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Jeffries CL, Cansado-Utrilla C, Beavogui AH, Stica C, Lama EK, Kristan M, Irish SR, Walker T. Evidence for natural hybridization and novel Wolbachia strain superinfections in the Anopheles gambiae complex from Guinea. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202032. [PMID: 33868697 PMCID: PMC8025300 DOI: 10.1098/rsos.202032] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/15/2021] [Indexed: 05/05/2023]
Abstract
Wolbachia, a widespread bacterium which can influence mosquito-borne pathogen transmission, has recently been detected within Anopheles (An.) species that are malaria vectors in Sub-Saharan Africa. Although studies have reported Wolbachia strains in the An. gambiae complex, apparent low density and prevalence rates require confirmation. In this study, wild Anopheles mosquitoes collected from two regions of Guinea were investigated. In contrast with previous studies, RNA was extracted from adult females (n = 516) to increase the chances for the detection of actively expressed Wolbachia genes, determine Wolbachia prevalence rates and estimate relative strain densities. Molecular confirmation of mosquito species and Wolbachia multilocus sequence typing (MLST) were carried out to analyse phylogenetic relationships of mosquito hosts and newly discovered Wolbachia strains. Strains were detected in An. melas (prevalence rate of 11.6%-16/138) and hybrids between An. melas and An. gambiae sensu stricto (prevalence rate of 40.0%-6/15) from Senguelen in the Maferinyah region. Furthermore, a novel high-density strain, termed wAnsX, was found in an unclassified Anopheles species. The discovery of novel Wolbachia strains (particularly in members, and hybrids, of the An. gambiae complex) provides further candidate strains that could be used for future Wolbachia-based malaria biocontrol strategies.
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Affiliation(s)
- Claire L. Jeffries
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Cintia Cansado-Utrilla
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Abdoul H. Beavogui
- Centre National de Formation et de Recherche en Santé Rurale de Mafèrinyah B.P. 2649, Conakry, Guinea
| | - Caleb Stica
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Eugene K. Lama
- Programme National de Lutte contre le Paludisme, Guinée, B.P. 6339 Conakry, Guinea
| | - Mojca Kristan
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Seth R. Irish
- The US President's Malaria Initiative and Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329-4027, USA
| | - Thomas Walker
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
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Bernardini F, Kriezis A, Galizi R, Nolan T, Crisanti A. Introgression of a synthetic sex ratio distortion system from Anopheles gambiae into Anopheles arabiensis. Sci Rep 2019; 9:5158. [PMID: 30914785 PMCID: PMC6435806 DOI: 10.1038/s41598-019-41646-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 03/14/2019] [Indexed: 12/04/2022] Open
Abstract
I-PpoI is a homing endonuclease that has a high cleavage activity and specificity for a conserved sequence within the ribosomal rDNA repeats, located in a single cluster on the Anopheles gambiae X chromosome. This property has been exploited to develop a synthetic sex ratio distortion system in this mosquito species. When I-PpoI is expressed from a transgene during spermatogenesis in mosquitoes, the paternal X chromosome is shredded and only Y chromosome-bearing sperm are viable, resulting in a male-biased sex ratio of >95% in the progeny. These distorter male mosquitoes can efficiently suppress caged wild-type populations, providing a powerful tool for vector control strategies. Given that malaria mosquito vectors belong to a species complex comprising at least two major vectors, we investigated whether the sex distorter I-PpoI, originally integrated in the A. gambiae genome, could be transferred via introgression to the sibling vector species Anopheles arabiensis. In compliance with Haldane’s rule, F1 hybrid male sterility is known to occur in all intercrosses among members of the Anopheles gambiae complex. A scheme based on genetic crosses and transgene selection was used to bypass F1 hybrid male sterility and introgress the sex distorter I-PpoI into the A. arabiensis genetic background. Our data suggest that this sex distortion technique can be successfully applied to target A. arabiensis mosquitoes.
