1
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Feng R, Xie J, Gao L. EDTP enhances and protects the fluorescent signal of GFP in cleared and expanded tissues. Sci Rep 2024; 14:15279. [PMID: 38961181 PMCID: PMC11222453 DOI: 10.1038/s41598-024-66398-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 07/01/2024] [Indexed: 07/05/2024] Open
Abstract
Advanced 3D high-resolution imaging techniques are essential for investigating biological challenges, such as neural circuit analysis and tumor microenvironment in intact tissues. However, the fluorescence signal emitted by endogenous fluorescent proteins in cleared or expanded biological samples gradually diminishes with repeated irradiation and prolonged imaging, compromising its ability to accurately depict the underlying scientific problem. We have developed a strategy to preserve fluorescence in cleared and expanded tissue samples during prolonged high-resolution three-dimensional imaging. We evaluated various compounds at different concentrations to determine their ability to enhance fluorescence intensity and resistance to photobleaching while maintaining the structural integrity of the tissue. Specifically, we investigated the impact of EDTP utilization on GFP, as it has been observed to significantly improve fluorescence intensity, resistance to photobleaching, and maintain fluorescence during extended room temperature storage. This breakthrough will facilitate extended hydrophilic and hydrogel-based clearing and expansion methods for achieving long-term high-resolution 3D imaging of cleared biological tissues by effectively safeguarding fluorescent proteins within the tissue.
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Affiliation(s)
- Ruili Feng
- Fudan University, Shanghai, 200433, China.
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024, Zhejiang, China.
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024, Zhejiang, China.
| | - Jiongfang Xie
- Fudan University, Shanghai, 200433, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024, Zhejiang, China
| | - Liang Gao
- Fudan University, Shanghai, 200433, China
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024, Zhejiang, China
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2
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Bullard MR, Cervantes JCM, Quaicoe NB, Jin A, Adams DA, Lin JM, Iliadis E, Seidler TM, Cervantes-Sandoval I, He HY. Accelerated protein retention expansion microscopy using microwave radiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.11.593228. [PMID: 38766072 PMCID: PMC11100821 DOI: 10.1101/2024.05.11.593228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Protein retention expansion microscopy (ExM) retains genetically encoded fluorescent proteins or antibody-conjugated fluorescent probes in fixed tissue and isotropically expands the tissue through a swellable polymer network to allow nanoscale (<70 nm) resolution on diffraction-limited confocal microscopes. Despite numerous advantages ExM brings to biological studies, the full protocol is time-consuming and can take multiple days to complete. Here, we adapted the ExM protocol to the vibratome-sectioned brain tissue of Xenopus laevis tadpoles and implemented a microwave-assisted protocol to reduce the workflow from days to hours. In addition to the significantly accelerated processing time, our microwave-assisted ExM (M/WExM) protocol maintains the superior resolution and signal-to-noise ratio of the original ExM protocol. Furthermore, the M/WExM protocol yields higher magnitude of expansion, suggesting that in addition to accelerating the process through increased diffusion rate of reagents, microwave radiation may also facilitate the expansion process. To demonstrate the applicability of this method to other specimens and protocols, we adapted the microwave-accelerated protocol to whole mount adult brain tissue of Drosophila melanogaster fruit flies, and successfully reduced the total processing time of a widely-used Drosophila IHC-ExM protocol from 6 days to 2 days. Our results demonstrate that with appropriate adjustment of the microwave parameters (wattage, pulse duration, interval, and number of cycles), this protocol can be readily adapted to different model organisms and tissue types to greatly increase the efficiency of ExM experiments.
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Affiliation(s)
| | | | | | - Amanda Jin
- Department of Biology, Georgetown University, Washington, DC 20057
| | - Danya A. Adams
- Department of Biology, Georgetown University, Washington, DC 20057
| | - Jessica M. Lin
- Department of Biology, Georgetown University, Washington, DC 20057
| | - Elena Iliadis
- Department of Biology, Georgetown University, Washington, DC 20057
| | - Tess M. Seidler
- Department of Biology, Georgetown University, Washington, DC 20057
| | | | - Hai-yan He
- Department of Biology, Georgetown University, Washington, DC 20057
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3
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Balaram P, Takasaki K, Hellevik A, Tandukar J, Turschak E, MacLennan B, Ouellette N, Torres R, Laughland C, Gliko O, Seshamani S, Perlman E, Taormina M, Peterson E, Juneau Z, Potekhina L, Glaser A, Chandrashekar J, Logsdon M, Cao K, Dylla C, Hatanaka G, Chatterjee S, Ting J, Vumbaco D, Waters J, Bair W, Tsao D, Gao R, Reid C. Microscale visualization of cellular features in adult macaque visual cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.02.565381. [PMID: 37961179 PMCID: PMC10635096 DOI: 10.1101/2023.11.02.565381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Expansion microscopy and light sheet imaging enable fine-scale resolution of intracellular features that comprise neural circuits. Most current techniques visualize sparsely distributed features across whole brains or densely distributed features within individual brain regions. Here, we visualize dense distributions of immunolabeled proteins across early visual cortical areas in adult macaque monkeys. This process may be combined with multiphoton or magnetic resonance imaging to produce multimodal atlases in large, gyrencephalic brains.
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4
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Taddei RN, Perbet R, Mate de Gerando A, Wiedmer AE, Sanchez-Mico M, Connors Stewart T, Gaona A, Melloni A, Amaral AC, Duff K, Frosch MP, Gómez-Isla T. Tau Oligomer-Containing Synapse Elimination by Microglia and Astrocytes in Alzheimer Disease. JAMA Neurol 2023; 80:1209-1221. [PMID: 37812432 PMCID: PMC10562992 DOI: 10.1001/jamaneurol.2023.3530] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 08/03/2023] [Indexed: 10/10/2023]
Abstract
Importance Factors associated with synapse loss beyond amyloid-β plaques and neurofibrillary tangles may more closely correlate with the emergence of cognitive deficits in Alzheimer disease (AD) and be relevant for early therapeutic intervention. Objective To investigate whether accumulation of tau oligomers in synapses is associated with excessive synapse elimination by microglia or astrocytes and with cognitive outcomes (dementia vs no dementia [hereinafter termed resilient]) of individuals with equal burdens of AD neuropathologic changes at autopsy. Design, Setting, and Participants This cross-sectional postmortem study included 40 human brains from the Massachusetts Alzheimer Disease Research Center Brain Bank with Braak III to IV stages of tau pathology but divergent antemortem cognition (dementia vs resilient) and cognitively normal controls with negligible AD neuropathologic changes. The visual cortex, a region without tau tangle deposition at Braak III to IV stages, was assessed after expansion microscopy to analyze spatial relationships of synapses with microglia and astrocytes. Participants were matched for age, sex, and apolipoprotein E status. Evidence of Lewy bodies, TDP-43 aggregates, or other lesions different from AD neuropathology were exclusion criteria. Tissue was collected from July 1998 to November 2020, and analyses were conducted from February 1, 2022, through May 31, 2023. Main Outcomes and Measures Amyloid-β plaques, tau neuropil thread burden, synapse density, tau oligomers in synapses, and internalization of tau oligomer-tagged synapses by microglia and astrocytes were quantitated. Analyses were performed using 1-way analysis of variance for parametric variables and the Kruskal-Wallis test for nonparametric variables; between-group differences were evaluated with Holm-Šídák tests. Results Of 40 included participants (mean [SD] age at death, 88 [8] years; 21 [52%] male), 19 had early-stage dementia with Braak stages III to IV, 13 had resilient brains with similar Braak stages III to IV, and 8 had no dementia (Braak stages 0-II). Brains with dementia but not resilient brains had substantial loss of presynaptic (43%), postsynaptic (33%), and colocalized mature synaptic elements (38%) compared with controls and significantly higher percentages of mature synapses internalized by IBA1-positive microglia (mean [SD], 13.3% [3.9%] in dementia vs 2.6% [1.9%] in resilient vs 0.9% [0.5%] in control; P < .001) and by GFAP-positive astrocytes (mean [SD], 17.2% [10.9%] in dementia vs 3.7% [4.0%] in resilient vs 2.7% [1.8%] in control; P = .001). In brains with dementia but not in resilient brains, tau oligomers more often colocalized with synapses, and the proportions of tau oligomer-containing synapses inside microglia (mean [SD] for presynapses, mean [SD], 7.4% [1.8%] in dementia vs 5.1% [1.9%] resilient vs 3.7% [0.8%] control; P = .006; and for postsynapses 11.6% [3.6%] dementia vs 6.8% [1.3%] resilient vs 7.4% [2.5%] control; P = .001) and astrocytes (mean [SD] for presynapses, 7.0% [2.1%] dementia vs 4.3% [2.2%] resilient vs 4.0% [0.7%] control; P = .001; and for postsynapses, 7.9% [2.2%] dementia vs 5.3% [1.8%] resilient vs 3.0% [1.5%] control; P < .001) were significantly increased compared with controls. Those changes in brains with dementia occurred in the absence of tau tangle deposition in visual cortex. Conclusion and Relevance The findings from this cross-sectional study suggest that microglia and astrocytes may excessively engulf synapses in brains of individuals with dementia and that the abnormal presence of tau oligomers in synapses may serve as signals for increased glial-mediated synapse elimination and early loss of brain function in AD.
