A Simplified Bacterial Spore Stain

A simplification of the Schaeffer-Fulton spore stain for bacteria is presented. It is shown that omission of the heating step during staining with malachite green resulted in spore stains as good as when the heat was applied. The simplified procedure involves (1) heat fixation of the smear by 20 passages through the flame, (2) staining with saturated aqueous malachite green for 10 minutes, (3) rinsing, and (4) counterstaining with 0.25% aqueous safranin for 15 seconds. The omission of the heating step in staining has obvious advantages, particularly in the classroom.     

细菌芽胞染色方法改进研究

改进微生物学实验教材上介绍的Schaeffer-Fulton氏芽胞染色法。将涂片的初染用水浴蒸汽加热和烘箱加热,通过显微镜观察不同温度下不同染色时间的染色效果。以5%孔雀绿为染色剂,100℃蒸汽加热4m in或80℃蒸汽加热6 m in能达到好的染色效果。改进方法操作简单易行,加热过程不需添加染料,更符合环保要求;将改进的染色方法运用于微生物学实验教学,收到了良好的教学效果。     

Malachite Green: Applications in Electron Microscopy

Incorporation of malachite green into a glutaraldehyde fixative results in enhanced staining of a number of cellular elements. Ribosomes and myofilaments exhibit increased electron density, but cell membranes generally are not stained. In certain tissues, lipid inclusions are uniformly and heavily stained. Other populations of lipid droplets exhibit differential affinity for malachite green, facilitating their division into subclasses. In addition to its function as a dye, malachite green has previously been reported to stabilize lipid elements soluble in aqueous glutaraldehyde. Such a component was observed in the stroma of uterine endometrium. The variety of cell components which exhibit increased contrast after preparation with malachite green suggests that this technique may find widespread application in fine structure studies.     

Malachite green: applications in electron microscopy.

Incorporation of malachite green into a glutaraldehyde fixative results in enhanced staining of a number of cellular elements. Ribosomes and myofilaments exhibit increased electron density, but cell membranes generally are not stained. In certain tissues, lipid inclusions are uniformly and heavily stained. Other populations of lipid droplets exhibit differential affinity for malachite green, facilitating their division into subclasses. In addition to its function as a dye, malachite green has previously been reported to stabilize lipid elements soluble in aqueous glutaraldehyde. Such a component was observed in the stroma of uterine endometrium. The variety of cell components which exhibit increased contrast after preparation with malachite green suggests that this technique may find widespread application in fine structure studies.     

Effect of estrogen on the affinity of malachite green for staining cardiac lipid inclusions in mice

The effect of estradiol-17-beta on lipids of the ventricular myocardium of mice has been studied with a cytochemical technique in which malachite green was added to glutaraldehyde. This malachite green-glutaraldehyde fixative enhances the visualization of certain phospholipid-related elements. Estrogen induces an affinity of ventricular cardiac lipid inclusions for the cationic dye malachite green. The staining affinity is evidenced only in the estrous female, not in diestrus. In oophorectomized animals, malachite green staining is seen only following estradiol injection, but this effect is blocked by progesterone. In the male, ventricular lipids do not stain, nor do they develop malachite green affinity with estrogen stimulation. These results imply a blockade of the estradiol-mediated dye affinity by progesterone and testosterone. This reinforces the concept of the heart as a target organ for sex steroids and expands the previously described estrogen effects on myocardium.     

Selective extraction, concentration, and assay of orthophosphate from microliter quantities of cultured mammalian cells

A colorimetric procedure is described for determination of orthophosphate (0.2-2.5 nmol) in sample volumes up to 400 microliters. Orthophosphate is selectively extracted (in the form of phosphomolybdate) into an organic solvent mixture (2-methylpropan-1-ol and petroleum spirit) leaving interfering substances, such as labile organic phosphates, in the aqueous phase. Orthophosphate is then back-extracted into a small volume of aqueous sodium hydroxide. By keeping this volume small, orthophosphate from large dilute samples can be concentrated into small volumes and assayed colorimetrically in microcuvettes using the dye malachite green. The procedure is highly reproducible and insensitive to interfering substances, as shown by comparison with a conventional malachite green assay without the solvent extraction.     

