Y Chromosome: The male sex chromosome, being the differential sex chromosome carried by half the male gametes and none of the female gametes in humans and in some other male-heterogametic species in which the homologue of the X chromosome has been retained.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.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)Chromosome Mapping: Any method used for determining the location of and relative distances between genes on a chromosome.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.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)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.Sex Chromosome Aberrations: Abnormal number or structure of the SEX CHROMOSOMES. Some sex chromosome aberrations are associated with SEX CHROMOSOME DISORDERS and SEX CHROMOSOME DISORDERS OF SEX DEVELOPMENT.Chromosome Deletion: Actual loss of portion of a chromosome.Chromosome Aberrations: Abnormal number or structure of chromosomes. Chromosome aberrations may result in CHROMOSOME DISORDERS.Genes, Y-Linked: Genes that are located on the Y CHROMOSOME.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.Chromosomes, Human, Pair 1: A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.Chromosome Segregation: The orderly segregation of CHROMOSOMES during MEIOSIS or MITOSIS.Sex-Determining Region Y Protein: A transcription factor that plays an essential role in the development of the TESTES. It is encoded by a gene on the Y chromosome and contains a specific HMG-BOX DOMAIN that is found within members of the SOX family of transcription factors.Chromosomes, Plant: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of PLANTS.Karyotyping: Mapping of the KARYOTYPE of a cell.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, Bacterial: Structures within the nucleus of bacterial cells consisting of or containing DNA, which carry genetic information essential to the cell.Chromosomes, Human, Pair 7: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 11: A specific pair of GROUP C CHROMOSOMES 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.Chromosomes, Human, Pair 17: A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 21: A specific pair of GROUP G CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 6: A specific pair GROUP C CHROMSOMES of the human chromosome classification.Sex Chromosome Disorders of Sex Development: Congenital conditions of atypical sexual development associated with abnormal sex chromosome constitutions including MONOSOMY; TRISOMY; and MOSAICISM.Chromosome Pairing: The alignment of CHROMOSOMES at homologous sequences.Chromosomes, Human, Pair 9: A specific pair of GROUP C CHROMSOMES of the human chromosome classification.Chromosomes, Mammalian: Complex nucleoprotein structures which contain the genomic DNA and are part of the CELL NUCLEUS of MAMMALS.Oligospermia: A condition of suboptimal concentration of SPERMATOZOA in the ejaculated SEMEN to ensure successful FERTILIZATION of an OVUM. In humans, oligospermia is defined as a sperm count below 20 million per milliliter semen.Chromosomes, Fungal: Structures within the nucleus of fungal cells consisting of or containing DNA, which carry genetic information essential to the cell.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.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.Genetic Markers: A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.Seminal Plasma Proteins: Proteins found in SEMEN. Major seminal plasma proteins are secretory proteins from the male sex accessory glands, such as the SEMINAL VESICLES and the PROSTATE. They include the seminal vesicle-specific antigen, an ejaculate clotting protein; and the PROSTATE-SPECIFIC ANTIGEN, a protease and an esterase.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 2: A specific pair of human chromosomes in group A (CHROMOSOMES, HUMAN, 1-3) of the human chromosome classification.Chromosomes, Human, Pair 16: A specific pair of GROUP E 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 13: A specific pair of GROUP D 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)Infertility, Male: The inability of the male to effect FERTILIZATION of an OVUM after a specified period of unprotected intercourse. Male sterility is permanent infertility.Silene: A plant genus of the family CARYOPHYLLACEAE. The common name of campion is also used with LYCHNIS. The common name of 'pink' can be confused with other plants.Genes, sry: The primary testis-determining gene in mammalians, located on the Y CHROMOSOME. It codes for a high mobility group box transcription factor (TRANSCRIPTION FACTORS) which initiates the development of the TESTES from the embryonic GONADS.Chromosomes, Human, Pair 4: A specific pair of GROUP B CHROMOSOMES of the human chromosome classification.Chromosomes, Human, Pair 10: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Azoospermia: A condition of having no sperm present in the ejaculate (SEMEN).Haplotypes: The genetic constitution of individuals with respect to one member of a pair of allelic genes, or sets of genes that are closely linked and tend to be inherited together such as those of the MAJOR HISTOCOMPATIBILITY COMPLEX.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.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.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, Human, Pair 12: A specific pair of GROUP C CHROMOSOMES of the human chromosome classification.Sex Determination Analysis: Validation of the SEX of an individual by inspection of the GONADS and/or by genetic tests.Chromosomes, Human, Pair 5: One of the two pairs of human chromosomes in the group B class (CHROMOSOMES, HUMAN, 4-5).Sex Determination Processes: The mechanisms by which the SEX of an individual's GONADS are fixed.Sequence Tagged Sites: Short tracts of DNA sequence that are used as landmarks in GENOME mapping. In most instances, 200 to 500 base pairs of sequence define a Sequence Tagged Site (STS) that is operationally unique in the human genome (i.e., can be specifically detected by the polymerase chain reaction in the presence of all other genomic sequences). The overwhelming advantage of STSs over mapping landmarks defined in other ways is that the means of testing for the presence of a particular STS can be completely described as information in a database.