Production Of Polyunsaturated Fatty Acids Research Articles

Silencing 1,3-β-glucan synthase gene promotes total lipid production and changes fatty acids composition by affecting carbon flow distribution in Phaeodactylum tricornutum

To clarify the effect of 1,3-β-glucan (known as chrysolaminarin) synthase ( Pt BGS) on carbon flow distribution, expression of 1,3-β-glucan synthase gene ( Ptbgs ) was silenced by RNA interference in Phaeodactylum tricornutum . The results showed that the chrysolaminarin content in all transgenic strains was significantly lower than that in the wild-type (WT), while the total lipid content increased to varying degrees. Importantly, the decrease in chrysolaminarin content was significantly correlated with the increase in total lipid content. There was no significant difference in the protein content between all the transgenic strains and WT. Thus, Pt BGS mainly affected the distribution of carbon flow in total lipids and polysaccharides , mainly chrysolaminarin. Silencing Ptbgs changed the fatty acids composition , and specifically promoted polyunsaturated fatty acids production and reduced monounsaturated fatty acids content, but had only a little effect on saturated fatty acids content. Interestingly, the growth of transgenic strains was not influenced while the lipid content increased, indicating that Ptbgs silencing may be an effective strategy to improve lipid production in diatoms. • Distribution of carbon flow can be affected by 1,3-β-glucan synthase ( Pt BGS). • Inhibiting the expression of Ptbgs promoted lipid accumulation. • Silencing Ptbgs changed the fatty acids composition. • Interfering with Ptbgs exerted little effect on growth in Phaeodactylum tricornutum . • Ptbgs silencing may be an effective strategy to improve lipid production in diatoms.

Whole genome analysis and elucidation of docosahexaenoic acid (DHA) biosynthetic pathway in Aurantiochytrium sp. SW1

Aurantiochytrium sp., a fungoid marine protist that belongs to Stramenophila has proven its potential in the production of polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acids (DHA). In this study, genomic characterisation of a potential producer for commercial production of DHA, Aurantiochytrium sp. SW1 has been carried out via whole genome sequencing analysis. The genome size of this strain is 60.89 Mb, with a total of 11,588 protein-coding genes. Among these, 9,127 genes could be functionally annotated into a total of 7,248 (62.5 %) from UniProt, 6,554 (56.6 %) from KEGG and 8,643 (74.6 %) genes from eggNOG protein database. The highest proportion of genes belongs to the protein family of metabolism were further assigned into 11 metabolic categories. The highest number of genes belonging to lipid metabolism (321 genes) followed by carbohydrate metabolism (290 genes), metabolism of cofactors and vitamins (197 genes) and amino acid metabolism (188 genes). Further analysis into the biosynthetic pathway for DHA showed evidence of all genes involved in PKS (polyketide synthase)-like PUFA synthase pathway and incomplete fatty acid synthase-elongase/desaturase pathway. Analysis of PUFA synthase showed the presence of up to ten tandem acyl carrier protein (ACP) domains which might have contributed to high DHA production in this organism. In addition, a hybrid system incorporating elements of FAS, Type I PKS and Type II PKS systems were found to be involved in the biosynthetic pathways of fatty acids in Aurantiochytrium sp. SW1. This study delivers an important reference for future research to enhance the lipid, especially DHA production in Aurantiochytrium sp, SW1 and establishment of this strain as an oleaginous thraustochytrid model.

Homologous and Heterologous Expression of Delta(12)-Desaturase in Mucor circinelloides Enhanced the Production of Linolenic Acid.

Linolenic acid (LA) is gaining more interest within the scientific community. This is because it has a potential medical role in reducing the risk of inflammation, carcinogenesis, atherosclerosis and diabetes and is a valuable nutraceutical for human health. The oleaginous fungus Mucor circinelloides produces a high lipid content (36%), including valuable polyunsaturated fatty acids (PUFAs). However, the critical step in which oleic acid (OA) is converted into LA is not efficient at supplying enough substrates for PUFA synthesis. Hence, we propose a method to increase LA production based on genetic engineering. The overexpression of the Δ12-desaturase gene from M. circinelloides and Mortierella alpina increased the LA content and improved the lipid accumulation (from 14.9% to 21.6% in the Δ12-desaturase gene of the M. circinelloides overexpressing strain (Mc-D12MC) and from 14.9% to 18.7% in the Δ12-desaturase gene of M. alpina overexpressing strain (Mc-D12MA)). Additionally, the up-regulated expression levels of these genes targeted the genes involved in NADPH production, implying that the elevated Δ12-desaturase gene may function as a critical regulator of NADPH and lipid synthesis in M. circinelloides. This study provides the first evidence to support the design of metabolic engineering related to LA and PUFA production in M. circinelloides for potential industrial applications.

