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Harrell RA. Mosquito Embryo Microinjection under Halocarbon Oil or in Aqueous Solution. Cold Spring Harb Protoc 2024; 2024:pdb.prot108203. [PMID: 37788868 DOI: 10.1101/pdb.prot108203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
The process of genetically modifying mosquitoes requires skilled delivery of reagents for modification. Plasmids, RNA, DNA, and/or protein must be transported into the developing embryo during an appropriate time in development when these agents will have access to the genome. Embryo microinjection has been the main method by which such modifying agents have been delivered. Ideally the microinjection process will deliver these modifying agents in sufficient quantity to effect the genetic modification without severely damaging or killing the injected embryo in the process. As semiaquatic insects, mosquitoes have embryos that are susceptible to desiccation and the degree to which embryos are susceptible is based on species. Two microinjection methods are outlined here. The first method describes embryo microinjections performed under Halocarbon-27 oil. The oil is used to reduce desiccation during the injection process. A second method limits desiccation by injecting the mosquito embryos in water. In both procedures, the embryos are first aligned and then injected before the embryos cellularize, ∼1 h and 45 min after oviposition.
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Affiliation(s)
- Robert A Harrell
- The Institute for Bioscience and Biotechnology Research, University of Maryland Insect Transformation Facility, Rockville, Maryland 20850, USA
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2
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Häcker I, Rehling T, Schlosser H, Mayorga-Ch D, Heilig M, Yan Y, Armbruster PA, Schetelig MF. Improved piggyBac Transformation with Capped Transposase mRNA in Pest Insects. Int J Mol Sci 2023; 24:15155. [PMID: 37894833 PMCID: PMC10606561 DOI: 10.3390/ijms242015155] [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: 08/31/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023] Open
Abstract
Creating transgenic insects is a key technology in insect genetics and molecular biology. A widely used instrument in insect transgenesis is the piggyBac transposase, resulting in essentially random genomic integrations. In contrast, site-specific recombinases allow the targeted integration of the transgene construct into a specific genomic target site. Both strategies, however, often face limitations due to low transgenesis efficiencies. We aimed to enhance transgenesis efficiencies by utilizing capped mRNA as a source of transposase or recombinase instead of a helper plasmid. A systematic comparison of transgenesis efficiencies in Aedes mosquitoes, as models for hard-to-transform insects, showed that suppling piggyBac transposase as mRNA increased the average transformation efficiency in Aedes aegypti from less than 5% with the plasmid source to about 50% with mRNA. Similar high activity was observed in Ae. albopictus with pBac mRNA. No efficiency differences between plasmid and mRNA were observed in recombination experiments. Furthermore, a hyperactive version of piggyBac transposase delivered as a plasmid did not improve the transformation efficiency in Ae. aegypti or the agricultural pest Drosophila suzukii. We believe that the use of mRNA has strong potential for enhancing piggyBac transformation efficiencies in other mosquitoes and important agricultural pests, such as tephritids.
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Affiliation(s)
- Irina Häcker
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, Winchesterstr. 2, 35394 Giessen, Germany (H.S.); (Y.Y.); (M.F.S.)
- Liebig Centre for Agroecology & Climate Impact Research, 35394 Giessen, Germany
| | - Tanja Rehling
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, Winchesterstr. 2, 35394 Giessen, Germany (H.S.); (Y.Y.); (M.F.S.)
- Liebig Centre for Agroecology & Climate Impact Research, 35394 Giessen, Germany
| | - Henrik Schlosser
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, Winchesterstr. 2, 35394 Giessen, Germany (H.S.); (Y.Y.); (M.F.S.)
| | - Daniela Mayorga-Ch
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, Winchesterstr. 2, 35394 Giessen, Germany (H.S.); (Y.Y.); (M.F.S.)
| | - Mara Heilig
- Department of Biology, Georgetown University, 37th and O Streets NW, Washington, DC 20057-1229, USA; (M.H.); (P.A.A.)
| | - Ying Yan
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, Winchesterstr. 2, 35394 Giessen, Germany (H.S.); (Y.Y.); (M.F.S.)
- Liebig Centre for Agroecology & Climate Impact Research, 35394 Giessen, Germany
| | - Peter A. Armbruster
- Department of Biology, Georgetown University, 37th and O Streets NW, Washington, DC 20057-1229, USA; (M.H.); (P.A.A.)
| | - Marc F. Schetelig
- Department of Insect Biotechnology in Plant Protection, Justus Liebig University Giessen, Winchesterstr. 2, 35394 Giessen, Germany (H.S.); (Y.Y.); (M.F.S.)
- Liebig Centre for Agroecology & Climate Impact Research, 35394 Giessen, Germany
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Alcalay Y, Fuchs S, Galizi R, Bernardini F, Haghighat-Khah RE, Rusch DB, Adrion JR, Hahn MW, Tortosa P, Rotenberry R, Papathanos PA. The Potential for a Released Autosomal X-Shredder Becoming a Driving-Y Chromosome and Invasively Suppressing Wild Populations of Malaria Mosquitoes. Front Bioeng Biotechnol 2021; 9:752253. [PMID: 34957064 PMCID: PMC8698249 DOI: 10.3389/fbioe.2021.752253] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/15/2021] [Indexed: 11/16/2022] Open
Abstract
Sex-ratio distorters based on X-chromosome shredding are more efficient than sterile male releases for population suppression. X-shredding is a form of sex distortion that skews spermatogenesis of XY males towards the preferential transmission of Y-bearing gametes, resulting in a higher fraction of sons than daughters. Strains harboring X-shredders on autosomes were first developed in the malaria mosquito Anopheles gambiae, resulting in strong sex-ratio distortion. Since autosomal X-shredders are transmitted in a Mendelian fashion and can be selected against, their frequency in the population declines once releases are halted. However, unintended transfer of X-shredders to the Y-chromosome could produce an invasive meiotic drive element, that benefits from its biased transmission to the predominant male-biased offspring and its effective shielding from female negative selection. Indeed, linkage to the Y-chromosome of an active X-shredder instigated the development of the nuclease-based X-shredding system. Here, we analyze mechanisms whereby an autosomal X-shredder could become unintentionally Y-linked after release by evaluating the stability of an established X-shredder strain that is being considered for release, exploring its potential for remobilization in laboratory and wild-type genomes of An. gambiae and provide data regarding expression on the mosquito Y-chromosome. Our data suggest that an invasive X-shredder resulting from a post-release movement of such autosomal transgenes onto the Y-chromosome is unlikely.
