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A comparison of silver staining methods for detecting proteins in ultrathin polyacrylamide gels on support film after isoelectric focusing.

The application of silver staining methods to the detection of proteins on ultrathin isoelectric focusing gel systems requires the optimization of many steps in the procedure in order to obtain reproducible staining of proteins with acceptable levels of background. Three different methods which have been reported for detecting proteins by silver staining in sodium dodecyl sulfate-polyacrylamide gel systems were investigated. A major problem with staining ultrathin isoelectric focusing gels was found to be surface staining that was associated with gels cast on support films. A modification of the method of Poehling and Neuhoff (H.-M. Poehling and V. Neuhoff, 1981, Electrophoresis 2, 141-147) was found to give the best results.

Coloring Agents↗

Detection of a few picograms of DNA on polyacrylamide gels by silver staining.

DNA fragments separated on polyacrylamide gels are silver stained in ethanolamine solution. The staining procedure can be completed in 3 1/2 h. Illumination of the gels on a black background increases the sensitivity of detection compared with the usual transillumination. The limit level of detection is 3-5 pg per band with a cross-sectional area of 5 mm2. Five to fifty picograms of DNA may be detected quantitatively by scanning the gels. The method will detect 0.1 to 1 ng per band of low-molecular-weight RNA components.

Animals↗

Light microscope analysis of meiotic prophase chromosomes by silver staining.

A method is described for the silver staining of the synaptonemal complex in surface-spread mammalian spermatocytes for light microscope examination. The method is quick, reliable, of broad applicability, and provides a means of making karyotype analysis at meiotic prophase. Many hundreds of suitable cells can be examined in an average preparation in a relatively short space of time. It has so far been applied only to mammalian spermatocytes, but could be used for karyotype analysis in oocytes of mammals and also applied to gonocytes of non-mammalian species.

Animals↗

Distribution of rDNA in the nucleus of Giardia lamblia: detection by Ag-I silver stain.

OBJECTIVE: To determine whether rDNA of Giardia lamblia forms a nucleolus organizer region (NOR)-like structure and is in a very primitive state. STUDY DESIGN: G lamblia was used as the experimental animal, with Euglena gracilis as the control. The distribution was demonstrated indirectly by the modified Ag-I silver technique, which can specifically indicate the NOR under both light and electron microscopes. RESULTS: In the ultrathin sections of silver-stained Euglena cells, all the silver grains were concentrated in the fibrosa of the nucleolus, while no grains found in the cytoplasm, nucleoplasm, condensed chromosomes or pars granulosa of the nucleus. In the silver-stained Giardia cells, no nucleolus was found; a few silver grains were scattered in the nucleus but were not concentrated in any specific region. CONCLUSION: The distribution of silver grains in G lamblia showed that the transcription of rDNA occurs inside the nucleus, though no nucleolus is present. It is possible that chromosomes are in a very primitive state in diplomonad cells; as each chromosome has few prRNA genes, the transcription is independent of a nucleolus. These results imply that the rDNA of Giardia does not form a NOR-like structure and seems to represent a very primitive state in the evolution of the nucleolus.

Animals↗

The silver staining procedure of sodium dodecyl sulfate-gels may be accelerated by shortening fixation time.

In most silver staining methods the first step in the staining of proteins separated after sodium dodecyl sulfate-polyacrylamide gel electrophoresis is a rather protracted fixation of the gels. Optimum fixation should be short, cause no background staining and effectively immobilize the proteins in the gel without masking the proteins for reaction with the staining solution. Further, the concentration of the fixing compounds should be as low as possible due to the potential toxicity of fixatives. Fixation for only 5 min with mixtures of very low concentrations of formaldehyde and glutaraldehyde in ethanol, or a solution of formaldehyde or glutaraldehyde in picric acid and ethanol, fulfill these demands, provided that the gels were prefixed in ethanol-acetic acid for 10 min. As a consequence of these results a fast and sensitive silver staining procedure is proposed.

Amino Acids↗

Silver staining of nucleic acids. Applications in virus research and in diagnostic virology.

The rapid and sensitive method of silver staining of nucleic acids in polyacrylamide gels is used to visualise double-stranded (ds) and single-stranded (ss) molecules of both DNA and RNA. The binding of silver ions to nucleic acids in gels is stoichiometric and independent of the GC content of ds DNA. Silver staining can be applied to problems in virus research and to the analysis of clinical virus isolates.

DNA, Viral↗

Investigation of immunogold-silver staining by electron microscopy.

Deposition of metallic silver on colloidal gold immunoreagents has been shown to be a very sensitive immunostaining technique capable of detecting low levels of immunoreactivity in tissue sections. Using electron microscopy we have shown that immunolabelling is highest with small sizes of gold which can penetrate sections better and achieve higher densities of particles in the section than larger particles. Chemical permeabilisation of the embedding medium aids the penetration of colloidal gold. The silver enhancement step in immunogold-silver staining was shown to be progressive, allowing optimisation of staining and the selection of the final size of silver deposits required. Some poorly understood features of the technique are rationalised and the additional knowledge gained will aid the wider application of this method.

