Effects of radiation during space flight on microorganisms and plants on the Biosatellite II and Gemini XI Missions.

The results of recent experiments with the lysogenic bacteria, Escherichia coli and Salmonella typhimurium, the bread mold Neurospora crassa and the flowering plant Tradescantia on the Biosatellite II and Gemini XI Missions will be summarized. In the lysogenic bacteria experiment (Dr. Rudolf H.T. Mattoni, NUS Corporation) on the Biosatellite II mission significant effects of space flight were found on both growth rate and the induction of prophage. In that part of the Neurospora experiment on both the Biosatellite II and Gemini XI Missions (Dr. J.F. de Serres), utilizing non-dividing and inactive spores, no difference was found in the genetic effects of radiation between the flight and ground samples. In that portion of the Neurospora experiment on the Gemini XI mission utilizing rapidly-metabolizing spores the genetic effects of radiation were less serious in the flight samples than the ground samples. In the Tradescantia experiment (Dr. A.H. Sparrow, Brookhaven National Laboratory) on the Biosatellite II Mission, the irradiated flight material, in general, produced increased rates of cell death, abortion of pollen, loss of reproductive integrity, as well as other abnormalities in cell structure and function. In some of the experiments there were found significantly genetic effects of space flight alone, and the enhancement of various genetic effects of radiation under weightlessness was no more than 2- or 3-fold.