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Adult somatic stem cells in the human parasite Schistosoma mansoni. Nature 2013; 494:476-9. [PMID: 23426263 PMCID: PMC3586782 DOI: 10.1038/nature11924] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 01/18/2013] [Indexed: 12/13/2022]
Abstract
Schistosomiasis is among the most prevalent human parasitic diseases, affecting more than 200 million people worldwide1. The etiological agents of this disease are trematode flatworms (Schistosoma) that live and lay eggs within the vasculature of the host. These eggs lodge in host tissues, causing inflammatory responses that are the primary cause of morbidity. Because these parasites can live and reproduce within human hosts for decades2, elucidating the mechanisms that promote their longevity is of fundamental importance. Although adult pluripotent stem cells, called neoblasts, drive long-term homeostatic tissue maintenance in long-lived free-living flatworms3,4 (e.g., planarians), and neoblast-like cells have been described in some parasitic tapeworms5, little is known about whether similar cell types exist in any trematode species. Here, we describe a population of neoblast-like cells in the trematode Schistosoma mansoni. These cells resemble planarian neoblasts morphologically and share their ability to proliferate and differentiate into derivatives of multiple germ layers. Capitalizing on available genomic resources6,7 and RNAseq-based gene expression profiling, we find that these schistosome neoblast-like cells express a fibroblast growth factor receptor ortholog. Using RNA interference we demonstrate that this gene is required for the maintenance of these neoblast-like cells. Our observations suggest that adaptation of developmental strategies shared by free-living ancestors to modern-day schistosomes likely contributed to the success of these animals as long-lived obligate parasites. We expect that future studies deciphering the function of these neoblast-like cells will have important implications for understanding the biology of these devastating parasites.
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The functional role of a serotonin transporter in Schistosoma mansoni elucidated through immunolocalization and RNA interference (RNAi). Mol Biochem Parasitol 2012; 187:32-42. [PMID: 23246818 DOI: 10.1016/j.molbiopara.2012.11.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 11/28/2012] [Accepted: 11/29/2012] [Indexed: 12/14/2022]
Abstract
Serotonin is an important neurotransmitter in both vertebrates and invertebrates. In the parasitic flatworm, Schistosoma mansoni, serotonin stimulates worm movement and potentiates muscle contraction. A specific serotonin transporter (SmSERT) was previously cloned from S. mansoni and characterized in vitro. Here we conduct a first investigation of the native protein in the worm so as to elucidate the biological role of SmSERT and to assess its drug targeting potential. Confocal immunofluorescence studies using specific antibodies determined that SmSERT is expressed predominantly in the nervous system both in adult worms and larvae (schistosomula). SmSERT immunoreactivity was detected in the main nerve cords of the central nervous system and the peripheral nerve plexus of the body wall in adult males and females, in apparent nerve endings of the male tubercles and possibly the male tegument. In the larvae, SmSERT localized mainly to the peripheral nerve plexus of the body wall. Co-localization experiments showed that the pattern of SmSERT expression coincides with that of serotonin itself, suggesting that SmSERT is present in serotonergic neurons. To test whether SmSERT is involved in the motor effects of serotonin, we treated S. mansoni schistosomula with SmSERT blockers or SmSERT-specific short-interfering RNAs (siRNAs) and then recorded larval motility, using a quantitative imaging assay. In both cases, the treatment produced a strongly hyperactive phenotype, corresponding to a ~3-fold increase in larval motility, roughly the same effect as treatment with an excess of exogenous serotonin. The siRNA effect correlated with a ≈50% decrease in expression of the SmSERT when tested by real-time qPCR. To test if SmSERT mediates transport of exogenous serotonin across the tegument, uptake assays were also performed in intact schistosomula treated with SmSERT siRNAs or an irrelevant siRNA. We found a significant but modest decrease (~25%) in serotonin uptake in the siRNA-suppressed larvae when compared to the negative controls. These results suggest that the SmSERT's function is primarily neuromuscular and may also play a secondary role in the uptake of exogenous (host-derived) serotonin.