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 15: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.Chromosomes, Insect: Structures within the CELL NUCLEUS of insect cells containing DNA.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).Chromosomes, Human, Pair 14: A specific pair of GROUP D CHROMOSOMES of the human chromosome classification.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Chromosomes, Human, Pair 18: A specific pair of GROUP E CHROMOSOMES of the human chromosome classification.Ring Chromosomes: Aberrant chromosomes with no ends, i.e., circular.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.Chromosome Breakage: A type of chromosomal aberration involving DNA BREAKS. Chromosome breakage can result in CHROMOSOMAL TRANSLOCATION; CHROMOSOME INVERSION; or SEQUENCE DELETION.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, 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.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.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.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.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.Gene Pool: The total genetic information possessed by the reproductive members of a POPULATION of sexually reproducing organisms.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.Mosaicism: The occurrence in an individual of two or more cell populations of different chromosomal constitutions, derived from a single ZYGOTE, as opposed to CHIMERISM in which the different cell populations are derived from more than one zygote.Genetic Variation: Genotypic differences observed among individuals in a population.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.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.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.Spermatogenesis: The process of germ cell development in the male from the primordial germ cells, through SPERMATOGONIA; SPERMATOCYTES; SPERMATIDS; to the mature haploid SPERMATOZOA.Chromosome Positioning: The mechanisms of eukaryotic CELLS that place or keep the CHROMOSOMES in a particular SUBNUCLEAR SPACE.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.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.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.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).Genetic Loci: Specific regions that are mapped within a GENOME. Genetic loci are usually identified with a shorthand notation that indicates the chromosome number and the position of a specific band along the P or Q arm of the chromosome where they are found. For example the locus 6p21 is found within band 21 of the P-arm of CHROMOSOME 6. Many well known genetic loci are also known by common names that are associated with a genetic function or HEREDITARY DISEASE.Turner Syndrome: A syndrome of defective gonadal development in phenotypic females associated with the karyotype 45,X (or 45,XO). Patients generally are of short stature with undifferentiated GONADS (streak gonads), SEXUAL INFANTILISM, HYPOGONADISM, webbing of the neck, cubitus valgus, elevated GONADOTROPINS, decreased ESTRADIOL level in blood, and CONGENITAL HEART DEFECTS. NOONAN SYNDROME (also called Pseudo-Turner Syndrome and Male Turner Syndrome) resembles this disorder; however, it occurs in males and females with a normal karyotype and is inherited as an autosomal dominant.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Sex Chromosome Disorders: Clinical conditions caused by an abnormal sex chromosome constitution (SEX CHROMOSOME ABERRATIONS), in which there is extra or missing sex chromosome material (either a whole chromosome or a chromosome segment).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.Chromosome Structures: Structures which are contained in or part of CHROMOSOMES.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.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.Genetics, Population: The discipline studying genetic composition of populations and effects of factors such as GENETIC SELECTION, population size, MUTATION, migration, and GENETIC DRIFT on the frequencies of various GENOTYPES and PHENOTYPES using a variety of GENETIC TECHNIQUES.Disorders of Sex Development: In gonochoristic organisms, congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. Effects from exposure to abnormal levels of GONADAL HORMONES in the maternal environment, or disruption of the function of those hormones by ENDOCRINE DISRUPTORS are included.Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.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.Drosophila melanogaster: A species of fruit fly much used in genetics because of the large size of its chromosomes.Testis: The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS.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.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).Polymerase Chain Reaction: In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships.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.Euchromatin: Chromosome regions that are loosely packaged and more accessible to RNA polymerases than HETEROCHROMATIN. These regions also stain differentially in CHROMOSOME BANDING preparations.