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Milne G, Walker LA. High-Pressure Freezing and Transmission Electron Microscopy to Visualize the Ultrastructure of the C. auris Cell Wall. Methods Mol Biol 2022; 2517:189-201. [PMID: 35674955 DOI: 10.1007/978-1-0716-2417-3_15] [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] [Indexed: 06/15/2023]
Abstract
Transmission electron microscopy (TEM) is the main technique used to study the ultrastructure of biological samples. Chemical fixation was considered the main method for preserving samples for TEM; however, it is a relatively slow method of fixation and can result in morphological alterations. Cryofixation using high-pressure freezing (HPF) overcomes the limitations of chemical fixation by preserving samples instantly. Here, we describe our HPF methods optimized for visualizing Candida auris at the ultrastructural level.
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Affiliation(s)
- Gillian Milne
- Institute of Medical Sciences (IMS), School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Louise A Walker
- Institute of Medical Sciences (IMS), School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK.
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2
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Akhtar S, Khan FA, Buhaimed A. Functionalized magnetic nanoparticles attenuate cancer cells proliferation: Transmission electron microscopy analysis. Microsc Res Tech 2019; 82:983-992. [PMID: 30809861 DOI: 10.1002/jemt.23245] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 02/07/2019] [Accepted: 02/10/2019] [Indexed: 12/18/2022]
Abstract
The penetration and transportation of nanoparticles (NPs) inside the cancer cells is critical to study. In this article, cancer cells (HCT-116) were treated with functionalized magnetic NPs for the period of 48 hr and studied their ultrastructure by transmission electron microscopy (TEM). The NPs-treated cells were prepared by chemical fixation and sliced into electron-transparent arbitrary sections (200 × 200 μm2 ) by ultramicrotome. Major events of NPs-cell interaction, such as penetration of NPs, encapsulation of NPs into the intracellular compartments, transportation of NPs, and NPs exit, were examined by TEM to understand the mechanism of cell death. The NPs showed the uniform spherical shape with broad size distribution (100-400 nm), while cells displayed irregular morphology with average diameter ~5 μm. Our results showed the successful penetration of NPs deep into the cell, encapsulation, transportation, and exocytosis. Furthermore, we tested the different concentrations (0, 1.5, 12.5, and 50 μg/ml) of NPs on cancer cells and evaluated the cell viability. Laser confocal microscopy and colorimetric analysis together demonstrated that the cell viability is a dose-dependent phenomenon, where 50 μg/ml specimen showed the highest killing of cancer cells compared to other dosages.
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Affiliation(s)
- Sultan Akhtar
- Department of Biophysics, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Firdos Alam Khan
- Department of Stem Cell Biology, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
| | - Abdullah Buhaimed
- Department of Stem Cell Biology, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia
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He X, Guo F, Liu B. Oolong tea and LR-White resin: a new method of plant sample preparation for transmission electron microscopy. J Microsc 2018; 270:244-251. [PMID: 29334400 DOI: 10.1111/jmi.12678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/22/2017] [Accepted: 12/17/2017] [Indexed: 11/27/2022]
Abstract
Simplifying sample processing, shortening the sample preparation time, and adjusting procedures to suitable for new health and safety regulations, these issues are the current challenges which electron microscopic examinations need to face. In order to resolve these problems, new plant tissue sample processing protocols for transmission electron microscopy should be developed. In the present study, we chose the LR-White resin-assisted processing protocol for the ultrastructural observation of different types of plant tissues. Moreover, we explored Oolong tea extract (OTE) as a substitute for UA in staining ultrathin sections of plant samples. The results revealed that there was no significant difference between the OTE double staining method and the traditional double staining method. Furthermore, in some organelles, such as mitochondria in root cells of tomatoes and chloroplast in leaf cells of watermelons, the OTE double staining method achieved little better results than the traditional double staining method. Therefore, OTE demonstrated good potentials in replacing UA as a counterstain on ultrathin sections. In addition, sample preparation time was significantly shortened and simplified using LR-White resin. This novel protocol reduced the time for preparing plant samples, and hazardous reagents in traditional method (acetone and UA) were also replaced by less toxic ones (ethanol and OTE).
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Affiliation(s)
- Xiaohua He
- Key Laboratory of Plant Protection Resources and Pest Management of the Ministry of Education, Entomological Museum, Northwest A&F University, Yangling, Shaanxi, China
| | - Fuzhen Guo
- Key Laboratory of Plant Protection Resources and Pest Management of the Ministry of Education, Entomological Museum, Northwest A&F University, Yangling, Shaanxi, China
| | - Bin Liu
- College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi, China
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Abstract
Low-temperature electron microscopy endeavors to provide "solidification of a biological specimen by cooling with the aim of minimal displacement of its components through the use of low temperature as a physical fixation strategy" (Steinbrecht and Zierold, Cryotechniques in biological electron microscopy. Springer-Verlag, Berlin, p 293, 1987). The intention is to maintain confidence that the tissue observed retains the morphology and dimensions of the living material while also ensuring soluble cellular components are not displaced. As applied to both scanning and transmission electron microscopy, cryo-electron microscopy is a strategy whereby the application of low-temperature techniques are used to reduce or remove processing artifacts which are commonly encountered in more conventional room temperature electron microscopy techniques which rely heavily on chemical fixation and heavy metal staining. Often, cryo-electron microscopy allows direct observation of specimens, which have not been stained or chemically fixed.
