The role of weightlessness in the genetic damage from preflight gamma-irradiation of organisms in experiments aboard the Salyut 6 orbital station.

The effect of weightlessness on chromosomal aberration frequency in preflight irradiated Crepis capillaris seeds, on the viability, fertility and mutation frequency in Arabidopsis thaliana, and on the frequency of nondisjunction and loss of X chromosomes in pre-flight irradiated Drosophila melanogaster gametes was studied aboard the Salyut 6 orbital station. The following effects were observed: a flight-time dependent amplification of the effects of preflight gamma-irradiation in A. thaliana with respect to all the parameters studied; unequal effects in seeds and seedlings Crepis capillaris; and a significant increase in the frequency of nondisjunction and loss of chromosomes during meiosis in Drosophila females. These observations are discussed in terms of the data of ground-based model experiments and flight experiments with a different time of exposure of objects to weightlessness. An attempt is made to elucidate the role of weightlessness in the modification of ionizing radiation effects.