C18 Unsaturated Fatty Acids Research Articles

400 Effect of pH on in vitro ruminal metabolism of trans-10 18:1 and trans-11 18:1

Abstract Dietary C18 unsaturated fatty acids are extensively biohydrogenated by rumen microbiota into 18:0 and trans-18:1 isomers. Usually, the biohydrogenation (BH) pathways produce mostly 18:0 and trans-11 18:1 as the main intermediate. However, when fed low-forage diets that decrease the rumen pH, the main BH intermediate often is the trans-10 18:1 isomer. This change in BH, called the trans-10 shift, is associated with milk fat depression, but despite that, little is known about the triggers of the trans-10 shift and its ecological role in rumen microbiota. Microbiota stressed by low rumen pH may benefit from increased trans-18:1 availability favoring the production of the trans-18:1 isomer with a slower rate of BH. Thus, we hypothesize that at low rumen pH conditions, the BH of trans-10 18:1 will be slower than that of trans-11 18:1. We tested that with an in vitro experiment using batch incubation in Hungate tubes, replicated in 5 wk. In each run, 24 tubes were allocated at 6 treatments and 4 incubation times (0, 6, 24 and 48 h). The treatments resulted from the combination of 2 buffering solution pH (6.74 vs. 5.85) and 3 substrates: 1) Control (60 mg feed DM) 2) T10 (Control plus 1.2 mg of trans-10 18:1) and 3) T11 (Control plus 1.2 mg of trans-11 18:1). Volatile fatty acids (VFA) and long-chain fatty acids were analyzed by gas chromatography. Data were analyzed using the 2 × 3 factorial arrangement for each incubation time. Low pH resulted in less 30 to 37% DM disappearance than those with high pH at all incubation times (P < 0.05). The decrease in VFA with low pH was less expressive (≈17%) and only evident at 24 and 48 h incubation times. The low pH also decreased (P < 0.05) the BH of 18:1n-9 (less ≈47 to 53%), 18:2n-6 (less 30 to 34%) and 18:3n-3 (less 20 to 22%) at 24h and 48h incubation times, respectively. The disappearance of trans-11 18:1 was 14.6% at 6 h, 29.0% at 24 h and 32.8% at 48 h and was not affected by pH. The disappearance of trans-10 18:1 was dependent on pH. At 6 h and high pH the disappearance of both was similar, but at low pH the disappearance of trans-10 18:1 was much less (9.8%) than that of trans-11 18:1. However, at 48 h and low pH, the disappearance was similar between isomers and the disappearance of trans-10 18:1 was much greater (46.6%) than trans-11 18:1. In summary, the BH of trans-10 18:1 is less at low pH than at high pH, and this could in part explain its abundance in some practical ruminant feeding conditions. Acknowledgements: Fundação para a Ciência e a Tecnologia (FCT) funding through PTDC/CAL-ZOO/29654/2017(RumOmics), PTDC/CAL-ZOO/4515/2021(Gene2Rumen), UIDB/00276/2020 (CIISA), and LA/P/0059/2020 (AL4Animals) projects.

Effect of Amorphous Halomonas-PHB on Growth, Body Composition, Immune-Related Gene Expression and Vibrio anguillarum Resistance of Hybrid Grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatu ♂) Juveniles.

