I recently found a very interesting news article regarding the longevity of the Greenland shark (Somniosus microcephalus). At first I didn’t quiet believe it, so I had a little dig to find the academic paper and my mind hasn’t stopped racing, pondering what it is that allows this mysterious animal to have such a long life.
The Greenland shark is an iconic a mysterious,deep-sea species of the Arctic Seas. it has a slow growth rate and can reach >500 centimetres (cm) in total length. the paper suggests a life span well beyond those of other vertebrates just shy of 400 years!!
The study radiocarbon dated the eye lens nuclei from 28 female sharks. Additionally from the research it was estimated that these fish reach sexual maturity at around 156 ± 22 years of age. This slow growth rate, and maturity age raises many concerns about the conservation of this species. Additionally it could have ramifications about the conservation of many other species of shark. Research into the age of sharks in limited, therefore there could be other species that have a longer longevity the current estimates.
Here’s a link to the paper http://science.sciencemag.org/content/353/6300/702.full
What about the Genetics?
The study gives us this information but it has left me wanting to know much more. One thing that has particularly sparked my interest is what genetic mechanisms allow such a long life? Are there a set of mutations which have caused this longevity? if so do we see the same mutations in other long-lived species?
Many studies, usually involving the genetic model organism Caenorhabditis elegans have found some genes that have been shown to promote longevity across taxa. However, how these genes do so still remains poorly understood. Various isoforms (any of two or more functionally similar proteins that have a similar but not identical amino acid sequence and are encoded by different genes) of the FoxO transcription factors, such as DAF-2 and DAF-16 have been shown to massively increase longevity in mutant C.elegans. Furthermore, a variant of FOXO3 has been shown to be associated with longevity in humans. It is commonly found the genome of most centenarians and a variety of ethnic groups around the globe.
I think it would be very interesting as a follow-up study with the Greenland shark to do a genome-wide functional genomic screen for longevity genes. I would imagine that a study like this is applying for funding or even in the early stages of study. Either way I do look forwards to see the results to such a study in the near future.