Assimilation Of Fatty Acids Research Articles

Honey bee protein and lipid nutrition in avocado and blueberry agroecosystems with conventional and organic management

Honey bees play a crucial role in agricultural production. Farmers rely on commercial bee pollination to obtain optimal yields, and beekeepers on the income from pollination fees. However, commercial pollination confronts honey bees with pests and pathogens, pesticides, and low-quality food, which in many cases do not fulfill the minimal nutritional requirements of honey bees. In this work, we evaluated honey bee nutrition in avocado and blueberry plantations under organic and conventional management, by assessing the nutritional quality of pollen and bee bread based on their protein, fatty acid, and microbial content, and by analyzing honey bee health through the examination of abdominal fatty acid profiles and head protein content. Low protein content in honey bee hemolymph was evident under conventional management. Regardless of management, avocado pollen showed higher protein levels, which were translated into higher honey bee head protein levels being 60% higher in avocado under conventional management when compared to blueberry under the same management. However, higher protein levels in avocado pollen were also translated into lower amounts of fatty acids in bee bread and in honey bee fat. In particular, the total amount of fatty acids in bee bread from conventional management was 50% lower than that from organic management. Additionally, the saturated fatty acids in conventional blueberries were lower compared to that of organic blueberries. Crop system and bee bread microbial composition altered the plant-honey bee nutrition cascades transforming pollen to bee bread with increased amount of saturated, unsaturated, and total fatty acids. In conclusion, both crop species and crop systems determine honey bee nutrition through alterations in the pollen transformation, affecting protein and fatty acid assimilation.

The Bbotf1 Zn(Ⅱ)2Cys6 transcription factor contributes to antioxidant response, fatty acid assimilation, peroxisome proliferation and infection cycles in insect pathogenic fungus Beauveria bassiana

The abilities to withstand oxidation and assimilate fatty acids are critical for successful infection by many pathogenic fungi. Here, we characterized a Zn(II)2Cys6 transcription factor Bbotf1 in the insect pathogenic fungus Beauveria bassiana, which links oxidative response and fatty acid assimilation via regulating peroxisome proliferation. The null mutant ΔBbotf1 showed impaired resistance to oxidants, accompanied by decreased activities of antioxidant enzymes including CATs, PODs and SODs, and down-regulated expression of many antioxidation-associated genes under oxidative stress condition. Meanwhile, Bbotf1 acts as an activator to regulate fatty acid assimilation, lipid and iron homeostasis as well as peroxisome proliferation and localization, and the expressions of some critical genes related to glyoxylate cycle and peroxins were down-regulated in ΔBbotf1 in presence of oleic acid. In addition, ΔBbotf1 was more sensitive to osmotic stressors, CFW, SDS and LDS. Insect bioassays revealed that insignificant changes in virulence were seen between the null mutant and parent strain when conidia produced on CZP plates were used for topical application. However, propagules recovered from cadavers killed by ΔBbotf1 exhibited impaired virulence as compared with counterparts of the parent strain. These data offer a novel insight into fine-tuned aspects of Bbotf1 concerning multi-stress responses, lipid catabolism and infection cycles.

Survival, Growth Performance, and Hepatic Antioxidant and Lipid Profiles in Infected Rainbow Trout (Oncorhynchus mykiss) Fed a Diet Supplemented with Dihydroquercetin and Arabinogalactan.

