Transfer Of Essential Fatty Acids Research Articles

Basal resource quality and energy sources in three habitats of a lowland river ecosystem

AbstractUnderstanding energy flow through ecosystems and among sub‐habitats is critical for understanding patterns of biodiversity and ecosystem function. It can also be of considerable applied interest in situations where managing for connectivity among habitats is important for restoring degraded ecosystems. Here, we describe patterns of basal resource quality and identify primary basal energy sources in three habitats—river channels, anabranches and wetlands—of a lowland river floodplain in the Murray River catchment, Australia during a period of disconnected surface flow. We used a combination of stable isotope and fatty acid analyses to determine which basal resources were assimilated by the backswimmer Anisops thienemanni and the Eastern mosquitofish Gambusia holbrooki and assessed food quality across the three habitats. Seston was a primary basal resource for both animals in all three habitats, but was of higher quality within floodplain habitats than in the river channel. Although floodplain seston contained higher concentrations of essential fatty acids, fatty acid profiles of animals from different habitats remained similar. Our research suggests that inundation of floodplains and subsequent reconnection to the river could be valuable to afford riverine animals the opportunity to access high quality resources, but highlights a need to quantitatively assess the transfer of essential fatty acids between trophic levels to determine how much riverine animals are in fact limited by poorer quality food resources. We demonstrate the importance of estimating the quality of organic matter fluxes into food webs, and the potential role of targeted environmental flows to re‐establish high quality energy pathways in riverine ecosystems.

Ontogeny of Sex-Related Differences in Foetal Developmental Features, Lipid Availability and Fatty Acid Composition.

Sex-related differences in lipid availability and fatty acid composition during swine foetal development were investigated. Plasma cholesterol and triglyceride concentrations in the mother were strongly related to the adequacy or inadequacy of foetal development and concomitant activation of protective growth in some organs (brain, heart, liver and spleen). Cholesterol and triglyceride availability was similar in male and female offspring, but female foetuses showed evidence of higher placental transfer of essential fatty acids and synthesis of non-essential fatty acids in muscle and liver. These sex-related differences affected primarily the neutral lipid fraction (triglycerides), which may lead to sex-related postnatal differences in energy partitioning. These results illustrate the strong influence of the maternal lipid profile on foetal development and homeorhesis, and they confirm and extend previous reports that female offspring show better adaptive responses to maternal malnutrition than male offspring. These findings may help guide dietary interventions to ensure adequate fatty acid availability for postnatal development.

Lake eutrophication and brownification downgrade availability and transfer of essential fatty acids for human consumption

Fish are an important source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for birds, mammals and humans. In aquatic food webs, these highly unsaturated fatty acids (HUFA) are essential for many physiological processes and mainly synthetized by distinct phytoplankton taxa. Consumers at different trophic levels obtain essential fatty acids from their diet because they cannot produce these sufficiently de novo. Here, we evaluated how the increase in phosphorus concentration (eutrophication) or terrestrial organic matter inputs (brownification) change EPA and DHA content in the phytoplankton. Then, we evaluated whether these changes can be seen in the EPA and DHA content of piscivorous European perch (Perca fluviatilis), which is a widely distributed species and commonly consumed by humans. Data from 713 lakes showed statistically significant differences in the abundance of EPA- and DHA-synthesizing phytoplankton as well as in the concentrations and content of these essential fatty acids among oligo-mesotrophic, eutrophic and dystrophic lakes. The EPA and DHA content of phytoplankton biomass (mgHUFAg−1) was significantly lower in the eutrophic lakes than in the oligo-mesotrophic or dystrophic lakes. We found a strong significant correlation between the DHA content in the muscle of piscivorous perch and phytoplankton DHA content (r=0.85) as well with the contribution of DHA-synthesizing phytoplankton taxa (r=0.83). Among all DHA-synthesizing phytoplankton this correlation was the strongest with the dinoflagellates (r=0.74) and chrysophytes (r=0.70). Accordingly, the EPA+DHA content of perch muscle decreased with increasing total phosphorus (r2=0.80) and dissolved organic carbon concentration (r2=0.83) in the lakes. Our results suggest that although eutrophication generally increase biomass production across different trophic levels, the high proportion of low-quality primary producers reduce EPA and DHA content in the food web up to predatory fish. Ultimately, it seems that lake eutrophication and brownification decrease the nutritional quality of fish for human consumers.

