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membrane fluidity

Carme Huguet, Susanne Fietz, Antoni Rosell-Melé, Xavier Daura, Lionel Costenaro
Archaeal tetraether membrane lipids span the whole membrane width and present two C40 isoprenoid chains bound by two glycerol groups (or one glycerol and calditol). These lipids confer stability and maintain the membrane fluidity in mesophile to extremophile environments, making them very attractive for biotechnological applications. The isoprenoid lipid composition in archaeal membranes varies with temperature, which has placed these lipids in the focus of paleo-climatological studies for about a decade. Non-hydroxylated isoprenoid archaeal lipids are typically used as paleo-thermometry proxies, but recently identified hydroxylated (OH) derivatives have also been proposed as temperature proxies...
February 15, 2017: Biochimica et Biophysica Acta
Yong-Nan Liu, Tian-Jun Zhang, Xiao-Xiao Lu, Bao-Liang Ma, Ang Ren, Liang Shi, Ai-Liang Jiang, Han-Shou Yu, Ming-Wen Zhao
Ganoderma lucidum has become a potential model system for evaluating how environmental factors regulate the secondary metabolism of basidiomycetes. Heat stress (HS) is one of the most important environmental factors. It was previously reported that HS could induce the biosynthesis of ganoderic acids (GA). In this study, we found that HS increased GA biosynthesis and also significantly increased cell membrane fluidity. Furthermore, our results showed that addition of the membrane rigidifier DMSO could revert the increased GA biosynthesis elicited by HS...
February 15, 2017: Environmental Microbiology
M Fritzsche, D Li, H Colin-York, V T Chang, E Moeendarbary, J H Felce, E Sezgin, G Charras, E Betzig, C Eggeling
Cell-free studies have demonstrated how collective action of actin-associated proteins can organize actin filaments into dynamic patterns, such as vortices, asters and stars. Using complementary microscopic techniques, we here show evidence of such self-organization of the actin cortex in living HeLa cells. During cell adhesion, an active multistage process naturally leads to pattern transitions from actin vortices over stars into asters. This process is primarily driven by Arp2/3 complex nucleation, but not by myosin motors, which is in contrast to what has been theoretically predicted and observed in vitro...
February 13, 2017: Nature Communications
J M Teijeiro, P E Marini, M J Bragado, L J Garcia-Marin
Male germ cells undergo different processes within the female reproductive tract to successfully fertilize the oocyte. These processes are triggered by different extracellular stimuli leading to activation of protein phosphorylation. Protein kinase C (PKC) is a key regulatory enzyme in signal transduction mechanisms involved in many cellular processes. Studies in boar sperm demonstrated a role for PKC in the intracellular signaling involved in motility and cellular volume regulation. Experiments using phorbol 12-myristate 13-acetate (PMA) showed increases in the Serine/Threonine phosphorylation of substrates downstream of PKC in boar sperm...
February 10, 2017: Andrology
Vikas Dubey, Xavier Prasanna, Durba Sengupta
The insertion and association of membrane proteins is critical in several cellular processes. These processes were thought to be protein-driven, but increasing evidence points towards an important role of the lipid bilayer. The lipid-mediated contribution has been shown to be important in the association of membrane peptides, but the corresponding "lipophobic" component has not been directly estimated. Here, we calculate the free energy of insertion for transmembrane peptides and estimate the lipophobic component from the cost of cavity formation...
February 10, 2017: Journal of Physical Chemistry. B
Mouhedine Cheniour, Jonathan Brewer, Luis Bagatolli, Olivier Marcillat, Thierry Granjon
BACKGROUND: Mitochondrial Creatine kinase (mtCK) is highly abundant in mitochondria; its quantity is equimolecular to the Adenylic Nucleotide Translocator and represents 1% of the mitochondrial proteins. It is a multitask protein localized in the mitochondria intermembrane space where it binds to the specific cardiolipin (CL) phospholipid. If mtCK was initially thought to be exclusively implicated in energy transfer between mitochondria and cytosol through a mechanism referred to as the phosphocreatine shuttle, several recent studies suggested an additional role in maintaining mitochondria membrane structure...
February 6, 2017: Biochimica et Biophysica Acta
Mariam Alaverdashvili, Mark J Hackett, Sally Caine, Phyllis G Paterson
While protein-energy malnutrition in the adult has been reported to induce motor abnormalities and exaggerate motor deficits caused by stroke, it is not known if alterations in mature cortical neurons contribute to the functional deficits. Therefore, we explored if PEM in adult rats provoked changes in the biochemical profile of neurons in the forelimb and hindlimb regions of the motor cortex. Fourier transform infrared spectroscopic imaging using a synchrotron generated light source revealed for the first time altered lipid composition in neurons and subcellular domains (cytosol and nuclei) in a cortical layer and region-specific manner...