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Affiliation(s)
- Raquel N. Taddei
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
- Department of Neurology, Dementia Research Institute, University College London, United Kingdom
| | - Romain Perbet
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | | | - Anne E. Wiedmer
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Maria Sanchez-Mico
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Theresa Connors Stewart
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Angelica Gaona
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Alexandra Melloni
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Ana C. Amaral
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
| | - Karen Duff
- Department of Neurology, Dementia Research Institute, University College London, United Kingdom
| | - Matthew P. Frosch
- C.S. Kubik Laboratory for Neuropathology, Massachusetts General Hospital, Boston, Massachusetts
| | - Teresa Gómez-Isla
- Neurology Department, Massachusetts General Hospital, Harvard University, Boston, Massachusetts
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5
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Saal KA, Shaib AH, Mougios N, Crzan D, Opazo F, Rizzoli SO. Heat denaturation enables multicolor X10-STED microscopy. Sci Rep 2023; 13:5366. [PMID: 37005431 PMCID: PMC10067834 DOI: 10.1038/s41598-023-32524-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 03/29/2023] [Indexed: 04/04/2023] Open
Abstract
Expansion microscopy (ExM) improves imaging quality by physically enlarging the biological specimens. In principle, combining a large expansion factor with optical super-resolution should provide extremely high imaging precision. However, large expansion factors imply that the expanded specimens are dim and are therefore poorly suited for optical super-resolution. To solve this problem, we present a protocol that ensures the expansion of the samples up to 10-fold, in a single expansion step, through high-temperature homogenization (X10ht). The resulting gels exhibit a higher fluorescence intensity than gels homogenized using enzymatic digestion (based on proteinase K). This enables the sample analysis by multicolor stimulated emission depletion (STED) microscopy, for a final resolution of 6-8 nm in neuronal cell cultures or isolated vesicles. X10ht also enables the expansion of 100-200 µm thick brain samples, up to 6-fold. The better epitope preservation also enables the use of nanobodies as labeling probes and the implementation of post-expansion signal amplification. We conclude that X10ht is a promising tool for nanoscale resolution in biological samples.
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Affiliation(s)
- Kim Ann Saal
- Department of Sensory- and Neurophysiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
| | - Ali H Shaib
- Department of Sensory- and Neurophysiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Nikolaos Mougios
- Department of Sensory- and Neurophysiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), Von-Sieboldt-Str. 3a, 37075, Göttingen, Germany
| | - Dagmar Crzan
- Department of Sensory- and Neurophysiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
| | - Felipe Opazo
- Department of Sensory- and Neurophysiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany
- NanoTag Biotechnologies GmbH, Rudolf Wissell Str. 28a, 37079, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), Von-Sieboldt-Str. 3a, 37075, Göttingen, Germany
| | - Silvio O Rizzoli
- Department of Sensory- and Neurophysiology, University Medical Center Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration (BIN), Von-Sieboldt-Str. 3a, 37075, Göttingen, Germany.
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6
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Ghosh S, Sapkota BS, Rao RS, Patil S, Rajkumar C, Lakshminarayan S. Expansion microscopy: A revolution in diagnostic pathology. J Microsc 2023; 290:3-9. [PMID: 36641735 DOI: 10.1111/jmi.13170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 12/21/2022] [Accepted: 01/09/2023] [Indexed: 01/16/2023]
Abstract
Expansion microscopy (ExM) is a recent discovery in diagnostic pathology and microbiology that promotes a physical magnification of the tissue specimen instead of optical magnification. It not only improves the resolution of the specimen but also enhances the diagnostic precision, and permits nanoscale imaging of the specimen. Optical microscopy is routinely used in histopathology and microbiology for ages. Due to its simplicity, compatibility with different types of specimens, and ease of operation it is accepted by pathologists. ExM and its variants have been widely tested in different types of tissue specimens and microbiological specimens and yielded brilliant results.
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Affiliation(s)
- Snehashish Ghosh
- Department of Oral Pathology, College of Medical Sciences, Bharatpur, Nepal
| | | | - Roopa S Rao
- Faculty of Dental Sciences, Department of Oral Pathology, Ramaiah University of Applied Sciences, Bangalore, India
| | - Shankargouda Patil
- College of Dental Medicine, Roseman University of Health Sciences, South Jordan, Utah
- Centre of Molecular Medicine and Diagnostics (COMManD), Saveetha Dental College and Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, India
| | - Chandini Rajkumar
- Department of Oral Pathology and Microbiology, Sathyabama Dental College and Hospital, Chennai, India
| | - Surendra Lakshminarayan
- Department of Oral Pathology and Microbiology, Faculty of Dental Sciences, Ramaiah University of Applied Sciences, Bengaluru, India
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7
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Lopes MM, Paysan J, Rino J, Lopes SM, Pereira de Almeida L, Cortes L, Nobre RJ. A new protocol for whole-brain biodistribution analysis of AAVs by tissue clearing, light-sheet microscopy and semi-automated spatial quantification. Gene Ther 2022; 29:665-679. [PMID: 36316447 DOI: 10.1038/s41434-022-00372-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 10/04/2022] [Accepted: 10/10/2022] [Indexed: 12/23/2022]
Abstract
Recombinant adeno-associated virus (rAAV) has become one of the most promising gene delivery systems for both in vitro and in vivo applications. However, a key challenge is the lack of suitable imaging technologies to evaluate delivery, biodistribution and tropism of rAAVs and efficiently monitor disease amelioration promoted by AAV-based therapies at a whole-organ level with single-cell resolution. Therefore, we aimed to establish a new pipeline for the biodistribution analysis of natural and new variants of AAVs at a whole-brain level by tissue clearing and light-sheet fluorescence microscopy (LSFM). To test this platform, neonatal C57BL/6 mice were intravenously injected with rAAV9 encoding EGFP and, after sacrifice, brains were processed by standard immunohistochemistry and a recently released aqueous-based clearing procedure. This clearing technique required no dedicated equipment and rendered highly cleared brains, while simultaneously preserving endogenous fluorescence. Moreover, three-dimensional imaging by LSFM allowed the quantitative analysis of EGFP at a whole-brain level, as well as the reconstruction of Purkinje cells for the retrieval of valuable morphological information inaccessible by standard immunohistochemistry. In conclusion, the pipeline herein described takes the AAVs to a new level when coupled to LSFM, proving its worth as a bioimaging tool in tropism and gene therapy studies.
