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Pattern of activity of nucleolus organizers during spermatogenesis in mammals as analyzed by silver-staining.

Silver-staining in the nuclei and chromosomes of spermatogenesis of four species of mammals (Man, Mus musculus, Rattus norvegicus, and Cavia cobaya) was investigated qualitatively and quantitatively. These species show a very similar pattern of activity of the nucleolus organizer regions (NORs) during the various stages of spermatogenesis. Silver precipitates are detectable in growing spermatogonia and up until the pachytene stage of meiotic prophase. During the meiotic metaphases I and II and during interkinesis silver-stainability disappears completely. A resumpton of silver-stainability occurs in round spermatids indicating a postmeiotic reactivation of NORs. This process does not persist beyond the early elongation phase. The quantitative determination of the silver-covered areas in relation to the total nuclear areas reveals minor differences between the species investigated with regard to the times and extents of maximum activation. The known localizations of the NORs in the karyotypes of the species investigated was confirmed using metaphase-preparations derived from somatic tissues.

Animals↗

Sequential silver staining and hybridization in situ on nucleolus organizing regions in human cells.

Chromosome preparations from eight individuals were first stained with silver nitrate to reveal the nucleolus organizing regions (NORs) and then hybridized in situ with ribosomal RNA. In six individuals the size of the silver-staining regions was positively correlated with the amount of label present after hybridization in situ. Thus the variation in silver-staining intensity among chromosomes was largely explained by variation in the number of rDNA gene copies per NOR. However, in two individuals this correlation was absent, suggesting that other factors can also influence the size of the silver-staining region.

Chromosome Banding↗

Fine silver staining analysis of the nucleolar organizer regions during oogenesis in Penaeus kerathurus (Crustacea, Decapoda).

In previtellogenic oocytes, nucleoli showed segregated components, with the dense fibrillar component (DFC) appearing highly developed and presenting several fibrillar centers (FC). The granular component (GC) was less developed and formed a wide-spaced reticulum. Only the DFC appeared stained by silver, with higher intensities being found at its periphery. During early vitellogenesis, the nucleolar components were kept segregated but both the DFC and the GC enlarged, without evident changes being noticed in the silver staining pattern. In mid and late vitellogenesis, the nucleoli showed integrated components, with the DFC being intermeshed with the GC. Both nucleolar components were highly developed, no evident FC were noticed, and silver stained the DFC in a heterogeneous pattern. During cortical vesicle formation, the nuclear chromatin condensed and nucleoli appeared disintegrated, showing high levels of accelerated exportation of silver stained materials. Results suggest that the size of the DFC is kept high and the size of the GC kept low (low rDNA transcription levels and RNP exportation accelerated), in the segregated nucleoli of the previtellogenic oocyte, as the cell stores nuages but shows absence of rough endoplasmic reticulum and thus low protein svnthesis; that the size of the DFC and of the GC is increased in the segregated nucleoli of early vitellogenic oocytes (intermediate levels of rDNA transcription and of protein synthesis), which is in accordance with the appearance of the rough endoplasmic reticulum and of yolk vesicles formed with endogenous and exogenous sources; that during mid and late vitellogenesis the DFC and the GC appear highly developed and integrated (high levels of rDNA transcription and of protein synthesis) as the rough endoplasmic reticulum expands and the large yolk vesicles grow by endogenous synthesis; and that chromatin condense and nucleoli disintegrate (very low levels of rDNA transcription with accelerated RNP exportation) when cortical vesicles are formed.

Animals↗

Comparative study on rapid dot-immunogold staining and two immunogold silver staining assays for diagnosing schistosomiasis japonica.

