Stable Isotope Composition of Fatty Acids in Organisms of Different Trophic Levels in the Yenisei River

We studied four-link food chain, periphytic microalgae and water moss (producers), trichopteran larvae (consumers I), gammarids (omnivorous – consumers II) and Siberian grayling (consumers III) at a littoral site of the Yenisei River on the basis of three years monthly sampling. Analysis of bulk carbon stable isotopes and compound specific isotope analysis of fatty acids (FA) were done. As found, there was a gradual depletion in 13C contents of fatty acids, including essential FA upward the food chain. In all the trophic levels a parabolic dependence of δ13C values of fatty acids on their degree of unsaturation/chain length occurred, with 18:2n-6 and 18:3n-3 in its lowest point. The pattern in the δ13C differences between individual fatty acids was quite similar to that reported in literature for marine pelagic food webs. Hypotheses on isotope fractionation were suggested to explain the findings

Fatty Acid Content and Composition of Fly Larvae Lucilia sericata (Family Calliphoridae) Grown on Diets with Different Content of Polyunsaturated Fatty Acids and the Amino Acid Composition of this Species

Аквакультура – быстроразвивающаяся отрасль сельского хозяйства, однако сейчас она столкнулась с недостатком кормов, основу которых составляют уловы дикой рыбы, и, как следствие, повышением их стоимости. Для дальнейшего устойчивого развития аквакультуры необходимо разработать альтернативные корма, производимые не из дикой рыбы. Насекомые рассматриваются как подходящий источник кормового белка для рыб, однако их жирнокислотный (ЖК) состав часто не соответствует требованиям аквакультуры. В рыбьем жире среди ПНЖК доминируют кислоты семейства омега‑3, а в наземных насекомых – семейства омега‑6. Исследование возможности модификации ЖК состава личинок насекомых для увеличения содержания омега‑3 ПНЖК является актуальной задачей. Целью данной работы было изучить состав и содержание жирных кислот в личинках мухи Lucilia sericata, выращенных на стандартном корме и корме с добавлением рыжикового масла, богатом альфа-линоленовой кислотой (АЛК, 18:3n‑3), и проанализировать аминокислотный состав (АК) личинок данного вида мух. ЖК анализ проводили на газовом хроматографе с масс-спектрометрическим детектором. АК анализ выполняли на жидкостном хроматографе. АК состав исследованных личинок мух, как и других насекомых отряда Diptera, был близок к АК составу рыбной муки. Состав и содержание жирных кислот личинок мухи на стандартном корме характеризовались низким соотношением омега‑3 / омега‑6 ПНЖК и доминированием 18:1n‑9 и 18:2n‑6 – жирных кислот, которые суммарно составляли от 40 % до 60 % от суммы ЖК. Добавление рыжикового масла изменило соотношение омега‑3 / омега‑6 ПНЖК с 0,11 до 0,46, главным образом за счёт увеличения содержания АЛК. Таким образом, ЖК состав личинок L. sericata может быть существенно модифицирован пищейAquaculture is a fast-growing branch of agriculture, but it faces fish feed shortages due to a decrease in wild fish catches. As a result, the price of feed increases. For further development it requires alternative feed sources. Insects are considered a suitable protein source for fish, but their fatty acid (FA) composition often does not meet the requirements of aquaculture. In fish oil, PUFAs are dominated by the omega‑3 family, and in terrestrial insects, by the omega‑6 family. A question arises whether insect larvae lipid composition can be modified to increase the content of omega‑3 PUFAs. For this purpose, Lucilia sericata larvae were grown on standard feed and feed with addition of camelina oil rich in alpha-linolenic acid (ALA, 18:3n‑3), and their FA content and composition were compared. To evaluate the quality of these larvae protein, their amino acid (AA) composition was determined. The FA analysis was performed on a gas chromatograph equipped with a mass-spectrometer detector. The AA analysis was performed on a liquid chromatograph. The AA composition of the examined fly larvae, similarly to other insects (Diptera), was close to the AA composition of fish meal. Fatty acid composition and content of fly larvae grown on standard food was characterized by a low ratio of omega‑3/omega‑6 PUFAs and by the dominance of 18:1n‑9 and 18:2n‑6 fatty acids, which together comprised 40–60 % of the total of FAs. The addition of camelina oil changed the ratio of omega‑3/ omega‑6 PUFAs from 0.11 to 0.46, mainly due to the increase in ALA content. Thus, FA content and composition of L. sericata larvae can be significantly modified by a die

