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EdU Incorporation To Assess Cell Proliferation and Drug Susceptibility in Naegleria fowleri. Antimicrob Agents Chemother 2021; 65:e0001721. [PMID: 33846135 DOI: 10.1128/aac.00017-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Naegleria fowleri is a pathogenic free-living amoeba that is commonly found in warm freshwater and can cause a rapidly fulminant disease known as primary amoebic meningoencephalitis (PAM). New drugs are urgently needed to treat PAM, as the fatality rate is >97%. Until recently, few advances have been made in the discovery of new drugs for N. fowleri, and one drawback is the lack of validated tools and methods to enhance drug discovery and diagnostics research. In this study, we aimed to validate alternative methods to assess cell proliferation that are commonly used for other cell types and develop a novel drug screening assay to evaluate drug efficacy on N. fowleri replication. EdU (5-ethynyl-2'-deoxyuridine) is a pyrimidine analog of thymidine that can be used as a quantitative endpoint for cell proliferation. EdU incorporation is detected via a copper catalyzed click reaction with an Alexa Fluor-linked azide. EdU incorporation in replicating N. fowleri was validated using fluorescence microscopy, and quantitative methods for assessing EdU incorporation were developed by using an imaging flow cytometer. Currently used PAM therapeutics inhibited N. fowleri replication and EdU incorporation in vitro. EdA (7-deaza-2'-deoxy-7-ethynyladenosine), an adenine analog, also was incorporated by N. fowleri but was more cytotoxic than EdU. In summary, EdU incorporation could be used as a complimentary method for drug discovery for these neglected pathogens.
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2
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Ultra-structural analysis and morphological changes during the differentiation of trophozoite to cyst in Entamoeba invadens. Mol Biochem Parasitol 2021; 242:111363. [PMID: 33524469 DOI: 10.1016/j.molbiopara.2021.111363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 11/21/2022]
Abstract
Entamoeba histolytica, a pathogenic parasite, is the causative organism of amoebiasis and uses human colon to complete its life cycle. It destroys intestinal tissue leading to invasive disease. Since it does not form cyst in culture medium, a reptilian parasite Entamoeba invadens serves as the model system to study encystation. Detailed investigation on the mechanism of cyst formation, information on ultra-structural changes and cyst wall formation during encystation are still lacking in E. invadens. Here, we used electron microscopy to study the ultrastructural changes during cyst formation and showed that the increase in heterochromatin patches and deformation of nuclear shape were early events in encystation. These changes peaked at ∼20 h post induction, and normal nuclear morphology was restored by 72 h. Two types of cellular structures were visible by 16 h. One was densely stained and consisted of the cytoplasmic mass with clearly visible nucleus. The other consisted of membranous shells with large vacuoles and scant cytoplasm. The former structure developed into the mature cyst while the latter structure was lost after 20 h, This study of ultra-structural changes during encystation in E. invadens opens up the possibilities for further investigation into the mechanisms involved in this novel process.
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3
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Varghese SS, Ghosh SK. Stress-responsive Entamoeba topoisomerase II: a potential antiamoebic target. FEBS Lett 2019; 594:1005-1020. [PMID: 31724164 DOI: 10.1002/1873-3468.13677] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 11/05/2019] [Accepted: 11/05/2019] [Indexed: 12/21/2022]
Abstract
Topoisomerases, the ubiquitous enzymes involved in all DNA processes across the biological world, are targets for various anticancer and antimicrobial agents. In Entamoeba histolytica, the causative agent of amebiasis, we found one of seven unexplored putative topoisomerases to be highly upregulated during heat shock and oxidative stress, and also during the late hours of encystation. Further analysis revealed the upregulated enzyme to be a eukaryotic type IIA topoisomerase (TopoII) with demonstrable activity in vitro. This enzyme is localized to newly forming nuclei during encystation. Gene silencing of the TopoII reduces viability and encystation efficiency. Notable susceptibility of Entamoeba TopoII to prokaryotic topoisomerase inhibitors opens up the possibility for exploring this enzyme as a new antiamoebic target.
