Phospholipid Composition of Fingerlings of Atlantic Salmon Salmo salar during Growth and Development in Aquaculture: The Effect of Different Lighting and Feeding Regimes.

The effect of different feeding and lighting regimes (natural and continuous) on the phospholipid composition of Atlantic salmon fingerlings reared in commercial aquaculture in the summer-autumn period in North Ossetia-Alania was studied. Qualitative and quantitative determination of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, lysophosphatidylcholine, sphingomyelin was performed by high-performance liquid chromatography. A decrease (September-November) in the content of the studied phospholipids in fingerlings decreased, which should be considered primarily as a biochemical adaptation of development and preparation of juveniles for the upcoming smoltification. The effects of lighting and feeding regime on phospholipid composition were found mainly in the fish reared under constant lighting and 24/7 feeding and the fish reared under natural light and feeding during daylight hours. However, the observed changes were not specific to a particular experimental group of fish in the framework of this study.

Fatty Acid Composition of Total Lipids in Atlantic Salmon Salmo salar L. Parr and Smolts Reared in Aquaculture at Various Lighting Regimes.

Continuous artificial lighting (24LD) was introduced experimentally in the standard technology to grow salmon juveniles in a southern region (Republic of North Ossetia-Alania) and its effect on fatty acid (FA) composition of total lipids in muscles and the liver was assessed in parr and smolts of the Atlantic salmon Salmo salar L. Changes in the key FA were observed in the FA spectrum of fish, indicating that smoltification was complete and that smolts were ready for new habitat conditions. Thus the content of polyunsaturated FAs (PUFAs) significantly increased as a result of an increase in (n-3) PUFAs, and, in particular, marine-type 22:6(n-3), and high values were observed for (n-3)/(n-6) and 22:6(n-3)/18:3(n-3) PUFA ratios. The most significant changes were detected in muscles. In all experimental groups, a decrease in saturated FAs (SFAs) and an increase in total lipid unsaturation was attributed primarily to PUFAs, while monounsaturated FAs (MUFAs) decreased along with SFAs. The experimental data on the lipid and FA composition in salmon juveniles and a higher proportion of smolts in the test groups indicated that smoltification was the most successful in groups with continuous lighting and 24-h feeding and a natural regime of lighting and feeding.

Effect of Salinity on Reproduction and Fatty Acid Profile of the Microalga Nitzschia сf. thermaloides.

The microalga Nitzschia cf. thermaloides was found in reservoirs of mud volcanoes in eastern Crimea. The species was observed to have a wide range of halotolerance and, in particular, to be capable of vegetative reproduction within a substrate salinity range of 0-110‰. The effect of salinity on the fatty acid (FA) profile was for the first time studied in N. cf. thermaloides. The quantitative and qualitative FA composition remained unchanged regardless of salinity, suggesting maintenance of a stable compacted membrane structure, which probably contributes to the species adaptation to salinity. Saturated FAs accounted for a major portion of total FAs, and the species was therefore assumed to provide a potentially valuable source of saturated FAs for biotechnology and an alternative raw material for biofuel.

Activities of Energy Metabolism Enzymes in Atlantic Salmon Salmo salar L. Smolts and Parr Grown under Different Light Regimens.

Activities of enzymes of energy and carbohydrate metabolism in muscles and the liver were studied in Atlantic salmon Salmo salar L. smolts and parr grown under continuous or natural lighting and different feeding regimens in autumn followed by a short photoperiod in winter. Enzyme activities were found to differ between test and control salmon groups and between parr and smolts sampled at the end of the winter period. Smolts grown under continuous lighting and round-the-clock feeding differed from other groups by having higher cytochrome c oxidase (COX) activity and lower aldolase activity in muscles. Differences in aerobic metabolism in muscles between parr and smolts were found to be the same in all experimental groups, COX and aldolase activities being relatively higher in smolts. The pattern of changes in enzyme activities in the liver from parr to smolts differed between different experimental groups. Based on the results, the photoperiod was assumed to affect the activities of energy metabolism enzymes in salmon juveniles and may eventually affect the completion of smoltification.

Antimicrobial Activity of Lipid Extracts of Echinoderms in the Nhatrang Bay (South China Sea).

