Causal analysis of serum polyunsaturated fatty acids with juvenile idiopathic arthritis and ocular comorbidity.

BACKGROUND & OBJECTIVE: To investigate the causal effects of plasma Polyunsaturated fatty acids (PUFAs) on the risk of juvenile idiopathic arthritis (JIA) and ocular comorbidity through Mendelian randomization (MR) analysis. METHODS: Genetic variants (formerly single nucleotide polymorphisms, SNPs) that are strongly associated with PUFAs levels (P < 5×10-8) were selected as instrumental variables. Summary-level MR was performed with outcome estimates for JIA (n = 31,142) and JIA associated iridocyclitis (n = 94,197). The inverse variance-weighted (IVW) method was employed as the main approach to combine the estimation for each SNP. Two set of models with summary statistics were conducted and multiple sensitivity analyses were applied for testing of pleiotropic bias. RESULTS: In model 1, genetically predicted n-6 PUFAs linoleic acid (LA) and arachidonic acid (AA) were associated with lower and higher risk of JIA associated iridocyclitis using IVW (ORLA = 0.940, 95% CI: 0.895-0.988, P = 0.015; ORAA = 1.053, 95% CI: 1.007-1.101, P = 0.024). No such association was observed between each plasma PUFAs and JIA susceptibility (P > 0.05). In further MR analysis, results from model 2 also showed a consistent trend. Besides, multiple sensitivity analyses revealed that there was no obvious evidence for unknown pleiotropy (P > 0.05). CONCLUSIONS: Our MR study provides genetic evidence on the possible causality that plasma LA level might protect against JIA associated iridocyclitis, whereas AA was responsible for opposite effect.

Quantitative proteomic and lipidomics analyses of high oil content GmDGAT1-2 transgenic soybean illustrate the regulatory mechanism of lipoxygenase and oleosin.

KEY MESSAGE: Proteomic and lipidomics analyses of WT and GmDGAT1-2 transgenic soybeans showed that GmDGAT1-2 over-expression induced lipoxygenase down-regulatation and oleoin up-regulatation, which significantly changed the compositions and total fatty acid. The main goal of soybean breeding is to increase the oil content. Diacylglycerol acyltransferase (DGAT) is a key rate-limiting enzyme in fatty acid metabolism and may regulate oil content. Herein, 10 GmDGAT genes were isolated from soybean and transferred into wild-type (WT) Arabidopsis. The total fatty acid was 1.2 times higher in T3 GmDGAT1-2 transgenic Arabidopsis seeds than in WT. Therefore, GmDGAT1-2 was transferred into WT soybean (JACK), and four T3 transgenic soybean lines were obtained. The results of high-performance gas chromatography and Soxhlet extractor showed that, compared with those of JACK, oleic acid (18:1), and total fatty acid levels in transgenic soybean plants were much higher, but linoleic acid (18:2) was lower than WT. Palmitic acid (16:0), stearic acid (18:0), and linolenic acid (18:3) were not significantly different. For mechanistic studies, 436 differentially expressed proteins (DEPs) and 180 differentially expressed metabolites (DEMs) were identified between WT (JACK) and transgenic soybean pods using proteomic and lipidomics analyses. Four lipoxygenase proteins were down-regulated in linoleic acid metabolism while four oleosin proteins were up-regulated in the final oil formation. The results showed an increase in the total fatty acid and 18:1 composition, and a decrease in the 18:2 composition of fatty acid. Our study brings new insights into soybean genetic transformation and the deep study of molecular mechanism that changes the total fatty acid, 18:1, and 18:2 compositions in GmDGAT1-2 transgenic soybean.

Transcriptomic Analysis Reveals Key Genes Involved in Oil and Linoleic Acid Biosynthesis during Artemisia sphaerocephala Seed Development.

