Engineering Yarrowia lipolytica for sustainable ricinoleic acid production: A pathway to free fatty acid synthesis.

Ricinoleic acid (C18:1-OH, RA) is a valuable hydroxy fatty acid with versatile applications. The current industrial source of RA relies on the hydrolysis of castor bean oil. However, the coexistence of the toxic compound ricin and the unstable supply of this plant have led to an exploration of promising alternatives: generating RA in heterologous plants or microorganisms. In this study, we engineered the oleaginous yeast Yarrowia lipolytica to produce RA in the form of free fatty acids (FFA). First, we overexpressed fungal Δ12 oleate hydroxylase gene (CpFAH12) from Claviceps purpurea while deleting genes related to fatty acid degradation (MEF1 and PEX10) and oleic acid desaturation (FAD2). Since Δ12 oleate hydroxylase converts oleic acid (C18:1) located at the sn-2 position of phosphatidylcholine (PC), we next focused on increasing the PC pool containing oleic acid. This objective was achieved thorough implementing metabolic engineering strategies designed to enhance the biosynthesis of PC and C18 fatty acids. To increase the PC pool, we redirected the flux towards phospholipid biosynthesis by deleting phosphatidic acid phosphatase genes (PAH1 and APP1) and diacylglycerol acyltransferase gene (DGA1), involved in the production of diacylglycerol and triacylglycerol, respectively. Furthermore, the PC biosynthesis via the CDP-DAG pathway was enhanced through the overexpression of CDS1, PSD1, CHO2, and OPI3 genes. Subsequently, to increase the oleic acid content within PC, we overexpressed the heterologous fatty acid elongase gene (MaC16E) involved in the conversion of C16 to C18 fatty acids. As RA production titer escalated, the produced RA was mainly found in the FFA form, leading to cell growth inhibition. The growth inhibition was mitigated by inducing RA secretion via Triton X-100 treatment, a process that simultaneously amplified RA production by redirecting flux towards RA synthesis. The final engineered strain JHYL-R146 produced 2.061 g/L of free RA in a medium treated with 5% Triton X-100, constituting 74% of the total FFAs produced. Generating free RA offers the added benefit of bypassing the hydrolysis stage required when employing castor bean oil as an RA source. This achievement represents the highest level of RA synthesis from glucose reported thus far, underscoring the potential of Y. lipolytica as a host for sustainable RA production.

Enhanced production of seed oil with improved fatty acid composition by overexpressing NAD+ -dependent glycerol-3-phosphate dehydrogenase in soybean.

There is growing interest in expanding the production of soybean oils (mainly triacylglycerol, or TAG) to meet rising feed demand and address global energy concerns. We report that a plastid-localized glycerol-3-phosphate dehydrogenase (GPDH), encoded by GmGPDHp1 gene, catalyzes the formation of glycerol-3-phosphate (G3P), an obligate substrate required for TAG biosynthesis. Overexpression of GmGPDHp1 increases soybean seed oil content with high levels of unsaturated fatty acids (FAs), especially oleic acid (C18:1), without detectably affecting growth or seed protein content or seed weight. Based on the lipidomic analyses, we found that the increase in G3P content led to an elevated diacylglycerol (DAG) pool, in which the Kennedy pathway-derived DAG was mostly increased, followed by PC-derived DAG, thereby promoting the synthesis of TAG containing relatively high proportion of C18:1. The increased G3P levels induced several transcriptional alterations of genes involved in the glycerolipid pathways. In particular, genes encoding the enzymes responsible for de novo glycerolipid synthesis were largely upregulated in the transgenic lines, in-line with the identified biochemical phenotype. These results reveal a key role for GmGPDHp1-mediated G3P metabolism in enhancing TAG synthesis and demonstrate a strategy to modify the FA compositions of soybean oils for improved nutrition and biofuel.

Genome-wide association study identifies candidate genes related to oleic acid content in soybean seeds.

