The Effect of Combined Exposure of Fusarium Mycotoxins on Lipid Peroxidation, Antioxidant Defense, Fatty Acid Profile, and Histopathology in Laying Hens' Liver

Fumonisin B1, T-2 toxin, and deoxynivalenol are frequently detected in feed materials. The mycotoxins induce free radical formation and, thereby, lipid peroxidation. The effects of mycotoxin exposure at the EU recommended limit (T-2/HT-2 toxin: 0.25 mg/kg; DON = 3AcDON/15-AScDON: 5 mg/kg; fumonisin B1: 20 mg/kg) and double dose (T-2/HT-2 toxin: 0.5 mg/kg, DON/3-AcDON/15-AcDON: 10 mg, and FB1: 40 mg/kg feed) were investigated during short-term (3 days) per os exposure in the liver of laying hens. On day 1 higher while on day 3 lower MDA concentrations were found in the low-dose group compared to the control. Fatty acid composition also changed: the proportion of monounsaturated fatty acids increased (p < 0.05) and the proportion of polyunsaturated fatty acids decreased by day 3. These alterations resulted in a decrease in the index of unsaturation and average fatty acid chain length. Histopathological alterations suggested that the incidence and severity of liver lesions were higher in the mycotoxin-treated laying hens, and the symptoms correlated with the fatty acid profile of total phospholipids. Overall, the findings revealed that mycotoxin exposure, even at the EU-recommended limits, induced lipid peroxidation in the liver, which led to changes in fatty acid composition, matched with tissue damage.

Interleaved trinuclear MRS for single-session investigation of carbohydrate and lipid metabolism in human liver at 7T

The liver plays a central role in metabolic homeostasis, as exemplified by a variety of clinical disorders with hepatic and systemic metabolic disarrays. Of particular interest are the complex interactions between lipid and carbohydrate metabolism in highly prevalent conditions such as obesity, diabetes, and fatty liver disease. Limited accessibility and the need for invasive procedures challenge direct investigations in humans. Hence, noninvasive dynamic evaluations of glycolytic flux and steady-state assessments of lipid levels and composition are crucial for basic understanding and may open new avenues toward novel therapeutic targets. Here, three different MR spectroscopy (MRS) techniques that have been combined in a single interleaved examination in a 7T MR scanner are evaluated. 1 H-MRS and 13 C-MRS probe endogenous metabolites, while deuterium metabolic imaging (DMI) relies on administration of deuterated tracers, currently 2 H-labelled glucose, to map the spatial and temporal evolution of their metabolic fate. All three techniques have been optimized for a robust single-session clinical investigation and applied in a preliminary study of healthy subjects. The use of a triple-channel 1 H/2 H/13 C RF coil enables interleaved examinations with no need for repositioning. Short-echo-time STEAM spectroscopy provides well resolved spectra to quantify lipid content and composition. The relative benefits of using water saturation versus metabolite cycling and types of respiratory synchronization were evaluated. 2 H-MR spectroscopic imaging allowed for registration of time- and space-resolved glucose levels following oral ingestion of 2 H-glucose, while natural abundance 13 C-MRS of glycogen provides a dynamic measure of hepatic glucose storage. For DMI and 13 C-MRS, the measurement precision of the method was estimated to be about 0.2 and about 16 mM, respectively, for 5 min scanning periods. Excellent results were shown for the determination of dynamic uptake of glucose with DMI and lipid profiles with 1 H-MRS, while the determination of changes in glycogen levels by 13 C-MRS is also feasible but somewhat more limited by signal-to-noise ratio.

Comparative lipidomics analysis of in vitro lipid digestion of sheep milk: Influence of homogenization and heat treatment

This study investigated the changes in sheep milk lipids during in vitro gastrointestinal digestion in response to heat treatment (75°C/15 s and 95°C/5 min) and homogenization (200/50 bar) using lipidomics. Homogenized and pasteurized sheep milk had higher levels of polar lipids in gastric digesta emptied at 20 min than raw sheep milk. Intense heat treatment of homogenized sheep milk resulted in a reduced level of polar lipids compared with homogenized-pasteurized sheep milk. The release rate of free fatty acids during small intestinal digestion for gastric digesta emptied at 20 min followed the order: raw ≤ pasteurized < homogenized-pasteurized ≤ homogenized-heated sheep milk; the rate for gastric digesta emptied at 180 min showed a reverse order. No differences in the lipolysis degree were observed among differently processed sheep milks. These results indicated that processing treatments affect the lipid composition of digesta and the lipolysis rate but not the lipolysis degree during small intestinal digestion.

Lipid Nanocarrier-Based mRNA Therapy: Challenges and Promise for Clinical Transformation

Due to the outbreak of novel coronavirus pneumonia, messenger RNA (mRNA) technology has attracted heated attention. A specific, safe, and efficient mRNA delivery system is needed. Lipid nanocarriers have become attractive carriers for mRNA delivery due to their high delivery efficiency, few side effects, and easy modification to change their structures and functions. To achieve the desired biological effect, lipid nanocarriers must reach the designated location for effective drug delivery. Therefore, the effects of the composition of lipid nanocarriers on their key properties are briefly reviewed. In addition, the progress of smart drug delivery by changing the composition of lipid nanocarriers is summarized, and the importance of component design and structure is emphasized. Subsequently, this review summarizes the latest progress in lipid nanocarrier-based mRNA technology and provides corresponding strategies for its current challenges, putting forward valuable information for the future design of lipid nanocarriers and mRNA.

Superior component compositions and antioxidant activity of Volvariella volvacea oil compared to those of Agrocybe cylindracea and two Lentinula edodes oils

The biological activity of an oil not only depends on its fatty acid composition but also the lipid composition and trace components. In this paper, to select the optimal mushroom oil, the component compositions (fatty acids, lipids, polyphenols, flavones, tocopherols, and unsaponifiable matters) and antioxidant activities in vitro of four mushroom oils (Agrocybe cylindracea, two Lentinula edodes, and Volvariella volvacea) were investigated and compared. The results showed that the four tested oils had the same fatty acid composition in different amounts, but the lipid component, minor components, and free radical scavenging activity in the tested oils varied widely depending on the type of mushroom. Overall, Volvariella volvacea oil was considered superior to the other three tested oils, as it had the largest contents of polar lipids, diglycerides, polyunsaturated fatty acids (74.38%), unsaponifiable matter (319.09 mg/kg), total phenols (124.08 mg/100 g), tocopherols (139.86 mg/100 g), as well as the highest ABTS and FRAP values (349.45 and 3801.70 μmol Trolox/100 g). This finding suggests that Volvariella volvacea oil is a promising resource that should be further researched.

Effects of Hydroxytyrosol Supplementation on Performance, Fat and Blood Parameters of Broiler Chickens

The study aimed to evaluate the effects of dietary supplementation of hydroxytyrosol (HT) on performance, fat, and blood parameters of broilers. In total, 960 male chicks were distributed into four treatments groups with 12 replicates with 20 birds per pen, with varying HT levels (0, 5, 10, and 50 mg/kg of feed) added to the basal diet from 1 to 42 days old. Feed intake, body weight gain, and feed conversion ratio were evaluated. Enzymes related to liver injury were evaluated in blood. Fatty acid profile and malondialdehyde (MDA) concentration were determined in the breast meat. Dietary supplementation of HT did not improve broilers' performance (p > 0.05). Birds fed 50 mg HT/kg had lower AST, ALT, and GGT concentrations (p ≤ 0.05), whereas broilers fed 5, 10, and 50 mg HT/kg, had lower TBIL concentrations (p ≤ 0.05). Breast meat of broilers fed 50 mg HT/kg had lower lipid content, saturated fatty acid, unsaturated fatty acids, MDA concentrations (p ≤ 0.05), and polyunsaturated fatty acids (p < 0.0001). In summary, supplementation of 5, 10, and 50 mg HT/kg does not improve the performance of broilers, but the dose of 50 mg HT/kg helps the liver against inflammation and improves fat parameters.

