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Benchimol M, Gadelha AP, de Souza W. Unusual Cell Structures and Organelles in Giardia intestinalis and Trichomonas vaginalis Are Potential Drug Targets. Microorganisms 2022; 10:2176. [PMID: 36363768 PMCID: PMC9698047 DOI: 10.3390/microorganisms10112176] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 10/28/2022] [Accepted: 10/31/2022] [Indexed: 09/29/2023] Open
Abstract
This review presents the main cell organelles and structures of two important protist parasites, Giardia intestinalis, and Trichomonas vaginalis; many are unusual and are not found in other eukaryotic cells, thus could be good candidates for new drug targets aimed at improvement of the chemotherapy of diseases caused by these eukaryotic protists. For example, in Giardia, the ventral disc is a specific structure to this parasite and is fundamental for the adhesion and pathogenicity to the host. In Trichomonas, the hydrogenosome, a double membrane-bounded organelle that produces ATP, also can be a good target. Other structures include mitosomes, ribosomes, and proteasomes. Metronidazole is the most frequent compound used to kill many anaerobic organisms, including Giardia and Trichomonas. It enters the cell by passive diffusion and needs to find a highly reductive environment to be reduced to the nitro radicals to be active. However, it provokes several side effects, and some strains present metronidazole resistance. Therefore, to improve the quality of the chemotherapy against parasitic protozoa is important to invest in the development of highly specific compounds that interfere with key steps of essential metabolic pathways or in the functional macromolecular complexes which are most often associated with cell structures and organelles.
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Affiliation(s)
- Marlene Benchimol
- Laboratorio de Ultraestrutura Celular Hertha Meyer, Centro de Ciêcias da Saúde, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitaria, Rio de Janeiro 96200-000, Brazil
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
- Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens e Centro Nacional de Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Ana Paula Gadelha
- Diretoria de Metrologia Aplicada as Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMETRO), Rio de Janeiro 25250-020, Brazil
| | - Wanderley de Souza
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
- Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens e Centro Nacional de Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
- CMABio, Escola Superior de Saúde, Universidade do Estado do Amazonas-UEA, Manaus 69850-000, Brazil
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2
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Santos R, Ástvaldsson Á, Pipaliya SV, Zumthor JP, Dacks JB, Svärd S, Hehl AB, Faso C. Combined nanometric and phylogenetic analysis of unique endocytic compartments in Giardia lamblia sheds light on the evolution of endocytosis in Metamonada. BMC Biol 2022; 20:206. [PMID: 36127707 PMCID: PMC9490929 DOI: 10.1186/s12915-022-01402-3] [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] [Received: 05/06/2022] [Accepted: 09/06/2022] [Indexed: 11/27/2022] Open
Abstract
Background Giardia lamblia, a parasitic protist of the Metamonada supergroup, has evolved one of the most diverged endocytic compartment systems investigated so far. Peripheral endocytic compartments, currently known as peripheral vesicles or vacuoles (PVs), perform bulk uptake of fluid phase material which is then digested and sorted either to the cell cytosol or back to the extracellular space. Results Here, we present a quantitative morphological characterization of these organelles using volumetric electron microscopy and super-resolution microscopy (SRM). We defined a morphological classification for the heterogenous population of PVs and performed a comparative analysis of PVs and endosome-like organelles in representatives of phylogenetically related taxa, Spironucleus spp. and Tritrichomonas foetus. To investigate the as-yet insufficiently understood connection between PVs and clathrin assemblies in G. lamblia, we further performed an in-depth search for two key elements of the endocytic machinery, clathrin heavy chain (CHC) and clathrin light chain (CLC), across different lineages in Metamonada. Our data point to the loss of a bona fide CLC in the last Fornicata common ancestor (LFCA) with the emergence of a protein analogous to CLC (GlACLC) in the Giardia genus. Finally, the location of clathrin in the various compartments was quantified. Conclusions Taken together, this provides the first comprehensive nanometric view of Giardia’s endocytic system architecture and sheds light on the evolution of GlACLC analogues in the Fornicata supergroup and, specific to Giardia, as a possible adaptation to the formation and maintenance of stable clathrin assemblies at PVs. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01402-3.
