1
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Deem KD, Halfon MS, Tomoyasu Y. A new suite of reporter vectors and a novel landing site survey system to study cis-regulatory elements in diverse insect species. Sci Rep 2024; 14:10078. [PMID: 38698030 PMCID: PMC11066043 DOI: 10.1038/s41598-024-60432-9] [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: 01/24/2024] [Accepted: 04/23/2024] [Indexed: 05/05/2024] Open
Abstract
Comparative analyses between traditional model organisms, such as the fruit fly Drosophila melanogaster, and more recent model organisms, such as the red flour beetle Tribolium castaneum, have provided a wealth of insight into conserved and diverged aspects of gene regulation. While the study of trans-regulatory components is relatively straightforward, the study of cis-regulatory elements (CREs, or enhancers) remains challenging outside of Drosophila. A central component of this challenge has been finding a core promoter suitable for enhancer-reporter assays in diverse insect species. Previously, we demonstrated that a Drosophila Synthetic Core Promoter (DSCP) functions in a cross-species manner in Drosophila and Tribolium. Given the over 300 million years of divergence between the Diptera and Coleoptera, we reasoned that DSCP-based reporter constructs will be useful when studying cis-regulation in a variety of insect models across the holometabola and possibly beyond. To this end, we sought to create a suite of new DSCP-based reporter vectors, leveraging dual compatibility with piggyBac and PhiC31-integration, the 3xP3 universal eye marker, GATEWAY cloning, different colors of reporters and markers, as well as Gal4-UAS binary expression. While all constructs functioned properly with a Tc-nub enhancer in Drosophila, complications arose with tissue-specific Gal4-UAS binary expression in Tribolium. Nevertheless, the functionality of these constructs across multiple holometabolous orders suggests a high potential compatibility with a variety of other insects. In addition, we present the piggyLANDR (piggyBac-LoxP AttP Neutralizable Destination Reporter) platform for the establishment of proper PhiC31 landing sites free from position effects. As a proof-of-principle, we demonstrated the workflow for piggyLANDR in Drosophila. The potential utility of these tools ranges from molecular biology research to pest and disease-vector management, and will help advance the study of gene regulation beyond traditional insect models.
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Affiliation(s)
- Kevin D Deem
- Department of Biology, Miami University, Oxford, OH, 45056, USA
- Department of Biology, University of Rochester, Rochester, NY, 14627, USA
| | - Marc S Halfon
- Department of Biochemistry, University at Buffalo-State University of New York, Buffalo, NY, 14203, USA
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2
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Giraldo D, Hammond AM, Wu J, Feole B, Al-Saloum N, McMeniman CJ. An expanded neurogenetic toolkit to decode olfaction in the African malaria mosquito Anopheles gambiae. CELL REPORTS METHODS 2024; 4:100714. [PMID: 38412833 PMCID: PMC10921037 DOI: 10.1016/j.crmeth.2024.100714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/01/2023] [Accepted: 01/29/2024] [Indexed: 02/29/2024]
Abstract
Anopheles gambiae uses its sense of smell to hunt humans. We report a two-step method yielding cell-type-specific driver lines for enhanced neuroanatomical and functional studies of its olfactory system. We first integrated a driver-responder-marker (DRM) system cassette consisting of a linked T2A-QF2 driver, QUAS-GFP responder, and a gut-specific transgenesis marker into four chemoreceptor genes (Ir25a, Ir76b, Gr22, and orco) using CRISPR-Cas9-mediated homology-directed repair. The DRM system facilitated rapid selection of in-frame integrations via screening for GFP+ olfactory sensory neurons (OSNs) in G1 larval progeny, even at genomic loci such as orco where we found the transgenesis marker was not visible. Next, we converted these DRM integrations into T2A-QF2 driver-marker lines by Cre-loxP excision of the GFP responder, making them suitable for binary use in transcuticular calcium imaging. These cell-type-specific driver lines tiling key OSN subsets will support systematic efforts to decode olfaction in this prolific malaria vector.
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Affiliation(s)
- Diego Giraldo
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Andrew M Hammond
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Life Sciences, Imperial College London, London, UK
| | - Jinling Wu
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Brandon Feole
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Noor Al-Saloum
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Conor J McMeniman
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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3
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Poulton BC, Colman F, Anthousi A, Sattelle DB, Lycett GJ. Aedes aegypti CCEae3A carboxylase expression confers carbamate, organophosphate and limited pyrethroid resistance in a model transgenic mosquito. PLoS Negl Trop Dis 2024; 18:e0011595. [PMID: 38377131 PMCID: PMC10906864 DOI: 10.1371/journal.pntd.0011595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 03/01/2024] [Accepted: 01/26/2024] [Indexed: 02/22/2024] Open
Abstract
Insecticide resistance is a serious threat to our ability to control mosquito vectors which transmit pathogens including malaria parasites and arboviruses. Understanding the underlying mechanisms is an essential first step in tackling the challenges presented by resistance. This study aimed to functionally characterise the carboxylesterase, CCEae3A, the elevated expression of which has been implicated in temephos resistance in Aedes aegypti and Aedes albopictus larvae. Using our GAL4/UAS expression system, already established in insecticide-sensitive Anopheles gambiae mosquitoes, we produced transgenic An. gambiae mosquitoes that express an Ae. aegypti CCEae3A ubiquitously. This new transgenic line permits examination of CCEae3A expression in a background in which there is not a clear orthologue in Vectorbase and allows comparison with existing An. gambiae GAL4-UAS lines. Insecticide resistance profiling of these transgenic An. gambiae larvae indicated significant increases in resistance ratio for three organophosphate insecticides, temephos (6), chloropyriphos (6.6) and fenthion (3.2) when compared to the parental strain. Cross resistance to adulticides from three major insecticide classes: organophosphates (malathion, fenitrothion and pirimiphos methyl), carbamates (bendiocarb and propoxur) and pyrethroid (alpha-cypermethrin) was also detected. Resistance to certain organophosphates and carbamates validates conclusions drawn from previous expression and phenotypic data. However, detection of resistance to pirimiphos methyl and alphacypermethrin has not previously been formally associated with CCEae3A, despite occurring in Ae. aegypti strains where this gene was upregulated. Our findings highlight the importance of characterising individual resistance mechanisms, thereby ensuring accurate information is used to guide future vector control strategies.
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Affiliation(s)
- Beth C. Poulton
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Fraser Colman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Amalia Anthousi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - David B. Sattelle
- Division of Medicine, University College London, London, United Kingdom
| | - Gareth J. Lycett
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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4
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Bottino-Rojas V, James AA. Mosquito Transposon-Mediated Transgenesis. Cold Spring Harb Protoc 2023:pdb.top107687. [PMID: 37816607 PMCID: PMC11025883 DOI: 10.1101/pdb.top107687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Transposon-mediated transgenesis of mosquito vectors of disease pathogens followed the early success of transgenesis in the vinegar fly, Drosophila melanogaster The P transposable element used in Drosophila does not function canonically in mosquitoes, and repeatable, routine transgenesis in mosquitoes was not accomplished until new transposable elements were discovered and validated. A number of distinct transposons were subsequently identified that mediate the introduction of exogenous DNA in a stable and heritable manner in mosquito species, including members of the genera Aedes, Anopheles, and Culex The most versatile element, piggyBac, is functional in all of these mosquito genera, as well as in many other insects in diverse orders, and has been used extensively outside the class. Transposon-mediated transgenesis of recessive and dominant marker genes and reporter systems has been used to define functional fragments of gene control sequences, introduce exogenous DNA encoding products beneficial to medical interests, and act as "enhancer traps" to identify endogenous genes with specific expression characteristics.