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Affiliation(s)
- Miguel M Lopes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,IIIUC - Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | | | - José Rino
- iMM - Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sara M Lopes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,IIIUC - Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Luís Pereira de Almeida
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal. .,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal. .,ViraVector - Viral Vectors for Gene Transfer Core Facility, University of Coimbra, Coimbra, Portugal. .,FFUC - Faculty of Pharmacy of the University of Coimbra, Coimbra, Portugal.
| | - Luísa Cortes
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal. .,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal. .,IIIUC - Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal. .,MICC-CNC - Microscopy Imaging Center of Coimbra - CNC, University of Coimbra, Coimbra, Portugal.
| | - Rui Jorge Nobre
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal. .,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal. .,IIIUC - Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal. .,ViraVector - Viral Vectors for Gene Transfer Core Facility, University of Coimbra, Coimbra, Portugal.
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8
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Single p197 molecules of the mitochondrial genome segregation system of Trypanosoma brucei determine the distance between basal body and outer membrane. Proc Natl Acad Sci U S A 2022; 119:e2204294119. [PMID: 36161893 PMCID: PMC9546609 DOI: 10.1073/pnas.2204294119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Segregation of the replicated single unit mitochondrial genome of Trypanosoma brucei requires a large hardwired structure that connects the organellar DNA with the flagellar basal body. The cytosolic part of this structure consists of filaments made of p197 molecules, a protein with a molecular weight of approximately 660 kDa. The N terminus of p197 is anchored to the peripheral mitochondrial outer membrane protein TAC65, whereas its C terminus connects to the base of the basal body. The large α-helical central domain of p197 consists of approximately 26 repeats each 175 aa in length. It provides a flexible spacer that connects the outer membrane with the basal body and determines the distance between the two structures. The tripartite attachment complex (TAC) couples the segregation of the single unit mitochondrial DNA of trypanosomes with the basal body (BB) of the flagellum. Here, we studied the architecture of the exclusion zone filament (EZF) of the TAC, the only known component of which is p197, that connects the BB with the mitochondrial outer membrane (OM). We show that p197 has three domains that are all essential for mitochondrial DNA inheritance. The C terminus of p197 interacts with the mature and probasal body (pro-BB), whereas its N terminus binds to the peripheral OM protein TAC65. The large central region of p197 has a high α-helical content and likely acts as a flexible spacer. Ultrastructure expansion microscopy (U-ExM) of cell lines exclusively expressing p197 versions of different lengths that contain both N- and C-terminal epitope tags demonstrates that full-length p197 alone can bridge the ∼270-nm distance between the BB and the cytosolic face of the OM. Thus U-ExM allows the localization of distinct domains within the same molecules and suggests that p197 is the TAC subunit most proximal to the BB. In addition, U-ExM revealed that p197 acts as a spacer molecule, as two shorter versions of p197, with the repeat domain either removed or replaced by the central domain of the Trypanosoma cruzi p197 ortholog reduced the distance between the BB and the OM in proportion to their predicted molecular weight.
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9
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Babi M, Neuman K, Peng CY, Maiuri T, Suart CE, Truant R. Recent Microscopy Advances and the Applications to Huntington’s Disease Research. J Huntingtons Dis 2022; 11:269-280. [PMID: 35848031 PMCID: PMC9484089 DOI: 10.3233/jhd-220536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Huntingtin is a 3144 amino acid protein defined as a scaffold protein with many intracellular locations that suggest functions in these compartments. Expansion of the CAG DNA tract in the huntingtin first exon is the cause of Huntington’s disease. An important tool in understanding the biological functions of huntingtin is molecular imaging at the single-cell level by microscopy and nanoscopy. The evolution of these technologies has accelerated since the Nobel Prize in Chemistry was awarded in 2014 for super-resolution nanoscopy. We are in a new era of light imaging at the single-cell level, not just for protein location, but also for protein conformation and biochemical function. Large-scale microscopy-based screening is also being accelerated by a coincident development of machine-based learning that offers a framework for truly unbiased data acquisition and analysis at very large scales. This review will summarize the newest technologies in light, electron, and atomic force microscopy in the context of unique challenges with huntingtin cell biology and biochemistry.
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Affiliation(s)
- Mouhanad Babi
- McMaster Centre for Advanced Light Microscopy (CALM) McMaster University, Hamilton, Canada
| | - Kaitlyn Neuman
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Christina Y. Peng
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Tamara Maiuri
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Celeste E. Suart
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Ray Truant
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
- McMaster Centre for Advanced Light Microscopy (CALM) McMaster University, Hamilton, Canada
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10
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Ayuso-Jimeno IP, Ronchi P, Wang T, Gallori CE, Gross CT. Identifying long-range synaptic inputs using genetically encoded labels and volume electron microscopy. Sci Rep 2022; 12:10213. [PMID: 35715545 PMCID: PMC9205864 DOI: 10.1038/s41598-022-14309-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 06/06/2022] [Indexed: 11/08/2022] Open
Abstract
Enzymes that facilitate the local deposition of electron dense reaction products have been widely used as labels in electron microscopy (EM) for the identification of synaptic contacts in neural tissue. Peroxidases, in particular, can efficiently metabolize 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) to produce precipitates with high contrast under EM following heavy metal staining, and can be genetically encoded to facilitate the labeling of specific cell-types or organelles. Nevertheless, the peroxidase/DAB method has so far not been reported to work in a multiplexed manner in combination with 3D volume EM techniques (e.g. Serial blockface electron microscopy, SBEM; Focused ion beam electron microscopy, FIBSEM) that are favored for the large-scale ultrastructural assessment of synaptic architecture However, a recently described peroxidase with enhanced enzymatic activity (dAPEX2) can efficienty deposit EM-visible DAB products in thick tissue without detergent treatment opening the possibility for the multiplex labeling of genetically defined cell-types in combination with volume EM methods. Here we demonstrate that multiplexed dAPEX2/DAB tagging is compatible with both FIBSEM and SBEM volume EM approaches and use them to map long-range genetically identified synaptic inputs from the anterior cingulate cortex to the periaqueductal gray in the mouse brain.
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Affiliation(s)
- Irene P Ayuso-Jimeno
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy
| | - Paolo Ronchi
- Electron Microscopy Core Facility (EMCF), European Molecular Biology Laboratory (EMBL), 69117, Meyerhofstr, Germany
| | - Tianzi Wang
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy
| | - Catherine E Gallori
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy
| | - Cornelius T Gross
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Via Ramarini 32, 00015, Monterotondo, RM, Italy.
