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The nutritional value of meat is an increasingly important factor influencing consumer preferences for poultry, red meat and processed meat products. Intramuscular fat content and composition, in addition to high quality protein, trace minerals and vitamins are important determinants of nutritional value. Fat content of meat at retail has decreased substantially over the past 40 years through advances in animal genetics, nutrition and management and changes in processing techniques. Evidence of the association between diet and the incidence of human non-communicable diseases has driven an interest in developing production systems for lowering total SFA and trans fatty acid (TFA) content and enrichment of n-3 PUFA concentrations in meat and meat products. Typically, poultry and pork has a lower fat content, containing higher PUFA and lower TFA concentrations than lamb or beef. Animal genetics, nutrition and maturity, coupled with their rumen microbiome, are the main factors influencing tissue lipid content and relative proportions of SFA, MUFA and PUFA. Altering the fatty acid (FA) profile of lamb and beef is determined to a large extent by extensive plant and microbial lipolysis and subsequent microbial biohydrogenation of dietary lipid in the rumen, and one of the major reasons explaining the differences in lipid composition of meat from monogastrics and ruminants. Nutritional strategies can be used to align the fat content and FA composition of poultry, pork, lamb and beef with Public Health Guidelines for lowering the social and economic burden of chronic disease.

Background/Objectives: Gramicidin S (GS) is a cyclic antimicrobial peptide with strong antibacterial activity but significant cytotoxicity toward mammalian cells. This study evaluated GS-induced cytotoxicity in L929 fibroblast cells using both traditional 2D monolayer cultures and more physiologically relevant 3D spheroid models, and assessed whether liposomal encapsulation could mitigate toxicity and improve biocompatibility. Methods: L929 cells were cultured in monolayers and spheroids and treated with free GS or GS encapsulated in liposomes of varying lipid compositions. Cell viability and morphology were evaluated after 24 h of exposure using standard cytotoxicity assays. Results: Control liposomes, regardless of tested lipid type or concentration, showed no adverse effects on cell morphology or viability. Free GS caused pronounced, dose-dependent cytotoxicity in monolayers, decreasing viability to 11.0 ± 1.9% and 0.5 ± 1.1% at 50 and 75 µg/mL, respectively. By contrast, encapsulation in liposomes significantly reduced toxicity (p < 0.05), preserving 80.3–82.2% viability at 75 µg/mL depending on formulation, corresponding to protection factors exceeding 160-fold (80.3% vs. 0.5%). Spheroid cultures showed slightly higher resistance to GS; free GS reduced viability to 2.9%, while liposomal GS preserved it above 84.8%, depending on lipid composition. Conclusions: Liposomal encapsulation effectively reduces GS-induced cytotoxicity, likely by limiting direct membrane disruption. Moreover, spheroid models provide a more physiologically relevant and predictive platform for toxicity testing, while the results support nanoliposomes as a practical delivery strategy to enhance the safety of antimicrobial peptides during preclinical development.

The article provides a comprehensive overview of biological membrane lipid composition and distribution and ion transport processes, focusing particularly on red blood cells (RBCs). It begins with a historical perspective, detailing the introduction of the terms ‘cell’ and ‘membrane’ in biological sciences, and the development of the fluid-mosaic model of membrane structure. Early findings on ion transport highlighted the non-equilibrium distribution of Na+ and K+ across cell membranes, leading to the discovery of the Na+/K+ pump. The article delves into the lipid composition of RBC membranes, emphasising the roles of various lipids, including cardiolipin, and the concept of lipid rafts. These rafts, enriched with sphingolipids and cholesterol, play crucial roles in cellular processes. Variations in RBC shapes are discussed, with biophysical theories explaining transformations and pathological conditions affecting RBC morphology, such as sickle cell anaemia. Na+ and K+ transporters in RBC membranes are explored, highlighting the almost ubiquitous presence of the Na+/K+ pump (absent in Carnivora RBCs) and various ion channels, including the Gárdos and Piezo1 channels. The article notes species-specific differences in ion transport mechanisms and the activation or suppression of transporters during RBC maturation. The mechanism of residual ion transport is examined, questioning whether a Na+(K+)/H+ antiporter exists in the human RBC membrane. Residual ion fluxes are mediated by this antiporter, influenced by the fatty acid composition of the RBC membrane. The outlook section underscores the need for further research to fully understand the complexities of RBC membrane structure and function, suggesting that many questions remain unanswered despite significant advances.

