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Abstract
Microsporidia are obligate intracellular pathogens related to Fungi. These organisms have a unique invasion organelle, the polar tube, which upon appropriate environmental stimulation rapidly discharges out of the spore, pierces a host cell's membrane, and serves as a conduit for sporoplasm passage into the host cell. Phylogenetic analysis suggests that microsporidia are related to the Fungi, being either a basal branch or sister group. Despite the description of microsporidia over 150 years ago, we still lack an understanding of the mechanism of invasion, including the role of various polar tube proteins, spore wall proteins, and host cell proteins in the formation and function of the invasion synapse. Recent advances in ultrastructural techniques are helping to better define the formation and functioning of the invasion synapse. Over the past 2 decades, proteomic approaches have helped define polar tube proteins and spore wall proteins as well as the importance of posttranslational modifications such as glycosylation in the functioning of these proteins, but the absence of genetic techniques for the manipulation of microsporidia has hampered research on the function of these various proteins. The study of the mechanism of invasion should provide fundamental insights into the biology of these ubiquitous intracellular pathogens that can be integrated into studies aimed at treating or controlling microsporidiosis.
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Dia N, Lavie L, Faye N, Méténier G, Yeramian E, Duroure C, Toguebaye BS, Frutos R, Niang MN, Vivarès CP, Ben Mamoun C, Cornillot E. Subtelomere organization in the genome of the microsporidian Encephalitozoon cuniculi: patterns of repeated sequences and physicochemical signatures. BMC Genomics 2016; 17:34. [PMID: 26744270 PMCID: PMC4704409 DOI: 10.1186/s12864-015-1920-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 09/11/2015] [Indexed: 12/23/2022] Open
Abstract
Background The microsporidian Encephalitozoon cuniculi is an obligate intracellular eukaryotic pathogen with a small nuclear genome (2.9 Mbp) consisting of 11 chromosomes. Although each chromosome end is known to contain a single rDNA unit, the incomplete assembly of subtelomeric regions following sequencing of the genome identified only 3 of the 22 expected rDNA units. While chromosome end assembly remains a difficult process in most eukaryotic genomes, it is of significant importance for pathogens because these regions encode factors important for virulence and host evasion. Results Here we report the first complete assembly of E. cuniculi chromosome ends, and describe a novel mosaic structure of segmental duplications (EXT repeats) in these regions. EXT repeats range in size between 3.5 and 23.8 kbp and contain four multigene families encoding membrane associated proteins. Twenty-one recombination sites were identified in the sub-terminal region of E. cuniculi chromosomes. Our analysis suggests that these sites contribute to the diversity of chromosome ends organization through Double Strand Break repair mechanisms. The region containing EXT repeats at chromosome extremities can be differentiated based on gene composition, GC content, recombination sites density and chromosome landscape. Conclusion Together this study provides the complete structure of the chromosome ends of E. cuniculi GB-M1, and identifies important factors, which could play a major role in parasite diversity and host-parasite interactions. Comparison with other eukaryotic genomes suggests that terminal regions could be distinguished precisely based on gene content, genetic instability and base composition biais. The diversity of processes assciated with chromosome extremities and their biological consequences, as they are presented in the present study, emphasize the fact that great effort will be necessary in the future to characterize more carefully these regions during whole genome sequencing efforts. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1920-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ndongo Dia
- Unité de Virologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, B.P. 220, Dakar, Sénégal.
| | - Laurence Lavie
- Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes, Génome et Environnement, UMR 6023, CNRS, 63177, Aubière, France.
| | - Ngor Faye
- Laboratoire de Parasitologie Générale, Département de Biologie Animale, Faculté des Sciences et Technologies, Université Cheikh Anta Diop, Dakar, Sénégal.
| | - Guy Méténier
- Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes, Génome et Environnement, UMR 6023, CNRS, 63177, Aubière, France.
| | - Edouard Yeramian
- Unité de Bioinformatique Structurale, UMR 3528 CNRS, Institut Pasteur, 25-28, rue du Dr Roux, 75015, Paris, France.
| | - Christophe Duroure
- Laboratoire de Météorologie Physique, OPGC UMR 6016 CNRS-Université Blaise Pascal, 24 Avenue des Landais, 63177, Aubière Cedex, France.