Artemisia sphaerocephala seeds are rich in polysaccharides and linoleic acid (C18:2), which have been widely used as traditional medicine and to improve food quality. The accumulation patterns and molecular regulatory mechanisms of polysaccharides during A. sphaerocephala seed development have been studied. However, the related research on seed oil and C18:2 remain unclear. For this study, A. sphaerocephala seeds at seven different development stages at 10, 20, 30, 40, 50, 60, and 70 days after flowering (designated as S1~S7), respectively, were employed as experimental samples, the accumulation patterns of oil and fatty acids (FA) and the underlying molecular regulatory mechanisms were analyzed. The results revealed that oil content increased from 10.1% to 20.0% in the early stages of seed development (S1~S2), and up to 32.0% in mature seeds, of which C18:2 accounted for 80.6% of the total FA. FA and triacylglycerol biosynthesis-related genes jointly involved in the rapid accumulation of oil in S1~S2. Weighted gene co-expression network analysis showed that transcription factors FUS3 and bHLH played a critical role in the seed oil biosynthesis. The perfect harmonization of the high expression of FAD2 with the extremely low expression of FAD3 regulated the accumulation of C18:2. This study uncovered the gene involved in oil biosynthesis and molecular regulatory mechanisms of high C18:2 accumulation in A. sphaerocephala seeds; thus, advancing research into unsaturated fatty acid metabolism in plants while generating valuable genetic resources for optimal C18:2 breeding.

Seed specifically over-expressing DGAT2A enhances oil and linoleic acid contents in soybean seeds.

Triacylglycerol (TAG), a main component of oil, is mainly biosynthesized by diacylglycerol acyltransferase (DGAT), which is critical for oil accumulation in plants. Intensive focus has been on DGAT2 functioning in unsaturated fatty acids biosynthesis. In this study, we analyzed the coding sequence (CDS) and amino acid sequence of GmDGAT2A and determined its key active sites through site-directed mutagenesis. As a consequence, H132, G201, and P152-X-I154-K155 were found to be essential active sites for GmDGAT2A. The spatial structure of the protein may bring the three active sites into close proximity, constituting an active domain. Additionally, N-terminus of GmDGAT2A was found to be an important regulator for the activity. Further, in vitro activity results uncovered GmDGAT2A was prone to utilize C18:2-CoA as the substrate. Consequently, overexpression of GmDGAT2A driven by a seed-specific promoter of Gmole1 in soybean significantly increased linoleic acid content specifically and total oil content, concomitant with accelerated elongation.

Lipidomic and transcriptional analysis of the linoleoyl-omega-hydroxyceramide biosynthetic pathway in human psoriatic lesions.

A complex assembly of lipids including fatty acids, cholesterol, and ceramides is vital to the integrity of the mammalian epidermal barrier. The formation of this barrier requires oxidation of the substrate fatty acid, linoleic acid (LA), which is initiated by the enzyme 12R-lipoxygenase (LOX). In the epidermis, unoxidized LA is primarily found in long-chain acylceramides termed esterified omega-hydroxy sphingosine (EOS)/phytosphingosine/hydroxysphingosine (collectively EOx). The precise structure and localization of LOX-oxidized EOx in the human epidermis is unknown, as is their regulation in diseases such as psoriasis, one of the most common inflammatory diseases affecting the skin. Here, using precursor LC/MS/MS, we characterized multiple intermediates of EOx, including 9-HODE, 9,10-epoxy-13-HOME, and 9,10,13-TriHOME, in healthy human epidermis likely to be formed via the epidermal LOX pathways. The top layers of the skin contained more LA, 9-HODE, and 9,10,13-TriHOME EOSs, whereas 9,10-epoxy-13-HOME EOS was more prevalent deeper in the stratum corneum. In psoriatic lesions, levels of native EOx and free HODEs and HOMEs were significantly elevated, whereas oxidized species were generally reduced. A transcriptional network analysis of human psoriatic lesions identified significantly elevated expression of the entire biosynthetic/metabolic pathway for oxygenated ceramides, suggesting a regulatory function for EOx lipids in reconstituting epidermal integrity. The role of these new lipids in progression or resolution of psoriasis is currently unknown. We also discovered the central coordinated role of the zinc finger protein transcription factor, ZIC1, in driving the phenotype of this disease. In summary, long-chain oxygenated ceramide metabolism is dysregulated at the lipidomic level in psoriasis, likely driven by the transcriptional differences also observed, and we identified ZIC1 as a potential regulatory target for future therapeutic interventions.

