Meiosis is a process of importance for sexually reproducing eukaryotic organisms. In the fission yeast Schizosaccharomyces pombe, meiosis normally proceeds in a diploid zygote which is produced by conjugation of haploid cells of opposite mating types. We demonstrate that activation of the pheromone-responsive MAPK, Spk1, by the ectopic expression of a constitutively active form of Byr1 (MAPKK f...

Background Gametes are generated through a specialized cell division called meiosis, in which ploidy is reduced by half because two consecutive rounds of chromosome segregation, meiosis I and meiosis II, occur without intervening DNA replication. This contrasts with the mitotic cell cycle where DNA replication and chromosome segregation alternate to maintain the same ploidy. At the end of mitos...

In meiosis in male fruitflies, chromosome pairing events do not facilitate genetic exchange, but rather create bivalents that can be sequestered to discrete pockets of the prophase nucleus. This assignment of homologs to a common pocket likely facilitates the orientation of homologous centromeres to opposite poles.

Meiosis is the specialized cell division that generates gametes. In contrast to mitosis, molecular mechanisms and regulation of meiosis are much less understood. Meiosis shares mechanisms and regulation with mitosis in many aspects, but also has critical differences from mitosis. This review highlights these differences between meiosis and mitosis. Recent studies using various model systems rev...

Material and methods. ................................. A brief resume of meiotic behavior in diploid individuals. Meiosis in the triploid individual. ....................... Plaamodial sporogenous tissue. .......................... Chromatin extrusion in sporogenous tissue ................ TheF~generation ..................................... Meiosis in Fr individuals. ...........................

The condensin complex is a key determinant of higher-ordered chromosome structure. We show here that the complex is also important for the correct alignment of chromosomes on the meiosis I spindle. Unlike during mitosis and meiosis II, when sister chromatids attach to microtubules emanating from opposite spindle poles (biorientation), accurate meiosis I chromosome segregation requires that sist...

Chromosomal aneuploidy is the most frequent genetic damage observed in newborn children and originates as a rule from nondisjunction during maternal or paternal germ cell development. The error of chromosome segregation could be allocated in the past--at least in cases of 47,XXY--to maternal meiosis I (50%) or meiosis II (10%) and to paternal meiosis I (40%). Recent cytological improvements wit...

The kinase Cdc2p is a central regulator of entry into and progression through nuclear division during mitosis and meiosis in eukaryotes. Cdc2p is activated at the onset of mitosis by dephosphorylation on tyrosine-15, the phosphorylation status of which is determined mainly by the kinase Wee1p and the phosphatase Cdc25p. In fission yeast, the forkhead-type transcription factor Mei4p is required ...

Meiosis is a specialized cell division that generates gametes, such as eggs and sperm. Errors in meiosis result in miscarriages and are the leading cause of birth defects; however, the molecular origins of these defects remain unknown. Studies in model organisms are beginning to identify the genes and pathways important for meiosis, but the parts list is still poorly defined. Here we present a ...