Utilization of saline and viscous food-processing liquid waste for cultivation of thraustochytrid for production of polyunsaturated fatty acids

Utilization of saline and viscous food-processing liquid waste for cultivation of thraustochytrid for production of polyunsaturated fatty acids

Combined effects of eutrophication and warming on polyunsaturated fatty acids in complex phytoplankton communities: A mesocosm experiment

Climate change and eutrophication are among the main stressors of shallow freshwater ecosystems, and their effects on phytoplankton community structure and primary production have been studied extensively. However, their combined effects on the algal production of polyunsaturated fatty acids (PUFA), specifically, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are currently unresolved. Moreover, the proximate reasons for changes in phytoplankton EPA and DHA concentrations are unclear, i.e., the relative importance of ecological (changes in the community composition) vs. ecophysiological (within taxa changes in EPA and DHA levels) factors.We investigated the responses of phytoplankton EPA and DHA concentrations to warming (IPCC climate scenario) and nutrient additions in mesocosms which had been run continuously at varying temperature and nutrient levels for 15 years prior to this study. Nutrient treatment had a significant effect on phytoplankton EPA and DHA concentrations and about 59 % of the variation in EPA and DHA concentrations could be explained by changes in the phytoplankton community structure. Increased biomass of diatoms corresponded with high EPA and DHA concentrations, while cyanobacteria/chlorophyte dominated mesocosm had low EPA and DHA concentrations. Warming had only a marginal effect on the EPA and DHA concentrations in these mesocosms. However, a significant interaction was observed with warming and N:P ratio.Our findings indicate that direct nutrient/temperature effects on algal physiology and PUFA metabolism were negligible and the changes in EPA and DHA concentrations were mostly related to the phytoplankton community structure and biomass. These results also imply that in shallow temperate lakes eutrophication, leading to increased dominance of cyanobacteria, will probably be a greater threat to phytoplankton EPA and DHA production than warming. EPA and DHA are nutritionally important for upper trophic level consumers and decreased production may impair secondary production.

Dark stress for improved lipid quantity and quality in bioprospected acid-tolerant green microalgae.

The cost of microalgae cultivation is one of the largest limitations to achieving sustainable, large-scale microalgae production of commercially desirable lipids. Utilizing CO2 as a 'free' carbon source from waste industrial flue gas emissions can offer wide-ranging cost savings. However, these gas streams typically create acidic environments, in which most microalgae cannot survive due to the concentration of CO2 and the presence of other acidic gasses such as NO2 and SO2. To address this situation, we investigated growth of a mixed acid-tolerant green microalgal culture (91% dominated by a single Coccomyxa sp. taxon) bioprospected at pH 2.8 from an acid mine drainage impacted water body. The culture was grown at pH 2.5 and fed with a simulated flue gas containing 6% CO2 and 94% N2. On reaching the end of the exponential growth phase, the culture was exposed to either continued light-dark cycle conditions or continual dark conditions. After three days in the dark, the biomass consisted of 28% of lipids, which was 42% higher than at the end of the exponential phase and 55% higher than the maximum lipid content achieved under light/dark conditions. The stress caused by being continually in the dark also favoured the production of omega-3 and omega-6 polyunsaturated fatty acids (PUFAs; 19.47% and 21.04%, respectively, after 7 days) compared to 7-days of light-dark treatment (1.94% and 9.53%, respectively) and showed an increase in nitrogen content (C:N ratio of 6.4) compared to light-dark treatment (C:N ratio of 11.9). The results of the research indicate that use of acid tolerant microalgae overcomes issues using flue gasses that will create an acidic environment and that applying dark stress is a low-cost stressor stimulates production of desirable dietary lipids.

