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ABSTRACT Fatty acid desaturase (FAD) is essential for plant growth and development and plant defence response. Although flax (Linum usitatissimum L.) is an important oil and fibre crop, but its FAD gene remains understudied. This study identified 43 LuFAD genes in the flax genome. The phylogenetic analysis divided the FAD genes into seven subfamilies. LuFAD is unevenly distributed on 15 chromosomes, and fragment duplication is the only driving force for the amplification of the LuFAD gene family. In the LuFAD gene promoter region, most elements respond to plant hormones (MeJA, ABA) and abiotic stresses (anaerobic and low temperature). The expression pattern analysis showed that the temporal and spatial expression patterns of all LuFAD genes in different tissues and the response patterns to abiotic stresses (heat and salt) were identified. Subcellular localisation showed that all LuFAD2‐GFP were expressed in the endoplasmic reticulum membrane. RT‐qPCR analysis revealed that LuFAD2 was significantly upregulated under cold, salt and drought stress, and its overexpression in Arabidopsis thaliana enhanced cold tolerance genes and reduced ROS accumulation. This study offers key insights into the FAD gene family's role in flax development and stress adaptation. [ABSTRACT FROM AUTHOR]

The adaptation of marine fish to freshwater environments includes prodigious examples of rapid evolution.Given the scarcity of ω‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA) in freshwater, we expect selection to be strong on fish transitioning to freshwater habitats and yet the underlying ecological causes of genomic and phenotypic differentiation are poorly understood for traits associated with lipid content and composition. Threespine stickleback Gasterosteus aculeatus have repeatedly colonized, and adapted to, freshwater habitats across the Northern Hemisphere. These freshwater populations often show elevated copy number of the fatty acid desaturase 2 gene (FADS2), which increases the biosynthetic capacity of LC‐PUFA. The starkly lower content of LC‐PUFA in freshwater compared to marine prey, especially docosahexaenoic acid (DHA), likely imposes strong positive selection on freshwater fish for either increased biosynthesis or greater dietary acquisition of LC‐PUFA. The recently colonized and relatively undisturbed threespine stickleback populations in postglacial coastal lakes of southern Greenland offer an exceptional opportunity to study how variation in the copy number of FADS2 is related to abiotic and biotic conditions of lakes and their morphometry. As expected, given its position on the stickleback X chromosome, we found strong sexual dimorphism in FADS2 copy number in all populations (19 freshwater, 1 marine and 1 brackish), and an increased dimorphism in some freshwater populations. We also found that FADS2 copy number was negatively correlated, for both males and females, with the abundance of copepods, which are a DHA‐rich food source in the zooplankton community. Overall, our results suggest that the prey community context of lakes might influence the process of metabolic adaptation of marine fish colonizing freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Understanding fungal lipid biology and metabolism is critical for antifungal target discovery as lipids play central roles in cellular processes. Nuances in lipid structural differences can significantly impact their functions, making it necessary to characterize lipids in detail to understand their roles in these complex systems. In particular, lipid double bond (DB) locations are an important component of lipid structure that can only be determined using a few specialized analytical techniques. Ozone‐induced dissociation mass spectrometry (OzID‐MS) is one such technique that uses ozone to break lipid DBs, producing pairs of characteristic fragments that allow the determination of DB positions. In this work, we apply OzID‐MS and LipidOz software to analyze the complex lipids of Saccharomyces cerevisiae yeast strains transformed with different fatty acid desaturases from Histoplasma capsulatum to determine the specific unsaturated lipids produced. The automated data analysis in LipidOz made the determination of DB positions from this large dataset more practical, but manual verification for all targets was still time‐consuming. The DL model reduces manual involvement in data analysis, but since it was trained using mammalian lipid extracts, the prediction accuracy on yeast‐derived data was reduced. We addressed both shortcomings by retraining the DL model to act as a pre‐filter to prioritize targets for automated analysis, providing confident manually verified results but requiring less computational time and manual effort. Our workflow resulted in the determination of detailed DB positions and enzymatic specificity. [ABSTRACT FROM AUTHOR]

The spectral composition of light is an important factor for the metabolism of photosynthetic organisms. Several blue light‐regulated metabolic processes have already been identified in the industrially relevant microalga Monoraphidium braunii. However, little is known about the spectral impact on this species' growth, fatty acid (FA), and pigment composition. In this study, M. braunii was cultivated under different light spectra (white light: 400–700 nm, blue light: 400–550 nm, green light: 450–600 nm, and red light: 580–700 nm) at 25°C for 96 h. The growth was monitored daily. Additionally, the FA composition, and pigment concentration was analyzed after 96 h. The highest biomass production was observed upon white light and red light irradiation. However, green light also led to comparably high biomass production, fueling the scientific debate about the contribution of weakly absorbed light wavelengths to microalgal biomass production. All light spectra (white, blue, and green) that comprised blue‐green light (450–550 nm) led to a higher degree of FA unsaturation and a greater concentration of all identified pigments than red light. These results further contribute to the growing understanding that blue‐green light is an essential trigger for maximized pigment concentration and FA unsaturation in green microalgae. [ABSTRACT FROM AUTHOR]

Background: Extracellular vesicles in human milk are critical in supporting newborn growth and development. Bioavailability of dietary extracellular vesicles may depend on the composition of membrane lipids. Single‐nucleotide polymorphisms (SNPs) in the fatty acid desaturase gene cluster impact the content of long‐chain polyunsaturated fatty acids in human milk phospholipids. This study investigated the relation between variation in FADS1 and FADS2 with the content of polyunsaturated fatty acids in extracellular vesicles from human milk. Methods: Milk was obtained from a cohort of mothers (N = 70) at 2–4 weeks of lactation. SNPs in the FADS gene locus were determined using pyrosequencing for rs174546 in FADS1 and rs174575 in FADS2. Quantitative lipidomic analysis of polyunsaturated fatty acids in human milk and extracellular vesicles from human milk was completed by gas chromatography–mass spectrometry. Results: The rs174546 and rs174575 genotypes were independent predictors of the arachidonic acid content in extracellular vesicles. The rs174546 genotype also predicted eicosapentaenoic acid and docosahexaenoic acid in extracellular vesicles. The reduced content of long‐chain polyunsaturated fatty acids in extracellular vesicles in human milk may be due to lower fatty acid desaturase activity in mothers who are carriers of the A allele in rs174546 or the G allele in rs174575. Conclusion: The polyunsaturated fatty acid composition of milk extracellular vesicles is predicted by the FADS genotype. These findings yield novel insights regarding extracellular vesicle content and composition that can inform the design of future research to explore how lipid metabolites impact the bioavailability of human milk extracellular vesicles. [ABSTRACT FROM AUTHOR]

Products from peanut seeds are nutritious for human and/or animal consumption. Peanut seed nutritional quality is determined by the genotype (G) of cultivars or accessions, environmental conditions (E), and their interactions (G × E). To evaluate the effects of genotype, environment, and their interactions on seed nutritional quality, 52 peanut germplasm accessions, which vary in oil content and fatty acid composition, were planted at three locations (Citra, FL; Byron, GA; and Clovis, NM) for 2 years (2017 and 2018). The harvested seeds were analyzed for protein, oil, and fatty acid composition using an N analyzer, nuclear magnetic resonance, and gas chromatography, respectively. Significant effects of accession, FAD2 gene, where FAD is fatty acid desaturase, location, year, and their interactions on the investigated traits were evaluated. The average oil content from accessions grown in Florida (51.1%) or Georgia (50.7%) was significantly higher than those grown in New Mexico (45.8%), whereas the average protein content from accessions grown in Florida (23.2%) was significantly lower than those grown in New Mexico (25.4%) or Georgia (24.8%). This is expected as there is a negative correlation between oil and protein content. After genotyping and classification (A/A, A/W, and G/W) for the FAD2A/FAD2B genes, the nutritional quality variations were further evaluated at the levels of the specific haplotype of FAD2A/FAD2B and explicit environmental index. The average prediction accuracy of seed nutritional quality trait values from the prediction model demonstrated that predicting trait values in new environments is feasible. The results of this study provide insights into the seed nutritional analysis, germplasm evaluation, and peanut breeding, cultivation, and production to peanut breeders, curators, farmers, and product processors. Core Ideas: Genotype, environment, and their interactions affect peanut seed nutritional quality.The FAD2A/FAD2B gene (F) effect significantly alters seed fatty acid composition.Location (L) effect significantly changes seed oil and protein content.Photothermal time may be a good parameter for representing the growing location environmental conditions for data analysis.Recommendation was given to farmers and processors on how to cultivate the right peanut varieties and purchase the right seeds from specific regions. [ABSTRACT FROM AUTHOR]