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.Sequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Nucleic Acid Hybridization: Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)Sex Chromatin: In the interphase nucleus, a condensed mass of chromatin representing an inactivated X chromosome. Each X CHROMOSOME, in excess of one, forms sex chromatin (Barr body) in the mammalian nucleus. (from King & Stansfield, A Dictionary of Genetics, 4th ed)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).Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.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.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.Gene Dosage: The number of copies of a given gene present in the cell of an organism. An increase in gene dosage (by GENE DUPLICATION for example) can result in higher levels of gene product formation. GENE DOSAGE COMPENSATION mechanisms result in adjustments to the level GENE EXPRESSION when there are changes or differences in gene dosage.Emigration and Immigration: The process of leaving one's country to establish residence in a foreign country.Klinefelter Syndrome: A form of male HYPOGONADISM, characterized by the presence of an extra X CHROMOSOME, small TESTES, seminiferous tubule dysgenesis, elevated levels of GONADOTROPINS, low serum TESTOSTERONE, underdeveloped secondary sex characteristics, and male infertility (INFERTILITY, MALE). Patients tend to have long legs and a slim, tall stature. GYNECOMASTIA is present in many of the patients. The classic form has the karyotype 47,XXY. Several karyotype variants include 48,XXYY; 48,XXXY; 49,XXXXY, and mosaic patterns ( 46,XY/47,XXY; 47,XXY/48,XXXY, etc.).Trisomy: The possession of a third chromosome of any one type in an otherwise diploid cell.Blotting, Southern: A method (first developed by E.M. Southern) for detection of DNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.DNA Probes: Species- or subspecies-specific DNA (including COMPLEMENTARY DNA; conserved genes, whole chromosomes, or whole genomes) used in hybridization studies in order to identify microorganisms, to measure DNA-DNA homologies, to group subspecies, etc. The DNA probe hybridizes with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, Southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the DNA probe include the radioisotope labels 32P and 125I and the chemical label biotin. The use of DNA probes provides a specific, sensitive, rapid, and inexpensive replacement for cell culture techniques for diagnosing infections.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.Chromosome Duplication: An aberration in which an extra chromosome or a chromosomal segment is made.DNA, Mitochondrial: Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.Gonadoblastoma: A complex neoplasm composed of a mixture of gonadal elements, such as large primordial GERM CELLS, immature SERTOLI CELLS or GRANULOSA CELLS of the sex cord, and gonadal stromal cells. Gonadoblastomas are most often associated with gonadal dysgenesis, 46, XY.Genes, X-Linked: Genes that are located on the X CHROMOSOME.Karyotype: The full set of CHROMOSOMES presented as a systematized array of METAPHASE chromosomes from a photomicrograph of a single CELL NUCLEUS arranged in pairs in descending order of size and according to the position of the CENTROMERE. (From Stedman, 25th ed)Gonadal Dysgenesis: A number of syndromes with defective gonadal developments such as streak GONADS and dysgenetic testes or ovaries. The spectrum of gonadal and sexual abnormalities is reflected in their varied sex chromosome (SEX CHROMOSOMES) constitution as shown by the karyotypes of 45,X monosomy (TURNER SYNDROME); 46,XX (GONADAL DYSGENESIS, 46XX); 46,XY (GONADAL DYSGENESIS, 46,XY); and sex chromosome MOSAICISM; (GONADAL DYSGENESIS, MIXED). Their phenotypes range from female, through ambiguous, to male. This concept includes gonadal agenesis.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."Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.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.Siberia: A region, north-central Asia, largely in Russia. It extends from the Ural Mountains to the Pacific Ocean and from the Arctic Ocean to central Kazakhstan and the borders of China and Mongolia.Carica: A plant genus of the family Caricaceae, order Violales, subclass Dilleniidae, class Magnoliopsida. It is the source of edible fruit and PAPAIN.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.Tandem Repeat Sequences: Copies of DNA sequences which lie adjacent to each other in the same orientation (direct tandem repeats) or in the opposite direction to each other (INVERTED TANDEM REPEATS).Spermatozoa: Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.Sequence Homology, Nucleic Acid: The sequential correspondence of nucleotides in one nucleic acid molecule with those of another nucleic acid molecule. Sequence homology is an indication of the genetic relatedness of different organisms and gene function.XYY Karyotype: Abnormal genetic constitution in males characterized by an extra Y chromosome.Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Gene Duplication: Processes occurring in various organisms by which new genes are copied. Gene duplication may result in a MULTIGENE FAMILY; supergenes or PSEUDOGENES.Polynesia: The collective name for the islands of the central Pacific Ocean, including the Austral Islands, Cook Islands, Easter Island, HAWAII; NEW ZEALAND; Phoenix Islands, PITCAIRN ISLAND; SAMOA; TONGA; Tuamotu Archipelago, Wake Island, and Wallis and Futuna Islands. Polynesians are of the Caucasoid race, but many are of mixed origin. Polynesia is from the Greek poly, many + nesos, island, with reference to the many islands in the group. (From Webster's New Geographical Dictionary, 1988, p966 & Room, Brewer's Dictionary of Names, 1992, p426)Multigene Family: A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed)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.Genes: A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.Pseudogenes: Genes bearing close resemblance to known genes at different loci, but rendered non-functional by additions or deletions in structure that prevent normal transcription or translation. When lacking introns and containing a poly-A segment near the downstream end (as a result of reverse copying from processed nuclear RNA into double-stranded DNA), they are called processed genes.