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https://www.readbyqxmd.com/read/28325886/mouse-mitochondrial-lipid-composition-is-defined-by-age-in-brain-and-muscle
#1
Amelia K Pollard, Catharine A Ortori, Reinhard Stöger, David A Barrett, Lisa Chakrabarti
Functionality of the lipid rich mitochondrial organelle declines with increased age. Recent advances in lipidomic technologies allowed us to perform a global characterisation of lipid composition in two different tissue types and age ranges. Ultra-high performance liquid chromatography coupled with high resolution mass spectrometry was used to establish and compare mitochondrial lipidomes of brain and skeletal muscle from young (4-11 weeks old) and middle age (78 weeks old) healthy mice. In middle age the brain mitochondria had reduced levels of fatty acids, particularly polyunsaturated fatty acids, while skeletal muscle mitochondria had a decreased abundance of phosphatidylethanolamine, but a pronounced increase of triglyceride levels...
March 21, 2017: Aging
https://www.readbyqxmd.com/read/28323063/lipid-engineering-reveals-regulatory-roles-for-membrane-fluidity-in-yeast-flocculation-and-oxygen-limited-growth
#2
Daniel Degreif, Tristan de Rond, Adam Bertl, Jay D Keasling, Itay Budin
Cells modulate lipid metabolism in order to maintain membrane homeostasis. Here we use a metabolic engineering approach to manipulate the stoichiometry of fatty acid unsaturation, a regulator of cell membrane fluidity, in Saccharomyces cerevisiae. Unexpectedly, reduced lipid unsaturation triggered cell-cell adhesion (flocculation), a phenomenon characteristic of industrial yeast but uncommon in laboratory strains. We find that ER lipid saturation sensors induce expression of FLO1 - encoding a cell wall polysaccharide binding protein - independently of its canonical regulator...
March 16, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28321485/initial-autophagic-protection-switches-to-disruption-of-autophagic-flux-by-lysosomal-instability-during-cadmium-stress-accrual-in-renal-nrk-52e-cells
#3
W-K Lee, S Probst, M P Santoyo-Sánchez, W Al-Hamdani, I Diebels, J-K von Sivers, E Kerek, E J Prenner, F Thévenod
The renal proximal tubule (PT) is the major target of cadmium (Cd(2+)) toxicity where Cd(2+) causes stress and apoptosis. Autophagy is induced by cell stress, e.g., endoplasmic reticulum (ER) stress, and may contribute to cell survival or death. The role of autophagy in Cd(2+)-induced nephrotoxicity remains unsettled due to contradictory results and lack of evidence for autophagic machinery damage by Cd(2+). Cd(2+)-induced autophagy in rat kidney PT cell line NRK-52E and its role in cell death was investigated...
March 20, 2017: Archives of Toxicology
https://www.readbyqxmd.com/read/28320741/hypoxia-enhances-antibody-dependent-dengue-virus-infection
#4
Esther Shuyi Gan, Wei Fun Cheong, Kuan Rong Chan, Eugenia Ziying Ong, Xiaoran Chai, Hwee Cheng Tan, Sujoy Ghosh, Markus R Wenk, Eng Eong Ooi
Dengue virus (DENV) has been found to replicate in lymphoid organs such as the lymph nodes, spleen, and liver in post-mortem analysis. These organs are known to have low oxygen levels (~0.5-4.5% O2) due to the vascular anatomy. However, how physiologically low levels of oxygen affect DENV infection via hypoxia-induced changes in the immune response remains unknown. Here, we show that monocytes adapted to 3% O2 show greater susceptibility to antibody-dependent enhancement of DENV infection. Low oxygen level induces HIF1α-dependent upregulation of fragment crystallizable gamma receptor IIA (FcγRIIA) as well as HIF1α-independent alterations in membrane ether lipid concentrations...