Alkenones are long-chain methyl/ethyl ketones (mainly in length of C37-C39) with two to four trans-unsaturated bonds produced by several kinds of marine haptophytes such as Emiliania huxleyi (coccolithophore). The physiological functions and metabolic profile of alkenones are not well known yet. In this study, we focused on elucidating how alkenones contribute to energy storage and cellular carbon partitioning in relation to other cellular components. For the purpose, we analyzed the changes in carbon allocation among various cell components like lipids, alkenones, proteins, and polysaccharides between cells exposed to N-sufficient (+N) and N-limited conditions (−N) in E. huxleyi CCMP 2090. Finally, the alkenones were found to function as main storage lipids and their accumulation was clearly increased by −N, whereas triacylglycerols (TAGs) were barely detected under any N conditions. The mobilization of carbons into alkenones was stimulated by −N from 15% under +N to 27% under −N. However, photosynthetic C allocation into other components was suppressed by −N, showing that percent C allocation into fatty acids, proteins, and polysaccharides was decreased from 9, 46, and 6.8% under +N to 7, 25, and 4.5% under −N, respectively. In addition, fatty acids such as 16:0, 18:0, 18:1, and 18:2 became dominant under −N while 18:5 became dominant under +N conditions, with no significant change in 22:6. This study revealed that alkenones function as primary carbon storage pools especially under −N condition in E. huxleyi CCMP 2090 and that N supply triggers a dynamic change in carbon metabolism by modifying membrane lipid composition and regulating carbon allocation preferences.

Rapid urbanization threatens soil biodiversity and ecosystem functions, but the structural and physiological adaptations of soil microorganisms to urbanization remain unclear. We examined variations in soil microbial biomass, community structure and membrane lipid composition along an urban–suburban–exurban gradient in Guangzhou, China, using phospholipid fatty acid analysis. Samples were collected from four to five quadrats per site at three depths during dry and wet seasons. PERMANOVA revealed that both the urbanization gradient and the soil depth significantly shaped microbial communities. Depth was the strongest driver, explaining 45.5% of the variance in total microbial biomass, while site explained 27.2%. Microbial biomass decreased from exurban to urban sites and from surface to deep soils. Concurrently, the ratios of fungi/bacteria and Gram-positive/Gram-negative bacteria increased in urban areas and deeper soils. Physiologically, the membrane lipids shifted toward more saturated fatty acids in urban and surface soils, while unsaturated fatty acids predominated in exurban and deeper layers. These shifts in microbial community structure and membrane lipid composition were strongly correlated with key soil properties, including soil organic carbon, total nitrogen, and bulk density. The findings demonstrate urbanization diminishes microbial biomass and triggers adaptive microbial responses, providing a scientific basis for the sustainable management of urban forests.

