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|Docosahexaenoic acid biosynthesis via fatty acyl elongase and Δ4-desaturase and its modulation by dietary lipid level and fatty acid composition in a marine vertebrate
Tocher, Douglas R
polyunsaturated fatty acid synthesis
desaturation and elongation activity
dietary lipid level
fatty acid composition
|Morais S, Mourente G, Martinez A, Gras N & Tocher DR (2015) Docosahexaenoic acid biosynthesis via fatty acyl elongase and Δ4-desaturase and its modulation by dietary lipid level and fatty acid composition in a marine vertebrate. Biochimica et Biophysica Acta (BBA)- Molecular and Cell Biology of Lipids, 1851 (5), pp. 588-597. https://doi.org/10.1016/j.bbalip.2015.01.014
|The present study presents the first "in vivo" evidence of enzymatic activity and nutritional regulation of a Δ4-desaturase-dependent DHA synthesis pathway in the teleost Solea senegalensis. Juvenile fish were fed diets containing 2 lipid levels (8 and 18%, LL and HL) with either 100 % fish oil (FO) or 75 % of the FO replaced by vegetable oils (VO). Fatty acyl elongation (Elovl5) and desaturation (Δ4Fad) activities were measured in isolated enterocytes and hepatocytes incubated with radiolabelled a-linolenic acid (ALA; 18:3n-3) and eicosapentaenoic acid (EPA; 20:5n-3). Tissue distributions of elovl5 and Δ4fad transcripts were also determined, and the transcriptional regulation of these genes in liver and intestine was assessed at fasting and postprandially. DHA biosynthesis from EPA occurred in both cell types, although Elovl5 and Δ4Fad activities tended to be higher in hepatocytes. In contrast, no Δ6Fad activity was detected on 14C-ALA, which was only elongated to 20:3n-3. Enzymatic activities and gene transcription were modulated by dietary lipid level (LL > HL) and fatty acid (FA) composition (VO > FO), more significantly in liver than in intestine, which was reflected in tissue FA compositions. Dietary VO induced a significant up-regulation of Δ4fad transcripts in liver 6 h after feeding, whereas in fasting conditions the effect of lipid level possibly prevailed over or interacted with FA composition in regulating the expression of elovl5 and Δ4fad, which were down-regulated in liver of fish fed the HL diets. Results indicated functionality and biological relevance of the Δ4 LC-PUFA biosynthesis pathway in S. senegalensis.
|This item has been embargoed for a period. During the embargo please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study. Accepted refereed manuscript of: Morais S, Mourente G, Martinez A, Gras N & Tocher DR (2015) Docosahexaenoic acid biosynthesis via fatty acyl elongase and Δ4-desaturase and its modulation by dietary lipid level and fatty acid composition in a marine vertebrate, Biochimica et Biophysica Acta (BBA)- Molecular and Cell Biology of Lipids, 1851 (5), pp. 588-597. DOI: 10.1016/j.bbalip.2015.01.014 © 2015, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
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