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Affiliation(s)
- Federica Bernardini
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Antonios Kriezis
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Roberto Galizi
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Tony Nolan
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Andrea Crisanti
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
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Bernardini F, Galizi R, Wunderlich M, Taxiarchi C, Kranjc N, Kyrou K, Hammond A, Nolan T, Lawniczak MNK, Papathanos PA, Crisanti A, Windbichler N. Cross-Species Y Chromosome Function Between Malaria Vectors of the Anopheles gambiae Species Complex. Genetics 2017; 207:729-740. [PMID: 28860320 PMCID: PMC5629335 DOI: 10.1534/genetics.117.300221] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 08/21/2017] [Indexed: 02/03/2023] Open
Abstract
Y chromosome function, structure and evolution is poorly understood in many species, including the Anopheles genus of mosquitoes-an emerging model system for studying speciation that also represents the major vectors of malaria. While the Anopheline Y had previously been implicated in male mating behavior, recent data from the Anopheles gambiae complex suggests that, apart from the putative primary sex-determiner, no other genes are conserved on the Y. Studying the functional basis of the evolutionary divergence of the Y chromosome in the gambiae complex is complicated by complete F1 male hybrid sterility. Here, we used an F1 × F0 crossing scheme to overcome a severe bottleneck of male hybrid incompatibilities that enabled us to experimentally purify a genetically labeled A. gambiae Y chromosome in an A. arabiensis background. Whole genome sequencing (WGS) confirmed that the A. gambiae Y retained its original sequence content in the A. arabiensis genomic background. In contrast to comparable experiments in Drosophila, we find that the presence of a heterospecific Y chromosome has no significant effect on the expression of A. arabiensis genes, and transcriptional differences can be explained almost exclusively as a direct consequence of transcripts arising from sequence elements present on the A. gambiae Y chromosome itself. We find that Y hybrids show no obvious fertility defects, and no substantial reduction in male competitiveness. Our results demonstrate that, despite their radically different structure, Y chromosomes of these two species of the gambiae complex that diverged an estimated 1.85 MYA function interchangeably, thus indicating that the Y chromosome does not harbor loci contributing to hybrid incompatibility. Therefore, Y chromosome gene flow between members of the gambiae complex is possible even at their current level of divergence. Importantly, this also suggests that malaria control interventions based on sex-distorting Y drive would be transferable, whether intentionally or contingent, between the major malaria vector species.
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Affiliation(s)
- Federica Bernardini
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Roberto Galizi
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Mariana Wunderlich
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Chrysanthi Taxiarchi
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Nace Kranjc
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Kyros Kyrou
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Andrew Hammond
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Tony Nolan
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Mara N K Lawniczak
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, CB10 1SA Cambridge, United Kingdom
| | - Philippos Aris Papathanos
- Section of Genomics and Genetics, Department of Experimental Medicine, University of Perugia, 06132, Italy
| | - Andrea Crisanti
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Nikolai Windbichler
- Department of Life Sciences, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
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Kang S, Jung J, Kim W. Population Genetic Structure of the Malaria Vector Anopheles sinensis (Diptera: Culicidae) Sensu Stricto and Evidence for Possible Introgression in the Republic of Korea. JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:1270-1281. [PMID: 26336253 DOI: 10.1093/jme/tjv114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 07/17/2015] [Indexed: 06/05/2023]
Abstract
Anopheles sinensis Wiedemann sensu stricto (s.s.) is a dominant mosquito and considered a secondary malaria vector in the Republic of Korea (ROK). Despite the potential significance for malaria control, population genetics studies have been conducted using only mitochondrial DNA (mtDNA), and studies of the genetics of hybridization have never been attempted. In this study, 346 specimens from 23 localities were subject to experiments. Among them, 305 An. sinensis s.s. specimens from 20 localities were used for mtDNA analysis, and 346 specimens comprising 341 An. sinensis s.s. from 22 localities and five Anopheles kleini Rueda from one locality were examined in the microsatellite study. Neighbor-joining analysis of pairwise FST and RST based on microsatellite results showed that the populations are divided into two groups, as did the mtDNA results. However, the Bayesian analysis and factorial correspondence analysis plots showed three distinct clusters. Among the mtDNA and microsatellite results, only microsatellites represented small but positive and significant isolation-by-distance patterns. Both molecular markers show the Taebaek and Sobaek Mountain ranges as barriers between the northern and southern parts of the ROK. The newly recognized third group suggests possible introgressive hybridization of An. sinensis s.s. with closely related species. The slightly different composition of populations in each group based on different markers is probably because of different population dynamics in each group. These results imply that there is restricted gene flow of epidemiologically important malaria-related genes between the northern and southern parts of the ROK.