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Affiliation(s)
- Sneha Susan Varghese
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Sudip Kumar Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India
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4
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Naiyer S, Bhattacharya A, Bhattacharya S. Advances in Entamoeba histolytica Biology Through Transcriptomic Analysis. Front Microbiol 2019; 10:1921. [PMID: 31481949 PMCID: PMC6710346 DOI: 10.3389/fmicb.2019.01921] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/05/2019] [Indexed: 12/13/2022] Open
Abstract
A large number of transcriptome-level studies in Entamoeba histolytica, the protozoan parasite that causes amoebiasis, have investigated gene expression patterns to help understand the pathology and biology of the organism. They have compared virulent and avirulent strains in lab culture and after tissue invasion, cells grown under different stress conditions, response to anti-amoebic drug treatments, and gene expression changes during the process of encystation. These studies have revealed interesting molecules/pathways that will help increase our mechanistic understanding of differentially expressed genes during growth perturbations and tissue invasion. Some of the important insights obtained from transcriptome studies include the observations that regulation of carbohydrate metabolism may be an important determinant for tissue invasion, while the novel up-regulated genes during encystation include phospholipase D, and meiotic genes, suggesting the possibility of meiosis during the process. Classification of genes according to expression levels showed that amongst the highly transcribed genes in cultured E. histolytica trophozoites were some virulence factors, raising the question of the role of these factors in normal parasite growth. Promoter motifs associated with differential gene expression and regulation were identified. Some of these motifs associated with high gene expression were located downstream of start codon, and were required for efficient transcription. The listing of E. histolytica genes according to transcript expression levels will help us determine the scale of post-transcriptional regulation, and the possible roles of predicted promoter motifs. The small RNA transcriptome is a valuable resource for detailed structural and functional analysis of these molecules and their regulatory roles. These studies provide new drug targets and enhance our understanding of gene regulation in E. histolytica.
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Affiliation(s)
- Sarah Naiyer
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Sudha Bhattacharya
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
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5
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Welter BH, Sehorn MG, Temesvari LA. Flow cytometric characterization of encystation in Entamoeba invadens. Mol Biochem Parasitol 2017; 218:23-27. [PMID: 29037797 DOI: 10.1016/j.molbiopara.2017.10.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/12/2017] [Accepted: 10/13/2017] [Indexed: 10/18/2022]
Abstract
Entamoeba histolytica causes dysentery and liver abscess mostly in countries that lack proper sanitation. Infection is acquired by ingestion of the cyst form in contaminated food or water. E. histolytica does not encyst in vitro; thus, E. invadens, a reptilian parasite that encysts in vitro, has been used as a surrogate. Cysts are small and possess chitin-rich walls. These are characteristics that may be exploited by flow cytometry. We stained encysting E. invadens cells with a fluorescent chitin stain, and analyzed fluorescence and forward scatter by flow cytometry. We demonstrate that flow cytometry can be used to track differentiation, reveal unique cell populations, and evaluate encystation inhibitors.
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Affiliation(s)
- Brenda H Welter
- Department of Biological Sciences, Clemson University, Clemson, SC, 29634, USA; Eukaryotic Pathogens Innovation Center (EPIC), Clemson University, Clemson, SC, 29634, USA
| | - Michael G Sehorn
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC, 29634, USA; Eukaryotic Pathogens Innovation Center (EPIC), Clemson University, Clemson, SC, 29634, USA
| | - Lesly A Temesvari
- Department of Biological Sciences, Clemson University, Clemson, SC, 29634, USA; Eukaryotic Pathogens Innovation Center (EPIC), Clemson University, Clemson, SC, 29634, USA.
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6
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Herman E, Siegesmund MA, Bottery MJ, van Aerle R, Shather MM, Caler E, Dacks JB, van der Giezen M. Membrane Trafficking Modulation during Entamoeba Encystation. Sci Rep 2017; 7:12854. [PMID: 28993644 PMCID: PMC5634486 DOI: 10.1038/s41598-017-12875-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 09/11/2017] [Indexed: 12/15/2022] Open
Abstract
Entamoeba histolytica is an intestinal parasite that infects 50-100 million people and causes up to 55,000 deaths annually. The transmissive form of E. histolytica is the cyst, with a single infected individual passing up to 45 million cysts per day, making cyst production an attractive target for infection control. Lectins and chitin are secreted to form the cyst wall, although little is known about the underlying membrane trafficking processes supporting encystation. As E. histolytica does not readily form cysts in vitro, we assessed membrane trafficking gene expression during encystation in the closely related model Entamoeba invadens. Genes involved in secretion are up-regulated during cyst formation, as are some trans-Golgi network-to-endosome trafficking genes. Furthermore, endocytic and general trafficking genes are up-regulated in the mature cyst, potentially preserved as mRNA in preparation for excystation. Two divergent dynamin-related proteins found in Entamoeba are predominantly expressed during cyst formation. Phylogenetic analyses indicate that they are paralogous to, but quite distinct from, classical dynamins found in human, suggesting that they may be potential drug targets to block encystation. The membrane-trafficking machinery is clearly regulated during encystation, providing an additional facet to understanding this crucial parasitic process.
