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  • 1
    Unknown
    Amsterdam : Academic
    Call number: QH442:204(3)
    Keywords: Human gene mapping ; Human genome ; Human Genetics
    Notes: First ed. by R. Scott Hawley and Catherine A. Mori.
    Pages: xiv, 585 p. : ill.
    Edition: 3rd ed.
    ISBN: 978-0-12-333445-9
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    QH442:204(3) available
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  • 2
    Unknown
    Cold Spring Harbor, N.Y. : Cold Spring Harbor Laboratory Press
    Call number: A0700:4 ; B110:6 ; B140:2
    Keywords: Drosophila
    Pages: xiv, 697 p. : ill. (some col.)
    ISBN: 978-0-87969-586-6
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    A0700:4 departmental collection or stack – please contact the library
    B110:6 departmental collection or stack – please contact the library
    B140:2 departmental collection or stack – please contact the library
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  • 3
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. This paper reports on a new role for mei-41 in cell cycle control during meiosis. This function is revealed by the requirement of mei-41 for the precocious anaphase observed in crossover-defective mutants. Normally in Drosophila oocytes, tension on the meiotic spindle causes a metaphase I arrest. This tension results because crossovers, and the resulting chiasmata, hold homologs together that are being pulled by kinetochore microtobules toward opposite spindle poles. In the absence of tension, such as in a recombination-defective mutant, metaphase arrest is not observed and meiosis proceeds through the two divisions. Here we show that in some recombination-defective mutants, the precocious anaphase requires the mei-41 gene product. For example, metaphase arrest is not observed in mei-218 mutants because of the severe reduction in crossing over. In mei-41 mei-218 double mutants, however, metaphase arrest was restored. The effect of mei-41 is dependent on double-strand break formation. Thus, in mutants that fail to initiate meiotic recombination the absence of mei-41 has no effect.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Homologous chromosomes initially undergo weak alignments that bring homologous sequences into register during meiosis. These alignments can be facilitated by two types of mechanisms: interstitial homology searches and telomere-telomere alignments. As prophase (and chromatin compaction) proceeds, these initial pairings or alignments need to be stabilized. In at least some organisms, such as Saccharomyces cerevisiae and S. pombe, these pairings can apparently be maintained by the creation of recombination intermediates. In contrast, synapsis during zygotene may be able to facilitate and/or maintain chromosome pairing even in the absence of exchange in several higher organisms. It thus seems possible that the synaptonemal complex plays a role both in maintaining homolog adhesion during meiotic prophase and, more speculatively, in facilitating meiotic exchange.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1617-4623
    Keywords: Drosophila melanogaster ; Kinesin ; Meiosis ; Mutagenesis ; Nod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have analyzed a collection of 12 mutations in the Drosophila melanogaster nod locus, which encodes a kinesin-like protein involved in female meiotic chromosome segregation. The kinesin-like domain is at the N-terminus of the protein, while the C-terminal portion of the protein is unique. Four of the mutations are missense and affect highly conserved domains of the kinesin-like portion of the predicted protein, and thus demonstrate that the sequence conservation is biologically relevant. Surprisingly, two other mutations, which behave genetically as null alleles, are the result of mutations in the last exon of the nod gene. Thus, these two mutations affect the most C-terminal residues in the unique portion of the predicted protein. Based on these mutations, we suggest that this part of the protein may also be essential for wild-type function. The mutations were induced by either gamma-rays or ethyl methanesulfonate (EMS). All of the gamma-ray induced mutations were small or large chromosomal rearrangements, while all of the EMS mutations were G → A transitions. These findings are consistent with the biochemical basis of the mode of action of each mutagen.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0192-253X