Microalgae-Based PUFAs for Food and Feed: Current Applications, Future Possibilities, and Constraints

Microalgae are currently considered an attractive source of highly valuable compounds for human and animal consumption, including polyunsaturated fatty acids (PUFAs). Several microalgae-derived compounds, such as ω-3 fatty acids, pigments, and whole dried biomasses are available on the market and are mainly produced by culturing microalgae in open ponds, which can be achieved with low setup and maintenance costs with respect to enclosed systems. However, open tanks are more susceptible to bacterial and other environmental contamination, do not guarantee a high reproducibility of algal biochemical profiles and productivities, and constrain massive cultivation to a limited number of species. Genetic engineering techniques have substantially improved over the last decade, and several model microalgae have been successfully modified to promote the accumulation of specific value-added compounds. However, transgenic strains should be cultured in closed photobioreactors (PBRs) to minimize risks of contamination of aquatic environments with allochthonous species; in addition, faster growth rates and higher yields of compounds of interest can be achieved in PBRs compared to open ponds. In this review, we present information collected about the major microalgae-derived commodities (with a special focus on PUFAs) produced at industrial scale, as well genetically-engineered microalgae to increase PUFA production. We also critically analyzed the main bottlenecks that make large-scale production of algal commodities difficult, as well as possible solutions to overcome the main problems and render the processes economically and environmentally safe.

Eco-friendly production of nutraceutical and cosmeceutical fatty acids by oleaginous fungus Lichtheimia hyalospora UCP 1266 using renewable substrates

Polyunsaturated fatty acids (PUFAs) are essential for human functions and can be used in nutraceuticals; however, traditional sources are environmentally unsustainable. A promising strategy to reduce the production costs of PUFAs is the use of economical agro-industrial sources as substrates in culture media for oleaginous microorganisms. In this study, we investigated the potential of the fungus Lichtheimia hyalospora UCP 1266 (isolated from the Caatinga soil, Brazil) in the production of PUFAs, through the metabolic conversion of alternative substrates crude glycerol (CG) and corn steep liquor (CSL). The cultivation of L. hyalospora UCP 1266 in medium containing glucose (Synthetic Medium for Mucorales - SMM) yielded 2.1 g/L of biomass and 0.6 g/L of total lipids. However, assay 4 of the 22 full-factorial design, with CG 8% and CSL 8%, provided higher yields of biomass (15.5 g/L) and total lipids (12.8 g/L). The lipids produced in this medium presented a composition of saturated, monounsaturated and polyunsaturated fatty acids (SFAs=35.13%, MUFAs=46.09% and PUFAs=18.14%). The microorganism proved to be promising in the production of omega 6 (linoleic acid, C18:2), γ-linolenic acid (C18:3), omega 3 (α-linolenic acid, C18:3) and omega 9 (oleic acid, C18:1). The results indicated L. hyalospora UCP 1266 as an oleaginous fungus with great potential for use in the development of nutraceutical ingredients for food or applied in cosmeceuticals and/or nutricosmetics.

Comparative Lipidome and Transcriptome Provide Novel Insight Into Polyunsaturated Fatty Acids Metabolism of the Sea Urchin

The sea urchin Strongylocentrotus intermedius is one of the most economically important echinoids harvested from northeast Pacific Ocean coastal waters. The gonads of sea urchins have high nutritional value and are primarily a candidate source of polyunsaturated fatty acids (PUFA). PUFAs are essential for human health, and the biological synthesis and industry production of PUFA have attracted more and more attention from the scientific community. Moreover, PUFAs are important necessary nutrients that determine not only the nutritional value of sea urchins but guarantee their normal growth and reproduction. In this study, we divided 178 sea urchins into three groups (high, medium, and low concentration PUFA groups) according to the concentration of PUFAs, and conducted integrative lipidomics and transcriptomics analyses of different PUFA abundances of S. intermedius to determine the critical genes related to PUFA metabolism in sea urchin gonads. Illumina sequencing generated 894,295,712 clean reads (133.28 Gb) in 18 cDNA libraries. Among all of the unigenes, nine up- and seven down-regulated unigenes were found in a comparison of the “high vs low” concentration PUFA groups of gonads. Interestingly, we found that tudor domain-containing protein 3 (TDRD3) was up-regulated in the high concentration PUFA group, and this gene was significantly related to eicosapentaenoic acid (EPA) in the correlation analysis (p<0.05), and may be used as a candidate marker for EPA biosynthesis and metabolism in the sea urchin. The lipidome and transcriptome information will provide a basic resource for further studies designed to elucidate the molecular mechanism of PUFA metabolism in marine invertebrates, and act as a valuable resource for the practical applications and regulation of the sea urchin aquaculture industry in the future.

