In vivo germinal mutation detection with "monospecific" antibody against lactate dehydrogenase-X.

This report describes developments toward a cell specific-locus test for measuring point mutations directly in sperm based upon the use of a monospecific antibody against sperm-specific lactate dehydrogenase-X (LDH-X). The antibody recognizes amino acid differences between mouse and rat LDH-X molecules. In general, mouse sperm do not bind the monospecific antibody against rat LDH-X, but a few exceptional mouse sperm do. Such mouse sperm are believed to contain LDH-X molecules in which an amino acid normally present in mouse LDH-X has been exchanged with one present in rat LDH-X at a place where rat and mouse enzymes are antigenically different. Thus, in the fluorescent antibody technique, mouse sperm carrying normal LDH-X do not stain but the sperm containing mutated enzyme do stain. By using this technique, the spontaneous presumptive mutation frequency in DBA/2 mice was found to be 0.43 X 10(-6); it increased to 7.6 X 10(-6) upon procarbazine treatment of the mice.