Genetic differences of DNA and RNA synthesis in the epithelium of the lens of the chick

Abstract

SUMMARYThe genetically unrelated chick strains Hy-1 and Hy-2, which have been strongly selected for growth rate, both exhibit hyperplasia of the lens epithelium. These two strains and a control strain N, not selected for growth rate, were compared with respect to incorporation of3H-thymidine and14C-uridine by freshly excised lenses in culture at different times throughout a 24-h period. The levels of incorporation of label into the lens cells were found to vary according to the time of day. The pattern of diurnal variation in both thymidine and uridine incorporation was found to be strain specific. Hy-1 and Hy-2 showed a greater degree of synchrony than did normal (N) lenses, and the frequency of the peaks of incorporation was also higher. Autoradiography confirmed that only lens epithelium incorporates thymidine during culture and that the number of labelled nuclei depends on the time of day when the lenses were explanted. These data point to genetic control of the cell cycle.