Quantitative and qualitative coding of Lactate dehydrogenase isoenzymes and their genes: Evolutionary implication in genus Channa (Channidae: Channiformes)

Lactate dehydrogenase (LDH: 3.1.1.27) is a tetrameric enzyme participates in carbohydrate metabolism by catalyzing the oxidation of lactate and reduction of pyruvate. The random tetramerization of LDH-A and -B subunits leads to the formation of five tetramers: LDHB4, LDH-A1B3, LDH-A2B2, LDH-A3B1 and LDH-A4. Due to the biochemical and evolutionary significance of LDH isoenzyme characters or LDH genes, efforts are made here to propose a numerical coding method of quantifying the isoenzyme activities and demonstrate the presence of LDH loci or the changing levels of isoenzymes in different tissues of selected airbreathing teleosts Channa punctata, C. gachua and C. striatus. Polyacrylamide gel electrophoretic (PAGE) profiles of LDH isoenzymes were utilized and software analysis of gel scans was performed. Our results show a great variation in the quantitative as well as qualitative presence of isoenzymes or their genes among the selected freshwater congeneric species. Based on the obtained results, adaptive strategies of Channa species are discussed in relation to their evolutionary set up.