Production, Processing, and Protection of Microalgal n-3 PUFA-Rich Oil.

Microalgae have been increasingly considered as a sustainable “biofactory” with huge potentials to fill up the current and future shortages of food and nutrition. They have become an economically and technologically viable solution to produce a great diversity of high-value bioactive compounds, including n-3 polyunsaturated fatty acids (PUFA). The n-3 PUFA, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), possess an array of biological activities and positively affect a number of diseases, including cardiovascular and neurodegenerative disorders. As such, the global market of n-3 PUFA has been increasing at a fast pace in the past two decades. Nowadays, the supply of n-3 PUFA is facing serious challenges as a result of global warming and maximal/over marine fisheries catches. Although increasing rapidly in recent years, aquaculture as an alternative source of n-3 PUFA appears insufficient to meet the fast increase in consumption and market demand. Therefore, the cultivation of microalgae stands out as a potential solution to meet the shortages of the n-3 PUFA market and provides unique fatty acids for the special groups of the population. This review focuses on the biosynthesis pathways and recombinant engineering approaches that can be used to enhance the production of n-3 PUFA, the impact of environmental conditions in heterotrophic cultivation on n-3 PUFA production, and the technologies that have been applied in the food industry to extract and purify oil in microalgae and protect n-3 PUFA from oxidation.

Association Analysis between Genetic Variants of elovl5a and elovl5b and Poly-Unsaturated Fatty Acids in Common Carp (Cyprinus carpio).

Simple SummaryPUFAs have an essential impact on human health, but their availability constitutes a critical bottleneck in food production. Although fish is the traditional source of PUFAs, it is limited by the stagnation of fisheries. Many studies aim to increase the PUFA products of fish. Genetic markers are efficient in aquaculture breeding. Fatty acid desaturase 2 (fads2) and elongase 5 (elovl5) are the rate-limiting enzymes in the synthesis of PUFAs. The allo-tetraploid common carp is able to biosynthesize endogenous PUFAs. However, selective breeding common carp with high PUFA contents was hindered due to a lack of effective molecular markers. For future breeding common carp capable of producing endogenous PUFAs more effectively, we previously identified the polymorphisms in the coding regions of two duplicated fads2, fads2a and fads2b. However, the polymorphisms in the duplicated elovl5, elovl5a and elovl5b, were not detected. This study screened the genetic variants in the coding regions of elovl5a and elovl5b. Moreover, the joint effects of multiple coding SNPs in fads2b and elovl5b, two major genes regulating the PUFA biosynthesis, were evidenced with the increased explained percentages of the PUFA contents. These polymorphisms in these two genes were used to evaluate the breeding values of PUFAs. These SNPs would be potential markers for future selection to improve the PUFA contents in common carp.The allo-tetraploid common carp, one widely cultured food fish, is able to produce poly-unsaturated fatty acids (PUFAs). The genetic markers on the PUFA contents for breeding was limited. The polymorphisms in elovl5a and elovl5b, the rate-limiting enzymes in the PUFA biosynthesis, have not been investigated yet. Herein, we identified one coding SNP (cSNP) in elovl5a associated with the content of one PUFA and two cSNPs in elovl5b with the contents of eight PUFAs. The heterozygous genotypes in these three loci were associated with higher contents than the homozygotes. Together with previously identified two associated cSNPs in fads2b, we found the joint effect of these four cSNPs in fads2b and elovl5b on the PUFA contents with the increased explained percentages of PUFA contents. The genotype combinations of more heterozygotes were associated with higher PUFA contents than the other combinations. Using ten genomic selection programs with all cSNPs in fads2b and elovl5b, we obtained the high and positive correlations between the phenotypes and the estimated breeding values of eight PUFAs. These results suggested that elovl5b might be the major gene corresponding to common carp PUFA contents compared with elovl5a. The cSNP combinations in fads2b and elovl5b and the optimal genomic selection program will be used in the future selection breeding to improve the PUFA contents of common carp.