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.Azure Stains: PHENOTHIAZINES with an amino group at the 3-position that are green crystals or powder. They are used as biological stains.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.Gonadal Dysgenesis, Mixed: A type of defective gonadal development in patients with a wide spectrum of chromosomal mosaic variants. Their karyotypes are of partial sex chromosome monosomy resulting from an absence or an abnormal second sex chromosome (X or Y). Karyotypes include 45,X/46,XX; 45,X/46,XX/47,XXX; 46,XXp-; 45,X/46,XY; 45,X/47,XYY; 46,XYpi; etc. The spectrum of phenotypes may range from phenotypic female to phenotypic male including variations in gonads and internal and external genitalia, depending on the ratio in each gonad of 45,X primordial germ cells to those with normal 46,XX or 46,XY constitution.Platypus: A small aquatic oviparous mammal of the order Monotremata found in Australia and Tasmania.Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.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.Heterochromatin: The portion of chromosome material that remains condensed and is transcriptionally inactive during INTERPHASE.Polymorphism, Single Nucleotide: A single nucleotide variation in a genetic sequence that occurs at appreciable frequency in the population.Cytogenetic Analysis: Examination of CHROMOSOMES to diagnose, classify, screen for, or manage genetic diseases and abnormalities. Following preparation of the sample, KARYOTYPING is performed and/or the specific chromosomes are analyzed.Geography: The science dealing with the earth and its life, especially the description of land, sea, and air and the distribution of plant and animal life, including humanity and human industries with reference to the mutual relations of these elements. (From Webster, 3d ed)Cytogenetics: A subdiscipline of genetics which deals with the cytological and molecular analysis of the CHROMOSOMES, and location of the GENES on chromosomes, and the movements of chromosomes during the CELL CYCLE.Gene Frequency: The proportion of one particular in the total of all ALLELES for one genetic locus in a breeding POPULATION.Hybridization, Genetic: The genetic process of crossbreeding between genetically dissimilar parents to produce a hybrid.Fertility: The capacity to conceive or to induce conception. It may refer to either the male or female.Genes, Insect: The functional hereditary units of INSECTS.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.Rumex: A plant genus of the family POLYGONACEAE that contains patientosides and other naphthalene glycosides.Haploidy: The chromosomal constitution of cells, in which each type of CHROMOSOME is represented once. Symbol: N.Sex Ratio: The number of males per 100 females.Indians, South American: Individual members of South American ethnic groups with historic ancestral origins in Asia.Chromosomes, Artificial, Human: DNA constructs that are composed of, at least, all elements, such as a REPLICATION ORIGIN; TELOMERE; and CENTROMERE, required for successful replication, propagation to and maintainance in progeny human cells. In addition, they are constructed to carry other sequences for analysis or gene transfer.Kinetochores: Large multiprotein complexes that bind the centromeres of the chromosomes to the microtubules of the mitotic spindle during metaphase in the cell cycle.Cosmids: Plasmids containing at least one cos (cohesive-end site) of PHAGE LAMBDA. They are used as cloning vehicles.Receptors, Purinergic P2Y1: A subclass of purinergic P2Y receptors that have a preference for ATP and ADP. The activated P2Y1 receptor signals through the G-PROTEIN-coupled activation of PHOSPHOLIPASE C and mobilization of intracellular CALCIUM.DNA Transposable Elements: Discrete segments of DNA which can excise and reintegrate to another site in the genome. Most are inactive, i.e., have not been found to exist outside the integrated state. DNA transposable elements include bacterial IS (insertion sequence) elements, Tn elements, the maize controlling elements Ac and Ds, Drosophila P, gypsy, and pogo elements, the human Tigger elements and the Tc and mariner elements which are found throughout the animal kingdom.Judaism: The religion of the Jews characterized by belief in one God and in the mission of the Jews to teach the Fatherhood of God as revealed in the Hebrew Scriptures. (Webster, 3d ed)Chromosome Walking: A technique with which an unknown region of a chromosome can be explored. It is generally used to isolate a locus of interest for which no probe is available but that is known to be linked to a gene which has been identified and cloned. A fragment containing a known gene is selected and used as a probe to identify other overlapping fragments which contain the same gene. The nucleotide sequences of these fragments can then be characterized. This process continues for the length of the chromosome.