BACKGROUND: Soybean oil is a complex mixture of five fatty acids (palmitic, stearic, oleic, linoleic, and linolenic). Soybean oil with a high oleic acid content is desirable because this monounsaturated fatty acid improves the oxidative stability of the oil. To investigate the genetic architecture of oleic acid in soybean seeds, 260 soybean germplasms from Northeast China were collected as natural populations. A genome-wide association study (GWAS) was conducted on a panel of 260 germplasm resources. RESULTS: Phenotypic identification results showed that the oleic acid content varied from 8.2 to 35.0%. A total of 2,311,337 single-nucleotide polymorphism (SNP) markers were obtained. GWAS analysis showed that there were many genes related to oleic acid content with a contribution rate of 7%. The candidate genes Glyma.11G229600.1 on chromosome 11 and Glyma.04G102900.1 on chromosome 4 were detected in a 2-year-long GWAS. The candidate gene Glyma.11G229600.1 showed a positive correlation with the oleic acid content, and the correlation coefficient was 0.980, while Glyma.04G102900.1 showed a negative correlation, with a coefficient of - 0.964. CONCLUSIONS: Glyma.04G102900.1 on chromosome 4 and Glyma.11G229600.1 on chromosome 11 were detected in both analyses (2018 and 2019). Glyma.04G102900.1 and Glyma.11G229600.1 are new key candidate genes related to oleic acid in soybean seeds. These results will be useful for high-oleic soybean breeding.

Marker assisted selection of new high oleic and low linolenic winter oilseed rape (Brassica napus L.) inbred lines revealing good agricultural value.

Development of oilseed rape (Brassica napus L.) breeding lines producing oil characterized by high oleic and low linolenic acid content is an important goal of rapeseed breeding programs worldwide. Such kind of oil is ideal for deep frying and can also be used as a raw material for biodiesel production. By performing chemical mutagenesis using ethyl methanesulfonate, we obtained mutant winter rapeseed breeding lines that can produce oil with a high content of oleic acid (C18:1, more than 75%) and a low content of linolenic acid (C18:3, less than 3%). However, the mutant lines revealed low agricultural value as they were characterized by low seed yield, low wintering, and high content of glucosinolates in seed meal. The aim of this work was to improve the mutant lines and develop high-oleic and low-linolenic recombinants exhibiting both good oil quality and high agronomic value. The plant materials used in this study included high-oleic and low-linolenic mutant breeding lines and high-yielding domestic canola-type breeding lines of good agricultural value with high oleic acid content and extremely low glucosinolates content. Field trials were conducted in four environments, in a randomized complete block design. Phenotyping was performed for wintering, yield of seed and oil, and seed quality traits. Genotype × environment interaction was investigated with respect to the content of C18:1 and C18:3 acids in seed oil. Genotyping was done for the selection of homozygous high oleic and low linolenic lines using allele-specific CAPS markers and SNaPshot assay, respectively. Finally, new high oleic and low linolenic winter rapeseed recombinant lines were obtained for use as a starting material for the development of new varieties that may be of high value on the oil crop market.

Group V secreted phospholipase A2 plays a protective role against aortic dissection.

Aortic dissection is a life-threatening aortopathy involving separation of the aortic wall, whose underlying mechanisms are still incompletely understood. Epidemiological evidence suggests that unsaturated fatty acids improve cardiovascular health. Here, using quantitative RT-PCR, histological analyses, magnetic cell sorting and flow cytometry assays, and MS-based lipidomics, we show that the activity of a lipid-metabolizing enzyme, secreted phospholipase A2 group V (sPLA2-V), protects against aortic dissection by endogenously mobilizing vasoprotective lipids. Global and endothelial cell-specific sPLA2-V-deficient mice frequently developed aortic dissection shortly after infusion of angiotensin II (AT-II). We observed that in the AT-II-treated aorta, endothelial sPLA2-V mobilized oleic and linoleic acids, which attenuated endoplasmic reticulum stress, increased the expression of lysyl oxidase, and thereby stabilized the extracellular matrix in the aorta. Of note, dietary supplementation with oleic or linoleic acid reversed the increased susceptibility of sPLA2-V-deficient mice to aortic dissection. These findings reveal an unexplored functional link between sPLA2-driven phospholipid metabolism and aortic stability, possibly contributing to the development of improved diagnostic and/or therapeutic strategies for preventing aortic dissection.