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Affiliation(s)
- Vanessa Bottino-Rojas
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California 92697-4500, USA
| | - Anthony A James
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California 92697-4500, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, USA
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5
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Sagna AB, Zéla L, Ouedraogo COW, Pooda SH, Porciani A, Furnival-Adams J, Lado P, Somé AF, Pennetier C, Chaccour CJ, Dabiré RK, Mouline K. Ivermectin as a novel malaria control tool: Getting ahead of the resistance curse. Acta Trop 2023; 245:106973. [PMID: 37352998 DOI: 10.1016/j.actatropica.2023.106973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 06/25/2023]
Abstract
Reduction in malaria clinical cases is strongly dependent on the ability to prevent Anopheles infectious bites. Vector control strategies using long-lasting insecticidal nets and indoor residual spraying with insecticides have contributed to significantly reduce the incidence of malaria in many endemic countries, especially in the Sub-Saharan region. However, global progress in reducing malaria cases has plateaued since 2015 mostly due to the increased insecticide resistance and behavioral changes in Anopheles vectors. Additional control strategies are thus required to further reduce the burden of malaria and contain the spread of resistant and invasive Anopheles vectors. The use of endectocides such as ivermectin as an additional malaria control tool is now receiving increased attention, driven by its different mode of action compared to insecticides used so far and its excellent safety record for humans. In this opinion article, we discuss the advantages and disadvantages of using ivermectin for malaria control with a focus on the risk of selecting ivermectin resistance in malaria vectors. We also highlight the importance of understanding how ivermectin resistance could develop in mosquitoes and what its underlying mechanisms and associated molecular markers are, and propose a research agenda to manage this phenomenon.
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Affiliation(s)
- André B Sagna
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France.
| | - Lamidi Zéla
- Centre International de Recherche-Développement sur l'Elevage en zone Subhumide, Bobo-Dioulasso, Burkina Faso
| | - Cheick Oumar W Ouedraogo
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Centre National de Recherche Scientifique et Technologique, Bobo-Dioulasso, Burkina Faso
| | - Sié H Pooda
- Centre International de Recherche-Développement sur l'Elevage en zone Subhumide, Bobo-Dioulasso, Burkina Faso; Université de Dédougou, Dédougou, Burkina Faso
| | | | | | - Paula Lado
- Center for Vector-borne Infectious Diseases, Colorado State University, Fort Collins, CO, USA
| | - Anyirékun F Somé
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Centre National de Recherche Scientifique et Technologique, Bobo-Dioulasso, Burkina Faso
| | - Cédric Pennetier
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
| | - Carlos J Chaccour
- ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain; Centro de Investigación Biomédica en Red de Enfermedades Infecciosas, Madrid, Spain; Universidad de Navarra, Pamplona, Spain
| | - Roch K Dabiré
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Centre National de Recherche Scientifique et Technologique, Bobo-Dioulasso, Burkina Faso
| | - Karine Mouline
- MIVEGEC, University of Montpellier, IRD, CNRS, Montpellier, France
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6
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Bottino-Rojas V, James AA. Use of Insect Promoters in Genetic Engineering to Control Mosquito-Borne Diseases. Biomolecules 2022; 13:biom13010016. [PMID: 36671401 PMCID: PMC9855440 DOI: 10.3390/biom13010016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
Mosquito transgenesis and gene-drive technologies provide the basis for developing promising new tools for vector-borne disease prevention by either suppressing wild mosquito populations or reducing their capacity from transmitting pathogens. Many studies of the regulatory DNA and promoters of genes with robust sex-, tissue- and stage-specific expression profiles have supported the development of new tools and strategies that could bring mosquito-borne diseases under control. Although the list of regulatory elements available is significant, only a limited set of those can reliably drive spatial-temporal expression. Here, we review the advances in our ability to express beneficial and other genes in mosquitoes, and highlight the information needed for the development of new mosquito-control and anti-disease strategies.
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Affiliation(s)
- Vanessa Bottino-Rojas
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, USA
| | - Anthony A. James
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697, USA
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
- Correspondence:
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7
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Genetics tools for corpora allata specific gene expression in Aedes aegypti mosquitoes. Sci Rep 2022; 12:20426. [PMID: 36443489 PMCID: PMC9705396 DOI: 10.1038/s41598-022-25009-4] [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: 03/23/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Juvenile hormone (JH) is synthesized by the corpora allata (CA) and controls development and reproduction in insects. Therefore, achieving tissue-specific expression of transgenes in the CA would be beneficial for mosquito research and control. Different CA promoters have been used to drive transgene expression in Drosophila, but mosquito CA-specific promoters have not been identified. Using the CRISPR/Cas9 system, we integrated transgenes encoding the reporter green fluorescent protein (GFP) close to the transcription start site of juvenile hormone acid methyl transferase (JHAMT), a locus encoding a JH biosynthetic enzyme, specifically and highly expressed in the CA of Aedes aegypti mosquitoes. Transgenic individuals showed specific GFP expression in the CA but failed to reproduce the full pattern of jhamt spatiotemporal expression. In addition, we created GeneSwitch driver and responder mosquito lines expressing an inducible fluorescent marker, enabling the temporal regulation of the transgene via the presence or absence of an inducer drug. The use of the GeneSwitch system has not previously been reported in mosquitoes and provides a new inducible binary system that can control transgene expression in Aedes aegypti.
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8
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Krzywinska E, Ferretti L, Krzywinski J. Establishment and a comparative transcriptomic analysis of a male-specific cell line from the African malaria mosquito Anopheles gambiae. Sci Rep 2022; 12:6885. [PMID: 35477969 PMCID: PMC9046191 DOI: 10.1038/s41598-022-10686-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/12/2022] [Indexed: 11/18/2022] Open
Abstract
Cell lines allow studying various biological processes that may not be easily tractable in whole organisms. Here, we have established the first male-specific cell line from the African malaria mosquito, Anopheles gambiae. The cells, named AgMM and derived from the sex-sorted neonate larvae, were able to undergo spontaneous contractions for a number of passages following establishment, indicating their myoblast origin. Comparison of their transcriptome to the transcriptome of an A. gambiae-derived Sua5.1 hemocyte cells revealed distinguishing molecular signatures of each cell line, including numerous muscle-related genes that were highly and uniquely expressed in the AgMM cells. Moreover, the AgMM cells express the primary sex determiner gene Yob and support male sex determination and dosage compensation pathways. Therefore, the AgMM cell line represents a valuable tool for molecular and biochemical in vitro studies of these male-specific processes. In a broader context, a rich transcriptomic data set generated in this study contributes to a better understanding of transcribed regions of the A. gambiae genome and sheds light on the biology of both cell types, facilitating their anticipated use for various cell-based assays.