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Affiliation(s)
- Yehonatan Alcalay
- Department of Entomology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Silke Fuchs
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Roberto Galizi
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, United Kingdom
| | - Federica Bernardini
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, United States
| | - Jeffrey R Adrion
- Institute of Ecology and Evolution, University of Oregon, Eugene, OR, United States
| | - Matthew W Hahn
- Department of Biology, Indiana University, Bloomington, IN, United States.,Department of Computer Science, Indiana University, Bloomington, IN, United States
| | - Pablo Tortosa
- Unité Mixte de Recherche Processus Infectieux en Milieu Insulaire Tropical (UMR PIMIT), Université de La Réunion, INSERM 1187, CNRS 9192, IRD 249, Plateforme de Recherche CYROI, Saint Denis, France
| | - Rachel Rotenberry
- Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Philippos Aris Papathanos
- Department of Entomology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
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Billingsley PF, George KI, Eappen AG, Harrell RA, Alford R, Li T, Chakravarty S, Sim BKL, Hoffman SL, O'Brochta DA. Transient knockdown of Anopheles stephensi LRIM1 using RNAi increases Plasmodium falciparum sporozoite salivary gland infections. Malar J 2021; 20:284. [PMID: 34174879 PMCID: PMC8235909 DOI: 10.1186/s12936-021-03818-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/15/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum (Pf) sporozoites (PfSPZ) can be administered as a highly protective vaccine conferring the highest protection seen to date. Sanaria® PfSPZ vaccines are produced using aseptically reared Anopheles stephensi mosquitoes. The bionomics of sporogonic development of P. falciparum in A. stephensi to fully mature salivary gland PfSPZ is thought to be modulated by several components of the mosquito innate immune system. In order to increase salivary gland PfSPZ infections in A. stephensi and thereby increase vaccine production efficiency, a gene knock down approach was used to investigate the activity of the immune deficiency (IMD) signaling pathway downstream effector leucine-rich repeat immune molecule 1 (LRIM1), an antagonist to Plasmodium development. METHODS Expression of LRIM1 in A. stephensi was reduced following injection of double stranded (ds) RNA into mosquitoes. By combining the Gal4/UAS bipartite system with in vivo expression of short hairpin (sh) RNA coding for LRIM1 reduced expression of LRIM1 was targeted in the midgut, fat body, and salivary glands. RT-qPCR was used to demonstrate fold-changes in gene expression in three transgenic crosses and the effects on P. falciparum infections determined in mosquitoes showing the greatest reduction in LRIM1 expression. RESULTS LRIM1 expression could be reduced, but not completely silenced, by expression of LRIM1 dsRNA. Infections of P. falciparum oocysts and PfSPZ were consistently and significantly higher in transgenic mosquitoes than wild type controls, with increases in PfSPZ ranging from 2.5- to tenfold. CONCLUSIONS Plasmodium falciparum infections in A. stephensi can be increased following reduced expression of LRIM1. These data provide the springboard for more precise knockout of LRIM1 for the eventual incorporation of immune-compromised A. stephensi into manufacturing of Sanaria's PfSPZ products.
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Affiliation(s)
- Peter F Billingsley
- Sanaria Inc, Suite A209, 9800 Medical Center Drive, Rockville, MD, 20850, USA.
| | - Kasim I George
- Institute for Bioscience and Biotechnology Research and Department of Entomology, University of Maryland, Gudelsky Drive, Rockville, MD, 20850, USA
- Qiagen Inc, 19300 Germantown Road, Germantown, MD, 20874, USA
| | - Abraham G Eappen
- Sanaria Inc, Suite A209, 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | - Robert A Harrell
- Institute for Bioscience and Biotechnology Research and Department of Entomology, University of Maryland, Gudelsky Drive, Rockville, MD, 20850, USA
- Insect Transformation Facility, Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD, 20850, USA
| | - Robert Alford
- Institute for Bioscience and Biotechnology Research and Department of Entomology, University of Maryland, Gudelsky Drive, Rockville, MD, 20850, USA
- Insect Transformation Facility, Institute for Bioscience and Biotechnology Research, University of Maryland, 9600 Gudelsky Drive, Rockville, MD, 20850, USA
| | - Tao Li
- Sanaria Inc, Suite A209, 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | - Sumana Chakravarty
- Sanaria Inc, Suite A209, 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | - B Kim Lee Sim
- Sanaria Inc, Suite A209, 9800 Medical Center Drive, Rockville, MD, 20850, USA
- Protein Potential, Suite A209, 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | - Stephen L Hoffman
- Sanaria Inc, Suite A209, 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | - David A O'Brochta
- Institute for Bioscience and Biotechnology Research and Department of Entomology, University of Maryland, Gudelsky Drive, Rockville, MD, 20850, USA
- Foundation for the National Institutes of Health, 11400 Rockville Pike, Suite 600, North Bethesda, MD, 20852, USA
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Zapletal J, Najmitabrizi N, Erraguntla M, Lawley MA, Myles KM, Adelman ZN. Making gene drive biodegradable. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190804. [PMID: 33357058 PMCID: PMC7776940 DOI: 10.1098/rstb.2019.0804] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Gene drive systems have long been sought to modify mosquito populations and thus combat malaria and dengue. Powerful gene drive systems have been developed in laboratory experiments, but may never be used in practice unless they can be shown to be acceptable through rigorous field-based testing. Such testing is complicated by the anticipated difficulty in removing gene drive transgenes from nature. Here, we consider the inclusion of self-elimination mechanisms into the design of homing-based gene drive transgenes. This approach not only caused the excision of the gene drive transgene, but also generates a transgene-free allele resistant to further action by the gene drive. Strikingly, our models suggest that this mechanism, acting at a modest rate (10%) as part of a single-component system, would be sufficient to cause the rapid reversion of even the most robust homing-based gene drive transgenes, without the need for further remediation. Modelling also suggests that unlike gene drive transgenes themselves, self-eliminating transgene approaches are expected to tolerate substantial rates of failure. Thus, self-elimination technology may permit rigorous field-based testing of gene drives by establishing strict time limits on the existence of gene drive transgenes in nature, rendering them essentially biodegradable. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Josef Zapletal
- Department of Industrial and Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Neda Najmitabrizi
- Department of Industrial and Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Madhav Erraguntla
- Department of Industrial and Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Mark A Lawley
- Department of Industrial and Systems Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Kevin M Myles
- Department of Entomology and Agrilife Research, Texas A&M University, College Station, TX 77843, USA
| | - Zach N Adelman
- Department of Entomology and Agrilife Research, Texas A&M University, College Station, TX 77843, USA
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Ahmed HMM, Heese F, Wimmer EA. Improvement on the genetic engineering of an invasive agricultural pest insect, the cherry vinegar fly, Drosophila suzukii. BMC Genet 2020; 21:139. [PMID: 33339511 PMCID: PMC7747376 DOI: 10.1186/s12863-020-00940-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Background The invasive fly Drosophila suzukii has become an established fruit pest in Europe, the USA, and South America with no effective and safe pest management. Genetic engineering enables the development of transgene-based novel genetic control strategies against insect pests and disease vectors. This, however, requires the establishment of reliable germline transformation techniques. Previous studies have shown that D. suzukii is amenable to transgenesis using the transposon-based vectors piggyBac and Minos, site-specific recombination (lox/Cre), and CRISPR/Cas9 genome editing. Results We experienced differences in the usability of piggyBac-based germline transformation in different strains of D. suzukii: we obtained no transgenic lines in a US strain, a single rare transgenic line in an Italian strain, but observed a reliable transformation rate of 2.5 to 11% in a strain from the French Alps. This difference in efficiency was confirmed by comparative examination of these three strains. In addition, we used an attP landing site line to successfully established φC31-integrase-mediated plasmid integration at a rate of 10% and generated landing site lines with two attP sequences to effectively perform φC31-Recombinase Mediated Cassette Exchange (φC31-RMCE) with 11% efficiency. Moreover, we isolated and used the endogenous regulatory regions of Ds nanos to express φC31 integrase maternally to generate self-docking lines for φC31-RMCE. Besides, we isolated the promoter/enhancer of Ds serendipity α to drive the heterologous tetracycline-controlled transactivator (tTA) during early embryonic development and generated a testes-specific tTA driver line using the endogenous beta-2-tubulin (β2t) promoter/enhancer. Conclusion Our results provide evidence that the D. suzukii strain AM derived from the French Alps is more suitable for piggyBac germline transformation than other strains. We demonstrated the feasibility of using φC31-RMCE in the cherry vinegar fly and generated a set of lines that can be used for highly efficient integration of larger constructs. The φC31-based integration will facilitate modification and stabilization of previously generated transgenic lines that carry at least one attP site in the transgene construction. An early embryo-specific and a spermatogenesis-specific driver line were generated for future use of the binary expression system tet-off to engineer tissue- and stage-specific effector gene expression for genetic pest control strategies. Supplementary Information The online version contains supplementary material available at 10.1186/s12863-020-00940-5.