Animals↗

Cytogenetic peculiarities in the Algerian hedgehog: silver stains not only NORs but also heterochromatic blocks.

Hedgehogs belong to one of the several mammalian taxa in which karyotype differences are based on variations in heterochromatin content. Furthermore, the number and location of nucleolar organizer regions (NORs) can also vary widely. In the present study these cytogenetic features were investigated in the Algerian hedgehog, Erinaceus (Aethechinus) algirus. The heterochromatin and NOR distribution patterns in the karyotype of this species are new among hedgehogs, whereas the euchromatic regions, including their G-band pattern, are similar to those reported by others. In addition, silver staining revealed a cytogenetic feature exclusive to the heterochromatic blocks of E. algirus: their silver staining with standard cytogenetic procedures. Because no similar phenomenon has been described previously in a mammalian species, several hypotheses about the significance and specificity of silver staining to NOR sites are discussed. Finally, the existence of different types of heterochromatin in the species analysed here, lead us to propose that what hedgehogs have inherited from their common ancestor is a mechanism which permits the accumulation of heterochromatin on specific chromosomes, rather than the heterochromatin itself.

Animals↗

Evaluation of a gold-silver staining method for detection and identification of Candida species by light microscopy.

A gold-silver staining procedure was evaluated for detection of Candida species of medical importance. Probes were prepared by coupling lectins or antibodies (polyclonal and monoclonal) directly or indirectly to colloidal gold particles. Structures reacting to these probes were specifically revealed by light microscopy in cells present in infected kidney tissue sections or in isolated yeast cells on glass slides. Definition, contrast and sensitivity were of a high order. Preliminary data showed that it was possible, using discriminating dilutions, to identify cells from different species of the genus Candida, grown in vitro, according to their ability to stain with polyclonal monospecific antisera. The advantages of gold-silver staining compared with other staining procedures currently used in routine mycological laboratories are its sensitivity, good definition, ease and rapidity, and long conservation of reaction. It is suggested that the procedure has applications for research and identification of yeasts in clinical samples.

Candida↗

Signal amplification in immunohistochemistry at the light microscopic level using biotinylated tyramide and nanogold-silver staining.

Signal amplification techniques greatly enhance the sensitivity of immunohistochemical (IHC) and in situ hybridization (ISH) methods. In particular, catalyzed signal amplification (CSA) using labeled tyramide or Nanogold-silver staining is an important signal amplification tool. We have applied a combination of both techniques, as has been introduced for ISH, for a further increase in sensitivity of an IHC method to detect cathepsin B. This lysosomal proteinase can also be expressed extracellularly, particularly in relation to cancer metastasis. Higher sensitivity of the IHC method was needed because existing methods failed to demonstrate cathepsin B protein where cathepsin B activity was found with a fluorescence enzyme histochemical method. Combined CSA and Nanogold-silver staining provided the sensitivity that was required. Moreover, this signal amplification method enabled the use of a 10-fold lower concentration of primary antibody (1 microg/ml). Nonspecific background staining was low provided that endogenous biotin, avidin, and peroxidase were completely blocked. The method was reproducible when all steps, and particularly the silver enhancement step, were rigidly controlled. The method resulted in localization patterns of cathepsin B protein that were in agreement with those of cathepsin B activity in serial sections of rat liver containing colon cancer metastases. We concluded that combined application of CSA and Nanogold-silver staining provides high sensitivity for immunohistochemical methods and that activity localization by an enzyme histochemical method is a very attractive alternative to IHC localization of an enzyme because it is at least as sensitive, it is rapid and simple, and it provides direct information on the function of an enzyme.

Animals↗

[A simple and rapid methods used for silver staining and gel preservation].

This paper introduced the simple and rapid methods of silver staining and gel preservation. It was taken only about 10 and 15 minutes to stain a gel. The background of gel was light, the bands were clear, the sensibility was high and the stabilization was well by the method of silver staining. The gel preservation adopted a method named two-layer transparent plastic paper "Sandwich" which could keep the gel with primitive colors for a long time. The methods were used on PAG checking and SSCP typing of HLA and the results were satisfactory. The set of methods are expected to be widely used in laboratories.

English Abstract↗

Nucleolar silver staining patterns and HLA-DR antigen expression in bronchial epithelial cells in chronic bronchitis.

Bronchial epithelial cells obtained by brush biopsy during fiberoptic bronchoscopy performed in 12 patients with chronic bronchitis and 12 healthy control subjects, were investigated for HLA-DR antigen expression and nucleolar silver staining patterns. In all patients with chronic bronchitis the number of bronchial epithelial cells positive to HLA-DR antigen was highly increased (> 90%), whereas in the controls only a few epithelial cells (< 10%) showed a weak HLA-DR antigen expression. Patients with chronic bronchitis showed an increased lymphocytic reaction compared to the control subjects. Both in the patients with chronic bronchitis and in the healthy controls the number of nucleoli was the same. The number of silver stained dots per nucleus was significantly higher in patients with chronic bronchitis than in the control subjects (7.70 +/- 0.87 as against 5.11 +/- 0.52; p < 0.0001). The intensity of the lymphocytic reaction correlated with the HLA-DR antigen expression and the increase in silver staining (Spearman's r = 0.543; p < 0.01). This indicates the influence of inflammation on the activation of epithelial cells derived from the respiratory tract.