Efficacy of Chitosan, Pectin and Xanthan as Cold Gelling Agents in Emulsion Gels Stabilized with Legume Proteins to Be Used as Pork Backfat Replacers in Beef Burgers

This study aimed to develop stable emulsion gels enriched in polyunsaturated fatty acids, formulated with a mixture of olive (75%) and linseed (25%) oils, by incorporating two different stabilizers-pea and soy protein isolates-and three different cold gelling agents-chitosan, pectin and xanthan-to be used as pork backfat replacers in beef burgers. The color, pH, stability and textural properties of the emulsion gels were analyzed as affected by cold storage (4 °C, 7 days). Proximate composition, fatty acid content, technological and sensory properties were determined after burger processing. Meanwhile, color, pH, textural parameters and lipid oxidation were monitored in burgers at 0, 5 and 10 days of storage at 4 °C. A reduction of the fat content between 21.49% and 39.26% was achieved in the reformulated burgers as compared with the control, while the n-6/n-3 polyunsaturated fatty acid ratio decreased from 5.11 to 0.62. The highest moisture and fat retention were found in reformulated burgers made with xanthan, both with pea and soy proteins; however, their textural properties were negatively affected. The reformulated burgers made with chitosan were rated highest for sensory attributes and overall acceptability, not significantly different from the controls.

Echo time optimization for in-vivo measurement of unsaturated lipid resonances using J-difference-edited MRS

PURPOSE

Measuring lipid composition provides more information than just total lipid content. Hence, the non-invasive measurement of unsaturated lipid protons with both high efficiency and precision is of pressing need. This study was to optimize echo time (TE) for the best resolving of J-difference editing of unsaturated lipid resonances.

METHODS

The TE dependence of J-difference-edited (JDE) MRS was verified in the density-matrix simulation, soybean oil phantom, in-vivo experiments of white adipose tissue (WAT), and skeletal muscles using single-voxel MEGA-PRESS sequence at 3T. The peak SNRs and Cramér-Rao lower bounds (CRLBs) acquired at the proposed TE of 45 ms and previously published TE of 70 ms were compared (eight pairs) in WAT, extramyocelluar lipids (EMCLs), and intramyocellular lipids (IMCLs). The lipid composition in skeletal muscles was compared between healthy males (n = 7) and females (n = 7).

RESULTS

The optimal TE was suggested as 45 ms. Compared to 70 ms, the mean signal gains at TE of 45 ms were 151% in WAT, 168% in EMCL, 204% in IMCL for allylic resonance, and 52% in EMCL for diallylic resonance. CRLBs were significantly reduced at TE of 45 ms in WAT, EMCL, IMCL for allylic resonance and in EMCL for diallylic resonance. With TE of 45 ms, significant gender differences were found in the lipid composition in EMCL pools, while no difference in IMCL pools.

CONCLUSION

The JDE-MRS protocol with TE of 45 ms allows improved quantification of unsaturated lipid resonances in vivo and future lipid metabolism investigations.

Alkaline Phosphatase PhoD Mutation Induces Fatty Acid and Long-Chain Polyunsaturated Fatty Acid (LC-PUFA)-Bound Phospholipid Production in the Model Diatom Phaeodactylum tricornutum

With rapid growth and high lipid contents, microalgae have become promising environmentally friendly candidates for renewable biodiesel and health supplements in our era of global warming and energy depletion. Various pathways have been explored to enhance algal lipid production, especially gene editing. Previously, we found that the functional loss of PhoD-type alkaline phosphatase (AP), a phosphorus-stress indicator in phytoplankton, could lead to increased lipid contents in the model diatom Phaeodactylum tricornutum, but how the AP mutation may change lipid composition remains unexplored. This study addresses the gap in the research and investigates the effects of PhoD-type AP mutation on the lipid composition and metabolic regulation in P. tricornutum using transcriptomic and lipidomic analyses. We observed significantly modified lipid composition and elevated production of fatty acids, lysophosphatidylcholine, lysophosphatidylethanolamine, ceramide, phosphatidylinositol bisphosphate, and monogalactosylmonoacylglycerol after PhoD_45757 mutation. Meanwhile, genes involved in fatty acid biosynthesis were upregulated in mutant cells. Moreover, the mutant exhibited increased contents of ω-3 long-chain polyunsaturated fatty acid (LC-PUFA)-bound phospholipids, indicating that PhoD_45757 mutation could improve the potential bioavailability of PUFAs. Our findings indicate that AP mutation could influence cellular lipid synthesis and probably redirect carbon toward lipid production and further demonstrate that AP mutation is a promising approach for the development of high-value microalgal strains for biomedical and other applications.

The Expression Kinetics and Immunogenicity of Lipid Nanoparticles Delivering Plasmid DNA and mRNA in Mice

In recent years, lipid nanoparticles (LNPs) have emerged as a revolutionary technology for vaccine delivery. LNPs serve as an integral component of mRNA vaccines by protecting and transporting the mRNA payload into host cells. Despite their prominence in mRNA vaccines, there remains a notable gap in our understanding of the potential application of LNPs for the delivery of DNA vaccines. In this study, we sought to investigate the suitability of leading LNP formulations for the delivery of plasmid DNA (pDNA). In addition, we aimed to explore key differences in the properties of popular LNP formulations when delivering either mRNA or DNA. To address these questions, we compared three leading LNP formulations encapsulating mRNA- or pDNA-encoding firefly luciferase based on potency, expression kinetics, biodistribution, and immunogenicity. Following intramuscular injection in mice, we determined that RNA-LNPs formulated with either SM-102 or ALC-0315 lipids were the most potent (all p-values < 0.01) and immunogenic (all p-values < 0.05), while DNA-LNPs formulated with SM-102 or ALC-0315 demonstrated the longest duration of signal. Additionally, all LNP formulations were found to induce expression in the liver that was proportional to the signal at the injection site (SM102: r = 0.8787, p < 0.0001; ALC0315: r = 0.9012, p < 0.0001; KC2: r = 0.9343, p < 0.0001). Overall, this study provides important insights into the differences between leading LNP formulations and their applicability to DNA- and RNA-based vaccinations.

Lipid Process Markers of Durum Wheat Debranning Fractions

At present, whole grains are usually obtained by adding bran and middlings to refined flours, and this recombination leads to certain variations in the ratio of endosperm, bran and germ, resulting in flours with very different compositional characteristics and rheological properties. Therefore, this study focuses on the identification of specific lipid markers in different debranning fractions of Italian and Canadian durum wheat blends. The by-products obtained from five different debranning levels (3, 6, 9, 12 and 15%) had a high content of monounsaturated fatty acids and a higher concentration of tocopherols and sterols than the corresponding debranned grains. The Italian and Canadian durum wheat samples did not show significant differences in the content of these bioactive lipid compounds. In particular, palmitic acid, oleic acid, tocopherol isomers and total sterols could be useful biomarkers for evaluating the grain-to-tissue ratio in recombined flours.

Dietary Taurine Intake Affects the Growth Performance, Lipid Composition, and Antioxidant Defense of Juvenile Ivory Shell (Babylonia areolata)

In this study, an eight-week feeding trial was performed to investigate the effects of different taurine supplementation levels (0.0% as control, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0%) on the growth performance, lipid composition, and antioxidant ability in juvenile ivory shells Babylonia areolata. The results showed that taurine supplementation significantly improved the specific growth rates (SGRs) and survival rates of ivory shell (except the survival rate in the 3.0% taurine diet group) (p < 0.05). The SGRs showed an increasing and then decreasing tendency with increasing dietary taurine supplementation, and the highest value was observed in the 2.0% taurine diet (2.60%/d). The taurine content in the muscle of ivory shells fed taurine-supplemented diets significantly increased when compared to the control group (p < 0.05). The profiles of C22:2n6 in the muscle of ivory shells fed taurine-supplemented diets were significantly higher than in the control group (p < 0.05), and the highest values were observed in the 2.0% taurine supplementation group. The high-density lipoprotein cholesterol (HDL-C) content in the hepatopancreas showed an increasing and then decreasing tendency with increasing dietary taurine supplementation, while the low-density lipoprotein cholesterol (LDL-C) concentration showed a decreasing tendency. Furthermore, the activities of pepsin and lipase in both the intestine and hepatopancreas significantly increased at moderate taurine supplementation levels compared to the control group (p < 0.05). Accordingly, obvious increases in the histological parameters in the intestine of ivory shells fed taurine-supplemented diets were also found. As for the antioxidant ability, the activities of the total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) showed an increasing and then decreasing tendency with increasing dietary taurine supplementation, and the highest values were observed in the 1.0% and 1.0-2.0% taurine supplementation groups, respectively; the malondialdehyde (MDA) contents significantly decreased with increasing dietary taurine supplementation (p < 0.05). The taurine intake affected the expression of four appetite-related genes in the hepatopancreas, in which orexin and NPY showed an increasing and then decreasing tendency, while leptin and cholecyatoklnin decreased with increasing dietary taurine supplementation. In conclusion, moderate taurine supplementation in an artificial diet (about 1.5-2.0%) could improve the growth performance and antioxidant ability and change the lipid composition of juvenile ivory shells.

