Modification of X-ray sensitivity by metal ions in Crotalaria intermedia seeds

Abstract

The effect of metal ions, present during irradiation, on sensitivity to X-irradiation of dry Crotalaria intermedia seeds was investigated. Seeds soaked for 10 hr in 0·01 M ZnSO₄, CuSO₄, MnSO₄ and MgSO₄ were dried back and equilibrated for moisture content at relative humidities of 5 and 32 per cent, in air or in nitrogen prior to X-irradiation in the same atmosphere. The number of mutated sectors appearing on the first leaf was used as a measure of radiation effect. The results indicate that the presence of cupric ions during X-irradiation enhance the effect. Other metal ions did not show any significant modification of radiation effect. It is suggested that the observed sensitization by cupric ions may be due to binding of the metal ions with DNA and other macromolecules thus rendering them more vulnerable to damage by radicals produced.