Valorization of Seaweed Wracks : Inclusion as Additive in Diets for Grass Carp (Ctenopharyngodon idella)

Macroalgae have been recently described as a potential ingredient for aquafeeds, exerting several physiological benefits. Grass carp (Ctenopharyngodon idella) is a freshwater species, which has been the major fish species produced in the world in the last years. In order to determine the potential use of macroalgal wracks in fish feeding, C. idella juveniles were fed with an extruded commercial diet (CD) or the CD supplemented with 7% of a wind dried-powder (1 mm) from either a multispecific macroalgal wrack (CD + MU7) or a monospecific macroalgal wrack (CD + MO7) obtained from Gran Canaria island (Spain) coasts. After 100 days of feeding, survival, fish weight, and body indexes were determined, and muscle, liver, and digestive tract samples were collected. The total antioxidant capacity of macroalgal wracks was analyzed by assesing the antioxidant defense response and digestive enzymes activity in fish. Finally, muscle proximate composition, lipid classes (LC), and fatty acid (FA) profiles were also studied. Our results suggest that dietary inclusion of macroalgal wracks does not have negative effects on growth, proximate, and lipid composition, antioxidative status, or digestive capacity of C. idella. In fact, both macroalgal wracks caused a general lower fat deposition, and the multispecific wrack enhanced catalase activity in the liver.This study was funded by the European Interreg Programme 2014-2020 (MACBIOBLUE; MAC/1.1b/086). FCT–Fundação para a Ciência e a Tecnologia and as applicable cofinanced by the FEDER within the PT2020 Partnership Agreement by funding the cE3c centre (UID/BIA/00329/2019).info:eu-repo/semantics/publishedVersio

Polyunsaturated fatty acid metabolism in three fish species with different trophic level

Reducing the dependency of fishfeed for marine ingredients and species diversification are both considered crucial factors for the sustainable development of aquaculture. The substitution of fish oil (FO) by vegetable oils (VO) in aquafeeds is an economically feasible solution. However, such substitution may compromise the fish flesh content of essential n-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) and, therefore, its nutritional value for human consumption. Likewise, there is a wide range of strategies to select new target species for sector diversification, among which, the capacity to biosynthesize n-3 LC-PUFA from their C18 precursors abundant in VO might be considered as a fair preliminary strategy. Therefore, the aim of the present study was to analyze the metabolic fate of [1-14C] labeled 18:2n-6, 18:3n-3, 20:5n-3 and 22:6n-3 in isolated hepatocytes and enterocytes from wild individuals of three fish species with different trophic level: the marine herbivorous salema (Sarpa salpa), the strict carnivorous sand sole (Pegusa lascaris) and the omnivorous thicklip grey mullet (Chelon labrosus). These species were selected for their phylogenetic proximity to consolidated farmed species such as gilthead seabream (Sparus aurata), senegalese sole (Solea senegalensis), and golden grey mullet (Liza aurata), respectively. The study also assessed the molecular cloning, functional characterization and tissue distribution of the fatty acyl elongase (Elovl) gene, elovl5, involved in the biosynthetic metabolism of n-3 LC-PUFA. The three species were able to biosynthesize docosahexaenoic acid (22:6n-3). S. salpa seems to have similar biosynthetic capacity than S. aurata, with a fatty acyl desaturase 2 (Fads2), with 6, 8 and 5 activities. P. lascaris showed a wider Fads2 activity repertory than S. senegalensis, including 4 and residual 6/5 activities. In C. labrosus, both 8 and 5 activities but not the 6 described for L. aurata were detected in the incubated cells. Elongation from C18 and C20 precursors to C20 and C22 products occurred in hepatocytes and enterocytes as well as in the functional characterization of Elovl5 by heterologous expression in yeast. Elovl5 showed a species specific expression pattern, with the highest rates observed in the liver, gut and brain in S. salpa and P. lascaris, and in the brain for C. labrosus. In summary, the LC-PUFA biosynthesis capacity from S. salpa, P. lascaris and C. labrosus greatly resembled that of their phylogenetic closer species. The three studied species could be further explored as candidates for the aquaculture diversification from their potential ability to biosynthesize LC-PUFA

