A Five-Hour Variant of Gomori's Methenamine Silver method for Argentaffin Cells

Gomori's methenamine silver method for argentaffin cells has been modified and considerably accelerated by almost doubling the silver concentration and raising the incubation temperature to 60°C. Argentaffin cells are selectively impregnated in 3 to 4 hours and the background remains relatively clear up to 4 hours. The contrasts are clearer than with the ammoniacal silver methods of Masson and of Gluckmann.     

A Five-Hour Variant of Gomori's Methenamine Silver method for Argentaffin Cells

Gomori's methenamine silver method for argentaffin cells has been modified and considerably accelerated by almost doubling the silver concentration and raising the incubation temperature to 60°C. Argentaffin cells are selectively impregnated in 3 to 4 hours and the background remains relatively clear up to 4 hours. The contrasts are clearer than with the ammoniacal silver methods of Masson and of Gluckmann.     

A faithful double stain of proteins in the polyacrylamide gels with Coomassie blue and silver

The conditions for prior fixing of proteins in a gel in order to attain a greater degree of faithful silver staining and sensitivity were examined. Fixing with formaldehyde enhanced the retention of proteins in a gel, particularly basic proteins such as histones and ribosomal proteins. The gel, one stained with Coomassie blue and following the removal of the free dyes, is capable of undergoing silver staining, and, moreover, the prestain considerably enhanced the staining intensity of various proteins differing in basicity in subsequent silver staining. Coupling the formaldehyde fixation with Coomassie brilliant blue prestain afforded a reproducible and pronounced stainability of various proteins.     

Assessing the Environmental Risks of Silver from Clothes in an Urban Area

The environmental risks from the use of silver-containing clothes (“silver clothes”) were assessed for an urban area. First, we evaluated whether the use of silver clothes may cause contamination of wastewater treatment sludge that exceeds certain risk thresholds. Second, we assessed the risk of silver exposure to earthworms from applying the sludge as fertilizer to agricultural land. The most critical parameter was the concentration of silver in silver clothes, for which estimates in the literature vary by more than five orders of magnitude. For concentrations at the high end of that parameter range, there is considerably increased concentration of silver in the sludge, and toxic effects on earthworms even at modest use rates of silver clothes suggest high risk. At the low end, no risks can be expected. The main recommendation from this study is that if silver is used in clothes, the silver concentration must be kept at the lower end of the range applied in this study if risks are to be avoided. This can be done either by design choices of companies, or by regulation. If the function of the applied silver is not maintained at these lower levels, the use of silver clothes should be minimized.     

A simple method of protein determination in polyacrylamide gel using silver staining

A simple and relatively rapid method is elaborated for development of electrophoregram in PAAG by silver binding directly with protein. This permits avoiding the gel staining, considerably improves the quality of staining and promotes better reproducibility of the results. Sensitivity of the method permits detecting 1 ng of protein in the band.     

Modified pyrogallol-initiated immunogold-silver enhancement technique applicable to prokaryotes

A modified immunogold-silver enhancement technique that was designed to reduce the nonspecific granular background staining, particularly for application on prokaryotic organisms, is reported. Aerial oxidation of pyrogallol contained in the commercial silver enhancer solution was effectively controlled during storage and in the reaction mixture. A combination of strategies such as storing the reagent under argon, modifying it using 0.5% (w/v) anhydrous sodium sulfite, reducing the concentration of silver ions in the reaction mixture and limiting the length of the silver enhancement reaction considerably reduced the granular background staining. The modified technique was demonstrated on the bacterium Xanthomonas campestris pv. malvacearum (Smith) Dye. A 7-min silver enhancement step produced little background staining, while optimal silver intensification of the bacterium pre-treated with the immunogold label was achieved.     

