Fatty Acid Carbon Chain Research Articles

Preparation of fatty acid solutions exerts significant impact on experimental outcomes in cell culture models of lipotoxicity.

Free fatty acids are essentially involved in the pathogenesis of chronic diseases such as diabetes mellitus, non-alcoholic fatty liver disease, and cardiovascular disease. They promote mitochondrial dysfunction, oxidative stress, respiratory chain uncoupling, and endoplasmic reticulum stress and modulate stress-sensitive pathways. These detrimental biological effects summarized as lipotoxicity mainly depend on fatty acid carbon chain length, degree of unsaturation, concentration, and treatment time. Preparation of fatty acid solutions involves dissolving and complexing. Solvent toxicity and concentration, amount of bovine serum albumin (BSA), and ratio of albumin to fatty acids can vary significantly between equal concentrations, mediating considerable harmful effects and/or interference with certain assays such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Herein, we studied the impact of commonly used solvents ethanol and dimethyl sulfoxide and varying concentrations of BSA directly and in solution with oleic acid on MTT to formazan conversion, adenosine triphosphate level, and insulin content and secretion of murine β-cell line MIN6 employing different treatment duration. Our data show that experimental outcomes and assay readouts can be significantly affected by mere preparation of fatty acid solutions and should thus be carefully considered and described in detail to ensure comparability and distinct evaluation of data.

Long-Acting Tumor-Activated Prodrug of a TGFβR Inhibitor.

Inhibition of TGFβ signaling in concert with a checkpoint blockade has been shown to provide improved and durable antitumor immune response in mouse models. However, on-target adverse cardiovascular effects have limited the clinical use of TGFβ receptor (TGFβR) inhibitors in cancer therapy. To restrict the activity of TGFβR inhibitors to tumor tissues and thereby widen the therapeutic index, a series of tumor-activated prodrugs of a selective small molecule TGFβR1 inhibitor 1 were prepared by appending 1 to a serine protease substrate and a half-life extension fatty acid carbon chain. The prodrugs were shown to be selectively metabolized in tumor tissues relative to the heart and blood and demonstrated a prolonged favorable increase in the tumor-to-heart ratio of the active drug in tissue distribution studies. Once-weekly administration of the most tissue-selective compound 10 provided anti-tumor efficacy comparable to the parent compound and reduced systemic exposure of the active drug.

212 Fatty Acid Analysis and Composition in Meat by Mass Spectrometry

Abstract Fatty acids determine the physical and chemical properties of fats. Animal fats, regardless of species, have more saturated and monounsaturated than polyunsaturated fatty acids. The major fatty acids in meat are palmitic (16:0), stearic (18:0), palmitoleic (16:1), oleic (18:1), linoleic (18:2), and linolenic (18:3) acids, among which oleic acid is the most predominant. Arachidonic acid (20:4 cis 5,8,11,14) is an essential fatty acid only found in animal fats and can be used as a quality control indicator in the fatty acid analysis. Fatty acid analysis has been traditionally performed by gas chromatography (GC) of volatile fatty acid derivatives, prominently the methyl esters, and flame ionization detection (FID), in which the carbon chain of fatty acids is degraded to the formylium ion CHO+. The FID is very sensitive and is the most widely used detection method for GC, providing a linear response, i.e., peak area, over a wide range of concentrations. Researchers have been used the FID peak area to calculate the percentages of fatty acids. However, the FID is a “carbon counter” and relies on the “equal per carbon” rule; therefore, at the same molar concentration, fatty acids with a different number of carbons produce different peak areas. The recent development of mass spectrometry technology has improved the specificity of fatty acid detection. Specific target and qualifier ions provide better identification and more accurate quantification of fatty acid concentrations. Although fatty acids can be identified through comparing ion fragmentation with various databases, authentic standards are needed for quantification purposes. Using mass spectrometry, more than 50 fatty acids have been identified in meat samples. Some branched-chain fatty acids may have flavor, safety, and shelf life implications in meat products.