Gram staining and lectin binding properties of Myxosporea and Sporozoea

The staining method developed by Christian Gram was introduced as a simple and highly selective tool for demonstrating myxosporean and coccidian sporogonic stages. When using standard blood staining procedures for those enigmatic parasites it is sometimes difficult to distinguish them from fish host tissue. They clearly exhibit a partial Gram-positive reaction in histological sections, but staining is variable in air dried fish organ imprints. To visualize the Gram-negative background of different host tissue components in histological sections, the conventional safranin counterstain of the Gram protocol may be modified as follows: after application of 2% crystal violet (basic violet 3) and Lugol's solution, sections are stained with 0.1% nuclear fast red-5% aluminum sulfate and 0.35% aniline blue (acid blue 22) dissolved in saturated aqueous picric acid. Replacement of the Gram-specific dye crystal violet with 2% malachite green gave similar results in organ imprints containing myxospores or coccidia, but only in sections containing myxosporea. Staining for 1 min with an aqueous solution of 0.5% malachite green and followed 1 min washing was sufficient for rapidly demonstrating the parasite spores in organ imprints of both myxosores and oocysts. With regard to the role of acid mucopolysaccharides and other carbohydrates in the Gram reaction of spores, alcian blue 8GX staining was compared to the binding of FITC-labeled WGA, GS I and GS II. Each lectin was applied at 20 μl/ml PBS, HEPES for 1 hr. Whereas WGA yielded a nonspecific pattern like the alcian blue staining, GS II resulted in a pattern similar to the Gram staining results. This binding was weak in untreated specimens, but was significantly enhanced when digested first within trypsin overnight in a humid chamber at 37 °C. The binding of GS II to both myxosporidian and coccidian spores suggests that they are both composed of polymers containing N-acetyl-D-glucosamine residues. Furthermore, the results suggest that this hexosamine plays a key role in the Gram reaction.     

Differential staining of cartilage and bone in whole mouse fetuses by alcian blue and alizarin red S

The procedure described by Inouye ('76) for the staining of full-term mouse fetal skeletons has been adapted for use with mouse embryos and fetuses of days 14-18 of gestation. The main adaptations for younger specimens involve a longer time in acetone, in lieu of skinning, and omission of the aqueous KOH step. These adaptations require more time but result in consistently good staining of intact specimens.     

The Use of Buffered Solutions in Staining: Theory and Practice

The importance of pH in staining tissue is emphasized. The effect of pH upon the selectivity and intensity of staining with iron hematoxylin, malachite green, and eosin Y is considered. Many difficulties may be avoided by staining in the higher alcohols and directions are given for the preparation of buffer solutions from pH 1.2-8 in alcohol. The concentration of stains, time of staining, and order of staining are discussed for progressive and regressive staining. At pH 8 in 95% alcohol very few tissues stain with malachite green at a concentration of 1/1000 saturated. At pH 6 most cytoplasmic elements stain with malachite green at a concentration of 1/1000 saturated or with eosin Y at 1/250 saturated. As the pH is lowered more tissue elements stain until the nucleus is completely stained. This behavior is in accord with the theory of chemical combination of dyes with proteins, which states that proteins combine with basic dyes on the basic side of their isoelectric points and with acid dyes on the acid side of their isoelectric points. With hematoxylin stain the pH range is much shorter. A satisfactory hematoxylin stain is composed of 0.1% hematoxylin, 0.1% FeCl₃, and HCl to bring the pH to 1.2-1.6 in 80% alcohol. With this stain, which may be used immediately, the nuclei of most tissues begin to stain at pH 1.2 and much of the cytoplasm will be stained if the pH is raised to 1.4. The shortness of this effective pH range is thought to be due to the dissociation of the hematoxylin-iron-protein complex. The use of different dyes successively at different pH values, such as hematoxylin at 1.3, malachite green at 8, and eosin at 6, permits better differentiation of the tissue elements, and intelligent variations in the staining technic.     

