"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).
These genes control development of parasegments 0 and 1 (Dfd), 2 and 3
(Scr), and 4 and 5 (Antp). As with genes in the BX-C, the linear order of
genes in the ANT-C corresponds to their pattern of expression along the body
axis. 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?
Art
http://chadwicka.swac.edu