Microbes: A Hidden Treasure of Polyunsaturated Fatty Acids.

Microbes have gained a lot of attention for their potential in producing polyunsaturated fatty acids (PUFAs). PUFAs are gaining scientific interest due to their important health-promoting effects on higher organisms including humans. The current sources of PUFAs (animal and plant) have associated limitations that have led to increased interest in microbial PUFAs as most reliable alternative source. The focus is on increasing the product value of existing oleaginous microbes or discovering new microbes by implementing new biotechnological strategies in order to compete with other sources. The multidisciplinary approaches, including metabolic engineering, high-throughput screening, tapping new microbial sources, genome-mining as well as co-culturing and elicitation for the production of PUFAs, have been considered and discussed in this review. The usage of agro-industrial wastes as alternative low-cost substrates in fermentation for high-value single-cell oil production has also been discussed. Multidisciplinary approaches combined with new technologies may help to uncover new microbial PUFA sources that may have nutraceutical and biotechnological importance.

On 'The thiobarbituric acid reaction and the autoxidations of polyunsaturated fatty acid methyl esters' by Leland K.Dahle, Eldon G.Hill and Ralph T.Holman

This commentary describes a highly cited paper by Dahle, Hill, and Holman, Arch Biochem Biophys. 1962; 98: 253–261. They showed that the oxidation products of polyunsaturated fatty acids reacted with thiobarbituric acid to give a colored product, which might be used to assess lipid oxidation.

Transcriptomic and fatty acid analyses of Neochloris aquatica grown under different nitrogen concentration.

In this study, we characterized the fatty acid production in Neochloris aquatica at transcriptomics and biochemical levels under limiting, normal, and excess nitrate concentrations in different growth phases. At the stationary phase, N. aquatica mainly produced saturated fatty acids such as stearic acid under the limiting nitrate concentration, which is suitable for biodiesel production. However, it produced polyunsaturated fatty acids such as α-linolenic acid under the excess nitrate concentration, which has nutritional values as food supplements. In addition, RNA-seq was employed to identify genes and pathways that were being affected in N. aquatica for three growth phases in the presence of the different nitrate amounts. Genes that are responsible for the production of saturated fatty acids were upregulated in the cells grown under a limiting nitrogen amount while genes that are responsible for the production of polyunsaturated fatty acid were upregulated in the cells grown under excess nitrogen amount. Further analysis showed more genes differentially expressed (DEGs) at the logarithmic phase in all conditions while a relatively steady trend was observed during the transition from the logarithmic phase to the stationary phase under limiting and excess nitrogen. Our results provide a foundation for identifying developmentally important genes and understanding the biological processes in the different growth phases of the N. aquatica in terms of biomass and lipid production.

Regulation of the Leucine Metabolism in Mortierella alpina.

The oleaginous fungus Mortierella alpina is a safe source of polyunsaturated fatty acids (PUFA) in industrial food and feed production. Besides PUFA production, pharmaceutically relevant surface-active and antimicrobial oligopeptides were isolated from this basal fungus. Both production of fatty acids and oligopeptides rely on the biosynthesis and high turnover of branched-chain-amino acids (BCAA), especially l-leucine. However, the regulation of BCAA biosynthesis in basal fungi is largely unknown. Here, we report on the regulation of the leucine, isoleucine, and valine metabolism in M. alpina. In contrast to higher fungi, the biosynthetic genes for BCAA are hardly transcriptionally regulated, as shown by qRT-PCR analysis, which suggests a constant production of BCAAs. However, the enzymes of the leucine metabolism are tightly metabolically regulated. Three enzymes of the leucine metabolism were heterologously produced in Escherichia coli, one of which is inhibited by allosteric feedback loops: The key regulator is the α-isopropylmalate synthase LeuA1, which is strongly disabled by l-leucine, α-ketoisocaproate, and propionyl-CoA, the precursor of the odd-chain fatty acid catabolism. Its gene is not related to homologs from higher fungi, but it has been inherited from a phototrophic ancestor by horizontal gene transfer.