Nanoscale Structural and Mechanical Analysis of Bacillus anthracis Spores Inactivated with Rapid Dry Heating

Effective killing of Bacillus anthracis spores is of paramount importance to antibioterrorism, food safety, environmental protection, and the medical device industry. Thus, a deeper understanding of the mechanisms of spore resistance and inactivation is highly desired for developing new strategies or improving the known methods for spore destruction. Previous studies have shown that spore inactivation mechanisms differ considerably depending upon the killing agents, such as heat (wet heat, dry heat), UV, ionizing radiation, and chemicals. It is believed that wet heat kills spores by inactivating critical enzymes, while dry heat kills spores by damaging their DNA. Many studies have focused on the biochemical aspects of spore inactivation by dry heat; few have investigated structural damages and changes in spore mechanical properties. In this study, we have inactivated Bacillus anthracis spores with rapid dry heating and performed nanoscale topographical and mechanical analysis of inactivated spores using atomic force microscopy (AFM). Our results revealed significant changes in spore morphology and nanomechanical properties after heat inactivation. In addition, we also found that these changes were different under different heating conditions that produced similar inactivation probabilities (high temperature for short exposure time versus low temperature for long exposure time). We attributed the differences to the differential thermal and mechanical stresses in the spore. The buildup of internal thermal and mechanical stresses may become prominent only in ultrafast, high-temperature heat inactivation when the experimental timescale is too short for heat-generated vapor to efficiently escape from the spore. Our results thus provide direct, visual evidences of the importance of thermal stresses and heat and mass transfer to spore inactivation by very rapid dry heating.     

The action of visible radiation on the formation and properties of Saccharomyces ascospores

Summary Light in the blue and green bands of the spectrum inhibited ascospore formation in both Saccharomyces cerevisiae and S. carlsbergensis. Ascospores which were produced failed to stain with malachite green and mature spores formed in the dark lost their staining ability when exposed to light in these bands. It is thought that this is due to an alteration brought about in the molecular organization of the spore wall, so that the damaged walls become permeable to molecules of considerably greater size. Red light was without effect on S. cerevisiae, but stimulated sporulation in S. carlsbergensis. This response seemed to be strictly under the control of the yeast cell, and of a totally different nature from the injurious character of shorter wave lengths.     

A Tribasic Stain for Thin Sections of Plastic-Embedded, OsO4-Fixed Tissues

Thin (0.5-1 μ) sections of plastic-embedded, OsO₄-fixed tissues were attached to glass slides by heating to 70 C for 1 min. A saturated solution combining toluidine blue and malachite green was prepared in ethanol (8% of each dye) or water (4% of each dye). Methacrylate or epoxy sections were stained in the ethanol solution for 2-5 min. The water solution was more effective for some epoxy sections (10-80 min). Epoxy sections could be mordanted by 2% KMnO₄, in acetone (1 min) before use of the aqueous dye, reducing staining time to 5-10 min and improving contrast. Aqueous basic fuchsin (4%) was used as the counter-stain in all cases; staining time varied from 1-30 min depending upon the embedding medium and desired effects, methacrylate sections requiring the least time. In the completed stain, nuclei were blue to violet; erythrocytes and mitochondria, green; collagen and elastic tissue, magenta; and much and cartilage, bright cherry red. Sections were coated with an acrylic resin spray and examined or photographed with an oil-immersion lens.     

Detection of Polyhedra from Insect Virus Diseases on Filter Membranes

Polyhedra filtered directly from the air or from aqueous suspensions by means of Millipore filter membranes, are stained on the membranes as follows: To a microscope slide mount consisting of a small piece of membrane filter on which the polyhedra are retained, are added 1 drop of a 1:4 dilution of saturated aqueous picric acid and 1 drop of staining solution: 0.1 gm of naphthol blue-black, C.I. 246 (Hartman-Leddon Co.) dissolved in a mixture of 98% methanol, 5; distilled water, 4 and glacial acetic acid, 1—parts by volume (Grosset et al. Proc. Soc. Exp. Biol. Med., 97, 72-7, 1958). The slide is placed on a hot plate at 600° C (dull red heat) until evaporation takes place and the filter membrane turns blue. Before the membrane begins to burn, the slide is removed and allowed to cool. For stain-sensitive polyhedra the above procedure is adequate. However, for stain-resistant polyhedra it is sometimes necessary to heat the mount with the picric acid alone, followed by the stain and a second heating. For highly resistant polyhedra it can be necessary to heat the untreated mount, follow with a second heating with double strength picric acid; and follow this with a third heating with stain. Revealing the polyhedra, stained dark lilac-blue or green blue, for bright-field illumination, is effected by clearing the membrane with media such as Euparal, aniline, linseed oil or clove oil. This method is suitable for the detection and observation of polyhedra dispersed in nature. Groups of different size can be separated by graduated pore-size filtration during concentration and purification. Enumeration and morphological studies are thereby facilitated.     

