David W. Barnes, Ph.D.

Elasmobranchs (sharks, rays, and skates) are evolutionarily among the earliest arising vertebrates. We study the cell and molecular biology of these animals.  Elasmobranchs have a cartilaginous skeleton, unlike the bony fish that make up the majority of marine and freshwater vertebrate species, and were among the first animals to exhibit jaws, adaptive immunity, and a pressurized circulatory system. We have derived cell cultures from early embryos of both sharks and skates and examined the genes expressed in the cells of these cultures. We have compared shark gene sequences with those from a number of other species (bony fish, amphibians, birds, and mammals, including humans).  We have specifically looked for nucleotide sequences in areas of the genome that do not code for proteins and therefore would not be expected to be maintained in a similar sequence pattern over the long (400 million-year) period of divergence between sharks and the later arising vertebrates.

In about one percent of the genes we examined, we found that long stretches of noncoding nucleotide sequences were remarkably similar among many of the species. This included comparisons between sharks and humans. Also interesting is the observation that the genes we identified were all related to cellular growth or development, although we had not set out to search specifically for such genes. The long evolutionary conservation of these nucleotide sequences suggests that they may have some importance in controlling gene expression related to growth, development, or other processes within the cell. We are currently attempting to identify the signals these sequences might be providing within the genome to affect gene expression. 

Recent PubMed Publications

Cell and Molecular Biology of Marine Elasmobranchs

Elasmobranchs (sharks, rays and skates) are evolutionarily among the earliest arising vertebrates. We have derived cell cultures from early embryos of both sharks and skates and examined the genes expressed in the cells. We have compared noncoding shark mRNA sequences with those from a number of other species (bony fish, amphibians, birds, and mammals, including humans). We found some of the genes examined showed long stretches of noncoding nucleotide sequences that were remarkably similar among many of the species. Currently we are attempting to identify the signals these sequences might be providing within the genome to affect gene expression. Students would be involved in both molecular biological experiments and cell biological experiments with cultured cells of marine and mammalian origin.