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Riesgo A, Andrade SCS, Sharma PP, Novo M, Pérez-Porro AR, Vahtera V, González VL, Kawauchi GY, Giribet G. Comparative description of ten transcriptomes of newly sequenced invertebrates and efficiency estimation of genomic sampling in non-model taxa. Front Zool 2012; 9:33. [PMID: 23190771 PMCID: PMC3538665 DOI: 10.1186/1742-9994-9-33] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 11/08/2012] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED INTRODUCTION Traditionally, genomic or transcriptomic data have been restricted to a few model or emerging model organisms, and to a handful of species of medical and/or environmental importance. Next-generation sequencing techniques have the capability of yielding massive amounts of gene sequence data for virtually any species at a modest cost. Here we provide a comparative analysis of de novo assembled transcriptomic data for ten non-model species of previously understudied animal taxa. RESULTS cDNA libraries of ten species belonging to five animal phyla (2 Annelida [including Sipuncula], 2 Arthropoda, 2 Mollusca, 2 Nemertea, and 2 Porifera) were sequenced in different batches with an Illumina Genome Analyzer II (read length 100 or 150 bp), rendering between ca. 25 and 52 million reads per species. Read thinning, trimming, and de novo assembly were performed under different parameters to optimize output. Between 67,423 and 207,559 contigs were obtained across the ten species, post-optimization. Of those, 9,069 to 25,681 contigs retrieved blast hits against the NCBI non-redundant database, and approximately 50% of these were assigned with Gene Ontology terms, covering all major categories, and with similar percentages in all species. Local blasts against our datasets, using selected genes from major signaling pathways and housekeeping genes, revealed high efficiency in gene recovery compared to available genomes of closely related species. Intriguingly, our transcriptomic datasets detected multiple paralogues in all phyla and in nearly all gene pathways, including housekeeping genes that are traditionally used in phylogenetic applications for their purported single-copy nature. CONCLUSIONS We generated the first study of comparative transcriptomics across multiple animal phyla (comparing two species per phylum in most cases), established the first Illumina-based transcriptomic datasets for sponge, nemertean, and sipunculan species, and generated a tractable catalogue of annotated genes (or gene fragments) and protein families for ten newly sequenced non-model organisms, some of commercial importance (i.e., Octopus vulgaris). These comprehensive sets of genes can be readily used for phylogenetic analysis, gene expression profiling, developmental analysis, and can also be a powerful resource for gene discovery. The characterization of the transcriptomes of such a diverse array of animal species permitted the comparison of sequencing depth, functional annotation, and efficiency of genomic sampling using the same pipelines, which proved to be similar for all considered species. In addition, the datasets revealed their potential as a resource for paralogue detection, a recurrent concern in various aspects of biological inquiry, including phylogenetics, molecular evolution, development, and cellular biochemistry.
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Affiliation(s)
- Ana Riesgo
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
- Centro de Estudios Avanzados de Blanes, CSIC, c/ Accés a la Cala St. Francesc 14, Blanes, Girona, 17300, Spain
| | - Sónia C S Andrade
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
| | - Prashant P Sharma
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
| | - Marta Novo
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
- Current address: Cardiff School of Biosciences, Cardiff University, BIOSI 1, Museum Avenue, Cardiff, CF10 3TL, UK
| | - Alicia R Pérez-Porro
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
- Centro de Estudios Avanzados de Blanes, CSIC, c/ Accés a la Cala St. Francesc 14, Blanes, Girona, 17300, Spain
| | - Varpu Vahtera
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
- Current address: Finnish Museum of Natural History, Zoology Unit, Pohjoinen Rautatiekatu 13, 00014 University of Helsinki, Helsinki, Finland
| | - Vanessa L González
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
| | - Gisele Y Kawauchi
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
| | - Gonzalo Giribet
- Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA
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Parkinson J, Wasmuth JD, Salinas G, Bizarro CV, Sanford C, Berriman M, Ferreira HB, Zaha A, Blaxter ML, Maizels RM, Fernández C. A transcriptomic analysis of Echinococcus granulosus larval stages: implications for parasite biology and host adaptation. PLoS Negl Trop Dis 2012; 6:e1897. [PMID: 23209850 PMCID: PMC3510090 DOI: 10.1371/journal.pntd.0001897] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 09/25/2012] [Indexed: 01/14/2023] Open
Abstract
Background The cestode Echinococcus granulosus - the agent of cystic echinococcosis, a zoonosis affecting humans and domestic animals worldwide - is an excellent model for the study of host-parasite cross-talk that interfaces with two mammalian hosts. To develop the molecular analysis of these interactions, we carried out an EST survey of E. granulosus larval stages. We report the salient features of this study with a focus on genes reflecting physiological adaptations of different parasite stages. Methodology/Principal Findings We generated ∼10,000 ESTs from two sets of full-length enriched libraries (derived from oligo-capped and trans-spliced cDNAs) prepared with three parasite materials: hydatid cyst wall, larval worms (protoscoleces), and pepsin/H+-activated protoscoleces. The ESTs were clustered into 2700 distinct gene products. In the context of the biology of E. granulosus, our analyses reveal: (i) a diverse group of abundant long non-protein coding transcripts showing homology to a middle repetitive element (EgBRep) that could either be active molecular species or represent precursors of small RNAs (like piRNAs); (ii) an up-regulation of fermentative pathways in the tissue of the cyst wall; (iii) highly expressed thiol- and selenol-dependent antioxidant enzyme targets of thioredoxin glutathione reductase, the functional hub of redox metabolism in parasitic flatworms; (iv) candidate apomucins for the external layer of the tissue-dwelling hydatid cyst, a mucin-rich structure that is critical for survival in the intermediate host; (v) a set of tetraspanins, a protein family that appears to have expanded in the cestode lineage; and (vi) a set of platyhelminth-specific gene products that may offer targets for novel pan-platyhelminth drug development. Conclusions/Significance This survey has greatly increased the quality and the quantity of the molecular information on E. granulosus and constitutes a valuable resource for gene prediction on the parasite genome and for further genomic and proteomic analyses focused on cestodes and platyhelminths. Cestodes are a neglected group of platyhelminth parasites, despite causing chronic infections to humans and domestic animals worldwide. We used Echinococcus granulosus as a model to study the molecular basis of the host-parasite cross-talk during cestode infections. For this purpose, we carried out a survey of the genes expressed by parasite larval stages interfacing with definitive and intermediate hosts. Sequencing from several high quality cDNA libraries provided numerous insights into the expression of genes involved in important aspects of E. granulosus biology, e.g. its metabolism (energy production and antioxidant defences) and the synthesis of key parasite structures (notably, the one exposed to humans and livestock intermediate hosts). Our results also uncovered the existence of an intriguing set of abundant repeat-associated non-protein coding transcripts that may participate in the regulation of gene expression in all surveyed stages. The dataset now generated constitutes a valuable resource for gene prediction on the parasite genome and for further genomic and proteomic studies focused on cestodes and platyhelminths. In particular, the detailed characterization of a range of newly discovered genes will contribute to a better understanding of the biology of cestode infections and, therefore, to the development of products allowing their efficient control.
