Received: by alpheratz.cpm.aca.mmu.ac.uk id FAA13795 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Tue, 13 Feb 2001 05:48:51 GMT Date: Tue, 13 Feb 2001 11:08:50 +0530 (IST) From: Dr Able Lawrence <able@sgpgi.ac.in> To: memetics@mmu.ac.uk Subject: Human Genome Message-ID: <Pine.LNX.4.10.10102131046040.19692-100000@sushrut.sgpgi.ac.in> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
Hi All,
Genome report (only 3000 genes) is not really surprising at all if
we understand the implications of the recently discovered complexities in
gene expression regulation The transcription factors are huge multi
subunit
complexes with countless interactions amongst them. The permutation and
combination possible for interactions amongst transcription factors is
realy mind boggling. There is more to genetics than mere genes and DNA
sequences.
The real implication of the new finding is that one gene- one
function hypothesis is dead. Now we know that a single gene can produce
myriad proteins like the immunoglobuin or T cell receptor or neural
adhesion molecules involved in the complex wiring of the nervous system.
On the contrary multiple genes are required for functional units (multi
subunit complexes) involved in such vital functions as regulation of
gene expression or respiration or protein synthesis.
A lot of the complexity in higher organism is probably at the level
of gene-gene interactions and the complex cascading and epigenetic effects
on gene expression.
To emphasize the point furhter, all our cells have the same DNA
sequence (well almost) but are morphologically and functionally diverse.
So it is not necessary to have different sets of genes but more fine
tuned interacions to create us humans.
As I pointed out earlier that smple minor vaqriations in gene
expressions can have profound morphological implications. So the gene
regulating embryogenesis (Hox genes) are highly conserved vertically in
the evolutionary ladder (ladder itself is an anthropocentric view and
other organisms can object!)
throughout evolution new functions have rarely ever come about by
inventing new genes (it takes too much directed ingenuity for that, may be
only Lamarck or biotechnologists a few decades down the line can only do
it) but by making new use or modifying old genes. Once useful but
rudimentary function is discovered for an old gene, variation and
evolution (and duplication if the old gene already has an indispensable
function) would be favoured and would arise in due course of time.
Duplication of genes in malignant clones in the body is a case in point.
It would be ridiculous to say that the multidrug resistance gene in
human malignancy had the same function before that begins to get favoured
by surviving tumour cells.
We must view genes as dynaqmically interacting information
and also should not forget that the genes get their properties through the
proteins they encode (with all the complexities of protein chemistry and
protein protein interaction)
Anthropocentrism is alive only in Christian theology!!
~~~~~~~~~~~~~~~~~~~
Dr Able Lawrence MD
Senior Resident
Clinical Immunology
SGPGIMS, Lucknow
able@sgpgi.ac.in
Ph +91 98390 70247
~~~~~~~~~~~~~~~~~~~
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