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  • 1
    Online Resource
    Online Resource
    Wiley ; 2020
    In:  Journal of Microscopy Vol. 278, No. 3 ( 2020-06), p. 145-153
    In: Journal of Microscopy, Wiley, Vol. 278, No. 3 ( 2020-06), p. 145-153
    Abstract: Both plants and animals sense and respond to mechanical stresses that arise internally or are externally imposed. In many cases, tissues respond by changing their gene expression or their mechanical properties, which has an impact on how they develop. Many tools have been developed to measure mechanical properties and to investigate responses to mechanical stress. Here we review the state of microscope‐coupled tensile testing at the single‐cell and tissue scale and give a view on future opportunities for extending the technology. Uniaxial tensile testing involves quantifying the deformation of a sample when a force is applied. By varying the amount of force, the speed at which the force is applied or the length of time that it is applied for, many characteristics of the mechanical properties of the sample can be calculated. Tensile testing has been used extensively to measure the mechanical properties of whole tissues or organs. The need for higher resolution data resulted in more researchers using indentation tests to measure mechanical properties instead. Indentation tests provide information at a different scale and are not suitable for answering the same type of questions as tensile testing. Here we discuss that by coupling tensile‐testing machinery with microscopes such as is the case for the Automated Confocal Micro‐Extensometer (ACME) it is possible to obtain tissue‐scale measurements of mechanical properties with cellular resolution. Moreover, to understand and identify the biological processes cells and tissues use to respond to mechanical stress, we need to be able to apply mechanical perturbations to plant samples while recording the induced biological changes with microscopy. Lay Description Plants, like most living organisms, are sensitive to their environment. This includes mechanical stresses imposed upon them by gravity or wind. Mechanical stress can also arise from internal tissue tension, which can build up if different parts of a tissue grow at different rates. In many cases, the cells respond to mechanical stress by changing their mechanical properties, which can affect their growth and their final shape. There is thus a critical need to develop tools for measuring mechanical properties and the response to mechanical stress. Mechanical properties cannot be visualised directly but must be inferred by looking at how a tissue deforms when a force is applied or vice versa. This is more challenging when one wishes to achieve this at the cellular scale, as the forces and deformations are much smaller. There are a range of methods available that have advantages and disadvantages. Here we review some of these methods. In particular, we focus on methods that cause deformation in the main axis of the tissue. This type of test can be coupled with conventional and state‐of‐the‐art microscopes. Coupling with microscopes increases the resolution of the tests that can be performed and facilitates the simultaneous observation of responses to the mechanical stresses.
    Type of Medium: Online Resource
    ISSN: 0022-2720 , 1365-2818
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2007259-4
    SSG: 11
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  • 2
    In: Biophysical Journal, Elsevier BV, Vol. 106, No. 2 ( 2014-01), p. 356a-
    Type of Medium: Online Resource
    ISSN: 0006-3495
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
    detail.hit.zdb_id: 1477214-0
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2014
    In:  Proceedings of the National Academy of Sciences Vol. 111, No. 36 ( 2014-09-09), p. 13075-13080
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 111, No. 36 ( 2014-09-09), p. 13075-13080
    Abstract: Cell shape affects proliferation and differentiation, which are processes known to depend on integrin-based focal adhesion (FA) signaling. Because shape results from force balance and FAs are mechanosensitive complexes transmitting tension from the cell structure to its mechanical environment, we investigated the interplay between 3D cell shape, traction forces generated through the cell body, and FA growth during early spreading. Combining measurements of cell-scale normal traction forces with FA monitoring, we show that the cell body contact angle controls the onset of force generation and, subsequently, the initiation of FA growth at the leading edge of the lamella. This suggests that, when the cell body switches from convex to concave, tension in the apical cortex is transmitted to the lamella where force-sensitive FAs start to grow. Along this line, increasing the stiffness resisting cell body contraction led to a decrease of the lag time between force generation and FA growth, indicating mechanical continuity of the cell structure and force transmission from the cell body to the leading edge. Remarkably, the overall normal force per unit area of FA increased with stiffness, and its values were similar to those reported for local tangential forces acting on individual FAs. These results reveal how the 3D cell shape feeds back on its internal organization and how it may control cell fate through FA-based signaling.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2014
