Geneticists have sequenced the DNA of the elephant shark, the first member of the shark family to be decoded. Cartilaginous fishes-such as sharks, rays, and skates-diverged from bony vertebrates 450 million years ago. The new study revealed a family of genes that may help explain that transition. Zebrafish with these genes knocked out experienced reduced bone formation, a finding that could aid research on bone-related diseases. More surprising, the elephant shark lacked the CD4 genes related to immune function, including ones considered vital for defense against infections and for preventing autoimmune disorders.
展开▼