Raman Spectroscopy Enables Non-Invasive Identification of Peanut Genotypes and Value-Added Traits.

Identification of specific genotypes can be accomplished by visual recognition of their distinct phenotypical appearance, as well as DNA analysis. Visual identification (ID) of species is subjective and usually requires substantial taxonomic expertise. Genotyping and sequencing are destructive, time- and labor-consuming. In this study, we investigate the potential use of Raman spectroscopy (RS) as a label-free, non-invasive and non-destructive analytical technique for the fast and accurate identification of peanut genotypes. We show that chemometric analysis of peanut leaflet spectra provides accurate identification of different varieties. This same analysis can be used for prediction of nematode resistance and oleic-linoleic oil (O/L) ratio. Raman-based analysis of seeds provides accurate genotype identification in 95% of samples. Additionally, we present data on the identification of carbohydrates, proteins, fiber and other nutrients obtained from spectroscopic signatures of peanut seeds. These results demonstrate that RS allows for fast, accurate and non-invasive screening and selection of plants which can be used for precision breeding.

Multi-level engineering of Baeyer-Villiger monooxygenase-based Escherichia coli biocatalysts for the production of C9 chemicals from oleic acid.

Whole-cell biotransformation is one of the promising alternative approaches to microbial fermentation for producing high-value chemicals. Baeyer-Villiger monooxygenase (BVMO)-based Escherichia coli biocatalysts have been engineered to produce industrially relevant C9 chemicals, such as n-nonanoic acid and 9-hydroxynonanoic acid, from a renewable long-chain fatty acid. The key enzyme in the biotransformation pathway (i.e., BVMO from Pseudomonans putida KT2440) was first engineered, using structure modeling-based design, to improve oxidative and thermal stabilities. Using a stable and tunable plasmid (STAPL) system, E. coli host cells were engineered to have increased plasmid stability and homogeneity of the recombinant E. coli population, as well as to optimize the level of BVMO expression. Multi-level engineering of the key enzyme in host cells, allowed recombinant E. coli expressing a fatty acid double-bond hydratase, a long-chain secondary alcohol dehydrogenase, and the engineered BVMO from P. putida KT2440 (i.e., E6BVMO_C302L/M340L), to ultimately produce C9 chemicals (i.e., n-nonanoic acid and 9-hydroxynonanoic acid) from oleic acid, with a yield of up to 6 mmoL/g dry cells. This yield was 2.4-fold greater than the yield in the control strain before engineering. Therefore, this study will contribute to the development of improved processes for the biosynthesis of industrially relevant medium chain fatty acids via whole-cell biocatalysis.

Vitamin A deficiency increases the oleic acid (C18:1) levels in the kidney of high fructose diet-fed rats.

Background & objectives: Stearoyl-CoA desaturase 1 (SCD1) is a key lipogenic enzyme responsible for endogenous synthesis of monounsaturated fatty acids (MUFA) and plays a key role in various pathophysiology, including fatty liver diseases. In this experimental study the impact of vitamin A deficiency was assessed on SCD1 regulation in relation to kidney biology, under high fructose (HFr) diet-fed condition in rats. Methods: Forty male weanling (21 day old) Wistar rats were divided into four groups control, vitamin A-deficient (VAD), HFr, VAD with HFr consisting of eight rats each, except 16 for the VAD group. The groups received one of the following diets: control, VAD, HFr and VAD with HFr for 16 wk, except half of the VAD diet-fed rats were shifted to HFr diet, after eight week period. Results: Feeding of VAD diet (alone or with HFr) significantly reduced the kidney retinol (0.51, 0.44 µg/g vs. 2.1 µg/g; P < 0.05), while increased oleic (C18:1) and total MUFA levels (23.3, 22.2% and 27.3, 25.4% respectively vs. 14.7 and 16.6%; P < 0.05) without affecting the SCD1, both at protein and mRNA levels, when compared with HFr. Comparable, immunohistological staining for SCD1 was observed in the distal convoluted tubules. Despite an increase in MUFA, morphology, triglyceride content and markers of kidney function were not affected by VAD diet feeding. Interpretation & conclusions: Feeding of VAD diet either alone or under HFr condition increased the kidney oleic acid (C18:1) levels and thus total MUFA, which corroborated with elevated SCD1 activity index, without affecting its expression status. However, these changes did not alter the kidney morphology and function. Thus, nutrient-gene regulation in kidney biology seems to be divergent.

