Evolutionary evidence for a regulator gene controlling the lactate dehydrogenase B gene in rodent erythrocytes

Erythrocyte and tissue lactate dehydrogenase (LDH) electrophoretic patterns of 26 rodent species from ten families were examined. The LDH B gene was observed to range in erythrocyte expression from species without detectable B subunits to those which predominantly expressed B subunits. However, the shift in erythrocyte B gene expression was not observed in the tissue LDH electrophoretic patterns between rodent species. Species which did not express erythrocyte B subunits, or only small quantities of B subunits, were restricted to the suborder Myomorpha. In erythrocytes of other rodent species, and most mammals, LDH B subunits are expressed equally or in excess of A subunits. The results suggest either structural differences in the LDH B gene between Myomorph and non-Myomorph rodents or a regulator gene which controls the expression of the B gene in Myomorph erythrocytes. Existing evidence favors the latter hypothesis.Supported by U.S. Public Health Service Grants 5F2 HD-35,531 (T.B.S.), GM-09966 (F.H.R.), G.R.S. 5 SO1 FR-05400-07, and NSF GB 5440X (E.J.M.).