Full Analysis of Mammoth Genome Published
Late last month (June 2015) a team of researchers at the University of Chicago Medical Centre published an analysis of the entire woolly mammoth genome. The analysis revealed 1.4 million unique genetic variations which would have adapted the mammoths to their life in the snowy tundra.
Mammoths have long fascinated humanity. Our ancestors lived alongside them and they are depicted in our earliest art works. Up until 10,000 years ago the mammoths would have been a common sight across the tundra of North America and Europe, but at some point the pressure of climate change or over hunting by humans drove them to extinction. Despite this we have recovered dozens of beautifully preserved specimens and some of them have even yielded DNA. Until now though attempts to fully analyse the sequence have been unsuccessful or have only managed to examine a handful of genes. Instead this study examined the fully genomes of two woolly mammoths and compared them to the sequence from 3 Indian elephants (their closest living relatives). They then compared these sequences to that of an African elephant which allowed the team to identify those genes unique to the mammoths.
The results were impressive. The team found 1.4 million individual genetic variants which altered the protein sequences controlled by around 1,600 genes. These genes controlled many different traits that would have helped the mammoths adapt to the extreme conditions of the frozen northern hemisphere. Amongst these were genes controlling fat metabolism, insulin regulation, skin and hair development (specifically genes for lighter hair colour), the circadian clock and also temperature sensation. This latter characteristic is controlled by a gene called TRPV3 which is still found in modern elephants. In order to test the mammoth version the researchers recreated it in the lab and injected it into human cells in culture. The results were that the mammoth variant of the gene produced proteins which was far less responsive to heat then the ancestral elephant version.
This analysis seems to show that mammoths were highly adapted to their frigid homes with many physiological changes as well as the obvious physical ones such as thick hair and smaller ears. However, the researchers were quick to point out that this information doesn’t prove anything about how real mammoths lived, because it is impossible to judge environmental effects on development and changes in gene expression from the genome alone.
Reference: Lynch, V.J. et al. 2015. Elephantid Genomes Reveal the Molecular Bases of Woolly Mammoth Adaptations to the Arctic. Cell Reports.
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