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Affiliation(s)
- Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, New Hunts House, Guy's Campus, London, SE1 1UL, UK,
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McDonald KL. Out with the old and in with the new: rapid specimen preparation procedures for electron microscopy of sectioned biological material. PROTOPLASMA 2014; 251:429-448. [PMID: 24258967 DOI: 10.1007/s00709-013-0575-y] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 06/02/2023]
Abstract
This article presents the best current practices for preparation of biological samples for examination as thin sections in an electron microscope. The historical development of fixation, dehydration, and embedding procedures for biological materials are reviewed for both conventional and low temperature methods. Conventional procedures for processing cells and tissues are usually done over days and often produce distortions, extractions, and other artifacts that are not acceptable for today's structural biology standards. High-pressure freezing and freeze substitution can minimize some of these artifacts. New methods that reduce the times for freeze substitution and resin embedding to a few hours are discussed as well as a new rapid room temperature method for preparing cells for on-section immunolabeling without the use of aldehyde fixatives.
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Affiliation(s)
- Kent L McDonald
- Electron Microscope Laboratory, University of California, 26 Giannini Hall, Berkeley, CA, 94720, USA,
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McDonald KL. Rapid embedding methods into epoxy and LR White resins for morphological and immunological analysis of cryofixed biological specimens. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:152-163. [PMID: 24252586 DOI: 10.1017/s1431927613013846] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A variety of specimens including bacteria, ciliates, choanoflagellates (Salpingoeca rosetta), zebrafish (Danio rerio) embryos, nematode worms (Caenorhabditis elegans), and leaves of white clover (Trifolium repens) plants were high pressure frozen, freeze-substituted, infiltrated with either Epon, Epon-Araldite, or LR White resins, and polymerized. Total processing time from freezing to blocks ready to section was about 6 h. For epoxy embedding the specimens were freeze-substituted in 1% osmium tetroxide plus 0.1% uranyl acetate in acetone. For embedding in LR White the freeze-substitution medium was 0.2% uranyl acetate in acetone. Rapid infiltration was achieved by centrifugation through increasing concentrations of resin followed by polymerization at 100°C for 1.5-2 h. The preservation of ultrastructure was comparable to standard freeze substitution and resin embedding methods that take days to complete. On-section immunolabeling results for actin and tubulin molecules were positive with very low background labeling. The LR White methods offer a safer, quicker, and less-expensive alternative to Lowicryl embedding of specimens processed for on-section immunolabeling without traditional aldehyde fixatives.
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Affiliation(s)
- Kent L McDonald
- Electron Microscope Laboratory, University of California, Berkeley, CA 94720, USA
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Austin JR. High-pressure freezing and freeze substitution of Arabidopsis for electron microscopy. Methods Mol Biol 2014; 1062:473-86. [PMID: 24057382 DOI: 10.1007/978-1-62703-580-4_25] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The objectives of electron microscopy ultrastructural studies are to examine cellular architecture and relate the cell's structural machinery to dynamic functional roles. This aspiration is difficult to achieve if specimens have not been adequately preserved in a "living state"; hence specimen preparation is of the utmost importance for the success of any electron micrographic study. High-pressure freezing (HPF)/freeze substitution (FS) has long been recognized as the primer technique for the preservation of ultrastructure in biological samples. In most cases a basic HPF/freeze substitution protocol is sufficient to obtain superior ultrastructural preservation and structural contrast, which allows one to use more advanced microscopy techniques such as 3D electron tomography. However, for plant tissues, which have a thick cell wall, large water-filled vacuoles, and air spaces (all of which are detrimental to cryopreservation), these basic HPF/FS protocols often yield undesirable results. In particular, ice crystal artifacts and the staining of membrane systems are often poorly or negatively stained, which make 3D segmentation of a tomogram difficult. To overcome these problems, various aspects of the HPF/FS protocol can be altered, including the cryo-filler(s) used, freeze substitution cocktail, and the resin infiltration process. This chapter will describe these modifications for the preparation of plant tissues for routine electron microscopic studies, immunocytochemistry, and 3D tomographic electron imaging.
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Affiliation(s)
- Jotham R Austin
- Advance Electron Microscopy Facility, Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
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Porta D, López-Iglesias C. A comparison of cryo- versus chemical fixation in the soil green algae Jaagiella. Tissue Cell 2012; 30:368-76. [PMID: 18627846 DOI: 10.1016/s0040-8166(98)80050-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/1997] [Accepted: 02/10/1998] [Indexed: 11/29/2022]
Abstract
Chemical fixation protocols provided unsatisfactory preserved material for ultrastructural studies on Jaagiella alpicola Vischer (Chlorophyta). Instead, several methods of rapid freeze fixation followed by freeze substitution were applied. For fast freeze fixation, two methods were tried: plunge immersion freezing in liquid propane using a home-made device, and projection against a copper block cooled by either liquid nitrogen or liquid helium. Each method furnished well fixed material. The quality of the fixed samples was quite similar whether propane or the cryoblock cooled with liquid nitrogen was used. Liquid helium, however, provided superior results. After fixation the samples were cryosubstituted, using acetone or methanol as organic solvent with a chemical fixative added. Acetone gave better results than methanol as a substitution solvent when high temperature embedding was performed. The best cryosubstitution for ultrastructural studies was that in which osmium tetroxide or a mixture of osmium tetroxide and urany acetate was used.