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Affiliation(s)
- Hassan M M Ahmed
- Department of Developmental Biology, Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology, Göttingen Center for Molecular Biosciences, Georg-August-University Göttingen, 37077, Göttingen, Germany.,Department of Crop Protection, Faculty of Agriculture-University of Khartoum, P.O. Box 32, 13314, Khartoum North, Khartoum, Sudan
| | - Fabienne Heese
- Department of Developmental Biology, Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology, Göttingen Center for Molecular Biosciences, Georg-August-University Göttingen, 37077, Göttingen, Germany
| | - Ernst A Wimmer
- Department of Developmental Biology, Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology, Göttingen Center for Molecular Biosciences, Georg-August-University Göttingen, 37077, Göttingen, Germany.
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Abstract
Vector control programs based on population reduction by matings with mass-released sterile insects require the release of only male mosquitoes, as the release of females, even if sterile, would increase the number of biting and potentially disease-transmitting individuals. While small-scale releases demonstrated the applicability of sterile males releases to control the yellow fever mosquito Aedes aegypti, large-scale programs for mosquitoes are currently prevented by the lack of efficient sexing systems in any of the vector species.Different approaches of sexing are pursued, including classical genetic and mechanical methods of sex separation. Another strategy is the development of transgenic sexing systems. Such systems already exist in other insect pests. Genome modification tools could be used to apply similar strategies to mosquitoes. Three major tools to modify mosquito genomes are currently used: transposable elements, site-specific recombination systems, and genome editing via TALEN or CRISPR/Cas. All three can serve the purpose of developing sexing systems and vector control strains in mosquitoes in two ways: first, via their use in basic research. A better understanding of mosquito biology, including the sex-determining pathways and the involved genes can greatly facilitate the development of sexing strains. Moreover, basic research can help to identify other regulatory elements and genes potentially useful for the construction of transgenic sexing systems. Second, these genome modification tools can be used to apply the gained knowledge to build and test mosquito sexing strains for vector control.
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Affiliation(s)
- Irina Häcker
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany.
| | - Marc F Schetelig
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
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Reid W, Pilitt K, Alford R, Cervantes-Medina A, Yu H, Aluvihare C, Harrell R, O'Brochta DA. An Anopheles stephensi Promoter-Trap: Augmenting Genome Annotation and Functional Genomics. G3 (BETHESDA, MD.) 2018; 8:3119-3130. [PMID: 30135106 PMCID: PMC6169391 DOI: 10.1534/g3.118.200347] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/15/2018] [Indexed: 12/20/2022]
Abstract
The piggyBac transposon was modified to generate gene trap constructs, which were then incorporated into the genome of the Asian malaria vector, Anopheles stephensi and remobilized through genetic crosses using a piggyBac transposase expressing line. A total of 620 remobilization events were documented, and 73 were further characterized at the DNA level to identify patterns in insertion site preferences, remobilization frequencies, and remobilization patterns. Overall, the use of the tetameric AmCyan reporter as the fusion peptide displayed a preference for insertion into the 5'-end of transcripts. Notably 183 - 44882 bp upstream of the An. stephensi v1.0 ab initio gene models, which demonstrated that the promoter regions for the genes of An. stephensi are further upstream of the 5'-proximal regions of the genes in the ab inito models than may be otherwise predicted. RNA-Seq transcript coverage supported the insertion of the splice acceptor gene trap element into 5'-UTR introns for nearly half of all insertions identified. The use of a gene trap element that prefers insertion into the 5'-end of genes supports the use of this technology for the random generation of knock-out mutants, as well as the experimental confirmation of 5'-UTR introns in An. stephensi.
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Affiliation(s)
- William Reid
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
| | - Kristina Pilitt
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
| | - Robert Alford
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
- Insect Transformation Facility, Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
| | - Adriana Cervantes-Medina
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
| | - Hao Yu
- Department of Plant Protection, Henan Institute of Science and Technology, East Street Huan-Lan, Xinxiang City, Henan Province 453003, CHINA
| | - Channa Aluvihare
- Insect Transformation Facility, Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
| | - Rob Harrell
- Insect Transformation Facility, Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
| | - David A O'Brochta
- Institute for Bioscience and Biotechnology Research, University of Maryland College Park, 9600 Gudelsky Drive, Rockville, MD 20850-3467
- Department of Entomology, University of Maryland College Park, 4112 Plant Sciences Building, College Park, MD 20742-4454
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Rhodes VL, Thomas MB, Michel K. The interplay between dose and immune system activation determines fungal infection outcome in the African malaria mosquito, Anopheles gambiae. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 85:125-133. [PMID: 29649553 PMCID: PMC5935592 DOI: 10.1016/j.dci.2018.04.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 04/05/2018] [Accepted: 04/06/2018] [Indexed: 05/27/2023]
Abstract
The Toll pathway is a central regulator of antifungal immunity in insects. In mosquitoes, the Toll pathway affects infections with the fungal entomopathogen, Beauveria bassiana, which is considered a potential mosquito biopesticide. We report here the use of B. bassiana strain I93-825 in Anopheles gambiae to analyze the impact of Toll pathway modulation on mosquito survival. Exposure to a narrow dose range of conidia by direct contact decreased mosquito longevity and median survival. In addition, fungal exposure dose correlated positively and linearly with hazard ratio. Increased Toll signaling by knockdown of its inhibitor, cactus, decreased survivorship of uninfected females, increased mosquito survival after low dose B. bassiana exposure, but had little effect following exposure to higher doses. This observed trade-off could have implications for development of B. bassiana as a prospective vector control tool. On the one hand, selection for small increases in mosquito immune signaling across a narrow dose range could impair efficacy of B. bassiana. On the other hand, costs of immunity and the capacity for higher doses of fungus to overwhelm immune responses could limit evolution of resistance.