Controlling the Orientation and Viscoelasticity of Materials-Binding Peptides on Hexagonal Boron Nitride Using Fatty Acids.

The adsorption of materials-binding peptides to technologically relevant 2D nanosheets of h-BN could be transformative for both property modulation and materials applications. To enhance binding, integration of non-natural functionalities into the biomolecule could prove to be important. However, very little is understood regarding the impact of these biomolecular structural alterations on the binding, which could influence the affinity and surface-adsorbed structures. Here, the effect of fatty acid incorporation site and carbon chain length is investigated using the BP7 peptide, previously identified with affinity for h-BN. The peptide was modified at either the N- or C-terminus with a fatty acid chain length of 6-12 carbons long. The binding affinity and bio-overlayer viscoelasticity are quantified using quartz crystal microbalance analysis. While fatty acid conjugation did not substantially affect the affinity of the resultant biomolecules, it did alter the viscoelasticity of the biomolecular overlayer on the h-BN surface based upon the carbon chain length and incorporation site. Molecular dynamics simulations demonstrate interplay between enthalpic and entropic effects in modifying the overlayer viscoelasticity. The simulations predict that C-terminal conjugation promotes the enhancement of upright adsorbed states, compared with the N-terminal case, with this effect most pronounced for the 10-carbon chain.

The Divergent Immunomodulatory Effects of Short Chain Fatty Acids and Medium Chain Fatty Acids.

Fatty acids are derived from diet and fermentative processes by the intestinal flora. Two to five carbon chain fatty acids, termed short chain fatty acids (SCFA) are increasingly recognized to play a role in intestinal homeostasis. However, the characteristics of slightly longer 6 to 10 carbon, medium chain fatty acids (MCFA), derived primarily from diet, are less understood. Here, we demonstrated that SCFA and MCFA have divergent immunomodulatory propensities. SCFA down-attenuated host pro-inflammatory IL-1β, IL-6, and TNFα response predominantly through the TLR4 pathway, whereas MCFA augmented inflammation through TLR2. Butyric (C4) and decanoic (C10) acid displayed most potent modulatory effects within the SCFA and MCFA, respectively. Reduction in TRAF3, IRF3 and TRAF6 expression were observed with butyric acid. Decanoic acid induced up-regulation of GPR84 and PPARγ and altered HIF-1α/HIF-2α ratio. These variant immune characteristics of the fatty acids which differ by just several carbon atoms may be attributable to their origins, with SCFA being primarily endogenous and playing a physiological role, and MCFA exogenously from the diet.

Development of novel anti‐wetting coating on cellulosic surface using low carbon butyric acid

In this work, first time anti-wetting coating on wood surface is prepared by using titanium dioxide (TiO2) nanoparticles and low carbon chain fatty acid (butyric acid). By combining TiO2 nanoparticles and butyric acid, superhydrophobicity is achieved with water static contact angle of 168 ± 2° and tilt angle of 6 ± 1°. Coating exhibits the excellent anti-dust and anti-stain properties. Coating is found to be mechanical, thermally, UV and chemically stable after performing water jet, sand abrasion, annealing, sun light exposure and chemical stability tests. Additionally present study also shows that coated surface attains sticky superhydrophobicity at high impact velocity. We envision that the durable superhydrophobic coating of TiO2 nanoparticles and butyric acid can be effective for anti-dust and anti-stain properties of wood surface and aforesaid coating has great industrial and household applications.

Effects of abomasal infusions of fatty acids and 1-carbon donors on apparent fatty acid digestibility and incorporation into milk fat in cows

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.

