Expression of
pancreatic enzyme genes during the early larval stage of Japanese eel Anguilla
japonica
T. Kurokawa, T. Suzuki, H. Ohta, H.
Kagawa, H. Tanaka, T. Unuma-2002
Fisheries
Science,
68(4): 736-744
Abstract:
To reveal the ontogeny of pancreatic
exocrine function in the early larval stage of eel, cDNAs encoding major
pancreatic enzymes, trypsinogen, amylase and lipase were identified from the
Japanese eel Anguilla japonica and their expression pattern in larvae
was analyzed. The cloned eel trypsinogen precursor consisted of 224 amino
acids and showed 82.2% identity to trypsinogen-2 of winter flounder Pleuronectes
americanus. The eel amylase precursor consisted of 512 amino acids and
showed 77% identity to winter flounder amylase. Eel pancreatic lipase was
composed of 470 amino acids and had 58.3% of identity to human pancreatic
lipase. In the eel larvae, mRNA expression of trypsinogen and amylase was
first detected at 6 days post-hatching (d.p.h.), and the expression level
increased between 7 and 8 d.p.h. In contrast, mRNA expression of lipase
was first detected at 8 d.p.h. Eel larvae start to feed actively at 8 d.p.h.
Thus, it was indicated that eel pancreas starts to synthesize digestive
enzymes at 6 d.p.h. and acquires full function by the onset of
exogenous feeding at 8 d.p.h.
(National Research Institute of Aquaculture,
Fisheries Research Agency, Nansei, Mie 516-0193, Japan, Tel:
81-599-66-1830. Fax: 81-599-66-1962. Email: kurokawa@fra.affrc.go.jp)