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posted by martyb on Saturday May 24 2014, @09:27AM   Printer-friendly
from the happened-twice-it-was-so-nice dept.

If you think that early animals started out simple and gradually evolved new features, and things like sponges branched off before the new features were added, you wouldn't be alone. Over the years, lots of researchers argued the same thing. But a recent genome sequence indicated that the oldest branch of the animal family tree that led to the comb jellies, with muscles, nerves, and tentacles, were an older branch than sponges. Now with a new paper on the comb jelly, researchers are starting to argue over what this actually tells us about the earliest animals.

The comb jellies' genome contains a variety of other indications that they are exceptional. Most of the innate immune system, which broadly recognizes pathogens like bacteria and viruses, is missing. So is the machinery that processes micro RNAs, which are used to control the expression of other genes. Key regulators of development, like hedgehog and JAK/STAT proteins, are also absent. So are key genes involved in the formation of muscles, suggesting that these, too, may have evolved separately in the ctenophores.

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  • (Score: 2) by lubricus on Saturday May 24 2014, @11:05PM

    by lubricus (232) on Saturday May 24 2014, @11:05PM (#47197) that life arose one and is all related.

    The answer is that:
    1. Not *all* live uses DNA (think retroviruses or prions... which probably arose from DNA based life)
    2. ... There is no 2 for DNA specifically, although there are arguments for 4 bases (ATGC, as opposed to 2 or 6), and for the 3-base codon (as opposed to more or fewer), but those always seemed like just-so stories to me.

    The simple answer seems the best.

    ... sorry about the typos
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  • (Score: 2) by lubricus on Saturday May 24 2014, @11:10PM

    by lubricus (232) on Saturday May 24 2014, @11:10PM (#47199)

    "The complicated answer is that:"...
    funny how the hands skip words that pass by the mind..

    ... sorry about the typos
  • (Score: 2) by frojack on Sunday May 25 2014, @12:14AM

    by frojack (1554) Subscriber Badge on Sunday May 25 2014, @12:14AM (#47212) Journal

    4 bases vs 6 vs 20...

    You are still thinking in DNA terms. Kind of like fussing over national course threads on a bolt rather than National fine.

    Its still a bolt.

    Why isn't there a life form that uses rivets or glue or something totally different.

    Maybe no bases, maybe crystalline structured, metals, etc.

    No, you are mistaken. I've always had this sig.