Identification of tung tree FATB as a promoter of 18:3 fatty acid accumulation through hydrolyzing 18:0-ACP

Tung oil extracted from tung tree (Vernicia fordii) seeds is very industrially useful due to its drying quality given by α-eleostearic acid (ESA). Previous comparative transcriptome analysis revealed that a putative tung tree FATB gene (VfFATB) encoding fatty acyl-ACP (acyl carrier protein) thioesterase B (FATB) was significantly unregulated during oil synthesis stage. Fatty acyl-ACP thioesterases determine the length of the fatty acid carbon chains through releasing acyl chain from acyl-ACP. For a better understanding of the mechanism of α-eleostearic acid biosynthesis, it would be desirable to further characterize the function of VfFATB gene involved in fatty acid synthesis pathways in tung tree seeds. In view of this, VfFATB gene was cloned by RACE (rapid amplification of cDNA ends) method to further characterize its functions. Expression profiles of VfFATB were positively correlated with oil contents in tung tree seeds. VfFATB is localized in chloroplasts and restored the abnormal development of Arabidopsis fatb mutants. Fatty acid profiles in VfFATB-transformed E. coli (Escherichia coli) cells and Arabidopsis fatb mutant plants showed that the presence of VfFATB led to accumulation of 18:0 and 18:3 fatty acids in vivo. In vitro thioesterase assay using crude extract from seed tissue of tung tree and purified VfFATB protein further indicated that 18:0-ACP rather than 18:3-ACP was the main substrate of VfFATB. The above results strongly suggest that VfFATB, an 18:0-ACP-preferring thioesterase, is essential for plant normal development and promotes the accumulation of 18:3 fatty acid through hydrolyzing 18:0-ACP to produce free 18:0 fatty acid as the substrate of downstream related enzymes. VfFATB functions in chloroplast. VfFATB expression level is positively correlated with tung oil content. VfFATB is essential for plant normal development. VfFATB is an 18:0-ACP-preferring thioesterase.

Kinetic interactions of nanocomplexes between astaxanthin esters with different molecular structures and β-lactoglobulin

The influence of different fatty acid carbon chains on the kinetic interactions of nanocomplexes between esterified astaxanthin (E-Asta) and β-lactoglobulin (β-Lg) were investigated by multi-spectroscopy and molecular modeling techniques. We synthesized ten different E-Asta bound to β-Lg and formed nanocomplexes (< 300 nm). Fluorescence spectroscopy showed moderate affinities (binding constants Ka = 103–104 M−1). Docosahexaenoic acid astaxanthin monoester (Asta-C22:6) had the strongest binding affinity towards β-Lg (Ka = 3.77 × 104 M−1). The fluorescence quenching of β-Lg upon binding of E-Asta displayed a static mechanism, with binding sites (n) equal to 1. Fourier transform infrared spectroscopy and ultraviolet–visible absorption spectroscopy revealed that E-Asta might enter the β-Lg hydrophobic cavity, leading to unfolding of the peptide chain skeleton. In summary, β-Lg and E-Asta can form stable nanocomplex emulsions to achieve an effective delivery process for E-Asta.

Intracellular delivery, accumulation, and discrepancy in antibacterial activity of four enrofloxacin-loaded fatty acid solid lipid nanoparticles

Four fatty acid-solid lipid nanoparticles (SLNs) were formulated and evaluated for intracellular delivery, accumulation, as well as discrepancy in antimicrobial efficacy of their loaded enrofloxacin by using RAW 264.7 cells. The delivery efficacy of enrofloxacin into the macrophages by docosanoic acid SLNs (DAS), octadecanoic acid SLNs (OAS), hexadecanoic acid SLNs (HAS), and tetradecanoic acid SLNs (TAS) were 26.1–29.0, 9.3–10.3, 4.7–5.3 and 4.5–5.0 folds, respectively, compared to free drug when co-incubation for 0.25−4 h. The longer fatty acid prepared nanoparticles loaded enrofloxacin eliminated more slowly and accumulated in the cells for a longer time.The confocal microscopy also demonstrated that higher amount of fatty acid SLNs entered the cells with stronger accumulation performance and less amount SLNs absorbed on the cytomembrane as the carbon chain of fatty acids increased. The bactericidal activity of the four fatty acid SLNs against intracellular Salmonella CVCC541 significantly enhanced compared to the free enrofloxacin. These results revealed that fatty acid SLNs, especially docosanoic acid nanoparticles, might be effective nanocarriers to ferry enrofloxacin or other lipid soluble drugs into cells for intracellular bacterial infection treatment.