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.Sex Differentiation: The process in developing sex- or gender-specific tissue, organ, or function after SEX DETERMINATION PROCESSES have set the sex of the GONADS. Major areas of sex differentiation occur in the reproductive tract (GENITALIA) and the brain.Chromosomes, Artificial: DNA constructs that are composed of, at least, elements such as a REPLICATION ORIGIN; TELOMERE; and CENTROMERE, that are required for successful replication, propagation to and maintenance in progeny cells. In addition, they are constructed to carry other sequences for analysis or gene transfer.H-Y Antigen: A sex-specific cell surface antigen produced by the sex-determining gene of the Y chromosome in mammals. It causes syngeneic grafts from males to females to be rejected and interacts with somatic elements of the embryologic undifferentiated gonad to produce testicular organogenesis.Genome, Human: The complete genetic complement contained in the DNA of a set of CHROMOSOMES in a HUMAN. The length of the human genome is about 3 billion base pairs.Founder Effect: A phenomenon that is observed when a small subgroup of a larger POPULATION establishes itself as a separate and isolated entity. The subgroup's GENE POOL carries only a fraction of the genetic diversity of the parental population resulting in an increased frequency of certain diseases in the subgroup, especially those diseases known to be autosomal recessive.Muridae: A family of the order Rodentia containing 250 genera including the two genera Mus (MICE) and Rattus (RATS), from which the laboratory inbred strains are developed. The fifteen subfamilies are SIGMODONTINAE (New World mice and rats), CRICETINAE, Spalacinae, Myospalacinae, Lophiomyinae, ARVICOLINAE, Platacanthomyinae, Nesomyinae, Otomyinae, Rhizomyinae, GERBILLINAE, Dendromurinae, Cricetomyinae, MURINAE (Old World mice and rats), and Hydromyinae.Chromosomal Instability: An increased tendency to acquire CHROMOSOME ABERRATIONS when various processes involved in chromosome replication, repair, or segregation are dysfunctional.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.Contig Mapping: Overlapping of cloned or sequenced DNA to construct a continuous region of a gene, chromosome or genome.Gene Rearrangement: The ordered rearrangement of gene regions by DNA recombination such as that which occurs normally during development.Dosage Compensation, Genetic: Genetic mechanisms that allow GENES to be expressed at a similar level irrespective of their GENE DOSAGE. This term is usually used in discussing genes that lie on the SEX CHROMOSOMES. Because the sex chromosomes are only partially homologous, there is a different copy number, i.e., dosage, of these genes in males vs. females. In DROSOPHILA, dosage compensation is accomplished by hypertranscription of genes located on the X CHROMOSOME. In mammals, dosage compensation of X chromosome genes is accomplished by random X CHROMOSOME INACTIVATION of one of the two X chromosomes in the female.Chromosome Fragility: Susceptibility of chromosomes to breakage leading to translocation; CHROMOSOME INVERSION; SEQUENCE DELETION; or other CHROMOSOME BREAKAGE related aberrations.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.Heterozygote: An individual having different alleles at one or more loci regarding a specific character.Quantitative Trait Loci: Genetic loci associated with a QUANTITATIVE TRAIT.Pan troglodytes: The common chimpanzee, a species of the genus Pan, family HOMINIDAE. It lives in Africa, primarily in the tropical rainforests. There are a number of recognized subspecies.Melanesia: The collective name for the islands of the Pacific Ocean northeast of Australia, including NEW CALEDONIA; VANUATU; New Hebrides, Solomon Islands, Admiralty Islands, Bismarck Archipelago, FIJI, etc. Melanesia (from the Greek melas, black + nesos, island) is so called from the black color of the natives who are generally considered to be descended originally from the Negroid Papuans and the Polynesians or Malays. (From Webster's New Geographical Dictionary, 1988, p748 & Room, Brewer's Dictionary of Names, 1992, p344)Chromosome Breakpoints: The locations in specific DNA sequences where CHROMOSOME BREAKS have occurred.Gonadal Dysgenesis, 46,XY: Defects in the SEX DETERMINATION PROCESS in 46, XY individuals that result in abnormal gonadal development and deficiencies in TESTOSTERONE and subsequently ANTIMULLERIAN HORMONE or other factors required for normal male sex development. This leads to the development of female phenotypes (male to female sex reversal), normal to tall stature, and bilateral streak or dysgenic gonads which are susceptible to GONADAL TISSUE NEOPLASMS. An XY gonadal dysgenesis is associated with structural abnormalities on the Y CHROMOSOME, a mutation in the GENE, SRY, or a mutation in other autosomal genes that are involved in sex determination.Genome: The genetic complement of an organism, including all of its GENES, as represented in its DNA, or in some cases, its RNA.Oryzias: The only genus in the family Oryziinae, order BELONIFORMES. Oryzias are egg-layers; other fish of the same order are livebearers. Oryzias are used extensively in testing carcinogens.Africa, Northern: The geographical area of Africa comprising ALGERIA; EGYPT; LIBYA; MOROCCO; and TUNISIA. It includes also the vast deserts and oases of the Sahara. It is often referred to as North Africa, French-speaking Africa, or the Maghreb. (From Webster's New Geographical Dictionary, 1988, p856)Selection, Genetic: Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population.Polymorphism, Restriction Fragment Length: Variation occurring within a species in the presence or length of DNA fragment generated by a specific endonuclease at a specific site in the genome. Such variations are generated by mutations that create or abolish recognition sites for these enzymes or change the length of the fragment.Transcription Factors: Endogenous substances, usually proteins, which are effective in the initiation, stimulation, or termination of the genetic transcription process.Spermatids: Male germ cells derived from the haploid secondary SPERMATOCYTES. Without further division, spermatids undergo structural changes and give rise to SPERMATOZOA.
