Month: September 2022

NUMBER 2: OXIDATIVE STRESS. "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." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

OXIDATIVE STRESS HYPOTHESIS. "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. 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." (DSB = double strand breaks). http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

THE CORE. “In eukaryotic sexual life cycles, haploid cells fuse to give rise to diploids, before diploid cells are converted back to haploids in a process known as meiosis. Meiosis reduces a cells chromosome number by half, whilst also creating new allele combinations distributed across daughter cells through segregation and recombination.” http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

DOUBLING AND HALVING. "A particular feature of meiosis is that it starts with a chromosome doubling (2n→ 4n) before meiosis I (4n→2(2n)) and II (2(2n)→4(n)) occur. For ploidy reduction, the initial steps appear superfluous. A simpler single-step cell division (2n→2(n)), without the initial DNA replication phase, could in principle achieve ploidy reduction." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

TWO STEP HYPOTHESIS 1. "Three hypotheses have been proposed to account for two-step meiosis. The first postulates that two-step meiosis better protects against particular selfish genetic elements that increase their transmission frequencies by sabotaging the meiotic products in which they do not end up (known as ‘sister killers’)." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

TWO STEP HYPOTHESIS 2. "The second hypothesis is that sexual species with one-step-meiosis would be vulnerable to invasion by asexual mutants, and have thus gone disproportionally extinct in the past." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

HYPOTHESIS 3. "A third hypothesis posits that a one-step-meiosis is more complex and thus less likely to evolve than a two-step-meiosis." https://lnkd.in/e2tp_G5 View in LinkedIn

LARGELY CONSERVED. "Meiosis is remarkably conserved across eukaryotes. Nevertheless, in many species, variants exist that may offer insights into the evolutionary origins and mechanistic constraints of meiosis." https://lnkd.in/e2tp_G5 View in LinkedIn

COMMON DESPITE. "Polyploidy is surprisingly common in eukaryotes given the considerable problems it poses to meiosis." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

MULTIVALENT FORMATION. "In diploids, homologous chromosomes recognise each other and align to form bivalents during Prophase I, but when there are three or more chromosomes with sufficient homology, these chromosomes may all align to varying degrees and form multivalents." https://lnkd.in/e2tp_G5 View in LinkedIn