The Evolution of Meiosis From Mitosis

MOS, aneuploidy and the ploidy cycle of cancer cells

“…Furthermore, meiosis almost certainly evolved from mitosis (Hurst and Nurse, 1991;Wilkins and Holliday, 2009), possibly for the purpose of reducing polyploidy. This shared evolution may be central to the ability of polyploid cells to revert back to mitosis as they share homology to checkpoints, such as the spindle checkpoint (Page and Orr-Weaver, 1997;Nebreda and Ferby, 2000;Nasmyth, 2001).…”

“…Here, Mos favors the accumulation of Cdk1/cyclin B, thereby condensing chromosomes in interkinesis in the environment akin to G2 of the mitotic cycle, preventing replication licensing, the second condition for reduction division. This activity reaches a peak in metaphase II wherein Mos/MEK-primed p90 Rsk (in co-operation with cytostatic Emi proteins) induces meiosis-specific activation of the spindle checkpoint uncoupled from apoptosis (Wu and Kornbluth, 2008;Extavour, 2009;Wilkins and Holliday, 2009). The question then arises whether these activities (cohesion of sister chromatids in the first division and subsequent omission of S-phase before the second) are applicable to somatic ETCs?…”

Evolutionary history of the mammalian synaptonemal complex

“…Assuming meiosis having evolved from mitosis only once, this first meiotic division, however, also harbors most evolutionary novelties and essential adaptions of the meiotic chromosome architecture that allow the reduction of the chromosome set and make the differences to the mitotic division (Petronczki et al 2003;Wilkins and Holliday 2009). These specific features of meiotic chromosomes will be described in the following section.…”

Evolutionary mysteries in meiosis

“…Most evidence suggests that homologous recombination evolved long before meiosis, as it occurs in all domains of life and involves proteins that share strong homology [25,26]. One hypothesis is that meiotic pairing and extensive homologous recombination in meiosis evolved to avoid the burden and consequences of non-allelic ectopic recombination in the large genomes of early eukaryotes, which presumably had many repetitive sequences [9,27,28]. Such sequences may have been related to the spread of retrotransposons in early eukaryotes, of which many types are very ancient in eukaryotes, but absent in bacteria and archaea [29].…”

“…Another hypothesis is that pairing and recombination initially arose as a way to repair mutational damage caused by increased oxidative stress due to rising atmospheric oxygen or endosymbiosis [7,[31][32][33]. This scenario presupposes that DNA maintenance is inefficient in the absence of meiosis; however, prokaryotes (including archaea) have efficient repair mechanisms that involve recombination, but not meiosis [9]. In addition, this scenario does not fit well with the observation that a large number of DSBs are actively generated at the onset of meiosis [1,34].…”