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Dyer NA, Lucas ER, Nagi SC, McDermott DP, Brenas JH, Miles A, Clarkson CS, Mawejje HD, Wilding CS, Halfon MS, Asma H, Heinz E, Donnelly MJ. Mechanisms of transcriptional regulation in Anopheles gambiae revealed by allele-specific expression. Proc Biol Sci 2024; 291:20241142. [PMID: 39288798 PMCID: PMC11407855 DOI: 10.1098/rspb.2024.1142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 07/05/2024] [Accepted: 07/24/2024] [Indexed: 09/19/2024] Open
Abstract
Malaria control relies on insecticides targeting the mosquito vector, but this is increasingly compromised by insecticide resistance, which can be achieved by elevated expression of detoxifying enzymes that metabolize the insecticide. In diploid organisms, gene expression is regulated both in cis, by regulatory sequences on the same chromosome, and by trans acting factors, affecting both alleles equally. Differing levels of transcription can be caused by mutations in cis-regulatory modules (CRM), but few of these have been identified in mosquitoes. We crossed bendiocarb-resistant and susceptible Anopheles gambiae strains to identify cis-regulated genes that might be responsible for the resistant phenotype using RNAseq, and CRM sequences controlling gene expression in insecticide resistance relevant tissues were predicted using machine learning. We found 115 genes showing allele-specific expression (ASE) in hybrids of insecticide susceptible and resistant strains, suggesting cis-regulation is an important mechanism of gene expression regulation in A. gambiae. The genes showing ASE included a higher proportion of Anopheles-specific genes on average younger than genes with balanced allelic expression.
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Affiliation(s)
- Naomi A. Dyer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, UK
| | - Eric R. Lucas
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, UK
| | - Sanjay C. Nagi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, UK
| | - Daniel P. McDermott
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, UK
| | - Jon H. Brenas
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CambridgeCB10 1SA, UK
| | - Alistair Miles
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CambridgeCB10 1SA, UK
| | - Chris S. Clarkson
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CambridgeCB10 1SA, UK
| | - Henry D. Mawejje
- Infectious Diseases Research Collaboration (IDRC), Plot 2C Nakasero Hill Road, PO Box 7475, Kampala, Uganda
| | - Craig S. Wilding
- School of Biological and Environmental Sciences, Liverpool John Moores University, Byrom Street, LiverpoolL3 3AF, UK
| | - Marc S. Halfon
- Department of Biochemistry, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo-State University of New York, 955 Main Street, Buffalo, NY14203, USA
| | - Hasiba Asma
- Department of Biochemistry, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo-State University of New York, 955 Main Street, Buffalo, NY14203, USA
| | - Eva Heinz
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, UK
- Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, GlasgowG4 0RE, UK
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, UK
| | - Martin J. Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, LiverpoolL3 5QA, UK
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Dyer NA, Lucas ER, Nagi SC, McDermott DP, Brenas JH, Miles A, Clarkson CS, Mawejje HD, Wilding CS, Halfon MS, Asma H, Heinz E, Donnelly MJ. Mechanisms of transcriptional regulation in Anopheles gambiae revealed by allele specific expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568226. [PMID: 38045426 PMCID: PMC10690255 DOI: 10.1101/2023.11.22.568226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Malaria control relies on insecticides targeting the mosquito vector, but this is increasingly compromised by insecticide resistance, which can be achieved by elevated expression of detoxifying enzymes that metabolize the insecticide. In diploid organisms, gene expression is regulated both in cis, by regulatory sequences on the same chromosome, and by trans acting factors, affecting both alleles equally. Differing levels of transcription can be caused by mutations in cis-regulatory modules (CRM), but few of these have been identified in mosquitoes. We crossed bendiocarb resistant and susceptible Anopheles gambiae strains to identify cis-regulated genes that might be responsible for the resistant phenotype using RNAseq, and cis-regulatory module sequences controlling gene expression in insecticide resistance relevant tissues were predicted using machine learning. We found 115 genes showing allele specific expression in hybrids of insecticide susceptible and resistant strains, suggesting cis regulation is an important mechanism of gene expression regulation in Anopheles gambiae. The genes showing allele specific expression included a higher proportion of Anopheles specific genes on average younger than genes those with balanced allelic expression.