A simple, highly sensitive, and facile method to quantify ceramide at the plasma membrane

The role of ceramide in biological functions is typically based on the elevation of cellular ceramide, measured by LC-MS in the total cell lysate. However, it has become increasingly appreciated that ceramide in different subcellular organelles regulates specific functions. In the plasma membrane, changes in ceramide levels might represent a small percentage of the total cellular ceramide, evading MS detection but playing a critical role in cell signaling. Importantly, there are currently no efficient techniques to quantify ceramide in the plasma membrane. Here, we developed a method to measure the mass of ceramide in the plasma membrane using a short protocol that is based on the hydrolysis of plasma membrane ceramide into sphingosine by the action of exogenously applied bacterial recombinant neutral ceramidase. Plasma membrane ceramide content can then be determined by measuring the newly generated sphingosine at a stoichiometry of 1:1. A key step of this protocol is the chemical fixation of cells to block cellular sphingolipid metabolism, especially of sphingosine to sphingosine 1-phosphate. We confirmed that chemical fixation does not disrupt the lipid composition at the plasma membrane, which remains intact during the time of the assay. We illustrate the power of the approach by applying this protocol to interrogate the effects of the chemotherapeutic compound doxorubicin. Here we distinguished two pools of ceramide, depending on the doxorubicin concentration, consolidating different reports. In summary, we have developed the first approach to quantify ceramide in the plasma membrane, allowing the study of new avenues in sphingolipid compartmentalization and function.

Comparative Evaluation of Wild and Farmed Rainbow Trout Fish Based on Representative Chemosensory and Microbial Indicators of Their Habitats

Wild and farmed rainbow trout were compared with chemical profiling, chemosensory properties, carbon concentration and isotope analyses, 1- and 2-GC/O-MS, GC-FID, and aroma profile analyses. Results were linked with the prokaryotic and eukaryotic microbiological profile of the fish sources using multivariate statistical analysis. Fish from natural environments proved to have better sensory properties in terms of fruity, sweet, and citrusy attributes, compared to farmed fish. However, the farmed fish were found to have higher nutritional value based on their lipid contents. These differences might relate to the introduction of feed extrudates, which could influence the overall quality of fish products. Thereby, malodor episodes linked to musty/earthy off-odor notes related to odorants including geosmin, β-caryophyllene, (E,Z)-2,4-nonadienal, and (E,E)-2,4-nonadienal. These compounds, in turn, correlated with Asticcacaulis benevestitus, Curvibacter sp., Albidiferax sp., Aquabacterium commune, and Aquabacterium citratiphilum abundance and were further affected by oxygen levels in the water column.

H2-induced transient upregulation of phospholipids with suppression of energy metabolism

Molecular hydrogen (H₂) is an antioxidant and anti-inflammatory agent; however, the molecular mechanisms underlying its biological effects are largely unknown. Similar to other gaseous molecules such as inhalation anesthetics, H₂ is more soluble in lipids than in water. A recent study demonstrated that H₂ reduces radical polymerization-induced cellular damage by suppressing fatty acid peroxidation and membrane permeability. Thus, we sought to examine the effects of short exposure to H₂ on lipid composition and associated physiological changes in SH-SY5Y neuroblastoma cells. We analyzed cells by liquid chromatography-high-resolution mass spectrometry to define changes in lipid components. Lipid class analysis of cells exposed to H₂ for 1 hour revealed transient increases in glycerophospholipids including phosphatidylethanolamine, phosphatidylinositol, and cardiolipin. Metabolomic analysis also showed that H₂ exposure for 1 hour transiently suppressed overall energy metabolism accompanied by a decrease in glutathione. We further observed alterations to endosomal morphology by staining with specific antibodies. Endosomal transport of cholera toxin B to recycling endosomes localized around the Golgi body was delayed in H₂-exposed cells. We speculate that H₂-induced modification of lipid composition depresses energy production and endosomal transport concomitant with enhancement of oxidative stress, which transiently stimulates stress response pathways to protect cells.

4-Hydroxynonenal Modulates Blood-Brain Barrier Permeability In Vitro through Changes in Lipid Composition and Oxidative Status of Endothelial Cells and Astrocytes

Blood brain barrier (BBB) is a dynamic interface responsible for proper functioning of brain, but also a major obstacle for effective treatment of neurological diseases. Increased levels of free radicals, in high ferrous and high lipid content surrounding, induce lipid peroxidation, leading to production of 4-hydroxynonenal (HNE). HNE modifies all key proteins responsible for proper brain functioning thus playing a major role in the onset of neurological diseases. To investigate HNE effects on BBB permeability, we developed two in vitro BBB models-'physiological' and 'pathological'. The latter mimicked HNE modified extracellular matrix under oxidative stress conditions in brain pathologies. We showed that exogenous HNE induce activation of antioxidative defense systems by increasing catalase activity and glutathione content as well as reducing lipid peroxide levels in endothelial cells and astrocytes of 'physiological' model. While in 'pathological' model, exogenous HNE further increased lipid peroxidation levels of endothelial cells and astrocytes, followed by increase in Nrf2 and glutathione levels in endothelial cells. At lipid composition level, HNE caused increase in ω3 polyunsaturated fatty acid (PUFA) level in endothelial cells, followed by decrease in ω3 PUFA level and increase in monounsaturated fatty acid level in astrocytes. Using these models, we showed for the first time that HNE in 'pathological' model can reduce BBB permeability.

Comparison of chemical characterization and oxidative stability of Lycium barbarum seed oils: A comprehensive study based on processing methods

Five different processing methods (cold pressing, hot pressing, solvent extraction, ultrasound-assisted solvent extraction, and supercritical fluid extraction) were evaluated to extract oils from Lycium barbarum (L. barbarum) seeds based on the lipid composition, minor bioactive components, and oxidative stability of oils. A large proportion of unsaturated fatty acids was detected in the L. barbarum seed oil, especially linoleic acid (65.24-66.26%). Minor bioactive components were abundant in L. barbarum seed oils, including tocopherols (292.65-488.49 mg/kg), phytosterols (9606.31-166,684.77 mg/kg), polyphenols (35.65-113.87 mg/kg), and carotenoid (4.17-46.16 mg/100 g). Specifically, the phytosterol content was higher than that of other common oils. Comparing the different processing techniques, ultrasound-assisted solvent extraction provided the highest extraction yield and recovery. The quantities of tocopherols, phenols, and phytosterols in hot-pressed oil were higher than those in oils extracted from other methods, and thus it had the best oxidative stability. L. barbarum seed oils extracted by different techniques showed various characteristics and could be distinguished through principal component analysis and hierarchical cluster analysis. PRACTICAL APPLICATION: L. barbarum seed oil is a potentially underutilized oil resource with abundant essential fatty acid and phytosterol, which owns great value to apply in the nutritional, cosmetic, and medicinal fields. Hot pressing is an efficient method to produce L. barbarum seed oil for health care with high nutritional value and good quality, which can also be easily implemented on an industrial scale.

Effect of Lipid Composition on the Atheroprotective Properties of HDL-Mimicking Micelles

Atherosclerosis progression is driven by an imbalance of cholesterol and unresolved local inflammation in the arteries. The administration of recombinant apolipoprotein A-I (ApoA-I)-based high-density lipoprotein (HDL) nanoparticles has been used to reduce the size of atheroma and rescue inflammatory response in clinical studies. Because of the difficulty in producing large quantities of recombinant ApoA-I, here, we describe the preparation of phospholipid-based, ApoA-I-free micelles that structurally and functionally resemble HDL nanoparticles. Micelles were prepared using various phosphatidylcholine (PC) lipids combined with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[azido(polyethylene glycol)-2000] (DSPE-PEG2k) to form nanoparticles of 15-30 nm in diameter. The impacts of PC composition and PEGylation on the anti-inflammatory activity, cholesterol efflux capacity, and cholesterol crystal dissolution potential of micelles were investigated in vitro. The effects of micelle composition on pharmacokinetics and cholesterol mobilization ability were evaluated in vivo in Sprague Dawley rats. The study shows that the composition of HDL-mimicking micelles impacts their overall atheroprotective properties and supports further investigation of micelles as a therapeutic for the treatment of atherosclerosis.