Effects of buffer salts on the freeze-drying survival rate of Lactobacillus plantarum LIP-1 based on transcriptome and proteome analyses

Buffer salts are often added to culture medium to promote bacterial growth. However, we found that buffer salts can improve the freeze-drying survival rate. In this experiment, the mechanisms for the effects of different buffer salts on the survival rate of freeze-dried strains were examined. The results showed that buffer salts had important effects on the freeze-drying survival rate of L. plantarum LIP-1 that were related to changes in fatty acid composition. Different buffer salts affected the expression of fatty acid metabolic genes. A new gene cluster that regulates fatty acid metabolism and synthesis was discovered. Potassium ions in buffer salts upregulated the trkA gene and lysR-type transcription factor, and then upregulated the expression of fatty acid synthesis-related acc and fab family genes. These genes help to extend the fatty acid carbon chain and promote the unsaturated fatty acids content, which improves cell membrane fluidity and improves resistance to freeze-drying.

Effect of fatty acid addition on properties of amylose nanoparticles prepared via complexing and precipitation

Amylose nanoparticles were prepared by complexing with fatty acids (palmitic acid, lauric acid and n-caproic acid) and then ethanol precipitation. The effects of the fatty acid addition and fatty acid carbon chain length on the size, crystallinity, morphology and fatty acid content of the complex nanoparticles were studied. Analyses of FT-IR, complexing index and 13C CP/MAS NMR suggested that amylose complexed with the fatty acids. The determined complexing indexes were 7.8 %, 36.2 % and 44.5 % for the n-caproic acid, lauric acid, and palmitic acid at the 10 % addition. The complexing index increased from 37.1%–44.7% for the palmitic acid when the addition was increased from 5 % to 20 %. XRD results showed that the complex nanoparticles possessed V-type crystalline structure, but the crystallinity decreased from 54.22%–36.38 % when the palmitic acid addition changed from 0 to 20 %. At the 10 % addition, the crystallinity decreased from 51.07%–42.15 % as fatty acid chain length increased from 6 carbon atoms to 16 carbon atoms. The result of 13C CP/MAS NMR analysis indicated that the fatty acid content in the complex nanoparticles increased with increasing of fatty acid chain length at 10 % addition. The findings of this study provide a guideline to prepare nanoparticles of amylose-fatty acid complexes with desired properties.

Development Of Novel Liposome-Encapsulated Combretastatin A4 Acylated Derivatives: Prodrug Approach For Improving Antitumor Efficacy.

PurposeThe objective of the present study was to develop a liposomal drug delivery system based on combretastatin A4 (CA4) prodrugs modified with varying alkyl chains and investigate the in vitro drug conversion from prodrug and in vivo antitumor effect.MethodsThe prodrug of CA4 was synthesized with stearyl chloride (18-carbon chain), palmitoyl chloride (16-carbon chain), myristoyl chloride (14-carbon chain), decanoyl chloride (10-carbon chain), and hexanoyl chloride (6-carbon chain) at the 3′-position of the CA4. Subsequently, it was encapsulated with liposomes through the thin-film evaporation method. Furthermore, the characteristics of prodrug-liposome were evaluated using in vitro drug release, conversion, and cytotoxicity assays, as well as in vivo pharmacokinetic, antitumor, and biodistribution studies.ResultsThe liposome system with loaded CA4 derivatives was successfully developed with nano-size and electronegative particles. The rate of in vitro drug release and conversion was reduced as the fatty acid carbon chain lengthened. On the contrary, in vivo antitumor effects were improved with the enlargement of the fatty acid carbon chain. The results of the in vivo pharmacokinetic and tissue distribution studies indicated that the reduced rate of CA4 release with a long carbon chain could prolong the circulation time and increase the drug concentration in the tumor tissue.ConclusionThese results suggested that the release or hydrolysis of the parent drug from the prodrug was closely related with the in vitro and in vivo properties. The slow drug release of CA4 modified with longer acyl chain could prolong the circulation time and increase the concentration of the drug in the tumor tissue. These effects play a critical role in increasing the antitumor efficacy.