Poly-β-hydroxybutyrate (PHB) is a bacterial metabolite produced by bacteria such as Halomonas sp. that serves as a carbon and energy storage compound for bacteria under nutrient-limited conditions. Two experiments were conducted to investigate the effects of dietary supplementation with Halomonas-PHB on hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatu ♂). In experiment I, juvenile groupers were fed basal diets supplemented with 3% Halomonas-PHB (3% HM-PHB) containing 1.4% PHB and 3% Halomonas (3% HM) without PHB, as well as a control diet, for seven weeks. The results showed no significant difference in survival rate, weight gain, and crude fat content between the 3% HM-PHB group and the control group; however, the crude protein of the 3% HM-PHB group was significantly lower than that of the control group. Furthermore, supplementation with 3% HM-PHB increased the fatty acids content in fish muscles, including long-chain unsaturated fatty acids C18:1n9, EPA, and DHA. In experiment II, groupers were fed a basal diet supplemented with 6.5% Halomonas-PHB (6.5% HM-PHB) containing 3% PHB and 6.5% Halomonas (6.5% HM) containing no PHB, as well as a basal diet (Control). After seven weeks of rearing, the fish were challenged with Vibrio anguillarum for 48 h. Although no significant difference in survival rate and growth was observed among different groups, the dietary supplement of 6.5% Halomonas-PHB improved the survival rate of V. anguillarum challenged grouper and significantly increased the gene expressions of catalase (CAT) and superoxide dismutase (SOD) in blood, interleukin 1 (IL1) and interleukin 10 (IL10) in the liver, spleen, head kidney, and blood (p < 0.05). In conclusion, dietary supplementation of Halomonas-PHB had no significantly positive effect on fish growth performance but increased the content of fatty acids, including long-chain unsaturated fatty acids C18:1n9, EPA, and DHA in fish muscle; it also improved the V. anguillarum resistance, possibly through increasing immune-related gene expression in different tissues and organs. Our findings offer compelling evidence that Halomonas-PHB can be utilized as a feed additive in intensive grouper farming to enhance the groupers' resistance to Vibrio.

Electrophoresis analysis and specific IgE-binding capacity of C18 unsaturated fatty acid-milk protein complexes during in vitro gastrointestinal digestion

The main whey allergenic proteins in bovine milk are α-lactalbumin (BLA) and β-lactoglobulin (BLG). When people consume bovine milk, BLA and BLG bind to C18 unsaturated fatty acids (UFA) in the matrix and form fatty acid-milk protein complexes. In this study, we explored the digestive stability of fatty acid-milk protein complexes by simulating infant and adult gastrointestinal digestion conditions and assessed the effects of C18 UFA on milk protein allergenicity. Our findings revealed that the optimal pH digestion for milk proteins in infants and adults was pH 3.0 and pH 2.0, respectively. The tricine-SDS-PAGE and IgE-binding capacity results revealed that the complexes were not easily degraded during digestion resistance, and the digestion products had strong IgE-binding capacity. Therefore, C18 UFA make milk proteins resistant to digestion, thereby increasing their allergenicity.

Rhamnolipids and fengycins interact differently with biomimetic lipid membrane models of Botrytis cinerea and Sclerotinia sclerotiorum: Lipidomics profiles and biophysical studies

Rhamnolipids (RLs) and Fengycins (FGs) are biosurfactants with very promising antifungal properties proposed to reduce the use of synthetic pesticides in crops. They are amphiphilic molecules, both known to target the plasma membrane. They act differently on Botrytis cinerea and Sclerotinia sclerotiorum, two close Sclerotiniaceae phytopathogenic fungi. RLs are more efficient at permeabilizing S. sclerotiorum, and FGs are more efficient at permeabilizing B. cinerea mycelial cells. To study the link between the lipid membrane composition and the activity of RLs and FGs, we analyzed the lipid profiles of B. cinerea and S. sclerotiorum. We determined that unsaturated or saturated C18 and saturated C16 fatty acids are predominant in both fungi. We also showed that phosphatidylethanolamine (PE), phosphatidic acid (PA), and phosphatidylcholine (PC) are the main phospholipids (in this order) in both fungi, with more PA and less PC in S. sclerotiorum. The results were used to build biomimetic lipid membrane models of B. cinerea and S. sclerotiorum for all-atom molecular dynamic simulations and solid-state NMR experiments to more deeply study the interactions between RLs or FGs with different compositions of lipid bilayers. Distinctive effects are exerted by both compounds. RLs completely insert in all the studied model membranes with a fluidification effect. FGs tend to form aggregates out of the bilayer and insert individually more easily into the models representative of B. cinerea than those of S. sclerotiorum, with a higher fluidification effect. These results provide new insights into the lipid composition of closely related fungi and its impact on the mode of action of very promising membranotropic antifungal molecules for agricultural applications.