Incorporation of phosphatidylserine improves efficiency of lipid based gene delivery systems

The essential homeostatic process of dead cell clearance (efferocytosis) is used by viruses in an act of apoptotic mimicry. Among others, virions leverage phosphatidylserine (PS) as an essential "eat me" signal in viral envelopes to increase their infectivity. In a virus-inspired biomimetic approach, we demonstrate that PS can be incorporated into non-viral lipid nanoparticle (LNP) pDNA/mRNA constructs to enhance cellular transfection. The inclusion of the bioactive PS leads to an increased ability of LNPs to deliver nucleic acids invitro to cultured HuH-7 hepatocellular carcinoma cells resulting in a 6-fold enhanced expression of a transgene. Optimal PS concentrations are in the range of 2.5 to 5% of total lipids. PS-decorated mRNA-LNPs show a 5.2-fold enhancement of invivo transfection efficiency as compared to mRNA-LNPs devoid of PS. Effects were less pronounced for PS-decorated pDNA-LNPs (3.2-fold increase). Incorporation of small, defined amounts of PS into gene delivery vectors opens new avenues for efficient gene therapy and can be easily extended to other therapeutic systems.

Dimensional Changes in Lipid Rafts from Human Brain Cortex Associated to Development of Alzheimer's Disease. Predictions from an Agent-Based Mathematical Model

Alzheimer’s disease (AD) is a neurodegenerative disease caused by abnormal functioning of critical physiological processes in nerve cells and aberrant accumulation of protein aggregates in the brain. The initial cause remains elusive—the only unquestionable risk factor for the most frequent variant of the disease is age. Lipid rafts are microdomains present in nerve cell membranes and they are known to play a significant role in the generation of hallmark proteinopathies associated to AD, namely senile plaques, formed by aggregates of amyloid β peptides. Recent studies have demonstrated that human brain cortex lipid rafts are altered during early neuropathological phases of AD as defined by Braak and Braak staging. The lipid composition and physical properties of these domains appear altered even before clinical symptoms are detected. Here, we use a coarse grain molecular dynamics mathematical model to predict the dimensional evolution of these domains using the experimental data reported by our group in human frontal cortex. The model predicts significant size and frequency changes which are detectable at the earliest neuropathological stage (ADI/II) of Alzheimer’s disease. Simulations reveal a lower number and a larger size in lipid rafts from ADV/VI, the most advanced stage of AD. Paralleling these changes, the predictions also indicate that non-rafts domains undergo simultaneous alterations in membrane peroxidability, which support a link between oxidative stress and AD progression. These synergistic changes in lipid rafts dimensions and non-rafts peroxidability are likely to become part of a positive feedback loop linked to an irreversible amyloid burden and neuronal death during the evolution of AD neuropathology.

Giant Unilamellar Vesicle Electroformation: What to Use, What to Avoid, and How to Quantify the Results

Since its inception more than thirty years ago, electroformation has become the most commonly used method for growing giant unilamellar vesicles (GUVs). Although the method seems quite straightforward at first, researchers must consider the interplay of a large number of parameters, different lipid compositions, and internal solutions in order to avoid artifactual results or reproducibility problems. These issues motivated us to write a short review of the most recent methodological developments and possible pitfalls. Additionally, since traditional manual analysis can lead to biased results, we have included a discussion on methods for automatic analysis of GUVs. Finally, we discuss possible improvements in the preparation of GUVs containing high cholesterol contents in order to avoid the formation of artifactual cholesterol crystals. We intend this review to be a reference for those trying to decide what parameters to use as well as an overview providing insight into problems not yet addressed or solved.

Cholesterol Modulates the Interaction between HIV-1 Viral Protein R and Membrane

Being a major metabolite for maintaining cellular homeostasis, as well as an important structural component in lipid membrane, cholesterol also plays critical roles in the life cycles of some viruses, including human immunodeficiency virus-1 (HIV-1). The involvement of cholesterol in HIV-1 infectivity, assembly and budding has made it an important research target. Viral protein R (Vpr) is an accessory protein of HIV-1, which is involved in many major events in the life cycle of HIV-1. In addition to its multi-functional roles in the HIV-1 life cycle, it is shown to interact with lipid membrane and form a cation-selective channel. In this work, we examined the effect of cholesterol on the interaction of Vpr and lipid membrane. Using calcein release assay, we found that the membrane permeability induced by the membrane binding of Vpr was significantly reduced in the presence of cholesterol in membrane. In addition, using solid-state NMR (ssNMR) spectroscopy, Vpr was shown to experience multiple chemical environments in lipid membrane, as indicated by the broad line shape of carbonyl 13C resonance of Cys-76 residue ranging from 165-178 ppm, which can be attributed to the existence of complex Vpr-membrane environments. We further showed that the presence of cholesterol in membrane will alter the distribution of Vpr in the complex membrane environments, which may explain the change of the Vpr induced membrane permeability in the presence of cholesterol.

Medium-Chain Triglyceride (MCT) Content of Adult Enteral Tube Feeding Formulas and Clinical Outcomes. A Systematic Review

Available data on the effect of lipid composition of enteral formulas on clinical outcomes are controversial. The present systematic review was performed in order to verify whether the presence of specific lipidic substrates, namely medium-chain triglycerides (MCT), in enteral tube feeding formulas is associated to measurable clinical benefits in patients receiving enteral nutrition in different clinical settings, including home enteral nutrition (HEN). The results of this systematic review highlight a lack of robust evidence supporting the use of specific types of lipids in standard or disease-specific formulas. Evidence exists, however, that MCT-containing formulas are safe and well-tolerated. Further, well-designed, adequately powered, randomized controlled trials would be needed in order to assess the superiority of MCT- containing enteral formulas over other standard or disease-specific commercially available enteral products.

Contrastive analysis of lipid composition and thermal and crystallization behavior of olein/stearin fractionated by novel layer melt crystallization from palm oil

BACKGROUND

Melt crystallization is typically recognized as a highly efficient and green method for oil fractionation. This work concentrated on novel layer melt crystallization for preparing desirable olein and stearin products from palm oil and the evaluation of fraction quality. Layer melt crystallization was performed at various temperatures and the effects on fractions were evaluated using iodine value (IV), solid fat content (SFC) and melting point. The lipid composition, thermal and crystallization properties, and phase behaviors of the final optimized fractions were determined using gas chromatography, high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry and differential scanning calorimetry.

RESULTS

Increasing crystallization tube temperatures under the same jacket temperature increased the melting point and SFC, while decreasing the IV of the olein product. Opposite results were observed for the stearin product. Major fatty acids in fractions were determined as palmitic acid and oleic acid. 1,2-Dioleoyl-3-palmitoylglycerol and 1,3-dipalmitoyl-2-oleoylglycerol were identified as the main triacylglycerols in olein and stearin fractions, respectively. A critical effect of crystallization temperature on co-crystallization of oleins and stearins was revealed. A transition from plate-like crystal growth to spherulitic growth with spontaneous nucleation was indicated in palm oil and stearin fractions with increasing crystallization temperature. As for olein fractions, a temperature increase resulted in heterogeneous nucleation from instantaneous nucleation.

CONCLUSIONS

Novel layer melt crystallization was successfully applied and optimized for fractionating palm oil. The composition and property changes of obtained fractions were analyzed and explained at both macroscopic and microscopic levels. © 2021 Society of Chemical Industry.

Effects of the entomopathogenic fungi Metarhizium robertsii, Metarhizium flavoviride, and Isaria fumosorosea on the lipid composition of Galleria mellonella larvae

Galleria mellonella is a pest of the honey bee (Apis mellifera L.) and causes significant losses to the beekeeping industry; therefore, experiments are needed to decode the effects of entomopathogenic fungi on insect physiology. The gas chromatography-mass spectrometry (GC-MS) method was successful for the determination of the organic compounds of Galleria mellonella larvae, noninfected and infected by three fungal species: M. robertsii, M. flavoviride, and I. fumosorosea. A total of 46 compounds were identified in G. mellonella, including fatty acids, other acids, fatty acid methyl esters, monoacylglycerols, amino acids, sterols, and several other organic compounds. The lipids of G. mellonella larvae after M. robertsii, M. flavoviride, and I. fumosorosea exposure contained 40, 35, and 33 organic compounds, respectively. The following organic compounds, present in the noninfected larvae, were absent from the infected larvae: fatty acids C22:0 and C24:0, glutaric acid, urocanic acid, hydroxycinnamic acid, dihydroxycinnamic acid, 10-oxodecanoic acid, glycine, aspartic acid, glutamic acid, lysine, tyrosine, tryptophan, 2-aminobutyric acid, and tyramine. These compounds can be used by fungi as an exogenous source of carbon. The following organic compounds, present in the infected larvae, were absent from the noninfected larvae: fatty acids C10:0, C11:0, C13:0, and C20:0, suberic acid, phenylacetic acid, fatty acid methyl ester (FAME) C16:0, FAME C18:2, FAME C18:1, glycerol 2-monopalmitate, norvaline, proline, sitosterol, and 2-dekanal. These compounds can be synthesized as an insect response to fungal infection.

