Re: [asa] One Species' Genome Found Within Another

From: David Campbell <pleuronaia@gmail.com>
Date: Fri Aug 31 2007 - 18:35:36 EDT

The free preview for Science mentions chunks of Wolbachia genome in
multiple arthropods and nematodes, as well as the apparently almost
complete copy in the one fly.

"The chance that a chunk of DNA of this magnitude is totally neutral,
I think, is pretty small, so the implication is that it has imparted
some selective advantage to the host," principal investigator Jack
Werren said in a prepared statement. "The question is, are these
foreign genes providing new functions for the host? This is something
we need to figure out."

Not entirely well-worded, at any rate. It's possible that the genome
is neutral-diferences in bacterial versus animal DNA processing might
make it less functional-but was very recently transferred and has not
yet gotten deleted. It's also possible that it has gained some sort
of function in the animal while not exactly giving a selective
advantage. I.e., it's just as good as whatever the fly did before.
Finally, given that Wolbachia (the source bacterium) spreads itself by
affecting the reproduction of the host (infected mating with
non-infected are generally sterile), it's possible that the bacterial
genome is functioning essentially parasitically. A variant on this is
the possibility that it started out functioning essentially
parasitically but is now put to use by the fly.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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Received on Fri Aug 31 18:36:10 2007

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