BACKGROUND: Yeast is often used to build cell factories to produce various chemicals or nutrient substances, which means the yeast has to encounter stressful environments. Previous research reported that unsaturated fatty acids were closely related to yeast stress resistance. Engineering unsaturated fatty acids may be a viable strategy for enhancing the stress resistance of cells. RESULTS: In this study, two desaturase genes, OLE1 and FAD2 from Z. rouxii, were overexpressed in S. cerevisiae to determine how unsaturated fatty acids affect cellular stress tolerance of cells. After cloning and plasmid recombination, the recombinant S. cerevisiae cells were constructed. Analysis of membrane fatty acid contents revealed that the recombinant S. cerevisiae with overexpression of OLE1 and FAD2 genes contained higher levels of fatty acids C16:1 (2.77 times), C18:1 (1.51 times) and C18:2 (4.15 times) than the wild‐type S. cerevisiae pY15TEF1. In addition, recombinant S. cerevisiae cells were more resistant to multiple stresses, and exhibited improved membrane functionality, including membrane fluidity and integrity. CONCLUSION: These findings demonstrated that strengthening the expression of desaturases was beneficial to stress tolerance. Overall, this study may provide a suitable means to build a cell factory of industrial yeast cells with high tolerance during biological manufacturing. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Polyunsaturated fatty acids (PUFAs) are essential nutrients for all living organisms. PUFA synthesis is mediated by Δ12 desaturases in plants and microorganisms, whereas animals usually obtain PUFAs through their diet. The whitefly Bemisia tabaci is an extremely polyphagous agricultural pest that feeds on phloem sap of many plants that do not always provide them with sufficient PUFAs. Here, a plant‐derived Δ12 desaturase gene family BtFAD2 is characterized in B. tabaci and it shows that the BtFAD2‐9 gene enables the pest to synthesize PUFAs, thereby significantly enhancing its fecundity. The role of BtFAD2‐9 in reproduction is further confirmed by transferring the gene to Drosophila melanogaster, which also increases the fruit fly's reproduction. These findings reveal an extraordinary evolutionary scenario whereby a phytophagous insect acquired a family of plant genes that enables it to synthesize essential nutrients, thereby lessening its nutritional dependency and allowing it to feed and reproduce on many host plants. [ABSTRACT FROM AUTHOR]

This article, published in the journal Pigment Cell & Melanoma Research, explores the role of TFE3, a transcription factor expressed in melanomas, in sensitizing cells to ferroptotic cell death. The study reveals that TFE3 promotes ferroptosis in melanoma cells, which is a form of nonapoptotic cell death caused by lipid peroxidation. The research suggests that targeting TFE3 could be a potential therapeutic strategy for treating metastatic melanoma. The findings provide new insights into the regulation of ferroptosis and highlight TFE3 as a potential target for inducing cell death in invasive melanoma cells. [Extracted from the article]

Ambient temperature during olive fruit growth modulates oil content and fatty acid composition. However, the mechanisms behind their regulation are not completely understood. In this work, the transcriptional regulation of oil synthesis and fatty acid desaturation were evaluated by manipulating air temperature in the field. Three‐year‐old trees of cultivars 'Arbequina' and 'Coratina' were placed in open‐top chambers (OTC) where control or elevated air temperatures were applied early in the oil accumulation phase, and fruits were sampled after 10 or 36 days of exposure. Upon elevated temperature, the oil content in 'Coratina' mesocarp tissue decreased less than in 'Arbequina' compared to their respective controls. However, the oleic acid content of 'Coratina' was more sensitive to temperature. The cultivar‐dependent responses were mainly explained by differential gene expression. In 'Arbequina', the downregulation of genes involved in triacylglycerol biosynthesis (OeDGAT1‐2, OeDGAT2, OePDAT1‐1, and OePDAT1‐2), upon elevated temperature explains the decrease in oil content, whereas the downregulation of the fatty acid desaturases genes (OeSAD1, OeSAD3, OeFAD2‐1, OeFAD2‐2, and OeFAD2‐5) decreased the oleic/linoleic ratio. In contrast, in 'Coratina', OePDAT1‐2 downregulation explains the fluctuation in oil content, but the increased expression of three members of the OeFAD2 gene family was responsible for the oleic/linoleic ratio. This knowledge contributes to developing an integrated strategy for olive production under high temperatures, and the analysis of the expression of key genes could be used as a selection criterion in genetic improvement programs for the adaptation of olive cultivars to global warming. [ABSTRACT FROM AUTHOR]

The synthesis rates of n‐3 and n‐6 polyunsaturated fatty acids (PUFAs) in rodents and humans are not agreed upon and depend on substrate availability independently of the capacity for synthesis. Therefore, we aimed to assess the activities of the enzymes for n‐3 and n‐6 PUFA synthesis pathways in liver, brain, testicle, kidney, heart, and lung, in relation to their protein concentration levels. Eight‐week‐old Balb/c mice (n = 8) were fed a standard chow diet (6.2% fat, 18.6% protein, and 44.2% carbohydrates) until 14 weeks of age, anesthetized with isoflurane and tissue samples were collected (previously perfused) and stored at −80°C. The protein concentration of the enzymes (Δ‐6D, Δ‐5D, Elovl2, and Elovl5) were assessed by ELISA kits; their activities were assayed using specific PUFA precursors and measuring the respective PUFA products as fatty acid methyl esters by gas chromatographic analysis. The liver had the highest capacity for PUFA biosynthesis, with limited activity in the brain, testicles, and kidney, while we failed to detect activity in the heart and lung. The protein concentration and activity of the enzymes were significantly correlated. Furthermore, Δ‐6D, Δ‐5D, and Elovl2 have a higher affinity for n‐3 PUFA precursors compared to n‐6 PUFA. The capacity for PUFA synthesis in mice mainly resides in the liver, with enzymes having preference for n‐3 PUFAs. [ABSTRACT FROM AUTHOR]

SUMMARY: Lipocalins constitute a conserved protein family that binds to and transports a variety of lipids while fatty acid desaturases (FADs) are required for maintaining the cell membrane fluidity under cold stress. Nevertheless, it remains unclear whether plant lipocalins promote FADs for the cell membrane integrity under cold stress. Here, we identified the role of OsTIL1 lipocalin in FADs‐mediated glycerolipid remodeling under cold stress. Overexpression and CRISPR/Cas9 mediated gene edition experiments demonstrated that OsTIL1 positively regulated cold stress tolerance by protecting the cell membrane integrity from reactive oxygen species damage and enhancing the activities of peroxidase and ascorbate peroxidase, which was confirmed by combined cold stress with a membrane rigidifier dimethyl sulfoxide or a H2O2 scavenger dimethyl thiourea. OsTIL1 overexpression induced higher 18:3 content, and higher 18:3/18:2 and (18:2 + 18:3)/18:1 ratios than the wild type under cold stress whereas the gene edition mutant showed the opposite. Furthermore, the lipidomic analysis showed that OsTIL1 overexpression led to higher contents of 18:3‐mediated glycerolipids, including galactolipids (monoglactosyldiacylglycerol and digalactosyldiacylglycerol) and phospholipids (phosphatidyl glycerol, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine and phosphatidyl inositol) under cold stress. RNA‐seq and enzyme linked immunosorbent assay analyses indicated that OsTIL1 overexpression enhanced the transcription and enzyme abundance of four ω‐3 FADs (OsFAD3‐1/3‐2, 7, and 8) under cold stress. These results reveal an important role of OsTIL1 in maintaining the cell membrane integrity from oxidative damage under cold stress, providing a good candidate gene for improving cold tolerance in rice. [ABSTRACT FROM AUTHOR]

Summary: Fruit ripening and disease resistance are two essential biological processes for quality formation and maintenance. DNA methylation, in the form of 5‐methylcytosine (5mC), has been elucidated to modulate fruit ripening, but its role in regulating fruit disease resistance remains poorly understood. In this study, we show that mutation of SlDML2, the DNA demethylase gene essential for fruit ripening, affects multiple developmental processes of tomato besides fruit ripening, including seed germination, leaf length and width and flower branching. Intriguingly, loss of SlDML2 function decreased the resistance of tomato fruits against the necrotrophic fungal pathogen Botrytis cinerea. Comparative transcriptomic analysis revealed an obvious transcriptome reprogramming caused by SlDML2 mutation during B. cinerea invasion. Among the thousands of differentially expressed genes, SlβCA3 encoding a β‐carbonic anhydrase and SlFAD3 encoding a ω‐3 fatty acid desaturase were demonstrated to be transcriptionally activated by SlDML2‐mediated DNA demethylation and positively regulate tomato resistance to B. cinerea probably in the same genetic pathway with SlDML2. We further show that the pericarp tissue surrounding B. cinerea infection exhibited a delay in ripening with singnificant decrease in expression of ripening genes that are targeted by SlDML2 and increase in expression of SlβCA3 and SlFAD3. Taken together, our results uncover an essential layer of gene regulation mediated by DNA methylation upon B. cinerea infection and raise the possible that the DNA demethylase gene SlDML2, as a multifunctional gene, participates in modulating the trade‐off between fruit ripening and disease resistance. [ABSTRACT FROM AUTHOR]