The effect of supplementation with rubber seed kernel pellet on in vitro rumen fermentation characteristics and fatty acid profiles in swamp buffalo

BackgroundRubber seed kernel is a by-product derived from rubber tree plantations. It is rich in C18 unsaturated fatty acids (UFA) and has the potential to be used as a protein source for ruminant diets. This investigation has been conducted to determine the influence of rubber seed kernel pellet (RUSKEP) supplementation on in vitro rumen fermentation characteristics and fatty acid profiles in swamp buffalo. Using a completely randomized design (CRD) and supplementation of RUSKEP at 0, 2, 4, 6, 8, and 10% dry matter (DM) of substrate.ResultsThe supplementation with RUSKEP had no effect on gas kinetics, cumulative gas production, or degradability. Ruminal pH decreased linearly (P < 0.01) and ammonia-nitrogen (NH3-N) concentration decreased quadratically (P < 0.01) by RUSKEP supplementation. The proportion of acetate (C2) decreased linearly (P < 0.01), but propionate (C3) and butyrate (C4) increased linearly (P < 0.01), resulting in a decrease in the acetate to propionate ratio (C2:C3) (P < 0.01) by RUSKEP supplementation. With an increasing level of dietary RUSKEP, there was a slight increase in UFA in the rumen by increasing the oleic acid (OA; C18:1 cis-9 + trans-9), linoleic acid (LA; C18:2 cis-9,12 + trans-9,12), and α-linolenic acid (ALA; C18:3 cis-9,12,15) concentrations (P < 0.01).ConclusionsAdding up to 10% of RUSKEP could improve in vitro rumen fermentation and C18 unsaturated fatty acids, especially ALA, in swamp buffalo.

Trans-Palmitoleic acid promotes adipose thermogenesis to reduce obesity via hypothalamic FFAR1 signaling.

Diet-induced thermogenesis (DIT) is crucial for maintaining body weight homeostasis, and the role of dietary fatty acids in modulating DIT is essential. However, the underlying mechanism of fatty acid regulated diet-induced thermogenesis remains elusive. Utilizing the diet- and genetic ablation-induced obese mice models, we found that the C16 unsaturated fatty acids, trans-palmitoleic acid (TPA) and cis-palmitoleic acid (CPA), significantly increased the energy expenditure by promoting the thermogenesis of brown adipose tissues and the production of beige cells in white adipose. As a result, there is a significant reduction in the occurrence of obesity, associated hepatic steatosis and hyperglycemia. Notably, TPA exhibited more potent effects on promoting DIT and alleviating obesity than CPA did. Using inhibitor and gene deletion mice models, we unveiled that TPA acted as a signaling molecule to play a biological function, which could be sensed by the hypothalamic FFAR1 to activate the sympathetic nervous system in promoting adipose tissue thermogenesis. Together, these results demonstrate the underlying mechanism of free fatty acids associated-DIT and will provide fresh insights into the roles of trans-fatty acids in the development of obesity.

Fads2b Plays a Dominant Role in ∆6/∆5 Desaturation Activities Compared with Fads2a in Common Carp (Cyprinus carpio).

Highly unsaturated fatty acids (HUFAs) are essential for mammalian health, development and growth. However, most mammals, including humans, are incapable of synthesizing n-6 and n-3 HUFAs. Fish can convert C18 unsaturated fatty acids into n-6 and n-3 HUFAs via fatty acid desaturase (Fads), in which Fads2 is a key enzyme in HUFA biosynthesis. The allo-tetraploid common carp theoretically encode two duplicated fads2 genes. The expression patterns and desaturase functions of these two homologous genes are still unknown. In this study, the full length of the fads2a and fads2b were identified in common carp (Cyprinus carpio). Expression analyses indicate that both genes were mainly expressed in the liver and the expression of fads2b is higher than fads2a at different developmental stages in carp embryos. Heterogenous expression and 3D docking analyses suggested that Fads2b demonstrated stronger ∆6 and ∆5 desaturase activities than Fads2a. The core promotor regions of fads2a and fads2b were characterized and found to have different potential transcriptional binding sites. These results revealed the same desaturase functions, but different activities of two homologues of fasd2 genes in common carp. The data showed that fads2b played a more important role in HUFA synthesis through both expression and functional analyses.

Biomimetic lipid-fluorescein probe for cellular bioimaging.

Fluorescence probe is one of the most powerful tools for cellular imaging. Here, three phospholipid-mimicking fluorescent probes (FP1-FP3) comprising fluorescein and two lipophilic groups of saturated and/or unsaturated C18 fatty acids were synthesized, and their optical properties were investigated. Like in biological phospholipids, the fluorescein group acts as a hydrophilic polar headgroup and the lipid groups act as hydrophobic non-polar tail groups. Laser confocal microscope images illustrated that FP3, which contains both saturated and unsaturated lipid tails, showed great uptake into the canine adipose-derived mesenchymal stem cells.