A fast, specific, sensitive, convenient, and economical rapid-dot-immunogold staining (R-Dot-IGS) assay was used to detect serum antibodies in patients infected with Schistosoma japonicum. The soluble egg antigen of Schistosoma japonicum was added onto microspore membrane. After pre-reacting and blocking, the serum to be detected and sheep anti-human IgG labeled with chloroauric acid were added sequentially. The assay took 15 minutes. For comparison, the dot-immunogold silver staining (Dot-IGSS) and rapid micro-volume Dot-IGSS (RM-Dot-IGSS) assay were also performed. The positive rate to detect the serum of schistosomiasis japonica by the R-Dot-IGS, Dot-IGSS and RM-Dot-IGSS assay was 98%, 98% and 100%, respectively. Samples from 50 healthy controls, 10 cases of clonorchiasis, and 10 cases of paragonimiasis showed negative reactions except for one case of clonorchiasis with RM-Dot-IGSS assay. Compared with Dot-IGSS and RM-Dot-IGSS, R-Dot-IGS assay has similar sensitivity and specificity, but the latter is quicker, simpler, and cheaper. Therefore, R-Dot-IGS is strongly recommended for rapid diagnosis of schistosomiasis japonica both in epidemiological study and in the clinic.

Animals↗

Opposite staining effect of two silver-staining techniques on sister chromatids.

Opposite differential staining between sister chromatids was obtained by two silver-staining techniques on chromosomes replicated twice in medium containing 5-bromodeoxyuridine (BrdU) and pretreated with Hoechst plus black light. Both silver-nitrate and silver-carbonate staining were affected by chemical extraction and enzyme digestion of chromosomal proteins. Prestaining of silver nitrate or silver carbonate also blocked the fluorescences of protein dyes. However, removal of chromosomal DNA affected the silver-carbonate but not the silver-nitrate staining; the fluorescences of DNA dyes were blocked by the prestaining of silver carbonate but not silver nitrate. Chromosomal protein labelling was released only slightly and its relative amount between BrdU bifilarly substituted and unifilarly substituted chromatids was unchanged during pretreatment of Hoechst plus black light. We speculate that chromosomal non-histones are the targets for silver-nitrate stain, and DNA-non-histone complexes for silver-carbonate stain.

Animals↗

Silver-staining patterns of mammalian epididymal spermatozoa.

Epididymal spermatozoa from 12 species of mammals were stained using silver nitrate and examined with the light microscope. Silver nitrate differentiates many of the gross morphological features of spermatozoa, including the acrosome, subacrosomal region, perforatorium, postacrosomal sheath, neck, dense outer fibers of the core of the midpiece, annulus, principal piece, and end piece. Silver-staining patterns of spermatozoa reveal both species-specific and strain-specific differences, particularly of the sperm head. The biochemical basis of silver staining may be due in part to the presence of sulfhydryl- and disulfide-rich proteins; however, it cannot be explained entirely by the presence of these moieties. The detail obtained using silver nitrate staining, coupled with the ease and rapidity of the procedure, should be useful to workers in many areas of biological and medical research.

Acrosome↗

Mercury localization in mouse kidney over time: autoradiography versus silver staining.

Several methods of silver staining have been employed to localize mercury in tissue, under the assumption that the techniques represent total Hg, but recent reports have suggested that these stains are specific for a limited fraction of the Hg present in some samples. Magos et al. (1985, Arch. Toxicol. 57, 260-267) hypothesized that the stains actually vary with inorganic mercury content. The purpose of the present study was to compare localization by radiolabeling to localization by one silver stain, the photoemulsion histochemical technique, in tissues prepared to contain a range of levels of total Hg and a range of levels of inorganic Hg. Mice dosed with 8 mg Hg/kg as MeHg were killed 24 hr, 1 week, or 2 weeks after exposure, to allow a decrease in total Hg and an increase in the proportion of demethylated Hg over time. Mice dosed with 4 mg Hg/kg as HgCl2 provided samples in which all the Hg present was in the inorganic form. Atomic absorption of kidneys of mice dosed with MeHg showed that total Hg fell from 55 micrograms/g to 39 to 25 over 2 weeks, while the inorganic fraction climbed from about 2 to 27 to 35%. Grain counts from autoradiographs of 203Hg-labeled sections correlated with total Hg content at +0.88, but silver staining was correlated with inorganic Hg content, appearing only at late termination times in MeHg-exposed animals, but soon after dosing in mice exposed to inorganic Hg. The photoemulsion histochemical technique revealed a substance strictly localized in the proximal tubules, while autoradiographs and grain counts showed total Hg to be present throughout the kidney tissue. These results support the contention that silver stains are selective for inorganic Hg and suggest that the distribution of inorganic Hg, whether introduced experimentally or by gradual demethylation, is different from the distribution of MeHg. If subsequent studies support the association of silver stains with inorganic Hg, it should be possible to localize Hg in histologic sections, distinguishing between organic and inorganic forms, which differ in toxicity.

