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Tierney ARP, Chin CY, Weiss DS, Rather PN. A LysR-Type Transcriptional Regulator Controls Multiple Phenotypes in Acinetobacter baumannii. Front Cell Infect Microbiol 2021; 11:778331. [PMID: 34805000 PMCID: PMC8601201 DOI: 10.3389/fcimb.2021.778331] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 10/14/2021] [Indexed: 12/03/2022] Open
Abstract
Acinetobacter baumannii is a multidrug-resistant, Gram-negative nosocomial pathogen that exhibits phenotypic heterogeneity resulting in virulent opaque (VIR-O) and avirulent translucent (AV-T) colony variants. Each variant has a distinct gene expression profile resulting in multiple phenotypic differences. Cells interconvert between the VIR-O and AV-T variants at high frequency under laboratory conditions, suggesting that the genetic mechanism underlying the phenotypic switch could be manipulated to attenuate virulence. Therefore, our group has focused on identifying and characterizing genes that regulate this switch, which led to the investigation of ABUW_1132 (1132), a highly conserved gene predicted to encode a LysR-type transcriptional regulator. ABUW_1132 was shown to be a global regulator as the expression of 74 genes was altered ≥ 2-fold in an 1132 deletion mutant. The 1132 deletion also resulted in a 16-fold decrease in VIR-O to AV-T switching, loss of 3-OH-C12-HSL secretion, and reduced surface-associated motility. Further, the deletion of 1132 in the AV-T background caused elevated capsule production, which increased colony opacity and altered the typical avirulent phenotype of translucent cells. These findings distinguish 1132 as a global regulatory gene and advance our understanding of A. baumannii’s opacity-virulence switch.
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Affiliation(s)
- Aimee R P Tierney
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States
| | - Chui Yoke Chin
- Emory Vaccine Center, Atlanta, GA, United States.,Yerkes National Primate Research Center, Atlanta, GA, United States.,Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States.,Emory Antibiotic Resistance Center, Atlanta, GA, United States
| | - David S Weiss
- Emory Vaccine Center, Atlanta, GA, United States.,Yerkes National Primate Research Center, Atlanta, GA, United States.,Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States.,Emory Antibiotic Resistance Center, Atlanta, GA, United States.,Research Service, Department of Veterans Affairs, Atlanta Veterans Affairs (VA) Medical Center, Decatur, GA, United States
| | - Philip N Rather
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, United States.,Research Service, Department of Veterans Affairs, Atlanta Veterans Affairs (VA) Medical Center, Decatur, GA, United States
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2
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Hafeezunnisa M, Sen R. The Rho-Dependent Transcription Termination Is Involved in Broad-Spectrum Antibiotic Susceptibility in Escherichia coli. Front Microbiol 2020; 11:605305. [PMID: 33329496 PMCID: PMC7734253 DOI: 10.3389/fmicb.2020.605305] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/10/2020] [Indexed: 01/19/2023] Open
Abstract
One of the major ways of acquiring multidrug resistance in bacteria is via drug influx and efflux pathways. Here, we show that E. coli with compromised Rho-dependent transcription termination function has enhanced broad-spectrum antibiotic susceptibility, which arises from the inefficient TolC-efflux process and increased permeability of the membrane. The Rho mutants have altered morphology, distinct cell surface, and increased levels of lipopolysaccharide in their outer membrane, which might have rendered the TolC efflux pumps inefficient. These alterations are due to the upregulations of poly-N-acetyl-glucosamine and lipopolysaccharide synthesis operons because of inefficient Rho functions. The Rho mutants are capable of growing on various dipeptides and carbohydrate sources, unlike their WT counterpart. Dipeptides uptake arises from the upregulations of the di-peptide permease operon in these mutants. The metabolomics of the Rho mutants revealed the presence of a high level of novel metabolites. Accumulation of these metabolites in these Rho mutants might titrate out the TolC-efflux pumps, which could further reduce their efficiency. We conclude that the transcription termination factor, Rho, regulates the broad-spectrum antibiotic susceptibility of E. coli through multipartite pathways in a TolC-dependent manner. The involvement of Rho-dependent termination in multiple pathways and its association with antibiotic susceptibility should make Rho-inhibitors useful in the anti-bacterial treatment regimen.