Chemical States of Bacterial Spores: Heat Resistance and Its Kinetics at Intermediate Water Activity

Bacterial spore heat resistance at intermediate water activity, like aqueous and strictly dry heat resistance, is a property manipulatable by chemical pretreatments of the dormant mature spore. Heat resistances differ widely, and survival is prominently nonlogarithmic for both chemical forms of the spore. Log survival varies approximately as the cube of time for the resistant state of Bacillus stearothermophilus spores and as the square of time for the sensitive state. A method for measuring heat resistance at intermediate humidity was designed to provide direct and unequivocal control of water vapor concentration with quick equilibration, maintenance of known spore state, and dispersion of spores singly for valid survivor counting. Temperature characteristics such as z, E(a), and Q(10) cannot be determined in the usual sense (as a spore property) for spores encapsulated with a constant weight of water. Effect on spore survival of temperature induced changes of water activity in such systems is discussed.     

A method for staining pollen tubes in pistil

A quadruple staining procedure has been developed for staining pollen tubes in pistil. The staining mixture is made by adding the following in the order given: lactic acid, 80 ml; 1% aqueous malachite green, 4 ml; 1% aqueous acid fuchsin, 6 ml; 1% aqueous aniline blue, 4 ml; 1% orange G in 50% alcohol, 2 ml; and chloral hydrate, 5 g. Pistils are fixed for 6 hr in modified Carnoy's fluid (absolute alcohol:chloroform:glacial acetic acid 6:4:1), hydrated in descending alcohols, transferred to stain and held there for 24 hr at 45 +/- 2 C. They were then transferred to a clearing and softening fluid containing 78 ml lactic acid, 10 g phenol, 10 g chloral hydrate and 2 ml 1% orange G. The pistils were held there for 24 hr at 45 +/- 2 C, hydrolyzed in the clearing and softening fluid at 58 +/- 1 C for 30 min, then stored in lactic acid for later use or immediately mounted in a drop of medium containing equal parts of lactic acid and glycerol for examination. Pollen tubes are stained dark blue to bluish red and stylar tissue light green to light greenish blue. This stain permits pollen tubes to be traced even up to their entry into the micropyle.     

A Method for Staining Pollen Tubes in Pistil

A quadruple staining procedure has been developed for staining pollen tubes in pistil. The staining mixture is made by adding the following in the order given: lactic acid, 80 ml; 1% aqueous malachite green, 4 ml; 1% aqueous acid fuchsia, 6 ml; 1% aqueous aniline blue, 4 ml; 1 % orange G in 50% alcohol, 2 ml; and chloral hydrate, 5 g. Pistils are fixed for 6 hr in modified Carnoy's fluid (absolute alcohol:chloroform:glacial acetic acid 6:4:1), hydrated in descending alcohols, transferred to stain and held there for 24 hr at 45±2 C They were then transferred to a clearing and softening fluid containing 78 ml lactic acid, 10 g phenol, 10 g chloral hydrate and 2 ml 1% orange G. The pistils were held there for 24 hr at 45±2 C, hydrolyzed in the clearing and softening fluid at 58±1 C for SO min, then stored in lactic acid for later use or immediately mounted in a drop of medium containing equal parts of lactic acid and glycerol for examination. Pollen tubes are stained dark blue to bluish red and stylar tissue light green to light greenish blue. This stain permits pollen tubes to be traced even up to their entry into the micropyle.     

