共查询到20条相似文献,搜索用时 125 毫秒
1.
Ye K Shibasaki S Ueda M Murai T Kamasawa N Osumi M Shimizu K Tanaka A 《Applied microbiology and biotechnology》2000,54(1):90-96
An engineered yeast with emission of fluorescence from the cell surface was constructed. Cell surface engineering was applied
to display a visible reporter molecule, green fluorescent protein (GFP). A glucose-inducible promoter GAPDH as a model promoter was selected to control the expression of the reporter gene in response to environmental changes. The
GFP gene was fused with the gene encoding the C-terminal half of α-agglutinin of Saccharomyces cerevisiae having a glycosylphosphatidylinositol anchor attachment signal sequence. A secretion signal sequence of the fungal glucoamylase
precursor protein was connected to the N-terminal of GFP. This designed gene was integrated into the TRP1 locus of the chromosome of S. cerevisiae with homologous recombination. Fluorescence microscopy demonstrated that the transformant cells emitted green fluorescence
derived from functionally expressed GFP involved in the fusion molecule. The surface display of GFP was further verified by
immunofluorescence labeling with a polyclonal antibody (raised in rabbits) against GFP as the first antibody and Rhodamine
Red-X-conjugated goat anti-rabbit IgG as the second antibody which cannot penetrate into the cell membrane. The display of
GFP on the cell surface was confirmed using a confocal laser scanning microscope and by measuring fluorescence in each cell
fraction obtained after the subcellular fractionation. As GFP was proved to be displayed as an active form on the cell surface,
selection of promoters will endow yeast cells with abilities to respond to changes in environmental conditions, including
nutrient concentrations in the media, through the emission of fluorescence.
Received: 23 August 1999 / Received revision: 16 November 1999 / Accepted: 29 November 1999 相似文献
2.
The availability of high-speed, two-dimensional (2-D) confocal microscopes and the expanding armamentarium of fluorescent probes presents unprecedented opportunities and new challenges for studying the spatial and temporal dynamics of cellular processes. The need to remove subjectivity from the detection process, the difficulty of the human eye to detect subtle changes in fluorescence in these 2-D images, and the large volume of data produced by these confocal microscopes call for the need to develop algorithms to automatically mark the changes in fluorescence. These fluorescence signal changes are often subtle, so the statistical estimate of the likelihood that the detected signal is not noise is an integral part of the detection algorithm. This statistical estimation is fundamental to our new approach to detection; in earlier Ca(2+) spark detectors, this statistical assessment was incidental to detection. Importantly, the use of the statistical properties of the signal local to the spark, instead of over the whole image, reduces the false positive and false negative rates. We developed an automatic spark detection algorithm based on these principles and used it to detect sparks on an inhomogeneous background of transverse tubule-labeled rat ventricular cells. Because of the large region of the cell surveyed by the confocal microscope, we can detect a large enough number of sparks to measure the dynamic changes in spark frequency in individual cells. We also found, in contrast to earlier results, that cardiac sparks are spatially symmetric. This new approach puts the detection of fluorescent signals on a firm statistical foundation. 相似文献
3.
Green fluorescent proteins (GFPs) are widely used in tracing transgene expression and have been known as convenient and efficient
markers for plant transformation. However, sometimes researchers are still puzzled by the weak fluorescence since it makes
the observation of GFP signals and confirmation of transgenic plants difficult. In this investigation, we explored the possibility
of enhancing the weak signals by changing the pH environment of detection and took microplate reader as a more effective instrument
compared to traditional fluorescent microscope to detect the weak signals. It was found that the fluorescence intensity of
enhanced GFP (EGFP) in transgenic plants can be increased 2–6 folds by altering the environmental pH, and the concentration
of EGFP at a large scale (ranged from 20 ng/ml to 20 μg/ml) can be detected and quantified. It can exclude the influence of
degradation fragment and hence facilitate later analysis; these advantages were further verified by comparing with western
blotting and confocal microscopy. It was reliable and effective for the qualitative and quantitative analysis of transgenic
plants and was more suitable for the detection of very weak fluorescent signals. 相似文献
4.