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Affiliation(s)
- Md Hafeezunnisa
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.,Graduate Studies, Manipal Academy of Higher Education, Manipal, India
| | - Ranjan Sen
- Laboratory of Transcription, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
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3
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Abstract
Electron microscopy allows for studying bacterial ultrastructure at high resolutions. Two types of electron microscopes are used for this purpose. The transmission electron microscope allows for access to inner bacterial ultrastructure when imaging ultrathin sections as well as cell wall-attached structures by negative staining, whereas scanning electron microscopy allows for the detection of structures on the bacterial cell surface alone or to study the interplay between pneumococci and their host cells. This chapter deals with recommendations for well-adapted methodologies to examine pneumococcal ultrastructure in detail. Especially, we focus on the preservation of the pneumococcal capsular polysaccharide, which represents an important virulence factor of pneumococci. Since capsules are highly hydrated structures, the introduction of a new fixation protocol involving lysine acetate, ruthenium red, and osmium (LRR fixation) results in a very well-preserved capsular structure in such a way that the amount of capsular material bound on the bacterial surface can be compared within different serotypes. In our method, capsular ultrastructure is preserved without the need for serotype-specific antibodies, which have been used in other studies to preserve the pneumococcal capsule. In addition, the new LRR fixation allows for studying the presence or absence of capsular material during adhesion and invasion of pneumococci on epithelial or endothelial host cells in cell culture experiments.
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Fabre-Gray ACM, Down CJ, Neal CR, Foster RR, Satchell SC, Bills VL. Imaging the placental glycocalyx with transmission electron microscopy. Placenta 2018; 74:59-61. [PMID: 30616903 DOI: 10.1016/j.placenta.2018.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/06/2018] [Accepted: 12/12/2018] [Indexed: 01/01/2023]
Abstract
There is a significant glycocalyx present at the maternal-fetal interface of the human placenta, with increasing evidence to suggest it has an important role in placental function. Glycocalyx is adversely affected by traditional tissue processing and fixation techniques. Using transmission electron microscopy, we present methodologies for reliably imaging and measuring glycocalyx of both the syncytiotrophoblast and fetal capillary endothelium in term healthy placentae. These techniques can be used to study the role of the placental glycocalyx in both health and disease, including pre-eclampsia.
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Affiliation(s)
- Anna C M Fabre-Gray
- Department of Fetal Medicine, St Michael's Hospital, University Hospitals Bristol NHS Foundation Trust, UK
| | - Colin J Down
- Department of Fetal Medicine, St Michael's Hospital, University Hospitals Bristol NHS Foundation Trust, UK; Bristol Renal, Translational Health Sciences, Bristol Medical School, University of Bristol, UK.
| | - Christopher R Neal
- Bristol Renal, Translational Health Sciences, Bristol Medical School, University of Bristol, UK; Wolfson Bioimaging Facility, University of Bristol, UK
| | - Rebecca R Foster
- Bristol Renal, Translational Health Sciences, Bristol Medical School, University of Bristol, UK
| | - Simon C Satchell
- Bristol Renal, Translational Health Sciences, Bristol Medical School, University of Bristol, UK
| | - Victoria L Bills
- Department of Fetal Medicine, St Michael's Hospital, University Hospitals Bristol NHS Foundation Trust, UK
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5
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Borgersen Q, Bolick DT, Kolling GL, Aijuka M, Ruiz-Perez F, Guerrant RL, Nataro JP, Santiago AE. Abundant production of exopolysaccharide by EAEC strains enhances the formation of bacterial biofilms in contaminated sprouts. Gut Microbes 2018; 9:264-278. [PMID: 29543544 PMCID: PMC6219584 DOI: 10.1080/19490976.2018.1429877] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/02/2018] [Accepted: 01/12/2018] [Indexed: 02/03/2023] Open
Abstract
Enteroaggregative E. coli (EAEC) is associated with food-borne outbreaks of diarrhea and growth faltering among children in developing countries. A Shiga toxin-producing EAEC strain of serotype O104:H4 strain caused one of the largest outbreaks of a food-borne infection in Europe in 2011. The outbreak was traced to contaminated fenugreek sprouts, yet the mechanisms whereby such persistent contamination of sprouts could have occurred are not clear. We found that under ambient conditions of temperature and in minimal media, pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both produce high levels of exopolysaccharide structures (EPS) that are released to the external milieu. The exopolysaccharide was identified as colanic acid (CA). Unexpectedly, Shiga-toxin producing EAEC strain 227-11 produced 3-6-fold higher levels of CA than the 042 strain, suggesting differential regulation of the CA in the two strains. The presence of CA was accompanied by the formation of large biofilm structures on the surface of sprouts. The wcaF-wza chromosomal locus was required for the synthesis of CA in EAEC 042. Deletion in the glycosyltransferase wcaE gene abolished the production of CA in 042, and resulted in diminished adherence to sprouts when co-cultured at ambient temperature. In conclusion, this work suggests that copious production of CA may contribute to persistence of EAEC in the environment and suggests a potential explanation for the large Shiga toxin-producing EAEC outbreak in 2011.