PCDHY: PCDH11Y is a gene unique to human males which competes with FOXP2 for the title of the "language gene." PCDH11Y is the gene for making Protocadherin 11Y, a protein that guides the development of nerve cells.Premature chromosome condensation: Premature chromosome condensation (PCC) occurs in eukaryotic organisms when mitotic cells fuse with interphase cells. Chromatin, a substance that contains genetic material such as DNA, is normally found in a loose bundle inside a cell's nucleus.Chromosome regionsSmith–Fineman–Myers syndrome: Smith–Fineman–Myers syndrome (SFMS1), also called X-linked mental retardation-hypotonic facies syndrome 1 (MRXHF1), Carpenter–Waziri syndrome, Chudley–Lowry syndrome, SFMS, Holmes–Gang syndrome and Juberg–Marsidi syndrome (JMS), is a rare X-linked recessive congenital disorder that causes birth defects. This syndrome was named after 3 men, Richard D.Genetic imbalance: Genetic imbalance is to describe situation when the genome of a cell or organism has more copies of some genes than other genes due to chromosomal rearrangements or aneuploidy.Immortal DNA strand hypothesis: The immortal DNA strand hypothesis was proposed in 1975 by John Cairns as a mechanism for adult stem cells to minimize mutations in their genomes.Cairns, J.Circular bacterial chromosome: A circular bacterial chromosome is a bacterial chromosome in the form of a molecule of circular DNA. Unlike the linear DNA of most eukaryotes, typical bacterial chromosomes are circular.Transient neonatal diabetes mellitusFNA Mapping: Fine needle aspiration (FNA) cytology has been used to examine pathological human tissue from various organs for over 100 years.,Posner C.CAP protein family: In molecular biology, the CAP protein family (cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins (CAP)) is a large family of proteins that are found in a wide range of organisms, including prokaryotes and non-vertebrate eukaryotes. The nine subfamilies of the mammalian CAP 'super'family include: the human glioma pathogenesis-related 1 (GLIPR1), Golgi associated pathogenesis related-1 (GAPR1) proteins, peptidase inhibitor 15 (PI15), peptidase inhibitor 16 (PI16), cysteine-rich secretory proteins (CRISPs), CRISP LCCL domain containing 1 (CRISPLD1), CRISP LCCL domain containing 2 (CRISPLD2), mannose receptor like and the R3H domain containing like proteins.Male infertilitySilene undulataAzoospermiaGenetic linkage: Genetic linkage is the tendency of alleles that are located close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. Genes whose loci are nearer to each other are less likely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be genetically linked.Suresh Jayakar: Suresh Dinakar Jayakar (21 September 1937, Bombay-21 January 1988) was an Indian biologist who pioneered in the use of quantitative approaches in genetics and biology.Coles PhillipsMicrosatellite: A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from 2–5 base pairs) are repeated, typically 5-50 times. Microsatellites occur at thousands of locations in the human genome and they are notable for their high mutation rate and high diversity in the population.Symmetry element: A symmetry element is a point of reference about which symmetry operations can take place. In particular, symmetry elements can be centers of inversion, axes of rotation and mirror planes.Ring chromosome: A ring chromosome is a chromosome whose arms have fused together to form a ring. Ring chromosomes were first discovered by Lilian Vaughan Morgan in 1926.John Payne ToddMolecular evolution: Molecular evolution is a change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genetics to explain patterns in these changes.CentromereGene pool: The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species.Confined placental mosaicism: Confined placental mosaicism (CPM) represents a discrepancy between the chromosomal makeup of the cells in the placenta and the cells in the baby. CPM was first described by Kalousek and Dill in 1983.Genetic variation: right|thumbRecombination (cosmology): In cosmology, recombination refers to the epoch at which charged electrons and protons first became bound to form electrically neutral hydrogen atoms.Note that the term recombination is a misnomer, considering that it represents the first time that electrically neutral hydrogen formed.Oncogene: An oncogene is a gene that has the potential to cause cancer.Wilbur, Beth, editor.CP 55,940William Lakin Turner: William Lakin Turner (25 February 1867 – 21 October 1936) was an English landscape artist.Branching order of bacterial phyla (Gupta, 2001): There are several models of the Branching order of bacterial phyla, one of these was proposed in 2001 by Gupta based on conserved indels or protein, termed "protein signatures", an alternative approach to molecular phylogeny. Some problematic exceptions and conflicts are present to these conserved indels, however, they are in agreement with several groupings of classes and phyla.Silent mutation: Silent mutations are mutations in DNA that do not significantly alter the phenotype of the organism in which they occur. Silent mutations can occur in non-coding regions (outside of genes or within introns), or they may occur within exons.Infinite alleles model: The infinite alleles model is a mathematical model for calculating genetic mutations. The Japanese geneticist Motoo Kimura and American geneticist James F.Panmixia: Panmixia (or panmixis) means random mating.King C and Stanfield W.List of diseases (M): This is a list of diseases starting with the letter "M".Phenotype microarray: The phenotype microarray approach is a technology for high-throughput phenotyping of cells.Metaphase: Metaphase (from the Greek μετά, "adjacent" and φάσις, "stage") is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their second-most condensed and coiled stage (they are at their most condensed in anaphase. These chromosomes, carrying genetic information, align in the equator of the cell before being separated into each of the two daughter cells.
(1/1444) Mitotic recombination in the heterochromatin of the sex chromosomes of Drosophila melanogaster.