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Affiliation(s)
- D Porta
- Laboratori de Botànica, Facultat de Farmàcia, Universitat de Barcelona, Joan XXIII s/n, 08028 Barcelona, Spain
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The three dimensionality of cell membranes: lamellar to cubic membrane transition as investigated by electron microscopy. Methods Cell Biol 2012; 108:319-43. [PMID: 22325609 DOI: 10.1016/b978-0-12-386487-1.00015-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/24/2023]
Abstract
Biological membranes are generally perceived as phospholipid bilayer structures that delineate in a lamellar form the cell surface and intracellular organelles. However, much more complex and highly convoluted membrane organizations are ubiquitously present in many cell types under certain types of stress, states of disease, or in the course of viral infections. Their occurrence under pathological conditions make such three-dimensionally (3D) folded and highly ordered membranes attractive biomarkers. They have also stimulated great biomedical interest in understanding the molecular basis of their formation. Currently, the analysis of such membrane arrangements, which include tubulo-reticular structures (TRS) or cubic membranes of various subtypes, is restricted to electron microscopic methods, including tomography. Preservation of membrane structures during sample preparation is the key to understand their true 3D nature. This chapter discusses methods for appropriate sample preparations to successfully examine and analyze well-preserved highly ordered membranes by electron microscopy. Processing methods and analysis conditions for green algae (Zygnema sp.) and amoeba (Chaos carolinense), mammalian cells in culture and primary tissue cells are described. We also discuss methods to identify cubic membranes by transmission electron microscopy (TEM) with the aid of a direct template matching method and by computer simulation. A 3D analysis of cubic cell membrane topology by electron tomography is described as well as scanning electron microscopy (SEM) to investigate surface contours of isolated mitochondria with cubic membrane arrangement.
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Lim JI, Park HK. Boric acid-enhanced embedding medium for cryomicrotomy. Acta Histochem 2012; 114:296-9. [PMID: 21570708 DOI: 10.1016/j.acthis.2011.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 04/11/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
Abstract
A polyvinyl alcohol (PVA)/polyethylene glycol (PEG)-based resin is commonly used as a cryoembedding medium for the histological analysis of frozen tissue sections. However, it is not easy to obtain sufficient numbers of satisfactory reproducible sections owing to the differences between the mechanical properties of the medium and embedded tissue and the low cohesive force of the medium. We describe a modified PVA-based cryoembedding medium, composed of PVA (10wt% and 15wt%) with the addition of boric acid (from 0 to 5wt%), that can improve the sectioning properties and efficiency of frozen tissue for histological analysis. The amount of load under the same compressive displacement as well as cohesive force increased with increasing boric acid and PVA contents. 15wt% PVA and 3wt% boric acid was determined as an optimal composition for cryoembedding material based on the sectioning efficiency measured by the numbers of unimpaired sectioned slices and the amount of load under the same compressive displacement test. On the basis of the results of routine hematoxylin and eosin staining of cryosections of tissue embedded in a medium with 3wt% boric acid and PVA, it was concluded that the modified PVA cryoembedding medium can improve the efficiency of cryosectioning for subsequent histological or histochemical analysis of various tissues.
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Affiliation(s)
- Jin Ik Lim
- Department of Biomedical Engineering and Healthcare Industry Research Institute, College of Medicine, Kyung Hee University, Dongdaemun-gu, Seoul, Republic of Korea
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Application of "in vivo cryotechnique" to morphological and immunohistochemical analyses of living mouse subepicardial microcirculation under various pathological conditions. Appl Immunohistochem Mol Morphol 2011; 20:304-17. [PMID: 22024992 DOI: 10.1097/pai.0b013e318225a2a0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
"In vivo cryotechnique" (IVCT), which involves immediately cryofixing cells and tissues of living animals in situ, can display more native morphology in vivo and eliminate artificial changes in conventional preparations. However, the technical characteristics of IVCT are not known for the practical examination of subepicardial microcirculation of beating heart tissue. Histological sections of subepicardial area were prepared using IVCT and conventional fixation methods: quick freezing, immersion fixation, or perfusion fixation followed by alcohol dehydration, respectively from healthy mice. In addition, changes of erythrocyte shape, T-tubule, and microvasculature in mouse heart from a variety of models (acute increase of left ventricular afterload, myocardial ischemia, and cardiac arrest) were examined by IVCT. With IVCT, flowing erythrocytes, blood flow, microvasculature, and myocyte structure could be well preserved without artificial change of erythrocyte shape and translocation of serum proteins as displayed in conventional preparation samples. Furthermore, in various pathological models prepared by IVCT, T-tubules with albumin immuno-positive staining were arranged in a disorderly way and were decreased in volume in samples of acute increase of left ventricular afterload (IVCT-LAA). This was more evident in acute regional myocardial ischemia (IVCT-IC) and less evident in heart arrest (IVCT-HA). In addition, the leakage of serum proteins from microvasculature into myocyte was found only in IVCT-IC but not in IVCT-LAA and in IVCT-HA. In conclusion, IVCT is a new technique for examining morphology of subepicardial microcirculation without artifacts compared with conventional methods and is a more sensitive fixation technique in detecting pathological changes of the heart.