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Affiliation(s)
- Seunghyun Kang
- Division of Polar Life Sciences, Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-gu, Incheon 406-840, Republic of Korea
| | - Jongwoo Jung
- Department of Science Education, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-gu, Seoul 120-750, Republic of Korea
| | - Won Kim
- School of Biological Sciences, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
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Fontaine MC, Pease JB, Steele A, Waterhouse RM, Neafsey DE, Sharakhov IV, Jiang X, Hall AB, Catteruccia F, Kakani E, Mitchell SN, Wu YC, Smith HA, Love RR, Lawniczak MK, Slotman MA, Emrich SJ, Hahn MW, Besansky NJ. Mosquito genomics. Extensive introgression in a malaria vector species complex revealed by phylogenomics. Science 2015; 347:1258524. [PMID: 25431491 PMCID: PMC4380269 DOI: 10.1126/science.1258524] [Citation(s) in RCA: 371] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Introgressive hybridization is now recognized as a widespread phenomenon, but its role in evolution remains contested. Here, we use newly available reference genome assemblies to investigate phylogenetic relationships and introgression in a medically important group of Afrotropical mosquito sibling species. We have identified the correct species branching order to resolve a contentious phylogeny and show that lineages leading to the principal vectors of human malaria were among the first to split. Pervasive autosomal introgression between these malaria vectors means that only a small fraction of the genome, mainly on the X chromosome, has not crossed species boundaries. Our results suggest that traits enhancing vectorial capacity may be gained through interspecific gene flow, including between nonsister species.
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Affiliation(s)
- Michael C Fontaine
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA. Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
| | - James B Pease
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Aaron Steele
- Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Robert M Waterhouse
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, 32 Vassar Street, Cambridge, MA 02139, USA. The Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA. Department of Genetic Medicine and Development, University of Geneva Medical School, rue Michel-Servet 1, 1211 Geneva, Switzerland. Swiss Institute of Bioinformatics, rue Michel-Servet 1, 1211 Geneva, Switzerland
| | - Daniel E Neafsey
- The Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA
| | - Igor V Sharakhov
- Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA. The Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Xiaofang Jiang
- The Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Andrew B Hall
- The Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Flaminia Catteruccia
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA. Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università degli Studi di Perugia, Perugia, Italy
| | - Evdoxia Kakani
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA. Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università degli Studi di Perugia, Perugia, Italy
| | - Sara N Mitchell
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Yi-Chieh Wu
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, 32 Vassar Street, Cambridge, MA 02139, USA
| | - Hilary A Smith
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA. Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
| | - R Rebecca Love
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA. Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Mara K Lawniczak
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Michel A Slotman
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | - Scott J Emrich
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA. Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Matthew W Hahn
- Department of Biology, Indiana University, Bloomington, IN 47405, USA. School of Informatics and Computing, Indiana University, Bloomington, IN 47405, USA.
| | - Nora J Besansky
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA. Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN 46556, USA.