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 4
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2019-02-13)
    Abstract: In plants mechanical signals pattern morphogenesis through the polar transport of the hormone auxin and through regulation of interphase microtubule (MT) orientation. To date, the mechanisms by which such signals induce changes in cell polarity remain unknown. Through a combination of time-lapse imaging, and chemical and mechanical perturbations, we show that mechanical stimulation of the SAM causes transient changes in cytoplasmic calcium ion concentration (Ca 2+ ) and that transient Ca 2+ response is required for downstream changes in PIN-FORMED 1 (PIN1) polarity. We also find that dynamic changes in Ca 2+ occur during development of the SAM and this Ca 2+ response is required for changes in PIN1 polarity, though not sufficient. In contrast, we find that Ca 2+ is not necessary for the response of MTs to mechanical perturbations revealing that Ca 2+ specifically acts downstream of mechanics to regulate PIN1 polarity response.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2553671-0
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  • 5
    In: Biophysical Journal, Elsevier BV, Vol. 107, No. 10 ( 2014-11), p. 2237-2244
    Type of Medium: Online Resource
    ISSN: 0006-3495
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
    detail.hit.zdb_id: 1477214-0
    SSG: 12
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  • 6
    In: Nature Methods, Springer Science and Business Media LLC, Vol. 15, No. 7 ( 2018-7), p. 491-498
    Type of Medium: Online Resource
    ISSN: 1548-7091 , 1548-7105
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2018
    detail.hit.zdb_id: 2163081-1
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  • 7
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2015
    In:  Proceedings of the National Academy of Sciences Vol. 112, No. 9 ( 2015-03-03), p. 2740-2745
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 112, No. 9 ( 2015-03-03), p. 2740-2745
    Abstract: Living cells adapt and respond actively to the mechanical properties of their environment. In addition to biochemical mechanotransduction, evidence exists for a myosin-dependent purely mechanical sensitivity to the stiffness of the surroundings at the scale of the whole cell. Using a minimal model of the dynamics of actomyosin cortex, we show that the interplay of myosin power strokes with the rapidly remodeling actin network results in a regulation of force and cell shape that adapts to the stiffness of the environment. Instantaneous changes of the environment stiffness are found to trigger an intrinsic mechanical response of the actomyosin cortex. Cortical retrograde flow resulting from actin polymerization at the edges is shown to be modulated by the stress resulting from myosin contractility, which in turn, regulates the cell length in a force-dependent manner. The model describes the maximum force that cells can exert and the maximum speed at which they can contract, which are measured experimentally. These limiting cases are found to be associated with energy dissipation phenomena, which are of the same nature as those taking place during the contraction of a whole muscle. This similarity explains the fact that single nonmuscle cell and whole-muscle contraction both follow a Hill-like force–velocity relationship.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2015
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 29 ( 2020-07-21), p. 17399-17408
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 29 ( 2020-07-21), p. 17399-17408
    Abstract: The cytoskeleton plays a key role in establishing robust cell shape. In animals, it is well established that cell shape can also influence cytoskeletal organization. Cytoskeletal proteins are well conserved between animal and plant kingdoms; nevertheless, because plant cells exhibit major structural differences to animal cells, the question arises whether the plant cytoskeleton also responds to geometrical cues. Recent numerical simulations predicted that a geometry-based rule is sufficient to explain the microtubule (MT) organization observed in cells. Due to their high flexural rigidity and persistence length of the order of a few millimeters, MTs are rigid over cellular dimensions and are thus expected to align along their long axis if constrained in specific geometries. This hypothesis remains to be tested in cellulo . Here, we explore the relative contribution of geometry to the final organization of actin and MT cytoskeletons in single plant cells of Arabidopsis thaliana . We show that the cytoskeleton aligns with the long axis of the cells. We find that actin organization relies on MTs but not the opposite. We develop a model of self-organizing MTs in three dimensions, which predicts the importance of MT severing, which we confirm experimentally. This work is a first step toward assessing quantitatively how cellular geometry contributes to the control of cytoskeletal organization in living plant cells.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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