Science has moved a small step closer to a 21st century version of the the woolly mammoth, after they found the genetic alterations that enabled the extinct giants to adapt to Arctic environments.
Mammoth genes, according to the study, differed from their counterparts in elephants in fat metabolism, skin and hair development, insulin signaling and multiple other traits. The genes associated with physical traits, like skull shape, small ears and short tails, were also identified.
Study author Vincent Lynch, PhD, assistant professor of human genetics at the University of Chicago, said:
“This is by far the most comprehensive study to look at the genetic changes that make a woolly mammoth a woolly mammoth. They are an excellent model to understand how morphological evolution works, because mammoths are so closely related to living elephants, which have none of the traits they had.”
Earlier attempts to sequence preserved mammoth DNA were error-prone or yielded data concerning only a limited number of genes.
Woolly mammoths lived on the frigid tundra steppes of northern Asia, Europe and North America roughly 10,000 years ago.
They have been well-studied because of the amount of skeletons, frozen carcasses and depictions in prehistoric art. Woolly mammoths had long, coarse fur, a thick layer of subcutaneous fat, small ears and tails and a brown-fat deposit behind the neck which may have functioned similar to a camel hump.
Lynch and his team deep sequenced the genomes of two woolly mammoths and three Asian elephants, the closest living relative of the mammoth. Then they compared these genomes against each other and against the genome of African elephants, a slightly more distant evolutionary cousin to both mammoths and Asian elephants.
The team found around 1.4 million gene variants unique to woolly mammoths.
The variants caused changes to the proteins produced by around 1,600 genes, including 26 that lost function and one that was duplicated. To discover the effects of these differences, they ran numerous computational analyses, including comparisons to massive databases of known gene functions and of mice in which genes are artificially deactivated.
“We can’t know with absolute certainty the effects of these genes unless someone resurrects a complete woolly mammoth, but we can try to infer by doing experiments in the laboratory,” Lynch said.
The researchers are now identifying candidates for other mammoth genes to functionally test as well as planning experiments to study mammoth proteins in elephant cells.
Vincent J. Lynch, Oscar C. Bedoya-Reina, Aakrosh Ratan, Michael Sulak, Daniela I. Drautz-Moses, George H. Perry, Webb Miller, Stephan C. Schuster
Elephantid Genomes Reveal the Molecular Bases of Woolly Mammoth Adaptations to the Arctic
Cell Reports DOI: http://dx.doi.org/10.1016/j.celrep.2015.06.027
Illustration: Vincent J. Lynch et al, CC BY-NC-ND license
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