[Gene regulation of the lactate dehydrogenase isoenzyme spectrum in the mouse liver]

The isozyme pattern of lactate dehydrogenase (LDH) was studied by means of electrophoretic and immunochemical methods in liver of inbred mouse strains: CBA/Lac, DBA/1J, DBA/2J, AKR/J, C57BL/6J, C3H/He. Interstrain polymorphism for the activity of LDH isozymes in mouse liver is found to take place, which is due to the presence of the regulatory gene Ldr-2. Based on the breeding data of DBA/2J and CBA/Lac mice, which show different liver LDH patterns, and judging by the results of the immunochemical analysis, it is suggested that the low activity of LDH isozymes containing subunit B and controlled by the gene Ldr-2 is inherited codominantly. It is found that the effect of the gene Ldr-2 is independent on that of the gene Ldr-1, which modifies the phenotypic expression of the gene B of erythrocyte LDH in mice. The gene Ldr-2 is in the same linkage group as the gene Ldr-1, at a distance of 19.6 map units from it. The data of immunochemical analysis suggest that the effect of the gene Ldr-2a is related with the decreased content of the subunit B, and possibly of the subunit A of LDH. The study of LDH pattern throughout mouse development has demonstrated, that the differences in liver KDH patterns between CBA/Lac and DBA/2J mice, controlled by the gene Ldr-2, express phenotypically on 6-8 dyas and are finally formed in the middle of the first month of the life.