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Serafim TD, Iniguez E, Barletta ABF, Cecilio P, Doehl JSP, Short M, Lack J, Nair V, Disotuar M, Wilson T, Coutinho-Abreu IV, Meneses C, Andersen J, Alves E Silva TL, Oliveira F, Vega-Rodriguez J, Barillas-Mury C, Ribeiro JMC, Beverley SM, Kamhawi S, Valenzuela JG. Leishmania genetic exchange is mediated by IgM natural antibodies. Nature 2023; 623:149-156. [PMID: 37880367 DOI: 10.1038/s41586-023-06655-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 09/19/2023] [Indexed: 10/27/2023]
Abstract
Host factors that mediate Leishmania genetic exchange are not well defined. Here we demonstrate that natural IgM (IgMn)1-4 antibodies mediate parasite genetic exchange by inducing the transient formation of a spherical parasite clump that promotes parasite fusion and hybrid formation. We establish that IgMn from Leishmania-free animals binds to the surface of Leishmania parasites to induce significant changes in the expression of parasite transcripts and proteins. Leishmania binding to IgMn is partially lost after glycosidase treatment, although parasite surface phosphoglycans, including lipophosphoglycan, are not required for IgMn-induced parasite clumping. Notably, the transient formation of parasite clumps is essential for Leishmania hybridization in vitro. In vivo, we observed a 12-fold increase in hybrid formation in sand flies provided a second blood meal containing IgMn compared with controls. Furthermore, the generation of recombinant progeny from mating hybrids and parental lines were only observed in sand flies provided with IgMn. Both in vitro and in vivo IgM-induced Leishmania crosses resulted in full genome hybrids that show equal patterns of biparental contribution. Leishmania co-option of a host natural antibody to facilitate mating in the insect vector establishes a new paradigm of parasite-host-vector interdependence that contributes to parasite diversity and fitness by promoting genetic exchange.
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Affiliation(s)
- Tiago D Serafim
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
| | - Eva Iniguez
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Ana Beatriz F Barletta
- Mosquito Immunity and Vector Competence Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Pedro Cecilio
- Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Johannes S P Doehl
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Mara Short
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Justin Lack
- NIAID Collaborative Bioinformatics Resource, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Vinod Nair
- Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Maria Disotuar
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Timothy Wilson
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Iliano V Coutinho-Abreu
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Claudio Meneses
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - John Andersen
- Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Thiago Luiz Alves E Silva
- Molecular Parasitology and Entomology Unit, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Fabiano Oliveira
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Joel Vega-Rodriguez
- Molecular Parasitology and Entomology Unit, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Carolina Barillas-Mury
- Mosquito Immunity and Vector Competence Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - José M C Ribeiro
- Vector Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Stephen M Beverley
- Department of Molecular Microbiology, School of Medicine, Washington University, St Louis, MO, USA.
| | - Shaden Kamhawi
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
| | - Jesus G Valenzuela
- Vector Molecular Biology Section, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
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Subspecific Nomenclature of Giardia duodenalis in the Light of a Compared Population Genomics of Pathogens. Pathogens 2023; 12:pathogens12020249. [PMID: 36839521 PMCID: PMC9960469 DOI: 10.3390/pathogens12020249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/30/2023] [Accepted: 01/30/2023] [Indexed: 02/08/2023] Open
Abstract
Genetic and genomic data have long recognized that the species Giardia duodenalis is subdivided into at least eight genetic clusters that have been named "assemblages" by specialists in the field. Some of these assemblages have been given the status of species, with Linnean binames. In the framework of the predominant clonal evolution model (PCE), we have shown that, from an evolutionary point of view, G. duodenalis assemblages are equatable to "near-clades", that is to say: clades whose discreteness is somewhat clouded by occasional genetic exchange, but remain discrete and stable in space and time. The implications of this evolutionary status for the species described within G. duodenalis are discussed in light of the most recent genetic and genomic studies. The pattern of this species' subspecific genetic variability and genetic clustering appears to be very similar to the ones of various parasitic, fungal and bacteria species. This underlines the relevance of a compared population genomics of pathogenic species allowed by the broad framework of the PCE model.
