Dietary fatty acid composition changes mitochondrial phospholipids and oxidative capacities in rainbow trout red muscle |
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Authors: | H Guderley E Kraffe W Bureau D P Bureau |
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Institution: | (1) Département de Biologie, Université Laval, G1K 7P4 Quebec, QC, Canada;(2) UG/OMNR Fish Nutrition Research Laboratory, Department of Animal and Poultry Science, University of Guelph, N1G 2W1 Guelph, ON, Canada;(3) Unité mixte CNRS 6521, Université de Bretagne Occidentale, C.S. 93837, 29238 Brest cedex 3, France |
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Abstract: | Dietary conditioning of juvenile trout changed the acyl chain composition of mitochondrial phospholipids and the oxidative
capacities of muscle mitochondria. Trout were fed three diets differing only in fatty acid (FA) composition. The highly unsaturated
22:6 n-3 (DHA) accounted for 0.4, 14, and 30% of fatty acids in Diets 1, 2 and 3. After 10 weeks of growth, the dietary groups
differed markedly in FA composition of mitochondrial phospholipids, with significant dietary effects for virtually all FA.
Mean mitochondrial DHA levels were 19, 40 and 33% in trout fed Diets 1, 2 and 3. Mitochondrial oxidative capacities changed
with diet, while mitochondrial concentrations of cytochromes and of the adenylate nucleotide translocase (nmol mg1 protein) did not. Mitochondria from fish fed Diet 1 had higher non-phosphorylating (state 4) rates at 5°C than those fed
other diets. When phosphorylating (state 3) rates differed between dietary groups, rates at 5 and 15°C were higher for fish
fed the more unsaturated diets. Stepwise multiple regressions indicated that FA composition could explain much (42–70%) of
the variability of state 4 rates, particularly at 5°C. At 15°C, FA composition explained 16–42% of the variability of states
3 and 4 rates. Similar conclusions were obtained for the complete data set (trout fed diets 1, 2 and 3) and for the data from
trout achieving similar growth rates (e.g. those fed Diets 1 and 2). Neither general characteristics of membrane FA, such
as % saturates, unsaturation index, n-3, n-6 or n-3/n-6 nor levels of abundant unsaturated FA such as DHA or 18:1(n-9 + n-7),
were systematically correlated with mitochondrial capacities even though they differed considerably between trout fed the
different diets. Relatively minor FA (20:5n-3, 20:0, 18:2n-6, 18:3n-3, 18:0 and 15:0) showed better correlations with mitochondrial
oxidative capacities. This supports the concept that acyl chain composition modulates mitochondrial capacities via interactions
between membrane proteins and specific FA of particular phospholipid classes in their microenvironment. |
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Keywords: | Membrane pacemaker DHA EPA Oxidative phosphorylation n-3 n-6 |
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