Isolation and characterization of germ line DNA from mouse sperm

Mouse germ line DNA was isolated from sperm by a physicochemical procedure that preferentially destroys contaminating somatic cell DNA. The use of reducing conditions and chelating agents in combination with phenol permitted extraction of molecular weight DNA from mature sperm nuclei with approximately 80% efficiency. Less than 0.1% somatic cell DNA contamination remained in sperm DNA prepared by this method. Germ line DNA was characterized by determination of its ultraviolet absorbance spectrum, buoyant density in cesium chloride, and melting profile on a hydroxyapatite column. Contamination by mitochondrial DNA was assessed by cesium chloride/ethidium bromide gradient centrifugation. The significance of the mouse germ line DNA isolation procedure is discussed with respect to the possible genetic transmission of mammary tumor virus and leukemia virus, the origin of antibody diversity, and the origin of testicular teratomas.