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Tibayrenc M, Ayala FJ. Microevolution and subspecific taxonomy of Trypanosoma cruzi. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 103:105344. [PMID: 35926722 DOI: 10.1016/j.meegid.2022.105344] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Trypanosoma cruzi, the agent of Chagas disease, is a highly polymorphic species, subdivided into 6 main evolutionary lineages or near-clades (formerly discrete typing units or DTUs). An additional near-clade (TC-bat) has recently been evidenced. This pattern is considered to be the result of predominant clonal evolution (PCE). PCE is compatible with occasional mating/hybridization, which do not break the prevalent pattern of clonal evolution, the main trait of it being the presence of Multigene Bifurcating Trees (MGBTs) at all evolutionary levels ("clonal frame"). The development of highly resolutive genetic (microsatellites*) and genomic (sequencing and multi-single nucleotide polymorphism {SNP}* typing) markers shows that PCE also operates at a microevolutionary* level within each of the near-clades ("Russian doll pattern"), in spite of occasional meiosis and hybridization events. Within each near-clade, one can evidence widespread clonal multilocus genotypes*, linkage disequilibrium*, Multigene Bifurcating Trees and lesser near-clades. The within near-clade population structure is like a miniature picture of that of the whole species, suggesting gradual rather than saltatory evolution. Additional data are required to evaluate the stability of these lesser near-clades in the long run and to evaluate the need for an adequate nomenclature for this microevolutionary level.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), Institut de Recherche Pour le Développement, BP 6450134394 Montpellier Cedex 5, France.
| | - Francisco J Ayala
- Catedra Francisco Jose Ayala of Science, Technology, and Religion, University of Comillas, 28015 Madrid, Spain. 2 Locke Court, Irvine, CA 92617, USA
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McTaggart AR, James TY, Shivas RG, Drenth A, Wingfield BD, Summerell BA, Duong TA. Population genomics reveals historical and ongoing recombination in the Fusarium oxysporum species complex. Stud Mycol 2022; 99:100132. [PMID: 35027981 PMCID: PMC8693468 DOI: 10.1016/j.simyco.2021.100132] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The Fusarium oxysporum species complex (FOSC) is a group of closely related plant pathogens long-considered strictly clonal, as sexual stages have never been recorded. Several studies have questioned whether recombination occurs in FOSC, and if it occurs its nature and frequency are unknown. We analysed 410 assembled genomes to answer whether FOSC diversified by occasional sexual reproduction interspersed with numerous cycles of asexual reproduction akin to a model of predominant clonal evolution (PCE). We tested the hypothesis that sexual reproduction occurred in the evolutionary history of FOSC by examining the distribution of idiomorphs at the mating locus, phylogenetic conflict and independent measures of recombination from genome-wide SNPs and genes. A phylogenomic dataset of 40 single copy orthologs was used to define structure a priori within FOSC based on genealogical concordance. Recombination within FOSC was tested using the pairwise homoplasy index and divergence ages were estimated by molecular dating. We called SNPs from assembled genomes using a k-mer approach and tested for significant linkage disequilibrium as an indication of PCE. We clone-corrected and tested whether SNPs were randomly associated as an indication of recombination. Our analyses provide evidence for sexual or parasexual reproduction within, but not between, clades of FOSC that diversified from a most recent common ancestor about 500 000 years ago. There was no evidence of substructure based on geography or host that might indicate how clades diversified. Competing evolutionary hypotheses for FOSC are discussed in the context of our results.
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Affiliation(s)
- A R McTaggart
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Ecosciences Precinct, Dutton Park, 4102, Queensland, Australia
| | - T Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - R G Shivas
- Centre for Crop Health, Institute for Life Sciences and the Environment, University of Southern Queensland, Toowoomba, 4350, Australia
| | - A Drenth
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Ecosciences Precinct, Dutton Park, 4102, Queensland, Australia
| | - B D Wingfield
- Department of Biochemistry, Genetics and Microbiology, Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa
| | - B A Summerell
- Australian Institute of Botanical Science, Royal Botanic Gardens & Domain Trust, Sydney, Australia
| | - T A Duong
- Department of Biochemistry, Genetics and Microbiology, Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa
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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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Reproduction in Trypanosomatids: Past and Present. BIOLOGY 2021; 10:biology10060471. [PMID: 34071741 PMCID: PMC8230138 DOI: 10.3390/biology10060471] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/20/2021] [Accepted: 05/25/2021] [Indexed: 01/07/2023]
Abstract
Simple Summary The reproduction of trypanosomatids is a fundamental issue for host–parasite interaction, and its biological importance lies in knowing how these species acquire new defense mechanisms against the countermeasures imposed by the host, which is consistent with the theory of the endless race or the Red Queen hypothesis for the existence of meiotic sex. Moreover, the way these species re-produce may also be at the origin of novel and more virulent clades and is relevant from a thera-peutic or vaccination point of view, as sex may contribute to increased tolerance and even to the rapid acquisition of drug resistance mechanisms. Kinetoplastids are single-celled organisms, many of them being responsible for important parasitic diseases, globally termed neglected diseases, which are endemic in low-income countries. Leishmaniasis, African (sleeping sickness) and American trypanosomiasis (Chagas disease) caused by trypanosomatids are among the most ne-glected tropical scourges related to poverty and poor health systems. The reproduction of these microorganisms has long been considered to be clonal due to population genetic observations. However, there is increasing evidence of true sex and genetic exchange events under laboratory conditions. We would like to highlight the importance of this topic in the field of host/parasite in-terplay, virulence, and drug resistance. Abstract Diseases caused by trypanosomatids (Sleeping sickness, Chagas disease, and leishmaniasis) are a serious public health concern in low-income endemic countries. These diseases are produced by single-celled parasites with a diploid genome (although aneuploidy is frequent) organized in pairs of non-condensable chromosomes. To explain the way they reproduce through the analysis of natural populations, the theory of strict clonal propagation of these microorganisms was taken as a rule at the beginning of the studies, since it partially justified their genomic stability. However, numerous experimental works provide evidence of sexual reproduction, thus explaining certain naturally occurring events that link the number of meiosis per mitosis and the frequency of mating. Recent techniques have demonstrated genetic exchange between individuals of the same species under laboratory conditions, as well as the expression of meiosis specific genes. The current debate focuses on the frequency of genomic recombination events and its impact on the natural parasite population structure. This paper reviews the results and techniques used to demonstrate the existence of sex in trypanosomatids, the inheritance of kinetoplast DNA (maxi- and minicircles), the impact of genetic exchange in these parasites, and how it can contribute to the phenotypic diversity of natural populations.