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Affiliation(s)
| | - Luca Ferretti
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK
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9
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Fölsz O, Lin CC, Task D, Riabinina O, Potter CJ. The Q-system: A Versatile Repressible Binary Expression System. Methods Mol Biol 2022; 2540:35-78. [PMID: 35980572 DOI: 10.1007/978-1-0716-2541-5_2] [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] [Indexed: 06/15/2023]
Abstract
Binary expression systems are useful genetic tools for experimentally labeling or manipulating the function of defined cells. The Q-system is a repressible binary expression system that consists of a transcription factor QF (and the recently improved QF2/QF2w), the inhibitor QS, a QUAS-geneX effector, and a drug that inhibits QS (quinic acid). The Q-system can be used alone or in combination with other binary expression systems, such as GAL4/UAS and LexA/LexAop. In this review chapter, we discuss the past, present, and future of the Q-system for applications in Drosophila and other organisms. We discuss the in vivo application of the Q-system for transgenic labeling, the modular nature of QF that allows chimeric or split transcriptional activators to be developed, its temporal control by quinic acid, new methods to generate QF2 reagents, intersectional expression labeling, and its recent adoption into many emerging experimental species.
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Affiliation(s)
- Orsolya Fölsz
- Department of Biosciences, Durham University, Durham, UK
| | - Chun-Chieh Lin
- Department of Pathology and Laboratory Medicine, Giesel School of Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
| | - Darya Task
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | | | - Christopher J Potter
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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10
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Schember I, Halfon MS. Identification of new Anopheles gambiae transcriptional enhancers using a cross-species prediction approach. INSECT MOLECULAR BIOLOGY 2021; 30:410-419. [PMID: 33866636 PMCID: PMC8266755 DOI: 10.1111/imb.12705] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 02/09/2021] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
The success of transgenic mosquito vector control approaches relies on well-targeted gene expression, requiring the identification and characterization of a diverse set of mosquito promoters and transcriptional enhancers. However, few enhancers have been characterized in Anopheles gambiae to date. Here, we employ the SCRMshaw method we previously developed to predict enhancers in the A. gambiae genome, preferentially targeting vector-relevant tissues such as the salivary glands, midgut and nervous system. We demonstrate a high overall success rate, with at least 8 of 11 (73%) tested sequences validating as enhancers in an in vivo xenotransgenic assay. Four tested sequences drive expression in either the salivary gland or the midgut, making them directly useful for probing the biology of these infection-relevant tissues. The success of our study suggests that computational enhancer prediction should serve as an effective means for identifying A. gambiae enhancers with activity in tissues involved in malaria propagation and transmission.
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Affiliation(s)
- Isabella Schember
- Department of Biochemistry, University at Buffalo-State University of New York, Buffalo, NY 14203
| | - Marc S. Halfon
- Department of Biochemistry, University at Buffalo-State University of New York, Buffalo, NY 14203
- Department of Biomedical Informatics, University at Buffalo-State University of New York, Buffalo, NY 14203
- Department of Biological Sciences, University at Buffalo-State University of New York, Buffalo, NY 14203
- NY State Center of Excellence in Bioinformatics & Life Sciences, Buffalo, NY 14203
- Department of Molecular and Cellular Biology and Program in Cancer Genetics, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263
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11
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Caragata EP, Dong S, Dong Y, Simões ML, Tikhe CV, Dimopoulos G. Prospects and Pitfalls: Next-Generation Tools to Control Mosquito-Transmitted Disease. Annu Rev Microbiol 2021; 74:455-475. [PMID: 32905752 DOI: 10.1146/annurev-micro-011320-025557] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mosquito-transmitted diseases, including malaria and dengue, are a major threat to human health around the globe, affecting millions each year. A diverse array of next-generation tools has been designed to eliminate mosquito populations or to replace them with mosquitoes that are less capable of transmitting key pathogens. Many of these new approaches have been built on recent advances in CRISPR/Cas9-based genome editing. These initiatives have driven the development of pathogen-resistant lines, new genetics-based sexing methods, and new methods of driving desirable genetic traits into mosquito populations. Many other emerging tools involve microorganisms, including two strategies involving Wolbachia that are achieving great success in the field. At the same time, other mosquito-associated bacteria, fungi, and even viruses represent untapped sources of new mosquitocidal or antipathogen compounds. Although there are still hurdles to be overcome, the prospect that such approaches will reduce the impact of these diseases is highly encouraging.
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Affiliation(s)
- E P Caragata
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA; , , , , ,
| | - S Dong
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA; , , , , ,
| | - Y Dong
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA; , , , , ,
| | - M L Simões
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA; , , , , ,
| | - C V Tikhe
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA; , , , , ,
| | - G Dimopoulos
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA; , , , , ,
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12
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Driesschaert B, Mergan L, Temmerman L. Conditional gene expression in invertebrate animal models. J Genet Genomics 2021; 48:14-31. [PMID: 33814307 DOI: 10.1016/j.jgg.2021.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/11/2020] [Accepted: 01/08/2021] [Indexed: 10/22/2022]
Abstract
A mechanistic understanding of biology requires appreciating spatiotemporal aspects of gene expression and its functional implications. Conditional expression allows for (ir)reversible switching of genes on or off, with the potential of spatial and/or temporal control. This provides a valuable complement to the more often used constitutive gene (in)activation through mutagenesis, providing tools to answer a wider array of research questions across biological disciplines. Spatial and/or temporal control are granted primarily by (combinations of) specific promoters, temperature regimens, compound addition, or illumination. The use of such genetic tool kits is particularly widespread in invertebrate animal models because they can be applied to study biological processes in short time frames and on large scales, using organisms amenable to easy genetic manipulation. Recent years witnessed an exciting expansion and optimization of such tools, of which we provide a comprehensive overview and discussion regarding their use in invertebrates. The mechanism, applicability, benefits, and drawbacks of each of the systems, as well as further developments to be expected in the foreseeable future, are highlighted.
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Affiliation(s)
- Brecht Driesschaert
- Animal Physiology and Neurobiology, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59 - Box 2465, B-3000 Leuven, Belgium
| | - Lucas Mergan
- Animal Physiology and Neurobiology, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59 - Box 2465, B-3000 Leuven, Belgium
| | - Liesbet Temmerman
- Animal Physiology and Neurobiology, Department of Biology, University of Leuven (KU Leuven), Naamsestraat 59 - Box 2465, B-3000 Leuven, Belgium.
