Fatty Acid Chain Length Research Articles

Characterization of Long-Chain Fatty Acid as N-(4-Aminomethylphenyl) Pyridinium Derivative by MALDI LIFT-TOF/TOF Mass Spectrometry.

Charge remote fragmentation (CRF) elimination of CnH2n+2 residues along the aliphatic tail of long chain fatty acid is hall mark of keV high-energy CID fragmentation process. It is an important fragmentation pathway leading to structural characterization of biomolecules by CID tandem mass spectrometry. In this report, we describe MALDI LIFT TOF-TOF mass spectrometric approach to study a wide variety of fatty acids (FAs), which were derivatized to N-(4-aminomethylphenyl) pyridinium (AMPP) derivative, and desorbed as M+ ions by laser with or without matrix. The high-energy MALDI LIFT TOF-TOF mass spectra of FA-AMPP contain fragment ions mainly deriving from CRF cleavages of CnH2n+2 residues, as expected. These ions together with ions from specific cleavages of the bond(s) involving the functional group within the molecule provide more complete structural identification than those produced by low-energy CID/HCD using a linear ion-trap instrument. However, this LIFT TOF-TOF mass spectrometric approach inherits low sensitivity, a typical feature of high-energy CID tandem mass spectrometry. Because of the lack of unit mass precursor ion selection with sufficient sensitivity of the current LIFT TOF-TOF technology, product ion spectra from same chain length fatty acids with difference in one or two double bonds in a mixture are not distinguishable. Graphical Abstract ᅟ.

Carbon flux to growth or polyhydroxyalkanoate synthesis under microaerophilic conditions is affected by fatty acid chain-length in Pseudomonas putida LS46.

Economical production of medium-chain length polyhydroxyalkanoates (mcl-PHA) is dependent on efficient cultivation processes. This work describes growth and mcl-PHA synthesis characteristics of Pseudomonas putida LS46 when grown on medium-chain length fatty acids (octanoic acid) and lower-cost long-chain fatty acids (LCFAs, derived from hydrolyzed canola oil) in microaerophilic environments. Growth on octanoic acid ceased when the oxygen uptake rate was limited by the oxygen transfer rate, and mcl-PHA accumulated to 61.9% of the cell dry mass. From LCFAs, production of non-PHA cell mass continued at a rate of 0.36gL-1h-1 under oxygen-limited conditions, while mcl-PHA accumulated simultaneously to 31% of the cell dry mass. The titer of non-PHA cell mass from LCFAs at 14h post-inoculation was double that obtained from octanoic acid in bioreactors operated with identical feeding and aeration conditions. While the productivity for octanoic acid was higher by 14h, prolonged cultivation on LCFAs achieved similar productivity but with twice the PHA titer. Simultaneous co-feeding of each substrate demonstrated the continued cell growth under microaerophilic conditions characteristic of LCFAs, and the resulting polymer was dominant in C8 monomers. Furthermore, co-feeding resulted in improved PHA titer and volumetric productivity compared to either substrate individually. These results suggest that LCFAs improve growth of P. putida in oxygen-limited environments and could reduce production costs since more non-PHA cell mass, the cellular factories required to produce mcl-PHA and the most oxygen-intensive cellular process, can be produced for a given oxygen transfer rate.

Preparation and characterization of lotus seed starch-fatty acid complexes formed by microfluidization

Using dynamic high pressure microfluidization, we prepared starch-lipid complexes from lotus seed starch (LS) and six saturated fatty acids (FAs) of different carbon chain length and analyzed their semi-crystalline structure and digestibility. Iodine blue value analysis showed the highest complex index (86.3%) was observed between LS and octanoic acid (C8). X-ray diffraction analysis showed crystal structure changed from V6II to V6I type with decreasing FA chain length. Small angle x-ray scattering and differential scanning calorimetry analyses confirmed the presence of a strong V6I-type mass fractal structure with a Bragg distance of 12.3 nm in LS-C8, which can be considered to be a type-II complex with high melting temperature (Tp = 123.98 °C). Scanning electron microscopy results showed the complexes had more spherocrystals with decreasing FA chain length. Compared to other FAs, C8 significantly reduced the LS susceptibility to digestive enzymes, increased slowly digestion starch content (26.06%) and decreased digestion rate (3.59 × 10−2).