Causal Effects of N-6 Polyunsaturated Fatty Acids on Age-related Macular Degeneration: A Mendelian Randomization Study.

CONTEXT: Although the role of n-6 polyunsaturated fatty acids (PUFAs) in age-related macular degeneration (AMD) has been studied in previous observational studies, the precise manner in which 1 or more n-6 PUFAs account for this relationship remains unclear. OBJECTIVE: Using genetic instruments for n-6 PUFAs traits implemented through mendelian randomization (MR), we aimed to study possible causal associations between n-6 PUFAs and AMD. METHODS: The 2-sample MR method was used to obtain unconfounded causal estimates. We selected genetic variants strongly associated (P < 5 × 10-8) with circulating linoleic acid (LA) and arachidonic acid (AA) from a study involving 8 631 individuals and applied to an AMD case-control study (33 526 participants and 16 144 cases). The weighted median and MR Egger methods were used for the sensitivity analysis. RESULTS: Our MR analysis suggested that circulating LA was a causal protective factor for AMD, with an odds ratio (OR) estimate of 0.967 (95% CI 0.945 to 0.990; P = .005) per percentage in total fatty acid increase in LA. In contrast, higher genetically predicted circulating AA causally increased the AMD risk (OR = 1.034; 95% CI 1.012 to 1.056; P = .002). Sensitivity analysis provided no indication of unknown pleiotropy. The findings from different single-nucleotide polymorphism selections and analytic methods were consistent, suggesting the robustness of the causal associations. CONCLUSION: Our study provided genetic evidence that circulating LA accounted for protective effects of n-6 PUFAs against the risk of AMD, whereas AA was responsible for deleterious effects on higher AMD risk.

Insights into profiling of volatile ester and LOX-pathway related gene families accompanying post-harvest ripening of 'Nanguo' pears.

'Nanguo' pear is particularly renowned for its fragrance. Esters are the main components of its aroma, which are synthesized primarily by the LOX pathway. We identified the main volatile esters and critical gene family members involved in the LOX pathway by monitoring their variation accompanying post-harvest ripening and examining their roles through principal component analysis (PCA), partial least-square regression (PLSR), and correlation analysis. In pears ripening to the optimum taste period (OTP), components and contents of volatile esters reached a peak, of which ethyl butanoate, ethyl hexanoate, and hexyl acetate were most prominent. Linoleic acid and linolenic acid contents rose greatly until OTP and then declined; the activities of LOX, alcohol dehydrogenase (ADH), and alcohol acyltransferase (AAT) increased progressively until the OTP. Among the genes involved in LOX-pathway, the expressions of PuLOX3, PuADH3, and PuAAT contributed most to changes of total ester and main esters in 'Nanguo' pears.

Genome-Wide Association Study Identifies Candidate Genes Related to the Linoleic Acid Content in Soybean Seeds.

Soybean (Glycine max (L.) Merrill) oil is a complex mixture of five fatty acids (palmitic, stearic, oleic, linoleic, and linolenic). The high content of linoleic acid (LA) contributes to the oil having poor oxidative stability. Therefore, soybean seed with a lower LA content is desirable. To investigate the genetic architecture of LA, we performed a genome-wide association study (GWAS) using 510 soybean cultivars collected from China. The phenotypic identification results showed that the content of LA varied from 36.22% to 72.18%. The GWAS analysis showed that there were 37 genes related to oleic acid content, with a contribution rate of 7%. The candidate gene Glyma.04G116500.1 (GmWRI14) on chromosome 4 was detected in three consecutive years. The GmWRI14 showed a negative correlation with the LA content and the correlation coefficient was -0.912. To test whether GmWRI14 can lead to a lower LA content in soybean, we introduced GmWRI14 into the soybean genome. Matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI-TOF IMS) showed that the overexpression of GmWRI14 leads to a lower LA content in soybean seeds. Meanwhile, RNA-seq verified that GmWRI14-overexpressed soybean lines showed a lower accumulation of GmFAD2-1A and GmFAD2-1B than control lines. Our results indicate that the down-regulation of the FAD2 gene triggered by the transcription factor GmWRI14 is the underlying mechanism reducing the LA level of seed. Our results provide novel insights into the genetic architecture of LA and pinpoint potential candidate genes for further in-depth studies.

