Consv.of gene linkage in evol.

A.Marchant marchaa at agric.nsw.gov.au
Mon Jun 5 03:48:41 EST 1995


Christopher G Winter <cgw1 at columbia.edu> wrote:

	I have a problem which begins with the fact that I have a nearly 
complete ignorance of genetics. My  question is: To what extent is the distance 
between two particular, unrelated genes conserved between eukaryotic  
species. If one finds that gene X and gene Y are close together in the 
genome of mouse, would you expect that the human homologues of gene X and 
gene Y would also be closely linked, or would you expect that their 
positions would be shuffled in the absence of some selective pressure to 
maintain their linkage? Some related  genes tend to be found in groups 
due , I suppose, to recent gene duplication events (I'm told this is true 
for some of the members of the interleukin family).But what about genes 
with no sequence homology to each other?
	I would be grateful if someone could set me straight on this, or 
at least point me in the right direction in terms of finding references 
which would answer this question.  

Thanks in advance,

Chris

Response:

	There's a fair bit of conservation of gene order, which is really
handy for gene mapping.  A nice poster showing the mouse genome map and
its human parallels is in Science 1st October 1993 - I have a copy from
the Gibco-BRL company.  A simple summary of the mouse-human
relationship would be that one chromosome of
one species generally corresponds to 5-10 chunks of different chromosomes
from the other species.  Within these chunks, gene order is generally
conserved.  

	There is a www page about comparative mammalian genome maps:
http://www.informatics.jax.org
This is reviewed on pp363-365 of Nature 26th Jan 1995.

	If you're interested in plants, most of the cereals have very similar
gene maps (the technical word for parallel gene order is 'synteny').  A
little article on this by Robert Shields is on pp297-298 of Nature 23
Sept. 1993.

	Adam Marchant
	Agricultural Research Institute
	Wagga Wagga
	NSW  Australia

	marchaa at agric.nsw.gov.au





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