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Rivera J, Valerdi-Negreros JC, Vázquez-Enciso DM, Argueta-Zepeda FS, Vinuesa P. Phylogenomic, structural, and cell biological analyses reveal that Stenotrophomonas maltophilia replicates in acidified Rab7A-positive vacuoles of Acanthamoeba castellanii. Microbiol Spectr 2024; 12:e0298823. [PMID: 38319117 PMCID: PMC10913462 DOI: 10.1128/spectrum.02988-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 01/15/2024] [Indexed: 02/07/2024] Open
Abstract
Acanthamoeba species are clinically relevant free-living amoebae (FLA) ubiquitously found in soil and water bodies. Metabolically active trophozoites graze on diverse microbes via phagocytosis. However, functional studies on Rab GTPases (Rabs), which are critical for controlling vesicle trafficking and maturation, are scarce for this FLA. This knowledge gap can be partly explained by the limited genetic tools available for Acanthamoeba cell biology. Here, we developed plasmids to generate fusions of A. castellanii strain Neff proteins to the N- or C-termini of mEGFP and mCherry2. Phylogenomic and structural analyses of the 11 Neff Rab7 paralogs found in the RefSeq assembly revealed that eight of them had non-canonical sequences. After correcting the gene annotation for the Rab7A ortholog, we generated a line stably expressing an mEGFP-Rab7A fusion, demonstrating its correct localization to acidified macropinocytic and phagocytic vacuoles using fluorescence microscopy live cell imaging (LCI). Direct labeling of live Stenotrophomonas maltophilia ESTM1D_MKCAZ16_6a (Sm18) cells with pHrodo Red, a pH-sensitive dye, demonstrated that they reside within acidified, Rab7A-positive vacuoles. We constructed new mini-Tn7 delivery plasmids and tagged Sm18 with constitutively expressed mScarlet-I. Co-culture experiments of Neff trophozoites with Sm18::mTn7TC1_Pc_mScarlet-I, coupled with LCI and microplate reader assays, demonstrated that Sm18 underwent multiple replication rounds before reaching the extracellular medium via non-lytic exocytosis. We conclude that S. maltophilia belongs to the class of bacteria that can use amoeba as an intracellular replication niche within a Stenotrophomonas-containing vacuole that interacts extensively with the endocytic pathway.IMPORTANCEDiverse Acanthamoeba lineages (genotypes) are of increasing clinical concern, mainly causing amoebic keratitis and granulomatous amebic encephalitis among other infections. S. maltophilia ranks among the top 10 most prevalent multidrug-resistant opportunistic nosocomial pathogens and is a recurrent member of the microbiome hosted by Acanthamoeba and other free-living amoebae. However, little is known about the molecular strategies deployed by Stenotrophomonas for an intracellular lifestyle in amoebae and other professional phagocytes such as macrophages, which allow the bacterium to evade the immune system and the action of antibiotics. Our plasmids and easy-to-use microtiter plate co-culture assays should facilitate investigations into the cellular microbiology of Acanthamoeba interactions with Stenotrophomonas and other opportunistic pathogens, which may ultimately lead to the discovery of new molecular targets and antimicrobial therapies to combat difficult-to-treat infections caused by these ubiquitous microbes.
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Affiliation(s)
- Javier Rivera
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
| | - Julio C. Valerdi-Negreros
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
- Programa de Doctorado en Ciencias Biomédicas, UNAM, Mexico City, Mexico
| | - Diana M. Vázquez-Enciso
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
- Programa de Maestría y Doctorado en Ciencias Bioquímicas, UNAM, Mexico City, Mexico
| | - Fulvia-Stefany Argueta-Zepeda
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
- Programa de Maestría y Doctorado en Ciencias Bioquímicas, UNAM, Mexico City, Mexico
| | - Pablo Vinuesa
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, Mexico
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2
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Philippe N, Shukla A, Abergel C, Bisio H. Genetic manipulation of giant viruses and their host, Acanthamoeba castellanii. Nat Protoc 2024; 19:3-29. [PMID: 37964008 DOI: 10.1038/s41596-023-00910-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 08/25/2023] [Indexed: 11/16/2023]
Abstract
Giant viruses (GVs) provide an unprecedented source of genetic innovation in the viral world and are thus, besides their importance in basic and environmental virology, in the spotlight for bioengineering advances. Their host, Acanthamoeba castellanii, is an accidental human pathogen that acts as a natural host and environmental reservoir of other human pathogens. Tools for genetic manipulation of viruses and host were lacking. Here, we provide a detailed method for genetic manipulation of A. castellanii and the GVs it plays host to by using CRISPR-Cas9 or homologous recombination. We detail the steps of vector preparation (4 d), transfection of amoeba cells (1 h), infection (1 h), selection (5 d for viruses, 2 weeks for amoebas) and cloning of recombinant viruses (4 d) or amoebas (2 weeks). This procedure takes ~3 weeks or 1 month for the generation of recombinant viruses or amoebas, respectively. This methodology allows the generation of stable gene modifications, which was not possible by using RNA silencing, the only previously available reverse genetic tool. We also include detailed sample-preparation steps for protein localization by immunofluorescence (4 h), western blotting (4 h), quantification of viral particles by optical density (15 min), calculation of viral lethal dose 50 (7 d) and quantification of DNA replication by quantitative PCR (4 h) to allow efficient broad phenotyping of recombinant organisms. This methodology allows the function of thousands of ORFan genes present in GVs, as well as the complex pathogen-host, pathogen-pathogen or pathogen-symbiont interactions in A. castellanii, to be studied in vivo.
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Affiliation(s)
- Nadege Philippe
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), Marseille, France
| | - Avi Shukla
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), Marseille, France
| | - Chantal Abergel
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), Marseille, France.
| | - Hugo Bisio
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), Marseille, France.
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3
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Bisio H, Legendre M, Giry C, Philippe N, Alempic JM, Jeudy S, Abergel C. Evolution of giant pandoravirus revealed by CRISPR/Cas9. Nat Commun 2023; 14:428. [PMID: 36702819 PMCID: PMC9879987 DOI: 10.1038/s41467-023-36145-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 01/17/2023] [Indexed: 01/27/2023] Open
Abstract
Giant viruses (GVs) are a hotspot of unresolved controversies since their discovery, including the definition of "Virus" and their origin. While increasing knowledge of genome diversity has accumulated, GV functional genomics was largely neglected. Here, we describe an experimental framework to genetically modify nuclear GVs and their host Acanthamoeba castellanii using CRISPR/Cas9, shedding light on the evolution from small icosahedral viruses to amphora-shaped GVs. Ablation of the icosahedral major capsid protein in the phylogenetically-related mollivirus highlights a transition in virion shape and size. We additionally demonstrate the existence of a reduced core essential genome in pandoravirus, reminiscent of their proposed smaller ancestors. This proposed genetic expansion led to increased genome robustness, indicating selective pressures for adaptation to uncertain environments. Overall, we introduce new tools for manipulation of the unexplored genome of nuclear GVs and provide experimental evidence suggesting that viral gigantism has aroused as an emerging trait.
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Affiliation(s)
- Hugo Bisio
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), 13288, Marseille, Cedex 9, France.
| | - Matthieu Legendre
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), 13288, Marseille, Cedex 9, France
| | - Claire Giry
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), 13288, Marseille, Cedex 9, France
| | - Nadege Philippe
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), 13288, Marseille, Cedex 9, France
| | - Jean-Marie Alempic
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), 13288, Marseille, Cedex 9, France
| | - Sandra Jeudy
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), 13288, Marseille, Cedex 9, France
| | - Chantal Abergel
- Aix-Marseille University, Centre National de la Recherche Scientifique, Information Genomique & Structurale, Unite Mixte de Recherche 7256 (Institut de Microbiologie de la Mediterranee, FR3479, IM2B), 13288, Marseille, Cedex 9, France.
