scholarly journals Investigating the biomechanical properties of streptococcal polysaccharide capsules using atomic force microscopy

2019 ◽  
Author(s):  
H Marshall ◽  
S Aguayo ◽  
M Kilian ◽  
FC Petersen ◽  
L Bozec ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Biomechanical Properties ◽  
Bacterial Strains ◽  
Biophysical Properties ◽  
Adhesive Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Virulence Potential ◽  
Force Volume ◽  
Polysaccharide Capsules

AbstractIn common with many bacterial pathogens, Streptococcus pneumoniae has a polysaccharide capsule, which facilitates immune evasion and is a key virulence determinant. However, recent data has shown that the closely related Streptococcus mitis can also express polysaccharide capsules including those with an identical chemical structure to S. pneumoniae capsular serotypes. We have used atomic force microscopy (AFM) techniques to investigate the biophysical properties of S. mitis and S. pneumoniae strains expressing the same capsular serotypes that might relate to their differences in virulence potential. When comparing S. mitis and S. pneumoniae strains with identical capsule serotypes S. mitis strains were more susceptible to neutrophil killing and imaging using electron microscopy and AFM demonstrated significant morphological differences. Force-volume mapping using AFM showed distinct force-curve profiles for the centre and edge areas of encapsulated S. pneumoniae and S. mitis strains. This “edge effect” was not observed in the unencapsulated streptococcal strains and in an unencapsulated Staphylococcus aureus strain, and therefore was a direct representation of the mechanical properties of the bacterial capsule. When two strains of S. mitis and S. pneumoniae expressed an identical capsular serotype, they presented also similar biomechanical characteristics. This would infer a potential relationship between capsule biochemistry and nanomechanics, independent of the bacterial strains. Overall, AFM was an effective tool to explore the biophysical properties of bacterial capsules of living bacteria by reproducibly quantifying the elastic and adhesive properties of bacterial cell surfaces. Using AFM to investigate capsule differences over a wider range of strains and capsular serotypes of streptococci and correlate the data with phenotypic differences will elucidate how the biophysical properties of the capsule can influence its biological role during infection.

scholarly journals miR-218 Affects the ECM Composition and Cell Biomechanical Properties of Glioblastoma Cells

2021 ◽  
Author(s):  
Małgorzata Grabowska ◽  
Konrad Kuczyński ◽  
Monika Piwecka ◽  
Alicja Rabiasz ◽  
Joanna Zemła ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Real Time ◽  
Protein Level ◽  
Biomechanical Properties ◽  
Cell Stiffness ◽  
Luciferase Assay ◽  
Adhesive Properties ◽  
Force Microscopy ◽  
Time Migration ◽  
Atomic Force

Abstract BackgroundGlioblastoma (GBM) is the most common malignant brain tumour. GBM cells have ability to infiltrate into the surrounding brain tissue, which results in a significant decrease in the patient’s survival rate. Infiltration is a consequence of the low adhesion and high migration of the tumour cells, two features being associated with the highly remodelled extracellular matrix (ECM). MethodsThe expression profile of miRNAs and mRNAs was analysed by qPCR on 19 GBM tissue samples. Than luciferase assay was performed to confirm interaction between miR-218 and target sequences. Next we checked how supplementation of glioma cell line (U118-MG) with microRNA 218 will change expression pattern of TN-C and SDC both on transcript level and on protein level. Analysis of protein level were made with western-blot technique. Last step in expression profiling of genes connected to cellular motility and adhesion was done with use of qPCR analysis after supplementation with miR-218. To assess the abilities of cells to migrate and proliferate real-time cell culture analysis with use of Incelligence system were utilized. Also this results were backed by classic wound-healing assay. To conclude we used atomic force microscopy (AFM) to measure physical properties such as adhesion and stiffness of cells. This study was supported by microscopy analysis of cytoskeleton changes after supplementation of miR-218.ResultsIn this study, we report that ECM composition is partially regulated at the posttranscriptional level by miRNA. Particularly, we show that miR-218, a well-known miRNA suppressor, is involved in direct regulation of ECM components, tenascin-C (TN-C) and syndecan-2 (SDC-2). We demonstrated that the overexpression of miR-218 reduces the mRNA and protein expression levels of TN-C and SDC-2, and subsequently influences biomechanical properties of GBM cells. Atomic force microscopy (AFM) and real-time migration analysis revealed that miR-218 overexpression impairs the migration potential and enhances the adhesive properties of cells. AFM analysis followed by F-actin staining demonstrated that expression level of miR-218 has an impact on cell stiffness and cytoskeletal reorganization. Global gene expression analysis showed deregulation of a number of genes involved in tumour cell motility and adhesion or ECM remodelling upon miR-218 treatment, suggesting further indirect interactions between the cells and ECM. Conclusion The results demonstrated a direct impact of miR-218 reduction in GBM tumours on the qualitative ECM content, leading to changes in the rigidity of the ECM and GBM cells being conducive to increased invasiveness of GBM.

