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Horáčková V, Voleman L, Hagen KD, Petrů M, Vinopalová M, Weisz F, Janowicz N, Marková L, Motyčková A, Najdrová V, Tůmová P, Dawson SC, Doležal P. Efficient CRISPR/Cas9-mediated gene disruption in the tetraploid protist Giardia intestinalis. Open Biol 2022; 12:210361. [PMID: 35472287 PMCID: PMC9042576 DOI: 10.1098/rsob.210361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 03/14/2022] [Indexed: 01/07/2023] Open
Abstract
CRISPR/Cas9-mediated genome editing has become an extremely powerful technique used to modify gene expression in many organisms, including parasitic protists. Giardia intestinalis, a protist parasite that infects approximately 280 million people around the world each year, has been eluding the use of CRISPR/Cas9 to generate knockout cell lines due to its tetraploid genome. In this work, we show the ability of the in vitro assembled CRISPR/Cas9 components to successfully edit the genome of G. intestinalis. The cell line that stably expresses Cas9 in both nuclei of G. intestinalis showed effective recombination of the cassette containing the transcription units for the gRNA and the resistance marker. This highly efficient process led to the removal of all gene copies at once for three independent experimental genes, mem, cwp1 and mlf1. The method was also applicable to incomplete disruption of the essential gene, as evidenced by significantly reduced expression of tom40. Finally, testing the efficiency of Cas9-induced recombination revealed that homologous arms as short as 150 bp can be sufficient to establish a complete knockout cell line in G. intestinalis.
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Affiliation(s)
- Vendula Horáčková
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Luboš Voleman
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Kari D. Hagen
- Department of Microbiology and Molecular Genetics, College of Biological Sciences, UC Davis, Davis, CA, USA
| | - Markéta Petrů
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Martina Vinopalová
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Filip Weisz
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Natalia Janowicz
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Lenka Marková
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Alžběta Motyčková
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Vladimíra Najdrová
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
| | - Pavla Tůmová
- Institute of Immunology and Microbiology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Scott C. Dawson
- Department of Microbiology and Molecular Genetics, College of Biological Sciences, UC Davis, Davis, CA, USA
| | - Pavel Doležal
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Praha, Czech Republic
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2
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Zajaczkowski P, Lee R, Fletcher-Lartey SM, Alexander K, Mahimbo A, Stark D, Ellis JT. The controversies surrounding Giardia intestinalis assemblages A and B. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2022; 1:100055. [PMID: 35284870 PMCID: PMC8906113 DOI: 10.1016/j.crpvbd.2021.100055] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 10/09/2021] [Indexed: 11/27/2022]
Abstract
Giardia intestinalis continues to be one of the most encountered parasitic diseases around the world. Although more frequently detected in developing countries, Giardia infections nonetheless pose significant public health problems in developed countries as well. Molecular characterisation of Giardia isolates from humans and animals reveals that there are two genetically different assemblages (known as assemblage A and B) that cause human infections. However, the current molecular assays used to genotype G. intestinalis isolates are quite controversial. This is in part due to a complex phenomenon where assemblages are incorrectly typed and underreported depending on which targeted locus is sequenced. In this review, we outline current knowledge based on molecular epidemiological studies and raise questions as to the reliability of current genotyping assays and a lack of a globally accepted method. Additionally, we discuss the clinical symptoms caused by G. intestinalis infection and how these symptoms vary depending on the assemblage infecting an individual. We also introduce the host-parasite factors that play a role in the subsequent clinical presentation of an infected person, and explore which assemblages are most seen globally.
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Affiliation(s)
- Patricia Zajaczkowski
- Faculty of Science, School of Life Sciences, University of Technology Sydney, Australia
| | - Rogan Lee
- Centre for Infectious Diseases and Microbiology Laboratory Services, ICPMR, Westmead Hospital, Westmead, New South Wales, Australia.,Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Westmead Hospital, Westmead, NSW, Australia
| | | | - Kate Alexander
- Public Health Unit, South Western Sydney Local Health District, Liverpool, Australia
| | - Abela Mahimbo
- Faculty of Health, School of Public Health, University of Technology Sydney, Australia
| | - Damien Stark
- Department of Microbiology, St Vincent's Hospital Sydney, Darlinghurst, New South Wales, Australia
| | - John T Ellis
- Faculty of Science, School of Life Sciences, University of Technology Sydney, Australia
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3
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Leishmania and the Model of Predominant Clonal Evolution. Microorganisms 2021; 9:microorganisms9112409. [PMID: 34835534 PMCID: PMC8620605 DOI: 10.3390/microorganisms9112409] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/18/2021] [Accepted: 11/20/2021] [Indexed: 01/23/2023] Open
Abstract
As it is the case for other pathogenic microorganisms, the respective impact of clonality and genetic exchange on Leishmania natural populations has been the object of lively debates since the early 1980s. The predominant clonal evolution (PCE) model states that genetic exchange in these parasites’ natural populations may have a high relevance on an evolutionary scale, but is not sufficient to erase a persistent phylogenetic signal and the existence of bifurcating trees. Recent data based on high-resolution markers and genomic polymorphisms fully confirm the PCE model down to a microevolutionary level.
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Abstract
Giardia duodenalis captured the attention of Leeuwenhoek in 1681 while he was examining his own diarrheal stool, but, ironically, it did not really gain attention as a human pathogen until the 1960s, when outbreaks were reported. Key technological advances, including in vitro cultivation, genomic and proteomic databases, and advances in microscopic and molecular approaches, have led to an understanding that this is a eukaryotic organism with a reduced genome rather than a truly premitochondriate eukaryote. This has included the discovery of mitosomes (vestiges of mitochondria), a transport system with many of the features of the Golgi apparatus, and even evidence for a sexual or parasexual cycle. Cell biology approaches have led to a better understanding of how Giardia survives with two nuclei and how it goes through its life cycle as a noninvasive organism in the hostile environment of the lumen of the host intestine. Studies of its immunology and pathogenesis have moved past the general understanding of the importance of the antibody response in controlling infection to determining the key role of the Th17 response. This work has led to understanding of the requirement for a balanced host immune response that avoids the extremes of an excessive response with collateral damage or one that is unable to clear the organism. This understanding is especially important in view of the remarkable ranges of early manifestations, which range from asymptomatic to persistent diarrhea and weight loss, and longer-term sequelae that include growth stunting in children who had no obvious symptoms and a high frequency of postinfectious irritable bowel syndrome (IBS).
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5
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Gibson W. The sexual side of parasitic protists. Mol Biochem Parasitol 2021; 243:111371. [PMID: 33872659 DOI: 10.1016/j.molbiopara.2021.111371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 03/26/2021] [Accepted: 04/13/2021] [Indexed: 01/09/2023]
Abstract
Much of the vast evolutionary landscape occupied by Eukaryotes is dominated by protists. Though parasitism has arisen in many lineages, there are three main groups of parasitic protists of relevance to human and livestock health: the Apicomplexa, including the malaria parasite Plasmodium and coccidian pathogens of livestock such as Eimeria; the excavate flagellates, encompassing a diverse range of protist pathogens including trypanosomes, Leishmania, Giardia and Trichomonas; and the Amoebozoa, including pathogenic amoebae such as Entamoeba. These three groups represent separate, deep branches of the eukaryote tree, underlining their divergent evolutionary histories. Here, I explore what is known about sex in these three main groups of parasitic protists.