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4
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Matthey-Doret C, Colp MJ, Escoll P, Thierry A, Moreau P, Curtis B, Sahr T, Sarrasin M, Gray MW, Lang BF, Archibald JM, Buchrieser C, Koszul R. Chromosome-scale assemblies of Acanthamoeba castellanii genomes provide insights into Legionella pneumophila infection-related chromatin reorganization. Genome Res 2022; 32:1698-1710. [PMID: 36109147 PMCID: PMC9528979 DOI: 10.1101/gr.276375.121] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 07/25/2022] [Indexed: 11/24/2022]
Abstract
The unicellular amoeba Acanthamoeba castellanii is ubiquitous in aquatic environments, where it preys on bacteria. The organism also hosts bacterial endosymbionts, some of which are parasitic, including human pathogens such as Chlamydia and Legionella spp. Here we report complete, high-quality genome sequences for two extensively studied A. castellanii strains, Neff and C3. Combining long- and short-read data with Hi-C, we generated near chromosome-level assemblies for both strains with 90% of the genome contained in 29 scaffolds for the Neff strain and 31 for the C3 strain. Comparative genomics revealed strain-specific functional enrichment, most notably genes related to signal transduction in the C3 strain and to viral replication in Neff. Furthermore, we characterized the spatial organization of the A. castellanii genome and showed that it is reorganized during infection by Legionella pneumophila Infection-dependent chromatin loops were found to be enriched in genes for signal transduction and phosphorylation processes. In genomic regions where chromatin organization changed during Legionella infection, we found functional enrichment for genes associated with metabolism, organelle assembly, and cytoskeleton organization. Given Legionella infection is known to alter its host's cell cycle, to exploit the host's organelles, and to modulate the host's metabolism in its favor, these changes in chromatin organization may partly be related to mechanisms of host control during Legionella infection.
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Affiliation(s)
- Cyril Matthey-Doret
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
- Collège Doctoral, Sorbonne Université, F-75005 Paris, France
| | - Morgan J Colp
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Pedro Escoll
- Institut Pasteur, Université de Paris, Biologie des Bactéries Intracellulaires and CNRS UMR 6047, F-75015 Paris, France
| | - Agnès Thierry
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
| | - Pierrick Moreau
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
| | - Bruce Curtis
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Tobias Sahr
- Institut Pasteur, Université de Paris, Biologie des Bactéries Intracellulaires and CNRS UMR 6047, F-75015 Paris, France
| | - Matt Sarrasin
- Robert Cedergren Centre for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - Michael W Gray
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - B Franz Lang
- Robert Cedergren Centre for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | - John M Archibald
- Department of Biochemistry and Molecular Biology and Institute for Comparative Genomics, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Carmen Buchrieser
- Institut Pasteur, Université de Paris, Biologie des Bactéries Intracellulaires and CNRS UMR 6047, F-75015 Paris, France
| | - Romain Koszul
- Institut Pasteur, CNRS UMR 3525, Université de Paris, Unité Régulation Spatiale des Génomes, F-75015 Paris, France
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5
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Munyenyembe K, Timmons C, Weiner AKM, Katz LA, Yan Y. DAPI staining and DNA content estimation of nuclei in uncultivable microbial eukaryotes (Arcellinida and Ciliates). Eur J Protistol 2021; 81:125840. [PMID: 34717075 PMCID: PMC8699166 DOI: 10.1016/j.ejop.2021.125840] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 08/09/2021] [Accepted: 08/30/2021] [Indexed: 01/03/2023]
Abstract
Though representing a major component of eukaryotic biodiversity, many microbial eukaryotes remain poorly studied, including the focus of the present work, testate amoebae of the order Arcellinida (Amoebozoa) and non-model lineages of ciliates (Alveolata). In particular, knowledge of genome structures and changes in genome content over the often-complex life cycles of these lineages remains enigmatic. However, the limited available knowledge suggests that microbial eukaryotes have the potential to challenge our textbook views on eukaryotic genomes and genome evolution. In this study, we developed protocols for DAPI (4',6-diamidino-2-phenylindole) staining of Arcellinida nuclei and adapted protocols for ciliates. In addition, image analysis software was used to estimate the DNA content in the nuclei of Arcellinida and ciliates, and the measurements of target organisms were compared to those of well-known model organisms.The results demonstrate that the methods we have developed for nuclear staining in these lineages are effective and can be applied to other microbial eukaryotic groups by adjusting certain stages in the protocols.
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Affiliation(s)
- Ketty Munyenyembe
- Smith College, Department of Biological Sciences, Northampton, MA, USA
| | - Caitlin Timmons
- Smith College, Department of Biological Sciences, Northampton, MA, USA
| | - Agnes K M Weiner
- Smith College, Department of Biological Sciences, Northampton, MA, USA
| | - Laura A Katz
- Smith College, Department of Biological Sciences, Northampton, MA, USA; University of Massachusetts Amherst, Program in Organismic and Evolutionary Biology, Amherst, MA, USA.
| | - Ying Yan
- Smith College, Department of Biological Sciences, Northampton, MA, USA.
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6
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Abstract
How mitochondria shaped the evolution of eukaryotic complexity has been controversial for decades. The discovery of the Asgard archaea, which harbor close phylogenetic ties to the eukaryotes, supports the idea that a critical endosymbiosis between an archaeal host and a bacterial endosymbiont transformed the selective constraints present at the origin of eukaryotes. Cultured Asgard archaea are typically prokaryotic in both size and internal morphology, albeit featuring extensive protrusions. The acquisition of the mitochondrial predecessor by an archaeal host cell fundamentally altered the topology of genes in relation to bioenergetic membranes. Mitochondria internalised not only the bioenergetic membranes but also the genetic machinery needed for local control of oxidative phosphorylation. Gene loss from mitochondria enabled expansion of the nuclear genome, giving rise to an extreme genomic asymmetry that is ancestral to all extant eukaryotes. This genomic restructuring gave eukaryotes thousands of fold more energy availability per gene. In principle, that difference can support more and larger genes, far more non-coding DNA, greater regulatory complexity, and thousands of fold more protein synthesis per gene. These changes released eukaryotes from the bioenergetic constraints on prokaryotes, facilitating the evolution of morphological complexity.
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Affiliation(s)
- Nick Lane
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK.
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7
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Kawano-Sugaya T, Izumiyama S, Yanagawa Y, Saito-Nakano Y, Watanabe K, Kobayashi S, Nakada-Tsukui K, Nozaki T. Near-chromosome level genome assembly reveals ploidy diversity and plasticity in the intestinal protozoan parasite Entamoeba histolytica. BMC Genomics 2020; 21:813. [PMID: 33225881 PMCID: PMC7681961 DOI: 10.1186/s12864-020-07167-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 10/20/2020] [Indexed: 12/11/2022] Open
Abstract
Background Amoebozoa is a eukaryotic supergroup composed of unicellular and multicellular amoebic protozoa (e.g. Acanthamoeba, Dictyostelium, and Entamoeba). They are model organisms for studies in cellular and evolutionary biology and are of medical and veterinary importance. Despite their importance, Amoebozoan genome organization and genetic diversity remain poorly studied due to a lack of high-quality reference genomes. The slime mold Dictyostelium discoideum is the only Amoebozoan species whose genome is available at the chromosome-level. Results Here, we provide a near-chromosome-level assembly of the Entamoeba histolytica genome, the second semi-completed Amoebozoan genome. The availability of this improved genome allowed us to discover inter-strain heterogeneity in ploidy at the near-chromosome or sub-chromosome level among 11 clinical isolates and the reference strain. Furthermore, we observed ploidy-independent regulation of gene expression, contrary to what is observed in other organisms, where RNA levels are affected by ploidy. Conclusions Our findings offer new insights into Entamoeba chromosome organization, ploidy, transcriptional regulation, and inter-strain variation, which will help to further decipher observed spectrums of virulence, disease symptoms, and drug sensitivity of E. histolytica isolates. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-020-07167-9.