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Tibayrenc M, Ayala FJ. Models in parasite and pathogen evolution: Genomic analysis reveals predominant clonality and progressive evolution at all evolutionary scales in parasitic protozoa, yeasts and bacteria. ADVANCES IN PARASITOLOGY 2021; 111:75-117. [PMID: 33482977 DOI: 10.1016/bs.apar.2020.12.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The predominant clonal evolution (PCE) model of pathogenic microorganisms postulates that the impact of genetic recombination in those pathogens' natural populations is not enough to erase a persistent phylogenetic signal at all evolutionary scales from microevolution till geological times in the whole ecogeographical range of the species considered. We have tested this model with a set of representative parasitic protozoa, yeasts and bacteria in the light of the most recent genomic data. All surveyed species, including those that were considered as highly recombining, exhibit similar PCE patterns above and under the species level, from macro- to micro-evolutionary scales (Russian doll pattern), suggesting gradual evolution. To our knowledge, it is the first time that such a strong common evolutionary feature among very diverse pathogens has been evidenced. The implications of this model for basic biology and applied research are exposed. These implications include our knowledge on the pathogens' reproductive mode, their population structure, the possibility to type strain and to follow up epidemics (molecular epidemiology) and to revisit pathogens' taxonomy through a flexible use of the phylogenetic species concept (Cracraft, 1983).
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), Institut de recherche pour le développement, Montpellier Cedex 5, France.
| | - Francisco J Ayala
- Catedra Francisco Jose Ayala of Science, Technology, and Religion, University of Comillas, Madrid, Spain; 2 Locke Court, Irvine, CA, United States
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Nennig M, Llarena AK, Herold M, Mossong J, Penny C, Losch S, Tresse O, Ragimbeau C. Investigating Major Recurring Campylobacter jejuni Lineages in Luxembourg Using Four Core or Whole Genome Sequencing Typing Schemes. Front Cell Infect Microbiol 2021; 10:608020. [PMID: 33489938 PMCID: PMC7819963 DOI: 10.3389/fcimb.2020.608020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/23/2020] [Indexed: 12/31/2022] Open
Abstract
Campylobacter jejuni is the leading cause of bacterial gastroenteritis, which has motivated the monitoring of genetic profiles circulating in Luxembourg since 13 years. From our integrated surveillance using a genotyping strategy based on an extended MLST scheme including gyrA and porA markers, an unexpected endemic pattern was discovered in the temporal distribution of genotypes. We aimed to test the hypothesis of stable lineages occurrence by implementing whole genome sequencing (WGS) associated with comprehensive and internationally validated schemes. This pilot study assessed four WGS-based typing schemes to classify a panel of 108 strains previously identified as recurrent or sporadic profiles using this in-house typing system. The strain collection included four common lineages in human infection (N = 67) initially identified from recurrent combination of ST-gyrA-porA alleles also detected in non-human samples: veterinary (N = 19), food (N = 20), and environmental (N = 2) sources. An additional set of 19 strains belonging to sporadic profiles completed the tested panel. All the strains were processed by WGS by using Illumina technologies and by applying stringent criteria for filtering sequencing data; we ensure robustness in our genomic comparison. Four typing schemes were applied to classify the strains: (i) the cgMLST SeqSphere+ scheme of 637 loci, (ii) the cgMLST Oxford scheme of 1,343 loci, (iii) the cgMLST INNUENDO scheme of 678 loci, and (iv) the wgMLST INNUENDO scheme of 2,795 loci. A high concordance between the typing schemes was determined by comparing the calculated adjusted Wallace coefficients. After quality control and analyses with these four typing schemes, 60 strains were confirmed as members of the four recurrent lineages regardless of the method used (N = 32, 12, 7, and 9, respectively). Our results indicate that, regardless of the typing scheme used, epidemic or endemic signals were detected as reflected by lineage B (ST2254-gyrA9-porA1) in 2014 or lineage A (ST19-gyrA8-porA7), respectively. These findings support the clonal expansion of stable genomes in Campylobacter population exhibiting a multi-host profile and accounting for the majority of clinical strains isolated over a decade. Such recurring genotypes suggest persistence in reservoirs, sources or environment, emphasizing the need to investigate their survival strategy in greater depth.