| | - Bhen S Toguebaye
- Laboratoire de Parasitologie Générale, Département de Biologie Animale, Faculté des Sciences et Technologies, Université Cheikh Anta Diop, Dakar, Sénégal.
| | - Roger Frutos
- CIRAD, UMR 17, Cirad-Ird, TA-A17/G, Campus International de Baillarguet, 34398, Montpellier, France.
| | - Mbayame N Niang
- Unité de Virologie Médicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, B.P. 220, Dakar, Sénégal.
| | - Christian P Vivarès
- Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes, Génome et Environnement, UMR 6023, CNRS, 63177, Aubière, France.
| | - Choukri Ben Mamoun
- Section of Infectious Disease and Department of Microbial Pathogenesis, Winchester Building WWW403D, Yale School of Medicine, 15 York St., New Haven, CT, 06520, USA.
| | - Emmanuel Cornillot
- Institut de Recherche en Cancérologie de Montpellier, IRCM - INSERM U1194 & Université de Montpellier & ICM, Institut régional du Cancer Montpellier, Campus Val d'Aurelle, 34298, Montpellier cedex 5, France. .,Institut de Biologie Computationnelle, IBC, Campus Saint Priest, 34090, Montpellier, France.
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Jenkins AJ, Joglekar MV, Hardikar AA, Keech AC, O'Neal DN, Januszewski AS. Biomarkers in Diabetic Retinopathy. Rev Diabet Stud 2015; 12:159-95. [PMID: 26676667 DOI: 10.1900/rds.2015.12.159] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
There is a global diabetes epidemic correlating with an increase in obesity. This coincidence may lead to a rise in the prevalence of type 2 diabetes. There is also an as yet unexplained increase in the incidence of type 1 diabetes, which is not related to adiposity. Whilst improved diabetes care has substantially improved diabetes outcomes, the disease remains a common cause of working age adult-onset blindness. Diabetic retinopathy is the most frequently occurring complication of diabetes; it is greatly feared by many diabetes patients. There are multiple risk factors and markers for the onset and progression of diabetic retinopathy, yet residual risk remains. Screening for diabetic retinopathy is recommended to facilitate early detection and treatment. Common biomarkers of diabetic retinopathy and its risk in clinical practice today relate to the visualization of the retinal vasculature and measures of glycemia, lipids, blood pressure, body weight, smoking, and pregnancy status. Greater knowledge of novel biomarkers and mediators of diabetic retinopathy, such as those related to inflammation and angiogenesis, has contributed to the development of additional therapeutics, in particular for late-stage retinopathy, including intra-ocular corticosteroids and intravitreal vascular endothelial growth factor inhibitors ('anti-VEGFs') agents. Unfortunately, in spite of a range of treatments (including laser photocoagulation, intraocular steroids, and anti-VEGF agents, and more recently oral fenofibrate, a PPAR-alpha agonist lipid-lowering drug), many patients with diabetic retinopathy do not respond well to current therapeutics. Therefore, more effective treatments for diabetic retinopathy are necessary. New analytical techniques, in particular those related to molecular markers, are accelerating progress in diabetic retinopathy research. Given the increasing incidence and prevalence of diabetes, and the limited capacity of healthcare systems to screen and treat diabetic retinopathy, there is need to reliably identify and triage people with diabetes. Biomarkers may facilitate a better understanding of diabetic retinopathy, and contribute to the development of novel treatments and new clinical strategies to prevent vision loss in people with diabetes. This article reviews key aspects related to biomarker research, and focuses on some specific biomarkers relevant to diabetic retinopathy.
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Affiliation(s)
- Alicia J Jenkins
- NHMRC Clinical Trials Centre, University of Sydney, Camperdown, Sydney, Australia
| | - Mugdha V Joglekar
- NHMRC Clinical Trials Centre, University of Sydney, Camperdown, Sydney, Australia
| | | | - Anthony C Keech
- NHMRC Clinical Trials Centre, University of Sydney, Camperdown, Sydney, Australia
| | - David N O'Neal
- NHMRC Clinical Trials Centre, University of Sydney, Camperdown, Sydney, Australia
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4
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Corradi N, Slamovits CH. The intriguing nature of microsporidian genomes. Brief Funct Genomics 2010; 10:115-24. [PMID: 21177329 DOI: 10.1093/bfgp/elq032] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Microsporidia are a group of highly adapted unicellular fungi that are known to infect a wide range of animals, including humans and species of great economic importance. These organisms are best known for their very simple cellular and genomic features, an adaptive consequence of their obligate intracellular parasitism. In the last decade, the acquisition of a large amount of genomic and transcriptomic data from several microsporidian species has greatly improved our understanding of the consequences of a purely intracellular lifestyle. In particular, genome sequence data from these pathogens has revealed how obligate intracellular parasitism can result in radical changes in the composition and structure of nuclear genomes and how these changes can affect cellular and evolutionary mechanisms that are otherwise well conserved among eukaryotes. This article reviews our current understanding of the genome content and structure of microsporidia, discussing their evolutionary origin and cataloguing the mechanisms that have often been involved in their extreme reduction.
