20 Feb 2019

ciimar work on the white shark genome

An international consortium involving the CIIMAR researcher Agostinho Antunes decodes the genome of the iconic white shark and reveals key adaptations in its genes involved in wound healing and DNA stability linked to cancer protection.



The study, published in the prestigious scientific journal "Proceedings of the National Academy of Sciences of the United States of America" ​​(PNAS), presents the genome of the great white shark (Carcharodon carcharias), one of the most charismatic marine animals among the public.

This international consortium of researchers was led by scientists from the Nova Southeastern University in Florida, USA, who compared the DNA of the white shark (Carcharodon carcharias) with other species: from humans to the whale shark. The geneticist Agostinho Antunes, coordinator of the Group of Evolutionary and Bioinformatics Genomics of CIIMAR, was part of this consortium and then was thus involved in this important scientific work of decoding the genome of this iconic predator, and thus understanding  the biology of sharks in general.



The data revealed that the great genetic content of white shark is enriched with mechanisms that increase the stability of the DNA acting as defenses against DNA damage. These data emphasize a selective pressure that combines: the large size of the genome, high repetition content, high representation of retrotransposons, large body size and also long lifetime. In fact, the white shark can reach 73 years of life and the whale shark can reach 140 years.



These adaptive mutations were found in genes closely linked to DNA repair, DNA damage response and DNA damage tolerance, among other genes, allowing greater resistance to aging among other diseases. The opposite phenomenon, the instability of the genome, which results from accumulated DNA damage, is well known and predisposes humans to numerous cancers and diseases related to aging. The study also notes molecular adaptations for wound healing, with positive selection in key genes involved in the healing process.



In addition to the evidence already mentioned, it is also important to note that the white shark has an acute sense of smell. However, the study revealed a genome with very few olfactory receptor encoding genes, an aspect that strongly contrasts with the large number of olfactory genes present in mammals (which is considered to be the largest family of genes in this group of living beings). Nevertheless, the high number of copies of vomeronasal genes found in white shark (13), whale shark (10) and elephant shark (30) suggest that this gene family may explain the strong olfactory sense of these cartilaginous fish.



The impacts of the study published in the bulletin of the American National Academy of Sciences have wide applications: in addition to helping to direct the conservation efforts for this and other species of sharks, may also be useful for studies related to cancer and aging diseases, as well as to improve the treatment enhancing the healing process in humans.