Tibetans Inherited High-Altitude Gene From Ancient Human

A “superathlete” gene that helps Sherpas and other Tibetans breathe easy at high altitudes was inherited from an ancient species of human. That’s the conclusion of a new study, which finds that the gene variant came from people known as Denisovans, who went extinct soon after they mated with the ancestors of Europeans and Asians about 40,000 years ago. This is the first time a version of a gene acquired from interbreeding with another type of human has been shown to help modern humans adapt to their environment.

Researchers have long wondered how Tibetans live and work at altitudes above 4000 meters, where the limited supply of oxygen makes most people sick. Other high-altitude people, such as Andean highlanders, have adapted to such thin air by adding more oxygen-carrying hemoglobin to their blood. But Tibetans have adapted by having less hemoglobin in their blood; scientists think this trait helps them avoid serious problems, such as clots and strokes caused when the blood thickens with more hemoglobin-laden red blood cells.

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Breathing easy. This Tibetan inherited a beneficial high-altitude gene from archaic Denisovan people.

Beijing Genomics Institute

Source: sciencemag

Antibiotics not promote resistance through gene conjugation.

The exponential rise of antibiotic drug resistance is a considerable threat to global public health. Researchers are continually searching for the underlying mechanisms that promote this resistant phenotype. Some evidence exists to suggest that antibiotic use encourages the spread of bacterial resistance through genetic swapping. However, new research suggests that these examples are outliers and not indicative of the majority of bacterial populations.

Researchers at Duke University suggest that differential birth and death rates of microbes and not DNA donation are to blame. The results have implications for designing antibiotic protocols to avoid the spread of antibacterial resistance. 

"The entire field knows there's a huge problem of overusing antibiotics," noted senior study author Lingchong You, Ph.D., associate professor of engineering at Duke University. "It is incredibly tempting to assume that antibiotics are promoting the spread of resistance by increasing the rate at which bacteria share resistant genes with each other, but our research shows they often aren't."

Investigators have known for decades that bacteria can swap genetic elements through a process called conjugation, which allows helpful genes to spread quickly between individuals and even between species. Because the number of resistant bacteria rises when antibiotics fail to kill them, many researchers have assumed that the drugs increased the amount of genetic swapping taking place. The Duke researchers, however, hypothesized that the antibiotics were killing off the two "parent" lineages and allowing a newly resistant strain to thrive instead.

Read more: Antibiotics not promote resistance through gene conjugation.

Source: biologyexams4u