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Affiliation(s)
- Rui Santos
- Institute of Parasitology, University of Zürich, Winterthurerstrasse 266a, 8057, Zürich, Switzerland.,Institute of Anatomy, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Ásgeir Ástvaldsson
- Department of Cell and Molecular Biology, University of Uppsala, Husargatan 3, 752 37, Uppsala, Sweden.,Department of Microbiology, National Veterinary Institute, 751 23, Uppsala, Sweden
| | - Shweta V Pipaliya
- Division of Infectious Diseases, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.,School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland and Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Jon Paulin Zumthor
- Amt für Lebensmittelsicherheit und Tiergesundheit Graubünden, Chur, Switzerland
| | - Joel B Dacks
- Division of Infectious Diseases, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.,Institute of Parasitology, Biology Centre, CAS, v.v.i., Branisovska 31, 370 05, Ceske Budejovice, Czech Republic
| | - Staffan Svärd
- Department of Cell and Molecular Biology, University of Uppsala, Husargatan 3, 752 37, Uppsala, Sweden
| | - Adrian B Hehl
- Institute of Parasitology, University of Zürich, Winterthurerstrasse 266a, 8057, Zürich, Switzerland
| | - Carmen Faso
- Institute of Cell Biology, University of Bern, Bern, Switzerland. .,Multidisciplinary Center for Infectious Diseases, Vetsuisse, University of Bern, Bern, Switzerland.
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3
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In situ visualization of a simple bipartite kinetochore with a single microtubule attachment in Giardia intestinalis (Metamonada). Eur J Cell Biol 2022; 101:151217. [DOI: 10.1016/j.ejcb.2022.151217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/17/2022] [Accepted: 03/15/2022] [Indexed: 11/18/2022] Open
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4
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Abstract
Giardia intestinalis, the causative agent of giardiasis, has complex cytoskeleton organization with structures involved in motility, adhesion, cell division, and cell differentiation. Microtubules are key components of the cytoskeleton and are the main elements of the ventral disc, median body, funis, in addition to four pairs of flagella. These cytoskeletal elements are basically stable microtubule arrangements. Although tubulins are the main proteins of these elements, molecular and biochemical analyses of Giardia trophozoites have revealed the presence of several new and not yet characterized proteins in these structures, which may contribute to their nanoarchitecture (mainly in the ventral disc). Despite these findings, morphological data are still required for understanding the organization and biogenesis of the cytoskeletal structures. In the study of this complex and specialized network of filaments in Giardia, two distinct and complementary approaches have been used in recent years: (a) transmission electron microscopy tomography of conventionally processed as well as cryo-fixed samples and (b) high-resolution scanning electron microscopy and helium ion microscopy in combination with new plasma membrane extraction protocols. In this review we include the most recent studies that have allowed better understanding of new Giardia components and their association with other filamentous structures of this parasite, thus providing new insights in the role of the cytoskeletal structures and their function in Giardia trophozoites.
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de Carvalho LSA, Alves Jr Ij, Junqueira LR, Silva LM, Riani LR, de Faria Pinto P, da Silva Filho AA. ATP-Diphosphohydrolases in Parasites: Localization, Functions and Recent Developments in Drug Discovery. Curr Protein Pept Sci 2020; 20:873-884. [PMID: 31272352 DOI: 10.2174/1389203720666190704152827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/19/2019] [Accepted: 05/30/2019] [Indexed: 01/11/2023]
Abstract
ATP-diphosphohydrolases (EC 3.6.1.5), also known as ATPDases, NTPases, NTPDases, EATPases or apyrases, are enzymes that hydrolyze a variety of nucleoside tri- and diphosphates to their respective nucleosides, being their activities dependent on the presence of divalent cations, such as calcium and magnesium. Recently, ATP-diphosphohydrolases were identified on the surface of several parasites, such as Trypanosoma sp, Leishmania sp and Schistosoma sp. In parasites, the activity of ATPdiphosphohydrolases has been associated with the purine recuperation and/or as a protective mechanism against the host organism under conditions that involve ATP or ADP, such as immune responses and platelet activation. These proteins have been suggested as possible targets for the development of new antiparasitic drugs. In this review, we will comprehensively address the main aspects of the location and function of ATP-diphosphohydrolase in parasites. Also, we performed a detailed research in scientific database of recent developments in new natural and synthetic inhibitors of the ATPdiphosphohydrolases in parasites.
