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membrane fluidity

Alvaro Toledo, Zhen Huang, Jorge L Benach, Erwin London
Lipid rafts are membrane microdomains that are involved in cellular processes such as protein trafficking and signaling processes, and which play a fundamental role in membrane fluidity and budding. The lipid composition of the membrane and the biochemical characteristics of the lipids found within rafts define the ability of cells to form microdomains and compartmentalize the membrane. In this chapter, we describe the biophysical, biochemical, and molecular approaches used to define and characterize lipid rafts in the Lyme disease agent, Borrelia burgdorferi...
2018: Methods in Molecular Biology
Kakali Ghoshal, Subhadip Chakraborty, Chirantan Das, Sanatan Chattopadhyay, Subhankar Chowdhury, Maitree Bhattacharyya
Dielectric properties of a living biological membrane play crucial role indicating the status of the cell in pathogenic or healthy condition. A distinct variation in membrane capacitance and impedance was observed for PBMC suspensions for diabetic and diabetic-dyslipidemic subjects compared to healthy control. Low frequency region were explicitly considered in electrical analysis to address complex membrane dielectric factors that alter the system capacitance of a PBMC suspension. Such variation was marked in size, morphology and membrane function of PBMCs for control and diseased cases...
October 10, 2017: Archives of Biochemistry and Biophysics
Sheila Roitman, Ellen Hornung, José Flores-Uribe, Itai Sharon, Ivo Feussner, Oded Béjà
Cyanobacteria are among the most abundant photosynthetic organisms in the oceans; viruses infecting cyanobacteria (cyanophages) can alter cyanobacterial populations, and therefore affect the local food web and global biochemical cycles. These phages carry auxiliary metabolic genes (AMGs), which rewire various metabolic pathways in the infected host cell, resulting in increased phage fitness. Coping with stress resulting from photodamage appears to be a central necessity of cyanophages, yet the overall mechanism is poorly understood...
October 13, 2017: ISME Journal
Saba Ghazvini, Ryan Alonso, Nabil Alhakamy, Prajnaparamita Dhar
Lipid membranes, a major component of cells, are subjected to significant changes in the pH depending on their location in the cell: the outer leaflet of the cell membrane is exposed to a pH of 7.4 while lipid membranes that make up late endosomes and lysosomes are exposed to a pH as low as 4.4. The purpose of this study is to evaluate how changes in the environmental pH within cells alter the fluidity of phospholipid membranes. Specifically, we studied pH induced alterations in the surface arrangement of monounsaturated lipids with zwitterionic head-groups (phosphoethanolamine (PE) and phosphocholine (PC)) that are abundant in plasma membrane, as well as anionic lipids (phosphatidylserine (PS) and phosphatidylglycerol (PG)) that are abundant in inner membranes, using a combination of techniques including surface tension vs...
October 11, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Pia Steinrücken, Svein Rune Erga, Svein Are Mjøs, Hans Kleivdal, Siv Kristin Prestegard
Microalgae are considered to be an important and sustainable alternative to fish oil as a source for the polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Due to their health benefits, there is an increasing interest in the commercial application of these fatty acids (FA) to health and dietary products, and to aquaculture feeds. However, FA from microalgae are still expensive to produce compared to fish or plant oils. With only a few microalgal strains being cultivated on a large scale for commercial PUFA production, prospecting for new, robust and fast-growing strains with increased PUFA content is essential in order to reduce production costs...
September 2017: Algal research
Siew-Leng Loo, Winna Siti, Monisha Thiyagarajan, Jaume Torres, Rong Wang, Xiao Matthew Hu
Film rehydration method is commonly used for membrane protein (MP) reconstitution into block copolymer (BCP), but the lack of control in the rehydration step formed a heterogeneous population of proteopolymersomes that interferes with the characterization and performance of devices incorporating them. To improve the self-assembly of polymersomes with simultaneous MP reconstitution, the study reported herein aimed to understand the effects of different variants of the rehydration procedure on the MP reconstitution into BCP membranes...
October 6, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Vincent L Thoms, Tristan T Hormel, Matthew A Reyer, Raghuveer Parthasarathy
The diffusion of biomolecules at lipid membranes is governed by the viscosity of the underlying two-dimensionally fluid lipid bilayer. For common three-dimensional fluids, viscosity can be modulated by hydrostatic pressure, and pressure-viscosity data have been measured for decades. Remarkably, the two-dimensional analogue of this relationship, the dependence of molecular mobility on tension, has to the best of our knowledge never been measured for lipid bilayers, limiting our understanding of cellular mechanotransduction as well as the fundamental fluid mechanics of membranes...