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Affiliation(s)
- Tetsuro Kawano-Sugaya
- Graduate School of Medicine, The University of Tokyo, Bunkyo, Tokyo, Japan.,Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Shinji Izumiyama
- Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Yasuaki Yanagawa
- AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan
| | - Yumiko Saito-Nakano
- Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Koji Watanabe
- AIDS Clinical Center, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan
| | - Seiki Kobayashi
- Department of Infectious Diseases, Keio University School of Medicine, Shinjuku, Tokyo, Japan
| | - Kumiko Nakada-Tsukui
- Graduate School of Medicine, The University of Tokyo, Bunkyo, Tokyo, Japan.,Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan
| | - Tomoyoshi Nozaki
- Graduate School of Medicine, The University of Tokyo, Bunkyo, Tokyo, Japan.
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8
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Tekle YI, Wang F, Heidari A, Stewart AJ. Differential gene expression analysis and cytological evidence reveal a sexual stage of an amoeba with multiparental cellular and nuclear fusion. PLoS One 2020; 15:e0235725. [PMID: 33147262 PMCID: PMC7641356 DOI: 10.1371/journal.pone.0235725] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/06/2020] [Indexed: 12/20/2022] Open
Abstract
Sex is a hallmark of eukaryotes but its evolution in microbial eukaryotes is poorly elucidated. Recent genomic studies revealed microbial eukaryotes possess a genetic toolkit necessary for sexual reproduction. However, the mechanism of sexual development in a majority of microbial eukaryotes including amoebozoans is poorly characterized. The major hurdle in studying sex in microbial eukaryotes is a lack of observational evidence, primarily due to its cryptic nature. In this study, we used a tractable fusing amoeba, Cochliopodium, to investigate sexual development using stage-specific Differential Gene Expression (DGE) and cytological analyses. Both DGE and cytological results showed that most of the meiosis and sex-related genes are upregulated in Cochliopodium undergoing fusion in laboratory culture. Relative gene ontology (GO) category representations in unfused and fused cells revealed a functional skew of the fused transcriptome toward DNA metabolism, nucleus and ligases that are suggestive of a commitment to sexual development. However, the GO categories of unfused cells were dominated by metabolic pathways and other processes indicative of a vegetative phase. Our study provides strong evidence that the fused cells represent a sexual stage in Cochliopodium. Our findings have further implications in understanding the evolution and mechanism of inheritance involving multiparents in other eukaryotes with a similar reproductive strategy.
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Affiliation(s)
- Yonas I. Tekle
- Department of Biology, Spelman College, Atlanta, Georgia, United States of America
- * E-mail:
| | - Fang Wang
- Department of Biology, Spelman College, Atlanta, Georgia, United States of America
| | - Alireza Heidari
- Department of Biology, Spelman College, Atlanta, Georgia, United States of America
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9
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Species, Sequence Types and Alleles: Dissecting Genetic Variation in Acanthamoeba. Pathogens 2020; 9:pathogens9070534. [PMID: 32630775 PMCID: PMC7400246 DOI: 10.3390/pathogens9070534] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 12/15/2022] Open
Abstract
Species designations within Acanthamoeba are problematic because of pleomorphic morphology. Molecular approaches, including DNA sequencing, hinted at a resolution that has yet to be fully achieved. Alternative approaches were required. In 1996, the Byers/Fuerst lab introduced the concept of sequence types. Differences between isolates of Acanthamoeba could be quantitatively assessed by comparing sequences of the nuclear 18S rRNA gene, ultimately producing 22 sequence types, designated T1 through T22. The concept of sequence types helps our understanding of Acanthamoeba evolution. Nevertheless, substantial variation in the 18S rRNA gene differentiates many isolates within each sequence type. Because the majority of isolates with sequences in the international DNA databases have been studied for only a small segment of the gene, designated ASA.S1, genetic variation within this hypervariable region of the 18S rRNA gene has been scrutinized. In 2002, we first categorized variation in this region in a sample of T3 and T4 isolates from Hong Kong, observing ten “alleles” within type T4 and five “alleles” within T3. Subsequently, confusion occurred when different labs applied redundant numerical labels to identify different alleles. A more unified approach was required. We have tabulated alleles occurring in the sequences submitted to the international DNA databases, and determined their frequencies. Over 150 alleles have occurred more than once within 3500+ isolates of sequence type T4. Results from smaller samples of other sequence types (T3, T5, T11 and T15, and supergroup T2/6) have also been obtained. Our results provide new insights into the evolutionary history of Acanthamoeba, further illuminating the degree of genetic separation between significant taxonomic units within the genus, perhaps eventually elucidating what constitutes a species of Acanthamoeba.
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10
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11
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Abstract
Sex in social amoebae (or dictyostelids) has a number of striking features. Dictyostelid zygotes do not proliferate but grow to a large size by feeding on other cells of the same species, each zygote ultimately forming a walled structure called a macrocyst. The diploid macrocyst nucleus undergoes meiosis, after which a single meiotic product survives to restart haploid vegetative growth. Meiotic recombination is generally initiated by the Spo11 enzyme, which introduces DNA double-strand breaks. Uniquely, as far as is known among sexual eukaryotes, dictyostelids lack a SPO11 gene. Despite this, recombination occurs at high frequencies during meiosis in dictyostelids, through unknown mechanisms. The molecular processes underlying these events, and the evolutionary drivers that brought them into being, may shed light on the genetic conflicts that occur within and between genomes, and how they can be resolved.
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12
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Hidalgo O, Pellicer J, Christenhusz M, Schneider H, Leitch AR, Leitch IJ. Is There an Upper Limit to Genome Size? TRENDS IN PLANT SCIENCE 2017; 22:567-573. [PMID: 28506667 DOI: 10.1016/j.tplants.2017.04.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 04/03/2017] [Accepted: 04/05/2017] [Indexed: 05/08/2023]
Abstract
At 50-fold the size of the human genome (3 Gb), the staggeringly huge genome of 147.3 Gb recently discovered in the fern Tmesipteris obliqua is comparable in size to those of the other plant and animal record-holders (i.e., Paris japonica, a flowering plant with a genome size of 148.8 Gb, and Protopterus aethiopicus, a lungfish with a genome of 130 Gb). The synthesis of available information on giant genomes suggests that the biological limit to genome size expansion in eukaryotes may have been reached. We propose several explanations for why the genomes of ferns, flowering plants, and lungfish, all of which have independently undergone dramatic increases in genome size through a variety of mechanisms, do not exceed 150 Gb.
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Affiliation(s)
| | | | | | - Harald Schneider
- Department of Life Sciences, Natural History Museum, London W7 5BD, UK; Xishuangbanna Tropical Botanical Garden, Centre for Integrative Conservation, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, PR China
| | - Andrew R Leitch
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK
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13
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Siddiqui R, Ali IKM, Cope JR, Khan NA. Biology and pathogenesis of Naegleria fowleri. Acta Trop 2016; 164:375-394. [PMID: 27616699 DOI: 10.1016/j.actatropica.2016.09.009] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/06/2016] [Accepted: 09/06/2016] [Indexed: 12/13/2022]
Abstract
Naegleria fowleri is a protist pathogen that can cause lethal brain infection. Despite decades of research, the mortality rate related with primary amoebic meningoencephalitis owing to N. fowleri remains more than 90%. The amoebae pass through the nose to enter the central nervous system killing the host within days, making it one of the deadliest opportunistic parasites. Accordingly, we present an up to date review of the biology and pathogenesis of N. fowleri and discuss needs for future research against this fatal infection.
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Asexual Amoebae Escape Muller's Ratchet through Polyploidy. Trends Parasitol 2016; 32:855-862. [PMID: 27599632 DOI: 10.1016/j.pt.2016.08.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 08/05/2016] [Accepted: 08/08/2016] [Indexed: 11/23/2022]
Abstract
While some amoebae reproduce sexually, many amoebae (e.g., Acanthamoeba, Naegleria) reproduce asexually and therefore, according to popular doctrine, are likely to have been genetically disadvantaged as a consequence. In the absence of sex, mutations are proposed to accumulate by a mechanism known as Muller's ratchet. I hypothesise that amoebae can escape the ravages of accumulated mutation by virtue of their being polyploid. The polyploid state reduces spontaneous mutation accumulation by gene conversion, the freshly mutated copy being corrected by the presence of the many other wild-type copies. In this manner these amoebae reap the benefits of an asexual reproductive existence: principally, that it is rapid and convenient. Evidence for this mechanism comes from polyploid plants, bacteria, and archaea.
