Development of digestive enzymes in larvae of Mayan cichlid Cichlasoma urophthalmus

Abstract

The development of digestive enzymes during the early ontogeny of the Mayan cichlid (Cichlasoma urophthalmus) was studied using biochemical and electrophoretic techniques. From yolk absorption (6days after hatching: dah), larvae were fed Artemia nauplii until 15dah, afterward they were fed with commercial microparticulated trout food (45% protein and 16% lipids) from 16 to 60dah. Several samples were collected including yolk-sac larvae (considered as day 1 after hatching) and specimens up to 60dah. Most digestive enzymes were present from yolk absorption (5-6dah), except for the specific acid proteases activity (pepsin-like), which increase rapidly from 8dah up to 20dah. Three alkaline proteases isoforms (24.0, 24.8, 84.5kDa) were detected at 8dah using SDS-PAGE zymogram, corresponding to trypsin, chymotrypsin and probably leucine aminopeptidase enzymes, and only one isoform was detected (relative electromobility, Rf=0.54) for acid proteases (pepsin-like) from 3dah onwards using PAGE zymogram. We concluded that C. urophthamus is a precocious fish with a great capacity to digest all kinds of food items, including artificial diets provided from 13dah.