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  • homologous
  • Second, the neo-sex chromosome is homologous to the sex chromosomes of mammals, which makes it possible - for the first time - to study mammalian X gene homologs in a novel, avian Z-linked environment where females are the heterogametic sex (ZW), and thus to draw direct parallels over the avian ZW-mammalian XY boundary. (lu.se)
  • chromosomal
  • Most likely this suppression was the result of a series of chromosomal inversions on the Y chromosome, which would also explain why the genes appear to be in order on the X but scrambled on the Y," Page explains. (abc.net.au)
  • locus
  • The selected Xi becomes the target of a chromosome‐wide mechanism of transcriptional silencing, which constitutes an exciting paradigm for epigenetic regulations and confirms interest in the molecular dissection of the X‐inactivation centre ( Xic ), a locus on the X chromosome that contains the Xist gene and the elements involved in counting, choice and silencing. (embopress.org)
  • AMONG species with genetic sex determination, sex is determined in the vast majority by a single locus or chromosome ( B ull 1983 ). (genetics.org)
  • Genetic
  • This lack of detailed knowledge about sex chromosome evolution compromises our understanding of fundamental biological questions (e.g. the evolution of sexual conflicts) as well as more practical ones (e.g. about sex-linked genetic diseases). (lu.se)
  • possess
  • In particular, females with Turner's syndrome (TS) who have only one X-chromosome exhibit deficits of spatial ability whereas males with Klinefelter's syndrome (KS) who possess a supernumerary X-chromosome are delayed in acquiring words. (ox.ac.uk)
  • Female ES cells possess two active X chromosomes and recapitulate random XCI when induced to differentiate. (embopress.org)
  • mechanism
  • The mechanism by which specific regions of the chromosome are organized and segregated prior to division remains a mystery. (wiley.com)
  • human
  • The improper partitioning of chromosomes is responsible for a many human maladies. (omrf.org)
  • In addition, we have recently determined that the spindle checkpoint is especially important for the segregation of error-prone meiotic chromosomes and that the human spindle checkpoint protein, BubR1, can participate in this process in yeast. (omrf.org)
  • Nevertheless, many genes on the human Y chromosome have homologues (analogous genes) on the X chromosome. (abc.net.au)
  • The reconstruction of the defining events of human sex-chromosome evolution is analogous to the reconstruction of the evolution of species, except that we are looking at changes of a pair of chromosomes over geologic time rather than changes of whole organisms," says Lahn. (abc.net.au)
  • The PAR1 spans the first 2.7 Mb of the proximal arm of the human sex chromosomes, while the much smaller PAR2 encompasses the distal 320 kb of the long arm of each sex chromosome. (genetics.org)
  • cellular
  • 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)
  • 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. (omrf.org)
  • This system has allowed us to describe the cellular processes that are used to correctly partition the error-prone chromosomes in most meioses. (omrf.org)
  • discovery
  • Ever since their discovery, these chromosomes have captivated researchers because of their obvious involvement in fundamental aspects of an organism's life, such as sex determination, sexual reproduction and sexual conflicts. (lu.se)
  • events
  • We propose a model in which ObgE is required to license chromosome segregation and subsequent cell cycle events. (wiley.com)
  • The first events that created the sex chromosomes had been thought to have occurred at least 170 million years ago," says researcher Dr David Page. (abc.net.au)
  • By fossil digging on the sex chromosomes, we were able to reconstruct the four events that drove sex chromosomes into their distinctive X and Y forms, and to date when these events occurred during evolution," says Lahn. (abc.net.au)
  • development
  • The findings suggest that the number of sex chromosomes influences the development of brain asymmetry not simply to modify the torque but in a complex pattern along the antero-posterior axis. (ox.ac.uk)
  • found
  • No increased risk for AML with complex CCA or with total or partial losses of chromosomes 5 or 7 were observed, but a higher risk was found for AML with trisomy 8 (OR 11, 95% CI 2.7-42) as the sole aberration. (sjweh.fi)
  • The X chromosome was found to have four groups of genes physically arranged as four consecutive blocks, like the layers of rock in geological strata. (abc.net.au)
  • move
  • In the 'extrusion-capture' model, replication through an anchored replisome provides the force to move daughter chromosomes to the poles ( Lemon and Grossman, 2001 ). (wiley.com)
  • research
  • The research in our laboratory is focused on both the regulatory and mechanical aspects of chromosome behavior. (omrf.org)
  • Research published in this week's Science reveals that the Y chromosome developed from an X-like ancestor around 300 million years ago. (abc.net.au)
  • early
  • In this chapter, we summarise current knowledge of errors in chromosome segregation during oogenesis and early embryogenesis, with special reference to the clinical implications for successful assisted reproduction. (warwick.ac.uk)
  • function
  • Specifically, we tested Crow's prediction that the magnitude of the brain torque (i.e., a combination of rightward frontal and leftward occipital asymmetry) would, as a function of sex chromosome dosage, be respectively decreased in TS women and increased in KS men, relative to genotypically normal controls. (ox.ac.uk)
  • Female
  • X chromosome inactivation (XCI), which occurs only in female (XX) and not in male (XY) embryos, ensures dosage compensation of X‐linked genes between the sexes. (embopress.org)
  • supernumerary chromosomes
