Phototaxis in the flagellate, Euglena gracilis, under the effect of microgravity.
Positive phototaxis was analyzed in the unicellular photosynthetic flagellate, Euglena gracilis, under the conditions of microgravity during a parabolic rocket flight (TEXUS experiment). The fluence rate at which positive phototaxis changes to negative phototaxis was the same in a sample which had previously been exposed to microgravity as in a sample which had not been exposed to microgravity. During weightlessness the precision of positive phototaxis is higher than at 1 g at the same fluence rate. The swimming velocity of the cells is higher at 0 g than at 1 g confirming previous results that under terrestrial conditions the cells are subject to simultaneous sedimentation while they swim upward. Tracks of organisms recorded at 0 g show much more frequent deviations from the straight path than those at 1 g.
Kuhnel-Kratz
C h
Ch
Institut fur Botanik und Pharmazeutische Biologie, Friedrich-Alexander-Universitat, Erlangen, Germany.
Schafer
J
J
Hader
D P
DP
D000818:Animals; D005056:Euglena gracilis / Q000502:physiology / Q000528:radiation effects*; D008027:Light; D009043:Motor Activity / Q000502:physiology / Q000528:radiation effects*; D009949:Orientation; D010775:Photic Stimulation; D013026:Space Flight / Q000295:instrumentation*; D013550:Swimming; D014743:Videotape Recording; D014893:Weightlessness