the development of digestive ability in larvae of
haddock (melanogrammus aeglefinus)
J.C.
Perez Casanova, H.M. Murray, N.W. Ross, S. Douglas, S.C. Johnson
Abstract:
Two
problems faced in the culture of non-salmonid fish such as haddock are high
mortality during the larval stages, possibly due to feeding problems such as
poor nutrition, and the high costs associated with feeding live feeds. The
development of a nutritionally complete formulated diet for larvae would
help solve these problems. Information on the digestive capabilities of
larvae is important for the development of such diets. In our laboratory, we
are examining the production of digestive enzymes in haddock larvae from
hatch through 45 days post-hatch. Using biochemical techniques trypsin,
pepsin, total protease, α-amylase, esterase and alkaline phosphatase
activities are being determined in whole body extracts. At eight days post
hatch of all these enzymes are present at measurable levels. With exception
of total protease activity all enzyme activities increased with larval age.
We are in the process of using labelled anti-sense RNA probes to confirm the
timing and location of digestive enzyme gene expression. To date we have
localized trypsin activity in pancreatic tissue at 10 days post-hatch.
Expression of pepsin genes has been seen as early as 25 days post-hatch.
(Department
of Biology, Dalhousie University, Halifax, N.S. Canada, B3H 4J1)