Animals↗

Identification of nucleolar organizer regions in non-neoplastic and neoplastic hepatocytes by the silver-staining technique.

The silver staining technique to demonstrate nucleolar organizer region (NOR)-associated proteins (AgNORs) was applied to a variety of liver tissues, including chronic persistent hepatitis (CPH), chronic active hepatitis (CAH), liver cirrhosis (LC), liver cell dysplasia (LCD), focal nodular hyperplasia (FNH), adenomatous hyperplasia (AH) and hepatocellular carcinoma (HCC). In the present study, only discrete, easily counted black dots within nuclei and silver-stained nucleolus were counted under a magnification of x400 without oil-immersion objectives. The mean AgNOR counts of HCC and LCD were significantly higher than that of normal hepatocytes, and 77% of cases of LCD and 56% of HCC had mean AgNOR counts more than 2, whereas those in CPH, CAH, LC, FNH and AH were always less than 2 and were not different from that of normal hepatocytes. Among HCC, the mean number of AgNORs increased with the grade of the tumor. However, the AgNOR counts of grade I HCC were always less than 2 and overlapped with those of normal hepatocytes and other benign categories. All cases with mean AgNOR counts of more than 2 turned out to be HCC, except LCD which exhibited characteristic histologic appearances easily distinguished from HCC. These findings suggest that AgNORs could be quantitatively useful in evaluating the grade of HCC, even under routine microscopic examination without oil-immersion objectives, and mean AgNOR counts of more than 2 per nucleus are hallmarks of HCC.

Antigens, Nuclear↗

Immuno gold staining (IGS) and immuno gold silver staining (IGSS) for the identification of the plant pathogenic bacterium Erwinia amylovora (Burrill) Winslow et al.

For the identification of the plant pathogenic bacterium Erwinia amylovora, the immuno gold staining (IGS) and immuno gold silver staining (IGSS) techniques are tested. The IGS and IGSS methods are at least as sensitive an indirect immunofluorescence and require less primary antiserum. Moreover they have the advantage that the preparations can be conserved permanently and unchanged. The preparation of the IGS can be observed with transmitted light or--with considerable better result--using epipolarization microscopy. The IGSS method deserves special attention because of its high contrast in normal brigth field microscopy with transmitted light.

Animals↗

Quantitation of protein and DNA in silver-stained agarose gels.

A silver stain for both proteins and DNA in agarose gels is described. Quantitation of proteins with this stain is possible, with individual proteins exhibiting characteristic responses, as observed with other stains. The advantage of the silver stain over Coomassie blue is its increased (50- to 100-fold) sensitivity, which allows samples containing very low protein concentrations to be analyzed without prior concentration. This silver stain, when applied to DNA, is at least as sensitive as ethidium bromide, and gives a linear response for the type of DNA and fragment sizes studied.

Chemical Phenomena↗

Silver staining in clinical cytogenetics.

