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This review presents the main modern ideas about the biosynthesis of long-chain polyunsaturated fatty acids in teleost fishes and about the genes encoding key enzymes, desaturases and elongases, involved in this process. The authors summarized basic information about the set of elongases and desaturases genes and the features of their functioning in the Atlantic salmon Salmo salar and the rainbow trout Oncorhynchus mykiss, as the most studied and valuable commercial salmon species. The data can be used when conducting research to improve and modify the biotechnology of fish farming with the possibility of targeted regulation of lipogenesis (primarily to control the content of essential FAs) in their body. [ABSTRACT FROM AUTHOR]

Disease-modifying strategies for Parkinson disease (PD), the most common synucleinopathy, represent a critical unmet medical need. Accumulation of the neuronal protein alpha-synuclein (αS) and abnormal lipid metabolism have each been implicated in PD pathogenesis. Here, we elucidate how retinoid-X-receptor (RXR) nuclear receptor signaling impacts these two aspects of PD pathogenesis. We find that activated RXR differentially regulates fatty acid desaturases, significantly reducing the transcript levels of the largely brain-specific desaturase SCD5 in human cultured neural cells and PD patient-derived neurons. This was associated with reduced perilipin-2 protein levels in patient neurons, reversal of αS-induced increases in lipid droplet (LD) size, and a reduction of triglyceride levels in human cultured cells. With regard to αS proteostasis, our study reveals that RXR agonism stimulates lysosomal clearance of αS. Our data support the involvement of Polo-like kinase 2 activity and αS S129 phosphorylation in mediating this benefit. The lowering of cellular αS levels was associated with reduced cytotoxicity. Compared to RXR activation, the RXR antagonist HX531 had the opposite effects on LD size, SCD, αS turnover, and cytotoxicity, all supporting pathway specificity. Together, our findings show that RXR-activating ligands can modulate fatty acid metabolism and αS turnover to confer benefit in cellular models of PD, including patient neurons. We offer a new paradigm to investigate nuclear receptor ligands as a promising strategy for PD and related synucleinopathies. [ABSTRACT FROM AUTHOR]

Stearoyl-CoA desaturase 1 (SCD1) is an attractive target for cancer therapy. However, the clinical efficacy of SCD1 inhibitor monotherapy is limited. There is thus a need to elucidate the mechanisms of resistance to SCD1 inhibition and develop new therapeutic strategies for combination therapy. In this study, we investigated the molecular mechanisms by which cancer cells acquire resistance to endoplasmic reticulum (ER) stress-dependent cancer cell death induced by SCD1 inhibition. SCD1 inhibitor-sensitive and -resistant cancer cells were treated with SCD1 inhibitors in vitro, and SCD1 inhibitor-sensitive cancer cells accumulated palmitic acid and underwent ER stress response-induced cell death. Conversely, SCD1-resistant cancer cells did not undergo ER stress response-induced cell death because fatty acid desaturase 2 (FADS2) eliminated the accumulation of palmitic acid. Furthermore, genetic depletion using siRNA showed that FADS2 is a key determinant of sensitivity/resistance of cancer cells to SCD1 inhibitor. A549 cells, an SCD1 inhibitor-resistant cancer cell line, underwent ER stress-dependent cancer cell death upon dual inhibition of SCD1 and FADS2. Thus, combination therapy with SCD1 inhibition and FADS2 inhibition is potentially a new cancer therapeutic strategy targeting fatty acid metabolism. [ABSTRACT FROM AUTHOR]

BAX and BAK are proapoptotic members of the BCL2 family that directly mediate mitochondrial outer membrane permeabilition (MOMP), a central step in apoptosis execution. However, the molecular architecture of the mitochondrial apoptotic pore remains a key open question and especially little is known about the contribution of lipids to MOMP. By performing a comparative lipidomics analysis of the proximal membrane environment of BAK isolated in lipid nanodiscs, we find a significant enrichment of unsaturated species nearby BAK and BAX in apoptotic conditions. We then demonstrate that unsaturated lipids promote BAX pore activity in model membranes, isolated mitochondria and cellular systems, which is further supported by molecular dynamics simulations. Accordingly, the fatty acid desaturase FADS2 not only enhances apoptosis sensitivity, but also the activation of the cGAS/STING pathway downstream mtDNA release. The correlation of FADS2 levels with the sensitization to apoptosis of different lung and kidney cancer cell lines by co-treatment with unsaturated fatty acids supports the relevance of our findings. Altogether, our work provides an insight on how local lipid environment affects BAX and BAK function during apoptosis. BAX and BAK are proapoptotic proteins that directly mediate mitochondrial outer membrane permeabilization (MOMP). Here, lipidomics and other data provide insight on how local lipid environment affects BAX and BAK function during apoptosis, suggesting that unsaturated lipids promote BAX pore activity. [ABSTRACT FROM AUTHOR]

Fatty acid desaturase (FAD) plays a crucial role in plant growth, development, and stress response. The FADs have been identified and reported in diverse plants, but so far, the whole genome exploration and analysis of FADs in castor (Ricinus communis L.) have not been reported yet. In this study, the identification of the RcFADs was carried out using a sequence alignment method. The physicochemical properties, gene structure, protein motifs, evolution, as well as gene expression under cold stress and different tissues were analyzed. A total of 16 RcFADs in the castor genome were identified, which contained the TMEM189 domain (PF10520)/FA_desaturase (PF00487)/FA_desaturase_2 (PF03405) conserved domain. Phylogenetic analysis showed that RcFADs can be categorized into ω-3, ω-6, ADS/SLD/DES, FAD4, and FAB2 groups, indicating that the function of RcFADs may vary. RNA-Sequencing and real-time PCR showed that the expression of RcFAD4 and RcFAD8.1 were increased with the duration of cold treatments, indicating their involvement in cold adaptability of castor. Global expression profiles of the RcFADs in different tissues displayed diverse expression patterns, which suggested that these genes might play important roles in regulating different developmental and physiological processes in castor. This study provides valuable information for understanding the potential function of RcFADs in regulating the growth and development and abiotic stress responses in castor. [ABSTRACT FROM AUTHOR]

With the increasing public attention to the health benefit of polyunsaturated fatty acids (PUFAs) and demand for linolenic acid (C18:3), it is of great significance to increase the C18:3 content in our meal. As an oil crop with high content of C18:3, Camelina sativa has three homologous copies of FAD2 and three homologous copies FAD3. In this study, we seed-specifically overexpressed two Camelina sativa fatty acid desaturase genes, CsFAD2 and CsFAD3, in rapeseed cultivar Zhongshuang 9. The results show that C18:3 content in CsFAD2 and CsFAD3 overexpressed seeds is increased from 8.62% in wild-type (WT) to 10.62–12.95% and 14.54–26.16%, respectively. We crossed CsFAD2 and CsFAD3 overexpression lines, and stable homozygous digenic crossed lines were obtained. The C18:3 content was increased from 8.62% in WT to 28.46–53.57% in crossed overexpression lines. In addition, we found that the overexpression of CsFAD2 and CsFAD3 had no effect on rapeseed growth, development, and other agronomic traits. In conclusion, we successfully generated rapeseed germplasms with high C18:3 content by simultaneously overexpressing CsFAD2 and CsFAD3, which provides a feasible way for breeding high C18:3 rapeseed cultivars. [ABSTRACT FROM AUTHOR]

The polymorphism of the rs174570, rs74771917, and rs7115739 loci of the FADS gene in Siberian populations was studied. It was shown that the frequency of the rs174570-T variant marking haplotype A with a reduced level of fatty acid desaturase expression in the modern indigenous populations increases in the direction from the south to the north of Siberia. Similarly, an increase in the frequency of the TTT haplotype at the rs174570, rs74771917, and rs7115739 loci was observed in the northern direction. However, in ancient times, the populations of Eastern Siberia (its northeastern part, Baikal region, and Primorye) were characterized by an equally high frequency of the rs174570-T variant (over 80%). It was shown that the main influx of the rs174570-C allele (and the CCG haplotype) to northeast Siberia occurred relatively recently, over the past 300 years, as a result of mating contacts between indigenous populations and immigrant groups of predominantly eastern European origin. The gene flow intensity (for the rs174570-C allele) is estimated to be 1.5–4.4% per generation. The appearance of the rs174570-C variant in the population of the Baikal region has been registered since the Eneolithic epoch, which is apparently associated mainly with the advance of the Afanasievo culture tribes to the east of Siberia. Meanwhile, analysis of paleogenomic data showed that the TTT haplotype, with high frequency distributed in modern Eskimos and Amerindians, was present in the Upper Paleolithic population of the Amur region, and therefore its carriers apparently took part in the formation of the ancient Beringian population. [ABSTRACT FROM AUTHOR]

