Tag Archives: cell biology

Elastic shell theory for plant cell wall stiffness reveals contributions of cell wall elasticity and turgor pressure in AFM measurement

The stiffness of a plant cell in response to an applied force is determined not only by the elasticity of the cell wall but also by turgor pressure and cell geometry, which affect the tension of the cell wall. Although stiffness has been investigated using atomic force microscopy (AFM) and Young’s modulus of the cell wall has occasionally been estimated using the contact-stress theory (Hertz theory), the existence of tension has made the study of stiffness more complex. *

An alternative model is a contact model based on elastic shell theory, in which the cell wall is assumed to be a thin, curved surface pushed by turgor pressure. This theory enables one to infer turgor pressure from the apparent stiffness in some cases. In the unified formula from the elastic shell theory, AFM indentation is described as the contributions of cell wall elasticity and turgor pressure, while the estimation of elasticity and pressure remains ambiguous. *

In the article “Elastic shell theory for plant cell wall stiffness reveals contributions of cell wall elasticity and turgor pressure in AFM measurement” Satoru Tsugawa, Yuki Yamasaki, Shota Horiguchi, Tianhao Zhang, Takara Muto, Yosuke Nakaso, Kenshiro Ito, Ryu Takebayashi, Kazunori Okano, Eri Akita, Ryohei Yasukuni, Taku Demura, Tetsuro Mimura, Ken’ichi Kawaguchi and Yoichiroh Hosokawa describe how they used finite element method simulations to verify the formula of the elastic shell theory for onion (Allium cepa) cells and further optimized the formula to analyze the apparent stiffness observed from the AFM measurement based on the elastic shell theory.*

The authors applied the formula and simulations to successfully quantify the turgor pressure and elasticity of a cell in the plane direction using the cell curvature and apparent stiffness measured by atomic force microscopy. They conclude that tension resulting from turgor pressure regulates cell stiffness, which can be modified by a slight adjustment of turgor pressure in the order of 0.1 MPa. This theoretical analysis reveals a path for understanding forces inherent in plant cells. *

NANOSENSORS™ sphere AFM probes SD-Sphere-NCH-S from the NANOSENSORS™ Special Developments List were used for the force-indentation curve measurements described in the article. NANOSENSORS™ tipless AFM cantilevers of the TL-NCH type were used to evaluate the tip radius dependence. *

Fig-3-S-Tsugawa-et-al-2022-Elastic-shell-theory-for-plant-cell-wall-stiffness-reveals-contributions-of-cell-wall-elasticity-and-turgor-pressure-in-AFM-measurement NANOSENSORS Sphere-AFM probes SD-Sphere-NCH-S from the NANOSENSORS™ Special Developments List were used for the force-indentation curve measurements with atomic force microscopy
Figure 3 from “Elastic shell theory for plant cell wall stiffness reveals contributions of cell wall elasticity and turgor pressure in AFM measurement” by Satoru Tsugawa et al.:
AFM measurement of an onion epidermal cell with laser perforation. (A) Photographs of the cell measured before (left) and after (right) perforation. Yellow arrow indicates the perforation point. Cell lengths along long- and short- axes are denoted by La and Lb, respectively. Bars, 50 µm. (B) Topographic images before (left) and after (right) perforation. Measurement area corresponds to the dashed box area in (A). Lower images are three-dimensional images of upper images. (C) Enlarged image of the perforation point. (D) Cross-sectional graph of the cell wall surface before (red line) and after (blue line) perforation, corresponding to the height of dashed lines in upper-left and -right images in (B), respectively. Bulge height of the cell surface is denoted by w. Dashed lines are curves for curvature calculated from Lb and w. (E) Quantities determined from AFM measurement. Mean curvature of the cell wall surface κM is calculated from La, Lb, and w. (F) Force–indentation curves of the cell wall before (red dots) and after (blue dots) perforation. Dashed lines are fitting curves by the Hertz model and solid lines are fitting lines by the shell model. (G) Apparent stiffness kas as a function of force F applied to the cell wall before (red dots) and after (blue dots) perforation. kas is estimated by linear least squares fitting of the force-indentation curve in the vicinity of the F, as shown in (F). Bars on dots represent root mean squared error. Solid lines are exponential plateau curves: kas = 35 × {1 − exp(− F/7)} (red line); kas = 10 × {1 − exp(− F/1.28)} (blue line).
Abstract
The stiffness of a plant cell in response to an applied force is determined not only by the elasticity of the cell wall but also by turgor pressure and cell geometry, which affect the tension of the cell wall. Although stiffness has been investigated using atomic force microscopy (AFM) and Young’s modulus of the cell wall has occasionally been estimated using the contact-stress theory (Hertz theory), the existence of tension has made the study of stiffness more complex. Elastic shell theory has been proposed as an alternative method; however, the estimation of elasticity remains ambiguous. Here, we used finite element method simulations to verify the formula of the elastic shell theory for onion (Allium cepa) cells. We applied the formula and simulations to successfully quantify the turgor pressure and elasticity of a cell in the plane direction using the cell curvature and apparent stiffness measured by AFM. We conclude that tension resulting from turgor pressure regulates cell stiffness, which can be modified by a slight adjustment of turgor pressure in the order of 0.1 MPa. This theoretical analysis reveals a path for understanding forces inherent in plant cells.

