Radiation-induced Chromosome Exchanges in Campelia zanonia (L.) H.B.K.: Distortion Hypothesis as an Alternative to a Limited Number of Sites

Abstract

It is generally assumed that radiation-induced lesions are produced in chromosomal material at random, and that chromosome exchanges arise from pairs of these lesions in spatial and temporal proximity. The places within the nucleus where these conditions are fulfilled have been termed “sites”^1,2. On the basis of the observations that in some materials exchanges of the dicentric and centric ring types are distributed between nuclei in an under-dispersed manner (“binomial”)^1–3, and that the radiation dose-response curves for these changes eventually saturate^4,5, it has been inferred that the number of such sites must be very limited.