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13
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Grigoraki L, Grau-Bové X, Carrington Yates H, Lycett GJ, Ranson H. Isolation and transcriptomic analysis of Anopheles gambiae oenocytes enables the delineation of hydrocarbon biosynthesis. eLife 2020; 9:e58019. [PMID: 32538778 PMCID: PMC7351493 DOI: 10.7554/elife.58019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/12/2020] [Indexed: 12/29/2022] Open
Abstract
The surface of insects is coated in cuticular hydrocarbons (CHCs); variations in the composition of this layer affect a range of traits including adaptation to arid environments and defence against pathogens and toxins. In the African malaria vector, Anopheles gambiae quantitative and qualitative variance in CHC composition have been associated with speciation, ecological habitat and insecticide resistance. Understanding how these modifications arise will inform us of how mosquitoes are responding to climate change and vector control interventions. CHCs are synthesised in sub-epidermal cells called oenocytes that are very difficult to isolate from surrounding tissues. Here we utilise a transgenic line with fluorescent oenocytes to purify these cells for the first time. Comparative transcriptomics revealed the enrichment of biological processes related to long chain fatty acyl-CoA biosynthesis and elongation of mono-, poly-unsaturated and saturated fatty acids and enabled us to delineate, and partially validate, the hydrocarbon biosynthetic pathway in An. gambiae.
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Affiliation(s)
- Linda Grigoraki
- Liverpool School of Tropical Medicine, Vector Biology DepartmentLiverpoolUnited Kingdom
| | - Xavier Grau-Bové
- Liverpool School of Tropical Medicine, Vector Biology DepartmentLiverpoolUnited Kingdom
| | | | - Gareth J Lycett
- Liverpool School of Tropical Medicine, Vector Biology DepartmentLiverpoolUnited Kingdom
| | - Hilary Ranson
- Liverpool School of Tropical Medicine, Vector Biology DepartmentLiverpoolUnited Kingdom
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14
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Pondeville E, Puchot N, Parvy JP, Carissimo G, Poidevin M, Waterhouse RM, Marois E, Bourgouin C. Hemocyte-targeted gene expression in the female malaria mosquito using the hemolectin promoter from Drosophila. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 120:103339. [PMID: 32105779 PMCID: PMC7181189 DOI: 10.1016/j.ibmb.2020.103339] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 06/10/2023]
Abstract
Hemocytes, the immune cells in mosquitoes, participate in immune defenses against pathogens including malaria parasites. Mosquito hemocytes can also be infected by arthropod-borne viruses but the pro- or anti-viral nature of this interaction is unknown. Although there has been progress on hemocyte characterization during pathogen infection in mosquitoes, the specific contribution of hemocytes to immune responses and the hemocyte-specific functions of immune genes and pathways remain unresolved due to the lack of genetic tools to manipulate gene expression in these cells specifically. Here, we used the Gal4-UAS system to characterize the activity of the Drosophila hemocyte-specific hemolectin promoter in the adults of Anopheles gambiae, the malaria mosquito. We established an hml-Gal4 driver line that we further crossed to a fluorescent UAS responder line, and examined the expression pattern in the adult progeny driven by the hml promoter. We show that the hml regulatory region drives hemocyte-specific transgene expression in a subset of hemocytes, and that transgene expression is triggered after a blood meal. The hml promoter drives transgene expression in differentiating prohemocytes as well as in differentiated granulocytes. Analysis of different immune markers in hemocytes in which the hml promoter drives transgene expression revealed that this regulatory region could be used to study phagocytosis as well as melanization. Finally, the hml promoter drives transgene expression in hemocytes in which o'nyong-nyong virus replicates. Altogether, the Drosophila hml promoter constitutes a good tool to drive transgene expression in hemocyte only and to analyze the function of these cells and the genes they express during pathogen infection in Anopheles gambiae.
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Affiliation(s)
- Emilie Pondeville
- CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France.
| | - Nicolas Puchot
- CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France
| | | | - Guillaume Carissimo
- CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France
| | - Mickael Poidevin
- Centre de Génétique Moléculaire, CNRS UPR 2167, Gif-sur-Yvette, France
| | - Robert M Waterhouse
- Department of Ecology and Evolution, Swiss Institute of Bioinformatics, University of Lausanne, 1015, Lausanne, Switzerland
| | - Eric Marois
- CNRS UPR9022, INSERM U1257, Université de Strasbourg, Strasbourg, France
| | - Catherine Bourgouin
- CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France.
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15
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Tomoyasu Y, Halfon MS. How to study enhancers in non-traditional insect models. ACTA ACUST UNITED AC 2020; 223:223/Suppl_1/jeb212241. [PMID: 32034049 DOI: 10.1242/jeb.212241] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transcriptional enhancers are central to the function and evolution of genes and gene regulation. At the organismal level, enhancers play a crucial role in coordinating tissue- and context-dependent gene expression. At the population level, changes in enhancers are thought to be a major driving force that facilitates evolution of diverse traits. An amazing array of diverse traits seen in insect morphology, physiology and behavior has been the subject of research for centuries. Although enhancer studies in insects outside of Drosophila have been limited, recent advances in functional genomic approaches have begun to make such studies possible in an increasing selection of insect species. Here, instead of comprehensively reviewing currently available technologies for enhancer studies in established model organisms such as Drosophila, we focus on a subset of computational and experimental approaches that are likely applicable to non-Drosophila insects, and discuss the pros and cons of each approach. We discuss the importance of validating enhancer function and evaluate several possible validation methods, such as reporter assays and genome editing. Key points and potential pitfalls when establishing a reporter assay system in non-traditional insect models are also discussed. We close with a discussion of how to advance enhancer studies in insects, both by improving computational approaches and by expanding the genetic toolbox in various insects. Through these discussions, this Review provides a conceptual framework for studying the function and evolution of enhancers in non-traditional insect models.
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Affiliation(s)
| | - Marc S Halfon
- Department of Biochemistry, University at Buffalo-State University of New York, Buffalo, NY 14203, USA
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16
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Functional genetic validation of key genes conferring insecticide resistance in the major African malaria vector, Anopheles gambiae. Proc Natl Acad Sci U S A 2019; 116:25764-25772. [PMID: 31801878 PMCID: PMC6926047 DOI: 10.1073/pnas.1914633116] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Insecticide resistance in Anopheles gambiae mosquitoes can derail malaria control programs, and to overcome it, we need to discover the underlying molecular basis. Here, we characterize 3 genes most often associated with insecticide resistance directly by their overproduction in genetically modified An. gambiae. We show that overexpression of each gene confers resistance to representatives of at least 1 insecticide class, and taken together, the 3 genes provide cross-resistance to all 4 major insecticide classes currently used in public health. These data validate the candidate genes as markers to monitor the spread of resistance in mosquito populations. The modified mosquitoes produced are also valuable tools to prescreen the efficacy of new insecticides against existing resistance mechanisms. Resistance in Anopheles gambiae to members of all 4 major classes (pyrethroids, carbamates, organochlorines, and organophosphates) of public health insecticides limits effective control of malaria transmission in Africa. Increase in expression of detoxifying enzymes has been associated with insecticide resistance, but their direct functional validation in An. gambiae is still lacking. Here, we perform transgenic analysis using the GAL4/UAS system to examine insecticide resistance phenotypes conferred by increased expression of the 3 genes—Cyp6m2, Cyp6p3, and Gste2—most often found up-regulated in resistant An. gambiae. We report evidence in An. gambiae that organophosphate and organochlorine resistance is conferred by overexpression of GSTE2 in a broad tissue profile. Pyrethroid and carbamate resistance is bestowed by similar Cyp6p3 overexpression, and Cyp6m2 confers only pyrethroid resistance when overexpressed in the same tissues. Conversely, such Cyp6m2 overexpression increases susceptibility to the organophosphate malathion, presumably due to conversion to the more toxic metabolite, malaoxon. No resistant phenotypes are conferred when either Cyp6 gene overexpression is restricted to the midgut or oenocytes, indicating that neither tissue is involved in insecticide resistance mediated by the candidate P450s examined. Validation of genes conferring resistance provides markers to guide control strategies, and the observed negative cross-resistance due to Cyp6m2 gives credence to proposed dual-insecticide strategies to overcome pyrethroid resistance. These transgenic An. gambiae-resistant lines are being used to test the “resistance-breaking” efficacy of active compounds early in their development.