March 20, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28319163/hopanoid-free-methylobacterium-extorquens-dm4-overproduces-carotenoids-and-has-widespread-growth-impairment
#5
Alexander S Bradley, Paige K Swanson, Emilie E L Muller, Françoise Bringel, Sean M Caroll, Ann Pearson, Stéphane Vuilleumier, Christopher J Marx
Hopanoids are sterol-like membrane lipids widely used as geochemical proxies for bacteria. Currently, the physiological role of hopanoids is not well understood, and this represents one of the major limitations in interpreting the significance of their presence in ancient or contemporary sediments. Previous analyses of mutants lacking hopanoids in a range of bacteria have revealed a range of phenotypes under normal growth conditions, but with most having at least an increased sensitivity to toxins and osmotic stress...
2017: PloS One
https://www.readbyqxmd.com/read/28317901/membrane-remodeling-by-the-m2-amphipathic-helix-drives-influenza-virus-membrane-scission
#6
Agnieszka Martyna, Basma Bahsoun, Matthew D Badham, Saipraveen Srinivasan, Mark J Howard, Jeremy S Rossman
Membrane scission is a crucial step in all budding processes, from endocytosis to viral budding. Many proteins have been associated with scission, though the underlying molecular details of how scission is accomplished often remain unknown. Here, we investigate the process of M2-mediated membrane scission during the budding of influenza viruses. Residues 50-61 of the viral M2 protein bind membrane and form an amphipathic α-helix (AH). Membrane binding requires hydrophobic interactions with the lipid tails but not charged interactions with the lipid headgroups...
March 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28301981/alterations-of-hepatocyte-function-with-free-radical-generators-and-reparation-or-prevention-with-coffee-polyphenols
#7
Amel Saidi Merzouk, Merzouk Hafida, Amel Medjdoub, Bouchra Loukidi, Sabri Cherrak, Sid Ahmed Merzouk, Mourad Elhabiri
Liver diseases are linked in the majority of cases to oxidative stress that antioxidants could neutralize with reducing liver injury. Chlorogenic acid, a coffee polyphenol, possesses antioxidant prosperities. The aim of this study was to evaluate in vitro preventive and corrective effects of cholorogenic acid in hepatocyte toxicity induced by free radicals. Hepatocytes were isolated from adult male Wistar rats. To determine corrective effects and reparation, cells were first exposed to two free radical generators (Hydrogen peroxide/Iron sulfate for hydroxyl radical formation, and Phenazine methosulfate/Nicotinamide adenine dinucleotide for superoxide anion formation) for 12H and thereafter treated by chlorogenic acid (1 and 10 µM final concentration) for another 12H...
March 16, 2017: Free Radical Research
https://www.readbyqxmd.com/read/28299707/functionalized-vesicles-by-microfluidic-device
#8
Derek Vallejo, Shih-Hui Lee, Abraham Lee
In recent years, lipid vesicles have become popular vehicles for the creation of biosensors. Vesicles can hold reaction components within a selective permeable membrane that provides an ideal environment for membrane protein biosensing elements. The lipid bilayer allows a protein to retain its native structure and function, and the membrane fluidity can allow for conformational changes and physiological interactions with target analytes. Here, we present two methods for the production of giant unilamellar vesicles (GUVs) within a microfluidic device that can be used as the basis for a biosensor...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28297642/interplay-between-endothelial-cell-cytoskeletal-rigidity-and-plasma-membrane-fluidity
#9
Gary J Blanchard, Julia V Busik
No abstract text is available yet for this article.
March 14, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28286737/pdgf-induced-fibroblast-growth-requires-monounsaturated-fatty-acid-production-by-stearoyl-coa-desaturase
#10
Alexandra Coomans de Brachène, Nicolas Dif, Audrey de Rocca Serra, Chloé Bonnineau, Amélie I Velghe, Yvan Larondelle, Donatienne Tyteca, Jean-Baptiste Demoulin
Stearoyl-coenzyme A desaturase (SCD) catalyzes the Δ9-cis desaturation of saturated fatty acids (SFA) to generate monounsaturated fatty acids (MUFA). This enzyme is highly up-regulated by platelet-derived growth factor (PDGF) in human fibroblasts. Accordingly, the analysis of cellular fatty acids by gas chromatography showed that PDGF significantly increased the proportion of MUFA, particularly palmitoleate, in cellular lipids. To further analyze the role of SCD in fibroblasts, we used small hairpin RNA targeting SCD (shSCD), which decreased the MUFA content...