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Affiliation(s)
- Nicolas Corradi
- Canadian Institute for Advanced Research, Department of Biology, University of Ottawa, Gendron Hall, ON, Canada.
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5
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Corradi N, Pombert JF, Farinelli L, Didier ES, Keeling PJ. The complete sequence of the smallest known nuclear genome from the microsporidian Encephalitozoon intestinalis. Nat Commun 2010; 1:77. [PMID: 20865802 PMCID: PMC4355639 DOI: 10.1038/ncomms1082] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 08/25/2010] [Indexed: 12/20/2022] Open
Abstract
The genome of the microsporidia Encephalitozoon cuniculi is widely recognized as a model for extreme reduction and compaction. At only 2.9 Mbp, the genome encodes approximately 2,000 densely packed genes and little else. However, the nuclear genome of its sister, Encephalitozoon intestinalis, is even more reduced; at 2.3 Mbp, it represents a 20% reduction from an already severely compacted genome, raising the question, what else can be lost? In this paper, we describe the complete sequence of the E. intestinalis genome and its comparison with that of E. cuniculi. The two species share a conserved gene content, order and density over most of their genomes. The exceptions are the subtelomeric regions, where E. intestinalis chromosomes are missing large gene blocks of sequence found in E. cuniculi. In the remaining gene-dense chromosome 'cores', the diminutive intergenic sequences and introns are actually more highly conserved than the genes themselves, suggesting that they have reached the limits of reduction for a fully functional genome. A comparison of related genomes provides valuable information about how they evolve. Here, the complete sequence of the smallest known nuclear genome from the microsporidia E. intestinalis is described and compared with its larger sister E. cuniculi, revealing what parts are indispensable in even the most reduced genomes.
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Affiliation(s)
- Nicolas Corradi
- Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, 3529-6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4
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6
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Abstract
The genomic peculiarities among microbial eukaryotes challenge the conventional wisdom of genome evolution. Currently, many studies and textbooks explore principles of genome evolution from a limited number of eukaryotic lineages, focusing often on only a few representative species of plants, animals and fungi. Increasing emphasis on studies of genomes in microbial eukaryotes has and will continue to uncover features that are either not present in the representative species (e.g. hypervariable karyotypes or highly fragmented mitochondrial genomes) or are exaggerated in microbial groups (e.g. chromosomal processing between germline and somatic nuclei). Data for microbial eukaryotes have emerged from recent genome sequencing projects, enabling comparisons of the genomes from diverse lineages across the eukaryotic phylogenetic tree. Some of these features, including amplified rDNAs, subtelomeric rDNAs and reduced genomes, appear to have evolved multiple times within eukaryotes, whereas other features, such as absolute strand polarity, are found only within single lineages.
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Affiliation(s)
- Casey L McGrath
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA
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7
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Dia N, Lavie L, Méténier G, Toguebaye BS, Vivarès CP, Cornillot E. InterB multigenic family, a gene repertoire associated with subterminal chromosome regions of Encephalitozoon cuniculi and conserved in several human-infecting microsporidian species. Curr Genet 2007; 51:171-86. [PMID: 17235519 DOI: 10.1007/s00294-006-0114-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2006] [Revised: 11/08/2006] [Accepted: 11/28/2006] [Indexed: 11/30/2022]
Abstract
Microsporidia are fungi-related obligate intracellular parasites that infect numerous animals, including man. Encephalitozoon cuniculi harbours a very small genome (2.9 Mbp) with about 2,000 coding sequences (CDSs). Most repeated CDSs are of unknown function and are distributed in subterminal regions that mark the transitions between subtelomeric rDNA units and chromosome cores. A potential multigenic family (interB) encoding proteins within a size range of 579-641 aa was investigated by PCR and RT-PCR. Thirty members were finally assigned to the E. cuniculi interB family and a predominant interB transcript was found to originate from a newly identified gene on chromosome III. Microsporidian species from eight different genera infecting insects, fishes or mammals, were tested for a possible intra-phylum conservation of interB genes. Only representatives of the Encephalitozoon, Vittaforma and Brachiola genera, differing in host range but all able to invade humans, were positive. Molecular karyotyping of Brachiola algerae showed a complex set of chromosome bands, providing a haploid genome size estimate of 15-20 Mbp. In spite of this large difference in genome complexity, B. algerae and E. cuniculi shared some similar interB gene copies and a common location of interB genes in near-rDNA subterminal regions.
