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Sun S, Ren T, Li X, Cao X, Gao J. Polyunsaturated fatty acids synthesized by freshwater fish: A new insight to the roles of elovl2 and elovl5 in vivo. Biochem Biophys Res Commun 2020; 532:414-419. [PMID: 32883522 DOI: 10.1016/j.bbrc.2020.08.074] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 08/19/2020] [Indexed: 12/12/2022]
Abstract
At present, fish provide an important supply of long-chain polyunsaturated fatty acids (LC-PUFAs) for human consumption. Previous studies have shown that fatty acyl elongase 2 (elovl2) and elovl5 play important roles in fish LC-PUFA synthesis. Generally, freshwater fish have a stronger ability to synthesize LC-PUFAs than marine fish. However, the roles of elovl2, elovl5 and elovl2 + elovl5 in LC-PUFA synthesis of freshwater fish in vivo are not very clear. In this study, the elovl2 knockout zebrafish (elovl2-/-), elovl5 knockout zebrafish (elovl5-/-) and the double gene knockout zebrafish (DKO) were generated by CRISPR/Cas9 technology for the first time. Compared with wild type zebrafish (WT), elovl5-deletion zebrafish showed a significant increase in C22 PUFA content, which might be due to the up-regulation expressions of elovl4b and elovl2. elovl5 expressed at very low levels in livers of elovl2-/- relative to WT, indicating that elovl5 may be an "assistant attacker" of elovl2 in LC-PUFA synthesis of zebrafish. Moreover, there were no significant differences in levels of C18-C22 PUFAs between DKO and WT, indicating that besides elovl2 + elovl5 path, LC-PUFA synthesis in zebrafish could be performed by other paths. In addition, the hepatic lipidomic analysis results revealed that the contents of C22:6n-3 in phosphatidyl ethanolamine (PE-DHA) and PE-C22 PUFAs were more easily affected by the absence of elovl2 and elovl5. Our results suggest that the elovl2+elovl5 path is not the only path for LC-PUFA synthesis in zebrafish, and provide novel insights into the roles of elovl2 and elovl5 in LC-PUFA synthesis of freshwater fish.
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Affiliation(s)
- Shouxiang Sun
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China
| | - Tianying Ren
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xin Li
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiaojuan Cao
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China; College of Fisheries, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education/Hubei Provincial Engineering Laboratory for Pond Aquaculture, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jian Gao
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China; College of Fisheries, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education/Hubei Provincial Engineering Laboratory for Pond Aquaculture, Huazhong Agricultural University, Wuhan, 430070, China.
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Katan T, Caballero-Solares A, Taylor RG, Rise ML, Parrish CC. Effect of plant-based diets with varying ratios of ω6 to ω3 fatty acids on growth performance, tissue composition, fatty acid biosynthesis and lipid-related gene expression in Atlantic salmon (Salmo salar). Comp Biochem Physiol Part D Genomics Proteomics 2019; 30:290-304. [PMID: 31003197 DOI: 10.1016/j.cbd.2019.03.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 03/11/2019] [Accepted: 03/14/2019] [Indexed: 01/02/2023]
Abstract
Little is known about how variation in omega-6 to omega-3 (ω6:ω3) fatty acid (FA) ratios affects lipid metabolism and eicosanoid synthesis in salmon, and the potential underlying molecular mechanisms. The current study examined the impact of five plant-based diets (12-week exposure) with varying ω6:ω3 (0.3-2.7) on the growth, tissue lipid composition (muscle and liver), and hepatic transcript expression of lipid metabolism and eicosanoid synthesis-related genes in Atlantic salmon. Growth performance and organ indices were not affected by dietary ω6:ω3. The liver and muscle FA composition was highly reflective of the diet (ω6:ω3 of 0.2-0.8 and 0.3-1.9, respectively) and suggested elongation and desaturation of the ω3 and ω6 precursors 18:3ω3 and 18:2ω6. Furthermore, proportions of ω6 and ω3 PUFA in both tissues showed significant positive correlations with dietary inclusion (% of diet) of soy and linseed oils, respectively. Compound-specific stable isotope analysis (CSIA) further demonstrated that liver long-chain polyunsaturated fatty acid (LC-PUFA) synthesis (specifically 20:5ω3 and 20:4ω6) was largely driven by dietary 18:3ω3 and 18:2ω6, even when 20:5ω3 and 22:6ω3 were supplied at levels above minimum requirements. In addition, significant positive and negative correlations were identified between the transcript expression of LC-PUFA synthesis-related genes and liver ω6 and ω3 LC-PUFA, respectively, further supporting FA biosynthesis. Liver ω3 LC-PUFA also correlated negatively with the eicosanoid synthesis-related transcripts pgds and cox1. This is the first study to use CSIA, hepatic transcriptome, and tissue lipid composition analyses concurrently to demonstrate the impact of plant-based diets with varying ω6:ω3 on farmed Atlantic salmon.
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Affiliation(s)
- Tomer Katan
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's A1C 5S7, NL. Canada.
| | - Albert Caballero-Solares
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's A1C 5S7, NL. Canada
| | | | - Matthew L Rise
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's A1C 5S7, NL. Canada
| | - Christopher C Parrish
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's A1C 5S7, NL. Canada.
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