Persistence of maternal isoenzyme patterns of the lactate dehydrogenase and phosphoglucomutase system during early development of hybrid trout

Developmental changes in the isoenzyme patterns of LDH and PGM during early embryogenesis (until hatching) in two trout species (Salmo trutta and Salmo irideus) as well as in their reciprocal interspecific hybrids are reported, completing a previous study which had commenced from hatching onward (Hitzeroth et al., 1968). Isoenzymes of both systems occur in unfertilized eggs and in embryos from fertilization onward. Until about the Augenpunkt stage, the isoenzyme patterns remain unchanged and are identical to the patterns of unfertilized eggs; the reciprocal hybrids correspond to the respective maternal species. Additional isoenzymes appearing for the first time at about the Augenpunkt stage in the interspecific hybrids show the same electrophoretic mobility as those in the animals of the respective maternal species at this developmental stage. It is discussed whether the appearance of additional isoenzymes characterizes the activation of maternally derived alleles of the embryonic genome, or whether maternally derived cytoplasmic factors are responsible for the occurrence of these additional bands.Supported by the Deutsche Forschungsgemeinschaft.