Re: epidermal structures

[TomHopp@aol.com]

Well said, Alan. Those darn epidermal structures are devilishly complex. One 
of the wonders of nature, and we need to approach them carefully, lest we get 
hopelessly tangled in terminology.
   That said, it is fun nonetheless, to speculate a bit on their origins and 
interrelationships. Relevant to your insights on gene regulation and cell 
differentiation, it has been my experience, while working with transgenic 
experimental animals, that gene expression is exquisitely sensitive to 
mutations in the regulatory, non-protein-coding regions (binding regions for 
RNA transcription factors etc). Single point mutations can completely 
suppress gene expression in a given tissue, and/or promote it in some other, 
ectopic, locale. Quite amazing, and one of the reasons we must tread 
cautiously when hypothesizing evolutionary relationships among body 
structures.
   But pretty cool too, huh?

Thomas P. Hopp
Author of DINOSAUR WARS, a science fiction novel published by iUniverse
Now Humans are the Endangered Species!  http://members.aol.com/dinosaurwars