Comparison of the spatial and temporal expression of supernatant malate dehydrogenase in Barbus hybrids (Cypriniformes, Teleostei).

The tissue specificity and ontogeny of supernatant malate dehydrogenase (s-MDH) are reported for the tiger barb, cherry barb, and their reciprocal hybrids. The tissue distribution of s-MDH isozymes in Barbus is consistent with the patterns reported in other teleosts. The expression of the Mdh-B locus is correlated with the initial muscle contractions of the developing embryos. It is suggested that the state of muscle cell differentiation may be the stimulus necessary for the expression of this locus in Barbus. Expression of maternal and paternal alleles at the B locus are synchronously delayed in reciprocal hybrids, as compared to their expression intraspecifically.