Ocean acidification reduces transfer of essential biomolecules in a natural plankton community.

Ocean acidification (OA), a process of increasing seawater acidity caused by the uptake of anthropogenic carbon dioxide (CO2) by the ocean, is expected to change surface ocean pH to levels unprecedented for millions of years, affecting marine food web structures and trophic interactions. Using an in situ mesocosm approach we investigated effects of OA on community composition and trophic transfer of essential fatty acids (FA) in a natural plankton assemblage. Elevated pCO2 favored the smallest phytoplankton size class in terms of biomass, primarily picoeukaryotes, at the expense of chlorophyta and haptophyta in the nano-plankton size range. This shift in community composition and size structure was accompanied by a decline in the proportion of polyunsaturated FA (PUFA) to total FA content in the nano- and picophytoplankton size fractions. This decline was mirrored in a continuing reduction in the relative PUFA content of the dominant copepod, Calanus finmarchicus, which primarily fed on the nano-size class. Our results demonstrate that a shift in phytoplankton community composition and biochemical composition in response to rising CO2 can affect the transfer of essential compounds to higher trophic levels, which rely on their prey as a source for essential macromolecules.

Transfer of omega‐3 fatty acids across the blood–brain barrier after dietary supplementation with a docosahexaenoic acid‐rich omega‐3 fatty acid preparation in patients with Alzheimer's disease: the OmegAD study

Little is known about the transfer of essential fatty acids (FAs) across the human blood-brain barrier (BBB) in adulthood. In this study, we investigated whether oral supplementation with omega-3 (n-3) FAs would change the FA profile of the cerebrospinal fluid (CSF). A total of 33 patients (18 receiving the n-3 FA supplement and 15 receiving placebo) were included in the study. These patients were participants in the double-blind, placebo-controlled randomized OmegAD study in which 204 patients with mild Alzheimer's disease (AD) received 2.3 g n-3 FA [high in docosahexaenoic acid (DHA)] or placebo daily for 6 months. CSF FA levels were related to changes in plasma FA and to CSF biomarkers of AD and inflammation. At 6 months, the n-3 FA supplement group displayed significant increases in CSF (and plasma) eicosapentaenoic acid (EPA), DHA and total n-3 FA levels (P < 0.01), whereas no changes were observed in the placebo group. Changes in CSF and plasma levels of EPA and n-3 docosapentaenoic acid were strongly correlated, in contrast to those of DHA. Changes in DHA levels in CSF were inversely correlated with CSF levels of total and phosphorylated tau, and directly correlated with soluble interleukin-1 receptor type II. Thus, the more DHA increased in CSF, the greater the change in CSF AD/inflammatory biomarkers. Oral supplementation with n-3 FAs conferred changes in the n-3 FA profile in CSF, suggesting transfer of these FAs across the BBB in adults.

Effects of a DHA rich n‐3 fatty acid supplementation on fatty acid composition in cerebrospinal fluid in Alzheimer disease. The OmegAD study

BackgroundLittle is known about the transfer of essential fatty acids (FA) across the human blood‐brain barrier (BBB) in adulthood.ObjectiveWill oral supplementation for 6 mo with omega‐3 fatty acids (n‐3 FA), high in DHA, change the FA profile in cerebrospinal fluid (CSF) in patients with Alzheimer's disease (AD)?MethodsFA in CSF were analyzed by gas chromatography and mass spectrometry in 33 patients; 18 received n‐3 FA and 15 placebo. Participants were part of the OmegAD Study, where 204 patients with mild AD received 2.3 g n‐3 FA daily or placebo for 6 mo in a randomized fashion. Correlation analyses were made with plasma FA, CSF markers of AD and of inflammation.ResultsAt 6 mo a significant increase in CSF (and plasma) EPA, DHA and total n‐3 levels were noted in the n‐3 FA group, whereas no changes were observed in the placebo group. Changes of CSF DHA levels correlated significantly to changes of total and phosphorylated Tau and soluble IL‐1RII in CSF, i.e. the more the FA increased, the more the AD biomarkers decreased.SummaryN‐3 FA supplementation conferred discrete changes of n‐3 FA in CSF, suggesting transfer over the adult BBB. Significant correlations between CSF n‐3 FA and CSF AD markers suggest possible relationships.

