Updates to the n-3 polyunsaturated fatty acid biosynthesis pathway: DHA synthesis rates, tetracosahexaenoic acid and (minimal) retroconversion

Metherel, Adam H.; Bazinet, Richard P.

doi:10.1016/j.plipres.2019.101008

Cited by 67 publications

(55 citation statements)

References 126 publications

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“…Our data may thus indicate that the chosen dietary levels of EPA + DHA in this study were low. There are also indications that retroconversion of supplemented DHA to EPA occurs in humans, rats, and cell cultures but as reviewed by Metherel and Bazinet (2019) it is more likely that the reason behind this response is a feedback inhibition of EPA elongation to DPA n-3 (e.g., Metherel et al, 2017).…”

Section: Assimilation Of Fatty Acids In Whole Fish and Filetmentioning

confidence: 99%

Microalgal Schizochytrium limacinum Biomass Improves Growth and Filet Quality When Used Long-Term as a Replacement for Fish Oil, in Modern Salmon Diets

et al. 2020

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Aquaculture contributes to global food security but sustainable aquaculture development in terms of biodiversity impacts requires the establishment of viable solutions in replacement of the fisheries-based components in aquafeeds. In the current work, pit-tagged Atlantic salmon individuals were grown, from fresh water (18 g body weight) to salt water in tanks (up to 800 g body weight), on diets with low fish meal (FM) (10%) and 1-1.25% total n-3 LC-PUFA levels balanced across the experimental diets. Dietary n-3 LC-PUFAs were supplemented by (1) fish oil (FO), (2) Schizochytrium limacinum biomass (ScB), or (3) a mix of the two (FO/ScB). Further, the fish from all treatments were mixed and redistributed in sea cages reared to slaughter (ca. 3 kg body weight) on either FO or ScB. As FO was rich in both EPA and DHA and ScB was rich in DHA and nearly devoid of EPA, the experimental diets differed significantly in DHA/EPA ratio (0.8 vs. 10.5 in average for FO and ScB, respectively). ScB treatment fish grew to significantly higher body weight in the end of the experiment (2.8 kg vs. 3.3 kg, for FO and ScB, respectively) but similar FCR, survival rate, and biometric indexes compared to the FO groups. ScB fish contained higher levels of EPA + DHA in the filet but lower in the liver, and better filet pigmentation already from the tank phase of the experiment as determined chemically, by salmonfan and a trained sensory panel, and lower prevalence of melanin spots at slaughter. The trained sensory panel found no differences in flavor or odor in the filets from the different dietary groups; however, filets in the FO group were perceived as softer and juicier compared to ScB. The pre-diets up to 800 g body weight had minor effects on fish performance. Global transcriptomics in liver and intestinal tissues revealed significant dietary effects on the expression of immune modulating, as well as ion, lipid, protein, and xenobiotic metabolism genes.

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Section: Assimilation Of Fatty Acids In Whole Fish and Filetmentioning

confidence: 99%

Microalgal Schizochytrium limacinum Biomass Improves Growth and Filet Quality When Used Long-Term as a Replacement for Fish Oil, in Modern Salmon Diets

et al. 2020

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“…For DHA in mammals the synthesis from EPA involves the ‘Sprecher pathway’ [1,6], with a 24C intermediate and chain shortening by beta-oxidation. However, this biosynthetic route has recently been re-examined [7]. Once 20 or 22C PUFA have been produced they can be subject to oxidation by cyclooxygenase, lipoxygenase or epoxidase enzymes (Figure 2).…”

Section: Introductionmentioning

confidence: 99%

Algae: Critical Sources of Very Long-Chain Polyunsaturated Fatty Acids

Harwood

2019

Biomolecules

120

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Polyunsaturated fatty acids (PUFAs), which are divided into n-3 and n-6 classes, are essential for good health in humans and many animals. They are metabolised to lipid mediators, such as eicosanoids, resolvins and protectins. Increasing interest has been paid to the 20 or 22 carbon very long chain PUFAs, since these compounds can be used to form lipid mediators and, thus, avoid inefficient formation of dietary plant PUFAs. The ultimate sources of very long chain PUFAs are algae, which are consumed by fish and then by humans. In this review, I describe the biosynthesis of very long chain PUFAs by algae and how this synthesis can be manipulated for commercial purposes. Ultimately, the production of algal oils is critical for ecosystems worldwide, as well as for human dietary lipids.

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“…However, Δ 4 -desaturase activity could not be detected in mammalian tissues and so the ‘Sprecher pathway’ involving a 24:6 intermediate followed by beta-oxidation was proposed (see [ 83 ]). A recent article has suggested a re-visiting of the situation [ 84 ] but, nevertheless, the Sprecher pathway seems to be key in humans and, with the exception of a few teleost species, in fish also [ 85 ]. Thus, because fish are the main dietary source of n -3 VLCPUFA for humans, it is important that they contain adequate levels of EPA and DHA, and oily fish sources should be from capture fisheries or from aquaculture with an adequate supply of n -3 VLCPUFA in the feed.…”

Section: Production Of Vlcpufas From Dietary Essential Fatty Acidsmentioning

confidence: 99%

Oxidation of polyunsaturated fatty acids to produce lipid mediators

Christie

Harwood

2020

Essays in Biochemistry

150

102

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Abstract The chemistry, biochemistry, pharmacology and molecular biology of oxylipins (defined as a family of oxygenated natural products that are formed from unsaturated fatty acids by pathways involving at least one step of dioxygen-dependent oxidation) are complex and occasionally contradictory subjects that continue to develop at an extraordinarily rapid rate. The term includes docosanoids (e.g. protectins, resolvins and maresins, or specialized pro-resolving mediators), eicosanoids and octadecanoids and plant oxylipins, which are derived from either the omega-6 (n-6) or the omega-3 (n-3) families of polyunsaturated fatty acids. For example, the term eicosanoid is used to embrace those biologically active lipid mediators that are derived from C20 fatty acids, and include prostaglandins, thromboxanes, leukotrienes, hydroxyeicosatetraenoic acids and related oxygenated derivatives. The key enzymes for the production of prostanoids are prostaglandin endoperoxide H synthases (cyclo-oxygenases), while lipoxygenases and oxidases of the cytochrome P450 family produce numerous other metabolites. In plants, the lipoxygenase pathway from C18 polyunsaturated fatty acids yields a variety of important products, especially the jasmonates, which have some comparable structural features and functions. Related oxylipins are produced by non-enzymic means (isoprostanes), while fatty acid esters of hydroxy fatty acids (FAHFA) are now being considered together with the oxylipins from a functional perspective. In all kingdoms of life, oxylipins usually act as lipid mediators through specific receptors, have short half-lives and have functions in innumerable biological contexts.

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Updates to the n-3 polyunsaturated fatty acid biosynthesis pathway: DHA synthesis rates, tetracosahexaenoic acid and (minimal) retroconversion

Cited by 67 publications

References 126 publications

Microalgal Schizochytrium limacinum Biomass Improves Growth and Filet Quality When Used Long-Term as a Replacement for Fish Oil, in Modern Salmon Diets

Microalgal Schizochytrium limacinum Biomass Improves Growth and Filet Quality When Used Long-Term as a Replacement for Fish Oil, in Modern Salmon Diets

Algae: Critical Sources of Very Long-Chain Polyunsaturated Fatty Acids

Oxidation of polyunsaturated fatty acids to produce lipid mediators

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