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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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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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Champer J, Buchman A, Akbari OS. Cheating evolution: engineering gene drives to manipulate the fate of wild populations. Nat Rev Genet 2016; 17:146-59. [PMID: 26875679 DOI: 10.1038/nrg.2015.34] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Engineered gene drives - the process of stimulating the biased inheritance of specific genes - have the potential to enable the spread of desirable genes throughout wild populations or to suppress harmful species, and may be particularly useful for the control of vector-borne diseases such as malaria. Although several types of selfish genetic elements exist in nature, few have been successfully engineered in the laboratory thus far. With the discovery of RNA-guided CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated 9) nucleases, which can be utilized to create, streamline and improve synthetic gene drives, this is rapidly changing. Here, we discuss the different types of engineered gene drives and their potential applications, as well as current policies regarding the safety and regulation of gene drives for the manipulation of wild populations.
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Affiliation(s)
- Jackson Champer
- Department of Entomology, University of California, Riverside, Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
| | - Anna Buchman
- Department of Entomology, University of California, Riverside, Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
| | - Omar S Akbari
- Department of Entomology, University of California, Riverside, Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA
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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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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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Ma X, Zhao Y, Sun W, Shimabukuro K, Miao L. Transformation: how do nematode sperm become activated and crawl? Protein Cell 2012; 3:755-61. [PMID: 22903434 PMCID: PMC4875351 DOI: 10.1007/s13238-012-2936-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 05/09/2012] [Indexed: 01/16/2023] Open
Abstract
Nematode sperm undergo a drastic physiological change during spermiogenesis (sperm activation). Unlike mammalian flagellated sperm, nematode sperm are amoeboid cells and their motility is driven by the dynamics of a cytoskeleton composed of major sperm protein (MSP) rather than actin found in other crawling cells. This review focuses on sperm from Caenorhabditis elegans and Ascaris suum to address the roles of external and internal factors that trigger sperm activation and power sperm motility. Nematode sperm can be activated in vitro by several factors, including Pronase and ionophores, and in vivo through the TRY-5 and SPE-8 pathways. Moreover, protease and protease inhibitors are crucial regulators of sperm maturation. MSP-based sperm motility involves a coupled process of protrusion and retraction, both of which have been reconstituted in vitro. Sperm motility is mediated by phosphorylation signals, as illustrated by identification of several key components (MPOP, MFPs and MPAK) in Ascaris and the characterization of GSP-3/4 in C. elegans.
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Affiliation(s)
- Xuan Ma
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Yanmei Zhao
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Wei Sun
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
- Graduate University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Katsuya Shimabukuro
- Department of Chemical and Biological Engineering, Ube National College of Technology, Ube, Yamaguchi, 755-8555 Japan
| | - Long Miao
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
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Alcázar R, Pecinka A, Aarts MGM, Fransz PF, Koornneef M. Signals of speciation within Arabidopsis thaliana in comparison with its relatives. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:205-211. [PMID: 22265228 DOI: 10.1016/j.pbi.2012.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 12/06/2011] [Accepted: 01/03/2012] [Indexed: 05/31/2023]
Abstract
The species within the now well-defined Arabidopsis genus provide biological materials suitable to investigate speciation and the development of reproductive isolation barriers between related species. Even within the model species A. thaliana, genetic differentiation between populations due to environmental adaptation or demographic history can lead to cases where hybrids between accessions are non-viable. Experimental evidence supports the importance of genome duplications and genetic epistatic interactions in the occurrence of reproductive isolation. Other examples of adaptation to specific environments can be found in Arabidopsis relatives where hybridization and chromosome doubling lead to new amphidiploid species. Molecular signals of speciation found in the Arabidopsis genus should provide a better understanding of speciation processes in plants from a genetic, molecular and evolutionary perspective.
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Affiliation(s)
- Rubén Alcázar
- Department of Plant Breeding and Genetics, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Cologne, Germany
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Bire S, Rouleux-Bonnin F. Transposable elements as tools for reshaping the genome: it is a huge world after all! Methods Mol Biol 2012; 859:1-28. [PMID: 22367863 DOI: 10.1007/978-1-61779-603-6_1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Transposable elements (TEs) are discrete pieces of DNA that can move from one site to another within genomes and sometime between genomes. They are found in all major branches of life. Because of their wide distribution and considerable diversity, they are a considerable source of genomic variation and as such, they constitute powerful drivers of genome evolution. Moreover, it is becoming clear that the epigenetic regulation of certain genes is derived from defense mechanisms against the activity of ancestral transposable elements. TEs now tend to be viewed as natural molecular tools that can reshape the genome, which challenges the idea that TEs are natural tools used to answer biological questions. In the first part of this chapter, we review the classification and distribution of TEs, and look at how they have contributed to the structural and transcriptional reshaping of genomes. In the second part, we describe methodological innovations that have modified their contribution as molecular tools.
