Changes in Activities of Related Enzymes in Early Developmental Stages of Sepia esculenta

Abstract:

Chemical and biological methods were employed to determine specific activities of several enzymes including trypsin, pepsin, alkaline phosphatase (AKP), lipase, and alanine aminotransferase (ALT) at different stages of fertilized eggs and 0–10 days old larvae of golden cuttlefish Sepia esculenta. The results showed that the soluble protein content was elevated in the early embryonic and larval stages, but was depressed from the mid to late embryonic stages. The protein content was the highest in the blastula and gastrulae stage(Ⅱ) (81.50 mg/g), and the lowest in the newly-hatched larvae (Ⅶ) (4.24 mg/g). During the development, the specific activities of trypsin, pepsin, and ALT in five enzymes all followed the up-down-up pattern. Activities of all three enzymes were detectable but very low in embryonic developmental stages, suggesting their maternal originality. Moreover, the enzymatic activities were significantly increased in newly-hatched larvae, which were 0.51 U/g, 1.68 U/mg and 37.84 U/g respectively. The enzymatic activities in 5 days old larvae (Ⅷ) dropped significantly compared to the level before hatching, and rose slowly in 10 days old larvae (Ⅸ). The activities of both AKP and lipase were generally elevated, starting from very low during the embryonic stages to significantly higher after hatching. These results implied the gradual maturation of organs and the improvement of digestion capability.