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https://www.readbyqxmd.com/read/28528628/millisecond-time-resolution-correlative-light-and-electron-microscopy-for-dynamic-cellular-processes
#1
Ludek Stepanek, Gaia Pigino
Molecular motors propel cellular components at velocities up to microns per second with nanometer precision. Imaging techniques combining high temporal and spatial resolution are therefore indispensable to understand the cellular mechanics at the molecular level. For example, intraflagellar transport (IFT) trains constantly shuttle ciliary components between the base and tip of the eukaryotic cilium. 3-D electron microscopy has revealed IFT train morphology and position, but was unable to correlate these features with the direction of train movement...
2017: Methods in Cell Biology
https://www.readbyqxmd.com/read/28527239/the-structure-of-a-lair1-containing-human-antibody-reveals-a-novel-mechanism-of-antigen-recognition
#2
Fu-Lien Hsieh, Matthew K Higgins
Antibodies are critical components of the human adaptive immune system, providing versatile scaffolds to display diverse antigen binding surfaces. Nevertheless, most antibodies have similar architectures, with the variable immunoglobulin domains of the heavy and light chain each providing three hypervariable loops, which are varied to generate diversity. The recent identification of a novel class of antibody in humans from malaria endemic regions of Africa was therefore surprising as one hypervariable loop contains the entire collagen-binding domain of human LAIR1...
May 20, 2017: ELife
https://www.readbyqxmd.com/read/28523617/one-pot-synthesis-of-lightly-doped-zn1-x-cu-x-o-and-au-zn1-x-cu-x-o-with-solar-light-photocatalytic-activity-in-liquid-phase
#3
Anis Fkiri, Marisa Rico Santacruz, Amine Mezni, Leila-Samia Smiri, Valérie Keller, Nicolas Keller
We report on the facile and low-temperature one-pot chemical synthesis of lightly doped Zn1-x Cu x O and hybrid Au-Zn1-x Cu x O photocatalysts with low Cu molar content (0 < x < 0.7%) using 1,3-propanediol polyol simultaneously as solvent, reducing and a stabilizing agent, without any final thermal treatment. The photocatalysts have been characterized by X-ray diffraction, N2 adsorption study, UV-vis diffuse reflectance spectroscopy, inductively coupled plasma optical emission spectroscopy, and transmission electron microscopy...
May 18, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28522397/cellulose-acetate-poly-lactic-acid-coaxial-wet-electrospun-scaffold-containing-citalopram-loaded-gelatin-nanocarriers-for-neural-tissue-engineering-applications
#4
Mahdi Naseri-Nosar, Majid Salehi, Shahriar Hojjati-Emami
The current study aimed to develop a biodegradable three-dimensional drug-loaded scaffold with the core-shell structured fibrils using coaxial wet-electrospinning for neural tissue engineering application. Poly lactic acid was wet-electrospun as the core, whereas cellulose acetate was fabricated into the fibril's shell. The scaffold then was coated with citalopram-loaded gelatin nanocarriers (CGNs) produced by nanoprecipitation. Scanning electron microscope observation revealed that the fibrils formed a nonwoven structure with the average diameter of ∼950nm...
May 15, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28522192/overcoming-photodynamic-resistance-and-tumor-targeting-dual-therapy-mediated-by-indocyanine-green-conjugated-gold-nanospheres
#5
Wei Li, Xiaomeng Guo, Fenfen Kong, Hanbo Zhang, Lihua Luo, Qingpo Li, Chunqi Zhu, Jie Yang, Yongzhong Du, Jian You
Photodynamic therapy (PDT) and photothermal therapy (PTT) have captured much attention due to the great potential to cure malignant tumor. Nevertheless, photodynamic resistance of cancer cells has limited the further efficacy of PDT. Unfortunately, the resistance mechanism and efforts to overcome the resistance still have been rarely reported so far. Here, we report a nanosystem with specific tumor targeting for combined PDT and PTT mediated by near-infrared (NIR) light, which was established by covalently conjugating indocyanine green (ICG) and TNYL peptide onto the surface of hollow gold nanospheres (HAuNS)...