The infectious agent piscine myocarditis virus (PMCV) causes cardiomyopathy syndrome (CMS) and is responsible for substantial mortality and economic losses in the Atlantic salmon (Salmo salar) farming industry. Previous research has demonstrated that breeding for resistance against PMCV is an effective approach to mitigate the disease's impact. In this study, a new quantitative trait locus (QTL) is described on chromosome 23, together with previously described QTLs on chromosomes 12 and 27. The findings are based on two genome‐wide association studies conducted on two different year‐classes of Atlantic salmon of the Rauma strain. In this study, we utilized data from an experimental challenge trial with the viral load as the phenotype and a field outbreak of CMS with survival data as the phenotype. The estimated SNP‐based heritability was 0.55 and 0.44 in the two studies, respectively. In the infection trial, the top associated SNP on chromosome 23 accounted for approximately 46% of the genetic and 25.53% of the phenotypic variations in the viral load. In the field outbreak, we identified a QTL on the same genomic region of chromosome 23. The most significantly associated marker on this chromosome explained 13.57% and 5.97% of the genetic and phenotypic variations. The QTL on chromosome 23 is in proximity to delta‐5 fatty acyl desaturase and fatty acid desaturase 2 genes, both of which play a role in the production of polyunsaturated fatty acids. This proximity is particularly interesting as it offers valuable insights into enhancing our understanding of resistance against PMCV. [ABSTRACT FROM AUTHOR]

Sebum is a lipid‐rich mixture secreted by the sebaceous gland (SG) onto the skin surface. By penetrating through the epidermis, sebum may be involved in the regulation of epidermal and dermal cells in both healthy and diseased skin conditions. Saturated and monounsaturated fatty acids (FAs), found as free FAs (FFAs) and in bound form in neutral lipids, are essential constituents of sebum and key players of the inflammatory processes occurring in the pilosebaceous unit in acne‐prone skin. Little is known on the interplay among uptake of saturated FFAs, their biotransformation, and induction of proinflammatory cytokines in sebocytes. In the human SG, palmitate (C16:0) is the precursor of sapienate (C16:1n‐10) formed by insertion of a double bond (DB) at the Δ6 position catalysed by the fatty acid desaturase 2 (FADS2) enzyme. Conversely, palmitoleate (C16:1n‐7) is formed by insertion of a DB at the Δ9 position catalysed by the stearoyl coenzyme A desaturase 1 (SCD1) enzyme. Other FFAs processed in the SG, also undergo these main desaturation pathways. We investigated lipogenesis and release of IL‐6 and IL‐8 pro‐inflammatory cytokines in SZ95 sebocytes in vitro after treatment with saturated FFAs, that is, C16:0, margarate (C17:0), and stearate (C18:0) with or without specific inhibitors of SCD1 and FADS2 desaturase enzymes, and a drug with mixed inhibitory effects on FADS1 and FADS2 activities. C16:0 underwent extended desaturation through both SCD1 and FADS2 catalysed pathways and displayed the strongest lipoinflammatory effects. Inhibition of desaturation pathways proved to enhance lipoinflammation induced by SFAs in SZ95 sebocytes. Palmitate (C16:0), margarate (C17:0), and stearate (C18:0) are saturated fatty acids that induce different arrays of neutral lipids (triglycerides) and dissimilar grades of inflammation in sebocytes. [ABSTRACT FROM AUTHOR]

Membrane fatty acid desaturase (FADS)‐like superfamily proteins (FADSs) are essential for the synthesis of unsaturated fatty acids (UFAs). Recently, studies on FADS in fishes have mostly focused on marine species, and a comprehensive analysis of the FADS superfamily, including the FADS, stearoyl‐CoA desaturase (SCD), and sphingolipid delta 4‐desaturase (DEGS) families, in freshwater economic fishes is urgently required. To this end, we conducted a thorough analysis of the number, gene/protein structure, chromosomal location, gene linkage map, phylogeny, and expression of the FADS superfamily. We identified 156 FADSs genes in the genome of 27 representative species. Notably, FADS1 and SCD5 were lost in most freshwater fish and other teleosts. All FADSs proteins contain 4 transmembrane helices and 2–3 amphipathic α‐helices. FADSs in the same family are often linked on the same chromosome; moreover, FADS and SCD or DEGS are frequently collocated on the same chromosome. In addition, FADS, SCD, and DEGS family proteins share similar evolutionary patterns. Interestingly, FADS6, as a member of the FADS family, exhibits a similar gene structure and chromosome location to that of SCD family members, which may be the transitional form of FADS and SCD. This study shed light on the type, structure, and phylogenetic relationship of FADSs in freshwater fishes, offering a new perspective into the functional mechanism analysis of FADSs. [ABSTRACT FROM AUTHOR]

Summary: Fatty acids metabolic products and intramuscular fat (IMF) content determine meat quality in chickens. In this study, the mechanisms of G0/G1 switch gene 2 (G0S2) underlying modulation of chicken IMF content as well as fatty acid synthesis was investigated. Several advanced techniques including Gas Chromatography–Mass Spectrometer (GC–MS), RNA‐sequencing and lentiviral transfection were utilised. RNA‐sequencing showed that 2242 differentially expressed genes were significantly different, and many of these were related to lipid catabolism, such as stearoyl‐CoA desaturase 1 (SCD), acyl‐CoA synthetase bubblegum family member 2 (ACSBG2), and fatty acid desaturase 2 (FADS2), etc. Knocking down of G0S2 also affected the biological activities of signal transduction, catalytic activity, lipid metabolism, cell cycle and death, cell differentiation and immune response. GC–MS revealed that decreased lipid accumulation and lower unsaturated fatty acid percentage were observed in G0S2 knockdown adipocytes. Our results showed that lower expression of G0S2 decreased lipid accumulation mainly via down‐regulated SCD, then regulated mRNA levels of patatin‐like phospholipase domain containing 2 (PNPLA2), which was shown as a major triglyceride lipase in the liver and adipose tissue. Importantly, we further verified the regulation network of G0S2 in the thigh tissues of 12 Huangshan Black chickens, which was consistent with previous IMF results. Thus, our study highlights that G0S2 modulated chicken meat quality traits by the G0S2–SCD–PNPLA2 axis in lipid metabolism in vitro and in vivo. These findings are expected to provide a strategy from a genetic perspective for improving the meat quality. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mold‐ripened cheeses have low levels of unsaturated fatty acids (UFAs). Geotrichum candidum is an adjunct culture for the development of Geotrichum‐ripened cheese but has a low ability to produce high levels of UFAs. Δ12 fatty acid desaturase (FADS12) is a pivotal enzyme that converts oleic acid (OA) to linoleic acid (LA) and plays a vital role in UFA biosynthesis. By investigating FADS12 catalytic activity from various species with OA substrates, we found that FADS12 from Mucor circinelloides (McFADS12) had the highest catalytic activity for OA. RESULTS: In the current study, a plasmid harboring McFADS12 was constructed and overexpressed in G. candidum. Our results showed that LA production increased to 31.1 ± 1.4% in engineered G. candidum – three times higher than that in wild‐type G. candidum. To enhance LA production, an exogenous substrate (OA) was supplemented, and the yield of LA was increased to 154 ± 6 mg L−1 in engineered G. candidum. Engineered G. candidum was used as an adjunct culture for Geotrichum‐ripened cheese production. The LA level reached 74.3 ± 5.4 g kg−1 cheese, whereas the level of saturated fatty acids (SFAs) decreased by 9.9 ± 0.5%. In addition, the soybean byproduct (okara) was introduced into the engineered G. candidum growth and the level of LA increased to 126 ± 4 g kg−1 cheese and the percentage of UFAs:SFAs increased from 0.8:1 to 1.3:1. CONCLUSION: This study offers a suitable technology for converting SFAs to UFAs in Geotrichum‐ripened cheeses and provides a novel trend for converting soybean waste into a value‐added product. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to explore the anti‐inflammatory and anti‐lipid effects of lactoferrin on SZ95 human sebaceous gland cells and mouse model of acne. Methods: SZ95 cells were co‐cultured with different concentrations of lactoferrin, and cell viability was determined using the 2,5‐diphenyl‐2H‐tetrazolium bromide method. Oil red O and Nile red staining were performed to determine the lipid content. The mRNA expression of genes related to lipid metabolism (sterol regulatory element‐binding protein‐1 [SREBP‐1], fatty acid synthase [FAS], stearoyl‐CoA desaturase‐1 [SCD‐1], fatty acid desaturase 2 [FADS2]) and inflammation (interleukin‐8 [IL‐8]) was determined by reverse transcription–polymerase chain reaction. An acne mouse model was established using injection of P. acnes on the backs of mice. The proliferation and apoptosis of sebaceous gland cells were examined by immunohistochemistry against proliferating cell nuclear antigen (PCNA) and TUNEL staining, respectively. Western blotting was used to detect FADS2 and CXCL15 protein expression. Results: Lactoferrin treatment at 10–500 μg/ml significantly decreased the lipid content, as revealed by the oil red O and Nile red staining. It also attenuated the increase of mRNA expression of SREBP‐1, FAS, SCD‐1, FADS2, and IL‐8 in insulin‐treated SZ95 cells. Moreover, lactoferrin treatment at the doses of 1–50 mg/mouse significantly reduced the inflammation and lipid production in the mouse model of acne. Also, the number of sebaceous gland cells was significantly reduced, and apoptosis was significantly increased by lactoferrin treatment in the mice. Mechanically, the levels of FADS2 and CXCL15 proteins in tissues were significantly decreased after lactoferrin treatment in the model mice. Conclusion: Our results demonstrate the potential of lactoferrin against sebogenesis, sebaceous gland inflammation in acne. [ABSTRACT FROM AUTHOR]