The aim of this study was to develop chitosan-coated and polyplex-loaded liposomes (PLLs) containing DNA vaccine for Peyer’s
patch targeting. Plain liposomes carrying plasmid pRc/CMV-HBs were prepared by the reverse-phase evaporation method. Chitosan
coating was carried out by incubation of the liposomal suspensions with chitosan solution. Main lipid components of liposomes
were phosphatidylcholine/cholesterol. Sodium deoxycholate and dicetyl phosphate were used as negative charge inducers. The
zeta potentials of plain liposomes were strongly affected by the pH of the medium. Coating with chitosan variably increased
the surface charges of the liposomes. To increase the zeta potential and stability of the liposome, chitosan was also used
as a DNA condensing agent to form a polyplex. The PLLs were coated with chitosan solution. In vivo study of PLLs was carried out in comparison with chitosan-coated liposomes using plasmid encoding green fluorescence protein
as a reporter. A single dose of plasmid equal to 100 μg was intragastrically inoculated into BALB/c mice. The expression of
green fluorescence protein (GFP) was detected after 24 h using a confocal laser scanning microscope. The signal of GFP was
obtained from positively charged chitosan-coated liposomes but found only at the upper part of duodenum. With chitosan-coated
PLL540, the signal of GFP was found throughout the intestine. Chitosan-coated PLL demonstrated a higher potential to deliver
the DNA to the distal intestine than the chitosan-coated liposomes due to the increase in permanent positive surface charges
and the decreased enzymatic degradation. 相似文献
5.
Jinwoo Lee Yukihiro Miyanaga Masahiro Ueda Sungchul Hohng 《Biophysical journal》2012,103(8):1691-1697
There is no confocal microscope optimized for single-molecule imaging in live cells and superresolution fluorescence imaging. By combining the swiftness of the line-scanning method and the high sensitivity of wide-field detection, we have developed a, to our knowledge, novel confocal fluorescence microscope with a good optical-sectioning capability (1.0 μm), fast frame rates (<33 fps), and superior fluorescence detection efficiency. Full compatibility of the microscope with conventional cell-imaging techniques allowed us to do single-molecule imaging with a great ease at arbitrary depths of live cells. With the new microscope, we monitored diffusion motion of fluorescently labeled cAMP receptors of Dictyostelium discoideum at both the basal and apical surfaces and obtained superresolution fluorescence images of microtubules of COS-7 cells at depths in the range 0–85 μm from the surface of a coverglass. 相似文献
6.
Most current superresolution (SR) microscope techniques surpass the diffraction limit at the expense of temporal resolution, compromising their applications to live-cell imaging. Here we describe a new SR fluorescence microscope based on confocal microscope optics, which we name the spinning disk superresolution microscope (SDSRM). Theoretically, the SDSRM is equivalent to a structured illumination microscope (SIM) and achieves a spatial resolution of 120 nm, double that of the diffraction limit of wide-field fluorescence microscopy. However, the SDSRM is 10 times faster than a conventional SIM because SR signals are recovered by optical demodulation through the stripe pattern of the disk. Therefore a single SR image requires only a single averaged image through the rotating disk. On the basis of this theory, we modified a commercial spinning disk confocal microscope. The improved resolution around 120 nm was confirmed with biological samples. The rapid dynamics of microtubules, mitochondria, lysosomes, and endosomes were observed with temporal resolutions of 30–100 frames/s. Because our method requires only small optical modifications, it will enable an easy upgrade from an existing spinning disk confocal to a SR microscope for live-cell imaging. 相似文献
7.
Lipofectamine 2000 is commonly used for siRNA transfections. However, few studies have examined cellular responses to this
delivery system. The purpose of this study is to evaluate the effect of siRNA transfection using Lipofectamine 2000 on cellular
autophagy. Huh7.5 cells, stably transfected to express GFP–LC3, were treated with Lipofectamine 2000/negative control siRNA
(NC siRNA) complexes. At different time points after treatment, cells were lysed and analyzed by immunoblotting and fluorescence
spectroscopy. Cells were also observed using confocal microscopy. An increase of endogenous LC3 lipidation, GFP–LC3 fluorescence,
and autophagosomal puncta was observed in cells treated with Lipofectamine 2000/NC siRNA complexes. The kinetics of the increase
of GFP–LC3 fluorescence correlated with the concentration of NC siRNA transfected, where 50, 100, and 200 nM NC siRNA caused
a significant increase at 72, 48, and 24 h, respectively, after transfection. A similar effect on the GFP–LC3 signal was also
observed for cells treated with Lipofectamine 2000 complexed with two other NC siRNAs. The effects were also confirmed in
another hepatoma cell line, H4IIE, by immunoblotting. Lipofectamine 2000-mediated transport of NC siRNAs led to an increase
of autophagosomes in a dose- and time-dependent manner. Thus, this effect on cells should be taken into consideration when
using this approach for intracellular delivery of siRNA. 相似文献
8.