Pharmacologic activation of peroxisome proliferator-activating receptor-α accelerates hepatic fatty acid oxidation in neonatal pigs

Up-regulation of peroxisome proliferator-activating receptor-α (PPARα) and increasing fatty acid oxidation are important for reducing pre-weaning mortality of pigs. We examined the time-dependent regulatory effects of PPARα activation via oral postnatal clofibrate administration (75 mg/(kg-BW·d) for up to 7 days) on mitochondrial and peroxisomal fatty acid oxidation in pigs, a species with limited hepatic fatty acid oxidative capacity due to low ketogenesis. Hepatic oxidation was increased by 44-147% (depending on fatty acid chain-length) and was attained after only 4 days of clofibrate treatment. Acyl-CoA oxidase (ACO) and carnitine palmitoyltransferase I (CPTI) activities accelerated in parallel. The increase in CPTI activity was accompanied by a rapid reduction in the sensitivity of CPTI to malonyl-CoA inhibition. The mRNA abundance of CPTI and ACO, as well as peroxisomal keto-acyl-CoA thiolase (KetoACoA) and mitochondrial malonyl-CoA decarboxylase (MCD), also were augmented greatly. However, the increase in ACO activity and MCD expression were different from CPTI, and significant interactions were observed between postnatal age and clofibrate administration. Furthermore, the expression of acetyl-CoA carboxylase β (ACCβ) decreased with postnatal age and clofibrate had no effect on its expression. Collectively these results demonstrate that the expression of PPARα target genes and the increase in fatty acid oxidation induced by clofibrate are time- and age-dependent in the liver of neonatal pigs. Although the induction patterns of CPTI, MCD, ACO, KetoACoA, and ACCβ are different during the early postnatal period, 4 days of exposure to clofibrate were sufficient to robustly accelerate fatty acid oxidation.

Very-long-chain fatty acid diversity in nine Heliophila seed oils

Heliophila is a genus of approximately 90 recognized plant species endemic to southern Africa and considered the most morphologically diverse genus in the family Brassicaceae. To begin to characterize chemical diversity in the genus, seed oil content and fatty acid composition were determined for 9 species, with representatives from the three major recognized clades. All species produced very-long-chain fatty acids (VLCFAs) as major components of the seed triacylglycerol (TAG) oil, with considerable diversity of fatty acid chain length. The 22-carbon (C22) monounsaturated fatty acid erucic acid (cis-13-docosenoic acid) was the dominant VLCFA in the oil of Heliophila coronopifolia at 47.6% of total seed fatty acids whereas the unusual C26 fatty acid ximenic acid (cis-17-hexacosenoic acid) dominated the VLCFA profile of oil from Heliophila scoparia at 35.8%. Heliophila africana oil was identified as a potential novel source of the nutraceutical fatty acid, nervonic acid (cis-15-tetracosenoic acid). Analysis of the oil of 3 species by sn-1,3 regioselective lipase digestion demonstrated the virtual exclusion of VLCFAs from the sn-2 position of TAG. Examination of the oil from H. scoparia by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry revealed the presence of high molecular weight TAGs and widespread distribution of VLCFAs among the TAG molecular species. Heliophila species have significant potential as sources of novel seed oil enriched in VLCFAs and as model species to study the mechanisms and evolution of VLCFA biosynthesis in plants.

Matching Protein Interfaces for Improved Medium-Chain Fatty Acid Production.