The outer mitochondrial membrane (OMM) is involved in multiple cellular functions such as apoptosis, inflammation and signaling via its membrane-associated and -embedded proteins. Despite the central role of the OMM in these vital phenomena, the structure and dynamics of the membrane have regularly been investigated in silico using simple two-component models. Accordingly, the aim was to generate the realistic multi-component model of the OMM and inspect its properties using atomistic molecular dynamics (MD) simulations. All major lipid components, phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS), were included in the probed OMM models. Because increased levels of anionic PS lipids have potential effects on schizophrenia and, more specifically, on monoamine oxidase B enzyme activity, the effect of varying the PS concentration was explored. The MD simulations indicate that the complex membrane lipid composition (MLC) behavior is notably different from the two-component PC-PE model. The MLC changes caused relatively minor effects on the membrane structural properties such as membrane thickness or area per lipid; however, notable effects could be seen with the dynamical parameters at the water-membrane interface. Increase of PS levels appears to slow down lateral diffusion of all lipids and, in general, the presence of anionic lipids reduced hydration and slowed down the PE headgroup rotation. In addition, sodium ions could neutralize the membrane surface, when PI was the main anionic component; however, a similar effect was not seen for high PS levels. Based on these results, it is advisable for future studies on the OMM and its protein or ligand partners, especially when wanting to replicate the correct properties on the water-membrane interface, to use models that are sufficiently complex, containing anionic lipid types, PI in particular.

Background The Laminaria digitata is an abundant macroalga and a sustainable feedstock for poultry nutrition. L. digitata is a good source of essential amino acids, carbohydrates and vitamins, including A, D, E, and K, as well as triacylglycerols and minerals, in particular iron and calcium. However, the few studies available in the literature with broilers document the application of this macroalga as a dietary supplement rather than a feed ingredient. No study has addressed up until now the effects of a high-level incorporation (> 2% in the diet) of L. digitata on plasma biochemical markers and hepatic lipid composition, as well as minerals and pigments profile in the liver of broilers. Our experimental design included one hundred and twenty Ross 308 male birds contained in 40 wired-floor cages and distributed to the following diets at 22 days of age ( n  = 10) for 15 days: 1) a corn-soybean basal diet (Control); 2) the basal diet plus 15% of L. digitata (LA); 3) the basal diet plus 15% of L. digitata with 0.005% of Rovabio® Excel AP (LAR); and 4) the basal diet plus 15% of L. digitata with 0.01% of the recombinant CAZyme, alginate lyase (LAE). Results L. digitata compromised birds’ growth performance by causing a reduction in final body weight. It was found an increase in hepatic n -3 and n -6 fatty acids, in particular C18:2 n -6, C18:3 n -6, C20:4 n -6, C20:5 n -3, C22:5 n -3 and C22:6 n -3 with the addition of the macroalga, with or without feed enzymes, to the broiler diets. Also, the beneficial C18:3 n -3 fatty acid was increased by combining L. digitata and commercial Rovabio® Excel AP compared to the control diet. The sum of SFA, MUFA and the n -6 /n -3 PUFA ratio were decreased by L. digitata , regardless the addition of exogenous enzymes. β-carotene was enhanced by L. digitata , individually or combined with CAZymes, being also responsible for a positive increase in total pigments. Macrominerals, in particular phosphorous and sulphur, were increased in the liver of broilers fed L. digitata individually relative to the control. For microminerals, copper, iron and the correspondent sum were consistently elevated in the liver of broilers fed L. digitata , individually or combined with exogenous CAZymes. The powerful discriminant analysis tool based on the hepatic characterization revealed a good separation between the control group and L. digitata diets but failed to discriminate the addition of feed enzymes. Conclusions Overall, this study highlights the value of L. digitata as a feed ingredient for the poultry industry. Moreover, we can conclude that the effect of L. digitata overpowers the effect of feed enzymes, both the Rovabio® Excel AP and the alginate lyase. Having in mind the negative effects observed on birds’ performance, our main recommendation at this stage is to restraint L. digitata incorporation level in forthcoming nutritional studies.

