Essential Fatty Acid Content Research Articles

Effects of energy and essential fatty acids content in breast milk on infant's head dimensions.

Essential fatty acids (EFA), including linoleic acid (LA) and alpha-linolenic acid (ALA), are indispensable for proper brain growth especially in the first months after birth when it develops most rapidly. Since fats, especially EFA, in breast milk are highly variable between mothers, we indirectly examined whether milk energy, LA and ALA content in breast milk affect volume and shape of the infant's head. The study encompassed 60 mothers and their healthy term-born infants between the third and sixth month of lactation. The percentage of macronutrients and dry matter in human milk samples was assessed using Fourier-transform infrared spectroscopy (FTIR), and LA and ALA concentrations in breast milk were determined using gas chromatography (GC). Infant head measurements were taken using standard anthropometric equipment and methods. LA content in breast milk was found to be positively associated with head volume in boys. Furthermore, ALA content was positively associated with the head height-to-length ratio thus with more arched head in infants irrespective of sex. No relationship was found between milk energy content in mothers' milk and infant head dimensions. This is the first study to demonstrate a relationship between EFA concentration in human milk and infant head dimensions. Given that LA and ALA in human milk are variable in women and due to the extremely rapid growth of nerve tissue in the first months of life, adequate supply of EFA in breast milk should attract the attention of public health sciences.

Serum omega-3 and omega-6 fatty acid concentrations and natural fertility.

Are serum omega-3 and omega-6 essential fatty acid concentrations associated with the probability of conceiving? There is no strong association between serum concentrations of omega-3 and omega-6 fatty acids and the probability of conceiving naturally. Omega-3 and omega-6 fatty acid serum concentrations have been shown to play an important role in reproduction in animal models, while conflicting results have been reported in human studies of infertile women. It is unknown to what extent omega fatty acid serum concentrations impact natural fertility. A nested, case-control study was conducted consisting of 200 participants [fertile: conceived within 3cycles of attempt (n= 50), subfertile: conceived within 4 and 12cycles of attempt (n= 100) and infertile: did not conceive within 12cycles of attempt (n= 50)] randomly selected from the Time to Conceive cohort, a prospective time-to-pregnancy study (2008 to 2015). In the Time to Conceive study, women aged 30-44years who were trying to conceive for <3months and had no history of infertility were recruited and followed until the end of their pregnancy or ~1year of pregnancy attempt. For this study, serum collected early in the woman's pregnancy attempt was analysed for anti-Müllerian hormone (AMH) and omega-3 and omega-6 fatty acid concentrations by liquid chromatography-mass spectrometry. The primary outcome was a positive home pregnancy test. The secondary outcomes were miscarriage and serum AMH level. A discrete-time Cox proportional hazards model was used to estimate the fecundability ratio. The odds ratios for miscarriage were calculated using logistic regression. The association between serum omega fatty acid concentrations and AMH level (natural log transformed) was analysed using Pearson's Correlation. A total of 200 women provided 1321cycles for analysis.Mean omega-3, omega-6 and omega-6:omega-3 ratios did not significantly differ between the fertile, subfertile and infertile groups. There were no associations (all fecundability ratios ~1.0) between pregnancy and individual omega-3 fatty acid concentrations, including alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid, or omega-6 fatty acids, including linoleic acid (LA), dihommo-gamma linolenic acid and arachidonic acid. There was no significant association between any individual omega fatty acid serum concentration and the age-adjusted odds of miscarriage. No association was found between any serum omega fatty acid concentration and AMH. This study is limited by the sample size. Omega-3 and omega-6 fatty acid concentrations were derived from serum provided at a single timepoint in the first cycle of enrollment. Serum concentrations may therefore not be representative of all critical timepoints in the menstrual cycle or throughout their attempts to conceive. Additionally, women enrolled in this study were 30years of age and older, and therefore the findings may not apply to younger women. These data would suggest that omega-3 and omega-6 serum levels are not associated with natural fertility or risk of miscarriage. However, due to the above-mentioned limitations, future investigation is still needed to determine whether omega-3 fatty acid supplementation may benefit women planning to conceive naturally. This study was supported by the Division of Reproductive Endocrinology and Infertility at the University of North Carolina at Chapel Hill, by the NIH/NICHD (R21 HD060229-01 and R01 HD067683-01) and, in part, by the Intramural Research Program of the National Institute of Environmental Health Sciences (Z01ES103333). Dr. Jukic received vitamin D supplements for a research study from Theralogix, Inc. The authors have no other conflicts of interest to disclose. N/A.

