Production Of Polyunsaturated Fatty Acids Research Articles

Production of Omega-3 Fatty Acids from the Microalga Crypthecodinium cohnii by Utilizing Both Pentose and Hexose Sugars from Agricultural Residues

The core objective of this work was to take advantage of the unexploited wheat straw biomass, currently considered as a broadly available waste stream from the Greek agricultural sector, towards the integrated valorization of sugar streams for the microbial production of polyunsaturated omega-3 fatty acids (PUFAs). The OxiOrganosolv pretreatment process was applied using acetone and ethanol as organic solvents without any additional catalyst. The results proved that both cellulose-rich solid pulp and hemicellulosic oligosaccharides-rich aqueous liquid fraction after pretreatment can be efficiently hydrolyzed enzymatically, thus resulting in high yields of fermentable monosaccharides. The latter were supplied as carbon sources to the heterotrophic microalga Crypthecodinium cohnii for the production of PUFAs, more specifically docosahexaenoic acid (DHA). The solid fractions consisted mainly of hexose sugars and led to higher DHA productivity than their pentose-rich liquid counterparts, which can be attributed to the different carbon source and C/N ratio in the two streams. The best performance was obtained with the solid pulp pretreated with ethanol at 160 °C for 120 min and an O2 pressure of 16 bar. The total fatty acids content reached 70.3 wt% of dried cell biomass, of which 32.2% was DHA. The total DHA produced was 7.1 mg per g of untreated wheat straw biomass.

Comparative Life Cycle Assessment of EPA and DHA Production from Microalgae and Farmed Fish

The present study aims at comparing the life cycle environmental impacts of polyunsaturated fatty acids production (PUFA) from microalgae and farmed fish. PUFA production from microalgae cultivated via heterotrophy and photoautotrophy was assessed and compared. The primary energy demand (PED) and environmental impacts (EI) of PUFA production from microalgae via heterotrophy were significantly lower compared to PUFA produced via photoautotrophy. Furthermore, PED and EI of PUFA production from fish farmed in marine net pens were assessed. The results indicated that the PED and EI of PUFA production from farmed fish are higher than that produced from microalgae cultivated via heterotrophy. Therefore, the results suggest that PUFA produced from microalgae via heterotrophy could substitute fish oil from an environmental perspective. Furthermore, life cycle analysis results indicate that PUFA derived from microalgae could potentially replace fish oil in the fish feed, thus reducing the pressure on oceans.

Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium Microcystis.

Cyanobacteria dominance and warming have been suggested to decrease the production of polyunsaturated fatty acids (PUFA) in freshwater ecosystems. Physiological adaptations of poikilothermic animals to higher temperatures may further decrease PUFA levels in aquatic food webs. We conducted diet manipulation experiments to investigate the combined effects of dietary PUFA and warming on the proportions of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) in Chironomus riparius. The experimental diet consisted of a nontoxic cyanobacterium Microcystis, which contained C20 PUFA: 20:3n-3, 20:4n-3, and 20:3n-6, but no EPA or ARA. Additionally, we used TetraMin® fish flakes as a control treatment. A temperature increase from 20 °C to 25 °C decreased the proportion of n-3 C20 PUFA and the n-3/n-6 ratio in Microcystis. Diet manipulation experiments indicated that Chironomus desaturated dietary C20 precursors to EPA and ARA, but warming decreased this bioconversion and resulted in lower levels of EPA and ARA in Chironomus. Warming did not alter the proportions of EPA and ARA in Chironomus larvae if these PUFA were readily available in the diet (TetraMin® control treatment). In conclusion, warming and cyanobacteria dominance may decrease the production and trophic transfer of physiologically important PUFA in freshwaters by (1) decreasing the n-3/n-6 ratio and the abundance of n-3 C20 precursors in Microcystis, and (2) decreasing the bioconversion of n-3 and n-6 C20 precursors to EPA and ARA in chironomids. These changes may have cascading effects throughout the food web and decrease the content of EPA in fish, potentially affecting its availability to humans.

