scholarly journals CRISPR/Cas9-Based RGEN-ISL Allows the Simultaneous and Specific Visualization of Proteins, DNA Repeats, and Sites of DNA Replication

2019 ◽  
Vol 159 (1) ◽  
pp. 48-53 ◽  
Author(s):  
Alžběta Němečková ◽  
Christina Wäsch ◽  
Veit Schubert ◽  
Takayoshi Ishii ◽  
Eva Hřibová ◽  
...  

Visualizing the spatiotemporal organization of the genome will improve our understanding of how chromatin structure and function are intertwined. Here, we describe a further development of the CRISPR/Cas9-based RNA-guided endonuclease-in situ labeling (RGEN-ISL) method. RGEN-ISL allowed the differentiation between vertebrate-type (TTAGGG)n and Arabidopsis-type (TTTAGGG)n telomere repeats. Using maize as an example, we established a combination of RGEN-ISL, immunostaining, and EdU labeling to visualize in situ specific repeats, histone marks, and DNA replication sites, respectively. The effects of the non-denaturing RGEN-ISL and standard denaturing FISH on the chromatin structure were compared using super-resolution microscopy. 3D structured illumination microscopy revealed that denaturation and acetic acid fixation impaired and flattened the chromatin. The broad range of adaptability of RGEN-ISL to different combinations of methods has the potential to advance the field of chromosome biology.

2020 ◽  
Vol 10 (11) ◽  
pp. 778
Author(s):  
Luca Colnaghi ◽  
Andrea Conz ◽  
Luca Russo ◽  
Clara A. Musi ◽  
Luana Fioriti ◽  
...  

SUMOylation of proteins plays a key role in modulating neuronal function. For this reason, the balance between protein SUMOylation and deSUMOylation requires fine regulation to guarantee the homeostasis of neural tissue. While extensive research has been carried out on the localization and function of small ubiquitin-related modifier (SUMO) variants in neurons, less attention has been paid to the SUMO-specific isopeptidases that constitute the human SUMO-specific isopeptidase (SENP)/Ubiquitin-Specific Protease (ULP) cysteine protease family (SENP1-3 and SENP5-7). Here, for the first time, we studied the localization of SENP1, SENP6, and SENP7 in cultured hippocampal primary neurons at a super resolution detail level, with structured illumination microscopy (SIM). We found that the deSUMOylases partially colocalize with pre- and post-synaptic markers such as synaptophysin and drebrin. Thus, further confirming the presence with synaptic markers of the negative regulators of the SUMOylation machinery.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Abril Angélica Escamilla-Ayala ◽  
Ragna Sannerud ◽  
Magali Mondin ◽  
Karin Poersch ◽  
Wendy Vermeire ◽  
...  

γ-Secretase is a multi-subunit enzyme whose aberrant activity is associated with Alzheimer’s disease and cancer. While its structure is atomically resolved, γ-secretase localization in the membrane in situ relies mostly on biochemical data. Here, we combined fluorescent tagging of γ-secretase subunits with super-resolution microscopy in fibroblasts. Structured illumination microscopy revealed single γ-secretase complexes with a monodisperse distribution and in a 1:1 stoichiometry of PSEN1 and nicastrin subunits. In living cells, sptPALM revealed PSEN1/γ-secretase mainly with directed motility and frequenting ‘hotspots’ or high track-density areas that are sensitive to γ-secretase inhibitors. We visualized γ-secretase association with substrates like amyloid precursor protein and N-cadherin, but not with its sheddases ADAM10 or BACE1 at the cell surface, arguing against pre-formed megadalton complexes. Nonetheless, in living cells PSEN1/γ-secretase transiently visits ADAM10 hotspots. Our results highlight the power of super-resolution microscopy for the study of γ-secretase distribution and dynamics in the membrane.


2021 ◽  
Vol 9 ◽  
Author(s):  
Tianyu Zhao ◽  
Zhaojun Wang ◽  
Tongsheng Chen ◽  
Ming Lei ◽  
Baoli Yao ◽  
...  

Super-resolution microscopy surpasses the diffraction limit to enable the observation of the fine details in sub-cellular structures and their dynamics in diverse biological processes within living cells. Structured illumination microscopy (SIM) uses a relatively low illumination light power compared with other super-resolution microscopies and has great potential to meet the demands of live-cell imaging. However, the imaging acquisition and reconstruction speeds limit its further applications. In this article, recent developments all targeted at improving the overall speed of SIM are reviewed. These comprise both hardware and software improvements, which include a reduction in the number of raw images, GPU acceleration, deep learning and the spatial domain reconstruction. We also discuss the application of these developments in live-cell imaging.


2019 ◽  
Author(s):  
Anna Maria Ranieri ◽  
Kathryn Leslie ◽  
Song Huang ◽  
Stefano Stagni ◽  
Denis Jacquemin ◽  
...  