Background: Previous studies have demonstrated that Runt‐associated transcription factor 2 (RUNX2) serves as the main transcription factor for osteoblast differentiation and chondrocyte maturation. RUNX2 is related to a variety of tumors, particularly tumor invasion and metastasis, while the expression and molecular mechanisms of RUNX2 in clear cell renal cell carcinoma (ccRCC) keep to be determined. Stearyl CoA desaturase 1 (SCD1), an endoplasmic reticulum fatty acid desaturase, transfers saturated fatty acids to monounsaturated fatty acids, is expressed highly in numerous malignancies. Methods: The Cancer Genome Atlas (TCGA) datebase and Western blot was used to analyzed the mRNA and protein levels of the target gene in ccRCC tissues and adjacent tissues. The proliferation ability of ccRCC cells was tested by colony forming and EdU assay. The migration ability of cells was detected by transwell assay. Immunoprecipitation was utilized to detect protein–protein interaction. Cycloheximide chase assay was used to measure the half‐life of SCD1 protein. Results: In this study, the expressions of RUNX2 and SCD1 are increased in ccRCC tissues as well as ccRCC cell lines. Both RUNX2 and SCD1 could promote proliferation and migration in ccRCC cells. Furthermore, RUNX2 could physically interact with SCD1. In addition, the functional degradation and the inactivation of Wnt/β‐catenin signaling pathway triggered by the downregulation of RUNX2 could be partly offset by the overexpression of SCD1. Conclusion: The findings indicate that the RUNX2/SCD1 axis may act as a potential therapeutic target via the Wnt/β‐catenin signaling pathway of ccRCC. [ABSTRACT FROM AUTHOR]

Aims/Introduction: Fatty acid desaturase (FADS) genetic polymorphisms are strongly correlated with the risk of dyslipidemia and cardiovascular disease. In this study, we examined the impact of FADS1 and FADS2 genetic variants on plasma lipid status, and assessed interactions between FADS genetic polymorphisms and plasma n‐3/n‐6 fatty acids regarding lipid status within a population of 816 Taiwanese patients with type 2 diabetes. Materials and Methods: Selected tag single‐nucleotide polymorphisms (FADS1 rs174546 [T/C]; FADS2 rs174602 [A/G] and rs2072114 [A/G]) were genotyped (n = 816). Results: The distribution of genotypes were compared with reports publicly available in the Genome Aggregation Database for East Asian populations (https://gnomad.broadinstitute.org). In the subgroup of patients not taking lipid‐lowering medications (n = 192), we observed that the G allele of FADS2 rs174602 was statistically significantly correlated with lower low‐density lipoprotein cholesterol (LDL‐C) concentrations (P = 0.001), whereas the G allele of rs2072114 was marginally associated with LDL‐C concentrations (P = 0.091). Using a general linear model adjusted for confounding factors, statistically significant interactions (P = 0.016) between single‐nucleotide polymorphisms in rs2072114 and a low alpha‐linolenic acid (18:3n‐3)/linoleic acid (18:2n‐6) ratio; the G allele correlated with lower LDL‐C levels among individuals with a low alpha‐linolenic acid/linoleic acid ratio. Interaction between rs174602 single‐nucleotide polymorphisms and low alpha‐linolenic acid/linoleic acid values on LDL‐C was only marginally significant (P = 0.063). Conclusions: Our results show the role of n‐3/n‐6 dietary polyunsaturated fatty acids in modifying the effects of genetic susceptibility on lipoprotein concentrations in patients with type 2 diabetes. Our findings highlight the potential of interventions with dietary polyunsaturated fatty acids regarding developing individualized prevention strategies for type 2 diabetes presenting with co‐occurring dyslipidemia and cardiovascular diseases. [ABSTRACT FROM AUTHOR]

The genomes of the best‐studied pseudomonads, Pseudomonas aeruginosa and Pseudomonas putida, which share 85% of the predicted coding regions, contain a fabA fabB operon (demonstrated in P. aeruginosa, putative in P. putida). The enzymes encoded by the fabA and fabB genes catalyze the introduction of a double bond into a 10‐carbon precursor which is elongated to the 16:1Δ9 and 18:1Δ11 unsaturated fatty acyl chains required for functional membrane phospholipids. A detailed analysis of transcription of the P. putida fabA fabB gene cluster showed that fabA and fabB constitute an operon and disclosed an unexpected and essential fabB promoter located within the fabA coding sequence. Inactivation of the fabA fabB operon fails to halt the growth of P. aeruginosa PAO1 but blocks growth of P. putida F1 unless an exogenous unsaturated fatty acid is provided. We report that the asymmetry between these two species is due to the P. aeruginosa PAO1 desA gene which encodes a fatty acid desaturase that introduces double bonds into the 16‐carbon acyl chains of membrane phospholipids. Although P. putida F1 encodes a putative DesA homolog that is 84% identical to the P. aeruginosa PAO1, the protein fails to provide sufficient unsaturated fatty acid synthesis for growth when the FabA FabB pathway is inactivated. We report that the P. putida F1 DesA homolog can functionally replace the P. aeruginosa DesA. Hence, the defect in P. putida F1 desaturation is not due to a defective P. putida F1 DesA protein but probably to a weakly active component of the electron transfer process. [ABSTRACT FROM AUTHOR]

Obesity promotes the development of osteoarthritis (OA). It is also well‐established that obesity leads to excessive lipid deposition in nonadipose tissues, which often induces lipotoxicity. The objective of this study was to investigate changes in the levels of various lipids in mouse cartilage in the context of obesity and determine if chondrocyte de novo lipogenesis is altered. We used Oil Red O to determine the accumulation of lipid droplets in cartilage from mice fed high‐fat diet (HFD) or low‐fat diet (LFD). We further used mass spectrometry‐based lipidomic analyses to quantify levels of different lipid species. Expression of genes involving in fatty acid (FA) uptake, synthesis, elongation, and desaturation were examined using quantitative polymerase chain reaction. To further study the potential mechanisms, we cultured primary mouse chondrocytes under high‐glucose and high‐insulin conditions to mimic the local microenvironment associated with obesity and subsequently examined the abundance of cellular lipid droplets. The acetyl‐CoA carboxylase (ACC) inhibitor, ND‐630, was added to the culture medium to examine the effect of inhibiting de novo lipogenesis on lipid accumulation in chondrocytes. When compared to the mice receiving LFD, the HFD group displayed more chondrocytes with visible intracellular lipid droplets. Significantly higher amounts of total FAs were also detected in the HFD group. Five out of six significantly upregulated FAs were ω‐6 FAs, while the two significantly downregulated FAs were ω‐3 FAs. Consequently, the HFD group displayed a significantly higher ω‐6/ω‐3 FA ratio. Ether linked phosphatidylcholine was also found to be higher in the HFD group. Fatty acid desaturase (Fad1‐3), fatty acid‐binding protein 4 (Fabp4), and fatty acid synthase (Fasn) transcripts were not found to be different between the treatment groups and fatty acid elongase (Elovl1‐7) transcripts were undetectable in cartilage. Ceramide synthase 2 (Cers‐2), the only transcript found to be changed in these studies, was significantly upregulated in the HFD group. In vitro, chondrocytes upregulated de novo lipogenesis when cultured under high‐glucose, high‐insulin conditions, and this observation was associated with the activation of ACC, which was attenuated by the addition of ND‐630. This study provides the first evidence that lipid deposition is increased in cartilage with obesity and that this is associated with the upregulation of ACC‐mediated de novo lipogenesis. This was supported by our observation that ACC inhibition ameliorated lipid accumulation in chondrocytes, thereby suggesting that ACC could potentially be targeted to treat obesity‐associated OA. [ABSTRACT FROM AUTHOR]

This review highlights the key role of fatty acid desaturases in the synthesis of naturally occurring, more common and not unsaturated fatty acids. The three major classes of fatty acid desaturases, such as acyl‐lipid, acyl‐acyl carrier protein and acyl‐coenzyme A, are described in detail, with particular attention to the cellular localisation, the structure, the substrate and product specificity and the expression and regulation of desaturase genes. The review also gives an insight into the biocatalytic reaction of fatty acid desaturation by covering the general and more class‐specific mechanistic studies around the synthesis of unsaturated fatty acids Finally, we conclude the review by looking at the numerous novel applications for desaturases in order to meet the very high demand for polyunsaturated fatty acids, taking into account the opportunity for the development of new, more efficient, easily reproducible, sustainable bioengineering advances in the field. [ABSTRACT FROM AUTHOR]

