linkedin post 2017-09-30 15:18:29

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FRAGMENT FROM NATURE contemplates the question of how animals differ from plants. This may seem like a quaint and perhaps academic question, but it is far from the case. Imagine a creature that continues to form body parts throughout its life, in a quasi pluripotent state, forever capable of regeneration of an adult from a fragment of tissue. This creature can morph its anatomy and physiology according to the conditions. And the delineation of an individual in this creature is essentially a group of cells, not the organism. Read on. View in LinkedIn
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linkedin post 2017-09-28 06:35:15

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TERM CHIMAERAS. "Previous attempts to achieve development to term of aggregation chimaeras between parthenogenetic and fertilised embryos were apparently unsuccessful. We have introduced inner cell masses (ICMs) from diploid, parthenogenetic embryos into intact fertilised mouse blastocysts, and we report here the development of a chimaera to term." https://lnkd.in/gAXZaG6 View in LinkedIn
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linkedin post 2017-09-29 07:15:44

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TRANSITION OF SETS. "The emergence of a new master sex-determining gene on a different chromosome can also lead to a shift of the heterogametic sex, [e.g., transforming a XY system into ZW (nonhomologous transition)]. Such a situation is again represented in the ricefishes. Two species have ZW sex determination on two linkage groups, which are different from those that became the X and the Y in the other five species." http://www.pnas.org/content/112/34/10575.full View in LinkedIn
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linkedin post 2017-09-29 07:12:46

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NEW CHROMOSOMES. "If a gene from elsewhere in the genome becomes the new male sex-determining gene, then a new chromosome will evolve to become the Y (nonhomologous turnover). An increasing number of systems are described where this may have happened." http://www.pnas.org/content/112/34/10575.full View in LinkedIn
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linkedin post 2017-09-29 07:11:09

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CHANGING MASTER GENES. "Even more intriguingly, the master sex-determining gene itself can change; and depending on the type of change, this has different chromosomal consequences. If for example, the function of a gene as a male sex-determining gene is turned over to a different gene, which resides nearby on the same chromosome as the previous master gene, there is no change of the Y chromosome (homologous turnover)." http://www.pnas.org/content/112/34/10575.full View in LinkedIn
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linkedin post 2017-09-29 07:07:25

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JUMPING GENES AND SEX GENES. "Here, recent evidence assigns transposable elements a role in having moved the male sex-determining gene to other chromosomes. As result, the Y chromosome is a different linkage group in several salmonid species. If large pieces or the entire Y are translocated to an autosome, so-called “neo-Y chromosomes” and multiple sex-chromosome systems are created." http://www.pnas.org/content/112/34/10575.full View in LinkedIn
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linkedin post 2017-09-29 07:02:48

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MOVING SEX GENES. "When sex is determined by a single locus or chromosomal region, the corresponding chromosome pair becomes the sex chromosomes. However, the affiliation of the master sex-determining gene and a chromosome are not always forever. The same sex-determining gene can reside on different chromosomes in closely related species, for example in the salmonids (rainbow trout, salmon, and relatives)." http://www.pnas.org/content/112/34/10575.full View in LinkedIn
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linkedin post 2017-09-29 06:59:10

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TRANSITION SETS. "Curiously, outside of mammals and birds, the phylogenetic patterns of these two obviously contrary modes of sex determination indicate many transitions. Many cases have been documented where closely related lineages switch between XY or ZW sex chromosomes, demonstrating that transitions between male and female heterogamety have occurred quite frequently in the evolutionary past of vertebrates." http://www.pnas.org/content/112/34/10575.full View in LinkedIn
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