Medium-chain fatty acids (MCFAs) are key intermediates in the synthesis of medium-chain chemicals including α-olefins and dicarboxylic acids. In bacteria, microbial production of MCFAs is limited by the activity and product profile of fatty acyl-ACP thioesterases. Here, we engineer a heterologous bacterial medium-chain fatty acyl-ACP thioesterase for improved MCFA production in Escherichia coli. Electrostatically matching the interface between the heterologous medium-chain Acinetobacter baylyi fatty acyl-ACP thioesterase (AbTE) and the endogenous E.coli fatty acid ACP ( E.coli AcpP) by replacing small nonpolar amino acids on the AbTE surface for positively charged ones increased secreted MCFA titers more than 3-fold. Nuclear magnetic resonance titration of E.coli 15N-octanoyl-AcpP with a single AbTE point mutant and the best double mutant showed a progressive and significant increase in the number of interactions when compared to AbTE wildtype. The best AbTE mutant produced 131 mg/L of MCFAs, with MCFAs being 80% of all secreted fatty acid chain lengths after 72 h. To enable the future screening of larger numbers of AbTE variants to further improve MCFA titers, we show that a previously developed G-protein coupled receptor (GPCR)-based MCFA sensor differentially detects MCFAs secreted by E.coli expressing different AbTE variants. This work demonstrates that engineering the interface of heterologous enzymes to better couple with endogenous host proteins is a useful strategy to increase the titers of microbially produced chemicals. Further, this work shows that GPCR-based sensors are producer microbe agnostic and can detect chemicals directly in the producer microbe supernatant, setting the stage for the sensor-guided engineering of MCFA producing microbes.

High Spatial Resolution Imaging of Mouse Pancreatic Islets Using Nanospray Desorption Electrospray Ionization Mass Spectrometry.

Nanospray Desorption Electrospray Ionization mass spectrometry imaging (nano-DESI MSI) enables ambient imaging of biological samples with high sensitivity and minimal sample pretreatment. Recently, we developed an approach for constant-distance mode MSI using shear force microscopy to precisely control the distance between the sample and the nano-DESI probe. Herein, we demonstrate the power of this approach for robust imaging of pancreatic islets with high spatial resolution of ∼11 μm. Pancreatic islets are difficult to characterize using traditional mass spectrometry approaches due to their small size (∼100 μm) and molecular heterogeneity. Nano-DESI MSI was used to examine the spatial localization of several lipid classes including phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM), phosphatidylinositol (PI), and phosphatidylserine (PS) along with fatty acids and their metabolites (e.g., prostaglandins) in the individual islets and surrounding tissue. Several lipids were found to be substantially enhanced in the islets indicating these lipids may be involved in insulin secretion. Remarkably different distributions were observed for several pairs of Lyso PC (LPC) and PC species differing only by one double bond, such as LPC 18:1 vs LPC 18:0, PC 32:1 vs PC 32:0, and PC 34:2 vs PC 34:1. These findings indicate that minor variations in the fatty acid chain length and saturation have a pronounced effect on the localization of PC and LPC species in pancreatic islets. Interestingly, oxidized PC species observed experimentally were found to be specifically localized to pancreatic islets. These PCs are potential biomarkers for reactive oxygen species in the islets, which could be harmful to pancreatic beta cells. The experimental approach presented in this study will provide valuable information on the heterogeneity of individual pancreatic islets, which is difficult to assess using bulk characterization techniques.

Abstract 389: The Impact of Phospholipid Composition of Synthetic High-Density Lipoprotein on Its Pharmacological Activity

Objective: Synthetic high-density lipoprotein (sHDL) is a nanoparticle that can mimic biological activities of endogenous HDL such as reverse cholesterol transport (RCT) and anti-inflammatory properties. We hypothesize that differences in the fluidity of sHDL phospholipids at body temperature effect plasma stability of sHDL, particle ability to efflux cholesterol and inhibit inflammation. Methods: sHDL particles with different membrane fluidities were prepared complexing phospholipids with different fatty acid chain length and saturation (POPC, DMPC, DPPC, and DSPC) with the apoA-I mimetic peptide, PVLDLFRELLNELLEALKQKLK (22A). The ability of various sHDL compositions to efflux cholesterol, inhibit NF-kB activation and cytokine release, and cause lipid raft disruption was examined in RAW264.7 macrophages. Various sHDL were administered to mice challenged by injection of 0.05 mg/kg LPS at 10 mg/kg dose and the levels of cytokine release were measured at 2 hours post-dose. Various sHDL were dosed to normal rats at 50 mg/kg and cholesterol mobilization and pharmacokinetics were examined. Results: 22A-POPC and 22A-DMPC sHDL have relatively fluid phospholipid layer at body temperature compared to 22A-DPPC and 22A-DSPC sHDL due to lower phospholipid transition temperature. 22A-POPC and 22A-DMPC sHDL inhibited NF-κB activation and cytokine release in a concentration-dependent manner. From murine endotoxin infusion studies, 22A-DMPC displayed the significant inhibition of cytokine release. Cholesterol efflux studies demonstrated that 22A-POPC and 22A-DMPC displayed highest cholesterol efflux. Interestingly, in vivo RCT study showed that 22A-DSPC had longest plasma residence time and resulted in greatest cholesterol mobilization. Conclusions: Phospholipid composition of sHDL particles has a significant effect on its cholesterol efflux and anti-inflammatory properties, yet the effect appears to be different in vitro and in vivo . in vitro effect is driven by the ability of fluid phospholipid bilayer to bind LPS, cholesterol, and LCAT, while in vivo effect is defined by particle stability in plasma and residence time in the body.