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Affiliation(s)
- Ndongo Dia
- Equipe Parasitologie Moléculaire et Cellulaire, Laboratoire de Biologie des Protistes, UMR CNRS 6023, Bâtiment Biologie A, Université Blaise Pascal, 63177 Aubière cedex, France
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8
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O'Mahony EM, Tay WT, Paxton RJ. Multiple rRNA Variants in a Single Spore of the Microsporidian Nosema bombi. J Eukaryot Microbiol 2007; 54:103-9. [PMID: 17300528 DOI: 10.1111/j.1550-7408.2006.00232.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To understand the source of the multiple DNA sequence variants of Nosema bombi ribosomal RNA (rRNA) found in a single bumble bee host, we PCR amplified, cloned, and sequenced the partial rRNA gene from 125 clones, which were derived from four out of 46 spores individually isolated from a single host by laser microdissection. At least two rRNA variants, characterized by either (GTTT)(2) or (GTTT)(3) repeat units within the internal transcribed spacer (ITS) region, were found per spore in approximately equal proportions, variants which were also found in approximately equal proportions in 55 clones of the two DNA extracts of multiple spores from the same host. Firstly, we demonstrate for the first time that DNA sequences can be obtained from single-binucleate microsporidia. Secondly, it appears that concerted evolution has not homogenized the sequences of all rRNA copies within a single N. bombi spore or even within a single nucleus. We thereby demonstrate unequivocally that two or more rRNA sequence variants exist per N. bombi spore, and urge caution in the use of multicopy rRNA genes for population genetic and phylogenetic analysis of this and other Microsporidia unless homologous copies can be reliably typed.
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Affiliation(s)
- Elaine M O'Mahony
- School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, United Kingdom.
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9
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Affiliation(s)
- Patrick J Keeling
- Canadian Institute for Advanced Research, Botany Department, University of British Columbia, 3529-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada.
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10
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Mansour L, Cheikali C, Desaunais P, Coulon JP, Daubin J, Hassine OKB, Vivarès CP, Jeanjean J, Cornillot E. Description of an ultrathin multiwire proportional chamber-based detector and application to the characterization of theSpraguea lophii(Microspora) two-dimensional genome fingerprint. Electrophoresis 2004; 25:3365-77. [PMID: 15490460 DOI: 10.1002/elps.200406089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Multiwire proportional chamber is a useful technology to build detectors that supersede the lack of interactivity of autoradiography in molecular biology experiments. Some drawbacks still limited the diffusion of existing instruments in biological laboratories. The major competitors are storage phosphor imaging systems. The simplified description of a radio-chromato-imager prototype (RCI) based on an original ultrathin multiwire proportional chamber is presented. It combines the advantage of the different existing technologies to present competitive properties in terms of efficiency, spatial resolution, robustness, manipulation easiness and production cost. Application of the RCI detector to molecular biology was performed by the analysis of karyotype and restriction display two-dimensional pulsed-field gel electrophoresis (KARD 2-D PFGE) data which are used to describe small eukaryotic genome structures. The comparative analysis with autoradiography was performed with the PDQuest software on Spraguea lophii (Microspora) genome fingerprints. The spot detection procedure applied to the different images leads to a similar conclusion considering the genome structure of S. lophii which appeared to be composed of 15 chromosomes for 13 karyotypic bands (200-880 kbp).
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Affiliation(s)
- Lamjed Mansour
- Parasitologie Moléculaireet Cellulaire, Université Blaise Pascal, Aubière, France.
