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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

TWO STEPS. "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." 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 TOPIC BREADTH. "We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots)." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

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

DIPLOID TO HAPLOID. "Meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction. During reproduction, when the sperm and egg unite to form a single cell, the number of chromosomes is restored in the offspring." https://lnkd.in/eTsFK2C View in LinkedIn

NUMBER 1: RETROTRANSPOSONS. "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 have repetitive sequences. Such sequences might 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." https://lnkd.in/e2tp_G5 View in LinkedIn

SEXUAL REPRODUCTION requires two parents which share equal amounts of genetic information in the offspring. Meiosis creates the germ cells. It is a strategy used by most of the animal kingdom and by many plants, whose flowers are their sexual organs. View in LinkedIn

UBIQUITOUS HOMOLOGOUS RECOMBINATION. "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, but the origins and selective advantage of synapsis, gene conversion and recombination remain poorly understood." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn

GENE CONVERSION. "During meiosis, crossover recombination results from the pairing of homologous chromosomes and the formation of DNA double-strand breaks (DSBs), followed by synapsis, a process in which homologues become tightly paired along their length involving a protein structure known as the synaptonemal complex. DSBs are then repaired as either crossovers (hereafter ‘COs’), resulting in the exchange of large chromatid segments, or gene-conversion events." http://biorxiv.org/content/biorxiv/early/2016/04/28/050831.full.pdf View in LinkedIn