Linoleic acid is the material for biosynthesis of sex attracting and blocking (postmating) pheromones in Nasonia vitripennis, it is synthesized from oleic acid by a male‐biased fatty acid desaturase (SCD5a). In this study, we developed a specific antibody and further characterized the expression patterns of SCD5a in males at different mating stages by western blot. SCD5a was mainly expressed in male heads rather than in abdomens. Along with the aging process (from Day 1 to Day 3), SCD5a increased significantly. Compared with virgin males, mated males showed higher levels of SCD5a. Likewise, abdomen dipping frequency, during which males release attracting pheromone, increased with age and mating. Moreover, real‐time quantitative PCR revealed that genes responsible for the first three steps of attracting pheromone biosynthesis were more highly expressed in head than in abdomen, but the final gene for transformation of attracting pheromone was more highly expressed in abdomen than in head. These results suggest that linoleic acid for biosynthesis of attracting pheromones may also originate from the head rather than only synthesized at the rectal vesicles. Research Highlights: SCD5a was expressed more in the head than in the abdomen.Linoleic acid for attracting pheromone synthesis may also originate from male's head.Aged or mated males released more attracting pheromone and possess a higher possibility of successful mating. [ABSTRACT FROM AUTHOR]

The relative contribution of carbon sources generated from leaves and fruits photosynthesis for triacylglycerol biosynthesis in the olive mesocarp and their interaction with water stress was investigated. With this aim, altered carbon source treatments were combined with different irrigation conditions. A higher decrease in mesocarp oil content was observed in fruits under girdled and defoliated shoot treatment compared to darkened fruit conditions, indicating that both leaf and fruit photosynthesis participate in carbon supply for oil biosynthesis being leaves the main source. The carbon supply and water status affected oil synthesis in the mesocarp, regulating the expression of DGAT and PDAT genes and implicating DGAT1‐1, DGAT2, PDAT1‐1, and PDAT1‐2 as the principal genes responsible for triacylglycerol biosynthesis. A major role was indicated for DGAT2 and PDAT1‐2 in well‐watered conditions. Moreover, polyunsaturated fatty acid content together with FAD2‐1, FAD2‐2 and FAD7‐1 expression levels were augmented in response to modified carbon supply in the olive mesocarp. Furthermore, water stress caused an increase in DGAT1‐1, DGAT1‐2, PDAT1‐1, and FAD2‐5 gene transcript levels. Overall, these data indicate that oil content and fatty acid composition in olive fruit mesocarp are regulated by carbon supply and water status, affecting the transcription of key genes in both metabolic pathways. Summary statement: Triacylglycerol biosynthesis and fatty acid composition depend on the carbon supply and the water status, which control the transcription of PDAT and DGAT genes involved in oil accumulation and FAD2 and FAD7 genes related with unsaturated fatty acid composition. [ABSTRACT FROM AUTHOR]

Long‐chain polyunsaturated fatty acids are biologically important lipids that are unevenly distributed between and throughout environments. This heterogeneity can affect the evolution of metabolic processes, as populations adapt to the resource landscape that they encounter. Here, we compare fatty acid phenotypes of stickleback over two time scales of evolutionary divergence: between two lineages with different metabolic capacities for fatty acid synthesis (i.e. different copy number of the fatty acid desaturase gene; FADS2) that independently colonized European freshwaters during the Pleistocene and Holocene; and between two ecotypes within each lineage that have diverged more recently (~150 years) in different habitats (i.e. lake and stream). We measured fatty acid profiles of wild‐caught and lab‐reared fish for each lineage and ecotype combination after rearing lab fish on a diet deficient in omega‐3 long‐chain polyunsaturated fatty acids. Since these lineages hybridize in nature, we also measured profiles of lab‐reared hybrids and backcrosses raised on the same deficient diet. Wild fish showed strong compositional differences in fatty acids between habitats, lineages and sexes. Common garden fish had generally lower polyunsaturated fatty acid levels than wild fish, and females had lower omega‐6:omega‐3 than males. Fish from the lineage with fewer FADS2 copies also had lower levels of docosahexaenoic acid. Overall, we document divergence in fatty acid phenotypes between stickleback lineages with different histories of freshwater colonization, and between ecotypes in the early stages of adaptive population divergence. [ABSTRACT FROM AUTHOR]

Gene variants that influence human biology today reflect thousands of years of evolution. Genetic effects on infant health are a major point of selective pressure, given that childhood survival is essential to evolutionary success. Knowledge of this evolutionary history can have implications for paediatric research. Conclusion: An episode of human adaptation to the extremely low ultraviolet radiation environment of the Arctic 20,000 years ago implicates the Ectodysplasin A Receptor (EDAR) and the Fatty Acid Desaturases (FADS) in human lactation and epithelial inflammation. [ABSTRACT FROM AUTHOR]

As a member of the fatty acid desaturase family, fatty acid desaturase 2 (FADS2) gene is a rate‐limiting enzyme in the synthesis of unsaturated fatty acids and within/near to the reported QTL regions for milk‐production traits. We previously found that FADS2 is differentially expressed during different lactations of Chinese Holstein cows, and participates in lipid metabolic processes by influencing the insulin, PI3K‐Akt, MAPK, AMPK, mTOR and PPAR signaling pathways. Therefore, we considered this gene as a candidate gene for milk‐production traits. In this study, we identified 12 SNPs in FADS2 by re‐sequencing, including two SNPs in the 5′ flanking region, one in the seventh exon, five in introns, two in the 3′ untranslated region and two in the 3′ flanking region. The 29:g.40378819C>T is a missense mutation that causes alanine (GCG) to be replaced with valine (GTG). Through single marker association analysis, we found that all of the 12 SNPs were significantly associated with 305 day milk yield, fat yield, fat percentage, protein yield or protein percentage (p < 0.0493). The results of the subsequent haplotype association analysis also confirmed the associations between the gene and milk‐production traits. In summary, this study suggests that there is a significant genetic association between FADS2 and milk‐production traits, and that the SNPs with significant genetic effects can provide important molecular information for the development of a genomic selection chip in dairy cattle. [ABSTRACT FROM AUTHOR]

BACKGROUND: α‐linolenic acid is an essential unsaturated fatty acid in organisms. However, there is a large gap between α‐linolenic acid accumulation and its synthesis mechanism in insects. Fatty acid synthases (FASs) and desaturases (Desats) are vital enzymes required for the synthesis of unsaturated fatty acids. RESULTS: The pupae of Glyphodes pyloalis (Lepidoptera: Pyralidae), which is a destructive pest of mulberry trees, contain the highest level of α‐linolenic acid compared to other life‐history stages. To further explore the synthesis mechanism of α‐linolenic acid in G. pyloalis pupae, we constructed a pupal transcriptome dataset and identified 106 genes related to fatty acid metabolism from it. Among these, two fatty acid synthases (GpylFAS) and five desaturases (GpylDesat) were identified. A qRT‐PCR validation revealed that GpylFAS1 and GpylDesat1, 2, 3, 5 were expressed highest at pupal stages. Furthermore, the content of α‐linolenic acid decreased significantly after silencing GpylFAS1 and GpylDesat5, respectively. Besides, knocking down GpylFAS1 or GpylDesat5 resulted in more malformed pupae and adults, as well as lower emergence rates. Meanwhile, silencing GpylFAS1 or GpylDesat5 affected the expressions of the other GpylFASs and GpylDesats. CONCLUSION: The present results illustrate the pivotal function of FASs and Desats in α‐linolenic acid biosynthesis and metamorphosis in insects. Our research also broadens the sources of unsaturated fatty acids, especially for α‐linolenic acid from insects, and provides novel insights for the management of mulberry insect pests from the perspective of utilization rather than control. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The risk of esophageal adenocarcinoma (EAC) is associated with gastro‐esophageal reflux disease (GERD) and obesity. Lipid metabolism‐targeted therapies decrease the risk of progressing from Barrett's esophagus (BE) to EAC, but the precise lipid metabolic changes and their roles in genotoxicity during EAC development are yet to be established. Methods: Esophageal biopsies from the normal epithelium (NE), BE, and EAC, were analyzed using concurrent lipidomics and proteomics (n = 30) followed by orthogonal validation on independent samples using RNAseq transcriptomics (n = 22) and immunohistochemistry (IHC, n = 80). The EAC cell line FLO‐1 was treated with FADS2 selective inhibitor SC26196, and/or bile acid cocktail, followed by immunofluorescence staining for γH2AX. Results: Metabolism‐focused Reactome analysis of the proteomics data revealed enrichment of fatty acid metabolism, ketone body metabolism, and biosynthesis of specialized pro‐resolving mediators in EAC pathogenesis. Lipidomics revealed progressive alterations (NE‐BE‐EAC) in glycerophospholipid synthesis with decreasing triglycerides and increasing phosphatidylcholine and phosphatidylethanolamine, and sphingolipid synthesis with decreasing dihydroceramide and increasing ceramides. Furthermore, a progressive increase in lipids with C20 fatty acids and polyunsaturated lipids with ≥4 double bonds were also observed. Integration with transcriptome data identified candidate enzymes for IHC validation: Δ4‐Desaturase, Sphingolipid 1 (DEGS1) which desaturates dihydroceramide to ceramide, and Δ5 and Δ6‐Desaturases (fatty acid desaturases, FADS1 and FADS2), responsible for polyunsaturation. All three enzymes showed significant increases from BE through dysplasia to EAC, but transcript levels of DEGS1 were decreased suggesting post‐translational regulation. Finally, the FADS2 selective inhibitor SC26196 significantly reduced polyunsaturated lipids with three and four double bonds and reduced bile acid‐induced DNA double‐strand breaks in FLO‐1 cells in vitro. Conclusions: Integrated multiomics revealed sphingolipid and phospholipid metabolism rewiring during EAC development. FADS2 inhibition and reduction of the high polyunsaturated lipids effectively protected EAC cells from bile acid‐induced DNA damage in vitro, potentially through reduced lipid peroxidation. [ABSTRACT FROM AUTHOR]