Production of high oleic/low linoleic rice by genome editing.

Rice bran oil (RBO) contains many valuable healthy constituents, including oleic acid. Improvement of the fatty acid composition in RBO, including an increase in the content of oleic acid, which helps suppress lifestyle disease, would increase health benefits. The enzyme fatty acid desaturase 2 (FAD2) catalyzes the conversion of oleic acid to linoleic acid in plants, and FAD2 mutants exhibit altered oleic and linoleic acid content in many crops. There are three functional FAD2 genes in the genome of rice (Oryza sativa L.), and, of these, expression of the OsFAD2-1 gene is highest in rice seeds. In order to produce high oleic/low linoleic RBO, we attempted to disrupt the OsFAD2-1 gene by CRISPR/Cas9-mediated targeted mutagenesis. We succeeded in the production of homozygous OsFAD2-1 knockout rice plants. The content of oleic acid increased to more than twice that of wild type, and, surprisingly, linoleic acid, a catabolite of oleic acid by FAD2, decreased dramatically to undetectable levels in fad2-1 mutant brown rice seeds. In this study, by genome editing based on genome information, we succeeded in the production of rice whose fatty acid composition is greatly improved. We suggest that CRISPR/Cas9-mediated mutagenesis of a major gene that shows dominant expression in the target tissue could be a powerful tool to improve target traits in a tissue-specific manner.

Correlation of trans fatty acids with the severity of coronary artery disease lesions.

BACKGROUND: Nutritional choices, which include the source of dietary fatty acids (FA), have an important significant impact on coronary artery disease (CAD). We aimed to determine on patients with CAD the relationships between Trans fatty acids (Trans FA) and different CAD associated parameters such as inflammatory and oxidative stress parameters in addition to Gensini score as a vascular severity index. METHODS: Fatty acid profiles were established by gas chromatography from 111 CAD patients compared to 120 age-matched control group. Lipid peroxidation biomarkers, oxidative stress, inflammatory parameters and Gensini score were studied. RESULTS: Our study showed a significant decrease of the antioxidant parameters levels such as erythrocyte glutathione peroxydase (GPx) and superoxide dismutase (SOD) activities, plasma antioxidant status (FRAP) and thiol (SH) groups in CAD patients. On the other hand, catalase activity, conjugated dienes and malondialdehyde were increased. Plasmatic and erythrocyte Trans FA were also increased in CAD patients compared to controls. Furthermore, divergent associations of these Trans FA accumulations were observed with low-density lipoprotein-cholesterol/ high-density lipoprotein-cholesterol (LDL-C/HDL-C) ratio, Apolipoprotein B (ApoB), lipid peroxidation parameters, high-sensitivity C Reactive Protein (hs-CRP), Interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α) and Gensini score. Especially, elaidic acid (C18:1 trans 9), trans C18:2 isomers and trans 11 eicosanoic acid are correlated with these parameters. Trans FA are also associated with oxidative stress, confirmed by a positive correlation between C20:1 trans 11 and GPx in erythrocytes. CONCLUSIONS: High level of Trans FA was highly associated with the induction of inflammation, oxidative stress and lipoperoxidation which appear to be based on the vascular severity and might be of interest to assess the stage and progression of atherosclerosis. The measurement of these Trans FA would be of great value for the screening of lipid metabolism disorders in CAD patients.

Comparative genome analysis to identify SNPs associated with high oleic acid and elevated protein content in soybean.

