Survival, Growth Performance, and Hepatic Antioxidant and Lipid Profiles in Infected Rainbow Trout (Oncorhynchus mykiss) Fed a Diet Supplemented with Dihydroquercetin and Arabinogalactan.

Natural feed supplements have been shown to improve fish viability, health, and growth, and the ability to withstand multiple stressors related to intensive cultivation. We assumed that a dietary mix of plant-origin substances, such as dihydroquercetin, a flavonoid with antioxidative, anti-inflammatory, and antimicrobial properties, and arabinogalactan, a polysaccharide with immunomodulating activity, would promote fish stress resistance and expected it to have a protective effect against infectious diseases. Farmed rainbow trout fish, Oncorhynchus mykiss, received either a standard diet or a diet supplemented with 25 mg/kg of dihydroquercetin and 50 mg/kg of arabinogalactan during a feeding season, from June to November. The fish in the control and experimental groups were sampled twice a month (eight samplings in total) for growth variable estimations and tissue sampling. The hepatic antioxidant status was assessed via the quantification of molecular antioxidants, such as reduced glutathione and alpha-tocopherol rates, as well as the enzyme activity rates of peroxidase, catalase, and glutathione-S-transferase. The lipid and fatty acid compositions of the feed and fish liver were analyzed using thin-layer and high-performance liquid chromatography. The viability, size, and biochemical indices of the fish responded to the growth physiology, environmental variables such as the dissolved oxygen content and water temperature, and sporadic factors. Due to an outbreak of a natural bacterial infection in the fish stock followed by antibiotic treatment, a higher mortality rate was observed in the fish that received a standard diet compared to those fed supplemented feed. In the postinfection period, reduced dietary 18:2n-6 and 18:3n-3 fatty acid assimilation contents were detected in the fish that received the standard diet in contrast to the supplemented diet. By the end of the feeding season, an impaired antioxidant response, including reduced glutathione S-transferase activity and glutathione content, and a shift in the composition of membrane lipids, such as sterols, 18:1n-7 fatty acid, and phospholipids, were also revealed in fish fed the standard diet. Dietary supplementation with plant-origin substances, such as dihydroquercetin and arabinogalactan, decreases lethality in fish stocks, presumably though the stimulation of natural resistance in farmed fish, thereby increasing the economic efficacy during fish production. From the sustainable aquaculture perspective, natural additives also diminish the anthropogenic transformation of aquaculture-bearing water bodies and their ecosystems.

Copper and Nickel Induce Changes in the Lipid and Fatty Acid Composition of Anodonta cygnea.

The effect of copper and nickel ions on the lipid composition of freshwater mussels Anodonta cygnea was investigated using an aquarium experiment. The contents of the main lipid classes were determined using thin layer chromatography and spectrophotometry, and the fatty acid composition was analysed using gas-liquid chromatography. The results indicated that copper and nickel had different effects on the mussels' lipid composition, with copper producing less effect on the composition of lipids and fatty acids than nickel. On the first experiment day, excessive copper content in the organism caused oxidative stress and modifications in membrane lipids, which returned to their initial level by the end of the experiment. Nickel accumulated predominantly in gills; however, significant modifications in lipids and fatty acids were seen also in the digestive gland from the first day of the experiment. This indicated the activation of nickel-induced lipid peroxidation processes. Moreover, this study revealed a dose-dependent effect of nickel on lipid composition, which was likely related to the development of compensatory biochemical mechanisms in response to nickel-induced oxidative stress. A comparative study of the lipid composition alteration in mussels in response to copper and nickel action revealed the consequences of the toxic impact of metal ions and the defensive mechanisms that organisms employ to detoxify and remove xenobiotics.

Tissue Lipid Profiles of Rainbow Trout, Oncorhynchus mykiss, Cultivated under Environmental Variables on a Diet Supplemented with Dihydroquercetin and Arabinogalactan.

Reared rainbow trout are vulnerable to environmental stressors, in particular seasonal water warming, which affects fish welfare and growth and induces a temperature response, which involves modifications in tissue lipid profiles. Dietary supplements of plant origin, including the studied mix of a flavonoid, dihydroquercetin and a polysaccharide, arabinogalactan (25 and 50 mg per 1 kg of feed, respectively), extracted from larch wood waste, were shown to facilitate stress tolerance in fish and also to be beneficial for the safety of natural ecosystems and the sustainability of aquaculture production. This four-month feeding trial aimed to determine the effects of the supplement on liver and muscle lipid accumulation and the composition in rainbow trout reared under environmental variables. During periods of environmental optimum for trout, a consistent increase in energy lipid stores, particularly triacylglycerols (2.18 vs. 1.49-fold over a growing season), and an overall increase in lipid saturation due to lower levels of PUFAs, such as eicosapentaenoic (20:5n-3), docosahexaenoic (22:6n-3) and arachidonic (20:4n-6) acids, were observed in both control and supplement-fed fish, respectively. However, in fish stressed by an increase in ambient temperature, dietary supplementation with dihydroquercetin and arabinogalactan reduced mortality (3.65 in control vs. 2.88% in supplement-fed fish, p < 0.05) and alleviated the high-temperature-induced inhibition of lipid accumulation. It also stabilised the membrane phospholipid ratio and moderated the fatty acid composition of fish muscle and liver, resulting in higher levels of n-3 PUFAs and their precursors. Thus, the natural compounds tested are beneficial in accelerating fish tolerance to environmental stressors, reducing mortality and thermal response, and moderately improving fillet quality attributes by increasing the protein/lipid ratio and the abundance of fatty acids essential for human nutrition.