Natural feed supplements have been shown to improve fish viability, health, and growth, and the ability to withstand multiple stressors related to intensive cultivation. We assumed that a dietary mix of plant-origin substances, such as dihydroquercetin, a flavonoid with antioxidative, anti-inflammatory, and antimicrobial properties, and arabinogalactan, a polysaccharide with immunomodulating activity, would promote fish stress resistance and expected it to have a protective effect against infectious diseases. Farmed rainbow trout fish, Oncorhynchus mykiss, received either a standard diet or a diet supplemented with 25 mg/kg of dihydroquercetin and 50 mg/kg of arabinogalactan during a feeding season, from June to November. The fish in the control and experimental groups were sampled twice a month (eight samplings in total) for growth variable estimations and tissue sampling. The hepatic antioxidant status was assessed via the quantification of molecular antioxidants, such as reduced glutathione and alpha-tocopherol rates, as well as the enzyme activity rates of peroxidase, catalase, and glutathione-S-transferase. The lipid and fatty acid compositions of the feed and fish liver were analyzed using thin-layer and high-performance liquid chromatography. The viability, size, and biochemical indices of the fish responded to the growth physiology, environmental variables such as the dissolved oxygen content and water temperature, and sporadic factors. Due to an outbreak of a natural bacterial infection in the fish stock followed by antibiotic treatment, a higher mortality rate was observed in the fish that received a standard diet compared to those fed supplemented feed. In the postinfection period, reduced dietary 18:2n-6 and 18:3n-3 fatty acid assimilation contents were detected in the fish that received the standard diet in contrast to the supplemented diet. By the end of the feeding season, an impaired antioxidant response, including reduced glutathione S-transferase activity and glutathione content, and a shift in the composition of membrane lipids, such as sterols, 18:1n-7 fatty acid, and phospholipids, were also revealed in fish fed the standard diet. Dietary supplementation with plant-origin substances, such as dihydroquercetin and arabinogalactan, decreases lethality in fish stocks, presumably though the stimulation of natural resistance in farmed fish, thereby increasing the economic efficacy during fish production. From the sustainable aquaculture perspective, natural additives also diminish the anthropogenic transformation of aquaculture-bearing water bodies and their ecosystems.

A unique, newly discovered four-member protein family involved in extracellular fatty acid binding in Yarrowia lipolytica

BackgroundYarrowia lipolytica, a nonconventional oleaginous yeast species, has attracted attention due to its high lipid degradation and accumulation capacities. Y. lipolytica is used as a chassis for the production of usual and unusual lipids and lipid derivatives. While the genes involved in the intracellular transport and activation of fatty acids in different cellular compartments have been characterized, no genes involved in fatty acid transport from the extracellular medium into the cell have been identified thus far. In this study, we identified secreted proteins involved in extracellular fatty acid binding.ResultsRecent analysis of the Y. lipolytica secretome led to the identification of a multigene family that encodes four secreted proteins, preliminarily named UP1 to UP4. These proteins were efficiently overexpressed individually in wild-type and multideletant strain (Q4: Δup1Δup2Δup3Δup4) backgrounds. Phenotypic analysis demonstrated the involvement of these proteins in the binding of extracellular fatty acids. Additionally, gene deletion and overexpression prevented and promoted sensitivity to octanoic acid (C8) toxicity, respectively. The results suggested binding is dependent on aliphatic chain length and fatty acid concentration. 3D structure modeling supports the proteins’ role in fatty acid assimilation at the molecular level.ConclusionsWe discovered a family of extracellular-fatty-acid-binding proteins in Y. lipolytica and have proposed to name its members eFbp1 to eFbp4. The exact mode of eFbps action remains to be deciphered individually and synergistically; nevertheless, it is expected that the proteins will have applications in lipid biotechnology, such as improving fatty acid production and/or bioconversion.

Analysis of the metabolic proteome of lung adenocarcinomas by reverse-phase protein arrays (RPPA) emphasizes mitochondria as targets for therapy

Lung cancer is the leading cause of cancer-related death worldwide despite the success of therapies targeting oncogenic drivers and immune-checkpoint inhibitors. Although metabolic enzymes offer additional targets for therapy, the precise metabolic proteome of lung adenocarcinomas is unknown, hampering its clinical translation. Herein, we used Reverse Phase Protein Arrays to quantify the changes in enzymes of glycolysis, oxidation of pyruvate, fatty acid metabolism, oxidative phosphorylation, antioxidant response and protein oxidative damage in 128 tumors and paired non-tumor adjacent tissue of lung adenocarcinomas to profile the proteome of metabolism. Steady-state levels of mitochondrial proteins of fatty acid oxidation, oxidative phosphorylation and of the antioxidant response are independent predictors of survival and/or of disease recurrence in lung adenocarcinoma patients. Next, we addressed the mechanisms by which the overexpression of ATPase Inhibitory Factor 1, the physiological inhibitor of oxidative phosphorylation, which is an independent predictor of disease recurrence, prevents metastatic disease. We highlight that IF1 overexpression promotes a more vulnerable and less invasive phenotype in lung adenocarcinoma cells. Finally, and as proof of concept, the therapeutic potential of targeting fatty acid assimilation or oxidation in combination with an inhibitor of oxidative phosphorylation was studied in mice bearing lung adenocarcinomas. The results revealed that this therapeutic approach significantly extended the lifespan and provided better welfare to mice than cisplatin treatments, supporting mitochondrial activities as targets of therapy in lung adenocarcinoma patients.