Adult↗

Silver-stained nucleolar organizer regions (AgNORs) as a prognostic value in malignant melanoma.

The nucleolar organizer regions (NORs) are chromosomal loops of DNA and proteins involved in ribosomal synthesis. By silver staining, they can be identified as black dots (AgNORs) in the nuclei. Their size and number reflect cell and nuclear activity. Therefore, AgNOR count may correlate with the proliferative activity of tumors. In malignant melanoma, correlation between AgNOR count and the growth phase was found. However, the value of AgNORs in determining prognosis is disputable. Our purpose was to evaluate the role of AgNORs in predicting the biological behavior of melanoma. Paraffin-embedded sections of 30 cases of primary melanoma, 0.4-5 mm thick (mean, 1.6 mm) were stained with silver. Follow-up of all patients was at least 5 years. For each tumor, at least 50 cells were randomly selected for AgNOR count at a final magnification of 500, and the mean of AgNOR content was calculated. Sample parameters corresponded well to the epidemiology and the natural history of melanoma. AgNOR counts (0.78-4.26; mean, 1.42+/-0.72) correlated with tumor thickness (p = 0.01); thus, most superficial tumors had low AgNOR counts, whereas most deep tumors (> or = 1.5 mm) showed high counts. Patients who had tumors with AgNOR counts lower than the median had longer disease-free interval (DFI) than did patients who had tumors with higher counts (p = 0.02). Furthermore, in a multivariate Cox analysis, AgNOR count was independent of tumor thickness in determining DFI (p = 0.05). Therefore, AgNORs may serve as a parameter to predict more accurately the progression of melanomas (mainly thin ones). Larger studies are needed in order to consolidate these preliminary results and to characterize AgNOR value further as a prognostic factor in melanoma.

Adolescent↗

Satellite associations and silver staining in a case of multiple G and D variants.

Satellite associations and silver staining were analyzed in a normal woman carrying three "s" variants, on chromosomes 13, 21, and 22. Six of the acrocentric chromosomes were identified and a positive correlation between the parameters of satellite association frequency and positive silver staining was found for each chromosome. These parameters seem to depend on the presence and size of a secondary constriction and are unaffected by stallelite size.

Adult↗

A refined method for silver staining of nucleic acids fixed on nitrocellulose.

A refined silver staining method was developed to stain nucleic acids fixed onto nitrocellulose membranes and nylon-based membranes. Approximately 4 ng RNA or DNA can be stained with this method with no protein interference. This method involves simple repetition of immersions of membranes in three solutions prepared from common chemicals. The total staining time is less than 30 min.

Collodion↗

A simple modification of Blum's silver stain method allows for 30 minute detection of proteins in polyacrylamide gels.

A simple and rapid protocol for silver staining of proteins following electrophoresis in polyacrylamide gels (PAGE) is described. We have reduced the number of steps in the procedure of Blum et al. (Electrophoresis (1987) 8, 93-99), and shortened fixation and washing times so that efficient detection of proteins can be achieved within 30 min. In common with more time-consuming silver-staining methods, the present protocol is capable of detecting nanogram quantities of proteins on a colorless background and is suitable for rapid screening of large numbers of samples.

Electrophoresis, Polyacrylamide Gel↗

Silver staining profiles distinguish Pick bodies from neurofibrillary tangles of Alzheimer type: comparison between Gallyas and Campbell-Switzer methods.

Silver staining profiles of Pick bodies (PBs) and their relation to tau-like immunoreactivity were examined on hippocampal sections and compared with those of neurofibrillary tangles of Alzheimer type (NFTs). Pairs of mirror sections were double-fluorolabeled with an anti-paired helical filament tau (AT8) antibody and thiazin red (TR), a fluorochrome that identifies fibrillary structures such as NFTs. One of the paired sections was subsequently stained using the Gallyas method (GAL), and the other using the Campbell-Switzer method (CS). By comparison of the same microscopic field on fluorolabeled sections and on both silver-stained paired sections, four different profiles of each structure could be distinguished: AT8 immunoreactivity, affinity to TR, argyrophilia with GAL or CS staining. PBs, containing mainly three-repeat (3R) tau, were positive for CS but not for GAL and its affinity to TR was, at most, weak. This selective affinity of PBs to CS is in sharp contrast with tau-positive structures of corticobasal degeneration/progressive supranuclear palsy, which are positive for GAL but not for CS, as we reported previously. This contrast is explainable if the argyrophilia with CS is related to deposits containing 3R tau, while that with GAL is linked to those containing four-repeat (4R) tau. Indeed, NFTs, containing both 3R and 4R tau, are positive for both CS and GAL, as expected. Taken together, differences in molecular composition of tau protein in these deposits are linked to their argyrophilic properties that are dependent on the staining method. Although explanations for these empirical differences are not yet available, awareness of this clear distinction is potentially of diagnostic and pathological relevance.

Aged↗