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Affiliation(s)
- John Parkinson
- Program in Molecular Structure and Function, Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - James D. Wasmuth
- Program in Molecular Structure and Function, Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Gustavo Salinas
- Cátedra de Inmunología, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Cristiano V. Bizarro
- Laboratório de Biologia Molecular de Cestódeos and Laboratorio de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Chris Sanford
- Program in Molecular Structure and Function, Hospital for Sick Children, University of Toronto, Toronto, Canada
| | - Matthew Berriman
- Parasite Genomics, The Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Henrique B. Ferreira
- Laboratório de Biologia Molecular de Cestódeos and Laboratorio de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Arnaldo Zaha
- Laboratório de Biologia Molecular de Cestódeos and Laboratorio de Genômica Estrutural e Funcional, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Mark L. Blaxter
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Rick M. Maizels
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (RMM); (CF)
| | - Cecilia Fernández
- Cátedra de Inmunología, Facultad de Química, Universidad de la República, Montevideo, Uruguay
- * E-mail: (RMM); (CF)
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New frontiers in schistosoma genomics and transcriptomics. J Parasitol Res 2012; 2012:849132. [PMID: 23227308 PMCID: PMC3512318 DOI: 10.1155/2012/849132] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 10/16/2012] [Indexed: 12/11/2022] Open
Abstract
Schistosomes are digenean blood flukes of aves and mammals comprising 23 species. Some species are causative agents of human schistosomiasis, the second major neglected disease affecting over 230 million people worldwide. Modern technologies including the sequencing and characterization of nucleic acids and proteins have allowed large-scale analyses of parasites and hosts, opening new frontiers in biological research with potential biomedical and biotechnological applications. Nuclear genomes of the three most socioeconomically important species (S. haematobium, S. japonicum, and S. mansoni) have been sequenced and are under intense investigation. Mitochondrial genomes of six Schistosoma species have also been completely sequenced and analysed from an evolutionary perspective. Furthermore, DNA barcoding of mitochondrial sequences is used for biodiversity assessment of schistosomes. Despite the efforts in the characterization of Schistosoma genomes and transcriptomes, many questions regarding the biology and evolution of this important taxon remain unanswered. This paper aims to discuss some advances in the schistosome research with emphasis on genomics and transcriptomics. It also aims to discuss the main challenges of the current research and to point out some future directions in schistosome studies.
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306
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Zerlotini A, Aguiar ERGR, Yu F, Xu H, Li Y, Young ND, Gasser RB, Protasio AV, Berriman M, Roos DS, Kissinger JC, Oliveira G. SchistoDB: an updated genome resource for the three key schistosomes of humans. Nucleic Acids Res 2012; 41:D728-31. [PMID: 23161692 PMCID: PMC3531198 DOI: 10.1093/nar/gks1087] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The new release of SchistoDB (http://SchistoDB.net) provides a rich resource of genomic data for key blood flukes (genus Schistosoma) which cause disease in hundreds of millions of people worldwide. SchistoDB integrates whole-genome sequence and annotation of three species of the genus and provides enhanced bioinformatics analyses and data-mining tools. A simple, yet comprehensive web interface provided through the Strategies Web Development Kit is available for the mining and visualization of the data. Genomic scale data can be queried based on BLAST searches, annotation keywords and gene ID searches, gene ontology terms, sequence motifs, protein characteristics and phylogenetic relationships. Search strategies can be saved within a user's profile for future retrieval and may also be shared with other researchers using a unique web address.
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Affiliation(s)
- Adhemar Zerlotini
- Centro de Excelência em Bioinformática, National Institute for Science and Technology in Tropical Diseases FIOCRUZ-Minas, Belo Horizonte, MG 30190-002, Brazil
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307
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Silva LL, Marcet-Houben M, Nahum LA, Zerlotini A, Gabaldón T, Oliveira G. The Schistosoma mansoni phylome: using evolutionary genomics to gain insight into a parasite's biology. BMC Genomics 2012; 13:617. [PMID: 23148687 PMCID: PMC3534613 DOI: 10.1186/1471-2164-13-617] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 10/22/2012] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Schistosoma mansoni is one of the causative agents of schistosomiasis, a neglected tropical disease that affects about 237 million people worldwide. Despite recent efforts, we still lack a general understanding of the relevant host-parasite interactions, and the possible treatments are limited by the emergence of resistant strains and the absence of a vaccine. The S. mansoni genome was completely sequenced and still under continuous annotation. Nevertheless, more than 45% of the encoded proteins remain without experimental characterization or even functional prediction. To improve our knowledge regarding the biology of this parasite, we conducted a proteome-wide evolutionary analysis to provide a broad view of the S. mansoni's proteome evolution and to improve its functional annotation. RESULTS Using a phylogenomic approach, we reconstructed the S. mansoni phylome, which comprises the evolutionary histories of all parasite proteins and their homologs across 12 other organisms. The analysis of a total of 7,964 phylogenies allowed a deeper understanding of genomic complexity and evolutionary adaptations to a parasitic lifestyle. In particular, the identification of lineage-specific gene duplications pointed to the diversification of several protein families that are relevant for host-parasite interaction, including proteases, tetraspanins, fucosyltransferases, venom allergen-like proteins, and tegumental-allergen-like proteins. In addition to the evolutionary knowledge, the phylome data enabled us to automatically re-annotate 3,451 proteins through a phylogenetic-based approach rather than solely sequence similarity searches. To allow further exploitation of this valuable data, all information has been made available at PhylomeDB (http://www.phylomedb.org). CONCLUSIONS In this study, we used an evolutionary approach to assess S. mansoni parasite biology, improve genome/proteome functional annotation, and provide insights into host-parasite interactions. Taking advantage of a proteome-wide perspective rather than focusing on individual proteins, we identified that this parasite has experienced specific gene duplication events, particularly affecting genes that are potentially related to the parasitic lifestyle. These innovations may be related to the mechanisms that protect S. mansoni against host immune responses being important adaptations for the parasite survival in a potentially hostile environment. Continuing this work, a comparative analysis involving genomic, transcriptomic, and proteomic data from other helminth parasites, other parasites, and vectors will supply more information regarding parasite's biology as well as host-parasite interactions.