In this article, we report a new type of fluorescence confocal microscope: frequency division multiplexed multichannel fluorescence confocal microscope, in which we encode the spatial location information into the frequency domain. In this microscope, the exciting laser beam is first split into multiple beams and each beam is modulated at a different frequency. These multiple beams are focused at different locations of the target to form multiple focal points, which further generate multiple fluorescent emission spots. The fluorescent emissions from different focal points are also modulated at different frequencies, because the exciting beams are modulated at different frequencies (or difference carrier frequency). Then, all the fluorescent emissions (modulated at different frequencies) are collected together and detected by a highly sensitive, large-dynamic-range photomultiplier tube. By demodulating the detected signal (i.e., via the Fourier transform), we can distinguish the fluorescent light emitted from the different locations by the corresponding carrier frequencies. The major advantage of this unique fluorescence confocal microscope is that it not only has a high sensitivity because of the use of photomultiplier tube but also can get multiple-point data simultaneously, which is crucial to study the dynamic behavior of many biological process. As an initial step, to verify the feasibility of the proposed multichannel confocal microscope, we have developed a two-channel confocal fluorescence microscope and applied it to study the dynamic behavior of the changes of the calcium ion concentration during the single cardiac myocyte contraction. Our preliminary experimental results demonstrated that we could indeed realize multichannel confocal fluorescence microscopy by utilizing the frequency division multiplexed microscope, which could become an effective tool to study the dynamic behavior of many biological processes. 相似文献
9.
Fluorescence and confocal laser scanning microscopy imaging of elastic fibers in hematoxylin-eosin stained sections 总被引:2,自引:0,他引:2
Hernandes Faustino de Carvalho Sebastião Roberto Taboga 《Histochemistry and cell biology》1996,106(6):587-592
We have studied the possibility of associating fluorescence microscopy and hematoxylin-eosin staining for the identification
of elastic fibers in elastin-rich tissues. Elastic fibers and elastic laminae were consistently identified by the proposed
procedure, which revealed itself to be easy and useful for the determination of such structures and their distribution. The
fluorescence properties of stained elastic fibers are due to eosin staining as revealed by fluorescence analysis of the dye
in solution, with no or only minor contribution by the elastin auto-fluorescence. The main advantage of this technique resides
in the possibility of studying the distribution of elastic fibers in file material without further sectioning and staining.
The use of the confocal laser scanning microscope greatly improved the resolution and selectivity of imaging elastic fibers
in different tissues. The determination of the three-dimensional distribution and structure of elastic fiber and laminae using
the confocal laser scanning microscope was evaluated and also produced excellent results.
Accepted: 28 August 1996 相似文献
10.
Ren Siegmund Frank Werner Stefan Jakobs Claudia Geisler Alexander Egner 《Biophysical journal》2021,120(16):3303-3314
Fluorescence microscopy is an excellent tool to gain knowledge on cellular structures and biochemical processes. Stimulated emission depletion (STED) microscopy provides a resolution in the range of a few 10 nm at relatively fast data acquisition. As cellular structures can be oriented in any direction, it is of great benefit if the microscope exhibits an isotropic resolution. Here, we present an isoSTED microscope that utilizes water-immersion objective lenses and enables imaging of cellular structures with an isotropic resolution of better than 60 nm in living samples at room temperature and without CO2 supply or another pH control. This corresponds to a reduction of the focal volume by far more than two orders of magnitude as compared to confocal microscopy. The imaging speed is in the range of 0.8 s/μm3. Because fluorescence signal can only be detected from a diffraction-limited volume, a background signal is inevitably observed at resolutions well beyond the diffraction limit. Therefore, we additionally present a method that allows us to identify this unspecific background signal and to remove it from the image. 相似文献
11.