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Affiliation(s)
- Naomi A Dyer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Eric R Lucas
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Sanjay C Nagi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Daniel P McDermott
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Jon H Brenas
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Alistair Miles
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Chris S Clarkson
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Henry D Mawejje
- Infectious Diseases Research Collaboration (IDRC), Plot 2C Nakasero Hill Road, P.O.Box 7475, Kampala, Uganda
| | - Craig S Wilding
- School of Biological and Environmental Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - Marc S Halfon
- Department of Biochemistry, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo-State University of New York, 955 Main Street, Buffalo, New York 14203, USA
| | - Hasiba Asma
- Department of Biochemistry, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo-State University of New York, 955 Main Street, Buffalo, New York 14203, USA
| | - Eva Heinz
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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Pollegioni P, Persampieri T, Minuz RL, Bucci A, Trusso A, Martino SD, Leo C, Bruttini M, Ciolfi M, Waldvogel A, Tripet F, Simoni A, Crisanti A, Müller R. Introgression of a synthetic sex ratio distortion transgene into different genetic backgrounds of Anopheles coluzzii. INSECT MOLECULAR BIOLOGY 2023; 32:56-68. [PMID: 36251429 PMCID: PMC10092091 DOI: 10.1111/imb.12813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
The development of genetically modified mosquitoes (GMM) and their subsequent field release offers innovative approaches for vector control of malaria. A non-gene drive self-limiting male-bias Ag(PMB)1 strain has been developed in a 47-year-old laboratory G3 strain of Anopheles gambiae s.l. When Ag(PMB)1 males are crossed to wild-type females, expression of the endonuclease I-PpoI during spermatogenesis causes the meiotic cleavage of the X chromosome in sperm cells, leading to fertile offspring with a 95% male bias. However, World Health Organization states that the functionality of the transgene could differ when inserted in different genetic backgrounds of Anopheles coluzzii which is currently a predominant species in several West-African countries and thus a likely recipient for a potential release of self-limiting GMMs. In this study, we introgressed the transgene from the donor Ag(PMB)1 by six serial backcrosses into two recipient colonies of An. coluzzii that had been isolated in Mali and Burkina Faso. Scans of informative Single Nucleotide Polymorphism (SNP) markers and whole-genome sequencing analysis revealed a nearly complete introgression of chromosomes 3 and X, but a remarkable genomic divergence in a large region of chromosome 2 between the later backcrossed (BC6) transgenic offspring and the recipient paternal strains. These findings suggested to extend the backcrossing breeding strategy beyond BC6 generation and increasing the introgression efficiency of critical regions that have ecological and epidemiological implications through the targeted selection of specific markers. Disregarding differential introgression efficiency, we concluded that the phenotype of the sex ratio distorter is stable in the BC6 introgressed An. coluzzii strains.
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Affiliation(s)
- Paola Pollegioni
- Research Institute on Terrestrial EcosystemsNational Research CouncilTerniItaly
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Tania Persampieri
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Roxana L. Minuz
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Alessandro Bucci
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Alessandro Trusso
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Salvatore Di Martino
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Chiara Leo
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Marco Bruttini
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
- Tuscan Centre of Precision Medicine, Department of Medicine, Surgery and NeurosciencesUniversity of SienaSienaItaly
| | - Marco Ciolfi
- Research Institute on Terrestrial EcosystemsNational Research CouncilTerniItaly
| | | | - Frédéric Tripet
- Centre for Applied Entomology and ParasitologyKeele UniversityNewcastle‐under‐LymeUK
| | - Alekos Simoni
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Andrea Crisanti
- Department of Molecular MedicineUniversity of PadovaPadovaItaly
| | - Ruth Müller
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
- Unit Entomology, Department of Biomedical SciencesInstitute of Tropical MedicineAntwerpBelgium
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Filipović I, Rašić G, Hereward J, Gharuka M, Devine GJ, Furlong MJ, Etebari K. A high-quality de novo genome assembly based on nanopore sequencing of a wild-caught coconut rhinoceros beetle (Oryctes rhinoceros). BMC Genomics 2022; 23:426. [PMID: 35672676 PMCID: PMC9172067 DOI: 10.1186/s12864-022-08628-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 05/03/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND An optimal starting point for relating genome function to organismal biology is a high-quality nuclear genome assembly, and long-read sequencing is revolutionizing the production of this genomic resource in insects. Despite this, nuclear genome assemblies have been under-represented for agricultural insect pests, particularly from the order Coleoptera. Here we present a de novo genome assembly and structural