Obtaining DHA–EPA Oil Concentrates from the Biomass of Microalga Chlorella sorokiniana

Microalgae have attracted growing interest all around the world due to their potential applications in multiple sectors of industry, such as energetics, nutraceuticals, pharmaceuticals, agriculture, and ecology. Concepts of biorefinery of microalgae lipids for biodiesel production coupled with other applications have been suggested in several studies. However, very few studies focus on overcoming the degree of unsaturation of microalgae lipids using methods of fractionation. This study presents a method for obtaining two oil fractions from microalgae Chlorella sorokiniana suitable for food and biofuels via urea complex formation with further production of a long-chain PUFA concentrated oil suitable for the nutraceutical industry. A DHA–EPA-rich fraction was obtained from the dry microalga biomass using a succession of extraction, urea-complexation, fractionation, and esterification with glycerol. Analytical and organoleptic methods were used to assess the quality of the final product. Results show that the urea-complexation method allowed the obtaining of two lipid fractions with different fatty acid profiles. The urea complexed fraction (UCF) contained a majority of saturated fatty acids (54.46%); thus, it could find applications in the biofuels or food industry. The non-urea complexed fraction (NUCF) was rich in polyunsaturated fatty acids (PUFA) (81.00%), especially long-chain PUFA with 16.52% EPA and 35.08% DHA. The recovery rates of EPA and DHA in the NUCF reached 59% and 87.14%, respectively. Finally, the physicochemical and organoleptic characteristics of the DHA–EPA oil concentrate were determined and found conform to the norms recommended by the WHO/FAO standards for edible oils and the Russian State Standard GOST 1129-2013.

Effects of fatty acid synthase-inhibitors on polyunsaturated fatty acid production in marine diatom Fistulifera solaris JPCC DA0580

Omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA, C20:5ω-3) are essential for human health and fish growth especially in aquaculture sector. However, with the growing of aquaculture, the demand of PUFA supply also has been increasing. Fistulifera solaris, a marine diatom, is known for its ability to accumulate 65% of lipid content per dry cell weight, and can produce the high content of EPA. Thus, this diatom shows a great potential to be a feedstock of omega-3 PUFAs for fish feeds. In this study, in order to further understand and enhance the metabolism of PUFA biosynthesis in the diatom, the impacts of ketoacyl-ACP synthase (KAS) and ketoacyl-CoA synthase (KCS) inhibition on the PUFA production were analyzed by adding the specific inhibitors. KAS and KCS enzymes both play a role in the fatty acid elongation. As a result, the inhibition of KAS showed an increase in EPA content without arresting the cell growth. On the other hand, inhibition of KCS did not show a significant impact on the PUFA content in F.solaris. Our finding suggests that the specific suppression of KAS function can be a promising way to enhance the omega-3 PUFA production in F.solaris.

Crypthecodinium cohnii Growth and Omega Fatty Acid Production in Mediums Supplemented with Extract from Recycled Biomass.

Crypthecodinium cohnii is a marine heterotrophic dinoflagellate that can accumulate high amounts of omega-3 polyunsaturated fatty acids (PUFAs), and thus has the potential to replace conventional PUFAs production with eco-friendlier technology. So far, C. cohnii cultivation has been mainly carried out with the use of yeast extract (YE) as a nitrogen source. In the present study, alternative carbon and nitrogen sources were studied: the extraction ethanol (EE), remaining after lipid extraction, as a carbon source, and dinoflagellate extract (DE) from recycled algae biomass C. cohnii as a source of carbon, nitrogen, and vitamins. In mediums with glucose and DE, the highest specific biomass growth rate reached a maximum of 1.012 h−1, while the biomass yield from substrate reached 0.601 g·g−1. EE as the carbon source, in comparison to pure ethanol, showed good results in terms of stimulating the biomass growth rate (an 18.5% increase in specific biomass growth rate was observed). DE supplement to the EE-based mediums promoted both the biomass growth (the specific growth rate reached 0.701 h−1) and yield from the substrate (0.234 g·g−1). The FTIR spectroscopy data showed that mediums supplemented with EE or DE promoted the accumulation of PUFAs/docosahexaenoic acid (DHA), when compared to mediums containing glucose and commercial YE.

Sex Hormone-Dependent Lipid Mediator Formation in Male and Female Mice During Peritonitis.

