Meiosis is a key step for sexual reproduction in which chromosome number is halved by two successive meiotic divisions after a single round of DNA replication. In the first meiotic division (meiosis I), homologous chromosomes pair, synapse, and recombine with their partners in prophase I. As a result, homologous chromosomes are physically connected until metaphase I and then segregated from eac...

In many organisms, the rate of genetic recombination is not uniform along the length of chromosomes or between sexes. To compare the relative recombination rates during meiosis in male and female zebrafish, we constructed a genetic map based on male meiosis. We developed a meiotic mapping panel of 94 androgenetic haploid embryos that were scored for genetic polymorphisms. The resulting male map...

The two alleles at a heterozygous locus segregate during meiosis, sometimes at meiosis I and sometimes at meiosis II. The timing of segregation is determined by the pattern of crossing-over between a locus and its attached centromeres. Genes near centromeres can exploit this process by driving against spores from which the genes separated at meiosis I. Other genes, located distal to centromeres...

In the absence of Spo13, budding yeast cells complete a single meiotic division during which sister chromatids often separate. We investigated the function of Spo13 by following chromosomes tagged with green fluorescent protein. The occurrence of a single division in spo13Delta homozygous diploids depends on the spindle checkpoint. Eliminating the checkpoint accelerates meiosis I in spo13Delta ...

Meiosis encompasses a large number of dynamic processes. Some of them are biochemical, such as formation and repair of meiotic double-strand breaks, while others are physical in nature, such as homologous chromosome segregation in anaphase I. Plants have been used as model species in meiosis studies for over 80 years. However, the past decade brought a dramatic improvement in the understanding ...

background: the aim of this study was to assess effects of cysteamine as an anti-oxidant on rate of in vitro maturation of oocyte and determination of its effects on spindle size and shape. methods: pre-mature mice were primed with pregnant mare stimulating gonadotrophin (pmsg) and germinal vesicle (gv) stage oocytes were obtained 48 h after. the oocytes were cultured in tissue culture medium (...

To ensure genome stability, sexually reproducing organisms require that mating brings together exactly 2 haploid gametes and meiosis occurs only in diploid zygotes. In the fission yeast Schizosaccharomyces pombe , fertilization triggers Mei3-Pat1-Mei2 signaling cascade, which represses subsequent initiates meiosis. Here, we establish a degron system to specifically degrade proteins postfusion d...

Abstract The molecular machinery and chromosome structures carrying out meiosis are frequently conserved from yeast to mammals. However, signals initiating appear divergent: while nutrient restriction induces in the system, retinoic acid (RA) its target Stra8 have been shown be necessary but not sufficient induce meiotic initiation mammalian germ cells. Here, we use primary culture of mouse und...

CENP-A (CID in flies) is the histone H3 variant essential for centromere specification, kinetochore formation, and chromosome segregation during cell division. Recent studies have elucidated major cell cycle mechanisms and factors critical for CENP-A incorporation in mitosis, predominantly in cultured cells. However, we do not understand the roles, regulation, and cell cycle timing of CENP-A as...

Meiosis is often described as a special case of cell division since it differs from mitosis in having two nuclear divisions without an intervening S-phase. It will be of great interest to uncover what molecular mechanisms underlie these special features of meiosis. We previously reported that the tardy asynchronous meiosis (tam) mutant of Arabidopsis (Arabidopsis thaliana) is slower in cell cyc...