Infection and antibiotic treatment have prolonged effects on gut microbiota, muscle and hepatic fatty acids in rainbow trout (Oncorhynchus mykiss).

AIMS: The aim of the present study was to investigate the gastrointestinal (GI) microbiota and bacterium-specific fatty acid occurrence in the muscle and hepatic lipids of rainbow trout Oncorhynchus mykiss (Walbaum, 1792), both healthy and those naturally infected with bacterial pathogens. METHODS AND RESULTS: From June 2017 (L1) to September 2018 (L8), 74 specimens of rainbow trout Oncorhynchus mykiss (with an average weight from 139.2 ± 7.1 g (L1) to 2191.7 ± 85.1 g (L8)) were studied. Amplicon sequencing targeted to the V3-V4 region of 16S rRNA gene fragments is used for the identification of the taxonomic composition of gut bacterial communities. Firmicutes, Bacteroidetes, Proteobacteria, Tenericutes and Fusobacteria were the major phyla. Besides behavioural and physiological manifestations of the bacterial mixed disease (yersiniosis, pseudomonosis and flavobacteriosis), some disorders induced by both the infection and followed antibiotic treatment were detected in the host organism, including (1) a progressive decrease in the content of odd-chain saturated fatty acids of bacterial origin within the trout lipid molecules and (2) abnormalities in trout GI tract microbiota, such as the elimination of LAB and progressive occurrence of certain bacterial taxa, particularly Mycoplasmataceae. CONCLUSIONS: The GI bacterial flora varied principally due to Mycoplasmataceae and Lactobacillaceae, which could be considered in the search for bioindicators. The content of specific bacterium-derived fatty acids incorporated into the lipids of trout muscle and hepatic seems to be related to the prevalence of bacterial taxa, and their deficit could be regarded as an early warning sign of microbiota disturbance. SIGNIFICANCE AND IMPACT OF STUDY: Our results demonstrated that infectious disease and antibiotic treatment of reared species can cause a pertinent imbalance in their gut microbiota and reduce the abundance of specific fatty acids. This can be useful for the sustainable aquaculture industry due to the development of early indication technologies for rapid disease diagnosis.

Changes of Heart Rate and Lipid Composition in Mytilus Edulis and Modiolus Modiolus Caused by Crude Oil Pollution and Low Salinity Effects.

Blue mussels, Mytilus edulis, inhabiting tidal zones, are naturally exposed to fluctuating environmental conditions (e.g., fluctuations in temperature and salinities), while horse mussels, Modiolus modiolus, live under relatively invariable shelf water conditions. The present investigation tested the hypothesis: blue mussels, in comparison to horse mussels, have an increased ability to tolerate the stress of pollution combined with low salinity. To assess the response of blue mussels and horse mussels to oil pollution at seawater salinities of 25 psu (normal) and 15 psu (low), we used a combination of heart rate and lipid composition as physiological and biochemical indicators, respectively. A sharp decrease in heart rate as well as important fluctuations in cardiac activity was observed under all oil concentrations. Modifications in the concentrations of the main membrane lipid classes (phosphatidylcholine, phosphatidylethanolamine, and cholesterol) and storage lipids (primarily triacylglycerols) in response to different crude oil concentrations were time- and dose-dependent. Both chosen indicators showed a high sensitivity to crude oil contamination. Furthermore, both bivalve species showed similar responses to oil pollution, suggesting a universal mechanism for biochemical adaptation to crude oil pollution.

Lipid profiles in Himasthla elongata and their intermediate hosts, Littorina littorea and Mytilus edulis.

In this research, the lipid profiles in rediae and free-living larvae (cercariae) of the trematodes Himasthla elongata were studied. It was shown that the lipid profiles of cercariae and rediae reflect the selective accumulation of membrane phospholipids and polyunsaturated fatty acids. In addition, infected tissues' lipid compositions in the intermediate hosts Littorina littorea (whole organism) and Mytilus edulis (foot) were studied. Modifications in the molluscs' lipid compositions were mainly caused by the parasites' metabolic requirements, as the parasites are unable to engage in de novo lipid biosynthesis, and thus, they utilise the host tissues' metabolites. The assumption that changes in the lipid unsaturation of infected intermediate hosts may affect their temperature resistance was discussed.

Does the membrane pacemaker theory of metabolism explain the size dependence of metabolic rate in marine mussels?