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Affiliation(s)
- Larissa Lopes Silva
- Grupo de Genômica e Biologia Computacional, Centro de Pesquisas René Rachou. Instituto Nacional de Ciência e Tecnologia em Doenças Tropicais. Fundação Oswaldo Cruz - FIOCRUZ, Belo Horizonte, MG, 30190-002, Brazil
- Centro de Excelência em Bioinformática, Fundação Oswaldo Cruz – FIOCRUZ, Belo Horizonte, MG, Brazil
- Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais – UFMG, Belo Horizonte, MG, Brazil
| | - Marina Marcet-Houben
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Dr. Aiguader, 88, 08003, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
| | - Laila Alves Nahum
- Grupo de Genômica e Biologia Computacional, Centro de Pesquisas René Rachou. Instituto Nacional de Ciência e Tecnologia em Doenças Tropicais. Fundação Oswaldo Cruz - FIOCRUZ, Belo Horizonte, MG, 30190-002, Brazil
- Centro de Excelência em Bioinformática, Fundação Oswaldo Cruz – FIOCRUZ, Belo Horizonte, MG, Brazil
- Faculdade Infórium de Tecnologia, Belo Horizonte, MG, 30130-180, Brazil
| | - Adhemar Zerlotini
- Centro de Excelência em Bioinformática, Fundação Oswaldo Cruz – FIOCRUZ, Belo Horizonte, MG, Brazil
- Laboratório Multiusuário de Bioinformática, Embrapa Informática Agropecuária, Campinas, São Paulo, Brazil
| | - Toni Gabaldón
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Dr. Aiguader, 88, 08003, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), 08003, Barcelona, Spain
| | - Guilherme Oliveira
- Grupo de Genômica e Biologia Computacional, Centro de Pesquisas René Rachou. Instituto Nacional de Ciência e Tecnologia em Doenças Tropicais. Fundação Oswaldo Cruz - FIOCRUZ, Belo Horizonte, MG, 30190-002, Brazil
- Centro de Excelência em Bioinformática, Fundação Oswaldo Cruz – FIOCRUZ, Belo Horizonte, MG, Brazil
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308
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Schistosoma tegument proteins in vaccine and diagnosis development: an update. J Parasitol Res 2012; 2012:541268. [PMID: 23125917 PMCID: PMC3483795 DOI: 10.1155/2012/541268] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 09/24/2012] [Indexed: 01/16/2023] Open
Abstract
The development of a vaccine against schistosomiasis and also the availability of a more sensitive diagnosis test are important tools to help chemotherapy in controlling disease transmission. Bioinformatics tools, together with the access to parasite genome, published recently, should help generate new knowledge on parasite biology and search for new vaccines or therapeutic targets and antigens to be used in the disease diagnosis. Parasite surface proteins, especially those expressed in schistosomula tegument, represent interesting targets to be used in vaccine formulations and in the diagnosis of early infections, since the tegument represents the interface between host and parasite and its molecules are responsible for essential functions to parasite survival. In this paper we will present the advances in the development of vaccines and diagnosis tests achieved with the use of the information from schistosome genome focused on parasite tegument as a source for antigens.
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309
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Abstract
Epigenetics is a major field of biomedical research, and epigenetic drug discovery shows great promise for new drugs. The first epigenetic inhibitors are already approved for human treatment. Here, we review a number of case studies that cover different aspects of epigenetic drug discovery spanning from sequencing of epigenetic modifications, assays development over screening to medicinal chemistry, in vivo testing and clinical application.