Among all TAG profiles produced, those TAG species with three VLCPUFAs were the most abundant, followed by those with one or two VLCPUFAs such as DTA/DDA/ALA, DTA/ALA/ETA, DTA/18:1/LA, DDA/ALA/16:0. Transgenic I B. carinata i expressing the four genes (EhELO1+CpDesX+EhLPAAT2+PiO3) further produced many new TAG species with three VLCPUFAs such as DTA/DTA/24:3 and DTA/DTA/DDA. Keywords: very long-chain polyunsaturated fatty acid; docosatrienoic acid; metabolic engineering; Brassica carinata EN very long-chain polyunsaturated fatty acid docosatrienoic acid metabolic engineering Brassica carinata 8 10 3 01/11/23 20230101 NES 230101 Very long-chain polyunsaturated fatty acids (VLCPUFAs) are essential components of cell membranes and precursors for bioactive compounds regulating important physiological processes in humans and animals. [Extracted from the article]

The FATTY ACID DESATURASE 7 (FAD7) enzyme is widely conserved across many groups of plants and influences resistance to multiple stresses, including aphid infestation. In the model plant Arabidopsis thaliana (L.) Heynh. (Brassicaceae), a loss‐of‐function mutation in the FAD7 gene decreases population growth of a generalist herbivore, the green peach aphid (GPA), Myzus persicae (Sulzer) (Hemiptera: Aphididae). This study used multiple bioassay designs to further characterize the effects of a fad7 mutant on the GPA, and also to determine whether fad7 impacts a specialist herbivore, the cabbage aphid (CA), Brevicoryne brassicae L. (Hemiptera: Aphididae). In choice assays, when presented with wild‐type A. thaliana (Col‐0) or fad7, neither GPA nor CA showed a preference between genotypes within 48 h. In no‐choice assays the fad7 mutation decreased the overall population growth of GPA, with significant differences in juvenile production occurring as early as 48 h after infestation. In contrast, CA showed comparable population growth on fad7 and Col‐0 at all time points, from 24 to 144 h (6 days). No‐choice assays also demonstrated that the fad7 mutation increased GPA development time and reduced fecundity but did not influence the mortality rates of adults or juveniles, or the weight of newly emerged adults reared on fad7. These results indicate that aphid resistance in the fad7 mutant is species‐specific, and that it impacts the population growth of GPA solely through antibiosis, decreasing adult fecundity and increasing juvenile development time. [ABSTRACT FROM AUTHOR]

Atherosclerosis is the main cause of cardiovascular diseases. The Fat‐1 gene can express the n‐3 fatty acid desaturase, which converts n‐6 polyunsaturated fatty acids (PUFA) to n‐3 PUFAs. The role of n‐3 PUFAs in atherosclerosis is widely debated. This study explored the effect of n‐3 PUFAs on atherosclerosis in rabbits. In this study, atherosclerosis was induced in Fat‐1 transgenic rabbits and their littermate (WT) rabbits by feeding a high‐cholesterol diet containing 0.3% cholesterol and 3% soybean oil for 16 weeks. Plasma lipid, fatty acid and pathological analyses of atherosclerotic lesions were conducted. Fatty acid composition in the liver and muscle showed that n‐3 PUFAs increased and n‐6 PUFAs decreased in the Fat‐1 group. Plasma high‐density lipoprotein cholesterol (HDL‐C) levels were significantly increased in the Fat‐1 group, and the atherosclerotic lesion area of the aortic arch in Fat‐1 transgenic rabbits was significantly reduced. Histological analysis showed that smooth muscle cells (SMCs) in atherosclerotic lesions decreased significantly. In conclusion, n‐3 PUFAs improve atherosclerosis in Fat‐1 transgenic rabbits, and this process may depend on the increase in plasma HDL‐C and the decrease in the amount of SMCs in atherosclerotic plaques. [ABSTRACT FROM AUTHOR]

Summary: Jasmonates are fatty acid‐derived hormones that regulate multiple aspects of plant development, growth and stress responses. Bioactive jasmonates, defined as the ligands of the conserved COI1 receptor, differ between vascular plants and bryophytes (jasmonoyl‐l‐isoleucine (JA‐Ile) and dinor‐12‐oxo‐10,15(Z)‐phytodienoic acid (dn‐OPDA), respectively). The biosynthetic pathways of JA‐Ile in the model vascular plant Arabidopsis thaliana have been elucidated. However, the details of dn‐OPDA biosynthesis in bryophytes are still unclear.Here, we identify an orthologue of Arabidopsis fatty‐acid‐desaturase 5 (AtFAD5) in the model liverwort Marchantia polymorpha and show that FAD5 function is ancient and conserved between species separated by more than 450 million years (Myr) of independent evolution. Similar to AtFAD5, MpFAD5 is required for the synthesis of 7Z‐hexadecenoic acid. Consequently, in Mpfad5 mutants, the hexadecanoid pathway is blocked, dn‐OPDA concentrations are almost completely depleted and normal chloroplast development is impaired.Our results demonstrate that the main source of wounding‐induced dn‐OPDA in Marchantia is the hexadecanoid pathway and the contribution of the octadecanoid pathway (i.e. from OPDA) is minimal.Remarkably, despite extremely low concentrations of dn‐OPDA, MpCOI1‐mediated responses to wounding and insect feeding can still be activated in Mpfad5, suggesting that dn‐OPDA may not be the only bioactive jasmonate and COI1 ligand in Marchantia. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chilling injury (CI) is a physiological disorder that results in a limitation for cold storage (CS) of many fruits and vegetables. The low temperature‐induced changes in the properties and composition of cell membranes are involved in the response to chilling temperature and in the mechanism of CI and tolerance. RESULTS: We compared the changes in the lipid composition by gas chromatography‐mass spectrometry before, immediately after CS, as well as during a 3‐day subsequent period, of tomato fruits with different chilling‐sensitivity: Micro‐Tom (tolerant) and Minitomato (susceptible). The changes in linolenic acid content, double bond index and digalactosyldiacylglycerol/monogalactosyldiacylglycerol ratio (DGDG/MGDG) showed membrane fluidity adjustment, depending on the temperature. By a database search, we identified 18 membrane‐bound fatty acid desaturase (FAD) genes and five DGDG synthases (DGD) genes that phylogenetically clustered into four and two subfamilies, respectively. The FAD and DGD genes were differentially expressed in response to CS, as determined by quantitative reverse transcriptase‐polymerase chain reaction analysis. CONCLUSION: The data strongly suggest that reversion of CS‐induced changes during the recovery period is important for the proper function of the membrane and tolerance to postharvest CI in tomato fruit. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Gene redundancy allows a very high mutant load of 35-40 mutations per kilobase, and the populations of ~1500 and ~1200 lines each harbour ~22-23 missense or truncation mutations per gene. Keywords: burden test; rare-variant association analysis; mutant population; wheat EN burden test rare-variant association analysis mutant population wheat 1850 1852 3 09/23/22 20221001 NES 221001 Forward genetic screens are an excellent tool to assign gene function, but it is often necessary to employ map-based cloning to identify the causal genes. Burden tests can be used to map causal genes for a simple metabolic trait in an exome-sequenced polyploid mutant population. [Extracted from the article]

Lipids are major and essential constituents of plant cells and provide energy for various metabolic processes. However, the function of the lipid signal in defence against Verticillium dahliae, a hemibiotrophic pathogen, remains unknown. Here, we characterized 19 conserved stearoyl‐ACP desaturase family proteins from upland cotton (Gossypium hirsutum). We further confirmed that GhSSI2 isoforms, including GhSSI2‐A, GhSSI2‐B, and GhSSI2‐C located on chromosomes A10, D10, and A12, respectively, played a dominant role to the cotton 18:1 (oleic acid) pool. Suppressing the expression of GhSSI2s reduced the 18:1 level, which autoactivated the hypersensitive response (HR) and enhanced cotton Verticillium wilt and Fusarium wilt resistance. We found that low 18:1 levels induced phenylalanine ammonia‐lyase‐mediated salicylic acid (SA) accumulation and activated a SA‐independent defence response in GhSSI2s‐silenced cotton, whereas suppressing expression of GhSSI2s affected PDF1.2‐dependent jasmonic acid (JA) perception but not the biosynthesis and signalling cascade of JA. Further investigation showed that structurally divergent resistance‐related genes and nitric oxide (NO) signal were activated in GhSSI2s‐silenced cotton. Taken together, these results indicate that SA‐independent defence response, multiple resistance‐related proteins, and elevated NO level play an important role in GhSSI2s‐regulated Verticillium wilt resistance. These findings broaden our knowledge regarding the lipid signal in disease resistance and provide novel insights into the molecular mechanism of cotton fungal disease resistance. [ABSTRACT FROM AUTHOR]