Long-chain polyunsaturated fatty acids (PUFA) are critical for reproduction and thermal adaptation. Year-round variability in the expression of fads2 (fatty acid desaturase 2) in the liver of European perch (Perca fluviatilis) in a boreal lake was tested in relation to individual variation in size, sex, and maturity, together with stable isotopes values as well as fatty acids (FA) content in different tissues and prey items. ARA and DHA primary production was restricted to the summer months, however, perch required larger amounts of these PUFA during winter, as their ARA and DHA muscle content was higher compared to summer. The expression of fads2 in perch liver increased during winter and was higher in mature females. Mature females stored DHA in their gonads already in late summer and autumn, long before the upcoming spring spawning period in May. Lower δ13CDHA values in the gonads in September suggest that these females actively synthesized DHA as part of this reproductive investment. Lower δ13CARA values in the liver of all individuals during winter suggest that perch were synthesizing essential FA to help cope with over-wintering conditions. Perch seem able to modulate its biosynthesis of physiologically required PUFA in situations of stress (fasting or cold temperatures) or in situations of high energetic demand (gonadal development). Biosynthesis of physiologically required PUFA may be an important part of survival and reproduction in aquatic food webs with long cold periods. [ABSTRACT FROM AUTHOR]

The Pacific saury Cololabis saira is an important fishery resource in the Far East, where it is appreciated for its high lipid content, which includes long-chain polyunsaturated fatty acids (LC-PUFAs) such as docosahexaenoic acid (DHA). Although it has been hypothesized that these fatty acids are derived from their prey items, this study focused on evaluating the capacity of saury for endogenous production of LC-PUFAs. To describe its LC-PUFA biosynthetic pathway, we characterized fatty acid desaturase 2 (Fads2) and elongation of very long-chain fatty acid protein 5 (Elovl5) in Pacific saury. Two paralogous fads2 genes, namely fads2a and fads2b, were isolated from the saury and their recombinant protein showed ∆6∆8 and ∆4∆5 desaturase activities, respectively. Meanwhile, saury Elovl5 had elongase activity toward C18 and C20 PUFA. These three enzyme genes were expressed in the brain and liver, although fads2a was absent in the latter. Our results suggest that the saury has sufficient enzymatic functions, particularly in its brain, for DHA biosynthesis through the ∆4 pathway even from α-linolenic acid. This information provides novel insights into the origin of LC-PUFAs in Pacific saury and the future perspective for its potential as a source of such vital fatty acids for human consumption. [ABSTRACT FROM AUTHOR]

The association between fatty acids and prostate cancer remains poorly explored in African-descent populations. Here, we analyze 24 circulating fatty acids in 2934 men, including 1431 prostate cancer cases and 1503 population controls from Ghana and the United States, using CLIA-certified mass spectrometry-based assays. We investigate their associations with population groups (Ghanaian, African American, European American men), lifestyle factors, the fatty acid desaturase (FADS) genetic locus, and prostate cancer. Blood levels of circulating fatty acids vary significantly between the three population groups, particularly trans, omega-3 and omega-6 fatty acids. FADS1/2 germline genetic variants and lifestyle factors explain some of the variation in fatty acid levels, with the FADS1/2 locus showing population-specific associations, suggesting differences in their control by germline genetic factors. All trans fatty acids, namely elaidic, palmitelaidic, and linoelaidic acids, associated with an increase in the odds of developing prostate cancer, independent of ancestry, geographic location, or potential confounders. Analyses of the association between fatty acids and prostate cancer have often neglected African patients. Here, the authors analyse 24 circulating fatty acids in Ghanaian, African American, and European American men, and explore the associations with socio-demographic factors, diet, FADS1/2 locus, and prostate cancer. [ABSTRACT FROM AUTHOR]

Long-lived individuals (LLIs) are considered an ideal model to study healthy human aging. Blood fatty acid (FA) profile of a cohort of LLIs (90–111 years old, n = 49) from Sicily was compared to adults (18–64 years old, n = 69) and older adults (65–89 years old, n = 54) from the same area. Genetic variants in key enzymes related to FA biosynthesis and metabolism were also genotyped to investigate a potential genetic predisposition in determining the FA profile. Gas chromatography was employed to determine the FA profile, and genotyping was performed using high-resolution melt (HRM) analysis. Blood levels of total polyunsaturated FA (PUFA) and total trans-FA decreased with age, while the levels of saturated FA (SFA) remained unchanged. Interestingly, distinctively higher circulatory levels of monounsaturated FA (MUFA) in LLIs compared to adults and older adults were observed. In addition, among LLIs, rs174537 in the FA desaturase 1/2 (FADS1/2) gene was associated with linoleic acid (LA, 18:2n-6) and docosatetraenoic acid (DTA, 22:4n-6) levels, and the rs953413 in the elongase of very long FA 2 (ELOVL2) was associated with DTA levels. We further observed that rs174579 and rs174626 genotypes in FADS1/2 significantly affect delta-6 desaturase (D6D) activity. In conclusion, our results suggest that the LLIs have a different FA profile characterized by high MUFA content, which indicates reduced peroxidation while maintaining membrane fluidity. [ABSTRACT FROM AUTHOR]

Influences of photosynthesis of leaf and silique on seeds yield and quality of oilseed rape (Brassica napus L.) were explored in this study. A field comparing experiment with several rapeseed varieties was conducted and the results showed, that the leaf area index (LAI), silique surface area index (SAI), siliques number per plant, and biological yield were statistically classified as the first principal factors which greatly influenced seeds yield, the leaf net photosynthetic rate (Pn) and silique Pn were the second principal factors; the stomatal conductance (Gs) and chlorophyll a (Chl a) content were the first principal factors which influenced leaf Pn and silique Pn. A shading experiment was conducted and the results showed that, under treatments of the ZH1, ZH2, and ZH3 (shading rapeseed plants during flowering stage, during time from initial flowering until seeds ripening, and during time from flowering ending until seeds ripening, respectively), respectively the seeds yield per plant was reduced by 34.6%, 84.3%, and 86.1%, the seed protein content was significantly increased. The treatment ZH1 Not, but the ZH2 and ZH3 caused significant decrease in both seed oil content and oleic acid (C18:1) content in seed oil, and the contents of linoleic acid (C18:2), linolenic acid (C18:3) in oil were significantly increased, gene expression of the ACCase (Acetyl-CoA carboxylase), FAD2 (fatty acid desaturase), and FAD3 (ω-3 fatty acid dehydrogenase) in green seeds was restrained/changed. Thus the LAI, SAI, siliques number per plant, biological yield per plant, leaf Pn, silique Pn, and the Gs, Chl a content of leaf and silique formed an indexes system to be used in screening rapeseed variety with higher light efficiency and seeds yield; the silique photosynthesis inhibition and the photosynthates deficiency in rapeseed plant after flowering stage predominately influenced seeds yield and quality. [ABSTRACT FROM AUTHOR]

The oleaginous yeast Lipomyces starkeyi has considerable potential in industrial application, since it can accumulate a large amount of triacylglycerol (TAG), which is produced from sugars under nitrogen limitation condition. However, the regulation of lipogenesis in L. starkeyi has not been investigated in depth. In this study, we compared the genome sequences of wild-type and mutants with increased TAG productivity, and identified a regulatory protein, LsSpt23p, which contributes to the regulation of TAG synthesis in L. starkeyi. L. starkeyi mutants overexpressing LsSPT23 had increased TAG productivity compared with the wild-type strain. Quantitative real-time PCR analysis showed that LsSpt23p upregulated the expression of GPD1, which encodes glycerol 3-phosphate dehydrogenase; the Kennedy pathway genes SCT1, SLC1, PAH1, DGA1, and DGA2; the citrate-mediated acyl-CoA synthesis pathway-related genes ACL1, ACL2, ACC1, FAS1, and FAS2; and OLE1, which encodes ∆9 fatty acid desaturase. Chromatin immunoprecipitation-quantitative PCR assays indicated that LsSpt23p acts as a direct regulator of SLC1 and PAH1, all the citrate-mediated acyl-CoA synthesis pathway–related genes, and OLE1. These results indicate that LsSpt23p regulates TAG synthesis. Phosphatidic acid is a common substrate of phosphatidic acid phosphohydrolase, which is used for TAG synthesis, and phosphatidate cytidylyltransferase 1 for phospholipid synthesis in the Kennedy pathway. LsSpt23p directly regulated PAH1 but did not affect the expression of CDS1, suggesting that the preferred route of carbon is the Pah1p-mediated TAG synthesis pathway under nitrogen limitation condition. The present study contributes to understanding the regulation of TAG synthesis, and will be valuable in future improvement of TAG productivity in oleaginous yeasts. Key points: LsSpt23p was identified as a positive regulator of TAG biosynthesis LsSPT23 overexpression enhanced TAG biosynthesis gene expression and TAG production LsSPT23M1108Toverexpression mutant showed fivefold higher TAG production than control [ABSTRACT FROM AUTHOR]