Biosynthesis of silver and gold nanoparticles using thermophilic bacterium Geobacillus stearothermophilus

Nanomaterials have assumed a great deal of importance as they often display unique and considerably modified physical, chemical and biological properties as compared to their counterparts of the macroscale. In this study, biogenic synthesis of silver and gold nanoparticles by Geobacillus stearothermophilus has been attempted. The exposure of G. stearothermophilus cell free extract to the metal salts leads to the formation of stable silver and gold nanoparticles in the solution. These nanoparticles were characterized by UV–Vis spectra, FTIR, TEM, and XRD. The silver and gold nanoparticles have absorption maxima at 423 nm and 522 nm respectively. The TEM micrograph revealed the formation of polydispersed particles in the case of silver nanoparticles and monodispersed particles with respect to the gold nanoparticles. High stability of the nanoparticle solution could be attributed to the secretion of certain capping proteins by the bacterium in the reaction mixture. The involvement of these proteins was confirmed by FTIR and SDS PAGE.     

Application of Achillea millefolium extract as a reducing agent for synthesis of silver nanoparticles (AgNPs) on the cotton: antibacterial,antioxidant and dyeing studies

BioMetals - The phyto-synthesis of silver nanoparticles and cotton dyeing with natural colorants can reduce the environmental impact of the process considerably. In this study, the extraction of...     

The incidence of mistletoe (<Emphasis Type="Italic">Viscum album</Emphasis> ssp. <Emphasis Type="Italic">abietis</Emphasis>) on silver fir (<Emphasis Type="Italic">Abies alba</Emphasis>) in Croatia

The research on incidence of mistletoe (Viscum album ssp. abietis) on silver fir (Abies alba) was carried out in natural fir stands in Croatia. In the area of Gorski Kotar 32.8 % of the examined dominant fir trees were infected with mistletoe. The mistletoe incidence was presented according to the damage degrees of silver fir from 0 (healthy trees) to 4 (dead trees), rated by the crown defoliation and needle discoloration. With the increase of incidence, mistletoe spreads more onto more vital, i.e. less damaged trees. In the Dinaric Alps 28.6% of the examined fir trees were infected, this percentage amounting to 27.1% for the mountainous regions between the Sava and Drava rivers. The site and stand parameters (exposure, elevation, site quality, forest community and crown closure) were analysed in order to establish whether there was a correlation between these parameters and mistletoe incidence. There was a negative correlation between the elevation and mistletoe incidence. Among the compartments with a closed stands there were considerably less compartments with higher mistletoe incidence than among compartments with a sparsely closed and understocked stands. The other analysed site and stand parameters individually had no significant influence on mistletoe incidence. The correlation of silver fir mortality in 2004 and mistletoe incidence in 2002/03 was analysed, and their strong correlation was established. Mistletoe could be considered as a bioindicator of silver fir decline, and probably a significant contributor to that decline. In the areas where mistletoe incidence is great it can be presumed that silver fir is significantly damaged.     

Purification of a light-harvesting B880 complex from wild-type Rhodospirillum rubrum

The light-harvesting B880 complex of Rhodospirillum rubrum was purified by a new method which allowed recovery of 66% of the amount present in the crude solubilized extract. Electrophoretic analysis of the isolated complex, followed by either Coomassie brilliant blue or silver staining, revealed only two low-molecular-weight polypeptides. When compared to a previously described preparation, the stability of the complex was considerably increased. In addition, the new procedure yielded B880 of higher purity as evidenced both by the decreased protein to pigment ratio (A280/A880 = 0.4) and by the absence of contaminants previously detected by silver staining or by an immunochemical method in other preparations. The most prominent of those contaminants were identified in this work as lipopolysaccharides of the bacterial outer membrane.     

The ultrasensitive silver "protein" stain also detects nanograms of nucleic acids

The ultrasensitive silver staining procedure developed for proteins also stains nanogram quantities of RNA and DNA in polyacrylamide gels. A gradient polyacrylamide gel system is described which separates proteins from 10⁴ to 10⁶ M_r, RNA from 5S to 23S and DNA from 0.4 to 21 Kb. The sensitivity of nucleic acid silver staining in this gel system considerably exceeds that of commonly used DNA and RNA dye-binding stains.     