Effect of pH on biomass production and carbohydrate accumulation of Chlorella vulgaris JSC-6 under autotrophic, mixotrophic, and photoheterotrophic cultivation

Microalgal biomass, known as the third generation feedstock for biofuels production, is currently being explored mainly for lipids and functional components. However, the potential of microalgal carbohydrates has not been evaluated. In this investigation, Chlorella vulgaris JSC-6 was used for carbohydrates production from CO2 and fatty acids under different cultivation strategies to meet the requirements of a CO2-neutral and clean fermentation system for biofuel production. Autotrophic cultivation resulted in better carbon assimilation and carbohydrate accumulation; about 1.4 g CO2 could be converted to 1 g biomass, of which 50% are carbohydrates. Assimilation of fatty acids in photoheterotrophic and mixotrophic modes was influenced by pH, and pH 7–7.5 supported butyrate and acetate assimilation. The maximum carbohydrate content (49.86%) was attained in mixotrophic mode, and the ratio of the simple sugars glucose-xylose-arabinose was 1:0.11:0.02. The higher glucose content makes the microalgal biomass a suitable feedstock for sugar-based fermentations.

Metabolomic Evaluation of the Central Metabolic Pathways of Mannosylerythritol Lipid Biosynthesis in Moesziomyces antarcticus T-34.

Moesziomyces antarcticus is a basidiomycetous yeast that produces mannosylerythritol lipids (MELs), which have potential applications as bio-based functional materials in various oleochemical industries, the cosmetics, toiletry, agriculture, and pharmaceutical industries. To better understand the MEL producer, we characterized the central metabolic pathways of M. antarcticus strain T-34 grown on glucose or olive oil via metabolomics. The relative fatty acid content was higher in the cells cultured in olive oil compared to glucose, while the acetyl-CoA content was lower in cells cultured in olive oil. The levels of the tricarboxylic acid cycle metabolites citrate/isocitrate, α-ketoglutarate, and succinate were lower in olive oil compared to glucose, while fumarate and malate levels exhibited the opposite pattern. Pyruvate was not detected in olive oil compared to glucose culture. The levels of glycerol, as well as trehalose, myo-inositol, threitol/erythritol, and mannitol/sorbitol, were higher in olive oil compared to glucose cultures. The ATP level was lower in olive oil compared to glucose culture, although the assimilation of fatty acids produced by digestion of olive oil should promote large amounts of ATP production. The possibility that ATP regeneration by respiratory chain complex promote oil utilization and MEL production in M. antarcticus T-34 was found based on the results of this metabolomic analysis.

Participation of Acyl-Coenzyme A Synthetase FadD4 of Pseudomonas aeruginosa PAO1 in Acyclic Terpene/Fatty Acid Assimilation and Virulence by Lipid A Modification.

The pathogenic bacterium Pseudomonas aeruginosa possesses high metabolic versatility, with its effectiveness to cause infections likely due to its well-regulated genetic content. P. aeruginosa PAO1 has at least six fadD paralogous genes, which have been implicated in fatty acid (FA) degradation and pathogenicity. In this study, we used mutagenesis and a functional approach in P. aeruginosa PAO1 to determine the roles of the fadD4 gene in acyclic terpene (AT) and FA assimilation and on pathogenicity. The results indicate that fadD4 encodes a terpenoyl-CoA synthetase utilized for AT and FA assimilation. Additionally, mutations in fadD paralogs led to the modification of the quorum-sensing las/rhl systems, as well as the content of virulence factors pyocyanin, biofilm, rhamnolipids, lipopolysaccharides (LPS), and polyhydroxyalkanoates. In a Caenorhabditis elegans in vivo pathogenicity model, culture supernatants from the 24-h-grown fadD4 single mutant increased lethality compared to the PAO1 wild-type (WT) strain; however, the double mutants fadD1/fadD2, fadD1/fadD4, and fadD2/fadD4 and single mutant fadD2 increased worm survival. A correlation analysis indicated an interaction between worm death by the PAO1 strain, the fadD4 mutation, and the virulence factor LPS. Fatty acid methyl ester (FAME) analysis of LPS revealed that a proportion of the LPS and FA on lipid A were modified by the fadD4 mutation, suggesting that FadD4 is also involved in the synthesis/degradation and modification of the lipid A component of LPS. LPS isolated from the fadD4 mutant and double mutants fadD1/fadD4 and fadD2/fadD4 showed a differential behavior to induce an increase in body temperature in rats injected with LPS compared to the WT strain or from the fadD1 and fadD2 mutants. In agreement, LPS isolated from the fadD4 mutant and double mutants fadD1/fadD2 and fadD2/fadD4 increased the induction of IL-8 in rat sera, but IL1-β cytokine levels decreased in the double mutants fadD1/fadD2 and fadD1/fadD4. The results indicate that the fadD genes are implicated in the degree of pathogenicity of P. aeruginosa PAO1 induced by LPS-lipid A, suggesting that FadD4 contributes to the removal of acyl-linked FA from LPS, rendering modification in its immunogenic response associated to Toll-like receptor TLR4. The genetic redundancy of fadD is important for bacterial adaptability and pathogenicity over the host.