503 Defining the Minimum Inhibitory Concentration of Synthetic and Commercial Medium Chain Fatty Acid Based Products Against Salmonella Typhimurium.

Research has confirmed that a 2% inclusion rate of a blend of C6:0, C8:0, and C10:0 in swine diets and ingredients can reduce Salmonella enterica serotype Typhimurium. However, it is unclear how the chain length and concentration of medium chain fatty acids (MCFA) impacts bacteriostatic properties. This can be tested through a minimum inhibitory concentration (MIC) benchtop assay, which identifies the lowest concentration of a chemical that prevents visible growth of a bacterium. The objective of this set of experiments was to utilize MIC as a mechanism to screen commercial or developmental feed additives containing MCFA for potential to mitigate Salmonella Typhimurium. First, the MIC of four synthetic MCFA treatments (C6:0, C8:0, C10:0, and 1:1:1 ratio of C:6:C8:C10 blend) was determined for Salmonella Typhimurium. The MIC of each treatment was conducted in a modified microbroth dilution and had three replicates. The MIC of C6:0 and C8:0 (0.4 and 0.5%, respectively) were similar (P > 0.05) to one another, but lower (P < 0.05) than the MIC of C10:0 or the blend of C6:C8:C10 (0.6% and >1.0%, respectively). It was therefore hypothesized that products containing high concentrations of C6:0 or C8:0 would have the greatest potential to mitigate Salmonella Typhimurium. Next, the fatty acid profile of 24 feed additive products that were commercially developed or in the development process and containing MCFA was determined via gas chromatography. As a result, four products in the development phase from varying companies plus coconut oil were selected as having a high potential for mitigating Salmonella Typhimurium based on their C6:0 and C8:0 levels. Development products 1, 2, 3, 4, and coconut oil contained 29.5, 43.1, 27.4, 0.98, and 6.82 mg/g of C6:0 and 123.20, 610.3, 248.7, 227.1, and 72.0 mg/g of C8:0, respectively. The MIC of these products vs. Salmonella Typhimurium was then determined. The MIC of Product 1 and Product 2 (0.5% and 1.3%, respectively) were similar (P > 0.05) to one another, but lower (P < 0.05) than the MIC of Products 3 or 4 (3.8% and 4.3%, respectively). All four products had a lower (P < 0.05) MIC than coconut oil (> 5.0%). In summary, current or future feed additives containing high concentrations of C6:0 and C8:0 appear to be more effective at mitigating Salmonella Typhimurium than those containing C10:0. Furthermore, it is hypothesized that free MCFA have greater antibacterial potential than those in triglyceride form.

Cellular and Molecular Responses of Dunaliella tertiolecta by Expression of a Plant Medium Chain Length Fatty Acid Specific Acyl-ACP Thioesterase.

