RE: 'Directed' evolution?

Kevin L. O'Brien (klob@lamar.colostate.edu)
Tue, 22 Sep 1998 18:15:34 -0600

Greetings Art:

"Using Spetners definition (his expertise is in information theory) of what
constitutes new information (and he deals in his book with each of the
cases you suggest), none of these meet the criteria of new information."

Then please provide Spetner's definition, because it seems to me that the
appearance of a new protein function that never existed before and never
could exist at all under normal circumstances is an excellent example of
new information.

"Either they exploit information that is already in the genome, but
inactive, or they involve a loss of information that decreases
specificity."

"Decreases specificity" is a meaningless phrase. An enzyme that breaks
cellulose down into the individual glucose units that, because of a
mutation, can no longer recognize the cellulose bond is not going to go off
looking for other bonds to break. Chances are excellent it won't be able
to do anything else at all. On the other hand if a different mutation
changes the enzymes specificity from cellulose to glycogen, the enzyme will
certainly loose specificity for cellulose but will gain specificity for
glycogen. So a mutation is likely to alter an enzyme's specificity
regardless of what it does to the enzyme, but that does not mean no new
information can be gained from the change.

Kevin L. O'Brien

"Good God, consider yourselves fortunate that you have John Adams to abuse,
for no sane man would tolerate it!" William Daniels, _1776_