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Zhanmu O, Zhao P, Yang Y, Yang X, Gong H, Li X. Maintenance of Fluorescence During Paraffin Embedding of Fluorescent Protein-Labeled Specimens. Front Neurosci 2019; 13:752. [PMID: 31396038 PMCID: PMC6664058 DOI: 10.3389/fnins.2019.00752] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/08/2019] [Indexed: 11/20/2022] Open
Abstract
Paraffin embedding is widely used in microscopic imaging for preparing biological specimens. However, owing to significant fluorescence quenching during the embedding process, it is not compatible with fluorescent-labeling techniques, such as transgenic and viral labeling using green fluorescent protein (GFP). Here, we investigate the quenching mechanism and optimize the embedding process to improve the preservation of fluorescence intensity. The results show that dehydration is the main reason for fluorescence quenching during paraffin embedding, caused by the full denaturation of GFP molecules in ethyl alcohol. To evaluate fluorescent and morphological preservation, we modified the embedding process using tertiary butanol (TBA) instead of ethyl alcohol. Fluorescence intensity following TBA dehydration increased 12.08-fold of that observed in the traditional method. We obtained uniform fluorescence maintenance throughout the whole mouse brain, while the continuous apical dendrites, spines, and axon terminals were shown evenly within the cortex, hippocampus, and the amygdala. Moreover, we embedded a whole rat brain labeled with AAV in the prelimbic cortex (Prl). With the axon terminals in different areas, such as the caudate putamen, thalamus, and pyramidal tract, the results showed a continuous tract of Prl neurons throughout the whole brain. This method was also suitable for tdTomota labeled samples. These findings indicate that this modified embedding method could be compatible with GFP and provides a potential turning point for applications in the fluorescent labeling of samples.
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Affiliation(s)
- Ouyang Zhanmu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, China.,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China
| | - Peilin Zhao
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, China.,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China
| | - Yang Yang
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, China.,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoquan Yang
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, China.,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China.,HUST-Suzhou Institute for Brainsmatics, Suzhou, China
| | - Hui Gong
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, China.,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China.,HUST-Suzhou Institute for Brainsmatics, Suzhou, China
| | - Xiangning Li
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, China.,MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan, China.,HUST-Suzhou Institute for Brainsmatics, Suzhou, China
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Nakagawa A, Alt KV, Lillemoe KD, Castillo CFD, Warshaw AL, Liss AS. A method for fixing and paraffin embedding tissue to retain the natural fluorescence of reporter proteins. Biotechniques 2015; 59:153-5. [PMID: 26345508 DOI: 10.2144/000114328] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 06/30/2015] [Indexed: 11/23/2022] Open
Abstract
Green fluorescent protein (GFP) and its derivatives are routinely employed as surrogate markers for gene expression and lineage tracing in genetically engineered mice. Tissues from these mice are commonly formalin fixed and paraffin embedded (FFPE) for histological studies. However, this results in inactivation of the natural fluorescence of these proteins, requiring their detection by immunological techniques. Here we present an ethanol fixation protocol that allows for the direct visualization of the natural fluorescence of reporter proteins while maintaining excellent tissue histology. We demonstrate the utility of this method for visualizing green and red fluorescent proteins in a wide range of murine tissues using both cytoplasmic and membrane-localized fluorescent reporter proteins. Tissues fixed by this method also allow for immunohistochemical studies, providing a single method to visualize the natural fluorescence of reporter proteins with subsequent detection of cellular proteins.
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Affiliation(s)
- Akifumi Nakagawa
- Department of Surgery and the Andrew L Warshaw, MD, Institute for Pancreatic Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Kate Von Alt
- Department of Surgery and the Andrew L Warshaw, MD, Institute for Pancreatic Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Keith D Lillemoe
- Department of Surgery and the Andrew L Warshaw, MD, Institute for Pancreatic Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Carlos Fernández-Del Castillo
- Department of Surgery and the Andrew L Warshaw, MD, Institute for Pancreatic Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Andrew L Warshaw
- Department of Surgery and the Andrew L Warshaw, MD, Institute for Pancreatic Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA
| | - Andrew S Liss
- Department of Surgery and the Andrew L Warshaw, MD, Institute for Pancreatic Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA
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Al-Ebraheem A, Dao E, Desouza E, Li C, Wainman BC, McNeill FE, Farquharson MJ. Effect of sample preparation techniques on the concentrations and distributions of elements in biological tissues using µSRXRF: a comparative study. Physiol Meas 2015; 36:N51-60. [DOI: 10.1088/0967-3334/36/3/n51] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Cinar O, Semiz O, Can A. A microscopic survey on the efficiency of well-known routine chemical fixatives on cryosections. Acta Histochem 2006; 108:487-96. [PMID: 16950501 DOI: 10.1016/j.acthis.2006.05.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2006] [Revised: 05/27/2006] [Accepted: 05/29/2006] [Indexed: 11/21/2022]
Abstract
This study was designed to analyze and compare tissue preservation efficiency of acetone (AC), formaldehyde (FA) and paraformaldehyde (PFA) on cryosections. Brain, kidney, heart and liver tissue of adult Balb/c mice were fixed with either FA or PFA prior to cryosectioning, or fixed with AC alone immediately after cryosectioning. Hematoxylin and eosin staining showed that AC is a poor fixative in preserving the general tissue and cellular organization. PFA, and to a lesser extent FA, produced significantly better results. Another set of cryosections were further analyzed to test the properties of those fixatives to preserve proteins from specific cell structures. Cytokeratin filaments, F-actin filaments and nuclei were immunolabeled and examined using confocal microscopy. Results demonstrated that, overall, PFA is the best fixative tested. However, FA fixation gave poor results in preserving neuronal tissues. Immunofluorescence confirmed the inefficiency of AC fixation, after which no specific labelling of cytokeratin filaments was detectable. Nevertheless, actin filaments were detectable on AC-fixed samples, a finding that was supported by the quantification of fluorescein-phalloidin binding to F-actin. Overall, the data suggest that AC fixation is unacceptable for preservation of most samples, whereas FA and PFA fixation should be chosen according to the tissues and proteins to be studied.
