Relationship between Cell Cycle Stage in the Fertilized Egg of Mice and Repair Capacity for X-ray-induced Damage in the Sperm

Summary

The potentiation effects of 3-aminobenzamide, caffeine, hydroxyurea and arabinofuranosyl cytosine on the yield of X-ray-induced chromosome aberrations of mouse sperm were examined at the first-cleavage metaphase, to clarify a correlation between chromosome aberrations and cell cycle dependency of repair capacity of the fertilized egg. The result provided evidence that there are two major types of DNA damage in X-irradiated sperm: (1) short-lived DNA lesions; the lesions are subject to repair inhibition by agents added in G₁ and are converted into chromosome-type aberrations during G₁, and (2) long-lived DNA lesions; the lesions persist until S phase and repair of the lesions is inhibited by caffeine, hydroxyurea and arabinofuranosyl cytosine in G₂.