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11
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Brugere JF, Cornillot E, Bourbon T, Metenier G, Vivarès CP. Inter-strain variability of insertion/deletion events in the Encephalitozoon cuniculi genome: a comparative KARD-PFGE analysis. J Eukaryot Microbiol 2002; Suppl:50S-55S. [PMID: 11906078 DOI: 10.1111/j.1550-7408.2001.tb00451.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We applied a two-dimensional pulsed-field gel electrophoresis procedure to the genomes of two karyotype variants assigned to two different strains of the microsporidian Encephalitozoon cuniculi, termed D (strain III) and F (strain II). Data obtained for BssHII and MluI restriction fragment length polymorphisms in each chromosome are compiled and compared to the reference strain I variant A. Six Insertion/Deletion (InDels) are found in subterminal position, some of these being characteristic of either D or F. Like in strain 1, the terminal fragments extending between each telomere and rDNA locus are conserved in length for each chromosome. They are however smaller than in reference variant. This size reduction is estimated to be 2.5 kbp for the strain III isolate and 3.5 kbp for the strain II isolate. We hypothesize that for the three E. cuniculi strains, all chromosome extremities are prone to a constant process of sequence homogenization through mitotic recombination between conserved regions.
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Affiliation(s)
- J F Brugere
- Parasitologie Moléculaire et Cellulaire, LBP, UMR CNRS 6023, Université Blaise Pascal, Aubière, France
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Mercereau-Puijalon O, Barale JC, Bischoff E. Three multigene families in Plasmodium parasites: facts and questions. Int J Parasitol 2002; 32:1323-44. [PMID: 12350369 DOI: 10.1016/s0020-7519(02)00111-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Multigene families optimise fitness by providing a set of related genes with possibly different temporal and/or topological expression patterns. We analyse here the structural organisation and sequence diversity of the rDNA, sera and var C Plasmodium falciparum families, and discuss their consequences for parasite biology. The low rDNA copy number, which reduces reshuffling, is probably the corollary of the need for functionally distinct rRNAs in the insect and in the vertebrate host. The unusual intra-genome and population rDNA sequence diversity results in cells equipped with mosaic ribosome sets. The functional constraints are such that ribosome compatibility could influence parasite fitness and contribute to population structuring. Unlike the dispersed rDNA units, the sera family is arranged as a tandem gene cluster, with seven contiguous similar genes, and one more distantly related paralog. We address the question of the inclusion criteria in family definition. We discuss the results concerning the SERA proteins expression and function in the context of the long overlooked multigene family. The var C module is shared by var genes, 'orphan' var C and var C pseudogenes. Analysis of 125 var C deduced protein sequences highlights a well-conserved framework, including putative phosphorylation sites, consistent with the proposed function of mediating interaction with cytoskeletal proteins. The 5' and 3' flanking sequences of the var C pseudogenes are heterogeneous. In contrast, the flanking sequences of the uninterrupted var C modules show remarkable conservation. This is interesting in view of the silencing activity of the var intronic sequence on var expression. The 5' flanking sequence dichotomy reported for internal and sub-telomeric var genes extends to the 3' flanking sequences. This has profound implications for transcription regulation and generation of diversity. The var C family suggests a role for pseudogenes as a diversity reservoir and in genome dynamics by promoting ectopic recombination.
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Affiliation(s)
- Odile Mercereau-Puijalon
- Unité d'Immunologie Moléculaire des Parasites, Unité de Recherche Associée 1960 du Centre National de la Recherche Scientifique, Institut Pasteur, 25 rue du Dr ROUX, 75015, Paris, France.
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Cornillot E, Keller B, Cushion MT, Méténier G, Vivarès CP. Fine analysis of the Pneumocystis carinii f. sp. carinii genome by two-dimensional pulsed-field gel electrophoresis. Gene 2002; 293:87-95. [PMID: 12137946 DOI: 10.1016/s0378-1119(02)00604-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pneumocystis carinii is a general designation for a group of unusual unicellular fungal parasites responsible of pneumopathy in animal hosts. Divided into several subgroups termed the 'special forms', P. carinii is prone to an extensive karyotype variation. In previous studies, the nuclear genome of these organisms has been considered to be haploid and a set of 16 chromosomes has been assigned to P. carinii f. sp. carinii, a special form known to infect rats. We report the analysis of the genome of an isolate representative of the karyotype 1 of this special form, using two-dimensional pulsed-field gel electrophoresis procedures. The 'karyotype and restriction display' (KARD) fingerprints indicated the presence of 17 different chromosomes. The haploid genome size was estimated to be 8.4 Mbp. Some homologous chromosomes were distinguished on the basis of a single restriction fragment length polymorphism, which raises the possibility of a diploid nucleus. A restriction map of the chromosome 15, characterized by two homologues with a size difference of 7 kb, was constructed. Hybridization data indicated that insertion/deletion events may have occurred within subtelomeric regions which carry genes encoding the major surface glycoprotein (MSG) of Pneumocystis.