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Weetman D, Steen K, Rippon EJ, Mawejje HD, Donnelly MJ, Wilding CS. Contemporary gene flow between wild An. gambiae s.s. and An. arabiensis. Parasit Vectors 2014; 7:345. [PMID: 25060488 PMCID: PMC4124135 DOI: 10.1186/1756-3305-7-345] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 07/21/2014] [Indexed: 11/10/2022] Open
Abstract
Background In areas where the morphologically indistinguishable malaria mosquitoes Anopheles gambiae Giles and An. arabiensis Patton are sympatric, hybrids are detected occasionally via species-diagnostic molecular assays. An. gambiae and An. arabiensis exhibit both pre- and post-reproductive mating barriers, with swarms largely species-specific and male F1 (first-generation) hybrids sterile. Consequently advanced-stage hybrids (back-crosses to parental species), which would represent a route for potentially-adaptive introgression, are expected to be very rare in natural populations. Yet the use of one or two physically linked single-locus diagnostic assays renders them indistinguishable from F1 hybrids and levels of interspecific gene flow are unknown. Methods We used data from over 350 polymorphic autosomal SNPs to investigate post F1 gene flow via patterns of genomic admixture between An. gambiae and An. arabiensis from eastern Uganda. Simulations were used to investigate the statistical power to detect hybrids with different levels of crossing and to identify the hybrid category significantly admixed genotypes could represent. Results A range of admixture proportions were detected for 11 field-collected hybrids identified via single-locus species-diagnostic PCRs. Comparison of admixture data with simulations indicated that at least seven of these hybrids were advanced generation crosses, with backcrosses to each species identified. In addition, of 36 individuals typing as An. gambiae or An. arabiensis that exhibited outlying admixture proportions, ten were identified as significantly mixed backcrosses, and at least four of these were second or third generation crosses. Conclusions Our results show that hybrids detected using standard diagnostics will often be hybrid generations beyond F1, and that in our study area around 5% (95% confidence intervals 3%-9%) of apparently ‘pure’ species samples may also be backcrosses. This is likely an underestimate because of rapidly-declining detection power beyond the first two backcross generations. Post-F1 gene flow occurs at a far from inconsequential rate between An. gambiae and An. arabiensis, and, especially for traits under strong selection, could readily lead to adaptive introgression of genetic variants relevant for vector control. Electronic supplementary material The online version of this article (doi:10.1186/1756-3305-7-345) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | - Craig S Wilding
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
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Choochote W, Min GS, Intapan PM, Tantrawatpan C, Saeung A, Lulitanond V. Evidence to support natural hybridization between Anopheles sinensis and Anopheles kleini (Diptera: Culicidae): possibly a significant mechanism for gene introgression in sympatric populations. Parasit Vectors 2014; 7:36. [PMID: 24443885 PMCID: PMC3899613 DOI: 10.1186/1756-3305-7-36] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 01/18/2014] [Indexed: 01/02/2023] Open
Abstract
Background Malaria caused by Plasmodium vivax is still a public health problem in the Republic of Korea (ROK), particularly regarding the recent re-emergence of this malarial species near the demilitarized zone in northwestern Paju City, Gyeonggi-do Province. Currently, at least 4 species (An. kleini, An. pullus, An. belenrae and An. lesteri) of the Hyrcanus Group are reported as possible natural vectors of vivax malaria in the ROK, and An. sinensis, which is the most dominant species, has long been incriminated as an important natural vector of this P. vivax. However, An. sinensis was ranked recently as a low potential vector. According to the discovery of natural hybrids between An. sinensis (a low potential vector for P. vivax) and An. kleini (a high potential vector for P. vivax) in Paju City, intensive investigation of this phenomenon is warranted under laboratory conditions. Methods Mosquitoes were collected during 2010-2012 from Paju City, ROK. Hybridization experiments used iso-female line colonies of these anophelines together with DNA analysis of ribosomal DNA [second internal transcribed spacer (ITS2)] and mitochondrial DNA [cytochrome c oxidase subunit I (COI)] of the parental colonies, F1-hybrids and repeated backcross progenies were performed intensively by using a PCR-based assay and pyrosequencing technology. Results The results from hybridization experiments and molecular investigations revealed that the mitochondrial COI gene was introgressed from An. sinensis into An. kleini. The An. sinensis progenies obtained from consecutive repeated backcrosses in both directions, i.e., F2-11 progeny [(An. sinensis x An. kleini) x An. sinensis] and F3-5 progeny [(An. kleini x An. sinensis) x An. kleini] provided good supportive evidence. Conclusions This study revealed introgression of the mitochondrial COI gene between An. sinensis and An. kleini through consecutive repeated backcrosses under laboratory conditions. This new body of knowledge will be emphasized in reliable promising strategies in order to replace the population of An. kleini as a high potential vector for P. vivax, with that of a low potential vector, An. sinensis, through the mechanism of gene introgression in nature.
