Merits of the cyclopoid copepod Apocyclops dengizicus as a suitable and sustainable live feed for marine finfish seed production.

Long-chain polyunsaturated fatty acids, pregnancy, and pregnancy outcome

Short-term lecithin enrichments can enhance the phospholipid and DHA contents of the polar lipid fraction of Artemia nauplii

The European eel (Anguilla anguilla L.) exhibits a remarkable phenotypic plasticity by occupying both marine and freshwater habitats and transitional areas in between. Because these habitats are characterized by different food sources with different fatty acid compositions, it remains unclear how eels from different habitats obtain essential long-chain polyunsaturated fatty acids (LC-PUFAs) to integrate in their lipids. We studied whether the fatty acid composition of eels in three different habitats, that is, a marine lagoon, an estuary, and a river, could be related to the expression levels of genes involved in the LC-PUFA pathways. In general, there were no significant differences in gene expression between eels from marine and freshwater habitats; gene expression in marine and freshwater specimens significantly differed from eels caught in the estuary. However, levels of essential LC-PUFAs and fatty acid ratio markers differed significantly between eels from the river and the marine lagoon. Therefore, we conclude that the LC-PUFA composition of the European eel is likely defined by their food intake from the local environment they are living in and potentially affected by the prevailing conditions, such as food availability, temperature, and salinity.

Domestication of animals imposes strong targeted selection for desired traits but can also result in unintended selection due to new domestic environments. Atlantic salmon (Salmo salmar) was domesticated in the 1970s and has subsequently been selected for faster growth in systematic breeding programmes. More recently, salmon aquaculture has replaced fish oils (FOs) with vegetable oils (VOs) in feed, radically changing the levels of essential long-chain polyunsaturated fatty acids (LC-PUFAs). Our aim here was to study the impact of domestication on metabolism and explore the hypothesis that the shift to VO diets has unintentionally selected for a domestication-specific lipid metabolism. We conducted a 96-day feeding trial of domesticated and wild salmon fed diets based on FOs, VOs or phospholipids, and compared transcriptomes and fatty acids in tissues involved in lipid absorption (pyloric caeca) and lipid turnover and synthesis (liver). Domesticated salmon had faster growth and higher gene expression in glucose and lipid metabolism compared to wild fish, possibly linked to differences in regulation of circadian rhythm pathways. Only the domesticated salmon increased expression of LC-PUFA synthesis genes when given VOs. This transcriptome response difference was mirrored at the physiological level, with domesticated salmon having higher LC-PUFA levels but lower 18:3n-3 and 18:2n-6 levels. In line with this, the VO diet decreased growth rate in wild but not domesticated salmon. Our study revealed a clear impact of domestication on transcriptomic regulation linked to metabolism and suggests that unintentional selection in the domestic environment has resulted in evolution of stronger compensatory mechanisms to a diet low in LC-PUFAs.

Elongation of very long-chain fatty acid (Elovl) proteins plays pivotal functions in the biosynthesis of the physiologically essential long-chain polyunsaturated fatty acids (LC-PUFA). Polychaetes have important roles in marine ecosystems, contributing not only to nutrient recycling but also exhibiting a distinctive capacity for biosynthesizing LC-PUFA. To expand our understanding of the LC-PUFA biosynthesis in polychaetes, this study conducted a thorough molecular and functional characterization of Elovl occurring in the model organism Platynereis dumerilii. We identify six Elovl in the genome of P. dumerilii. The sequence and phylogenetic analyses established that four Elovl, identified as Elovl2/5, Elovl4 (two genes) and Elovl1/7, have putative functions in LC-PUFA biosynthesis. Functional characterization confirmed the roles of these elongases in LC-PUFA biosynthesis, demonstrating that P. dumerilii possesses a varied and functionally diverse complement of Elovl that, along with the enzymatic specificities of previously characterized desaturases, enables P. dumerilii to perform all the reactions required for the biosynthesis of the LC-PUFA. Importantly, we uncovered that one of the two Elovl4-encoding genes is remarkably long in comparison with any other animals' Elovl, which contains a C terminal KH domain unique among Elovl. The distinctive expression pattern of this protein in photoreceptors strongly suggests a central role in vision.