  • Supernumerary chromosomes that confer an adaptive advantage in certain habitats, such as the ability to cause disease on a specific host, may be referred to as "conditionally dispensable" chromosomes in order to reflect their importance in some, but not all, growth conditions. (springer.com)
  • In addition to describing the structural and functional characteristics of known supernumerary chromosomes in fungi, this review discusses the relative merits of the terms that have been used to describe them, and establishes experimental criteria for their identification. (springer.com)
  • sequences
  • Moreover, lampbrush chromosomes are widely used for high-resolution mapping of DNA sequences and construction of detail cytological maps of individual chromosomes. (wikipedia.org)
  • This re-estimation of the age of the therian XY system is based on the finding that sequences that are on the X chromosomes of marsupials and eutherian mammals are present on the autosomes of platypus and birds. (wikipedia.org)
  • The older estimate was based on erroneous reports that the platypus X chromosomes contained these sequences. (wikipedia.org)
  • nucleus
  • Amphibian and avian lampbrush chromosomes can be microsurgically isolated from oocyte nucleus (germinal vesicle) with either forceps or needles. (wikipedia.org)
  • Next, the cells are dropped onto a microscope slide so that the nucleus, which holds all of the genetic material together, breaks apart and releases the chromosomes onto the slide. (wikipedia.org)
  • The chromosome territory concept holds that despite this apparent disorder, chromosomes largely occupy defined regions of the nucleus. (wikipedia.org)
  • segregation
  • In animal cells, chromosomes reach their highest compaction level in anaphase during segregation. (wikipedia.org)
  • Normal cells make errors in chromosome segregation in 1% of cell divisions, whereas cells with CIN make these errors approximately 20% of cell divisions. (wikipedia.org)
  • Upon proper segregation, a complete set of chromatids ends up in each of two nuclei, and when cell division is completed, each DNA copy previously referred to as a chromatid is now called a chromosome. (wikipedia.org)
  • Improper chromosome segregation can result in aneuploid gametes having either too few or too many chromosomes. (wikipedia.org)
  • Chromatin
  • Some use the term chromosome in a wider sense, to refer to the individualized portions of chromatin in cells, either visible or not under light microscopy. (wikipedia.org)
  • Lampbrush chromosomes are clearly visible even in the light microscope, where they are seen to be organized into a series of chromomeres with large chromatin loops extended laterally. (wikipedia.org)
  • disorders
  • Founded, supported, and run by parents just like you, for over 25 years CDO has been supporting those born with rare chromosome disorders. (chromodisorder.org)
  • Individuals, families and medical professionals all provide vital information and help to raise awareness and understanding of rare chromosome disorders. (chromodisorder.org)
  • Help us in our efforts to raise awareness of rare chromosome disorders by visiting our online store. (chromodisorder.org)
  • Known human disorders include Charcot-Marie-Tooth disease type 1A , which may be caused by duplication of the gene encoding peripheral myelin protein 22 (PMP22) on chromosome 17. (wikipedia.org)
  • Human genetic disorders can be caused by ring chromosome formation. (wikipedia.org)
  • citation needed] In the future, chromosome engineering will experiment in removing more common disorders such as asthma, diabetes, and cancer. (wikipedia.org)
  • Clarence Erwin M
  • She realized that the previous idea of Clarence Erwin McClung, that the X chromosome determines sex, was wrong and that sex determination is, in fact, due to the presence or absence of the Y chromosome. (wikipedia.org)
  • It was first suggested that the X chromosome was involved in sex determination by Clarence Erwin McClung in 1901 after comparing his work on locusts with Henking's and others. (wikipedia.org)
  • inactivation
  • Dupont C and Gribnau J (2013) Different flavors of X‐chromosome inactivation in mammals. (els.net)
  • If X-inactivation in the somatic cell meant a complete de-functionalizing of one of the X-chromosomes, it would ensure that females, like males, had only one functional copy of the X chromosome in each somatic cell. (wikipedia.org)
  • Inheritance
  • Aided by the rediscovery at the start of the 1900s of Gregor Mendel's earlier work, Boveri was able to point out the connection between the rules of inheritance and the behaviour of the chromosomes. (wikipedia.org)
  • In his famous textbook The Cell in Development and Heredity, Wilson linked together the independent work of Boveri and Sutton (both around 1902) by naming the chromosome theory of inheritance the Boveri-Sutton chromosome theory (the names are sometimes reversed). (wikipedia.org)
  • Luke Hutchison noticed that a number of possible ancestors on the X chromosome inheritance line at a given ancestral generation follows the Fibonacci sequence. (wikipedia.org)
  • spans
  • Chromosome 16 spans about 90 million base pairs (the building material of DNA) and represents just under 3% of the total DNA in cells . (wikipedia.org)
  • Chromosome 20 spans around 63 million base pairs (the building material of DNA ) and represents between 2 and 2.5 percent of the total DNA in cells . (wikipedia.org)
  • alleles
  • In other instances, the presence of one of the two alleles of the sex‐determining gene on both chromosomes led to the differentiation of one sex, whereas its presence on only one of the two autosomes led to the differentiation of the other sex. (els.net)
  • sperm
  • McClung noted that only half the sperm received an X chromosome. (wikipedia.org)
  • Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in nearly all somatic cells (cells other than egg and sperm cells). (wikipedia.org)
  • homology
  • Platypus sex chromosomes in fact appear to bear a much stronger homology (similarity) with the avian Z chromosome, and the SRY gene so central to sex-determination in most other mammals is apparently not involved in platypus sex-determination. (wikipedia.org)