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Affiliation(s)
- Quintin Borgersen
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - David T. Bolick
- Center for Global Health, Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA , USA
| | - Glynis L. Kolling
- Center for Global Health, Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA , USA
| | - Matthew Aijuka
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Richard L. Guerrant
- Center for Global Health, Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA , USA
| | - James P. Nataro
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Araceli E. Santiago
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
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Marcellin E, Steen JA, Nielsen LK. Insight into hyaluronic acid molecular weight control. Appl Microbiol Biotechnol 2014; 98:6947-56. [DOI: 10.1007/s00253-014-5853-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 05/22/2014] [Accepted: 05/24/2014] [Indexed: 01/03/2023]
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Lin CY, Su WT, Li LT. Heat-induced antigen retrieval applied in zebrafish: whole-mount in situ immunofluorescence microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2012; 18:493-496. [PMID: 22640961 DOI: 10.1017/s1431927612000141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Whole-mount immunofluorescence technique provides a way to reveal integrated expression patterns of biological molecules in individuals. Well-documented morphological preservation ability in biology makes aldehydes the fixative of choice. Cross-linking among biocomponents and aldehydes is the key for maintaining morphology but masks the biological molecules for immunodetection. This study performs an easily accessible method by applying heat-induced retrieval, which can rescue the antigenicity of the proteins and also enhance the labeling sensitivity of the fluorescence dye in overfixed zebrafish embryos. The results show that the immunoreactivities of antibodies to myosin in the muscles, green fluorescent protein in the blood vessels and the nuclei in the cells can be recovered significantly, and the morphology of the zebrafish embryos, even the fragile mutants, is at the same time well maintained. Therefore, we provide a choice for antigen retrieval, which is effective for whole-mount immunofluorescence microscopy.
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Affiliation(s)
- Chuang-yu Lin
- Department of Chemical Engineering, National Taipei University of Technology, Taipei 106, Taiwan
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Rukke HV, Hegna IK, Petersen FC. Identification of a functional capsule locus in Streptococcus mitis. Mol Oral Microbiol 2011; 27:95-108. [PMID: 22394468 DOI: 10.1111/j.2041-1014.2011.00635.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The polysaccharide capsule of Streptococcus pneumoniae is a hallmark for virulence in humans. In its close relative Streptococcus mitis, a common human commensal, analysis of the sequenced genomes of six strains revealed the presence of a putative capsule locus in four of them. We constructed an isogenic S. mitis mutant from the type strain that lacked the 19 open reading frames in the capsule locus (Δcps mutant), using a deletion strategy similar to previous capsule functional studies in S. pneumoniae. Transmission electron microscopy and atomic force microscopy revealed a capsule-like structure in the S. mitis type strain that was absent or reduced in the Δcps mutant. Since S. mitis are predominant oral colonizers of tooth surfaces, we addressed the relevance of the capsule locus for the S. mitis overall surface properties, autoaggregation and biofilm formation. The capsule deletion resulted in a mutant with approximately two-fold increase in hydrophobicity. Binding to the Stains-all cationic dye was reduced by 40%, suggesting a reduction in the overall negative surface charge of the mutant. The mutant exhibited also increased autoaggregation in coaggregation buffer, and up to six-fold increase in biofilm levels. The results suggested that the capsule locus is associated with production of a capsule-like structure in S. mitis and indicated that the S. mitis capsule-like structure may confer surface attributes similar to those associated with the capsule in S. pneumoniae.