Summary: Safflower (Carthamus tinctorius L.), a member of the Asteraceae, is a popular crop due to its high linoleic acid (LA) and flavonoid (such as hydroxysafflor yellow A) contents. Here, we report the first high‐quality genome assembly (contig N50 of 21.23 Mb) for the 12 pseudochromosomes of safflower using single‐molecule real‐time sequencing, Hi‐C mapping technologies and a genetic linkage map. Phyloge nomic analysis showed that safflower diverged from artichoke (Cynara cardunculus) and sunflower (Helianthusannuus) approximately 30.7 and 60.5 million years ago, respectively. Comparative genomic analyses revealed that uniquely expanded gene families in safflower were enriched for those predicted to be involved in lipid metabolism and transport and abscisic acid signalling. Notably, the fatty acid desaturase 2 (FAD2) and chalcone synthase (CHS) families, which function in the LA and flavonoid biosynthesis pathways, respectively, were expanded via tandem duplications in safflower. CarFAD2‐12 was specifically expressed in seeds and was vital for high‐LA content in seeds, while tandemly duplicated CarFAD2 genes were up‐regulated in ovaries compared to CarFAD2‐12, which indicates regulatory divergence of FAD2 in seeds and ovaries. CarCHS1, CarCHS4 and tandem‐duplicated CarCHS5˜CarCHS6, which were up‐regulated compared to other CarCHS members at early stages, contribute to the accumulation of major flavonoids in flowers. In addition, our data reveal multiple alternative splicing events in gene families related to fatty acid and flavonoid biosynthesis. Together, these results provide a high‐quality reference genome and evolutionary insights into the molecular basis of fatty acid and flavonoid biosynthesis in safflower. [ABSTRACT FROM AUTHOR]

Deficiency of polyunsaturated fatty acids (PUFAs) is known to induce hepatic steatosis. However, it is not clearly understood which type of PUFA is responsible for the worsening of steatosis. This study observed a marked accumulation of hepatic triacylglycerol and cholesterol in fatty acid desaturase 2 knockout (FADS2−/−) mice lacking both C18 and ≥ C20 PUFAs that were fed a PUFA‐depleted diet. Hepatic triacylglycerol accumulation was associated with enhanced sterol regulatory element‐binding protein (SREBP)‐1‐dependent lipogenesis and decreased triacylglycerol secretion into the plasma via very‐low‐density lipoprotein (VLDL). Furthermore, upregulation of cholesterol synthesis contributed to increased hepatic cholesterol content in FADS2−/− mice. These results suggest that ≥ C20 PUFAs synthesized by FADS2 are important in regulating hepatic triacylglycerol and cholesterol accumulation during PUFA deficiency. [ABSTRACT FROM AUTHOR]

Background: Increases in the red blood cell (RBC) degree of fatty acid desaturation are reported in response to exercise, aging, or diseases associated with systemic oxidant stress. However, no studies have focused on the presence and activity of fatty acid desaturases (FADS) in the mature RBC.Study Design and Methods: Steady state metabolomics and isotope-labeled tracing experiments, immunofluorescence approaches, and pharmacological interventions were used to determine the degree of fatty acid unsaturation, FADS activity as a function of storage, oxidant stress, and G6PD deficiency in human and mouse RBCs.Results: In 250 blood units from the REDS III RBC Omics recalled donor population, we report a storage-dependent accumulation of free mono-, poly-(PUFAs), and highly unsaturated fatty acids (HUFAs), which occur at a faster rate than saturated fatty acid accumulation. Through a combination of immunofluorescence, pharmacological inhibition, tracing experiments with stable isotope-labeled fatty acids, and oxidant challenge with hydrogen peroxide, we demonstrate the presence and redox-sensitive activity of FADS2, FADS1, and FADS5 in the mature RBC. Increases in PUFAs and HUFAs in human and mouse RBCs correlate negatively with storage hemolysis and positively with posttransfusion recovery. Inhibition of these enzymes decreases accumulation of free PUFAs and HUFAs in stored RBCs, concomitant to increases in pyruvate/lactate ratios. Alterations of this ratio in G6PD deficient patients or units supplemented with pyruvate-rich rejuvenation solutions corresponded to decreased PUFA and HUFA accumulation.Conclusion: Fatty acid desaturases are present and active in mature RBCs. Their activity is sensitive to oxidant stress, storage duration, and alterations of the pyruvate/lactate ratio. [ABSTRACT FROM AUTHOR]

Algal lipids are important molecules to store energy in algae and transfer energy in the marine food chain, and are potential materials for high value nutraceuticals (e.g., omega‐3 fatty acids) or biofuel production. However, how lipid biosynthesis is regulated is not well understood in many species including Eutreptiella from the phylum of Euglenozoa. Here, we characterized the fatty acid (FA) profile of an Eutreptiella species isolated from Long Island Sound, USA, using gas chromatography–tandem mass spectrometry (GC/MS/MS) and investigated their biosynthesis pathways by transcriptome sequencing. We discovered 24 types of FAs including a relatively high proportion of long‐chain unsaturated FAs. The abundances of C16, C18, and saturated FAs decreased when phosphate in the culture medium was depleted. Among the 24 FAs, docosahexaenoic acid (C22:6∆4,7,10,13,16,19) was most abundant, suggesting that Eutreptiella sp. preferentially invests in the synthesis of long‐chain polyunsaturated fatty acids (LC‐PFAs). Further transcriptomic analysis revealed that Eutreptiella sp. likely synthesizes LC‐PFAs via ∆8 pathway and uses type I and II fatty acid synthases. Using RT–qPCR, we found that some of the lipid synthesis genes, such as β‐ketoacyl‐ACP reductase, fatty acid desaturase, acetyl‐CoA carboxylase, acyl carrier protein, ∆8 desaturase, and Acyl‐ACP thioesterase, were more actively expressed during light period, and two carbon fixation genes were up‐regulated in the high‐lipid illuminated cultures, suggesting a linkage between photosynthesis and lipid production. The lipid profile renders Eutreptiella sp. a nutritional prey and valuable source for nutraceuticals, and the biosynthesis pathway documented here will be useful for future research and applications. [ABSTRACT FROM AUTHOR]

BACKGROUND: PfFAD3 transgenic soybean expressing omega‐3 fatty acid desaturase 3 of Physaria produces increased level of α‐linolenic acid in seed. Composition data of non‐transgenic conventional varieties is important in the safety assessment of the genetically‐modified (GM) crops in the context of the natural variation. RESULTS: The natural variation was characterized in seed composition of 13 Korean soybean varieties grown in three locations in South Korea for 2 years. Univariate analysis of combined data showed significant differences by variety and cultivation environment for proximates, minerals, anti‐nutrients, and fatty acids. Percent variability analysis demonstrated that genotype, environment and the interaction of environment with genotype contributed to soybean seed compositions. Principal component analysis and orthogonal projections to latent structure discriminant analysis indicated that significant variance in compositions was attributable to location and cultivation year. The composition of three PfFAD3 soybean lines for proximates, minerals, anti‐nutrients, and fatty acids was compared to a non‐transgenic commercial comparator (Kwangankong, KA), and three non‐transgenic commercial varieties grown at two sites in South Korea. Only linoleic and linolenic acids significantly differed in PfFAD3‐1 lines compared to KA, which were expected changes by the introduction of the PfFAD3‐1 trait in KA. CONCLUSION: Genotype, environment, and the interaction of environment with genotype contributed to compositional variability in soybean. PfFAD3‐1 soybean is equivalent to the conventional varieties with respect to these components. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The macrophage‐activating lipopeptide‐2 (MALP‐2) activates cells carrying a functional Toll‐like receptor (TLR)‐2/6. Human sebocytes express functional TLR‐2, TLR‐4 and CD14. Upregulation of stearoyl‐CoA desaturase (SCD) and fatty acid desaturase‐2 (FADS2) expression induces pro‐inflammatory sebaceous activity. On the other hand, corticotropin‐releasing hormone (CRH) is likely to serve as an autocrine stress hormone in human sebocytes. In addition to its antiproliferative, lipogenetic and androgen‐activating functions, CRH exhibits a pro‐inflammatory action and its expression is upregulated in acne‐involved sebaceous glands. Objective: Determination of the pro‐inflammatory function of MALP‐2 and CRH and clarification of the option that MALP‐2 and/or CRH activity on human sebocytes might be mediated through SCD and/or FADS2. Methods: SZ95 sebocytes were treated with MALP‐2, CRH and the SCD inhibitor/ligand FPCA. SCD, FADS2, TLR‐2 mRNA and protein levels and IL‐6 and IL‐8 secretion were investigated. Intracellular CRH levels were assessed under treatment with CRH, MALP‐2, linoleic acid and arachidonic acid. Phorbol 12‐myristate 13‐acetate and dexamethasone served as positive and negative controls, respectively. Results: MALP‐2 upregulated SCD, FADS2, TLR‐2 mRNA and protein levels and IL‐6 and IL‐8 secretion from SZ95 sebocytes. Co‐incubation of SZ95 sebocytes with MALP‐2/FPCA did not affect the MALP‐2‐induced SCD mRNA upregulation but reduced FADS2 mRNA levels and inhibited IL‐8 secretion. CRH induced an early, low‐level SCD and FADS2 upregulation and TLR‐2 and IL‐8 secretion. High intracellular CRH concentrations could be detected early after CRH treatment and persisted up to 24 h. MALP‐2 stimulated intracellular CRH levels. Conclusions: MALP‐2 stimulates the inflammatory signalling in human sebocytes through SCD and FADS2 activation. Inhibition of FADS2 mRNA levels and IL‐8 secretion through MALP‐2/FCPA co‐incubation and diminution of fatty acid unsaturation might lead to a reduction of pro‐inflammatory sebaceous lipids. CRH upregulates inflammatory signalling via the SCD/FADS2 pathway, and MALP‐2 selectively enhances CRH levels in human sebocytes. [ABSTRACT FROM AUTHOR]