Effects of di-(2-ethylhexyl)-phthalate and its metabolites on the lipid profiling in rat HRP-1 trophoblast cells

The highly directional maternal-to-fetal transfer of essential fatty acids (EFAs) across the placenta plays a critical role in guiding proper fetal development. Exposure to xenobiotics that may alter the fetal supply of EFAs/lipids could lead to fetal toxicity. Since the placenta is the first fetal arising organ that regulates fetal fatty acid homeostasis, the fatty acid/lipid composition in the placenta may serve as an indicator of fetal composition. In this study, we investigated the effects of the peroxisome proliferator chemical di-(2-ethylhexyl)-phthalate (DEHP), a widely used plasticizer and ubiquitous environmental contaminant, and its selective metabolites, mono-(2-ethylhexyl)-phthalate (MEHP) and 2-ethylhexanoic acid (EHA) on the lipid metabolome in a rat HRP-1 trophoblast model. The concentrations of ten lipid classes (cholesterol esters, diacylglycerol, triacylglycerides, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, lysophosphatidylcholine, cardiolipin, and sphingomyelin) were determined, as well as the individual fatty acid compositions, especially the omega-3 and omega-6 family of EFAs. The level of each lipid class was significantly increased upon exposure to the agents, with MEHP and EHA generally showing higher increases than DEHP. The same trends were observed in comparing the fatty acid compositions. For example, the omega-3/omega-6 fatty acids ratio did not change, although the levels of omega-3 and omega-6 fatty acids were significantly elevated upon exposure. These results suggest that DEHP and its metabolites can alter lipid metabolome in a rat placental cell line, implying that these compounds may contribute to aberrant placental EFA/lipid homeostasis caused by peroxisome proliferation, and potentially result in abnormal fetal development.

Essential fatty acid composition of plasma phospholipids and birth weight: a study in term neonates

Essential fatty acids (EFAs) in umbilical cord blood samples are associated with attained birth weight in premature infants and low-birth-weight neonates. The objective was to investigate relations between the EFA composition of cord and maternal plasma phospholipids and birth weight in term neonates. This was a cross-sectional study in 627 singletons born at term. The plasma phospholipid EFA composition of the mothers was determined by gas-liquid chromatography at study entry (< or = 16 wk gestation), at delivery, and in cord plasma at birth. Birth weights were normalized to SD scores. In cord plasma, the dihomo-gamma-linolenic acid concentration was positively related to weight SD scores. Both arachidonic acid (AA) and docosahexaenoic acid (DHA) were negatively related to weight SD scores. EFA-status indicators showed similar negative associations, whereas eicosatrienoic acid concentrations were positively related to neonatal size. In maternal plasma, proportions of n-3 long-chain polyenes (LCPs) and n-6 LCPs decreased during pregnancy. Larger decreases in AA, DHA, n-3 LCP, and n-6 LCP fractions were observed in mothers of heavier babies. Higher concentrations of LCPs in maternal plasma were, however, not related to a larger infant size at birth. A lower biochemical EFA status in umbilical cord plasma and a larger decrease in maternal plasma LCP concentrations are associated with a higher weight-for-gestational-age at birth in term neonates. Our findings do not support a growth-stimulating effect of AA or DHA; however, they do suggest that maternal-to-fetal transfer of EFAs might be a limiting factor in determining neonatal EFA status.

Adaptation of maternal lipid flux to pregnancy: research needs.

Adaptations of maternal lipid metabolism during pregnancy are directed toward both the needs of the fetus for lipid substrates and maternal requirements for lipid stores serving as energy reserves for lactation. The mechanisms are poorly understood, but must be elucidated before new dietary recommendations can be made about dietary supplementation with long-chain polyunsaturated fatty acids (LC-PUFA). Problems of high priority for research are: (1) Fetal requirements for specific fatty acids, including essential fatty acids (EFA) and long-chain polyunsaturated fatty acids (LC-PUFA); (2) The mechanisms for transfer of fatty acids across the placenta; (3) The role of very low density lipoproteins (VLDL) in transfer of EFA and LC-PUFA from the maternal liver to the placenta; (4) Adjustments of fatty acid metabolism in the maternal liver during pregnancy; and (5) The effect of dietary LC-PUFA on maternal fatty acid metabolism during pregnancy.