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310
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Investigation on the 19S ATPase proteasome subunits (Rpt1-6) conservation and their differential gene expression in Schistosoma mansoni. Parasitol Res 2012; 112:235-42. [PMID: 23052763 DOI: 10.1007/s00436-012-3130-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 09/18/2012] [Indexed: 10/27/2022]
Abstract
The ubiquitin-proteasome system is responsible for degradation of the majority of intracellular proteins in eukaryotic cells. The 26S proteasome proteolytic complex is composed of a 20S core particle responsible for protein degradation and the 19S lid which plays a role in the recognition of polyubiquitinated substrates. The 19S regulatory particle (Rps) is composed of ATPase (Rpt) and non-ATPase (Rpn) subunits. In this study, we analyzed the expression profile of 19S Rpt subunits in the larvae and adult stage of the Schistosoma mansoni life cycle. Conventional reverse transcriptase polymerase chain reaction (RT-PCR) revealed that the majority of the 19S Rpt subunits amplified at the expected molecular masses for various investigated stages. In addition, SmRpt1, SmRpt2, and SmRpt6 transcript levels were increased in 3 h-cultured schistosomula and reasonably maintained until 5 h in culture, as revealed by qRT-PCR. Phylogenetic analysis of 19S Rpt subunits showed high structural conservation in comparison to other Rpt orthologues. The mRNA expression profile of 19S Rpt subunits did not correlate with 26S proteasome proteolytic activity as judged by a (14)C-casein-degrading assay, in the early cultured schistosomula. Taken together, these results revealed a differential expression profile for 19S Rpt subunits whose transcript levels could not be directly associated to 26S proteasome activity.
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311
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Albertin CB, Bonnaud L, Brown CT, Crookes-Goodson WJ, da Fonseca RR, Di Cristo C, Dilkes BP, Edsinger-Gonzales E, Freeman RM, Hanlon RT, Koenig KM, Lindgren AR, Martindale MQ, Minx P, Moroz LL, Nödl MT, Nyholm SV, Ogura A, Pungor JR, Rosenthal JJC, Schwarz EM, Shigeno S, Strugnell JM, Wollesen T, Zhang G, Ragsdale CW. Cephalopod genomics: A plan of strategies and organization. Stand Genomic Sci 2012; 7:175-88. [PMID: 23451296 PMCID: PMC3570802 DOI: 10.4056/sigs.3136559] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The Cephalopod Sequencing Consortium (CephSeq Consortium) was established at a NESCent Catalysis Group Meeting, “Paths to Cephalopod Genomics- Strategies, Choices, Organization,” held in Durham, North Carolina, USA on May 24-27, 2012. Twenty-eight participants representing nine countries (Austria, Australia, China, Denmark, France, Italy, Japan, Spain and the USA) met to address the pressing need for genome sequencing of cephalopod mollusks. This group, drawn from cephalopod biologists, neuroscientists, developmental and evolutionary biologists, materials scientists, bioinformaticians and researchers active in sequencing, assembling and annotating genomes, agreed on a set of cephalopod species of particular importance for initial sequencing and developed strategies and an organization (CephSeq Consortium) to promote this sequencing. The conclusions and recommendations of this meeting are described in this white paper.
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Affiliation(s)
- Caroline B Albertin
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA
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312
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Progressive cross-reactivity in IgE responses: an explanation for the slow development of human immunity to schistosomiasis? Infect Immun 2012; 80:4264-70. [PMID: 23006852 DOI: 10.1128/iai.00641-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
People in regions of Schistosoma mansoni endemicity slowly acquire immunity, but why this takes years to develop is still not clear. It has been associated with increases in parasite-specific IgE, induced, some investigators propose, to antigens exposed during the death of adult worms. These antigens include members of the tegumental-allergen-like protein family (TAL1 to TAL13). Previously, in a group of S. mansoni-infected Ugandan males, we showed that IgE responses to three TALs expressed in worms (TAL1, -3, and -5) became more prevalent with age. Now, in a subcohort we examined associations of these responses with resistance to reinfection and use the data to propose a mechanism for the slow development of immunity. IgE was measured 9 weeks posttreatment and at reinfection at 2 years (n = 144). An anti-TAL5 IgE (herein referred to as TAL5 IgE) response was associated with reduced reinfection even after adjusting for age using regression analysis (geometric mean odds ratio, 0.24; P = 0.016). TAL5 IgE responders were a subset of TAL3 IgE responders, themselves a subset of TAL1 responders. TAL3 IgE and TAL5 IgE were highly cross-reactive, with TAL3 the immunizing antigen and TAL5 the cross-reactive antigen. Transcriptional and translational studies show that TAL3 is most abundant in adult worms and that TAL5 is most abundant in infectious larvae. We propose that in chronic schistosomiasis, older individuals have repeatedly experienced IgE antigens exposed when adult worms die (e.g., TAL3) and that this leads to increasing cross-reactivity with antigens of invading larvae (e.g., TAL5). Progressive accumulation of worm/larvae cross-reactivity could explain the age-dependent immunity observed in areas of endemicity.
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313
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Wilson RA. Virulence factors of schistosomes. Microbes Infect 2012; 14:1442-50. [PMID: 22982150 DOI: 10.1016/j.micinf.2012.09.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 07/18/2012] [Accepted: 09/03/2012] [Indexed: 12/25/2022]
Abstract
This review considers whether the products of schistosomes in the mammalian host can be considered as virulence factors. These include: the cercarial secretions used in infection, those of the migrating schistosomulum, surface-exposed proteins of adult worms in the portal system and their gut vomitus in the context of immune evasion, secretions of the egg facilitating its escape from gut tissues and micro-exon gene products.
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Affiliation(s)
- R Alan Wilson
- Centre for Immunology & Infection, Department of Biology, University of York, Heslington, York YO10 5DD, UK.