Metabolic engineering of microalgae to accumulate high levels of medium chain length fatty acids (MCFAs) has met with limited success. Traditional approaches employ single introduction of MCFA specific acyl-ACP thioesterases (TEs), but our current research in transgenic Dunaliella tertiolecta line has highlighted that, there is no single rate-limiting approach that can effectively increase MCFA levels. Here, we explore the accumulation of MCFAs in D. tertiolecta after transgenic expression of myristic acid biased TE (C14TE). We observe that the MCFA levels were negatively correlated to the fatty acid (FA) synthesis genes, ketoacyl-ACP synthase II (KASII), stearoyl-CoA-9-desaturase (Δ9D), and oleoyl-CoA-12-desaturase (Δ12D). To further examine the molecular mechanism of MCFA accumulation in microalgae, we investigate the transcriptomic dynamics of the MCFA producing strain of D. tertiolecta. At the transcript level, enhanced MCFA accumulation primarily involved up-regulation of photosynthetic genes and down-regulation of genes from central carbon metabolic processes, resulting in an overall decrease in carbon precursors for FA synthesis. We additionally observe that MCFA specific peroxisomal β-oxidation gene (ACX3) was greatly enhanced to prevent excessive build-up of unusual MCFA levels. Besides, long chain acyl-CoA synthetase gene (LACS) was down-regulated, likely in attempt to control fatty acyl supply flux to FA synthesis cycle. This article provides a spatial regulation model of unusual FA accumulation in microalgae and a platform for additional metabolic engineering targeting pathways from FA synthesis, FA transport, and peroxisomal β-oxidation to achieve microalgae oils with higher levels of MCFAs.

Aggregation behavior and adsorption properties of salt-free catanionic surfactant mixtures containing tetradecyltrimethyl ammonium salts

ABSTRACTThe aggregation behavior of salt-free catanionic surfactants, tetradecyltrimethyl ammonium hydroxide (TTAOH)/fatty acid (FA) including octanoic acid (OA), decylic acid (DA) and lauric acid (LA) in aqueous solutions were studied. The critical micelle concentration(cmc), surface tension at cmc (γcmc), surface excess (Гmax), mean molecular surface area (Amin), adsorption efficiency (pc20) and surface tension reduction effectiveness (πcmc) were obtained from surface tension isotherms. The influence of temperature on the surface tension of salt-free TTAOH/FA (TTAOF) systems was investigated. Data of adsorption dynamics indicated that at fixed adsorption time, the order of adsorption capacity was TTAOH < TTAOH/OA (TTAOO) < TTAOH/DA (TTAOD) < TTAOH/LA (TTAOL). The adsorption process of salt-free TTAOF was adsorption-controlled. The complex and storage moduli increased with increasing oscillation frequency, however, the loss modulus showed the opposite trend. The complex modulus passed through a maximum value with increasing concentration of salt-free surfactant TTAOF. The adsorbed TTAOF layer was elastic, and the elasticity increased with increasing hydrocarbon chain length of FA.

Fatty acid based phosphite ionic liquids as multifunctional lubricant additives in mineral oil and refined vegetable oil

Abstract Ionic liquids (ILs) are highly attractive lubricant additives for their nonflammability, low vapor pressures, structural diversity and reasonable tribological properties. A convenient synthesis route to oil-dispersible ILs has been presented in this paper. Phosphite binds to aliphatic acid as anion and triethylbenzylammonium serve as a cation, which could be applied as lubricant additives in mineral oil (5CST) and refined vegetable oil (RSO). Results demonstrated that these ILs could effectively enhance the antiwear, friction-reducing and extreme pressure properties of 5CST and RSO. The chain length and unsaturation of fatty acid is significant in improving the tribological properties of base oil. TEY and FY mode K-edge XANES analysis of the formed tribofilms showed that the improvement of anti-wear and friction-reducing properties was closely related to the content of phosphate species on the near surface.

Kerosene-Like Fuel Production from Coconut Oil and Cashew-Nut Oil - Effects of Fatty Acid Degree of Saturation and Chain Length

This research tested the hypothesis of whether fatty acid saturation and chain length of feedstock oil has any effect on the physico-chemical properties of synthesized kerosene-like fuel. Biodiesel was obtained from the feedstocks via transesterification and were subjected to distillation under vacuum between 50 to 100 o C to obtain kerosene-like fuel as the final product. The heat value, flash points, kinematic viscosity and specific gravity values were obtained and found to be within the stipulated range of fossil kerosene. The products were analysed using infrared spectrometer to confirm the presence of the functional groups in the kerosene-like fuel produced. Furthermore, Analysis by the elemental analyser showed that the kerosene-like fuel obtained from coconut oil has a significantly higher heat content value (9211.9 Kcal.Kg -1 ) than that from cashew-nut oil (5699.4 Kcal.Kg -1 ). This distinction in heat value can be ascribed to the nature of fatty acid in the oils as coconut oil is significantly more saturated and has shorter fatty acid hydrocarbon chain length than cashew-nut oil.