A high-density-lipoprotein receptor appears to mediate the transfer of essential fatty acids from high-density lipoprotein to lymphocytes.

It has been shown previously that a specific high-density lipoprotein (HDL) receptor exists on human lymphocytes that recognizes apoprotein (apo) A1 as its ligand, and may be responsible for utilization of HDL lipids to respond optimally to mitogenic stimulation when cultured in serum-free medium supplemented with HDL. To clarify further the relationship between various HDL lipids used by lymphocytes and HDL receptor activity, the lipid composition of the cells and the regulation of HDL and low-density lipoprotein (LDL) receptors on freshly isolated lymphocytes and mitogen-activated T-blasts after treatment with lipoproteins, liposomes or fatty acids were investigated. Our data show that the linear increase in cell proliferation correlates with the presence of HDL in fatty-acid-free culture medium in the concentration range of HDL receptor saturation. Decreased binding/uptake of dioctadecylindocarbocyanine (DiI)-fluorescence-labelled HDL by freshly isolated lymphocytes was observed in the presence of unlabelled HDL in 4-day culture, whereas T-blast binding/uptake was down-regulated by preincubation not only with HDL but also with LDL. T-blasts pretreated with HDL showed increased cellular contents of phosphatidylcholine, oleic acid (C18:1,n-9) and linoleic acid (C18:2,n-6), which are essential for optimal proliferation of mitogen-stimulated lymphocytes. Furthermore, DiI-HDL binding on lymphocytes was down-regulated by up to 20% (resting T cells) and 50% (T-blasts) when cultured in the presence of apoA1-phosphatidylcholine liposomes (T-blasts only), oleic acid or linoleic acid, but not by stearic acid (C18:0). The results indicate that HDL provide lymphocytes with essential fatty acids, which in turn regulate HDL receptor activity.

Placental transfer of essential fatty acids in humans: venous-arterial difference for docosahexaenoic acid in fetal umbilical erythrocytes.

Docosahexaenoic acid [22:6(n-3); 22:6(4,-7,10,13,16,19) (DHA)] is required in quantity by the developing nervous system of the fetus. This need could be met through synthesis of DHA from linolenic acid in the fetus or through placental transfer of DHA directly. To study the placental transfer of n-3 fatty acids, we obtained umbilical and maternal blood samples from 26 healthy women and infants at parturition and measured the fatty acid composition and content of both plasma and erythrocytes. A striking finding was a considerable venous-arterial difference for DHA in the umbilical erythrocytes as a proportion of total fatty acids and in absolute concentration. This difference of 2.2 micrograms per billion erythrocytes was 6 times larger than the difference in fetal plasma, when the plasma and erythrocyte concentrations were normalized to whole blood. Most other erythrocyte fatty acids showed a similar trend. In umbilical plasma, significant venous-arterial differences were found for 16:0, 16:1, 18:2, and total saturated fatty acids. There was a similar trend for most other plasma fatty acids. Compared with maternal blood, fetal plasma and erythrocytes had higher levels of 20:4 and DHA and lower levels of 18:2 and 18:3(n - 3) fatty acids as a proportion of total fatty acids. These results suggest that erythrocytes play a major role in the necessary transport of the essential fatty acid DHA into the fetus.

Lipid incorporation of linoleic and arachidonic acids by peripheral blood leucocytes in human pregnancy at term

Peripheral blood leucocytes from pregnant women at term and from non-pregnant controls were incubated for 1h in the presence of 14C-linoleic acid and 3H-arachidonic acid. After 2h, a higher percentage of both 14C-linoleic acid and 3H-arachidonic acid were incorporated from the medium into the leucocytes from pregnant women than controls. In leucocytes from pregnant women, significantly more 14C-linoleic acid and 3H-arachidonic acid remained as the intracellular free fatty acid and less of both fatty acids were incorporated into phosphatidylcholine. These changes may be important for the transfer of essential fatty acids to the fetus.