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.

PhoQ is an unsaturated fatty acid receptor that fine-tunes Salmonella pathogenic traits.

The Salmonella enterica PhoP/PhoQ two-component signaling system coordinates the spatiotemporal expression of key virulence factors that confer pathogenic traits. Through biochemical and structural analyses, we found that the sensor histidine kinase PhoQ acted as a receptor for long-chain unsaturated fatty acids (LCUFAs), which induced a conformational change in the periplasmic domain of the PhoQ protein. This resulted in the repression of PhoQ autokinase activity, leading to inhibition of the expression of PhoP/PhoQ-dependent genes. Recognition of the LCUFA linoleic acid (LA) by PhoQ was not stereospecific because positional and geometrical isomers of LA equally inhibited PhoQ autophosphorylation, which was conserved in multiple S. enterica serovars. Because orally acquired Salmonella encounters conjugated LA (CLA), a product of the metabolic conversion of LA by microbiota, in the human intestine, we tested how short-term oral administration of CLA affected gut colonization and systemic dissemination in a mouse model of Salmonella-induced colitis. Compared to untreated mice, CLA-treated mice showed increased gut colonization by wild-type Salmonella, as well as increased dissemination to the spleen. In contrast, the inability of the phoP strain to disseminate systemically remained unchanged by CLA treatment. Together, our results reveal that, by inhibiting PhoQ, environmental LCUFAs fine-tune the fate of Salmonella during infection. These findings may aid in the design of new anti-Salmonella therapies.

Plasma Phospholipid Fatty Acids and Risk of Atrial Fibrillation: A Mendelian Randomization Study.

Available evidence on the associations of dietary and circulating levels of long-chain n-3 fatty acids, which have potential antiarrhythmic properties, and other fatty acids with atrial fibrillation is conflicting and limited. We conducted a Mendelian randomization study to assess the associations between plasma phospholipid fatty acid levels and atrial fibrillation. Summary-level data of atrial fibrillation were available from 65,446 cases and 522,744 non-cases included in the Atrial Fibrillation Consortium. Sixteen single-nucleotide polymorphisms associated with ten fatty acids at significance level of p < 5 × 10-8 were identified as instrumental variables from the hitherto largest genome-wide association studies for plasma fatty acids. The fixed-effects inverse-variance weighted method was used to assess the association of individual plasma fatty acids and atrial fibrillation risk. The random-effects inverse-variance weighted method, weighted median method, and Mendelian randomization (MR)-Egger method were employed as the sensitivity analyses. Genetic predisposition to higher levels of any of the ten individual fatty acids was not associated with atrial fibrillation risk.

Loss of virulence in NAD(P)H cytochrome b5 oxidoreductase deficient Leishmania major.