MTORC1 is required for the lipidation and ER‐to‐Golgi transport of prechylomicrons in Caco‐2 cells

Dietary fats are efficiently digested and absorbed by enterocytes, assembled into triacylglycerol‐rich chylomicrons and finally secreted in a multistep process. The role of mTORC1 (mechanistic target of rapamycin complex 1) in the fate of absorbed lipids, their intracellular trafficking, triacylglycerol packaging in chylomicrons by enterocytes has not been previously studied. On the basis of our previous work in hepatocytes showing that mTORC1 positively regulate VLDL production, we hypothesized that intestinal mTORC1 supports the production and secretion of chylomicrons. Lentivirus mediated shRNA technology was used to knockdown (&gt;90% down) mTORC1 signaling‐associated proteins, Raptor and TSC2, to create three Caco‐2 cell lines that exhibit basal (shScramble cells), low (shRaptor cells) or high (shTSC2 cells) mTORC1 activity. Chylomicron production was primed with the addition of 1.2 mM oleate/1.5% BSA complex to the apical side of ThinCert™ cell culture inserts. We found that knocking down Raptor disrupts triacylglycerol synthesis and chylomicron assembly. Knockdown of Raptor decreased the mRNA levels of APOB (−87%), MTTP (−94%), FASN (−76%), DGAT1 (−77%) and DGAT2 (−81%) compared with control shScramble cells. The cellular protein abundance of apoB (−89%), MTTP (−63%) and FASN (−80%), and the secretion of apoB100 (−51%), apoB48 (−66%) and triacylglycerols (−69%) were decreased compared with control shScramble cells. Rapamycin (a mTORC1 inhibitor) lowered the secretion of apoB100 and apoB48 in shScramble cells by 47% and 75%, respectively. Knockdown of Raptor decreased the gene expression of prechylomicron transport vesicle‐associated proteins VAMP7 (vesicle‐associated membrane protein 7) and SAR1B (secretion associated Ras related GTPase 1B) by 85% and 70%, respectively, compared with shScramble cells, suggesting that prechylomicron trafficking from the ER to the Golgi was repressed in the absence of Raptor. In conclusion, our studies revealed the critical role of mTORC1 in chylomicron metabolism. These findings have broad implications for the absorption of essential fatty acids and lipid‐soluble vitamins, for chylomicron retention disease, chylomicron overproduction and associated hypertriglyceridemia.Support or Funding InformationUSDA Hatch Act, USDA‐NIFA

Meat Quality of Commercial Chickens Reared in Different Production Systems: Industrial, Range and Organic

Abstract Meat is an important part of the human diet since it provides several nutrients. However, the amount of these nutrients can differ according to several factors. With this in mind, the present research was designed with the main objective of evaluating the effect of production system of broiler chickens (industrial, range and organic) on meat quality. The physicochemical, chemical and nutritional characteristics were determined in breast and drumstick meat. The organic chickens presented the lowest amounts of fat and cholesterol and the highest amounts of protein. The colour was also influenced by the production system, where organic and range chickens had the highest values of redness in both cuts (breast and drumstick). In addition, the content of essential fatty acids (C18:2n-6 and C18:3n-3) and other fatty acids with high biological importance, such as eicosapentanoic acid (EPA; C20:5n-3), docosapentanoic acid (DPA; C22:5n-3) and docosahexanoic acid (DHA; C22:6n-3) were higher in organic samples compared to industrial or range chickens. The amino acids content did not vary with the production system. With regard to mineral contents, organic chickens had the highest values of iron in drumstick and significantly lower values of magnesium in both cuts than industrial chickens. On the whole, the meat of the organic chickens showed better nutritional characteristics than those produced in range or industrial conditions.