February 4, 2017: NeuroImage
Lu Lai, Sheng-Jin Li, Jing Feng, Ping Mei, Zhao-Hua Ren, Yan-Ling Chang, Yi Liu
The inhibitory effects of CdTe/ZnS quantum dots (QDs) modified with 3-mercaptopropionic acid (negatively charged) or cysteamine (positively charged) on the metabolic activity of Escherichia coli were investigated using biological microcalorimetry. Results show that the inhibitory ratio of positive QDs is higher than that of negative QDs. Transmission electron microscopy images indicate that QDs are prone to be adsorbed on the surface of E. coli. This condition disturbs the membrane structure and function of E...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Rebeca Gadea, Nicolas Glibota, Ruben Pérez Pulido, Antonio Galvez, Elena Ortega
Chlorhexidine (CH) and quaternary ammonium compounds (QAC), like cetrimide (CE) are widely used as disinfectants because of their broad antimicrobial spectrum. However, their frequent use for disinfection in different settings may promote bacterial drug resistance against both biocides and clinically relevant antibiotics. This study analyzes the effects of step-wise exposure to cetrimide (CE) and chlorhexidine (CH) of bacteria from organic foods and previously classified as sensitive to biocides. Gradual exposure of these strains to biocides resulted in mainly transient decreased antimicrobial susceptibility to other biocides and to antibiotics...
February 8, 2017: Journal of Agricultural and Food Chemistry
D M Silva, S A Holden, A Lyons, J C Souza, S Fair
The aim of the present study was to assess the effect of the addition of docosahexaenoic acid (DHA) on the in vitro quality of cooled and frozen-thawed stallion semen. In Experiment 1, semen from 10 stallions was collected (three ejaculates per stallion). Semen was diluted to 100×106 spermatozoa mL-1 with 0.02mM vitamin E (VE) and 0, 1, 10 or 20ng mL-1 DHA and frozen. Semen was thawed and total motility (TM), rapid progressive motility (PM), acrosome integrity, membrane fluidity and morphology were assessed...
February 8, 2017: Reproduction, Fertility, and Development
E M Murphy, C Stanton, C O ' Brien, C Murphy, S Holden, R P Murphy, P Varley, M P Boland, S Fair
The objective of this study was to assess the effects of dietary supplementation of a commercial algal product rich in docosahexaenoic acid (DHA) on boar fertility as assessed in vitro and in vivo. Boars were fed one of three experimental diets for 19 weeks: (i) Control (Ctl) diet (n = 31), (ii) Ctl diet plus 75g All-G-Rich per day (n = 31) or (iii) Ctl diet plus 150g All-G-Rich per day (n = 30). Parameters assessed were (i) raw semen quality; volume, sperm concentration, total motility and morphology (ii) liquid semen quality; progressive motility, viability, hypotonic resistance and acrosomal integrity (iii) frozen-thawed semen quality; motility, thermal stress, viability, membrane fluidity and mitochondrial activity (iv) sperm and seminal plasma (SP) fatty acid composition (FAC) (v) total antioxidant capacity (TAC) of SP and (vi) farrowing rates and litter sizes of sows (n = 1158) inseminated with liquid semen...
March 1, 2017: Theriogenology
C J Byrne, S Fair, A M English, S A Holden, J R Dick, P Lonergan, D A Kenny
The aim of this study was to examine the effects of dietary supplementation with rumen protected n-6 or n-3 polyunsaturated fatty acids (PUFA) on the quantity and quality of semen from young post-pubertal dairy bulls. Pubertal Holstein-Friesian (n = 43) and Jersey (n = 7) bulls with a mean ± s.e.m. age and bodyweight of 420.1 ± 5.86 days and 382 ± 8.94 kg, respectively, were blocked on breed, weight, age and semen quality (based on the outcomes of two pre-trial ejaculates) and randomly assigned to one of three treatments: (i) a non-supplemented control (CTL, n = 15), (ii) rumen-protected safflower (SO, n = 15), (iii) rumen-protected n-3 PUFA-enriched fish oil (FO, n = 20)...
March 1, 2017: Theriogenology
Fumihiko Iwasaki, Sandra Luginbühl, Keishi Suga, Peter Walde, Hiroshi Umakoshi
Artificial vesicles formed from sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in aqueous solution are used successfully as additives for enzymatic oligomerizations or polymerizations of aniline or the aniline dimer p-aminodiphenylamine (PADPA) under slightly acidic conditions (e.g., pH 4.3 with horseradish peroxidase and hydrogen peroxide as oxidants). In these systems, the reactions occur membrane surface-confined. Therefore, (i) the physicochemical properties of the vesicle membrane and (ii) the interaction of aniline or PADPA with the AOT membrane play crucial roles in the progress and final outcome of the reactions...