Hydrothermal catalytic conversion of oleic acid to heptadecane over Ni/ZrO2

There is growing interest in the substitution of expensive noble metal catalysts with low-cost earth-abundant metals in applications targeting biofuels production from waste organic feedstocks. Here, nickel (Ni) catalysts supported on zirconium dioxide (ZrO2), both with and without copper (Cu) as a co-metal, were tested in hydrothermal reactions of unsaturated and saturated C18 fatty acids as models for waste oil feedstocks. In contrast to recent reports, this study showed no enhancement of nickel's activity for fatty acid conversion to alkane products when Cu was present. Ni/ZrO2 prepared by metal coprecipitation methods converted 100% of oleic acid with 25% selectivity to heptadecane after 5 h of reaction at 350 °C using methanol as a hydrogen donor source, increasing to 41% heptadecane after 20 h. Lower yields were observed with catalysts prepared by wet impregnation and using alternative hydrogen donor sources (glycerol, formic acid). Greater selectivity to heptadecane was also observed at higher temperatures (370 °C) and when the initial fatty acid had greater saturation. Longer term exposure to hydrothermal media led to metal sintering and catalyst deactivation. Findings support a path forward to the development of earth-abundant metal catalysts for the upgrading of waste organic feedstocks.

Separation of unsaturated C18 fatty acids using perfluorinated-micellar electrokinetic chromatography

Separation of unsaturated C18 fatty acids using perfluorinated-micellar electrokinetic chromatography

Separation of unsaturated C18 fatty acids using perfluorinated-micellar electrokinetic chromatography: I.Optimization and separation process.

Ammonium perfluorooctanoate (APFOA) was used as a surfactant for the separation of free unsaturated C18 fatty acids by micellar electrokinetic chromatography. A simple background electrolyte of 50mM APFOA water/methanol (90:10, v/v) at pH=10 enabled the repeatable separation of oleic acid, elaidic acid, linoleic acid, and alpha-linolenic acid in less than 20min. Separation conditions were optimized regarding various parameters (organic solvent, counterion, APFOA concentration, and pH). Because the repulsive interactions between fluorocarbon chains and hydrogenated chains are known to lead to segregation and phase separation, the choice of perfluorinated micelles to separate such perhydrogenated long-chain acids could appear astonishing. Therefore, the critical micelle concentration, the charge density, and the mobility of the micelles have been determined, resulting in a first description of the separation process.

Enrichment of nervonic acid in Acer truncatum Bunge oil by combination of two-stage molecular distillation, one-stage urea complexation and five-stage solvent crystallization

Nervonic acid is the world's first and only potent substance that can repair damaged nerve fibers and promote nerve cell regeneration with high nutritional value. The wide variety of fatty acids in plant oils and fats with similar structures makes the large-scale separation and purification of high-purity nervonic acid very difficult. A new combined process of molecular distillation, urea inclusion and solvent crystallization was established to prepare high-purity nervonic acid with the mixed fatty acids obtained after saponification and acidification of Acer truncatum Bunge oil as raw materials. First, according to the difference in the mean free path of fatty acids, molecular distillation was used to separate and remove C16 saturated fatty acid of palmitic acid and four C18–C20 fatty acids of stearic, oleic, linoleic, and linolenic acids. The content of C16–C20 fatty acids decreased from 72.92% to 19.22% after two-stage molecular distillation processes, in which the contents of saturated fatty acid of palmitic acid decreased to about 0.5%. Then, according to the difference in carbon chain length and saturation of fatty acid, the contents of C22–C24 saturated fatty acids of tetracosanoic and docosanoic acids decreased to 0.21% and 0.07% by urea inclusion with urea/free fatty acid preparation by saponification (SPOMFs) ratio as 0.6. In addition, all saturated fatty acids were basically separated. Finally, according to the difference in the solubility of fatty acids in solvents, the C18–C20 unsaturated fatty acids of oleic, linoleic, and linolenic acids and C22 unsaturated fatty acid of erucic acid were removed by solvent crystallization. The content of C18–C20 unsaturated fatty acids decreased to less than 5% with pentanol as the solvent after the first stage solvent crystallization. The content of erucic acid decreased to 3.47% with anhydrous ethanol as the solvent after the second to fifth stage solvent crystallization. The combined process of molecular distillation, urea inclusion and low temperature crystallization innovatively adopted an efficient, simple and easy-to-industrial solvent crystallization method to separate erucic and nervonic acids, obtaining nervonic acid with purity of 96.53% and final yield of 47.99%.