October 6, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Rebeca Caires, Francisco J Sierra-Valdez, Jonathan R M Millet, Joshua D Herwig, Esra Roan, Valeria Vásquez, Julio F Cordero-Morales
Dietary consumption of ω-3 polyunsaturated fatty acids (PUFAs), present in fish oils, is known to improve the vascular response, but their molecular targets remain largely unknown. Activation of the TRPV4 channel has been implicated in endothelium-dependent vasorelaxation. Here, we studied the contribution of ω-3 PUFAs to TRPV4 function by precisely manipulating the fatty acid content in Caenorhabditis elegans. By genetically depriving the worms of PUFAs, we determined that the metabolism of ω-3 fatty acids is required for TRPV4 activity...
October 3, 2017: Cell Reports
Gong Chen, Qi Bei, Tao Huang, Zhenqiang Wu
BACKGROUND: Monascus pigments are promising sources for food and medicine due to their natural food-coloring functions and pharmaceutical values. The innovative technology of extractive fermentation is used to promote pigment productivity, but reports of pigment trans-membrane secretion mechanism are rare. In this study, tracking of pigment accumulation and secretion in extractive fermentation of Monascus anka GIM 3.592 was investigated. RESULTS: The increased vacuole size in mycelia correlated with fluorescence intensity (r > 0...
October 4, 2017: Microbial Cell Factories
Paola de Andrade Mello, Shu Bian, Luiz Eduardo Baggio Savio, Haohai Zhang, Jingping Zhang, Wolfgang Junger, Márcia Rosângela Wink, Guido Lenz, Andréia Buffon, Yan Wu, Simon Christopher Robson
Extracellular ATP (eATP) accumulation within the tumor microenvironment (TME) has the potential to activate purinergic signaling. The eATP evoked signaling effects bolster antitumor immune responses while exerting direct cytotoxicity on tumor cells and vascular endothelial cells, mediated at least in part through P2X7 receptors. Approaches to augment purinergic signaling in TME e.g. by ectonucleotidase CD39 blockade, and/or boosting P2X7 functional responses, might be used as immunomodulatory therapies in cancer treatment...
September 15, 2017: Oncotarget
Michael S Lopez, Irene S Tan, Donghong Yan, Jing Kang, Mark McCreary, Zora Modrusan, Cary D Austin, Min Xu, Eric J Brown
The type VII secretion system (T7SS) of Staphylococcus aureus is a multiprotein complex dedicated to the export of several virulence factors during host infection. This virulence pathway plays a key role in promoting bacterial survival and the long-term persistence of staphylococcal abscess communities. The expression of the T7SS is activated by bacterial interaction with host tissues including blood serum, nasal secretions, and pulmonary surfactant. In this work we identify the major stimulatory factors as host-specific cis-unsaturated fatty acids...
October 2, 2017: Proceedings of the National Academy of Sciences of the United States of America
Marjorie Whitfield, Rachel Guiton, Jeremie Rispal, Niyazi Acar, Ayhan Kocer, Joël R Drevet, Fabrice Saez
Lipid metabolism disorders (dyslipidemia) are causes of male infertility, but little is known about their impact on male gametes when considering post-testicular maturation events, given that studies concentrate most often on endocrine dysfunctions and testicular consequences. In this study, three-month-old wild type (wt) and Liver-X-Receptors knock out (Lxrα;β-/-) males were fed four weeks with a control or a lipid-enriched diet containing 1.25% cholesterol (High Cholesterol Diet - HCD). The HCD triggered a dyslipidemia leading to sperm post-testicular alterations and infertility...
October 2, 2017: Reproduction: the Official Journal of the Society for the Study of Fertility
Azusa Oshima, Koji Sumitomo
The fusion of proteoliposomes is a promising approach for incorporating membrane proteins in artificial lipid membranes. In this study, we employed an electrostatic interaction between vesicles and supported bilayer lipid membranes (s-BLMs) to control the fusion process. We combined large unilamellar vesicles (LUVs) containing anionic lipids, which we used instead of proteoliposomes, and s-BLMs containing cationic lipids to control electrostatic interaction. Anionic LUVs were never adsorbed or ruptured on the SiO2 substrate with a slight negative charge, and selectively fused with cationic s-BLMs...