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17
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Split-QF System for Fine-Tuned Transgene Expression in Drosophila. Genetics 2019; 212:53-63. [PMID: 30862621 PMCID: PMC6499530 DOI: 10.1534/genetics.119.302034] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 03/03/2019] [Indexed: 11/18/2022] Open
Abstract
The Q-system is a binary expression system that works well across species. Here, we report the development and demonstrate the applications of a split-QF system that drives strong expression in Drosophila, is repressible by QS, and is inducible by a small nontoxic molecule (quinic acid). The split-QF system is fully compatible with existing split-GAL4 and split-LexA lines, thus greatly expanding the range of possible advanced intersectional experiments and anatomical, physiological, and behavioral assays in Drosophila, and in other organisms.
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18
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Adolfi A, Lycett GJ. Opening the toolkit for genetic analysis and control of Anopheles mosquito vectors. CURRENT OPINION IN INSECT SCIENCE 2018; 30:8-18. [PMID: 30553490 DOI: 10.1016/j.cois.2018.07.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 07/24/2018] [Indexed: 06/09/2023]
Abstract
Anopheles is the only genus of mosquitoes that transmit human malaria and consequently the focus of large scale genome and transcriptome-wide association studies. Genetic tools to define the function of the candidate genes arising from these analyses are vital. Moreover, genome editing offers the potential to modify Anopheles population structure at local and global scale to provide complementary tools towards the ultimate goal of malaria elimination. Major breakthroughs in Anopheles genetic analysis came with the development of germline transformation and RNA interference technology. Yet, the field has been revolutionised again by precise genome editing now possible through site-specific nucleases. Here we review the components of the current genetic toolkit available to study Anopheles, focusing particularly on how these technical advances are used to gain insight into malaria transmission and the design of genetic methods to control Anopheles vectors.
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Affiliation(s)
- Adriana Adolfi
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697-4500, USA
| | - Gareth John Lycett
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
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19
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Homem RA, Davies TGE. An overview of functional genomic tools in deciphering insecticide resistance. CURRENT OPINION IN INSECT SCIENCE 2018; 27:103-110. [PMID: 30025625 PMCID: PMC6060081 DOI: 10.1016/j.cois.2018.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 03/19/2018] [Accepted: 04/09/2018] [Indexed: 05/13/2023]
Abstract
In this short review, we highlight three functional genomic technologies that have recently been contributing to the understanding of the molecular mechanisms underpinning insecticide resistance: the GAL4/UAS system, a molecular tool used to express genes of interest in a spatiotemporal controlled manner; the RNAi system, which is used to knock-down gene expression; and the most recently developed gene editing tool, CRISPR/Cas9, which can be used to knock-out and knock-in sequences of interest.
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Affiliation(s)
- Rafael A Homem
- Department of Biointeractions and Crop Protection, Rothamsted Research, Harpenden AL5 2JQ, UK.
| | - Thomas G Emyr Davies
- Department of Biointeractions and Crop Protection, Rothamsted Research, Harpenden AL5 2JQ, UK.
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20
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Adolfi A, Pondeville E, Lynd A, Bourgouin C, Lycett GJ. Multi-tissue GAL4-mediated gene expression in all Anopheles gambiae life stages using an endogenous polyubiquitin promoter. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 96:1-9. [PMID: 29578046 DOI: 10.1016/j.ibmb.2018.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 03/12/2018] [Accepted: 03/19/2018] [Indexed: 06/08/2023]
Abstract
The ability to manipulate the Anopheles gambiae genome and alter gene expression effectively and reproducibly is a prerequisite for functional genetic analysis and for the development of novel control strategies in this important disease vector. However, in vivo transgenic analysis in mosquitoes is limited by the lack of promoters active ubiquitously. To address this, we used the GAL4/UAS system to investigate the promoter of the An. gambiae Polyubiquitin-c (PUBc) gene and demonstrated its ability to drive expression in mosquito cell culture before incorporation into An. gambiae transgenic driver lines. To generate such lines, piggyBac-mediated insertion was used to identify genomic regions able to sustain widespread expression and to create φC31 docking lines at these permissive sites. Patterns of expression induced by PUBc-GAL4 drivers carrying single intergenic insertions were assessed by crossing with a novel responder UAS-mCD8:mCherry line that was created by φC31-mediated integration. Amongst the drivers created at single, unique chromosomal integration loci, two were isolated that induced differential expression levels in a similar multiple-tissue spatial pattern throughout the mosquito life cycle. This work expands the tools available for An. gambiae functional analysis by providing a novel promoter for investigating phenotypes resulting from widespread multi-tissue expression, as well as identifying and tagging genomic sites that sustain broad transcriptional activity.
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Affiliation(s)
- Adriana Adolfi
- Liverpool School of Tropical Medicine, Vector Biology Department, Liverpool, UK.
| | - Emilie Pondeville
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS Unit URA3012, Paris, France.
| | - Amy Lynd
- Liverpool School of Tropical Medicine, Vector Biology Department, Liverpool, UK
| | - Catherine Bourgouin
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS Unit URA3012, Paris, France
| | - Gareth J Lycett
- Liverpool School of Tropical Medicine, Vector Biology Department, Liverpool, UK.
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21
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Riabinina O, Task D, Marr E, Lin CC, Alford R, O'Brochta DA, Potter CJ. Organization of olfactory centres in the malaria mosquito Anopheles gambiae. Nat Commun 2016; 7:13010. [PMID: 27694947 PMCID: PMC5063964 DOI: 10.1038/ncomms13010] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 08/25/2016] [Indexed: 02/01/2023] Open
Abstract
Mosquitoes are vectors for multiple infectious human diseases and use a variety of sensory cues (olfactory, temperature, humidity and visual) to locate a human host. A comprehensive understanding of the circuitry underlying sensory signalling in the mosquito brain is lacking. Here we used the Q-system of binary gene expression to develop transgenic lines of Anopheles gambiae in which olfactory receptor neurons expressing the odorant receptor co-receptor (Orco) gene are labelled with GFP. These neurons project from the antennae and maxillary palps to the antennal lobe (AL) and from the labella on the proboscis to the suboesophageal zone (SEZ), suggesting integration of olfactory and gustatory signals occurs in this brain region. We present detailed anatomical maps of olfactory innervations in the AL and the SEZ, identifying glomeruli that may respond to human body odours or carbon dioxide. Our results pave the way for anatomical and functional neurogenetic studies of sensory processing in mosquitoes.