Background: CRISPR/Cas9 is the most powerful and versatile genome-editing tool that permits multiplexed-targeted gene modifications for the genetic enhancement of oil palm. Multiplex genome-editing has recently been developed for modifying multiple loci in a gene or multiple genes in a genome with high precision. This study focuses on the development of high-oleic oil palm, the primary target trait for healthy low-saturated oil. To achieve this, the fatty acid desaturase 2 (FAD2) and palmitoyl-acyl carrier protein thioesterase (PAT) genes, both of which are associated with fatty acid metabolism biosynthesis pathways in oil palm, need to be knocked out. The knockout of FAD2 and PAT leads to an accumulation of oleic acid content in oil palms. Results: A total of four single-guide RNAs (sgRNAs) were designed in silico based on the genomic sequences of EgFAD2 and EgPAT. Using robust plant CRISPR/Cas9 vector technology, multiple sgRNA expression cassettes were efficiently constructed into a single-binary CRISPR/Cas9 vector to edit the EgFAD2 and EgPAT genes. Each of the constructed transformation vectors was then delivered into oil palm embryogenic calli using the biolistic, Agrobacterium-mediated, and PEG-mediated protoplast transformation methods. Sequence analysis of PCR products from 15 samples confirmed that mutations were introduced at four target sites of the oil palm EgFAD2 and EgPAT genes. Single- and double-knockout mutants of both genes were generated, with large and small deletions within the targeted regions. Mutations found at EgFAD2 and EgPAT target sites indicate that the Cas9/sgRNA genome-editing system effectively knocked out both genes in oil palm. Conclusion: This technology is the first in oil palm to use CRISPR/Cas9 genome-editing to target high-oleic-associated genes. These findings showed that multiplex genome-editing in oil palm could be achieved using multiple sgRNAs. Targeted mutations detected establish that the CRISPR/Cas9 technology offers a great potential for oil palm. [ABSTRACT FROM AUTHOR]

Plants use different strategies in response to environmental stress. Unsaturated fatty acids (UFAs) protect the plant against environmental stresses, especially temperature stresses, by regulating the fluidity of the cell membrane and also by scavenging reactive oxygen species (ROS) compounds. In this study, the expression changes of (Fatty Acid Desaturases) FAD2, 3 and 4 genes as well as fatty acid profile in two species Pistacia khinjuk and Pistacia atlantica were studied in response to different climatic conditions. The results show that the highest content of polyunsaturated fatty acids (PUFAs) is related to P. khinjuk species in Anjirk (AJ) region. Also, the highest content of monounsaturated fatty acids (MUFAs) can be seen in the same region in P. atlantica species. Comparing the two species, it can be observed that P. atlantica relatively contains more unsaturated fatty acids. The lowest expression of desaturase genes in the studied samples was in the Jebalbarez (JE) region. These results prove that both studied species changed the expression of desaturase genes in response to stress and finally the nutritional quality of the plant has been affected. [ABSTRACT FROM AUTHOR]

CRISPR–Cas9 gene-editing technology enables efficient genome editing in various plants, but entails difficulties and inefficiencies in transforming allotetraploid soybeans. Therefore, for producing transgenic soybeans using high-efficiency CRISPR–Cas9, a method for verifying the mutation efficiency of the target gene guide RNA is essential. Here, we present an experimental method using soybean protoplasts to confirm the effectiveness of single guide RNAs (sgRNAs) and sgRNA clones used for target gene mutagenesis to produce CRISPR–Cas9-mediated transgenic soybeans. In addition, we propose a method to improve the time-consuming process of producing CRISPR–Cas9-mediated transgenic soybeans. First, the fatty acid desaturase 2 (FAD2) gene was selected as a target gene for CRISPR–Cas9 application, and each of the three sgRNAs of the FAD2 isoforms (A, B) was produced based on the corresponding gene sequence. The sgRNAs of the three FAD2 genes were transfected into soybean protoplasts, and next-generation sequencing was performed using the isolated genomic DNA. The two FAD2-1A-1 and FAD2-1B-1 sgRNAs exhibited the highest insertion and deletion (indel) efficiency. Next, the selected FAD2-1A-1 and FAD2-1B-1 sgRNAs were cloned into three different binary vectors, and genomic DNA was isolated after transfection into the protoplast. Indel efficiency was high when pECO202 for FAD2-1A-1 and pECO201 for FAD2-1B-1 were used. Transgenic soybean was produced using the FAD2-1A-1::pECO202 and FAD2-1B-1::pECO201 sgRNA clones. The presented soybean protoplast transformation method can verify the mutation effect of specific sgRNAs and sgRNA clones of the soybean target gene used for CRISPR–Cas9 in a short period of time and reduce the time consumption of transgenic soybean production. [ABSTRACT FROM AUTHOR]

Background: Biological and abiotic stresses such as salt, extreme temperatures, and pests and diseases place major constraints on plant growth and crop yields. Fatty acids (FAs) and FA- derivatives are unique biologically active substance that show a wide range of functions in biological systems. They are not only participated in the regulation of energy storage substances and cell membrane plasm composition, but also extensively participate in the regulation of plant basic immunity, effector induced resistance and systemic resistance and other defense pathways, thereby improving plant resistance to adversity stress. Fatty acid desaturases (FADs) is involved in the desaturation of fatty acids, where desaturated fatty acids can be used as substrates for FA-derivatives. Objective: In this paper, the role of omega-FADs (ω-3 FADs and ω-6 FADs) in the prokaryotic and eukaryotic pathways of fatty acid biosynthesis in plant defense against stress (biological and abiotic stress) and the latest research progress were summarized. Moreover' the existing problems in related research and future research directions were also discussed. Results: Fatty acid desaturases are involved in various responses of plants during biotic and abiotic stress. For example, it is involved in regulating the stability and fluidity of cell membranes, reactive oxygen species signaling pathways, etc. In this review, we have collected several experimental studies to represent the differential effects of fatty acid desaturases on biotic and abiotic species. Conclusion: Fatty acid desaturases play an important role in regulating biotic and abiotic stresses. [ABSTRACT FROM AUTHOR]

Fatty acid desaturase catalyzes the desaturation reactions by inserting double bonds into the fatty acyl chain, producing unsaturated fatty acids, which play a vital part in the synthesis of polyunsaturated fatty acids. Though soluble fatty acid desaturases have been described extensively in advanced organisms, there are very limited studies of membrane fatty acid desaturases due to their difficulties in producing a sufficient amount of recombinant desaturases. However, the advancement of technology has shown substantial progress towards the development of elucidating crystal structures of membrane fatty acid desaturase, thus, allowing modification of structure to be manipulated. Understanding the structure, mechanism, and biosynthesis of fatty acid desaturase lay a foundation for the potential production of various strategies associated with alteration and modifications of polyunsaturated fatty acids. This manuscript presents the current state of knowledge and understanding about the structure, mechanisms, and biosynthesis of fatty acid desaturase. In addition, the role of unsaturated fatty acid desaturases in health and diseases is also encompassed. This will be useful in understanding the molecular basis and structural protein of fatty acid desaturase that are significant for the advancement of therapeutic strategies associated with the improvement of health status. Key points: • Current state of knowledge and understanding about the biosynthesis, mechanisms, and structure of fatty acid desaturase. • The role of unsaturated fatty acid desaturase. • The molecular basis and structural protein elucidated the crystal structure of fatty acid desaturase. [ABSTRACT FROM AUTHOR]