A new culture medium based on genetic algorithms for Isochrysis galbana production relevant to hatcheries

The nutrient content of a commercial seawater culture medium for growing the microalga Isochrysis galbana was optimized using a stochastic strategy based on genetic algorithms. For this, 210 experiments spread over seven generations were carried out. This strategy reduced the number of assays by more than 90% compared to a factorial design involving the optimization of twelve nutrients simultaneously. The optimized medium outperformed the reference medium in all aspects. The genetic algorithm strategy achieved a polyunsaturated fatty acids (PUFAs) productivity of 7.8 mg L−1 day−1 in a continuous culture of I. galbana, corresponding to an increase of 15% compared to the commercial formulation. Carotenoids, on the other hand, increased by 50% d.w. In addition, PUFA yields were significantly improved, which allowed us to reduce the requirement of several nutrients, for instance, N (25%), Mo (20%), Mn (60%), Co (60%), and Cu (60%).

Effect of fatty acid saturation on gel properties of salt-soluble protein in pork.

The objective of this study was to evaluate the effect of fatty acid saturation (oleic acid, linoleic acid, and linolenic acid) on water distribution, migration, and gel properties of pork salt-soluble protein, by detected indicators that are Low field nuclear magnetic resonance (LF-NMR), magnetic resonance imaging (MRI), water-holding capacity (WHC), and gel strength. These results suggested that the WHC and gel strength decreased with the decrease of fatty acid saturation (p<0.05). LF-NMR analysis revealed that the relaxation time T21 and T22 decrease (p<0.05) with the decrease of fatty acid saturation. Results also showed that the T21 increased and T23 decreased in linolenic acid group compared with oleic acid group. Meanwhile, the peak area ratio of P21 and P22 decreased (p<0.05), while P23 increased (p<0.05). Therefore, the saturation of fatty acids had a great influence on the gel properties of protein. PRACTICAL APPLICATION: It provides a theoretical basis for the production of polyunsaturated fatty acids emulsified gel meat products and promotes the development of meat processing industry.

Effect of sucrose on the fatty acid metabolism of adventitious root cultures in vitro of Stevia rebaudiana

In this study, the effect of sucrose on the neutral lipid profile of adventitious root cultures of Stevia rebaudiana was evaluated. The cultures were obtained employing a roller bottle system. In this system, Schott-type flasks were used, which contained Murashige and Skoog liquid medium at 33.3% strength (MS/3) supplemented with 30, 60, and 80 g L-1 of sucrose, respectively, and 10.7 mM 1-naphthaleneacetic acid (NAA). The spectroscopic analyzes showed that the portion of polyunsaturated fatty acids (PUFAs) was highest in roots treated with 30 g L-1 of sucrose. The spectrometric analyzes showed that the palmitic acid was found to be present in relatively higher amounts in the roots submitted to the MS/3-30 g L-1 (31.9%) and MS/3-60 g L-1 (29.5%) sucrose treatments, and lower in the treatment with MS/3-80 g L-1 (28.8%) of sucrose. Also, the treatment using 30 g L-1 of sucrose was the best for obtaining unsaturated fatty acids (UFAs) in the culture, with a relative percentage of 62.9%. Our results indicate that the MS medium that received 30 g L-1 of sucrose induced a lesser abiotic stress condition, which favored PUFAs production in the adventitious root cultures of S. rebaudiana.

Optimization of docosahexaenoic acid production by Schizochytrium SP. – A review

Microorganisms are becoming increasingly popular as a source of raw materials for the production of food for humans and feed for animals. These raw materials are usually associated with a relatively high price due to the still low efficiency of microorganisms biomass production. The fall in prices is inextricably linked to the optimization of the production process, specific for each species. The aim of this review is to summarize the results of research for the optimization of oil production from Schizochytrium sp., with a strong emphasis on the production of long-chain omega-3 polyunsaturated fatty acids. This genus is related to a high percentage of docosahexaenoic acid (DHA) in the composition of fatty acids, with relatively high concentration of dry matter per liter of medium. Optimization of DHA production involves the use of appropriate source and concentration of carbon and nitrogen, providing the microorganisms with optimal growth environment, which consists of pH, oxygenation, water temperature, salinity and medium fluid dynamics.

