Sharks can heal themselves, resist mutations in their genes thanks to evolution

The great white shark — one of the most fearsome predators in the world’s oceans in both fact and fiction — is a formidable creature, right down to its genes. Scientists on Monday said they have decoded the genome of Earth’s largest predatory fish, detecting numerous genetic traits that help explain its remarkable evolutionary success, including molecular adaptations to enhance wound healing as well as genomic stability such as DNA repair and DNA damage tolerance. The great white shark, whose scientific name is Carcharodon carcharias, boasts a very large genome, 1-1/2 times bigger than the human genome. [caption id=“attachment_6116281” align=“alignnone” width=“1280”] An evolutionary wonder.[/caption] In theory, large genomes with a lot of repeated DNA, like this shark possesses, and its large body size should promote a high incidence of genome instability, with much more DNA and many more cells seemingly vulnerable as targets for damage through an accumulation of routine mutations. Just the opposite seems to be the case for this shark, thanks to adaptations in genes involved in preserving genome integrity. “This knowledge, in addition to providing understanding into how sharks work at their most fundamental level — their genes — may also be useful in downstream applications to human medicine to combat cancers and age-related diseases that result from genome instability,” said Mahmood Shivji, director of the Save Our Seas Foundation Shark Research Center and Guy Harvey Research Institute at Nova Southeastern University in Florida. [caption id=“attachment_6116291” align=“alignnone” width=“1280”] Sharks had 400 million years on the Earth to evolve to their current forms. Are they the new cockroaches? The new ultimate survivor?[/caption] This species, star of the 1975 Hollywood blockbuster “Jaws” and its multiple sequels, roams the world’s oceans, primarily in cool coastal waters. Gray with a white underbelly and torpedo-shaped body, it can reach 20 feet (6 meters) long, weigh 7,000 pounds (3.18 tonnes) and dive to nearly 4,000 feet (1,200 meters) deep. It uses its mouthful of large, serrated teeth to rip into prey including fish, seals and dolphins, swallowing mouth-sized chunks of flesh whole. Sharks are an evolutionary success story, thriving for more than 400 million years. Our species appeared roughly 300,000 years ago. The great white shark also displayed genetic adaptations in several genes that play fundamental roles in wound healing. For example, a key gene involved in producing a major component of blood clots was found to have undergone adaptations. “These adaptations and enrichments of essential wound-healing genes may underlie the ability of sharks to heal from wounds so efficiently,” said Cornell University’s Michael Stanhope, co-leader of the research published in the Proceedings of the National Academy of Sciences.