Silver staining of human chromosomes at prometaphase or metaphase identifies variants in the stalk (nucleolar organizing) regions of acrocentric chromosomes (Nos. 13, 14, 15, 21, 22). Variants are defined by size, number, and morphology of silver staining areas. They are heritable polymorphisms and have not been associated with clinical abnormalities. However, these variants are useful in clinical cytogenetics, specifically in studies attempting to determine whether genetic material has been gained or lost in chromosomal rearrangements, the origin of chromosomal aberrations, the origin of cells in tissue culture, the chromosomal location of single genes, clonal origin of tumors, the zygosity of twins, and paternity. Some chromosomal aberrations require silver staining for their definition. Because loss of the stalk regions per se is apparently not deleterious, demonstration that chromosomal breaks occurred within this region without concomitant loss or gain of genetic material essential for normal human development provides basis for a good prognosis for the individual with the chromosomal rearrangement resulting from such breakage. The principle underlying most of the other applications is to determine whether variants being compared are identical or dissimilar, and to make inferences from these results (e.g., variants in monozygotic twins should all be identical, whereas in dizygotic twins they are as similar as in any pair of sibs). Silver staining is a valuable technique for special questions in clinical analysis.

Chromosome Aberrations↗

Cytogenetic study of silver-staining NOR in 8-cell-stage mouse blastomeres fused to 1-cell-stage embryos.

Isolated blastomeres from 8- to 16-cell-stage embryos were fused by standard micromanipulatory means with either unfertilized eggs or fertilized or haploid parthenogenetically activated pronuclear-stage embryos. The hybrid eggs/embryos were incubated overnight in the presence of Colcemid until they had entered the first cleavage division. Air-dried chromosome preparations were then stained with silver nitrate in order to detect active nucleolar organizing regions (NOR). While control unfertilized eggs and 1-cell-stage fertilized and parthenogenetically activated embryos showed no evidence of silver-staining NOR-positive regions, the metaphase plates from 8- to 16-cell embryos showed characteristic NOR-positive regions, while their interphase nuclei also showed a characteristic reticular staining appearance. When hybrids between blastomere nuclei and unfertilized eggs were examined, none of the blastomere nuclei entered mitosis. However, when hybrids between blastomere nuclei and fertilized embryos were examined, in two thirds of the embryos, a single blastomere-derived diploid metaphase plate was present in association with two pronuclear-derived haploid metaphase plates. In most instances, the blastomere-derived chromosomes did not display silver-nitrate-staining NOR. Similar findings were observed when the blastomere-derived chromosomes in hybrids between blastomere nuclei and haploid parthenogenetic embryos were analysed. In the majority of cases, when blastomere nuclei remained in interphase, the characteristic silver-nitrate-staining fine reticular material either was not seen, or the nuclear contents were dispersed into clumps of chromatin-like material. Occasionally, the diploid chromosomes in the hybrids displayed morphological abnormalities. Our findings suggest that the cytoplasm of activated (but not nonactivated) 1-cell embryos is capable of influencing the nucleolar activity of the introduced 8- to 16-cell nuclei, effectively erasing from their chromosomes the memory of at least three previous rounds of rRNA synthesis.

Animals↗

A four- to sixfold enhancement in sensitivity for detecting trace proteins in dye or silver stained polyacrylamide gels.

A very simple procedure which enhances sensitivity in visualizing proteins stained by all standard procedures in polyacrylamide gels is described. The process, based on the use of concentrated polyethylene glycol 6000 solutions, produces a conspicuous, reversible, and uniform size reduction of gels. The entity of the reduction depends principally on the polyethylene glycol 6000 concentration and on the acrylamide content of gels. Using an appropriate polyethylene glycol 6000 concentration, it is possible to regulate the final size and then the sensitivity as needed. Depending upon the above conditions it is possible to increase the sensitivity by a factor of 4-6 or more. Reduction of the gel volume by such a factor may eliminate the need for the cumbersome and frequently impossible preconcentration of samples. Besides the Coomassie blue stained gels, silver stained gels may also be treated in a similar manner with a consequent further enhancement in sensitivity. In addition, gels containing radiolabeled materials can be autoradiographed in times proportionally shorter, without significant sacrifice of resolution.