Stimulating Effects of Mercuric-and Silver Ions on the Superoxide Anion Production in Human Polymorphonuclear Leukocytes

In a survey of a number of heavy metal ions for effects on the oxidative metabolism (respiratory burst) of human polymorphonuclear leukocytes (neutrophils) we have found that mercury(II) and silver ions in micromolar concentration significantly increase the production of superoxide anions in cells, initiated by formyl-methionyl-leucylphenylalanine (fMLP). The stimulation of radical formation induced by a certain ion concentration varied considerably in cells isolated from different blood donors, from a moderate increase to a very large (up to 400% of control values). When the soluble stimulator phorbol myristate acetate (PMA) or the particulate stimulator Zymosan were used to initiate the cell respiratory burst, no additional stimulating effects by the metal ions on superoxide anion formation were observed. This fact might indicate that the effect of the metal ions on the fMLP-dependent initiation of cell activity is a mechanism coupled to the interaction between the chemotactic peptide and its corresponding receptor molecules on the cell surface.

By increasing the concentration of silver ions during pre-incubation of resting neutrophils, a spontaneous activation of the cells could be recorded at a concentration exceeding 5 μM. However, the silver ion concentration at which such spontaneous initiation of the respiratory burst occurred varied significantly between blood samples from different donors with a concentration range of 5 to 15 μM. This effect could not be shown for mercuric ions due to the toxicity of the metal above 5 μM. Blood samples from some donors contained neutrophils that could be activated by either mercuric- or silver ions at concentration as low at 1 μM.

The spontaneous activation of neutrophils with elevated concentrations of silver ions is kinetically similar to the PMA-induced. The onset of superoxide anion formation is preceeded by a lag period whose length varies in time with the concentration of agent applied to the cells. It is a known fact that once the neutrophils have been activated with fMLP it is not possible to reactivate the cells by a second supplementation of fMLP. However, after cessation of the fMLP-induced activation, addition of PMA or silver ions gives rise to renewed production of superoxide anions.

We propose two different mechanisms of action of silver ions on oxidative metabolism of neutrophils. At a low concentration the metal ions are thought to interact with an activating agent and a corresponding cell surface receptor molecule, while at elevated ion concentrations, we postulate an action like that of phorbol-esters on neutrophils, (i.e., an interaction between activating agent and the enzyme protein kinase C of the cells).     

Absence of nucleolar dominance in mouse-human heterokaryons

Autoradiographic analysis of [³H]uridine incorporation 48 h after polyethylene glycol-mediated cell fusion indicates that nucleolar RNA synthesis persists in both human and mouse nuclei in interspecific heterokaryons. The absence of nucleolar dominance in heterokaryons has been confirmed by zinc-dithizone nucleolus-specific staining, and is true even when there are considerably more nuclei of one species than of the other in the heterokaryon. Studies of actinomycin D-induced nucleolar segregation indicate that the zinc-binding proteins responsible for zinc-dithizone staining are located in a different nucleolar component than the protein responsible for silver staining.     

Raman and surface-enhanced Raman spectroscopy investigation of vasopressin analogues containing 1-aminocyclohexane-1-carboxylic acid residue