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Affiliation(s)
- Wendy Gibson
- School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, BS8 1TQ, United Kingdom.
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6
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Pollo SMJ, Reiling SJ, Wit J, Workentine ML, Guy RA, Batoff GW, Yee J, Dixon BR, Wasmuth JD. Benchmarking hybrid assemblies of Giardia and prediction of widespread intra-isolate structural variation. Parasit Vectors 2020; 13:108. [PMID: 32111234 PMCID: PMC7048089 DOI: 10.1186/s13071-020-3968-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/13/2020] [Indexed: 01/02/2023] Open
Abstract
Background Currently available short read genome assemblies of the tetraploid protozoan parasite Giardia intestinalis are highly fragmented, highlighting the need for improved genome assemblies at a reasonable cost. Long nanopore reads are well suited to resolve repetitive genomic regions resulting in better quality assemblies of eukaryotic genomes. Subsequent addition of highly accurate short reads to long-read assemblies further improves assembly quality. Using this hybrid approach, we assembled genomes for three Giardia isolates, two with published assemblies and one novel, to evaluate the improvement in genome quality gained from long reads. We then used the long reads to predict structural variants to examine this previously unexplored source of genetic variation in Giardia. Methods With MinION reads for each isolate, we assembled genomes using several assemblers specializing in long reads. Assembly metrics, gene finding, and whole genome alignments to the reference genomes enabled direct comparison to evaluate the performance of the nanopore reads. Further improvements from adding Illumina reads to the long-read assemblies were evaluated using gene finding. Structural variants were predicted from alignments of the long reads to the best hybrid genome for each isolate and enrichment of key genes was analyzed using random genome sampling and calculation of percentiles to find thresholds of significance. Results Our hybrid assembly method generated reference quality genomes for each isolate. Consistent with previous findings based on SNPs, examination of heterozygosity using the structural variants found that Giardia BGS was considerably more heterozygous than the other isolates that are from Assemblage A. Further, each isolate was shown to contain structural variant regions enriched for variant-specific surface proteins, a key class of virulence factor in Giardia. Conclusions The ability to generate reference quality genomes from a single MinION run and a multiplexed MiSeq run enables future large-scale comparative genomic studies within the genus Giardia. Further, prediction of structural variants from long reads allows for more in-depth analyses of major sources of genetic variation within and between Giardia isolates that could have effects on both pathogenicity and host range.![]()
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Affiliation(s)
- Stephen M J Pollo
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.,Host-Parasite Interactions Training Program, University of Calgary, Calgary, AB, Canada
| | - Sarah J Reiling
- Bureau of Microbial Hazards, Food Directorate, Health Canada, Ottawa, ON, Canada
| | - Janneke Wit
- Host-Parasite Interactions Training Program, University of Calgary, Calgary, AB, Canada.,Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Matthew L Workentine
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Rebecca A Guy
- Division of Enteric Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Guelph, ON, Canada
| | - G William Batoff
- Department of Biology, Biochemistry and Molecular Biology Program, Trent University, Peterborough, ON, Canada
| | - Janet Yee
- Department of Biology, Biochemistry and Molecular Biology Program, Trent University, Peterborough, ON, Canada
| | - Brent R Dixon
- Bureau of Microbial Hazards, Food Directorate, Health Canada, Ottawa, ON, Canada
| | - James D Wasmuth
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada. .,Host-Parasite Interactions Training Program, University of Calgary, Calgary, AB, Canada.
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Mizuno T, Matey EJ, Bi X, Songok EM, Ichimura H, Tokoro M. Extremely diversified haplotypes observed among assemblage B population of Giardia intestinalis in Kenya. Parasitol Int 2019; 75:102038. [PMID: 31837398 DOI: 10.1016/j.parint.2019.102038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 12/09/2019] [Accepted: 12/10/2019] [Indexed: 12/15/2022]
Abstract
In molecular epidemiological studies of Giardia intestinalis, an pathogenic intestinal flagellate, due to the presence of allelic sequence heterogeneity (ASH) on the tetraploid genome, the image of haplotype diversity in the field remains uncertain. Here we employed the nine assemblage B positive stool samples, which had previously reported from Kenyan children, for the clonal sequence analysis of multiple gene loci (glutamate dehydrogenase (GDH), triosephosphate isomerase (TPI), and beta-giardin (BG)). The diversified unique assemblage B haplotypes as GDH (n = 67), TPI (n = 84), and BG (n = 62), and the assemblage A haplotypes as GDH (n = 7), TPI (n = 14), and BG (n = 15), which were hidden in the previous direct-sequence results, were detected. Among the assemblage B haplotypes, Bayesian phylogeny revealed multiple statistically significant clusters (9, 7, and 7 clusters for GDH, TPI, and BG, respectively). A part of the clusters (2 for GDH and 1 for BG), which included >4 haplotypes from an individual sample, indicated the presence of co-transmission with multiple strains sharing a recent ancestor. Locus-dependent discrepancies, such as different compositions of derived samples in clusters and different genotyping results for the assemblages, were also observed and considered to be the traces of both intra- and inter-assemblage genetic recombination respectively. Our clonal sequence analysis for giardial population, which applied firstly in Kenya, could reveal the higher rates of ASH far beyond the levels reported in other areas and address the complex population structure. The clonal analysis is indispensable for the molecular field study of G. intestinalis.
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Affiliation(s)
- Tetsushi Mizuno
- Department of Parasitology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | | | - Xiuqiong Bi
- Department of Viral Infection and International Health, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | | | - Hiroshi Ichimura
- Department of Viral Infection and International Health, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Masaharu Tokoro
- Department of Parasitology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan.
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8
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Maciver SK, Koutsogiannis Z, de Obeso Fernández Del Valle A. 'Meiotic genes' are constitutively expressed in an asexual amoeba and are not necessarily involved in sexual reproduction. Biol Lett 2019; 15:20180871. [PMID: 30836881 DOI: 10.1098/rsbl.2018.0871] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The amoebae (and many other protists) have traditionally been considered as asexual organisms, but suspicion has been growing that these organisms are cryptically sexual or are at least related to sexual lineages. This contention is mainly based on genome studies in which the presence of 'meiotic genes' has been discovered. Using RNA-seq (next-generation shotgun sequencing, identifying and quantifying the RNA species in a sample), we have found that the entire repertoire of meiotic genes is expressed in exponentially growing Acanthamoeba and we argue that these so-called meiotic genes are involved in the related process of homologous recombination in this amoeba. We contend that they are only involved in meiosis in other organisms that indulge in sexual reproduction and that homologous recombination is important in asexual protists as a guard against the accumulation of mutations. We also suggest that asexual reproduction is the ancestral state.