May 15, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/28521517/dynamic-model-of-vascular-targeted-photodynamic-therapy
#6
Xiao-Ming Hu, Linhuan He, Yi Zhao
Vascular-targeted photodynamic therapy has shown efficiency in treating port wine stains. A dynamic model that incorporates blood flow, kinetic diffusion, oxygen and photosensitizer consumption and reaction, and light modulation is proposed to reveal the interactions among light, photosensitizer, and oxygen. Simulation results show that pulse light modulation synchronized with heartbeats hold the advantage of increased singlet oxygen accumulation, higher oxygen concentration and lower temperature. Meanwhile, constant light treatment is advantageous in terms of higher temperature, lower total oxygen concentration and singlet oxygen accumulation...
May 19, 2017: Computer Methods in Biomechanics and Biomedical Engineering
https://www.readbyqxmd.com/read/28518090/flash-and-freeze-a-novel-technique-to-capture-membrane-dynamics-with-electron-microscopy
#7
Shuo Li, Sumana Raychaudhuri, Shigeki Watanabe
Cells constantly change their membrane architecture and protein distribution, but it is extremely difficult to visualize these events at a temporal and spatial resolution on the order of ms and nm, respectively. We have developed a time-resolved electron microscopy technique, "flash-and-freeze," that induces cellular events with optogenetics and visualizes the resulting membrane dynamics by freezing cells at defined time points after stimulation. To demonstrate this technique, we expressed channelrhodopsin, a light-sensitive cation channel, in mouse hippocampal neurons...
May 1, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28516845/activity-and-functional-properties-of-the-isocitrate-lyase-in-the-cyanobacterium-cyanothece-sp-pcc-7424
#8
Marianne Gründel, Henning Knoop, Ralf Steuer
Cyanobacteria are ubiquitous photoautotrophs that assimilate atmospheric CO2 as their main source of carbon. Several cyanobacteria are known to be facultative heterotrophs that are able to grow on diverse carbon sources. For selected strains, assimilation of organic acids and mixotrophic growth on acetate has been reported for decades. However, evidence for the existence of a functional glyoxylate shunt in cyanobacteria has long been contradictory and unclear. Genes coding for isocitrate lyase (ICL) and malate synthase were recently identified in two strains of the genus Cyanothece, and the existence of the complete glyoxylate shunt was verified in a strain of Chlorogloeopsis fritschii...
May 18, 2017: Microbiology
https://www.readbyqxmd.com/read/28515734/plant-growth-under-natural-light-conditions-provides-highly-flexible-short-term-acclimation-properties-toward-high-light-stress
#9
Tobias Schumann, Suman Paul, Michael Melzer, Peter Dörmann, Peter Jahns
Efficient acclimation to different growth light intensities is essential for plant fitness. So far, most studies on light acclimation have been conducted with plants grown under different constant light regimes, but more recent work indicated that acclimation to fluctuating light or field conditions may result in different physiological properties of plants. Thale cress (Arabidopsis thaliana) was grown under three different constant light intensities (LL: 25 μmol photons m(-2) s(-1); NL: 100 μmol photons m(-2) s(-)(1); HL: 500 μmol photons m(-2) s(-1)) and under natural fluctuating light (NatL) conditions...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28510657/heteroblasty-in-epiphytic-bromeliads-functional-implications-for-species-in-understorey-and-exposed-growing-sites
#10
Joachim Beyschlag, Gerhard Zotz
Background and Aims: The functional relevance of heteroblasty, an abrupt morphological change in the ontogeny of a considerable number of angiosperm species, is still largely unresolved. During the ontogeny of many epiphytic Tillandsioids (Bromeliaceae), such a change occurs when small individuals transform into larger, tank-forming individuals that are capable of external water storage. Apart from its fundamental effect on plant water relations, the associated transition from narrow to broader leaves also affects plant architecture...