Utilization of unconventional lignocellulosic waste biomass for the biosorption of toxic triphenylmethane dye malachite green from aqueous solution

Biosorption potential of novel lignocellulosic biosorbents Musa sp. peel (MSP) and Aegle marmelos shell (AMS) was investigated for the removal of toxic triphenylmethane dye malachite green (MG), from aqueous solution. Batch experiments were performed to study the biosorption characteristics of malachite green onto lignocellulosic biosorbents as a function of initial solution pH, initial malachite green concentration, biosorbents dosage, and temperature. Biosorption equilibrium data were fitted to two and three parameters isotherm models. Three-parameter isotherm models better described the equilibrium data. The maximum monolayer biosorption capacities obtained using the Langmuir model for MG removal using MSP and AMS was 47.61 and 18.86 mg/g, respectively. The biosorption kinetic data were analyzed using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models. The pseudo-second-order kinetic model best fitted the experimental data, indicated the MG biosorption using MSP and AMS as chemisorption process. The removal of MG using AMS was found as highly dependent on the process temperature. The removal efficiency of MG showed declined effect at the higher concentrations of NaCl and CaCl₂. The regeneration test of the biosorbents toward MG removal was successful up to three cycles.     

Sequential Use of Wright's and Ziehl-Neelsen's Stains for Demonstrating Phagocytosis of Bacterial Spores

Nongerminating spores, germinating spores, and vegetative cells of Clostridium botulinum type A were observed during phagocytosis in the peritoneal fluid of white mice. Since phagocytes are easily ruptured by heat, the method described avoids heating, as this has been employed in conventional spore staining methods. A thin smear of the fluid is air dried on the slide for 2 hr, and stained by Wright's method: stain, 2 min; dilution water, 2 min; and rinsed; then in 0.005% methylene blue for 30 sec, and rinsed. This is followed by Ziehl-Neelsen's stain for 3-4 min and destained with 1: acetone-95% ethanol for 10 sec. The slide is rinsed, and Wright's staining repeated: stain 1 min, dilution 2-3 min; and thereafter washed about 5 ml of Wright's buffer. Blotting and air drying completes the staining. Non-germinating spores stain light red with a red spore wall, germinating spores are deep red throughout, vegetative cells are blue, and leucocytes show a dark purple nucleus and light blue cytoplasm.     

Occurrence of a Highly Heat-Sensitive Spore Subpopulation of Bacillus coagulans STCC 4522 and Its Conversion to a More Heat-Stable Form

The profile of the survival curves, at different heating temperatures, of B. coagulans STCC 4522 sporulated at 52(deg)C has been studied, focusing on the early moments of treatment. A highly heat-sensitive spore subpopulation that includes more than 90% of the total spore population has been found. This heat-sensitive spore fraction was inactivated after 2 s of treatment at 111(deg)C. Its heat resistance was as much as 200-fold lower than that of the heat-resistant spore fraction (D(inf111(deg)C) of 0.01 min for the heat-sensitive spore fraction compared with D(inf111(deg)C) of 2 min for the heat-resistant fraction). The shape of the survival curve at 108.5(deg)C was modified after a sublethal heat shock at 80(deg)C for 3.5 h, resulting in a straight-line survival curve. The temperature of treatment also influenced the shape of the survival curves. The conversion of the highly heat-sensitive spore subpopulation to a more heat-stable form is discussed.     

Method of counterstaining preparations for immunofluorescent studies of the pituitary]

To elucidate nonfluorescent structural elements of the hypophyseal parenchyma for immunofluorescent investigations, properties of some dyes most commonly applied for hypophysis staining have been studied. Such dyes as paraldehide-fuchsin, light green, orange G, chromotrop 2R, hematoxylin, eosin, fuchsin, azocarmin possess their own intensive luminescence and block immunofluorescence completely. Some other dyes (trypan blue, bromthymol blue, aniline blue, malachite green, methyl green) though not blocking immunofluorescence, they do not reveal hypophyseal cellular elements distinctly enough. Good results have been obtained with 0.3% water solution of toluidine blue, 0.5% solution of methylene light blue, methylene blue, as well as with Gram--Weigert's staining and with gallocyanin after Einarson. For special staining of corticotropocytes, the authors recommend 0.1% solution of bromphenol blue in barate buffer, pH 8.2.