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Affiliation(s)
- Sutherland K Maciver
- Centre for Discovery Brain Sciences, Edinburgh Medical School, Biomedical Sciences, University of Edinburgh , Hugh Robson Building, George Square, Edinburgh EH8 9XD , UK
| | - Zisis Koutsogiannis
- Centre for Discovery Brain Sciences, Edinburgh Medical School, Biomedical Sciences, University of Edinburgh , Hugh Robson Building, George Square, Edinburgh EH8 9XD , UK
| | - Alvaro de Obeso Fernández Del Valle
- Centre for Discovery Brain Sciences, Edinburgh Medical School, Biomedical Sciences, University of Edinburgh , Hugh Robson Building, George Square, Edinburgh EH8 9XD , UK
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9
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Bernstein H, Bernstein C, Michod RE. Sex in microbial pathogens. INFECTION GENETICS AND EVOLUTION 2018; 57:8-25. [DOI: 10.1016/j.meegid.2017.10.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/25/2017] [Accepted: 10/26/2017] [Indexed: 10/18/2022]
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10
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Faria CP, Zanini GM, Dias GS, da Silva S, Sousa MDC. New multilocus genotypes of Giardia lamblia human isolates. INFECTION GENETICS AND EVOLUTION 2017; 54:128-137. [PMID: 28669825 DOI: 10.1016/j.meegid.2017.06.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 06/28/2017] [Accepted: 06/28/2017] [Indexed: 10/19/2022]
Abstract
Giardia lamblia is considered a species complex, whose members show little differences in their morphology, but have remarkable genetic variability. The aim of this study was to identify inter- and intra-assemblage genetic variation in G. lamblia among patients in Rio de Janeiro. The parasitological study was performed on faeces, and DNA was extracted from the samples which tested positive for G. lamblia. The genetic assemblages and subtypes were determined via multilocus sequence typing (MLST) using β-giardin, triose phosphate isomerase and glutamate dehydrogenase gene loci. Fourteen assemblage A samples were successfully genotyped at the three MLST loci (bg/tpi/gdh). Two previously identified multilocus genotypes were found (AII-1 and AII-4), and two novel multilocus genotypes are proposed (AII-8, profile A2/A2/A4; AII-9, profile A3/A2/A2). Sequence analysis showed that assemblage B isolates have a higher nucleotide variation than those from assemblage A. Novel assemblage B sequences are described and most (66.7%) have heterogeneous nucleotides, which prevent the definition of multilocus genotypes. This is the first time that MLST has been used to characterise G. lamblia isolates in human clinical samples from Rio de Janeiro. In addition, MLST has enabled the detection of novel subtypes in both assemblages and the description of two novel multilocus genotypes in assemblage A. This study provides new insights into the genetic diversity of assemblage A and shows that MLST should be used to characterise G. lamblia both in Brazil and globally.
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Affiliation(s)
- Clarissa Perez Faria
- CNC - Center for Neurosciences and Cell Biology, University of Coimbra, 3030-548 Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, 3030-548 Coimbra, Portugal; Laboratory of Parasitology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, 21040-900, Brazil
| | - Graziela Maria Zanini
- Laboratory of Parasitology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, 21040-900, Brazil
| | - Gisele Silva Dias
- Laboratory of Parasitology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, 21040-900, Brazil
| | - Sidnei da Silva
- Laboratory of Parasitology, Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, 21040-900, Brazil
| | - Maria do Céu Sousa
- CNC - Center for Neurosciences and Cell Biology, University of Coimbra, 3030-548 Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, 3030-548 Coimbra, Portugal.
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Gabín-García LB, Bartolomé C, Abal-Fabeiro JL, Méndez S, Llovo J, Maside X. Strong genetic structure revealed by multilocus patterns of variation in Giardia duodenalis isolates of patients from Galicia (NW-Iberian Peninsula). INFECTION GENETICS AND EVOLUTION 2016; 48:131-141. [PMID: 27993728 DOI: 10.1016/j.meegid.2016.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/28/2016] [Accepted: 12/13/2016] [Indexed: 10/20/2022]
Abstract
We report a survey of genetic variation at three coding loci in Giardia duodenalis of assemblages A and B obtained from stool samples of patients from Santiago de Compostela (Galicia, NW-Iberian Peninsula). The mean pooled synonymous diversity for assemblage A was nearly five times lower than for assemblage B (0.77%±0.30% and 4.14%±1.65%, respectively). Synonymous variation in both assemblages was in mutation-drift equilibrium and an excess of low-frequency nonsynonymous variants suggested the action of purifying selection at the three loci. Differences between isolates contributed to 40% and 60% of total genetic variance in assemblages A and B, respectively, which revealed a significant genetic structure. These results, together with the lack of evidence for recombination, support that (i) Giardia assemblages A and B are in demographic equilibrium and behave as two genetically isolated populations, (ii) infections are initiated by a reduced number of individuals, which may be genetically diverse and even belong to different assemblages, and (iii) parasites reproduce clonally within the host. However, the observation of invariant loci in some isolates means that mechanisms for the homogenization of the genetic content of the two diploid nuclei in each individual must exist.
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Affiliation(s)
- Luis B Gabín-García
- Grupo de Medicina Xenómica, Centro de Investigación en Medicina Molecular e Enfermidades Crónicas da Universidade de Santiago de Compostela (CIMUS), Avda. Barcelona s/n, 15782 Santiago, Galicia, Spain; Xenómica Comparada de Parasitos Humanos, Instituto de Investigacións Sanitarias de Santiago (IDIS), Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain.
