Sweaty Human Evolution, Through a Mouse Lens
Mice are helping scientists learn about the evolution of some humans' sweat glands. In 2007, computational analyses revealed that some Asians carry a particular version of a gene called EDAR. To learn the effects of that version, called 370A, Harvard Medical School's Yana Kamberov and her colleagues developed a strain of mice that carried 370A instead of the usual EDAR gene. Those mice have thicker hair, more sweat glands (blue tubes in the mouse footpad, above), denser mammary glands, and smaller fat pads around those mammary glands, the researchers report this week in Cell. The team also evaluated sweat gland density in Han Chinese carrying one or two copies of 370A and found that those with two copies had more sweat glands. "It's one of the first papers that clearly shows that a change that was important in recent human evolution can be modeled in the mouse," says Wolfgang Enard, an evolutionary geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The analysis suggests 370A arose in Central China 30,000 years ago and may have been favored as an adaptation to the humid environment. http://scim.ag/sweatyev
First Evidence of Life Under Antarctic Ice
Researchers have gotten the first glimpse of life lurking beneath Antarctic ice. Last month, a U.S. team drilled through 1000 meters of ice to reach subglacial Lake Whillans, part of a complex hydrological system in West Antarctica—and on 7 February the team announced that they now have obtained the first evidence of microbial life in a subglacial Antarctic lake.
Last month, a team of Russian scientists announced that they had successfully sampled another subglacial lake located thousands of kilometers away on the East Antarctic Ice Sheet; what microbes might exist in those waters are still unknown. But the two systems are very different: Unlike Lake Vostok, the Whillans system has been in periodic contact with surface waters, rather than isolated from the rest of the planet for millions of years. The team, which is seeking clues not only to glacial microbiology but also to ice sheet dynamics and the impact of climate change on the continent, hopes the Lake Whillans microbial community can shed light on organisms that can exist in the extreme dark and cold, and how such microbes might affect the chemistry of the ice.
Proto-RNA: Clues to Origin of Life
Origin of life researchers have long thought that RNA, the molecular cousin of the DNA that encodes our genes, may have played a starring role in the initial evolution of life from a soup of organic molecules.
But there are problems with this "RNA World" hypothesis. For starters, in water, the four chemical components of RNA, the nucleotides abbreviated A, G, C, and U, don't spontaneously assemble to create sizable molecules. So it remains a mystery how the first long gene-length chains of RNA would have ever taken shape in Earth's ancient environment.
Now, researchers led by Nicholas Hud, a chemist at the Georgia Institute of Technology in Atlanta, report in the Journal of the American Chemical Society that they have created a pair of RNA-like molecules that can spontaneously assemble into genelength chains in water. Although it's likely to be difficult to determine whether these proto-RNAs or others like them were present at the dawn of life, the researchers are now working to see if the proto-RNAs can indeed faithfully encode information and evolve toward RNA. http://scim.ag/RNAlife