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11
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Sun Y, Zhang Z, Bing T, Liu J, Li W, Liu X, Zhang N, Shu Y, Wang J, Shangguan D. Aptamer-Based Cell Nucleus Imaging via Expansion Microscopy. Anal Chem 2022; 94:6044-6049. [PMID: 35380789 DOI: 10.1021/acs.analchem.2c00773] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Expansion microscopy (ExM) is a newly developed technology in recent years that enables nanoscale imaging under conventional microscopes. Herein, we report an aptamer-based ExM imaging strategy. A nucleus-targeting aptamer Ch4-1 was chemically labeled with a dye and an acrydite at each end to perform the functions of molecular recognition, fluorescence reporting, and gel anchoring. After binding cell nucleus, the dual labeled aptamer Ac-Ch4-1-FAM directly participated in gelation and anchored in polyacrylamide gel. After expanding the gel, high-resolution imaging was achieved by confocal microscopy. Multicolor ExM imaging was also realized by combining Ac-Ch4-1-FAM, antibodies and fluorescent dyes. This aptamer-based ExM could clearly image the chromatin morphology at different mitotic stages. The expansion process is simple and the aptamer labeling is easy. The aptamer-based ExM holds great promise in super-resolution imaging of cells and tissues.
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Affiliation(s)
- Yue Sun
- Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China.,Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhicheng Zhang
- Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China.,Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Tao Bing
- The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer (IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jing Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weiwei Li
- The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer (IBMC), Chinese Academy of Sciences, Hangzhou, Zhejiang 310022, China.,School of Molecular Medicine, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310013, China
| | - Xiangjun Liu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nan Zhang
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Shu
- Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China
| | - Jianhua Wang
- Department of Chemistry, College of Sciences, Northeastern University, Shenyang 110819, China
| | - Dihua Shangguan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,School of Molecular Medicine, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310013, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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12
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Sneve MA, Piatkevich KD. Towards a Comprehensive Optical Connectome at Single Synapse Resolution via Expansion Microscopy. Front Synaptic Neurosci 2022; 13:754814. [PMID: 35115916 PMCID: PMC8803729 DOI: 10.3389/fnsyn.2021.754814] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 12/17/2021] [Indexed: 12/04/2022] Open
Abstract
Mapping and determining the molecular identity of individual synapses is a crucial step towards the comprehensive reconstruction of neuronal circuits. Throughout the history of neuroscience, microscopy has been a key technology for mapping brain circuits. However, subdiffraction size and high density of synapses in brain tissue make this process extremely challenging. Electron microscopy (EM), with its nanoscale resolution, offers one approach to this challenge yet comes with many practical limitations, and to date has only been used in very small samples such as C. elegans, tadpole larvae, fruit fly brain, or very small pieces of mammalian brain tissue. Moreover, EM datasets require tedious data tracing. Light microscopy in combination with tissue expansion via physical magnification-known as expansion microscopy (ExM)-offers an alternative approach to this problem. ExM enables nanoscale imaging of large biological samples, which in combination with multicolor neuronal and synaptic labeling offers the unprecedented capability to trace and map entire neuronal circuits in fully automated mode. Recent advances in new methods for synaptic staining as well as new types of optical molecular probes with superior stability, specificity, and brightness provide new modalities for studying brain circuits. Here we review advanced methods and molecular probes for fluorescence staining of the synapses in the brain that are compatible with currently available expansion microscopy techniques. In particular, we will describe genetically encoded probes for synaptic labeling in mice, zebrafish, Drosophila fruit flies, and C. elegans, which enable the visualization of post-synaptic scaffolds and receptors, presynaptic terminals and vesicles, and even a snapshot of the synaptic activity itself. We will address current methods for applying these probes in ExM experiments, as well as appropriate vectors for the delivery of these molecular constructs. In addition, we offer experimental considerations and limitations for using each of these tools as well as our perspective on emerging tools.
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Affiliation(s)
- Madison A Sneve
- Department of Brain and Cognitive Sciences, MIT, Cambridge, MA, United States
| | - Kiryl D Piatkevich
- School of Life Sciences, Westlake University, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, Hangzhou, China
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, China
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13
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Brzozowski CF, Hijaz BA, Singh V, Gcwensa NZ, Kelly K, Boyden ES, West AB, Sarkar D, Volpicelli-Daley LA. Inhibition of LRRK2 kinase activity promotes anterograde axonal transport and presynaptic targeting of α-synuclein. Acta Neuropathol Commun 2021; 9:180. [PMID: 34749824 PMCID: PMC8576889 DOI: 10.1186/s40478-021-01283-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/20/2021] [Indexed: 01/18/2023] Open
Abstract
Pathologic inclusions composed of α-synuclein called Lewy pathology are hallmarks of Parkinson’s Disease (PD). Dominant inherited mutations in leucine rich repeat kinase 2 (LRRK2) are the most common genetic cause of PD. Lewy pathology is found in the majority of individuals with LRRK2-PD, particularly those with the G2019S-LRRK2 mutation. Lewy pathology in LRRK2-PD associates with increased non-motor symptoms such as cognitive deficits, anxiety, and orthostatic hypotension. Thus, understanding the relationship between LRRK2 and α-synuclein could be important for determining the mechanisms of non-motor symptoms. In PD models, expression of mutant LRRK2 reduces membrane localization of α-synuclein, and enhances formation of pathologic α-synuclein, particularly when synaptic activity is increased. α-Synuclein and LRRK2 both localize to the presynaptic terminal. LRRK2 plays a role in membrane traffic, including axonal transport, and therefore may influence α-synuclein synaptic localization. This study shows that LRRK2 kinase activity influences α-synuclein targeting to the presynaptic terminal. We used the selective LRRK2 kinase inhibitors, MLi-2 and PF-06685360 (PF-360) to determine the impact of reduced LRRK2 kinase activity on presynaptic localization of α-synuclein. Expansion microscopy (ExM) in primary hippocampal cultures and the mouse striatum, in vivo, was used to more precisely resolve the presynaptic localization of α-synuclein. Live imaging of axonal transport of α-synuclein-GFP was used to investigate the impact of LRRK2 kinase inhibition on α-synuclein axonal transport towards the presynaptic terminal. Reduced LRRK2 kinase activity increases α-synuclein overlap with presynaptic markers in primary neurons, and increases anterograde axonal transport of α-synuclein-GFP. In vivo, LRRK2 inhibition increases α-synuclein overlap with glutamatergic, cortico-striatal terminals, and dopaminergic nigral-striatal presynaptic terminals. The findings suggest that LRRK2 kinase activity plays a role in axonal transport, and presynaptic targeting of α-synuclein. These data provide potential mechanisms by which LRRK2-mediated perturbations of α-synuclein localization could cause pathology in both LRRK2-PD, and idiopathic PD.
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14
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Endo M, Maruoka H, Okabe S. Advanced Technologies for Local Neural Circuits in the Cerebral Cortex. Front Neuroanat 2021; 15:757499. [PMID: 34803616 PMCID: PMC8595196 DOI: 10.3389/fnana.2021.757499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
The neural network in the brain can be viewed as an integrated system assembled from a large number of local neural circuits specialized for particular brain functions. Activities of neurons in local neural circuits are thought to be organized both spatially and temporally under the rules optimized for their roles in information processing. It is well perceived that different areas of the mammalian neocortex have specific cognitive functions and distinct computational properties. However, the organizational principles of the local neural circuits in different cortical regions have not yet been clarified. Therefore, new research principles and related neuro-technologies that enable efficient and precise recording of large-scale neuronal activities and synaptic connections are necessary. Innovative technologies for structural analysis, including tissue clearing and expansion microscopy, have enabled super resolution imaging of the neural circuits containing thousands of neurons at a single synapse resolution. The imaging resolution and volume achieved by new technologies are beyond the limits of conventional light or electron microscopic methods. Progress in genome editing and related technologies has made it possible to label and manipulate specific cell types and discriminate activities of multiple cell types. These technologies will provide a breakthrough for multiscale analysis of the structure and function of local neural circuits. This review summarizes the basic concepts and practical applications of the emerging technologies and new insight into local neural circuits obtained by these technologies.
