The fate of DNA originally existing in the zygote nucleus during achromosomal cleavage of fertilized echinoderm eggs in the presence of aphidicolin: microscopic studies with anti-DNA antibody.

In fertilized echinoderm eggs, the male and female pronuclei fuse to form the diploid nucleus even in the presence of aphidicolin, a specific inhibitor of eukaryotic DNA polymerase-alpha. The subsequent first cleavage is independent of chromosomes but dependent on spindle and amphiaster. The fate of DNA originally existing in the fused nucleus during achromosomal cleavage of fertilized sea urchin and starfish eggs induced by aphidicolin was determined using antidenatured DNA antibody. The nucleus is not formed in the divided daughter cells at the two-cell stage but the nuclear-envelope-free chromatin mass which is unassociated with mitotic apparatus remains in the center region of embryos, especially near the first cleavage furrow. These results indicate that the condensed and nonreplicated chromatin can not be associated with spindle and asters in the presence of aphidicolin.