annotation for the coconut rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae), based on Oxford Nanopore Technologies (ONT) long-read data generated from a wild-caught female, as well as the assembly process that also led to the recovery of the complete circular genome assemblies of the beetle's mitochondrial genome and that of the biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). As an invasive pest of palm trees, O. rhinoceros is undergoing an expansion in its range across the Pacific Islands, requiring new approaches to management that may include strategies facilitated by genome assembly and annotation. RESULTS High-quality DNA isolated from an adult female was used to create four ONT libraries that were sequenced using four MinION flow cells, producing a total of 27.2 Gb of high-quality long-read sequences. We employed an iterative assembly process and polishing with one lane of high-accuracy Illumina reads, obtaining a final size of the assembly of 377.36 Mb that had high contiguity (fragment N50 length = 12 Mb) and accuracy, as evidenced by the exceptionally high completeness of the benchmarked set of conserved single-copy orthologous genes (BUSCO completeness = 99.1%). These quality metrics place our assembly ahead of the published Coleopteran genomes, including that of an insect model, the red flour beetle (Tribolium castaneum). The structural annotation of the nuclear genome assembly contained a highly-accurate set of 16,371 protein-coding genes, with only 2.8% missing BUSCOs, and the expected number of non-coding RNAs. The number and structure of paralogous genes in a gene family like Sigma GST is lower than in another scarab beetle (Onthophagus taurus), but higher than in the red flour beetle (Tribolium castaneum), which suggests expansion of this GST class in Scarabaeidae. The quality of our gene models was also confirmed with the correct placement of O. rhinoceros among other members of the rhinoceros beetles (subfamily Dynastinae) in a phylogeny based on the sequences of 95 protein-coding genes in 373 beetle species from all major lineages of Coleoptera. Finally, we provide a list of 30 candidate dsRNA targets whose orthologs have been experimentally validated as highly effective targets for RNAi-based control of several beetles. CONCLUSIONS The genomic resources produced in this study form a foundation for further functional genetic research and management programs that may inform the control and surveillance of O. rhinoceros populations, and we demonstrate the efficacy of de novo genome assembly using long-read ONT data from a single field-caught insect.
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Affiliation(s)
- Igor Filipović
- School of Biological Sciences, The University of Queensland, St. Lucia, Australia.
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
| | - Gordana Rašić
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - James Hereward
- School of Biological Sciences, The University of Queensland, St. Lucia, Australia
| | - Maria Gharuka
- Research Division, Ministry of Agriculture and Livestock, Honiara, Solomon Islands
| | - Gregor J Devine
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Michael J Furlong
- School of Biological Sciences, The University of Queensland, St. Lucia, Australia
| | - Kayvan Etebari
- School of Biological Sciences, The University of Queensland, St. Lucia, Australia
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Beaghton PJ, Burt A. Gene drives and population persistence vs elimination: The impact of spatial structure and inbreeding at low density. Theor Popul Biol 2022; 145:109-125. [PMID: 35247370 DOI: 10.1016/j.tpb.2022.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/15/2022] [Accepted: 02/22/2022] [Indexed: 11/26/2022]
Abstract
Synthetic gene drive constructs are being developed to control disease vectors, invasive species, and other pest species. In a well-mixed random mating population a sufficiently strong gene drive is expected to eliminate a target population, but it is not clear whether the same is true when spatial processes play a role. In species with an appropriate biology it is possible that drive-induced reductions in density might lead to increased inbreeding, reducing the efficacy of drive, eventually leading to suppression rather than elimination, regardless of how strong the drive is. To investigate this question we analyse a series of explicitly solvable stochastic models considering a range of scenarios for the relative timing of mating, reproduction, and dispersal and analyse the impact of two different types of gene drive, a Driving Y chromosome and a homing construct targeting an essential gene. We find in all cases a sufficiently strong Driving Y will go to fixation and the population will be eliminated, except in the one life history scenario (reproduction and mating in patches followed by dispersal) where low density leads to increased inbreeding, in which case the population persists indefinitely, tending to either a stable equilibrium or a limit cycle. These dynamics arise because Driving Y males have reduced mating success, particularly at low densities, due to having fewer sisters to mate with. Increased inbreeding at low densities can also prevent a homing construct from eliminating a population. For both types of drive, if there is strong inbreeding depression, then the population cannot be rescued by inbreeding and it is eliminated. These results highlight the potentially critical role that low-density-induced inbreeding and inbreeding depression (and, by extension, other sources of Allee effects) can have on the eventual impact of a gene drive on a target population.