Key message: This study focused on enhancing resilience of soybean crops to drought and salinity stresses by overexpression of GmFAD3A gene, which plays an important role in modulating membrane fluidity and ultimately influence plants response to various abiotic stresses. Fatty acid desaturases (FADs) are a class of enzymes that mediate desaturation of fatty acids by introducing double bonds. They play an important role in modulating membrane fluidity in response to various abiotic stresses. However, a comprehensive analysis of GmFAD3 in drought and salinity stress tolerance in soybean is lacking. We used bean pod mottle virus (BPMV)-based vector for achieving rapid and efficient overexpression as well as silencing of Omega-3 Fatty Acid Desaturase gene from Glycine max (GmFAD3) to assess the functional role of GmFAD3 in abiotic stress responses in soybean. Higher levels of recombinant BPMV-GmFAD3A transcripts were detected in overexpressing soybean plants. Overexpression of GmFAD3A in soybean resulted in increased levels of jasmonic acid and higher expression of GmWRKY54 as compared to mock-inoculated, vector-infected and FAD3-silenced soybean plants under drought and salinity stress conditions. The GmFAD3A-overexpressing plants showed higher levels of chlorophyll content, efficient photosystem-II, relative water content, transpiration rate, stomatal conductance, proline content and also cooler canopy under drought and salinity stress conditions as compared to mock-inoculated, vector-infected and FAD3-silenced soybean plants. Results from the current study revealed that GmFAD3A-overexpressing soybean plants exhibited tolerance to drought and salinity stresses. However, soybean plants silenced for GmFAD3 were vulnerable to drought and salinity stresses. [ABSTRACT FROM AUTHOR]

The influences of three wheat gluten peptides (WGP-LL, WGP-LML, and WGP-LLL) on the osmotic stress tolerance and membrane lipid component in brewer's yeast were investigated. The results demonstrated that the growth and survival of yeast under osmotic stress were enhanced by WGP supplementation. The addition of WGP upregulated the expressions of OLE1 (encoded the delta-9 fatty acid desaturase) and ERG1 (encoded squalene epoxidase) genes under osmotic stress. At the same time, WGP addition enhanced palmitoleic acid (C16:1) content, unsaturated fatty acids/saturated fatty acids ratio, and the amount of ergosterol in yeast cells under osmotic stress. Furthermore, yeast cells in WGP-LL and WGP-LLL groups were more resistant to osmotic stress. WGP-LL and WGP-LLL addition caused 25.08% and 27.02% increase in membrane fluidity, 22.36% and 29.54% reduction in membrane permeability, 18.38% and 14.26% rise in membrane integrity in yeast cells, respectively. In addition, scanning electron microscopy analysis revealed that the addition of WGP was capable of maintaining yeast cell morphology and reducing cell membrane damage under osmotic stress. Thus, alteration of membrane lipid component by WGP was an effective approach for increasing the growth and survival of yeast cells under osmotic stress. Key points: •WGP addition enhanced cell growth and survival of yeast under osmotic stress. •WGP addition increased unsaturated fatty acids and ergosterol contents in yeast. •WGP supplementation improved membrane homeostasis in yeast at osmotic stress. [ABSTRACT FROM AUTHOR]

The diagnosis of RCVS was established by the combination of the following findings: (i) thunderclap headache, (ii) vasoconstriction on cerebrovascular imaging, and (iii) rule out of subarachnoid haemorrhage by CT and lumbar puncture. Dear Sirs, Reversible cerebral vasoconstriction syndrome (RCVS) is an important differential diagnosis in patients with acute onset thunderclap headache [[1]]. Since the symptoms (acute severe headache) as well as the clinical and radiographic constellation were neither suggestive of intracranial hypertension nor typical MRI abnormalities reported in patients with intracranial hypertension, we saw no indication for further diagnostics and particularly treatment. To our knowledge, this is the first case describing thunderclap headache and RCVS after intravenous iron substitution in a patient with chronic iron deficiency anemia. [Extracted from the article]

Enzyme catalyzed desaturation of intracellular fatty acids plays an important role in various physiological and pathological processes related to lipids. Limited to the multiple transmembrane domains, it is difficult to obtain their three-dimensional structure of fatty acid desaturases. So how they interact with their substrates is unclear. Here, we predicted the complex of Micromonas pusilla delta 6 desaturase (MpFADS6) with the substrate linoleinyl-CoA (ALA-CoA) by trRosetta software and docking poses by Dock 6 software. The potential enzyme–substrate binding sites were anchored by analysis of the complex. Then, site-directed mutagenesis and activity verification clarified that W290, W224, and F352 were critical residues of the substrate tunnel and directly bonded to ALA-CoA. H94 and H69 were indispensable for transporting electrons with heme. H452, N445, and H358 significantly influenced the recognition and attraction of MpFADS6 to the substrate. These findings provide new insights and methods to determine the structure, mechanisms and directed transformation of membrane-bound desaturases. Keypoints: The structure of the Δ6 fatty acid desaturase and substrate complex is modeled. The substrate tunnel and key residues of MpFADS6 catalytic activity are determined. The new insights to determine the mechanism of the membrane-bound desaturases. [ABSTRACT FROM AUTHOR]

Studies have shown that environmental carcinogens exerted an important function in the high incidence of esophageal cancer (EC). Nitrosamines have been identified as important environmental carcinogens for EC. This study aimed to investigate the metabolic disturbances and new key toxicological markers in the malignant transformation process of normal esophageal epithelial cells (Het-1A) induced by MNNG (N-methyl-N′-nitro-N-nitrosoguanidine). Untargeted metabolomic and lipidomic profiling analysis by using ultra-high-performance liquid chromatography coupled with mass spectrometry (UHPLC-MS) were applied to explore the metabolic network alterations of Het-1A cells. The metabolomic results showed that significant alterations were observed in metabolic signatures between different generations (P5, P15, P25, P35) and the control cell group (P0). A total of 48 differential endogenous metabolites were screened and identified, mainly containing fatty acids, amino acids, and nucleotides. The differential metabolites were predominantly linked to the pathway of biosynthesis of unsaturated fatty acids metabolism. The cell lipidomic profiling revealed that the most differential lipids contained fatty acids (FAs), phosphatidylcholines (PC), phosphatidylethanolamines (PE), and phosphatidylserines (PS). The enrichment of the lipidomic pathway also confirmed that the lipid metabolism of biosynthesis of unsaturated fatty acids was the significant variation during the cell malignant transformation. Furthermore, we detected the expression of the upstream regulatory enzymes related to the unsaturated fatty acids to explore the regulation mechanism. The expression of stearoyl-CoA desaturase (SCD), ELOVL fatty acid elongase 1 (ELOVL1) promoted, and fatty acid desaturase 1 (FADS1) inhibited the key fatty acids of unsaturated fatty acids metabolism compared to the control cell group. Overall, our results revealed that lipid fatty acid metabolism was involved in the malignant transformation of Het-1A cells induced by MNNG and deepened the awareness of the carcinogenic mechanism of environmental exposure pollutants. [ABSTRACT FROM AUTHOR]

Mango fruit is severely affected by chilling injury during storage at low temperatures. The molecular and biochemical processes occurring in fruits during the course of chilling injury development are not yet completely understood. The current study was carried out using the fruits of mango cv. Alphonso. Fruits were exposed to two treatments comprising temperature gradient storage (TGS) and low-temperature (5 °C) storage for 10, 20 and 30 days and compared with the room-temperature ripened fruits (control). The generation of free radicals and the content of malondialdehyde (MDA), leakage of electrolytes (EL), fatty acids, chlorophyll and total carotenoids were significantly affected in 5 °C stored fruits compared to control and TGS. Significant increase was observed in free radical generation and antioxidant enzyme activities at 5 °C storage. Consequently, the peroxidation of lipids and protein carbonyls were also significantly higher in low-temperature stored fruits. Unsaturated fatty acids were markedly reduced during the first 20 days at 5 °C leading to severe membrane leakage compared to TGS. Gene expression of Fatty Acid Desaturase (FAD), Peroxidase (POD) and Glutathione Reductase (GR) correlated with the observed increase in the level of unsaturated fatty acids, indicating the roles of these enzymes in cold stress-induced membrane changes. Out study has shown that the TGS treatment significantly reduces chilling injury by increasing the unsaturated fatty acids and also by reducing the peroxidation of lipids and protein carbonyls when compared to storage at 5 °C. [ABSTRACT FROM AUTHOR]

Since ancient times, meat and fat of seals and whales, rich in omega-3 polyunsaturated fatty acids, prevailed in the traditional "Arctic" diet of the indigenous people of the far Northeast of Siberia (Eskimos, Chukchi, Koryaks). This was reflected in the peculiarities of lipid metabolism of northern aborigines—for example, among them, variants of the genes for fatty acid desaturases (FADS1 and FADS2) encoding enzymes with reduced activity are predominantly widespread. In this study, we investigated the distribution of 22 bp insertion of the FADS2 gene (rs66698963), which affects the expression of the FADS1 gene, in populations of the northeastern (Koryaks, Evens) and southern (Buryats) parts of Siberia. The Koryaks had a minimum frequency of 22 bp insertions (5.6%)—almost an order of magnitude less frequently than Buryats (45.3%). In addition, a high frequency (10.9%) of nonsense mutation in the CYB5R2 gene (position 7 694 023 of chromosome 11) was detected in the Koryaks. This mutation leads to premature termination of the synthesis of NADH cytochrome b5 reductase, which is necessary for the functioning of desaturases encoded by FADS genes. The revealed genetic features of the indigenous population of the Far North are explained by long-term adaptation to a traditional diet very rich in lipids, which is a reason that prevents the need for additional synthesis of polyunsaturated fatty acids using fatty acid desaturases. [ABSTRACT FROM AUTHOR]