The frequency of spontaneous and X-ray-induced mitotic recombination involving the Y chromosome has been studied in individuals with a marked Y chromosome arm and different XY compound chromosomes. The genotypes used include X chromosomes with different amounts of X heterochromatin and either or both arms of the Y chromosome attached to either side of the centromere. Individuals with two Y chromosomes have also been studied. The results show that the bulk of mitotic recombination takes place between homologous regions. (+info)
(2/1444) Germ cell development in the XXY mouse: evidence that X chromosome reactivation is independent of sexual differentiation.
Prior to entry into meiosis, XX germ cells in the fetal ovary undergo X chromosome reactivation. The signal for reactivation is thought to emanate from the genital ridge, but it is unclear whether it is specific to the developing ovary. To determine whether the signals are present in the developing testis as well as the ovary, we examined the expression of X-linked genes in germ cells from XXY male mice. To facilitate this analysis, we generated XXY and XX fetuses carrying X chromosomes that were differentially marked and subject to nonrandom inactivation. This pattern of nonrandom inactivation was maintained in somatic cells but, in XX as well as XXY fetuses, both parental alleles were expressed in germ cell-enriched cell populations. Because testis differentiation is temporally and morphologically normal in the XXY testis and because all germ cells embark upon a male pathway of development, these results provide compelling evidence that X chromosome reactivation in fetal germ cells is independent of the somatic events of sexual differentiation. Proper X chromosome dosage is essential for the normal fertility of male mammals, and abnormalities in germ cell development are apparent in the XXY testis within several days of X reactivation. Studies of exceptional germ cells that survive in the postnatal XXY testis demonstrated that surviving germ cells are exclusively XY and result from rare nondisjunctional events that give rise to clones of XY cells. (+info)
(3/1444) Sexual dimorphism in white campion: complex control of carpel number is revealed by y chromosome deletions.
Sexual dimorphism in the dioecious plant white campion (Silene latifolia = Melandrium album) is under the control of two main regions on the Y chromosome. One such region, encoding the gynoecium-suppressing function (GSF), is responsible for the arrest of carpel initiation in male flowers. To generate chromosomal deletions, we used pollen irradiation in male plants to produce hermaphroditic mutants (bsx mutants) in which carpel development was restored. The mutants resulted from alterations in at least two GSF chromosomal regions, one autosomal and one located on the distal half of the (p)-arm of the Y chromosome. The two mutations affected carpel development independently, each mutation showing incomplete penetrance and variegation, albeit at significantly different levels. During successive meiotic generations, a progressive increase in penetrance and a reduction in variegation levels were observed and quantified at the level of the Y-linked GSF (GSF-Y). Possible mechanisms are proposed to explain the behavior of the bsx mutations: epigenetic regulation or/and second-site mutation of modifier genes. In addition, studies on the inheritance of the hermaphroditic trait showed that, unlike wild-type Y chromosomes, deleted Y chromosomes can be transmitted through both the male and the female lines. Altogether, these findings bring experimental support, on the one hand, to the existence on the Y chromosome of genic meiotic drive function(s) and, on the other hand, to models that consider that dioecy evolved through multiple mutation events. As such, the GSF is actually a system containing more than one locus and whose primary component is located on the Y chromosome. (+info)
(4/1444) Sexual dimorphism in white campion: deletion on the Y chromosome results in a floral asexual phenotype.
White campion is a dioecious plant with heteromorphic X and Y sex chromosomes. In male plants, a filamentous structure replaces the pistil, while in female plants the stamens degenerate early in flower development. Asexual (asx) mutants, cumulating the two developmental defects that characterize the sexual dimorphism in this species, were produced by gamma ray irradiation of pollen and screening in the M1 generation. The mutants harbor a novel type of mutation affecting an early function in sporogenous/parietal cell differentiation within the anther. The function is called stamen-promoting function (SPF). The mutants are shown to result from interstitial deletions on the Y chromosome. We present evidence that such deletions tentatively cover the central domain on the (p)-arm of the Y chromosome (Y2 region). By comparing stamen development in wild-type female and asx mutant flowers we show that they share the same block in anther development, which results in the production of vestigial anthers. The data suggest that the SPF, a key function(s) controlling the sporogenous/parietal specialization in premeiotic anthers, is genuinely missing in females (XX constitution). We argue that this is the earliest function in the male program that is Y-linked and is likely responsible for "male dimorphism" (sexual dimorphism in the third floral whorl) in white campion. More generally, the reported results improve our knowledge of the structural and functional organization of the Y chromosome and favor the view that sex determination in this species results primarily from a trigger signal on the Y chromosome (Y1 region) that suppresses female development. The default state is therefore the ancestral hermaphroditic state. (+info)
(5/1444) Y chromosome and male infertility.
Recent genome analysis of the Y chromosome has increased the number of genes found on this chromosome markedly. Many of these genes in the part of the Y chromosome that does not undergo recombination with the X chromosome are members of gene families. Evolutionary considerations imply that genes on the Y chromosome will degenerate unless they have male advantageous or female deleterious functions. Spermatogenesis is an example of a male advantageous function and genes in three regions of the human Y chromosome have been promoted as candidate male fertility factors. (+info)
(6/1444) Ancestral Asian source(s) of new world Y-chromosome founder haplotypes.