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Affiliation(s)
- Morgane Nennig
- Epidemiology and Microbial Genomics, Laboratoire National de Santé, Dudelange, Luxembourg.,INRAE, Oniris, SECALIM, Nantes, France
| | - Ann-Katrin Llarena
- Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Malte Herold
- Epidemiology and Microbial Genomics, Laboratoire National de Santé, Dudelange, Luxembourg
| | - Joël Mossong
- Epidemiology and Microbial Genomics, Laboratoire National de Santé, Dudelange, Luxembourg
| | - Christian Penny
- Luxembourg Institute of Science and Technology, Environmental Research and Innovation Department, Belvaux, Luxembourg
| | - Serge Losch
- Laboratoire de Médecine Vétérinaire de l'Etat, Veterinary Services Administration, Dudelange, Luxembourg
| | | | - Catherine Ragimbeau
- Epidemiology and Microbial Genomics, Laboratoire National de Santé, Dudelange, Luxembourg
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Ortega‐Beltran A, Callicott KA, Cotty PJ. Founder events influence structures of Aspergillus flavus populations. Environ Microbiol 2020; 22:3522-3534. [PMID: 32515100 PMCID: PMC7496522 DOI: 10.1111/1462-2920.15122] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 04/29/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022]
Abstract
In warm regions, agricultural fields are occupied by complex Aspergillus flavus communities composed of isolates in many vegetative compatibility groups (VCGs) with varying abilities to produce highly toxic, carcinogenic aflatoxins. Aflatoxin contamination is reduced with biocontrol products that enable atoxigenic isolates from atoxigenic VCGs to dominate the population. Shifts in VCG frequencies similar to those caused by the introduction of biocontrol isolates were detected in Sonora, Mexico, where biocontrol is not currently practiced. The shifts were attributed to founder events. Although VCGs reproduce clonally, significant diversity exists within VCGs. Simple sequence repeat (SSR) fingerprinting revealed that increased frequencies of VCG YV150 involved a single haplotype. This is consistent with a founder event. Additionally, great diversity was detected among 82 YV150 isolates collected over 20 years across Mexico and the United States. Thirty-six YV150 haplotypes were separated into two populations by Structure and SplitsTree analyses. Sixty-five percent of isolates had MAT1-1 and belonged to one population. The remaining had MAT1-2 and belonged to the second population. SSR alleles varied within populations, but recombination between populations was not detected despite co-occurrence at some locations. Results suggest that YV150 isolates with opposite mating-type have either strongly restrained or lost sexual reproduction among themselves.
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Affiliation(s)
- Alejandro Ortega‐Beltran
- School of Plant SciencesUniversity of ArizonaTucsonAZ85721USA
- International Institute of Tropical AgriculturePMB 5320 Oyo Road, IbadanNigeria
| | | | - Peter J. Cotty
- USDA‐ARSTucsonAZ85721USA
- School of Food Science and EngineeringOcean University of ChinaQingdaoShandong266003China
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Ortega-Beltran A, Callicott KA, Cotty PJ. Founder events influence structures of Aspergillus flavus populations. Environ Microbiol 2020; 22:3522-3534. [PMID: 32515100 DOI: 10.1111/emi.15122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 04/29/2020] [Accepted: 06/04/2020] [Indexed: 05/25/2023]
Abstract
In warm regions, agricultural fields are occupied by complex Aspergillus flavus communities composed of isolates in many vegetative compatibility groups (VCGs) with varying abilities to produce highly toxic, carcinogenic aflatoxins. Aflatoxin contamination is reduced with biocontrol products that enable atoxigenic isolates from atoxigenic VCGs to dominate the population. Shifts in VCG frequencies similar to those caused by the introduction of biocontrol isolates were detected in Sonora, Mexico, where biocontrol is not currently practiced. The shifts were attributed to founder events. Although VCGs reproduce clonally, significant diversity exists within VCGs. Simple sequence repeat (SSR) fingerprinting revealed that increased frequencies of VCG YV150 involved a single haplotype. This is consistent with a founder event. Additionally, great diversity was detected among 82 YV150 isolates collected over 20 years across Mexico and the United States. Thirty-six YV150 haplotypes were separated into two populations by Structure and SplitsTree analyses. Sixty-five percent of isolates had MAT1-1 and belonged to one population. The remaining had MAT1-2 and belonged to the second population. SSR alleles varied within populations, but recombination between populations was not detected despite co-occurrence at some locations. Results suggest that YV150 isolates with opposite mating-type have either strongly restrained or lost sexual reproduction among themselves.
