Abstract
A Mycobacterium (strain Jucho) was irradiated with ultraviolet light, and a comparison of the amounts of nucleic acids, incorporation of P32-orthophosphate and phosphorus turnover in irradiated and nonirradiated cells was made.
Under the conditions tested, no difference in the amounts of DNA and RNA could be detected between the irradiated and nonirradiated cells immedi. ately after irradiation and during post-irradiation incubation. P32 was somewhatmore rapidly incorporated into the cellular fractions, including DNA and RNA fractions, of ultraviolet-irradiated cells than into those which were not irradiated.
When P32-labeled cells, nonirradiated and irradiated, were placed in a nonradioactive phosphate solution, the 1-hour- and 3-hour-labeled nonirradiated cells showed a decrease in radioactivity from P32 in the protein fraction. This suggests the existence of a labile phosphorus compound, showing an active phosphorus turnover. The ultraviolet-irradiated cells did not contain such labile compound in the protein fraction, and, , in addition, they showed an increase in radioactivity from P32. It appears that some abnormal phosphorus metabolism is related to protein synthesis in the ultraviolet-irradiated cells.