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Affiliation(s)
| | | | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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15
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Kang S, Park S, Song H, Choi D, Park HE, Ahn BH, Kim SY, Lee Y. Expansion Microscopy with a Thermally Adjustable Expansion Factor Using Thermoresponsive Biospecimen-Hydrogel Hybrids. ACS APPLIED MATERIALS & INTERFACES 2021; 13:28962-28974. [PMID: 34107679 DOI: 10.1021/acsami.1c07592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Expansion microscopy (ExM) is a technique in which swellable hydrogel-embedded biological samples are physically expanded to effectively increase imaging resolution. Here, we develop thermoresponsive reversible ExM (T-RevExM), in which the expansion factor can be thermally adjusted in a reversible manner. In this method, samples are embedded in thermoresponsive hydrogels and partially digested to allow for reversible swelling of the sample-gel hybrid in a temperature-dependent manner. We first synthesized hydrogels exhibiting lower critical solution temperature (LCST)- and upper critical solution temperature (UCST)-phase transition properties with N-alkyl acrylamide or sulfobetaine monomers, respectively. We then formed covalent hybrids between the LCST or UCST hydrogel and biomolecules across the cultured cells and tissues. The resulting hybrid could be reversibly swelled or deswelled in a temperature-dependent manner, with LCST- and UCST-based hybrids negatively and positively responding to the increase in temperature (termed thermonegative RevExM and thermopositive RevExM, respectively). We further showed reliable imaging of both unexpanded and expanded cells and tissues and demonstrated minimal distortions from the original sample using conventional confocal microscopy. Thus, T-RevExM enables easy adjustment of the size of biological samples and therefore the effective magnification and resolution of the sample, simply by changing the sample temperature.
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Affiliation(s)
- Sunah Kang
- Department of Chemistry, College of Natural Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Sohyun Park
- Department of Chemistry, College of Natural Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Hojoon Song
- Department of Chemistry, College of Natural Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Dongkil Choi
- Department of Chemistry, College of Natural Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Han-Eol Park
- Institute of Molecular Biology and Genetics, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Benjamin H Ahn
- Department of Chemistry, College of Natural Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
- Institute of Molecular Biology and Genetics, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Sung-Yon Kim
- Department of Chemistry, College of Natural Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
- Institute of Molecular Biology and Genetics, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Yan Lee
- Department of Chemistry, College of Natural Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
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16
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Cover KK, Mathur BN. Axo-axonic synapses: Diversity in neural circuit function. J Comp Neurol 2021; 529:2391-2401. [PMID: 33314077 PMCID: PMC8053672 DOI: 10.1002/cne.25087] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/20/2022]
Abstract
The chemical synapse is the principal form of contact between neurons of the central nervous system. These synapses are typically configured as presynaptic axon terminations onto postsynaptic dendrites or somata, giving rise to axo-dendritic and axo-somatic synapses, respectively. Beyond these common synapse configurations are less-studied, non-canonical synapse types that are prevalent throughout the brain and significantly contribute to neural circuit function. Among these are the axo-axonic synapses, which consist of an axon terminating on another axon or axon terminal. Here, we review evidence for axo-axonic synapse contributions to neural signaling in the mammalian nervous system and survey functional neural circuit motifs enabled by these synapses. We also detail how recent advances in microscopy, transgenics, and biological sensors may be used to identify and functionally assay axo-axonic synapses.
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Affiliation(s)
- Kara K. Cover
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD USA 21201
| | - Brian N. Mathur
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD USA 21201
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17
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Choquet D, Sainlos M, Sibarita JB. Advanced imaging and labelling methods to decipher brain cell organization and function. Nat Rev Neurosci 2021; 22:237-255. [PMID: 33712727 DOI: 10.1038/s41583-021-00441-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2021] [Indexed: 01/31/2023]
Abstract
The brain is arguably the most complex organ. The branched and extended morphology of nerve cells, their subcellular complexity, the multiplicity of brain cell types as well as their intricate connectivity and the scattering properties of brain tissue present formidable challenges to the understanding of brain function. Neuroscientists have often been at the forefront of technological and methodological developments to overcome these hurdles to visualize, quantify and modify cell and network properties. Over the last few decades, the development of advanced imaging methods has revolutionized our approach to explore the brain. Super-resolution microscopy and tissue imaging approaches have recently exploded. These instrumentation-based innovations have occurred in parallel with the development of new molecular approaches to label protein targets, to evolve new biosensors and to target them to appropriate cell types or subcellular compartments. We review the latest developments for labelling and functionalizing proteins with small localization and functionalized reporters. We present how these molecular tools are combined with the development of a wide variety of imaging methods that break either the diffraction barrier or the tissue penetration depth limits. We put these developments in perspective to emphasize how they will enable step changes in our understanding of the brain.
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Affiliation(s)
- Daniel Choquet
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France. .,University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, Bordeaux, France.
| | - Matthieu Sainlos
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
| | - Jean-Baptiste Sibarita
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
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18
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Mohr SE, Tattikota SG, Xu J, Zirin J, Hu Y, Perrimon N. Methods and tools for spatial mapping of single-cell RNAseq clusters in Drosophila. Genetics 2021; 217:6156631. [PMID: 33713129 DOI: 10.1093/genetics/iyab019] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/02/2021] [Indexed: 01/26/2023] Open
Abstract
Single-cell RNA sequencing (scRNAseq) experiments provide a powerful means to identify clusters of cells that share common gene expression signatures. A major challenge in scRNAseq studies is to map the clusters to specific anatomical regions along the body and within tissues. Existing data, such as information obtained from large-scale in situ RNA hybridization studies, cell type specific transcriptomics, gene expression reporters, antibody stainings, and fluorescent tagged proteins, can help to map clusters to anatomy. However, in many cases, additional validation is needed to precisely map the spatial location of cells in clusters. Several approaches are available for spatial resolution in Drosophila, including mining of existing datasets, and use of existing or new tools for direct or indirect detection of RNA, or direct detection of proteins. Here, we review available resources and emerging technologies that will facilitate spatial mapping of scRNAseq clusters at high resolution in Drosophila. Importantly, we discuss the need, available approaches, and reagents for multiplexing gene expression detection in situ, as in most cases scRNAseq clusters are defined by the unique coexpression of sets of genes.