Improving the application of quantitative fatty acid signature analysis in soil food webs: The effects of diet fat content.

Quantitative fatty acid signature analysis (QFASA) as a biochemical tool to study the diet composition of predators is frequently used in marine ecology to infer trophic links in vertebrate consumers. However, the potential and challenges of this method in other ecosystems have only recently been studied. The application in soil ecosystems leads to hurdles not encountered in the marine, such as the low similarity of fatty acid signatures between resource and consumer. So far, diet estimation attempts have been semisuccessful, necessitating to adapt QFASA for use in soil food webs. Dietary fat content may play an important role, as it influences consumer metabolism, and thus calibration coefficients for fatty acid trophic transfer. A series of feeding trials with baker's yeast spiked with five different pure fatty acids at various concentrations was conducted with Collembola, and the changes in calibration coefficients were observed. From there, equations were gained through regression analysis and new sets of calibration coefficients were calculated. QFASA was applied on a range of basal resources and the results compared with previously defined calibration coefficients. Calibration coefficients changed with the proportion of fatty acids in the diet and differed between the three Collembolan species. The re‐estimation of diets showed an improvement of model performance by the new calibration coefficients and indicated several modes of fatty acid assimilation. These greatly influence the outcome of diet estimation, for example, algal and bacterial diets are likely underestimated due to high metabolic turnover rates. The application of QFASA in soil ecosystems remains challenging. The variation in calibration coefficients and the resulting decrease in estimation deviation indicate the merit of calculating calibration coefficients from consumer signatures through linear or exponential equations. Ideally, the method should, when extended to the entire fatty acid signature, allow correct determination of consumer diets in soil food webs.

RegX3 Controls Glyoxylate Shunt and Mycobacteria Survival by Directly Regulating the Transcription of Isocitrate Lyase Gene in Mycobacterium smegmatis.

The glyoxylate shunt is a pathway associated with the assimilation of fatty acids and is implicated in the resistance of M. tuberculosis (Mtb). Isocitrate lyase (ICL), the first enzyme in the glyoxylate shunt, mediates Mtb infections and its survival in mice via fatty acids, metabolism, and physiological functions. Here, we found that in Mycobacterium smegmatis (M. smegmatis) the two-component system SenX3-RegX3 regulated the glyoxylate shunt in response to phosphate starvation by controlling the transcription of icl. In response to phosphate availability, the phosphate regulator RegX3 directly bound to the upstream regulatory region of icl and repressed its transcription. The inactivation of regX3 increased icl transcription and ICL activity, causing a growth defect in M. smegmatis with fatty acids as the sole source of carbon and energy. The growth defect was partly due to the toxicity of the excess glyoxylate produced by ICL. A decrease in glyoxylic acid levels, overexpression of regX3, or the chemical inhibition (IA or 3-NP) of ICL restored the growth of the Regx3-deficient M. smegmatis. Thus, we established a genetic network between the phosphate stress response and glyoxylate shunt based on the amount of intracellular ICL during mycobacterial survival on short-chain fatty acids, which contributed to its antimicrobial arsenal.

Dietary fat concentrations influence fatty acid assimilation patterns in Atlantic pollock (Pollachius virens).

