Effects of different dietary arachidonic acid : docosahexaenoic acid ratios on phospholipid fatty acid compositions and prostaglandin production in juvenile turbot (Scophthalmus maximus) |
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Authors: | J Gordon Bell John D Castell Douglas R Tocher Fiona M MacDonald John R Sargent |
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Institution: | (1) N.E.R.C. Unit of Aquatic Biochemistry, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, U.K.;(2) Department of Fisheries and Oceans, P.O. Box 550, 1707 Lower Water Street, Halifax, Nova Scotia, Canada, B3J 2S7 |
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Abstract: | Five purified diets containing AA (20:4n-6) at 0.02–0.78% dry weight and DHA (22:6n-3) at 0.93–0.17% dry weight were fed to duplicate groups of juvenile turbot (Scophthalmus maximus) of initial weight 0.87 g for a period of 11 weeks. The dietary DHA:AA ratio ranged from 62 to 0.2. Incorporation of AA into liver phospholipids increased with increasing dietary AA input. Phospholipids from fish fed diets containing 0.02, 0.06 and 0.11% of dry weight as AA generally contained less AA compared to fish fed fish oil while those fed diets containing 0.35 and 0.78% of dry weight as AA had higher AA levels in their phospholipids. The highest levels of AA were found in PI but the greatest percentage increase in AA incorporation was in PE and PC. Brain phospholipid fatty acid compositions were less altered by dietary treatment than those of liver but DHA content of PC and PE in brain was substantially lower in fish fed 0.93% pure DHA compared to those fed fish oil. This suggests that dietary DHA must exceed 1% of dry weight to satisfy the requirements of the developing neural system in juvenile turbot. In both tissues, (20:5n-3) concentration was inversely related to both dietary and tissue PI AA concentration. Similar dietary induced changes in AA, EPA and DHA concentrations occurred in the phospholipids of heart, gill and kidney. PGE2 and 6-ketoPGF1 were measured in homogenates of heart, brain, gill and kidney. In general, fish fed the lowest dietary AA levels had reduced levels of prostaglandins in their tissue homogenates while those fed the highest level of AA had increased prostaglandin levels, compared to fish fed fish oil. In brains, the PGE2 concentration was only significantly increased in fish fed the highest dietary AA.Abbreviations AA
arachidonic acid
- DHA
docosahexaenoic acid
- EFA
essential fatty acid
- EPA
eicosapentaenoic acid
- HPTLC
high performance thin-layer chromatography
- HUFA
highly unsaturated fatty acid
- PC
phosphatidylcholine
- PE
phosphatidylethanolamine
- PGE
prostaglandin E
- PGE
prostaglandin E
- PI
phosphatidylinositol
- PS
phosphatidylserine
- PUFA
polyunsaturated fatty acid
- TLC
thin-layer chromatography |
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Keywords: | turbot arachidonic acid docosahexaenoic acid phospholipid prostaglandin |
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