PROVIDENCE, R.I. -- Scientists have long known that humans and sea urchins are closely related. In fact, these animals are the only invertebrates on the human branch of the evolutionary tree of life. Now that the sea urchin genome is sequenced and assembled, that genetic connection is even clearer.

After identifying 23,300 genes made from 814 million letters of DNA code taken from Strongylocentrotus purpuratus, the California purple urchin, an international science team has found that humans share 7,077 genes with urchins. This makes the spiny, spineless creature a closer genetic cousin to man than the fruit fly or worm, more widely studied model organisms. Results from the sequencing project are published in a special six-article section of Science.

Other surprises from the project: Urchins have the most sophisticated innate immune system of any animal studied to date. They carry genes associated with many human diseases, such as muscular dystrophy and Huntington's disease. The urchin also has genes associated with taste and smell, hearing and balance.

And these eyeless animals can see or at least sense light. How? Through their feet. Scientists found genes associated with vision, genes that are activated in the urchin's tube feet, puny projections on the animal's shells that help it move and feed.

"Nobody would've predicted that sea urchins have such a robust gene set for visual perception," said Gary Wessel, a Brown University biology professor and member of the Sea Urchin Genome Sequencing Consortium. "I've been looking at these organisms for 31 years and now I know they were looking back at me."

As part of the sequencing project, Wessel led the group of scientists who studied hundreds of thousands of letters of genetic code and identified the genes responsible for sea urchin reproduction. A professor in the Department of Molecular Biology, Cell Biology and Biochemistry at Brown, Wessel runs one of t
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Contact: Wendy Lawton
Wendy_Lawton@brown.edu
401-863-1862
Brown University
9-Nov-2006