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EFFECTS OF SHORT DURATION MICROGRAVITY ON DROSOPHILA MELANOGASTER (FRUIT FLY) ACTIVITY.   M.S. Miller and T.S. Keller. Dept of Mechanical Engineering, Univ. of Vermont, Burlington.

                The effects of microgravity on Drosophila melanogaster (fruit fly) activity was examined during six KC-135 flights and one Nike-Orion sounding rocket launch. Previous investigator’s experiments on Cosmos satellites and Space Shuttle missions have shown a significant decrease in the life span of male fruit flies after microgravity exposure. Understanding the mechanism(s) behind this reduced life span could lead to important advances in the understanding of the aging process. The increased aging is hypothesized to be induced by an increased locomotor activity, driven by the Drosophila’s negative geotaxic response. This response is the tendency of the flies, when stimulated, to walk in the opposite direction of Earth’s gravitational vector. During microgravity exposure, Drosophila may become more active since they are confused by the lack of gravity and begin searching for the gravity vector. Two separate systems were used to determine fruit fly activity. A video system monitored 32 flies housed separately in either linear or circular tracks. An infrared system monitored an additional 240 flies, all housed in linear tracks, using 480 pairs of emitters and detectors. Locomotor activity is determined by counting the number of times than an infrared beam is broken per time period. Most Drosophila examined have had a normal geotaxic response, but a small number of flies with a large negative geotaxic response or positive geotaxic response have been flown to determine the effect of this trait. During the KC-135 flights, the infrared data on the normal geotaxic flies showed a significant increase in activity (p < 0.01) during portions of the microgravity exposure when compared to activity at 1 g. The non-normal geotaxic flies showed no increased activity during microgravity and their activity level was significantly different from the normal geotaxic flies (p < 0.01) throughout microgravity. Based on this data, Drosophila activity appears to increase during microgravity and may be related to the flies’ geotaxic response.

                (Supported by NASA: NGT-5135.)