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Affiliation(s)
- Solenne Bire
- GICC, UMR CNRS 6239, Université François Rabelais, UFR des Sciences et Technques, Tours, France
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Abstract
The ability to manipulate the genomes of many insects has become a practical reality over the past 15 years. This has been led by the identification of several useful transposon vector systems that have allowed the identification and development of generalized, species-specific, and tissue-specific promoter systems for controlled expression of gene products upon introduction into insect genomes. Armed with these capabilities, researchers have made significant strides in both fundamental and applied transgenics in key model systems such as Bombyx mori, Tribolium casteneum, Aedes aegypti, and Anopheles stephensi. Limitations of transposon systems were identified, and alternative tools were developed, thus significantly increasing the potential for applied transgenics for control of both agricultural and medical insect pests. The next 10 years promise to be an exciting time of transitioning from the laboratory to the field, from basic research to applied control, during which the full potential of gene manipulation in insect systems will ultimately be realized.
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Affiliation(s)
- Malcolm J Fraser
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556-0369, USA.
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Arensburger P, Hice RH, Wright JA, Craig NL, Atkinson PW. The mosquito Aedes aegypti has a large genome size and high transposable element load but contains a low proportion of transposon-specific piRNAs. BMC Genomics 2011; 12:606. [PMID: 22171608 PMCID: PMC3259105 DOI: 10.1186/1471-2164-12-606] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 12/15/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The piRNA pathway has been shown in model organisms to be involved in silencing of transposons thereby providing genome stability. In D. melanogaster the majority of piRNAs map to these sequences. The medically important mosquito species Aedes aegypti has a large genome size, a high transposon load which includes Miniature Inverted repeat Transposable Elements (MITES) and an expansion of the piRNA biogenesis genes. Studies of transgenic lines of Ae. aegypti have indicated that introduced transposons are poorly remobilized and we sought to explore the basis of this. We wished to analyze the piRNA profile of Ae. aegypti and thereby determine if it is responsible for transposon silencing in this mosquito. RESULTS Estimated piRNA sequence diversity was comparable between Ae. aegypti and D. melanogaster, but surprisingly only 19% of mosquito piRNAs mapped to transposons compared to 51% for D. melanogaster. Ae. aegypti piRNA clusters made up a larger percentage of the total genome than those of D. melanogaster but did not contain significantly higher percentages of transposon derived sequences than other regions of the genome. Ae. aegypti contains a number of protein coding genes that may be sources of piRNA biogenesis with two, traffic jam and maelstrom, implicated in this process in model organisms. Several genes of viral origin were also targeted by piRNAs. Examination of six mosquito libraries that had previously been transformed with transposon derived sequence revealed that new piRNA sequences had been generated to the transformed sequences, suggesting that they may have stimulated a transposon inactivation mechanism. CONCLUSIONS Ae. aegypti has a large piRNA complement that maps to transposons but primarily gene sequences, including many viral-derived sequences. This, together the more uniform distribution of piRNA clusters throughout its genome, suggest that some aspects of the piRNA system differ between Ae. aegypti and D. melanogaster.
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Affiliation(s)
- Peter Arensburger
- Center for Disease Vector Research, Institute for Integrative Genome Biology, and Department of Entomology, University of California, Riverside, CA 92521, USA
| | - Robert H Hice
- Center for Disease Vector Research, Institute for Integrative Genome Biology, and Department of Entomology, University of California, Riverside, CA 92521, USA
| | - Jennifer A Wright
- Center for Disease Vector Research, Institute for Integrative Genome Biology, and Department of Entomology, University of California, Riverside, CA 92521, USA
| | - Nancy L Craig
- Department of Molecular Biology & Genetics and Howard Hughes Medical Institute, Johns Hopkins School of Medicine, Baltimore, MD 20742,USA
| | - Peter W Atkinson
- Center for Disease Vector Research, Institute for Integrative Genome Biology, and Department of Entomology, University of California, Riverside, CA 92521, USA
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