Comparison of Physicochemical Properties and Fatty Acid Composition of Crocodile Oil (Crocodylus siamensis) Extracted by Using Various Extraction Methods

ABSTRACT Crocodile oil has been used worldwide for cosmetic and pharmaceutical purposes due to its essential fatty acid contents. This study aimed to investigate the best extraction method of crocodile oil extracted from abdominal adipose tissues (Crocodylus siamensis) by using four different ways. The results showed that the oil derived from the dry rendering method had lower levels of omega-3 alpha-linolenic acid (0.92 ± 0.049 g per 100 g sample) when compared to the oil extracted by using the other methods (1.16 ± 0.142, 0.96 ± 0.049, and 1.18 ± 0.010 g per 100 g sample, respectively). Interestingly, the crocodile oil extracted by wet cold pressing showed no bottom clouded sediment with a more transparent light-yellow color compared to the other oil samples. Moreover, the principle component analysis plots showed a highly positive relationship (r > 0.87) for docosahexaenoic acid (omega-3) and arachidonic acid (omega-6) in crocodile oil extracted using all methods. Therefore, it could be suggested that the modified wet cold pressing method could produce high-quality crocodile oil and could be adapted to further food and dietary supplement processing industries.

Fatty and amino acid profile of mealworm larvae (Tenebrio molitor L.)

The yellow mealworm (Tenebrio molitor L., Coleoptera: Tenebrionidae) is an edible insect, distributed worldwide and a convenient candidate for industrial-scale production. Mealworms could be commercially used for the substitution of conventional protein sources. In our previous study, it was found that T. molitor larvae predominantly contained crude protein (55.83%) and crude fat (25.19%), as well as low content of nitrogen-free extract (based on dry weight). Mealworm specimens were maintained in an incubator under controlled conditions in plastic containers. Insects were sieved and put into the container with boiling water and cooked for 180 seconds. Moisture content was determined as weight loss after drying of larvae. Amino acids were determined on an Agilent Technologies 1260 series HPLC system. Fatty acid composition was determined on a Thermo Scientific TRACE 1300 gas chromatograph equipped with a flame ionization detector using TR-FAME column. The results showed that the content of unsaturated fatty acid is very high, i.e. oleic acid (C18:1) formed the major lipid component in 40.83%, which was followed by linoleic acid (C18:2, omega-6 fatty acid) with 29.80% and linolenic acid (C18:3) with 1.08%. The essential amino acids are highly represented in the samples (in % dry matter). This primarily refers to isoleucine (4.12), tyrosine (3.86), phenylalanine (3.06), leucine (2.96), lysine (2.67) and methionine (1.76). The differences in essential fatty and amino acid content between our results and discussed literature data, could be the consequence of different substrates used for rearing of insects. After everything stated above, the biological value of T. molitor larvae proves that it could be suitable as animal feed.

Physico-Chemical Properties of Sacha Inchi (Plukenetia volubilis L.) Seed Oil from Vietnam

Sacha inchi (Plukenetia volubilis L.) seed oil was studied for physico-chemical characteristics and chemical composition. Through gas chromatography-flame ionization (GC-FID) process, the fatty acid composition in the oil was analyzed, revealing that the oil is rich in linoleic acid (42.62 %), linolenic acid (36.32 %) and oleic acid (11.64 %). The tocopherol level in the oil was also high (7.7 ± 0.005 mg/Kg), revealed by high-performance liquid chromatography/ultraviolet-visible detector (HPLC/UV-VIS). The physico-chemical properties of the oil were also examined, including viscosity (88-92 cP), acid value (2.05 ± 0.005 mg KOH/g), saponification content (183.5 ± 1.45 mg KOH/g) and iodine value (192.4 ± 1.55 g I2/100 g). The results also indicated that sacha inchi is a health beneficial oil due to the high contents of essential fatty acids (ω-3, ω-6 and ω-9).

Composition in fatty acids of mature milk of nursing mothers

Abstract Objectives: to determine the fatty acid composition of mature milk of nursing mothers and its distribution according to some maternal variables. Methods: this is a cross-sectional observational epidemiological study based on the eva-luation of the fatty acid profile of mature human milk. Samples of mature breast milk were taken from 106 nursing mothers, by manual milking and who were after the 5th postpartum week. The milk fat extraction was carried out by using the Bligh and Dyer method and methy-lated with 0.25 mol/L sodium methoxide in methanol diethyl ether. The fatty acid of the milk profile was determined by a Gas Chromatograph equipped with a flame ionization detector. Results: among the saturated fatty acids, the highest values were observed for palmitic (C16:0), stearic (C18:0), myristic (C14:0) and lauric (C12:0) fatty acids, respectively. Among the monounsaturated fatty acids, there was a higher contribution of oleic (C18:1) and palmi-toleic (C16:1) fatty acids, respectively. The total essential fatty acids (linoleic and α-linolenic) was 14.94%. Conclusions: a low content of essential fatty acids in the breast milk of the nursing mothers was observed in the present study, which are important for infant growth and deve-lopment. We suggest the need to implement nutrition education strategies aimed for pregnant women and nursing mothers who should be advised to eat healthier foods.