scholarly journals Atomic force microscopy of a ctpA mutant in Rhizobium leguminosarum reveals surface defects linking CtpA function to biofilm formation

Microbiology ◽  
2011 ◽  
Vol 157 (11) ◽  
pp. 3049-3058 ◽  
Author(s):  
Jun Dong ◽  
Karla S. L. Signo ◽  
Elizabeth M. Vanderlinde ◽  
Christopher K. Yost ◽  
Tanya E. S. Dahms
Keyword(s):  
Atomic Force Microscopy ◽  
Mutant Strain ◽  
Biofilm Formation ◽  
Rhizobium Leguminosarum ◽  
Surface Defects ◽  
Ion Concentration ◽  
Adhesive Properties ◽  
Surface Ultrastructure ◽  
Force Microscopy ◽  
Atomic Force

Atomic force microscopy was used to investigate the surface ultrastructure, adhesive properties and biofilm formation of Rhizobium leguminosarum and a ctpA mutant strain. The surface ultrastructure of wild-type R. leguminosarum consists of tightly packed surface subunits, whereas the ctpA mutant has much larger subunits with loose lateral packing. The ctpA mutant strain is not capable of developing fully mature biofilms, consistent with its altered surface ultrastructure, greater roughness and stronger adhesion to hydrophilic surfaces. For both strains, surface roughness and adhesive forces increased as a function of calcium ion concentration, and for each, biofilms were thicker at higher calcium concentrations.

Effect of ampicillin on adhesive properties of bacteria examined by atomic force microscopy

Micron ◽  
2018 ◽  
Vol 112 ◽  
pp. 84-90 ◽  
Author(s):  
Dariusz Laskowski ◽  
Janusz Strzelecki ◽  
Konrad Pawlak ◽  
Hanna Dahm ◽  
Aleksander Balter
Keyword(s):  
Atomic Force Microscopy ◽  
Adhesive Properties ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Atomic Force Microscopy of Cell Growth and Division in Staphylococcus aureus

2004 ◽  
Vol 186 (11) ◽  
pp. 3286-3295 ◽  
Author(s):  
Ahmed Touhami ◽  
Manfred H. Jericho ◽  
Terry J. Beveridge
Keyword(s):  
Staphylococcus Aureus ◽  
Atomic Force Microscopy ◽  
Cell Wall ◽  
Cross Wall ◽  
Adhesive Properties ◽  
Reactive Material ◽  
Force Microscopy ◽  
Additional Information ◽  
Atomic Force ◽  
Sequential Images