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Lim JI, Lim KJ, Choi JY, Lee YK. Modified paraffin wax for improvement of histological analysis efficiency. Microsc Res Tech 2010; 73:761-5. [DOI: 10.1002/jemt.20818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Strádalová V, Gaplovská-Kyselá K, Hozák P. Ultrastructural and nuclear antigen preservation after high-pressure freezing/freeze-substitution and low-temperature LR White embedding of HeLa cells. Histochem Cell Biol 2008; 130:1047-52. [PMID: 18797913 DOI: 10.1007/s00418-008-0504-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2008] [Indexed: 12/01/2022]
Abstract
A protocol for high-pressure freezing and LR White embedding of mammalian cells suitable for fine ultrastructural studies in combination with immunogold labelling is presented. HeLa S3 cells enclosed in low-temperature gelling agarose were high-pressure frozen, freeze-substituted in acetone, and embedded in LR White at 0 degrees C. The morphology of such cells and the preservation of nuclear antigens were excellent in comparison with chemically fixed cells embedded in the same resin. The immunolabelling signal for different nuclear antigens was 4-to-13 times higher in high-pressure frozen than in chemically fixed cells. We conclude that one can successfully use high-pressure freezing/freeze-substitution and LR White embedding as an alternative of Lowicryl resins.
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Affiliation(s)
- Vendula Strádalová
- Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, v.v.i., Vídenská 1083, 142 20, Prague, Czech Republic
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Campbell AK. Jean-Marie Bassot (1933-2007): a life of unquenched curiosity. LUMINESCENCE 2008; 23:187-90. [PMID: 18452142 DOI: 10.1002/bio.1048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Anthony K Campbell
- Darwin Centre, Department of Medical Biochemistry and Immunology, Cardiff University, Tenovus Building, Heath Park, Cardiff CF14 4XN, UK.
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Ruan YL. Rapid cell expansion and cellulose synthesis regulated by plasmodesmata and sugar: insights from the single-celled cotton fibre. FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:1-10. [PMID: 32689326 DOI: 10.1071/fp06234] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Accepted: 11/21/2006] [Indexed: 05/24/2023]
Abstract
Higher plants comprise mixtures of some 40 different cell types, and this often complicates the interpretation of data obtained at the tissue level. Studies for a given cell type may provide novel insights into the mechanisms underlying defined cellular and developmental processes. In this regard, the cotton fibre represents an excellent single-cell model to study the control of rapid cell elongation and cellulose synthesis. These single cells, initiated from the ovule epidermis at anthesis, typically elongate to ~3-5 cm in the tetraploid species before they switch to intensive secondary cell wall cellulose synthesis. By maturity, more than 94% of fibre weight is cellulose. To unravel the mechanisms of fibre elongation and cellulose synthesis, two hypotheses have been examined: (a) that sucrose degradation and utilisation mediated by sucrose synthase (Sus) may play roles in fibre development and (b) that symplastic isolation of the fibre cells may be required for their rapid elongation. Reverse genetic and biochemical analyses have revealed the critical role that Sus plays in fibre initiation and early elongation. Late in development, plasma-membrane and cell wall association of Sus protein seems to be involved in rapid cellulose synthesis. Cell biology and gene expression studies showed a temporary closure of fibre plasmodesmata (PD), probably due to the deposition of callose, at the rapid phase of elongation. The duration of the PD closure correlates positively with the final fibre length attained. These data support the view that PD closure may be required for fibres to achieve extended elongation. The branching of PD towards the secondary cell wall stage is postulated to function as a molecule sieve for tight control of macromolecule trafficking into fibres to sustain intensive cellulose synthesis.
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Affiliation(s)
- Yong-Ling Ruan
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.Email
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Affiliation(s)
- Kent McDonald
- Electron Microscope Laboratory, University of California, Berkeley, California 94720, USA
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Mühlfeld C, Richter J. High-pressure freezing and freeze substitution of rat myocardium for immunogold labeling of connexin 43. ACTA ACUST UNITED AC 2006; 288:1059-67. [PMID: 16952173 DOI: 10.1002/ar.a.20380] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The value of high-pressure freezing (HPF) and freeze substitution (FS) for immunoelectron microscopy (immuno-EM) of the heart was investigated in bioptic specimens taken from isolated hearts of 0-, 5-, and 14-day-old rats at baseline and at 15, 30, 45, and 60 min after induction of ischemia. The target antigen chosen here was the gap junction protein connexin 43 (Cx43). After HPF and FS, immunogold labeling was applied for detection of Cx43. Gold particles associated with gap junction areas, free plasma membrane, and annular gap junctions (AGJs) were counted and distributions compared by contingency table analysis. HPF and FS resulted in excellent preservation of antigenicity for Cx43. The mostly good preservation of the ultrastructure was limited by mechanical damage at the border and by ice crystal formation in the center of the tissue blocks. In normal myocardium of newborns, gold particles associated with free plasma membrane were frequently observed, with AGJs only seldom. In older rats, the opposite relation was found. During ischemia, no distribution changes occurred in newborn or 14-day-old rats. In 5-day-old rats, however, ischemia induced a shift of Cx43 from gap junction plaques to AGJs. In conclusion, HPF and FS are an ideal alternative to chemical fixation for immuno-EM as the excellent preservation of antigenicity is combined with a well-preserved ultrastructure. The results indicate that the process of degradation of gap junctions via AGJs gradually increases during postnatal rat heart development, a process that may be accelerated by ischemia in an early developmental state.
