Because of their slow rate of evolution, researchers are able to look at a shark’s DNA as a sort of “living fossil,” according to a new study by the RIKEN Center for Biosystems Dynamics Research in Japan.
Scientists, led by Riken’s Shigehiro Kuraku, analyzed shark genomes using cutting-edge DNA sequencing technologies and comparative bioinformatics on three species of sharks — the brownbanded bamboo shark and the cloudy catshark, chosen for their availability at local aquariums, and the whale shark. They found that the shark’s large genome size is due to massive insertions of repetitive elements.
Because sharks have kept many ancestral gene repertoires, the researchers believe that mapping the genomes may unlock some of their unique characteristics, including body structures, reproductive systems, sensory systems, and extreme longevity on a molecular level.
“Our results will fill a long-standing gap in the genome biology of animals, and will also help us gain greater understanding about metabolism, reproductive cycle, and health monitoring of sharks,” author and the deputy director of Okinawa Churaumi AquariumKeiichi Sato said. “Such understanding should contribute to the conservation of marine environments as well as to sustainable husbandry and exhibitions at aquariums that allow everyone to experience biodiversity up close.”
The team, which published their findings in the latest issue of the journal Nature Ecology and Evolution, found that sharks have counterparts of human genes regulating growth, reproduction, and homeostasis, such as obesity, appetite, and sleep. This suggests that elements of the molecular machinery for basic physiology has existed for over 450 million years before sharks split from mammals common ancestors.