Renewable sources: applications in personal care formulations.

A global tendency for products considered environmentally sustainable, and ecologically obtained led the industry related to personal care formulations to fund the research and the development of personal care/cosmetics containing ingredients from natural resources. Furthermore, consumers are aware of environmental and sustainability issueans, thus not harming the environment represents a key consideration when developing a new cosmetic ingredient. In this study we review some examples of active ingredients or raw materials used in cosmetics/personal care/biomedical products that are coming from either through biotechnological systems, or as byproducts of several industries. A skin formulation containing biosynthetic actives, prepared by us and the study regarding its dermocosmetic properties are also described. The need for the standardization processes, the safety assessment tools, the improvement of the exploitation methods of these renewable sources in order the production to be ecologically and economically better are also discussed.

Complementary information from fatty acid and nutrient stoichiometry data improve stream food web analyses

Our study characterized the food web of a shaded stream to investigate consumer food choices and food source quality. We measured fatty acids (FA) and elemental carbon (C), nitrogen (N), and phosphorus (P) of autochthonous and allochthonous resources and macroinvertebrates (Hydropsyche sp., Ephemerella sp., Rhyacophila sp., and crayfish-Cambaridae). We examined trophic links using FAs and identified food source quality based on essential fatty acids (EFAs) and elemental nutrients. Autochthonous food sources had greater EFA content (20:5ω3 in periphyton, 20:4ω6 in bryophyte Hygrohypnum) than terrestrial matter. FAs confirmed the grazing nature of Ephemerella. Periphyton may release this invertebrate from N and P limitation, and FA biochemical constraints. Limitation by elemental nutrients, but not FAs, may exist for Hydropsyche if feeding solely on transported matter. Crayfish FA signature suggests consumption of the bryophyte Hygrohypnum as well as terrestrial matter. Our data demonstrate that autochthonous sources are crucial for many invertebrates in shaded streams, despite limited light availability. However, detrital food sources can also be important and their contribution to stream food webs should not be overlooked. Our study highlights the importance of measuring nutrient and biochemical constraints in order to understand factors driving secondary production in streams.

Effect of drying methods on bioactive compounds, nutritional, antioxidant, and antidiabetic potential of brown alga Durvillaea antarctica

The effects of vacuum, solar, convective, infrared, and freeze drying (VD, SD, CD, IRD, FD) on Durvillaea antarctica were evaluated in terms of nutritional composition, color, bioactive components, and antioxidant and antidiabetic activities. Nutritional composition of the dried seaweeds scarcely varied, while a tendency to lose the reddish tone occurred. CD-seaweed had highest phytochemical and vitamin contents, while FD-samples showed best retention of pigments. Both samples also exhibited the strongest antioxidant and antidiabetic activities. The highest essential amino acids and polyunsaturated fatty acids contents were found in IRD- and SD-samples, respectively. In general, FD and CD were proved to be viable drying options for D. antarctica.

Population structure, life cycle, and trophic niche of the glacial relict amphipod, Gammaracanthus lacustris, in a large boreal lake

Abstract Ecology of the glacial relict macrocrustacean Gammaracanthus lacustris, a rare inhabitant of deep Fennoscandian lakes, is poorly understood. We studied the life cycle and trophic position of this cold‐stenothermic amphipod in Lake Paasivesi, eastern Finland. The study is based on intensive sampling and analyses of fatty acid composition as well as stable carbon (δ13C) and nitrogen (δ15N) isotope ratios. Both day and night, the G. lacustris population occurred at depths below 25 m at temperatures &lt;8°C, and the density increased towards the bottom of the lake, where it was 0.4–0.6 individuals/m3. Gammaracanthus lacustris was observed to reach a length of &gt;40 mm and live up to 4 years. The oldest and the largest individuals and females seemed to favour the deepest zones. In October, almost 100% of females with length at least 25 mm (i.e. females presumably at least 1‐year‐old) had an embryo sack with 20–200 eggs or embryos—the larger the female, the more young it had. The developing eggs of G. lacustris had a very high fatty acid content, indicating that the females invest heavily on provisioning their young. Furthermore, the fatty acid composition differed among life stages, and in particular the eggs had a higher proportion of eicosapentaenoic acid than juveniles or adults. The stable δ13C and δ15N isotope ratios and fatty acid biomarkers of the food web, together with visual observations, indicate that G. lacustris is a carnivore that feeds mainly on zooplankton and other relict macrocrustaceans. Due to its high content of essential polyunsaturated fatty acids, G. lacustris is a valuable prey for fish and other predators in the food web. However, as a glacial relict with strict habitat requirements the species is vulnerable to global warming and local environmental changes. These facts should be considered in the management of lakes and their catchments.

