Word: bacteria
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Working with antibiotic-resistant bacteria, a new study by evolutionary biologists at Harvard suggests that a vast majority of evolutionary pathways for organisms are closed off by natural selection. Daniel M. Weinreich, a post-doctoral fellow in the Department of Organismic and Evolutionary Biology, headed a study—published in the journal Science last week—of the development of antibiotic resistance in E. coli. In particular, the scientists studied five point mutations that increases anti-biotic resistance in bacteria by five orders of magnitude. Since the overall mutation requires five sequential steps, there are 120 pathways from...
...prepared the way for the tetrapods. The plants created new aquatic habitats by stabilizing the banks of rivers and streams. They pumped oxygen into the atmosphere, making the earth habitable for large, air-breathing creatures. And they shed organic debris that formed the basis of a new food chain. Bacteria, fungi and small arthropods (the animal group that includes crustaceans and insects) moved in to feed on the debris; small fish moved in to eat the arthropods; bigger fish moved in to eat the small fish. Among them were the fishapod's lobe-finned ancestors, which found in the vegetation...
...human fecal matter and represents a significant health threat, which is why the U.S. Environmental Protection Agency requires that E. coli levels in public waters be closely monitored. E. coli also grows in the guts of geese, cows and other animals, but the disease risk from nonhuman fecal bacteria is considerably lower...
Sadowsky and his fellow researchers have found a way to tease out stretches of marker DNA that indicate whether the bacteria came from human or nonhuman sources. With cities and states across the country spending billions on new water-quality systems, the impact of Sadowsky's work could be huge...
...sample about 40,000 bacterial colonies at once. Using markers for geese that he pinpointed, he successfully identified geese as the source of contamination at a Lake Superior beach last year--allowing a beach to remain open that otherwise would have been closed. Identifying DNA markers for human fecal bacteria is next on his list...