    Keywords: Meiosis ; heterochromatin ; homology ; pairing ; segregation ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: There are numerous examples of the regular segregation of achiasmate chromosomes at meiosis I in Drosophila melanogaster females. Classically, the choice of achiasmate segregational partners has been thought to be independent of homology, but rather made on the basis of availability or similarities in size and shape. To the contrary, we show here that heterochromatic homology plays a primary role in ensuring the proper segregation of achiasmate homologs. We observe that the heterochromatin of chromosome 4 functions as, or contains, a meiotic pairing site. We show that free duplications carrying the 4th chromosome pericentric heterochromatin induce high frequencies of 4th chromosome nondisjunction regardless of their size. Moreover, a duplication from which some of the 4th chromosome heterochromatin has been removed is unable to induce 4th chromosome nondisjunction. Similarly, in the absence of either euchromatic homology or a size similarity, duplications bearing the X chromosome heterochromatin also disrupt the segregation of two achiasmate X chromosome centromeres. Although heterochromatic regions are sufficient to conjoin nonexchange homologues, we confirm that the segregation of heterologous chromosomes is determined by size, shape, and availability. The meiotic mutation Axs differentiates between these two processes of achiasmate centromere coorientation by disrupting only the homology-dependent mechanism. Thus there are two different mechanisms by which achiasmate segregational partners are chosen. We propose that the absence of diplotene-diakinesis during female meiosis allows heterochromatic pairings to persist until prometaphase and thus to co-orient homologous centromeres. We also propose that heterologous disjunctions result from a separate and homology-independent process that likely occurs during prometaphase. The latter process, which may not require the physical association of segregational partners, is similar to those observed in many insects, in Saccharomyces cerevisiae and in C. elegans males. We also suggest that the physical basis of this process may reflect known properties of the Drosophila meiotic spindle. © 1993 Wiley-Liss, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Recent studies of human oocytes have demonstrated an enrichment for distal exchanges among meiosis I (MI) nondisjunction events and for proximal exchanges among meiosis II (MII) events. Our characterization of 103 cases of spontaneous X chromosome nondisjunction in Drosophila oocytes strongly ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    ISSN: 1081-0706
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: The synaptonemal complex (SC) is a protein lattice that resembles railroad tracks and connects paired homologous chromosomes in most meiotic systems. The two side rails of the SC, known as lateral elements (LEs), are connected by proteins known as transverse filaments. The LEs are derived from the axial elements of the chromosomes and play important roles in chromosome condensation, pairing, transverse filament assembly, and prohibiting double-strand breaks (DSBs) from entering into recombination pathways that involve sister chromatids. The proteins that make up the transverse filaments of the SC also play a much earlier role in committing a subset of DSBs into a recombination pathway, which results in the production of reciprocal meiotic crossovers. Sites of crossover commitment can be observed as locations where the SC initiates and as immunostaining foci for a set of proteins required for the processing of DSBs to mature crossovers. In most (but not all) organisms it is the establishment of sites marking such crossover-committed DSBs that facilitates completion of synapsis (full-length extension of the SC). The function of the mature full-length SC may involve both the completion of meiotic recombination at the DNA level and the exchange of the axial elements of the two chromatids involved in the crossover. However, the demonstration that the sites of crossover formation are designated prior to SC formation, and the finding that these sites display interference, argues against a role of the mature SC in mediating the process of interference. Finally, in at least some organisms, modifications of the SC alone are sufficient to ensure meiotic chromosome segregation in the complete absence of meiotic recombination.
    Type of Medium: Electronic Resource
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  • 9
    Keywords: Drosophila melanogaster / Genetics ; Drosophila / genetics ; Female ; Meiosis / genetics
    Description / Table of Contents: Contents: Identification of genetic material -- The central dogma of meiosis -- Nondisjunction frequencies for the Drosophila genome -- A revised view of meiosis -- Chromosome segregation -- A mutational approach to understanding the meiotic process -- Development of tools to study meiosis in Drosophila females -- The 1996 P element screen -- Genes defined by our first large-scale screen for new meiotic mutants -- The 2004 ‘FLP-FRT’ screen -- Germline clone screen -- Achiasmate (nonexchange) segregations are preceded by heterochromatic pairings -- Mtrm and Polo
    Notes: Animated audio-visual presentation with synchronized narration.
    Pages: 1 streaming video file (53 min.) : digital, mono., SWF file, sd., col.
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