*Satoru Tsugawa, Yuki Yamasaki, Shota Horiguchi, Tianhao Zhang, Takara Muto, Yosuke Nakaso, Kenshiro Ito, Ryu Takebayashi, Kazunori Okano, Eri Akita, Ryohei Yasukuni, Taku Demura, Tetsuro Mimura, Ken’ichi Kawaguchi and Yoichiroh Hosokawa
Elastic shell theory for plant cell wall stiffness reveals contributions of cell wall elasticity and turgor pressure in AFM measurement
Nature Scientific Reports volume 12, Article number: 13044 (2022)
DOI: https://doi.org/10.1038/s41598-022-16880-2

Please follow this external link to read the full article: https://rdcu.be/cSWFR

Open Access: The article “Elastic shell theory for plant cell wall stiffness reveals contributions of cell wall elasticity and turgor pressure in AFM measurement” by Satoru Tsugawa, Yuki Yamasaki, Shota Horiguchi, Tianhao Zhang, Takara Muto, Yosuke Nakaso, Kenshiro Ito, Ryu Takebayashi, Kazunori Okano, Eri Akita, Ryohei Yasukuni, Taku Demura, Tetsuro Mimura, Ken’ichi Kawaguchi and Yoichiroh Hosokawa is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Efficient long-range conduction in cable bacteria through nickel protein wires

Bio-materials typically have an intrinsically low electrical conductivity, and so the availability of a bio-material with extraordinary electrical properties has great potential for new applications in bio-electronics. This prospect of technological application however requires a deeper understanding of the mechanism of electron transport as well as the structure and composition of the conductive fibers in cable bacteria.*

Filamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved.*

In their article “Efficient long-range conduction in cable bacteria through nickel protein wires”  Henricus T. S. Boschker, Perran L. M. Cook, Lubos Polerecky, Raghavendran Thiruvallur Eachambadi, Helena Lozano, Silvia Hidalgo-Martinez, Dmitry Khalenkow, Valentina Spampinato, Nathalie Claes, Paromita Kundu, Da Wang, Sara Bals, Karina K. Sand, Francesca Cavezza, Tom Hauffman, Jesper Tataru Bjerg, Andre G. Skirtach, Kamila Kochan, Merrilyn McKee, Bayden Wood, Diana Bedolla, Alessandra Gianoncelli, Nicole M. J. Geerlings, Nani Van Gerven, Han Remaut, Jeanine S. Geelhoed, Ruben Millan-Solsona, Laura Fumagalli, Lars Peter Nielsen, Alexis Franquet, Jean V. Manca, Gabriel Gomila and Filip J. R. Meysman combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer.*

The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.*

NANOSENSORS wear-resistant conductive Platinum Silicide AFM probes of the PtSi-CONT type were used for the Scanning dielectric microscopy (SDM) described in the article.