Separation of unsaturated C18 fatty acids using perfluorinated-micellar electrokinetic chromatography: II) role of nano-structuration

• Free fatty acids are separated by capillary electrophoresis using fluorosurfactants. • Scattering experiments evidence aggregation from small micelles to large structures. • Micelle structuration in injection buffer and background electrolytes is affected by fatty acids. • Selective interactions between fatty acids and fluorosurfactant allow CE separation. Three fatty acids were separated by micellar electrokinetic chromatography (MEKC) using ammonium perfluorooctanoate as volatile surfactant. Characterizations of both injection buffer and background electrolyte have been performed by complementary techniques including scattering experiments (light, x-rays) and NMR. Different structures have been observed such as small micelles at low methanol content and larger aggregates at high methanol content. In both cases fatty acids interact specifically with the perfluorinated self-assemblies due to different geometrical constraints and different interactions between polar head groups, ensuring separation by MEKC.

Inhibition of Staphylococcus aureus Biofilm Formation and Virulence Factor Production by Petroselinic Acid and Other Unsaturated C18 Fatty Acids.

ABSTRACTStaphylococcus aureus is a major human pathogen that secretes several toxins associated with the pathogenesis of sepsis and pneumonia. Its antibiotic resistance is notorious, and its biofilms play a critical role in antibiotic tolerance. We hypothesized fatty acids might inhibit S. aureus biofilm formation and the expressions of its virulence factors. Initially, the antibiofilm activities of 27 fatty acids against a methicillin-sensitive S. aureus strain were investigated. Of the fatty acids tested, three C18 unsaturated fatty acids, that is, petroselinic, vaccenic, and oleic acids at 100 μg/mL, inhibited S. aureus biofilm formation by more than 65% without affecting its planktonic cell growth (MICs were all > 400 μg/mL). Notably, petroselinic acid significantly inhibited biofilm formation of two methicillin-resistant S. aureus strains and two methicillin-sensitive S. aureus strains. In addition, petroselinic acid significantly suppressed the production of three virulence factors, namely, staphyloxanthin, lipase, and α-hemolysin. Transcriptional analysis showed that petroselinic acid repressed the gene expressions of quorum sensing regulator agrA, effector of quorum sensing RNAIII, α-hemolysin hla, nucleases nuc1 and nuc2, and the virulence regulator saeR. Furthermore, petroselinic acid dose-dependently inhibited S. aureus biofilm formation on abiotic surfaces and porcine skin. These findings suggest that fatty acids, particularly petroselinic acid, are potentially useful for controlling biofilm formation by S. aureus.IMPORTANCE Fatty acids with a long carbon chain have recently attracted attention because of their antibiofilm activities against microbes. Here, we report the antibiofilm activities of 27 fatty acids against S. aureus. Of the fatty acids tested, three C18 unsaturated fatty acids (petroselinic, vaccenic, and oleic acids) significantly inhibited biofilm formation by S. aureus. Furthermore, petroselinic acid inhibited the production of several virulence factors in S. aureus. The study also reveals that the action mechanism of petroselinic acid involves repression of quorum-sensing-related and virulence regulator genes. These findings show that natural and nontoxic petroselinic acid has potential use as a treatment for S. aureus infections, including infections by methicillin-resistant S. aureus strains, and in food processing facilities.