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15
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Bloomfield G. Atypical ploidy cycles, Spo11, and the evolution of meiosis. Semin Cell Dev Biol 2016; 54:158-64. [PMID: 26811992 DOI: 10.1016/j.semcdb.2016.01.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 01/20/2016] [Indexed: 12/14/2022]
Abstract
The Spo11 protein induces DNA double strand breaks before the first division of meiosis, enabling the formation of the chiasmata that physically link homologous chromosomes as they align. Spo11 is an ancient and well conserved protein, related in sequence and structure to a DNA topoisomerase subunit found in Archaea as well as a subset of eukaryotes. However the origins of its meiotic function are unclear. This review examines some apparent exceptions to the rule that Spo11 activity is specific to, and required for meiosis. Spo11 appears to function in the context of unusual forms of ploidy reduction in some protists and fungi. One lineage of amoebae, the dictyostelids, is thought to undergo meiosis during its sexual cycle despite having lost Spo11 entirely. Further experimental characterisation of these and other non-canonical ploidy cycling mechanisms may cast light of the evolution of meiosis.
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Affiliation(s)
- Gareth Bloomfield
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, United Kingdom.
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16
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Santos SS, Nielsen TK, Hansen LH, Winding A. Comparison of three DNA extraction methods for recovery of soil protist DNA. J Microbiol Methods 2015; 115:13-9. [PMID: 25966645 DOI: 10.1016/j.mimet.2015.05.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 04/30/2015] [Accepted: 05/07/2015] [Indexed: 11/24/2022]
Abstract
The use of molecular methods to investigate protist communities in soil is in rapid development this decade. Molecular analysis of soil protist communities is usually dependant on direct genomic DNA extraction from soil and inefficient or differential DNA extraction of protist DNA can lead to bias in downstream community analysis. Three commonly used soil DNA extraction methods have been tested on soil samples from three European Long-Term Observatories (LTOs) with different land-use and three protist cultures belonging to different phylogenetic groups in different growth stages. The methods tested were: ISOm-11063 (a version of the ISO-11063 method modified to include a FastPrep ®-24 mechanical lysis step), GnS-GII (developed by the GenoSol platform to extract soil DNA in large-scale soil surveys) and a commercial DNA extraction kit - Power Lyzer™ PowerSoil® DNA Isolation Kit (MoBio). DNA yield and quality were evaluated along with DNA suitability for amplification of 18S rDNA fragments by PCR. On soil samples, ISOm-11063 yields significantly higher DNA for two of the three soil samples, however, MoBio extraction favors DNA quality. This method was also more effective to recover copies of 18S rDNA numbers from all soil types. In addition and despite the lower yields, higher DNA quality was observed with DNA extracted from protist cultures with the MoBio method. Likewise, a bead-beating step shows to be a good solution for DNA extraction of soil protists, since the recovery of DNA from protist cultures and from the different soil samples with the ISOm method proved to be efficient in recovering PCR-amplifiable DNA. This study showed that soil DNA extraction methods provide biased results towards the cyst stages of protist organism.
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Affiliation(s)
- Susana S Santos
- Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Tue Kjærgaard Nielsen
- Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Lars H Hansen
- Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Anne Winding
- Department of Environmental Science, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
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Roberts CW, Henriquez FL. Drug target identification, validation, characterisation and exploitation for treatment of Acanthamoeba (species) infections. Exp Parasitol 2009; 126:91-6. [PMID: 20035751 DOI: 10.1016/j.exppara.2009.11.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 11/19/2009] [Accepted: 11/30/2009] [Indexed: 12/15/2022]
Abstract
New more efficacious antimicrobials as required for the treatment of Acanthamoeba infections as those currently available require arduous treatment regimes, are not always effective and are poorly active against the cystic stages. Herein, we review potential drug targets including tubulin, alternative oxidase, amino acid biosynthesis and myosin. In addition, we review the literature for current missing tools and resources for the identification, validation and development of new antimicrobials for this organism. Additional targets should come to light through a concerted genome sequencing effort.
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Affiliation(s)
- Craig W Roberts
- Strathclyde Institute for Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow G4 0NR, UK
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18
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Matsunaga S, Endo T, Yagita K, Hirukawa Y, Tomino S, Matsugo S, Tsuruhara T. Chromosome size polymorphisms in the genus acanthamoeba electrokaryotype by pulsed-field gel electrophoresis. Protist 2009. [PMID: 23194715 DOI: 10.1016/s1434-4610(98)70039-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Twenty-eight strains from 12 species from the genus Acanthamoeba, including five isolates from amoebic keratitis patients, were subjected to molecular karyotyping by pulsed-field gel electrophoresis. 9 to 21 chromosome-sized DNA bands ranging from 200 kb to 3 Mb in size were detected. Molecular karyotypes also showed a wide multifariousness, i.e. there existed inter- and intraspecific heterogeneity. The five isolates from amoebic keratitis patients did not exhibit characteristic molecular karyotypes distinguishable from environmental isolates. Although karyotypic heterogeneity was observed within group I amoeba, they are distinguishable from those of group II and III. Strains having identical restriction fragment length polymorphism profiles of mtDNA did not have an identical molecular karyotype, i.e. weak correlation was found between molecular karyotypes and mtDNA restriction fragment length polymorphism profiles.
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Affiliation(s)
- S Matsunaga
- Department of Biology, Tokyo Gakugei University, Koganei-shi, Tokyo 184-8501, Japan
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19
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Kiderlen AF, Radam E, Lewin A. Detection of Balamuthia mandrillaris DNA by real-time PCR targeting the RNase P gene. BMC Microbiol 2008; 8:210. [PMID: 19055756 PMCID: PMC2612680 DOI: 10.1186/1471-2180-8-210] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 12/03/2008] [Indexed: 12/27/2022] Open
Abstract
Background The free-living amoeba Balamuthia mandrillaris may cause fatal encephalitis both in immunocompromised and in – apparently – immunocompetent humans and other mammalian species. Rapid, specific, sensitive, and reliable detection requiring little pathogen-specific expertise is an absolute prerequisite for a successful therapy and a welcome tool for both experimental and epidemiological research. Results A real-time polymerase chain reaction assay using TaqMan® probes (real-time PCR) was established specifically targeting the RNase P gene of B. mandrillaris amoebae. The assay detected at least 2 (down to 0.5) genomes of B. mandrillaris grown in axenic culture. It did not react with DNA from closely related Acanthamoeba (3 species), nor with DNA from Toxoplasma gondii, Leishmania major, Pneumocystis murina, Mycobacterium bovis (BCG), human brain, various mouse organs, or from human and murine cell lines. The assay efficiently detected B. mandrillaris DNA in spiked cell cultures, spiked murine organ homogenates, B. mandrillaris-infected mice, and CNS tissue-DNA preparations from 2 patients with proven cerebral balamuthiasis. This novel primer set was successfully combined with a published set that targets the B. mandrillaris 18S rRNA gene in a duplex real-time PCR assay to ensure maximum specificity and as a precaution against false negative results. Conclusion A real-time PCR assay for B. mandrillaris amoebae is presented, that is highly specific, sensitive, and reliable and thus suited both for diagnosis and for research.
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Affiliation(s)
- Albrecht F Kiderlen
- Robert Koch Institute, Cellular Immunology Unit P22, Nordufer 20, 13353 Berlin, Germany.