A key aspect in the use of fatty acids (FA) to estimate predator diets using quantitative FA signature analysis (QFASA) is the ability to account for FA assimilation through the use of calibration coefficients (CC). Here, we tested the assumption that CC are independent of dietary fat concentrations by feeding Atlantic pollock (Pollachius virens) three formulated diets with very similar FA proportions but different fat concentrations (5-9% of diet) for 20 weeks. CC calculated using FA profiles of diet and triacylglycerols in pollock liver were significantly different for the three diets. To test the robustness of diet estimates to these differences, we used the CC set derived from feeding the diet with the lowest fat concentration, published prey FA profiles and realistic diet estimates of pollock to construct 'pseudo-predators'. Application of QFASA to each pseudo-predator using the three sets of CC and the same prey FA profiles resulted in diet estimate biases of twofold for major prey items and approximately fivefold for minor prey items. This work illustrates the importance of incorporating diets with fat concentrations that are similar to natural prey when conducting feeding experiments to calculate CC. This article is part of the theme 'The next horizons for lipids as 'trophic biomarkers': evidence and significance of consumer modification of dietary fatty acids'.

A fatty acid-binding protein of Streptococcus pneumoniae facilitates the acquisition of host polyunsaturated fatty acids

Streptococcus pneumoniae is responsible for the majority of pneumonia, motivating ongoing searches for insights into its physiology that could enable new treatments. S. pneumoniae responds to exogenous fatty acids by suppressing its de novo biosynthetic pathway and exclusively utilizing extracellular fatty acids for membrane phospholipid synthesis. The first step in exogenous fatty acid assimilation is phosphorylation by fatty acid kinase (FakA), whereas bound by a fatty acid-binding protein (FakB). Staphylococcus aureus has two binding proteins, whereas S. pneumoniae expresses three. The functions of these binding proteins were not clear. We determined the SpFakB1- and SpFakB2-binding proteins were bioinformatically related to the two binding proteins of Staphylococcus aureus, and biochemical and X-ray crystallographic analysis showed that SpFakB1 selectively bound saturates, whereas SpFakB2 allows the activation of monounsaturates akin to their S. aureus counterparts. The distinct SpFakB3 enables the utilization of polyunsaturates. The SpFakB3 crystal structure in complex with linoleic acid reveals an expanded fatty acid-binding pocket within the hydrophobic interior of SpFakB3 that explains its ability to accommodate multiple cis double bonds. SpFakB3 also utilizes a different hydrogen bond network than other FakBs to anchor the fatty acid carbonyl and stabilize the protein. S. pneumoniae strain JMG1 (ΔfakB3) was deficient in incorporation of linoleate from human serum verifying the role of FakB3 in this process. Thus, the multiple FakBs of S. pneumoniae permit the utilization of the entire spectrum of mammalian fatty acid structures to construct its membrane.

Lipid and fatty acid turnover of the pteropods Limacina helicina, L. retroversa and Clione limacina from Svalbard waters

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 609:133-149 (2019) - DOI: https://doi.org/10.3354/meps12837 Lipid and fatty acid turnover of the pteropods Limacina helicina, L. retroversa and Clione limacina from Svalbard waters Lauris Boissonnot1,2,*, Barbara Niehoff1, Benedikt Ehrenfels2,3, Janne E. Søreide2, Wilhelm Hagen4, Martin Graeve1 1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany 2University Centre in Svalbard, 9171 Longyearbyen, Norway 3University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany 4BreMarE Bremen Marine Ecology, Marine Zoology, University of Bremen, 28334 Bremen, Germany *Corresponding author: lauris.boissonnot@gmail.com ABSTRACT: This study aimed at a better understanding of the fatty acid (FA) turnover in Arctic pteropods. Thecosome pteropods, i.e. Limacina helicina (juveniles and adults) and L. retroversa (adults), were collected in summer/autumn in Kongsfjorden and Isfjorden (Svalbard, 78° N) and, for the first time, successfully fed with 13C-labeled algae for 6 d. The gymnosome pteropod Clione limacina was sampled in summer in northern Svalbard and fed with 13C-labeled L. retroversa for 23 d. FA compositions were determined by gas chromatography, and 13C enrichment of FAs was analyzed by compound-specific isotope analysis. Among the thecosomes, maximum lipid turnover occurred in L. retroversa adults (1.3% d-1). L. helicina adults and juveniles showed lower lipid turnover rates (0.1 and 0.2% d-1, respectively). The thecosomes exhibited the ability to assimilate omega-3 FAs (up to 8.0% d-1). The lipid turnover rate of C. limacina averaged at only 0.07% d-1. However, C. limacina clearly showed the unusual capacity of de novo synthesis of odd-chain FAs (up to 1.2% d-1). Lipid turnover rates of pteropods were lower than those reported for Arctic copepods. However, pteropods may play a substantial role in the transfer of lipids to higher trophic levels, especially in autumn, when copepods have descended from the upper layers of the water column. The pteropods also showed the capacity to channel particular compounds such as omega-3 and odd-chain FAs, and therefore could be important for the functional diversity of the Arctic zooplankton community. KEY WORDS: Fatty acid assimilation · Trophic transfer · Omega-3 fatty acids · 13C labeling · Compound-specific isotope analysis · CSIA · Arctic Full text in pdf format PreviousNextCite this article as: Boissonnot L, Niehoff B, Ehrenfels B, Søreide JE, Hagen W, Graeve M (2019) Lipid and fatty acid turnover of the pteropods Limacina helicina, L. retroversa and Clione limacina from Svalbard waters. Mar Ecol Prog Ser 609:133-149. https://doi.org/10.3354/meps12837 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 609. Online publication date: January 17, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