Function of ORFC of the polyketide synthase gene cluster on fatty acid accumulation in Schizochytrium limacinum SR21

BackgroundAs a potential source of polyunsaturated fatty acids (PUFA), Schizochytrium sp. has been widely used in industry for PUFA production. Polyketide synthase (PKS) cluster is supposed to be the primary way of PUFA synthesis in Schizochytrium sp. As one of three open reading frames (ORF) in the PKS cluster, ORFC plays an essential role in fatty acid biosynthesis. However, the function of domains in ORFC in the fatty acid synthesis of Schizochytrium sp. remained unclear.ResultsIn this study, heterologous expression and overexpression were carried out to study the role of ORFC and its domains in fatty acid accumulation. Firstly, ORFC was heterologously expressed in yeast which increased the PUFA content significantly. Then, the dehydratase (DH) and enoyl reductase (ER) domains located on ORFC were overexpressed in Schizochytrium limacinum SR21, respectively. Fatty acids profile analysis showed that the contents of PUFA and saturated fatty acid were increased in the DH and ER overexpression strains, respectively. This indicated that the DH and ER domains played distinct roles in lipid accumulation. Metabolic and transcriptomic analysis revealed that the pentose phosphate pathway and triacylglycerol biosynthesis were enhanced, while the tricarboxylic acid cycle and fatty acids oxidation were weakened in DH-overexpression strain. However, the opposite effect was found in the ER-overexpression strain.ConclusionTherefore, ORFC was required for the biosynthesis of fatty acid. The DH domain played a crucial role in PUFA synthesis, whereas the ER domain might be related to saturated fatty acids (SFA) synthesis in Schizochytrium limacinum SR21. This research explored the role of ORFC in the PKS gene cluster in Schizochytrium limacinum and provided potential genetic modification strategies for improving lipid production and regulating PUFA and SFA content.

Intestinal Microbial-tissue Complex and Chronic Heart Failure (part 1): Pathogenesis

Antigenic and metabolic integration of the intestinal microbiota into the homeostasis of the human body is a factor that claims to play a key role in the pathogenesis of cardiovascular diseases. It acquires special significance against the background of the decrease in blood circulation and congestion in the digestive system during chronic heart failure. Aim of the review is analysis and synthesis of studies results on the role of intestinal microbiocenosis in the pathogenesis of heart remodeling and chronic heart failure. The search for articles was conducted in databases eLIBRARY.RU and Medline for the key terms "gut microbiota (microbiome, microbiocenosis)", "dysbiosis (dysbacteriosis)", "excessive bacterial growth syndrome", "lipopolysaccharide (endotoxin)", "trimethylamine-N-oxide" in combination with the terms "heart failure", "myocardial remodeling", "myocardium" in Russian and English, respectively. We selected articles containing the results of clinical and experimental studies published from 1995 to 2020. Review articles were considered only on the subject of the cited original publications. Most researchers have established the relationship between chronic heart failure and dysfunction and changes in the qualitative and quantitative composition of intestinal microbiocenosis. As negative changes, it is customary to note the proliferation of gram-negative opportunistic bacteria with concomitant endotoxinemia and a decrease in the pool of commensal microbiota. The available data suggest that the participation of the intestinal microbial-tissue complex in the pathogenesis of chronic heart failure and heart remodeling is realized through the activation of a local and then systemic inflammatory response, accompanied by cardiodepressive action of pro-inflammatory cytokines and universal proliferation factors, an imbalance of matrix metalloproteinases and their inhibitors, the initiation of apoptosis, fibrosis, and loss of contractile myocardium. Besides, a decrease in the production of short-chain and polyunsaturated fatty acids and vitamins by the commensal microbiota may be associated with changes in the electrical properties of cardiomyocyte membranes, a decrease in the systolic function of the left ventricle of the heart, and an increase in the risk of sudden cardiac death. It's also shown that the direct cardiotoxic effect of microbial molecules (lipopolysaccharides, peptidoglycans, trimethylamine-N-oxide, etc.), which interact with the receptors of cardiomyocytes and microenvironment cells, can cause the development of myocardial remodeling and its dysfunction. Recent studies have established mechanisms of myocardial remodeling mediated by microbial molecules, which may be associated with new strategies for the treatment and prevention of heart failure.

