Anti-G bias question

[mwooten at ducvax.auburn.edu]

I am new to this newsgroup so I apologize if this issue has been worked through
before.  

Issue:  In working with mitochondrial Cytochrome B sequences from livebearing
        fish, I have noted the same strong anti-G bias that has been reported
        for numerous mammals and other taxa.  My fish show somewhat less of a
        bias but the values are still significant and very consistent with
        patterns in other coding regions (both nuclear and mitochondrial).
        The most obvious location of this bias is in the third position where
        G is found less than 8% of the time.

Question: What molecular mechanism(s) could account for this pattern?

I have tried to work through a number of possible explanations based on
G-C binding and hairpins during transcription but given these ideas, it
is still unclear to me how any bias arises in the first place.

Anyone interested in a discussion on this issue?

Mike

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*   Michael C. Wooten
*
*   Dept. of Zoology
*   Auburn University
*   Auburn, AL  36849  USA
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*   BITNET: mwooten at auducvax.bitnet
*   INTERNET: mwooten at ducvax.auburn.edu
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