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Affiliation(s)
- P J Beaghton
- Institute for Security Science and Technology, South Kensington Campus, Imperial College London, London, UK; Department of Computing, South Kensington Campus, Imperial College London, London, UK.
| | - Austin Burt
- Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK
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Hemme RR, Smith EA, Felix G, White BJ, Diaz-Garcia MI, Rodriguez D, Ruiz-Valcarcel J, Acevedo V, Amador M, Barrera R. Multi-Year Mass-Trapping With Autocidal Gravid Ovitraps has Limited Influence on Insecticide Susceptibility in Aedes aegypti (Diptera: Culicidae) From Puerto Rico. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:314-319. [PMID: 34536077 DOI: 10.1093/jme/tjab162] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Indexed: 05/15/2023]
Abstract
Mass-trapping has been used to control outbreaks of Aedes aegypti (Linnaeus) (Diptera: Culicidae) in Puerto Rico since 2011. We investigated the effect of multi-year, insecticide-free mass trapping had on the insecticide susceptibility profile of Ae. aegypti. Eggs collected in southern Puerto Rico were used to generate F1 populations that were tested for susceptibility to permethrin, sumethrin, bifenthrin, deltamethrin, and malathion according to CDC bottle bioassays protocols. All populations of Ae. aegypti were resistant to the synthetic pyrethroids and mosquitoes from two locations were partially resistant to malathion. Population genetic analysis, using a double digest restriction sites associated DNA sequencing (ddRADseq) approach, indicated a large amount of migration between study sites effectively homogenizing the mosquito populations. Mass-trapping using noninsecticidal autocidal gravid ovitraps did not restore susceptibility to five active ingredients that are found in commercial insecticides. Migration between communities was high and would have brought outside alleles, including resistant alleles to the treatment communities. Further investigation suggests that household use of commercially available insecticide products may continue to select for resistance in absence of public health space spraying of insecticides.
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Affiliation(s)
- Ryan R Hemme
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
| | - Eric A Smith
- Department of Entomology, University of California, Riverside, CA, USA
- Diversigen, New Brighton, MN, USA
| | - Gilberto Felix
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
| | - Bradley J White
- Department of Entomology, University of California, Riverside, CA, USA
- Verily Life Sciences, South San Francisco, CA, USA
| | - Marta I Diaz-Garcia
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
| | - Damaris Rodriguez
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
| | - Jose Ruiz-Valcarcel
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
| | - Veronica Acevedo
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
| | - Manuel Amador
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
| | - Roberto Barrera
- Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico
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De Serrano AR, Hughes KA, Rodd FH. Paternal exposure to a common pharmaceutical (Ritalin) has transgenerational effects on the behaviour of Trinidadian guppies. Sci Rep 2021; 11:3985. [PMID: 33597600 PMCID: PMC7889922 DOI: 10.1038/s41598-021-83448-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/02/2021] [Indexed: 01/04/2023] Open
Abstract
Evidence is emerging that paternal effects, the nongenetic influence of fathers on their offspring, can be transgenerational, spanning several generations. Methylphenidate hydrochloride (MPH; e.g. Ritalin) is a dopaminergic drug that is highly prescribed to adolescent males for the treatment of Attention-deficit/hyperactivity disorder. It has been suggested that MPH could cause transgenerational effects because MPH can affect the male germline in rodents and because paternal effects have been observed in individuals taking similar drugs (e.g. cocaine). Despite these concerns, the transgenerational effects of paternal MPH exposure are unknown. Therefore, we exposed male and female Trinidadian guppies (Poecilia reticulata) to a low, chronic dose of MPH and observed that MPH affected the anxiety/exploratory behaviour of males, but not females. Because of this male-specific effect, we investigated the transgenerational effects of MPH through the paternal line. We observed behavioural effects of paternal MPH exposure on offspring and great-grandoffspring that were not directly administered the drug, making this the first study to demonstrate that paternal MPH exposure can affect descendants. These effects were not due to differential mortality or fecundity between control and MPH lines. These results highlight the transgenerational potential of MPH.