Comparative studies on the structural composition, surface/interface activity and application potential of rhamnolipids produced by Pseudomonas aeruginosa using hydrophobic or hydrophilic substrates

Pseudomonas aeruginosa SG produced 7.06 g/L and 10.32 g/L of rhamnolipids using glucose or soybean oil. Rhamnolipids produced from glucose contained 8 mono-rhamnolipids homologues and 6 di-rhamnolipids homologues with ratio of 61.46%:38.54%. Rhamnolipids produced from soybean oil contained 9 mono-rhamnolipids and 8 di-rhamnolipids homologues with ratio of 58.68%:41.32%. The main homologues produced from soybean oil possessed longer carbon chain of fatty acid. Rhamnolipids produced from glucose decreased surface tension to 26.3 mN/m with critical micelle concentration (CMC) of 50 mg/L; rhamnolipids produced from soybean oil reduced surface tension to 28.1 mN/m with CMC of 60 mg/L. Two rhamnolipids products were thermo-stable and halo-tolerant. Two rhamnolipids products efficiently cleaned oily sludge. Rhamnolipids produced from glucose possessed better surface activity and antimicrobial activity. Rhamnolipids produced from soybean oil exhibited greater emulsifying activity (EI24 = 76.1%) to better reduce oil viscosity. Different substrates make P. aeruginosa produce diverse rhamnolipids with distinct application potential.

A sensitive and efficient method for simultaneous profiling of bile acids and fatty acids by UPLC-MS/MS

The carboxyl group is the functional group in both bile acids (BAs) and fatty acids (FAs) (BAFAs). Considering the functional correlation and the structural similarity of these compounds, a sensitive and efficient method was developed here for the first time to simultaneously profile BAFAs based on ultrahigh performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Through optimization of the chromatographic conditions, all BAFAs can be efficiently separated and quantified in 19 min with excellent peak shape. For comprehensive profiling of endogenous FAs without standards, a strategy was established to predict the retention times (RTs) of all theoretically possible FAs on the basis of the good multiple linear regression relationship between RT and FA carbon chain length and double bond number. High-resolution mass spectrometry was employed for the final confirmation of these predicted FAs. Twenty-eight FAs in rat serum were newly identified using this strategy. Though the regulation of collision energies (CEs) for highly abundant compounds, the problems of their poor quantification linearity and accuracy caused by MS signal saturation were solved, facilitating the simultaneous quantification of both high- and low-abundance BAFAs with good linearity and accuracy. The established UPLC-MS/MS method was further used to quantify BAFAs in rat serum and to explore the disturbance of BAFA metabolism in the Tripterygium glycoside-induced liver injury rat model. A total of 25 BAs and 55 FAs in rat serum were identified and quantified. Several BAFAs, including nordeoxycholic acid, taurodeoxycholic acid and some unsaturated FAs, were found to differ significantly in the control and model groups. These BAFAs are very promising biomarkers for the evaluation of Tripterygium glycoside-induced liver injury.