| | - Carolina Bartolomé
- Grupo de Medicina Xenómica, Centro de Investigación en Medicina Molecular e Enfermidades Crónicas da Universidade de Santiago de Compostela (CIMUS), Avda. Barcelona s/n, 15782 Santiago, Galicia, Spain; Xenómica Comparada de Parasitos Humanos, Instituto de Investigacións Sanitarias de Santiago (IDIS), Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain
| | - José L Abal-Fabeiro
- Grupo de Medicina Xenómica, Centro de Investigación en Medicina Molecular e Enfermidades Crónicas da Universidade de Santiago de Compostela (CIMUS), Avda. Barcelona s/n, 15782 Santiago, Galicia, Spain; Xenómica Comparada de Parasitos Humanos, Instituto de Investigacións Sanitarias de Santiago (IDIS), Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain
| | - Santiago Méndez
- Xenómica Comparada de Parasitos Humanos, Instituto de Investigacións Sanitarias de Santiago (IDIS), Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain; Servizo de Microbioloxía e Parasitoloxía, Complexo Hospitalario Universitario de Santiago, Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain
| | - José Llovo
- Xenómica Comparada de Parasitos Humanos, Instituto de Investigacións Sanitarias de Santiago (IDIS), Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain; Servizo de Microbioloxía e Parasitoloxía, Complexo Hospitalario Universitario de Santiago, Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain
| | - Xulio Maside
- Grupo de Medicina Xenómica, Centro de Investigación en Medicina Molecular e Enfermidades Crónicas da Universidade de Santiago de Compostela (CIMUS), Avda. Barcelona s/n, 15782 Santiago, Galicia, Spain; Xenómica Comparada de Parasitos Humanos, Instituto de Investigacións Sanitarias de Santiago (IDIS), Travesia da Choupana s/n, 15706 Santiago, Galicia, Spain
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12
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Tibayrenc M, Ayala FJ. Is Predominant Clonal Evolution a Common Evolutionary Adaptation to Parasitism in Pathogenic Parasitic Protozoa, Fungi, Bacteria, and Viruses? ADVANCES IN PARASITOLOGY 2016; 97:243-325. [PMID: 28325372 DOI: 10.1016/bs.apar.2016.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We propose that predominant clonal evolution (PCE) in microbial pathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure. The main features of PCE are (1) strong linkage disequilibrium, (2) the widespread occurrence of stable genetic clusters blurred by occasional bouts of genetic exchange ('near-clades'), (3) the existence of a "clonality threshold", beyond which recombination is efficiently countered by PCE, and near-clades irreversibly diverge. We hypothesize that the PCE features are not mainly due to natural selection but also chiefly originate from in-built genetic properties of pathogens. We show that the PCE model obtains even in microbes that have been considered as 'highly recombining', such as Neisseria meningitidis, and that some clonality features are observed even in Plasmodium, which has been long described as panmictic. Lastly, we provide evidence that PCE features are also observed in viruses, taking into account their extremely fast genetic turnover. The PCE model provides a convenient population genetic framework for any kind of micropathogen. It makes it possible to describe convenient units of analysis (clones and near-clades) for all applied studies. Due to PCE features, these units of analysis are stable in space and time, and clearly delimited. The PCE model opens up the possibility of revisiting the problem of species definition in these organisms. We hypothesize that PCE constitutes a major evolutionary strategy for protozoa, fungi, bacteria, and viruses to adapt to parasitism.
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Affiliation(s)
- M Tibayrenc
- Institut de Recherche pour le Développement, Montpellier, France
| | - F J Ayala
- University of California at Irvine, United States
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13
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Thompson R, Ash A. Molecular epidemiology of Giardia and Cryptosporidium infections. INFECTION GENETICS AND EVOLUTION 2016; 40:315-323. [DOI: 10.1016/j.meegid.2015.09.028] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 09/23/2015] [Accepted: 09/24/2015] [Indexed: 11/28/2022]
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14
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Maside X, Gómez-Moracho T, Jara L, Martín-Hernández R, De la Rúa P, Higes M, Bartolomé C. Population Genetics of Nosema apis and Nosema ceranae: One Host (Apis mellifera) and Two Different Histories. PLoS One 2015; 10:e0145609. [PMID: 26720131 PMCID: PMC4699903 DOI: 10.1371/journal.pone.0145609] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 12/07/2015] [Indexed: 12/26/2022] Open
Abstract
Two microsporidians are known to infect honey bees: Nosema apis and Nosema ceranae. Whereas population genetics data for the latter have been released in the last few years, such information is still missing for N. apis. Here we analyze the patterns of nucleotide polymorphism at three single-copy loci (PTP2, PTP3 and RPB1) in a collection of Apis mellifera isolates from all over the world, naturally infected either with N. apis (N = 22) or N. ceranae (N = 23), to provide new insights into the genetic diversity, demography and evolution of N. apis, as well as to compare them with evidence from N. ceranae. Neutral variation in N. apis and N. ceranae is of the order of 1%. This amount of diversity suggests that there is no substantial differentiation between the genetic content of the two nuclei present in these parasites, and evidence for genetic recombination provides a putative mechanism for the flow of genetic information between chromosomes. The analysis of the frequency spectrum of neutral variants reveals a significant surplus of low frequency variants, particularly in N. ceranae, and suggests that the populations of the two pathogens are not in mutation-drift equilibrium and that they have experienced a population expansion. Most of the variation in both species occurs within honey bee colonies (between 62%-90% of the total genetic variance), although in N. apis there is evidence for differentiation between parasites isolated from distinct A. mellifera lineages (20%-34% of the total variance), specifically between those collected from lineages A and C (or M). This scenario is consistent with a long-term host-parasite relationship and contrasts with the lack of differentiation observed among host-lineages in N. ceranae (< 4% of the variance), which suggests that the spread of this emergent pathogen throughout the A. mellifera worldwide population is a recent event.
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Affiliation(s)
- Xulio Maside
- Medicina Xenómica, CIMUS, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
- Xenómica Comparada de Parásitos Humanos, IDIS, Santiago de Compostela, Galicia, Spain
- Departamento de Anatomía Patolóxica e Ciencias Forenses, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
| | - Tamara Gómez-Moracho
- Medicina Xenómica, CIMUS, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
- Xenómica Comparada de Parásitos Humanos, IDIS, Santiago de Compostela, Galicia, Spain
- Laboratorio de Patología Apícola. Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Marchamalo, Guadalajara, Spain
| | - Laura Jara
- Departamento de Zoología y Antropología Física, Facultad de Veterinaria, Universidad de Murcia, Murcia, Spain
| | - Raquel Martín-Hernández
- Laboratorio de Patología Apícola. Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Marchamalo, Guadalajara, Spain
- Instituto de Recursos Humanos para la Ciencia y la Tecnología (INCRECYT-FEDER), Fundación Parque Científico y Tecnológico de Albacete, Albacete, Spain
| | - Pilar De la Rúa
- Departamento de Zoología y Antropología Física, Facultad de Veterinaria, Universidad de Murcia, Murcia, Spain
| | - Mariano Higes
- Laboratorio de Patología Apícola. Centro de Investigación Apícola y Agroambiental (CIAPA), Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal (IRIAF), Consejería de Agricultura de la Junta de Comunidades de Castilla-La Mancha, Marchamalo, Guadalajara, Spain
| | - Carolina Bartolomé
- Medicina Xenómica, CIMUS, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain
- Xenómica Comparada de Parásitos Humanos, IDIS, Santiago de Compostela, Galicia, Spain
- * E-mail:
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Tibayrenc M, Ayala FJ. The population genetics of Trypanosoma cruzi revisited in the light of the predominant clonal evolution model. Acta Trop 2015; 151:156-65. [PMID: 26188332 PMCID: PMC7117470 DOI: 10.1016/j.actatropica.2015.05.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 05/02/2015] [Accepted: 05/06/2015] [Indexed: 01/18/2023]
Abstract
Comparing the population structure of Trypanosoma cruzi with that of other pathogens, including parasitic protozoa, fungi, bacteria and viruses, shows that the agent of Chagas disease shares typical traits with many other species, related to a predominant clonal evolution (PCE) pattern: statistically significant linkage disequilibrium, overrepresented multilocus genotypes, near-clades (genetic subdivisions somewhat blurred by occasional genetic exchange/hybridization) and "Russian doll" patterns (PCE is observed, not only at the level of the whole species, but also, within the near-clades). Moreover, T. cruzi population structure exhibits linkage with the diversity of several strongly selected genes, with gene expression profiles, and with some major phenotypic traits. We discuss the evolutionary significance of these results, and their implications in terms of applied research (molecular epidemiology/strain typing, analysis of genes of interest, vaccine and drug design, immunological diagnosis) and of experimental evolution. Lastly, we revisit the long-term debate of describing new species within the T. cruzi taxon.