A comprehensive study of raw and roasted macadamia nuts: Lipid profile, physicochemical, nutritional, and sensory properties

Macadamia nuts have high nutritional value and positive health attributes. Changes to the composition and availability of these compounds during roasting contribute to product quality. In this study, changes to the chemical composition of lipids (fatty acids, triglycerides, and free fatty acids) and other phytochemicals were analyzed, and a sensory evaluation was carried out of two major varieties of macadamia nuts planted in China, after roasting. Only small changes in fatty acid (FA) content and a slight decrease in total triglycerides (TAGs) were observed after roasting. The free fatty acid (FFA) content and the peroxide value were increased by roasting. The total available polyphenol content increased by 25.6% and the oxidative stability index of kernels increased by 21.6%. The sensory scores for taste and aroma were doubled by roasting. Overall, the sensory, nutritional quality, and oxidative stability of roasted macadamia nuts were greatly improved, compared with raw nuts.

Sex Differences in Insulin Sensitivity are Related to Muscle Tissue Acylcarnitine But Not Subcellular Lipid Distribution

OBJECTIVE

Sex differences in insulin sensitivity are present throughout the life-span, with men having a higher prevalence of insulin resistance and diabetes compared with women. Differences in lean mass, fat mass, and fat distribution-particularly ectopic fat-have all been postulated to contribute to the sexual dimorphism in diabetes risk. Emerging data suggest ectopic lipid composition and subcellular localization are most relevant; however, it is not known whether they explain sex differences in obesity-induced insulin resistance.

METHODS

To address this gap, this study evaluated insulin sensitivity and subcellular localization of intramuscular triacylglycerol, diacylglycerol, and sphingolipids as well as muscle acylcarnitines and serum lipidomics in people with obesity.

RESULTS

Insulin sensitivity was significantly lower in men (P < 0.05); however, no sex differences were found in localization of intramuscular triacylglycerol, diacylglycerol, or sphingolipids in skeletal muscle. In contrast, men had higher total muscle acylcarnitine (P < 0.05) and long-chain muscle acylcarnitine (P < 0.05), which were related to lower insulin sensitivity (r = -0.42, P < 0.05). Men also displayed higher serum ceramide (P = 0.05) and lysophosphatidylcholine (P < 0.01).

CONCLUSIONS

These data reveal novel sex-specific associations between lipid species involved in the coupling of mitochondrial fatty acid transport, β-oxidation, and tricarboxylic acid cycle flux that may provide therapeutic targets to improve insulin sensitivity.

Pulsed Electric Fields Promote Liposome Buddings

Background: Liposomes have been a useful tool to analyze membrane behavior. Various studies have attempted to induce biological activities, for example, buddings, divisions, and endocytosis, on liposomes, focusing on lipid rafts that move along electric fields. Materials and Methods: Liposomes consisting of soybean lecithin, phosphatidylcholine, and cholesterol were prepared, with inner and outer liquid conductivities of 0.595 and 1.564 S/m, respectively. Results: We tried to induce buddings by pulsed electric fields (PEFs) on liposomes. Results demonstrated that 1.248 kV/cm, 400 μs PEF promoted postpulse liposome buddings, which were preceded by a membrane relaxation. Although a transient thick area (a lipid raft-like area) on the membrane just after PEF application preceded buddings, it was not the sufficient factor for buddings. Conclusion: We established a brief model as follows: 1.248 kV/cm, 400 μs PEF induced the lipid membrane relaxation without electroporation to trigger buddings. The current results could be a new frontier in bioelectrics.

Lipid Metabolism at Membrane Contacts: Dynamics and Functions Beyond Lipid Homeostasis

Membrane contact sites (MCSs), regions where the membranes of two organelles are closely apposed, play critical roles in inter-organelle communication, such as lipid trafficking, intracellular signaling, and organelle biogenesis and division. First identified as “fraction X” in the early 90s, MCSs are now widely recognized to facilitate local lipid synthesis and inter-organelle lipid transfer, which are important for maintaining cellular lipid homeostasis. In this review, we discuss lipid metabolism and related cellular and physiological functions in MCSs. We start with the characteristics of lipid synthesis and breakdown at MCSs. Then we focus on proteins involved in lipid synthesis and turnover at these sites. Lastly, we summarize the cellular function of lipid metabolism at MCSs beyond mere lipid homeostasis, including the physiological meaning and relevance of MCSs regarding systemic lipid metabolism. This article is part of an article collection entitled: Coupling and Uncoupling: Dynamic Control of Membrane Contacts.

Building Blocks to Design Liposomal Delivery Systems

The flexibility of liposomal carriers does not just simply rely on their capability to encapsulate various types of therapeutic substances, but also on the large array of components used for designing liposome-based nanoformulations. Each of their components plays a very specific role in the formulation and can be easily replaced whenever a different therapeutic effect is desired. It is tempting to describe this by an analogy to Lego blocks, since a whole set of structures, differing in their features, can be designed using a certain pool of blocks. In this review, we focus on different design strategies, where a broad variety of liposomal components facilitates the attainment of straightforward control over targeting and drug release, which leads to the design of the most promising systems for drug delivery. The key aspects of this block-based architecture became evident after its implementation in our recent works on liposomal carriers of antisense oligonucleotides and statins, which are described in the last chapter of this review.

Effects of fatty liver on the size and composition of high-density lipoprotein cholesterol subpopulations in adolescents with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is an emerging disease in the pediatric population. The association between T2DM and non-alcoholic fatty liver disease (NAFLD) has been described. Recent evidence suggests that sizes and composition of high-density lipoprotein (HDL) may be more important that HDL-C levels in predicting coronary heart disease. There is not data regarding the HDL subclasses distribution and composition in T2DM youths with NAFLD.

METHODS

This cross-sectional study included 47 adolescents with T2DM and 23 non-diabetic controls of both sexes aged 10 to 18 years. The presence of NAFLD was determined estimated proton density fat fraction (PDFF) by magnetic resonance by spectroscopy. We compared the HDL subclasses distribution (HDL2b, HDL2a, HDL3a HDL3b and HDL3c) and the HDL chemical composition (total protein, triglyceride, phospholipid, cholesteryl esters, and free cholesterol) between the groups of adolescents with T2DM and the control group.

RESULTS

Patients with T2DM and NAFLD had a significantly lower proportion HDL2b (P = .040) and a higher proportion of HDL3c (P = .035); higher proportion of TG (P = .032) and a lower CE (P = .002) and FC (P < .001). A negative association was observed between PDFF and the percentages of HDL2b (r² = -0.341, P = .004) and the average particle size (r² = -0.327, P = .05), and a positive association with HDL3c subpopulations (r² = 0.327, P = .015); about composition inside HDL particle, a positive association with PDFF and the TG (r² = 0.299, P = .013) and negative with CE (r² = -0.265, P = .030).

CONCLUSIONS

In adolescents diagnosed with T2DM, the presence of NAFLD is associated with abnormalities in the distribution of HDL subpopulations and the lipid composition of HDL particles.

Influence of the Technological Process on the Biochemical Composition of Fresh Roe and Bottarga from Liza ramada and Mugil cephalus

Bottarga is a high-priced delicacy with high nutritional value, and, in Italy, bottarga from mullets has been recognized to be a traditional food product. The flathead grey mullet Mugil cephalus and the thinlip grey mullet Liza ramada are the main cultured grey mullets in the Mediterranean Sea. In this study, fresh roe and bottarga from these two species were investigated to evaluate the influence of the technological process and the species on their biochemical composition and health advantages. The 1 h/200 g salting-out step did not increase the levels of NaCl in the bottarga, although it highly decreased the levels of some heavy metals like Cu and Al. Processing of fresh roe in bottarga led to an essential modification of the lipid fraction, following a general series of monousatturated fatty acid (MUFA)> poliunsutturated fatti acid (PUFA) > saturated fatty acid (SAFA) and an increase in both ω3 and ω6 in Liza ramada. Moreover, bottarga showed higher levels of squalene and cholesterol and an increased Essential Amino Acid/Total Amino Acid ratio (EAA/TAA) in both species. In addition to the nutritional benefits for the consumer, the process proposed in this study may represent a reliable tool for local producers to obtain a final bottarga with both a reproducible biochemical composition and organoleptic characteristics.