Effect of of Artemia inherent fatty acid metabolism on the bioavailability of essential fatty acids for Octopus vulgaris paralarvae development

The aim of the present study was to determine the effect of Artemia metanauplii endogenous fatty acid (FA) metabolism in the actual availability of dietary essential fatty acids (EFA) for Octopus vulgaris paralarvae development. To this end, both Artemia metanauplii inherent radiolabelled FA metabolism and the Octopus vulgaris paralarvae FA metabolism, after being fed with Artemia metanauplii incubated with radiolabelled. FAs, were determined. Metanauplii were incubated in tissue culture plates during 12 h, with 0.3 mu M of a [1-C-14]FA, including either 18:3n-3, 20:4n-6 (ARA), 20:5n-3 (EPA) or 22:6n-3 (DHA), added individually to separate wells as their potassium salts bound to bovine serum albumin. A total of 3600 one-day-old paralarvae were reared up to 24 h in order to ensure the ingestion of a minimum amount of the labelled Artemia. Paralarvae rearing was performed in 4 L cylinder conical tanks at a density of 25 paralarvae L-1. Labelled Artemia metanauplii were added to each paralarvae rearing tank according to a specific [1-C-14]FA treatment. Artemia in vivo metabolism results showed a preferential catabolism of DHA, which was translated into (1) the lower incorporation of this FA into Artemia total lipids (TL)(2) the highest amount of de novo synthesis of shorter chain-length FAs, as a result of the beta-oxidation of the original DHA substrate. The registered amounts of radiolabelled substrates incorporated into O. vulgaris paralarvae TL fed with labelled Artemia metanauplii were extremely low. Nonetheless, certain amount of intact [1-C-14]ARA and [1-C-14]EPA was recovered into octopus paralarvae TL, and particularly into polar lipid classes, suggesting the possibility of using Artemia as a vehicle to provide ARA and EPA to octopus paralarvae without interfering their bioavailability for the de novo synthesis of phospholipids. On the other hand, and despite of the high amount of [1-C-14]18:3n-3 incorporated into Artemia TL, the FAs with the highest esterification rate into Anemia TAG (18:3n-3 and DHA) were also the lowest incorporated into paralarvae TL. Therefore, the present results suggest that O. vulgaris paralarvae may have a potentially low capacity to metabolise dietary TAG, and so, Artemia may not be the most appropriate vehicle to provide DHA to paralarvae.Spanish GovernmentSpanish Government [AGL2010-22120-CO3]Fundacao para a Ciencia e a Tecnologia (FCT)Portuguese Foundation for Science and Technology [SFRH/BD/76863/2011]FCTPortuguese Foundation for Science and Technology [IF/00576/2014

Effect of feed supplementation with seaweed wracks on performance, muscle lipid composition, antioxidant status, digestive enzyme activities, and plasma biochemistry of gilthead seabream (Sparus aurata) juveniles

Macroalgal wracks are frequently considered as waste products. However, macroalgae are a rich source of protein and bioactive compounds with antioxidant and antimicrobial activities whose inclusion in aquafeeds is receiving growing attention. The aim of this study was to assess the use of beach-cast macroalgae as dietary supplement for gilthead seabream (Sparus aurata) juveniles. Fish were fed for 93 days with an extruded commercial diet (CD); a CD supplemented with 7% of a dried-powder from a multispecific macroalgal wrack (30.9% Lobophora sp., 21.9% Dictyota sp., 19.6% Asparagopsis taxiformis, 17.5% Cymopolia sp., 1.8% Hypnea sp., 0.2% Laurencia sp., 0.1% Stypocaulon sp., and 8% not determined) (CD+MU7); a CD supplemented with a monospecific macroalgal wrack of 85% Lobophora sp. (CD+MOL7); and a CD supplemented with a monospecific macroalgal wrack of 85% Dictyota sp. (CD+MOD7). Macroalgae were extracted with n-hexanes, ethyl acetate and ethanol, and the antioxidant capacity of extracts was assessed, with ethyl acetate leading to the most active extracts (p < 0.05). The dietary inclusions of a 7% macroalgal wrack did not negatively affect S. aurata survival, growth, body indexes, proximate composition, oxidative status and plasma parameters. Contrarily, fish fed on CD+MU7 and CD+MOD7 showed the highest monoacylglycerols content, while both monospecific diets led to the highest total saturated fatty acids content in muscle (p < 0.05). The digestive enzymes profile was slightly modified (p < 0.05), but without compromising fish performance. Finally, muscle from fish fed on CD+MOL7 seemed to display a better capacity to modulate the glutathione metabolism (p < 0.05). In conclusion, a 7% of macroalgal wracks can be used as a dietary supplement for S. aurata juveniles, depicting an attractive alternative for the effective harnessing of this usually discarded biomass. Macroalgal inclusion may also reduce the use of fish-based ingredients for aquafeeds, diminishing the pressure on pelagic fisheries, and contributing to the blue bioeconomy strategy