The objective of this study was to determine the genetic relationship between the oleic acid and protein content. The genotypes having high oleic acid and elevated protein (HOEP) content were crossed with five elite lines having normal oleic acid and average protein (NOAP) content. The selected accessions were grown at six environments in three different locations and phenotyped for protein, oil, and fatty acid components. The mean protein content of parents, HOEP, and NOAP lines was 34.6%, 38%, and 34.9%, respectively. The oleic acid concentration of parents, HOEP, and NOAP lines was 21.7%, 80.5%, and 20.8%, respectively. The HOEP plants carried both FAD2-1A (S117N) and FAD2-1B (P137R) mutant alleles contributing to the high oleic acid phenotype. Comparative genome analysis using whole-genome resequencing data identified six genes having single nucleotide polymorphism (SNP) significantly associated with the traits analyzed. A single SNP in the putative gene Glyma.10G275800 was associated with the elevated protein content, and palmitic, oleic, and linoleic acids. The genes from the marker intervals of previously identified QTL did not carry SNPs associated with protein content and fatty acid composition in the lines used in this study, indicating that all the genes except Glyma.10G278000 may be the new genes associated with the respective traits.

Genome of wild olive and the evolution of oil biosynthesis.

Here we present the genome sequence and annotation of the wild olive tree (Olea europaea var. sylvestris), called oleaster, which is considered an ancestor of cultivated olive trees. More than 50,000 protein-coding genes were predicted, a majority of which could be anchored to 23 pseudochromosomes obtained through a newly constructed genetic map. The oleaster genome contains signatures of two Oleaceae lineage-specific paleopolyploidy events, dated at ∼28 and ∼59 Mya. These events contributed to the expansion and neofunctionalization of genes and gene families that play important roles in oil biosynthesis. The functional divergence of oil biosynthesis pathway genes, such as FAD2, SACPD, EAR, and ACPTE, following duplication, has been responsible for the differential accumulation of oleic and linoleic acids produced in olive compared with sesame, a closely related oil crop. Duplicated oleaster FAD2 genes are regulated by an siRNA derived from a transposable element-rich region, leading to suppressed levels of FAD2 gene expression. Additionally, neofunctionalization of members of the SACPD gene family has led to increased expression of SACPD2, 3, 5, and 7, consequently resulting in an increased desaturation of steric acid. Taken together, decreased FAD2 expression and increased SACPD expression likely explain the accumulation of exceptionally high levels of oleic acid in olive. The oleaster genome thus provides important insights into the evolution of oil biosynthesis and will be a valuable resource for oil crop genomics.

Direct stacking of sequence-specific nuclease-induced mutations to produce high oleic and low linolenic soybean oil.

BACKGROUND: The ability to modulate levels of individual fatty acids within soybean oil has potential to increase shelf-life and frying stability and to improve nutritional characteristics. Commodity soybean oil contains high levels of polyunsaturated linoleic and linolenic acid, which contribute to oxidative instability - a problem that has been addressed through partial hydrogenation. However, partial hydrogenation increases levels of trans-fatty acids, which have been associated with cardiovascular disease. Previously, we generated soybean lines with knockout mutations within fatty acid desaturase 2-1A (FAD2-1A) and FAD2-1B genes, resulting in oil with increased levels of monounsaturated oleic acid (18:1) and decreased levels of linoleic (18:2) and linolenic acid (18:3). Here, we stack mutations within FAD2-1A and FAD2-1B with mutations in fatty acid desaturase 3A (FAD3A) to further decrease levels of linolenic acid. Mutations were introduced into FAD3A by directly delivering TALENs into fad2-1a fad2-1b soybean plants. RESULTS: Oil from fad2-1a fad2-1b fad3a plants had significantly lower levels of linolenic acid (2.5 %), as compared to fad2-1a fad2-1b plants (4.7 %). Furthermore, oil had significantly lower levels of linoleic acid (2.7 % compared to 5.1 %) and significantly higher levels of oleic acid (82.2 % compared to 77.5 %). Transgene-free fad2-1a fad2-1b fad3a soybean lines were identified. CONCLUSIONS: The methods presented here provide an efficient means for using sequence-specific nucleases to stack quality traits in soybean. The resulting product comprised oleic acid levels above 80 % and linoleic and linolenic acid levels below 3 %.