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Affiliation(s)
- Emily Herman
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, T6G 2H7, Edmonton, Alberta, Canada
| | | | - Michael J Bottery
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK
| | - Ronny van Aerle
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Centre for Environment, Fisheries, and Aquaculture Science (Cefas), Barrack Road, The Nothe, Weymouth, Dorset, DT4 8UB, UK
| | | | - Elisabet Caler
- J. Craig Venter Institute, 9714 Medical Center Drive, Rockville, MD, 20850, USA
- National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), 6701, Rockledge Drive, Room 9144, Bethesda, MD, 20892-7950, USA
| | - Joel B Dacks
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, T6G 2H7, Edmonton, Alberta, Canada.
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7
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Verma D, Murmu A, Gourinath S, Bhattacharya A, Chary KVR. Structure of Ca2+-binding protein-6 from Entamoeba histolytica and its involvement in trophozoite proliferation regulation. PLoS Pathog 2017; 13:e1006332. [PMID: 28505197 PMCID: PMC5444848 DOI: 10.1371/journal.ppat.1006332] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 05/25/2017] [Accepted: 04/03/2017] [Indexed: 12/01/2022] Open
Abstract
Cell cycle of Entamoeba histolytica, the etiological agent of amoebiasis, follows a novel pathway, which includes nuclear division without the nuclear membrane disassembly. We report a nuclear localized Ca2+-binding protein from E. histolytica (abbreviated hereafter as EhCaBP6), which is associated with microtubules. We determined the 3D solution NMR structure of EhCaBP6, and identified one unusual, one canonical and two non-canonical cryptic EF-hand motifs. The cryptic EF-II and EF-IV pair with the Ca2+-binding EF-I and EF-III, respectively, to form a two-domain structure similar to Calmodulin and Centrin proteins. Downregulation of EhCaBP6 affects cell proliferation by causing delays in transition from G1 to S phase, and inhibition of DNA synthesis and cytokinesis. We also demonstrate that EhCaBP6 modulates microtubule dynamics by increasing the rate of tubulin polymerization. Our results, including structural inferences, suggest that EhCaBP6 is an unusual CaBP involved in regulating cell proliferation in E. histolytica similar to nuclear Calmodulin. E. histolytica, the etiological agent of amoebiasis, is a protozoan parasite responsible for around 100,000 deaths per year in developing nations. Though the organism has been identified more than 100 years back, there is not much understanding about the biology of this organism. Calcium signaling plays an important role in the biology of this organism. Here we show structure-functional relationship of one of the Ca2+-binding proteins (abbreviated as EhCaBP6) and suggest its involvement in cell division in this parasite. EhCaBP6, a nucleo-cytosolic Ca2+-binding protein, is a microtubule end binding protein and overexpression of its gene induces an increase in number of microtubular assemblies in E. histolytica. Cell division cycle in E. histolytica occurs along the microtubular structures without disruption of nuclear envelope. Occurrence of multinucleated cells in culture suggests duplication and reduplication of nuclear DNA without cytokinesis. Although Kinesin like protein (Klp1), Formin1 and EhCaBP6 were shown to be part of the microtubular assembly, their role in regulation of the cell cycle is not yet documented. Further, E. histolytica does not have a typical CaM like protein. However, the 3D structure of EhCaBP6 with two Ca2+-binding sites is similar to CaM, in spite of their low sequence similarity. Here, we demonstrate that EhCaBP6 regulates cell cycle specifically by facilitating DNA synthesis, transition from G1 to S phase and cytokinesis. The structural and functional similarity between EhCaBP6 and CaM suggests EhCaBP6 to be a functional homologue of nuclear CaM with important roles in regulation of cell cycle.
