Biologists from the U.S., Europe and Japan who study the effects of gravity on living organisms will meet NASA engineers working on the International Space Station at a conference in Davis, Calif. this week. Chuck Fuller, professor of exercise science at the University of California, Davis, is co-host of the meeting, together with Charles Wade of NASA's Ames Research Center. The meeting will bring together scientists who study the effects of gravity on very different organisms, said Fuller. Previously, there has been little interaction between those studying the effects of gravity on plants, animals and cells, he said. "This is the ultimate knowledge required for long-term space exploration," said Fuller, who has worked with both the U.S. and Russian space programs to study the effects of weightlessness on the body. "The point is to look at where we stand right now with preparation for the space station," said Wade. By bringing the group together, they hoped to stimulate the scientific community to use the unique facilities of the space station, he said. When astronauts are weightless for more than a short time, bones lose calcium, muscles wither, and blood moves from the legs to the face and head, said Fuller. The heart becomes weaker, because it has less resistance to push against. There are also changes in circadian rhythms, temperature regulation and body composition. Scientists study the effects of gravity on the body using centrifuges. In a typical experiment, the centrifuge is used to increase gravitational force to double normal gravity, or 2g, he said. By looking at the effects of gravity in a range from 1 g to 2 g, scientists could estimate the effects of gravitational forces outside this range, said Fuller. Recent research in humans and animals shows that changes in gravity cause shifts in metabolism, said Fuller. Space shuttle astronauts chose less fatty meals, but did not lose body fat. Research in Fuller's laboratory has shown that metabolic shifts are triggered by the effects of gravity on the inner ear. Genetically modified mice which do not have gravity sensors in the inner ear do not show these responses to increased gravity, said Fuller. Experiments on the space shuttle and the Russian Mir space station showed how organisms behaved in near-zero gravity, but it was difficult to separate these effects from other environmental factors such as noise, air pressure and radiation, said Fuller. The International Space Station will be equipped with a 2.5 m centrifuge capable of producing increased gravity fields during spaceflight, according to Fuller. "This will allow us to study the response of organisms to gravity fields from zero to 1g, and to simulate gravity on Mars or the Moon," said Fuller. Results from space station 1 g experiments would be compared with those from ground-based labs. Differences between them would be caused by environmental factors in space other than weightlessness, he said. The meeting, which is organized by the Galileo Foundation and sponsored by NASA, runs through Wednesday at the Hallmark Inn, Davis. The Galileo Foundation is a not-for-profit organization that facilitates international exchanges between gravitational biologists. UC Davis has been a leader in gravitational biology research for almost 40 years, since the establishment of the Chronic Acceleration Research Unit under professor emeritus Arthur Smith. More information: -- http://www.galileofndn.org/ -- http://spaceflight.nasa.gov/station/science/life/centrifug