Non-interaction of Radiation-induced Chromosome Lesions inTradescantiaMicrospores

Abstract

An x-ray response curve for chromosome exchanges in Tradescantia microspores has been obtained after a priming dose of 0.7 mev fast neutrons. The observed yield was significantly below that expected if the neutron and X-ray doses acted independently. The deficiency in yield can be quantitatively accounted for if the number of sites in the original population of cells was limited, and some of them are no longer available to the 2nd X-ray fraction because they have been utilized for exchange by the neutron priming dose. Two conclusions may be drawn from the results: Site inacti-vation does not appear to be an important consequence of irradiation by neutrons and neutrons and X-rays can act on the same exchange sites.