(*contributed equally to this work) 发布: 2020年10月05日第10卷第19期 DOI: 10.21769/BioProtoc.3783 浏览次数: 5678
评审: Ayelign M. AdalSara Posé Anonymous reviewer(s)
Abstract
The plant cell wall (PCW) is a pecto-cellulosic extracellular matrix that envelopes the plant cell. By integrating extra-and intra-cellular cues, PCW mediates a plethora of essential physiological functions. Notably, it permits controlled and oriented tissue growth by tuning its local mechano-chemical properties. To refine our knowledge of these essential properties of PCW, we need an appropriate tool for the accurate observation of the native (in muro) structure of the cell wall components. The label-free techniques, such as AFM, EM, FTIR, and Raman microscopy, are used; however, they either do not have the chemical or spatial resolution. Immunolabeling with electron microscopy allows observation of the cell wall nanostructure, however, it is mostly limited to single and, less frequently, multiple labeling. Immunohistochemistry (IHC) is a versatile tool to analyze the distribution and localization of multiple biomolecules in the tissue. The subcellular resolution of chemical changes in the cell wall component can be observed with standard diffraction-limited optical microscopy. Furthermore, novel chemical imaging tools such as multicolor 3D dSTORM (Three-dimensional, direct Stochastic Optical Reconstruction Microscopy) nanoscopy makes it possible to resolve the native structure of the cell wall polymers with nanometer precision and in three dimensions.
Here we present a protocol for preparing multi-target immunostaining of the PCW components taking as example Arabidopsis thaliana, Star fruit (Averrhoa carambola), and Maize thin tissue sections. This protocol is compatible with the standard confocal microscope, dSTORM nanoscope, and can also be implemented for other optical nanoscopy such as STED (Stimulated Emission Depletion Microscopy). The protocol can be adapted for any other subcellular compartments, plasma membrane, cytoplasmic, and intracellular organelles.
Background
PCW is an intricate material, which is durable but also undergoes constant structural changes in response to internal and external stimuli such as tissue expansion or pathogen attack. Nevertheless, how these seemingly contradictory features, mechanical strength and structural adaptation, cooperate, remains an unresolved question in plant cell biology. PCW contains cellulose, hemicellulose, different variants of pectin and various proteins, the architecture of which is highly organized (Peaucelle, 2018). The pectin family is composed of several polymers. The most abundant, homogalacturonan, can be demethylated after cell wall insertion. This change in chemistry is a significant step in the process of cell elongation, differentiation, and directional growth (Peaucelle et al., 2012). Several lines of evidence suggest that morphogenesis and cell differentiation are dependent on local changes in cell wall chemistry and cell wall polymer organization (Yang et al., 2016; Anane et al., 2017; Zhao et al., 2019; Haas et al., 2020). Therefore, detailed knowledge of PCW components architecture is essential for understanding plant growth. Historically, the cell wall structure has been studied using biochemical methods that involve disintegrating the tissue and destroying the native organization of its polymers (Höfte and Voxeur, 2017). Other imaging modalities, such as electron microscopy (EM) (Anane et al., 2017) and atomic force microscopy (AFM) (Zhang et al., 2017) are used for in situ cell wall observation, but these techniques often lack chemical contrast, providing only correlative quantification. Multicolor immunohistochemistry (IHC) can reveal multiple targets within a tissue section, and their spatial organization resolved in three dimensions. Despite its widespread use in the cell biology field, multicolor IHC is not yet a standard tool for studies of the cell wall. A broad palette of antibodies and probes against cell wall targets, coupled with multicolor IHC, together with the high resolving power of dSTORM (< 40 nm), permits quantitative in situ chemical analysis of cell wall nanostructure. Other imaging techniques for cell wall analysis on tissue cuts exist, such as Raman (Wightman et al., 2019) and FTIR (Mravec et al., 2017; Cuello et al., 2020). These techniques are based on the characteristic absorption/transmission of different chemical components and can measure some changes in cell wall composition at the cellular level but can lack sensitivity, and their ability to observe changes at the subcellular level is severely limited.
The dSTORM permits localization of biomolecules with the precision of 5-10 nm; however, the final dSTORM resolution, typically around 40 nm, is limited by the size of the antibody complex (~15-30 nm). The immunogold Electron Microscope (iEM) is also used in combination with ICH to study cellular structures at high resolutions. IEM is comparable to dSTORM resolution and is also limited by the antibody complex size. The size of the nanogold particle defines iEM contrast and resolution; > 1 nm gold nanoparticles are available; however, such a small particle limits the contrast, and larger particles are often used. IEM, contrasted with dSTORM, has several additional drawbacks: (1) the primary antibodies probed with protein-A (or G) gold complexes do not penetrate through the resin-embedded sample, and only recognize the surface epitopes, although the serial and ultra-thin cryo-sectioning technique can resolve this problem (50 nm, -120 °C [Slot, 1989]); (2) samples are mostly single-labeled; yet by using different nanoparticle size, two or three epitopes can be tagged, but it requires the technical experiences of ultra-thin cryo-sectioning technique (Slot and Geuze, 2007); (3) IEM has low labeling and detection efficiency (3-5 orders of magnitude less than dSTORM (Majda et al., 2017; Haas et al., 2020), which is also related to the fact, that only the surface epitopes are labeled. Multicolor 3D dSTORM nanoscopy can, therefore, provide unprecedented insights into the nanoarchitecture of the native-structure of the cell wall polysaccharides, beyond the applicability of the aforementioned techniques. DSTORM permits a quantitative three-dimensional (3D) nanoimaging of cells and tissues (Heilemann et al., 2008; Huang et al., 2008; Van De Linde et al., 2011; Sydor et al., 2015; Xu et al., 2018). Applied mainly to cellular systems, it unveiled new structural organizations of proteins, e.g., synaptic nanodomains, trans-synaptic nanocolumns, DNA recombinase nanofilaments, nuclear envelope pore structure, cytoskeleton, mitochondria, adhesion complexes, and chromatin transcriptional landscape (Shroff et al., 2008; Shim et al., 2012; Löschberger et al., 2012; Jakobs and Wurm, 2014; Prakash et al., 2015; Boettiger et al., 2016; Sellés et al., 2017; Dlasková et al., 2018; Haas et al., 2018a and 2018b; Pan et al., 2018; Xia et al., 2019; Chen et al., 2020; Wäldchen et al., 2020). Yet, due to the limitation of single-cell model systems requiring tissue-level imaging, its utilization in plant science is almost absent (Liesche et al., 2013; Komis et al., 2015; Haas et al., 2020). Here we present a detailed protocol for the sample preparation compatible with a standard confocal microscope and a dSTORM nanoscope on thin plant tissue sections.
Materials and Reagents
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© 2020 The Authors; exclusive licensee Bio-protocol LLC.
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分类
植物科学 > 植物细胞生物学 > 细胞成像
发育生物学 > 形态建成 > 细胞结构
细胞生物学 > 细胞成像 > 固定组织成像
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