Figure 5 from Henricus T. S. Boschker et al. “Efficient long-range conduction in cable bacteria through nickel protein wires” A Compositional model of the conductive fiber sheath in cable bacteria based on the present findings. Cross-sections through a filament in the middle of a cell are drawn and the number of fibers has been reduced for clarity—a 4 μm diameter cable bacterium has typically ~60 fibers5. In its native state (right panel), the fiber sheath is embedded periplasm between the cell and outer membrane and adopts a circular shape. After extraction, which removes the membranes and most of the cytoplasm and after drying upon a surface for analysis, the fiber sheath flattens, leading to two mirrored sheaths on top of each other (middle panel). The enlargement shows a section of the top sheath, which is the sample section probed by ToF-SIMS depth profiles and NanoSIMS images. Fibers are made of protein with a conductive Ni/S rich core and a non-conductive outer shell, and are embedded in a basal layer enriched in polysaccharide. B Topographic AFM image of a fiber sheath with a single isolated fiber detaching. The insert shows a detailed AFM image of this single fiber. C SDM amplitude image (right insert) and cross-sectional profile. D Corresponding SDM phase image (insert) and cross-sectional profile. Constant height (z = 66 nm) cross-section profiles are measured along the dashed lines shown in the left inserts. The red dotted lines in C and D represent model fits assuming the a fiber has a conductive core and an insulating outer shell. The right insert in C shows a vertical cross-section of the electric potential distribution as predicted by the model. Model parameters: shell thickness, d = 12 nm; fiber height, h = 42 nm; fiber width w = 87 nm; relative dielectric constants of the shell and core, εs = ω εc = 3; conductivity of the shell σs = 0 S/cm (insulating); conductivity of the core σc = 20 S/cm7 (see Supplementary Note 2 for treatment of SDM results and models tested). SDM analysis on a single fiber is available only from one samples as this is a rare event, but results from a double fiber and fiber sheaths are in agreement (see Supplementary Note 2). NANOSENSORS wear-resistant conductive Platinum Silicide AFM probes of the PtSi-CONT type were used for the Scanning dielectric microscopy (SDM).
Figure 5 from Henricus T. S. Boschker et al. “Efficient long-range conduction in cable bacteria through nickel protein wires”
A Compositional model of the conductive fiber sheath in cable bacteria based on the present findings. Cross-sections through a filament in the middle of a cell are drawn and the number of fibers has been reduced for clarity—a 4 μm diameter cable bacterium has typically ~60 fibers5. In its native state (right panel), the fiber sheath is embedded periplasm between the cell and outer membrane and adopts a circular shape. After extraction, which removes the membranes and most of the cytoplasm and after drying upon a surface for analysis, the fiber sheath flattens, leading to two mirrored sheaths on top of each other (middle panel). The enlargement shows a section of the top sheath, which is the sample section probed by ToF-SIMS depth profiles and NanoSIMS images. Fibers are made of protein with a conductive Ni/S rich core and a non-conductive outer shell, and are embedded in a basal layer enriched in polysaccharide. B Topographic AFM image of a fiber sheath with a single isolated fiber detaching. The insert shows a detailed AFM image of this single fiber. C SDM amplitude image (right insert) and cross-sectional profile. D Corresponding SDM phase image (insert) and cross-sectional profile. Constant height (z = 66 nm) cross-section profiles are measured along the dashed lines shown in the left inserts. The red dotted lines in C and D represent model fits assuming the a fiber has a conductive core and an insulating outer shell. The right insert in C shows a vertical cross-section of the electric potential distribution as predicted by the model. Model parameters: shell thickness, d = 12 nm; fiber height, h = 42 nm; fiber width w = 87 nm; relative dielectric constants of the shell and core, εs = ω εc = 3; conductivity of the shell σs = 0 S/cm (insulating); conductivity of the core σc = 20 S/cm7 (see Supplementary Note 2 for treatment of SDM results and models tested). SDM analysis on a single fiber is available only from one samples as this is a rare event, but results from a double fiber and fiber sheaths are in agreement (see Supplementary Note 2).

*Henricus T. S. Boschker, Perran L. M. Cook, Lubos Polerecky, Raghavendran Thiruvallur Eachambadi, Helena Lozano, Silvia Hidalgo-Martinez, Dmitry Khalenkow, Valentina Spampinato, Nathalie Claes, Paromita Kundu, Da Wang, Sara Bals, Karina K. Sand, Francesca Cavezza, Tom Hauffman, Jesper Tataru Bjerg, Andre G. Skirtach, Kamila Kochan, Merrilyn McKee, Bayden Wood, Diana Bedolla, Alessandra Gianoncelli, Nicole M. J. Geerlings, Nani Van Gerven, Han Remaut, Jeanine S. Geelhoed, Ruben Millan-Solsona, Laura Fumagalli, Lars Peter Nielsen, Alexis Franquet, Jean V. Manca, Gabriel Gomila and Filip J. R. Meysman
Efficient long-range conduction in cable bacteria through nickel protein wires
Nature Communications volume 12, Article number: 3996 (2021)
DOI: https://doi.org/10.1038/s41467-021-24312-4

Please follow this external link to read the full article:

https://rdcu.be/cP0I1

Open Access: The article “Efficient long-range conduction in cable bacteria through nickel protein wires” by Henricus T. S. Boschker, Perran L. M. Cook, Lubos Polerecky, Raghavendran Thiruvallur Eachambadi, Helena Lozano, Silvia Hidalgo-Martinez, Dmitry Khalenkow, Valentina Spampinato, Nathalie Claes, Paromita Kundu, Da Wang, Sara Bals, Karina K. Sand, Francesca Cavezza, Tom Hauffman, Jesper Tataru Bjerg, Andre G. Skirtach, Kamila Kochan, Merrilyn McKee, Bayden Wood, Diana Bedolla, Alessandra Gianoncelli, Nicole M. J. Geerlings, Nani Van Gerven, Han Remaut, Jeanine S. Geelhoed, Ruben Millan-Solsona, Laura Fumagalli, Lars Peter Nielsen, Alexis Franquet, Jean V. Manca, Gabriel Gomila & Filip J. R. Meysman is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Cytoskeletal disorganization underlies PABPN1-mediated myogenic disability