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Affiliation(s)
- Deepshikha Verma
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
- Tata Institute of Fundamental Research, Center for Interdisciplinary Sciences, Hyderabad, India
| | - Aruna Murmu
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | | | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Kandala V. R. Chary
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India
- Tata Institute of Fundamental Research, Center for Interdisciplinary Sciences, Hyderabad, India
- * E-mail:
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8
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Singh N, Singh AB. Deubiquitinases and cancer: A snapshot. Crit Rev Oncol Hematol 2016; 103:22-6. [PMID: 27211605 PMCID: PMC7128910 DOI: 10.1016/j.critrevonc.2016.04.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 03/19/2016] [Accepted: 04/27/2016] [Indexed: 12/31/2022] Open
Abstract
Ubiquitination is the vital system for controlling protein degradation and regulation of basic cellular processes. Deubiquitinases (DUBs) are emerging as an important regulator of several pathways related to cancer and other diseases. Their ability to detach ubiquitin from the target substrate and regulation of signaling makes it potential target to treat cancer and other fatal diseases. In the current review, we are trying to summarize deubiquitination, and their role in cancer and potential small molecules DUBs inhibitors which can be used as drugs for cancer treatment.
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Affiliation(s)
- Nishant Singh
- Department of Biological Sciences, Cleveland State University, Cleveland, OH 44115, USA.
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9
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Singh M, Sharma S, Bhattacharya A, Tatu U. Heat Shock Protein 90 regulates encystation in Entamoeba. Front Microbiol 2015; 6:1125. [PMID: 26528271 PMCID: PMC4602144 DOI: 10.3389/fmicb.2015.01125] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 09/28/2015] [Indexed: 11/18/2022] Open
Abstract
Enteric protozoan Entamoeba histolytica is a major cause of debilitating diarrheal infection worldwide with high morbidity and mortality. Even though the clinical burden of this parasite is very high, this infection is categorized as a neglected disease. Parasite is transmitted through feco-oral route and exhibit two distinct stages namely – trophozoites and cysts. Mechanism and regulation of encystation is not clearly understood. Previous studies have established the role of Heat shock protein 90 (Hsp90) in regulating stage transition in various protozoan parasites like Giardia, Plasmodium, Leishmania, and Toxoplasma. Our study for the first time reports that Hsp90 plays a crucial role in life cycle of Entamoeba as well. We identify Hsp90 to be a negative regulator of encystation in Entamoeba. We also show that Hsp90 inhibition interferes with the process of phagocytosis in Entamoeba. Overall, we show that Hsp90 plays an important role in virulence and transmission of Entamoeba.
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Affiliation(s)
- Meetali Singh
- Department of Biochemistry, Indian Institute of Science Bangalore, India
| | - Shalini Sharma
- School of Life Sciences, Jawaharlal Nehru University New Delhi, India
| | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University New Delhi, India
| | - Utpal Tatu
- Department of Biochemistry, Indian Institute of Science Bangalore, India
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10
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Kelso AA, Say AF, Sharma D, Ledford LL, Turchick A, Saski CA, King AV, Attaway CC, Temesvari LA, Sehorn MG. Entamoeba histolytica Dmc1 Catalyzes Homologous DNA Pairing and Strand Exchange That Is Stimulated by Calcium and Hop2-Mnd1. PLoS One 2015; 10:e0139399. [PMID: 26422142 PMCID: PMC4589404 DOI: 10.1371/journal.pone.0139399] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 09/12/2015] [Indexed: 01/03/2023] Open
Abstract
Meiosis depends on homologous recombination (HR) in most sexually reproducing organisms. Efficient meiotic HR requires the activity of the meiosis-specific recombinase, Dmc1. Previous work shows Dmc1 is expressed in Entamoeba histolytica, a eukaryotic parasite responsible for amoebiasis throughout the world, suggesting this organism undergoes meiosis. Here, we demonstrate Dmc1 protein is expressed in E. histolytica. We show that purified ehDmc1 forms presynaptic filaments and catalyzes ATP-dependent homologous DNA pairing and DNA strand exchange over at least several thousand base pairs. The DNA pairing and strand exchange activities are enhanced by the presence of calcium and the meiosis-specific recombination accessory factor, Hop2-Mnd1. In combination, calcium and Hop2-Mnd1 dramatically increase the rate of DNA strand exchange activity of ehDmc1. The biochemical system described herein provides a basis on which to better understand the role of ehDmc1 and other HR proteins in E. histolytica.
