Scientists Sequence Genome of African Coelacanth

Posted on April 20, 2013

Scientists have sequenced the genome of the African coelacanth, which is often described as a living fossil. Modern coelacanths closely resemble the fossilized skeletons of their more than 300-million-year-old ancestors. The fish was thought to be extinct before one was discovered off the African coast in 1938.

The coelacanth is a five-foot long cave dwelling fish. It has fleshy lobed fins that resemble the limbs of land-dwelling animals. The researchers say they found several important regions of the genome used in the formation of limbs, which suggest that land animals dopted these sequences from coelacanths to help them form limbs. The researchers also found that there are many regulatory changes that influence genes involved in the perception of smell, as creatures that transitioned to land needed a new means of detecting chemicals in the environment.

Prof. Byrappa Venkatesh, Research Director IMCB, whose group was involved in the project said in a statement, "The coelacanth with its distinctive fleshy fins represents an intermediary phase in the evolution of land animals from aquatic fishes. By comparing the genomes of coelacanth, human and other vertebrates our group has been able to discover gene regulatory elements that played a key role in the development of our limbs and fingers as well as our ability to detect air-borne odorants. Mutations in these elements can potentially lead to genetic diseases."

Researchers also found that genes in coelacanths are evolving more slowly than in other organisms. Jessica Alfoldi, a research scientist at the Broad Institute and co-first author of a paper on the coelacanth genome, said in a statement, "We found that the genes overall are evolving significantly slower than in every other fish and land vertebrate that we looked at. This is the first time that we've had a big enough gene set to really see that."

The research findings were published here in the journal, Nature.