Leishmania promastigotes have the ability to synthesize essential polyunsaturated fatty acids de novo and can grow in lipid free media. Recently, we have shown that NAD(P)H cytochrome b5 oxidoreductase (Ncb5or) enzyme in Leishmania acts as the redox partner for Δ12 fatty acid desaturase, which catalyses the conversion of oleate to linoleate. So far, the exact role of Leishmania derived linoleate synthesis is still incomplete in the literature. The viability assay by flow cytometry as well as microscopic studies suggests that linoleate is an absolute requirement for Leishmania promastigote survival in delipidated media. Western blot analysis suggested that infection with log phase linoleate deficient mutant (KO) results in increased level of NF-κBp65, IκB and IKKß phosphorylation in RAW264.7 cells. Similarly, the log phase KO infected RAW264.7 cells show dramatic increment of COX-2 expression and TNF-α secretion, compared to control or Ncb5or complement (CM) cell lines. The activation of inflammatory signaling pathways by KO mutant is significantly reduced when the RAW264.7 cells are pre-treated with BSA bound linoleate. Together, these findings confirmed that the leishmanial linoleate inhibits both COX-2 and TNF-α expression in macrophage via the inactivation of NF-κB signaling pathway. The stationary phase of KO promastigotes shows avirulence after infection in macrophages as well as inoculation into BALB/c mice; whereas CM cell lines show virulence. Collectively, these data provide strong evidence that de novo linoleate synthesis in Leishmania is an essential for parasite survival at extracellular promastigote stage as well as intracellular amastigote stage.

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.

Melon13-lipoxygenase CmLOX18 may be involved in C6 volatiles biosynthesis in fruit.

To better understand the function role of the melon CmLOX18 gene in the biosynthesis of C6 volatiles during fruit ripening, we biochemically characterized CmLOX18 and identified its subcellular localization in transgenic tomato plants. Heterologous expression in yeast cells showed that the molecular weight of the CmLOX18 protein was identical to that predicted, and that this enzyme possesseed lipoxygenase activity. Linoleic acid was demonstrated to be the preferred substrate for the purified recombinant CmLOX18 protein, which exhibited optimal catalytic activity at pH 4.5 and 30 °C. Chromatogram analysis of the reaction product indicated that the CmLOX18 protein exhibited positional specificity, as evidenced by its release of only a C-13 oxidized product. Subcellular localization analysis by transient expression in Arabidopsis protoplasts showed that CmLOX18 was localized to non-chloroplast organelles. When the CmLOX18 gene was transgenically expressed in tomato via Agrobacterium tumefaciens-mediated transformation, it was shown to enhance expression levels of the tomato hydroperoxide lyase gene LeHPL, whereas the expression levels of six TomLox genes were little changed. Furthermore, transgenic tomato fruits exhibited increases in the content of the C6 volatiles, namely hexanal, (Z)-3-hexanal, and (Z)-3-hexen-1-ol, indicating that CmLOX18 probably plays an important role in the synthesis of C6 compounds in fruits.

Selection in Europeans on Fatty Acid Desaturases Associated with Dietary Changes.

FADS genes encode fatty acid desaturases that are important for the conversion of short chain polyunsaturated fatty acids (PUFAs) to long chain fatty acids. Prior studies indicate that the FADS genes have been subjected to strong positive selection in Africa, South Asia, Greenland, and Europe. By comparing FADS sequencing data from present-day and Bronze Age (5-3k years ago) Europeans, we identify possible targets of selection in the European population, which suggest that selection has targeted different alleles in the FADS genes in Europe than it has in South Asia or Greenland. The alleles showing the strongest changes in allele frequency since the Bronze Age show associations with expression changes and multiple lipid-related phenotypes. Furthermore, the selected alleles are associated with a decrease in linoleic acid and an increase in arachidonic and eicosapentaenoic acids among Europeans; this is an opposite effect of that observed for selected alleles in Inuit from Greenland. We show that multiple SNPs in the region affect expression levels and PUFA synthesis. Additionally, we find evidence for a gene-environment interaction influencing low-density lipoprotein (LDL) levels between alleles affecting PUFA synthesis and PUFA dietary intake: carriers of the derived allele display lower LDL cholesterol levels with a higher intake of PUFAs. We hypothesize that the selective patterns observed in Europeans were driven by a change in dietary composition of fatty acids following the transition to agriculture, resulting in a lower intake of arachidonic acid and eicosapentaenoic acid, but a higher intake of linoleic acid and α-linolenic acid.