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Affiliation(s)
- Lara Soares Aleixo de Carvalho
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Alves Jr Ij
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Lauriene Ricardo Junqueira
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Lívia Mara Silva
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Lorena Rodrigues Riani
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
| | - Priscila de Faria Pinto
- Departament of Biochemistry, Institute of Biological Sciences, Federal University of Juiz de Fora, Juiz de Fora, MG, Brazil
| | - Ademar Alves da Silva Filho
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
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Joukov V, De Nicolo A. The Centrosome and the Primary Cilium: The Yin and Yang of a Hybrid Organelle. Cells 2019; 8:E701. [PMID: 31295970 PMCID: PMC6678760 DOI: 10.3390/cells8070701] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/04/2019] [Accepted: 07/06/2019] [Indexed: 12/27/2022] Open
Abstract
Centrosomes and primary cilia are usually considered as distinct organelles, although both are assembled with the same evolutionary conserved, microtubule-based templates, the centrioles. Centrosomes serve as major microtubule- and actin cytoskeleton-organizing centers and are involved in a variety of intracellular processes, whereas primary cilia receive and transduce environmental signals to elicit cellular and organismal responses. Understanding the functional relationship between centrosomes and primary cilia is important because defects in both structures have been implicated in various diseases, including cancer. Here, we discuss evidence that the animal centrosome evolved, with the transition to complex multicellularity, as a hybrid organelle comprised of the two distinct, but intertwined, structural-functional modules: the centriole/primary cilium module and the pericentriolar material/centrosome module. The evolution of the former module may have been caused by the expanding cellular diversification and intercommunication, whereas that of the latter module may have been driven by the increasing complexity of mitosis and the requirement for maintaining cell polarity, individuation, and adhesion. Through its unique ability to serve both as a plasma membrane-associated primary cilium organizer and a juxtanuclear microtubule-organizing center, the animal centrosome has become an ideal integrator of extracellular and intracellular signals with the cytoskeleton and a switch between the non-cell autonomous and the cell-autonomous signaling modes. In light of this hypothesis, we discuss centrosome dynamics during cell proliferation, migration, and differentiation and propose a model of centrosome-driven microtubule assembly in mitotic and interphase cells. In addition, we outline the evolutionary benefits of the animal centrosome and highlight the hierarchy and modularity of the centrosome biogenesis networks.
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Affiliation(s)
- Vladimir Joukov
- N.N. Petrov National Medical Research Center of Oncology, 197758 Saint-Petersburg, Russia.
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Coelho CH, Silva ACC, Costa AO, Fernandes AP. Morphological and physiological characteristics of a virulent and zoonotic assemblage A Giardia duodenalis canine strain. Acta Trop 2017; 174:76-81. [PMID: 28689000 DOI: 10.1016/j.actatropica.2017.07.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/27/2017] [Accepted: 07/04/2017] [Indexed: 12/29/2022]
Abstract
Giardiasis is an intestinal parasitosis that affects millions of people worldwide and is considered a zoonotic disease. Frequently in contact with humans, dogs are the main host involved in this zoonotic transmission. Here, we compared some aspects of Giardia duodenalis biology between two strains: a recently isolated dog strain (BHFC1) and a human reference strain (Portland-1). Growth curve analysis revealed that BHFC1 trophozoites multiply faster than the human isolate Portland-1 in axenic culture, but has a lower rate of cysts formation. Scanning electron microscopy revealed that BHFC1 trophozoites have the same conventional shape and morphological structures expected for G. duodenalis trophozoites, but presented a more prominent flange. For the best of our knowledge, this work is the first description of morphological aspects and encystation process of a G. duodenalis strain isolated from a dog. Since BHFC1 and Portland-1 have been maintained in axenic cultures for different periods of time, differences observed in growth, encystation rates and flange size may be attributed to adaptation of Portland-1 to axenic culture and lack of the environmental pressures. BHFC1 can be useful as tool for better understanding of Giardia duodenalis biology.
