The Greenland shark is known to be elusive, for years effectively hiding its most astounding traits. The sluggish creatures lurk primarily in the deep, cold waters of the North Atlantic and Arctic oceans and are the only sharks to withstand the freezing temperatures year-round. Some individuals of the species might have been swimming there since colonial times — and researchers are just beginning to unravel how.
epresentation of its genome, add to what’s known about the sharks’ structure and how their bodies function, but it also provides clues to why the animals have such staying power, the researchers said.
“Only with the genome assembly we can really understand which, for instance, mutations have accumulated in the shark that led to this enormous lifespan,” said Dr. Steve Hoffman, senior author of new research on the Greenland shark and a computational biologist at the Leibniz Institute on Aging in Germany. “To this end, this genome is some kind of a tool, if you will, that allows us, and of course also other researchers, to look into these molecular mechanisms of longevity.”
However, it seems that in the Greenland shark, the genes that repair DNA have been acting as jumping genes, distributing themselves into the genome and slowing down the aging process by fixing damaged DNA. As a result, “the detrimental effect of these transposable elements (jumping genes) is not only canceled out, but maybe even reversed so that the genome integrity is even better in the Greenland shark,” said lead author Dr. Arne Sahm, a bioinformatician and junior professor at Ruhr University Bochum in Germany.
The authors suggest that DNA repair genes in the species at some point evolved the ability to multiply, further contributing to DNA repair and in turn longevity. The researchers want to explore and analyze the Greenland shark’s DNA further, while also comparing its genome with other shark species and shorter-lived fish, to provide additional evidence for this unique trait, Hoffman said.
Studying the Greenland shark
Before the researchers sequenced the Greenland shark’s genome, only about 10 genomes were available for all elasmobranchs — a subclass of fish including sharks, rays and skates — said Dr. Nicole Phillips, an associate professor of ecology and organismal biology at the University of Southern Mississippi in Hattiesburg. Phillips was not involved in the research conducted by Hoffman, Sahm and their team.