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membrane fluidity

Elisabet Navarro-Tapia, Amparo Querol, Roberto Pérez-Torrado
The toxic effect of ethanol is one of the most important handicaps for many biotechnological applications of yeasts, such as bioethanol production. Elucidation of ethanol stress response will help to improve yeast performance in biotechnological processes. In the yeast Saccharomyces cerevisiae, ethanol stress has been recently described as an activator of the unfolded protein response (UPR), a conserved intracellular signalling pathway that regulates the transcription of ER homoeostasis-related genes. However, the signal and activation mechanism has not yet been unravelled...
February 22, 2018: Microbial Biotechnology
Yik Ling Chew, Adlina Maisarah Mahadi, Kak Ming Wong, Joo Kheng Goh
BACKGROUND: Bauhinia kockiana originates from Peninsular Malaysia and it is grown as a garden ornamental plant. Our previous study reported that this plant exhibited fairly strong antioxidant and antimicrobial activities. This paper focused on the assessment of the antibacterial activity of B. kockiana towards methicillin-resistance Staphylococcus aureus (MRSA), to purify and to identify the antibacterial compounds, and to determine the mechanism of antibacterial activity. METHODS: Antibacterial activity of B...
February 20, 2018: BMC Complementary and Alternative Medicine
Koji Mikami, Meiko Ito, Kensuke Taya, Ikuya Kishimoto, Takuya Kobayashi, Yutaka Itabashi, Ryusuke Tanaka
In the filamentous brown alga Ectocarpus siliculosus, male and female sex is expressed during the haploid parthenosporophyte phase of the life cycle. Here, we found that male parthenosporophytes displayed thermotolerance whereas female specimens displayed severely reduced viability at 25 °C and 28 °C. Profiling of polyunsaturated fatty acids showed that n-3 and n-6 were the predominant species in male and female parthenosporophytes, respectively, and that the n-3/n-6 fatty acid ratio was not affected by a temperature change...
February 10, 2018: Marine Environmental Research
Rola Abboud, Catherine Charcosset, Hélène Greige-Gerges
Human steroid hormones are involved in many aspects of physiology and have long been known to exert rapid and delayed effects. They are lipophilic molecules which can be incorporated into the lipid membranes. Through non-covalent interactions they can alter the properties of the membrane, including fluidity, lipid raft formation and others. In this review, different biophysical techniques were described to study the interaction of human steroid hormones with biological and biomimetic membranes such as differential scanning calorimetry, electron paramagnetic resonance, fluorescence spectroscopy and Fourier transform infrared spectroscopy...
February 13, 2018: Biochimie
Dennapa Saeloh, Varomyalin Tipmanee, Kin Ki Jim, Marien P Dekker, Wilbert Bitter, Supayang P Voravuthikunchai, Michaela Wenzel, Leendert W Hamoen
The acylphloroglucinol rhodomyrtone is a promising new antibiotic isolated from the rose myrtle Rhodomyrtus tomentosa, a plant used in Asian traditional medicine. While many studies have demonstrated its antibacterial potential in a variety of clinical applications, very little is known about the mechanism of action of rhodomyrtone. Preceding studies have been focused on intracellular targets, but no specific intracellular protein could be confirmed as main target. Using live cell, high-resolution, and electron microscopy we demonstrate that rhodomyrtone causes large membrane invaginations with a dramatic increase in fluidity, which attract a broad range of membrane proteins...
February 16, 2018: PLoS Pathogens
Tsz Wai Ng, Wing Lam Chan, Ka Man Lai
Finding ways to predict and control the survival of bacterial aerosols can contribute to the development of ways to alleviate a number of crucial microbiological problems. Significant damage in the membrane integrity of Escherichia coli during aerosolization and airborne suspension has been revealed which has prompted the question of how the membrane fatty acid composition and fluidity influence the survival of airborne bacteria. Two approaches of using isogenic mutants and different growth temperatures were selected to manipulate the membrane fatty acid composition of E...
