The Effect of X-Radiation on Enzyme Systems of Tetrahymena Pyriformis ,

Abstract

It had been shown previously by Eichel and Roth (1953b) that x-radiation at a level of 300,000 or 500,000 r depressed the respiration of Tetrahymena pyriformis W, 3 but did not appreciably affect the nuclease activity in homogenates prepared from irradiated whole cells. In irradiated homogenates, however, nuclease activity was reduced by approximately 50%. This paper presents some further observations of the effect of 300,000 to 600.000 r on respiration and several enzymes of T. pyriformis S. The S strain was chosen for two reasons; first, to obtain comparisons of the effect of x-radiation on respiration and deoxyribonuclease (DNase) activity in a strain different from that studied previously, and second, because the higher rate of succinate oxidation in the S strain (Eichel, 1954) would facilitate investigations of this specific enzyme system. The effects of x-radiation on catalase, and malic, glutamic, and succinic dehydrogenases, as well as some properties of succinic dehydrogenase and DNase, have also been observed. In addition, the effect of x-radiation on the oxidation of L-phenylalanine and acetate by the W strain has been studied.

Studies on the Metabolism of L‐Phenylalanine by Tetrahymena performs W*

“…However, results obtained by incubating cells. previously irradiated with 300,000 r of X-radiation ( 7 ) , with acetate or L-phenylalanine do not support this hypothesis. Thus, although acetate oxidation was greatly stimulated by the irradiation procedure, the oxidation of L-phenylalanine was considerably depressed.…”

Studies on the Metabolism of Tetrahymena pyriformis GL

“…In this respect, our results with acetate are markedly positive: even at rather excessive injury, restoration remains possible. At this point, strain GL or ganisms are comparable with irradiated strain S ciliates, which showed greatly increased oxidation of acetate [5,8]. As a result of the increase in acetate oxidation by irradiated cells, the net effect is a significant protective action achieved by treatment after irradiation, one of the few examples of such action.…”

Biochemical Studies on Irradiated Protozoa. I. Effect of Metabolites on the Respiration of X‐Irradiated Tetrahymena pyriformis*

“…Lactate markedly stimulated the respiration of control suspensions of Tetrakymena cells and oxidation of lactate by cells X a previous paper ( 5 ) , the effect of L-phenylalanine I and acetate on the ciliated protozoan. Tetrahymena pyriformis, irradiated with 300,000 r of X-radiation was studied.…”