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Rougeron V, De Meeûs T, Bañuls AL. Response to Tibayrenc et al.: can recombination in Leishmania parasites be so rare? Trends Parasitol 2015; 31:280-1. [PMID: 26142922 DOI: 10.1016/j.pt.2015.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/11/2015] [Accepted: 05/13/2015] [Indexed: 11/20/2022]
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Barratt JLN, Cao M, Stark DJ, Ellis JT. The Transcriptome Sequence of Dientamoeba fragilis Offers New Biological Insights on its Metabolism, Kinome, Degradome and Potential Mechanisms of Pathogenicity. Protist 2015; 166:389-408. [PMID: 26188431 DOI: 10.1016/j.protis.2015.06.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 05/27/2015] [Accepted: 06/13/2015] [Indexed: 01/08/2023]
Abstract
Dientamoeba fragilis is a human bowel parasite with a worldwide distribution. Dientamoeba was once described as a rare and harmless commensal though recent reports suggest it is common and potentially pathogenic. Molecular data on Dientamoeba is scarce which limits our understanding of this parasite. To address this, sequencing of the Dientamoeba transcriptome was performed. Messenger RNA was extracted from cultured Dientamoeba trophozoites originating from clinical stool specimens, and sequenced using Roche GS FLX and Illumina HiSeq technologies. In total 6,595 Dientamoeba transcripts were identified. These sequences were analysed using the BLAST2GO software suite and via BLAST comparisons to sequences available from TrichDB, GenBank, MEROPS and kinase.com. Several novel KEGG pathway maps were generated and gene ontology analysis was also performed. These results are thoroughly discussed guided by knowledge available for other related protozoa. Attention is paid to the novel biological insights afforded by this data including peptidases and kinases of Dientamoeba, as well as its metabolism, novel chemotherapeutics and possible mechanisms of pathogenicity. Currently, this work represents the largest contribution to our understanding of Dientamoeba molecular biology and also represents a major contribution to our understanding of the trichomonads generally, many of which are important pathogens of humans and animals.
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Affiliation(s)
- Joel L N Barratt
- University of Technology Sydney, iThree Institute, Broadway, New South Wales 2007, Australia; University of Technology Sydney, School of Life Sciences, Broadway, New South Wales 2007, Australia.
| | - Maisie Cao
- University of Technology Sydney, School of Life Sciences, Broadway, New South Wales 2007, Australia
| | - Damien J Stark
- University of Technology Sydney, School of Life Sciences, Broadway, New South Wales 2007, Australia; Division of Microbiology, Sydpath, St. Vincent's Hospital, Darlinghurst, New South Wales 2010, Australia
| | - John T Ellis
- University of Technology Sydney, School of Life Sciences, Broadway, New South Wales 2007, Australia
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Parasexuality and mosaic aneuploidy in Leishmania: alternative genetics. Trends Parasitol 2014; 30:429-35. [PMID: 25073852 DOI: 10.1016/j.pt.2014.07.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 12/25/2022]
Abstract
Reproduction as identical or similar organisms in most biological systems depends on the extreme accuracy of the mitotic (and meiotic) mechanisms involved in the transmission of the genetic material to the two daughter cells. Character recombination and genotype diversification are ensured by the alternation between haploidy and diploidy, which corresponds to the most predominant model in sexually reproducing organisms. In Leishmania, the unique association of high levels of automixis and of constitutive 'mosaic aneuploidy' unexpectedly does not lead to loss of heterozygosity but constitutes an alternative for genotype recombination, hence a source of adaptability.
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Tibayrenc M, Ayala FJ. Cryptosporidium,Giardia, Cryptococcus, Pneumocystis genetic variability: cryptic biological species or clonal near-clades? PLoS Pathog 2014; 10:e1003908. [PMID: 24722548 PMCID: PMC3983055 DOI: 10.1371/journal.ppat.1003908] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
An abundant literature dealing with the population genetics and taxonomy of Giardia duodenalis, Cryptosporidium spp., Pneumocystis spp., and Cryptococcus spp., pathogens of high medical and veterinary relevance, has been produced in recent years. We have analyzed these data in the light of new population genetic concepts dealing with predominant clonal evolution (PCE) recently proposed by us. In spite of the considerable phylogenetic diversity that exists among these pathogens, we have found striking similarities among them. The two main PCE features described by us, namely highly significant linkage disequilibrium and near-clading (stable phylogenetic clustering clouded by occasional recombination), are clearly observed in Cryptococcus and Giardia, and more limited indication of them is also present in Cryptosporidium and Pneumocystis. Moreover, in several cases, these features still obtain when the near-clades that subdivide the species are analyzed separately (“Russian doll pattern”). Lastly, several sets of data undermine the notion that certain microbes form clonal lineages simply owing to a lack of opportunity to outcross due to low transmission rates leading to lack of multiclonal infections (“starving sex hypothesis”). We propose that the divergent taxonomic and population genetic inferences advanced by various authors about these pathogens may not correspond to true evolutionary differences and could be, rather, the reflection of idiosyncratic practices among compartmentalized scientific communities. The PCE model provides an opportunity to revise the taxonomy and applied research dealing with these pathogens and others, such as viruses, bacteria, parasitic protozoa, and fungi. Micropathogen species definition is extremely difficult, since concepts applied to higher organisms (the biological species concept) are inadequate. In particular, the pathogens here surveyed have given rise to long-lasting controversies about their species status and that of the genotypes that subdivide them. The population genetic approach based on the predominant clonal evolution (PCE) concept proposed by us could bring simple solutions to these controversies, since it permits the description of clearly defined evolutionary entities (clonal multilocus genotypes and near-clades [incompletely isolated clades]) that could be the basis for species description, if the concerned specialists find it justified for applied research. The PCE model also provides a convenient framework for applied studies (molecular epidemiology, vaccine and drug design, clinical research) dealing with these pathogens and others.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), IRD Center, BP 64501, Montpellier, France
- * E-mail:
| | - Francisco J. Ayala
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, United States of America
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Raj D, Ghosh E, Mukherjee AK, Nozaki T, Ganguly S. Differential gene expression in Giardia lamblia under oxidative stress: Significance in eukaryotic evolution. Gene 2014; 535:131-9. [DOI: 10.1016/j.gene.2013.11.048] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/31/2013] [Accepted: 11/20/2013] [Indexed: 11/25/2022]
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Ramírez JD, Tapia-Calle G, Guhl F. Genetic structure of Trypanosoma cruzi in Colombia revealed by a High-throughput Nuclear Multilocus Sequence Typing (nMLST) approach. BMC Genet 2013; 14:96. [PMID: 24079755 PMCID: PMC3850472 DOI: 10.1186/1471-2156-14-96] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 09/25/2013] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Chagas disease is a systemic pathology caused by Trypanosoma cruzi. This parasite reveals remarkable genetic variability, evinced in six Discrete Typing Units (DTUs) named from T. cruzi I to T. cruzi VI (TcI to TcVI). Recently newly identified genotypes have emerged such as TcBat in Brazil, Colombia and Panama associated to anthropogenic bats. The genotype with the broadest geographical distribution is TcI, which has recently been associated to severe cardiomyopathies in Argentina and Colombia. Therefore, new studies unraveling the genetic structure and natural history of this DTU must be pursued. RESULTS We conducted a spatial and temporal analysis on 50 biological clones of T. cruzi I (TcI) isolated from humans with different clinical phenotypes, triatomine bugs and mammal reservoirs across three endemic regions for Chagas disease in Colombia. These clones were submitted to a nuclear Multilocus Sequence Typing (nMLST) analysis in order to elucidate its genetic diversity and clustering. After analyzing 13 nuclear housekeeping genes and obtaining a 5821 bp length alignment, we detected two robust genotypes within TcI henceforth named TcIDOM (associated to human infections) and a second cluster associated to peridomestic and sylvatic populations. Additionaly, we detected putative events of recombination and an intriguing lack of linkage disequilibrium. CONCLUSIONS These findings reinforce the emergence of an enigmatic domestic T. cruzi genotype (TcIDOM), and demonstrates the high frequency of recombination at nuclear level across natural populations of T. cruzi. Therefore, the need to pursue studies focused on the diferential virulence profiles of TcI strains. The biological and epidemiological implications of these findings are herein discussed.