Fatty Acids of Sestonic Lipid Classes as a Tool to Study Nutrition Spectra of Rotifers and Ciliates in a Siberian Eutrophic Reservoir

Fatty acid composition of triacylglycerols (TAG) and polar lipids (PL) of seston from the Siberian Reservoir Bugach was analyzed to reveal the spectra of nutrition of micro- and mesozooplankton (protozoa and rotifers). The seasonal changes of micro- and mesozooplankton nutrition were observed. Bacteria comprised relatively constant part in feeding protozoa and rotifers during the whole vegetation season. The maximum consumption of higher plants detritus occurred at the beginning of August. Phytoplankton was consumed more intensively in spring during the rapid growth of diatoms (Stephanodiscus sp.) and from the middle to the end of June when cyanobacteria (Anabaena flos-aquae, Aphanizomenon flos-aquae, Planktothrix agardhii), dynophytes (Peridinium sp.) euglenas (Euglena proxima) and diatoms (Stephanodiscus sp.) were dominated in Bugach Reservoir. The dominant species of protozoa differed in their nutrition spectra: Holophrya sp. was feeding on diatoms in spring and bacteria in the middle of summer; Tintinidium sp. was consuming diatoms and cyanobacteria; Nassula picta was feeding on cyanobacteria

Fluxes of Biomass and Essential Polyunsaturated Fatty Acids from Water to Land via Chironomid Emergence from a Mountain Lake

The taxonomic composition, seasonal dynamics, and emergence intensity of chironomid adults (the Chironomidae family) merging from Oiskoe mountain oligotrophic lake (Western Sayan, Southern Siberia) have been established. The value of the annual emergence of chironomid adults averages 0.42 g wet weight m−2 in the lake area and approaches the value of potential emergence, which is calculated based on the estimate of zoobenthos secondary production. For the first time the fatty-acid composition and contents of essential omega-3 polyunsaturated fatty acids (PUFAs) are compared between the larvae and adult stages of chironomids. The PUFA content per wet weight unit in adults is more than 7 times higher than that in larvae. The PUFA flux per lake area unit resulting from the chironomid emergence amounted to 1.752 mg m−2 y−1, which is over 10 times lower than the global estimate for the emergence of amphibiotic insects. Calculations show that the PUFA flux brought with the chironomid emergence per land unit of the studied mountain territory is very low when compared to that for other landscapes, with the exception of the shoreline part of the territory with a width of 15 m, in which the PUFA flux is comparable to that in productive landscapes

Fatty Acid Content and Composition of Freshwater Planaria Dendrocoelopsis sp. (Planariidae, Turbellaria, Platyhelminthes) from the Yenisei River

For the first time the fatty acid content and composition of freshwater planarian Dendrocoelopsis sp. has been studied in a station of the large Siberian River, the Yenisei. The dominant fatty acids were palmitic, oleic, eicosapentaenoic and docosapentaenoic acids. The characteristic feature of planarian fatty acid composition was that ω3 docosapentaenoic acid was 2-10 times higher than docosahexaenoic acid. The average content of ω3 PUFA in the planarian was significantly higher than that of ω6 PUFA, 7.20±1.21 and 1.22±0.22 mg/g of wet weight, respectively. The content of sum ω3 PUFAs which are essential for the nutrition of aquatic organisms of the higher trophic levels in the studied planarian was comparatively high

Fatty Acids of Sestonic Lipid Classes as a Tool to Study Nutrition Spectra of Rotifers and Ciliates in a Siberian Eutrophic Reservoir

Fatty acid composition of triacylglycerols (TAG) and polar lipids (PL) of seston from the Siberian Reservoir Bugach was analyzed to reveal the spectra of nutrition of micro- and mesozooplankton (protozoa and rotifers). The seasonal changes of micro- and mesozooplankton nutrition were observed. Bacteria comprised relatively constant part in feeding protozoa and rotifers during the whole vegetation season. The maximum consumption of higher plants detritus occurred at the beginning of August. Phytoplankton was consumed more intensively in spring during the rapid growth of diatoms (Stephanodiscus sp.) and from the middle to the end of June when cyanobacteria (Anabaena flos-aquae, Aphanizomenon flos-aquae, Planktothrix agardhii), dynophytes (Peridinium sp.) euglenas (Euglena proxima) and diatoms (Stephanodiscus sp.) were dominated in Bugach Reservoir. The dominant species of protozoa differed in their nutrition spectra: Holophrya sp. was feeding on diatoms in spring and bacteria in the middle of summer; Tintinidium sp. was consuming diatoms and cyanobacteria; Nassula picta was feeding on cyanobacteria