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Affiliation(s)
- Victoria L Rhodes
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Matthew B Thomas
- Department of Entomology and Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kristin Michel
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
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Chu FC, Klobasa W, Grubbs N, Lorenzen MD. Development and use of a piggyBac-based jumpstarter system in Drosophila suzukii. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2018; 97. [PMID: 29194761 DOI: 10.1002/arch.21439] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Spotted wing drosophila, Drosophila suzukii, is an invasive pest that primarily attacks fresh, soft-skinned fruit. Although others have reported successful integration of marked piggyBac elements into the D. suzukii genome, with a very respectable transgenesis rate of ∼16%, here we take this work a step further by creating D. suzukii jumpstarter strains. These were generated through integration of a fluorescent-marked Minos element carrying a heat shock protein 70-driven piggyBac transposase gene. We demonstrate that there is a dramatic increase in transformation rates when germline transformation is performed in a transposase-expressing background. For example, we achieved transformation rates as high as 80% when microinjecting piggyBac-based plasmids into embryos derived from one of these D. suzukii jumpstarter strains. We also investigate the effect of insert size on transformation efficiency by testing the ability of the most efficient jumpstarter strain to catalyze integration of differently-sized piggyBac elements. Finally, we demonstrate the ability of a jumpstarter strain to remobilize an already-integrated piggyBac element to a new location, demonstrating that our jumpstarter strains could be used in conjunction with a piggyBac-based donor strain for genome-wide mutagenesis of D. suzukii.
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Affiliation(s)
- Fu-Chyun Chu
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - William Klobasa
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Nathaniel Grubbs
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Marcé D Lorenzen
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
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11
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Macias VM, Ohm JR, Rasgon JL. Gene Drive for Mosquito Control: Where Did It Come from and Where Are We Headed? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14091006. [PMID: 28869513 PMCID: PMC5615543 DOI: 10.3390/ijerph14091006] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 08/25/2017] [Accepted: 08/28/2017] [Indexed: 02/08/2023]
Abstract
Mosquito-borne pathogens place an enormous burden on human health. The existing toolkit is insufficient to support ongoing vector-control efforts towards meeting disease elimination and eradication goals. The perspective that genetic approaches can potentially add a significant set of tools toward mosquito control is not new, but the recent improvements in site-specific gene editing with CRISPR/Cas9 systems have enhanced our ability to both study mosquito biology using reverse genetics and produce genetics-based tools. Cas9-mediated gene-editing is an efficient and adaptable platform for gene drive strategies, which have advantages over innundative release strategies for introgressing desirable suppression and pathogen-blocking genotypes into wild mosquito populations; until recently, an effective gene drive has been largely out of reach. Many considerations will inform the effective use of new genetic tools, including gene drives. Here we review the lengthy history of genetic advances in mosquito biology and discuss both the impact of efficient site-specific gene editing on vector biology and the resulting potential to deploy new genetic tools for the abatement of mosquito-borne disease.
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Affiliation(s)
- Vanessa M Macias
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
| | - Johanna R Ohm
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
| | - Jason L Rasgon
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
- The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
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12
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Macias VM, Jimenez AJ, Burini-Kojin B, Pledger D, Jasinskiene N, Phong CH, Chu K, Fazekas A, Martin K, Marinotti O, James AA. nanos-Driven expression of piggyBac transposase induces mobilization of a synthetic autonomous transposon in the malaria vector mosquito, Anopheles stephensi. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 87:81-89. [PMID: 28676355 PMCID: PMC5580807 DOI: 10.1016/j.ibmb.2017.06.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 06/07/2023]
Abstract
Transposons are a class of selfish DNA elements that can mobilize within a genome. If mobilization is accompanied by an increase in copy number (replicative transposition), the transposon may sweep through a population until it is fixed in all of its interbreeding members. This introgression has been proposed as the basis for drive systems to move genes with desirable phenotypes into target species. One such application would be to use them to move a gene conferring resistance to malaria parasites throughout a population of vector mosquitos. We assessed the feasibility of using the piggyBac transposon as a gene-drive mechanism to distribute anti-malarial transgenes in populations of the malaria vector, Anopheles stephensi. We designed synthetic gene constructs that express the piggyBac transposase in the female germline using the control DNA of the An. stephensi nanos orthologous gene linked to marker genes to monitor inheritance. Two remobilization events were observed with a frequency of one every 23 generations, a rate far below what would be useful to drive anti-pathogen transgenes into wild mosquito populations. We discuss the possibility of optimizing this system and the impetus to do so.
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Affiliation(s)
- Vanessa M Macias
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Alyssa J Jimenez
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Bianca Burini-Kojin
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - David Pledger
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Nijole Jasinskiene
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Celine Hien Phong
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Karen Chu
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Aniko Fazekas
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Kelcie Martin
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Osvaldo Marinotti
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States.
| | - Anthony A James
- Department of Molecular Biology and Biochemistry, University of California, Irvine, 3205 McGaugh Hall, Irvine, CA 92697-3900, United States; Department of Microbiology and Molecular Genetics, B240 Med Sci Bldg., School of Medicine, University of California, Irvine, CA 92697-4025, United States.
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13
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Adelman ZN, Tu Z. Control of Mosquito-Borne Infectious Diseases: Sex and Gene Drive. Trends Parasitol 2016; 32:219-229. [PMID: 26897660 DOI: 10.1016/j.pt.2015.12.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 12/01/2015] [Accepted: 12/04/2015] [Indexed: 01/23/2023]
Abstract
Sterile male releases have successfully reduced local populations of the dengue vector, Aedes aegypti, but challenges remain in scale and in separating sexes before release. The recent discovery of the first mosquito male determining factor (M factor) will facilitate our understanding of the genetic programs that initiate sexual development in mosquitoes. Manipulation of the M factor and possible intermediary factors may result in female-to-male conversion or female killing, enabling efficient sex separation and effective reduction of target mosquito populations. Given recent breakthroughs in the development of CRISPR-Cas9 reagents as a source of gene drive, more advanced technologies at driving maleness, the ultimate disease refractory phenotype, become possible and may represent efficient and self-limiting methods to control mosquito populations.
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Affiliation(s)
- Zach N Adelman
- Department of Entomology, Virginia Tech, Blacksburg, VA, USA; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA.
| | - Zhijian Tu
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA; Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA.
