Metabolism of Ribonucleic Acid and of Proteins in X-irradiated Isolated Thymus Nuclei

Summary

Effects of x-rays on the uptake of adenine-¹⁴C and phenylalanine-¹⁴C have been studied. An inhibition of about 20 per cent of the uptake of phenylalanine is found after 300 rads, and there is no further inhibition if the dosage of x-rays is increased. A similar response is sometimes found in the case of the uptake of adenine, but there is often no inhibition at all and even sometimes an increase in adenine uptake. It had been postulated that this behaviour might be explained by the existence of various RNA or protein fractions having different functions and responding differently to x-radiation. Fractionation experiments in order to test this hypothesis have been done; but no clear-cut results have been obtained.

It has also been shown that incubating irradiated nuclei with high concentration of denatured DNA restores the uptake of the amino acids.