Science  26 Aug 2011:
Vol. 333, Issue 6046, pp. 1077

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  1. Fossil Cells Are World's Oldest

    Scientists say they have discovered 3.4-billion-year-old cells, possibly the oldest fossils ever found. Geologists Martin Brasier of the University of Oxford in the United Kingdom and David Wacey of the University of Western Australia in Crawley discovered the fossil cells between cemented sand grains from an ancient beach in Western Australia.

    The fossil cells were hollow, and some were clustered together in groups surrounded by what looked like a membrane. “The morphology is very cell-like,” Brasier says. The cells were also patchily distributed in the sediment, just as modern bacteria tend to congregate near sources of food, the researchers reported online 21 August in Nature Geoscience.

    Old cells.

    Ancient life (inset) found in Australia.


    The two scientists say their chemical analyses of the minerals near the cells suggest the microorganisms depended on sulfur for fuel. Such a beach might have been life's first breeding ground, Brasier says.

    The work represents “some of the best evidence for the nature of Earth's earliest life,” says Bruce Runnegar, a geologist at the University of California, Los Angeles, who was not involved in the study.

  2. Helping Fat Mice Live Longer

    They work in mice—but will they work in people? That's one question hanging over a class of compounds intended to boost SIRT1, a protein thought to mimic the effects of calorie restriction. In a host of animals, slashing calories extends life and preserves health—and a study in Scientific Reports published 18 August shows that a particular SIRT1 booster helps obese mice live longer. The drug cut the amount of fat in the animals' livers and made them more responsive to insulin. It also prolonged their lives by 44% compared with control mice—but the obese animals still died earlier than normal mice. Closely related compounds are currently in clinical trials in people.

    The new study is at odds with an earlier study by a group at Pfizer, which reported that this compound and others like it don't activate the SIRT1 protein, and that they have many unintended targets in the body, suggesting they're unlikely to make good drugs.

  3. Disease-Fighting Mosquitoes Proliferate in Field Test


    A mosquito strain specially created to fight dengue, a viral disease that causes headaches, rash, and excruciating muscle and joint pains, has shown promise in its first open field study in two small towns in northern Australia.

    The experimental mosquitoes—a species called Aedes aegypti, which is dengue's main vector—are infected with a strain of Wolbachia pipientis, an intracellular bacterium that makes the insects virtually unable to transmit dengue but also has a way of spreading rapidly through their populations by playing strange tricks with their sex lives (Science, 10 December 2010, p. 1460). Led by Scott O'Neill from Monash University in Melbourne, the team released between 10,000 and 20,000 infected mosquitoes weekly in each of the towns for 10 weeks. Six weeks after the final release, the entire population in both towns had become infected, the team reported 25 August in Nature.

    The study wasn't designed to have an effect on dengue, which is rare in Australia. Field tests in Vietnam, Indonesia, Thailand, and Brazil, all endemic countries, are awaiting approval; O'Neill says the first released could happen within a year.