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Affiliation(s)
- Wej Choochote
- Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
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Zianni MR, Nikbakhtzadeh MR, Jackson BT, Panescu J, Foster WA. Rapid discrimination between Anopheles gambiae s.s. and Anopheles arabiensis by High-Resolution Melt (HRM) analysis. J Biomol Tech 2013; 24:1-7. [PMID: 23543777 DOI: 10.7171/jbt.13-2401-001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
There is a need for more cost-effective options to more accurately discriminate among members of the Anopheles gambiae complex, particularly An. gambiae and Anopheles arabiensis. These species are morphologically indistinguishable in the adult stage, have overlapping distributions, but are behaviorally and ecologically different, yet both are efficient vectors of malaria in equatorial Africa. The method described here, High-Resolution Melt (HRM) analysis, takes advantage of minute differences in DNA melting characteristics, depending on the number of incongruent single nucleotide polymorphisms in an intragenic spacer region of the X-chromosome-based ribosomal DNA. The two species in question differ by an average of 13 single-nucleotide polymorphisms giving widely divergent melting curves. A real-time PCR system, Bio-Rad CFX96, was used in combination with a dsDNA-specific dye, EvaGreen, to detect and measure the melting properties of the amplicon generated from leg-extracted DNA of selected mosquitoes. Results with seven individuals from pure colonies of known species, as well as 10 field-captured individuals unambiguously identified by DNA sequencing, demonstrated that the method provided a high level of accuracy. The method was used to identify 86 field mosquitoes through the assignment of each to the two common clusters with a high degree of certainty. Each cluster was defined by individuals from pure colonies. HRM analysis is simpler to use than most other methods and provides comparable or more accurate discrimination between the two sibling species but requires a specialized melt-analysis instrument and software.
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Affiliation(s)
- Michael R Zianni
- Plant-Microbe Genomics Facility, The Ohio State University, Columbus, OH 43210, USA.
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Kang S, Jung J, Lee S, Hwang H, Kim W. The polymorphism and the geographical distribution of the knockdown resistance (kdr) of Anopheles sinensis in the Republic of Korea. Malar J 2012; 11:151. [PMID: 22554130 PMCID: PMC3459742 DOI: 10.1186/1475-2875-11-151] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Accepted: 05/03/2012] [Indexed: 11/23/2022] Open
Abstract
Background In the Republic of Korea (ROK), six sibling species of the Anopheles sinensis complex are considered the vector species of malaria, but data on their susceptibilities to malaria and vector capacities have been controversial. The intensive use of insecticides has contributed to the rapid development and spread of insecticide resistance in the An. sinensis complex. Knockdown resistance (kdr) to pyrethroids and DDT in the An. sinensis complex is associated with a mutation in codon 1014 of the voltage-gated sodium channel (VGSC) gene. Because the degree of insecticide resistance varies among mosquito species and populations, the detection of kdr mutations among the six sibling species of the An. sinensis complex is a prerequisite for establishing effective long-term vector control strategies in the ROK Methods In order to investigate species-specific kdr mutations, An. sinensis complex specimens have been collected from 22 sites in the ROK. Because of the difficulties with species identifications that are based only on morphological characteristics, molecular identification methods have been conducted on every specimen. Part of the IIS6 domain of the VGSC was polymerase chain reaction-amplified and directly sequenced. Results The molecular analyses revealed that mutations existed at codon 1014 only in An. sinensis sensu stricto and no mutations were found in the other five Anopheles species. In An. sinensis s.s., one wild type (TTG L1014) and three mutant types (TTT L1014F, TTC L1014F, and TGT L1014C) of kdr alleles were detected. The TTC L1014F mutation was observed for the first time in this species. Conclusions The fact that the highly polymorphic kdr gene is only observed in An. sinensis s.s., out of the six Anopheles species and their geographical distribution suggest the need for future studies of insecticide resistance monitoring and investigations of species-specific resistance mechanisms in order to build successful malaria vector control programmes in the ROK.
