MODIFICATION OF THE FREQUENCY OF CHROMOSOMAL REARRANGEMENTS INDUCED BY X-RAYS IN DROSOPHILA. I. USE OF NEAR INFRARED RADIATION

Abstract

TUDENTS of radiation genetics have outlined in recent years the more S general aspects of the phenomenon whereby the activating energy of ionizing radiations induces changes within the chromosome that result in its eventual breakage. From the physical standpoint, information is available concerning the sequence of phenomena that lead to the activation of groups of atoms that presumably effect such severance. Comparison of the effects of radiations producing vastly different densities of activations within small areas suggests that the process of chromosome breakage depends ordinarily on a series of "ionizations" (LEA and CATCHESIDE 1942). The amount of energy required to disrupt the chromosome may accordingly be calculated, but the sequence of molecular changes by which this end is attained remains unknown.