Tatsuhiko Kataoka Maiko Mori Tomoko M. Nakanishi Satoshi Matsumoto Akira Uchiumi 《Journal of plant research》1997,110(3):305-309
We present highly sensitive aluminum detection method in root using fluorescent lumogallion. Roots treated with 100 μM AlCl3 including 0.2 mM CaCl2 (pH 4.5) were stained for 60 min with 10 μM lumogallion fluorescence solution and fluorescence from aluminum complex in root
was observed under confocal laser microscope. There was a good correlation between the intensity of fluorescence and aluminum
content. When the amount of aluminum lost during each step in staining process was measured, it was found that about 10% of
aluminum was lost only at staining stage. Through lumogallion staining method, aluminum accumulation especially at an early
stage of aluminum treatment in root was shown. At the beginning (2 hr), aluminum began to be accumulated in root cap. After
4 hr treatment, the aluminum distribution was spread to about 3 mm from root apex in the root cap and outer cortex. When aluminum
was found in the outer cortex in 3–5 mm from the root apex, the viability was tended to be decreased in the same area (6 hr).
At the same time, aluminum amount in meristem was increased. However the comparison of lumogallion staining method with that
of morin, which has been widely used to detect aluminum in root, the sensitivity of lumogallion method was found to be much
higher. 相似文献
12.
Luca M. Neri Caterina Cinti Spartaco Santi Marco Marchisio Silvano Capitani Nadir M. Maraldi 《Histochemistry and cell biology》1997,107(2):97-104
DNA sequences digested by HaeIII and reconstructed by in situ nick translation employing digoxigenin-labelled nucleotides are usually revealed either by
horseradish peroxidase or FITC fluorescence. To obtain a significant improvement in terms of resolution, sensitivity and specificity,
colloidal gold has been used instead of FITC (as the reporter molecule) to reveal the labelled DNA. Colloidal gold and propidium
iodide were visualised by employing the reflectance mode and the 488-nm laser line of a confocal laser scanning microscope.
In chromosomes, the fluorescent reaction pattern showed diffuse areas of labelling in which it was impossible to identify
any specific kind of banding along the arms. In some chromosomes and, in particular, 1 and 9, a C-negative banding due to
the negativity of the centromeric areas was seen. A more accurate localisation on chromosomes, including telomeric regions,
often organised in spot pairs that resembled an R-like banding, was detected using 1-nm colloidal gold. A fine labelling was
also demonstrated in nuclei, especially at their peripheral heterochromatin. The non-fading properties of colloidal gold combined
with visualisation by reflectance confocal laser scanning microscopy demonstrated the possibility of obtaining a higher spatial
resolution than when using conventional fluorophores or higher laser wavelength. This improved way to study the localization
of HaeIII digestion sites in single chromosomes and in interphase nuclei made the reaction a valuable tool for the detection of
antigens or of specific DNA sequences in biological preparations.
Accepted: 5 September 1996 相似文献
13.
Two Pichia pastoris cell surface display vectors were constructed. The vectors consisted of the flocculation functional domain of Flo 1p with
its own secretion signal sequence or the α-factor secretion signal sequence, a polyhistidine (6×His) tag for detection, an
enterokinase recognition site, and the insertion sites for target proteins. Adenoregulin (ADR) is a 33-amino-acid antimicrobial
peptide isolated from Phyllomedusa bicolor skin. The ADR was expressed and displayed on the Pichia pastoris KM71 cell surface with the system reported. The displayed recombinant ADR fusion protein was detected by fluorescence microscopy
and confocal laser scanning microscopy (CLSM). The antimicrobial activity of the recombinant adenoregulin was detected after
proteolytic cleavage of the fusion protein on cell surface. The validity of the Pichia pastoris cell surface display vectors was proved by the displayed ADR. 相似文献
14.