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Affiliation(s)
- Alex R De Serrano
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St, Toronto, ON, M5S 3B2, Canada.
| | - Kimberly A Hughes
- Department of Biological Science, Florida State University, 319 Stadium Dr, Tallahassee, FL, 32304, USA
| | - F Helen Rodd
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St, Toronto, ON, M5S 3B2, Canada
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8
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Powell JR. Genetic Variation in Insect Vectors: Death of Typology? INSECTS 2018; 9:E139. [PMID: 30314367 PMCID: PMC6316525 DOI: 10.3390/insects9040139] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/01/2018] [Accepted: 10/08/2018] [Indexed: 12/25/2022]
Abstract
The issue of typological versus population thinking in biology is briefly introduced and defined. It is then emphasized how population thinking is most relevant and useful in vector biology. Three points are made: (1) Vectors, as they exist in nature, are genetically very heterogeneous. (2) Four examples of how this is relevant in vector biology research are presented: Understanding variation in vector competence, GWAS, identifying the origin of new introductions of invasive species, and resistance to inbreeding. (3) The existence of high levels of vector genetic heterogeneity can lead to failure of some approaches to vector control, e.g., use of insecticides and release of sterile males (SIT). On the other hand, vector genetic heterogeneity can be harnessed in a vector control program based on selection for refractoriness.
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Affiliation(s)
- Jeffrey R Powell
- Yale University, 21 Sachem Street, New Haven, CT 06520-8105, USA.
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Kamdem C, Fouet C, Gamez S, White BJ. Pollutants and Insecticides Drive Local Adaptation in African Malaria Mosquitoes. Mol Biol Evol 2017; 34:1261-1275. [PMID: 28204524 PMCID: PMC5400387 DOI: 10.1093/molbev/msx087] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Anopheles gambiae complex contains a number of highly anthropophilic mosquito species that have acquired exceptional ability to thrive in complex human habitats. Thus, examining the evolutionary history of this Afrotropical mosquito may yield vital information on the selective processes that occurred during the adaptation to human-dominated environments. We performed reduced representation sequencing on 941 mosquitoes of the Anopheles gambiae complex collected across four ecogeographic zones in Cameroon. We find evidence for genetic and geographic subdivision within An. coluzzii and An. gambiae sensu stricto-the two most significant malaria vectors in the region. Importantly, in both species, rural and urban populations are genetically differentiated. Genome scans reveal pervasive signatures of selection centered on genes involved in xenobiotic resistance. Notably, a selective sweep containing detoxification enzymes is prominent in urban mosquitoes that exploit polluted breeding sites. Overall, our study suggests that recent anthropogenic environmental modifications and widespread use of insecticides are driving population differentiation and local adaptation in vectors with potentially significant consequences for malaria epidemiology.
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Affiliation(s)
- Colince Kamdem
- Department of Entomology, University of California, Riverside, CA
| | - Caroline Fouet
- Department of Entomology, University of California, Riverside, CA
| | - Stephanie Gamez
- Department of Entomology, University of California, Riverside, CA
| | - Bradley J. White
- Department of Entomology, University of California, Riverside, CA
- Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, CA
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10
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Domingos A, Pinheiro-Silva R, Couto J, do Rosário V, de la Fuente J. The Anopheles gambiae transcriptome - a turning point for malaria control. INSECT MOLECULAR BIOLOGY 2017; 26:140-151. [PMID: 28067439 DOI: 10.1111/imb.12289] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Mosquitoes are important vectors of several pathogens and thereby contribute to the spread of diseases, with social, economic and public health impacts. Amongst the approximately 450 species of Anopheles, about 60 are recognized as vectors of human malaria, the most important parasitic disease. In Africa, Anopheles gambiae is the main malaria vector mosquito. Current malaria control strategies are largely focused on drugs and vector control measures such as insecticides and bed-nets. Improvement of current, and the development of new, mosquito-targeted malaria control methods rely on a better understanding of mosquito vector biology. An organism's transcriptome is a reflection of its physiological state and transcriptomic analyses of different conditions that are relevant to mosquito vector competence can therefore yield important information. Transcriptomic analyses have contributed significant information on processes such as blood-feeding parasite-vector interaction, insecticide resistance, and tissue- and stage-specific gene regulation, thereby facilitating the path towards the development of new malaria control methods. Here, we discuss the main applications of transcriptomic analyses in An. gambiae that have led to a better understanding of mosquito vector competence.
