SCIENCE

Applying a sophisticated method of gene screening to seawater samples retrieved from deep North Atlantic and Pacific waters, Sogin's team compared genetic sequences in their samples -- released from dead microbes -- with the sequences of known microbial genes. Some of the samples came from areas around a volcanic vent deep in the northeast Pacific Ocean. They concluded that deep-sea bacterial communities are perhaps 100 times more genetically complex than previously appreciated.

That enhanced diversity -- large numbers of bacterial species, each of which is relatively rare -- is serving today as a precious reservoir of genetic material that could help keep the oceans productive as global climate change takes a toll on today's dominant microbial species, they concluded in last week's issue of Proceedings of the National Academy of Sciences.

-- Rick Weiss

Airflow Above Ionosphere May Cause Disruptive Plasma

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Gigantic electrically charged gas bubbles that form in the upper reaches of the atmosphere -- sometimes disrupting radio, Global Positioning System and other transmissions -- are probably caused by a force similar to wind shear -- the meeting of winds traveling in opposite directions.

The bubbles, which can reach 1,200 miles high, were first identified in the mid-1970s as a cause for disruptions in satellite communications. But none of the proposed theories could explain why they formed.

New work by a NASA-funded research team, led by David L. Hysell of Cornell University, found that there is a westward flow of air just below the eastward-moving high ionosphere. The periodic meeting of the two is what is believed to set up a shear, which in turn produces waves that are the seeds of the bubbles.

The bubbles -- or, more formally, electrically charged plasma -- usually appear at night and occur somewhere above the globe on about 50 percent of evenings. They generally form about 250 miles above the Earth, almost always above the equator. Unlike more earthbound gas bubbles, these plasma formations do not burst but gradually diffuse into the atmosphere.

The researchers did their work on the Marshall Islands atoll of Kwajalein, in the Pacific Ocean near the equator, and used sounding rockets to measure wind speeds and directions in the ionosphere. Hysell said that the team's discovery could lead to better forecasting of the radio disruptions because "we now know what to look for."

The discovery was described in a series of papers published or submitted to geophysical journals, including the Journal of Geophysical Research.

-- Marc Kaufman