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20
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Watkins RF, Gray MW. Sampling gene diversity across the supergroup Amoebozoa: large EST data sets from Acanthamoeba castellanii, Hartmannella vermiformis, Physarum polycephalum, Hyperamoeba dachnaya and Hyperamoeba sp. Protist 2008; 159:269-81. [PMID: 18276190 DOI: 10.1016/j.protis.2007.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 12/15/2007] [Indexed: 10/22/2022]
Abstract
From comparative analysis of EST data for five taxa within the eukaryotic supergroup Amoebozoa, including two free-living amoebae (Acanthamoeba castellanii, Hartmannella vermiformis) and three slime molds (Physarum polycephalum, Hyperamoeba dachnaya and Hyperamoeba sp.), we obtained new broad-range perspectives on the evolution and biosynthetic capacity of this assemblage. Together with genome sequences for the amoebozoans Dictyostelium discoideum and Entamoeba histolytica, and including partial genome sequence available for A. castellanii, we used the EST data to identify genes that appear to be exclusive to the supergroup, and to specific clades therein. Many of these genes are likely involved in cell-cell communication or differentiation. In examining on a broad scale a number of characters that previously have been considered in simpler cross-species comparisons, typically between Dictyostelium and Entamoeba, we find that Amoebozoa as a whole exhibits striking variation in the number and distribution of biosynthetic pathways, for example, ones for certain critical stress-response molecules, including trehalose and mannitol. Finally, we report additional compelling cases of lateral gene transfer within Amoebozoa, further emphasizing that although this process has influenced genome evolution in all examined amoebozoan taxa, it has done so to a variable extent.
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Affiliation(s)
- Russell F Watkins
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5
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21
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GICQUAUD CLAUDE, TREMBLAY NADINE. Observations with Hoechst Staining of Amitosis inAcanthamoeba castellanii. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1991.tb04432.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Ruhaya Abd S, . SM, . NMA, . AMA. Genetic Relatedness Among Isolates of Acanthamoeba Based on RAPD Analysis. JOURNAL OF APPLIED SCIENCES 2005; 6:15-19. [DOI: 10.3923/jas.2006.15.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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23
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Rivière D, Szczebara FM, Berjeaud JM, Frère J, Héchard Y. Development of a real-time PCR assay for quantification of Acanthamoeba trophozoites and cysts. J Microbiol Methods 2005; 64:78-83. [PMID: 15923051 DOI: 10.1016/j.mimet.2005.04.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Revised: 03/30/2005] [Accepted: 04/11/2005] [Indexed: 10/25/2022]
Abstract
Free-living amoebae have been found to be a reservoir for various pathogenic bacteria in aquatic environments. For example, the Acanthamoeba genus renders possible the intracellular multiplication of Legionella pneumophila, which is responsible for legionellosis. It consequently matters to quantify Acanthamoeba cells and thereby enhance our assessment of the risk of contamination. The classical microbiological method of quantification relies on amoebae growth and most probable number calculation. We have developed a real-time PCR assay based on a TaqMan probe that hybridizes onto 18S rDNA. This probe is specific to the Acanthamoeba genus. The assay was successful with both the trophozoite and the cyst forms of Acanthamoeba. Highly sensitive, it proved to permit detection of fewer than 10 cells, even those that are not easily cultivable, such as the cyst forms.
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Affiliation(s)
- Delphine Rivière
- Equipe de Microbiologie, Laboratoire de Chimie de l'Eau et de l'Environnement, UMR CNRS 6008, Université de Poitiers, 40 avenue du recteur Pineau, 86022 Poitiers, France
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24
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Peng Z, Omaruddin R, Bateman E. Stable transfection of Acanthamoeba castellanii. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1743:93-100. [PMID: 15777844 DOI: 10.1016/j.bbamcr.2004.08.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2004] [Revised: 08/23/2004] [Accepted: 08/24/2004] [Indexed: 11/16/2022]
Abstract
A simple method for stable transfection of Acanthamoeba castellanii using plasmids which confer resistance to neomycin G418 is described. Expression of neomycin phosphotransferase is driven by the Acanthamoeba TBP gene promoter, and can be monitored by cell growth in the presence of neomycin G418 or by Western blot analysis. Transfected cells can be passaged in the same manner as control cells and can be induced to differentiate into cysts, in which form they maintain resistance to neomycin G418 for at least several weeks, although expression of neomycin phosphotransferase is repressed during encystment. Expression of EGFP or an HA-tagged EGFP-TBP fusion can be driven from the same plasmid, using an additional copy of the Acanthamoeba TBP gene promoter or a deletion mutant. The TBP-EGFP fusion is localized to the nucleus, except in a small proportion of presumptive pre-mitotic cells. EGFP expression can also be driven by the cyst-specific CSP21 gene promoter, which is completely repressed in growing cells but strongly induced in differentiating cells. Transfected cells maintain their phenotype for several weeks, even in the absence of neomycin G418, suggesting that transfected genes are stably integrated within the genome. These results demonstrate the utility of the neomycin resistance based plasmids for stable transfection of Acanthamoeba, and may assist a number of investigations.
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Affiliation(s)
- Zhihua Peng
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington VT 05405, USA
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25
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Byers J, Eichinger D. Entamoeba invadens: restriction of ploidy by colonic short chain fatty acids. Exp Parasitol 2005; 110:203-6. [PMID: 15955313 DOI: 10.1016/j.exppara.2005.02.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Revised: 02/21/2005] [Accepted: 02/23/2005] [Indexed: 10/25/2022]
Abstract
The DNA content of Entamoeba parasites appears to be regulated by an unusual mechanism. This conclusion, however, was based on experiments that examined parasites grown in media that did not contain short chain fatty acids (SCFAs) normally found in the colonic lumen. Since one of these SCFAs, butyrate, is known to affect DNA replication in eukaryotic cells, we examined the effect of SCFAs on Entamoeba trophozoite DNA content. Similar to reports from others, we found that Entamoeba invadens trophozoite cultures grown in conventional medium (TYI-S-33) contained cells with 2N, 4N, 8N, and 16N amounts of DNA. In contrast, cultures grown in TYI medium containing colonic SCFAs added in place of glucose contained a minor population with 2N, a major population with 4N, and very few cells with higher amounts of DNA. SCFAs also prevented the normal increase in the number of nuclei per cell in trophozoites that were induced to encyst. These results suggest that E. invadens trophozoite stage parasites growing in the intestine in the presence of high amounts of SCFAs have a ploidy range restricted to 2N/4N. Axenic growth of trophozoites in the absence of SCFAs, however, appears to allow trophozoites to increase the amount of DNA per cell, which they must do during the normal encystment process.
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Affiliation(s)
- Jennifer Byers
- Department of Medical Parasitology, New York University School of Medicine, New York, NY 10010, USA
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26
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Vinogradov AE. Genome size and chromatin condensation in vertebrates. Chromosoma 2005; 113:362-9. [PMID: 15647899 DOI: 10.1007/s00412-004-0323-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Revised: 10/05/2004] [Accepted: 10/25/2004] [Indexed: 10/26/2022]
Abstract
Cell membrane-dependent chromatin condensation was studied by flow cytometry in erythrocytes of 36 species from six classes of vertebrates. A positive relationship was found between the degree of condensation and genome size. The distribution of variances among taxonomic levels is similar for both parameters. However, chromatin condensation varied relatively more at the lower taxonomic levels, which suggests that the degree of DNA packaging might serve for fine-tuning the 'skeletal' and/or 'buffering' function of noncoding DNA (although the range of this fine-tuning is smaller than the range of genome size changes). For two closely related amphibian species differing in genome size, change in chromatin condensation under the action of elevated extracellular salinity was investigated. Condensation was steadier and its reaction to changes in solvent composition was more inertial in the species with a larger genome, which is in agreement with the buffering function postulated for redundant DNA. The uppermost genome size in vertebrates (and in living beings in general) was updated using flow cytometry and was found to be about 80 pg (78,400 Mb). The widespread opinion that the largest genome occurs in unicellular organisms is rejected as being based on artifacts.
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Affiliation(s)
- Alexander E Vinogradov
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave. 4, St. Petersburg, 194064, Russia.