Browning reduces the availability—but not the transfer—of essential fatty acids in temperate lakes

Abstract Atmospheric changes are leading to the browning of northern lakes (i.e. increases in catchment‐derived dissolved organic matter [DOM]), consequently altering phytoplankton biomass and community composition. We hypothesised that lake browning and the concurrent increase in nutrients drive a shift towards greater cyanobacteria biomass. We further hypothesised that, as a consequence of this shift in phytoplankton, the content of ω‐3 (n‐3) essential fatty acids (EFA) in seston would decline, affecting the subsequent transfer of EFA to consumers across the plant–animal interface in pelagic regions of lakes. We tested these hypotheses in the epilimnion of 30 temperate lakes in Ontario (Canada), representing a gradient of lake browning, with dissolved organic carbon (DOC) ranging from 2 to 10 mg/L and total phosphorus ranging from 6.0 to 48.5 μg/L. In each of these lakes, the concentration and composition of DOM, the biomass of phytoplankton and cyanobacteria, and the EFA content of seston, cladocerans, and copepods were measured. An increase in aromatic DOM was associated with increased phytoplankton and cyanobacteria biomass. Due to the lower content of the EFA eicosapentaenoic acid (EPA; 20:5n‐3) and docosahexaenoic acid (DHA; 22:6n‐3) in cyanobacteria, this increase in phytoplankton biomass was associated with a decline in EPA and DHA content in lake seston. However, there was no significant change in EFA content of cladocerans and copepods. This homeostatic (diet‐independent) EFA composition in zooplankton suggested that, as the phytoplankton community shifted towards more cyanobacteria with lower EFA content, the cladocerans and copepods may have met their nutritional requirements by relying on alternative food sources (e.g. heterotrophic ciliates and flagellates) capable of either trophically upgrading phytoplankton‐produced EPA and DHA, or synthesising EPA and DHA de novo. Results from this study indicate that increasing DOC from low (2 mg DOC/L) to moderate levels (15 mg DOC/L) may increase the importance of the microbial pathway in the trophic transfer of EPA and DHA from basal resources to zooplankton. However, this supplementary transfer of EFA through the microbial food web may not sustain high EPA and DHA levels in zooplankton when lake browning starts to limit primary production (&gt;15 mg DOC/L).

Comparative transcriptome analysis of cultivated and wild seeds of Salvia hispanica (chia)

Salvia hispanica (chia) constituted an important crop for pre-Columbian civilizations and is considered a superfood for its rich content of essential fatty acids and proteins. In this study, we performed the first comprehensive comparative transcriptome analysis between seeds from cultivated varieties and from accessions collected from native wild populations in Mexico. From the 69,873 annotated transcripts assembled de novo, enriched functional categories and pathways revealed that the lipid metabolism was one of the most activated processes. Expression changes were detected among wild and cultivated groups and among growth conditions in transcripts responsible for triacylglycerol and fatty acid synthesis and degradation. We also quantified storage protein fractions that revealed variation concerning nutraceutical proteins such as albumin and glutelin. Genetic diversity estimated with 23,641 single nucleotide polymorphisms (SNPs) revealed that most of the variation remains in the wild populations, and that a wild-type cultivated variety is genetically related to wild accessions. Additionally, we reported 202 simple sequence repeat (SSRs) markers useful for population genetic studies. Overall, we provided transcript variation that can be used for breeding programs to further develop chia varieties with enhanced nutraceutical traits and tools to explore the genetic diversity and history of this rediscovered plant.