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Affiliation(s)
- A Domingos
- Instituto de Higiene e Medicina Tropical (IHMT), Lisboa, Portugal
- Global Health and Tropical Medicine (GHMT), Instituto de Higiene e Medicina Tropical (IHMT), Lisboa, Portugal
| | - R Pinheiro-Silva
- Instituto de Higiene e Medicina Tropical (IHMT), Lisboa, Portugal
| | - J Couto
- Instituto de Higiene e Medicina Tropical (IHMT), Lisboa, Portugal
| | - V do Rosário
- Instituto de Higiene e Medicina Tropical (IHMT), Lisboa, Portugal
| | - J de la Fuente
- SaBio. Instituto de Investigación de Recursos Cinegéticos, IREC-CSIC-UCLM-JCCM, Ciudad Real, Spain
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
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Laboratory rearing of Anopheles arabiensis: impact on genetic variability and implications for Sterile Insect Technique (SIT) based mosquito control in northern Sudan. Malar J 2016; 15:432. [PMID: 27799066 PMCID: PMC5088653 DOI: 10.1186/s12936-016-1484-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/11/2016] [Indexed: 12/18/2022] Open
Abstract
Background Mosquito colony populations often show significant changes in their population genetic make-up compared to the field populations that were used as founding source. Most of the changes that have been reported are indicators of depletion in the overall genetic diversity of the colony populations. The Sterile Insect Techniques programme of mosquito control that is underway in Northern Sudan uses sterilized males produced from a laboratory-maintained colony population. The genetic diversity of an advanced generation of this colony population was quantitatively assessed and compared to the field population from which the colony was derived. Methods Anopheles arabiensis mosquito samples from the 13th generation of the colony, and from the locality that was the source of the first generation of the colony, were genotyped at 11 microsatellite loci distributed throughout the species’ genome. Standard population genetic analyses were carried out to quantify and compare their population genetic make-up and diversities. Results The colony samples showed significant reduction in the total number of alleles, the numbers of rare and private alleles, and the fractions of heterozygote individuals at all the loci. The pattern of change is consistent with the expected effect of the use of a small number of mosquitoes when the colony was established. Departure from Hardy–Weinberg equilibrium in the direction of homozygote excess was observed at some loci and attributed to the presence of null-alleles. Conclusions This study highlights the need for broad sampling when initiating colony populations and for ongoing assessment of the population genetic make-up of colony populations. Previous assessments of survivorship, dispersive behaviour and swarm formation indicate that the inbreeding and reduced genetic variability reported in this study may not have had direct fitness consequences yet. However, noting the lessons learned in other SIT programmes about the impact of colonization on male sexual behaviour and longevity, as well as other inbreeding related adverse effects, a systematic investigation of these potential effects is recommended because they have direct impact on the ultimate success of the programme.