GlnR-Mediated Regulation of Short-Chain Fatty Acid Assimilation in Mycobacterium smegmatis.

Assimilation of short-chain fatty acids (SCFAs) plays an important role in the survival and lipid biosynthesis of Mycobacteria. However, regulation of this process has not been thoroughly described. In the present work, we demonstrate that GlnR as a well-known nitrogen-sensing regulator transcriptionally modulates the AMP-forming propionyl-CoA synthetase (MsPrpE), and acetyl-CoA synthetases (MsAcs) is associated with SCFAs assimilation in Mycobacterium smegmatis, a model Mycobacterium. GlnR can directly activate the expression of MsprpE and Msacs by binding to their promoter regions based upon sensed nitrogen starvation in the host. Moreover, GlnR can activate the expression of lysine acetyltransferase encoding Mspat, which significantly decreases the activity of MsPrpE and MsAcs through increased acylation. Next, growth curves and resazurin assay show that GlnR can further regulate the growth of M. smegmatis on different SCFAs to control the viability. These results demonstrate that GlnR-mediated regulation of SCFA assimilation in response to the change of nitrogen signal serves to control the survival of M. smegmatis. These findings provide insights into the survival and nutrient utilization mechanisms of Mycobacteria in their host, which may enable new strategies in drug discovery for the control of tuberculosis.

Evaluation of Marine Microalga Diacronema vlkianum Biomass Fatty Acid Assimilation in Wistar Rats

Diacronema vlkianum is a marine microalgae for which supposed health promoting effects have been claimed based on its phytochemical composition. The potential use of its biomass as health ingredient, including detox-shakes, and the lack of bioavailability studies were the main concerns. In order to evaluate the microalgae-biomass assimilation and its health-benefits, single-dose (CD1-mice) studies were followed by 66-days repeated-dose study in Wistar rats with the highest tested single-dose of microalgae equivalent to 101 mg/kg eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA). Microalgae-supplementation modulated EPA and docosapentaenoic acid enrichment at arachidonic acid content expenditure in erythrocytes and liver, while increasing EPA content of heart and adipose tissues of rats. Those fatty acid (FA) changes confirmed the D. vlkianum-biomass FA assimilation. The principal component analyses discriminated brain from other tissues, which formed two other groups (erythrocytes, liver, and heart separated from kidney and adipose tissues), pointing to a distinct signature of FA deposition for the brain and for the other organs. The improved serum lipid profile, omega-3 index and erythrocyte plasticity support the cardiovascular benefits of D. vlkianum. These results bolster the potential of D. vlkianum-biomass to become a “heart-healthy” food supplement providing a safe and renewable source of bioavailable omega-3 FA.

Docosahexaenoic acid at the sn-2 position of structured triacylglycerols improved n-3 polyunsaturated fatty acid assimilation in tissues of hamsters