March 2017: FEBS Open Bio
https://www.readbyqxmd.com/read/28276520/antimicrobial-peptide-cwfw-kills-by-combining-lipid-phase-separation-with-autolysis
#11
Kathi Scheinpflug, Michaela Wenzel, Oxana Krylova, Julia E Bandow, Margitta Dathe, Henrik Strahl
The synthetic cyclic hexapeptide cWFW (cyclo(RRRWFW)) has a rapid bactericidal activity against both Gram-positive and Gram-negative bacteria. Its detailed mode of action has, however, remained elusive. In contrast to most antimicrobial peptides, cWFW neither permeabilizes the membrane nor translocates to the cytoplasm. Using a combination of proteome analysis, fluorescence microscopy, and membrane analysis we show that cWFW instead triggers a rapid reduction of membrane fluidity both in live Bacillus subtilis cells and in model membranes...
March 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28276191/deleting-the-dag-kinase-dgk1-augments-yeast-vacuole-fusion-through-increased-ypt7-activity-and-altered-membrane-fluidity
#12
Gregory E Miner, Matthew L Starr, Logan R Hurst, Rutilio A Fratti
Diacylglycerol (DAG) is a fusogenic lipid that can be produced through phospholipase C activity on phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2 ], or through phosphatidic acid (PA) phosphatase activity. The fusion of Saccharomyces cerevisiae vacuoles requires DAG, PA and PI(4,5)P2 , and the production of these lipids is thought to provide temporally specific stoichiometries that are critical for each stage of fusion. Furthermore, DAG and PA can be interconverted by the DAG kinase Dgk1 and the PA phosphatase Pah1...
March 9, 2017: Traffic
https://www.readbyqxmd.com/read/28272888/preferential-adsorption-of-l-histidine-onto-dopc-sphingomyelin-3%C3%A3-n-n-n-dimethylaminoethane-carbamoyl-cholesterol-liposomes-in-the-presence-of-chiral-organic-acids
#13
Keishi Suga, Atsushi Tauchi, Takaaki Ishigami, Yukihiro Okamoto, Hiroshi Umakoshi
We investigated the effect of organic acids such as mandelic acid (MA) and tartaric acid (TA) on the adsorption behavior of both histidine (His) and propranolol (PPL) onto liposomes. A cationic and heterogeneous liposome prepared using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/sphingomyelin (SM)/3β-{N-[(N',N'-dimethylamino)ethyl]carbamoyl}cholesterol (DC-Ch) in a ratio of (4/3/3) showed the highest adsorption efficiency of MA and TA independent of chirality, while neutral liposome DOPC/SM/cholesterol = (4/3/3) showed low efficiency...
March 8, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28263610/correlating-membrane-morphological-responses-with-micellar-aggregation-behavior-of-capric-acid-and-monocaprin
#14
Bo Kyeong Yoon, Joshua A Jackman, Min Chul Kim, Tun Naw Sut, Nam-Joon Cho
The interaction of single-chain lipid amphiphiles with phospholipid membranes is relevant to many scientific fields, including molecular evolution, medicine, and biofuels. Two widely studied compounds within this class are the medium-chain saturated fatty acid, capric acid, and its monoglyceride derivative, monocaprin. To date, most studies about these compounds have involved in vitro evaluation of their biological activities, while mechanistic details of how capric acid and monocaprin interact with phospholipid bilayers remain elusive...
March 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28263102/effect-of-primycin-on-growth-arrested-cultures-and-cell-integrity-of-staphylococcus-aureus
#15
Péter Feiszt, György Schneider, Levente Emődy
Bactericidal effect against non-dividing bacteria is a very advantageous, but rare characteristic among antimicrobial agents, mostly possessed by those affecting the cell membrane. These kinds of agents can kill bacterial cells without lysis. We assessed these characteristics on primycin, a topical anti-staphylococcal agent highly effective against prevalent multiresistant strains, as it also acts on the cell membrane. In time-kill studies, primycin preserved its bactericidal activity against growth-arrested Staphylococcus aureus cultures...
