Composition and Content of Fatty Acids in Muscle Tissue of the Potanin Altai Osman Oreoleuciscus potanini (Cypriniformes, Actinopterigii) from Mongolian Reservoirs.

The composition of fatty acids in the muscle tissue of the unique Central Asian carp-like fish, Potanin Altai osman Oreoleuciscus potanini, was studied for the first time. The populations of these fish in the reservoirs of the semiarid zone (Durgun and Taishir) during the period of their formation are considered. It was shown that the content of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in O. potanini corresponds to the median of this value in the order Cypriniformes. It was established that the basis of the food web of the herbivorous form of this species consists of microalgae (diatoms, Euglena and, possibly, chrysophytes), as well as bacteria. At the same time, the levels of bacterial biomarkers, 15-17BCFA and 17:0 were significantly higher in fish in the Durgun reservoir, whereas the level of EPA (diatom biomarker) in O. potanini was higher in the Taishir reservoir. The established higher values of the heavy nitrogen isotope content in the muscles of O. potanini from the Taishir reservoir are most likely associated with the yet unformed benthic communities and with the incomplete diversification of the riverine form of the Potanin Altai osman into lacustrine forms.

The Role of the Grass Snake Natrix natrix (Reptilia, Colubridae) in the Transfer of Polyunsaturated Fatty Acids from Aquatic to Terrestrial Ecosystems to Land.

As a result of analyses of fatty acid (FA) composition in the grass snake Natrix natrix and its food objects, tadpoles and metamorphs of two amphibian species: the moor frog Rana arvalis and the Pallas spadefoot toad Pelobates vespertinus, it was shown for the first time that the high total content of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids in the biomass of the snakes indicates its important role in the transfer of these essential substances from aquatic ecosystems to land. It was found that, since food sources of DHA in terrestrial ecosystems are absent, its high level in R. arvalis metamorps and grass snakes may be provided only by synthesis from biochemical precursors contained in food of aquatic origin.

Use of Caviar and Fillet Biomarker Fatty Acids to Determine the Origin of Sterlet Acipenser ruthenus (Linnaeus, 1758).

Significant differences in the fatty acid (FA) composition of caviar and muscle tissue (fillet) were found in the sterlet Acipenser ruthenus (Linnaeus, 1758) between fish from the Yenisei River and aquaculture farms and were associated with different food sources. Caviar and muscle tissue of sterlet from the natural habitat showed significantly higher levels of the FAs that provide biomarkers of diatoms and bacterial matter. Oleic and linoleic acids, which are characteristic of higher plant oils, and long-chain monounsaturated fatty acids, which are biomarkers of marine copepods, displayed significantly higher contents in sterlet grown in aquaculture, apparently originating from artificial foods. A ratio of several biomarker FAs was for the first time proposed to assay, and its threshold value was established to determine whether sturgeon caviar and fillet originate from fish from natural habitats or aquaculture.

Fatty Acid Profile of Juvenile Arctic Char (Salvelinus alpinus Complex) from Natural Ecosystems and Aquaculture.

Significant differences in the fatty acid composition of the muscle tissue of juvenile Arctic char Salvelinus alpinus (Linnaeus, 1758) from the natural habitat (Lake Sobach'e) and aquaculture, as well as juveniles of the anadromous form of char (malma) Salvelinus malma (Walbaum, 1792) from the Avacha River were found. The observed differences between aquaculture and wild juvenile char were associated with different food sources. The muscle tissue of juvenile char from natural habitat was characterized by significantly higher levels of fatty acids-biomarkers of diatoms, as well as biomarkers of marine copepods in the anadromous form. In the fatty acid composition of juvenile char from aquaculture, significantly higher levels of linoleic acid were revealed, as well as long-chain monounsaturated acids, the source of which could be aquaculture feed. The identified differences did not have a significant effect on the content of eicosapentaenoic and docosahexaenoic acids in the muscle tissue of juvenile aquaculture and wild char. The content of biochemically valuable omega 3 polyunsaturated fatty acids in juvenile char from natural ecosystems and aquaculture was similar.

Differences in Fatty Acid Composition between Orb-Weaver Spiders Inhabiting a Riparian Zone and a Steppe Are Associated with the Consumption of Different Chironomid Taxa.

Amphibiotic insects, chironomids of the genera Glyptotendipes and Chironomus, which emerged from saline Lake Shira, differed in composition and content of fatty acids, including the essential eicosapentaenoic acid (20:5n-3, EPA), and upon flying out they were concentrated in different territories, the riparian zone and remote arid steppe zone, respectively. Potential consumers of chironomids adults, the orb-weaver spiders Larinoides suspicax, which inhabited both zones, also differed in fatty acid composition. The main difference in their biochemical composition was a significantly higher level of EPA in spiders from the riparian zone that likely to be explained by consumption of the Glyptotendipes adults enriched in this fatty acid and concentrated only within this zone. The higher level of EPA, which is deficient in terrestrial ecosystems, in orb-weaver spiders from the riparian zone of the saline lake may potentially promote a successful survival of the consumers in the arid landscape.

Polyunsaturated Fatty Acid Content in Muscle Tissue Is Associated with the Duration of Embryo Development in Salmonoid Fishes (Salmonoidei).