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Affiliation(s)
- Emmanuel Cornillot
- Parasitologie Moléculaire et Cellulaire, LBP, UMR CNRS 6023, Université Blaise Pascal, Bâtiment Biologie A, Campus universitaire des Cézeaux, Aubière, France.
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Brown AMV, Kent ML. Molecular Diagnostics for Loma Salmonae and Nucleospora Salmonis (Microsporidia). REVIEWS: METHODS AND TECHNOLOGIES IN FISH BIOLOGY AND FISHERIES 2002. [DOI: 10.1007/978-94-017-2315-2_10] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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15
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Abstract
A survey of the molecular features of microsporidia is presented which attempts to comment on unresolved questions concerning the physiology of these amitochondrial intracellular parasites. Various transports of host-derived molecules can be predicted and trehalose appears as a potential reserve of glucose for energy metabolism. Significant insights into membrane lipids, polyamine metabolism and sporogony-specific proteins have been gained. Some species, such as Encephalitozoon cuniculi, are heterogeneous entities and harbor a small genome. Although showing a variation in genome size of 8.5-fold, microsporidia share reduced rDNA genes. Finally, data on gene organization and a possible evolutionary relationship with fungi are considered.
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Affiliation(s)
- G Méténier
- Laboratoire de parasitologie moléculaire et cellulaire, LBP, UMC CNRS 6023 Biologie A, Université B. Pascal, 63177 cedex, Aubière, France.
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Peyret P, Katinka MD, Duprat S, Duffieux F, Barbe V, Barbazanges M, Weissenbach J, Saurin W, Vivarès CP. Sequence and analysis of chromosome I of the amitochondriate intracellular parasite Encephalitozoon cuniculi (Microspora). Genome Res 2001; 11:198-207. [PMID: 11157783 PMCID: PMC311017 DOI: 10.1101/gr.164301] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A DNA sequencing program was applied to the small (<3 Mb) genome of the microsporidian Encephalitozoon cuniculi, an amitochondriate eukaryotic parasite of mammals, and the sequence of the smallest chromosome was determined. The approximately 224-kb E. cuniculi chromosome I exhibits a dyad symmetry characterized by two identical 37-kb subtelomeric regions which are divergently oriented and extend just downstream of the inverted copies of an 8-kb duplicated cluster of six genes. Each subtelomeric region comprises a single 16S-23S rDNA transcription unit, flanked by various tandemly repeated sequences, and ends with approximately 1 kb of heterogeneous telomeric repeats. The central (or core) region of the chromosome harbors a highly compact arrangement of 132 potential protein-coding genes plus two tRNA genes (one gene per 1.14 kb). Most genes occur as single copies with no identified introns. Of these putative genes, only 53 could be assigned to known functions. A number of genes from the transcription and translation machineries as well as from other cellular processes display characteristic eukaryotic signatures or are clearly eukaryote-specific.
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Affiliation(s)
- P Peyret
- Equipe de Parasitologie Moléculaire et Cellulaire, LBP, UMR CNRS 6023, Université Blaise Pascal, 63177 Aubière Cedex, France. pierre.peyret@ lbp.univ-bpclermont.fr
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17
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Abstract
Microsporidia are well-known to infect immunocompromised patients and are also responsible for clinical syndromes in immunocompetent individuals. In recent years, evidence has been obtained in support of a very close relationship between Microsporidia and Fungi. In some species, the compaction of the genome and genes is remarkable. Thus, a systematic sequencing project has been initiated for the 2.9 Mbp genome of Encephalitozoon cuniculi, which will be useful for future comparative genomic studies.
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Affiliation(s)
- C P Vivarès
- Laboratoire Parasitologie Moléculaire et Cellulaire, UMR CNRS 6023, Université Blaise Pascal, 63177, Aubière Cedex, France.
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