Gene expression and activity of digestive enzymes during the larval development of Asian seabass (Lates calcarifer).

Knowledge of digestive enzyme development during larval stages provides a better understanding of the digestive and nutritional physiology of fish larvae. This study characterized the ontogeny of key digestive enzymes in Asian seabass larvae from hatching to juvenile stage (30 days post hatch, dph) using molecular and biochemical approaches. Gene expression and activity of pepsinogen (pg), trypsinogen (try), chymotrypsinogen (ctr), bile salt-activated lipase (bal), α-amylase (amy), leucine aminopeptidase (lap) and alkaline phosphatase (alp) were determined. Gene expression and enzyme activity of all digestive enzymes were detectable from hatching. Pepsinogen mRNA levels were close to detection limit during 0-15 dph, but were highly expressed from 18 dph and onwards. This coincided with a marked increase in specific and individual pepsin activity, indicating complete development of digestive function. Expression levels of try, ctr, amy and bal were high between 3 and 15 dph and thereafter a decreasing trend was observed. Intestinal enzymes, lap and alp, showed highest expression levels during the yolk sac stage, and thereafter levels decreased. Activity of all digestive enzymes increased from around 18 dph and onwards. In conclusion, the development of main digestive enzymes in Asian seabass larvae shows a similar pattern to that of other marine fish species.