This Week in Science (Nov. 22 – 29)

Nov 29, 2015

This is a collection of the 10 best and most popular stories from science and technology over the past 7 days. Click the individual images below to read the stories and follow the This Week in Science on wakelet (here) to get these weekly updates straight to your inbox every Sunday.

5 comments on “This Week in Science (Nov. 22 – 29)

  • @ link

    They found the H. dujardini genome is material from several entirely different kingdoms—mostly bacterial (16 percent) but also fungal (0.7 percent), plant (0.5 percent), archaeal (0.1 percent), and viral (0.1 percent).

    “We never expected to find that an animal genome would be quite so littered with foreign genes,” said Goldstein, whose study was published November 23 in the journal Proceedings of the National Academy of Sciences.

    The tardigrade acquires foreign DNA via a process called horizontal gene transfer, in which genetic material is transferred directly between organisms instead of being passed down from parent to offspring.

    “Many animals appear to have a small degree of horizontal gene transfer, including humans,” Boothby says. “But nowhere close to the proportion [about one-sixth of genes) that we see in the tardigrade genome.”

    “What this tells us is that instead of thinking about a tree of life, we can start to think more about a web of life, where genetic material from one branch, say the bacterial branch, can cross over to the animal branch.”

    So how exactly does the tardigrade get foreign DNA? It may have to do with one of the tardigrade’s survival skills—the ability to completely dry out in drought conditions, then rehydrate. (See “Five Extreme Life-Forms That Live on the Edge.”)

    As a cell dries out, its DNA breaks into fragments, and the cell membrane “becomes temporarily leaky as it rehydrates,” Boothby says.

    Where horizontal gene transfer dominates, life does seem to fit better on to a web, than on to the evolutionary tree of the more complex multicellular organisms with which most people are more familiar.

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  • @ link – Mars could gain a ring in 10-20 million years when its moon Phobos is torn to shreds by tidal forces due to Mars’ gravitational pull.

    This will depend on the structure of Phobos. If it is a captured “rubble-pile asteroid”, it will fall apart fairly easily under tidal stress. Denser parts would be strong enough to resist this, if rocks have been melted and then set solid.

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  • One more evolutionary step for the theory of evolution. Amazing organisms like the tardigrade define adaptation and earth does not confine them, if it ever did. The genetic modifications we only began to experiment with, the tardigrade exists on.

    Once upon a time, our biological ancestors also transferred genes horizontally. Our mitochondria is borrowed from bacteria-like organisms and up to 8% of our genome came from bornavirus through endogenesis. We have been part of the web.

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  • Helium shortage – how is it there’s enough to fill (60%) * Airlander 10 *; maybe the craft itself is the cause.

    Any ties with the military would give it clout, and front of the line placement, I imagine.

    “Balloon releases” (popular in the states) wreaks havoc on the environment down the line. Ban.

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