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314
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Rinaldi G, Eckert SE, Tsai IJ, Suttiprapa S, Kines KJ, Tort JF, Mann VH, Turner DJ, Berriman M, Brindley PJ. Germline transgenesis and insertional mutagenesis in Schistosoma mansoni mediated by murine leukemia virus. PLoS Pathog 2012; 8:e1002820. [PMID: 22911241 PMCID: PMC3406096 DOI: 10.1371/journal.ppat.1002820] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Accepted: 06/11/2012] [Indexed: 12/11/2022] Open
Abstract
Functional studies will facilitate characterization of role and essentiality of newly available genome sequences of the human schistosomes, Schistosoma mansoni, S. japonicum and S. haematobium. To develop transgenesis as a functional approach for these pathogens, we previously demonstrated that pseudotyped murine leukemia virus (MLV) can transduce schistosomes leading to chromosomal integration of reporter transgenes and short hairpin RNA cassettes. Here we investigated vertical transmission of transgenes through the developmental cycle of S. mansoni after introducing transgenes into eggs. Although MLV infection of schistosome eggs from mouse livers was efficient in terms of snail infectivity, >10-fold higher transgene copy numbers were detected in cercariae derived from in vitro laid eggs (IVLE). After infecting snails with miracidia from eggs transduced by MLV, sequencing of genomic DNA from cercariae released from the snails also revealed the presence of transgenes, demonstrating that transgenes had been transmitted through the asexual developmental cycle, and thereby confirming germline transgenesis. High-throughput sequencing of genomic DNA from schistosome populations exposed to MLV mapped widespread and random insertion of transgenes throughout the genome, along each of the autosomes and sex chromosomes, validating the utility of this approach for insertional mutagenesis. In addition, the germline-transmitted transgene encoding neomycin phosphotransferase rescued cultured schistosomules from toxicity of the antibiotic G418, and PCR analysis of eggs resulting from sexual reproduction of the transgenic worms in mice confirmed that retroviral transgenes were transmitted to the next (F1) generation. These findings provide the first description of wide-scale, random insertional mutagenesis of chromosomes and of germline transmission of a transgene in schistosomes. Transgenic lines of schistosomes expressing antibiotic resistance could advance functional genomics for these significant human pathogens. DATABASE ACCESSION: Sequence data from this study have been submitted to the European Nucleotide Archive (http://www.ebi.ac.uk/embl) under accession number ERP000379.
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Affiliation(s)
- Gabriel Rinaldi
- Department of Microbiology, Immunology & Tropical Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC, United States of America
- Departamento de Genética, Facultad de Medicina, Universidad de la República, (UDELAR), Montevideo, Uruguay
| | - Sabine E. Eckert
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Oxford Nanopore Technologies, Oxford, United Kingdom
| | - Isheng J. Tsai
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Sutas Suttiprapa
- Department of Microbiology, Immunology & Tropical Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC, United States of America
- Department of Pathobiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Kristine J. Kines
- Department of Microbiology, Immunology & Tropical Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC, United States of America
- Tulane Cancer Center, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - José F. Tort
- Departamento de Genética, Facultad de Medicina, Universidad de la República, (UDELAR), Montevideo, Uruguay
| | - Victoria H. Mann
- Department of Microbiology, Immunology & Tropical Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC, United States of America
| | - Daniel J. Turner
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Oxford Nanopore Technologies, Oxford, United Kingdom
| | - Matthew Berriman
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Paul J. Brindley
- Department of Microbiology, Immunology & Tropical Medicine, School of Medicine & Health Sciences, The George Washington University, Washington, DC, United States of America
- Research Center for Neglected Diseases of Poverty, The George Washington University, Washington, DC, United States of America
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315
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Hirai H, Hirai Y, LoVerde PT. Evolution of sex chromosomes ZW of Schistosoma mansoni inferred from chromosome paint and BAC mapping analyses. Parasitol Int 2012; 61:684-9. [PMID: 22831897 DOI: 10.1016/j.parint.2012.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/13/2012] [Accepted: 07/17/2012] [Indexed: 11/25/2022]
Abstract
Chromosomes of schistosome parasites among digenetic flukes have a unique evolution because they exhibit the sex chromosomes ZW, which are not found in the other groups of flukes that are hermaphrodites. We conducted molecular cytogenetic analyses for investigating the sex chromosome evolution using chromosome paint analysis and BAC clones mapping. To carry this out, we developed a technique for making paint probes of genomic DNA from a single scraped chromosome segment using a chromosome microdissection system, and a FISH mapping technique for BAC clones. Paint probes clearly identified each of the 8 pairs of chromosomes by a different fluorochrome color. Combination analysis of chromosome paint analysis with Z/W probes and chromosome mapping with 93 BAC clones revealed that the W chromosome of Schistosoma mansoni has evolved by at least four inversion events and heterochromatinization. Nine of 93 BAC clones hybridized with both the Z and W chromosomes, but the locations were different between Z and W chromosomes. The homologous regions were estimated to have moved from the original Z chromosome to the differentiated W chromosome by three inversions events that occurred before W heterohcromatinization. An inversion that was observed in the heterochromatic region of the W chromosome likely occurred after W heterochromatinization. These inversions and heterochromatinization are hypothesized to be the key factors that promoted the evolution of the W chromosome of S. mansoni.