The relationship of the oleic acid level and ECHDC3 mRNA expression with the extent of coronary lesion.

BACKGROUND: The fatty acid profile is associated with the risk and progression of several diseases, probably via mechanisms including its influence on gene expression. We previously reported a correlation between ECHDC3 upregulation and the severity of acute coronary syndrome. Here, we assessed the relationship of serum fatty acid profile and ECHDC3 expression with the extent of coronary lesion. METHODS: Fifty-nine individuals aged 30 to 74 years and undergoing elective cinecoronariography for the first time were enrolled in the present study. The extent of coronary lesion was assessed by the Friesinger index and patients were classified as without lesion (n = 18), low lesion (n = 17), intermediate lesion (n = 17) and major lesion (n = 7). Serum biochemistry, fatty acid concentration, and ECHDC3 mRNA expression in blood were evaluated. RESULTS: Elevated serum levels of oleic acid and total monounsaturated fatty acids were observed in patients with low and intermediate lesion, when compared to patients without lesion (p < 0.05). ECHDC3 mRNA expression was 1.2 fold higher in patients with low lesion than in patients without lesion (p = 0.020), and 1.8 fold lower in patients with major lesion patients than in patients with low lesion (p = 0.023). CONCLUSION: Increased levels of monounsaturated fatty acids, especially oleic acid, and ECHDC3 upregulation in patients with coronary artery lesion suggests that these are independent factors associated with the initial progression of cardiovascular disease.

Identification of Novel Genetic Determinants of Erythrocyte Membrane Fatty Acid Composition among Greenlanders.

Fatty acids (FAs) are involved in cellular processes important for normal body function, and perturbation of FA balance has been linked to metabolic disturbances, including type 2 diabetes. An individual's level of FAs is affected by diet, lifestyle, and genetic variation. We aimed to improve the understanding of the mechanisms and pathways involved in regulation of FA tissue levels, by identifying genetic loci associated with inter-individual differences in erythrocyte membrane FA levels. We assessed the levels of 22 FAs in the phospholipid fraction of erythrocyte membranes from 2,626 Greenlanders in relation to single nucleotide polymorphisms genotyped on the MetaboChip or imputed. We identified six independent association signals. Novel loci were identified on chromosomes 5 and 11 showing strongest association with oleic acid (rs76430747 in ACSL6, beta (SE): -0.386% (0.034), p = 1.8x10-28) and docosahexaenoic acid (rs6035106 in DTD1, 0.137% (0.025), p = 6.4x10-8), respectively. For a missense variant (rs80356779) in CPT1A, we identified a number of novel FA associations, the strongest with 11-eicosenoic acid (0.473% (0.035), p = 2.6x10-38), and for variants in FADS2 (rs174570), LPCAT3 (rs2110073), and CERS4 (rs11881630) we replicated known FA associations. Moreover, we observed metabolic implications of the ACSL6 (rs76430747) and CPT1A (rs80356779) variants, which both were associated with altered HbA1c (0.051% (0.013), p = 5.6x10-6 and -0.034% (0.016), p = 3.1x10-4, respectively). The latter variant was also associated with reduced insulin resistance (HOMA-IR, -0.193 (0.050), p = 3.8x10-6), as well as measures of smaller body size, including weight (-2.676 kg (0.523), p = 2.4x10-7), lean mass (-1.200 kg (0.271), p = 1.7x10-6), height (-0.966 cm (0.230), p = 2.0x10-5), and BMI (-0.638 kg/m2 (0.181), p = 2.8x10-4). In conclusion, we have identified novel genetic determinants of FA composition in phospholipids in erythrocyte membranes, and have shown examples of links between genetic variants associated with altered FA membrane levels and changes in metabolic traits.

Oleic acid activates MMPs up-regulation through SIRT1/PPAR-γ inhibition: a probable linkage between obesity and coronary arterial disease.