Structure-Activity Relationship in Monosaccharide-Based Toll-Like Receptor 4 (TLR4) Antagonists.

The structure-activity relationship was investigated in a series of synthetic TLR4 antagonists formed by a glucosamine core linked to two phosphate esters and two linear carbon chains. Molecular modeling showed that the compounds with 10, 12, and 14 carbons chains are associated with higher stabilization of the MD-2/TLR4 antagonist conformation than in the case of the C16 variant. Binding experiments with human MD-2 showed that the C12 and C14 variants have higher affinity than C10, while the C16 variant did not interact with the protein. The molecules, with the exception of the C16 variant, inhibited the LPS-stimulated TLR4 signal in human and murine cells, and the antagonist potency mirrored the MD-2 affinity calculated from in vitro binding experiments. Fourier-transform infrared, nuclear magnetic resonance, and small angle X-ray scattering measurements suggested that the aggregation state in aqueous solution depends on fatty acid chain lengths and that this property can influence TLR4 activity in this series of compounds.

Metabolomic profiling suggests long chain ceramides and sphingomyelins as a possible diagnostic biomarker of epithelial ovarian cancer

IntroductionEpithelial ovarian cancer (EOC) is a disease with a poor survival rate mostly due to its discovery in late stages. The aim of this study was to investigate the metabolomic profile of ovarian cancer with the intention of identifying and describing novel biomarkers with diagnostic potential. Material and methodsTargeted serum metabolomic profiling was performed on 15 patients with ovarian cancer, 21 healthy controls and 21 patients with benign ovarian conditions, using HPLC–TQ/MS. ResultsPanel of 49 top performing biomarkers shows separation between EOC and controls with 87% specificity and 87% sensitivity with AUC of 93% (CI 90%–95%). Using only 5 top biomarkers, specificity of 80% and sensitivity of 83% was achieved on extended sample set. Most significant biomarkers belong to sphingolipid classes, especially long chain ceramides and sphingomyelins. Different concentrations of various fatty acid chain lengths ceramides and sphingomyelins are also implying their respective roles in cell proliferation and growth inhibition. ConclusionLong chain ceramides and sphingomyelins may serve as a novel biomarker for epithelial ovarian cancer detection and may also offer insight into the role of sphingolipid metabolism in cell proliferation.

Improving Vegetable Oil Properties by Transforming Fatty Acid Chain Length in Jatropha Oil and Coconut Oil Blends

Efforts to improve the physical and chemical properties of vegetable oils as diesel fuels such as viscosity and calorific value are indispensable with the depletion of fossil oil reserves. Jatropha oil with long chain fatty acids and high degree of unsaturation is mixed with short chain saturated fatty acid coconut oil in various compositions. The mixture was heated and stirred for 30 min at 90 °C. This mixing leads to a decrease in viscosity which allows for the breaking of the bond. The fatty acid molecule structure undergoes transformation that changes the degree of unsaturation and the average length of the carbon chain. Consequently, the kinematic viscosity and flash point of the mixture decreases while its calorific value increases.

Metabolic Engineering for Enhanced Medium Chain Omega Hydroxy Fatty Acid Production in Escherichia coli.

Medium chain hydroxy fatty acids (HFAs) at ω-1, 2, or 3 positions (ω-1/2/3) are rare in nature but are attractive due to their potential applications in industry. They can be metabolically engineered in Escherichia coli, however, the current yield is low. In this study, metabolic engineering with P450BM3 monooxygenase was applied to regulate both the chain length and sub-terminal position of HFA products in E. coli, leading to increased yield. Five acyl-acyl carrier protein thioesterases from plants and bacteria were first evaluated for regulating the chain length of fatty acids. Co-expression of the selected thioesterase gene CcFatB1 with a fatty acid metabolism regulator fadR and monooxygenase P450BM3 boosted the production of HFAs especially ω-3-OH-C14:1, in both the wild type and fadD deficient strain. Supplementing renewable glycerol to reduce the usage of glucose as a carbon source further increased the HFAs production to 144 mg/L, representing the highest titer of such HFAs obtained in E. coli under the comparable conditions. This study illustrated an improved metabolic strategy for medium chain ω-1/2/3 HFAs production in E. coli. In addition, the produced HFAs were mostly secreted into culture media, which eased its recovery.