May 16, 2017: Annals of Botany
https://www.readbyqxmd.com/read/28510321/novel-zns-carbon-nanofibers-photocatalyst-for-degradation-of-rhodamine-6g-kinetics-tracking-of-operational-parameters-and-development-of-a-kinetics-model
#11
Ali Mehrizad, Parvin Gharbani
A novel nanocomposite in the role of photocatalyst was prepared by composition of zinc sulfide (ZnS) nanoparticles with carbon nanofibers (CNFs) and was characterized. The XRD, EDX, and FE-SEM analysis revealed that ZnS is successfully embedded in CNFs matrix. The DRS results indicated that supporting of ZnS by CNFs led to a decrease of the band gap energy. The photocatalytic degradation of a hazardous xanthine dye, Rhodamine 6 G (Rh-6G), by the prepared ZnS/CNFs composite was examined from the kinetics point of view...
May 16, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28510131/generation-of-radical-form-of-dipyridamole-at-illumination-of-photosynthetic-reaction-centers-of-rb-sphaeroides
#12
P P Knox, K N Timofeev, V V Gorokhov, N Kh Seifullina, A B Rubin
The study of the effect of vasodilator, antiplatelet agent, and inhibitor P-glycoprotein dipyridamole (DIP) on the functioning of the transmembrane protein of the reaction center (RC) of Rb. sphaeroides showed that the activation of RC by constant light generates the DIP radical cation, which significantly affects the kinetics of recombination of charges divided between photoactive bacteriochlorophyll and quinone acceptors. Thus, the antioxidant properties of DIP may affect the functional activity of membrane proteins, and this apparently should be taken into account in the studies of the mechanisms of therapeutic action of this drug...
March 2017: Doklady. Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28510018/a-hilly-path-through-the-thermodynamics-and-statistical-mechanics-of-protein-solutions
#13
REVIEW
Peter R Wills
The opus of Don Winzor in the fields of physical and analytical biochemistry is a major component of that certain antipodean approach to this broad area of research that blossomed in the second half of the twentieth century. The need to formulate problems in terms of thermodynamic nonideality posed the challenge of describing a clear route from molecular interactions to the parameters that biochemists routinely measure. Mapping out this route required delving into the statistical mechanics of solutions of macromolecules, and at every turn mathematically complex, rigorous, general results that had previously been derived previously, often by Terrell Hill, came to the fore...
December 2016: Biophysical Reviews
https://www.readbyqxmd.com/read/28507293/exploring-optoelectronic-properties-and-mechanisms-of-layered-ferroelectric-k4nb6o17-nanocrystalline-films-and-nanolaminas
#14
Qinglin Deng, Mengjiao Li, Junyong Wang, Peng Zhang, Kai Jiang, Jinzhong Zhang, Zhigao Hu, Junhao Chu
Two-dimensional layered K4Nb6O17 (KN) was easily formed as a secondary phase caused by the volatilization of alkali metal ions, when preparing ferroelectric K x Na1-x NbO3 based ceramics and films. In this work, it was believed that KN film is with weak ferroelectricity and has a little effect on the ferroelectric properties of K x Na1-x NbO3 based films. Moreover, temperature dependent (77-500 K) dielectric functions of KN film have been firstly extracted by fitting ellipsometric spectra with the Adachi dielectric function model and a four-phase layered model...
May 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28505497/binding-of-ciprofloxacin-to-bovine-serum-albumin-photophysical-and-thermodynamic-aspects
#15
Bijan K Paul, Nikhil Guchhait, Subhash Chandra Bhattacharya
The present work reveals the study of interaction of a promising chemotherapeutic drug ciprofloxacin (CFX) with a model transport protein bovine serum albumin (BSA). The occurrence of the drug-protein interaction is found to result in significant modulations of the fluorescence excitation and emission spectroscopic properties of CFX following interaction with BSA. However, the major focus of the study underlies a critical insight into the quantitation of the drug-protein interaction phenomenon. To this end, we have exploited the isothermal titration calorimetric (ITC) technique to quantify the affinity constant (Ka) and stoichiometry (n) of the CFX-BSA interaction with simultaneous revelation of the accompanying thermodynamics of the interaction process...
