February 15-18, 2009 Washington State Convention Center Seattle ...

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HEAT SHOCK PROTEIN REGULATION IN RAINBOW TROUT Oncorhynchus mykiss IS
ALTERED BY DIETARY SOYBEAN MEAL INCLUSION AND ANTI-PHOSPHOLIPASE A 2
ANTIBODY
Wendy M. Sealey * , Frederic T. Barrows, Charlie E. Smith, Jurij M. Wacyk, Brian C. Donahower,
Madison S. Powell, Ronald W. Hardy and Eric A. Shelden
Hagerman Fish Culture Experiment Station
University of Idaho
3059F National Fish Hatchery Road
Hagerman, ID 83332 USA
wsealey@uidaho.edu
Heat shock proteins (HSPs) are considered to be a cell survival factor and have been shown to improve cell function in multiple
models of cell injury including soybean meal-induced enteritis in salmonids. Recently, phospholipase A 2 , an enzyme that catalyzes
the hydrolysis of fatty acids to generate arachidonic acid, was shown to regulate HSPs. Thus alteration of phospholipase
A 2 activity may provide an opportunity to alter heat shock protein expression and reduce soybean meal-induced enteritis in
rainbow trout. Therefore, the aim of this study was to examine the effect of a commercially available anti-phospholipase A 2
supplement (Big Fish) on performance of rainbow trout fed high levels of soybean meal (SBM).
Rainbow trout were fed a practical-type control diet formulated to contain 45% protein and 15% fat with 0, 17.5 or 35% SBM
with and without the commercially available Big Fish (Aova Technology) supplement at an inclusion level of 0.3%. Diets were
fed to three replicate tanks of fish per treatment (20 fish/tank, House Creek strain) for 9 weeks. Trout were reared in 80 L tanks
supplied with 4 L/min of 14.8°C flow-through spring water. Following the trial, fish (n=3) were randomly selected from each
tank for whole body proximate analyses and fish performance indices. Total RNA was isolated from liver and intestinal tissues
(n=3) to detect alterations in HSP27, HSP70 and HSP90 gene expression by real time quantitative PCR; protein expression
was examined by Western blot. Histopathological examination was performed on the kidney, liver and distal intestine of three
randomly selected fish from each tank.
Decreased growth was observed for fish fed 35% SBM regardless of Big Fish supplementation. Fish fed 35% SBM had significantly
higher feed conversion ratios than fish fed 0 or 17.5% SBM. HSP27 and HSP90 mRNA expression was elevated in
fish fed 35% SBM. A significant interaction was observed for HSP90 mRNA expression in that fish fed 35% SBM with Big
Fish had lower HSP90 mRNA expression that fish without supplement. Histology of the distal intestine revealed significant
pathology in fish fed 35% SBM diets (with and without Big Fish). These data indicate feeding high levels of SBM alters the
expression and regulation of various HSP mRNA of rainbow trout in a HSP specific manner. Additionally, dietary inclusion of
Big Fish had only minimal effects on the pathology associated with high levels of SBM in rainbow trout.