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Affiliation(s)
- Olena Riabinina
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Darya Task
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Elizabeth Marr
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Chun-Chieh Lin
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
| | - Robert Alford
- University of Maryland College Park, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA
| | - David A O'Brochta
- University of Maryland College Park, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA
| | - Christopher J Potter
- The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, 434 Rangos Building, Baltimore, Maryland 21205, USA
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22
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Zhao B, Hou Y, Wang J, Kokoza VA, Saha TT, Wang XL, Lin L, Zou Z, Raikhel AS. Determination of juvenile hormone titers by means of LC-MS/MS/MS and a juvenile hormone-responsive Gal4/UAS system in Aedes aegypti mosquitoes. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2016; 77:69-77. [PMID: 27530057 PMCID: PMC5028310 DOI: 10.1016/j.ibmb.2016.08.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 05/16/2023]
Abstract
In anautogenous mosquitoes, juvenile hormone III (JH) plays an essential role in female post-eclosion (PE) development, preparing them for subsequent blood feeding and egg growth. We re-examined the JH titer during the reproductive cycle of female Aedes aegypti mosquitoes. Using liquid chromatography coupled with triple tandem mass spectrometry (LC-MS/MS/MS), we have shown that it reaches its peak at 48-54 h PE in the female hemolymph and at 72 h PE in whole body extracts. This method represents an effective assay for determination of JH titers. The 2.1-kb 5' promoter region of the Early Trypsin (ET) gene, which is specifically expressed in the female midgut under the control of JH during the PE phase, was utilized to genetically engineer the Ae. aegypti mosquito line with the ET-Gal4 activator. We then established the ET-GAL4>UAS-enhanced green fluorescent protein (EGFP) system in Ae. aegypti. In ET-Gal4>UAS-EGFP female mosquitoes, the intensity of the midgut-specific EGFP signal was observed to correspond to the ET gene transcript level and follow the JH titer during the PE phase. The EGFP signal and the EGFP transcript level were significantly diminished in midguts of transgenic female mosquitoes after RNA interference depletion of the JH receptor Methoprene-tolerant (Met), providing evidence of the control of ET gene expression by Met. Topical JH application caused premature enhancement of the EGFP signal and the EGFP transcript level in midguts of newly eclosed ET-Gal4>UAS-EGFP female mosquitoes, in which endogenous JH titer is still low. Hence, this novel ET-Gal4>UAS system permits JH-dependent gene overexpression in the midgut of Ae. aegypti female mosquitoes prior to a blood meal.
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Affiliation(s)
- Bo Zhao
- Department of Entomology, University of California, Riverside, CA, 92521, USA
| | - Yuan Hou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianjun Wang
- Department of Entomology, University of California, Riverside, CA, 92521, USA; College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China
| | - Vladimir A Kokoza
- Department of Entomology, University of California, Riverside, CA, 92521, USA
| | - Tusar T Saha
- Department of Entomology, University of California, Riverside, CA, 92521, USA
| | - Xue-Li Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ling Lin
- Department of Entomology, University of California, Riverside, CA, 92521, USA
| | - Zhen Zou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Alexander S Raikhel
- Department of Entomology, University of California, Riverside, CA, 92521, USA; The Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA.
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23
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24
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Li W, Ou G. The application of somatic CRISPR-Cas9 to conditional genome editing in Caenorhabditis elegans. Genesis 2016; 54:170-81. [PMID: 26934570 DOI: 10.1002/dvg.22932] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/23/2016] [Accepted: 02/25/2016] [Indexed: 12/20/2022]
Abstract
Forward and reverse genetic approaches have been well developed in the nematode Caenorhabditis elegans; however, efficient genetic tools to generate conditional gene mutations are still in high demand. Recently, the Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9 (CRISPR-Cas9) system for genome modification has provided an additional tool for C. elegans researchers to achieve simple and efficient conditional targeted mutagenesis. Here, we review recent advances in the somatic expression of Cas9 endonuclease for conditional gene editing. We present some practical considerations for improving the efficiency and reducing the off-target effects of somatic CRISPR-Cas9 and highlight a strategy to analyze somatic mutation at single-cell resolution. Finally, we outline future applications and consider challenges for this emerging genome editing platform that will need to be addressed in the future.
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Affiliation(s)
- Wei Li
- School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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25
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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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26
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Criscione F, O'Brochta DA, Reid W. Genetic technologies for disease vectors. CURRENT OPINION IN INSECT SCIENCE 2015; 10:90-97. [PMID: 29588019 DOI: 10.1016/j.cois.2015.04.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/17/2015] [Accepted: 04/20/2015] [Indexed: 06/08/2023]
Abstract
The first genetic technologies for insect vectors of disease were introduced 20 years ago. As of today there are 12 classes of genetic technologies used as functional genomic tools for insect vectors of important diseases. Although the applications of genetic technologies in insect disease vectors have been conducted primarily in mosquitoes, other insect systems could benefit from current technologies. While the various technological platforms are likely to function in diverse arthropods, the delivery of these technologies to cells and tissues of interest is the major technical constraint that limits their widespread adoption. Increased community resources of various types would enhance the adoption of these technologies and potentially eliminate technical limitations.
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Affiliation(s)
- Frank Criscione
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, 9600 Gudelsky Drive, Rockville, MD 20850, United States.
| | - David A O'Brochta
- Institute for Bioscience and Biotechnology Research, Department of Entomology, University of Maryland, College Park, 9600 Gudelsky Drive, Rockville, MD 20850, United States.
| | - William Reid
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, 9600 Gudelsky Drive, Rockville, MD 20850, United States.
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Abstract
Transgenesis is an essential tool to investigate gene function and to introduce desired characters in laboratory organisms. Setting-up transgenesis in non-model organisms is challenging due to the diversity of biological life traits and due to knowledge gaps in genomic information. Some procedures will be broadly applicable to many organisms, and others have to be specifically developed for the target species. Transgenesis in disease vector mosquitoes has existed since the 2000s but has remained limited by the delicate biology of these insects. Here, we report a compilation of the transgenesis tools that we have designed for the malaria vector Anopheles gambiae, including new docking strains, convenient transgenesis plasmids, a puromycin resistance selection marker, mosquitoes expressing cre recombinase, and various reporter lines defining the activity of cloned promoters. This toolbox contributed to rendering transgenesis routine in this species and is now enabling the development of increasingly refined genetic manipulations such as targeted mutagenesis. Some of the reagents and procedures reported here are easily transferable to other nonmodel species, including other disease vector or agricultural pest insects.
