Simon Wrote:
-------------------------------------------------------
> Hi Bernard
>
> I seem to have missed the fact you'd replied
> here.
>
>
> bernard Wrote:
> --------------------------------------------------
> -----
> > >
> > > So are you suggesting the immune system
> is a
> > 'fait
> > > a complete' and is no longer evolving ?
> Do
> > you
> > > see why I'm saying that the ability of
> the
> > immune
> > > system to generate lifetime immunity in
> the
> > next
> > > generation is very much part and parcel
> of
> > the
> > > bigger picture of evoution at a more
> > fundamental
> > > level ?
> >
> > It would be silly of me to say that something
> has
> > stopped evolving. However, normally evolution
> is a
> > very slow process and it is hard to see if
> > something is "evolving." When an adaptation
> is
> > working well it is quite stable some of the
> basic
> > biochemical processes have been around for
> million
> > and millions of years and they have changed
> from
> > species to species but no by being
> fundamentally
> > changed.
> >
>
> But I thought the whole thing with modern
> evolution theory since the various "genome
> decoding" projects is that nearly all life has the
> same essential code, its which genes are
> "activated" thats determines the species
> characteristics.

For some reason you are getting hung up and excited with "gene activation" 1) What is meant by life having the same code is that the same three bases in DNA code for the same amino acid in all life. It NOT that all the genes in all life are the same and the differences between species is what genes become "activated." You really need to get some of the basics of evolution down.



Hence the fact that the genome
> of the same sex in chimps and humans can be more
> similar than those of the different sexes.

Who in the world ever said that?

So if
> a gene become activated during reproduction, isn't
> that evolution (at some level) at work ?

YOu are taking a very small and unusual process (prions in yeast) and trying to extrapolate it way beyond its realm of its validity. This entire "gene becomes activated' concept. is being misconceived. Let's recap. What the yeast research says is that under certain conditions a unique thing happens in ONE organism (the yeast) with no evidence that it happens elsewhere. This is that a protein (Sud35) can be shifted in conformation to become a prion. When this happens its function is disrupted and the yeast's transcription machinery produces proteins based on the DNA code in the "non-coding" portion of the yeast's genome. This is NOT activating a gene. What is produced is the equivalent of producing mutations at a rate higher than would be normally expected. Mutations are most often not beneficial (as is the case here 80% of what is produced). The paper (which I have not yet read in the original) claims that some resistance to paraquat was found. This is not analogous to an immune response.

Ordinarily in genetics gene activation refers to a gene whose function is to turn another gene on or off. Both are encoded in the DNA and are subject to the normal processes of evolution. It has no similarity to the yeast situation.



There is
> obviously the bigger question of the mutations
> themselves, but that is another part of the same
> process we call evolution - surely ?
>
Bernard