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Affiliation(s)
- Andrew A. Kelso
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Amanda F. Say
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Deepti Sharma
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, United States of America
| | - LeAnna L. Ledford
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Audrey Turchick
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Christopher A. Saski
- Clemson University Genomics and Computational Biology Laboratory, Institute for Translational Genomics, Clemson, South Carolina, United States of America
| | - Ada V. King
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Christopher C. Attaway
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
| | - Lesly A. Temesvari
- Department of Biological Sciences, Clemson University, Clemson, South Carolina, United States of America
- Clemson University School of Health Research, Clemson, South Carolina, United States of America
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, South Carolina, United States of America
| | - Michael G. Sehorn
- Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, United States of America
- Clemson University School of Health Research, Clemson, South Carolina, United States of America
- Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, South Carolina, United States of America
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11
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Shukla S, Arora V, Jadaun A, Kumar J, Singh N, Jain VK. Magnetic removal of Entamoeba cysts from water using chitosan oligosaccharide-coated iron oxide nanoparticles. Int J Nanomedicine 2015; 10:4901-17. [PMID: 26261417 PMCID: PMC4527572 DOI: 10.2147/ijn.s77675] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Amebiasis, a major health problem in developing countries, is the second most common cause of death due to parasitic infection. Amebiasis is usually transmitted by the ingestion of Entamoeba histolytica cysts through oral–fecal route. Herein, we report on the use of chitosan oligosaccharide-functionalized iron oxide nanoparticles for efficient capture and removal of pathogenic protozoan cysts under the influence of an external magnetic field. These nanoparticles were synthesized through a chemical synthesis process. The synthesized particles were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and zeta potential analysis. The particles were found to be well dispersed and uniform in size. The capture and removal of pathogenic cysts were demonstrated by fluorescent microscopy, transmission electron microscopy, and scanning electron microscopy (SEM). Three-dimensional modeling of various biochemical components of cyst walls, and thereafter, flexible docking studies demonstrate the probable interaction mechanism of nanoparticles with various components of E. histolytica cyst walls. Results of the present study suggest that E. histolytica cysts can be efficiently captured and removed from contaminated aqueous systems through the application of synthesized nanoparticles.
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Affiliation(s)
- Sudeep Shukla
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Vikas Arora
- Department of Chemistry, Indian Institute of Technology, New Delhi, Delhi, India
| | - Alka Jadaun
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Jitender Kumar
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Nishant Singh
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Vinod Kumar Jain
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
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12
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Ojha S, Ahamad J, Bhattacharya A, Bhattacharya S. Ribosomal RNA and protein transcripts persist in the cysts of Entamoeba invadens. Mol Biochem Parasitol 2014; 195:6-9. [PMID: 24880110 DOI: 10.1016/j.molbiopara.2014.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 05/18/2014] [Accepted: 05/20/2014] [Indexed: 11/30/2022]
Abstract
In most organisms rDNA transcription ceases under conditions of growth stress. However, we have earlier shown that pre-rRNA accumulates during encystation in Entamoeba invadens. We labeled newly-synthesized rRNA during encystation, with [methyl-(3)H] methionine in the presence of chitinase to enable uptake of isotope. Incorporation rate reduced after 24h, and then increased to reach levels comparable with normal cells. The label was rapidly chased to the ribosomal pellet in dividing cells, while at late stages of encystation the ratio of counts going to the pellet dropped 3-fold. The transcript levels of selected ribosomal protein genes also went down initially but went up again at later stages of encystation. This suggested that rRNA and ribosomal protein transcription may be coordinately regulated. Our data shows that encysting E. invadens cells accumulate transcripts of both the RNA and protein components of the ribosome, which may ensure rapid synthesis of new ribosomes when growth resumes.
