Sep 25, 2007

Twisted Picks

This is the first of a series of posts where I plan to gather some links from my Connotea library that other people (you?) might find interesting. They'll mainly consist of links to research news or original articles, but don't expect many big headlines (that you can read anywhere). Links to research news will be preferred, as they are more readable by a wider audience. Most of the links will be microbe-centric but others may be related to biology fields beyond microbiology. So, there we go.

Microbes and spaceships, great combination! I thought that microorganisms were too small to be bothered by terrestrial gravity, but I was wrong. For instance, Salmonella can get more virulent during a space trip (not very good news for astronauts): Spaceflight shown to alter ability of bacteria to cause disease. Other researchers are studying the effects of microgravity on mutation and DNA recombination rates in microbes (including some streptomycetal astronauts!): Russian rocket carries experiment to be analyzed at MSU. No wonder that NASA workers do their best to avoid bacterial contamination of spaceships, which are assembled at specially clean rooms; but the tiny bugs are still there: NASA Study Will Help Stop Tiny Stowaways To Mars.

In relation to endurance, it seems that ancient microbes can be detected and resuscitated from ice samples ranging in age from 100,000 to 8 million years old: Locked in glaciers, ancient ice may return to life as glaciers melt (news release), Fossil genes and microbes in the oldest ice on Earth (original article). Yes, this is the story about "gene popsicles" (a new meme?). From the article:
"The community DNA immobilized in Antarctic ice is essentially a "gene popsicle," which can potentially be acquired by extant organisms upon thawing (...). Our analysis suggests that melting of polar ice in the geological past may have provided a conduit for large-scale phage-independent LGT [lateral gene transfer], potentially scrambling microbial phylogenies and accelerating the tempo of microbial evolution. Finally, the preservation of microbes and their genes in icy comets may have allowed transfer of genetic material among planets. However, given the extremely high cosmic radiation flux in space, our results suggest it is highly unlikely that life on Earth could have been seeded by genetic material external to this solar system."

By the way, lateral gene transfer seems to be more frequent than previously thought, even from prokaryotes to eukaryotes: Widespread lateral gene transfer from intracellular bacteria to multicellular eukaryotes. The whole genome of a bacteria has been naturally transferred to one of the chromosomes of a fruit fly... what shall we find next? Perhaps published genome sequences from eukaryotic organisms (such as us) should be fully reanalyzed, searching for prokaryotic sequences (previously removed as "contaminations").

And, finally... sex, sex, sex! There is a review article titled Bacterial solutions to the problem of sex. But don't misunderstand: bacteria don't have sexual problems (except when in pure culture at laboratories, I guess) (wait... "sexual microtherapist" could be a new job option for microbiologists, treating sexual dysfunctions in microbes...?) (oops, sorry about that!) The review highlights a research article reporting the use of bacteria in carefully designed experiments to study the possible advantages of sexual vs. asexual reproduction: Recombination speeds adaptation by reducing competition between beneficial mutations in populations of Escherichia coli. So, "the problem of sex" is ours (we feel the need to answer "why sex?"), not theirs (bacteria just don't care).

Image credits:
Spacecraft (Soyuz TMA-6), NASA.
Glacier (Grosser Aletschgletscher, Alps) by Dirk Beyer.
Fruit fly (Drosophila melanogaster) by André Karwath.
Bacterial conjugation by Mike Jones.

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