( University of Florida scientists have f...)UF scientists reveal ancient origin of vertebrate skeleton

It turns out lampreys, long thought to have taken a different evolutionary road than almost all other backboned animals, may not be so different after all, especially in terms of the genetics that govern their skeletal development, according to findings to be published online this week in the Proceedings of the National Academy of Sciences.

UF scientists found the same essential protein that builds cartilage in this odd animal - it spends the first five years of its development in the larval stage before it finally morphs into a boneless fish - is none other than collagen. This vital structural molecule is found in all vertebrates with backbones and jaws, including humans.

"It was thought collagen was a relatively recent invention in vertebrate evolution that unites us with reptiles, amphibians, sharks and bony fishes, while the lamprey skeleton was based on quite different proteins," said Martin Cohn, Ph.D., a developmental biologist and associate professor with the UF departments of zoology and anatomy and cell biology. "Knowing that lampreys also use collagen to build their skeletons makes sense. Lampreys and jawed vertebrates inherited the same genetic program for skeletal development from our common ancestor."

Lampreys live today in the Great Lakes and other freshwater bodies that connect to the sea. But they are considered a nuisance, largely because of their unsettling appearance and demeanor - picture a leech longer than your forearm with a rasp-like mouth that flares open at the end of its body.

Still, the lamprey and its cousin, the hagfish, offer insight into the early Cambrian period 540 million years ago, when multicellular animals first began to make shell and other hard body parts. About 40 million years into the process, jawed and jawless vertebrates branch
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Source:University of Florida