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.

scholarly journals Quantifying the Importance of Galactofuranose in Aspergillus nidulans Hyphal Wall Surface Organization by Atomic Force Microscopy

2011 ◽  
Vol 10 (5) ◽  
pp. 646-653 ◽  
Author(s):  
Biplab C. Paul ◽  
Amira M. El-Ganiny ◽  
Mariam Abbas ◽  
Susan G. W. Kaminskyj ◽  
Tanya E. S. Dahms
Keyword(s):  
Atomic Force Microscopy ◽  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Wall Surface ◽  
Wild Type ◽  
Content Type ◽  
Force Microscopy ◽  
Double Deletion ◽  
Atomic Force ◽  
Viscoelastic Modulus

ABSTRACTThe fungal wall mediates cell-environment interactions. Galactofuranose (Galf), the five-member ring form of galactose, has a relatively low abundance inAspergilluswalls yet is important for fungal growth and fitness.Aspergillus nidulansstrains deleted for Galfbiosynthesis enzymes UgeA (UDP-glucose-4-epimerase) and UgmA (UDP-galactopyranose mutase) lacked immunolocalizable Galf, had growth and sporulation defects, and had abnormal wall architecture. We used atomic force microscopy and force spectroscopy to image and quantify cell wall viscoelasticity and surface adhesion ofugeAΔ andugmAΔ strains. We compared the results forugeAΔ andugmAΔ strains with the results for a wild-type strain (AAE1) and theugeBdeletion strain, which has wild-type growth and sporulation. Our results suggest that UgeA and UgmA are important for cell wall surface subunit organization and wall viscoelasticity. TheugeAΔ andugmAΔ strains had significantly larger surface subunits and lower cell wall viscoelastic moduli than those of AAE1 orugeBΔ hyphae. Double deletion strains (ugeAΔugeBΔ andugeAΔugmAΔ) had more-disorganized surface subunits than single deletion strains. Changes in wall surface structure correlated with changes in its viscoelastic modulus for both fixed and living hyphae. Wild-type walls had the largest viscoelastic modulus, while the walls of the double deletion strains had the smallest. TheugmAΔ strain and particularly theugeAΔugmAΔ double deletion strain were more adhesive to hydrophilic surfaces than the wild type, consistent with changes in wall viscoelasticity and surface organization. We propose that Galfis necessary for full maturation ofA. nidulanswalls during hyphal extension.

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

Structure and assembly-disassembly properties of wild-type transthyretin amyloid protofibrils observed with atomic force microscopy

2011 ◽  
Vol 24 (3) ◽  
pp. 467-476 ◽  
Author(s):  
Ricardo H. Pires ◽  
Maria J. Saraiva ◽  
Ana M. Damas ◽  
Miklós S. Z. Kellermayer
Keyword(s):  
Atomic Force Microscopy ◽  
Wild Type ◽  
Force Microscopy ◽  
Atomic Force

Comparison study of live cells by atomic force microscopy, confocal microscopy, and scanning electrochemical microscopy

2007 ◽  
Vol 85 (3) ◽  
pp. 175-183 ◽  
Author(s):  
Xiaocui Zhao ◽  
Nils O Petersen ◽  
Zhifeng Ding
Keyword(s):  
Atomic Force Microscopy ◽  
Confocal Microscopy ◽  
Scanning Electrochemical Microscopy ◽  
Time Lapse ◽  
Live Cells ◽  
Tapping Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tapping Mode Afm ◽  
Electrochemical Microscopy

In this report, three kinds of scanning probe microscopy techniques, atomic force microscopy (AFM), confocal microscopy (CM), and scanning electrochemical microscopy (SECM), were used to study live cells in the physiological environment. Two model cell lines, CV-1 and COS-7, were studied. Time-lapse images were obtained with both contact and tapping mode AFM techniques. Cells were more easily scratched or moved by contact mode AFM than by tapping mode AFM. Detailed surface structures such as filamentous structures on the cell membrane can be obtained and easily discerned with tapping mode AFM. The toxicity of ferrocenemethanol (Fc) on live cells was studied by CM in reflection mode by recording the time-lapse images of controlled live cells and live cells with different Fc concentrations. No significant change in the morphology of cells was caused by Fc. Cells were imaged by SECM with Fc as the mediator at a biased potential of 0.35 V (vs. Ag/AgCl with a saturated KCl solution). Cells did not change visibly within 1 h, which indicated that SECM was a noninvasive technique and thus has a unique advantage for the study of soft cells, since the electrode scanned above the cells instead of in contact with them. Reactive oxygen species (ROS) generated by the cells were detected and images based on these chemical species were obtained. It is demonstrated that SECM can provide not only the topographical images but also the images related to the chemical or biochemical species released by the live cells.Key words: live cells, atomic force microscopy, confocal microscopy, scanning electrochemical microscopy.

scholarly journals Quantitative atomic force microscopy measurements of Acinetobacter morphology

2020 ◽  
Author(s):  
C. Phoebe Lostroh ◽  
Caroline M. Boyd ◽  
Nicholas Lammers ◽  
Kaleb S. Roush ◽  
Sara L. Worsham ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Growth Curve ◽  
Cell Shape ◽  
Nanometer Scale ◽  
Growth Media ◽  
Wild Type ◽  
Acinetobacter Baylyi ◽  
Force Microscopy ◽  
Atomic Force ◽  
Morphology Changes

Abstract Acinetobacter baylyi are variously reported as spherical or rod-shaped. Here we use atomic force microscopy (AFM) to make quantitative nanometer-scale measurements of cellular length and width for thousands of individual cells. We quantify the heterogeneity of populations grown in varying environmental conditions that dramatically affect cell shape. In particular, we look at morphology changes across a growth curve, and we examine cells from populations grown in various growth media. We also examine the morphology of a minC mutant, which suggests an interpretation for the morphological types observed in wild type cells.

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