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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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Haghighat-Khah RE, Scaife S, Martins S, St John O, Matzen KJ, Morrison N, Alphey L. Site-specific cassette exchange systems in the Aedes aegypti mosquito and the Plutella xylostella moth. PLoS One 2015; 10:e0121097. [PMID: 25830287 PMCID: PMC4382291 DOI: 10.1371/journal.pone.0121097] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 02/09/2015] [Indexed: 12/02/2022] Open
Abstract
Genetically engineered insects are being evaluated as potential tools to decrease the economic and public health burden of mosquitoes and agricultural pest insects. Here we describe a new tool for the reliable and targeted genome manipulation of pest insects for research and field release using recombinase mediated cassette exchange (RMCE) mechanisms. We successfully demonstrated the established ΦC31-RMCE method in the yellow fever mosquito, Aedes aegypti, which is the first report of RMCE in mosquitoes. A new variant of this RMCE system, called iRMCE, combines the ΦC31-att integration system and Cre or FLP-mediated excision to remove extraneous sequences introduced as part of the site-specific integration process. Complete iRMCE was achieved in two important insect pests, Aedes aegypti and the diamondback moth, Plutella xylostella, demonstrating the transferability of the system across a wide phylogenetic range of insect pests.
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Affiliation(s)
- Roya Elaine Haghighat-Khah
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Oxitec Limited, Oxford, United Kingdom
| | | | - Sara Martins
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Oxitec Limited, Oxford, United Kingdom
| | - Oliver St John
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Oxitec Limited, Oxford, United Kingdom
| | | | | | - Luke Alphey
- Department of Zoology, University of Oxford, Oxford, United Kingdom
- Oxitec Limited, Oxford, United Kingdom
- * E-mail: (LA); (KJM)
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16
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An efficient strategy for producing a stable, replaceable, highly efficient transgene expression system in silkworm, Bombyx mori. Sci Rep 2015; 5:8802. [PMID: 25739894 DOI: 10.1038/srep08802] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 02/04/2015] [Indexed: 12/16/2022] Open
Abstract
We developed an efficient strategy that combines a method for the post-integration elimination of all transposon sequences, a site-specific recombination system, and an optimized fibroin H-chain expression system to produce a stable, replaceable, highly efficient transgene expression system in the silkworm (Bombyx mori) that overcomes the disadvantages of random insertion and post-integration instability of transposons. Here, we generated four different transgenic silkworm strains, and of one the transgenic strains, designated TS1-RgG2, with up to 16% (w/w) of the target protein in the cocoons, was selected. The subsequent elimination of all the transposon sequences from TS1-RgG2 was completed by the heat-shock-induced expression of the transposase in vivo. The resulting transgenic silkworm strain was designated TS3-g2 and contained only the attP-flanked optimized fibroin H-chain expression cassette in its genome. A phiC31/att-system-based recombinase-mediated cassette exchange (RMCE) method could be used to integrate other genes of interest into the same genome locus between the attP sites in TS3-g2. Controlling for position effects with phiC31-mediated RMCE will also allow the optimization of exogenous protein expression and fine gene function analyses in the silkworm. The strategy developed here is also applicable to other lepidopteran insects, to improve the ecological safety of transgenic strains in biocontrol programs.
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17
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Lok J. piggyBac: A vehicle for integrative DNA transformation of parasitic nematodes. Mob Genet Elements 2014; 3:e24417. [PMID: 23914309 PMCID: PMC3681738 DOI: 10.4161/mge.24417] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/11/2013] [Accepted: 03/22/2013] [Indexed: 12/18/2022] Open
Abstract
In addition to their natural role in eukaryotic genome evolution, transposons can be powerful tools for functional genomics in diverse taxa. The piggyBac transposon has been applied as such in eukaryotic parasites, both protozoa and helminths, and in several important vector mosquitoes. piggyBac is advantageous for functional genomics because of its ability to transduce a wide range of taxa, its capacity to integrate large DNA ‘cargoes’ relative to other mobile genetic elements, its propensity to target transcriptional units and its ability to re-mobilize without leaving a pattern of non-excised sequences or ‘footprint’ in the genome. We recently demonstrated that piggyBac can integrate transgenes into the genome of the parasitic nematode Strongyloides ratti, an important model for parasitic nematode biology and a close relative of the significant human pathogen S. stercoralis. Unlike transgenes encoded in conventional plasmid vectors, which we assume are assembled into multi-copy episomal arrays as they are in Caenorhabditis elegans, transgenes integrated via piggyBac are not only stably inherited in S. ratti, they are also continuously expressed. This has allowed derivation of the first stable transgene expressing lines in any parasitic nematode, a significant advance in the development of functional genomic tools for these important pathogens.
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Affiliation(s)
- James Lok
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA USA
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18
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Jiang X, Peery A, Hall AB, Sharma A, Chen XG, Waterhouse RM, Komissarov A, Riehle MM, Shouche Y, Sharakhova MV, Lawson D, Pakpour N, Arensburger P, Davidson VLM, Eiglmeier K, Emrich S, George P, Kennedy RC, Mane SP, Maslen G, Oringanje C, Qi Y, Settlage R, Tojo M, Tubio JMC, Unger MF, Wang B, Vernick KD, Ribeiro JMC, James AA, Michel K, Riehle MA, Luckhart S, Sharakhov IV, Tu Z. Genome analysis of a major urban malaria vector mosquito, Anopheles stephensi. Genome Biol 2014; 15:459. [PMID: 25244985 PMCID: PMC4195908 DOI: 10.1186/s13059-014-0459-2] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 09/03/2014] [Indexed: 12/24/2022] Open
Abstract
Background Anopheles stephensi is the key vector of malaria throughout the Indian subcontinent and Middle East and an emerging model for molecular and genetic studies of mosquito-parasite interactions. The type form of the species is responsible for the majority of urban malaria transmission across its range. Results Here, we report the genome sequence and annotation of the Indian strain of the type form of An. stephensi. The 221 Mb genome assembly represents more than 92% of the entire genome and was produced using a combination of 454, Illumina, and PacBio sequencing. Physical mapping assigned 62% of the genome onto chromosomes, enabling chromosome-based analysis. Comparisons between An. stephensi and An. gambiae reveal that the rate of gene order reshuffling on the X chromosome was three times higher than that on the autosomes. An. stephensi has more heterochromatin in pericentric regions but less repetitive DNA in chromosome arms than An. gambiae. We also identify a number of Y-chromosome contigs and BACs. Interspersed repeats constitute 7.1% of the assembled genome while LTR retrotransposons alone comprise more than 49% of the Y contigs. RNA-seq analyses provide new insights into mosquito innate immunity, development, and sexual dimorphism. Conclusions The genome analysis described in this manuscript provides a resource and platform for fundamental and translational research into a major urban malaria vector. Chromosome-based investigations provide unique perspectives on Anopheles chromosome evolution. RNA-seq analysis and studies of immunity genes offer new insights into mosquito biology and mosquito-parasite interactions. Electronic supplementary material The online version of this article (doi:10.1186/s13059-014-0459-2) contains supplementary material, which is available to authorized users.