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27
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Chen L, Orfeo T, Gilmartin G, Bateman E. Mechanism of cyst specific protein 21 mRNA induction during Acanthamoeba differentiation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1691:23-31. [PMID: 15053921 DOI: 10.1016/j.bbamcr.2003.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2003] [Revised: 10/30/2003] [Accepted: 11/14/2003] [Indexed: 11/20/2022]
Abstract
The Acanthamoeba cyst specific protein 21 (CSP21) gene is tightly repressed in growing cells and highly induced early during differentiation into a dormant cyst. This increase is mediated by the rate of transcription of the CSP21 gene as determined by nuclear run-on assays. The promoter region of the CSP21 gene was analyzed by transcript start site mapping and in vitro transcription of wild-type or mutant templates, using extracts from growing cells. A sequence located 3' to a modified TATA box completely inhibits transcription and removal of this region permits robust transcription utilizing a start site approximately 35 base pairs downstream of the TATA box. Sequences 5' to the TATA box had no effect on transcription, suggesting that anti-repression is the only mechanism required for CSP21 induction. Fractionation of nuclear extracts yielded a fraction capable of transcription from the CSP21 promoter, and a fraction containing a promoter-specific repressing activity. Anti-repression may thus be a major mechanism regulating differentiation or maintenance of the proliferative cycle in Acanthamoeba.
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Affiliation(s)
- Li Chen
- Department of Microbiology and Molecular Genetics, Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
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28
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Schroeder JM, Booton GC, Hay J, Niszl IA, Seal DV, Markus MB, Fuerst PA, Byers TJ. Use of subgenic 18S ribosomal DNA PCR and sequencing for genus and genotype identification of acanthamoebae from humans with keratitis and from sewage sludge. J Clin Microbiol 2001; 39:1903-11. [PMID: 11326011 PMCID: PMC88046 DOI: 10.1128/jcm.39.5.1903-1911.2001] [Citation(s) in RCA: 398] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study identified subgenic PCR amplimers from 18S rDNA that were (i) highly specific for the genus Acanthamoeba, (ii) obtainable from all known genotypes, and (iii) useful for identification of individual genotypes. A 423- to 551-bp Acanthamoeba-specific amplimer ASA.S1 obtained with primers JDP1 and JDP2 was the most reliable for purposes i and ii. A variable region within this amplimer also identified genotype clusters, but purpose iii was best achieved with sequencing of the genotype-specific amplimer GTSA.B1. Because this amplimer could be obtained from any eukaryote, axenic Acanthamoeba cultures were required for its study. GTSA.B1, produced with primers CRN5 and 1137, extended between reference bp 1 and 1475. Genotypic identification relied on three segments: bp 178 to 355, 705 to 926, and 1175 to 1379. ASA.S1 was obtained from single amoeba, from cultures of all known 18S rDNA genotypes, and from corneal scrapings of Scottish patients with suspected Acanthamoeba keratitis (AK). The AK PCR findings were consistent with culture results for 11 of 15 culture-positive specimens and detected Acanthamoeba in one of nine culture-negative specimens. ASA.S1 sequences were examined for 6 of the 11 culture-positive isolates and were most closely associated with genotypic cluster T3-T4-T11. A similar distance analysis using GTSA.B1 sequences identified nine South African AK-associated isolates as genotype T4 and three isolates from sewage sludge as genotype T5. Our results demonstrate the usefulness of 18S ribosomal DNA PCR amplimers ASA.S1 and GTSA.B1 for Acanthamoeba-specific detection and reliable genotyping, respectively, and provide further evidence that T4 is the predominant genotype in AK.
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Affiliation(s)
- J M Schroeder
- Department of Molecular Genetics, The Ohio State University, 484 W. 12th Ave., Columbus, OH 43210, USA
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29
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Willhoeft U, Tannich E. Fluorescence microscopy and fluorescence in situ hybridization of Entamoeba histolytica nuclei to analyse mitosis and the localization of repetitive DNA. Mol Biochem Parasitol 2000; 105:291-6. [PMID: 10693751 DOI: 10.1016/s0166-6851(99)00181-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- U Willhoeft
- Bernhard-Nocht-Institute for Tropical Medicine, Hamburg, Germany.
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30
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Orfeo T, Chen L, Huang W, Ward G, Bateman E. Distamycin A selectively inhibits Acanthamoeba RNA synthesis and differentiation. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1446:273-85. [PMID: 10524202 DOI: 10.1016/s0167-4781(99)00076-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The effects of distamycin A on Acanthamoeba transcription, growth and differentiation were determined. Distamycin A inhibits transcription both in vitro and in vivo and can displace from DNA the transcription activator TATA binding protein promoter binding factor (TPBF). Inhibition in vivo is surprisingly selective for large rRNA precursors, 5S rRNA, profilin, S-adenosylmethionine synthetase, and extendin. Transcription from the TATA binding protein (TBP), TPBF, protein disulfide isomerase, tubulin and RNA polymerase II large subunit genes is only slightly inhibited. Moreover the rate of 5S rRNA transcription eventually recovers and exceeds that of untreated cells, while profilin transcription remains inhibited. Distamycin A inhibition is accompanied by a complex pattern of alterations to steady state levels of mRNAs. Actin, profilin and S-adenosylmethionine synthetase mRNAs are degraded, whereas mRNA encoding TBP is increased slightly in abundance. Transcription inhibition is accompanied by cessation of growth and severe morphological changes to Acanthamoeba, which are consistent with loss of production of mRNA encoding cytoskeletal proteins. Distamycin A also prevents starvation-induced differentiation of Acanthamoeba, in part due to complete prevention of cellulose production and cell wall formation.
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Affiliation(s)
- T Orfeo
- Department of Microbiology and Molecular Genetics, Markey Center for Molecular Genetics, University of Vermont, Burlington 05405, USA
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31
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Orfeo T, Bateman E. Transcription by RNA polymerase II during Acanthamoeba differentiation. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1443:297-304. [PMID: 9878798 DOI: 10.1016/s0167-4781(98)00227-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The rates of transcription of several protein coding genes during Acanthamoeba differentiation have been examined by nuclear run-on and RNase protection assays. During early encystment, transcription by RNA polymerase II increases approximately 4-fold, whereas transcription by RNA polymerases I and III is decreased, as previously described. The rates of transcription from a wide variety of individual genes are only slightly affected during the first 16 h of encystment, although profilin gene expression is markedly increased. The levels of mRNAs encoding TPBF, TATA binding protein, cyclin-dependent kinase, protein disulfide isomerase, profilin, myosin II heavy chain, ubiquitin and extendin are stable during mature cyst formation, whereas mRNAs encoding actin, S-adenosyl methionine synthase and tubulin are substantially decreased in abundance within 16 h of starvation-induced encystment. We conclude that in contrast to the negative regulation of large rRNA and 5S rRNA synthesis during differentiation, the RNA polymerase II transcription apparatus is not negatively regulated. Control of Acanthamoeba differentiation is likely to be mediated by positive regulation of genes necessary for cyst maturation.
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Affiliation(s)
- T Orfeo
- Department of Microbiology and Molecular Genetics, Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
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Nozaki T, Asai T, Kobayashi S, Ikegami F, Noji M, Saito K, Takeuchi T. Molecular cloning and characterization of the genes encoding two isoforms of cysteine synthase in the enteric protozoan parasite Entamoeba histolytica. Mol Biochem Parasitol 1998; 97:33-44. [PMID: 9879885 DOI: 10.1016/s0166-6851(98)00129-7] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The enteric protozoan parasite Entamoeba histolytica was shown to possess cysteine synthase (CS) activity. The cDNA and genomic clones that encode two isoforms of the E. histolytica CS were isolated and characterized from a clonal strain of E. histolytica by genetic complementation of the cysteine-auxotrophic Escherichia coli NK3 with an E. histolytica cDNA library. The two types of the E. histolytica CS genes differed from each other by three nucleotides, two of which resulted in amino acid substitution. Deduced amino acid sequences of the E. histolytica CS, with a calculated molecular mass of 36721 Da and an isoelectric point of 6.39, exhibited 38-48% identity with CS of bacterial and plant origins. The absence of the amino-terminal transit peptide in the deduced protein sequences and the presence of the CS protein mainly in the supernatant fraction of the amoebic lysate after cellular fractionation suggested that the identified E. histolytica CS genes encoded cytosolic isoforms. Substrate specificity of the recombinant E. histolytica CS was similar to that of plant CS. Phylogenetic analysis indicates that the amoebic CS, first described in Protozoa, does not belong to any families of the CS superfamily, and represents a new family.
