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Multiple genes for functional 6 fatty acyl desaturases (Fad) in Atlantic salmon (Salmo salar L.): gene and cDNA characterization, functional expression, tissue distribution and nutritional regulation.
Biochim Biophys Acta 2010; 1801(9):1072-81BB

Abstract

Fish are the primary source in the human food basket of the n-3 long-chain polyunsaturated fatty acids, eicosapentaenoate (EPA; 20:5n-3) and docosahexaenoate (DHA; 22:6n-3), that are crucial to the health of higher vertebrates. Atlantic salmon are able to synthesize EPA and DHA from 18:3n-3 through reactions catalyzed by fatty acyl desaturases (Fad) and elongases of very long chain fatty acids. Previously, two cDNAs encoding functionally distinct Delta5 and Delta6 Fads were isolated, but screening of a genomic DNA library revealed the existence of more putative fad genes in the Atlantic salmon genome. In the present study, we show that there are at least four genes encoding putative Fad proteins in Atlantic salmon. Two genes, Delta6fad_a and Delta5fad, corresponded to the previously cloned Delta6 and Delta5 Fad cDNAs. Functional characterization by heterologous expression in yeast showed that the cDNAs for both the two further putative fad genes, Delta6fad_b and Delta6fad_c, had only Delta6 activity, converting 47 % and 12 % of 18:3n-3 to 18:4n-3, and 25 and 7 % of 18:2n-6 to 18:3n-6, for 6Fad_b and Delta6fad_c, respectively. Both 6fad_a and 6fad_b genes were highly expressed in intestine (pyloric caeca), liver and brain, with 6fad_b also highly expressed in gill, whereas 6fad_c transcript was found predominantly in brain, with lower expression levels in all other tissues. The expression levels of the 6fad_a gene in liver and the 6fad_b gene in intestine were significantly higher in fish fed diets containing vegetable oil compared to fish fed fish oil suggesting up-regulation in response to reduced dietary EPA and DHA. In contrast, no significant differences were found between transcript levels for 6fad_a in intestine, 6fad_b in liver, or 6fad_c in liver or intestine of fish fed vegetable oil compared to fish fed fish oil. The observed differences in tissue expression and nutritional regulation of the fad genes are discussed in relation to gene structures and fish physiology.

Authors+Show Affiliations

Institute of Aquaculture, University of Stirling, Stirling FK94LA, Scotland, UK. oscar.monroig@stir.ac.ukNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

20403458

Citation

Monroig, Oscar, et al. "Multiple Genes for Functional 6 Fatty Acyl Desaturases (Fad) in Atlantic Salmon (Salmo Salar L.): Gene and cDNA Characterization, Functional Expression, Tissue Distribution and Nutritional Regulation." Biochimica Et Biophysica Acta, vol. 1801, no. 9, 2010, pp. 1072-81.
Monroig O, Zheng X, Morais S, et al. Multiple genes for functional 6 fatty acyl desaturases (Fad) in Atlantic salmon (Salmo salar L.): gene and cDNA characterization, functional expression, tissue distribution and nutritional regulation. Biochim Biophys Acta. 2010;1801(9):1072-81.
Monroig, O., Zheng, X., Morais, S., Leaver, M. J., Taggart, J. B., & Tocher, D. R. (2010). Multiple genes for functional 6 fatty acyl desaturases (Fad) in Atlantic salmon (Salmo salar L.): gene and cDNA characterization, functional expression, tissue distribution and nutritional regulation. Biochimica Et Biophysica Acta, 1801(9), pp. 1072-81. doi:10.1016/j.bbalip.2010.04.007.
Monroig O, et al. Multiple Genes for Functional 6 Fatty Acyl Desaturases (Fad) in Atlantic Salmon (Salmo Salar L.): Gene and cDNA Characterization, Functional Expression, Tissue Distribution and Nutritional Regulation. Biochim Biophys Acta. 2010;1801(9):1072-81. PubMed PMID: 20403458.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Multiple genes for functional 6 fatty acyl desaturases (Fad) in Atlantic salmon (Salmo salar L.): gene and cDNA characterization, functional expression, tissue distribution and nutritional regulation. AU - Monroig,Oscar, AU - Zheng,Xiaozhong, AU - Morais,Sofia, AU - Leaver,Michael J, AU - Taggart,John B, AU - Tocher,Douglas R, Y1 - 2010/04/18/ PY - 2010/01/23/received PY - 2010/03/25/revised PY - 2010/04/07/accepted PY - 2010/4/21/entrez PY - 2010/4/21/pubmed PY - 2010/10/19/medline SP - 1072 EP - 81 JF - Biochimica et biophysica acta JO - Biochim. Biophys. Acta VL - 1801 IS - 9 N2 - Fish are the primary source in the human food basket of the n-3 long-chain polyunsaturated fatty acids, eicosapentaenoate (EPA; 20:5n-3) and docosahexaenoate (DHA; 22:6n-3), that are crucial to the health of higher vertebrates. Atlantic salmon are able to synthesize EPA and DHA from 18:3n-3 through reactions catalyzed by fatty acyl desaturases (Fad) and elongases of very long chain fatty acids. Previously, two cDNAs encoding functionally distinct Delta5 and Delta6 Fads were isolated, but screening of a genomic DNA library revealed the existence of more putative fad genes in the Atlantic salmon genome. In the present study, we show that there are at least four genes encoding putative Fad proteins in Atlantic salmon. Two genes, Delta6fad_a and Delta5fad, corresponded to the previously cloned Delta6 and Delta5 Fad cDNAs. Functional characterization by heterologous expression in yeast showed that the cDNAs for both the two further putative fad genes, Delta6fad_b and Delta6fad_c, had only Delta6 activity, converting 47 % and 12 % of 18:3n-3 to 18:4n-3, and 25 and 7 % of 18:2n-6 to 18:3n-6, for 6Fad_b and Delta6fad_c, respectively. Both 6fad_a and 6fad_b genes were highly expressed in intestine (pyloric caeca), liver and brain, with 6fad_b also highly expressed in gill, whereas 6fad_c transcript was found predominantly in brain, with lower expression levels in all other tissues. The expression levels of the 6fad_a gene in liver and the 6fad_b gene in intestine were significantly higher in fish fed diets containing vegetable oil compared to fish fed fish oil suggesting up-regulation in response to reduced dietary EPA and DHA. In contrast, no significant differences were found between transcript levels for 6fad_a in intestine, 6fad_b in liver, or 6fad_c in liver or intestine of fish fed vegetable oil compared to fish fed fish oil. The observed differences in tissue expression and nutritional regulation of the fad genes are discussed in relation to gene structures and fish physiology. SN - 0006-3002 UR - https://www.unboundmedicine.com/medline/citation/20403458/Multiple_genes_for_functional_6_fatty_acyl_desaturases__Fad__in_Atlantic_salmon__Salmo_salar_L__:_gene_and_cDNA_characterization_functional_expression_tissue_distribution_and_nutritional_regulation_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1388-1981(10)00086-7 DB - PRIME DP - Unbound Medicine ER -