Relationships Between Lipid Profiles and Use of Ethnographic Pottery: an Exploratory Study

Investigating the organic content of archaeological pottery has largely focused on identifying food commodities, but their use and mode of processing still need to be thoroughly investigated. The present study aims to explore the diversity of organic residue absorption patterns, over a wider range of functions than previously studied by experimentation, by analysing ceramics still in use today. A field survey in Bedik Country, Senegal, where the use of pottery is still alive, was conducted to document the uses of ceramics and to interview potters and users of the vessels. As a preliminary study, nine ceramics whose use was recorded were investigated through 59 samples for their absorbed molecular profiles, lipid concentrations, and the preservation of triglycerides and C18 unsaturated fatty acids. The interpretations were first carried out as a blind test and then compared with the actual use. Lipid concentrations and molecular profiles indicated a diversity of contents, and the comparison of samples taken along the vertical transects of the vessels resulted in pottery function hypotheses that were broadly aligned with the actual uses. Cooking pots for fat-rich products were successfully identified, but the various documented patterns showed that lipid accumulation in ceramics is more complex than expected. Although caution is required to adopt this approach for archaeological pots, the vessel for fermenting plant products has been identified. Last, this work pointed out that ceramics can be used for a wider range of purposes than those usually considered for archaeological pottery, such as steaming or cooking non-food products.

High-Pressure crystallization of binary unsaturated fatty acids in cylindrical cell

The separation of the binary unsaturated fatty acids C18:1 + C18:2 system was examined by high-pressure crystallization at 298 K (25 °C). The binary fatty acid mixture containing 0.8 mol fraction of C18:1 was packed in the glass cell with a free piston, and then pressurized by an aqueous ethanol solution around the glass cell up to 200 MPa. The complete solid mixture was obtained after cooling at 253 K (- 20 °C) as a depressurized binary solid. The solid was divided into four parts, and the composition of C18:1 was analyzed at each part of the solid using a refractometer, which revealed there was a composition distribution throughout the solid with C18:1 crystallized one-directionally from the top to the bottom of the cell. High-pressure crystallization could be effective for the separation of binary fatty acids.

Characterization of fatty acid desaturases reveals stress-induced synthesis of C18 unsaturated fatty acids enriched in triacylglycerol in the oleaginous alga Chromochloris zofingiensis

BackgroundThe green microalga Chromochloris zofingiensis is capable of producing high levels of triacylglycerol rich in C18 unsaturated fatty acids (UFAs). FA desaturation degree is regulated by FA desaturases (FADs). Nevertheless, it remains largely unknown regarding what FADs are involved in FA desaturations and how these FADs collaborate to contribute to the high abundance of C18 UFAs in triacylglycerol in C. zofingiensis.ResultsTo address these issues, we firstly determined the transcription start sites of 11 putative membrane-bound FAD-coding genes (CzFADs) and updated their gene models. Functional validation of these CzFADs in yeast and cyanobacterial cells revealed that seven are bona fide FAD enzymes with distinct substrates. Combining the validated functions and predicted subcellular compartments of CzFADs and the FA profiles of C. zofingiensis, the FA desaturation pathways in this alga were reconstructed. Furthermore, a multifaceted lipidomic analysis by systematically integrating thin-layer chromatography, gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry techniques was conducted, unraveling profiles of polar membrane lipids in C. zofingiensis and major desaturation steps occurring in these lipids. By correlating transcriptional patterns of CzFAD genes and changes of lipids upon abiotic stress conditions, our results highlighted collaboration of CzFADs for C18 UFA synthesis and supported that both de novo FA synthesis and membrane lipid remodeling contributed C18 UFAs to triacylglycerol for storage.ConclusionsTaken together, our study for the first time elucidated the pathways of C18 FA desaturations and comprehensive profiles of polar membrane lipids in C. zofingiensis and shed light on collaboration of CzFADs for the synthesis and enrichment of C18 UFAs in triacylglycerol.

Effect of Growth Temperature on Muscle Lipid Class and Fatty Acid Composition in Adult Steelhead Trout (Oncorhynchus mykiss) Fed Commercial Diets with Different andomega;6 to andomega;3 Fatty Acid Ratios