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Affiliation(s)
- T Nozaki
- Department of Tropical Medicine and Parasitology, Keio University, School of Medicine, Tokyo, Japan.
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Ray SS, Gangopadhyay SS, Pande G, Samuelson J, Lohia A. Primary structure of Entamoeba histolytica gamma-tubulin and localisation of amoebic microtubule organising centres. Mol Biochem Parasitol 1997; 90:331-6. [PMID: 9497056 DOI: 10.1016/s0166-6851(97)00157-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- S S Ray
- Department of Biochemistry, Bose Institute, Calcutta, India
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Gangopadhyay SS, Ray SS, Kennady K, Pande G, Lohia A. Heterogeneity of DNA content and expression of cell cycle genes in axenically growing Entamoeba histolytica HM1:IMSS clone A. Mol Biochem Parasitol 1997; 90:9-20. [PMID: 9497028 DOI: 10.1016/s0166-6851(97)00156-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The cell division cycle of Entamoeba histolytica was studied using multi-parametric flow cytometry in asynchronous and partially synchronised cells. Dynamic changes in the DNA synthesis and DNA content of axenically growing trophozoites were observed by using 5-bromo-2'-deoxyuridine (BrdU) uptake and DNA specific fluorochromes. It was observed that DNA synthesis in these cells continues beyond the typical S-phase stop point when DNA duplication is complete. Asynchronously growing E. histolytica cells could be synchronised by serum starvation followed by serum re-addition. BrdU incorporation in synchronised cells showed that cell synchrony is maintained for at least one generation time, in which the G1 phase lasts for 2-3 h and the S-phase lasts for 5-6 h. Analysis of our results revealed that E. histolytica trophozoites, growing in axenic medium, are made up of a heterogenous population of euploid and polyploid cells. The number of polyploid cells increases with age of the cells in culture. Expression of putative cell cycle and signal transduction markers was studied using specific antibodies and changes in their expression levels have been correlated with changes in the DNA content. Based upon our results we could identify G1, S and G2 phases of the cell cycle of E. histolytica and also predict the mechanism underlying the generation of polyploidy in these cells, which may have significant effects on its biology and pathogenesis.
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Tanaka T, Tanaka M, Mitsui Y. Analysis of expressed sequence tags (ESTs) of the parasitic protozoa Entamoeba histolytica. Biochem Biophys Res Commun 1997; 236:611-5. [PMID: 9245698 DOI: 10.1006/bbrc.1997.7019] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A directional cDNA library constructed from mRNA of the trophozoite of Entamoeba histolytica HM-1:IMSS strain was used for the generation of expressed sequence tags (ESTs). From 5' ends of the distinct cDNA clones, 105 ESTs were obtained. Of these, 30 clones (29%) were previously known E. histolytica genes. Forty-five clones (42%) had matches with entries for other organisms in the databases. These new E. histolytica genes constituted a broad range of transcripts distributed among cytoplasmic structural and regulatory proteins, enzymes, nuclear and other proteins, and proteins of unknown function. Thirty clones (29%) had no significant database matches and thus potentially represent E. histolytica-specific genes. These data of E. histolytica genes identified by nucleotide sequencing indicate the value of the adoption of genome sequencing strategies for the rapid increase in knowledge of organisms causing dysentery and liver abscess.
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Affiliation(s)
- T Tanaka
- Division of Host Defense Mechanism, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
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36
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Ahearn DG, Gabriel MM. Contact lenses, disinfectants, and Acanthamoeba keratitis. ADVANCES IN APPLIED MICROBIOLOGY 1997; 43:35-56. [PMID: 9097411 DOI: 10.1016/s0065-2164(08)70222-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- D G Ahearn
- Department of Biology, Georgia State University, Atlanta 30302-4010, USA
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37
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Abstract
Advancements in our understanding of amebiasis have been rapid over the decade that I have followed this field. What was identified morphologically for years as Entamoeba histolytica has been redescribed with modern techniques as a complex of two species, the commensal parasite E. dispar and the pathogenic parasite E. histolytica that is the cause of colitis and liver abscess. Antigen detection tests are now available for the rapid detection in stool of the pathogenic species E. histolytica. New understandings of the importance of luminal as well as tissue-active antimebic medications in the treatment of invasive disease have been reached. The groundwork is being laid for an understanding of the protective immune responses to infection, and at the lab bench DNA transfection of the parasite has opened studies of pathogenesis to genetic analysis. While necessarily an incomplete sketch of the field, I have attempted here to highlight some recent and important developments of interest to clinicians and microbiologists.
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Affiliation(s)
- W A Petri
- Department of Internal Medicine, University of Virginia, Charlottesville 22908, USA
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Dvorak JA, Kobayashi S, Alling DW, Hallahan CW. Elucidation of the DNA synthetic cycle of Entamoeba spp. using flow cytometry and mathematical modeling. J Eukaryot Microbiol 1995; 42:610-6. [PMID: 7581336 DOI: 10.1111/j.1550-7408.1995.tb05915.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We developed a method to study the DNA synthetic cycles of Entamoeba histolytica and Entamoeba invadens by flow cytometry (FCM) based on a preparative procedure to reduce both high levels of natural fluorescence and non-specific adsorption of fluorochromes. We modeled G1, S, and G2 phases as a series of overlapping Gaussian curves. Both E. histolytica and E. invadens displayed G1, S, and G2 proportions that are consistent with eukaryotic cell populations in exponential or stationary growth phase. Exponential phase E. histolytica populations contained a hypodiploid subset with a mass of about 20% less than the diploid value which we estimate by FCM to be 24 x 10(-14) g DNA/cell. Exponential phase E. invadens populations contained a hypodiploid subset with a mass of about 6% less than the diploid value which we estimate by FCM to be 30 x 10(-14) g DNA/cell.
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Affiliation(s)
- J A Dvorak
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0425, USA
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Abstract
Sex involves syngamy (gamete fusion), which doubles the amount of DNA in a cell, and meiosis, which halves it. The result is a 'ploidy cycle' of alternating diploid and haploid phases. Asexual reproduction does not require changes of ploidy, and yet asexual forms may have ploidy cycles. Here I show that such cycles lessen the mutation load, compared with permanent diploidy or polyploidy, and are thus likely to evolve in cases where it is always advantageous to have more than one copy of the genome per cell. The asexual ploidy cycle could have facilitated the origin of sex, by providing a means of orderly genetic reduction available immediately after the origin of syngamy.
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Affiliation(s)
- A S Kondrashov
- Section of Ecology and Systematics, Cornell University, Ithaca, New York 14853
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41
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Purification and characterization of TATA-binding protein promoter binding factor. A regulatory transcription factor of the tbp gene. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32343-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Vodkin MH, Gordon VR, McLaughlin GL. A ribosomal protein in Acanthamoeba polyphaga is conserved in eukaryotic nuclei, organelles and bacteria. Gene 1993; 131:141-4. [PMID: 8370534 DOI: 10.1016/0378-1119(93)90683-t] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
An EcoRI fragment from the mitochondrial DNA of Acanthamoeba polyphaga was cloned and partly sequenced, and the conceptual translation product of the open reading frame (partial sequence) was found to have similarities with rp114, a ribosomal protein. Phylogenetic analysis based on the amino acid (aa) sequences of this conserved protein resolved four branches that consisted of: (1) eubacteria and the chloroplasts of algae and higher plants, (2) ciliate mitochondria, (3) Acanthamoeba, and (4) archaebacteria and the nuclei of eukaryotes. The groupings based on the rp114 aa sequences were consistent with the phylogenies derived by rRNA analysis of these organisms.