In this work, Raman spectroscopy (RS) was employed to characterize molecular structures of [Arg8]vasopressin (AVP) and its [Acc2,D-Arg8]AVP, [Acc3]AVP, and [Cpa1, Acc3]AVP analogues. The RS band assignments have been proposed. To determine the mechanism of adsorption of the above-mentioned compounds adsorbed on a colloidal silver surface, surface-enhanced Raman spectra (SERS) were measured. The SERS spectra were used to determine relative proximity of the adsorbed functional groups of [corrected] investigated peptides and their orientation on the silver surface. The AVP and [Acc3]AVP SERS spectra (Acc: 1-aminocyclohexane-1-carboxylic acid) show that the L-tyrosine (Tyr) lies far from the metal surface, whereas the [Cpa1,Acc3]AVP spectrum (Cpa: 1-mercaptocyclohexaneacetic acid) provides evidence that Tyr interacts with the silver surface. These results suggest that [corrected] the binding of the Tyr-ionized phenolic group might be responsible for the selectivity of the analogues. We show that the aromatic ring of L-phenylalanine (Phe) of AVP and [Acc2,D-Arg8]AVP interacts with the silver surface. The strength of this interaction is considerably weaker for [Acc2,D-Arg8]AVP than for AVP. This might be due either to a longer distance between the Phe ring and the silver surface, or to the almost perpendicular orientation of the Phe ring towards the surface. The carbonyl group of the L-glutamine [corrected] (Gln) or L-asparagine [corrected](Asn) of AVP, [Acc2,D-Arg8]AVP, and [Acc3]AVP is strongly bound to the silver surface. We have also found that all peptides adsorb on the silver surface via sulfur atoms of the disulfide bridge, adopting a "GGG" conformation, except [Cpa1,Acc3]AVP, which accepts a "TGG" geometry.     

A demonstration of the advantages of immunostaining in the quantification of amyloid plaque deposits

Extracellular amyloid deposits are a feature of both Alzheimer type dementia and the 'normal' aging process. Quantification of amyloid plaque deposits may well be useful in distinguishing between the senescent changes associated with 'normal' aging and the pathological processes underlying dementia. To determine the most reliable and reproducible method for visualisation of the amyloid we have compared conventional silver staining techniques with beta-amyloid immunocytochemistry on a large sample of post-mortem brain tissue from both demented (n = 15, age range 60-87) and non-demented (n = 65, age range 14-99) patients. The degree of amyloid deposition was rated on a four point scale and ratings for the two techniques were significantly correlated (P less than 0.01). However, the immunocytochemical approach has a number of distinct advantages for quantification. The antibody to beta-amyloid is highly specific and does not stain neurofibrillary tangles or background features, it is considerably more sensitive than silver staining in highlighting diffuse amyloid deposits and, perhaps most importantly, it produces high contrast staining which allows easier image digitisation and subsequent computer image analysis.     

Two-dimensional gel electrophoretic resolution of the polypeptides of rat liver mitochondria and the outer membrane

The proteins of highly purified rat liver mitochondria were resolved by two-dimensional polyacrylamide gel electrophoresis, and detected by staining with either Coomassie blue or silver. Approximately 250 polypeptides were detected with silver staining which is 2- to 3-times that observed with Coomassie blue. Silver staining was especially more effective than Coomassie blue for detecting polypeptides of less than 50 000 daltons. A two-dimensional gel pattern of rat liver microsomes was distinct from that of the mitochondria. The mitochondrial outer membrane was prepared from purified mitochondria either with digitonin or by swelling in a hypotonic medium. As assessed by marker enzymes, the latter method yielded a considerably purer outer membrane preparation (20-fold purification) than the former (2.6-fold purification). Approximately 50 polypeptides were observed in a two-dimensional gel (pH 3-10) of the highly purified outer membrane fraction. Three isoelectric forms of the pore (VDAC) protein were observed with pI values of 8.2, 7.8 and 7.1. Monoamine oxidase was identified as a polypeptide of Mr 60 000. About 50 polypeptides were also resolved in a reverse polarity non-equilibrium pH gradient electrophoresis gel of the outer membrane, pH 3-10, with at least six isoelectric forms of the VDAC protein observed under these conditions. The six isoforms of the VDAC protein were also observed in a non-equilibrium gel with 2 micrograms of the purified protein.     