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Affiliation(s)
- Stephanie E Mohr
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sudhir Gopal Tattikota
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jun Xu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jonathan Zirin
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.,Howard Hughes Medical Institute, Boston, MA 02115, USA
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19
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Zhao J, Lai HM, Qi Y, He D, Sun H. Current Status of Tissue Clearing and the Path Forward in Neuroscience. ACS Chem Neurosci 2021; 12:5-29. [PMID: 33326739 DOI: 10.1021/acschemneuro.0c00563] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Due to the complexity and limited availability of human brain tissues, for decades, pathologists have sought to maximize information gained from individual samples, based on which (patho)physiological processes could be inferred. Recently, new understandings of chemical and physical properties of biological tissues and multiple chemical profiling have given rise to the development of scalable tissue clearing methods allowing superior optical clearing of across-the-scale samples. In the past decade, tissue clearing techniques, molecular labeling methods, advanced laser scanning microscopes, and data visualization and analysis have become commonplace. Combined, they have made 3D visualization of brain tissues with unprecedented resolution and depth widely accessible. To facilitate further advancements and applications, here we provide a critical appraisal of these techniques. We propose a classification system of current tissue clearing and expansion methods that allows users to judge the applicability of individual ones to their questions, followed by a review of the current progress in molecular labeling, optical imaging, and data processing to demonstrate the whole 3D imaging pipeline based on tissue clearing and downstream techniques for visualizing the brain. We also raise the path forward of tissue-clearing-based imaging technology, that is, integrating with state-of-the-art techniques, such as multiplexing protein imaging, in situ signal amplification, RNA detection and sequencing, super-resolution imaging techniques, multiomics studies, and deep learning, for drawing the complete atlas of the human brain and building a 3D pathology platform for central nervous system disorders.
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Affiliation(s)
- Jiajia Zhao
- Department of Neurosurgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou 510515, China
- The Second Clinical Medical College, Southern Medical University, Guangzhou 510515, China
| | - Hei Ming Lai
- Department of Psychiatry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Yuwei Qi
- Department of Neurosurgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou 510515, China
- The Second Clinical Medical College, Southern Medical University, Guangzhou 510515, China
| | - Dian He
- Department of Neurosurgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou 510515, China
- The Second Clinical Medical College, Southern Medical University, Guangzhou 510515, China
| | - Haitao Sun
- Department of Neurosurgery, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Zhujiang Hospital, Southern Medical University, Guangzhou 510515, China
- The Second Clinical Medical College, Southern Medical University, Guangzhou 510515, China
- Microbiome Medicine Center, Department of Laboratory Medicine, Clinical Biobank Center, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou 510515, China
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20
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Abstract
Expansion microscopy is a recently developed super-resolution imaging technique, which provides an alternative to optics-based methods such as deterministic approaches (e.g. STED) or stochastic approaches (e.g. PALM/STORM). The idea behind expansion microscopy is to embed the biological sample in a swellable gel, and then to expand it isotropically, thereby increasing the distance between the fluorophores. This approach breaks the diffraction barrier by simply separating the emission point-spread-functions of the fluorophores. The resolution attainable in expansion microscopy is thus directly dependent on the separation that can be achieved, i.e. on the expansion factor. The original implementation of the technique achieved an expansion factor of fourfold, for a resolution of 70-80nm. The subsequently developed X10 method achieves an expansion factor of 10-fold, for a resolution of 25-30nm. This technique can be implemented with minimal technical requirements on any standard fluorescence microscope, and is more easily applied for multi-color imaging than either deterministic or stochastic super-resolution approaches. This renders X10 expansion microscopy a highly promising tool for new biological discoveries, as discussed here, and as demonstrated by several recent applications.
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Affiliation(s)
- Sven Truckenbrodt
- Institute of Science and Technology Austria, Am Campus 1, Klosterneuburg, Austria.
| | - Silvio O Rizzoli
- Institute for Neuro- and Sensory Physiology, Göttingen, Germany; Center for Biostructural Imaging of Neurodegeneration, Göttingen, Germany
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21
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Bucur O, Fu F, Calderon M, Mylvaganam GH, Ly NL, Day J, Watkin S, Walker BD, Boyden ES, Zhao Y. Nanoscale imaging of clinical specimens using conventional and rapid-expansion pathology. Nat Protoc 2020; 15:1649-1672. [PMID: 32238952 DOI: 10.1038/s41596-020-0300-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 01/16/2020] [Indexed: 11/09/2022]
Abstract
In pathology, microscopy is an important tool for the analysis of human tissues, both for the scientific study of disease states and for diagnosis. However, the microscopes commonly used in pathology are limited in resolution by diffraction. Recently, we discovered that it was possible, through a chemical process, to isotropically expand preserved cells and tissues by 4-5× in linear dimension. We call this process expansion microscopy (ExM). ExM enables nanoscale resolution imaging on conventional microscopes. Here we describe protocols for the simple and effective physical expansion of a variety of human tissues and clinical specimens, including paraffin-embedded, fresh frozen and chemically stained human tissues. These protocols require only inexpensive, commercially available reagents and hardware commonly found in a routine pathology laboratory. Our protocols are written for researchers and pathologists experienced in conventional fluorescence microscopy. The conventional protocol, expansion pathology, can be completed in ~1 d with immunostained tissue sections and 2 d with unstained specimens. We also include a new, fast variant, rapid expansion pathology, that can be performed on <5-µm-thick tissue sections, taking <4 h with immunostained tissue sections and <8 h with unstained specimens.
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Affiliation(s)
- Octavian Bucur
- Department of Pathology and Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.,Ludwig Center at Harvard Medical School, Boston, MA, USA.,Institute of Biochemistry of the Romanian Academy, Bucharest, Romania.,QPathology, Boston, MA, USA
| | - Feifei Fu
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Mike Calderon
- Center for Biologic Imaging, Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Geetha H Mylvaganam
- Ragon Institute of MGH, MIT and Harvard and Harvard University Center for AIDS Research, Cambridge, MA, USA.,Massachussetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Ngoc L Ly
- Ragon Institute of MGH, MIT and Harvard and Harvard University Center for AIDS Research, Cambridge, MA, USA.,Massachussetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jimmy Day
- Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Simon Watkin
- Center for Biologic Imaging, Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Bruce D Walker
- Ragon Institute of MGH, MIT and Harvard and Harvard University Center for AIDS Research, Cambridge, MA, USA.,Massachussetts General Hospital, Harvard Medical School, Boston, MA, USA.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Edward S Boyden
- Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. .,McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Koch Institute, Massachusetts Institute of Technology, Cambridge, MA, USA. .,Center for Neurobiological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Yongxin Zhao
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA. .,Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA.
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22
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Groh C, Rössler W. Analysis of Synaptic Microcircuits in the Mushroom Bodies of the Honeybee. INSECTS 2020; 11:insects11010043. [PMID: 31936165 PMCID: PMC7023465 DOI: 10.3390/insects11010043] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/02/2020] [Accepted: 01/03/2020] [Indexed: 01/18/2023]
Abstract
Mushroom bodies (MBs) are multisensory integration centers in the insect brain involved in learning and memory formation. In the honeybee, the main sensory input region (calyx) of MBs is comparatively large and receives input from mainly olfactory and visual senses, but also from gustatory/tactile modalities. Behavioral plasticity following differential brood care, changes in sensory exposure or the formation of associative long-term memory (LTM) was shown to be associated with structural plasticity in synaptic microcircuits (microglomeruli) within olfactory and visual compartments of the MB calyx. In the same line, physiological studies have demonstrated that MB-calyx microcircuits change response properties after associative learning. The aim of this review is to provide an update and synthesis of recent research on the plasticity of microcircuits in the MB calyx of the honeybee, specifically looking at the synaptic connectivity between sensory projection neurons (PNs) and MB intrinsic neurons (Kenyon cells). We focus on the honeybee as a favorable experimental insect for studying neuronal mechanisms underlying complex social behavior, but also compare it with other insect species for certain aspects. This review concludes by highlighting open questions and promising routes for future research aimed at understanding the causal relationships between neuronal and behavioral plasticity in this charismatic social insect.
