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41.
A novel integrated optical technique is used to monitor the kinetics of incorporation of glycophorin A (GPA) from solution into a planar dimyristoylphosphatidylcholine-cholesterol bilayer membrane, and the subsequent binding of wheat germ agglutinin (WGA) to the membrane-incorporated GPA. The technique significantly improves the attainable accuracy of kinetic measurements. The number of bound molecules can be determined to a precision of ca ± 80 mol µm–2. Our results show that GPA incorporates spontaneously into the bilayer. Binding of WGA to GPA is optimal in the presence of human serum albumin, and can be reversed byN-acetyl-d-glucosamine. The kinetics of the binding are consistent with the presence of two classes of kinetically distinguishable binding sites with association rates of 2.0×104 and 9.6×102 M–1 s–1, and dissociation rates of 2.7×10–3 s–1 and <10–5 s–1, respectively. A stoichiometry of 4 WGA monomers per GPA monomer was determined as characteristic of the overall binding interaction.Abbreviations DMPC
dimyristoylphosphatidylcholine
- GlcNAc
N-acetyl-d-glucosamine
- GPA
glycophorin A
- HSA
human serum albumin
- NeuNAc
N-acetyl-d-neuraminic acid
- TE
transverse electric
- TM
transverse magnetic
- WGA
wheat germ agglutinin 相似文献
42.
Joseph P.L. Morrall Marie P. Cifuentes Ruben Kellens Inge Asselberghs André Persoons Anthony C. Willis 《Inorganica chimica acta》2006,359(3):998-1005
The complexes trans-[Ru(CC-4-C6H4F)X(dppe)2] [X = Cl (1), CCPh (2), CC-4-C6H4NO2 (3)], trans-[Ru{CC-4-C6H4-(E)-CHCH-4-C6H4NO2}X(dppe)2] [X = CCPh (4), CC-4-C6H4CCPh (5)], and [C6H3-1,3-{CC-trans-[RuCl(dppe)2]}2-5-(CC-4-C6H4F)] (6) have been synthesized and the identity of 1 confirmed by a single-crystal X-ray diffraction study. Cyclic voltammetry reveals a metal-centered oxidation, the potential of which is largely invariant on alkynyl ligand replacement across the series 1-5; the diruthenium complex 6 shows two oxidation processes, consistent with weakly interacting metal centers. Hyper-Rayleigh scattering (HRS) studies at 1064 nm using ns pulses suggest quadratic nonlinearities for 3-5 that are amongst the largest thus far for organometallic complexes, a trend maintained with the two-level-corrected data. HRS studies at 800 nm using fs pulses and amplitude modulation to remove multi-photon fluorescence contributions reveal significant fluorescence-free nonlinearities for 3-5; the frequency-independent nonlinearities calculated from the 800 nm results are suggestive of fluorescence contributions to the 1064 nm data. Z-scan studies at 820 nm reveal cubic nonlinearities that increase with the size of the π-system, although error margins are significant. 相似文献
43.
Alexander Asanov Angélica Zepeda Luis Vaca 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2010,1801(2):147-155
In the present study we have applied a novel form of Total Internal Reflection Fluorescence Microscopy (LG-TIRFM) in combination with fluorescently labeled cholera toxin to the study of lipid rafts dynamics in living cells. We demonstrate the usefulness of such approach by showing the dynamic formation/disaggregation of islands of cholera toxin on the surface of cells. Using multicolor LG-TIRFM with co-localization studies we show for the first time that two receptors previously identified as constituents of lipid rafts are found on different and independent “raft domains” on the cell plasma membrane. Furthermore, LG-TIRFM studies revealed limited association and dissociation of both domains overtime on different areas of the plasma membrane. The implications of different “raft domains” on cell physiology are discussed. 相似文献
44.
Germn Gonzlez Conor L. Evans 《BioEssays : news and reviews in molecular, cellular and developmental biology》2019,41(6)
Here, a streamlined, scalable, laboratory approach is discussed that enables medium‐to‐large dataset analysis. The presented approach combines data management, artificial intelligence, containerization, cluster orchestration, and quality control in a unified analytic pipeline. The unique combination of these individual building blocks creates a new and powerful analysis approach that can readily be applied to medium‐to‐large datasets by researchers to accelerate the pace of research. The proposed framework is applied to a project that counts the number of plasmonic nanoparticles bound to peripheral blood mononuclear cells in dark‐field microscopy images. By using the techniques presented in this article, the images are automatically processed overnight, without user interaction, streamlining the path from experiment to conclusions. 相似文献
45.
46.
