JDBarron at Mindspring.com
Sun Mar 21 19:18:49 EST 1999
William Crymes wrote:
> I think most developmentally altered genes are the effect of
> differential transcription. Such that type "A" gene is transcribed
> during embryogenesis and type "B" gene is transcribed later. Look up
> fetal hemoglobin vs. adult hemoglobin. The one set of genes that are
> extensively altered are the genes of the immune system. The gene the
> make-up the antibodies in the immune system are hyper-variable, though
> they vary not as a result of development but as a result of exposure to
> different antigens.
> William B. Crymes, Jr.
> University of South Carolina
> Department of Biological Sciences
> 700 Sumter Street
> Columbia, South Carolina 29201
> Phone: (803)777-7105
> Fax: (803)777-4002
Strictly speaking the antibodies in the immune system are inherently
variable. What exposure to antigens does is to cause the *selection* and
reproduction of antibodies which have already been produced.
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