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Affiliation(s)
- Juan David Ramírez
- Centro de Investigaciones en Microbiología y Parasitología Tropical (CIMPAT), Universidad de Los Andes, Bogotá, Colombia.
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Tibayrenc M, Ayala FJ. Reproductive clonality of pathogens: a perspective on pathogenic viruses, bacteria, fungi, and parasitic protozoa. Proc Natl Acad Sci U S A 2012; 109:E3305-13. [PMID: 22949662 PMCID: PMC3511763 DOI: 10.1073/pnas.1212452109] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We propose that clonal evolution in micropathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure, a definition already widely used for all kinds of pathogens, although not clearly formulated by many scientists and rejected by others. The two main manifestations of clonal evolution are strong linkage disequilibrium (LD) and widespread genetic clustering ("near-clading"). We hypothesize that this pattern is not mainly due to natural selection, but originates chiefly from in-built genetic properties of pathogens, which could be ancestral and could function as alternative allelic systems to recombination genes ("clonality/sexuality machinery") to escape recombinational load. The clonal framework of species of pathogens should be ascertained before any analysis of biomedical phenotypes (phylogenetic character mapping). In our opinion, this model provides a conceptual framework for the population genetics of any micropathogen.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, Institut de Rercherche pour le Développement 224, Centre National de la Recherche Scientifique 5290, Universités Montpellier 1 and 2, 34394 Montpellier Cedex 5, France; and
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
| | - Francisco J. Ayala
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
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Haag KL, Traunecker E, Ebert D. Single-nucleotide polymorphisms of two closely related microsporidian parasites suggest a clonal population expansion after the last glaciation. Mol Ecol 2012; 22:314-26. [PMID: 23163569 DOI: 10.1111/mec.12126] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 10/03/2012] [Accepted: 10/07/2012] [Indexed: 11/27/2022]
Abstract
The mode of reproduction of microsporidian parasites has remained puzzling since many decades. It is generally accepted that microsporidia are capable of sexual reproduction, and that some species have switched to obligate asexuality, but such process had never been supported with population genetic evidence. We examine the mode of reproduction of Hamiltosporidium tvaerminnensis and Hamiltosporidium magnivora, two closely related microsporidian parasites of the widespread freshwater crustacean Daphnia magna, based on a set of 129 single-nucleotide polymorphisms distributed across 16 genes. We analyse 20 H. tvaerminnensis isolates from localities representative of the entire species' geographic distribution along the Skerry Island belt of the Baltic Sea. Five isolates of the sister species H. magnivora were used for comparison. We estimate the recombination rates in H. tvaerminnensis to be at least eight orders of magnitude lower than in H. magnivora and not significantly different from zero. This is corroborated by the higher divergence between H. tvaerminnensis alleles (including fixed heterozygosity), as compared to H. magnivora. Our study confirms that sexual recombination is present in microsporidia, that it can be lost, and that asexuals may become epidemic.
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Affiliation(s)
- Karen L Haag
- Zoological Institute, University of Basel, Vesalgasse 1, CH-4051, Basel, Switzerland.
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Takumi K, Swart A, Mank T, Lasek-Nesselquist E, Lebbad M, Cacciò SM, Sprong H. Population-based analyses of Giardia duodenalis is consistent with the clonal assemblage structure. Parasit Vectors 2012; 5:168. [PMID: 22882997 PMCID: PMC3431248 DOI: 10.1186/1756-3305-5-168] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 08/01/2012] [Indexed: 01/21/2023] Open
Abstract
Background Giardia duodenalis is a common protozoan parasite of humans and animals. Genetic characterization of single loci indicates the existence of eight groups called assemblages, which differ in their host distribution. Molecular analyses challenged the idea that G. duodenalis is a strictly clonal diplomonad by providing evidence of recombination within and between assemblages. Particularly, inter-assemblage recombination events would complicate the interpretation of multi-locus genotyping data from field isolates: where is a host infected with multiple Giardia genotypes or with a single, recombined Giardia genotype. Methods Population genetic analyses on the single and multiple-locus level on an extensive dataset of G. duodenalis isolates from humans and animals were performed. Results Our analyses indicate that recombination between isolates from different assemblages are apparently very rare or absent in the natural population of Giardia duodenalis. At the multi-locus level, our statistical analyses are more congruent with clonal reproduction and can equally well be explained with the presence of multiple G. duodenalis genotypes within one field isolate. Conclusions We conclude that recombination between G. duodenalis assemblages is either very rare or absent. Recombination between genotypes from the same assemblage and genetic exchange between the nuclei of a single cyst needs further investigation.