Obesity is positively related to the growing prevalence of coronary arterial disease (CAD). It is well established in terms of the plasma concentrations of free fatty acid (FFA) that are up-regulated in cases associating with obesity. Oleic acid (OA) is known as the most abundant monounsaturated fatty acid in the human circulatory system. Several pro-atherosclerotic responses of OA have been established. Sirtuin 1 (SIRT1) acts as a key role in regulating the normal physical function in smooth muscle cells (SMCs). SIRT1 activation is developed as a novel approach to delay the progression of atherosclerotic injuries. However, the mechanism is still unclear as to whether OA affects SIRT1 expression and its activity in SMCs. We confirmed that OA treatment represses SIRT1 and peroxisome proliferator-activated receptors-γ levels in SMCs. Moreover, OA enhances by transforming the growth factor-ß1 (TGF-ß1) release via activation of NF-κB. OA causes NO production by inducing the inducible nitric oxide synthase overexpression, thereby promoting the secretions of matrix metalloproteinases-1 (MMP-1) and MMP-3. Overall, we suggested that OA enhances MMPs activation through SIRT1 down-regulation. Therefore, our findings might provide a novel route for developing new therapeutic treatments for FFAs-related CADs.

Oleic acid induces specific alterations in the morphology, gene expression and steroid hormone production of cultured bovine granulosa cells.

After parturition, one of the major problems related to nutritional management that is faced by the majority of dairy cows is negative energy balance (NEB). During NEB, excessive lipid mobilization takes place and hence the levels of free fatty acids, among them oleic acid, increase in the blood, but also in the follicular fluid. This accumulation can be associated with serious metabolic and reproductive disorders. In the present study, we analyzed the effects of physiological concentrations of oleic acid on cell morphology, apoptosis, necrosis, proliferation and steroid production, and on the abundance of selected transcripts in cultured bovine granulosa cells. Increasing oleic acid concentrations induced intracellular lipid droplet accumulation, thus resulting in a foam cell-like morphology, but had no effects on apoptosis, necrosis or proliferation. Oleic acid also significantly reduced the transcript abundance of the gonadotropin hormone receptors, FSHR and LHCGR, steroidogenic genes STAR, CYP11A1, HSD3B1 and CYP19A1, the cell cycle regulator CCND2, but not of the proliferation marker PCNA. In addition, treatment increased the transcript levels of the fatty acid transporters CD36 and SLC27A1, and decreased the production of 17-beta-estradiol and progesterone. From these data it can be concluded that oleic acid specifically affects morphological and physiological features and gene expression levels thus altering the functionality of granulosa cells. Suggestively, these effects might be partly due to the reduced expression of FSHR and thus the reduced responsiveness to FSH stimulation.

Insights into the novel members of the FAD2 gene family involved in high-oleate fluxes in peanut.

The FAD2 gene family is functionally responsible for the conversion of oleic acid to linoleic acid in oilseed plants. Multiple members of the FAD gene are known to occur in several oilseed species. In this study, six novel full-length cDNA sequences (named as AhFAD2-1, -2, -3, -4, -5, and -6) were identified in peanut (Arachis hypogaea L.), an analysis of which revealed open reading frames of 379, 383, 394, or 442 amino acids. Sequence comparisons showed that AhFAD2-1 and AhFAD2-2 shared 76% identity, while AhFAD2-2, -3, and -4 displayed highly significant homology. There was only 27% identity overlap between the microsomal ω-6 fatty acid desaturase and the chloroplast ω-6 fatty acid desaturase encoded by AhFAD2-1, -2, -3, -4, and AhFAD2-5, -6, respectively. The phylogeny tree of FAD2 transcripts showed five major groups, and AhFAD2-1 was clearly separated from other groups. Analysis of AhFAD2-1 and AhFAD2-2 transcript distribution in different peanut tissues showed that the AhFAD2-1 gene showed upward of a 70-fold increase in expression of fatty acid than the AhFAD2-2 gene in peanut developing seeds, while the AhFAD2-2 gene expressed most abundantly in peanut flowers. Because the AhFAD2-1 gene played a major role in the conversion of oleic to linoleic acid during seed development, the identification of this novel member in this study would facilitate the further genetic manipulation of peanut oil quality. The implications of overall results also suggest that there may be more candidate genes controlling levels of oleate acid in developing seeds. Results also may be due to the presence of complex gene networks controlling the fluxes between the endoplasmic reticulum and the chloroplast within the peanut cells.