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23
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Menon KP, Kulkarni V, Takemura SY, Anaya M, Zinn K. Interactions between Dpr11 and DIP-γ control selection of amacrine neurons in Drosophila color vision circuits. eLife 2019; 8:e48935. [PMID: 31692445 PMCID: PMC6879306 DOI: 10.7554/elife.48935] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/05/2019] [Indexed: 12/17/2022] Open
Abstract
Drosophila R7 UV photoreceptors (PRs) are divided into yellow (y) and pale (p) subtypes. yR7 PRs express the Dpr11 cell surface protein and are presynaptic to Dm8 amacrine neurons (yDm8) that express Dpr11's binding partner DIP-γ, while pR7 PRs synapse onto DIP-γ-negative pDm8. Dpr11 and DIP-γ expression patterns define 'yellow' and 'pale' color vision circuits. We examined Dm8 neurons in these circuits by electron microscopic reconstruction and expansion microscopy. DIP-γ and dpr11 mutations affect the morphologies of yDm8 distal ('home column') dendrites. yDm8 neurons are generated in excess during development and compete for presynaptic yR7 PRs, and interactions between Dpr11 and DIP-γ are required for yDm8 survival. These interactions also allow yDm8 neurons to select yR7 PRs as their appropriate home column partners. yDm8 and pDm8 neurons do not normally compete for survival signals or R7 partners, but can be forced to do so by manipulation of R7 subtype fate.
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Affiliation(s)
- Kaushiki P Menon
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Vivek Kulkarni
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Shin-ya Takemura
- Janelia Research CampusHoward Hughes Medical InstituteAshburnUnited States
| | - Michael Anaya
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
| | - Kai Zinn
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaUnited States
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24
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Park H, Choi D, Park JS, Sim C, Park S, Kang S, Yim H, Lee M, Kim J, Pac J, Rhee K, Lee J, Lee Y, Lee Y, Kim S. Scalable and Isotropic Expansion of Tissues with Simply Tunable Expansion Ratio. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901673. [PMID: 31763149 PMCID: PMC6864509 DOI: 10.1002/advs.201901673] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 08/17/2019] [Indexed: 05/06/2023]
Abstract
Tissue expansion techniques physically expand swellable gel-embedded biological specimens to overcome the resolution limit of light microscopy. As the benefits of expansion come at the expense of signal concentration, imaging volume and time, and mechanical integrity of the sample, the optimal expansion ratio may widely differ depending on the experiment. However, existing expansion methods offer only fixed expansion ratios that cannot be easily adjusted to balance the gain and loss associated with expansion. Here, a hydrogel conversion-based expansion method is presented, that enables easy adjustment of the expansion ratio for individual needs, simply by changing the duration of a heating step. This method, termed ZOOM, isotropically expands samples up to eightfold in a single expansion process. ZOOM preserves biomolecules for post-processing labelings and supports multi-round expansion for the imaging of a single sample at multiple zoom factors. ZOOM can be flexibly and scalably applied to nanoscale imaging of diverse samples, ranging from cultured cells to thick tissues, as well as bacteria, exoskeletal Caenorhabditis elegans, and human brain samples.
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Affiliation(s)
- Han‐Eol Park
- Institute of Molecular Biology and GeneticsSeoul National UniversitySeoul08826South Korea
- Department of Biological SciencesSeoul National UniversitySeoul08826South Korea
| | - Dongkil Choi
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
| | - Ji Su Park
- Institute of Molecular Biology and GeneticsSeoul National UniversitySeoul08826South Korea
| | - Changgon Sim
- Institute of Molecular Biology and GeneticsSeoul National UniversitySeoul08826South Korea
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
| | - Sohyun Park
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
| | - Sunah Kang
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
| | - Hyunsoo Yim
- Institute of Molecular Biology and GeneticsSeoul National UniversitySeoul08826South Korea
- Department of Biological SciencesSeoul National UniversitySeoul08826South Korea
| | - Myungsun Lee
- Institute of Molecular Biology and GeneticsSeoul National UniversitySeoul08826South Korea
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
| | - Jaeyoun Kim
- Department of Biological SciencesSeoul National UniversitySeoul08826South Korea
| | - Jinyoung Pac
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
| | - Kunsoo Rhee
- Department of Biological SciencesSeoul National UniversitySeoul08826South Korea
| | - Junho Lee
- Institute of Molecular Biology and GeneticsSeoul National UniversitySeoul08826South Korea
- Department of Biological SciencesSeoul National UniversitySeoul08826South Korea
| | - Yunjong Lee
- Division of PharmacologyDepartment of Molecular Cell BiologySamsung Biomedical Research InstituteSungkyunkwan University School of MedicineSuwon16419South Korea
| | - Yan Lee
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
| | - Sung‐Yon Kim
- Institute of Molecular Biology and GeneticsSeoul National UniversitySeoul08826South Korea
- Department of ChemistrySeoul National UniversitySeoul08826South Korea
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25
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New observations in neuroscience using superresolution microscopy. J Neurosci 2019; 38:9459-9467. [PMID: 30381437 DOI: 10.1523/jneurosci.1678-18.2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/12/2018] [Accepted: 09/17/2018] [Indexed: 12/28/2022] Open
Abstract
Superresolution microscopy (SM) techniques are among the revolutionary methods for molecular and cellular observations in the 21st century. SM techniques overcome optical limitations, and several new observations using SM lead us to expect these techniques to have a large impact on neuroscience in the near future. Several types of SM have been developed, including structured illumination microscopy (SIM), stimulated emission depletion microscopy (STED), and photoactivated localization microscopy (PALM)/stochastic optical reconstruction microscopy (STORM), each with special features. In this Minisymposium, experts in these different types of SM discuss the new structural and functional information about specific important molecules in neuroscience that has been gained with SM. Using these techniques, we have revealed novel mechanisms of endocytosis in nerve growth, fusion pore dynamics, and described quantitative new properties of excitatory and inhibitory synapses. Additional powerful techniques, including single molecule-guided Bayesian localization SM (SIMBA) and expansion microscopy (ExM), alone or combined with super-resolution observation, are also introduced in this session.
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26
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Kulkarni A, Anderson AG, Merullo DP, Konopka G. Beyond bulk: a review of single cell transcriptomics methodologies and applications. Curr Opin Biotechnol 2019; 58:129-136. [PMID: 30978643 PMCID: PMC6710112 DOI: 10.1016/j.copbio.2019.03.001] [Citation(s) in RCA: 174] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/13/2019] [Accepted: 03/01/2019] [Indexed: 12/23/2022]
Abstract
Single-cell RNA sequencing (scRNA-seq) is a promising approach to study the transcriptomes of individual cells in the brain and the central nervous system (CNS). This technology acts as a bridge between neuroscience, computational biology, and systems biology, enabling an unbiased and novel understanding of the cellular composition of the brain and CNS. Gene expression at the single cell resolution is often noisy, sparse, and high-dimensional, creating challenges for computational analysis of such data. In this review, we overview fundamental sample preparation and data analysis processes of scRNA-seq and provide a comparative perspective for analyzing and visualizing these data.