February 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Simone S Grecco, Thais A Costa-Silva, Gerold Jerz, Fernanda S de Sousa, Geanne A Alves Conserva, Juliana T Mesquita, Mariana K Galuppo, Andre G Tempone, Bruno J Neves, Carolina H Andrade, Rodrigo L O R Cunha, Miriam Uemi, Patricia Sartorelli, João Henrique G Lago
BACKGROUND: From a previous screening of Brazilian biodiversity for antiprotozoal activity, the hexane extract from leaves of Nectandra leucantha (Nees & Mart.) (Lauraceae) demonstrated activity against Trypanosoma cruzi. Chromatographic separation of this extract afforded bioactive dehydrodieugenol (1). Furthermore, methylated derivative 2 (dehydrodieugenol dimethyl ether) was prepared and also tested against T. cruzi. PURPOSE: To examine the therapeutical potential of compounds 1 and 2 against T...
January 15, 2017: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
Ana Catarina Alves, Daniela Ribeiro, Miguel Horta, José L F C Lima, Cláudia Nunes, Salette Reis
The present work aimed to study the interactions between the anticancer drug daunorubicin and lipid membrane mimetic models of cancer cells composed by their most representative classes of phospholipids, with different degrees of complexity. Regarding these anticancer drug-membrane interactions, several biophysical parameters were assessed using liposomes (LUVs) composed of different molar ratios of DMPC, DOPC, DPPS, DOPE and Chol. In this context, daunorubicin's membrane concentration was determined by calculating its partition coefficient (Kp) between liposomes and water using derivative UV/vis spectrophotometry at 37°C and pH6...
January 30, 2017: Biochimica et Biophysica Acta
A Alcantar-Rodriguez, A Medrano
The objective was to assess the effect of cooling to different subzero temperatures around ice formation (-5°C) on dog sperm cryosurvival and plasma membrane fluidity. Semen was centrifuged, and sperm were resuspended in a Tris-egg yolk medium (3% glycerol). Diluted sperm were cooled from 22 to 5°C, and then, a Tris-egg yolk medium containing 7% glycerol was added (final concentration of 5% glycerol and 200 × 10(6)  cells/ml). Sperm were packaged in 0.5-ml plastic straws, and equilibration was done 16 hr at 5°C before freezing...
January 25, 2017: Reproduction in Domestic Animals, Zuchthygiene
Kyoung-Mi Kang, Nagendra N Mishra, Kun Taek Park, Gi-Yong Lee, Yong Ho Park, Arnold S Bayer, Soo-Jin Yang
Daptomycin (DAP) has potent activity in vitro and in vivo against both methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. DAP-resistance (DAP-R) in S. aureus has been mainly observed in MRSA strains, and has been linked to single nucleotide polymorphisms (SNPs) within the mprF gene leading to altered cell membrane (CM) phospholipid (PL) profiles, enhanced positive surface charge, and changes in CM fluidity. The current study was designed to delineate whether these same genotypic and phenotypic perturbations are demonstrated in clinically-derived DAP-R MSSA strains...
February 2017: Journal of Microbiology / the Microbiological Society of Korea
Hussein N Yassine, Meredith N Braskie, Wendy J Mack, Katherine J Castor, Alfred N Fonteh, Lon S Schneider, Michael G Harrington, Helena C Chui
Importance: The apolipoprotein E ε4 (APOE4) allele identifies a unique population that is at significant risk for developing Alzheimer disease (AD). Docosahexaenoic acid (DHA) is an essential ω-3 fatty acid that is critical to the formation of neuronal synapses and membrane fluidity. Observational studies have associated ω-3 intake, including DHA, with a reduced risk for incident AD. In contrast, randomized clinical trials of ω-3 fatty acids have yielded mixed and inconsistent results...
January 17, 2017: JAMA Neurology
Morgan Barker, Anthony Kennedy
Sucralose, an artificial sweetener, displays very different behavior towards membranes than its synthetic precursor sucrose. The impact of both sugars on model dipalmitoylphosphatidylcholine model membranes was investigated using absorbance and flourescence spectroscopy and the membrane probe merocyanine 540. This probe molecule is highly sensitive to changes in membrane packing, microviscosity and polarity. This work focuses on the impact of sugars on the outer leaflet of unilamellar dipalmitoyl phosphatidylcholine model membranes...
January 18, 2017: Colloids and Surfaces. B, Biointerfaces
Xiaozheng Duan, Yang Zhang, Liangyi Li, Ran Zhang, Mingming Ding, Qingrong Huang, Wen-Sheng Xu, Tongfei Shi, Lijia An
We employed coarse-grained Monte Carlo simulations to investigate a system composed of cationic polymers and a phosphatidyl-choline membrane monolayer, doped with univalent anionic phosphatidylserine (PS) and tetravalent anionic phosphatidylinositol 4,5-bisphosphate (PIP2) lipid molecules. For this system, we consider the conditions under which multiple cationic polymers can anchor onto the monolayer and explore how the concentration and ionization degree of the polymers affect the lateral rearrangement and fluidity of the negatively charged lipids...
February 9, 2017: Journal of Physical Chemistry. B
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