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Affiliation(s)
- H V Rukke
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
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9
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Lünsdorf H, Kristen I, Barth E. Cationic hydrous thorium dioxide colloids--a useful tool for staining negatively charged surface matrices of bacteria for use in energy-filtered transmission electron microscopy. BMC Microbiol 2006; 6:59. [PMID: 16803626 PMCID: PMC1524781 DOI: 10.1186/1471-2180-6-59] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 06/27/2006] [Indexed: 11/25/2022] Open
Abstract
Background Synthesis of cationic hydrous thorium dioxide colloids (ca. 1.0 to 1.7 nm) has been originally described by Müller [22] and Groot [11] and these have been used by Groot to stain acidic glucosaminoglycans for ultrastructure research of different tissues by conventional transmission electron microscopy. Results Synthesis of colloidal thorium dioxide has been modified and its use as a suitable stain of acidic mucopolysaccharides and other anionic biopolymers from bacteria, either as whole mount preparations or as preembedment labels, is described. The differences in stain behavior relative to commonly used rutheniumred-lysine and Alcian Blue™ electron dense acidic stains has been investigated and its use is exemplified for Pseudomonas aeruginosa adjacent cell wall biopolymers. For the first time thorificated biopolymers, i.e. bacterial outer cell wall layers, have been analysed at the ultrastructural level with electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI), leading to excellent contrast and signal strength for these extracellular biopolymers. Conclusion Application of cationic hydrous ThO2 colloids for tracing acidic groups of the bacterial surface and/or EPS has been shown to be rather effective by transmission electron microscopy. Because of its high electron density and its good diffusibility it stains and outlines electro-negative charges within these biopolymers. In combination with ESI, based on integrated energy-filtered electron microscopy (EFTEM) Th-densities and thus negative charge densities can be discriminated from other elemental densities, especially in environmental samples, such as biofilms.
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Affiliation(s)
- Heinrich Lünsdorf
- GBF-National Institute of Biotechnology, Department of Environmental Microbiology, Mascheroder Weg 1, D-38124 Braunschweig, Germany
| | - Ingeborg Kristen
- GBF-National Institute of Biotechnology, Department of Environmental Microbiology, Mascheroder Weg 1, D-38124 Braunschweig, Germany
| | - Elke Barth
- GBF-National Institute of Biotechnology, Department of Environmental Microbiology, Mascheroder Weg 1, D-38124 Braunschweig, Germany
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Hammerschmidt S, Wolff S, Hocke A, Rosseau S, Müller E, Rohde M. Illustration of pneumococcal polysaccharide capsule during adherence and invasion of epithelial cells. Infect Immun 2005; 73:4653-67. [PMID: 16040978 PMCID: PMC1201225 DOI: 10.1128/iai.73.8.4653-4667.2005] [Citation(s) in RCA: 290] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The capsular polysaccharide of Streptococcus pneumoniae represents an important virulence factor and protects against phagocytosis. In this study the amount of capsular polysaccharide present on the bacterial surface during the infection process was illustrated by electron microscopic studies. After infection of A549 cells (type II pneumocytes) and HEp-2 epithelial cells a modified fixation method was used that allowed visualization of the state of capsule expression. This modified fixation procedure did not require the use of capsule-specific antibodies. Visualization of pneumococci in intimate contact and invading cells demonstrated that pneumococci were devoid of capsular polysaccharide. Pneumococci not in contact with the cells did not show alterations in capsular polysaccharide. After infection of the cells, invasive pneumococci of different strains and serotypes were recovered. Single colonies of these recovered pneumococci exhibited an up-to-10(5)-fold-enhanced capacity to adhere and an up-to-10(4)-fold-enhanced capacity to invade epithelial cells. Electron microscopic studies using a lysine-ruthenium red (LRR) fixation procedure or cryo-field emission scanning electron microscopy revealed a reduction in capsular material, as determined in detail for a serotype 3 pneumococcal strain. The amount of polysaccharide in the serotype 3 capsule was also determined after intranasal infection of mice. This study illustrates for the first time the phenotypic variation of the polysaccharide capsule in the initial phase of pneumococcal infections. The modified LRR fixation allowed monitoring of the state of capsule expression of pathogens during the infectious process.
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Affiliation(s)
- Sven Hammerschmidt
- Research Center for Infectious Diseases, University of Würzburg, Röntgenring 11, 97070 Würzburg, Germany.
