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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

BIG SLITHER OF LIFE. “This vast range exceeds that of the Earth’s mass relative to that of the galaxy (which is ‘only’ 18 orders of magnitude) and is comparable to the mass of an electron relative to that of a cat.” http://jeb.biologists.org/content/jexbio/208/9/1575.full.pdf View in LinkedIn

SCALE OF LIFE. “Life is almost certainly the most complex and diverse physical system in the universe, covering more than 27 orders of magnitude in mass, from the molecules of the genetic code and metabolic process up to whales and sequoias. Organisms themselves span a mass range of over 21 orders of magnitude, ranging from the smallest microbes from 10(-13) g to the largest mammals and plants 10(8) g.” https://lnkd.in/eCs7eyu View in LinkedIn

FRAGMENT FROM NATURE continues from last week’s meditation on the place of life as we know it in the universe. Right now we are only sure of life on earth, but the probabilities are high that this obscure and tiny planet is not the only location of life in the universe. Our challenge is to look up and out, and be like the pilgrim in the Flammarion engraving of 1888 peering into the heavens. https://lnkd.in/eRnh42A View in LinkedIn

MULTIVALENT DISADVANTAGES. "Multivalent formation is often associated with mis-segregation of chromosomes as well as chromosomal rearrangements arising from recombination within multivalents, leading to reduced fertility and low-fitness offspring." https://lnkd.in/e2tp_G5 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

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

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