The Gemini-XI S-4 Spaceflight-Radiation Interaction Experiment. III. Comparison of the Spectra of Recessive Lethal Mutations at Specific Loci in the ad-3 Region in Neurospora crassa

Samples of asexual spores of a two-component heterokaryon of Neurospora crassa collected on Millipore filters or in suspension, were flown aboard the Gemini-XI spacecraft in September 1966 to permit an evaluation of the genetic effects of radiation in combination with weightlessness. A ground-based experiment was performed simultaneously as a control. The samples were exposed to different amounts of32 P β-irradiation and survival levels and forward-mutation frequencies in the ad-3 region were studied. Characterization of the ad-3 mutants has been performed by a series of genetic tests to determine the spectra of genetic alterations in the in-flight and ground control samples. These tests have shown that there is no difference between the spectra of genetic alterations in the in-flight and ground samples irradiated on filters. These tests have also shown that the lower frequencies of forward-mutation in the in-flight samples irradiated in suspension was due to a specific effect on point mutations (<tex-mat...