According to the membrane pacemaker theory of metabolism (MPT), allometric scaling of metabolic rate in animals is determined by the composition of cellular and mitochondrial membranes, which changes with body size in a predictable manner. MPT has been elaborated from interspecific comparisons in mammals. It projects that the degree of unsaturation of membrane phospholipids decreases in larger organisms, thereby lowering ion permeability of the membranes and making cellular, and thus whole-animal metabolism more efficient. Here, we tested the applicability of the MPT to a marine ectotherm, the mussel Mytilus edulis at the intraspecific level. We determined effects of body mass on whole-organism, tissue and cellular oxygen consumption rates, on heart rate, metabolic enzyme activities and on the lipid composition of membranes. In line with allometric patterns, the organismal functions and processes such as heart rate, whole-animal respiration rate and phospholipid contents showed a mass-dependent decline. However, the allometry of tissue and cellular respiration and activity of metabolic enzymes was poor; fatty acid unsaturation of membrane phospholipids of gill tissue was independent of animal size. It is thus conceivable that most of the metabolic allometry observed at the organismal level is determined by systemic functions. These whole-organism patterns may be supported by energy savings associated with growing cell size but not by structural changes in membranes. Overall, the set of processes contributing to metabolic allometry in ectotherms may differ from that operative in mammals and birds, with a reduced involvement of the mechanisms proposed by the MPT.

Effects of MTHFR gene polymorphism on the clinical and electrophysiological characteristics of migraine.

BACKGROUND: It was previously shown that the MTHFR gene polymorphism correlated with an increased risk of migraine, particularly migraine with aura. The substitution of cytosine for thymine at the position 677 of the MTHFR gene leads to formation of the thermolabile form of the protein and development of hyperhomocysteinemia, which increases the probability of migraine. The purpose of this study was to determine whether the replacement of C677T in the gene MTHFR influenced any particular symptoms of the disease. METHODS: We have analyzed clinical and electrophysiological characteristics of 83 patients with migraine (migraine with aura (MA), 19 patients, and migraine without aura (MO), 64 patients, according to the ICHD-II (2003)) taking into account their genotypes of C677T variant of MTHFR. RESULTS: We have shown that MA was significantly more prevalent among the T-allele carriers (37.2%), as compared to the СС genotype patients (0%), р < 0.0001. Patients with TT genotype were not only more likely to have accompanying symptoms (significant differences were found only for photophobia), but also more sensitive to migraine attack triggers. In RP-VEP test results we observed a trend that the T-allele carriers were presented with the decreased N75/P100 amplitudes and a positive habituation index, as compared to the СС genotype patients. CONCLUSIONS: Thus, according to our data, the MTHFR genotypes are associated with several clinical and electrophysiological characteristics of migraine.

Changes of blue mussels Mytilus edulis L. lipid composition under cadmium and copper toxic effect.

The lipid and fatty acid composition of the blue mussels Mytilus edulis L. gills and digestive glands was evaluated after 24 and 72 h of cadmium (Cd) and copper (Cu) exposure. Mussels were exposed to different cadmium (10, 100, and 500 µg/L) and copper (5, 50, and 250 µg/L) concentrations. Similar stress response of predominant membrane phospholipids level as well as polyenoic and non-methylene interrupted (NMI) fatty acids content was observed in mussel gills under both cadmium and copper effects. Increased NMI fatty acids level after 24 h, the metal ions treatment suggests that these acids contribute to the protective response to the membrane oxidative stress caused by accumulation of the metals. The content of cholesterol, some minor membrane phospholipids, and storage lipids (triacylglycerols, TAG) in the mussels' organs alter significantly under the cadmium and copper effect. A two-step response at the digestive glands TAG level depends on the duration of the cadmium and copper treatments (24 and 72 h) on the mussels. The results demonstrate that Cd and Cu impact has adverse effects on gills and digestive glands lipid and fatty acids composition. The type of observed effects varies with the nature and concentration of the metal ions and depends on the role of the metals in the mussels' life activity.

Physiological-biochemical properties of blue mussel Mytilus edulis adaptation to oil contamination.

Bivalves have a known ability to accumulate different contaminants from ambient water and can therefore serve as bioindicators. The paper analyses certain biochemical and physiological parameters of blue mussels in response to varying oil product concentrations. The heart rate (HR) of blue mussels from the sublittoral zone exposed to different levels of oil products was investigated in a long-term experiment using non-invasive monitoring. A sharp rise in HR was observed at oil concentrations of 8.0 and 38.0 mg/l. A decreasing in mussel HR under the effect of lower concentrations (0.4 and 1.9 mg/l) was significant on the fourth day. Strong fluctuations of the cardiac activity were noted under all concentrations. After 6 days of oil treatment, tissues of the mussels were sampled to determine the total lipid composition. Low concentrations of oil products produced no reliable changes in the lipid composition whereas high concentrations induced significant changes in the ratio of lipid components (cholesterol and phospholipids).