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Affiliation(s)
- Seunghyun Kang
- School of Biological Sciences, Seoul National University, 599 Gwanak-ro, Seoul, Republic of Korea
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Ng'habi KR, Knols BGJ, Lee Y, Ferguson HM, Lanzaro GC. Population genetic structure of Anopheles arabiensis and Anopheles gambiae in a malaria endemic region of southern Tanzania. Malar J 2011; 10:289. [PMID: 21975087 PMCID: PMC3195206 DOI: 10.1186/1475-2875-10-289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 10/05/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic diversity is a key factor that enables adaptation and persistence of natural populations towards environmental conditions. It is influenced by the interaction of a natural population's dynamics and the environment it inhabits. Anopheles gambiae s.s. and Anopheles arabiensis are the two major and widespread malaria vectors in sub-Saharan Africa. Several studies have examined the ecology and population dynamics of these vectors. Ecological conditions along the Kilombero valley in Tanzania influence the distribution and population density of these two vector species. It remains unclear whether the ecological diversity within the Kilombero valley has affected the population structure of An. gambiae s.l. populations. The goal of this study was to characterise the genetic structure of sympatric An. gambiae s.s and An. arabiensis populations along the Kilombero valley. METHODOLOGY Mosquitoes were collected from seven locations in Tanzania: six from the Kilombero valley and one outside the valley (-700 km away) as an out-group. To archive a genome-wide coverage, 13 microsatellite markers from chromosomes X, 2 and 3 were used. RESULTS High levels of genetic differentiation among An. arabiensis populations was observed, as opposed to An. gambiae s.s., which was genetically undifferentiated across the 6,650 km2 of the Kilombero valley landscape. It appears that genetic differentiation is not attributed to physical barriers or distance, but possibly by ecological diversification within the Kilombero valley. Genetic divergence among An. arabiensis populations (FST = 0.066) was higher than that of the well-known M and S forms of An. gambiae s. s. in West and Central Africa (FST = 0.035), suggesting that these populations are maintained by some level of reproductive isolation. CONCLUSION It was hypothesized that ecological diversification across the valley may be a driving force for observed An. arabiensis genetic divergence. The impact of the observed An. arabiensis substructure to the prospects for new vector control approaches is discussed.
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Affiliation(s)
- Kija R Ng'habi
- Biomedical and Environmental Thematic Group, Ifakara Health Institute, Box 53, Ifakara, Tanzania.
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Bonizzoni M, Afrane Y, Yan G. Loop-mediated isothermal amplification (LAMP) for rapid identification of Anopheles gambiae and Anopheles arabiensis mosquitoes. Am J Trop Med Hyg 2010; 81:1030-4. [PMID: 19996433 DOI: 10.4269/ajtmh.2009.09-0333] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The main malaria vectors of sub-Saharan Africa, Anopheles gambiae sensu stricto and Anopheles arabiensis are morphologically indistinguishable, but often occur in sympatry and differ in feeding preference and vector competence. It is important to assess vector species identity for understanding the vectorial system and establishing appropriate vector control measures. The currently available species diagnosis methods for An. gambiae sensu latu require equipment to which public health practitioners in many African countries may not have access. This report describes a loop-mediated isothermal amplification technique (LAMP) for An. gambiae species diagnosis. The LAMP method was tested in single mosquito legs and whole body. The sensitivity and specificity of the LAMP method, in reference to the conventional rDNA-polymerse chain reaction (PCR) method, ranged from 0.93 to 1.00. The LAMP-based species identification method can be performed in a water bath and completed within 65 minutes, representing an alternative method for rapid and field applicable vector species diagnosis.
