National Research Council of Canada. NRC Institute for Marine Biosciences
National Research Council of Canada. Human Health Therapeutics
The fish larval stage is a critical step since only those specimens that survive will reach the adult stage in future. Knowledge related to fish larval nutritional requirements and digestive enzymes capacity is still scarce, although necessary to obtain satisfactory survival and growth rates. Trypsinogen is the precursor of trypsin, the main proteolytic enzyme acting during the early larval stage. Bile salt-activated lipase (BAL) is a multi-substrate digestive enzyme that hydrolyzes carboxyl ester bonds of acylglycerols, cholesterol esters and fat-soluble vitamin esters. The goal of this study was to determine the pattern of trypsinogen and BAL expression during larval development in red porgy (Pagrus pagrus, Pisces, Sparidae), reared under standard conditions to provide the basis for future experiments testing the possible transcriptional regulation for this enzyme under different nutritional conditions. Thus, partial cDNAs for trypsinogen and BAL from red porgy were isolated. The putative aminoacid sequences obtained for both precursors showed around 80% identity to other fish sequences from GenBank database. Trypsinogen and BAL were expressed from hatching and specifically located in the exocrine pancreas, revealed by in situ hybridization. The present study shows that this species is being prepared for protein and lipid digestion before exogenous feeding starts, exhibiting an ontogenetically programmed pattern for trypsinogen and BAL expression during the yolk-sac stage.