Optimization of Polyunsaturated Fatty Acids (PUFAs) Production from Olive Cake by Pseudomonas fluorescens NBRC14160 using Response Surface Methodology and their Application in Kareish Cheese Manufacture

The aim of this study was to optimize the production of polyunsaturated fatty acids (PUFAs), using use the response surface methodology (RSM), to use the produced PUFAs in kareish cheese processing. Plackett Burman design (PBD) was employed to screen media components that affect PUFAs development (glucose, olive cake, yeast extract, tryptone, MgSO4, KH2PO4, NH4Cl, agitation speed, incubation time, and pH), and results showed that olive cake and yeast extract, with confidence level > 98%, had a positive effect on PUFAs production. The central composite design (CCD) of the response surface methodology was used to optimize the selected parameters levels where maximum PUFAs production (1790 mg/l) was observed near the mid-point (0) values (concentrations) of olive cake (15 g/l), tryptone (7.5 g/L) and KH2PO4 (1.25 g/l). Polyunsaturated fatty acids account for 47.83 % of the total fatty acid profile, according to gas chromatography analysis of the collected PUFAs. The produced PUFAs was encapsulated using whey protein concentrate and maltodextrin, freeze dried, grinded and incorporated in Kareish cheese manufacture. The average particle size of a 0.005% suspension of oil microcapsules was 671.4 nm with a poly dispersity index of 0.611 indicating a moderate stability of the emulsion. The negative zeta potential of the microcapsules particles was -37.6 mv, which is identical to the -42 mv value recorded in the literature for oil emulsions stabilized by whey protein, maltodextrin, and K-carrageenan. The addition of 0.5 % PUFAs-containing microcapsules to Kareish cheese increased antioxidative activity to 38.13 % compared to 30.14 % for the control, as well as Texture profile analysis (TPA) parameters including hardness, cohesiveness, gumminess, and chewiness. The elasticity of the Kareish cheese sample increased slightly by the addition of 0.5% microcapsules, but higher concentration tended to change the elasticity to a brittleness of the cheese structure.

Effects of light intensity on the production of phycoerythrin and polyunsaturated fatty acid by microalga Rhodomonas salina

Phycoerythrin (PE) is a phycobiliprotein with great potential in food, pharmaceuticals, and cosmetics applications. This work sought to investigate the effects of lighting conditions on the PE synthesis by the alga Rhodomonas salina. It was found that the effects of light intensity on the cell growth and PE synthesis highly depend on the cell density, and ultimately, the number of photons received per unit of cells. No obvious light limitation or inhibition to cell growth was observed when each cell received the photons within the range of 2.4–28 × 10−9 μmol·s−1. Under low light intensity, R. salina increased the PE synthesis in order to capture more photons to compensate light deficiency. A strategy of stepwise increasing light intensity was developed to capture the rapid cell growth and high PE synthesis. The PE titer with this method reached 32 mg L−1, ~20% higher than that obtained at a fixed light intensity of 250 μmol photon flux m−2 s−1 (μmol·m−2·s−1). In addition to PE synthesis, R. salina also produces an appreciable amount of omega-3 polyunsaturated fatty acids (PUFAs) with stearidonic acid (SDA, C18:4) in particular. Collectively, this work demonstrates that light intensity plays an important role in the culture of R. salina for simultaneous production of PE and PUFAs.

Chemical Characterization, Antiproliferative and Antioxidant Activities of Polyunsaturated Fatty Acid-Rich Extracts from Chlorella sp. S14.