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28
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Zhao B, Kokoza VA, Saha TT, Wang S, Roy S, Raikhel AS. Regulation of the gut-specific carboxypeptidase: a study using the binary Gal4/UAS system in the mosquito Aedes aegypti. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2014; 54:1-10. [PMID: 25152428 PMCID: PMC4426967 DOI: 10.1016/j.ibmb.2014.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 07/31/2014] [Accepted: 08/03/2014] [Indexed: 05/26/2023]
Abstract
Pathogen transmission by mosquitoes is tightly linked to blood feeding which, in turn, is required for egg development. Studies of these processes would greatly benefit from genetic methods, such as the binary Gal4/UAS system. The latter has been well established for model organisms, but its availability is limited for mosquitoes. The objective of this study was to develop the blood-meal-activated, gut-specific Gal4/UAS system for the yellow-fever mosquito Aedes aegypti and utilize it to investigate the regulation of gut-specific gene expression. A 1.1-kb, 5(') upstream region of the carboxypeptidase A (CP) gene was used to genetically engineer the CP-Gal4 driver mosquito line. The CP-Gal4 specifically activated the Enhanced Green Fluorescent Protein (EGFP) reporter only after blood feeding in the gut of the CP-Gal4 > UAS-EGFP female Ae. aegypti. We used this system to study the regulation of CP gene expression. In vitro treatments with either amino acids (AAs) or insulin stimulated expression of the CP-Gal4 > UAS-EGFP transgene; no effect was observed with 20-hydroxyecdysone (20E) treatments. The transgene activation by AAs and insulin was blocked by rapamycin, the inhibitor of the Target-of-Rapamycin (TOR) kinase. RNA interference (RNAi) silence of the insulin receptor (IR) reduced the expression of the CP-Gal4 > UAS-EGFP transgene. Thus, in vitro and in vivo experiments have revealed that insulin and TOR pathways control expression of the digestive enzyme CP. In contrast, 20E, the major regulator of post-blood-meal vitellogenic events in female mosquitoes, has no role in regulating the expression of this gene. This novel CP-Gal4/UAS system permits functional testing of midgut-specific genes that are involved in blood digestion and interaction with pathogens in Ae. aegypti mosquitoes.
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Affiliation(s)
- Bo Zhao
- Department of Entomology, University of California Riverside, Riverside, CA 92521, USA; Graduate Program in Genetics, Genomics and Bioinformatics, University of California Riverside, Riverside, CA 92521, USA.
| | - Vladimir A Kokoza
- Department of Entomology, University of California Riverside, Riverside, CA 92521, USA; The Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, USA.
| | - Tusar T Saha
- Department of Entomology, University of California Riverside, Riverside, CA 92521, USA; The Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, USA.
| | - Stephanie Wang
- Honors Undergraduate Program, University of California Riverside, Riverside, CA 92521, USA.
| | - Sourav Roy
- Department of Entomology, University of California Riverside, Riverside, CA 92521, USA; The Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, USA.
| | - Alexander S Raikhel
- Department of Entomology, University of California Riverside, Riverside, CA 92521, USA; The Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, USA.
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Pondeville E, Puchot N, Meredith JM, Lynd A, Vernick KD, Lycett GJ, Eggleston P, Bourgouin C. Efficient ΦC31 integrase-mediated site-specific germline transformation of Anopheles gambiae. Nat Protoc 2014; 9:1698-712. [PMID: 24945385 DOI: 10.1038/nprot.2014.117] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Current transgenic methodology developed for mosquitoes has not been applied widely to the major malaria vector Anopheles gambiae, which has proved more difficult to genetically manipulate than other mosquito species and dipteran insects. In this protocol, we describe ΦC31-mediated site-specific integration of transgenes into the genome of A. gambiae. The ΦC31 system has many advantages over 'classical' transposon-mediated germline transformation systems, because it allows integration of large transgenes at specific, characterized genomic locations. Starting from a general protocol, we have optimized steps from embryo collection to co-injection of transgene-containing plasmid and in vitro-produced ΦC31 integrase mRNA. We also provide tips for screening transgenic larvae. The outlined procedure provides robust transformation in A. gambiae, resulting in homozygous transgenic lines in ∼2-3 months.
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Affiliation(s)
- Emilie Pondeville
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France
| | - Nicolas Puchot
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France
| | - Janet M Meredith
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, UK
| | - Amy Lynd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Kenneth D Vernick
- Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France
| | - Gareth J Lycett
- 1] Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK. [2]
| | - Paul Eggleston
- 1] Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, UK. [2]
| | - Catherine Bourgouin
- 1] Institut Pasteur, Genetics and Genomics of Insect Vectors, CNRS unit URA3012, Paris, France. [2]
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30
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Akbari OS, Papathanos PA, Sandler JE, Kennedy K, Hay BA. Identification of germline transcriptional regulatory elements in Aedes aegypti. Sci Rep 2014; 4:3954. [PMID: 24492376 PMCID: PMC3912481 DOI: 10.1038/srep03954] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 01/16/2014] [Indexed: 12/18/2022] Open
Abstract
The mosquito Aedes aegypti is the principal vector for the yellow fever and dengue viruses, and is also responsible for recent outbreaks of the alphavirus chikungunya. Vector control strategies utilizing engineered gene drive systems are being developed as a means of replacing wild, pathogen transmitting mosquitoes with individuals refractory to disease transmission, or bringing about population suppression. Several of these systems, including Medea, UD(MEL), and site-specific nucleases, which can be used to drive genes into populations or bring about population suppression, utilize transcriptional regulatory elements that drive germline-specific expression. Here we report the identification of multiple regulatory elements able to drive gene expression specifically in the female germline, or in the male and female germline, in the mosquito Aedes aegypti. These elements can also be used as tools with which to probe the roles of specific genes in germline function and in the early embryo, through overexpression or RNA interference.
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Affiliation(s)
- Omar S Akbari
- 1] Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA [2]
| | - Philippos A Papathanos
- 1] Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA [2]
| | - Jeremy E Sandler
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
| | - Katie Kennedy
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
| | - Bruce A Hay
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
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Lucas KJ, Myles KM, Raikhel AS. Small RNAs: a new frontier in mosquito biology. Trends Parasitol 2013; 29:295-303. [PMID: 23680188 DOI: 10.1016/j.pt.2013.04.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/06/2013] [Accepted: 04/08/2013] [Indexed: 12/23/2022]
Abstract
The discovery of small non-coding RNAs has revolutionized our understanding of regulatory networks governing multiple functions in animals and plants. However, our knowledge of mosquito small RNAs is limited. We discuss here the state of current knowledge regarding the roles of small RNAs and their targets in mosquitoes, and describe the ongoing efforts to understand the role of the RNA interference (RNAi) pathway in mosquito antiviral immunity and transposon silencing. Providing a clear picture into the role of small RNAs in mosquito vectors will pave the way to the utilization of these small molecules in developing novel control approaches that target mosquito immunity and/or reproductive events. Elucidation of the functions of small RNAs represents a new frontier in mosquito biology.