Composition of fatty acids in virgin olive oils from cross breeding segregating populations by gas chromatography separation with flame ionization detection.

BACKGROUND: Recent technological advances to improve the quality of virgin olive oil (VOO) have been focused on olive breeding programs by selecting outstanding cultivars and target progenies. Fatty acid (FA) composition, with special emphasis on oleic acid (C18:1) and palmitic acid (C16:0), is one of the most critical quality factors to be evaluated in VOO. For this reason, the profile of FAs is frequently used as a decision tool in olive breeding programs. RESULTS: A method based on gas chromatography with flame ionization detection (GC-FID) was used to study the influence of genotype on the concentration of ten of the most important FAs in VOOs from target crosses Arbequina × Arbosana, Picual × Koroneiki and Sikitita × Arbosana and their corresponding genitors Arbequina, Arbosana, Koroneiki, Picual and Sikitita. For this purpose, a targeted approach was selected for determination of esterified FAs (EFAs) and non-esterified FAs (NEFAs) in a dual analysis by the same chromatographic method. A Pearson analysis revealed correlations between pairs of FAs, which allowed detecting metabolic connections through desaturation and elongation enzymes. An ANOVA test (with P < 0.01) led to identification of C16:0 EFA, C16:1 EFA and C18:1 EFA and also C16:1 NEFA and C18:0 NEFA as the FAs more influenced by cross breeding. Statistical analysis was carried out by unsupervised analysis using principal component analysis (PCA) and cluster analysis (CA) to look for variability sources. CONCLUSION: Crosses with a common genitor (Arbequina × Arbosana and Sikitita × Arbosana) were partially overlapped in the PCAs using the profile of FAs. The CA results revealed clear differences between Sikitita × Arbosana and Picual × Koroneiki crosses in the composition of the most significant FAs, while Arbequina × Arbosana was not properly discriminated from the other crosses.

Identification and expression of a stearoyl-ACP desaturase gene responsible for oleic acid accumulation in Xanthoceras sorbifolia seeds.

Xanthoceras sorbifolia Bunge is an oilseed tree that grows well on barren lands in dry climate. Its seeds contain a large amount of oil rich in oleic acid (18:1(Δ9)) and linoleic acid (18:2(Δ9, 12)). However, the molecular regulation of oil biosynthesis in X. sorbifolia seeds is poorly understood. Stearoyl-ACP desaturase (SAD, EC 1.14.99.6) is a plastid-localized soluble desaturase that catalyzes the conversion of stearic acid (18:0) to oleic acid, which plays a key role in determining the ratio of saturated to unsaturated fatty acids. In this study, a full-length cDNA of XsSAD was isolated from developing X. sorbifolia embryos. The XsSAD open reading frame had 1194-bp, encoding a polypeptide of 397 amino acids. XsSAD expression in Escherichia coli cells resulted in increased 18:1(Δ9) level, confirming the biological activity of the enzyme encoded by XsSAD. XsSAD expression in Arabidopsis ssi2 mutants partially restored the morphological phenotype and effectively increased the 18:1(Δ9) level. The levels of other unsaturated fatty acids synthesized with 18:1(Δ9) as the substrate also increased to some degree. XsSAD in X. sorbifolia had a much higher expression in embryos than in leaves and petals. XsSAD expression also correlated well with the oleic acid, unsaturated fatty acid, and total fatty acid levels in developing embryos. These data suggested that XsSAD determined the synthesis of oleic acid and contributed to the accumulation of unsaturated fatty acid and total oil in X. sorbifolia seeds. A preliminary tobacco rattle virus-based virus-induced gene silencing system established in X. sorbifolia can also be helpful for further analyzing the functions of XsSAD and other oil synthesis-related genes in woody plants.