ABSTRACT The growth and division of Staphylococcus aureus was monitored by atomic force microscopy (AFM) and thin-section transmission electron microscopy (TEM). A good correlation of the structural events of division was found using the two microscopies, and AFM was able to provide new additional information. AFM was performed under water, ensuring that all structures were in the hydrated condition. Sequential images on the same structure revealed progressive changes to surfaces, suggesting the cells were growing while images were being taken. Using AFM small depressions were seen around the septal annulus at the onset of division that could be attributed to so-called murosomes (Giesbrecht et al., Arch. Microbiol. 141:315-324, 1985). The new cell wall formed from the cross wall (i.e., completed septum) after cell separation and possessed concentric surface rings and a central depression; these structures could be correlated to a midline of reactive material in the developing septum that was seen by TEM. The older wall, that which was not derived from a newly formed cross wall, was partitioned into two different surface zones, smooth and gel-like zones, with different adhesive properties that could be attributed to cell wall turnover. The new and old wall topographies are equated to possible peptidoglycan arrangements, but no conclusion can be made regarding the planar or scaffolding models.

Adhesive properties of Staphylococcus epidermidis probed by atomic force microscopy

2011 ◽  
Vol 13 (21) ◽  
pp. 9995 ◽  
Author(s):  
Yifan Hu ◽  
Jens Ulstrup ◽  
Jingdong Zhang ◽  
Søren Molin ◽  
Vincent Dupres
Keyword(s):  
Atomic Force Microscopy ◽  
Staphylococcus Epidermidis ◽  
Adhesive Properties ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals The measurement of biomechanical properties of porcine articular cartilage using atomic force microscopy

2009 ◽  
Vol 72 (4/5) ◽  
pp. 251-259 ◽  
Author(s):  
Raphael Imer ◽  
Terunobu Akiyama ◽  
Nico F. de Rooij ◽  
Martin Stolz ◽  
Ueli Aebi ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Articular Cartilage ◽  
Biomechanical Properties ◽  
Force Microscopy ◽  
Atomic Force

Assessment of biophysical properties of Haemonchus contortus from different life cycle stages with atomic force microscopy

2020 ◽  
Vol 209 ◽  
pp. 112862 ◽  
Author(s):  
Livio M. Costa-Junior ◽  
Carolina R. Silva ◽  
Alexandra M.S. Soares ◽  
Alan S. Menezes ◽  
Maria R.L. Silva ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Life Cycle ◽  
Haemonchus Contortus ◽  
Biophysical Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Life Cycle Stages

scholarly journals Assessment of Elasticity and Topography of Aspergillus nidulans Spores via Atomic Force Microscopy

2005 ◽  
Vol 71 (2) ◽  
pp. 955-960 ◽  
Author(s):  
Liming Zhao ◽  
David Schaefer ◽  
Mark R. Marten
Keyword(s):  
Atomic Force Microscopy ◽  
Aspergillus Nidulans ◽  
Fungal Spores ◽  
Protein Structures ◽  
Spore Surface ◽  
Wild Type ◽  
Adhesive Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tapping Mode Afm

ABSTRACT Previous studies have described both surface morphology and adhesive properties of fungal spores, but little information is currently available on their mechanical properties. In this study, atomic force microscopy (AFM) was used to investigate both surface topography and micromechanical properties of Aspergillus nidulans spores. To assess the influence of proteins covering the spore surface, wild-type spores were compared with spores from isogenic rodA + and rodA − strains. Tapping-mode AFM images of wild-type and rodA + spores in air showed characteristic “rodlet” protein structures covering a granular spore surface. In comparison, rodA − spores were rodlet free but showed a granular surface structure similar to that of the wild-type and rodA + spores. Rodlets were removed from rodA + spores by sonication, uncovering the underlying granular layer. Both rodlet-covered and rodlet-free spores were subjected to nanoindentation measurements, conducted in air, which showed the stiffnesses to be 110 ± 10, 120 ± 10, and 300 ± 20 N/m and the elastic moduli to be 6.6 ± 0.4, 7.0 ± 0.7, and 22 ± 2 GPa for wild-type, rodA + and rodA − spores, respectively. These results imply the rodlet layer is significantly softer than the underlying portion of the cell wall.

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