Re: Homeotic genes

Steve Clark (ssclark@facstaff.wisc.edu)
Tue, 14 Nov 1995 18:37:56 -0600

Art quotes James Darnell
> "Remarkably, the order of the genes within the complex (Ubx, abdA, AbdB)
>corresponds to their linear order of expression along the body axis
>(anterior -> posterior).... The ANT-C is separated from the BX-C by some
>10cM on Drosophila chromosome III. It contains five protein-coding genes
>including Deformed (Dfd), Sex combs reduced (Scr), and Antennapedia (Antp).
[clip]
>This organization of both the ANT-C and BX-C is not likely to be
>serendipitous, AS IT IS OBSERVED IN HOMOLOGOUS GENE CLUSTERS IN HIGHER
>ORGANISMS [INCLUDING HUMANS...EMPHASIS ADDED]. The functional significance
>of this organization is not yet understood."
>
>So the most critical gene arrays, the homeotic genes responsible for
>development, are arranged in a highly significant order. True for flies,
>true for humans, and probably true for all other organisms. What is the
>source of the order? serendipity? Clearly the hand of a Master Designer at
>work. As I recall, the calculations of Eden suggested 5 billion years was
>just enough time to order two genes in one of the operons of E. coli. Who
>fixed these?

I am not sure that your analogy to E coli is correct. First, I do not know
what you mean by "two genes in one of the operons".

Next, most functionally relevant genes that lie in tandem, share significant
sequence similarity and could arise from gene duplication rather than by a
process by which different genes are somehow sorted and ordered in the genome.

Steve
__________________________________________________________________________
Steven S. Clark, Ph.D. Phone: (608) 263-9137
Associate Professor FAX: (608) 263-4226
Dept. of Human Oncology and email: ssclark@facstaff.wisc.edu
UW Comprehensive Cancer Ctr
University of Wisconsin
Madison, WI 53792

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seniors take none away...the knowledge accumulates." Mark Twain
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