May 5, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28505434/photolysis-of-particulate-nitrate-as-a-source-of-hono-and-nox
#16
Chunxiang Ye, Ning Zhang, Honglian Gao, Xianliang Zhou
Photolysis of nitric acid on the surface has been found recently to be greatly enhanced from that in the gas phase. Yet, photolysis of particulate nitrate (pNO3) associated with atmospheric aerosols is still relatively unknown. Here, aerosol filter samples were collected both near the ground surface and throughout the troposphere on board NSF/NACR C-130 aircraft. The photolysis rate constants of pNO3 were determined from these samples by directly monitoring the production rates of nitrous acid (HONO) and nitrogen dioxide (NO2) under UV light (> 290 nm) irradiation...
May 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28504728/scalable-fourier-transform-system-for-instantly-structured-illumination-in-lithography
#17
Yan Ye, Fengchuan Xu, Guojun Wei, Yishen Xu, Donglin Pu, Linsen Chen, Zhiwei Huang
We report the development of a unique scalable Fourier transform 4-f system for instantly structured illumination in lithography. In the 4-f system, coupled with a 1-D grating and a phase retarder, the ±1st order of diffracted light from the grating serve as coherent incident sources for creating interference patterns on the image plane. By adjusting the grating and the phase retarder, the interference fringes with consecutive frequencies, as well as their orientations and phase shifts, can be generated instantly within a constant interference area...
May 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28501642/a-novel-method-for-photo-oxidative-degradation-of-diatrizoate-in-water-via-electromagnetic-induction-electrodeless-lamp
#18
Lingjun Meng, Shaogui Yang, Cheng Sun, Huan He, Qiming Xian, Shiyin Li, Guoxiang Wang, Limin Zhang, Dong Jiang
In this study, an electromagnetic induction electrodeless lamp (EIEL) was first introduced into UV advanced oxidation processes (AOPs) for photodegradation of Diatrizoate (DTZ), which was the most persistent iodinated X-ray contrast medium (ICM), and traditional Hg lamps were taken as references. Direct photolysis rate of DTZ under EIEL irradiation was 1.34 times as that under Hg irradiation, but the electric energy consumption was 0.87 times. In this sense, the combination of EIEL and oxidants (O2, H2O2 and S2O8(2-)(PS)) was further investigated...
May 5, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28500710/characterization-of-the-blue-light-activated-adenylyl-cyclase-mpac-by-flash-photolysis-and-ftir-spectroscopy
#19
Silke Kerruth, Pit Langner, Sarah Raffelberg, Wolfgang Gärtner, Joachim Heberle
The recently discovered photo-activated adenylyl cyclase (mPAC from Microcoleus chthonoplastes) is the first PAC that owes a light-, oxygen- and voltage-sensitive (LOV) domain for blue-light sensing. The photoreaction of the mPAC receptor was studied by time-resolved UV/vis and light-induced Fourier transform infrared (FTIR) absorption difference spectroscopy. The photocycle comprises of the typical triplet state LOV715 and the thio-adduct state LOV390 . While the adduct state decays with a time constant of 8 s, the lifetime of the triplet state is with 656 ns significantly shorter than in all other reported LOV domains...
May 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28500700/influence-of-heterogeneity-on-the-ultrafast-photoisomerization-dynamics-of-pfr-in-cph1-phytochrome
#20
Till Stensitzki, Yang Yang, Anna Lena Wölke, Ernst-Walter Knapp, Jon Hughes, Maria Andrea Mroginski, Karsten Heyne
Photoisomerization of a protein-bound chromophore is the basis of light sensing and signaling in many photoreceptors. Phytochrome photoreceptors can be photoconverted reversibly between the Pr and Pfr states through photoisomerization of the methine bridge between rings C and D. Ground-state heterogeneity of the chromophore has been reported for both Pr and Pfr. Here, we report ultrafast visible (Vis) pump-probe and femtosecond polarization-resolved Vis pump-infrared (IR) probe studies of the Pfr photoreaction in native and (13) C/(15) N-labeled Cph1 phytochrome with unlabeled PCB chromophore, demonstrating different S0 substates, Pfr-I and Pfr-II, with distinct IR absorptions, orientations and dynamics of the carbonyl vibration of ring D...
May 2017: Photochemistry and Photobiology
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