No effect of saturated fatty acid chain length on meal-induced thermogenesis in overweight men

Monounsaturated (MUFA) fatty acids have been shown to induce greater meal-induced thermogenesis (MIT) than saturated fatty acids (SFA) in some studies, however, the effect of SFA chain length has not been examined. We hypothesized that a meal rich in short- to medium-chain SFA would elicit a greater MIT than one rich in long-chain SFA, and that MIT responses would be comparable between the short- to medium-chain SFA and the MUFA rich meal. A 3-arm crossover study was conducted with healthy overweight men, aged 18 to 40 years. Participants consumed either an iso-energetic (3780 ± 4.3 kJ), high fat (45%) meal rich in short-/medium-chain SFA (SMCSFA) (2-12 carbons); long-chain SFA (LCSFA) (14-24 carbons), and MUFA. MIT, fat oxidation, triglyceride and subjective appetite were measured for 6 hours post-prandial. Data were analyzed as total area under the curve and compared using a one-way repeated-measures ANOVA. The mean BMI of participants (n =13) was 29.3 ± 0.6 kg/m2 and mean age 23.8±1.4 years. MIT was not different between the meals: MUFA (204.2 ± 20.5 kJ/6 h), SMCSFA (192.6 ± 21.8 kJ/6 h), LCSFA (198.1 ± 21.5 kJ/6 h) (P = .888). Fat oxidation, plasma triglyceride, and hunger and fullness were similar after each meal (P > .05 all values). This study demonstrated that in healthy overweight men, SFA chain length, and fatty acid saturation have no acute differential effect on MIT, fat oxidation, triglyceride, or subjective appetite responses.

Composition-Dependent Alterations in Thickness and Physical Properties of Lipid Bilayer FILM Revealed by Frequency Modulation Atomic Force Microscopy

Assembly of microdomains and membrane viscosity due to these physical properties of membrane have been highlighted as important factors supporting proper functions of membrane proteins. Although advanced imaging technologies including scanning probe microscopy and super-resolution optical microscopy have revealed dynamics of microdomains and visco-elastic properties of cell membranes, it is still difficult to link modifications of nanoscale membrane structure and specific diseases. In this study, we aimed to obtain high-resolution structural information of supported planner membrane with different fatty acid lengths using liquid dynamic-mode AFM and FM-AFM (Frequency Modulation Atomic Force Microscope). In FM-AFM, the cantilever is moved in a non-contact state, maintaining the cantilever frequency shift (Δf) is constant. This enables a highly sensitive force detection, 20 times better S/N than with existing methods, thereby markedly improving the image resolution. We used supported phosphatidylcholine membranes with fatty acids ranged from PC 12:0 to PC 22:6. For saturated PCs, membrane thickness increased along with the number of carbon from 4.32 nm (PC12:0) to 6.37nm (PC18:0), but diarachidoylphosphatidylcholine (PC20:0) showed reduced membrane thickness: PC20:0 thickness had 6.09 nm, that is ≈0.3 nm thinner than PC18:0. Unsaturation of fatty acid further reduced membrane thickness to 4.12 nm for PC20:4, suggesting that structural arrangement of PCs with fatty acid chain length and unsaturation level occurred. These data demonstrated that our imaging modality can detect membrane thickness with minimal membrane compression by scanning probe while maintaining high detection sensitivity. We will also present modulations of mechanical properties of membrane in the functions of carbon chain length and the level of unsaturation.

Das molekulare Lineal: Wie entstehen Fettsäuren richtiger Länge?

Fatty acids are important biopolymers that are synthesized in a cyclic reaction. After each cycle, the synthesizing enzymes need to decide whether the growing chain is elongated in another cycle or released as mature fatty acid. Recent research has shed light onto the decision makers of fatty acid chain length and has also achieved the manipulation of chain length control for the production of the technologically interesting medium-chain-length fatty acids.