Muscle wasting is connected with changes in various cellular mechanisms that influence protein homeostasis, transcription, protein acetylation and different metabolic pathways. *

Scientific studies have shown that reduced levels of polyadenylation binding protein 1 ( PABPN1 , a multifactorial regulator of mRNA processing ) cause muscle wasting, including muscle atrophy, extracellular matrix thickening, myofiber typing transitions and central nucleation. *

However, the cellular mechanisms behind PABPN1-mediated muscle wasting are not fully understood. *

In the article “Cytoskeletal disorganization underlies PABPN1-mediated myogenic disability” Cyriel Sebastiaan Olie, Erik van der Wal, Cikes Domagoj, Loes Maton, Jessica C. de Greef, I.-Hsuan Lin, Yi-Fan Chen, Elsayad Kareem, Josef M. Penninger, Benedikt M. Kessler and Vered Raz examine the cytoskeletal auxiliary changes that are dependent on PABPN1 levels using 2D and 3D models, and investigate how these affect muscle wasting. *

They suggest that poor cytoskeletal mechanical features are caused by altered expression levels of cytoskeletal proteins and contribute to muscle wasting and atrophy. *

For the measurements of cell-mechanics properties in control and shPAB cells ( muscle cells with reduced PABPN1 levels ) the authors used Brillouin Light Scattering Microscopy and Atomic Force Microscopy. *

NANOSENSORS™ uniqprobe qp-BioAC ( CB3 ) AFM probes were used in the quantitative imaging where a force curve is applied at each point. The analyzed area of each cell was 5 µm × 5 µm (64 × 64 pixels) with an approach speed of 35 µm/s (3.4 ms/pixel), and applied forces of up to 118 pN. *

Figure 4 from “Cytoskeletal disorganization underlies PABPN1-mediated myogenic disability” by Cyriel Sebastiaan Olie et al.
 Disrupted cytoskeletal spatial organization in shPAB human muscle cell cultures. A Representative images of control and shPAB human muscle cell cultures, stained with antibodies to tubulin and actin, and the actin filaments were visualized with actin-GFP. B Tubulin staining in control and shPAB myoblast cell cultures after DMSO, 100 nM nocodazole or 25 nM paclitaxel treatment for 2 h. Scale bar is 25 µm. C Measurements of cell-mechanics properties in control and shPAB cells using the Brillouin Light Scattering Microscopy (Ci) or the Atomic Force Microscopy (Cii). Measurements were carried out in myoblasts; every dot represents the median from 1000 measurements in a cell. Cell stiffness is measured by GHz, and the young modulus reports the cell surface tension. Averages and standard deviations are from N = 15 cells. Statistical significance was calculated with the student’s t-test.
NANOSENSORS uniqprobe qp-BioAC ( CB3 ) AFM probes were used in the quantitative imaging of cell-mechanics properties.
Figure 4 from “Cytoskeletal disorganization underlies PABPN1-mediated myogenic disability” by Cyriel Sebastiaan Olie et al.
 Disrupted cytoskeletal spatial organization in shPAB human muscle cell cultures. A Representative images of control and shPAB human muscle cell cultures, stained with antibodies to tubulin and actin, and the actin filaments were visualized with actin-GFP. B Tubulin staining in control and shPAB myoblast cell cultures after DMSO, 100 nM nocodazole or 25 nM paclitaxel treatment for 2 h. Scale bar is 25 µm. C Measurements of cell-mechanics properties in control and shPAB cells using the Brillouin Light Scattering Microscopy (Ci) or the Atomic Force Microscopy (Cii). Measurements were carried out in myoblasts; every dot represents the median from 1000 measurements in a cell. Cell stiffness is measured by GHz, and the young modulus reports the cell surface tension. Averages and standard deviations are from N = 15 cells. Statistical significance was calculated with the student’s t-test.

*Cyriel Sebastiaan Olie, Erik van der Wal, Cikes Domagoj, Loes Maton, Jessica C. de Greef, I.-Hsuan Lin, Yi-Fan Chen, Elsayad Kareem, Josef M. Penninger, Benedikt M. Kessler & Vered Raz
Cytoskeletal disorganization underlies PABPN1-mediated myogenic disability
Nature Scientific Reports volume 10, Article number: 17621 (2020)
DOI: https://doi.org/10.1038/s41598-020-74676-8

Please follow this external link to read the full article https://rdcu.be/ceyJ4

Open Access: The article “Cytoskeletal disorganization underlies PABPN1-mediated myogenic disability” by Cyriel Sebastiaan Olie, Erik van der Wal, Cikes Domagoj, Loes Maton, Jessica C. de Greef, I.-Hsuan Lin, Yi-Fan Chen, Elsayad Kareem, Josef M. Penninger, Benedikt M. Kessler & Vered Raz is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.