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19
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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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20
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Identification of a novel strong and ubiquitous promoter/enhancer in the silkworm Bombyx mori. G3-GENES GENOMES GENETICS 2014; 4:1347-57. [PMID: 24875626 PMCID: PMC4455783 DOI: 10.1534/g3.114.011643] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Transgenic techniques offer a valuable tool for determining gene functions. Although various promoters are available for use in gene overexpression, gene knockdown, and identification of transgenic individuals, there is nevertheless a lack of versatile promoters for such studies, and this dearth acts as a bottleneck, especially with regard to nonmodel organisms. Here, we succeeded in identifying a novel strong and ubiquitous promoter/enhancer in the silkworm. We identified a unique silkworm strain whose reporter gene showed strong and ubiquitous expression during the establishment of enhancer trap strains. In this strain, the transposon was inserted into the 5'UTR of hsp90, a housekeeping gene that is abundantly expressed in a range of tissues. To determine whether the promoter/enhancer of hsp90 could be used to induce strong gene expression, a 2.9-kb upstream genomic fragment of hsp90 was isolated (hsp90(P2.9k)), and its transcriptional activation activity was examined. Strikingly, hsp90(P2.9k) induced strong gene expression in silkworm cell cultures and also strongly induced gene expression in various tissues and developmental stages of the silkworm. hsp90(P2.9k) also exhibited significant promoter/enhancer activity in Sf9, a cell culture from the armyworm, suggesting that this fragment might possibly be used as a gene expression tool in other Lepidoptera. We further found that 2.0 kb of hsp90(P2.9k) is sufficient for the induction of strong gene expression. We believe that this element will be of value for a range of studies such as targeted gene overexpression, gene knockdown and marker gene expression, not only in the silkworm but also in other insect species.
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21
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Hong JB, Chou FJ, Ku AT, Fan HH, Lee TL, Huang YH, Yang TL, Su IC, Yu IS, Lin SW, Chien CL, Ho HN, Chen YT. A nucleolus-predominant piggyBac transposase, NP-mPB, mediates elevated transposition efficiency in mammalian cells. PLoS One 2014; 9:e89396. [PMID: 24586748 PMCID: PMC3933532 DOI: 10.1371/journal.pone.0089396] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 01/20/2014] [Indexed: 11/25/2022] Open
Abstract
PiggyBac is a prevalent transposon system used to deliver transgenes and functionally explore the mammalian untouched genomic territory. The important features of piggyBac transposon are the relatively low insertion site preference and the ability of seamless removal from genome, which allow its potential uses in functional genomics and regenerative medicine. Efforts to increase its transposition efficiency in mammals were made through engineering the corresponding transposase (PBase) codon usage to enhance its expression level and through screening for mutant PBase variants with increased enzyme activity. To improve the safety for its potential use in regenerative medicine applications, site-specific transposition was achieved by using engineered zinc finger- and Gal4-fused PBases. An excision-prone PBase variant has also been successfully developed. Here we describe the construction of a nucleolus-predominant PBase, NP-mPB, by adding a nucleolus-predominant (NP) signal peptide from HIV-1 TAT protein to a mammalian codon-optimized PBase (mPB). Although there is a predominant fraction of the NP-mPB-tGFP fusion proteins concentrated in the nucleoli, an insertion site preference toward nucleolar organizer regions is not detected. Instead a 3–4 fold increase in piggyBac transposition efficiency is reproducibly observed in mouse and human cells.
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Affiliation(s)
- Jin-Bon Hong
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Dermatology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Fu-Ju Chou
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Amy T. Ku
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hsiang-Hsuan Fan
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Tung-Lung Lee
- Department of Dermatology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Yung-Hsin Huang
- Department of Dermatology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - Tsung-Lin Yang
- Department of Otolaryngology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
| | - I-Chang Su
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - I-Shing Yu
- Transgenic Mouse Model Core Facility of the National Research Program for Genomic Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
- Laboratory Animal Center, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shu-Wha Lin
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Laboratory Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Chung-Liang Chien
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
- Stem Cell Core Laboratory, National Taiwan University Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hong-Nerng Ho
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
- Stem Cell Core Laboratory, National Taiwan University Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan
| | - You-Tzung Chen
- Graduate Institute of Medical Genomics and Proteomics, National Taiwan University College of Medicine, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
- Stem Cell Core Laboratory, National Taiwan University Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Program, National Taiwan University, Taipei, Taiwan
- * E-mail:
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Ma S, Wang X, Fei J, Liu Y, Duan J, Wang F, Xu H, Zhao P, Xia Q. Genetic marking of sex using a W chromosome-linked transgene. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:1079-1086. [PMID: 24036279 DOI: 10.1016/j.ibmb.2013.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 08/29/2013] [Accepted: 08/29/2013] [Indexed: 06/02/2023]
Abstract
Many species belonging to the order Lepidoptera are major pests in agriculture and arboriculture. The sterile insect technique (SIT) is an eco-friendly and highly efficient genetically targeted pest management approach. In many cases, it is preferable to release only sterile males in an SIT program, and efficient sexing strategies are crucial to the successful large-scale implementation of SIT. In the present study, we established 160 transgenic silkworm (Bombyx mori) lines to test the possibility of genetic sexing using a W chromosome-linked transgene, which is thought to be the best sexing strategy for lepidopteran species. One transgenic line with a female-specific expression pattern of reporter gene was obtained. The expression level of the W-linked transgene was comparable with autosomal insertions and was stable for 17 continuous generations. Molecular characterization showed this line contained a single copy of the reporter gene on the W chromosome, and the integration site was TTAG in contig W-BAC-522N19-C9. The feasibility of using a W chromosome-linked transgene demonstrated here and the possible improvements discussed will provide valuable information for other lepidopteran pests. The novel W chromosome-linked transgenic line established in this study will serve as an important resource for fundamental research with the silkworm B. mori.
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Affiliation(s)
- Sanyuan Ma
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China
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Smith RC, Kizito C, Rasgon JL, Jacobs-Lorena M. Transgenic mosquitoes expressing a phospholipase A(2) gene have a fitness advantage when fed Plasmodium falciparum-infected blood. PLoS One 2013; 8:e76097. [PMID: 24098427 PMCID: PMC3788000 DOI: 10.1371/journal.pone.0076097] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 08/20/2013] [Indexed: 11/18/2022] Open
Abstract
Background Genetically modified mosquitoes have been proposed as an alternative strategy to reduce the heavy burden of malaria. In recent years, several proof-of-principle experiments have been performed that validate the idea that mosquitoes can be genetically modified to become refractory to malaria parasite development. Results We have created two transgenic lines of Anophelesstephensi, a natural vector of Plasmodium falciparum, which constitutively secrete a catalytically inactive phospholipase A2 (mPLA2) into the midgut lumen to interfere with Plasmodium ookinete invasion. Our experiments show that both transgenic lines expressing mPLA2 significantly impair the development of rodent malaria parasites, but only one line impairs the development of human malaria parasites. In addition, when fed on malaria-infected blood, mosquitoes from both transgenic lines are more fecund than non-transgenic mosquitoes. Consistent with these observations, cage experiments with mixed populations of transgenic and non-transgenic mosquitoes show that the percentage of transgenic mosquitoes increases when maintained on Plasmodium-infected blood. Conclusions Our results suggest that the expression of an anti-Plasmodium effector gene gives transgenic mosquitoes a fitness advantage when fed malaria-infected blood. These findings have important implications for future applications of transgenic mosquito technology in malaria control.
