CYTOLOOICAL EFFECT OF CHRONIC GAMMA IRRADIATION 



acidity alter the radio-sensitivity of the cell. It seems justifiable, however, 

 in this case to put the main emphasis on the oxidation of cysteine to cystine. 

 Although the protective actions of these chemicals are not understood, 

 indications of an indirect effect of radiation on chromosome fragmentation 

 are demonstrated. This indirect effect seems to be of great importance in 

 the production of chromosome breaks, since it is possible to reduce the 

 radiation damage to about half in most of the cases. Unfortunately, how- 

 ever, it will be difficult to determine the exact relation between direct and 

 indirect radiation effect by chemical means, because of their toxic effects on 

 roots at certain concentrations. 



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