Studies on the expressions and regulations of isozymic genes in silver carp (Hypophthalmichthys molitrix) during ontogenesis

The patterns of expression and regulations in six isozymic systems (LDH, MDH, IDH, ADH, SDH and EST) were investigated in the early developmental stages (from unfertilized eggs to the stage of complete yolk absorption) as well as six differentiated adult tissues (brain, eye, heart, muscle, kidney and liver) of silver carp. Isozymes were resolved by starch or polyacrylamide gel electrophoresis and then detected by specific histochemical staining. Isozymes in adult silver carp apparently exhibit a tissue-specific expression. During the early development period, both ADH and SDH genes seem to be inactive; the other four isozyme genes are active but exhibit different patterns of expressions. It is noteworthy, however that both LDH and EST genes in embryo from two pairs of silver carp parents taken from the same locality exhibit different patterns of expressions and regulations. We argued that these differences are related to the different compositions of LDH and EST isozymes in unfertilized eggs of different female parents. Some related problems which ought to be further studied are also mentioned in the present paper.