Ribonuclease-sensitive DNA-synthesizing complex in human sperm heads and seminal fluid

An endogenous DNA-synthesizing complex sensitive to ribonuclease has been found in purified preparations of swollen human sperm heads. Incorporation of [3H]dTTP into acid-precipitable material occurred in the presence of actinomycin D and required addition of dGTP, dCTP, dATP, plus Mg++. Polymerization was sensitive to pretreatment of the complex with pancreatic RNase A or Triton X-100. Exogenous activity was elicited by the synthetic template (dT)12--18-(rA)n but not by (dT)12--18-(dA)n or (dT)10. The complex sedimented from a 10,000 X g supernatant by centrifugation at 165,000 X g for 60 min and banded in sucrose at a density of 1.21--1.25 g/cm3. Endogenous RNase-sensitive DNA polymerase activity from cell-free seminal fluid was also detected in a fraction in sucrose at a density of 1.22 g/cm3. This activity was labile to freezing and stimulated by 0.04% Triton X-100, and thus differed from that of sperm heads.