Paternal effects on fatty acid composition of tree peony seed oil

Tree peony seed is a novel resource of edible oil with high α-linolenic acid (ALA) content (> 40%). To assess whether pollen sources influence the seed oil quality, fatty acids of hybrids from the combination of Paeonia ostii ‘Feng Dan’ and 30 cultivars were monitored and evaluated in this study. The results indicated that the content of total fatty acid and ALA ranged from 21.23 to 29.68% and from 46.75 to 64.71%, respectively. Thirty combinations were classified into four clusters. Cluster IV including ‘Tian Xiang Jin’, ‘Zhou Ban Hong’, ‘Xiang Yang Hong’ and ‘Yu Jie’ were good pollen donors because their hybrid seeds possessed the highest contents of ALA and unsaturated fatty acids, with an average of 159.39 mg g−1 and 263.76 mg g−1, respectively. This study provides a good base for breeding new cultivars with excellent edible oil and essential fatty acid contents for food.

Effect of ocean acidification on the nutritional quality of marine phytoplankton for copepod reproduction.

Phytoplankton are the oceans’ principal source of polyunsaturated fatty acids that support the growth and reproduction of consumers such as copepods. Previous studies have demonstrated ocean acidification (OA) can change the availability of polyunsaturated fatty acids to consumer diets which may affect consumer reproduction. Two laboratory experiments were conducted to examine the effects of feeding high-pCO2-reared phytoplankton on copepod egg production, hatching success, and naupliar survival. Marine phytoplankton Rhodomonas salina, Skeletonema marinoi, Prorocentrum micans, and Isochrysis galbana were exponentially grown in semi-continuous cultures at present (control) (400 ppm CO2, pH~8.1) and future (1,000 ppm CO2, pH~7.8) conditions and provided to Acartia tonsa copepods over 4 consecutive days as either nitrogen-limited (Exp. I) or nitrogen-depleted (Exp. II) mixed assemblage of phytoplankton. The composition of FAs in the phytoplankton diet was affected by pCO2 concentration and nitrogen deficiency; the ratio of essential fatty acids to total polyunsaturated fatty acids decreased in phytoplankton grown under high pCO2 and the mass of total fatty acids increased under nitrogen depletion. Additionally, total concentrations of essential fatty acids and polyunsaturated fatty acids in the diet mixtures were less under the high-pCO2 compared to the control-pCO2 treatments. Median egg production, hatching success, and naupliar survival were 48–52%, 4–87%, and 9–100% lower, respectively, in females fed high-pCO2 than females fed low-pCO2 phytoplankton, but this decrease in reproductive success was less severe when fed N-depleted, but fatty acid-rich cells. This study demonstrates that the effects of OA on the nutritional quality of phytoplankton (i.e., their cellular fatty acid composition and quota) were modified by the level of nitrogen deficiency and the resulting negative reproductive response of marine primary consumers.

Ценность мяса якутской лошади для продления жизни человека на Севере

&lt;span&gt; В статье рассмотрены вопросы долгожительства населения северного малонаселенного региона. Отмечен сдвиг гендерных и территориальных показателей за счет активной миграции пожилых из сельской местности в городские поселения. Проанализированы средняя ожидаемая продолжительность жизни лиц, достигших пенсионного возраста, а также увеличение вероятности дожить до пожилого возраста, выявившие сохранение гендерных различий. Обоснован вывод о том, что одним из факторов долголетия якутян является употребление традиционных мясных продуктов из молодой конины (жеребятины). Подчеркнуто, что источником формирования уникального состава мяса якутской лошади, влияющим на продление жизни, являются замороженные естественным холодом корма (криокорм) с высоким содержанием незаменимых жирных кислот. Представлены экономические предпосылки применения зеленого криокорма как основы повышения питательной ценности мяса якутской лошади.&lt;/span&gt;