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Affiliation(s)
- M H Vodkin
- Department of Veterinary Pathobiology, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907
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Abstract
After more than 70 years of intermittent debate over the true relationship between the 'pathogenic' and 'non-pathogenic' forms of Entamoeba histolytica, the application of molecular biology has finally yielded an unambiguous answer: these are not interconvertible phenotypes of the same parasite, a kind of unicellular Jekyll and Hyde, but two quite distinct genetic entities that just happen to look the same. But given the overwhelming evidence now available from gene sequences, pointing to an evolutionary divergence some tens of millions of years ago, why is it that certain eminent workers in the field are still claiming that, at least in vitro, conversion between the two phenotypes can take place? In this article Bill Spice and John Ackers review recent developments in the molecular biology of E. histolytica and assess the continuing controversy over the status of this enigmatic parasite.
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Affiliation(s)
- W M Spice
- Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK
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Wong JM, Liu F, Bateman E. Isolation of genomic DNA encoding transcription factor TFIID from Acanthamoeba castellanii: characterization of the promoter. Nucleic Acids Res 1992; 20:4817-24. [PMID: 1408796 PMCID: PMC334237 DOI: 10.1093/nar/20.18.4817] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We have isolated a genomic clone encoding Acanthamoeba castellanii TFIID. The clone contains the entire TFIID gene, 300 bp of 5' promoter sequences and several hundred base pairs of 3' non-coding sequence. The coding region is interrupted by two short introns, but is otherwise identical to Acanthamoeba TFIID cDNA. Comparisons between forty four Acanthamoeba intron 5' and 3' boundaries suggest a 5' splice site consensus of GTACG(T/C) and a 3' consensus of CAG. We determined the position of the transcription initiation site used in vivo, and show that the same site is used in vitro by homologous nuclear extracts. Deletion analysis of the promoter region shows that the minimal promoter required for efficient expression in vitro is located between -97 and +4 relative to the transcription start site. Three regions within the promoter are important for transcription in vitro; sequences between -97 and -35, the TATAAA box and the initiation region. The initiation region is dispensable but appears to position the transcription start site relative to the TATAAA box. The TATAAA box is absolutely required for transcription initiation whereas the upstream region stimulates transcription approximately five-fold.
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Affiliation(s)
- J M Wong
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington 05405-0068
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Wong JM, Liu F, Bateman E. Cloning and expression of the Acanthamoeba castellanii gene encoding transcription factor TFIID. Gene X 1992; 117:91-7. [PMID: 1339370 DOI: 10.1016/0378-1119(92)90494-a] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
We have cloned and characterized the cDNA encoding transcription factor TFIID from the eukaryote, Acanthamoeba castellanii. The gene occurs as a single species, encodes one mRNA and, presumably, a single protein. A. castellanii TFIID contains two recognizable domains, a nonconserved N-terminal domain and a highly conserved C-terminal domain. Similarities between the amino acid (aa) sequences of TFIID from several organisms are also found within the N-terminal 78 aa, suggesting a potential role in TFIID function. Full-length or truncated A. castellanii TFIID produced in Escherichia coli binds to a TATA box and is able to activate transcription in a TFIID-depleted HeLa cell extract, but the C-terminal 180-aa domain was found to be less efficient in these reactions.
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Affiliation(s)
- J M Wong
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington 05405-0068
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Abstract
The chromatin structure of Entamoeba histolytica was investigated. It was found that this protozoan organizes its chromatin in nucleosome-like particles 10 nm in diameter, but digestion of the chromatin with micrococcal nuclease did not render a regularly spaced DNA ladder in agarose gels. Southern blot analysis of the products of Entamoeba chromatin digestion using total amebic DNA and a non-transcribed repetitive sequence produced a banding pattern characteristic of eukaryotic chromatin with a repetitive size of approximately 130 bp. Conversely, hybridization with two active gene probes, actin and ribosomal RNA, showed that these sequences are not part of the chromatin organized in nucleosomes. It was also found that the basic nuclear proteins differ from histones of higher eukaryotes in electrophoretic mobility. Screening of an E. histolytica HM1-IMSS genomic library with Saccharomyces cerevisiae H3 and H4 genes and attempts to amplify E. histolytica sequences, homologous to these yeast histone genes, gave negative results suggesting that the Entamoeba proteins involved in chromatin organization are not typical histones.
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Affiliation(s)
- H Torres-Guerrero
- Departamento de Biologia Celular, CINVESTAV-IPN, Mexico City, Mexico
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Byers TJ, Hugo ER, Stewart VJ. Genes of Acanthamoeba: DNA, RNA and protein sequences (a review). THE JOURNAL OF PROTOZOOLOGY 1990; 37:17S-25S. [PMID: 1701831 DOI: 10.1111/j.1550-7408.1990.tb01141.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This review summarizes knowledge about the structure of nuclear genes and mitochondrial DNA in Acanthamoeba. The information about nuclear genes is derived from studies of DNA, RNA and protein sequences. The genes considered are those for 5S, 5.8S and 18S rRNA, actin I, profilins Ia/b and II, myosins IB, IC and II, and calmodulin. All of the sequences show strong similarities to comparable sequences from other organisms. Introns have been found in the actin and myosin genes. The location of the actin intron is unique, but many of the myosin introns occur at the same sites as introns in myosins of other organisms. Sequence comparisons, especially of 5S and 5.8S rRNA and actin, support previous evidence, based primarily on 18S rRNA, that Acanthamoeba genes are at least as closely related to those of higher plants and animals as they are to various other protistan genera. The functional organization of the promoter region for the nuclear rDNA transcription unit has been studied extensively, but there is a need for information about the functional organization of regulatory sequences for other genes. Restriction fragment length profile (RFLP) studies of mitochondrial DNA reveal relatively high levels of overall sequence diversity, but information on the structure and function of individual genes is needed. The RFLP appear to have potential as tools for taxonomic studies of this genus.
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Affiliation(s)
- T J Byers
- Department of Molecular Genetics, Ohio State University, Columbus 43210
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49
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Abstract
In the 4 yr since the molecular biology of DNA in Naegleria was last reviewed several major advances have been made, and these are reviewed here: isolation and characterization of mitochondrial and ribosomal DNAs; enumeration of chromosomal DNAs by pulsed field gel electrophoresis; sequence analysis of differentially expressed genes; phylogenetic placement of the genus Naegleria among the eukaryotes and Naegleria species within the genus.
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Affiliation(s)
- C G Clark
- Laboratory of Molecular Parasitology, Rockefeller University, New York, New York 10021
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50
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Valdés J, de la Cruz Hernández F, Ocádiz R, Orozco E. Molecular karyotype of Entamoeba histolytica and Entamoeba invadens. Trans R Soc Trop Med Hyg 1990; 84:537-41. [PMID: 2091349 DOI: 10.1016/0035-9203(90)90032-a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We report the size-fractionation of Entamoeba histolytica and E. invadens deoxyribonucleic acid (DNA) by pulsed field gradient electrophoresis. Using 3 different electrophoretic conditions, we were able to resolve 6 to 9 bands between 300 and 2000 kilobases (kb), distributed in 16-22 large and up to 31 small chromosomes for E. histolytica DNA. For E. invadens, 4 to 5 bands between 300 and over 2000 kb were resolved and discriminated in 4 large and 6 small chromosomes. A ribosomal probe from Trypanosoma brucei hybridized with a 1100 kb band in E. histolytica strain HM1:IMSS and with a 1000 kb band in clone A of strain HM1:IMSS. Both cell lines also showed hybridization at the origin. The ribosomal probe hybridized only at the origin of the E. invadens DNA lane. A triosephosphate isomerase DNA probe from T. brucei hybridized only with a 2000 kb band in E. invadens, indicating that banding patterns are chromosomal bands and ruling out the possibility of DNA degradation.
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Affiliation(s)
- J Valdés
- Department of Genetics and Molecular Biology, CINVESTAV I.P.N., México, D.F
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