We have developed a method for measurement of plasma membrane water permeability (P
f) in intact cells using laser scanning confocal microscopy. The method is based on confocal recording of the fluorescence
intensity emitted by calcein-loaded adherent cells during osmotic shock. P
f is calculated as a function of the time constant in the fluorescence intensity change, the cell surface-to-volume ratio and
the fractional content of the osmotically active cell volume. The method has been applied to the measurement of water permeability
in MDCK cells. The cells behaved as linear osmometers in the interval from 100 to 350 mosM. About 57% of the total cell volume
was found to be osmotically inactive. Water movement across the plasma membrane in intact MDCK cells was highly temperature
dependent. HgCl2 had no effect on water permeability, while amphotericin B and DMSO significantly increased P
f values. The water permeability in MDCK cells transfected with aquaporin 2 was an order of magnitude higher than in the intact
MDCK cell line. The water permeability of the nuclear membrane in both cell lines was found to be unlimited. Thus the intranuclear
fluid belongs to the osmotically active portion of the cell. We conclude that the use of confocal microscopy provides a sensitive
and reproducible method for measurement of water permeability in different types of adherent cells and potentially for coverslip-attached
tissue preparations.
Received: 12 June 1999 / Revised version: 21 February 2000 / Accepted: 25 February 2000 相似文献
15.
M. Aubele Horst Zitzelsberger Sandor Szücs Martin Werner Herbert Braselmann Peter Hutzler Karsten Rodenacker Lars Lehmann Günter Minkus Heinz Höfler 《Histochemistry and cell biology》1997,107(2):121-126
Interphase fluorescence in situ hybridization (FISH) was performed on 15-μm-thick paraffin sections from prostatic carcinomas
using a chromosome 7-specific α-satellite DNA probe. A confocal laser scanning microscope (CLSM) was used for optical sectioning
of the thick sections and reconstruction of 3D images. The number of FISH signals was determined by a gallery of optical sections
evaluating only complete nuclei. To investiate the influence of section thickness and truncation and nuclei on scoring results,
we compared the FISH data from 15-μm sections with signal counts obtained from 5-μm sections. The latter were evaluated by
conventional fluorescence microscopy in the same tumor regions previously defined and marked on the slides. After statistical
analysis of spot frequencies in tumor and non-tumorous cells (χ2 test), we transferred the signal frequencies into a cytogenetic classification (−7, +7, polysomy 7). Based on this classification,
most cases showed more than one chromosome 7 aberration type. Trisomy 7 (+7) became apparent in 15-μm-thick sections in all
19 tumors, polysomy 7 (>3 spots) in 18/19 cases, and monosomy 7 (−7) in 13/19 cases. In 5-μm sections, however, trisomy 7
and polysomy 7 were found in only 7/19 and 13/19 cases, respectively, and monosomy 7 in 7/19 cases. When comparing the classification
results of tumor cells of the same tumor regions originating either from 5-μm or 15-μm sections, the following discrepancies
were noted: in 15-μm sections exclusively, in 12/19 tumors, trisomy 7 was found; in 6/19 cases, polysomy 7; in 8/19 cases,
monosomy 7. The high proportion of cases with tumor nuclei expressing only one hybridization signal of chromosome 7 in 15-μm
sections could be confirmed as monosomy 7 in five selected cases by double-hybridization using centromere-specific probes
for chromosomes 7 and 12. These results demonstrate that numerical chromosome 7 aberrations are more frequently observed in
thick (15-μm) paraffin-embedded tissue sections by evaluating only complete nuclei. The use of routine sections (5-μm) for
interphase cytogenetic analyses is compromised by a remarkable underestimation of the real chromosome copy numbers.
Accepted: 7 November 1996 相似文献
16.