Zero-cost modification of bright field microscopes for imaging phase gradient on cells: Schlieren optics 总被引:1,自引:0,他引:1
Daniel Axelrod 《Cell biochemistry and biophysics》1981,3(2):167-173
A simple, zero-cost, reversible modification of a bright field microscope permits visualization of phase gradients in cells
by transmitted illumination, yielding a Nomarski-like effect. This modification, based on schlieren optics, is simultaneously
compatible with high-aperture epi-illumination fluorescence excitation. For many objectives that are intended for use in fluorescence
work, but are unavailable in phase contrast versions, the modification provides a simple means for locating cells in culture
with good image contrast and resolution. 相似文献
47.
ESTIMATION OF CHLOROPHYLL a FROM TIME SERIES MEASUREMENTS OF HIGH SPECTRAL RESOLUTION REFLECTANCE IN AN EUTROPHIC LAKE 总被引:1,自引:0,他引:1
John F. Schalles Anatoly A. Gitelson Yosef Z. Yacobi Amy E. Kroenke 《Journal of phycology》1998,34(2):383-390
We acquired high spectral resolution reflectance data in Carter Lake, a eutrophic oxbow on the Iowa–Nebraska border, from April 1995 to April 1996. Chlorophyll a, total seston, sestonic organic matter, Secchi depth, and nephelometric turbidity were determined for each respective spectral measurement. Changes in algal taxonomic structure and abundance coincided with the development and senescence of a midsummer through autumn bloom of Anabaena. Taxonomic structure was more diverse in late winter and spring when Synedra sp. (diatom) and several chlorophytes and dinoflagellates were present. Overall, chlorophyll a varied from about 20 to 280 μg·L?1, Secchi transparency from 18 to 74 cm, and seston dry weight from 11 to 48 mg·L?1 in February and September, respectively. Particulate matter completely dominated lake water light attenuation. Dissolved organic matter had low optical activity. The most sensitive spectral feature to variation in chlorophyll a concentration was the magnitude of the scattering peak near 700 nm. The 700-nm peak correlated to chlorophyll concentration through the relationships between algal pigment absorption near 670 nm and the cell biomass and surface-related scattering signal in the near infrared. An algorithm relating the height of the 700-nm reflectance peak above a reference baseline between 670 and 850 nm to chlorophyll a was accurate and robust despite large variations in optical constituents caused by both strong seasonality in the algal system and short-term variations in seston from wind-induced sediment resuspension. The present algorithms were successfully used in other systems with different seasonality and productivity patterns. The coefficients of the models relating chlorophyll a and spectral reflectance variables appeared to be ecosystem specific: both the intercept and slope for the models in this study were moderately lower than for several other recently published results. We validated our algorithm coefficients with a second, independent dataset. The standard error for chlorophyll a prediction was ±28 μg·L?1. 相似文献
48.
The structure and optics of the mesopelagic double-eyed mysid crustacean Euchaetomera typica Sars, 1884 are described for the first time. The lateral eye is a typical refracting superposition eye with a wide field of view (172°) and low resolution (interommatidial angle of 7.3°). The antero-dorsal part of the eye is elongated due to the extension of the clear zone. This dorsal eye has a restricted field of view (33°) but much higher resolution (1.5°). The dorsal eye also uses refracting superposition optics, although the optical array is unusual as many of the peripheral ommatidia lack crystalline cones. The centre of curvature of the cornea is in front of the flattened rhabdom layer whereas the axes of the crystalline cones are centred on a point about twice as deep as the rhabdom layer. This results in a well-focused eye, free of spherical aberration. There is a remarkable similarity in eye structure between this species and some mesopelagic double-eyed euphausiid crustaceans. 相似文献
49.
50.
Inside Cover: Fiber‐based fluorescence lifetime imaging of recellularization processes on vascular tissue constructs (J. Biophotonics 9/2018) 下载免费PDF全文
Alba Alfonso‐Garcia Jeny Shklover Benjamin E. Sherlock Alyssa Panitch Leigh G. Griffiths Laura Marcu 《Journal of biophotonics》2018,11(9)
Tissue autofluorescence provides fluorescence lifetime contrast between acellular tissue and that containing newly seeded cells. Fiber‐based fluorescence lifetime imaging (FLIm) can be used for tracking recellularization of engineered vascular grafts and potential matrix remodeling at large scale, without compromising sample integrity. FLIm cellular contrast was verified in a subset of samples seeded with eGFP‐labelled cells. Results suggests fiberbased FLIm is a suitable tool for monitoring recellularization of engineered tissue nondestructively. Further details can be found in the article by Alba Alfonso‐Garcia, Jeny Shklover, Benjamin E. Sherlock, et al. ( e201700391 ).