Obesity prevalence have tripled in the past decades. It is logical to consider new approaches to halt its prevalence. In this concept, considering the effect of interaction between fatty acid desaturase 2 (FADS2) gene variants and dietary advanced glycation end products (AGEs) on obesity-related characteristics seems to be challenging. The present cross-sectional study conducted among 347 obese individuals. A validated semi-quantitative 147-item food frequency questionnaire (FFQ) was used to estimate dietary intakes and American multiethnic database was used to calculate AGEs content of food items which were not available in Iranian Food Composition Table (FCT). FADS2 gene variants were determined according to Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Analysis of covariance (ANCOVA) was used to evaluate the modifier effect of FADS2 gene-dietary AGEs on biochemical values. Based on our findings, no significant differences was reported in term of biochemical variables between AGEs tertiles. In contrast, percent of macronutrients (carbohydrate, protein and fat) of total calorie intake, amount of daily intake of fiber and meat groups showed a significant differences among AGEs tertiles. Furthermore, statistical assays clarified the modifier effects of FADS2 gene-AGEs on weight (Pinteraction = 0.04), fat mass (Pinteraction = 0.03), waist circumference (Pinteraction = 0.008) and cholesterol (Pinteraction = 0.04) level. Accordingly, higher consumption of protein or fat based foods constitute high amount of AGEs and heterozygote genotype for FADS2 tended to show lower level of AGEs content. These findings address further investigation to develop new approaches for nutritional interventions. [ABSTRACT FROM AUTHOR]

Plastidial Δ12 fatty acid desaturase (FAD6) is a key enzyme for linoleic acid (LA) and α-linolenic acid (ALA) biosynthesis. Chia (Salvia hispanica L.) is a revived omega-3 plant source that is richest in ALA level. In this study, based on the RACE method, one full-length cDNA sequence encoding FAD6, named ShFAD6, was isolated from chia. There exist three alternative transcription start sites and five alternative poly(A) tailing sites in ShFAD6. The 5′UTR of ShFAD6 contains a purine-stretch of 44 bp. ShFAD6 has an ORF of 1335 bp encoding a 444 aa protein of 51.33 kDa. ShFAD6 contains a conserved Delta12-FADS-like domain together with three strong trans-membrane helices and three histidine motifs. There also exists a chloroplast transmit peptide in ShFAD6 N-terminal. Phylogenetic analyses validated its identity of dicot FAD6 protein and suggested some critical evolutionary features of plant FAD6 genes. Heterologous yeast expression confirmed the catalytic activity of ShFAD6. The qRT-PCR assay showed that ShFAD6 is mainly expressed in leaves, stems, flowers, buds and early-stage seeds, and also responded to various stresses and hormone treatments. Under Sclerotinia infection, qRT-PCR and fluorescence imaging illustrated the possible correlation of ShFAD6 expression and photosynthesis. This study provides insight for further function study of ShFAD6 in oil quality improvement in staple oilseed crops as well as stress response and adaptation in plants. [ABSTRACT FROM AUTHOR]

Purpose: Long-chain polyunsaturated fatty acids (LCPUFA) can be synthesised endogenously from linoleic acid (LA) and α-linolenic acid (ALA) in a pathway involving the fatty acid desaturase (FADS) genes. Endogenous synthesis is inefficient; therefore, dietary intake of preformed LCPUFA from their richest source of fish is preferred. This study investigated the effect of fish consumption on PUFA concentrations in women of childbearing age while stratifying by FADS genotype. The influence of fish consumption on lipid profile, and markers of inflammation and oxidative stress was also examined. Methods: Healthy women (n = 49) provided a buccal swab which was analysed for FADS2 genotype (rs3834458; T/deletion). Participants were stratified according to genotype and randomised to an intervention group to receive either no fish (n = 18), 1 portion (n = 14) or 2 portions (n = 17) (140 g per portion) of fish per week for a period of 8 weeks. Serum PUFA was analysed at baseline and post-intervention. Lipid profile, and markers of inflammation and oxidative stress were also analysed. Results: Participants consuming 2 portions of fish per week had significantly higher concentrations of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total n-3 PUFA, and a lower n-6:n-3 ratio compared to those in the no fish or 1 portion per week group (all p < 0.05). Fish consumption did not have a significant effect on biomarkers of oxidative stress, inflammation and lipid profile in the current study. Conclusion: Consumption of 2 portions of fish per week has beneficial effects on biological n-3 PUFA concentrations in women of childbearing age; however, no effects on oxidative stress, inflammation or lipid profile were observed. This trial was registered at www.clinicaltrials.gov (NCT03765580), registered December 2018. [ABSTRACT FROM AUTHOR]

Purpose: Azelaic acid (AzA) is a dicarboxylic acid naturally occurring in various grains having anti-inflammatory and anti-oxidation properties. Recently, AzA is shown to reduce high-fat diet-induced adiposity in animals. However, its physiological role in lipid metabolism and aging in various environmental stresses is unknown. Methods and Results: Using C. elegans as an invertebrate animal model, we demonstrate that AzA suppresses fat accumulation with no effect on lifespan at normal temperatures. Moreover, AzA promotes lifespan at low temperatures by elevation of unsaturated long-chain fatty acids and expression of genes in fatty acid desaturation. We further find that genes encoding fatty acid desaturases such as fat-1, fat-5, fat-6, and fat-7 are crucial for the lifespan-extending effect of AzA at low temperature. Conclusions: Taken together, our results suggest that AzA promotes adaption to low temperature in C. elegans via shifting fatty acid profile to unsaturated long-chain fatty acids. [ABSTRACT FROM AUTHOR]

Δ6 fatty acid desaturases (FADS6) have different substrate specificities that impact the ratio of omega-6/omega-3 polyunsaturated fatty acids, which are involved in regulating multiple signalling pathways associated with various diseases. For decades, FADS6 with different substrate specificities have been characterized and the functions of these crucial enzymes have been investigated, while it remains enigmatic that the substrate specificities of FADS6 from various species have a huge difference. This review summarizes the substrate specificities of FADS6 in different species and reveals the underlying relationship. Further evaluation of biochemical properties has revealed that the FADS6 prefer linoleic acid that is more hydrophilic and stable. Domain-swapping and site-directed mutagenesis have been employed to delineate the regions and sites that affect the substrate specificities of FADS6. These analyses improve our understanding of the functions of FADS6 and offer information for the discovery of novel biological resources. Key points: • Outline of the excavation and identification of Δ6 fatty acid desaturases. • Overview of methods used to determine the pivotal resides of desaturases. • Application of substrate properties to generate specific fatty acids. [ABSTRACT FROM AUTHOR]

The role of fatty acid ω3 acyl-lipid desaturases in low-temperature hardening (7 days at 3°C) of potato plants (Solanum tuberosum L., cv. Yubilei Zhukova) was studied. It was found that transcriptions of the three genes of ω3 acyl-lipid desaturases present in the potato genome significantly differed in their response to low temperature. The content of the FAD3 gene transcripts dramatically fell in the first day of cooling and was not restored until the end of the hardening period. The FAD7 gene was constitutively expressed through almost the entire adaptation period. The level of the FAD8 gene transcripts sharply increased in the first day of the hardening. The total fraction of trienoic fatty acids, which are synthesized by ω3 acyl-lipid desaturases, rose by 3% during the hardening, which is a relatively large value for potato. The hardened plants, in comparison with the unhardened ones, manifested a higher net photosynthesis/dark respiration ratio, higher (2.5-fold) concentration of soluble sugars, and stronger resistance to negative (–2 or –3°C) temperatures. It is suggested that the augmentation of the trienoic FA fraction, which are mainly localized in the thylakoid membranes of the potato chloroplasts, sustains the photosynthesis under low temperatures. Therefore, the maintenance of photosynthetic activity during the low-temperature acclimation supplies the plant with photoassimilates that are the principal sources of energy and metabolites necessary for the establishment of potato plant resistance to hypothermia. [ABSTRACT FROM AUTHOR]