In this study, we hypothesized that the incorporation of docosahexaenoic acid (DHA) in tissues will be higher when it is ingested as triacylglycerols (TAG) structured at the sn-2 position, which enhances efficacy and health benefits of dietary DHA n-3 supplementation. Ten-week-old Golden Syrian male hamsters were randomly allocated into 4 dietary groups with 10 animals in each: linseed oil (LSO; control group), fish oil (FO), fish oil ethyl esters (FO-EE), and structured DHA at the sn-2 position of TAG (DHA-SL). After 12weeks, there were no variations in the hamsters’ body composition parameters across dietary groups. The DHA-SL diet had the lowest values of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total lipids, and aspartate aminotransferase activity, whereas the inverse was observed for the FO diet. Glucose was increased in the LSO diet without affecting insulin and insulin resistance markers. Whereas n-3 polyunsaturated fatty acid was increased in the brain of hamsters fed the DHA-SL diet, higher levels of n-6 polyunsaturated fatty acid were observed in the liver and erythrocytes of the LSO. The highest omega-3 index was obtained with the DHA-SL diet. The principal component analyses discriminated DHA from other metabolites and set apart 4 clusters matching the 4 diets. Similarly, liver, erythrocytes, and brain were separated from each other, pointing toward an individual signature on fatty acid deposition. The structured sn-2 position DHA-containing TAG ameliorated blood lipids and fatty acid incorporation, in particular eicosapentaenoic acid and DHA in liver, erythrocytes, and brain, relative to commercially FOs, thus improving the health benefits of DHA due to its higher bioavailability.

Extracellular esterases of phylloplane yeast Pseudozyma antarctica induce defect on cuticle layer structure and water-holding ability of plant leaves.

Aerial plant surface (phylloplane) is a primary key habitat for many microorganisms but is generally recognized as limited in nutrient resources. Pseudozyma antarctica, a nonpathogenic yeast, is commonly isolated from plant surfaces and characterized as an esterase producer with fatty acid assimilation ability. In order to elucidate the biological functions of these esterases, culture filtrate with high esterase activity (crude enzyme) of P. antarctica was applied onto leaves of tomato and Arabidopsis. These leaves showed a wilty phenotype, which is typically associated with water deficiency. Furthermore, we confirmed that crude enzyme-treated detached leaves clearly lost their water-holding ability. In treated leaves of both plants, genes associated to abscisic acid (ABA; a plant stress hormone responding osmotic stress) were activated and accumulation of ABA was confirmed in tomato plants. Microscopic observation of treated leaf surfaces revealed that cuticle layer covering the aerial epidermis of leaves became thinner. A gas chromatography-mass spectrometry (GC-MS) analysis exhibited that fatty acids with 16 and 18 carbon chains were released in larger amounts from treated leaf surfaces, indicating that the crude enzyme has ability to degrade lipid components of cuticle layer. Among the three esterases detected in the crude enzyme, lipase A, lipase B, and P. antarctica esterase (PaE), an in vitro enzyme assay using para-nitrophenyl palmitate as substrate demonstrated that PaE was the most responsible for the degradation. These results suggest that PaE has a potential role in the extraction of fatty acids from plant surfaces, making them available for the growth of phylloplane yeasts.

Essential Fatty Acid Assimilation and Synthesis in Larvae of the Bivalve Crassostrea gigas.

Essential fatty acids (EFA) are important for bivalve larval survival and growth. The purpose of this study was to quantitatively assess for the first time through a mass-balance approach dietary EFA incorporation and synthesis within Crassostrea gigas larvae. A first experiment was carried out using two microalgae, Tisochrysis lutea (T) and Chaetoceros neogracile (Cg), as mono- and bi-specific diets. A second experiment using a similar design was performed to confirm and extend the results obtained in the first. Flow-through larval rearing was used for accurate control of food supply and measurement of ingestion. Non-methylene-interrupted fatty acids were synthetized from precursors supplied in the diet: 16:1n-7 and 18:1n-9, mediated by Δ5 desaturase. Moreover, this Δ5 desaturase presumably allowed larvae to convert 20:3n-6 and 20:4n-3 to 20:4n-6 and 20:5n-3, respectively, when the product EFA were poorly or not supplied in the diet, as when larvae were fed T exclusively. Under our experimental conditions, none of the diets induced 22:6n-3 synthesis; however, 22:6n-3 incorporation into larval tissues occurred selectively under non-limiting dietary supply to maintain optimal levels in the larvae. This combination of flow-through larval rearing and biochemical analysis of FA levels could be applied to additional dietary experiments to precisely define optimal levels of EFA supply.