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Affiliation(s)
- Alejandro Ortega-Beltran
- School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
- International Institute of Tropical Agriculture, PMB 5320 Oyo Road, Ibadan, Nigeria
| | | | - Peter J Cotty
- USDA-ARS, Tucson, AZ, 85721, USA
- School of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, 266003, China
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Species, Sequence Types and Alleles: Dissecting Genetic Variation in Acanthamoeba. Pathogens 2020; 9:pathogens9070534. [PMID: 32630775 PMCID: PMC7400246 DOI: 10.3390/pathogens9070534] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 12/15/2022] Open
Abstract
Species designations within Acanthamoeba are problematic because of pleomorphic morphology. Molecular approaches, including DNA sequencing, hinted at a resolution that has yet to be fully achieved. Alternative approaches were required. In 1996, the Byers/Fuerst lab introduced the concept of sequence types. Differences between isolates of Acanthamoeba could be quantitatively assessed by comparing sequences of the nuclear 18S rRNA gene, ultimately producing 22 sequence types, designated T1 through T22. The concept of sequence types helps our understanding of Acanthamoeba evolution. Nevertheless, substantial variation in the 18S rRNA gene differentiates many isolates within each sequence type. Because the majority of isolates with sequences in the international DNA databases have been studied for only a small segment of the gene, designated ASA.S1, genetic variation within this hypervariable region of the 18S rRNA gene has been scrutinized. In 2002, we first categorized variation in this region in a sample of T3 and T4 isolates from Hong Kong, observing ten “alleles” within type T4 and five “alleles” within T3. Subsequently, confusion occurred when different labs applied redundant numerical labels to identify different alleles. A more unified approach was required. We have tabulated alleles occurring in the sequences submitted to the international DNA databases, and determined their frequencies. Over 150 alleles have occurred more than once within 3500+ isolates of sequence type T4. Results from smaller samples of other sequence types (T3, T5, T11 and T15, and supergroup T2/6) have also been obtained. Our results provide new insights into the evolutionary history of Acanthamoeba, further illuminating the degree of genetic separation between significant taxonomic units within the genus, perhaps eventually elucidating what constitutes a species of Acanthamoeba.
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12
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Genomics and High-Resolution Typing Confirm Predominant Clonal Evolution Down to a Microevolutionary Scale in Trypanosoma cruzi. Pathogens 2020; 9:pathogens9050356. [PMID: 32397142 PMCID: PMC7281314 DOI: 10.3390/pathogens9050356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/07/2020] [Accepted: 05/07/2020] [Indexed: 12/27/2022] Open
Abstract
Trypanosoma cruzi, the agent of Chagas disease, is a paradigmatic case of the predominant clonal evolution (PCE) model, which states that the impact of genetic recombination in pathogens' natural populations is not sufficient to suppress a persistent phylogenetic signal at all evolutionary scales. In spite of indications for occasional recombination and meiosis, recent genomics and high-resolution typing data in T. cruzi reject the counterproposal that PCE does not operate at lower evolutionary scales, within the evolutionary units (=near-clades) that subdivide the species. Evolutionary patterns in the agent of Chagas disease at micro- and macroevolutionary scales are strikingly similar ("Russian doll pattern"), suggesting gradual, rather than saltatory evolution.
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Lauthier JJ, Ruybal P, Barroso PA, Hashiguchi Y, Marco JD, Korenaga M. Development of a Multilocus sequence typing (MLST) scheme for Pan-Leishmania. Acta Trop 2020; 201:105189. [PMID: 31580847 DOI: 10.1016/j.actatropica.2019.105189] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 09/06/2019] [Accepted: 09/19/2019] [Indexed: 12/14/2022]
Abstract
Since the description of the Leishmania genus, its identification and organization have been a challenge. A high number of molecular markers have been developed to resolve phylogenetic differences at the species level and for addressing key epidemiological and population genetics questions. Based on Multilocus enzyme electrophoresis (MLEE), Multilocus sequence typing (MLST) schemes have been developed using different gene candidates. From 38 original gene targets proposed by other authors, 27 of them were chosen. In silico selection was made by analyzing free access genomic sequence data of 33 Leishmania species, one Paraleishmania representative, and one outgroup, in order to select the best 15 loci. De novo amplifications and primers redesign of these 15 genes were analyzed over a panel of 20 reference strains and isolates. Phylogenetic analysis was made at every step. Two MLST schemes were selected. The first one was based on the analysis of three-gene fragments, and it is suitable for species assignment as well as basic phylogenetic studies. By the addition of seven-genes, an approach based on the analysis of ten-gene fragments was also proposed. This is the first work that two optimized MLST schemes have been suggested, validated against a phylogenetically diverse panel of Leishmania isolates. MLST is potentially a powerful phylogenetic approach, and most probably the new gold standard for Leishmania spp. characterization.