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Affiliation(s)
| | - Ashley G Anderson
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Devin P Merullo
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Genevieve Konopka
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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27
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CHEN K, ZHANG YC, ZHAO GF. Expansion Microscopy Imaging Technique and Its Application. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2019. [DOI: 10.1016/s1872-2040(19)61156-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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28
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Zhang Q, Lee WCA, Paul DL, Ginty DD. Multiplexed peroxidase-based electron microscopy labeling enables simultaneous visualization of multiple cell types. Nat Neurosci 2019; 22:828-839. [PMID: 30886406 PMCID: PMC6555422 DOI: 10.1038/s41593-019-0358-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 02/07/2019] [Indexed: 01/06/2023]
Abstract
Electron microscopy (EM) is a powerful tool for circuit mapping, but identifying specific cell types in EM datasets remains a major challenge. Here we describe a technique enabling simultaneous visualization of multiple, genetically identified neuronal populations so that synaptic interactions between them can be unequivocally defined. We present 15 AAV constructs and six mouse reporter lines for multiplexed EM labeling in the mammalian nervous system. These reporters feature dAPEX2, which exhibits dramatically improved signal compared to previously described ascorbate peroxidases. By targeting this enhanced peroxidase to different subcellular compartments, multiple orthogonal reporters can be simultaneously visualized and distinguished under EM using a protocol compatible with existing EM pipelines. Proof-of-principle double and triple EM labeling experiments demonstrated synaptic connections between primary afferents, descending cortical inputs, and inhibitory interneurons in the spinal cord dorsal horn. Our multiplexed peroxidase-based EM labeling system should therefore greatly facilitate analysis of connectivity in the nervous system.
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Affiliation(s)
- Qiyu Zhang
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Wei-Chung A Lee
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - David L Paul
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
| | - David D Ginty
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA. .,Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
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29
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Düring DN, Rocha MD, Dittrich F, Gahr M, Hahnloser RHR. Expansion Light Sheet Microscopy Resolves Subcellular Structures in Large Portions of the Songbird Brain. Front Neuroanat 2019; 13:2. [PMID: 30766480 PMCID: PMC6365838 DOI: 10.3389/fnana.2019.00002] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 01/11/2019] [Indexed: 12/24/2022] Open
Abstract
Expansion microscopy and light sheet imaging (ExLSM) provide a viable alternative to existing tissue clearing and large volume imaging approaches. The analysis of intact volumes of brain tissue presents a distinct challenge in neuroscience. Recent advances in tissue clearing and light sheet microscopy have re-addressed this challenge and blossomed into a plethora of protocols with diverse advantages and disadvantages. While refractive index matching achieves near perfect transparency and allows for imaging at large depths, the resolution of cleared brains is usually limited to the micrometer range. Moreover, the often long and harsh tissue clearing protocols hinder preservation of native fluorescence and antigenicity. Here we image large expanded brain volumes of zebra finch brain tissue in commercially available light sheet microscopes. Our expansion light sheet microscopy (ExLSM) approach presents a viable alternative to many clearing and imaging methods because it improves on tissue processing times, fluorophore compatibility, and image resolution.
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Affiliation(s)
- Daniel Normen Düring
- Institute of Neuroinformatics, University of Zürich/ETH Zürich, Zurich, Switzerland
- Neuroscience Center Zurich (ZNZ), Zurich, Switzerland
- Department of Behavioral Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Mariana Diales Rocha
- Department of Behavioral Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Falk Dittrich
- Department of Behavioral Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Manfred Gahr
- Department of Behavioral Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Richard Hans Robert Hahnloser
- Institute of Neuroinformatics, University of Zürich/ETH Zürich, Zurich, Switzerland
- Neuroscience Center Zurich (ZNZ), Zurich, Switzerland
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30
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Xu C, Ericsson M, Perrimon N. Understanding cellular signaling and systems biology with precision: A perspective from ultrastructure and organelle studies in the Drosophila midgut. CURRENT OPINION IN SYSTEMS BIOLOGY 2018; 11:24-31. [PMID: 31595264 PMCID: PMC6781628 DOI: 10.1016/j.coisb.2018.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
One of the aims of systems biology is to model and discover properties of cells, tissues and organisms functioning as a system. In recent years, studies in the adult Drosophila gut have provided a wealth of information on the cell types and their functions, and the signaling pathways involved in the complex interactions between proliferating and differentiated cells in the context of homeostasis and pathology. Here, we document and discuss how high-resolution ultrastructure studies of organelle morphology have much to contribute to our understanding of how the gut functions as an integrated system.
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Affiliation(s)
- Chiwei Xu
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Maria Ericsson
- Department of Cell Biology, Electron Microscopy Facility, Harvard Medical School, Goldenson 323, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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31
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Volpe A, Kurtys E, Fruhwirth GO. Cousins at work: How combining medical with optical imaging enhances in vivo cell tracking. Int J Biochem Cell Biol 2018; 102:40-50. [PMID: 29960079 PMCID: PMC6593261 DOI: 10.1016/j.biocel.2018.06.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/25/2018] [Accepted: 06/26/2018] [Indexed: 12/11/2022]
Abstract
Microscopy and medical imaging are related in their exploitation of electromagnetic waves, but were developed to satisfy differing needs, namely to observe small objects or to look inside subjects/objects, respectively. Together, these techniques can help elucidate complex biological processes and better understand health and disease. A current major challenge is to delineate mechanisms governing cell migration and tissue invasion in organismal development, the immune system and in human diseases such as cancer where the spatiotemporal tracking of small cell numbers in live animal models is extremely challenging. Multi-modal multi-scale in vivo cell tracking integrates medical and optical imaging. Fuelled by basic research in cancer biology and cell-based therapeutics, it has been enabled by technological advances providing enhanced resolution, sensitivity and multiplexing capabilities. Here, we review which imaging modalities have been successfully used for in vivo cell tracking and how this challenging task has benefitted from combining macroscopic with microscopic techniques.
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Affiliation(s)
- Alessia Volpe
- Department of Imaging Chemistry and Biology, School of Biomedical Engineering and Imaging Sciences, King's College London, SE1 7EH, London, UK
| | - Ewelina Kurtys
- Department of Imaging Chemistry and Biology, School of Biomedical Engineering and Imaging Sciences, King's College London, SE1 7EH, London, UK
| | - Gilbert O Fruhwirth
- Department of Imaging Chemistry and Biology, School of Biomedical Engineering and Imaging Sciences, King's College London, SE1 7EH, London, UK.
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32
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Janušonis S, Detering N. A stochastic approach to serotonergic fibers in mental disorders. Biochimie 2018; 161:15-22. [PMID: 30056260 DOI: 10.1016/j.biochi.2018.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 07/24/2018] [Indexed: 01/09/2023]
Abstract
Virtually all brain circuits are physically embedded in a three-dimensional matrix of fibers that release 5-hydroxytryptamine (5-HT, serotonin). The density of this matrix varies across brain regions and cortical laminae, and it is altered in some mental disorders, including Major Depressive Disorder and Autism Spectrum Disorder. We investigate how the regional structure of the serotonergic matrix depends on the stochastic behavior of individual serotonergic fibers and introduce a new framework for the quantitative analysis of this behavior. In particular, we show that a step-wise random walk, based on the von Mises-Fisher probability distribution, can provide a realistic and mathematically concise description of these fibers. We also consider other stochastic models, including the fractional Brownian motion. The proposed approach seeks to advance the current understanding of the ascending reticular activating system (ARAS) and may also support future theory-guided therapeutic approaches.
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Affiliation(s)
- Skirmantas Janušonis
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, 93106-9660, USA.
| | - Nils Detering
- Department of Statistics and Applied Probability, University of California, Santa Barbara, CA, 93106-3110, USA
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