Haplotypes constructed from Y-chromosome markers were used to trace the origins of Native Americans. Our sample consisted of 2,198 males from 60 global populations, including 19 Native American and 15 indigenous North Asian groups. A set of 12 biallelic polymorphisms gave rise to 14 unique Y-chromosome haplotypes that were unevenly distributed among the populations. Combining multiallelic variation at two Y-linked microsatellites (DYS19 and DXYS156Y) with the unique haplotypes results in a total of 95 combination haplotypes. Contra previous findings based on Y- chromosome data, our new results suggest the possibility of more than one Native American paternal founder haplotype. We postulate that, of the nine unique haplotypes found in Native Americans, haplotypes 1C and 1F are the best candidates for major New World founder haplotypes, whereas haplotypes 1B, 1I, and 1U may either be founder haplotypes and/or have arrived in the New World via recent admixture. Two of the other four haplotypes (YAP+ haplotypes 4 and 5) are probably present because of post-Columbian admixture, whereas haplotype 1G may have originated in the New World, and the Old World source of the final New World haplotype (1D) remains unresolved. The contrasting distribution patterns of the two major candidate founder haplotypes in Asia and the New World, as well as the results of a nested cladistic analysis, suggest the possibility of more than one paternal migration from the general region of Lake Baikal to the Americas. (+info)
(7/1444) Long-term fetal microchimerism in peripheral blood mononuclear cell subsets in healthy women and women with scleroderma.
Fetal CD34(+) CD38(+) cells have recently been found to persist in maternal peripheral blood for many years after pregnancy. CD34(+) CD38(+) cells are progenitor cells that can differentiate into mature immune-competent cells. We asked whether long-term fetal microchimerism occurs in T lymphocyte, B lymphocyte, monocyte, and natural-killer cell populations of previously pregnant women. We targeted women with sons and used polymerase chain reaction for a Y-chromosome-specific sequence to test DNA extracted from peripheral blood mononuclear cells (PBMC) and from CD3, CD19, CD14, and CD56/16 sorted subsets. We also asked whether persistent microchimerism might contribute to subsequent autoimmune disease in the mother and included women with the autoimmune disease scleroderma. Scleroderma has a peak incidence in women after childbearing years and has clinical similarities to chronic graft-versus-host disease that occurs after allogeneic hematopoietic stem-cell transplantation, known to involve chimerism. Sixty-eight parous women were studied for male DNA in PBMC and 20 for PBMC subsets. Microchimerism was found in PBMC from 33% (16 of 48) of healthy women and 60% (12 of 20) women with scleroderma, P =.046. Microchimerism was found in some women in CD3, CD19, CD14, and CD56/16 subsets including up to 38 years after pregnancy. Microchimerism in PBMC subsets was not appreciably more frequent in scleroderma patients than in healthy controls. Overall, microchimerism was found in CD3, CD19, and CD14 subsets in approximately one third of women and in CD56/16 in one half of women. HLA typing of mothers and sons indicated that HLA compatibility was not a requirement for persistent microchimerism in PBMC subsets. Fetal microchimerism in the face of HLA disparity implies that specific maternal immunoregulatory pathways exist that permit persistence but prevent effector function of these cells in normal women. Although microchimerism in PBMC was more frequent in women with scleroderma than healthy controls additional studies will be necessary to determine whether microchimerism plays a role in the pathogenesis of this or other autoimmune diseases. (+info)
(8/1444) Preimplantation diagnosis by fluorescence in situ hybridization using 13-, 16-, 18-, 21-, 22-, X-, and Y-chromosome probes.
PURPOSE: Our purpose was to select the proper chromosomes for preimplantation diagnosis based on aneuploidy distribution in abortuses and to carry out a feasibility study of preimplantation diagnosis for embryos using multiple-probe fluorescence in situ hybridization (FISH) on the selected chromosomes of biopsied blastomeres. METHODS: After determining the frequency distribution of aneuploidy found in abortuses, seven chromosomes were selected for FISH probes. Blastomeres were obtained from 33 abnormal or excess embryos. The chromosome complements of both the biopsied blastomeres and the remaining sibling blastomeres in each embryo were determined by FISH and compared to evaluate their preimplantation diagnostic potential. RESULTS: Chromosomes (16, 22, X, Y) and (13, 18, 21) were selected on the basis of the high aneuploid prevalence in abortuses for the former group and the presence of trisomy in the newborn for the latter. Thirty-six (72%) of 50 blastomeres gave signals to permit a diagnosis. Diagnoses made from biopsied blastomeres were consistent with the diagnoses made from the remaining sibling blastomeres in 18 embryos. In only 2 of 20 cases did the biopsied blastomere diagnosis and the embryo diagnosis not match. CONCLUSIONS: If FISH of biopsied blastomere was successful, a preimplantation diagnosis could be made with 10% error. When a combination of chromosome-13, -16, -18, -21, -22, -X, and -Y probes was used, up to 65% of the embryos destined to be aborted could be detected. (+info)