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Affiliation(s)
- Juan Jose Lauthier
- Parasitology Department, Kochi Medical School, Kochi University, Okocho Kohasu, Nankoku, Kochi Prefecture 783-8505, Japan.
| | - Paula Ruybal
- Universidad de Buenos Aires. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM). Facultad de Medicina. Paraguay 2155 Piso: 12, CABA (1121). Argentina
| | - Paola Andrea Barroso
- Instituto de Patología Experimental, Facultad de Ciencias de la Salud, Universidad Nacional de Salta / CONICET, Salta, Argentina
| | - Yoshihisa Hashiguchi
- Parasitology Department, Kochi Medical School, Kochi University, Okocho Kohasu, Nankoku, Kochi Prefecture 783-8505, Japan; Departamento de Parasitología y Medicina Tropical, Carrera de Medicina, Facultad de Ciencias Médicas, Universidad Católica de Santiago de Guayaquil, Guayaquil, Ecuador
| | - Jorge Diego Marco
- Instituto de Patología Experimental, Facultad de Ciencias de la Salud, Universidad Nacional de Salta / CONICET, Salta, Argentina
| | - Masataka Korenaga
- Parasitology Department, Kochi Medical School, Kochi University, Okocho Kohasu, Nankoku, Kochi Prefecture 783-8505, Japan.
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Espinosa A, Paz-Y-Miño-C G. Discrimination Experiments in Entamoeba and Evidence from Other Protists Suggest Pathogenic Amebas Cooperate with Kin to Colonize Hosts and Deter Rivals. J Eukaryot Microbiol 2019; 66:354-368. [PMID: 30055104 PMCID: PMC6349510 DOI: 10.1111/jeu.12673] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/27/2018] [Accepted: 07/25/2018] [Indexed: 01/06/2023]
Abstract
Entamoeba histolytica is one of the least understood protists in terms of taxa, clone, and kin discrimination/recognition ability. However, the capacity to tell apart same or self (clone/kin) from different or nonself (nonclone/nonkin) has long been demonstrated in pathogenic eukaryotes like Trypanosoma and Plasmodium, free-living social amebas (Dictyostelium, Polysphondylium), budding yeast (Saccharomyces), and in numerous bacteria and archaea (prokaryotes). Kin discrimination/recognition is explained under inclusive fitness theory; that is, the reproductive advantage that genetically closely related organisms (kin) can gain by cooperating preferably with one another (rather than with distantly related or unrelated individuals), minimizing antagonism and competition with kin, and excluding genetic strangers (or cheaters = noncooperators that benefit from others' investments in altruistic cooperation). In this review, we rely on the outcomes of in vitro pairwise discrimination/recognition encounters between seven Entamoeba lineages to discuss the biological significance of taxa, clone, and kin discrimination/recognition in a range of generalist and specialist species (close or distantly related phylogenetically). We then focus our discussion on the importance of these laboratory observations for E. histolytica's life cycle, host infestation, and implications of these features of the amebas' natural history for human health (including mitigation of amebiasis).