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Affiliation(s)
- Keira J Lucas
- Department of Entomology, University of California Riverside, Riverside, CA 92521, USA
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Carballar-Lejarazú R, Jasinskiene N, James AA. Exogenous gypsy insulator sequences modulate transgene expression in the malaria vector mosquito, Anopheles stephensi. Proc Natl Acad Sci U S A 2013; 110:7176-81. [PMID: 23584017 PMCID: PMC3645527 DOI: 10.1073/pnas.1304722110] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Malaria parasites are transmitted to humans by mosquitoes of the genus Anopheles, and these insects are the targets of innovative vector control programs. Proposed approaches include the use of genetic strategies based on transgenic mosquitoes to suppress or modify vector populations. Although substantial advances have been made in engineering resistant mosquito strains, limited efforts have been made in refining mosquito transgene expression, in particular attenuating the effects of insertions sites, which can result in variations in phenotypes and impacts on fitness due to the random integration of transposon constructs. A promising strategy to mitigate position effects is the identification of insulator or boundary DNA elements that could be used to isolate transgenes from the effects of their genomic environment. We applied quantitative approaches that show that exogenous insulator-like DNA derived from the Drosophila melanogaster gypsy retrotransposon can increase and stabilize transgene expression in transposon-mediated random insertions and recombinase-catalyzed, site-specific integrations in the malaria vector mosquito, Anopheles stephensi. These sequences can contribute to precise expression of transgenes in mosquitoes engineered for both basic and applied goals.
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Affiliation(s)
- Rebeca Carballar-Lejarazú
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and
| | - Nijole Jasinskiene
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and
| | - Anthony A. James
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900; and
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA 92697-4500
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33
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Nguyen C, Andrews E, Le C, Sun L, Annan Z, Clemons A, Severson DW, Duman-Scheel M. Functional genetic characterization of salivary gland development in Aedes aegypti. EvoDevo 2013; 4:9. [PMID: 23497573 PMCID: PMC3599648 DOI: 10.1186/2041-9139-4-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 12/07/2012] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Despite the devastating global impact of mosquito-borne illnesses on human health, very little is known about mosquito developmental biology. In this investigation, functional genetic analysis of embryonic salivary gland development was performed in Aedes aegypti, the dengue and yellow fever vector and an emerging model for vector mosquito development. Although embryonic salivary gland development has been well studied in Drosophila melanogaster, little is known about this process in mosquitoes or other arthropods. RESULTS Mosquitoes possess orthologs of many genes that regulate Drosophila melanogaster embryonic salivary gland development. The expression patterns of a large subset of these genes were assessed during Ae. aegypti development. These studies identified a set of molecular genetic markers for the developing mosquito salivary gland. Analysis of marker expression allowed for tracking of the progression of Ae. aegypti salivary gland development in embryos. In Drosophila, the salivary glands develop from placodes located in the ventral neuroectoderm. However, in Ae. aegypti, salivary marker genes are not expressed in placode-like patterns in the ventral neuroectoderm. Instead, marker gene expression is detected in salivary gland rudiments adjacent to the proventriculus. These observations highlighted the need for functional genetic characterization of mosquito salivary gland development. An siRNA- mediated knockdown strategy was therefore employed to investigate the role of one of the marker genes, cyclic-AMP response element binding protein A (Aae crebA), during Ae. aegypti salivary gland development. These experiments revealed that Aae crebA encodes a key transcriptional regulator of the secretory pathway in the developing Ae. aegypti salivary gland. CONCLUSIONS The results of this investigation indicated that the initiation of salivary gland development in Ae. aegypti significantly differs from that of D. melanogaster. Despite these differences, some elements of salivary gland development, including the ability of CrebA to regulate secretory gene expression, are conserved between the two species. These studies underscore the need for further analysis of mosquito developmental genetics and may foster comparative studies of salivary gland development in additional insect species.
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Affiliation(s)
- Chilinh Nguyen
- University of Notre Dame, Notre Dame, Eck Institute for Global Health and Department of Biological Sciences, Notre Dame, IN 46556, USA.
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Lucas K, Raikhel AS. Insect microRNAs: biogenesis, expression profiling and biological functions. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:24-38. [PMID: 23165178 PMCID: PMC3534889 DOI: 10.1016/j.ibmb.2012.10.009] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/24/2012] [Accepted: 10/28/2012] [Indexed: 05/09/2023]
Abstract
MicroRNAs (miRNA) are a class of endogenous regulatory RNA molecules 21-24 nucleotides in length that modulate gene expression at the post-transcriptional level via base pairing to target sites within messenger RNAs (mRNA). Typically, the miRNA "seed sequence" (nucleotides 2-8 at the 5' end) binds complementary seed match sites within the 3' untranslated region of mRNAs, resulting in either translational inhibition or mRNA degradation. MicroRNAs were first discovered in Caenorhabditis elegans and were shown to be involved in the timed regulation of developmental events. Since their discovery in the 1990s, thousands of potential miRNAs have since been identified in various organisms through small RNA cloning methods and/or computational prediction, and have been shown to play functionally important roles of gene regulation in invertebrates, vertebrates, plants, fungi and viruses. Numerous functions of miRNAs identified in Drosophila melanogaster have demonstrated a great significance of these regulatory molecules. However, elucidation of miRNA roles in non-drosophilid insects presents a challenging and important task.
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Affiliation(s)
- Keira Lucas
- Department of Entomology, University of California Riverside, Riverside, CA 92521, U.S.A
- Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, U.S.A
- Graduate Program in Genetics, Genomics and Bioinformatics, University of California Riverside, Riverside, CA 92521, U.S.A
| | - Alexander S. Raikhel
- Department of Entomology, University of California Riverside, Riverside, CA 92521, U.S.A
- Institute for Integrative Genome Biology, University of California Riverside, Riverside, CA 92521, U.S.A
- Corresponding author. Department of Entomology, University of California, Riverside, Riverside, CA 92521, U.S.A. Tel. +1 951 827 2129. (Keira Lucas); (Alexander S. Raikhel)
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Caljon G, De Vooght L, Van Den Abbeele J. Options for the delivery of anti-pathogen molecules in arthropod vectors. J Invertebr Pathol 2012; 112 Suppl:S75-82. [PMID: 22841635 DOI: 10.1016/j.jip.2012.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/15/2012] [Accepted: 05/18/2012] [Indexed: 10/28/2022]
Abstract
Blood feeding arthropods are responsible for the transmission of a large array of medically important infectious agents that include viruses, bacteria, protozoan parasites and helminths. The recent development of transgenic and paratransgenic technologies have enabled supplementing the immune system of these arthropod vectors with anti-pathogen effector molecules in view of compromising their vector competence for these microbial agents. The characteristics of the selected anti-pathogen compound will largely determine the efficacy and specificity of this approach. Low specificity will generally result in bystander effects, likely having a direct or indirect fitness cost for the arthropod. In contrast, the use of highly specific compounds from the adaptive immune system of vertebrates such as antibody derived fragments is more likely to enable highly specific effects without conferring a selective disadvantage to the (para)transgenic arthropods. Here, Nanobodies® are excellent candidates to increase the immune competence of arthropods. Moreover they were shown to exert a novel type of anti-pathogen activity that uniquely depends on their small size.
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Affiliation(s)
- Guy Caljon
- Department of Biomedical Sciences, Unit of Veterinary Protozoology, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium.
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