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Affiliation(s)
- Ozgur Cinar
- Department of Histology and Embryology, Ankara University School of Medicine, Sihhiye, 06100 Ankara, Turkey.
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Gill SK, Ishak M, Rylett RJ. Exposure of nuclear antigens in formalin-fixed, paraffin-embedded necropsy human spinal cord tissue: Detection of NeuN. J Neurosci Methods 2005; 148:26-35. [PMID: 16176837 DOI: 10.1016/j.jneumeth.2005.03.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Revised: 03/29/2005] [Accepted: 03/30/2005] [Indexed: 11/25/2022]
Abstract
Immunohistochemical and immunofluorescence staining approaches are powerful tools for characterization of the endogenous protein expression and subcellular compartmentalization. However, several technical problems hamper identification of low-abundance nuclear proteins in archival formalin-fixed, paraffin-embedded human neural tissue. These include loss of protein antigenicity during tissue fixation and processing, and intrinsic auto-fluorescence associated with the tissue related to its fixation and the presence of lipofuscin. We evaluated several antigen retrieval methods to establish a strategy for detection of neuronal nuclear proteins in human spinal cord formalin-fixed, paraffin-embedded tissue. Thus, using immunostaining of the neuron-specific nuclear protein NeuN as the outcome measure, we found that heating tissue sections in an alkaline pH buffer unmasked protein epitopes most effectively. Moreover, staining by immunohistochemistry with diaminobenzidine tetrahydrochloride chromagen was superior to immunofluorescence labeling, likely due to the signal amplification steps included in the former approach. Auto-fluorescence in the tissue sections can be effectively reduced, but a sufficient fluorescence signal associated with specific antibody labeling could not be detected above this background for NeuN in the nucleus.
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Affiliation(s)
- Sandeep K Gill
- Department of Physiology and Pharmacology, Medical Sciences Building, University of Western Ontario, London, Ont., Canada N6A 5C1.
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Kondo K, Miyoshi T, Hino N, Shimizu E, Masuda N, Takada M, Uyama T, Monden Y. High frequency expressions of CD44 standard and variant forms in non-small cell lung cancers, but not in small cell lung cancers. J Surg Oncol 1998; 69:128-36. [PMID: 9846498 DOI: 10.1002/(sici)1096-9098(199811)69:3<128::aid-jso3>3.0.co;2-m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND AND OBJECTIVES Organ specificity has been demonstrated in the mode of CD44 expression among several cancers. METHODS We examined the expressions of CD44 standard (CD44s) and CD44 variants (CD44v) in 14 cell lines (small cell lung cancer (SCLC): 5, non-small cell lung cancer (NSCLC): 9 and 20 surgically resected samples (SCLC: 7, NSCLC: 13) of lung cancer using reverse transcription polymerase chain reaction and immunohistochemistry. RESULTS Although both NSCLC and SCLC expressed CD44s, the frequency and intensity of CD44s expression in NSCLC were different from those in SCLC: cell lines, 89% vs. 40%; tumor samples, 100% (diffusely stained) vs. 57% (focally stained). CD44s expression was partially or completely repressed in SCLC. However, NSCLC frequently expressed CD44v, but SCLC expressed infrequently: cell lines, 67% vs. 20%; tumor samples, 69% vs. 0%. The N-417 line, which only expressed some CD44v in SCLC, falls SCLC and NSCLC both in biomarkers and in growth patterns. CONCLUSIONS CD44 expression was repressed in SCLC but was enhanced in NSCLC.
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Affiliation(s)
- K Kondo
- Second Department of Surgery, School of Medicine, University of Tokushima, Tokushima City, Japan.
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