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Affiliation(s)
- Sandeep Ojha
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Jamaluddin Ahamad
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Sudha Bhattacharya
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
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13
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The ribosomal RNA transcription unit of Entamoeba invadens: Accumulation of unprocessed pre-rRNA and a long non coding RNA during encystation. Mol Biochem Parasitol 2013; 192:30-8. [DOI: 10.1016/j.molbiopara.2013.10.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/25/2013] [Accepted: 10/29/2013] [Indexed: 01/20/2023]
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14
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Singh N, Bhattacharya A, Bhattacharya S. Homologous Recombination Occurs in Entamoeba and Is Enhanced during Growth Stress and Stage Conversion. PLoS One 2013; 8:e74465. [PMID: 24098652 PMCID: PMC3787063 DOI: 10.1371/journal.pone.0074465] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 08/01/2013] [Indexed: 12/28/2022] Open
Abstract
Homologous recombination (HR) has not been demonstrated in the parasitic protists Entamoeba histolytica or Entamoeba invadens, as no convenient method is available to measure it. However, HR must exist to ensure genome integrity, and possible genetic exchange, especially during stage conversion from trophozoite to cyst. Here we show the up regulation of mitotic and meiotic HR genes in Entamoeba during serum starvation, and encystation. To directly demonstrate HR we use a simple PCR-based method involving inverted repeats, which gives a reliable read out, as the recombination junctions can be determined by sequencing the amplicons. Using this read out, we demonstrate enhanced HR under growth stress in E. histolytica, and during encystation in E. invadens. We also demonstrate recombination between chromosomal inverted repeats. This is the first experimental demonstration of HR in Entamoeba and will help future investigations into this process, and to explore the possibility of meiosis in Entamoeba.
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Affiliation(s)
- Nishant Singh
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Alok Bhattacharya
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Sudha Bhattacharya
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
- * E-mail:
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15
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Ehrenkaufer GM, Weedall GD, Williams D, Lorenzi HA, Caler E, Hall N, Singh U. The genome and transcriptome of the enteric parasite Entamoeba invadens, a model for encystation. Genome Biol 2013; 14:R77. [PMID: 23889909 PMCID: PMC4053983 DOI: 10.1186/gb-2013-14-7-r77] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 07/26/2013] [Indexed: 12/27/2022] Open
Abstract
Background Several eukaryotic parasites form cysts that transmit infection. The process is found in diverse organisms such as Toxoplasma, Giardia, and nematodes. In Entamoeba histolytica this process cannot be induced in vitro, making it difficult to study. In Entamoeba invadens, stage conversion can be induced, but its utility as a model system to study developmental biology has been limited by a lack of genomic resources. We carried out genome and transcriptome sequencing of E. invadens to identify molecular processes involved in stage conversion. Results We report the sequencing and assembly of the E. invadens genome and use whole transcriptome sequencing to characterize changes in gene expression during encystation and excystation. The E. invadens genome is larger than that of E. histolytica, apparently largely due to expansion of intergenic regions; overall gene number and the machinery for gene regulation are conserved between the species. Over half the genes are regulated during the switch between morphological forms and a key signaling molecule, phospholipase D, appears to regulate encystation. We provide evidence for the occurrence of meiosis during encystation, suggesting that stage conversion may play a key role in recombination between strains. Conclusions Our analysis demonstrates that a number of core processes are common to encystation between distantly related parasites, including meiosis, lipid signaling and RNA modification. These data provide a foundation for understanding the developmental cascade in the important human pathogen E. histolytica and highlight conserved processes more widely relevant in enteric pathogens.
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Singh N, Ojha S, Bhattacharya A, Bhattacharya S. Establishment of a transient transfection system and expression of firefly luciferase in Entamoeba invadens. Mol Biochem Parasitol 2012; 183:90-3. [PMID: 22321531 DOI: 10.1016/j.molbiopara.2012.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 01/11/2012] [Accepted: 01/17/2012] [Indexed: 11/17/2022]
Abstract
Entamoeba invadens is used as a model system to study trophozoite to cyst differentiation since Entamoeba histolytica, the causative agent of amoebiasis cannot encyst in culture. However, a system for introduction of cloned genes in E. invadens is not available. Here we report an electroporation-based method for transfection of E. invadens tophozoites and demonstrate the expression of firefly luciferase reporter gene driven from the E. invadens ribosomal protein L3 promoter. The efficiency of luciferase expression driven from the promoters of three different E. invadens genes (rpl3, rps10 and h2b) was tested and found to correlate with the in vivo expression levels of the respective gene. This system will permit the analysis of regulatory elements required for gene expression in E. invadens.
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Affiliation(s)
- Nishant Singh
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
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