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Affiliation(s)
- Hirohisa Hirai
- Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
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316
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Skinner DE, Rinaldi G, Suttiprapa S, Mann VH, Smircich P, Cogswell AA, Williams DL, Brindley PJ. Vasa-Like DEAD-Box RNA Helicases of Schistosoma mansoni. PLoS Negl Trop Dis 2012; 6:e1686. [PMID: 22720105 PMCID: PMC3373655 DOI: 10.1371/journal.pntd.0001686] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 04/29/2012] [Indexed: 11/18/2022] Open
Abstract
Genome sequences are available for the human blood flukes, Schistosoma japonicum, S. mansoni and S. haematobium. Functional genomic approaches could aid in identifying the role and importance of these newly described schistosome genes. Transgenesis is established for functional genomics in model species, which can lead to gain- or loss-of-functions, facilitate vector-based RNA interference, and represents an effective forward genetics tool for insertional mutagenesis screens. Progress toward routine transgenesis in schistosomes might be expedited if germ cells could be reliably localized in cultured schistosomes. Vasa, a member of the ATP-dependent DEAD-box RNA helicase family, is a prototypic marker of primordial germ cells and the germ line in the Metazoa. Using bioinformatics, 33 putative DEAD-box RNA helicases exhibiting conserved motifs that characterize helicases of this family were identified in the S. mansoni genome. Moreover, three of the helicases exhibited vasa-like sequences; phylogenetic analysis confirmed the three vasa-like genes-termed Smvlg1, Smvlg2, and Smvlg3-were members of the Vasa/PL10 DEAD-box subfamily. Transcripts encoding Smvlg1, Smvlg2, and Smvlg3 were cloned from cDNAs from mixed sex adult worms, and quantitative real time PCR revealed their presence in developmental stages of S. mansoni with elevated expression in sporocysts, adult females, eggs, and miracidia, with strikingly high expression in the undeveloped egg. Whole mount in situ hybridization (WISH) analysis revealed that Smvlg1, Smvlg2 and Smvlg3 were transcribed in the posterior ovary where the oocytes mature. Germ cell specific expression of schistosome vasa-like genes should provide an informative landmark for germ line transgenesis of schistosomes, etiologic agents of major neglected tropical diseases.
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Affiliation(s)
- Danielle E. Skinner
- Department of Microbiology, Immunology & Tropical Medicine, and Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, George Washington University, Washington, D. C., United States of America
| | - Gabriel Rinaldi
- Department of Microbiology, Immunology & Tropical Medicine, and Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, George Washington University, Washington, D. C., United States of America
- Departamento de Genética, Facultad de Medicina, Universidad de la República, (UDELAR), Montevideo, Uruguay
| | - Sutas Suttiprapa
- Department of Pathobiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Victoria H. Mann
- Department of Microbiology, Immunology & Tropical Medicine, and Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, George Washington University, Washington, D. C., United States of America
| | - Pablo Smircich
- Departamento de Genética, Facultad de Medicina, Universidad de la República, (UDELAR), Montevideo, Uruguay
| | - Alexis A. Cogswell
- Department of Microbiology and Immunology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - David L. Williams
- Department of Microbiology and Immunology, Rush University Medical Center, Chicago, Illinois, United States of America
| | - Paul J. Brindley
- Department of Microbiology, Immunology & Tropical Medicine, and Center for Neglected Diseases of Poverty, School of Medicine & Health Sciences, George Washington University, Washington, D. C., United States of America
- * E-mail:
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317
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Swain MT, Tsai IJ, Assefa SA, Newbold C, Berriman M, Otto TD. A post-assembly genome-improvement toolkit (PAGIT) to obtain annotated genomes from contigs. Nat Protoc 2012; 7:1260-84. [PMID: 22678431 PMCID: PMC3648784 DOI: 10.1038/nprot.2012.068] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Genome projects now produce draft assemblies within weeks owing to advanced high-throughput sequencing technologies. For milestone projects such as Escherichia coli or Homo sapiens, teams of scientists were employed to manually curate and finish these genomes to a high standard. Nowadays, this is not feasible for most projects, and the quality of genomes is generally of a much lower standard. This protocol describes software (PAGIT) that is used to improve the quality of draft genomes. It offers flexible functionality to close gaps in scaffolds, correct base errors in the consensus sequence and exploit reference genomes (if available) in order to improve scaffolding and generating annotations. The protocol is most accessible for bacterial and small eukaryotic genomes (up to 300 Mb), such as pathogenic bacteria, malaria and parasitic worms. Applying PAGIT to an E. coli assembly takes ∼24 h: it doubles the average contig size and annotates over 4,300 gene models.