Introduction: Sex differences in inflammation are obvious and contribute to divergences in the incidence and severity of inflammation-related diseases that frequently preponderate in women. Lipid mediators (LMs), mainly produced by lipoxygenase (LOX) and cyclooxygenase (COX) pathways from polyunsaturated fatty acids (PUFAs), regulate all stages of inflammation. Experimental and clinical studies revealed sex divergences for selected LM pathways without covering the entire LM spectrum, and only few studies have addressed the respective role of sex hormones. Here, we performed the comprehensive LM profile analysis with inflammatory peritoneal exudates and plasma from male and female mice in zymosan-induced peritonitis to identify the potential sex differences in LM biosynthesis during the inflammatory response. We also addressed the impact of sex hormones by employing gonadectomy. Methods: Adult male and female CD1 mice received intraperitoneal injection of zymosan to induce peritonitis, a well-established experimental model of acute, self-resolving inflammation. Mice were gonadectomized 5 weeks prior to peritonitis induction. Peritoneal exudates and plasma were taken at 4 (peak of inflammation) and 24 h (onset of resolution) post zymosan and subjected to UPLC–MS-MS–based LM signature profiling; exudates were analyzed for LM biosynthetic proteins by Western blot; and plasma was analyzed for cytokines by ELISA. Results: Pro-inflammatory COX and 5-LOX products predominated in the peritoneum of males at 4 and 24 h post-zymosan, respectively, with slightly higher 12/15-LOX products in males after 24 h. Amounts of COX-2, 5-LOX/FLAP, and 15-LOX-1 were similar in exudates of males and females. In plasma of males, only moderate elevation of these LMs was apparent. At 4 h post-zymosan, gonadectomy strongly elevated 12/15-LOX products in the exudates of males, while in females, free PUFA and LOX products were rather impaired. In plasma, gonadectomy impaired most LMs in both sexes at 4 h with rather up-regulatory effects at 24 h. Finally, elevated 15-LOX-1 protein was evident in exudates of males at 24 h which was impaired by orchiectomy without the striking impact of gonadectomy on other enzymes in both sexes. Conclusions: Our results reveal obvious sex differences and roles of sex hormones in LM biosynthetic networks in acute self-resolving inflammation in mice, with several preponderances in males that appear under the control of androgens.

Content, composition, and transfer of polyunsaturated fatty acids in an Arctic lake food web

AbstractFreshwater fish production depends on the production and use of polyunsaturated fatty acids (n‐3 and n‐6 PUFA) from lower trophic levels. Here, we aimed to identify the main trophic pathways that support PUFA content in different fish species (mean 39.7 mg/g dry weight) used in the subsistence fishery of the Inuit community in Greiner Lake near Cambridge Bay (Nunavut, Canada). We used stable isotope and taxon‐specific PUFA stocks, to show that the lake food web was divided into distinctive pelagic and littoral benthic food webs and that different fish species obtained their PUFA from different sources within those food webs. The most concentrated fish in n‐3 PUFA was Arctic char (Salvelinus alpinus) that obtained nutritionally valuable PUFA compounds by feeding on pelagic zooplankton rich in the essential fatty acids EPA and DHA and on littoral prey with lower PUFA content. The pelagic consumer, lake whitefish (Coregonus clupeaformis), that fed on mysids and zooplankton was also rich in n‐3 PUFA. The least concentrated in n‐3 PUFA was lake trout (Salvelinus namaycush) that obtained PUFA from low n‐3 PUFA sticklebacks (Pungitius pungitius) and macroinvertebrates and from n‐3 PUFA‐rich littoral mysids. The benthic PUFA were entirely made of n‐6 fatty acids and no n‐3 PUFA were detected. We further quantified that from the mean daily phytoplankton production of 319 mg C·m−2·d−1, 2.9% was assimilated by zooplankton (9.4 mg C·m−2·d−1) and thereby made available to pelagic fish. The food webs to which fish belonged were supported by PUFA produced in the pelagic and benthic zones but likely complemented by inputs from the watershed. The description of the main PUFA pathways of the Greiner Lake food webs explains for the first time the trophic interactions and underlying mechanisms responsible for the health of the fish community in a high‐Arctic lake.