The obtained results on the study of the antimicrobial activity of lipid extracts of tissues of starfishes Linckia laevigata and Culcita novaeguineae and sea urchin Diadema setosum collected in the Nhatrang Bay (South China Sea) against nosocomial strains of Klebsiella pneumoniae, Enterococcus faecium, Escherichia coli, Pseudomonas aeruginosa, Candida sp., Streptococcus pyogenes, and Staphylococcus aureus are presented. The effect of the investigated extracts on Gram-positive, Gram-negative microorganisms, as well as yeast of the genus Candida, was determined. It was found that lipid extracts of echinoderms of the Nhatrang Bay exhibit the highest antimicrobial activity against the Gram-positive microorganisms, namely Streptococcus pyogenes.

Cortisol Level and Na+/K+-ATPase Activity during Growth and Development of Juvenile Daubed Shanny Leptoclinus maculatus (Fries, 1838) in the Arctic.

The dynamics of cortisol level and Na+/K+-ATPase activity that are associated with the maintenance of cell ion homeostasis was studied in skeletal muscles of juvenile circumpolar fish daubed shanny Leptoclinus maculatus (Fries, 1838), an ecologically significant representative of the ichthyofauna of the Arctic Svalbard Archipelago. It was established that the level of cortisol and Na+/K+-ATPase activity decrease during the development of daubed shanny juveniles from stage L2 pelagic juveniles to stage L5 juveniles, which are mainly demersal. The results obtained suggest that cortisol may be involved in the regulation of the activity of one of the main osmoregulatory factors, Na+/K+-ATPase. This may be important for the growth and adaptation of pelagic juveniles of daubed shanny to the demersal habitat during postembryonic development in the Arctic.

Comparative Study of Lipid Content in Leptoclinus maculatus Postlarvae from Kongsfjord and Rjipfjord, Svalbard Archipelago.

A comparative study of lipid profile of the daubed shanny Leptoclinus maculatus postlarvae from fjords of different domains (arctic-boreal Kongsfjord and high-arctic Rjipfjord) of Svalbard Archipelago waters in summer was performed. A more efficient accumulation of lipids in the fishes from Kongsfjord compared to Rjipfjord due to triacylglycerols and wax esters was established. These differences may be related mainly to the trophic conditions of the habitat (species composition, abundance, and availability of food items). The higher level of cholesterol esters than wax esters at the L1 stage of development of the daubed shanny postlarvae compared to older fishes pointed to their active feeding mainly on phytoplankton. The differences in the content of certain classes of phospholipids may indicate adaptive changes at the level of biomembranes, contributing to the maintenance of cell homeostasis in response to abiotic environmental factors, and reflect their additional intake with food at the early stages of fish development.

Lipid Status of Gray Whales Eschrichtius robustus in the Piltun Feeding Area.

For the first time, the relationship of lipid and fatty acid composition with individual, gender and age characteristics of the gray whale Eschrichtius robustus in the Piltun feeding area is shown using the methods of biochemical analysis.

Morphology and phylogeny of Henneguya oviperda infecting oocytes of Esox lucius, with description of parasite-induced histopathology.

Henneguya oviperda (Cohn, 1895) (Myxozoa: Myxobolidae) is a parasite infecting oocytes of the northern pike Esox lucius Linnaeus, 1758 (Actinopterygii: Esocidae). Infected oocytes are surrounded by all oocyte layers, some of them thinner and less visible than intact oocytes. A mature plasmodium of H. oviperda fills the entire internal space of the oocytes at the secondary growth phase, rendering the nucleus and organelles of the latter undetectable. Apart from the observed degradation of internal structures, alterations in the envelopes of the infected oocytes, and the deformation of the intact oocytes adjacent to them, no other developmental anomalies have been found in the reproductive products of female northern pike. Mature spores of H. oviperda have oval bodies with polar capsules of almost equal size and caudal projections that are on average equal to the spore body length. Phylogenetic analysis comparing 18S rDNA sequences placed H. oviperda into a clade of esocid-infecting species of the genus Henneguya and also supported H. psorospermica as a sister species.

Dynamics of Estradiol Level during Metamorphosis in the Daubed Shanny (Leptoclinus maculatus, Fries, 1838) from Spitsbergen Island.