Coloring Agents↗

Applicability of RAPD markers on silver-stained polyacrylamide gels to ascertain genetic diversity in Peripatus acacioi (Peripatidae; Onychophora).

RAPD (random amplification of polymorphic DNA) molecular markers can be utilized for analyzing genetic variability in populations for which only a few or no molecular markers are available. They were used in a study of an endangered species, Peripatus acacioi, found in the Tripuí Ecological Station, in Ouro Preto, MG, Brazil. The ecological station was specifically created to protect this velvet worm species, the first of this group found in Brazil. For an initial evaluation of the genetic diversity of this species, DNA samples from the lobopods of four individuals, collected at random, were analyzed using RAPD. Each reaction was run with a different primer (Operon RAPD 10-mer Kits), totaling 13 primers (OPC2, OPC3, OPC4, OPC6, OPC8, OPC10, OPC11, OPL2, OPL7, OPL11, OPL13, OPL18, and OPL19). Due to the low amplification yield, RAPD fragments were separated in polyacrylamide gels and stained with silver nitrate. Numerous bands were observed. Fifty-five of the amplified bands proved to be reproducible, both in terms of presence and intensity. Among these, 27 were variable and 28 were constant. The average number of bands per gel was 4.2. Nine of the 13 primers tested allowed the identification of constant and variable bands among these four individuals. RAPD analysis of genetic variation using silver-stained polyacrylamide gel electrophoresis provided measures of band sharing among the individuals, and therefore could be used in population genetics studies of P. acacioi.

Animals↗

Silver staining of high molecular weight proteins on large-pore polyacrylamide gels.

A large-pore gel for electrophoresis in the presence of sodium dodecyl sulfate, composed of 2.55% polyacrylamide crosslinked with 2.75% methylenebisacrylamide, is described. This gel has a resolving power for very high molecular weight proteins and can be stained with silver. The gel is suitable for fractionation of factor VIII/von Willebrand factor directly from plasma samples. Visualization by silver staining revealed a series of covalently bound multimers with molecular weights of up to 8 X 10(6). The procedure described should be useful also for studies on other very high molecular weight proteins and nucleic acids.

Acrylamides↗

Application of the chromogenic reaction to conventional silver staining, the Ag-NOR staining and the silver-intensified immunogold technique.

The principle of the chromogenic reaction and the transformation of "black and white" histochemical staining results or immunohistochemical signals to coloured microscopic images is described. The chromogenic reaction was optimized and is, so far, possible with either cyan-blue or magenta-red reaction products. The application of the chromogenic reaction to conventional silver stain was optimal in the Lendrum staining resulting in red or blue stained reticulin fibres. The Ag-NOR staining of the nucleolus organizing region (NOR) could be transformed by the same reaction to coloured reaction products as well as the silver-intensified immunogold technique in immunocytochemistry.

Arthritis, Rheumatoid↗

Detection of cell surface antigens in cryostat sections with immunogold-silver staining.

Immunogold-silver staining was used for the detection of lymphocyte cell surface antigens in cryostat sections of lymphoid tissues. The sections were incubated with monoclonal mouse antibodies and then with colloidal gold-labeled goat anti-mouse antibodies. They were then immersed in a physical developer, counterstained, and mounted. In light microscopy, the tissue architecture was well preserved, and a dark labeling was seen on the positive cells. Optimal labeling conditions were determined. The distribution of the lymphocyte subsets, as defined by a panel of monoclonal antibodies in tonsil and reactive lymph nodes, was similar to that found with a biotin-avidin-horseradish peroxidase method. The monoclonality of the neoplastic cells in lymph nodes of B-cell non-Hodgkin's lymphomas clearly could be demonstrated. The sensitivity of the technic was comparable with that of the biotin-avidin-horseradish peroxidase labeling method. In addition, immunogold-silver labeling was combined with acid phosphatase cytochemistry.

Antibodies, Monoclonal↗