Key message: Genomic editing with CRISPR/Cas9 system can simultaneously modify multiple copies of theBnaFAD2 gene to develop novel variations in fatty acids profiles in polyploidy rapeseed. Fatty acid composition affects edible and processing quality of vegetable oil and has been one of the primary targets for genetic modification in oilseed crops including rapeseed (Brassica napus). Fatty acid desaturase 2 gene, FAD2, is a key player that affects three major fatty acids, namely oleic, linoleic and linolenic acid, in oilseed plants. Previously, we showed that there are four copies of BnaFAD2 in allotetraploid rapeseed. In this study, we further established spatiotemporal expression pattern of each copy of BnaFAD2 using published RNA-seq data. Genomic editing technology based on CRISPR/Cas9 system was used to mutate all the copies of BnaFAD2 to create novel allelic variations in oleic acid and other fatty acid levels. A number of mutants at two targeting sites were identified, and the phenotypic variation in the mutants was systematically evaluated. The oleic acid content in the seed of the mutants increased significantly with the highest exceeding 80% compared with wild type of 66.43%, while linoleic and linolenic acid contents decreased accordingly. Mutations on BnaFAD2.A5 caused more dramatic changes of fatty acid profile than the mutations on BnaFAD2.C5 alleles that were identified with gene editing technique for the first time. Moreover, combining different mutated alleles of BnaFAD2 can even broaden the variation more dramatically. It was found that effects of different mutation types at BnaFAD2 alleles on oleic levels varied, indicating a possibility to manipulate fatty acid levels by precise mutation at specific region of a gene. [ABSTRACT FROM AUTHOR]

Polyunsaturated fatty acids (PUFAs) play crucial roles in adaptation to cold environments in a wide variety of animals and plants. However, the mechanisms by which PUFAs affect thermoregulatory behaviour remain elusive. Thus, we investigated the roles of PUFAs in thermoregulatory behaviour of Drosophila melanogaster. To this end, we generated transgenic flies expressing Caenorhabditis elegans Δ12 fatty acid desaturase (FAT-2), which converts mono-unsaturated fatty acids to PUFAs such as linoleic acid [C18:2 (n-6)] and linolenic acid [C18:3 (n-3)]. Neuron-specific expression of FAT-2 using the GAL4/UAS expression system led to increased contents of C18:2 (n-6)-containing phospholipids in central nerve system (CNS) and caused significant decreases in preferred temperature of third instar larvae. In genetic screening and calcium imaging analyses of thermoreceptor-expressing neurons, we demonstrated that ectopic expression of FAT-2 in TRPA1-expressing neurons led to decreases in preferred temperature by modulating neuronal activity. We conclude that functional expression of FAT-2 in a subset of neurons changes the thermoregulatory behaviour of D. melanogaster, likely by modulating quantities of PUFA-containing phospholipids in neuronal cell membranes. [ABSTRACT FROM AUTHOR]

Botryococcus braunii, a green alga that can produce a variety of secondary metabolites such as lipids, protein, and carotenoid, is considered a potential biodiesel feedstock for industrial commercialization. This study investigated the effects of exogenous plant growth regulators (PGRs) (6-benzylaminopurine (6-BA), abscisic acid (ABA), 2,4-epibrassinolide (EBR), ethephon (ETH), gibberellic acid (GA3), 1-naphthaleneacetic acid (NAA), salicylic acid (SA), and spermidine (SPD)) on the growth, protein, carotenoid and lipid biosynthesis, fatty acid composition, and expression of fatty acid biosynthetic genes in Botryococcus braunii B12 (B. braunii B12). NAA was the most effective inducer of microalgae biomass, which increased approximately 2-fold compared with that of the control. The maximum lipid accumulation and content were found under 15 mg/L GA3 treatment; the lipid accumulation reached 0.27 g/L, and the lipid content reached 60.25%. Moreover, the soluble protein content reached 28.49 mg/g DCW under 0.05 mg/L 6-BA treatment. Similarly, the highest carotenoid content (108.70 mg/g DCW) was observed under 50 mg/L NAA treatment. Furthermore, all PGRs altered the fatty acid composition of B. braunii B12, particularly the C16-C18 content (%). Finally, the effects of eight PGRs on seven lipid-related genes (acyl-acyl carrier protein (ACP), biotin carboxylase (BC), ω-3 fatty acid desaturase (FAD), acyl carrier protein thioesterase (FATA), 3-ketoacyl carrier protein synthase gene (KAS), malonyl-CoA:ACP transacylase (MCTK), and stearoyl-ACP-desaturase (SAD)) were studied by qRT-PCR, and an apparent correlation was found between gene expression and lipid synthesis in the microalgae. [ABSTRACT FROM AUTHOR]

Purpose: Aim of this study was to identify a possible relationship among dietary fatty acids (FA) intake, FA adipose tissue (AT) profile and cancer condition in lean vs obese subjects affected or not by colorectal cancer (CRC). Actually, inadequate dietary habits together with physical inactivity are primary determinants of obesity and cancer risk. Changes in lipid metabolism play a crucial role in different types of cancer and key enzymes involved in lipid-metabolic pathways, such as stearoyl-coA-desaturase 1 (SCD-1), are differentially expressed in normal and cancer tissues. Methods: Food frequency questionnaires (FFQ) were analyzed by Winfood software. FA were assessed by gas–liquid chromatography in visceral AT samples. Estimated desaturase activities were calculated as precursor FA/product FA ratio. Desaturase gene expressions were evaluated by RT-qPCR. Results: Lean and obese CRC subjects showed inadequate dietary habits. In particular, lean CRC subjects showed increase in the intake of saturated FA, specifically palmitic (p = 0.0042) and stearic acid (p = 0.0091), and a corresponding reduction of monounsaturated FA consumption, in particular oleic acid (p = 0.002) with respect to lean without CRC. Estimated SCD-1 activity in AT was increased in all the groups vs lean without CRC (pANOVA = 0.029). Conclusions: Unhealthy eating habits, characterizing obese and CRC subjects, may influence the visceral AT profile and contribute to the alteration of the metabolic pathways. The quality of the diet, other than the quantity, can have a main role in the establishment of inflammatory microenvironment and in metabolic changes favouring CRC. [ABSTRACT FROM AUTHOR]

The synthesis of α-linolenic acid (ALA) requires the activity of ω-3 fatty acid desaturases (ω-3 FADs). The quality of peanut oil would be much improved if the content of ALA could be increased. A scan of the peanut genome revealed that it harbored 36 FAD genes, mapping to 16 of the species' 20 chromosomes. A phylogenetic analysis concluded that these genes belonged to six sub-families, namely stearoyl-acyl-acyl carrier protein desaturases (SAD), FAD2, FAD3, FAD4/5, FAD6 and FAD7/8. Of these, FAD3 and FAD7/8 encoded ω-3 FADs, while genes belonging to the other four sub-families encoded ω-6 FADs. Based on RNA-Seq data, each of the 36 FAD genes was shown to be transcribed in non-stressed plants, but there was variation between them with respect to which organs they were transcribed in. Four ω-3 AhFAD3 genes were functionally characterized; when expressed in Arabidopsis thaliana protoplasts, each was localized mainly in the endoplasmic reticulum, while within peanut, the genes were more strongly transcribed in the developing seed than in either the root or the leaf. When constitutively expressed in Arabidopsis thaliana, both the total fatty acid content of the seed and the relative contribution of ALA were increased. The transgenic seedlings also exhibited an improved level of survival when challenged by salinity stress. [ABSTRACT FROM AUTHOR]

Oilseed crop oils contain a variety of unsaturated fatty acids that are synthesized and regulated by fatty acid desaturases (FADs). In this study, 14 FAD3 (ω3 desaturase) protein sequences from oilseeds are analyzed and presented through the application of several computational tools. The results indicated a close relationship between Brassica napus and Camelina sativa, as well as between Salvia hispanica and Perilla frutescens FAD3s, due to a high similarity in codon preferences in codon usage clusters and the phylogenetic tree. The cis-acting element results reveal that the seed-specific promoter region of BnFAD3 contains the critical conserved boxes such as HSE and ABRE, which are involved in responsiveness to heat stress and abscisic acid. The presence of the aforementioned conserved boxes may increase cold acclimation as well as tolerance to drought and high salinity. Omega(ω)3 desaturases contain a Skn-1 motif which is a cis-acting regulatory element required involved in endosperm development. In oilseed FAD3s, leucine is the most repeated amino acid in FAD3 proteins. The study conveyed that B. napus, Camelina sativa, Linum usitatissimum, Vernicia fordii, Gossypium hirsutum, S. hispanica, Cannabis sativa, and P. frutescens have retention signal KXKXX/XKXX at their c-terminus sites, which is one of the most important characteristics of FADs. Additionally, it was found that BnFAD3 is a transmembrane protein that can convert ω6 to ω3 fatty acids and may simultaneously act as a potassium ion channel in the ER. [ABSTRACT FROM AUTHOR]