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Affiliation(s)
- Christian Mühlfeld
- Division of Electron Microscopy, Department of Anatomy, University of Göttingen, Göttingen, Germany.
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Yamamoto M, Kurihara I, Kawano S. Late type of daughter cell wall synthesis in one of the Chlorellaceae, Parachlorella kessleri (Chlorophyta, Trebouxiophyceae). PLANTA 2005; 221:766-75. [PMID: 15744493 DOI: 10.1007/s00425-005-1486-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Accepted: 01/08/2005] [Indexed: 05/20/2023]
Abstract
Autosporulation is a common mode of propagation for unicellular algae. Autospore-forming species of Chlorellaceae, Chlorella vulgaris Beijerinck, C. sorokiniana Shihira et Krauss, C. lobophora Andreyeva, and Parachlorella kessleri (Fott et Nováková) Krienitz et al. have glucosamine as the main constituent of their rigid cell wall. Recent phylogenetic analyses have showed that the Chlorellaceae divided into two sister groups: the Chlorella-clade and the Parachlorella-clade. We compared the cell wall structure and synthesis of the daughter cell wall in the four species by electron microscopy using rapid freezing and freeze substitution methods. The cell wall of C. vulgaris, C. sorokiniana, and C. lobophora consisted of an electron-dense thin layer with an average thickness of 17-20, 22, and 19 nm, respectively. In these three species, daughter cell wall synthesis occurred on the outer surface of the plasma membrane in the early cell-growth phase. The cell wall of P. kessleri, however, was electron-transparent and 54-59 nm in thickness. Ruthenium red staining of P. kessleri indicated that ruthenium-red-specific polysaccharides accumulated over the outer surface of the plasma membrane. Immunoelectron microscopic observation with an anti-beta-1, 3-glucan antibody and staining with wheat germ agglutinin (WGA) indicated that the cell wall contained beta-1, 3-glucan and WGA specific N-acetyl-beta-D-glucosamine. In P. kessleri, daughter cell wall synthesis began after successive protoplast division. The daughter cell wall synthesis during autosporulation in the four species of Chlorellaceae can be classified into two types-the early and the late types.
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Affiliation(s)
- Maki Yamamoto
- School of Life Science, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
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Abstract
Freeze-substitution is a physicochemical process in which biological specimens are immobilized and stabilized for microscopy. Water frozen within cells is replaced by organic solvents at subzero temperatures. Freeze-substitution is widely used for ultrastructural and immunocytochemical analyses of cells by transmission and scanning electron microscopy. Less well recognized is its superiority over conventional chemical fixation in preserving labile and rare tissue antigens for immunocytochemistry by light microscopy. In the postgenome era, the focus of molecular genetics will shift from analyzing DNA sequence structure to elucidating the function of gene networks, the intercellular effects of polygenetic diseases, and the conformational rearrangements of proteins in situ. Novel strategies will be needed to integrate knowledge of chemical structures of normal and abnormal macromolecules with the physiology and developmental biology of cells and tissues from whole organisms. This review summarizes the progress and future prospects of freeze-substitution for such explorations.
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Affiliation(s)
- R Shiurba
- Misato Inc., Satte-shi, Saitama, Japan
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Haigler CH, Ivanova-Datcheva M, Hogan PS, Salnikov VV, Hwang S, Martin K, Delmer DP. Carbon partitioning to cellulose synthesis. PLANT MOLECULAR BIOLOGY 2001. [PMID: 11554477 DOI: 10.1007/978-94-010-0668-2_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
This article discusses the importance and implications of regulating carbon partitioning to cellulose synthesis, the characteristics of cells that serve as major sinks for cellulose deposition, and enzymes that participate in the conversion of supplied carbon to cellulose. Cotton fibers, which deposit almost pure cellulose into their secondary cell walls, are referred to as a primary model system. For sucrose synthase, we discuss its proposed role in channeling UDP-Glc to cellulose synthase during secondary wall deposition, its gene family, its manipulation in transgenic plants, and mechanisms that may regulate its association with sites of polysaccharide synthesis. For cellulose synthase, we discuss the organization of the gene family and how protein diversity could relate to control of carbon partitioning to cellulose synthesis. Other enzymes emphasized include UDP-Glc pyrophosphorylase and sucrose phosphate synthase. New data are included on phosphorylation of cotton fiber sucrose synthase, possible regulation by Ca2+ of sucrose synthase localization, electron microscopic immunolocalization of sucrose synthase in cotton fibers, and phylogenetic relationships between cellulose synthase proteins, including three new ones identified in differentiating tracheary elements of Zinnia elegans. We develop a model for metabolism related to cellulose synthesis that implicates the changing intracellular localization of sucrose synthase as a molecular switch between survival metabolism and growth and/or differentiation processes involving cellulose synthesis.
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Affiliation(s)
- C H Haigler
- Department of Biological Sciences, Texas Tech University, Lubbock 79409-3131, USA.