The Study of HIV-1 Vpr-Membrane and Vpr-hVDAC-1 Interactions by Graphene Field-Effect Transistor Biosensors

The viral protein R (Vpr) of human immunodeficiency virus 1 (HIV-1) is involved in many cellular processes during the viral life cycle; however, its associated mechanisms remain unclear. Here, we designed an Escherichia coli expression construct to achieve a milligram yield of recombinant Vpr. In addition, we fabricated a graphene field-effect transistor (G-FET) biosensor, with the modification of a supported lipid bilayer (SLB), to study the interaction between Vpr and its interaction partners. The Dirac point of the SLB/G-FET was observed to shift in response to the binding of Vpr to the SLB. By fitting the normalized shift of the Dirac point as a function of Vpr concentration to the Langmuir adsorption isotherm equation, we could extract the dissociation constant (K_d) to quantify the Vpr binding affinity. When the 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DOPG) membrane was used as the SLB, the dissociation constant was determined to be 9.6 ± 2.1 μM. In contrast, only a slight shift of the Dirac point was observed in response to the addition of Vpr when the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) membrane was used as the SLB. Taking advantage of the much weaker binding of Vpr to the DOPC membrane, we prepared a human voltage-dependent anion channel isoform 1 (hVDAC-1)-embedded DOPC membrane as the SLB for the G-FET and used it to determine the dissociation constant to be 5.1 ± 0.9 μM. In summary, using the clinically relevant Vpr protein as an example, we demonstrated that an SLB/G-FET biosensor is a suitable tool for studying the interaction between a membrane-associated protein and its interaction partners.

Lipid Composition of Sheffersomyces stipitis M12 Strain Grown on Glycerol as a Carbon Source

Research background

In this study the content and composition of lipids in ergosterol-reduced Sheffersomyces stipitis M12 strain grown on glycerol as a carbon source is determined. Blocking the ergosterol synthesis route in yeast cells is a recently proposed method for increasing S-adenosyl-l-methionine (SAM) production.

Experimental approach

The batch cultivation of M12 yeast was carried out under aerobic conditions in a laboratory bioreactor with glycerol as carbon source, and with pulsed addition of methionine. Glycerol and SAM content were monitored by high-performance liquid chromatography, while fatty acid composition of different lipid classes, separated by solid phase extraction, was determined by gas chromatography.

Results and conclusion

Despite the reduced amount of ergosterol in yeast cells, thanks to the reorganized lipid metabolism, M12 strain achieved high biomass yield and SAM production. Neutral lipids prevailed (making more than 75% of total lipids), but their content and composition differed significantly in the two tested types of yeast. Unsaturated and C18 fatty acids prevailed in both the M12 strain and wild type. In all fractions except free fatty acids, the index of unsaturation in M12 strain was lower than in the wild strain. Our tested strain adjusts itself by changing the content of lipids (mainly phospholipids, sterols and sterol esters), and with desaturation adjustments, to maintain proper functioning and fulfil increased energy needs.

Novelty and scientific contribution

Reorganization of S. stipitis lipid composition caused by blocking the metabolic pathway of ergosterol synthesis was presented. A simple scheme of actual lipid metabolism during active SAM production in S. stipitis, grown on glycerol was constructed and shown. This fundamental knowledge of lipid metabolic pathways will be a helpful tool in improving S. stipitis as an expression host and a model organism, opening new perspectives for its applied research.

Metabolite cycled liver 1 H MRS on a 7 T parallel transmit system

INTRODUCTION

Single-voxel ¹ H MRS in body applications often suffers from respiratory and other motion induced phase and frequency shifts, which lead to incoherent averaging and hence to suboptimal results.

METHODS

Here we show the application of metabolite cycling (MC) for liver STEAM-localized ¹ H MRS on a 7 T parallel transmit system, using eight transmit-receive fractionated dipole antennas with 16 additional, integrated receive loops. MC-STEAM measurements were made in six healthy, lean subjects and compared with STEAM measurements using VAPOR water suppression. Measurements were performed during free breathing and during synchronized breathing, for which the subjects did breathe in between the MRS acquisitions. Both intra-session repeatability and inter-session reproducibility of liver lipid quantification with MC-STEAM and VAPOR-STEAM were determined.

RESULTS

The preserved water signal in MC-STEAM allowed for robust phase and frequency correction of individual acquisitions before averaging, which resulted in in vivo liver spectra that were of equal quality when measurements were made with free breathing or synchronized breathing. Intra-session repeatability and inter-session reproducibility of liver lipid quantification were better for MC-STEAM than for VAPOR-STEAM. This may also be explained by the more robust phase and frequency correction of the individual MC-STEAM acquisitions as compared with the VAPOR-STEAM acquisitions, for which the low-signal-to-noise ratio lipid signals had to be used for the corrections.

CONCLUSION

Non-water-suppressed MC-STEAM on a 7 T system with parallel transmit is a promising approach for ¹ H MRS applications in the body that are affected by motion, such as in the liver, and yields better repeatability and reproducibility compared with water-suppressed measurements.

Lipid Profiling and Microstructure Characteristics of Goat Milk Fat from Different Stages of Lactation

Goat milk at different lactations show varied lipids distributions, which are potentially dietary influencing factors for the health of human consumers. Herein, the effects of lactation stages (colostral, transitional, and mature stages) on lipid profiling and microstructure of goat milk fat (GMF) were investigated. A total of 359 species of triacylglycerols (TAGs), 27 species of diacylglycerols (DAGs), and 10 classes of phospholipids (PLs) were identified using high resolution tandem mass spectrometry (HR-MS/MS). Of importance, goat transitional milk presented the highest levels of MUFA (29.51%) and lyso-phospholipids (7.95% of total PLs) among these three different lactations. A lactation-dependent attenuation was found at the level of PUFA in goat milk, particularly long-chain PUFA ω-6. Similar behavior was observed in the total proportions of POO (16:0/18:1/18:1) and PSL (16:0/18:0/18:2), presenting a decrease from 3.70% to 3.23% as the proceeding period from colostrum to mature. The relative contents of sphingomyelin and cholesterol in goat colostrum were approximately twice and three times that in mature milk, respectively. Unlikely, both PMCy+MCaM (16:0/14:0/8:0 + 14:0/10:0/14:0) and BuPO (4:0/16:0/18:1) TAGs, the foremost saturated and monounsaturated TAGs in goat colostrum, respectively, showed upward trends over the period from colostrum to mature. Interestingly, no significant variation in milk fat globule morphology was monitored at different lactation periods. Therefore, all our results demonstrated that the main influences of lactation stages on GMF were the lipid profiling, providing a theoretical guidance for rational implement of lipids in goat milk.

Arachidonic Acid in Human Milk

Breastfeeding is universally recommended as the optimal choice of infant feeding and consequently human milk has been extensively investigated to unravel its unique nutrient profile. The human milk lipid composition is unique and supplies specifically long-chain polyunsaturated fatty acids (LC-PUFAs), in particular, arachidonic acid (ARA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3). Arachidonic acid (ARA) is the most predominant long-chain polyunsaturated fatty acid in human milk, albeit at low concentrations as compared to other fatty acids. It occurs predominantly in the triglyceride form and to a lesser extent as milk fat globule membrane phospholipids. Human milk ARA levels are modulated by dietary intake as demonstrated by animal and human studies and consequently vary dependent on dietary habits among mothers and regions across the globe. ARA serves as a precursor to eicosanoids and endocannabinoids that also occur in human milk. A review of scientific and clinical studies reveals that ARA plays an important role in physiological development and its related functions during early life nutrition. Therefore, ARA is an important nutrient during infancy and childhood and, as such, appropriate attention is required regarding its nutritional status and presence in the infant diet. Data are emerging indicating considerable genetic variation in encoding for desaturases and other essential fatty acid metabolic enzymes that may influence the ARA level as well as other LC-PUFAs. Human milk from well-nourished mothers has adequate levels of both ARA and DHA to support nutritional and developmental needs of infants. In case breastfeeding is not possible and infant formula is being fed, experts recommend that both ARA and DHA are added at levels present in human milk.

