INDUCED MUTATIONS AT THE Vby LOCUS OF TRIFOLIUM REPENS. II. REDUCTION BELOW THE ADDITIVE BASE LINE BY FRACTIONATED DOSES OF GAMMA RADIATION
Dose-fractionation was shown to have a pronounced effect on the number of mutations produced but none on leaf production. Dose fractionation led to a reduction in the number of mutations recovered tc a value below the expected base line of the additive effects of the two fractions. The development of the protective effect was dependent on time, being at a maximum at 2 to 8 hours at 25 deg C; on temperature, taking longer to develop at 8 deg C than at 25 deg C; and on dose, being greater at higher doses. With high temperatures the effect diminished after long intervals, but persisted at lower temperatures. Doses as low as 12.5 rads induced protection, and the phenomenon developed within a very short period post-irradiation. Protection occurred only if the initial fraction was given in the presence of oxygen. The protective effect observed could be attributed tc mitotic delay and the presence of a sensitive stage in interphase for the induction of some point mutations. Attempts were made to correlate the observations with the known effects of radiation on DNA synthesis. (auth)
- Research Organization:
- Wantage Research Lab., Berks, Eng.
- NSA Number:
- NSA-15-027433
- OSTI ID:
- 4843754
- Journal Information:
- Genetics (U.S.), Vol. Vol: 46; Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
Induction of forward mutation at the yg2 locus in maize by ethylnitrosourea
EFFECT OF TOTAL-BODY X-RADIATION FROM NEAR THRESHOLD TO TISSUE-LETHAL DOSES ON THE SMALL BOWEL EPITHELIUM OF THE RAT. I. CHANGES IN MORPHOLOGY AND RATE OF CELL DIVISION IN RELATION TO TIME AND DOSE