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The influence of environment on radiation-induced mutations affecting growth

Journal Article · · Hereditas
The effect of different environmental conditions on the expression of a random sample of x-ray induced mutations affecting a quantitative character was examined using rate of cell division in a homozygous diploid strain of yeast. Contrasting environments were provided by media that differed greatly in their composition; one was fortified with peptone and yeast extract, the other was minimal and contained only chemically defined substances and only those necessary to support growth. A homothallic strain of Saccharomyces cerevisiae var. ellipsoideus was x irradiated with a dose of 8000 r, given at a dose rate of 574 r/min. Modal growth values were unaffected by x irradiation, but the mean growth value was reduced significantly in both environments. Negative mutations (decreased rates of cell division) were detected in each instance. It was found that a superior environment frequently masks the harmful effects of radioinduced mutations. Despite the general tendency toward a protective effect of a better environment, direct evidence of the converse was found in some instances; the detrimental effects of some mutations were more pronounced in a good than in a poor environment. This suggests that a selection program performed in a superior environment may easily lead to the fixing of genotypes that will be inferior under less optimal conditions.
Research Organization:
Atomic Energy of Canada Ltd., Chalk River, Ont.
Sponsoring Organization:
USDOE
NSA Number:
NSA-17-017842
OSTI ID:
4716442
Journal Information:
Hereditas, Journal Name: Hereditas Journal Issue: 1-2 Vol. 48; ISSN 0018-0661
Country of Publication:
Country unknown/Code not available
Language:
English

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