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Fritz ML, Paa S, Baltzegar J, Gould F. Application of a dense genetic map for assessment of genomic responses to selection and inbreeding in Heliothis virescens. INSECT MOLECULAR BIOLOGY 2016; 25:385-400. [PMID: 27097739 DOI: 10.1111/imb.12234] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Adaptation of pest species to laboratory conditions and selection for resistance to toxins in the laboratory are expected to cause inbreeding and genetic bottlenecks that reduce genetic variation. Heliothis virescens, a major cotton pest, has been colonized in the laboratory many times, and a few laboratory colonies have been selected for Bacillus thuringiensis (Bt) resistance. We developed 350-bp double-digest restriction-site associated DNA-sequencing (ddRAD-seq) molecular markers to examine and compare changes in genetic variation associated with laboratory adaptation, artificial selection and inbreeding in this nonmodel insect species. We found that allelic and nucleotide diversity declined dramatically in laboratory-reared H. virescens as compared with field-collected populations. The declines were primarily a result of the loss of low frequency alleles present in field-collected H. virescens. A further, albeit modest decline in genetic diversity was observed in a Bt-selected population. The greatest decline was seen in H. virescens that were sib-mated for 10 generations, in which more than 80% of loci were fixed for a single allele. To determine which regions of the genome were resistant to fixation in our sib-mated line, we generated a dense intraspecific linkage map containing three PCR-based and 659 ddRAD-seq markers. Markers that retained polymorphism were observed in small clusters spread over multiple linkage groups, but this clustering was not statistically significant. Overall, we have confirmed and extended the general expectations for reduced genetic diversity in laboratory colonies, provided tools for further genomic analyses and produced highly homozygous genomic DNA for future whole genome sequencing of H. virescens.
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Affiliation(s)
- M L Fritz
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
- Department of Biological Sciences, Program in Genetics, North Carolina State University, Raleigh, NC, USA
| | - S Paa
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
| | - J Baltzegar
- Department of Biological Sciences, Program in Genetics, North Carolina State University, Raleigh, NC, USA
| | - F Gould
- Department of Entomology, North Carolina State University, Raleigh, NC, USA
- Department of Biological Sciences, Program in Genetics, North Carolina State University, Raleigh, NC, USA
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Monzón JD, Atkinson EG, Henn BM, Benach JL. Population and Evolutionary Genomics of Amblyomma americanum, an Expanding Arthropod Disease Vector. Genome Biol Evol 2016; 8:1351-60. [PMID: 27190204 PMCID: PMC4898797 DOI: 10.1093/gbe/evw080] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The lone star tick, Amblyomma americanum, is an important disease vector and the most frequent tick found attached to humans in the eastern United States. The lone star tick has recently experienced a rapid range expansion into the Northeast and Midwest, but despite this emerging infectious threat to wildlife, livestock, and human health, little is known about the genetic causes and consequences of the geographic expansion. In the first population genomic analysis of any tick species, we characterize the genetic diversity and population structure of A. americanum across its current geographic range, which has recently expanded. Using a high-throughput genotyping-by-sequencing approach, we discovered more than 8,000 single nucleotide polymorphisms in 90 ticks from five locations. Surprisingly, newly established populations in New York (NY) and Oklahoma (OK) are as diverse as historic range populations in North and South Carolina. However, substantial population structure occurs among regions, such that new populations in NY and OK are genetically distinct from historic range populations and from one another. Ticks from a laboratory colony are genetically distinct from wild populations, underscoring the need to account for natural variation when conducting transmission or immunological studies, many of which utilize laboratory-reared ticks. An FST-outlier analysis comparing a recently established population to a long-standing population detected numerous outlier sites, compatible with positive and balancing selection, highlighting the potential for adaptation during the range expansion. This study provides a framework for applying high-throughput DNA sequencing technologies for future investigations of ticks, which are common vectors of diseases.
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Affiliation(s)
- Javier D Monzón
- Natural Science Division, Pepperdine University Department of Molecular Genetics & Microbiology, Stony Brook University
| | | | - Brenna M Henn
- Department of Ecology & Evolution, Stony Brook University
| | - Jorge L Benach
- Department of Molecular Genetics & Microbiology, Stony Brook University
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Donnelly MJ, Isaacs AT, Weetman D. Identification, Validation, and Application of Molecular Diagnostics for Insecticide Resistance in Malaria Vectors. Trends Parasitol 2015; 32:197-206. [PMID: 26750864 DOI: 10.1016/j.pt.2015.12.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/27/2015] [Accepted: 12/02/2015] [Indexed: 12/20/2022]
Abstract
Insecticide resistance is a major obstacle to control of Anopheles malaria mosquitoes in sub-Saharan Africa and requires an improved understanding of the underlying mechanisms. Efforts to discover resistance genes and DNA markers have been dominated by candidate gene and quantitative trait locus studies of laboratory strains, but with greater availability of genome sequences a shift toward field-based agnostic discovery is anticipated. Mechanisms evolve continually to produce elevated resistance yielding multiplicative diagnostic markers, co-screening of which can give high predictive value. With a shift toward prospective analyses, identification and screening of resistance marker panels will boost monitoring and programmatic decision making.