Microalgae is a rich source of polyunsaturated fatty acid. This study was conducted to identify and isolate microalgal strain with the potentials for producing polyunsaturated fatty acids (PUFAs) and determine its cytotoxic effect on some cancer cells. The algal strain (Chlorella sp. S14) was cultivated using modified BG-11 media, and algal biomass obtained was used for fatty acid extraction. Gas chromatographic–mass spectrometry was used to identify and quantify the levels of the fatty acid constituents. The total content of monounsaturated fatty acids (1.12%) was low compared to polyunsaturated fatty acids (PUFAs) (52.87%). Furthermore, n-3 PUFAs accounted for (12.37%) of total PUFAs with the presence of α-linolenic acid (2.16%) and cis-11,14,17-eicosatrienoic acid (2.16%). The PUFA-rich extract did not exhibit a cytotoxic effect on normal cells. Treatment with the PUFA-rich extract (150 µg/mL) significantly reduced cell viability in MCF-7 (31.58%) and A549 (62.56%) cells after the 48 h treatment. Furthermore, treatment of MCF-7 with fatty acid extracts (125 and 150 µg/mL) showed a significant reduction in MDA levels, increase in catalase activities and decrease in GSH level compared to untreated cells. However, a slight decrease in MDA level was observed in A549 cells after the 48 h treatment. There are no significant changes in catalase activities and GSH level in treated A549 cells. However, a slight reduction of NO levels was observed in treated MCF-7 and A549 cells. These results indicate the potentials of PUFA-rich extracts from Chlorella sp. S14 to reduce viability and modulate redox status in A549 and MCF-7 cells.

Regulation of hepatic coenzyme Q biosynthesis by dietary omega-3 polyunsaturated fatty acids

Dietary fats are important for human health, yet it is not fully understood how different fats affect various health problems. Although polyunsaturated fatty acids (PUFAs) are generally considered as highly oxidizable, those of the n-3 series can ameliorate the risk of many age-related disorders. Coenzyme Q (CoQ) is both an essential component of the mitochondrial electron transport chain and the only lipid-soluble antioxidant that animal cells can synthesize. Previous work has documented the protective antioxidant properties of CoQ against the autoxidation products of PUFAs. Here, we have explored in vitro and in vivo models to better understand the regulation of CoQ biosynthesis by dietary fats. In mouse liver, PUFAs increased CoQ content, and PUFAs of the n-3 series increased preferentially CoQ10. This response was recapitulated in hepatic cells cultured in the presence of lipid emulsions, where we additionally demonstrated a role for n-3 PUFAs as regulators of CoQ biosynthesis via the upregulation of several COQ proteins and farnesyl pyrophosphate levels. In both models, n-3 PUFAs altered the mitochondrial network without changing the overall mitochondrial mass. Furthermore, in cellular systems, n-3 PUFAs favored the synthesis of CoQ10 over CoQ9, thus altering the ratio between CoQ isoforms through a mechanism that involved downregulation of farnesyl diphosphate synthase activity. This effect was recapitulated by both siRNA silencing and by pharmacological inhibition of farnesyl diphosphate synthase with zoledronic acid. We highlight here the ability of n-3 PUFAs to regulate CoQ biosynthesis, CoQ content, and the ratio between its isoforms, which might be relevant to better understand the health benefits associated with this type of fat. Additionally, we identify for the first time zoledronic acid as a drug that inhibits CoQ biosynthesis, which must be also considered with respect to its biological effects on patients.

Altered lipid metabolism marks glioblastoma stem and non-stem cells in separate tumor niches