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Salnikov VV, Grimson MJ, Delmer DP, Haigler CH. Sucrose synthase localizes to cellulose synthesis sites in tracheary elements. PHYTOCHEMISTRY 2001; 57:823-33. [PMID: 11423134 DOI: 10.1016/s0031-9422(01)00045-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The synthesis of crystalline cellulose microfibrils in plants is a highly coordinated process that occurs at the interface of the cortex, plasma membrane, and cell wall. There is evidence that cellulose biogenesis is facilitated by the interaction of several proteins, but the details are just beginning to be understood. In particular, sucrose synthase, microtubules, and actin have been proposed to possibly associate with cellulose synthases (microfibril terminal complexes) in the plasma membrane. Differentiating tracheary elements of Zinnia elegans L. were used as a model system to determine the localization of sucrose synthase and actin in relation to the plasma membrane and its underlying microtubules during the deposition of patterned, cellulose-rich secondary walls. Cortical actin occurs with similar density both between and under secondary wall thickenings. In contrast, sucrose synthase is highly enriched near the plasma membrane and the microtubules under the secondary wall thickenings. Both actin and sucrose synthase lie closer to the plasma membrane than the microtubules. These results show that the preferential localization of sucrose synthase at sites of high-rate cellulose synthesis can be generalized beyond cotton fibers, and they establish a spatial context for further work on a multi-protein complex that may facilitate secondary wall cellulose synthesis.
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Affiliation(s)
- V V Salnikov
- Department of Biological Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409, USA
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24
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Young RD, Lawrence PA, Duance VC, Aigner T, Monaghan P. Immunolocalization of collagen types II and III in single fibrils of human articular cartilage. J Histochem Cytochem 2000; 48:423-32. [PMID: 10681396 DOI: 10.1177/002215540004800312] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Type II and III fibrillar collagens were localized by immunogold electron microscopy in resin sections of human femoral articular cartilage taken from the upper radial zone in specimens from patients with osteoarthritis. Tissue samples stabilized by high-pressure cryofixation were processed by freeze-substitution, either in acetone containing osmium or in methanol without chemical fixatives, before embedding in epoxy or Lowicryl resin, respectively. Ultrastructural preservation was superior with osmium-acetone, although it was not possible to localize collagens by this method. In contrast, in tissue prepared by low-temperature methods without chemical fixation, collagens were successfully localized with mono- or polyclonal antibodies to the helical (Types II and III) and amino-propeptide (Type III procollagen) domains of the molecule. Dual localization using secondary antibodies labeled with 5- or 10-nm gold particles demonstrated the presence of Types II and III collagen associated within single periodic banded fibrils. Collagen fibrils in articular cartilage are understood to be heteropolymers mainly of Types II, IX, and XI collagen. Our observations provide further evidence for the complexity of these assemblies, with the potential for interactions between at least 11 distinct collagen types as well as several noncollagenous components of the extracellular matrix.
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Affiliation(s)
- R D Young
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
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25
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Bourett TM, Czymmek KJ, Howard RJ. An improved method for affinity probe localization in whole cells of filamentous fungi. Fungal Genet Biol 1998; 24:3-13. [PMID: 9742188 DOI: 10.1006/fgbi.1998.1054] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The fungal cell wall, though phylogenetically variable, acts universally as a potent barrier to probing intracellular structures. Thus, the use of high-molecular-weight probes such as antibodies and lectins has proven a formidable challenge. We have devised a preparative method for use with various affinity probes that can be applied to a broad spectrum of filamentous fungal species and used for imaging whole cells. In this study, confocal imaging of whole-mount fungal hyphae after freeze substitution, methacrylate embedment/de-embedment, and infiltration with affinity probes has yielded remarkably improved renderings of the three-dimensional distribution of both microtubules (using antibodies against both alpha- and beta-tubulin) and concanavalin A binding sites. Using this protocol we have been able to document: (1) the three-dimensional distribution of microtubules in all regions of hyphae, (2) the presence of apparent foci for cytoplasmic microtubules, (3) persistent cytoplasmic microtubules during mitosis, and (4) a three-dimensional view of many compartments of the endomembrane system including Golgi-equivalent organelles and apical vesicles. The last result represents the first direct confirmation of apical vesicles comprising the Spitzenkörper.
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Affiliation(s)
- T M Bourett
- DuPont Agricultural Products, Wilmington, Delaware, 19880-0402, USA
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26
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Dictenberg JB, Zimmerman W, Sparks CA, Young A, Vidair C, Zheng Y, Carrington W, Fay FS, Doxsey SJ. Pericentrin and gamma-tubulin form a protein complex and are organized into a novel lattice at the centrosome. J Cell Biol 1998; 141:163-74. [PMID: 9531556 PMCID: PMC2132723 DOI: 10.1083/jcb.141.1.163] [Citation(s) in RCA: 388] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/1997] [Revised: 01/19/1998] [Indexed: 02/07/2023] Open
Abstract
Pericentrin and gamma-tubulin are integral centrosome proteins that play a role in microtubule nucleation and organization. In this study, we examined the relationship between these proteins in the cytoplasm and at the centrosome. In extracts prepared from Xenopus eggs, the proteins were part of a large complex as demonstrated by sucrose gradient sedimentation, gel filtration and coimmunoprecipitation analysis. The pericentrin-gamma-tubulin complex was distinct from the previously described gamma-tubulin ring complex (gamma-TuRC) as purified gamma-TuRC fractions did not contain detectable pericentrin. When assembled at the centrosome, the two proteins remained in close proximity as shown by fluorescence resonance energy transfer. The three- dimensional organization of the centrosome-associated fraction of these proteins was determined using an improved immunofluorescence method. This analysis revealed a novel reticular lattice that was conserved from mammals to amphibians, and was organized independent of centrioles. The lattice changed dramatically during the cell cycle, enlarging from G1 until mitosis, then rapidly disassembling as cells exited mitosis. In cells colabeled to detect centrosomes and nucleated microtubules, lattice elements appeared to contact the minus ends of nucleated microtubules. Our results indicate that pericentrin and gamma-tubulin assemble into a unique centrosome lattice that represents the higher-order organization of microtubule nucleating sites at the centrosome.