Differing Daphnia magna assimilation efficiencies for terrestrial, bacterial, and algal carbon and fatty acids

There is considerable interest in the pathways by which carbon and growth-limiting elemental and biochemical nutrients are supplied to upper trophic levels. Fatty acids and sterols are among the most important molecules transferred across the plant-animal interface of food webs. In lake ecosystems, in addition to phytoplankton, bacteria and terrestrial organic matter are potential trophic resources for zooplankton, especially in those receiving high terrestrial organic matter inputs. We therefore tested carbon, nitrogen, and fatty acid assimilation by the crustacean Daphnia magna when consuming these resources. We fed Daphnia with monospecific diets of high-quality (Cryptomonas marssonii) and intermediate-quality (Chlamydomonas sp. and Scenedesmus gracilis) phytoplankton species, two heterotrophic bacterial strains, and particles from the globally dispersed riparian grass, Phragmites australis, representing terrestrial particulate organic carbon (t-POC). We also fed Daphnia with various mixed diets, and compared Daphnia fatty acid, carbon, and nitrogen assimilation across treatments. Our results suggest that bacteria were nutritionally inadequate diets because they lacked sterols and polyunsaturated omega-3 and omega-6 (omega-3 and omega-6) fatty acids (PUFAs). However, Daphnia were able to effectively use carbon and nitrogen from Actinobacteria, if their basal needs for essential fatty acids and sterols were met by phytoplankton. In contrast to bacteria, t-POC contained sterols and omega-6 and omega-3 fatty acids, but only at 22%, 1.4%, and 0.2% of phytoplankton levels, respectively, which indicated that t-POC food quality was especially restricted with regard to omega-3 PUFAs. Our results also showed higher assimilation of carbon than fatty acids from t-POC and bacteria into Daphnia, based on stable-isotope and fatty acids analysis, respectively. A relatively high (>20%) assimilation of carbon and fatty acids from t-POC was observed only when the proportion of t-POC was >60%, but due to low PUFA to carbon ratio, these conditions yielded poor Daphnia growth. Because of lower assimilation for carbon, nitrogen, and fatty acids from t-POC relative to diets of bacteria mixed with phytoplankton, we conclude that the microbial food web, supported by phytoplankton, and not direct t-POC consumption, may support zooplankton production. Our results suggest that terrestrial particulate organic carbon poorly supports upper trophic levels of the lakes.

Structural and Binding Properties of Two Paralogous Fatty Acid Binding Proteins of Taenia solium Metacestode

BackgroundFatty acid (FA) binding proteins (FABPs) of helminths are implicated in acquisition and utilization of host-derived hydrophobic substances, as well as in signaling and cellular interactions. We previously demonstrated that secretory hydrophobic ligand binding proteins (HLBPs) of Taenia solium metacestode (TsM), a causative agent of neurocysticercosis (NC), shuttle FAs in the surrounding host tissues and inwardly transport the FAs across the parasite syncytial membrane. However, the protein molecules responsible for the intracellular trafficking and assimilation of FAs have remained elusive.Methodology/Principal FindingsWe isolated two novel TsMFABP genes (TsMFABP1 and TsMFABP2), which encoded 133- and 136-amino acid polypeptides with predicted molecular masses of 14.3 and 14.8 kDa, respectively. They shared 45% sequence identity with each other and 15–95% with other related-members. Homology modeling demonstrated a characteristic β-barrel composed of 10 anti-parallel β-strands and two α-helices. TsMFABP2 harbored two additional loops between β-strands two and three, and β-strands six and seven, respectively. TsMFABP1 was secreted into cyst fluid and surrounding environments, whereas TsMFABP2 was intracellularly confined. Partially purified native proteins migrated to 15 kDa with different isoelectric points of 9.2 (TsMFABP1) and 8.4 (TsMFABP2). Both native and recombinant proteins bound to 11-([5-dimethylaminonaphthalene-1-sulfonyl]amino)undecannoic acid, dansyl-DL-α-amino-caprylic acid, cis-parinaric acid and retinol, which were competitively inhibited by oleic acid. TsMFABP1 exhibited high affinity toward FA analogs. TsMFABPs showed weak binding activity to retinol, but TsMFABP2 showed relatively high affinity. Isolation of two distinct genes from an individual genome strongly suggested their paralogous nature. Abundant expression of TsMFABP1 and TsMFABP2 in the canal region of worm matched well with the histological distributions of lipids and retinol.Conclusions/SignificanceThe divergent biochemical properties, physiological roles and cellular distributions of the TsMFABPs might be one of the critical mechanisms compensating for inadequate de novo FA synthesis. These proteins might exert harmonized or independent roles on lipid assimilation and intracellular signaling. The specialized distribution of retinol in the canal region further implies that cells in this region might differentiate into diverse cell types during metamorphosis into an adult worm. Identification of bioactive systems pertinent to parasitic homeostasis may provide a valuable target for function-related drug design.