Glioblastoma (GBM) displays marked cellular and metabolic heterogeneity that varies among cellular microenvironments within a tumor. Metabolic targeting has long been advocated as a therapy against many tumors including GBM, but how lipid metabolism is altered to suit different microenvironmental conditions and whether cancer stem cells (CSCs) have altered lipid metabolism are outstanding questions in the field. We interrogated gene expression in separate microenvironments of GBM organoid models that mimic the transition between nutrient-rich and nutrient-poor pseudopalisading/perinecrotic tumor zones using spatial-capture RNA-sequencing. We revealed a striking difference in lipid processing gene expression and total lipid content between diverse cell populations from the same patient, with lipid enrichment in hypoxic organoid cores and also in perinecrotic and pseudopalisading regions of primary patient tumors. This was accompanied by regionally restricted upregulation of hypoxia-inducible lipid droplet-associated (HILPDA) gene expression in organoid cores and pseudopalisading regions of clinical GBM specimens, but not lower-grade brain tumors. CSCs have low lipid droplet accumulation compared to non-CSCs in organoid models and xenograft tumors, and prospectively sorted lipid-low GBM cells are functionally enriched for stem cell activity. Targeted lipidomic analysis of multiple patient-derived models revealed a significant shift in lipid metabolism between GBM CSCs and non-CSCs, suggesting that lipid levels may not be simply a product of the microenvironment but also may be a reflection of cellular state. CSCs had decreased levels of major classes of neutral lipids compared to non-CSCs, but had significantly increased polyunsaturated fatty acid production due to high fatty acid desaturase (FADS1/2) expression which was essential to maintain CSC viability and self-renewal. Our data demonstrate spatially and hierarchically distinct lipid metabolism phenotypes occur clinically in the majority of patients, can be recapitulated in laboratory models, and may represent therapeutic targets for GBM.

Genetic Suppression of Lethal Mutations in Fatty Acid Biosynthesis Mediated by a Secondary Lipid Synthase.

ABSTRACTThe biosynthesis and incorporation of polyunsaturated fatty acids into phospholipid membranes are unique features of certain marine Gammaproteobacteria inhabiting high-pressure and/or low-temperature environments. In these bacteria, monounsaturated and saturated fatty acids are produced via the classical dissociated type II fatty acid synthase mechanism, while omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) are produced by a hybrid polyketide/fatty acid synthase—encoded by the pfa genes—also referred to as the secondary lipid synthase mechanism. In this work, phenotypes associated with partial or complete loss of monounsaturated biosynthesis are shown to be compensated for by severalfold increased production of polyunsaturated fatty acids in the model marine bacterium Photobacterium profundum SS9. One route to suppression of these phenotypes could be achieved by transposition of insertion sequences within or upstream of the fabD coding sequence, which encodes malonyl coenzyme A (malonyl-CoA) acyl carrier protein transacylase. Genetic experiments in this strain indicated that fabD is not an essential gene, yet mutations in fabD and pfaA are synthetically lethal. Based on these results, we speculated that the malonyl-CoA transacylase domain within PfaA compensates for loss of FabD activity. Heterologous expression of either pfaABCD from P. profundum SS9 or pfaABCDE from Shewanella pealeana in Escherichia coli complemented the loss of the chromosomal copy of fabD in vivo. The co-occurrence of independent, yet compensatory, fatty acid biosynthetic pathways in selected marine bacteria may provide genetic redundancy to optimize fitness under extreme conditions.IMPORTANCE A defining trait among many cultured piezophilic and/or psychrophilic marine Gammaproteobacteria is the incorporation of both monounsaturated and polyunsaturated fatty acids into membrane phospholipids. The biosynthesis of these different classes of fatty acid molecules is linked to two genetically distinct co-occurring pathways that utilize the same pool of intracellular precursors. Using a genetic approach, new insights into the interactions between these two biosynthetic pathways have been gained. Specifically, core fatty acid biosynthesis genes previously thought to be essential were found to be nonessential in strains harboring both pathways due to functional overlap between the two pathways. These results provide new routes to genetically optimize long-chain omega-3 polyunsaturated fatty acid biosynthesis in bacteria and reveal a possible ecological role for maintaining multiple pathways for lipid synthesis in a single bacterium.

