Type II collagen-based cartilage evolved in stem vertebrates

This forum is for the discussion of the evidence for evolution. Anyone is welcome to post, however, scripture is not allowed. As the title says, Science Only please!

Moderator: Moderators

Type II collagen-based cartilage evolved in stem vertebrates

Postby Anonymous » Wed Nov 01, 2006 7:53 am

http://www.pnas.org/cgi/content/abstrac ... 103v1?etoc

Hagfish and lancelet fibrillar collagens reveal that type II collagen-based cartilage evolved in stem vertebrates

GuangJun Zhang and Martin J. Cohn

The origin of vertebrates was defined by evolution of a skeleton; however, little is known about the developmental mechanisms responsible for this landmark evolutionary innovation. In jawed vertebrates, cartilage matrix consists predominantly of type II collagen (Col2{alpha}1), whereas that of jawless fishes has long been thought to be noncollagenous. We recently showed that Col2{alpha}1 is present in lamprey cartilage, indicating that type II collagen-based cartilage evolved earlier than previously recognized. Here, we investigate the origin of vertebrate cartilage, and we report that hagfishes, the sister group to lampreys, also have Col2{alpha}1-based cartilage, suggesting its presence in the common ancestor of crown-group vertebrates. We go on to show that lancelets, a sister group to vertebrates, possess an ancestral clade A fibrillar collagen (ColA) gene that is expressed in the notochord. Together, these results suggest that duplication and diversification of ColA genes at the chordate-vertebrate transition may underlie the evolutionary origin of vertebrate skeletal tissues.

Return to Science Only

Who is online

Users browsing this forum: No registered users and 4 guests