February 15, 2018: Applied Microbiology and Biotechnology
Fumihiko Iwasaki, Keishi Suga, Yukihiro Okamoto, Hiroshi Umakoshi
Vesicles prepared by synthetic surfactant, DDAB (dilauryldimethylammonium bromide), were modified with cholesterol and their membrane surface properties of the vesicle were characterized through the analyses of fluorescent probes, such as Laurdan (6-lauroyl-2-dimethylaminonaphthalene) and DPH (1,6-diphenyl-1,3,5-hexatriene). The self-assembly of DDAB with cholesterol showed stable vesicle structure with a mean diameter of 127 nm through the dynamic light scattering analysis. While the DDAB vesicle showed high polarity and high fluidity, the modification of the DDAB vesicle with cholesterol lead to the formation of "heterogeneous phase" on the vesicle membrane...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Michelle J Chua, Richard L Campen, Lindsay Wahl, Joseph J Grzymski, Jill A Mikucki
Antarctic subice environments are diverse, underexplored microbial habitats. Here we describe the ecophysiology and annotated genome of a Marinobacter strain isolated from a cold, saline, iron-rich subglacial outflow of the Taylor Glacier, Antarctica. This strain (BF04_CF4) grows fastest at neutral pH (range 6-10), is psychrophilic (range: 0-20°C), moderately halophilic (range: 0.8-15% NaCl), and hosts genes encoding potential low temperature and high salt adaptations. The predicted proteome suggests it utilizes fewer charged amino acids than a mesophilic Marinobacter strain...
February 10, 2018: FEMS Microbiology Ecology
Rania K Eid, Ebtessam A Essa, Gamal M El Maghraby
The fluidity of vesicular membrane affects vesicular transdermal drug delivery. Essential oils can be located in vesicular membrane imparting flexibility and influencing transdermal delivery. Accordingly, the objective was to investigate the effect of incorporation of essential oils in niosomes on felodipine transdermal delivery. Rigid niosomes comprising Span 60 with cholesterol (2:1, w/w) were used with clove, eucalyptus or lemon oils being incorporated in the vesicles at increasing concentrations. The vesicle size and shape was monitored using scanning electron microscopy...
February 14, 2018: Pharmaceutical Development and Technology
Yulan Shi, Xiule Yue, Lizhe An
Ω-3 fatty acid desaturases (FADs) are thought to contribute to plant stress tolerance mainly through the C18:3-induced membrane stabilization, but the comprehensive analysis of their roles in stress adaptation is lacking. Here, we isolated a microsomal ω-3 FAD gene (CbFAD3) from a cryophyte (Chorispora bungeana), and elucidated its functions in stress tolerance. CbFAD3, exhibiting highest identity to Arabidopsis AtFAD3, was up-regulated by abiotic stresses. Its functionality was verified by heterogonous expression in yeast...
February 8, 2018: Journal of Experimental Botany
Kathryn Del Vecchio, Robert V Stahelin
Lipid biosensors are robust tools used in both in vitro and in vivo applications of lipid imaging and lipid detection. Lactadherin C2 (LactC2) was described in 2000 as being a potent and specific sensor for phosphatidylserine (PS) (Andersen et al. Biochemistry 39:6200-6206, 2000). PS is an anionic phospholipid enriched in the inner leaflet of the plasma membrane and has paramount roles in apoptosis, cells signaling, and autophagy. The myriad roles PS plays in membrane dynamics make monitoring PS levels and function an important endeavor...
February 10, 2018: Journal of Bioenergetics and Biomembranes
Mustafa Al-Saiedy, Ryan Pratt, Patrick Lai, Evan Kerek, Heidi Joyce, Elmar Prenner, Francis Green, Chang-Chun Ling, Ruud Veldhuizen, Salim Ghandorah, Matthias Amrein
Pulmonary surfactant forms a cohesive film at the alveolar air-lung interface, lowering surface tension, and thus reducing the work of breathing and preventing atelectasis. Surfactant function becomes impaired during inflammation due to degradation of the surfactant lipids and proteins by free radicals. In this study, we examine the role of reactive nitrogen (RNS) and oxygen (ROS) species on surfactant function with and without physiological cholesterol levels (5-10%). Surface activity was assessed in vitro in a captive bubble surfactometer (CBS)...
February 2, 2018: Biochimica et Biophysica Acta
Costanza Montis, Viola Generini, Giulia Boccalini, Paolo Bergese, Daniele Bani, Debora Berti
Understanding the interaction between nanomaterials and biological interfaces is a key unmet goal that still hampers clinical translation of nanomedicine. Here we investigate and compare non-specific interaction of gold nanoparticles (AuNPs) with synthetic lipid and wild type macrophage membranes. A comprehensive data set was generated by systematically varying the structural and physicochemical properties of the AuNPs (size, shape, charge, surface functionalization) and of the synthetic membranes (composition, fluidity, bending properties and surface charge), which allowed to unveil the matching conditions for the interaction of the AuNPs with macrophage plasma membranes in vitro...
