INFLUENCE OF ACCELERATIONS ON THE SPATIAL ORIENTATION OF LOXODES AND PARAMECIUM

The gravitactic ciliates Paramecium and Loxodes were cultivated for 15 days in space during the IML-2 spacelab mission. At dedicated times t heir behavioral responses to different accelerations between 10(-3) x g and 1.5 x g were investigated by using a slow rotating centrifuge mi croscope (NIZEMI). The threshold for gravitaxis of Paramecium was foun d to be at >0.16 x g and less than or equal to 0.3 x g. No adaptation of Paramecium to the conditions of weightlessness was observed over th e duration of 15 days. Loxodes showed no graviresponses to increasing accelerations, though it demonstrated gravitaxis after return to earth .