Deregulation of PPARß/δ target genes in tumor-associated macrophages by fatty acid ligands in the ovarian cancer microenvironment.

The nuclear receptor peroxisome proliferator-activated receptor ß/δ (PPARß/δ) is a lipid ligand-inducible transcription factor associated with macrophage polarization. However, its function in tumor-associated macrophages (TAMs) has not been investigated to date. Here, we report the PPARß/δ-regulated transcriptome and cistrome for TAMs from ovarian carcinoma patients. Comparison with monocyte-derived macrophages shows that the vast majority of direct PPARß/δ target genes are upregulated in TAMs and largely refractory to synthetic agonists, but repressible by inverse agonists. Besides genes with metabolic functions, these include cell type-selective genes associated with immune regulation and tumor progression, e.g., LRP5, CD300A, MAP3K8 and ANGPTL4. This deregulation is not due to increased expression of PPARß/δ or its enhanced recruitment to target genes. Instead, lipidomic analysis of malignancy-associated ascites revealed high concentrations of polyunsaturated fatty acids, in particular linoleic acid, acting as potent PPARß/δ agonists in macrophages. These fatty acid ligands accumulate in lipid droplets in TAMs, thereby providing a reservoir of PPARß/δ ligands. These observations suggest that the deregulation of PPARß/δ target genes by ligands of the tumor microenvironment contributes to the pro-tumorigenic polarization of ovarian carcinoma TAMs. This conclusion is supported by the association of high ANGPTL4 expression with a shorter relapse-free survival in serous ovarian carcinoma.

XsFAD2 gene encodes the enzyme responsible for the high linoleic acid content in oil accumulated in Xanthoceras sorbifolia seeds.

BACKGROUND: Xanthoceras sorbifolia Bunge is a valuable oilseed tree that has linoleic acid-rich seed oil. Microsomal oleate desaturase (FAD2; EC 1.3.1.35) is responsible for the conversion of oleic acid to linoleic acid during fatty acid synthesis. In this study, XsFAD2 was cloned from developing embryos of X. sorbifolia. RESULTS: XsFAD2 contained three histidine boxes, a C-terminal endoplasmic reticulum retrieval motif, and five putative transmembrane domains representing the characteristics of membrane-bound fatty acid desaturase. XsFAD2 expression in yeast cells resulted in linoleic acid (18:2) and palmitolinoleic acid (16:2) production, confirming the biological activity of the enzyme encoded by XsFAD2. These fatty acids are not normally present in wild-type yeast. Phylogenetic analysis indicated that XsFAD2 is located in a subgroup of FAD2 enzymes specifically or highly expressed in developing seeds. The expression level of XsFAD2 in seeds was much higher than those in leaves and petals. Furthermore, XsFAD2 expression pattern correlated well with linoleic acid accumulated in seeds. CONCLUSION: Results suggested that XsFAD2 is responsible for the high linoleic acid content in X. sorbifolia seed oil. This study provides insight on the regulation mechanism of fatty acid synthesis in X. sorbifolia seeds and a valuable gene for improving the oil quality in oilseed trees.

Phenotypic characterisation of colour stability of lamb meat.

A study was undertaken, using 2701 overwrapped loin samples aged for 5 days and subjected to a simulated retail display (SRD) for 3 days; sourced from lambs in the Cooperative Research Centre for Sheep Industry Innovation information nucleus flock, born 2007-2009. The ratio of reflectance of light in the wavelengths of 630 nm and 580 nm (oxy/met) was measured daily during the SRD, using a Hunterlab spectrophotometer. A series of linear mixed models was fitted to the oxy/met and time data to compare 4 breed types and identify relevant covariates, of 19, using a forward selection process. Breed type, pH at 24 h post slaughter and Linoleic acid concentration (LA) were the most important factors and covariates, in that order. Merino breed type, high pH and high LA reduced colour stability. Fitting a spline model to predict the time for oxy/met to reach a set value, represents an alternative to comparing oxy/met at a set time, for describing colour stability.