The effect of fluctuating temperature on muscle lipid composition was examined in 1.8 Kg steelhead trout fed 3 commercial diets with varying proportions (16.5 - 31% total) of Σω3 fatty acids and large differences (5×) in ω6:ω3 fatty acid ratios. Temperature was increased from 13.5°C to 18.0°C and then dropped back down to 13.5°C over a period of 12 weeks. Diet had no significant effect on growth or on total polyunsaturated fatty acid (PUFA) proportions in muscle tissue, but significant changes were observed in individual fatty acids. There was a greater response to changes in diet in the fatty acids than there was to changes in temperature. Muscle C20–C22 ω3PUFA and C18 unsaturated fatty acids reflected dietary inputs leading to very different (up to 40%) ω6:ω3 fatty acid ratios. Independent of diet, increasing temperature significantly increased total lipids and saturated fatty acids, especially 16:0, and decreased monounsaturated ones, especially 18:1ω9, as well as the PUFA 18:2ω6. The ω6:ω3 fatty acid ratio was also lowest at 18.0°C. Increasing total lipids, sterols and saturated fatty acids with increasing temperature, has important implications for both cultured and wild fish in terms of their nutrition, food quality for humans, and resource availability for aquafeeds.

RESEARCH OF COMPOSITION OF ANTIWEAR ADDITIVES FOR JET FUELS

In the framework of the state import substitution program for the development of a domestic antiwear additive for jet fuels the physicochemical characteristics of the approved foreign antiwear additives of DNK, HITEC 580 and Unicor J were analyzed at the first stage. The analysis revealed that using solvents during the production of HITEC 580 additives and Unicor J improve their consumer properties (low temperature characteristics). At the second stage of the study the composition of currently used additives HITEC 580 and Unicor J was studied by gas chromatography-mass spectrometry. It was shown, that the same active component is used in their composition - dimers of unsaturated fatty acids C18, namely a mixture of dimers of linolenic, linoleic and oleic acids, among which the dimer formed from linoleic and oleic acids prevails. An analysis of the solvents used in the additive composition showed that in the production of Unicor J additives they use an aromatic solvent containing 92% of monoaromatic compounds, mainly of the C10 series, which is probably the product of gasoline reforming, and HITEC 580 additives use an aliphatic solvent containing mainly n alkanes (41%). From the presented results of the study it follows that when developing a domestic antiwear additive formulation, it is necessary to choose compounds containing 1 or 2 carboxyl groups as the active component, and as the solvent either aromatic or aliphatic, depending on the cost and availability on the domestic market.

Effect of dietary lipids and other nutrients on milk odd- and branched-chain fatty acid composition in dairy ewes

Milk odd- and branched-chain fatty acids (OBCFA) are largely derived from bacteria leaving the rumen, which has encouraged research on their use as biomarkers of rumen function. Targeted research has examined relationships between these fatty acids (FA) and dietary components, but interactions between the effects of lipids and other nutrients on milk OBCFA are not well characterized yet. Furthermore, factors controlling milk OBCFA in sheep are largely unknown. Thus, the present meta-analysis examined relationships between diet composition and milk OBCFA using a database compiled with lot observations from 14 trials in dairy ewes fed lipid supplements. A total of 47 lots received lipid supplements, whereas their respective controls (27 lots) were fed the same basal diets without lipid supplementation. Relationships between milk OBCFA and dietary components were first assessed through a principal component analysis (PCA) and a correlation analysis. Then, responses of milk OBCFA to variations in specific dietary components (selected on the basis of the PCA) were examined in more detail by regression analysis. According to the loading plot, dietary unsaturated C18 FA loaded opposite to major milk OBCFA (e.g., 15:0, 15:0 anteiso, and 17:0) and were strongly correlated with principal component 1, which described 46% of variability. Overall, regression equations supported this negative, and generally linear, relationship between unsaturated C18 FA levels and milk OBCFA. However, the influence of C20-22 n-3 polyunsaturated FA and saturated FA was more limited. The PCA also suggested that dietary crude protein is not a determinant of milk OBCFA profile in dairy ewes, but significant relationships were observed between some OBCFA and dietary fiber or starch, consistent with a potential role of these FA as biomarkers of rumen cellulolytic and amylolytic bacteria. In this regard, regression equations indicated that iso FA would show opposite responses to increasing levels of acid detergent fiber (positive linear coefficients) and starch (negative linear coefficients). Lipid supplementation would not largely affect these associations, supporting the potential of OBCFA as noninvasive markers of rumen function under different feeding conditions (i.e., with or without lipid supplementation). Because consumption of these FA may have nutritional benefits for humans, the use of high-fiber/low-starch rations might be recommended to maintain the highest possible content of milk OBCFA in dairy sheep.