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Affiliation(s)
- Mariangela Bonizzoni
- College of Health Sciences, University of California at Irvine, Irvine, California 92697-4050, USA.
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Abstract
In the malaria mosquito Anopheles gambiae polymorphic chromosomal inversions may play an important role in adaptation to environmental variation. Recently, we used microarray-based divergence mapping combined with targeted resequencing to map nucleotide differentiation between alternative arrangements of the 2La inversion. Here, we applied the same technique to four different polymorphic inversions on the 2R chromosome of An. gambiae. Surprisingly, divergence was much lower between alternative arrangements for all 2R inversions when compared to the 2La inversion. For one of the rearrangements, 2Ru, we successfully mapped a very small region (approximately 100 kb) of elevated divergence. For the other three rearrangements, we did not identify any regions of significantly high divergence, despite ample independent evidence from natural populations of geographic clines and seasonal cycling, and stable heterotic polymorphisms in laboratory populations. If these inversions are the targets of selection as hypothesized, we suggest that divergence between rearrangements may have escaped detection due to retained ancestral polymorphism in the case of the youngest 2R rearrangements and to extensive gene flux in the older 2R inversion systems that segregate in both An. gambiae and its sibling species An. arabiensis.
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Walker ED, Thibault AR, Thelen AP, Bullard BA, Huang J, Odiere MR, Bayoh NM, Wilkins EE, Vulule JM. Identification of field caught Anopheles gambiae s.s. and Anopheles arabiensis by TaqMan single nucleotide polymorphism genotyping. Malar J 2007; 6:23. [PMID: 17326831 PMCID: PMC1808465 DOI: 10.1186/1475-2875-6-23] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Accepted: 02/27/2007] [Indexed: 11/12/2022] Open
Abstract
Background Identification of Anopheles gambiae s.s. and Anopheles arabiensis from field-collected Anopheles gambiae s.l. is often necessary in basic and applied research, and in operational control programmes. The currently accepted method involves use of standard polymerase chain reaction amplification of ribosomal DNA (rDNA) from the 3' 28S to 5' intergenic spacer region of the genome, and visual confirmation of amplicons of predicted size on agarose gels, after electrophoresis. This report describes development and evaluation of an automated, quantitative PCR method based upon TaqMan™ single nucleotide polymorphism (SNP) genotyping. Methods Standard PCR, and TaqMan SNP genotyping with newly designed primers and fluorophore-labeled probes hybridizing to sequences of complementary rDNA specific for either An. gambiae s.s. or An. arabiensis, were conducted in three experiments involving field-collected An. gambiae s.l. from western Kenya, and defined laboratory strains. DNA extraction was from a single leg, sonicated for five minutes in buffer in wells of 96-well PCR plates. Results TaqMan SNP genotyping showed a reaction success rate, sensitivity, and species specificity comparable to that of standard PCR. In an extensive field study, only 29 of 3,041 (0.95%) were determined to be hybrids by TaqMan (i.e., having rDNA sequences from both species), however, all but one were An. arabiensis by standard PCR, suggesting an acceptably low (ca. 1%) error rate for TaqMan genotyping in mistakenly identifying species hybrids. Conclusion TaqMan SNP genotyping proved to be a sensitive and rapid method for identification of An. gambiae s.l. and An. arabiensis, with a high success rate, specific results, and congruence with the standard PCR method.
