In situ detection of a DNA-polymerase activity in the nuclei of mouse spermatozoa

A nuclear DNA-polymerase activity has been detected in situ in mouse spermatozoa with a cytochemical method. The acid-insoluble radioactive product obtained after incubation in a mixture containing all four deoxyribonucleoside 5'-triphosphates, Mg++,KCl and dithiothreitol (DTT) was completely removed by DNAse but was insensitive to RNAse and pronase action. The polymerization reaction did not take place in the presence of only one nucleotide and was dramatically reduced when actinomycin D was present; it did not seem to be inhibited markedly by N-ethylmaleimide (NEM) or by parahydroxymercuribenzoate (PHMB) but was sensitive to high concentrations of KCl.--The reaction depended strictly on the presence of nuclear DNA as template since treatment with pancreatic DNAae before the DNA-polymerase assay completely prevented the appearance of any radioactivity.