk5rap2 regulates centrosome function and chromosome segregation in neuronal progenitors. Sofia B. Lizarraga, Steven P. ... Cdk5rap2 regulates centrosome function and chromosome segregation in neuronal progenitors. Sofia B. Lizarraga, Steven P. ... Cdk5rap2 regulates centrosome function and chromosome segregation in neuronal progenitors. Sofia B. Lizarraga, Steven P. ...
more infohttp://dev.biologists.org/content/137/11/1907

Variation in Crossover Frequencies Perturb Crossover Assurance Without Affecting Meiotic Chromosome Segregation in...Variation in Crossover Frequencies Perturb Crossover Assurance Without Affecting Meiotic Chromosome Segregation in...

Chromosome size and shape have a role in nonexchange chromosome segregation in Drosophila (Grell 1964; Hawley et al. 1992). In ... 2005 The roles of MAD1, MAD2 and MAD3 in meiotic progression and the segregation of nonexchange chromosomes. Nat. Genet. 37: ... A possible role for the Msh4/5 complex in segregation of nonexchange chromosomes can also explain why the mlh3Δ mms4Δ double ... Spindle checkpoint proteins Mad2 and Mad3 are known to be involved in nonexchange chromosome segregation (Shonn et al. 2000; ...
more infohttps://www.genetics.org/content/199/2/399

Site-specific recombination and circular chromosome segregation  - Enlighten: PublicationsSite-specific recombination and circular chromosome segregation - Enlighten: Publications

Site-specific recombination and circular chromosome segregation. Philosophical Transactions of the Royal Society B: Biological ... functions in Escherichia coli to ensure that circular plasmids and chromosomes are in the monomeric state prior to segregation ... Two recombinases, XerC and XerD, bind cooperatively to a recombination site present in the E. coli chromosome and to sites ...
more infohttp://eprints.gla.ac.uk/133505/
  • Furthermore, the severity of chromosomal segregation errors ranges from mild, where the chromosome deviates a few micrometers from the others, to severe with micronuclei formation. (nature.com)
  • Using our less-invasive live-cell imaging system optimized for long-term imaging for the analysis of molecular dynamics of mammal pre-implantation embryos 12 , the type/severity of early chromosomal segregation errors in pre-implantation embryos can be assessed. (nature.com)
  • We performed embryo transfer after fluorescence observation of chromosomal segregation using mouse embryos obtained by in vitro fertilization (IVF) (a technique where unfertilized eggs retrieved from females are fertilized in vitro with spermatozoa). (nature.com)
  • Through live-cell imaging, single embryo transfer, and genome sequencing at single-cell resolution, we demonstrated that early chromosomal segregation error resulting in aneuploidy in mouse pre-implantation embryos is a developmental risk to the blastocyst, but some blastocysts retain their developmental potential. (nature.com)
  • In the pre-implantation embryo, aneuploidy resulting from chromosome segregation error is considered responsible for pregnancy loss. (nature.com)
  • These results suggest that early chromosome segregation error causing micronuclei formation affects ploidy and development to blastocyst but does not necessarily cause developmental failure after the blastocyst stage. (nature.com)
  • An increased number of aneuploid blastomeres in embryos may result from chromosome segregation errors during early division. (nature.com)
  • They then analyzed the cause of abnormality of centromeric heterochromatin formation in splicing mutant strain, showing that introns in nontranslatable RNA are transcribed from chromosome centromeres, and that artificial removal of introns induced abnormalities in heterochromatin formation. (eurekalert.org)
  • This study revealed for the first time that intron sequences, originally thought to be useless sequences that were normally removed in the process of gene expression, have an important function of controlling heterochromatin formation in chromosome centromeres. (eurekalert.org)
  • Karyotype conversion, from mostly telocentric (centromere terminal) to mostly metacentric (centromere internal), typically reflects fixation of Robertsonian (Rb) fusions, a common chromosomal rearrangement that joins two telocentric chromosomes at their centromeres to create one metacentric. (upenn.edu)
  • These results suggest that early chromosome segregation error causing micronuclei formation affects ploidy and development to blastocyst but does not necessarily cause developmental failure after the blastocyst stage. (nature.com)
  • Abnormal chromosomal segregation, on the other hand, can cause cell death (apoptosis) or diseases like Down syndrome and cancer. (eurekalert.org)
  • Furthermore, the severity of chromosomal segregation errors ranges from mild, where the chromosome deviates a few micrometers from the others, to severe with micronuclei formation. (nature.com)
  • Using our less-invasive live-cell imaging system optimized for long-term imaging for the analysis of molecular dynamics of mammal pre-implantation embryos 12 , the type/severity of early chromosomal segregation errors in pre-implantation embryos can be assessed. (nature.com)
  • We performed embryo transfer after fluorescence observation of chromosomal segregation using mouse embryos obtained by in vitro fertilization (IVF) (a technique where unfertilized eggs retrieved from females are fertilized in vitro with spermatozoa). (nature.com)
  • Through live-cell imaging, single embryo transfer, and genome sequencing at single-cell resolution, we demonstrated that early chromosomal segregation error resulting in aneuploidy in mouse pre-implantation embryos is a developmental risk to the blastocyst, but some blastocysts retain their developmental potential. (nature.com)
  • Expression of a dominant-negative form of Gie1 in a cultured human cell line caused the appearance of micronuclei and abnormal chromosome segregation. (sciencemag.org)
  • Errors made during chromosome segregation e.g., due to a lack or overexpression of a single kinetochore protein, can lead to daughter cells with an abnormal number of chromosomes (aneuploidy). (ieo.it)
  • Some cells contained abnormal nuclear structures, such as condensed chromosomes with short spindles, or chromosomes stretched or unequally separated by elongating spindles. (genetics.org)
  • Low tension is a widely accepted mechanism for recognizing errors, but whether chromosome position regulates MT attachments is unknown. (upenn.edu)
  • However, only a few studies have examined the relationship between chromosome segregation errors during early cleavage and development. (nature.com)
  • An increased number of aneuploid blastomeres in embryos may result from chromosome segregation errors during early division. (nature.com)
  • The finding is expected to lead to the clarification of development mechanisms of diseases caused by abnormalities in the number of chromosomes, such as Down syndrome. (eurekalert.org)
  • Finally, RSC is not required for centromeric deposition of the histone H3 variant Cse4p, suggesting that RSC plays a role in reconfiguring centromeric and flanking nucleosomes following Cse4p recruitment for proper chromosome transmission. (asm.org)
  • Here we found that CDC42 signaling from the cell cortex regulated microtubule tyrosination to induce spindle asymmetry and that non-Mendelian segregation depended on this asymmetry. (ovid.com)
  • Preferential chromosome segregation is predicted to depend on spindle asymmetry. (upenn.edu)
  • The 82nd Cold Spring Harbor Symposium focused on Chromosome Segregation & Structure and addressed the enormous progress in our understanding of the nature and behavior of chromosomes during the life cycle of the cell. (cshlpress.com)
  • Determining how this unusual chromosome segregation behavior is established is central to understanding germ cell development. (elifesciences.org)
  • We propose a model in which ObgE is required to license chromosome segregation and subsequent cell cycle events. (wiley.com)
  • The discovery made by this research, however, revealed that introns have functions that are extremely important to organisms during chromosome segregation. (eurekalert.org)
  • Diploid organisms contain two sets of chromosomes, one set inherited from the mother and the other from the father. (elifesciences.org)
  • The speed at which this occurs (reviewed in Gordon and Wright, 2000 ) rules out passive models for bacterial chromosome segregation, which proposed that outward cellular growth could drive the movement of a fixed chromosome. (wiley.com)