A COMPARATIVE STUDY TO EVALUATE THREE IMPORTANT PLANT OILS FOUND IN EGYPT

Oils are a very important component in different diets, which makes it important for researchers to constantly search for a variety of sources of these oils that are acceptable to consumers on the one hand and are characterized by high nutritional value and storage properties on the other hand. This study was carried out to determine physical properties of linseed, soybean and walnut oils (Refractive index, color, specific gravity) as well as chemical properties (Acid value, saponification value, ester value, iodine value and peroxide value). The percentage of unsaponifiable matter and stability induction period at 100◦C were also estimated. To determine the nutritional value of these oils, both their fatty acid content (assessed by the gas chromatography apparatus) and sterol content (assessed by GC-MS). Physical properties of linseed, soybean or walnut oils showed that; refractive index were 1.48, 1.47 and 1.84, respectively, while color (red) intensity were 9.5, 3.5 and 2.6, respectively and specific gravity were 0.93, 0.92 and 0.92, respectively. On the other hand, chemical properties of linseed, soybean or walnut oils showed that; saponification value were 192, 191 and 190.73(mg KOH/g oil), respectively, while acid value were 0.87, 0.27 and 0.79 (mg KOH/g oil), respectively, and iodine value were 175, 128 and 145 (g I2/100 g oil), respectively, finally, peroxide value were 1.95, 0.77 and 1.31 (Meq oxygen/Kg), respectively. Alpha linolenic acid was the major fatty acid in linseed oil (60.21%), while linoleic acid was the main fatty acid in both, soybean oil (52.83%) and walnut oil (61.85%). β-sitosterol was the main sterol in the linseed, soybean or walnut oils (54.72, 40.13 and 76.85%, respectively). As shown by the results, the three studied oils showed high content of essential fatty acids, (both omega-3 and omega-6), making them promising oils to support diets with essential fatty acids.

Preliminary estimation of the export of omega-3 polyunsaturated fatty acids from aquatic to terrestrial ecosystems in biomes via emergent insects

Some terrestrial consumers may be limited by food quality, namely by contents of essential polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (20:5n−3, EPA) and docosahexaenoic acid (22:6n−3, DHA) in their food. Since EPA and DHA are mainly produced in aquatic ecosystems, for future estimating of the potential limitation by food quality in global scale, the water-land fluxes of these PUFA with the biomass of emergent aquatic insects in several biomes were calculated. The water /land area ratios for each biome were calculated by dividing the water area of each biome by its terrestrial area. Data on insect emergence from water bodies (g of dry mass m−2 year−1), were summarized and averaged for each biome. From available data, EPA and DHA contents (mg g−1dry mass), in the biomass of emergent aquatic insects were calculated first so that annual fluxes of PUFA to land area via aquatic insect emergence could be estimated for each biome. PUFA fluxes occurred between the biomes, ranging from 0.04 to 4.39 mg m−2 year−1. In this study, the aquatic PUFA supply to land area appeared to be significantly lower than estimated earlier. This suggests that terrestrial consumers may experience food quality limitations mediated by shortage of PUFA compounds.

Terrestrial organic matter increases zooplankton methylmercury accumulation in a brown-water boreal lake

Increases in terrestrial organic matter (tOM) transport from catchments to boreal lakes can affect methylmercury (MeHg) accumulation in aquatic biota both directly by increasing concentrations of aqueous MeHg, and indirectly through effects on MeHg bioavailability and on energy pathways in the lower food web. We carried out a detailed seasonal study of water chemistry, zooplankton diet, and MeHg accumulation in zooplankton in two lakes with contrasting tOM concentrations. Between-lake differences explained 51% of the variability in our water chemistry data, with no observed effect of season or sampling depth, contrary to our expectations. Higher tOM was correlated with higher aqueous Hg concentrations, lower areal pelagic primary productivity, and an increased contribution of terrestrial particles to pelagic particulate organic matter. Based on dietary marker analysis (δ13C, δ15N, and fatty acid [FA] composition), zooplankton diet was strongly linked to feeding mechanism, with dietary reliance on phytoplankton highest in the selective-feeding calanoid copepods, and lowest in filter feeding cladocerans. Zooplankton dietary reliance on phytoplankton and their concentrations of high-quality lipids, including polyunsaturated fatty acids, were higher in the clear-water lake than in the brown-water lake, where bacterial and terrestrial food sources were more prevalent. MeHg was highest in zooplankton from the brown-water lake, with highest concentrations in the 200–500 μm zooplankton size fraction for both lakes. Contrary to our expectations, there was no effect of season on zooplankton dietary markers or MeHg. Our results suggest that, overall, higher tOM results in higher MeHg concentrations in water and zooplankton, and reduces zooplankton dietary reliance on phytoplankton. Increased tOM thus leads to a decrease in the nutritional quality of zooplankton (i.e. higher MeHg concentrations, and lower concentrations of essential fatty acids), which may cascade up the food web with negative implications for higher trophic levels.