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Gräf R, Batsios P, Meyer I. Evolution of centrosomes and the nuclear lamina: Amoebozoan assets. Eur J Cell Biol 2015; 94:249-56. [DOI: 10.1016/j.ejcb.2015.04.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/21/2015] [Accepted: 04/21/2015] [Indexed: 02/08/2023] Open
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9
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Lauwaet T, Smith AJ, Reiner DS, Romijn EP, Wong CCL, Davids BJ, Shah SA, Yates JR, Gillin FD. Mining the Giardia genome and proteome for conserved and unique basal body proteins. Int J Parasitol 2011; 41:1079-92. [PMID: 21723868 DOI: 10.1016/j.ijpara.2011.06.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/25/2011] [Accepted: 06/01/2011] [Indexed: 12/27/2022]
Abstract
Giardia lamblia is a flagellated protozoan parasite and a major cause of diarrhoea in humans. Its microtubular cytoskeleton mediates trophozoite motility, attachment and cytokinesis, and is characterised by an attachment disk and eight flagella that are each nucleated in a basal body. To date, only 10 giardial basal body proteins have been identified, including universal signalling proteins that are important for regulating mitosis or differentiation. In this study, we have exploited bioinformatics and proteomic approaches to identify new Giardia basal body proteins and confocal microscopy to confirm their localisation in interphase trophozoites. This approach identified 75 homologs of conserved basal body proteins in the genome including 65 not previously known to be associated with Giardia basal bodies. Thirteen proteins were confirmed to co-localise with centrin to the Giardia basal bodies. We also demonstrate that most basal body proteins localise to additional cytoskeletal structures in interphase trophozoites. This might help to explain the roles of the four pairs of flagella and Giardia-specific organelles in motility and differentiation. A deeper understanding of the composition of the Giardia basal bodies will contribute insights into the complex signalling pathways that regulate its unique cytoskeleton and the biological divergence of these conserved organelles.
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Affiliation(s)
- Tineke Lauwaet
- Department of Pathology, University of California San Diego, San Diego, CA 92103, USA.
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10
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Davids BJ, Williams S, Lauwaet T, Palanca T, Gillin FD. Giardia lamblia aurora kinase: a regulator of mitosis in a binucleate parasite. Int J Parasitol 2007; 38:353-69. [PMID: 17964578 DOI: 10.1016/j.ijpara.2007.08.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 08/21/2007] [Accepted: 08/23/2007] [Indexed: 12/18/2022]
Abstract
Giardia lamblia is a major cause of diarrhoeal disease worldwide. Since it has no known toxin, the ability of trophozoites to colonise the human small intestine is required for its pathogenesis. Mitosis in this protozoan parasite is a unique challenge because its two equivalent nuclei and complex cytoskeleton must be duplicated and segregated accurately. Giardial mitosis is a complex and rapid event that is poorly understood at the cellular and molecular levels. Higher eukaryotes have one to three members of the highly conserved Ser/Thr aurora kinase (AK) family that regulate key aspects of mitosis and cytokinesis. Giardia has a single AK orthologue (gAK) with 61% similarity to human AK A. In addition to the conserved active site residues, activation loop and destruction-box motifs characteristic of AKs, gAK contains a unique insert near the active site region. We epitope-tagged gAK at its C-terminus and expressed it under its own promoter. During interphase, gAK localises exclusively to the nuclei, but is not phosphorylated as shown by lack of staining with an antibody specific to phosphorylated AK A (pAK). In contrast, during mitosis pAK localises to the basal bodies/centrosomes and co-localises with tubulin to the spindle. During specific stages of mitosis, giardial pAK also localised dynamically to cytoskeletal structures unique to Giardia: the paraflagellar dense rods of the anterior flagella and the median body, whose functions are unknown, as well as to the parent attachment disc. Two AK inhibitors significantly decreased giardial growth and increased the numbers of cells arrested in cytokinesis. These inhibitors appeared to increase microtubule nucleation and cell-ploidy. Our data show that gAK is phosphorylated in mitosis and suggest that it plays an important role in the Giardia cell cycle. The pleiotropic localisation of AK suggests that it may co-ordinate the reorganisation and segregation of tubulin-containing structures in mitosis. We believe this is the first report of a signalling protein regulating cell division in Giardia.
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Affiliation(s)
- Barbara J Davids
- Department of Pathology, Division of Infectious Diseases, University of California at San Diego, 214 Dickinson Street, San Diego, CA 92103-8416, USA.