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Affiliation(s)
- J B Dictenberg
- Program in Molecular Medicine and Department of Cell Biology, University of Massachusetts Medical Center, Worcester, Massachusetts 01655, USA
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27
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Wild P, Gabrieli A, Schraner EM, Pellegrini A, Thomas U, Frederik PM, Stuart MC, Von Fellenberg R. Reevaluation of the effect of lysoyzme on Escherichia coli employing ultrarapid freezing followed by cryoelectronmicroscopy or freeze substitution. Microsc Res Tech 1997; 39:297-304. [PMID: 9372501 DOI: 10.1002/(sici)1097-0029(19971101)39:3<297::aid-jemt8>3.0.co;2-h] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Lysozyme is able to lyse Gram-positive bacteria acting as muramidase on the peptidoglycan polymer. Gram-negative bacteria in vitro are not lysed by lysozyme. It was assumed that the peptido-glycan is protected by the outer membrane and thus that Gram-negative bacteria are not affected by lysozyme without the aid of other factors such as EDTA or complement which enable lysozyme to penetrate the outer membrane. Accidentally, Pellegrini et al. [(1992) J. Appl. Bacteriol., 72:180-187] found that lysozyme per se is able to kill some Gram-negative bacteria. On the basis of morphological and immunocytochemical findings obtained from chemically fixed bacteria, it was concluded that lysozyme does not lyse Gram-negative bacteria but affects the cytoplasm of for example, Escherichia coli, leading to its disintegration, whilst the membranes do not break down. In an attempt to clarify the action of lysozyme on E. coli, we employed cryotechniques including ultrarapid freezing, cryomicroscopy and freeze substitution, and immunolabeling. Bacteria that were immediately frozen after exposure to lysozyme remained morphologically intact. Individual bacteria plated on agar after exposure to lysozyme were mostly intact when frozen within a few seconds. However, inner and outer membranes of 80% of the bacteria were disrupted, whereas the cytoplasm of only a few bacteria showed signs of disintegration when bacteria were frozen with a delay of only 5 min of plating onto pure agar or agar containing growth medium. After a period of time of 15 min between plating onto agar and freezing, about 97% of the bacteria showed changes of disintegration of various extent. Immunolabeling showed that lysozyme binds to the outer cell membrane and may penetrate the membrane, reaching the periplasmic space and possibly the inner cell membrane. The ultrastructural findings and the results of antibacterial assays suggest that lysozyme is bactericidal for E. coli but is not able to induce disintegration. Disintegration is accomplished by changes of the environment starting at the cell membranes. The mechanism by which lysozyme penetrates the membrane, the way it acts to be bactericidal, and the way disintegration is initiated remain to be clarified.
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Affiliation(s)
- P Wild
- Institute of Veterinary Anatomy, University of Zürich, Switzerland.
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28
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Menco BP. Freeze-fracture, deep-etch, and freeze-substitution studies of olfactory epithelia, with special emphasis on immunocytochemical variables. Microsc Res Tech 1995; 32:337-56. [PMID: 8573783 DOI: 10.1002/jemt.1070320408] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Freeze-fracturing and deep-etching are a well-suited set of methods to study membrane and cytoplasmic features. Various approaches are available. Possible variables include tissue preparation, fracturing only or fracturing followed by etching, modes and materials of replication, and various ways of combining freeze-fracturing and/or deep-etching with (immuno)cytochemistry. Freeze-substitution, in particular combined with embedding in methacrylate resins such as the Lowicryls, is becoming rather widely accepted for purposes of ultrastructural (immuno)cytochemistry. Most investigators active in this field agree that this combination yields superior results compared to (immuno)cytochemistry combined with more conventional means of thin section transmission electron microscopy. Yet relatively little information is available on the variations that can occur with different approaches of freeze-substitution immunocytochemistry. This review deals with some of the variations in freeze-fracturing, freeze-etching, and freeze-substitution as applied to olfactory epithelial structures and with the effectiveness of observations obtained by application of the above sets of methods in relating the special morphology of olfactory epithelial cellular structures with those obtained by other approaches. Indeed, the data obtained continue to provide an integral image in which that morphology can be related to the special biochemistry, cell and molecular biology, and electrophysiology of olfactory epithelial structures.
