By VICTORIA GILL - BBC
Added: Thu, 24 Jun 2010 13:38:03 UTC

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The researchers discovered genes involved in fin but not limb development

A study has shed light on a key genetic step in the evolution of animals' limbs from the fins of fish, scientists say.

A team of researchers identified two new genes that are important in fin development.

They report in the journal Nature that the loss of these genes could have been an "important step" in the evolutionary transformation of fins into limbs.

Marie-Andree Akimenko, from the University of Ottawa in Canada, led the research.

She and her colleagues began their study by looking at the development of zebrafish embryos. They discovered two genes that coded for proteins that were important in the structure of fins.

These proteins were components of the thread-like fibres known as "actinotrichia". These are found in fish larvae and they eventually develop into the bony fin rays of mature fish.

"We found there were no [equivalent genes] in limbs, so this suggested these may have been lost in evolution," explained Dr Akimenko.

To confirm this, they looked for - and found - the same family of genes in the genomes of elephant sharks, which are a very basal (or ancient) fish species.
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TAGGED: BIOLOGY, EVOLUTION