Screening the rate-limiting genes in the ω6 polyunsaturated fatty acid biosynthesis pathway in Nannochloropsis oceanica

The enrichment of polyunsaturated fatty acids has made Nannochloropsis sp. a promising candidate for the production of polyunsaturated fatty acids. Although most of the genes involved in polyunsaturated fatty acid biosynthesis have been cloned, the regulatory mechanism at the molecular level has not been elucidated. To target the rate-limiting genes in the ω6 polyunsaturated fatty acid biosynthesis pathway in Nannochloropsis oceanica, we performed the following experiments. The function of the Δ9 fatty acid desaturase gene of N. oceanica was verified in Saccharomyces cerevisiae with a substrate preference for stearic acid. With gas chromatography–mass spectrometry (GC–MS) analysis, the fatty acid profiles in N. oceanica under different stress conditions (high nitrogen, low nitrogen, high temperature, and low temperature) were measured. The results showed that high nitrogen and low temperature stresses played significant roles in promoting polyunsaturated fatty acid biosynthesis. In contrast, low nitrogen and high temperature stresses were beneficial for the accumulation of monounsaturated fatty acids. We further measured the transcriptional abundances of all six genes in the ω6 polyunsaturated fatty acid biosynthesis pathway in N. oceanica and found that the Δ6 fatty acid elongase and the Δ12, Δ5, and Δ17 fatty acid desaturase genes were more sensitive to the stresses set in this study. Pearson correlation analysis showed that the Δ9 fatty acid desaturase was significantly associated with monounsaturated fatty acid biosynthesis, while Δ12, Δ5, and Δ17 fatty acid desaturases were proposed to be the rate-limiting enzymes in polyunsaturated fatty acid biosynthesis. This study helps to thoroughly elucidate the responses of N. oceanica to nitrogen and temperature stresses and optimize cultivation for high yield and quality of polyunsaturated fatty acids. More importantly, the selected rate-limiting genes may benefit further genetic engineering in N. oceanica.

Nordic cyanobacterial and algal lipids: Triacylglycerol accumulation, chemotaxonomy and bioindustrial potential.

The ability to capture and convert sunlight, water and nutrients into useful compounds make photosynthetic microbes ideal candidates for the bio-industrial factories of the future. However, the suitability of isolates from temperate regions to grow under Nordic conditions is questionable. In this work, we explore the chemotaxonomy of Nordic strains of cyanobacteria and one green alga and evaluate their potential as raw materials for the production of lipid-based bio-industrial compounds. Thin-layer chromatography was used to identify the presence of triacylglycerol, which were detected in the majority of strains. Fatty acid methyl ester profiles were analysed to determine the suitability of strains for the production of biodiesel or the production of polyunsaturated fatty acids for the nutraceutical industry. The Nordic Synechococcus strains were unique in demonstrating fatty acid profiles comprised mostly C14:0, C16:0 and C16:1 and lacking polyunsaturated fatty acids. These properties translated to superior predicted biodiesel qualities, including cetane number, cold filter plugging point and oxidative stability compared to the other evaluated strains. Polyunsaturated fatty acids were detected at high levels (38-53%), with Calothrix sp. 336/3 being abundant in two essential fatty acids, linoleic and alpha-linolenic acid (21 and 17%, respectively). Gamma-linoleic acid was the predominant polyunsaturated fatty acid for the remaining strains (13-21%). In addition to assessing the potential of Nordic strains for bio-industrial production, this work also discusses issues such as taxonomy and predictive modelling, which can affect the identification of prospective high-performing strains.

Characteristics of Metabolites by Seed-Specific Inhibition of FAD2 in Brassica napus L

Fatty acid desaturase-2 (FAD2) is a key enzyme in the production of polyunsaturated fatty acids in plants. RNAi technology can reduce the expression of FAD2 genes in Brassica napus seeds and acquire transgenic B. napus plants with a high oleic acid content, but the effect of seed-specific inhibition of FAD2 expression on B. napus seed metabolites is not clear. Here we use widely targeted metabolomics to investigate the metabolites of normal-oleic-acid rapeseed (OA) and high-oleic-acid rapeseed (HOA) seeds, resulting in a total of 726 metabolites being detected. Among them, 24 differential metabolites were significantly downregulated and 88 differential metabolites were significantly upregulated in HOA rapeseed. In further lipid profile experiments, more lipids in B. napus seeds were accurately quantified. The contents of glycolipids and phospholipids that contain C18:1 increased significantly and C18:2 decreased because FAD2 expression was inhibited. The changes in the expression of key genes in related pathways were also consistent with the changes in metabolites. The insertion site of the ihpRNA plant expression vector was reconfirmed through genomewide resequencing, and the transgenic event did not change the sequence of FAD2 genes. There was no significant difference in the germination rate and germination potential between OA and HOA rapeseed seeds because the seed-specific ihpRNA plant expression vector did not affect other stages of plant growth. This work provides a theoretical and practical guidance for subsequent molecular breeding of high OA B. napus.