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Affiliation(s)
- B P Menco
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208-3520, USA
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29
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Bassot JM, Nicolas MT. Bioluminescence in scale-worm photosomes: the photoprotein polynoidin is specific for the detection of superoxide radicals. Histochem Cell Biol 1995; 104:199-210. [PMID: 8542446 DOI: 10.1007/bf01835153] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Photosomes are the characteristic organelles of the luminous epithelium in the elytral appendages of polynoïd annelids. They are paracrystals of endoplasmic reticulum and emit a flash of bioluminescence in response to stimulation. The series of flashes in response to repetitive stimulation begins with a period of facilitation because the number of reacting photosomes increases in each photogenic cell. Reacting photosomes are coupled to the plasma membrane by dyad junctions which are established under stimulation and dedifferentiate in the resting system. The calcium influx of an action potential propagated through the conducting elytral epithelium triggers the luminous reaction. This reaction is based on a membrane photoprotein, polynoidin, which is specifically triggered by superoxide radicals. These oxy radicals result from the oxydation of riboflavin, which is present in a compartment of the photosomes. Polynoidin proved to be an interesting probe in the detection of superoxide radicals produced by activated white blood cells. Its potential applications are discussed.
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30
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Inoue S, Bendayan M. High-resolution ultrastructural study of the rat glomerular basement membrane in long-term experimental diabetes. Ultrastruct Pathol 1995; 19:175-85. [PMID: 7631432 DOI: 10.3109/01913129509064219] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The ultrastructure of the glomerular basement membrane of the long-term diabetic and age-matched control rats was studied with the application of advanced high-resolution microscopy. By using the freeze substitution method for the preparation of the renal tissue, it was possible to observe that the glomerular basement membrane in control and diabetic animals is composed on only a single lamina densa without the presence of a lamina lucida interna or externa. High-resolution electron microscopy of the diabetic glomerular basement membrane showed significant alterations in its morphology and ultrastructure. First, the basement membrane in diabetic condition appeared to be split into two halves, endothelial and epithelial. In the epithelial half of the membrane, the network of distinct strands referred to as cords, which were clearly present in the glomerular basement membrane of age-matched control animals, became less distinct and showed a diffused appearance being evenly replaced by thin filaments. The openings of the network were filled with a granular material. In the endothelial half of the membrane, on the other hand, the cord network was variably lost in diabetic condition and, within the resulting vacant spaces, bundles of fibrils 12 nm in width, identified as basotubules, were deposited. Immunolabeling for type IV collagen was found to be enriched in the endothelial half of the basement membrane being associated with the bundles of basotubules. The ultrastructural changes reported by high-resolution microscopy could be related to the molecular alterations of the basement membrane components and to the loss in permselectivity occurring during diabetes.
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Affiliation(s)
- S Inoue
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
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31
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Gowen BE, Buendia B, Karsenti E, Fuller SD. Postembedding α-tubulin immunolabelling of isolated centrosomes. ACTA ACUST UNITED AC 1995. [DOI: 10.1007/bf02389891] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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32
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Bendayan M. Colloidal gold post-embedding immunocytochemistry. PROGRESS IN HISTOCHEMISTRY AND CYTOCHEMISTRY 1995; 29:1-159. [PMID: 7480783 DOI: 10.1016/s0079-6336(11)80027-6] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- M Bendayan
- Department of Anatomy, University of Montreal, Canada
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33
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Nanci A, Kawaguchi H, Kogaya Y. Ultrastructural studies and immunolocalization of enamel proteins in rodent secretory stage ameloblasts processed by various cryofixation methods. Anat Rec (Hoboken) 1994; 238:425-36. [PMID: 8192240 DOI: 10.1002/ar.1092380402] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND Cryofixation rapidly immobilizes cell and tissue components in their native state, thereby resulting in an ultrastructural preservation very close to the living situation. We have applied this approach to examine the morphology of secretory stage ameloblasts and the distribution of enamel proteins in these cells. METHODS Molar and incisor tooth germs from newborn mice and/or rats were quickly dissected and divided into segments. The segments were then rapidly frozen using slam, plunge or pressure freezing, freeze-substituted and embedded in Epon. In addition, incisors from older rats were chemically fixed by vascular perfusion and also dehydrated by freeze-substitution. RESULTS Well-preserved ameloblasts were obtained with all four tissue processing methods. However, slam freezing often showed mechanical damage to the ameloblasts, particularly at the level of the distal portion of Tomes' processes which appeared severed or distorted. Plunging into liquid nitrogen-cooled liquid propane resulted in comparatively less tissue distortion. High pressure freezing gave a relatively higher yield of well-preserved specimens, although displacement of organelles in ameloblasts was sometimes observed, probably resulting from hydrostatic pressure. Minimal ice crystal and mechanical damage was observed in chemically fixed tooth samples processed by freeze-substitution since such specimens are cryoprotected and their examination is not restricted to a surface layer. With all of the above cryopreparation methods, the ultrastructure of well-preserved ameloblasts was, in general, similar to that obtained following conventional chemical fixation, and immunocytochemistry with an anti-amelogenin antibody indicated no profound differences in the distribution of enamel proteins. CONCLUSIONS These results indicate that, despite some limitations, it is possible to adequately cryofix tooth organs while preserving the architecture of ameloblasts and permitting immunolocalization of enamel proteins. Furthermore, they confirm the general morphology of secretory stage ameloblasts as currently derived from conventional chemical tissue processing.
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Affiliation(s)
- A Nanci
- Department of Anatomy, Université de Montréal, QC, Canada
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