Inbred animals were historically chosen for genome analysis to circumvent assembly issues caused by haplotype variation but this resulted in a composite of the two genomes. Here we report a haplotype-aware scaffolding and polishing pipeline which was used to create haplotype-resolved, chromosome-level genome assemblies of Angus (taurine) and Brahman (indicine) cattle subspecies from contigs generated by the trio binning method. These assemblies reveal structural and copy number variants that differentiate the subspecies and that variant detection is sensitive to the specific reference genome chosen. Six genes with immune related functions have additional copies in the indicine compared with taurine lineage and an indicus-specific extra copy of fatty acid desaturase is under positive selection. The haplotyped genomes also enable transcripts to be phased to detect allele-specific expression. This work exemplifies the value of haplotype-resolved genomes to better explore evolutionary and functional variations. Taurine and indicine cattle have different desirable traits making them better adapted to different climates across the world. Here, Low et al. describe a pipeline to produce haplotype-resolved, chromosome-level genomes of Angus and Brahman cattle breeds from a crossbred individual and report on comparisons of the two genomes. [ABSTRACT FROM AUTHOR]

In this study, the effects of limited and excess phosphate on biomass content, oil content, fatty acid profile and the expression of three fatty acid desaturases in Messastrum gracile SE-MC4 were determined. It was found that total biomass (0.67–0.83 g L−1), oil content (30.99–38.08%) and the duration for cells to reach stationary phase (25–27 days) were not considerably affected by phosphate limitation. However, excess phosphate slightly reduced total biomass and oil content to 0.50 g L−1 and 25.36% respectively. The dominant fatty acids in M. gracile, pamitic acid (C16:0) and oleic acid (C18:1) which constitute more than 81% of the total fatty acids remained relatively high and constant across all phosphate concentrations. Reduction of phosphate concentration to 25% and below significantly increased total MUFA, whereas increasing phosphate concentration to ≥ 50% and ≥ 100% significantly increased total SFA and PUFA content respectively. The expression of omega-3 fatty acid desaturase (ω-3 FADi1, ω-3 FADi2) and omega-6 fatty acid desaturase (ω-6 FAD) was increased under phosphate limitation, especially at ≤ 12.5% phosphate, whereas levels of streoyl-ACP desaturase (SAD) transcripts were relatively unchanged across all phosphate concentrations. The first isoform of ω-3 FAD (ω-3 FADi) displayed a binary upregulation under limited (≤ 12.5%) and excess (200%) phosphate. The expression of ω-6 FAD, ω-3 FAD and SAD were inconsistent with the accumulation of oleic acid (C18:1), linoleic acid (C18:2) and alpha-linolenic acid (C18:3), suggesting that these genes may be regulated indirectly by phosphate availability via post-transcriptional or post-translational mechanisms. [ABSTRACT FROM AUTHOR]

Brassica juncea is one of important oilseed crops, and FA compositions determine quality of vegetable oil. Although fatty acid desaturases (FADs) are mainly responsible for modifying seed FA compositions, genome-wide analysis of FAD gene family in B. juncea (BjuFAD) is not reported. Here, we identified 57 BjuFAD genes in B. juncea genome using homology searches. These FAD genes were unevenly distributed in 16 chromosomes and 3 scaffolds. Phylogenetic analysis showed that BjuFAD genes were divided into seven subfamilies. Exon–intron organizations, intron patterns and MEME motifs were highly conserved within each of BjuFAD subfamilies. Moreover, subcellular locations of deduced BjuFAD proteins and cis-acting elements in BjuFAD promoters were predicted and analyzed using online software. In addition, 16 SSR loci were totally found in BjuFAD genes/promoters. This work provides a basis for further function study of BjuFAD genes in quality improvement of B. juncea seed oil and in plant development as well as stress response. [ABSTRACT FROM AUTHOR]

In this study, the effects of limited and excess nitrate on biomass, lipid production, and fatty acid profile in Messastrum gracile SE-MC4 were determined. The expression of fatty acid desaturase genes, namely stearoyl-ACP desaturase (SAD), omega-6 fatty acid desaturase (ω-6 FAD), omega-3 fatty acid desaturase isoform 1 (ω-3 FADi1), and omega-3 fatty acid desaturase isoform 2 (ω-3 FADi2) was also assessed. It was found that nitrate limitation generally increased the total oil, α-linolenic acid (C18:3n3) and total polyunsaturated fatty acid (PUFA) contents in M. gracile. The reduction of nitrate concentration from 1.76 to 0.11 mM increased the total oil content significantly from 32.5 to 41.85% (dry weight). Palmitic (C16:0) and oleic (C18:1) acids as the predominant fatty acids in this microalgae constituted between 82 and 87% of the total oil content and were relatively consistent throughout all nitrate concentrations tested. The expression of SAD, ω-6 FAD, and ω-3 FADi2 genes increased under nitrate limitation, especially at 0.11 mM nitrate. The ω-3 FADi1 demonstrated a binary up-regulation pattern of expression under both nitrate-deficient (0.11 mM) and -excess (3.55 mM) conditions. Thus, findings from this study suggested that limited or excess nitrate could be used as part of a cultivation strategy to increase oil and PUFA content following media optimisation and more efficient culture methodology. Data obtained from the expression of desaturase genes would provide valuable insights into their roles under excess and limited nitrate conditions in M. gracile, potentially paving the way for future genetic modifications. [ABSTRACT FROM AUTHOR]

Fatty acid desaturases can catalyze saturated or unsaturated fatty acids to form a double bond at various locations in the hydrocarbon chain. In the present study, a total of 20 full-length desaturase genes were identified from rice genome. An exhaustive analysis was performed to describe their chromosomal locations, gene structures, phylogeny, cis-regulatory elements, sub-cellular localizations and expression patterns. The rice desaturase genes were distributed on ten of 12 chromosomes and phylogenetically classified into six subfamilies with the Arabidopsis counterparts, FAB2, FAD2, FAD3/7/8, FAD6, DES1 and SLD1. Among of them, 9 members were expanded via chromosomal tandem or segmental duplications. The gene structures and motif constituents were evolutionarily conserved in the same subfamilies. The majority of desaturase genes showed tissue-specific expression patterns and response to abiotic stresses and hormones based on microarray data and qRT-PCR analyses. This study will provide useful clues for functional validation of desaturase genes and contribute to produce nutritionally important fatty acids by genetic modification in rice. [ABSTRACT FROM AUTHOR]

Cold stress changes the molecular and physiological responses in wheat genotypes according to their genetic potential and duration of stress. Cold stress (6 °C) has been applied in time series of 9 days (1, 3, 6, and 9 days) and evaluated the morpho-physiological responses and genes involved in fatty acid metabolisms such as desaturases and lipid transfer protein by real-time PCR technique in two cultivars of wheat, including MV-17 (cold-tolerant) and Kuhdasht (cold-sensitive). Results indicated that cold stress had a significant effect on morpho-physiological traits in MV-17 when compared with Kuhdasht. Moreover, cold stress for a long period of time could induce more bioactive compounds like hydrogen peroxide and malondialdehyde in MV-17 cultivar than in Kuhdasht. The contents of proline and glycine betaine as osmoregulators increased during times after cold exposure in both cultivars, but ascorbic acids as an antioxidant significantly increased in MV-17 cultivar during prolonged cold treatments. Meanwhile, fatty acid desaturase and lipid transfer genes are involved in fatty acid biosynthesis and lipid changes and differently expressed in cold stress. The fatty acid desaturase 2 (FAD2) leads to lipid unsaturation and its transcript significantly increased in MV-17 cultivar, but it was non-significant in Kuhdasht cultivar. With prolonged cold exposure, fatty acid desaturase 3 (FAD3) and lipid transfer protein 1 (LTP1) gene expression increased and showed the similar trend in both cultivars, while stearoyl-acyl carrier protein desaturases (SAD1) reached to maximum level after 6 days of cold exposure. We found that MV-17 cultivar could be resistant to cold stress during prolonged exposure to 6 °C by the increase in the contents of osmolytes, antioxidant, and fatty acid desaturases especially FAD2 in comparison with Kuhdasht cultivar. [ABSTRACT FROM AUTHOR]