Elovl5 Expression in the Central Nervous System of the Adult Mouse.

ELOVL5 (Elongase of Very-Long Fatty Acid 5) gene encodes for an enzyme that elongates long chain fatty acids, with a marked preference for polyunsaturated molecules. In particular, it plays an essential role in the elongation of omega-3 and omega-6 fatty acids, precursors for long-chain polyunsaturated fatty acids (PUFAs). Mutations of ELOVL5 cause the spino-cerebellar ataxia type 38 (SCA38), a rare autosomal neurological disease characterized by gait abnormality, dysarthria, dysphagia, hyposmia and peripheral neuropathy, conditions well represented by a mouse model with a targeted deletion of this gene (Elovl5–/– mice). However, the expression pattern of this enzyme in neuronal and glial cells of the central nervous system (CNS) is still uninvestigated. This work is aimed at filling this gap of knowledge by taking advantage of an Elovl5-reporter mouse line and immunofluorescence analyses on adult mouse CNS sections and glial cell primary cultures. Notably, Elovl5 appears expressed in a region- and cell type-specific manner. Abundant Elovl5-positive cells were found in the cerebellum, brainstem, and primary and accessory olfactory regions, where mitral cells show the most prominent expression. Hippocampal pyramidal cells of CA2/CA3 where also moderately labeled, while in the rest of the telencephalon Elovl5 expression was high in regions related to motor control. Analysis of primary glial cell cultures revealed Elovl5 expression in oligodendroglial cells at various maturation steps and in microglia, while astrocytes showed a heterogeneous in vivo expression of Elovl5. The elucidation of Elovl5 CNS distribution provides relevant information to understand the physiological functions of this enzyme and its PUFA products, whose unbalance is known to be involved in many pathological conditions.

Co-expressing Eranthis hyemalis lysophosphatidic acid acyltransferase 2 and elongase improves two very long chain polyunsaturated fatty acid production in Brassica carinata

Docosadienoic acid (DDA, 22:2–13,16) and docosatrienoic acid (DTA, 22:3–13,16,19) are two very long chain polyunsaturated fatty acids (VLCPUFAs) that are recently shown to possess strong anti-inflammatory and antitumor properties. An ELO type elongase (EhELO1) from wild plant Eranthis hyemalis can synthesize the two fatty acids by sequential elongation of linoleic acid and alpha-linolenic acid, respectively. Seed-specific expression of this gene in oilseed crop Brassica carinata produced a considerable amount of DDA and DTA in transgenic seeds. However, these fatty acids were excluded from the sn-2 position of triacylglycerols (TAGs). To improve the production level and nutrition value of the VLCPUFAs in the transgenic oilseed crop, a cytoplasmic lysophosphatidic acid acyltransferase (EhLPAAT2) for the incorporation of the two fatty acids into the sn-2 position of triacylglycerols was identified from E. hyemalis. RT-PCR analysis showed that it was preferentially expressed in developing seeds where EhELO1 was exclusively expressed in E. hyemalis. Seed specific expression of EhLPAAT2 along with EhELO1 in B. carinata resulted in the effective incorporation of DDA and DTA at the sn-2 position of TAGs, thereby increasing the total amount of DDA and DTA in transgenic seeds. To our knowledge, this is the first plant LPAAT that can incorporate VLCPUFAs into TAGs. Improved production of DDA and DTA in the oilseed crop using EhLPAAT2 and EhELO1 provides a real commercial opportunity for high value agriculture products for nutraceutical uses.