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Affiliation(s)
- Avelina Espinosa
- Department of Biology, Roger Williams University, Bristol, Rhode Island
- New England Center for the Public Understanding of Science, Roger Williams University, Bristol, Rhode Island
| | - Guillermo Paz-Y-Miño-C
- New England Center for the Public Understanding of Science, Roger Williams University, Bristol, Rhode Island
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How clonal is Trypanosoma congolense? A necessary clarification of the predominant clonal evolution model. Acta Trop 2019; 190:28-29. [PMID: 30391231 DOI: 10.1016/j.actatropica.2018.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 10/25/2018] [Accepted: 10/27/2018] [Indexed: 11/23/2022]
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16
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Reis-Cunha JL, Baptista RP, Rodrigues-Luiz GF, Coqueiro-Dos-Santos A, Valdivia HO, de Almeida LV, Cardoso MS, D'Ávila DA, Dias FHC, Fujiwara RT, Galvão LMC, Chiari E, Cerqueira GC, Bartholomeu DC. Whole genome sequencing of Trypanosoma cruzi field isolates reveals extensive genomic variability and complex aneuploidy patterns within TcII DTU. BMC Genomics 2018; 19:816. [PMID: 30424726 PMCID: PMC6234542 DOI: 10.1186/s12864-018-5198-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 10/23/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Trypanosoma cruzi, the etiologic agent of Chagas disease, is currently divided into six discrete typing units (DTUs), named TcI-TcVI. TcII is among the major DTUs enrolled in human infections in South America southern cone, where it is associated with severe cardiac and digestive symptoms. Despite the importance of TcII in Chagas disease epidemiology and pathology, so far, no genome-wide comparisons of the mitochondrial and nuclear genomes of TcII field isolates have been performed to track the variability and evolution of this DTU in endemic regions. RESULTS In the present work, we have sequenced and compared the whole nuclear and mitochondrial genomes of seven TcII strains isolated from chagasic patients from the central and northeastern regions of Minas Gerais, Brazil, revealing an extensive genetic variability within this DTU. A comparison of the phylogeny based on the nuclear or mitochondrial genomes revealed that the majority of branches were shared by both sequences. The subtle divergences in the branches are probably consequence of mitochondrial introgression events between TcII strains. Two T. cruzi strains isolated from patients living in the central region of Minas Gerais, S15 and S162a, were clustered in the nuclear and mitochondrial phylogeny analysis. These two strains were isolated from the other five by the Espinhaço Mountains, a geographic barrier that could have restricted the traffic of insect vectors during T. cruzi evolution in the Minas Gerais state. Finally, the presence of aneuploidies was evaluated, revealing that all seven TcII strains have a different pattern of chromosomal duplication/loss. CONCLUSIONS Analysis of genomic variability and aneuploidies suggests that there is significant genomic variability within Minas Gerais TcII strains, which could be exploited by the parasite to allow rapid selection of favorable phenotypes. Also, the aneuploidy patterns vary among T. cruzi strains and does not correlate with the nuclear phylogeny, suggesting that chromosomal duplication/loss are recent and frequent events in the parasite evolution.
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Affiliation(s)
- João Luís Reis-Cunha
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Rodrigo P Baptista
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.,The University of Georgia, Athens, USA
| | - Gabriela F Rodrigues-Luiz
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.,Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | | | - Hugo O Valdivia
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.,U.S. Naval Medical Research, Lima, Peru
| | - Laila Viana de Almeida
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mariana Santos Cardoso
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | | | | | - Lúcia M C Galvão
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Egler Chiari
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Daniella C Bartholomeu
- Departamento de Parasitologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
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17
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Tibayrenc M, Ayala FJ. A misleading description of the predominant clonal evolution model in Trypanosoma cruzi. Acta Trop 2018; 187:13-14. [PMID: 30048630 DOI: 10.1016/j.actatropica.2018.07.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/18/2018] [Accepted: 07/20/2018] [Indexed: 12/16/2022]
Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), Institut de recherche pour le développement, BP 64501, 34394 Montpellier Cedex 5, France.
| | - Francisco J Ayala
- Department of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, CA, 92697, USA
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18
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Alves CL, Repolês BM, da Silva MS, Mendes IC, Marin PA, Aguiar PHN, Santos SDS, Franco GR, Macedo AM, Pena SDJ, Andrade LDO, Guarneri AA, Tahara EB, Elias MC, Machado CR. The recombinase Rad51 plays a key role in events of genetic exchange in Trypanosoma cruzi. Sci Rep 2018; 8:13335. [PMID: 30190603 PMCID: PMC6127316 DOI: 10.1038/s41598-018-31541-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/16/2018] [Indexed: 12/11/2022] Open
Abstract
Detection of genetic exchange has been a limiting factor to deepen the knowledge on the mechanisms by which Trypanosoma cruzi is able to generate progeny and genetic diversity. Here we show that incorporation of halogenated thymidine analogues, followed by immunostaining, is a reliable method not only to detect T. cruzi fused-cell hybrids, but also to quantify their percentage in populations of this parasite. Through this approach, we were able to detect and quantify fused-cell hybrids of T. cruzi clones CL Brener and Y. Given the increased detection of fused-cell hybrids in naturally-occurring hybrid CL Brener strain, which displays increased levels of RAD51 and BRCA2 transcripts, we further investigated the role of Rad51 - a recombinase involved in homologous recombination - in the process of genetic exchange. We also verified that the detection of fused-cell hybrids in T. cruzi overexpressing RAD51 is increased when compared to wild-type cells, suggesting a key role for Rad51 either in the formation or in the stabilization of fused-cell hybrids in this organism.
