Effect of Urethane and Colchicine on Radiation-induced Chromosome Loss in MaleDrosophila

Abstract

Urethane or colchicine was injected, either before or immediately after 2000 r of x-rays, into male Drosophila melanogaster. Urethane modified the radiationinduced loss of the ring X or Y sc 8 y+ chromosome, as determined by the number of XO male offspring. Urethane alone increased the loss of the ring X chromosome primarily in the mature spermatozoa and older spermatids, whereas x-rays induced chromosome loss to a greater extent in those cells in or about meiosis. Pre-treatment or post-treatment with colchicine by means of injection near the testis gave an apparent protection against radiation-induced chromosome loss; but colchicine alone induced sterility by reducing the number of gametes available to form zygotes by affecting those cells in spermatogenesis that were in or about meiosis at the time of treatment.