A hypothesis was advanced and grounded that the total content of eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic (DHA, 22:6n-3) acids in fish muscle tissue is associated with the species-specific (taxon-specific) duration of embryo development. A meta-analysis of the original and published data was performed using fishes of the families Coregonidae and Salmonidae as an example. Fishes with longer embryo development times, which are observed at lower temperatures, were found to have significantly higher EPA + DHA contents in muscles as compared with the species that belong to the same families but have shorter embryo development times. This association was explained by the fact that an embryo forms more cells per unit tissue volume at lower temperatures, which requires a greater specific amount of cell membranes and, therefore, greater amounts of EPA and DHA to produce them.

Isotope Composition of Nitrogen and Stoichiometric Ratios of Elements in Biomass of Spirogyra in Lake Baikal.

Using stable isotope analysis of nitrogen, for the first time the hypothesis on different sources of inorganic nutrients for two groups of littoral algae in Lake Baikal was confirmed. Strongly attached filamentous algae of genus Ulothrix, which developed in the wave-braking zone at depth 0.5 m, and loosely attached filamentous algae of genus Spirogyra, which developed in deeper layers 3.0-5.0 m in a low-turbulence zone, get inorganic nutrients presumably from surface discharge and groundwater inputs, respectively. Besides, stoichiometric ratios C:N and N:P in biomass of the algae indicated that growth of Spirogyra in Lake Baikal was likely limited by nitrogen, while growth of Ulothrix was limited by phosphorus.

Amphibia as a Vector of Transfer of Long-Chain Polyunsaturated Omega-3 Fatty Acids from Aquatic to Terrestrial Ecosystems.

The flow of long-chain polyunsaturated fatty acids (PUFAs) of the omega-3 family, namely, eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA), exported by amphibian metamorphs from water to terrestrial ecosystems in the Medveditsa River floodplain, was quantified for the first time. The total biomass export by three amphibian species (Pelobates fuscus, Bombina bombina, and Pelophylax ridibundus) per unit area of the lake surface was 0.594 g/m2 per year (as a mean for 2 years). The biomass flow per unit area of land was 0.726 g/ha per year (0.302 g/ha per year for organic carbon) in 2015-2016. The average annual total removal of EPA + DHA by amphibians from the floodplain lake was 1.47 mg/m2 of water surface area. Due to the high content of EPA and DHA in biomass, amphibians are potentially a valuable food for terrestrial predators having no access to other sources of essential PUFAs.

Fatty acid composition of odonate's eyes.

We have studied the fatty acid composition of eyes of amphibiotic insects, namely, the odonate Sympetrum flaveolum. The main polyunsaturated fatty acid of odonate's eyes has been found to be 20:5n-3 (eicosapentaenoic fatty acid, EPA) rather than 18:2n-6 and 18:3n-3, which usually dominate in eyes of terrestrial insects, or 22:6n-3, which dominates in eyes of vertebrates. The prevalence of EPA in odonate's eyes probably provides a more effective transmission of light signal in this animal compared to terrestrial insects. It is important for odonates because vision plays a decisive role in finding and catching prey.

Fatty acid composition of fish species with different feeding habits from an Arctic Lake.

We compared the composition and content of fatty acids (FAs) in fish with different feeding habits (sardine (least) cisco Coregonus sardinella, goggle-eyed charr (pucheglazka) form of Salvelinus alpinus complex, humpback whitefish Coregonus pidschian, broad whitefish Coregonus nasus, boganid charr Salvelinus boganidae, and northern pike Esox lucius from an Arctic Lake. Feeding habits of the studied fish (planktivore, benthivore, or piscivore) significantly affected the composition of biomarker fatty acids and the ratio of stable isotopes of carbon and nitrogen in their biomass. The hypothesis on a higher content of eicosapentaenoic and docosahexaenoic acids in the fish of higher trophic level (piscivores) when compared within the same taxonomic group (order Salmoniformes) was confirmed.

Analysis of fatty acid composition revealed differences in the diets of tadpoles of two amphibian species.

The study of the composition of fatty acid markers of tadpoles of cohabiting amphibian species for the first time revealed differences in their diets: the moor frog Rana arvalis prefers bacteria not associated with plant detritus, whereas the diet of the common spadefoot Pelobates fuscus is based on cyanobacteria, green algae, diatoms, and possibly higher plants. Major differences in the fatty acid composition are determined by the difference in the percentage of eicosapentaenoic and myristic acids.

Benefit-risk ratio of canned pacific saury (Cololabis saira) intake: Essential fatty acids vs. heavy metals.

Fatty acid (FA) and element contents were studied in 14 brands of canned (in its own juice and with sunflower oil) saury (Cololabis saira), a popular product of Russian market. Canned saury is a valuable source of essential polyunsaturated FA - eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). To obtain personal daily dose of EPA + DHA of 1 g for prevention of cardiovascular diseases, neural and inflammatory disorders one needs to intake from 26 to 76 g of canned saury, as was calculated for studied brands. ICP-OES analysis of 24 elements showed that Pb concentration in one brand and Cd content in most of studied saury samples exceeded standards for fish meat established by the European Commission. However, values of hazard quotient, HQEFA, which estimate benefit-risk ratio of fish intake, indicate that canned saury is safe product for human nutrition.