N-terminal domain replacement changes an archaeal monoacylglycerol lipase into a triacylglycerol lipase

BackgroundLipolytic enzymes of hyperthermophilic archaea generally prefer small carbon chain fatty acid esters (C2–C12) and are categorized as esterases. However, a few have shown activity with long-chain fatty acid esters, but none of them have been classified as a true lipase except a lipolytic enzyme AFL from Archaeglobus fulgidus. Thus, our main objective is to engineer an archaeal esterase into a true thermostable lipase for industrial applications. Lipases which hydrolyze long-chain fatty acid esters display an interfacial activation mediated by the lid domain which lies over active site and switches to open conformation at the oil–water interface. Lid domains modulate enzyme activities, substrate specificities, and stabilities which have been shown by protein engineering and mutational analyses. Here, we report engineering of an uncharacterized monoacylglycerol lipase (TON-LPL) from an archaeon Thermococcus onnurineus (strain NA1) into a triacylglycerol lipase (rc-TGL) by replacing its 61 N-terminus amino acid residues with 118 residues carrying lid domain of a thermophilic fungal lipase—Thermomyces lanuginosus (TLIP).ResultsTON-LPL and rc-TGL were cloned and overexpressed in E. coli, and the proteins were purified by Ni–NTA affinity chromatography for biochemical studies. Both enzymes were capable of hydrolyzing various monoglycerides and shared the same optimum pH of 7.0. However, rc-TGL showed a significant decrease of 10 °C in its optimum temperature (Topt). The far UV–CD spectrums were consistent with a well-folded α/β-hydrolase fold for both proteins, but gel filtration chromatography revealed a change in quaternary structure from trimer (TON-LPL) to monomer (rc-TGL). Seemingly, the difference in the oligomeric state of rc-TGL may be linked to a decrease in temperature optimum. Nonetheless, rc-TGL hydrolyzed triglycerides and castor oil, while TON-LPL was not active with these substrates.ConclusionsHere, we have confirmed the predicted esterase activity of TON-LPL and also performed the lid engineering on TON-LPL which effectively expanded its substrate specificity from monoglycerides to triglycerides. This approach provides a way to engineer other hyperthermophilic esterases into industrially suitable lipases by employing N-terminal domain replacement. The immobilized preparation of rc-TGL has shown significant activity with castor oil and has a potential application in castor oil biorefinery to obtain value-added chemicals.

Analysis of the peanut transgenic offspring with depressing AhFAD2 gene

The delta-12 fatty acid desaturase (Δ¹² FAD or FAD2) is a key enzyme that catalyzes oleic acid to linoleic acid by dehydrogenation at Δ¹² position of fatty acid carbon chain. In peanut, reduction or loss of FAD2 activity could enhance the relative content of oleic acid in kernels, and improve the quality and oxidation stability of peanut kernels and products. RNA interference (RNAi) technology could lead to non-expression or down-regulated expression of AhFAD2 gene. We constructed two RNA interference expression vectors with the inverted repeat sequence of partial AhFAD2 gene, which were driven separately by cauliflower mosaic virus (CaMV) 35S promoter or soybean agglutinin lectin seed-specific promoter. Homozygous transgenic lines carrying the two constructs stably in genetics were developed by peanut genetic transformation. There were no significant differences between the transgenic lines and the control through investigating the main agronomic traits. We analyzed the transcriptional level expression of AhFAD2 gene in transgenic lines and the control by real-time fluorescence quantitative PCR (qRT-PCR). The results suggested that the target genes of transgenic lines were likely suppressed by RNA interference, but showed different transcriptional levels in different peanut transgenic lines. Compared with untransformed lines, the resulting down-regulation of AhFAD2 gene resulted in a 15.09% or 36.40% increase in oleic acid content in the seeds of transformed HY23 and FH1 lines respectively, and the content of linoleic acid decreased by 16.19% or 29.81%, correspondingly, the ratio of oleic acid and linoleic acid (O/L) improved by 38.02%, 98.10%. The oleic acid content had significant differences between the two transformation constructs, and also among different transgenic lines. Moreover, the inhibition effect of RNAi was more obvious in the transgenic lines with FH1 as the receptor, and with transformation structure driven by seed specific promoter. The suppressed expression of AhFAD2 gene enabled the development of peanut fatty acid, which indicated that RNA interference would be a reliable technique for the genetic modification of peanut seed quality and the potential for improvement of other traits as well.

Accumulation and Biotransformation of Dinophysis Toxins by the Surf Clam Mesodesma donacium.