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Sloboda RD, Howard L. Localization of EB1, IFT polypeptides, and kinesin-2 in Chlamydomonas flagellar axonemes via immunogold scanning electron microscopy. ACTA ACUST UNITED AC 2007; 64:446-60. [PMID: 17326139 DOI: 10.1002/cm.20195] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Intraflagellar transport (IFT) refers to the bi-directional movement of particles and associated cargo along the axonemes of eukaryotic flagella and cilia. To provide a new perspective on the morphology of IFT particles, their association with the axoneme, and their composition, we have used immunogold localization coupled to detection via scanning electron microscopy. Here we co-localize in the Chlamydomonas flagellar axoneme polypeptides labeled with specific antibodies. Chlamydomonas EB1 localizes to the distal tip of the axoneme, as expected from previous immunofluorescent data (Pedersen et al. Curr Biol2003;13(22):1969-1974), thus demonstrating the utility of this approach. Using antibodies to IFT-related polypeptides, particles can be identified associated with the axoneme that fall into one of two classes: The first class is composed of IFT particles labeled with polyclonal antibodies to kinesin-2 and monoclonal antibodies to either IFT139 (an IFT complex A polypeptide) or IFT172 (a complex B polypeptide). The second class is comprised of particles that label with antibodies to IFT139 alone; thus, discrete particles are present associated with the axoneme that are composed only of complex A polypeptides. When IFT particles were purified by sucrose gradient ultracentrifugation, they appeared as more or less spherical aggregates of varying dimensions labeled with antibodies to IFT139 and to the motor protein kinesin-2. By contrast, isolated IFT particles that were labeled with IFT172 antibodies were not labeled with kinesin-2 antibodies. The data are discussed in terms of the total polypeptide composition of an IFT particle and the interaction of the particles with the motors that power IFT.
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Affiliation(s)
- Roger D Sloboda
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
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de Souza W, Campanati L, Attias M. Strategies and results of field emission scanning electron microscopy (FE-SEM) in the study of parasitic protozoa. Micron 2006; 39:77-87. [PMID: 17174097 DOI: 10.1016/j.micron.2006.11.003] [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: 11/06/2006] [Accepted: 11/07/2006] [Indexed: 10/23/2022]
Abstract
Field emission scanning electron microscopy (FE-SEM) provides a range of strategies for investigating the structural organization of biological systems, varying from isolated macromolecules to tissue organization and whole organisms. This review covers some of the results so far obtained using FE-SEM observation and various protocols of sample fixation to analyze the structural organization of parasitic protozoa and their interaction with host cells. The employment of FE-SEM can be broadened through the use of gold-labeled molecules or tracers, gradual extraction by detergents, and cleavage techniques. These analyses provide significant contributions to the characterization of these organisms concerning ultrastructure, cytoskeleton, motility and intracellular behavior.
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Affiliation(s)
- Wanderley de Souza
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Ilha do Fundão, 21949-900 Rio de Janeiro, RJ, Brazil.
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Benchimol M. New ultrastructural observations on the skeletal matrix of Tritrichomonas foetus. Parasitol Res 2005; 97:408-16. [PMID: 16151733 DOI: 10.1007/s00436-005-1480-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Accepted: 07/27/2005] [Indexed: 11/28/2022]
Abstract
Tritrichomonas foetus, a parasitic protozoon of the urogenital tract in cattle, presents a poorly known cytoskeleton, formed by rootlets and proteinaceous structures, many of which have not yet been characterized. Studies on its skeletal organization sheds light on the evolution of the matrix system, characteristic of higher eukaryotes. The skeletal matrix system of T. foetus in interphasic and dividing cells were studied using whole mount cell procedures observed either in field emission scanning electron microscopy (FESEM) or in transmission electron microscope (TEM) after the cell-sandwich technique, where the plasma membrane was mechanically removed. Three-dimensional-like images of the cell matrix were attained revealing a network of filaments that has not been described previously. Freeze-etching and cytochemistry using acridine orange for TEM, were also used. Membrane-skeleton interactions were examined in the hydrogenosomes, on the nuclear envelope at mitosis and interphase, and in the overall matrix filling of the cytoplasm and nucleoplasm. It was demonstrated that this eukaryote has a complex skeletal matrix other than just the rigid cytoskeletal structures. Our analysis indicated that the nucleus has a defined position, and fibrils perform an anchoring system for the nucleus. The possibility of a mechanism for nuclei fidelity migration during mitosis is discussed.
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Affiliation(s)
- Marlene Benchimol
- Laboratório de Ultraestrutura Celular, Universidade Santa Ursula, Botafogo, 222-31-010 Rio de Janeiro, Brazil.
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