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Affiliation(s)
- Katsuhisa Takumi
- National Institute of Public Health and Environment (RIVM), Laboratory for Zoonosis and Environmental Microbiology (CIb-LZO), P.O. Box 1, 3720, BA, Bilthoven, The Netherlands
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RAMÍREZ JUANDAVID, GUHL FELIPE, MESSENGER LOUISAA, LEWIS MICHAELD, MONTILLA MARLENY, CUCUNUBA ZULMA, MILES MICHAELA, LLEWELLYN MARTINS. Contemporary cryptic sexuality inTrypanosoma cruzi. Mol Ecol 2012; 21:4216-26. [DOI: 10.1111/j.1365-294x.2012.05699.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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26
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Ankarklev J, Svärd SG, Lebbad M. Allelic sequence heterozygosity in single Giardia parasites. BMC Microbiol 2012; 12:65. [PMID: 22554281 PMCID: PMC3438080 DOI: 10.1186/1471-2180-12-65] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 05/03/2012] [Indexed: 12/17/2022] Open
Abstract
Background Genetic heterogeneity has become a major inconvenience in the genotyping and molecular epidemiology of the intestinal protozoan parasite Giardia intestinalis, in particular for the major human infecting genotype, assemblage B. Sequence-based genotyping of assemblage B Giardia from patient fecal samples, where one or several of the commonly used genotyping loci (beta-giardin, triosephosphate isomerase and glutamate dehydrogenase) are implemented, is often hampered due to the presence of sequence heterogeneity in the sequencing chromatograms. This can be due to allelic sequence heterozygosity (ASH) and /or co-infections with parasites of different assemblage B sub-genotypes. Thus, two important questions have arisen; i) does ASH occur at the single cell level, and/or ii) do multiple sub-genotype infections commonly occur in patients infected with assemblage B, G. intestinalis isolates? Results We used micromanipulation in order to isolate single Giardia intestinalis, assemblage B trophozoites (GS isolate) and cysts from human patients. Molecular analysis at the tpi loci of trophozoites from the GS lineage indicated that ASH is present at the single cell level. Analyses of assemblage B Giardia cysts from clinical samples at the bg and tpi loci also indicated ASH at the single cell level. Additionally, alignment of sequence data from several different cysts that originated from the same patient yielded different sequence patterns, thus suggesting the presence of multiple sub-assemblage infections in congruence with ASH within the same patient. Conclusions Our results conclusively show that ASH does occur at the single cell level in assemblage B Giardia. Furthermore, sequence heterogeneity generated during sequence-based genotyping of assemblage B isolates may possess the complexity of single cell ASH in concurrence with co-infections of different assemblage B sub-genotypes. These findings explain the high abundance of sequence heterogeneity commonly found when performing sequence based genotyping of assemblage B Giardia, and illuminates the necessity of developing new G. intestinalis genotyping tools.
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Affiliation(s)
- Johan Ankarklev
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.
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Xu F, Jerlstrom-Hultqvist J, Andersson JO. Genome-Wide Analyses of Recombination Suggest That Giardia intestinalis Assemblages Represent Different Species. Mol Biol Evol 2012; 29:2895-8. [DOI: 10.1093/molbev/mss107] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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28
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Carpenter ML, Assaf ZJ, Gourguechon S, Cande WZ. Nuclear inheritance and genetic exchange without meiosis in the binucleate parasite Giardia intestinalis. J Cell Sci 2012; 125:2523-32. [PMID: 22366460 DOI: 10.1242/jcs.103879] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The protozoan parasite Giardia intestinalis (also known as Giardia lamblia) is a major waterborne pathogen. During its life cycle, Giardia alternates between the actively growing trophozoite, which has two diploid nuclei with low levels of allelic heterozygosity, and the infectious cyst, which has four nuclei and a tough outer wall. Although the formation of the cyst wall has been studied extensively, we still lack basic knowledge about many fundamental aspects of the cyst, including the sources of the four nuclei and their distribution during the transformation from cyst into trophozoite. In this study, we tracked the identities of the nuclei in the trophozoite and cyst using integrated nuclear markers and immunofluorescence staining. We demonstrate that the cyst is formed from a single trophozoite by a mitotic division without cytokinesis and not by the fusion of two trophozoites. During excystation, the cell completes cytokinesis to form two daughter trophozoites. The non-identical nuclear pairs derived from the parent trophozoite remain associated in the cyst and are distributed to daughter cells during excystation as pairs. Thus, nuclear sorting (such that each daughter cell receives a pair of identical nuclei) does not appear to be a mechanism by which Giardia reduces heterozygosity between its nuclei. Rather, we show that the cyst nuclei exchange chromosomal genetic material, perhaps as a way to reduce heterozygosity in the absence of meiosis and sex, which have not been described in Giardia. These results shed light on fundamental aspects of the Giardia life cycle and have implications for our understanding of the population genetics and cell biology of this binucleate parasite.
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Affiliation(s)
- Meredith L Carpenter
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Double peaks reveal rare diplomonad sex. Trends Parasitol 2012; 28:46-52. [DOI: 10.1016/j.pt.2011.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/16/2011] [Accepted: 11/17/2011] [Indexed: 01/23/2023]
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30
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Weedall GD, Clark CG, Koldkjaer P, Kay S, Bruchhaus I, Tannich E, Paterson S, Hall N. Genomic diversity of the human intestinal parasite Entamoeba histolytica. Genome Biol 2012; 13:R38. [PMID: 22630046 PMCID: PMC3446291 DOI: 10.1186/gb-2012-13-5-r38] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 04/29/2012] [Accepted: 05/25/2012] [Indexed: 11/10/2022] Open
Abstract
Background Results Conclusions
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Jiráková K, Kulda J, Nohýnková E. How nuclei of Giardia pass through cell differentiation: semi-open mitosis followed by nuclear interconnection. Protist 2011; 163:465-79. [PMID: 22209008 DOI: 10.1016/j.protis.2011.11.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 11/10/2011] [Indexed: 12/30/2022]
Abstract
Differentiation into infectious cysts (encystation) and multiplication of pathogenic trophozoites after hatching from the cyst (excystation) are fundamental processes in the life cycle of the human intestinal parasite Giardia intestinalis. During encystation, a bi-nucleated trophozoite transforms to a dormant tetra-nucleated cyst enveloped by a protective cyst wall. Nuclear division during encystation is not followed by cytokinesis. In contrast to the well-studied mechanism of cyst wall formation, information on nuclei behavior is incomplete and basic cytological data are lacking. Here we present evidence that (1) the nuclei divide by semi-open mitosis during early encystment; (2) the daughter nuclei coming from different parent nuclei are always arranged in pairs; (3) in both pairs, the nuclei are interconnected via bridges formed by fusion of their nuclear envelopes; (4) each interconnected nuclear pair is associated with one basal body tetrad of the undivided diplomonad mastigont; and (5) the interconnection between nuclei persists through the cyst stage being a characteristic feature of encysted Giardia. Based on the presented results, a model of nuclei behavior during Giardia differentiation is proposed.