Environmental contaminants such as persistent organic chlorines and heavy metals, which are supplied to the foetus by transplacental transfer and to breastfed infants by the milk, may impair cognitive functions. Long-chain polyunsaturated fatty acids, which are known to enhance development during foetal life and early infancy, may counteract the toxic effect of environmental contaminants. In this study, we have investigated whether polychlorinated biphenyls (PCBs) impair early development of vision, and whether such impairment can be modulated by essential long-chain polyunsaturated fatty acids. Healthy term infants born in Milan and its surroundings, and who were exclusively breastfed for at least 4 mo, were prospectively examined up to the age of 12 mo. Samples from colostrums, the first 2 d after delivery, and of mature breast-milk after 1 and 3 mo were collected. The samples were analyzed for PCB 105, 118, 138, 153, 156 and 180 and for DDT and DDE. In all infants, the plasma levels of the long-chain polyunsaturated fatty acids (LC-PUFAs), C18:2 n-6, C18:3 n-3, C20:4 n-6, C20:5 n-3 and C22:6 n-3 were analysed within the first three postnatal days. The PCB levels in colostral milk, as well as of LC-PUFAs in plasma, were considered to mirror perinatal supply. Visual function was evaluated by P100 with latency evoked potentials (VEPs) at 12 mo of age. Statistical analysis was based on simple and partial correlation coefficients (p < 0.05). On bivariate analysis, wave latency VEP at 15 min was significantly related to the colostral levels of DDT, DDE and all examined PCBs except PCB 105 (with correlation coefficient r = 0.401 to 0.618), whereas P100 wave latency VEP at 60 min was related to DDT (r = 0.513) and PCB 180 (r = 0.504). Infant plasma levels of C22:6 n-3 were inversely associated with P100 wave latency at 60 min (r = -0.418) and at 1Hz-2J (r = -0.466). After controlling for C22:6 n-3, the partial correlation coefficient of P100 wave latency VEP at 15 min to the colostral level of PCB 180 was 0.403 (p = 0.07). Within the population of this study, a weak relation was found between impaired visual function at 12 mo of age of healthy infants and the levels of PCBs, DDT and DDE in colostral milk. The effect of impairment was no longer evident after controlling for the plasma level of LC-PUFAs as found in the infant a few days after birth.

New strategies are required to enhance the efficient assimilation and bioconversion of plant-based ingredients in Atlantic salmon (Salmo salar) diets, especially relating to the essential long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). Our study investigated nutritional programming and specifically evaluated the optimal duration of dietary ‘stimulus’ and whether it could be reduced compared to a previous study using a three- week ‘stimulus’. Fish were fed an experimental ‘stimulus’ vegetable-based diet (VS, 5% marine meals [MM]/0% fish oil [FO]) or a standard marine-based control (MS, 82% MM/4% FO) for either one (V1) or two weeks (V2 and M) from first exogenous feeding. All groups were then fed a standard marine based formulation, for an ‘intermediate’ grow-out phase to the end of 16 weeks post-first feeding, prior to a ‘challenge’ phase of six weeks when all fish were fed a vegetable-based diet (VC, 10% MM/0% FO). Compared to M, fish from both V1 and V2 groups were significantly smaller at the end of the ‘stimulus’ phase, but there were no statistical differences in overall growth, proximate or fatty acid compositions at the end of the trial. However, hepatosomatic and viscerosomatic indices were significantly lower in V1 compared to V2 fish and there was an overall trend of improved performance in V1 fish throughout the ‘intermediate’ and ‘challenge’ phases. During the ‘challenge’ phase, M fish displayed a greater net gain of DHA than V1 fish, whilst V2 was a net consumer of all n-3 LC-PUFA over the same period. Compared to M, n-3 LC-PUFA biosynthesis genes in pyloric caeca were downregulated in both experimental groups indicating possible post-transcriptional modification of this pathway in either V1 or V2, considering the differences in DHA retention levels between groups. Taken together, the results suggested that nutritional programming was not initiated by a one- or two- week ‘stimulus’. However, more studies are required to elucidate the mechanism behind enhanced performance of V1 fish.

The biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFA) provides an intriguing example on how multi-enzymatic cascades evolve. Essential LC-PUFA, such as arachidonic, eicosapentaenoic, and docosahexaenoic acids (DHA), can be acquired from the diet but are also endogenously retailored from C18 precursors through consecutive elongations and desaturations catalyzed, respectively, by fatty acyl elongase and desaturase enzymes. The molecular wiring of this enzymatic pathway defines the ability of a species to biosynthesize LC-PUFA. Exactly when and how in animal evolution a functional LC-PUFA pathway emerged is still elusive. Here we examine key components of the LC-PUFA cascade, the Elovl2/Elovl5 elongases, from amphioxus, an invertebrate chordate, the sea lamprey, a representative of agnathans, and the elephant shark, a basal jawed vertebrate. We show that Elovl2 and Elovl5 emerged from genome duplications in vertebrate ancestry. The single Elovl2/5 from amphioxus efficiently elongates C18 and C20 and, to a marked lesser extent, C22 LC-PUFA. Lamprey is incapable of elongating C22 substrates. The elephant shark Elovl2 showed that the ability to efficiently elongate C22 PUFA and thus to synthesize DHA through the Sprecher pathway, emerged in the jawed vertebrate ancestor. Our findings illustrate how non-integrated “metabolic islands” evolve into fully wired pathways upon duplication and neofunctionalization.

Influence of dietary protein on essential fatty acids in the gonadal tissue of the sea urchins Psammechinus miliaris and Paracentrotus lividus (Echinodermata)

Structured Lipid Functionality and Application

Fish oil-free diets for Pacific white shrimp Litopenaeus vannamei: The effects of DHA-EPA supplementation on juvenile growth performance and muscle fatty acid profile

Regulatory divergence of homeologous Atlantic salmon elovl5 genes following the salmonid-specific whole-genome duplication

Associations between term birth dimensions and prenatal exposure to essential and trans fatty acids

Omega-3 fatty acids (FAs) are essential long-chain polyunsaturated fatty acids (LCPUFAs) that are essential for optimal health and development. The present study aimed to evaluate the effectiveness of maternal fish oil (containing omega-3 LCPUFA) intake from 21th week of pregnancy to 30 days postpartum for neurodevelopment and growth of infants at 9 and 12 months. This was a follow-up study of a triple-blinded clinical trial. The study population was 9- month-old infants. Their mothers were randomly divided into two groups of 75 people with a 1:1 ratio to take one fish oil supplement or a placebo daily. The anthropometric indicators of infants at months 9 and 12 and neurodevelopment at month 12 by the ASQ questionnaire were measured. In the fish oil and placebo groups, respectively, 73 and 71 infants at nine months, as well as 71 and 69 at 12 months, were analyzed. No statistically significant impact was observed following consuming omega-3 capsules on the neurodevelopmental domains, growth parameters, and the profile of maternal serum FAs (p > 0.05) except DHA. Neurodevelopmental problems were illustrated in one case in the intervention group and two cases in the placebo group. Perinatal relatively low-dose omega-3 LCPUFAs supplements indicated no statistically significant impacts on the growth and neurodevelopment of 9- and 12-month-old infants in a population with low consumption of marine products. Further studies investigating the effect of higher doses of omega-3 LCPUFAs are suggested.

Metabolic and endocrine effects of long-chain versus essential omega-3 polyunsaturated fatty acids in polycystic ovary syndrome