Essential PUFA in Physiology and Metabolism of Fish and Human: Functions, Needs, Sources

The long chain polyunsaturated fatty acids (PUFAs) of the omega-3 family (ω3 or n-3), namely eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), are recognized as molecules of high physiological values for animals of different taxonomic groups, including humans. N-3 PUFAs provide the normal functioning of the cardiovascular and nervous systems, immunity and metabolism in general, and their use is preventive. The medicinal properties of these PUFAs are ambiguous and are being actively discussed in the literature. The main source of EPA and DHA for human is fish. The content of n-3 PUFAs in fish depends on a number of factors and, as a result, varies widely. The needs of the different fish species in the PUFAs are not the same. Some species efficiently synthesize EPA and DHA from their precursors, while others obtain these FAs only with food. Moreover, n-3 PUFAs play important roles in the metabolism of all fishes. The catch of wild fish has reached its limit, but it does not satisfy the needs of mankind in n-3 PUFAs. To reduce the deficiency of EPA + DHA in human nutrition, there are several ways: aquaculture, biotechnology of microorganisms (single cell oils) and genetic engineering

Stable isotope fractionation of fatty acids of Daphnia fed laboratory cultures of microalgae

We tested a comparatively new method of tracing of natural food webs, compound-specific isotope analysis (CSIA) of fatty acids (FA), using laboratory culture of Daphnia galeata fed Chlorella vulgaris and Cryptomonas sp. In general, Daphnia had significantly lighter carbon stable isotope composition of most fatty acids, including essential, than those of their food, microalgae. Thus, our results did not support the pivotal premise of the FA-CSIA application for food web analysis, i.e., transmitting the isotope ‘signal’ of essential FAs to consumers from their food without any modification. Moreover, the values of isotope fractionation of particular FAs in the consumer relative to its food were not constant, but varied from 1.35‰ to 7.04‰. The different isotope fractionation (depletion) values of diverse FAs in consumer were probably caused by different processes of their synthesis, catabolism and assimilation. More work is evidently to be done for correct interpretation of results of FA-CSIA during field studies for tracing of natural food webs

Feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) using fatty acid trophic markers in seston food in two salt lakes in South Siberia (Khakasia, Russia)

During two vegetation seasons (2004–2005), we compared feeding spectra of Arctodiaptomus salinus (Calanoida, Copepoda) populations inhabiting two neighboring salt lakes, Shira and Shunet, Khakasia, Russia, using fatty acid (FA) trophic markers. Sestonic FA composition in two lakes moderately differed, whereas levels of diatom FA markers were higher in Lake Shunet and of Cyanobacteria and green algae markers in Lake Shira. In general, markers in storage lipids—triacylglycerols (TAG) of A. salinus—reflected the differences in sestonic composition of the two lakes. Nevertheless, TAG fraction was also enriched by FA trophic markers of the minor components of seston, which were selectively ingested by the animals. In Lake Shira, A. salinus had significantly higher concentrations of bacterial FA markers in TAG. In Lake Shunet, TAG of A. salinus contained significantly higher relative amounts of 18:4ω3, 18:5ω3 and C22 polyunsaturated fatty acids (PUFA), which indicated marked contribution of cryptophytes or (and) flagellates into the diet. Laboratory experiments showed feeding on Cryptomonas and sulfur purple bacteria in Lake Shunet and ciliates and colonial picoplankton in both lakes, and generally confirmed the differences in FA trophic markers in A. salinus between the lakes. The two populations of A. salinus markedly differed in levels of essential long-chain PUFA, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, although the levels of these FA in seston were quite similar between the two lakes. The higher levels of the essential ω3 PUFA in A. salinus in Lake Shunet may be an adaptive response of the animals to a vertical stratification of physico-chemical conditions and significantly higher salinity levels at the boundary of adjacent bottom layer in this lake.