An 8‐week growth trial was conducted to evaluate effects of dietary oil sources on growth, enzymes activity and genes expression levels related to lipid metabolism of hybrid grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatu) juveniles. Seven iso‐lipid (97 g/kg of dry matter) and iso‐protein (503.5 g/kg of dry matter) experimental diets were formulated containing 50 g/kg fish oil (FO; acting as controls) or various vegetable oils (VOs): corn oil (CO), sunflower oil (SO), tea oil (TO), olive oil (OO), rice oil (RO) and mixed oil (MO; comprising equal amounts of these oils). Each diet was fed to triplicate groups of 40 fish for per repetition (15.09 ± 0.01 g) for 56 days. The results show that (a) alternative dietary oils had no significant effects on final weight compared with control group (p >.05); (b) compared with FO group, VOs significantly changed the contents of serum lipoproteins, cholesterol, triglycerides and the activity of liver lipid‐metabolizing enzymes (p <.05); (c) CO group had the least effect on the serum lipoproteins, triglycerides and cholesterol of grouper compared with control; the activity of liver lipid‐metabolizing enzymes in RO and control group was the closest; (d) the mRNA levels of Δ6 Fatty acid desaturase (Δ6Fad), hormone‐sensitive lipase (HSL) and lipoprotein lipase (LPL) were not significantly effected by lipid sources, but CO, TO, OO and MO significantly down‐regulated the expression of fatty acid synthetase (FAS) mRNA level in liver, while RO opposite (p <.05); (e) vegetable oil significantly up‐regulated peroxisome proliferator‐activated receptor α (PPARα) and peroxisome proliferator‐activated receptor β (PPARβ) mRNA levels, while TO and RO down‐regulated peroxisome proliferator‐activated receptor γ (PPARγ) mRNA levels (p <.05); and 6) MO significantly increased the mRNA levels of heart‐type fatty acid‐binding protein (H‐FABP) and adipocyte‐type fatty acid‐binding protein (A‐FABP) (p <.05), while other VOs had no effect on them (p >.05). In conclusion, dietary substitution of FO by VO in diet affected lipid metabolism of grouper, which may be regulated by PPARs. [ABSTRACT FROM AUTHOR]

The Channel catfish is one of the most important freshwater fish species in North America. Conventionally their selection for genetic improvement is focused in growth related traits but not on quality traits as flavor and fatty acid deposition. The aim of this study was the sequencing of Stearoyl‐CoA Desaturase (SCD) and Fatty Acid Desaturase 2 (FADS2) genes, two of main genes in the biosynthesis of long chain polyunsaturated fatty acids, for novel variation discovering as a preliminary of marker assisted broader assessment. In SCD gene, two novel synonym polymorphisms (Exon 1 and 3) and a non‐synonymous Serine coding polymorphism in exon 3, were found. In FADS2, two synonymous polymorphisms (Exon 1 and 3) and multiple polymorphisms in non‐coding regions were discovered. Further association analysis of these novel variations could reveal punctual effect on fatty acid deposition traits and their utility for marker assisted selection purposes. [ABSTRACT FROM AUTHOR]

Summary: Forest fires generate a large amount of carbon that remains resident on the site as dead and partially 'pyrolysed' (i.e. burnt) material that has long residency times and constitutes a significant pool in fire‐prone ecosystems. In addition, fire‐induced hydrophobic soil layers, caused by condensation of pyrolysed waxes and lipids, increase post‐fire erosion and can lead to long‐term productivity losses. A small set of pyrophilous fungi dominate post‐fire soils and are likely to be involved with the degradation of all these compounds, yet almost nothing is currently known about what these fungi do or the metabolic processes they employ. In this study, we sequenced and analysed genomes from fungi isolated after Rim fire near Yosemite National Park in 2013 and showed the enrichment/expansion of CAZymes and families known to be involved in fruiting body initiation when compared to other basidiomycete fungi. We found gene families potentially involved in the degradation of the hydrophobic layer and pyrolysed organic matter, such as hydrophobic surface binding proteins, laccases (AA1_1), xylanases (GH10, GH11), fatty acid desaturases and tannases. Thus, pyrophilous fungi are important actors to restate the soil's functional capabilities. [ABSTRACT FROM AUTHOR]

As an important forage legume in the world, alfalfa (Medicago sativa L.) has high adaptability to various unfavorable climatic conditions and high biomass, and have been playing critical roles in animal husbandry and industrial applications. As α‐linolenic acid cannot be synthesized by animals, and most must be obtained from plants, the increasing of α‐linolenic acid content in alfalfa will greatly contribute to improve quality of livestock. However, the molecular mechanisms for α‐linolenic acid synthesis and accumulation in alfalfa are still limited. In this study, the importance of ω‐3 fatty acid desaturase (FAD) was demonstrated by analyzing α‐linolenic acid metabolic pathways, combined with the dynamics of accumulation of unsaturated fatty acids in alfalfa. Moreover, the FAD3.1 identified in alfalfa was located in the endoplasmic reticulum, and its expression level was consistent with the accumulation patterns of α‐linolenic acid in leaves. Heterologous expression in yeast cells proves that MsFAD3.1 was involved in the synthesis of α‐linolenic acid, and the α‐linolenic acid content in MsFAD3.1‐overexpression transgenic alfalfa lines was significantly increased. These results indicate that new alfalfa germplasm with high α‐linolenic acid content can be successfully created through biotechnology, providing a theoretical basis for further improving the quality of alfalfa and the nutritional value of dairy products. [ABSTRACT FROM AUTHOR]

Diiron(IV)‐oxo species are proposed to effect the cleavage of strong C−H bonds by nonheme diiron enzymes such as soluble methane monooxygenase (sMMO) and fatty acid desaturases. However, synthetic mimics of such diiron(IV) oxidants are rare. Herein we report the reaction of (TPA*)FeII (1) (TPA*=tris(3,5‐dimethyl‐4‐methoxypyridyl‐2‐methyl)amine) in CH3CN with 4 equiv CAN and 200 equiv HClO4 at 20 °C to form a complex with an [FeIV2(μ‐O)2]4+ core. CAN and HClO4 play essential roles in this unprecedented transformation, in which the comproportionation of FeIII‐O‐CeIV and FeIV=O/Ce4+ species is proposed to be involved in the assembly of the [FeIV2(μ‐O)2]4+ core. [ABSTRACT FROM AUTHOR]

Sustainably produced platform chemicals are increasingly sought after. Fatty acids containing olefinic and hydroxy groups are particularly interesting as platform chemicals for regio‐ and stereo‐selective downstream reactions. Integral membrane fatty acid desaturases can selectively introduce double bonds or catalyze unusual reactions such as acetylenation, conjugation, hydroxylation, and epoxidation. Here, a systematic overview of recent achievements and key literature of integral membrane desaturases is provided in the context of biotechnological potential of the enzyme family. Practical Application: Integral membrane fatty acid desaturases may be the most promising tool to increase the scope of fatty acids as platform chemicals. Plant oil production is well researched and an established sustainable pathway toward high‐yield chemicals. In addition, effort is increasing toward creating microbial high‐yield oil producers. The current bottleneck is the limited fatty acid species that can be produced at high yields. It is envisioned that future enzyme engineering work will enable the targeted design of desaturases to produce modified fatty acids that follow industry needs. This review provides a systematic overview of the natural diversity and complexity of integral membrane fatty acid desaturases to help researchers expand existing fatty acid production beyond currently utilized fatty acid species. [ABSTRACT FROM AUTHOR]