There is a lack of molecular probes for imaging bacteria, in comparison to the array of such tools available for the imaging of mammalian cells. This is especially so for correlative probes, which are proving to be powerful tools for enhancing the imaging of live cells. In this work a platinum(II)-naphthalimide molecule has been developed to extend small molecule correlative probes to bacterial imaging. The probe was designed to exploit the naphthalimide moiety as a luminescent probe for super-resolution microscopy, with the platinum(II) centre enabling visualisation of the complex with ion nanoscopy. Photophysical characterisation and theoretical studies confirmed that the emission properties of the naphthalimide are not altered by the platinum(II) centre. Structured illumination microscopy (SIM) imaging on live <i>Bacillus cereus</i>revealed that the platinum(II) centre does not change the sub-cellular localisation of the naphthalimide, and confirmed the suitability of the probe for super-resolution microscopy. NanoSIMS analysis of the sample was used to monitor the uptake of the platinum(II) complex within the bacteria and proved the correlative action of the probe. The successful combination of these two probe moieties with no perturbation of their individual detection introduces a platform for a versatile range of new correlative probes for bacteria.


Author(s):  
Kirti Prakash

We report that high-density single-molecule super-resolution microscopy can be achieved with a conventional epifluorescence microscope set-up and a mercury arc lamp. The configuration termed as laser-free super-resolution microscopy (LFSM) is an extension of single-molecule localization microscopy (SMLM) techniques and allows single molecules to be switched on and off (a phenomenon termed as ‘blinking’), detected and localized. The use of a short burst of deep blue excitation (350–380 nm) can be further used to reactivate the blinking, once the blinking process has slowed or stopped. A resolution of 90 nm is achieved on test specimens (mouse and amphibian meiotic chromosomes). Finally, we demonstrate that stimulated emission depletion and LFSM can be performed on the same biological sample using a simple commercial mounting medium. It is hoped that this type of correlative imaging will provide a basis for a further enhanced resolution. This article is part of the Theo Murphy meeting issue ‘Super-resolution structured illumination microscopy (part 1)’.


2019 ◽  
Vol 116 (19) ◽  
pp. 9586-9591 ◽  
Author(s):  
Raphaël Turcotte ◽  
Yajie Liang ◽  
Masashi Tanimoto ◽  
Qinrong Zhang ◽  
Ziwei Li ◽  
...  

Cells in the brain act as components of extended networks. Therefore, to understand neurobiological processes in a physiological context, it is essential to study them in vivo. Super-resolution microscopy has spatial resolution beyond the diffraction limit, thus promising to provide structural and functional insights that are not accessible with conventional microscopy. However, to apply it to in vivo brain imaging, we must address the challenges of 3D imaging in an optically heterogeneous tissue that is constantly in motion. We optimized image acquisition and reconstruction to combat sample motion and applied adaptive optics to correcting sample-induced optical aberrations in super-resolution structured illumination microscopy (SIM) in vivo. We imaged the brains of live zebrafish larvae and mice and observed the dynamics of dendrites and dendritic spines at nanoscale resolution.


2016 ◽  
Vol 09 (03) ◽  
pp. 1630010 ◽  
Author(s):  
Jianling Chen ◽  
Caimin Qiu ◽  
Minghai You ◽  
Xiaogang Chen ◽  
Hongqin Yang ◽  
...  

Optical microscopy allows us to observe the biological structures and processes within living cells. However, the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light diffraction. Structured illumination microscopy (SIM), a type of new emerging super-resolution microscopy, doubles the spatial resolution by illuminating the specimen with a patterned light, and the sample and light source requirements of SIM are not as strict as the other super-resolution microscopy. In addition, SIM is easier to combine with the other imaging techniques to improve their imaging resolution, leading to the developments of diverse types of SIM. SIM has great potential to meet the various requirements of living cells imaging. Here, we review the recent developments of SIM and its combination with other imaging techniques.


Author(s):  
Lucia C. S. Wunderlich ◽  
Florian Ströhl ◽  
Stefan Ströhl ◽  
Oliver Vanderpoorten ◽  
Luca Mascheroni ◽  
...  

AbstractImmunofluorescence microscopy is routinely used in the diagnosis of and research on renal impairments. However, this highly specific technique is restricted in its maximum resolution to about 250 nm in the lateral and 700 nm in the axial directions and thus not sufficient to investigate the fine subcellular structure of the kidney’s glomerular filtration barrier. In contrast, electron microscopy offers high resolution, but this comes at the cost of poor preservation of immunogenic epitopes and antibody penetration alongside a low throughput. Many of these drawbacks were overcome with the advent of super-resolution microscopy methods. So far, four different super-resolution approaches have been used to study the kidney: single-molecule localization microscopy (SMLM), stimulated emission depletion (STED) microscopy, structured illumination microscopy (SIM), and expansion microscopy (ExM), however, using different preservation methods and widely varying labelling strategies. In this work, all four methods were applied and critically compared on kidney slices obtained from samples treated with the most commonly used preservation technique: fixation by formalin and embedding in paraffin (FFPE). Strengths and weaknesses, as well as the practicalities of each method, are discussed to enable users of super-resolution microscopy in renal research make an informed decision on the best choice of technique. The methods discussed enable the efficient investigation of biopsies stored in kidney banks around the world.


2016 ◽  
Vol 214 (7) ◽  
pp. 789-791 ◽  
Author(s):  
Shi-Bin Hu ◽  
Run-Wen Yao ◽  
Ling-Ling Chen

The nuclear body paraspeckle is built on the lncRNA Neat1 and plays important roles in gene regulation. In this issue, West et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201601071) use super-resolution structured illumination microscopy to show that paraspeckles are organized in a core-shell spheroidal structure composed of Neat1 and seven proteins.


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