The estradiol content of muscles during metamorphosis in the daubed shanny (Leptoclinus maculatus) from different fjords of Spitsbergen Island, Svalbard, have been studied using mass spectrometry. The level of estradiol at the L4 larval stage of development is significantly lower than at the L2 stage. Values of this parameter in adults are significantly higher than in post-larvae (stage L5). Variations in the estradiol level during metamorphosis can be associated with the growth stimulation and regulation of the process.

Characteristics of the energy metabolism of the White Sea herring Clupea pallasii marisalbi Berg (Clupeiformes, Clupeidae) of Onega Bay, Dvina Bay, and Kandalaksha Bay of the White Sea.

The activity of the enzymes of the energy and carbohydrate metabolisms (cytochrome-c oxidase, L-lactate dehydrogenase, aldolase, and glycerol-1-phosphate dehydrogenase) have been studied in White Sea herring (the 1+, 2+, and 3+ age groups) sampled in Onega Bay, Dvina Bay, and Kandalaksha Bay of the White Sea. The bays differ in the hydrological regime, ecological and feeding conditions. The individual variability of the enzyme activity was the largest in the herring of the age 1+. The flexibility of the intensity and vector of the basic metabolic reactions probably supports the energy homeostasis, preconditions the switching to the most effective way of using the resources, and regulates the synthesis of the structural and storage molecules, as well as vectors the adaptation strategy of herring specimens of each age group to the hydrological regime, environment, and feeding conditions of the particular bay, corresponding to their age-related characteristics.

[Comparative Characteristics of the Lipid and Fatty Acid Status of Eyed-Stage Atlantic Salmon Embryos Reared in Natural and Artificial Environments].

The lipid status of Atlantic salmon (Salmo salar L.) embryos has been compared between embryos developing in incubator nests installed in the natural environment (UmbaRiver, Kola Peninsula) and those developing in a laboratory (in aquaria). The developmental stage of eye pigmentation selected for comparison is characterized by the highest sensitivity of the embryos to environmental factors. The content of certain classes of total lipids and fatty acids was different between the two groups of embryos, and the ratios between the relative content values for some of the compounds were different as well. The difference may be due to environmental factors (temperature, oxygen levels, running water in the nests, etc.) affecting the developing embryos, and they may determine the subsequent embryonic and postembryonic development of the fish.

Ontogenetic changes in the body structure of the Arctic fish Leptoclinus maculatus.

Histological studies of the ontogenetic changes in Arctic marine fishes are often fragmented and incomplete. Here we present a comprehensive histological ontogenetic analysis of the daubed shanny (Leptoclinus maculatus) from the Arctic, characterizing its development as it undergoes a series of changes in the organ and tissue organization, especially during the postlarvae transition from the pelagic to benthic lifestyle. The thyroid, heart, digestive tract, liver, gonads, blood, and the lipid sac of the postlarvae at different developmental stages (L1-L5) were studied for the first time. We found that L. maculatus has structural characteristics of marine fish developing in cold, high-oxygen polar waters. We conclude that the presence of the lipid sac and the absence of distinguishable red blood cells in pelagic postlarvae are unique features of the daubed shanny most likely linked to its successful growth and development in the Arctic environment.

[Dynamics of fatty acid composition of total lipids during embryonic development of Atlantic salmon Salmo salar L].

Dynamics of fatty acid composition of total lipids was studied for freshwater salmon Salmo salar L. during its embryonic development from blastula (3 hours) up to hatching (108 days) as well as in unfertilized eggs. Stable amount of total and some saturated, monounsaturated and polyunsaturated fatty acids (PUFA) of total lipids was observed during embryonic development. Considerable changes in fatty acid composition were observed at the stage of prelarvae hatching, i.e., significant decrease of (n-6) PUFA (18:2(n-6) and 20:4(n-6)) and (n-3) PUFA and increase of total and some saturated and monounsaturated fatty acids was registered. Change in saturation ratio of membrane lipids justifies the presence of the biochemical mechanism forwarded on regulation of cell membrane enzymes in accordance with the changes of internal physiological processes taking place in the organism and fluctuations of external environmental conditions or the preparation period (as reproduction). Data on peculiarities of transformation and utilization of fatty acids during salmon embryonic development may be used for understanding of their functional role in the developing organism as well as for assessing the quality of the caviar.