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Affiliation(s)
- Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; Malaria Programme, Wellcome Trust Sanger Institute, Cambridge, UK.
| | - Alison T Isaacs
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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Abstract
Using computer simulation we explore the consequences of linkage on the inbreeding load of an equilibrium population, and on the efficiency of purging and the loss of genetic diversity after a reduction in population size. We find that linkage tends to cause increased inbreeding load due to the build up of coupling groups of (partially) recessive deleterious alleles. It also induces associative overdominance at neutral sites but rarely causes increased neutral genetic diversity in equilibrium populations. After a reduction in population size, linkage can cause some delay both for the expression of the inbreeding load and the corresponding purging. However, reasonable predictions can be obtained for the evolution of fitness under inbreeding and purging by using empirical estimates of the inbreeding depression rate. Purging selection against homozygotes for deleterious alleles affects the population's pedigree. Furthermore, it can slow the loss of genetic diversity compared to that expected from the variance of gametic contributions to the breeding group and even from pedigree inbreeding. Under some conditions, this can lead to a smaller loss of genetic diversity, even below that expected from population size in the absence of selection.
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Lawniczak MK. Connecting genotypes to medically relevant phenotypes in major vector mosquitoes. CURRENT OPINION IN INSECT SCIENCE 2015; 10:59-64. [PMID: 29588015 DOI: 10.1016/j.cois.2015.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/16/2015] [Indexed: 06/08/2023]
Abstract
Transmission of mosquito-borne human disease relies on vectors maintaining strong human host preference and continued susceptibility to disease-causing pathogens or parasites. These traits are affected by the genetics and the environments of all involved organisms, and genotypic interactions are common between parasite and vector, and between virus and vector. A recent study on Aedes host preference has exploited natural genetic variation to make great progress. Here I review our current understanding of the genetic basis of transmission-relevant traits in Anopheles and Aedes, highlighting additional research areas that would benefit from the integration of natural genetic variation.
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Affiliation(s)
- Mara Kn Lawniczak
- Wellcome Trust Sanger Institute, Malaria Programme, Hinxton CB10 1SA, United Kingdom; Imperial College London, Department of Life Sciences, London SW7 2AZ, United Kingdom.
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Waiting with bated breath: opportunistic orientation to human odor in the malaria mosquito, Anopheles gambiae, is modulated by minute changes in carbon dioxide concentration. J Chem Ecol 2015; 41:59-66. [PMID: 25572756 DOI: 10.1007/s10886-014-0542-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 11/24/2014] [Accepted: 12/05/2014] [Indexed: 10/24/2022]
Abstract
Females of the malaria mosquito, Anopheles gambiae, predominantly obtain blood meals within human dwellings. Being highly anthropophilic, human skin odor offers a reliable, host-specific cue, but the challenge posed by pervasive human odor found indoors from used clothing, bedding etc. remains unclear. Anopheles gambiae spends much of its adult life indoors, constantly exposed to human odor even when dwellings are unoccupied. In landing assays, we found that female mosquitoes respond very weakly to human skin odor alone, suggesting that, alone, it is an ineffective landing cue. Landing, however, was dramatically increased by addition of carbon dioxide at a range of concentrations above ambient. Indeed, this effect was seen even when carbon dioxide was just 0.015% above ambient within the assay cage. The synergistic effect of added carbon dioxide quickly waned, thereby facilitating a highly adaptive "sit-and-wait" ambush strategy, wherein females ignore persistent human odor until a living human is present. Unexpectedly, landing rates in the presence of added carbon dioxide were almost as robust during daytime, when An. gambiae has previously been assumed inactive, possibly facilitating opportunistic feeding at times of day when human dwellings are occupied intermittently. We suggest earlier studies that showed strong upwind flight behavior toward human odor alone could, in fact, have been demonstrating orientation toward a human dwelling rather than toward a living human. This new interpretation of how human odors mediate upwind orientation and landing in An. gambiae is discussed.
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