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Gene-packing viruses spread evolution worldwide
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14:51, March 13, 2008

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Viruses carry tiny packages of genes around the globe in the process of spreading the key of evolution to other organisms, reports a new study.

This finding comes from a new study of the viruses and bacteria found in nine distinct locations on Earth and sheds light on the complex power swaps among viruses called phages and their bacterial hosts.

Bacteria are tiny, one-celled living organisms whose bodies are much more complex than those of viruses. The largest viruses are about the size of the tiniest bacteria. Antibiotics usually kill bacteria, but they have no effect on viruses.

"We've found previously that the viruses can move between biomes [ecological communities] pretty easily," co-researcher Forest Rohwer, a biologist at San Diego State University, told LiveScience. "So in theory they should be able to move things from one part of the world to another. These viral populations seem to be serving as reservoirs of genes that the microbes use."

That means genes that would confer environmental protection or some other adaptive tool could trek long distances via viruses from bacteria in one part of the world to another region.

The researchers collected samples of bacteria and viruses from nine major ecological communities: underground mines, highly saline ponds, coral reefs, oceans, bodies of freshwater, fish farms, humans and mosquito-associated areas, and sedimentary "fossils," which contain records of microbial life on Earth.

Using a technique called metagenomics, the team identified the genes and their relative abundances for entire communities of bacteria and viruses found in each environment. The genetic profile for each biome was found to be distinct. The team then focused on the abundant genes from each environment to learn more about their known functions.

In fish farms, the researchers found the viruses delivered "eating" genes to bacteria. The genes allowed bacteria to take advantage of so-called taureen, a sulfur-based acid added to fish food and not normally a part of the microbe's diet.

Viruses hanging out in coral-reef systems held a stash of genes for mucus eating. The genes were also found in the environment's bacteria, suggesting the viruses transferred the genes to the bacteria. In that way, the bacteria could slurp up mucous-like substances produced by coral.


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