Fatty Acid Composition and Contents of Fish of Genus Salvelinus from Natural Ecosystems and Aquaculture

Fatty acids (FA) of muscle tissue of Salvelinus species and its forms, S. alpinus, S. boganidae, S. drjagini, and S. fontinalis, from six Russian lakes and two aquacultures, were analyzed. Considerable variations in FA compositions and contents were found, including contents of eicosapentaenoic and docosahexaenoic acids (EPA and DHA), which are important indicators of fish nutritive value for humans. As found, contents of EPA+DHA (mg·g−1 wet weight) in muscle tissue of Salvelinus species and forms varied more than tenfold. These differences were supposed to be primarily determined by phylogenetic factors, rather than ecological factors, including food. Two species, S. boganidae and S. drjagini, had the highest EPA+DHA contents in their biomass and thereby could be recommended as promising species for aquaculture to obtain production with especially high nutritive value. Basing on revealed differences in FA composition of wild and farmed fish, levels of 15-17-BFA (branched fatty acids), 18:2NMI (non-methylene interrupted), 20:2NMI, 20:4n-3, and 22:4n-3 fatty acids were recommended for verifying trade label information of fish products on shelves, as the biomarkers to differentiate wild and farmed charr.

The Influence of Transglutaminase on Minced Muscular Fish Tissue Structure Formation After the Application of Various Protein Substrates

This research aimed to examine the effect of a microbial transglutaminase preparation (Activa® GS, Ajinomoto Co., Inc, Japan) on the structure formation of the myofibrillar protein system of a deep-sea fish species – the giant grenadier – after the addition of various protein substrates. The low content of proteins and their low water-holding capacity in this fish, subjected to various processing methods, leads to significant losses in the initial mass and decreased gelation ability in the muscle tissue system. Various concentrations of transglutaminase were used but these did not ensure the restructuring of the initial muscle tissue of the grenadier. Additional protein substrates with different molecular weights and amino acid composition were added, including gelatin, milk casein, hydrolysates of the skin and milt of the fish, and whole bivalves, which were used to create a firm structure. It was shown that the introduction of gelatin and casein at a concentration of 5% led to the formation of a firm, thermostable structure under the action of the enzyme, while hydrolyzed proteins with low molecular weight at their various concentrations enhanced the expression of water and formation of the fluid consistency. The ability of gastrointestinal tract proteases (pepsin and trypsin) to digest did not depend on the formation of protein-to-protein cross-linking in these combined products. The influence on the growth of the Tetrahymena pyriformis ciliates test culture also showed the high degree of product availability. The technology of molded products based on fermented minced muscle tissue of grenadier with added casein, both in the form of semi-finished products and in the form of ready-to-eat products, was developed. Keywords: transglutaminase, muscle tissue, structure formation, deep-sea fish

Effect of Methylmercury Exposure on Bioaccumulation and Nonspecific Immune Respsonses in Hybrid Grouper Epinephelus fuscoguttatus × Epinephelus lanceolatus

Mercury (Hg) is a dangerous heavy metal that can accumulate in fish and is harmful when consumed by humans. This study investigated the bioaccumulation of mercury in the form of methylmercury (MeHg) and evaluated nonspecific immune responses such as phagocytic activity and superoxide anion (O2−) production in hybrid grouper (Epinephelus fuscoguttatus × E. lanceolatus). The hybrid grouper leukocytes were incubated with methylmercury chloride (CH3HgCl) at concentrations of 10–10,000 µg/L to determine cell viability, phagocytic activity, and O2− production in vitro. Subsequently, the grouper were exposed daily to CH3HgCl mixed in the experimental diets at concentrations of 0, 1, 5, and 10 mg/kg for 28 days. The bioaccumulation of MeHg in the liver, head kidney, and muscle tissue was measured, and the phagocytic activity and O2− production were evaluated. In vitro results indicated that cell viability was significantly lower than that of the control group at concentrations > 500 µg/L. The phagocytic rate and O2− production at concentrations ˃ 500 and ˃ 200 µg/L, respectively, were significantly lower than those of the control group. The dietary exposure demonstrated that MeHg accumulated more substantially in the liver and head kidney compared with the muscle tissue in the treatment groups. Moreover, the cumulative concentration significantly increased with higher concentrations and more days of exposure. The phagocytic rate and O2− production in the treatment groups were significantly lower than those in the control group from days 2 and 1, respectively. In conclusion, hybrid grouper accumulated significant MeHg in the liver and head kidney compared with the muscle tissue, and higher concentrations and more exposure days resulted in decreased cell viability, phagocytic activity, and O2− production.

Comparative proteomic study of pig muscle proteins during growth and development of an animal

The production of high-quality pork is closely related to the growth and development of muscle tissue. The present article provides a comparative proteomic research of l. dorsi, b. femoris, m. brachiocephalicus during the pigs’ growth and development (at age of 60 days and 180 days). This work was supported by data of electrophoretic methods: one-dimensional electrophoresis according to Laemmli with densitometric assessment in the ImageJ software and two-dimensional electrophoresis according to O’Farrell method with its further processing on the software ImageMaster. The mass spectrometric identification was conducted with the help of the high-performance liquid chromatography (HPLC) system connected to a mass spectrometer; further the data were interpreted by search algorithm Andromeda. When comparing frequency diagrams of one-dimensional electrophoregrams of all three muscle tissues of weaned pigs, the greatest difference was observed for the muscle sample l. dorsi. Comparison of diagrams of muscle tissue samples taken for mature pigs showed a great similarity of all three studied muscles samples. Within the framework of the research, the Fold indicator was calculated. The exceeding its value by more than 2 units is generally considered to be a statistically significant difference. When analyzing two-dimensional electrophoretograms of weaned pigs’ muscles, 18 protein fractions were revealed with Fold > 2. When examining the muscle tissue of mature pigs, 15 of those proteins were found; the differences were mostly detected in the minor protein fractions. The mass spectrometric analysis of the cut bands with well-pronounced differences from the onedimensional electrophoretogram revealed 214 proteins involved to a greater extent in cellular and metabolic processes, physical activity and localization. Growth and development protein — semaphorin‑6B (96.78 kDa) — was revealed in muscle tissue of l. dorsi, a. Also in l. dorsi and b. femoris the growth and development proteins were found: cadherin‑13 (78.23 kDa), cadherin‑7 (87.01 kDa), the F‑actin-cap protein beta subunit (30.66 kDa), and two uncharacterized proteins at 65.60 kDa and 63.88 kDa.

Nanoengineered myogenic scaffolds for skeletal muscle tissue engineering

Here, we developed a nano-engineered biomaterial optimized for skeletal muscle proliferation and differentiation. Nanoclay disks were used to control the release of insulin-like growth factor (IGF-1), a key myogenic and immunogenic regulator.