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Affiliation(s)
- Klára Jiráková
- Department of Tropical Medicine, 1(st) Faculty of Medicine, Charles University in Prague and Faculty Hospital Bulovka, Studnickova 7, Prague 2, 128 00, Czech Republic
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Lahr DJG, Parfrey LW, Mitchell EAD, Katz LA, Lara E. The chastity of amoebae: re-evaluating evidence for sex in amoeboid organisms. Proc Biol Sci 2011; 278:2081-90. [PMID: 21429931 PMCID: PMC3107637 DOI: 10.1098/rspb.2011.0289] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 03/04/2011] [Indexed: 11/12/2022] Open
Abstract
Amoebae are generally assumed to be asexual. We argue that this view is a relict of early classification schemes that lumped all amoebae together inside the 'lower' protozoa, separated from the 'higher' plants, animals and fungi. This artificial classification allowed microbial eukaryotes, including amoebae, to be dismissed as primitive, and implied that the biological rules and theories developed for macro-organisms need not apply to microbes. Eukaryotic diversity is made up of 70+ lineages, most of which are microbial. Plants, animals and fungi are nested among these microbial lineages. Thus, theories on the prevalence and maintenance of sex developed for macro-organisms should in fact apply to microbial eukaryotes, though the theories may need to be refined and generalized (e.g. to account for the variation in sexual strategies and prevalence of facultative sex in natural populations of many microbial eukaryotes). We use a revised phylogenetic framework to assess evidence for sex in several amoeboid lineages that are traditionally considered asexual, and we interpret this evidence in light of theories on the evolution of sex developed for macro-organisms. We emphasize that the limited data available for many lineages coupled with natural variation in microbial life cycles overestimate the extent of asexuality. Mapping sexuality onto the eukaryotic tree of life demonstrates that the majority of amoeboid lineages are, contrary to popular belief, anciently sexual, and that most asexual groups have probably arisen recently and independently. Additionally, several unusual genomic traits are prevalent in amoeboid lineages, including cyclic polyploidy, which may serve as alternative mechanisms to minimize the deleterious effects of asexuality.
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Affiliation(s)
- Daniel J. G. Lahr
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Laura Wegener Parfrey
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Edward A. D. Mitchell
- Laboratory of Soil Biology, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Laura A. Katz
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, USA
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA
| | - Enrique Lara
- Laboratory of Soil Biology, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
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Lahr DJG, Parfrey LW, Mitchell EAD, Katz LA, Lara E. The chastity of amoebae: re-evaluating evidence for sex in amoeboid organisms. Proc Biol Sci 2011. [PMID: 21429931 DOI: 10.1098/rspb.2011.0289)10.1098/rspb.2011.0289)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Amoebae are generally assumed to be asexual. We argue that this view is a relict of early classification schemes that lumped all amoebae together inside the 'lower' protozoa, separated from the 'higher' plants, animals and fungi. This artificial classification allowed microbial eukaryotes, including amoebae, to be dismissed as primitive, and implied that the biological rules and theories developed for macro-organisms need not apply to microbes. Eukaryotic diversity is made up of 70+ lineages, most of which are microbial. Plants, animals and fungi are nested among these microbial lineages. Thus, theories on the prevalence and maintenance of sex developed for macro-organisms should in fact apply to microbial eukaryotes, though the theories may need to be refined and generalized (e.g. to account for the variation in sexual strategies and prevalence of facultative sex in natural populations of many microbial eukaryotes). We use a revised phylogenetic framework to assess evidence for sex in several amoeboid lineages that are traditionally considered asexual, and we interpret this evidence in light of theories on the evolution of sex developed for macro-organisms. We emphasize that the limited data available for many lineages coupled with natural variation in microbial life cycles overestimate the extent of asexuality. Mapping sexuality onto the eukaryotic tree of life demonstrates that the majority of amoeboid lineages are, contrary to popular belief, anciently sexual, and that most asexual groups have probably arisen recently and independently. Additionally, several unusual genomic traits are prevalent in amoeboid lineages, including cyclic polyploidy, which may serve as alternative mechanisms to minimize the deleterious effects of asexuality.
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Affiliation(s)
- Daniel J G Lahr
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, USA.
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Zoonotic potential and molecular epidemiology of Giardia species and giardiasis. Clin Microbiol Rev 2011; 24:110-40. [PMID: 21233509 DOI: 10.1128/cmr.00033-10] [Citation(s) in RCA: 804] [Impact Index Per Article: 61.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Molecular diagnostic tools have been used recently in assessing the taxonomy, zoonotic potential, and transmission of Giardia species and giardiasis in humans and animals. The results of these studies have firmly established giardiasis as a zoonotic disease, although host adaptation at the genotype and subtype levels has reduced the likelihood of zoonotic transmission. These studies have also identified variations in the distribution of Giardia duodenalis genotypes among geographic areas and between domestic and wild ruminants and differences in clinical manifestations and outbreak potentials of assemblages A and B. Nevertheless, our efforts in characterizing the molecular epidemiology of giardiasis and the roles of various animals in the transmission of human giardiasis are compromised by the lack of case-control and longitudinal cohort studies and the sampling and testing of humans and animals living in the same community, the frequent occurrence of infections with mixed genotypes and subtypes, and the apparent heterozygosity at some genetic loci for some G. duodenalis genotypes. With the increased usage of multilocus genotyping tools, the development of next-generation subtyping tools, the integration of molecular analysis in epidemiological studies, and an improved understanding of the population genetics of G. duodenalis in humans and animals, we should soon have a better appreciation of the molecular epidemiology of giardiasis, the disease burden of zoonotic transmission, the taxonomy status and virulences of various G. duodenalis genotypes, and the ecology of environmental contamination.
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Abstract
PURPOSE OF REVIEW To update the reader on the latest developments in the laboratory diagnosis of intestinal protozoa. RECENT FINDINGS Correct identification of a diarrhoea causing pathogens is essential for the choice of treatment in an individual patient as well as to map the aetiology of diarrhoea in a variety of patient populations. Classical diagnosis of diarrhoea causing protozoa by microscopic examination of a stool sample lacks both sensitivity and specificity. Alternative diagnostic platforms are discussed. SUMMARY Recent literature on the diagnosis of intestinal protozoa has focused mainly on nucleic acid-based assays, in particular the specific detection of parasite DNA in stool samples using real-time PCR. In addition, the trend has been moving from single pathogen detection to a multiplex approach, allowing simultaneous identification of multiple parasites. Different combinations of targets can be used within a routine diagnostic setting, depending on the patient population, such as children, immunocompromised individuals and those who have been travelling to tropical regions. Large-scale monitoring and evaluation of control strategies become feasible due to automation and high-throughput facilities. Improved technology also has become available for differentiating protozoa subspecies, which facilitates outbreak investigations and extensive research in molecular epidemiology.
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Abstract
No evidence of sexual reproduction has been detected in many eukaryotes, but this "negative evidence" of obligatory asexuality is still met with widespread skepticism. This is partly because obligatory asexual reproduction is deleterious in the long run and partly because it is logically possible that there are undetected sexual individuals. I point out that this skepticism stems from failure to think statistically, and the absence of sexual individuals in a sufficiently large sample can be very convincing evidence of obligatory asexuality. A survey of rotifer workers showed that approximately 458 515 bdelloid rotifers have been examined without finding any males or hermaphrodites; applying the Poisson distribution to these data shows that the upper 95% confidence interval of the number of sexual individuals is less than 8.1 x 10(-6). In darwinulid ostracods, a smaller sample puts the estimate at less than 1.75 x 10(-4) sexual individuals. If there were undetected sexual individuals at these low levels, the frequency of outcrossing must be even lower; so that sex will be ineffective and easily lost. Furthermore, recently published evidence shows that these ancient asexuals are not "scandalous" but merely the tail end of the age distribution of asexual lineages.
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Affiliation(s)
- C William Birky
- Department of Ecology and Evolutionary Biology, Biological Sciences West, The University of Arizona, Tucson, AZ 85721, USA.
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