In tomato, desaturation of linoleic acid (18:2) to α-linolenic acid (18:3) is mediated in the plastidial membranes by the ω-3 fatty acid desaturases 7 (FAD7), and in the ER membrane by its paralog FAD3. According to the prevalent model, the hormone jasmonic acid isoleucine (JA-Ile), which plays a key role in the plant response to various stresses, including wounding and herbivores attack, is derived from 18:3 which is released from the plastidial membrane glycerolipids. The current work aimed at assessing in tomato the effects of ectopic FAD3 over-expression or SlFAD7 silencing on herbivore tolerance and on wound response. The tomato SlFAD7 gene encoding for the plastidial-residing FAD7 was silenced by RNA interference, and enhanced expression of the extra-plastidial ER-residing FAD3 was induced by ectopic expression of BnFAD3. Over-expression of BnFAD3 led to increase, whereas SlFAD7 silencing led to decrease in 18:3 content in the extra-plastidial and plastidial membrane, respectively. As anticipated, silencing SlFAD7 attenuated the accumulation of JA-Ile following wounding, and enhanced susceptibility to two important pest insects: the chewing herbivores Spodoptera littoralis and Heliothis peltigera. Unexpected was the finding that ectopic over-expression of the extra-plastidial ER-residing FAD3 accelerated both wound-induced JA-Ile accumulation and expression of wound-response marker genes. Furthermore, BnFAD3 over-expression significantly improved the tomato tolerance to these two chewing herbivores. The presented information supports the notion that 18:3 derived from extra-plastidial membranes may serve as a substrate for, or as a source for a cue triggering, JA-Ile biosynthesis in response to wounding and insect chewing. [ABSTRACT FROM AUTHOR]

In this study, the mechanism recruited by exogenous melatonin application at 100 μM for alleviating chilling injury in tomato fruits during cold storage was investigated. Alleviating chilling injury in tomato fruits in response to exogenous melatonin application at 100 μM may ascribe to providing sufficient intracellular ATP occur by higher H-ATPase, Ca-ATPase, cytochrome c oxidase (CCO), and succinate dehydrogenase (SDH) enzymes activity during cold storage. Also, higher unsaturated/saturated fatty acids (unSFA/SFA) ratio owing to higher linoleic and linolenic acids accumulation coincides with lower palmitic, stearic and oleic acids accumulation may be responsible for alleviating chilling injury in tomato fruits in response to exogenous melatonin application at 100 μM, which may occur by higher fatty acid desaturase 3 and 7 (FAD3 and FAD7) genes expression accompanying by lower phospholipase D (PLD) and lipoxygenase (LOX) genes expression and enzymes activity, in addition to providing sufficient intracellular ATP. Therefore, exogenous melatonin application may be a beneficial postharvest procedure for alleviating chilling injury in tomato fruits during cold storage. [ABSTRACT FROM AUTHOR]

In this study, the effect of freezing stress on expression of fatty acid desaturases (FAD2-2, FAD6 and FAD7) and beta-glucosidase (BGLC) genes was investigated in freezing- tolerant ("Fishomi") and sensitive ("Zard") olive (Olea europaea L.) cultivars. The olive cultivars were exposed to freezing stress (–10°C) at three different times points (1, 4 and 8 h), followed by a recovery stage. The degree of cell membrane damage was determined by measurement of leaves ion leakage of two olive cultivars both at freezing and recovery condition. The results indicated that ion leakage of cv. "Fishomi" was significantly lower than cv. "Zard" when exposed to the freezing stress and recovery condition. Furthermore, BGLC gene expression level in cv. "Zard" significantly suppressed 8 h after freezing stress. At the recovery period, its expression increased about three-fold at cv. "Fishomi". However, it was suppressed in cv. "Zard" at recovery period. FAD genes expression pattern in cv. "Fishomi" was different from that in cv. "Zard". FAD2 expression level in cv. "Fishomi" initially increased at the first 1 h and 4 h of freezing stress time and thereafter, decreased to control level over 8 h. Following recovery period, FAD2 gene expression level in cv. "Fishomi" increased up 5-fold. While, no expression detected in "Zard" at any time point or recovery period. The expression of FAD6 and FAD7 genes showed similar patterns at both cultivars. FAD6 and FAD7 genes expression significantly up-regulated 5- and 4.5-fold, respectively, following recovery period in "Fishomi". Overall, the results suggested that FADs and BGLC could be involved in the increasing of freezing tolerance in olive cultivars, particularly in plants recovery from freezing stress. [ABSTRACT FROM AUTHOR]

Fatty acid desaturases catalyze the formation of a C=C double bond from a C-C single bond in fatty acids, leading to diversification of the fatty acid pool. In this study, we identified the fatty acid desaturase genes in the monogonont marine rotifer Brachionus koreanus, measured the messenger RNA (mRNA) expression, and quantified fatty acid composition under feeding with the alga Tetraselmis suecica. Eight fatty acid desaturase genes were identified and classified by phylogenetic analysis. Fatty acid desaturases in the rotifer B. koreanus were categorized into two Δ4 desaturases, five Δ5/6 desaturases, and one Δ9 desaturase. mRNA expression of B. koreanus under the alga T. suecica-fed condition clearly indicated that transcriptional levels of desaturase genes were increased compared to the non-T. suecica-fed group. Also, the distribution of fatty acids of B. koreanus fed T. suecica was more balanced compared to that of T. suecica. These results provide a better understanding of the role of fatty acid desaturases in B. koreanus fed the alga T. suecica. [ABSTRACT FROM AUTHOR]

The ω-3 fatty acid desaturase (ω3Des) is a key enzyme in the biosynthesis of polyunsaturated fatty acids (PUFAs). However, the enzyme exhibits a significant preference towards different fatty acid substrates. To examine the molecular mechanism of its substrate specificity, a series of site-directed mutants were constructed based on the membrane topology model and functionally characterised by heterologous expression in Saccharomyces cerevisiae. Our results revealed that the W106F and V137T mutations markedly decreased the enzyme activity which indicated that these two residues were associated with substrate recognition. In contrast, the A44S, M156I and W291M mutations showed significant increments (30 to 40%) of the conversion rate for AA substrate desaturation, which suggests that these residues play a pivotal role in desaturation of longer chain-length substrates. Through homology modelling of 3-dimensional structures and molecular docking of FADS15, we propose that the critical residues that bind to the CoA groups may affect substrate localisation and govern substrate preference and chain-length specificity. Our work increases the understanding of the structure-function relationships of the microbial membrane-bound desaturases. The growing knowledge of the molecular mechanism will also aid in the efficient production of value-added fatty acids. [ABSTRACT FROM AUTHOR]

Cyanobacterium sp. IPPAS B-1200 is characterized by a high content of rare fatty acids (FAs), both myristic (14:0-30%) and myristoleic (14:1Δ9-10%) in the membrane lipids. Thus, short-chain FAs reach 40% of the sum of all FAs in cells, which is unusual for Cyanobacteria. Monounsaturated palmitoleic acids (16:1Δ9) also reach 40% of the sum of the FAs. We determined the complete nucleotide sequence of the genome of this cyanobacterium and found the only gene for the acyl-lipid Δ9-desaturase, desC1. We cloned this gene and characterized its specificity to the length of the substrate using heterologous expression in Escheriсhia coli. The results show that DesC1 nonspecifically generates olefin bond in FAs with a length of 14, 16, and 18 carbon atoms. This finding confirms that all monoesterifed FAs in Cyanobacterium sp. IPPAS B-1200 are generated by one acyl-lipid Δ9-desaturase. [ABSTRACT FROM AUTHOR]

Several plant genes have their first intron in the 5′ untranslated region (5′ UTR), and such 5′ UTR introns often show several biological functions, including the intron-mediated enhancement of protein expression through an increase of mRNA level (IME), intron-dependent spatial expression, and intron-mediated enhancement of translation. Here, we show another function of the 5′ UTR intron, i.e., the 5′ UTR intron-mediated enhancement of constitutive splicing. The NtFAD3 gene, which encodes a tobacco microsome ω-3 fatty acid desaturase, has a 552 nucleotide-long 5′ UTR intron (intron 1), and the other seven introns are located in the coding sequence. The splicing of the 5′ half region of the NtFAD3 was studied through an in vivo splicing assay using Arabidopsis leaf explants. The low splicing efficiency of intron 2 was much improved when the assay construct harbored intron 1. Deletion of intron 1 and the replacement of intron 1 to the NtFAD3 intron 8 decreased the splicing efficiency of intron 2. The splicing enhancers were redundant and dispersed in the 5′ splice site-proximal, 284-nucleotides region of intron 1. In addition, the interaction among the cis-elements, i.e., the splicing enhancers in the intron 1 and exon 2, were necessary for the efficient splicing of intron 2. The 5′ UTR intron-mediated constitutive splicing was partially inhibited when an SR-like protein, SR45, was deficient. These results indicated a novel function of the 5′ UTR intron, namely an enhancement of the constitutive splicing. [ABSTRACT FROM AUTHOR]