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Affiliation(s)
- Ryan C. Smith
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Christopher Kizito
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Jason L. Rasgon
- Department of Entomology, Center for Infectious Disease Dynamics and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Marcelo Jacobs-Lorena
- Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
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Palavesam A, Esnault C, O’Brochta DA. Post-integration silencing of piggyBac transposable elements in Aedes aegypti. PLoS One 2013; 8:e68454. [PMID: 23861905 PMCID: PMC3701635 DOI: 10.1371/journal.pone.0068454] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/30/2013] [Indexed: 12/04/2022] Open
Abstract
The piggyBac transposon, originating in the genome of the Lepidoptera Trichoplusia ni, has a broad host range, making it useful for the development of a number of transposon-based functional genomic technologies including gene vectors, enhancer-, gene- and protein-traps. While capable of being used as a vector for the creation of transgenic insects and insect cell lines, piggyBac has very limited mobility once integrated into the genome of the yellow fever mosquito, Aedes aegypti. A transgenic Aedes aegypti cell line (AagPB8) was created containing three integrated piggyBac elements and the remobilization potential of the elements was tested. The integrated piggyBac elements in AagPB8 were transpositionally silent in the presence of functional transposase, which was shown to be capable of catalyzing the movement of plasmid-borne piggyBac elements in the same cells. The structural integrity of one of the integrated elements along with the quality of element-flanking DNA, which is known to influence transposition rates, were tested in D. melanogaster. The element was found to be structurally intact, capable of transposition and excision in the soma and germ-line of Drosophila melanogaster, and in a DNA sequence context highly conducive to element movement in Drosophila melanogaster. These data show that transpositional silencing of integrated piggyBac elements in the genome of Aedes aegypti appears to be a function of higher scale genome organization or perhaps epigenetic factors, and not due to structural defects or suboptimal integration sites.
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Affiliation(s)
- Azhahianambi Palavesam
- Department of Entomology, The Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, Maryland, United States of America
| | - Caroline Esnault
- Department of Entomology, The Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, Maryland, United States of America
| | - David A. O’Brochta
- Department of Entomology, The Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, Maryland, United States of America
- Institute for Bioscience and Biotechnology Research, Rockville, Maryland, United States of America
- * E-mail:
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Schetelig MF, Handler AM. Germline transformation of the spotted wing drosophilid, Drosophila suzukii, with a piggyBac transposon vector. Genetica 2013; 141:189-93. [DOI: 10.1007/s10709-013-9717-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 03/27/2013] [Indexed: 01/31/2023]
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Meredith JM, Underhill A, McArthur CC, Eggleston P. Next-generation site-directed transgenesis in the malaria vector mosquito Anopheles gambiae: self-docking strains expressing germline-specific phiC31 integrase. PLoS One 2013; 8:e59264. [PMID: 23516619 PMCID: PMC3596282 DOI: 10.1371/journal.pone.0059264] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 02/13/2013] [Indexed: 01/27/2023] Open
Abstract
Diseases transmitted by mosquitoes have a devastating impact on global health and the situation is complicated due to difficulties with both existing control measures and the impact of climate change. Genetically modified mosquitoes that are refractory to disease transmission are seen as having great potential in the delivery of novel control strategies. The Streptomyces phage phiC31 integrase system has been successfully adapted for site-directed transgene integration in a range of insects, thus overcoming many limitations due to size constraints and random integration associated with transposon-mediated transformation. Using this technology, we previously published the first site-directed transformation of Anopheles gambiae, the principal vector of human malaria. Mosquitoes were initially engineered to incorporate the phiC31 docking site at a defined genomic location. A second phase of genetic modification then achieved site-directed integration of an anti-malarial effector gene. In the current publication we report improved efficiency and utility of the phiC31 integrase system following the generation of Anopheles gambiae self-docking strains. Four independent strains, with docking sites at known locations on three different chromosome arms, were engineered to express integrase under control of the regulatory regions of the nanos gene from Anopheles gambiae. The resulting protein accumulates in the posterior oocyte to provide integrase activity at the site of germline development. Two self-docking strains, exhibiting significantly different levels of integrase expression, were assessed for site-directed transgene integration and found to demonstrate greatly improved survival and efficiency of transformation. In the fight against malaria, it is imperative to establish a broad repertoire of both anti-malarial effector genes and tissue-specific promoters to regulate their expression, enabling those offering maximum effect with minimum fitness cost to be identified. The improved technology we describe here will facilitate comparative studies of effector transgenes, allowing informed choices to be made that potentially lead to transmission blockade.
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Affiliation(s)
- Janet M. Meredith
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Ann Underhill
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Clare C. McArthur
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Paul Eggleston
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
- * E-mail:
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Gal4-based enhancer-trapping in the malaria mosquito Anopheles stephensi. G3-GENES GENOMES GENETICS 2012; 2:1305-15. [PMID: 23173082 PMCID: PMC3484661 DOI: 10.1534/g3.112.003582] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 08/22/2012] [Indexed: 12/16/2022]
Abstract
Transposon-based forward and reverse genetic technologies will contribute greatly to ongoing efforts to study mosquito functional genomics. A piggyBac transposon-based enhancer-trap system was developed that functions efficiently in the human malaria vector, Anopheles stephensi. The system consists of six transgenic lines of Anopheles stephensi, each with a single piggyBac-Gal4 element in a unique genomic location; six lines with a single piggyBac-UAStdTomato element; and two lines, each with a single Minos element containing the piggyBac-transposase gene under the regulatory control of the hsp70 promoter from Drosophila melanogaster. Enhancer detection depended upon the efficient remobilization of piggyBac-Gal4 transposons, which contain the yeast transcription factor gene Gal4 under the regulatory control of a basal promoter. Gal4 expression was detected through the expression of the fluorescent protein gene tdTomato under the regulatory control of a promoter with Gal4-binding UAS elements. From five genetic screens for larval- and adult-specific enhancers, 314 progeny were recovered from 24,250 total progeny (1.3%) with unique patterns of tdTomato expression arising from the influence of an enhancer. The frequency of piggyBac remobilization and enhancer detection was 2.5- to 3-fold higher in female germ lines compared with male germ lines. A small collection of enhancer-trap lines are described in which Gal4 expression occurred in adult female salivary glands, midgut, and fat body, either singly or in combination. These three tissues play critical roles during the infection of Anopheles stephensi by malaria-causing Plasmodium parasites. This system and the lines generated using it will be valuable resources to ongoing mosquito functional genomics efforts.
