The Effect of Roentgen Rays and Ultraviolet Radiation on the Permeability of Yeast

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Abstract
Irradiation with a dose of 30,000 r, sufficient to kill about 10% of the yeast cells, influenced the amt. of free radio-phosphorus and radio-potassium (P32 and K42, respectively) migrating daily from the yeast cells into the nutrient soln., and thus the cell permeability, but only to a very slight extent. The amt. of migrating P32, but not however of K42, was greatly increased after irradiation with a sublethal dose of u.v. radiation. Irradiation does not increase the free phosphate content of yeast cells. The phase boundary is thus influenced by the effect of the radiation. The migration of intracellular P32 into the nutrient soln. is not an interchange process, as the same percentage of P32 migrates into a phosphate-containing as into a phosphate-free soln. When the yeast cells were shaken with a nutrient soln. containing arsenate, the amt. of immigrating free P32 and K42 was found to be reduced to about half their normal values.