January 27, 2018: Journal of Colloid and Interface Science
Mohsen Sadeghi, Thomas R Weikl, Frank Noé
We present a simple and computationally efficient coarse-grained and solvent-free model for simulating lipid bilayer membranes. In order to be used in concert with particle-based reaction-diffusion simulations, the model is purely based on interacting and reacting particles, each representing a coarse patch of a lipid monolayer. Particle interactions include nearest-neighbor bond-stretching and angle-bending and are parameterized so as to reproduce the local membrane mechanics given by the Helfrich energy density over a range of relevant curvatures...
January 28, 2018: Journal of Chemical Physics
Jung Ho Ahn, Jong An Lee, Junho Bang, Sang Yup Lee
Engineering of microorganisms to produce desired bio-products with high titer, yield, and productivity is often limited by product toxicity. This is also true for succinic acid (SA), a four carbon dicarboxylic acid of industrial importance. Acid products often cause product toxicity to cells through several different factors, membrane damage being one of the primary factors. In this study, cis-trans isomerase from Pseudomonas aeruginosa was expressed in Mannheimia succiniciproducens to produce trans-unsaturated fatty acid (TUFA) and to reinforce the cell membrane of M...
January 29, 2018: Journal of Industrial Microbiology & Biotechnology
Nilanjan Dey, Santanu Bhattacharya
Easily synthesizable amphiphilic probes have been designed for the detection of Al3+ exclusively at mesoscopic interfaces. The surface charge of the surfactant assemblies and the fluidity of the lipid aggregates show pronounced effects on the extent of Al3+ detection. Excellent sensitivity has been observed specifically in the presence of anionic surfactants and the lipid membranes with more sol-like characteristics. Moreover, a variation in the modes of Al3+ complexation is observed on shifting from one regioisomer to another...
January 26, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Bernardo Duarte, Ana Rita Matos, João Carlos Marques, Isabel Caçador
Spartina patens is a highly dispersed halophytic grass invader in Mediterranean marshes. It is also characterized by having a high degree of resistance to salinity, one of the main drivers of plant zonation in salt marshes. Nevertheless, the physiological basis behind the extreme resistance of S. patens requires more detailed studies. In the present work, we aimed to study how membrane fatty acid remodeling could contribute to the resistance of this plant to salt. Spartina patens individuals exposed to increasing levels of salinity and its leaf fatty acid profile under lipid peroxidation products evaluated under all tested concentrations...
January 12, 2018: Plant Physiology and Biochemistry: PPB
Fabien Riols, Justine Bertrand-Michel
Oxysterols are oxygenated derivatives of cholesterol formed in the human body or ingested in the diet. By modulating the activity of many proteins (for instance, liver X receptors, oxysterol-binding proteins, some ATP-binding cassette transporters), oxysterols can affect many cellular functions and influence various physiological processes (e.g., cholesterol metabolism, membrane fluidity regulation, intracellular signaling pathways). Due to their crucial role, it is important to be able to quantify them in pathological conditions...
2018: Methods in Molecular Biology
Samuel C R Sherratt, R Preston Mason
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) differentially influence lipid oxidation, signal transduction, fluidity, and cholesterol domain formation, potentially due in part to distinct membrane interactions. We used small angle x-ray diffraction to evaluate the EPA and DHA effects on membrane structure. Membrane vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and cholesterol (C) (0.3C:POPC mole ratio) were prepared and treated with vehicle, EPA, or DHA (1:10 mole ratio to POPC)...
January 17, 2018: Chemistry and Physics of Lipids
Brendan J Houston, Brett Nixon, Jacinta H Martin, Geoffry N D E Iuliis, Elizabeth G Bromfield, Kristen E McEwen, R John Aitkena
The reproductive consequences of global warming are not currently understood. In order to address this issue we have examined the reproductive consequences of exposing male mice to a mild heat stress. For this purpose, adult male mice were exposed to an elevated ambient temperature of 35°C under two exposure models. The first involved acute exposure for 24 hours, followed by recovery periods of between 1 day and 6 weeks. The alternative heating regimen involved a daily exposure of 8 hours for periods of 1 or 2 weeks...
January 17, 2018: Biology of Reproduction
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