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Erlandsen SL, Kristich CJ, Dunny GM, Wells CL. High-resolution visualization of the microbial glycocalyx with low-voltage scanning electron microscopy: dependence on cationic dyes. J Histochem Cytochem 2004; 52:1427-35. [PMID: 15505337 PMCID: PMC3957825 DOI: 10.1369/jhc.4a6428.2004] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The microbial glycocalyx is composed of a variety of polyanionic exopolysaccharides and plays important roles in microbial attachment to different substrata and to other cells. Here we report the successful use of low-voltage scanning electron microscopy (LVSEM) to visualize the glycocalyx in two microbial models (Klebsiella pneumoniae and Enterococcus faecalis biofilms) at high resolution, and also the dependence on fixation containing polycationic dyes for its visualization. Fixation in a paraformaldehyde-glutaraldehyde cocktail without cationic dyes was inadequate for visualizing the glycocalyx, whereas addition of various dyes (alcian blue, safranin, and ruthenium red) to the aldehyde cocktail appeared necessary for stabilization. The cationic dyes varied in size, shape, and charge density, and these factors appeared responsible for different phenotypic appearances of the glycocalyx with each dye. These results suggest that aldehyde fixation with cationic dyes for high-resolution LVSEM will be a useful tool for investigation of microbial biofilms as well as investigation of the extent and role of the glycocalyx in microbial attachment to surfaces.
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Affiliation(s)
- Stanley L Erlandsen
- Deptartment of Genetics, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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Dinkla K, Rohde M, Jansen WTM, Kaplan EL, Chhatwal GS, Talay SR. Rheumatic fever-associated Streptococcus pyogenes isolates aggregate collagen. J Clin Invest 2003; 111:1905-12. [PMID: 12813026 PMCID: PMC161421 DOI: 10.1172/jci17247] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2002] [Accepted: 04/15/2003] [Indexed: 11/17/2022] Open
Abstract
Acute rheumatic fever is a serious autoimmune sequel of Streptococcus pyogenes infection. This study shows that serotype M3 and M18 S. pyogenes isolated during outbreaks of rheumatic fever have the unique capability to bind and aggregate human basement membrane collagen type IV. M3 protein is identified as collagen-binding factor of M3 streptococci, whereas M18 isolates bind collagen through a hyaluronic acid capsule, revealing a novel function for M3 protein and capsule. Following in vivo mouse passage, conversion of a nonencapsulated and collagen-binding negative M1 S. pyogenes into an encapsulated, collagen-binding strain further supports the crucial role of capsule in mediating collagen binding. Collagen binding represents a novel colonization mechanism, as it is demonstrated that S. pyogenes bind to collagen matrix in vitro and in vivo. Moreover, immunization of mice with purified recombinant M3 protein led to the generation of anti-collagen type IV antibodies. Finally, sera from acute rheumatic fever patients had significantly increased titers of anti-collagen type IV antibodies as compared with healthy controls. These findings may suggest a link between the potential of rheumatogenic S. pyogenes isolates to bind collagen, and the presence of collagen-reactive autoantibodies in the serum of rheumatic fever patients, which may form a basis for post-streptococcal rheumatic disease. These anti-collagen antibodies may form a basis for poststreptococcal rheumatic disease.
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Affiliation(s)
- Katrin Dinkla
- Department of Microbial Pathogenesis and Vaccine Research, Gesellschaft für Biotechnologische Forschung-German Research Centre for Biotechnology, Braunschweig, Germany
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Fassel TA, Edmiston CE. Bacterial biofilms: strategies for preparing glycocalyx for electron microscopy. Methods Enzymol 2001; 310:194-203. [PMID: 10547793 DOI: 10.1016/s0076-6879(99)10017-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- T A Fassel
- Core Electron Microscope Unit, Scripps Research Institute, La Jolla, California 92037-1027, USA
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Abstract
Ruthenium red, a promising cationic reagent for electron microscopy (EM), has long been an important tool in histology. The reagent was initially used by botanists as a semispecific stain for pectic substances, but it has gradually been embraced by investigators in microbiology and the animal sciences as a stain for anionic glycosylated polymeric substances. Luft developed a reliable method and demonstrated that ruthenium red was a useful reagent for visualizing ultrastructural detail. Many investigators, using modifications of Luft's approach, have identified numerous applications for this important reagent. Ruthenium red has been used to show the ultrastructural detail of bacterial glycocalyces. Strong, sharp and consistent observations of this ultrastructural component of the bacterial cell have given a better understanding its fibrous anionic matrix. Any variations in staining owing to artifactual alteration of the fine delicate ultrastructural features have been overcome by incorporation of diamine lysine into ruthenium red methods, thus providing flexible processing times under less than ideal laboratory sampling conditions. Ruthenium red has broad utility in the biological sciences, and in combination with lysine, it is an excellent EM stain for enhanced visualization of bacterial glycocalyx from culture or from clinical specimens.
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Affiliation(s)
- T A Fassel
- Core Electron Microscope Unit, The Scripps Research Institute, La Jolla, California 92037, USA
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