Mutational responses of insects in the Biosatellite II experiment.

Genetic effects associated with space flight include mutation induction by the space flight itself, and enhancements or antagonisms of radiation-induced mutations. The conditions of space flight vary in mutagenic effectiveness from no response at all to responses nine times that found in ground-based controls. The test systems follow the sensitivity pattern: spermatogonial translocations > oogonial and oocyte nondisjunction > recessive lethality of stages in spermatogenesis > dominant lethality of stages in spermatogenesis. Large enhancing and antagonistic effects of space flight in conjunction with radiation were observed in the Biosatellite II experiment. The most surprising one was the elimination of the effect of 2500 R by space flight in Habrobracon oogonia where the effects of 500 R normally can be easily observed. Two sets of parameters are considered in attempts to explain the responses: (1) the nature of the biological targets, and (2) the particular conditions of space flight that are responsible for the effects.