Surf clams, Mesodesma donacium, were shown to accumulate toxins from Dinophysis acuminata blooms. Only pectenotoxin 2 (PTX2) and some of its derivatives were found, and no toxins from the okadaic acid group were detected. PTX2 seems to be transformed to PTX2 seco-acid (PTX2sa), which was found in concentrations more than ten-fold those of PTX2. The seco-acid was transformed to acyl-derivatives by esterification with different fatty acids. The estimated amount of these derivatives in the mollusks was much higher than that of PTX2. Most esters were originated by even carbon chain fatty acids, but some originated by odd carbon number were also found in noticeable concentrations. Some peaks of toxin in the bivalves did not coincide with those of Dinophysis abundance, suggesting that there were large differences in toxin content per cell among the populations that developed throughout the year. The observed depuration (from the digestive gland) was fast (more than 0.2 day−1), and was faster for PTX2 than for PTX2sa, which in turn was faster than that of esters of PTX2sa. PTX2 and PTX2sa were distributed nearly equally between the digestive gland and the remaining tissues, but less than 5% of the palmytoyl-esters were found outside the digestive gland.

Fatty acid synthesis pathway provides lipid precursors for rhamnolipid biosynthesis in Burkholderia thailandensis E264

Rhamnolipid production was monitored for a period of 216 h using different substrates in Pseudomonas aeruginosa PAO1 and Burkholderia thailandensis E264 which showed comparable crude yields attained by both after 216 h. The crude yield for P. aeruginosa, however, was significantly higher at the early stages of fermentation (72 or 144 h). Additionally, P. aeruginosa produced rhamnolipid with odd and even carbon chain lipid moieties using odd carbon chain fatty acid substrates (up to 45.97 and 67.57%, respectively). In contrast, B. thailandensis produced rhamnolipid with predominantly even carbon chain lipid moieties (up to 99.26). These results indicate the use of the fatty acid synthesis (FAS II) pathway as the main source of lipid precursors in rhamnolipid biosynthesis by B. thailandensis. Isotope tracing using 0.25% stearic acid – d35 + 1% glycerol as carbon substrate showed a single pattern of deuterium incorporation: with predominantly less than 15 deuterium atoms incorporated into a single Di-C14-C14 rhamnolipid molecule. This further indicates that the FAS II pathway is the main source of the lipid precursor in rhamnolipid biosynthesis by B. thailandensis. The pathogenicity of these strains was also assessed, and results showed that B. thailandensis is significantly less pathogenic than P. aeruginosa with an LC50 at 24 h > 2500, approximately three logs higher than P. aeruginosa using the Galleria mellonella larva model.

High-oleate yeast oil without polyunsaturated fatty acids

BackgroundOleate-enriched triacylglycerides are well-suited for lubricant applications that require high oxidative stability. Fatty acid carbon chain length and degree of desaturation are key determinants of triacylglyceride properties and the ability to manipulate fatty acid composition in living organisms is critical to developing a source of bio-based oil tailored to meet specific application requirements.ResultsWe sought to engineer the oleaginous yeast Yarrowia lipolytica for production of high-oleate triacylglyceride oil. We studied the effect of deletions and overexpressions in the fatty acid and triacylglyceride synthesis pathways to identify modifications that increase oleate levels. Oleic acid accumulation in triacylglycerides was promoted by exchanging the native ∆9 fatty acid desaturase and glycerol-3-phosphate acyltransferase with heterologous enzymes, as well as deletion of the Δ12 fatty acid desaturase and expression of a fatty acid elongase. By combining these engineering steps, we eliminated polyunsaturated fatty acids and created a Y. lipolytica strain that accumulates triglycerides with > 90% oleate content.ConclusionsHigh-oleate content and lack of polyunsaturates distinguish this triacylglyceride oil from plant and algal derived oils. Its composition renders the oil suitable for applications that require high oxidative stability and further demonstrates the potential of Y. lipolytica as a producer of tailored lipid profiles.