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Affiliation(s)
- Ceres Luciana Alves
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Bruno Marçal Repolês
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Marcelo Santos da Silva
- Laboratório Especial de Ciclo Celular, Centro de Toxinas, Resposta Imune e Sinalização Celular, Instituto Butantan, São Paulo, SP, Brazil
| | - Isabela Cecília Mendes
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Paula Andrea Marin
- Laboratório Especial de Ciclo Celular, Centro de Toxinas, Resposta Imune e Sinalização Celular, Instituto Butantan, São Paulo, SP, Brazil
| | | | - Selma da Silva Santos
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Glória Regina Franco
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Andréa Mara Macedo
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Sérgio Danilo Junho Pena
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | | | - Erich Birelli Tahara
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Maria Carolina Elias
- Laboratório Especial de Ciclo Celular, Centro de Toxinas, Resposta Imune e Sinalização Celular, Instituto Butantan, São Paulo, SP, Brazil
| | - Carlos Renato Machado
- Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
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Tibayrenc M, Ayala F. Hybridization in Trypanosoma congolense does not challenge the predominant clonal evolution model. A comment on Tihon et al., 2017, Mol. Ecol. Mol Ecol 2018; 27:3421-3424. [PMID: 30146716 DOI: 10.1111/mec.14714] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 04/17/2018] [Accepted: 04/19/2018] [Indexed: 11/28/2022]
Abstract
Tihon et al. have just published in Mol. Ecol. a fine genomic study on Trypanosoma congolense, agent of Animal African Trypanosomiasis. They present very convincing evidence that T. congolense underwent several hybridization events between distinct genetic lines in Zambia. They claim that their data challenge our predominant clonal evolution model (PCE) of micropathogens. We point out the main tenets of our model and show that Tihon et al.'s claim is based on a misinterpretation of the PCE model. Actually, their data strongly support PCE in T. congolense at a microevolutionary level.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), Institut de recherché pour le développement, Montpellier, France
| | - Francisco Ayala
- Department of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, California
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20
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Recent advances in trypanosomatid research: genome organization, expression, metabolism, taxonomy and evolution. Parasitology 2018; 146:1-27. [PMID: 29898792 DOI: 10.1017/s0031182018000951] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Unicellular flagellates of the family Trypanosomatidae are obligatory parasites of invertebrates, vertebrates and plants. Dixenous species are aetiological agents of a number of diseases in humans, domestic animals and plants. Their monoxenous relatives are restricted to insects. Because of the high biological diversity, adaptability to dramatically different environmental conditions, and omnipresence, these protists have major impact on all biotic communities that still needs to be fully elucidated. In addition, as these organisms represent a highly divergent evolutionary lineage, they are strikingly different from the common 'model system' eukaryotes, such as some mammals, plants or fungi. A number of excellent reviews, published over the past decade, were dedicated to specialized topics from the areas of trypanosomatid molecular and cell biology, biochemistry, host-parasite relationships or other aspects of these fascinating organisms. However, there is a need for a more comprehensive review that summarizing recent advances in the studies of trypanosomatids in the last 30 years, a task, which we tried to accomplish with the current paper.
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Hauck S, Maiden MCJ. Clonally Evolving Pathogenic Bacteria. MOLECULAR MECHANISMS OF MICROBIAL EVOLUTION 2018. [DOI: 10.1007/978-3-319-69078-0_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Tibayrenc M, Ayala FJ. Relevant units of analysis for applied and basic research dealing with neglected transmissible diseases: The predominant clonal evolution model of pathogenic microorganisms. PLoS Negl Trop Dis 2017; 11:e0005293. [PMID: 28448491 PMCID: PMC5407763 DOI: 10.1371/journal.pntd.0005293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The predominant clonal evolution (PCE) model seeks to formulate a common population genetics framework for all micropathogens (namely, parasitic protozoa, fungi and yeasts, bacteria, and viruses). It relies on a definition of clonality that is only based on population structure features (namely, strongly restrained genetic recombination). Its clear-cut properties make it of strong interest for applied and basic research, since it permits the definition of stable, clearly delimited units of analysis below the species level: clonal genotypes and discrete genetic subdivisions (“near-clades”). These units of analysis can be used for clinical and epidemiological studies, vaccine and drug design, species description, and evolutionary studies on natural and experimental populations. In this review, the evolutionary and population genetics background of the model will be only briefly mentioned, while considerable emphasis will be given to its practical significance for the study and control of neglected tropical diseases. The goal of the paper is to make this practical usefulness accessible to a broad audience of readers, including scientists who are not evolution specialists, such as epidemiologists, field scientists, and clinicians. For extensive developments about the evolutionary background of the model, see our previous papers [1–9]. Citations of these former articles lead to the many references quoted in them, which cannot be listed again here.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), Institut de Rercherche pour le Développement (IRD), 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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