Specific Composition of Lipid Phases Allows Retaining an Optimal Thylakoid Membrane Fluidity in Plant Response to Low-Temperature Treatment

Thylakoid membranes isolated from leaves of two plant species, the chilling tolerant (CT) pea and chilling sensitive (CS) runner bean, were assessed for the composition of lipids, carotenoids as well as for the arrangement of photosynthetic complexes. The response to stress conditions was investigated in dark-chilled and subsequently photo-activated detached leaves of pea and bean. Thylakoids of both species have a similar level of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), but different sulfoquinovosyldiacylglycerol to phosphatidylglycerol (PG) ratio. In pea thylakoid fraction, the MGDG, DGDG and PG, have a higher double bond index (DBI), whereas bean thylakoids contain higher levels of high melting point PG. Furthermore, the lutein to the β-carotene ratio is higher in bean thylakoids. Smaller protein/lipid ratio in pea than in bean thylakoids suggests different lipid-protein interactions in both species. The differences between species are also reflected by the course of temperature-dependent plots of chlorophyll fluorescence pointing various temperatures of the lipid phase transitions of pea and bean thylakoids. Our results showed higher fluidity of the thylakoid membrane network in pea than in bean in optimal temperature conditions. Dark-chilling decreases the photochemical activity and induces significant degradation of MGDG in bean but not in pea leaves. Similarly, substantial changes in the arrangement of photosynthetic complexes with increase in LHCII phosphorylation and disturbances of the thylakoid structure take place in bean thylakoids only. Changes in the physical properties of bean thylakoids are manifested by the conversion of a three-phase temperature-dependent plot to a one-phase plot. Subsequent photo-activation of chilled bean leaves caused a partial restoration of the photochemistry and of membrane physical properties, but not of the photosynthetic complexes arrangement nor the thylakoid network structure. Summarizing, the composition of the thylakoid lipid matrix of CT pea allows retaining the optimal fluidity of its chloroplast membranes under low temperatures. In contrast, the fluidity of CS bean thylakoids is drastically changed, leading to the reorganization of the supramolecular structure of the photosynthetic complexes and finally results in structural remodeling of the CS bean thylakoid network.

The influence of dietary sunflower oil, rich in n-6 polyunsaturated fatty acids, in combination with vitamin C on ram semen parameters, sperm lipids and fertility

BACKGROUND

Dietary fats, fed to ruminant animals, have been observed to improve reproductive function. Sunflower oil is one of the richest sources of polyunsaturated fatty acids (PUFAs), over 60% of which is linoleic acid (C18:2). With regard to recommendations for increased consumption of PUFAs, special emphasis has been given to the importance of consuming more antioxidants to prevent lipid peroxide formation. This study evaluated the effects of dietary n-6 PUFAs and vitamin C (VC) in rams - in particular, on semen quality, blood metabolites, sperm lipids and overall fertility.

RESULTS

Diets supplemented with SFO and VC increased the proportion of motile sperms and their progressive motility improved (P < 0.01). Rams fed a diet containing SFO had an increased proportion of sperms with normal acrosomes in their semen samples (P < 0.01). The highest levels of lactate dehydrogenase activity (LDH) enzyme were found in control rams (2.60 U mL^-1 ). Feeding SFO significantly affected blood triglyceride and cholesterol concentrations (P < 0.05). Diets containing SFO increased the proportion of C18:2c, C20:4, C20:3 and C22 in the sperm lipid composition (P < 0.05). Semen of SFO and VC-fed rams was more fertile than that of control rams when it was artificially inseminated to ewes.

CONCLUSION

Feeding rams with supplemental SFO and VC increased semen quality and improved fertility rates. © 2019 Society of Chemical Industry.

Accumulation of saturated intramyocellular lipid is associated with insulin resistance

Intramyocellular lipid (IMCL) accumulation has been linked to both insulin-resistant and insulin-sensitive (athletes) states. Biochemical analysis of intramuscular triglyceride composition is confounded by extramyocellular triglycerides in biopsy samples, and hence the specific composition of IMCLs is unknown in these states. ¹H magnetic resonance spectroscopy (MRS) can be used to overcome this problem. Thus, we used a recently validated ¹H MRS method to compare the compositional saturation index (CH₂:CH₃) and concentration independent of the composition (CH₃) of IMCLs in the soleus and tibialis anterior muscles of 16 female insulin-resistant lipodystrophic subjects with that of age- and gender-matched athletes (n = 14) and healthy controls (n = 41). The IMCL CH₂:CH₃ ratio was significantly higher in both muscles of the lipodystrophic subjects compared with controls but was similar in athletes and controls. IMCL CH₂:CH₃ was dependent on the IMCL concentration in the controls and, after adjusting the compositional index for quantity (CH₂:CH_3adj), could distinguish lipodystrophics from athletes. This CH₂:CH_3adj marker had a stronger relationship with insulin resistance than IMCL concentration alone and was inversely related to VO_2max. The association of insulin resistance with the accumulation of saturated IMCLs is consistent with a potential pathogenic role for saturated fat and the reported benefits of exercise and diet in insulin-resistant states.

Activation of extracytoplasmic function sigma factors upon removal of glucolipids and reduction of phosphatidylglycerol content in Bacillus subtilis cells lacking lipoteichoic acid

In Bacillus subtilis, extracytoplasmic function (ECF) sigma factors are activated by reduction of phosphatidylglycerol (PG) content, absence of glucolipids, or absence of lipoteichoic acid (LTA). LTA is synthesized by polymerization of the glycerophosphate moiety of PG onto diglucosyldiacylglycerol (DGlcDG), a major glucolipid in B. subtilis, in the plasma membrane. Thus, reduction of PG content or absence of glucolipids might cause some changes in LTA, and hence we investigated whether reduction of PG content or absence of glucolipids induces the activation of ECF sigma factors independently from an ensuing change in LTA. Disruption of ugtP, responsible for glucolipid synthesis, in cells lacking LTA caused an additive increase of activation levels of σ^M, σ^X, σ^V and σ^Y (3.1-, 2.2-, 2.1- and 1.4-fold, respectively), relative to their activation levels in cells lacking LTA alone. Reduction of PG content (by repressing P_spac-pgsA) in the cells lacking LTA caused an additive increase of activation levels of σ^M, σ^W and σ^V (2.3-, 1.9- and 2.2-fold, respectively). These results suggested that absence of glucolipids or reduction of PG alone, not the possible secondary alteration in LTA, leads to changes that affect the regulation systems of some ECF sigma factors in the plasma membrane.

Characterization of chylomicron in preterm infants

BACKGROUND

The aim of this study was to investigate cholesterol and triglyceride levels in the chylomicron fraction of preterm infants at birth and during the early postnatal period.

METHODS

The subjects consisted of 133 infants (81 boys and 52 girls): 74 were term infants born at 37-41 weeks of gestation and 59 were preterm infants born at 29-36 weeks of gestation. Cholesterol and triglyceride in the chylomicron fraction were measured using high-performance liquid chromatography.

RESULTS

Compared with term infants, preterm infants had higher cholesterol and lower triglyceride in the chylomicron fraction, both in cord blood and at 1 month after birth. Thus, the chylomicron triglyceride/cholesterol ratio was significantly lower in preterm infants than in term infants in cord blood and at 1 month of age. On single regression analysis the chylomicron triglyceride/cholesterol ratio correlated positively with gestational age at birth (r = 0.331, P = 0.0003) and at 1 month (r = 0.221, P = 0.0119).

CONCLUSIONS

Preterm infants have a less-lipidated chylomicron composition at birth and at 1 month of age. Some prenatal factors may persist to influence chylomicron lipidation during the early postnatal period.

Lipids modulate the insertion and folding of the nascent chains of alpha helical membrane proteins

Membrane proteins must be inserted into a membrane and folded into their correct structure to function correctly. This insertion occurs during translation and synthesis by the ribosome for most α-helical membrane proteins. Precisely how this co-translational insertion and folding occurs, and the role played by the surrounding lipids, is still not understood. Most of the work on the influence of the lipid environment on folding and insertion has focussed on denatured, fully translated proteins, and thus does not replicate folding during unidirectional elongation of nascent chains that occurs in the cell. This review aims to highlight recent advances in elucidating lipid composition and bilayer properties optimal for insertion and folding of nascent chains in the membrane and in the assembly of oligomeric proteins.

Analysis of sensitive skin barrier function: basic indicators and sebum composition

OBJECTIVES

Sensitive skin (SS) is a condition characterised by high reactivity, low tolerance, and susceptibility to allergies of the skin. Owing to changes in the environment and marketing strategies, as well as the increasing public awareness about skin care, attention to skin condition is gradually increasing. The aim of this study is to explore the differences in the skin barrier of SS and normal skin (NS).

METHODS

A questionnaire survey was conducted and basic indicators of the skin barrier were analysed. It was found that sebum secretion in the SS group was lower than that in the NS group, suggesting that the development of SS might be associated with sebum secretion and its specific components. Next, an ultra performance liquid chromatography-quadruple time-of-flight mass spectrometer was used to identify facial sebum components in female volunteers.

RESULTS

The results showed that the sebum of female volunteers with SS had high levels of ceramides, glycerophosphoethanolamines, and diacylglycerols, and low levels of glucosylceramides, glycerophosphoserines, glycerophosphocholines, and triacylglycerols.