Ovarian Function Modulates the Effects of Long-Chain Polyunsaturated Fatty Acids on the Mouse Cerebral Cortex

Different dietary ratios of n−6/n−3 long-chain polyunsaturated fatty acids (LC-PUFAs) may alter brain lipid profile, neural activity, and brain cognitive function. To determine whether ovarian hormones influence the effect of diet on the brain, ovariectomized and sham-operated mice continuously treated with placebo or estradiol were fed for 3 months with diets containing low or high n−6/n−3 LC-PUFA ratios. The fatty acid (FA) profile and expression of key neuronal proteins were analyzed in the cerebral cortex, with intact female mice on standard diet serving as internal controls of brain lipidome composition. Diets containing different concentrations of LC-PUFAs greatly modified total FAs, sphingolipids, and gangliosides in the cerebral cortex. Some of these changes were dependent on ovarian hormones, as they were not detected in ovariectomized animals, and in the case of complex lipids, the effect of ovariectomy was partially or totally reversed by continuous administration of estradiol. However, even though differential dietary LC-PUFA content modified the expression of neuronal proteins such as synapsin and its phosphorylation level, PSD-95, amyloid precursor protein (APP), or glial proteins such as glial fibrillary acidic protein (GFAP), an effect also dependent on the presence of the ovary, chronic estradiol treatment was unable to revert the dietary effects on brain cortex synaptic proteins. These results suggest that, in addition to stable estradiol levels, other ovarian hormones such as progesterone and/or cyclic ovarian secretory activity could play a physiological role in the modulation of dietary LC-PUFAs on the cerebral cortex, which may have clinical implications for post-menopausal women on diets enriched with different proportions of n−3 and n−6 LC-PUFAs

Image_1_Ovarian Function Modulates the Effects of Long-Chain Polyunsaturated Fatty Acids on the Mouse Cerebral Cortex.pdf

<p>Different dietary ratios of n−6/n−3 long-chain polyunsaturated fatty acids (LC-PUFAs) may alter brain lipid profile, neural activity, and brain cognitive function. To determine whether ovarian hormones influence the effect of diet on the brain, ovariectomized and sham-operated mice continuously treated with placebo or estradiol were fed for 3 months with diets containing low or high n−6/n−3 LC-PUFA ratios. The fatty acid (FA) profile and expression of key neuronal proteins were analyzed in the cerebral cortex, with intact female mice on standard diet serving as internal controls of brain lipidome composition. Diets containing different concentrations of LC-PUFAs greatly modified total FAs, sphingolipids, and gangliosides in the cerebral cortex. Some of these changes were dependent on ovarian hormones, as they were not detected in ovariectomized animals, and in the case of complex lipids, the effect of ovariectomy was partially or totally reversed by continuous administration of estradiol. However, even though differential dietary LC-PUFA content modified the expression of neuronal proteins such as synapsin and its phosphorylation level, PSD-95, amyloid precursor protein (APP), or glial proteins such as glial fibrillary acidic protein (GFAP), an effect also dependent on the presence of the ovary, chronic estradiol treatment was unable to revert the dietary effects on brain cortex synaptic proteins. These results suggest that, in addition to stable estradiol levels, other ovarian hormones such as progesterone and/or cyclic ovarian secretory activity could play a physiological role in the modulation of dietary LC-PUFAs on the cerebral cortex, which may have clinical implications for post-menopausal women on diets enriched with different proportions of n−3 and n−6 LC-PUFAs.</p