A nutritionally-enhanced oil from transgenic Camelina sativa effectively replaces fish oil as a source of eicosapentaenoic acid for fish

Abstract

For humans a daily intake of up to 500 mg omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) is recommended, amounting to an annual requirement of 1.25 million metric tonnes (mt) for a population of 7 billion people. The annual global supply of n-3 LC-PUFA cannot meet this level of requirement and so there is a large gap between supply and demand. The dietary source of n-3 LC-PUFA, fish and seafood, is increasingly provided by aquaculture but using fish oil in feeds to supply n-3 LC-PUFA is unsustainable. Therefore, new sources of n-3 LC-PUFA are required to supply the demand from aquaculture and direct human consumption. One approach is metabolically engineering oilseed crops to synthesize n-3 LC-PUFA in seeds. Transgenic Camelina sativa expressing algal genes was used to produce an oil containing n-3 LC-PUFA to replace fish oil in salmon feeds. The oil had no detrimental effects on fish performance, metabolic responses or the nutritional quality of the fillets of the farmed fish.

Figure 1. Impact of diet on liver transcriptome of Atlantic salmon given feeds containing Camelina oils (ECO and WCO) in comparison with fish fed fish oil (FO).

(A) Venn diagram representing mRNA transcripts differentially expressed in the liver of Atlantic salmon fed the experimental diets WCO and ECO compared to diet FO. The area of the circles is scaled to the number of transcripts (Welch t-test, p < 0.05). (B) Distribution by categories of common differentially expressed genes (428) in liver between Atlantic salmon fed WCO and ECO when compared to FO-fed fish (Welch t-test, p < 0.05). Non-annotated genes and features corresponding to the same gene are not represented.

Figure 2. Impact of diet on liver transcriptome of Atlantic salmon given a feed containing oil from transgenic Camelina (ECO) in comparison with fish given feeds containing fish oil (FO) or wild-type Camelina oil (WCO).

(A) Venn diagram representing mRNA transcripts differentially expressed in the liver of Atlantic salmon fed the ECO diet compared to fish fed the WCO and FO diets. The area of the circles is scaled to the number of transcripts (Welch t-test, p < 0.05). (B) Numbers of DEG ranked by fold-change and direction of change, up- or down, in fish fed ECO compared to fish fed FO or WCO (C) Distribution by categories of common differentially expressed genes (428) in liver between Atlantic salmon fed ECO compared to fish fed FO and WCO (Welch t-test, p < 0.05). Non-annotated genes and features corresponding to the same gene are not represented.

Figure 3. Cropped gel showing PCR products from liver (a), pyloric caeca (b) and muscle/flesh (c) of Atlantic salmon fed either WCO or ECO diets for nptII (transgenesis marker; top image) or gh (fish gene, bottom image). All the gels were run under the same experimental conditions. Lanes 1–6, Atlantic salmon fed WCO diet; Lanes 7–12, Atlantic salmon fed ECO diet; EPA-Camelina, transgenic Camelina seed cake; M, marker; NTC, non template control.