Electron microscopy of cervical, gastric and bronchial mucus glycoproteins

Sheehan, John K.; Oates, K.; Carlstedt, Ingemar

doi:10.1042/bj2390147

Cited by 160 publications

(112 citation statements)

References 17 publications

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“…The images were selected at random and are representative of a large library of images, which portray similar structural information and surface coverage. The PGM appears as long filamentous strands, which is in good agreement with previous studies using electron and scanning tunnelling microscopy [18][19][20][21], and consistent with the swollen coil array\linear random coil model for mucins [4,23]. The characteristic flattened areas along the backbone seen earlier from electron microscopy for PGM and earlier for bronchial mucins [23] were notably absent.…”

Section: Pgm Glycoproteinsupporting

confidence: 90%

“…In order to reveal both the thin filamentous nature of the gastric mucin structure previously shown with transmission electron [ [18][19][20] and scanning tunnelling microscopy [21], together with the previously unvisualized characteristics of chitosan, an extremely flat sample substrate is required. To this end, mica was chosen for this study.…”

Section: Control Surfacesmentioning

confidence: 99%

“…With the previous imaging studies on PGMs by transmission electron microscopy [18][19][20], to facilitate visualization it had been necessary to coat the substrate with a thin layer of conductive material, and the mucins themselves were sprayed onto the surface of this substrate. The advantage of AFM over this is that the mucins may be adsorbed directly from solution and do not require further sample treatment prior to visualization.…”

Section: Pgm Glycoproteinmentioning

confidence: 99%

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Atomic force microscopy of gastric mucin and chitosan mucoadhesive systems

Deacon

McGurk

Roberts

et al. 2000

Biochemical Journal

117

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Atomic force microscopy has been utilized to probe, at a molecular level, the interaction between purified pig gastric mucin (PGM) and a mucoadhesive cationic polymer, chitosan (sea cure 210j), with a low degree (approx. 11 %) of acetylation. Images were produced detailing the structures of both PGM and chitosan in 0.1 M acetate buffer (pH 4.5), followed by the complex of the two structures in the same buffer. PGM in 0.1 M acetate buffer revealed long linear filamentous structures, consistent with earlier electron microscopy and scanning tunnelling micoscopy studies. The chitosan molecules also adopted a linear conformation in the same buffer, although with a smaller average

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Section: Pgm Glycoproteinsupporting

confidence: 90%

Section: Control Surfacesmentioning

confidence: 99%

Section: Pgm Glycoproteinmentioning

confidence: 99%

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Atomic force microscopy of gastric mucin and chitosan mucoadhesive systems

Deacon

McGurk

Roberts

et al. 2000

Biochemical Journal

117

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“…Early studies of PGM concluded that its general structure and chemical composition are similar to those of human gastric and respiratory mucins (Boat et al, 1976b;Scawen & Allen, 1977;Sheehan et al, 1986). However, more recent studies of mucins from a variety of species and epithelial locations have highlighted differences both between individual mucins and within overall mucus composition and this is reflected in the results obtained here and in previous studies on Pseudomonas mucin desulfation (Jansen et al, 1999;Tralau et al, 2007).…”

Section: Discussionsupporting

confidence: 50%

Desulfurization of mucin by Pseudomonas aeruginosa: influence of sulfate in the lungs of cystic fibrosis patients

Robinson

Elkins

Bialkowski

et al. 2012

Journal of Medical Microbiology

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Pseudomonas aeruginosa is a common cause of chronic respiratory infection in cystic fibrosis (CF) patients. Infection is established within the lung epithelial mucus layer through adhesion to mucins. Terminal residues on mucin oligosaccharide chains are highly sulfated and sialylated, which increases their resistance to degradation by bacterial enzymes. However, a number of microbes, including P. aeruginosa, display mucin sulfatase activity. Using ion chromatography, the levels of sulfation on different respiratory mucins and the availability of inorganic sulfate to pathogens in sputum from CF patients were quantified. The ability of clinical isolates of P. aeruginosa to desulfate mucin was tested by providing mucin as a sole sulfur source for growth. All tested P. aeruginosa strains isolated from the lungs of CF patients were able to use human respiratory mucin as a source of sulfur for growth, whereas other non-clinical species of the genus Pseudomonas were not. However, measured levels of inorganic sulfate in sputum from CF patients suggested that bacteria resident in the lung have sufficient inorganic sulfate for growth and are unlikely to require access to mucin sulfur as a sulfur source during chronic infection. This was confirmed when expression of sulfate-repressed P. aeruginosa genes atsK and msuE was found to be repressed in the sputum of CF patients, which was detected by using quantitative RT-PCR. These results indicate that sulfate starvation is unlikely to occur in pathogens residing in the sputum of CF patients and, therefore, mucin desulfation may have an alternative purpose in the association between P. aeruginosa and the airways of CF patients.

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“…Mucins are long, flexible and highly glycosylated proteins, with a fiber diameter of 5-10 nm based on their biochemical structure and as confirmed by both negatively stained electron microscopic images of individual mucin fibers (22,23) and by the DMSOmediated glutaraldehyde fixation method (1). The concentration of mucins in mucus gels typically ranges between 1-5% (1,(24)(25)(26)(27)(28).…”

Section: Resultsmentioning

confidence: 99%

Nanoparticles reveal that human cervicovaginal mucus is riddled with pores larger than viruses

Lai

Wang²,

Hida³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

333

343

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The mechanisms by which mucus helps prevent viruses from infecting mucosal surfaces are not well understood. We engineered non-mucoadhesive nanoparticles of various sizes and used them as probes to determine the spacing between mucin fibers (pore sizes) in fresh undiluted human cervicovaginal mucus (CVM) obtained from volunteers with healthy vaginal microflora. We found that most pores in CVM have diameters significantly larger than human viruses (average pore size 340 ± 70 nm; range approximately 50–1800 nm). This mesh structure is substantially more open than the 15–100-nm spacing expected assuming mucus consists primarily of a random array of individual mucin fibers. Addition of a nonionic detergent to CVM caused the average pore size to decrease to 130 ± 50 nm. This suggests hydrophobic interactions between lipid-coated “naked” protein regions on mucins normally cause mucin fibers to self-condense and/or bundle with other fibers, creating mucin “cables” at least three times thicker than individual mucin fibers. Although the native mesh structure is not tight enough to trap most viruses, we found that herpes simplex virus (approximately 180 nm) was strongly trapped in CVM, moving at least 8,000-fold slower than non-mucoadhesive 200-nm nanoparticles. This work provides an accurate measurement of the pore structure of fresh, hydrated ex vivo CVM and demonstrates that mucoadhesion, rather than steric obstruction, may be a critical protective mechanism against a major sexually transmitted virus and perhaps other viruses.

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Electron microscopy of cervical, gastric and bronchial mucus glycoproteins

Cited by 160 publications

References 17 publications

Atomic force microscopy of gastric mucin and chitosan mucoadhesive systems

Atomic force microscopy of gastric mucin and chitosan mucoadhesive systems

Desulfurization of mucin by Pseudomonas aeruginosa: influence of sulfate in the lungs of cystic fibrosis patients

Nanoparticles reveal that human cervicovaginal mucus is riddled with pores larger than viruses

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