gene development

Jim JDBarron at Mindspring.com
Sun Mar 21 19:18:49 EST 1999



William Crymes wrote:

> Kirk-
>   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.
> Bill
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 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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