Aims/hypothesisIntramyocellular lipid (IMCL) content associates with development of insulin resistance, albeit not in insulin-sensitive endurance-trained athletes (trained). Qualitative and spatial differences in muscle lipid composition may underlie this so-called athlete’s paradox. Here we studied triacylglycerol (TAG) composition of individual myocellular lipid droplets (LDs) in trained individuals and individuals with type 2 diabetes mellitus.MethodsTrained (V̇O2max 71.0 ± 1.6 ml O2 [kg lean body mass (LBM)]−1 min−1), normoglycaemic (fasting glucose 5.1 ± 0.1 mmol/l) individuals and untrained (V̇O2max 36.8 ± 1.5 ml O2 [kg LBM]−1 min−1) individuals with type 2 diabetes (fasting glucose 7.4 ± 0.5 mmol/l), with similar IMCL content (3.5 ± 0.7% vs 2.5 ± 0.3%, p = 0.241), but at opposite ends of the insulin sensitivity spectrum (glucose infusion rate 93.8 ± 6.6 vs 25.7 ± 5.3 μmol [kg LBM]−1 min−1 for trained individuals and those with type 2 diabetes, respectively) were included from our database in the present study. We applied in situ label-free broadband coherent anti-Stokes Raman scattering (CARS) microscopy to sections from skeletal muscle biopsies to measure TAG acyl chain length and saturation of myocellular LDs. This approach uniquely permits examination of individual LDs in their native environment, in a fibre-type-specific manner, taking into account LD size and subcellular location.ResultsDespite a significant difference in insulin sensitivity, we observed remarkably similar acyl chain length and saturation in trained and type 2 diabetic individuals (chain length: 18.12 ± 0.61 vs 18.36 ± 0.43 number of carbons; saturation: 0.37 ± 0.05 vs 0.38 ± 0.06 number of C=C bonds). Longer acyl chains or higher saturation (lower C=C number) could be detected in subpopulations of LDs, i.e. large LDs (chain length: 18.11 ± 0.48 vs 18.63 ± 0.57 carbon number) and subsarcolemmal LDs (saturation: 0.34 ± 0.02 vs 0.36 ± 0.04 C=C number), which are more abundant in individuals with type 2 diabetes.Conclusions/interpretationIn contrast to reports of profound differences in the lipid composition of lipids extracted from skeletal muscle from trained and type 2 diabetic individuals, our in situ, LD-specific approach detected only modest differences in TAG composition in LD subpopulations, which were dependent on LD size and subcellular location. If, and to what extent, these modest differences can impact insulin sensitivity remains to be elucidated.

Toll like receptors (TLRs) are an important and evolutionary conserved class of pattern recognition receptors associated with innate immunity. The recognition of Gram-positive cell wall constituents strongly depends on TLR2. In order to be functional, TLR2 predominantly forms a heterodimer with TLR1 or TLR6 within specialized membrane microdomains, the lipid rafts. The membrane lipid composition and the physicochemical properties of lipid rafts are subject to modification by exogenous fatty acids. Previous investigations of our group provide evidence that macrophage enrichment with polyunsaturated fatty acids (PUFA) induces a reordering of lipid rafts and non-rafts based on the incorporation of supplemented PUFA as well as their elongation and desaturation products. In the present study we investigated potential constraining effects of membrane microdomain reorganization on the clustering of TLR2 with its co-receptors TLR1 and TLR6 within lipid rafts. To this end, RAW264.7 macrophages were supplemented with either docosahexaenoic acid (DHA) or arachidonic acid (AA) and analyzed for receptor expression and microdomain localization in context of TLR stimulation. Our analyses showed that receptor levels and microdomain localization were unchanged by PUFA supplementation. The TLR2 pathway, in contrast to the TLR4 signaling cascade, is not affected by exogenous PUFA at the membrane level.

Cellular membranes are formed from a chemically diverse set of lipids present in various amounts and proportions. A high lipid diversity is universal in eukaryotes and is seen from the scale of a membrane leaflet to that of a whole organism, highlighting its importance and suggesting that membrane lipids fulfil many functions. Indeed, alterations of membrane lipid homeostasis are linked to various diseases. While many of their functions remain unknown, interdisciplinary approaches have begun to reveal novel functions of lipids and their interactions. We are beginning to understand why even small changes in lipid structures and in composition can have profound effects on crucial biological functions.