In mammals, following implantation of the embryo, a small number of cells from the epiblast eventually become the precursors of primordial germ cells (reviewed by Edson et al., 2009). After mitotic proliferation of the primordial germ cells, migration to the genital ridges and rapid proliferation again, meiosis is initiated in the oogonia at about day 13 of development in mice, at day 82 in bov...

The pattern of distribution of genetic markers among progeny of Agaricw bisporus, whether conventional mutants, electrophoretic isozyme variants or restriction fragment length polymorphisms, implies a combination of reduced recombination rates and preferential segregation of centromeres during meiosis. We have considered an alternative explanation, namely that meiosis may be an infrequent event...

In Xenopus oocytes, activation of MAP kinase occurs during meiotic maturation through a protein kinase cascade (the MAP kinase cascade), which is utilized commonly in various intracellular signaling pathways in eukaryotes. Studies with a neutralizing antibody against Xenopus MAP kinase kinase (MAPKK), a direct upstream activator for MAP kinase, have shown that the MAP kinase cascade plays a cru...

Immature oocytes become fertilisable eggs through a process called meiotic maturation, which is often induced by specific hormones. Oocyte maturation involves the activation of various signal transduction pathways that converge to activate maturation-promoting factor (MPF); this is a key activity that catalyses entry into M-phase of meiosis I and meiosis II. Whereas the function of MPF in promo...

Interhomolog recombination plays a critical role in promoting proper meiotic chromosome segregation but a mechanistic understanding of this process is far from complete. In vegetative cells, Rad51 is a highly conserved recombinase that exhibits a preference for repairing double strand breaks (DSBs) using sister chromatids, in contrast to the conserved, meiosis-specific recombinase, Dmc1, which ...

In mammals, a key transition in spermatogenesis is the exit from spermatogonial differentiation and mitotic proliferation and the entry into spermatocyte differentiation and meiosis. Although several genes that regulate this transition have been identified, how it is controlled and coordinated remains poorly understood. Here, we examine the role in male gametogenesis of the Doublesex-related ge...

Mutations in CDC13 have previously been found to cause cell cycle arrest of Saccharomyces cerevisiae at a stage in G2 immediately preceding the mitotic division. We show here that cdcl3 blocks the meiotic pathway at a stage that follows DNA replication, but in this case the spindle has not yet formed nor have the chromosomes undergone synapsis or recombination. This arrest is alleviated by rad9...