CONCLUSION

Analysis of lipid functions suggested that the main reason for SS development in women might be a barrier dysfunction caused by excessive apoptosis and lack of water. Therefore, anti-allergy additives in cosmetic products that could inhibit apoptosis of keratinocytes and methods to maintain the stability of water molecules in the skin should be further studied.

The host-cell restriction factor SERINC5 restricts HIV-1 infectivity without altering the lipid composition and organization of viral particles

The host-cell restriction factor SERINC5 potently suppresses the infectivity of HIV, type 1 (HIV-1) particles, and is counteracted by the viral pathogenesis factor Nef. However, the molecular mechanism by which SERINC5 restricts HIV-1 particle infectivity is still unclear. Because SERINC proteins have been suggested to facilitate the incorporation of serine during the biosynthesis of membrane lipids and because lipid composition of HIV particles is a major determinant of the infectious potential of the particles, we tested whether SERINC5-mediated restriction of HIV particle infectivity involves alterations of membrane lipid composition. We produced and purified HIV-1 particles from SERINC5293T cells with very low endogenous SERINC5 levels under conditions in which ectopically expressed SERINC5 restricts HIV-1 infectivity and is antagonized by Nef and analyzed both virions and producer cells with quantitative lipid MS. SERINC5 restriction and Nef antagonism were not associated with significant alterations in steady-state lipid composition of producer cells and HIV particles. Sphingosine metabolism kinetics were also unaltered by SERINC5 expression. Moreover, the levels of phosphatidylserine on the surface of HIV-1 particles, which may trigger uptake into non-productive internalization pathways in target cells, did not change upon expression of SERINC5 or Nef. Finally, saturating the phosphatidylserine-binding sites on HIV target cells did not affect SERINC5 restriction or Nef antagonism. These results demonstrate that the restriction of HIV-1 particle infectivity by SERINC5 does not depend on alterations in lipid composition and organization of HIV-1 particles and suggest that channeling serine into lipid biosynthesis may not be a cardinal cellular function of SERINC5.

Differential Lipid Composition and Gene Expression in the Semi-Russeted "Cox Orange Pippin" Apple Variety

Russeting is characterized by a particular rough and brown phenotype, which is mainly due to the accumulation of suberin in the inner part of the epidermal cell walls. In our previous bulk transcriptomic analysis, comparing fully russeted, and waxy apple varieties, showed, in apple fruit skin, a massive decreased expression of cutin, wax and some pentacyclic triterpene biosynthesis genes in the russeted varieties, with an expected concomitant enhanced expression of the suberin biosynthetic genes. In the present work, we performed a deep investigation of the aliphatic composition of the cutin, suberin, waxes, and triterpenes in the waxy and russeted patches of the semi-russeted apple variety "Cox Orange Pippin." A targeted gene expression profiling was performed to validate candidate genes which were identified in our previous work and might be involved in the respective metabolic pathways. Our results showed that a decrease of cuticular waxes, ursolic acid and oleanolic acid, accompanied by an accumulation of alkyl-hydroxycinamates and betulinic acid, occurs in the russeted patches. The suberin monomer composition is characterized by specific occurrence of 20, 22, and 24 carbon aliphatic chains, whereas cutin is mainly represented by common C16 and C18 aliphatic chains. This work depicts, for the first time in apple, the complex composition of suberin, cutin, waxes and triterpenes, and confirms the strong interplay between these epidermal polymers in apple fruit skin.

Fusion between fluid liposomes and intact bacteria: study of driving parameters and in vitro bactericidal efficacy

Background

Pseudomonas aeruginosa represents a good model of antibiotic resistance. These organisms have an outer membrane with a low level of permeability to drugs that is often combined with multidrug efflux pumps, enzymatic inactivation of the drug, or alteration of its molecular target. The acute and growing problem of antibiotic resistance of bacteria to conventional antibiotics made it imperative to develop new liposome formulations for antibiotics, and investigate the fusion between liposome and bacterium.

Methods

In this study, the factors involved in fluid liposome interaction with bacteria have been investigated. We also demonstrated a mechanism of fusion between liposomes (1,2-dipa lmitoyl-sn-glycero-3-phosphocholine [DPPC]/dimyristoylphosphatidylglycerol [DMPG] 9:1, mol/mol) in a fluid state, and intact bacterial cells, by lipid mixing assay.

Results

The observed fusion process is shown to be mainly dependent on several key factors. Perturbation of liposome fluidity by addition of cholesterol dramatically decreased the degree of fusion with P. aeruginosa from 44% to 5%. It was observed that fusion between fluid liposomes and bacteria and also the bactericidal activities were strongly dependent upon the properties of the bacteria themselves. The level of fusion detected when fluid liposomes were mixed with Escherichia coli (66%) or P. aeruginosa (44%) seems to be correlated to their outer membrane phosphatidylethanolamine (PE) phospholipids composition (91% and 71%, respectively). Divalent cations increased the degree of fusion in the sequence Fe²⁺ > Mg²⁺ > Ca²⁺ > Ba²⁺ whereas temperatures lower than the phase transition temperature of DPPC/DMPG (9:1) vesicles decreased their fusion capacity. Acidic as well as basic pHs conferred higher degrees of fusion (54% and 45%, respectively) when compared to neutral pH (35%).

Conclusion

Based on the results of this study, a possible mechanism involving cationic bridging between bacterial negatively charged lipopolysaccharide and fluid liposomes DMPG phospholipids was outlined. Furthermore, the fluid liposomal-encapsulated tobramycin was prepared, and the in vitro bactericidal effects were also investigated.

Lipid composition has significant effect on targeted drug delivery properties of NGR-modified liposomes

The Asn-Gly-Arg (NGR) motif has previously been demonstrated to specifically bind to CD13, which is selectively overexpressed in tumor vasculature and some tumor cells (e.g. HT1080). It was reported that NGR-modified stealth liposomes (NGR-SL) could be prepared with different lipid composition, such as 1,2-dipalmitoyl-sn-glycero-phosphatidylcholine (DPPC), hydrogenated soy posphatidylcholine (HSPC) and soy posphatidylcholine (SPC). In the present study, NGR-modified liposomes were prepared with DPPC, HSPC, SPC or the mixture of HSPC and SPC. The resultant liposomes with different lipid composition were compared in terms of cell uptake, antitumor efficacy and targeted drug delivery efficiency using HT1080 tumor model. It was found that NGR-SL composed of the mixture of HSPC and SPC was able to improve targeted drug delivery efficiency to tumor producing the most significant antitumor activity. Collectively, the NGR-modified liposomes composed of the mixture of HSPC and SPC are promising carriers for the treatment of tumor. Besides NGR ligand, lipid composition could also significantly affect the targeted delivery efficiency to the tumor.

Lipid Raft Size and Lipid Mobility in Non-raft Domains Increase during Aging and Are Exacerbated in APP/PS1 Mice Model of Alzheimer's Disease. Predictions from an Agent-Based Mathematical Model

A connection between lipid rafts and Alzheimer's disease has been studied during the last decades. Mathematical modeling approaches have recently been used to correlate the effects of lipid composition changes in the physicochemical properties of raft-like membranes. Here we propose an agent based model to assess the effect of lipid changes in lipid rafts on the evolution and progression of Alzheimer's disease using lipid profile data obtained in an established model of familial Alzheimer's disease. We have observed that lipid raft size and lipid mobility in non-raft domains are two main factors that increase during age and are accelerated in the transgenic Alzheimer's disease mouse model. The consequences of these changes are discussed in the context of neurotoxic amyloid β production. Our agent based model predicts that increasing sterols (mainly cholesterol) and long-chain polyunsaturated fatty acids (LCPUFA) (mainly DHA, docosahexaenoic acid) proportions in the membrane composition might delay the onset and progression of the disease.

Reduction of Influenza Virus Envelope's Fusogenicity by Viral Fusion Inhibitors

During cell entry of an enveloped virus, the viral membrane must be fused with the cellular membrane. The virus envelope has a unique structure consisting of viral proteins and a virus-specific lipid composition, whereas the host membrane has its own structure with host membrane proteins. Compound 136 was previously found to bind in close proximity to the viral envelope and inhibit influenza virus entry. We showed here that the 136-treated influenza virus still caused hemolysis. When liposomes were used as the target membrane for 136-treated viruses, aberrant fusion occurred; few liposomes fused per virion, and glycoproteins were not distributed evenly across fusion complexes. Additionally, large fusion aggregates did not form, and in some instances, neck-like structures were found. Based on previous results and hemolysis, fusion inhibition by 136 occurs post-scission but prior to lipid mixing.