Image correlation spectroscopy. II. Optimization for ultrasensitive detection of preexisting platelet-derived growth factor-beta receptor oligomers on intact cells. 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Previously we introduced image correlation spectroscopy (ICS) as an imaging analog of fluorescence correlation spectroscopy (FCS). Implementation of ICS with image collection via a standard fluorescence confocal microscope and computer-based autocorrelation analysis was shown to facilitate measurements of absolute number densities and determination of changes in aggregation state for fluorescently labeled macromolecules. In the present work we illustrate how to use ICS to quantify the aggregation state of immunolabeled plasma membrane receptors in an intact cellular milieu, taking into account background fluorescence. We introduce methods that enable us to completely remove white noise contributions from autocorrelation measurements for individual images and illustrate how to perform background corrections for autofluorescence and nonspecific fluorescence on cell population means obtained via ICS. The utilization of photon counting confocal imaging with ICS analysis in combination with the background correction techniques outlined enabled us to achieve very low detection limits with standard immunolabeling methods on normal, nontransformed human fibroblasts (AG1523) expressing relatively low numbers of platelet-derived growth factor-beta (PDGF-beta) receptors. Specifically, we determined that the PDGF-beta receptors were preaggregated as tetramers on average with a mean surface density of 2.3 clusters micrometer(-2) after immunolabeling at 4 degreesC. These measurements, which show preclustering of PDGF-beta receptors on the surface of normal human fibroblasts, contradict a fundamental assumption of the ligand-induced dimerization model for signal transduction and provide support for an alternative model that posits signal transduction from within preexisting receptor aggregates. 相似文献
17.
Guowei Lu Franck H. Lei Jean-François Angiboust Michel Manfait 《European biophysics journal : EBJ》2010,39(5):855-860
A fiber-tip-based near-field fluorescence correlation spectroscopy (FCS) has been developed for confining the detection volume
to sub-diffraction-limited dimensions. This near-field FCS is based on near-field illumination by coupling a scanning near-field
optical microscope (SNOM) to a conventional confocal FCS. Single-molecule FCS analysis at 100 nM Rhodamine 6G has been achieved
by using bare chemically etched, tapered fiber tips. The detection volume under control of the SNOM system has been reduced
over one order of magnitude compared to that of the conventional confocal FCS. Related factors influencing the near-field
FCS performance are investigated and discussed in detail. In this proof-of-principle study, the preliminary experimental results
suggest that the fiber-tip-based near-field FCS might be a good alternative to realize localized analysis at the single-molecule
level. 相似文献
18.
Mutations in presenilin 1 (PS1) gene are closely associated with the early onset of familial Alzheimer’s disease (EOFAD).
The fusion genes, GFPPS1 (recombinant plasmid pEGFP-C1-PS1) and PS1-GFP (recombinant plasmid pEGFP-N2-PS1) were constructed
to study the subcellular localization of PS1 holoprotein. Recombinant plasmids were transiently transfected into two cell
lines, HEK293 and CHO, respectively, using the green fluorescence from GFP (green fluorescence protein) as the PS1 localization
signal. Then, we observed green fluorescence with a SPOT II (Olympus, BH2) and CONFOCAL microscope (Olympus, FV300) under
488 nm. The results show that PS1 located on the nuclear envelope. A few can be found on the cellular membrane and in the
cytosol in a non-homogeneous distribution.
__________
Translated from China Biotechnology, 2006, 26(6): 17-22 [译自: 中 国生物工程杂志] 相似文献
19.
Carlos J. Baier Cristina E. Gallegos Valeria Levi Francisco J. Barrantes 《European biophysics journal : EBJ》2010,39(2):213-227
Nicotinic acetylcholine receptor (AChR) function and distribution are quite sensitive to cholesterol (Chol) levels in the
plasma membrane (reviewed by Barrantes in J Neurochem 103 (suppl 1):72–80, 2007). Here we combined confocal fluorescence recovery after photobleaching (FRAP) and confocal fluorescence correlation spectroscopy
(FCS) to examine the mobility of the AChR and its dependence on Chol content at the cell surface of a mammalian cell line.
Plasma membrane AChR exhibited limited mobility and only ~55% of the fluorescence was recovered within 10 min after photobleaching.
Depletion of membrane Chol by methyl-β-cyclodextrin strongly affected the mobility of the AChR at the plasma membrane; the
fraction of mobile AChR fell from 55 to 20% in Chol-depleted cells, whereas Chol enrichment by methyl-β-cyclodextrin-Chol
treatment did not reduce receptor mobility at the cell surface. Actin depolymerization caused by latrunculin A partially restored
receptor mobility in Chol-depleted cells. In agreement with the FRAP data, scanning FCS experiments showed that the diffusion
coefficient of the AChR was about 30% lower upon Chol depletion. Taken together, these results suggest that membrane Chol
modulates AChR mobility at the plasma membrane through a Chol-dependent mechanism sensitive to cortical actin. 相似文献