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Affiliation(s)
- Edward D Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Alisha R Thibault
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Annette P Thelen
- Department of Biochemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Blair A Bullard
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Juan Huang
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Maurice R Odiere
- Centre for Vector Biology and Control Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya
| | - Nabie M Bayoh
- Centre for Vector Biology and Control Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya
| | - Elizabeth E Wilkins
- Atlanta Research & Education Foundation, Malaria Research and Reference Reagent Resource Center, Centers for Disease Control and Prevention, 4770 Buford Hwy., Mailstop F-42, Atlanta GA 30341, USA
| | - John M Vulule
- Centre for Vector Biology and Control Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya
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Ayala FJ, Coluzzi M. Chromosome speciation: humans, Drosophila, and mosquitoes. Proc Natl Acad Sci U S A 2005; 102 Suppl 1:6535-42. [PMID: 15851677 PMCID: PMC1131864 DOI: 10.1073/pnas.0501847102] [Citation(s) in RCA: 225] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chromosome rearrangements (such as inversions, fusions, and fissions) may play significant roles in the speciation between parapatric (contiguous) or partly sympatric (geographically overlapping) populations. According to the "hybrid-dysfunction" model, speciation occurs because hybrids with heterozygous chromosome rearrangements produce dysfunctional gametes and thus have low reproductive fitness. Natural selection will, therefore, promote mutations that reduce the probability of intercrossing between populations carrying different rearrangements and thus promote their reproductive isolation. This model encounters a disabling difficulty: namely, how to account for the spread in a population of a chromosome rearrangement after it first arises as a mutation in a single individual. The "suppressed-recombination" model of speciation points out that chromosome rearrangements act as a genetic filter between populations. Mutations associated with the rearranged chromosomes cannot flow from one to another population, whereas genetic exchange will freely occur between colinear chromosomes. Mutations adaptive to local conditions will, therefore, accumulate differentially in the protected chromosome regions so that parapatric or partially sympatric populations will genetically differentiate, eventually evolving into different species. The speciation model of suppressed recombination has recently been tested by gene and DNA sequence comparisons between humans and chimpanzees, between Drosophila species, and between species related to Anopheles gambiae, the vector of malignant malaria in Africa.
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Affiliation(s)
- Francisco J Ayala
- Department of Ecology and Evolutionary Biology, University of California, Irvine, 92697, USA.
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Besansky NJ, Krzywinski J, Lehmann T, Simard F, Kern M, Mukabayire O, Fontenille D, Touré Y, Sagnon N. Semipermeable species boundaries between Anopheles gambiae and Anopheles arabiensis: evidence from multilocus DNA sequence variation. Proc Natl Acad Sci U S A 2003; 100:10818-23. [PMID: 12947038 PMCID: PMC196886 DOI: 10.1073/pnas.1434337100] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2003] [Indexed: 11/18/2022] Open
Abstract
Attempts to reconstruct the phylogenetic history of the Anopheles gambiae cryptic species complex have yielded strongly conflicting results. In particular, An. gambiae, the primary African malaria vector, is variously placed as a sister taxon to either Anopheles arabiensis or Anopheles merus. The recent divergence times for members of this complex complicate phylogenetic analysis, making it difficult to unambiguously implicate interspecific gene flow, versus retained ancestral polymorphism, as the source of conflict. Using sequences at four unlinked loci, which were determined from multiple specimens within each of five species in the complex, we found contrasting patterns of sequence divergence between the X chromosome and the autosomes. The isolation model of speciation assumes a lack of gene flow between species since their separation. This model could not be rejected for An. gambiae and An. arabiensis, although the data fit the model poorly. On the other hand, evidence from gene trees supports genetic introgression of chromosome 2 inversions between An. gambiae and An. arabiensis, and also points to more broad scale genetic exchange of autosomal sequences between this species pair. That such exchange has been relatively recent is suggested not only by the lack of fixed differences at three autosomal loci but also by the sharing of full haplotypes at two of the three loci, which is in contrast to several fixed differences and considerably deeper divergence on the X. The proposed acquisition by An. gambiae of sequences from the more arid-adapted An. arabiensis may have contributed to the spread and ecological dominance of this malaria vector.
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Affiliation(s)
- N J Besansky
- University of Notre Dame, Center for Tropical Disease Research and Training, Department of Biological Sciences, Notre Dame, IN 46556, USA.
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