From: Rafal Smigrodzki (rms2g@virginia.edu)
Date: Fri Dec 20 2002 - 09:21:42 MST
Robert Bradbury wrote:
> I disagree entirely that a "successful panspermic organism" has to
> be "autotrophic". The point I was trying to make was that one
> doesn't have to throw organisms across interstellar distances
> one only needs to throw information across interstellar distances.
> Now, on the receiving end, one does need to have something like
> a virus that can pick up a small fragment of DNA that happens
> to have something like an ATP receptor site that can be utilized
> creatively. I believe there are viruses and/or bacteria that do
> pick up DNA, incorporate it into their genomes and gradually may
> evolve such that it performs a "useful" function. The question
> revolves around whether the "nature" of the universe is to drive
> biological systems into "niches" that happen to be able to transfer
> information. I'm able to ask that question but don't have a clue
> as to how to go about providing an answer.
### The problem that I see is that for a "bit" of genetic information to be
useful it has to fulfill rather stringent criteria - the protein encoded
must either do something very useful on its own, or else interact
meaningfully with other proteins. There are very few proteins that have very
general usefulness, almost independently of the cell where they happen to
be. I could think about catalase, or a DNA repair enzyme here. So you have
another Great Filter - you need to transport not any fragment of DNA, but
one of the very few that do not need a complementary cellular machinery to
work. Otherwise the effect of the panspermic transfer will be about as much
as that of a few random mutations in the cell's non-coding, or
low-importance DNA.
Rafal
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