From: CurtAdams@aol.com
Date: Thu Sep 02 1999 - 15:38:22 MDT
In a message dated 9/2/99 14:03:01, bradbury@www.aeiveos.com writes:
>On Thu, 2 Sep 1999, Philip Witham wrote:
>
>>
>> This is amazing. How could it be that nature didn't select for this?
>> So simple, so apparently effective,
>
>From the paper:
>> the total number of NR2B-containing NMDA receptors per single synapse
>> is also increased in transgenic neurons at this stage.
>
>Sorry, but it isn't "simple" to for nature to increase the expression of
>a receptor in some part of the brain.
>
>That requires very accurate gene duplication of the gene in
>question (without duplicating any negative genes), or a very
>specific mutation in the NMDA expression or transcription
>regulatory region(s).
Mutations to regulatory regions do not need to be specific at all.
As a rule, most mutations in regulatory regions will either
increase or decrease expression. Increases aren't particularly
hard to come by either; although most mutation will decrease the
effect of the region, many regulators are repressors. Most
regulatory regions are several bases off consensus (= most
active, presumably) so *increases* to regulatory activity
aren't that hard to come by anyway.
Variation in regulatory regions is turning out to be quite common
and seems to underly most natural quantitative genetic variation.
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