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Affiliation(s)
- Martin T Swain
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK
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318
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Anderson L, Pierce RJ, Verjovski-Almeida S. Schistosoma mansoni histones: From transcription to chromatin regulation; an in silico analysis. Mol Biochem Parasitol 2012; 183:105-14. [DOI: 10.1016/j.molbiopara.2012.03.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 02/29/2012] [Accepted: 03/01/2012] [Indexed: 11/25/2022]
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319
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Biogenic amines and the control of neuromuscular signaling in schistosomes. INVERTEBRATE NEUROSCIENCE 2012; 12:13-28. [PMID: 22526557 DOI: 10.1007/s10158-012-0132-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 03/29/2012] [Indexed: 12/14/2022]
Abstract
Biogenic amines are small cationic monoamines that function broadly as neurotransmitters and/or neuromodulators in every animal phylum. They include such ubiquitous substances as serotonin, dopamine and invertebrate-specific phenolamines (tyramine, octopamine), among others. Biogenic amines are important neuroactive agents in all the flatworms, including blood flukes of the genus Schistosoma, the etiological agents of human schistosomiasis. A large body of evidence spanning nearly five decades identifies biogenic amines as major modulators of neuromuscular function in schistosomes, controlling movement, attachment to the host and other fundamental behaviors. Recent advances in schistosome genomics have made it possible to dissect the molecular mechanisms responsible for these effects and to identify the proteins involved. These efforts have already provided important new information about the mode of action of amine transmitters in the parasite. Moreover, these advances are continuing, as the field moves into a post-genomics era, and new molecular tools for gene and protein analysis are becoming available. Here, we review the current status of this research and discuss future prospects. In particular, we focus our attention on the receptors that mediate biogenic amine activity, their structural characteristics, functional properties and "druggability" potential. One of the themes that will emerge from this discussion is that schistosomes have a rich diversity of aminergic receptors, many of which share little sequence homology with those of the human host, making them ideally suited for selective drug targeting. Strategies for the characterization of these important parasite proteins will be discussed.
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320
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Nelson OW, Garrity GM. Genome sequences published outside of Standards in Genomic Sciences, January-March 2012. Stand Genomic Sci 2012. [DOI: 10.4056/sigs.1756022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Oranmiyan W. Nelson
- 1Editorial Office, Standards in Genomic Sciences and Department of Microbiology, Michigan State University, East Lansing, MI, USA
| | - George M. Garrity
- 1Editorial Office, Standards in Genomic Sciences and Department of Microbiology, Michigan State University, East Lansing, MI, USA
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321
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Lepesant JMJ, Cosseau C, Boissier J, Freitag M, Portela J, Climent D, Perrin C, Zerlotini A, Grunau C. Chromatin structural changes around satellite repeats on the female sex chromosome in Schistosoma mansoni and their possible role in sex chromosome emergence. Genome Biol 2012; 13:R14. [PMID: 22377319 PMCID: PMC3701142 DOI: 10.1186/gb-2012-13-2-r14] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/13/2012] [Accepted: 02/29/2012] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND In the leuphotrochozoan parasitic platyhelminth Schistosoma mansoni, male individuals are homogametic (ZZ) whereas females are heterogametic (ZW). To elucidate the mechanisms that led to the emergence of sex chromosomes, we compared the genomic sequence and the chromatin structure of male and female individuals. As for many eukaryotes, the lower estimate for the repeat content is 40%, with an unknown proportion of domesticated repeats. We used massive sequencing to de novo assemble all repeats, and identify unambiguously Z-specific, W-specific and pseudoautosomal regions of the S. mansoni sex chromosomes. RESULTS We show that 70 to 90% of S. mansoni W and Z are pseudoautosomal. No female-specific gene could be identified. Instead, the W-specific region is composed almost entirely of 36 satellite repeat families, of which 33 were previously unknown. Transcription and chromatin status of female-specific repeats are stage-specific: for those repeats that are transcribed, transcription is restricted to the larval stages lacking sexual dimorphism. In contrast, in the sexually dimorphic adult stage of the life cycle, no transcription occurs. In addition, the euchromatic character of histone modifications around the W-specific repeats decreases during the life cycle. Recombination repression occurs in this region even if homologous sequences are present on both the Z and W chromosomes. CONCLUSION Our study provides for the first time evidence for the hypothesis that, at least in organisms with a ZW type of sex chromosomes, repeat-induced chromatin structure changes could indeed be the initial event in sex chromosome emergence.
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Affiliation(s)
- Julie M J Lepesant
- Université de Perpignan Via Domitia, CNRS, UMR 5244 Ecologie et Evolution des Interactions (2EI), 52 Avenue Paul Alduy, 66860 Perpignan Cedex, France.
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322
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Lepesant JMJ, Roquis D, Emans R, Cosseau C, Arancibia N, Mitta G, Grunau C. Combination of de novo assembly of massive sequencing reads with classical repeat prediction improves identification of repetitive sequences in Schistosoma mansoni. Exp Parasitol 2012; 130:470-4. [PMID: 22381218 DOI: 10.1016/j.exppara.2012.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 02/07/2012] [Accepted: 02/08/2012] [Indexed: 11/18/2022]
Abstract
The genome of the parasitic platyhelminth Schistosoma mansoni is composed of approximately 40% of repetitive sequences of which roughly 20% correspond to transposable elements. When the genome sequence became available, conventional repeat prediction programs were used to find these repeats, but only a fraction could be identified. To exhaustively characterize the repeats we applied a new massive sequencing based strategy: we re-sequenced the genome by next generation sequencing, aligned the sequencing reads to the genome and assembled all multiple-hit reads into contigs corresponding to the repetitive part of the genome. We present here, for the first time, this de novo repeat assembly strategy and we confirm that such assembly is feasible. We identified and annotated 4,143 new repeats in the S. mansoni genome. At least one third of the repeats are transcribed. This strategy allowed us also to identify 14 new microsatellite markers, which can be used for pedigree studies. Annotations and the combined (previously known and new) 5,420 repeat sequences (corresponding to 47% of the genome) are available for download (http://methdb.univ-perp.fr/downloads/).
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