mRNA expression of pancreatic enzyme precursors and estimation of protein digestibility in first feeding larvae of the Japanese flounder, Paralichthys olivaceus.
An understanding of digestibility in marine fish larvae is required to formulate a diet to replace zooplankton. Using flounder, this study was aimed at determining which digestive enzymes are synthesized in the larval pancreas, and how the proteins are cleaved in the digestive canal. Whole mount in situ hybridization indicated that the mRNA of all digestive enzyme precursors examined, including trypsin, chymotrypsin, elastase, carboxypeptidase A and B, and lipase, was expressed in the pancreas of first feeding larvae at 3 days post-fertilization. In the larvae before differentiation of the stomach, protein digestion in the digestive canal mainly depends on pancreatic proteases. So, to evaluate protein digestibility in the larval digestive canal, the digestion of proteins by pancreatic extract was monitored by gel electrophoresis. It was indicated that thyroglobulin, albumin and lactate dehydrogenase were rapidly cleaved to polypeptide fragments, but ferritin and catalase exerted resistance to proteolysis, suggesting that digestibility in the larval digestive canal differs depending on protein species.
Srivastava
Anand S
AS
Metabolism Section, National Research Institute of Aquaculture, Fisheries Research Agency, Nansei, Mie 516-0193, Japan.
Kurokawa
Tadahide
T
Suzuki
Tohru
T
D000818:Animals; D004032:Diet; D004063:Digestion; D004792:Enzyme Precursors / Q000235:genetics* / Q000378:metabolism*; D005432:Flounder / Q000235:genetics* / Q000254:growth & development*; D015971:Gene Expression Regulation, Enzymologic; D017403:In Situ Hybridization; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007814:Larva / Q000201:enzymology*; D010179:Pancreas / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D004792:Enzyme Precursors; D007527:Isoenzymes; D012333:RNA, Messenger; D010196:Pancreatic Elastase