Release of DNA template restrictions in rabbit spermatozoa and rat liver nuclei

The effects of disulfide reduction on DNA template activity of rabbit sperm and rat liver nuclei are compared. After treatment of rabbit spermatozoa with 5 mM dithiothreitol and 1% Triton X-100 for 90 minutes at room temperature, sperm nuclei decondense and nuclear template restrictions for DNA synthesis are released. By contrast, similar thiol treatment of isolated rat liver nuclei fails to release DNA template restrictions. These results suggest a significant difference in the control of template activity in mammalian sperm and somatic cell nuclei.