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VIRAL BITS. "In many organisms, the sex chromosome pair can be recognized due to heteromorphy; the Y and W chromosomes have often lost many genes due to the absence of recombination during meiosis and are frequently heterochromatic. Repetitive sequences are found at a high proportion on such heterochromatic sex chromosomes and the evolution and emergence of sex chromosomes has been connected to the dynamics of repeats and transposable elements." https://lnkd.in/gMXukbs View in LinkedIn

GENE LOSS. "It is also well established that such nonrecombining Y or W chromosomes have lost many genes that are carried on the ancestrally homologous X or Z chromosomes (genetic degeneration." http://www.nature.com/hdy/journal/v95/n2/full/6800697a.html View in LinkedIn

NO COMBINATION. "It is well understood that the idea that sex-determining genes should not recombine can explain the lack of recombination between X and Y chromosomes of animals such as Drosophila and mammals with male heterogamety (or Z and W in taxa with female heterogamety such as birds and Lepidoptera." https://lnkd.in/gCh5RAX View in LinkedIn

ANCIENT SILENCING MODULES. "These dosage systems cannot be identical by descent but were probably constructed from elements of ancient silencing mechanisms that are ubiquitous among vertebrates and shared throughout eukaryotes." https://lnkd.in/gWDQizV View in LinkedIn

SIMILAR MODULES. "Systems that compensate for different gene dosages include a wide range of global, regional and gene-by-gene processes that differ in their extent and their molecular mechanisms. However, many elements of these control systems are similar across distant phylogenetic divisions and show parallels to other gene silencing systems." https://lnkd.in/gWDQizV View in LinkedIn

DOSAGE. "Differentiated sex chromosomes in mammals and other vertebrates evolved independently but in strikingly similar ways. Vertebrates with differentiated sex chromosomes share the problems of the unequal expression of the genes borne on sex chromosomes, both between the sexes and with respect to autosomes. Dosage compensation of genes on sex chromosomes is surprisingly variable — and can even be absent — in different vertebrate groups." https://lnkd.in/gWDQizV View in LinkedIn

BODY PLAN FLEXIBILITY. “Plant development is remarkably plastic. Groups of totipotent cells termed meristems, which are maintained throughout the life of the plant, give rise to all post-embryonic organs from roots and leaves to petals and fruit. This allows plants, unlike metazoans, to change their final body plans dramatically in response to environmental, hormonal and nutritional cues.” https://lnkd.in/gjRTTC9 View in LinkedIn

CONTROL OF MERISTEMS. “Meristems continually supply new cells for post-embryonic plant development and coordinate the initiation of new organs, such as leaves and flowers. Meristem function is regulated by a large and interconnected dynamic system that includes transcription networks, intercellular protein signalling, polarized transport of hormones and a constantly changing cellular topology.” https://lnkd.in/gBriN3x View in LinkedIn

LIFELONG. “Organogenesis is a postembryonic process that occurs in a continuous manner throughout the entire lifespan.” https://lnkd.in/gVEbgeX View in LinkedIn

PLANT STEM CELLS. “In plants, postembryonic development is organized by meristems, which both self-renew and produce daughter cells that differentiate and give rise to different organ structures.” https://lnkd.in/gVEbgeX View in LinkedIn