March 6, 2017: Acta Microbiologica et Immunologica Hungarica
https://www.readbyqxmd.com/read/28250315/a-preferable-method-for-the-formation-of-vesicles-from-lamellar-liquid-crystals-using-chemical-additives
#16
Yasutaka Enomoto, Yoko Imai, Kazuo Tajima
We present a method for vesicle formation from lamellar liquid crystals (LCs) using a cationic amphiphilic substance, namely 2-hydroxyethyl di(alkanol)oxyethyl methylammonium methylsulfate (DEAE). Vesicle formation from the DEAE lamellar dispersion occurred via a two-step chemical addition. This method required neither additional mechanical energy nor the use of special solvents. The transition was solubilized using an organic substance (e.g., limonene) in the lamellar DEAE LC, after which, a small amount of inorganic salt was added to the solubilized lamellar LC dispersion with gentle stirring...
2017: Journal of Oleo Science
https://www.readbyqxmd.com/read/28250108/the-sphingosine-rheostat-is-involved-in-the-cnidarian-heat-stress-response-but-not-necessarily-in-bleaching
#17
Sheila A Kitchen, Virginia M Weis
Sphingolipids play important roles in mitigating cellular heat and oxidative stress by altering membrane fluidity, receptor clustering and gene expression. Accumulation of signaling sphingolipids that comprise the sphingosine rheostat, pro-apoptotic sphingosine (Sph) and pro-survival sphingosine-1-phosphate (S1P), is key to determining cell fate. Reef-building corals and other symbiotic cnidarians living in shallow tropical waters can experience elevated seawater temperature and high UV irradiance, two stressors that are increasing in frequency and severity with climate change...
February 22, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28229140/partitioning-of-caffeine-in-lipid-bilayers-reduces-membrane-fluidity-and-increases-membrane-thickness
#18
Adree Khondker, Alexander Dhaliwal, Richard J Alsop, Jennifer Tang, Matilda Backholm, An-Chang Shi, Maikel C Rheinstädter
Caffeine is a small amphiphilic molecule, which is widely consumed as a stimulant to prevent fatigue, but is also used as a common drug adjuvant in modern medicine. Here, we show that caffeine interacts with unsaturated lipid membranes made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). By combining X-ray diffraction and molecular dynamics simulations, we present evidence that caffeine partitions in lipid membranes and locates at the head group-tail group interface of the bilayers. By attracting water molecules from neighboring lipid molecules, it leads to the formation of "water pockets", i...
February 23, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28224174/spectroscopic-polarographic-and-microcalorimetric-studies-on-mitochondrial-dysfunction-induced-by-ethanol
#19
Long Ma, Jia-Xin Dong, Can Wu, Xue-Yi Li, Jing Chen, Hong Zhang, Yi Liu
Liver mitochondria are involved in several important life processes; mitochondrial dysfunction and disorders are implicated in several human diseases. Alcohol permeates all tissues of the body and exerts some intrinsic hepatotoxicity. In this work, our results demonstrated that ethanol caused a series of mitochondria permeability transition pore (MPTP) opening factors such as mitochondrial swelling, increased permeability of H(+) and K(+), collapsed membrane potential, and increased membrane fluidity. Furthermore, mitochondrial ultrastructure alternation observed clearly by transmission electron microscopy and the release of Cytochrome c could explain the MPTP opening from another aspect...
February 21, 2017: Journal of Membrane Biology
https://www.readbyqxmd.com/read/28219008/nanoroughness-strongly-impacts-lipid-mobility-in-supported-membranes
#20
Florence Blachon, Frédéric Harb, Bogdan Munteanu, Agnès Piednoir, Rémy Fulcrand, Thierry Charitat, Giovanna Fragneto, Olivier Pierre-Louis, Bernard Tinland, Jean-Paul Rieu
In vivo lipid membranes interact with rough supramolecular structures such as protein clusters and fibrils. How these features whose size ranges from a few nanometers to a few tens of nanometers impact lipid and protein mobility is still being investigated. Here, we study supported phospholipid bilayers, a unique biomimetic model, deposited on etched surfaces bearing nanometric corrugations. The surface roughness and mean curvature are carefully characterized by AFM imaging using ultrasharp tips. Neutron specular reflectivity supplements this surface characterization and indicates that the bilayers follow the large-scale corrugations of the substrate...
February 24, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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