September 2017: Biochemistry and Biophysics Reports
Pratik Krishnan, Akshi Singla, Chin-An Lee, Joshua D Weatherston, Nolan C Worstell, Hung-Jen Wu
GM1 has generally been considered as the major receptor that binds to cholera toxin subunit B (CTB) due to its low dissociation constant. However, using a unique nanocube sensor technology, we have shown that CTB can also bind to other glycolipid receptors, fucosyl-GM1 and GD1b. Additionally, we have demonstrated that GM2 can contribute to CTB binding if present in a glycolipid mixture with a strongly binding receptor (GM1/fucosyl-GM1/GD1b). This hetero-multivalent binding result was unintuitive because the interaction between CTB and pure GM2 is negligible...
September 14, 2017: Colloids and Surfaces. B, Biointerfaces
Sutharsan Govindarajan, Orna Amster-Choder
The Sec system is responsible for protein insertion, translocation and secretion across membranes in all cells. The bacterial actin homolog MreB controls various processes, including cell wall synthesis, membrane organization and polarity establishment. Here we show that the two systems genetically interact and that components of the Sec system, especially the SecA motor protein, are essential for spatiotemporal organization of MreB in E. coli, as evidenced by the accumulation of MreB at irregular sites in Sec-impaired cells...
September 2017: PLoS Genetics
Konstantin N Belosludtsev, Natalia V Belosludtseva, Kirill S Tenkov, Nikita V Penkov, Alexey V Agafonov, Lyubov L Pavlik, Valery A Yashin, Victor N Samartsev, Mikhail V Dubinin
The effect of the antimicrobial compound triclosan (5-chloro-2'-(2,4-dichlorophenoxy)phenol;) on the permeability of lecithin liposomes and rat liver mitochondria was studied. It was found that triclosan was able to increase nonspecific permeability of liposomes in a dose-dependent manner, which was detected by the release of the fluorescent probe sulforhodamine B (SRB) from vesicles. A partial release of SRB occurs instantly at the moment of triclosan addition, which is followed by a slow leakage of the dye...
September 19, 2017: Biochimica et Biophysica Acta
Marcin Broniatowski, Martyna Binczycka, Aneta Wójcik, Michał Flasiński, Paweł Wydro
High molecular weight polycyclic aromatic hydrocarbons (HMW-PAHs) are persistent organic pollutants which due to their limited biodegradability accumulate in soils where their increased presence can lead to the impoverishment of the decomposer organisms. As very hydrophobic PAHs easily penetrate cellular membranes of soil bacteria and can be incorporated therein, changing the membrane fluidity and other functions which in consequence can lead to the death of the organism. The structure and size of PAH molecule can be crucial for its membrane activity; however the correlation between PAH structure and its interaction with phospholipids have not been investigated so far...
September 20, 2017: Biochimica et Biophysica Acta
María Cecilia De Rossi, Diana E Wetzler, Lorena Benseñor, María Emilia De Rossi, Mariela Sued, Daniela Rodríguez, Vladimir Gelfand, Luciana Bruno, Valeria Levi
BACKGROUND: Intracellular transport requires molecular motors that step along cytoskeletal filaments actively dragging cargoes through the crowded cytoplasm. Here, we explore the interplay of the opposed polarity motors kinesin-1 and cytoplasmic dynein during peroxisome transport along microtubules in Drosophila S2 cells. METHODS: We used single particle tracking with nanometer accuracy and millisecond time resolution to extract quantitative information on the bidirectional motion of organelles...
September 19, 2017: Biochimica et Biophysica Acta
Sebastião Antonio Mendanha, Cássia Alessandra Marquezin, Amando Siuiti Ito, Antonio Alonso
The sesquiterpene nerolidol and the monoterpene limonene are potent skin-permeation enhancers that have also been shown to have antitumor, antibacterial, antifungal and antiparasitic activities. Because terpenes are membrane-active compounds, we used electron paramagnetic resonance (EPR) spectroscopy of three membrane spin labels combined with the fluorescence spectroscopy of three lipid probes to study the interactions of these terpenes with stratum corneum (SC) intercellular membranes. An experimental apparatus was developed to assess the lipid fluidity of hydrated SC membranes via the fluorescence anisotropy of extrinsic membrane probes...
September 19, 2017: International Journal of Pharmaceutics
Amin Feizpour, David N Stelter, Crystal Wong, Hisashi Akiyama, Suryaram Gummuluru, Tom Keyes, Bjoern M Reinhard
Viral membranes are nanomaterials whose fluidity depends on their composition, in particular the cholesterol (chol) content. As differences in the membrane composition of individual virus particles can lead to different intracellular fates, biophysical tools capable of sensing the membrane fluidity on the single-virus level are required. In this manuscript, we demonstrate that fluctuations in the polarization of light scattered off gold or silver nanoparticle (NP)-labeled virus-like-particles (VLPs) encode information about the membrane fluidity of individual VLPs...
September 21, 2017: ACS Sensors
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