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Shao H, Li X, Nolan TJ, Massey HC, Pearce EJ, Lok JB. Transposon-mediated chromosomal integration of transgenes in the parasitic nematode Strongyloides ratti and establishment of stable transgenic lines. PLoS Pathog 2012; 8:e1002871. [PMID: 22912584 PMCID: PMC3415448 DOI: 10.1371/journal.ppat.1002871] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 07/06/2012] [Indexed: 11/28/2022] Open
Abstract
Genetic transformation is a potential tool for analyzing gene function and thereby identifying new drug and vaccine targets in parasitic nematodes, which adversely affect more than one billion people. We have previously developed a robust system for transgenesis in Strongyloides spp. using gonadal microinjection for gene transfer. In this system, transgenes are expressed in promoter-regulated fashion in the F1 but are silenced in subsequent generations, presumably because of their location in repetitive episomal arrays. To counteract this silencing, we explored transposon-mediated chromosomal integration of transgenes in S. ratti. To this end, we constructed a donor vector encoding green fluorescent protein (GFP) under the control of the Ss-act-2 promoter with flanking inverted tandem repeats specific for the piggyBac transposon. In three experiments, free-living Strongyloides ratti females were transformed with this donor vector and a helper plasmid encoding the piggyBac transposase. A mean of 7.9% of F1 larvae were GFP-positive. We inoculated rats with GFP-positive F1 infective larvae, and 0.5% of 6014 F2 individuals resulting from this host passage were GFP-positive. We cultured GFP-positive F2 individuals to produce GFP-positive F3 L3i for additional rounds of host and culture passage. Mean GFP expression frequencies in subsequent generations were 15.6% in the F3, 99.0% in the F4, 82.4% in the F5 and 98.7% in the F6. The resulting transgenic lines now have virtually uniform GFP expression among all progeny after at least 10 generations of passage. Chromosomal integration of the reporter transgenes was confirmed by Southern blotting and splinkerette PCR, which revealed the transgene flanked by S. ratti genomic sequences corresponding to five discrete integration sites. BLAST searches of flanking sequences against the S. ratti genome revealed integrations in five contigs. This result provides the basis for two powerful functional genomic tools in S. ratti: heritable transgenesis and insertional mutagenesis.
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Affiliation(s)
- Hongguang Shao
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Xinshe Li
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Thomas J. Nolan
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Holman C. Massey
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Edward J. Pearce
- Department of Pathology and Immunology, School of Medicine, Washington University, St. Louis, Missouri, United States of America
| | - James B. Lok
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Long DP, Zhao AC, Chen XJ, Zhang Y, Lu WJ, Guo Q, Handler AM, Xiang ZH. FLP recombinase-mediated site-specific recombination in silkworm, Bombyx mori. PLoS One 2012; 7:e40150. [PMID: 22768245 PMCID: PMC3387143 DOI: 10.1371/journal.pone.0040150] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/01/2012] [Indexed: 11/18/2022] Open
Abstract
A comprehensive understanding of gene function and the production of site-specific genetically modified mutants are two major goals of genetic engineering in the post-genomic era. Although site-specific recombination systems have been powerful tools for genome manipulation of many organisms, they have not yet been established for use in the manipulation of the silkworm Bombyx mori genome. In this study, we achieved site-specific excision of a target gene at predefined chromosomal sites in the silkworm using a FLP/FRT site-specific recombination system. We first constructed two stable transgenic target silkworm strains that both contain a single copy of the transgene construct comprising a target gene expression cassette flanked by FRT sites. Using pre-blastoderm microinjection of a FLP recombinase helper expression vector, 32 G3 site-specific recombinant transgenic individuals were isolated from five of 143 broods. The average frequency of FLP recombinase-mediated site-specific excision in the two target strains genome was approximately 3.5%. This study shows that it is feasible to achieve site-specific recombination in silkworms using the FLP/FRT system. We conclude that the FLP/FRT system is a useful tool for genome manipulation in the silkworm. Furthermore, this is the first reported use of the FLP/FRT system for the genetic manipulation of a lepidopteran genome and thus provides a useful reference for the establishment of genome manipulation technologies in other lepidopteran species.
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Affiliation(s)
- Ding-Pei Long
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Ai-Chun Zhao
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
- * E-mail:
| | - Xue-Jiao Chen
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Yang Zhang
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Wei-Jian Lu
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Qing Guo
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
| | - Alfred M. Handler
- USDA/ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, United States of America
| | - Zhong-Huai Xiang
- State Key Laboratory of Silkworm Genome Biology, Institute of Sericulture and Systems Biology, Southwest University, Chongqing, China
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Yang G, Wong A, Rooke R. ATon, abundant novel nonautonomous mobile genetic elements in yellow fever mosquito (Aedes aegypti). BMC Genomics 2012; 13:283. [PMID: 22738224 PMCID: PMC3422177 DOI: 10.1186/1471-2164-13-283] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Accepted: 06/27/2012] [Indexed: 12/16/2022] Open
Abstract
Background Mosquitoes are important pathogen vectors affecting human and other animals. Studies on genetic control of mosquito mediated disease transmission gained traction recently due to mosquito transgenesis technology. Active transposons are considered valuable tools to propagate pathogen resistance transgenes among mosquitoes, rendering the whole population recalcitrant to diseases. A major hurdle in this approach is the inefficient remobilization activity after the integration of heterologous transposon vectors bearing transgenes into chromosomes. Therefore, endogenous active transposons in mosquito genomes are highly desirable. Results Starting with the transposable element database of the yellow fever mosquito Aedes aegypti genome, detailed analyses of the members of each TE family were performed to identify sequences with multiple identical copies, an indicator of their latest or current transposition activity. Among a dozen of potentially active TE families, two DNA elements (TF000728 and TF000742 in TEfam) are short and nonautonomous. Close inspection of the elements revealed that these two families were previously mis-categorized and, unlike other known TEs, insert specifically at dinucleotide “AT”. These two families were therefore designated as ATon-I and ATon-II. ATon-I has a total copy number of 294, among which three elements have more than 10 identical copies (146, 61 and 17). ATon-II has a total copy number of 317, among which three elements have more than 10 identical copies (84, 15 and 12). Genome wide searches revealed additional 24 ATon families in A. aegypti genome with nearly 6500 copies in total. Transposon display analysis of ATon-1 family using different A. aegypti strains suggests that the elements are similarly abundant in the tested mosquito strains. Conclusion ATons are novel mobile genetic elements bearing terminal inverted repeats and insert specifically at dinucleotide “AT”. Five ATon families contain elements existing at more than 10 identical copies, suggesting very recent or current transposition activity. A total of 24 new TE families with nearly 6000 copies were identified in this study.
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Affiliation(s)
- Guojun Yang
- Department of Biology, University of Toronto Mississauga, SB3058, Mississauga, ON, L5L 1 C6, Canada.
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