Indirect effect of different fish communities on nutrient chlorophyll relationship in shallow hypertrophic water quality reservoirs

Effects of different fish communities on the proportion of different nitrogen and phosphorous forms and the amount of phytoplankton (chlorophyll a) were examined in two consecutive years (1992–1993) in three Hungarian shallow water reservoirs (Cassette and outer reservoir of the Kis–Balaton Water Protection System, and Marcali reservoir). Possible interactions between nutrient concentrations and the amount of phytoplankton in these reservoirs were also examined. Considerable differences in the proportions of different nutrient forms were observed between the three test sites, which could be explained by the presence of different fish stocks in these reservoirs. In the Cassette, the fish biomass necessary for a water quality improvement was around 50 kg ha⁻¹. Phytoplankton biomass was controlled by the zooplankton, consequently chlorophyll a concentrations decreased considerably, while those of dissolved nutrients significantly increased. In the outer reservoir, phytoplankton was controlled bottom-up, since the 250 kg ha⁻¹ fish biomass was larger than the critical value due to the high proportion of planktivorous species. Chlorophyll a concentrations were high, and nutrients were mainly in particulate form (in algal cells). In the Marcali reservoir, the recently introduced silver carp population could not control fully the phytoplankton. The biomass of phytoplankton decreased only slightly, while its composition changed considerably. Although biomanipulation with silver carp is suitable for ceasing cyanobacterial blooms, reduction of the amount of planktivorous fish seems to be a more adequate method for increasing water transparency, rather than introduction of phytoplankton feeding fish.

     

Allelic expression in intergeneric fox hybrids (Alopex lagopus × Vulpes vulpes). III. Regulation of the expression of the parental alleles at the Gpd locus linked to the X chromosome

The electrophoretic pattern of glucose-6-phosphate dehydrogenase (G6PD) was studied in 60 intergeneric fox hybrids (Alopex lagopus × Vulpes vulpes), 33 females and 27 males. It is shown that the structural gene for G6PD, designated Gpd, is located on the X chromosome in both Arctic and silver foxes. Analysis of G6PD patterns in the erythrocytes of hybrid females demonstrated that the phenotypic expression of parental alleles at the Gpd locus varied considerably: from 1:1 to the hemizygous manifestation of an allele of either the Artic or the silver fox. The expression of the parental allels at this locus is different in the various tissues of single female hybrids. It is suggested that the variable quantitative expression of the alleles at the Gpd locus in hybrid females is related to the presence of two cell populations having in an active state either the X chromosome of the Arctic fox or that of the silver fox. It is also proposed that the size of the two cell populations is largely affected by the different relationships between cells having different activated X-chromosomes among initiator (stem) cells from which various definitive organs and tissues develop. The number of initiator cells for erythroid tissue has been calculated to be five or six.     

Sulfide-controlled continuous culture of sulfate-reducing bacteria

In continuous culture set-up for sulfate-reducing bacteria a sulfide electrode (made from silver wire) is used to control the electron donor supply and the medium pump. The sulfied concentration of the medium is kept at a low level by continuosly flushing out H₂S and replacing it with CO₂. The pH is controlled automatically by regulating the CO₂ content of the gas mixture flushed through the medium. With the sulfide-controlled set-up sulfate-reducing bacteria can be grown in chemostat culture under electron donor as well as electron acceptor limitation. Furthermore, by continuously washing out the culture to a preselected residual sulfide concentration, cells can be grown in sulfidostat culture under non-limiting conditions at maximal growth rate. Growth yields of Desulfotmaculum orientis, when growth in this system with hydrogen as electron donor, were considerably higher than previously reported.     

对虾体表共栖纤毛虫一新种——拟恩茨聚缩虫(纤毛动物门:缘毛目)

本文报道了共栖于对虾体表的缘毛类纤毛虫一新种,拟恩茨聚缩虫。通过活体观察,蛋白银法及干银法染色对其形态学,口器结构及银线系做了全面研究,并与相似种做了讨论和比较。