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Re: Limb Evolution - "Old" genes

I wrote a news story for New Scientist

It looks like very solid work - 

At 11:32 AM +0100 5/24/07, Luis Azevedo Rodrigues wrote:
>Any comments?
>Nature 447, 473-476 (24 May 2007) 
>An autopodial-like pattern of Hox expression in the fins of a basal 
>actinopterygian fish
>Marcus C. Davis, Randall D. Dahn & Neil H. Shubin
>Comparative analyses of Hox gene expression and regulation in teleost fish and 
>tetrapods support the long-entrenched notion that the distal region of 
>tetrapod limbs, containing the wrist, ankle and digits, is an evolutionary 
>novelty. Data from fossils support the notion that the unique features of 
>tetrapod limbs were assembled over evolutionary time in the paired fins of 
>fish. The challenge in linking developmental and palaeontological approaches 
>has been that developmental data for fins and limbs compare only highly 
>derived teleosts and tetrapods; what is lacking are data from extant taxa that 
>retain greater portions of the fin skeletal morphology considered primitive to 
>all bony fish. Here, we report on the expression and function of genes 
>implicated in the origin of the autopod in a basal actinopterygian, Polyodon 
>spathula. Polyodon exhibits a late-phase, inverted collinear expression of 5' 
>HoxD genes, a pattern of expression long considered a developmental hallmark 
>of the
 autopod and shown in tetrapods to be controlled by a 'digit enhancer' region. 
These data show that aspects of the development of the autopod are primitive to 
tetrapods and that the origin of digits entailed the redeployment of ancient 
patterns of gene activity.

Jeff Hecht, science & technology writer
jeff@jeffhecht.com  http://www.jeffhecht.com
Boston Correspondent: New Scientist magazine
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