1
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Kim J, Harris KD, Kim IK, Shemesh S, Messer PW, Greenbaum G. Incorporating ecology into gene drive modelling. Ecol Lett 2023; 26 Suppl 1:S62-S80. [PMID: 37840022 DOI: 10.1111/ele.14194] [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: 10/19/2022] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 10/17/2023]
Abstract
Gene drive technology, in which fast-spreading engineered drive alleles are introduced into wild populations, represents a promising new tool in the fight against vector-borne diseases, agricultural pests and invasive species. Due to the risks involved, gene drives have so far only been tested in laboratory settings while their population-level behaviour is mainly studied using mathematical and computational models. The spread of a gene drive is a rapid evolutionary process that occurs over timescales similar to many ecological processes. This can potentially generate strong eco-evolutionary feedback that could profoundly affect the dynamics and outcome of a gene drive release. We, therefore, argue for the importance of incorporating ecological features into gene drive models. We describe the key ecological features that could affect gene drive behaviour, such as population structure, life-history, environmental variation and mode of selection. We review previous gene drive modelling efforts and identify areas where further research is needed. As gene drive technology approaches the level of field experimentation, it is crucial to evaluate gene drive dynamics, potential outcomes, and risks realistically by including ecological processes.
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Affiliation(s)
- Jaehee Kim
- Department of Computational Biology, Cornell University, Ithaca, New York, USA
| | - Keith D Harris
- Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Isabel K Kim
- Department of Computational Biology, Cornell University, Ithaca, New York, USA
| | - Shahar Shemesh
- Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Philipp W Messer
- Department of Computational Biology, Cornell University, Ithaca, New York, USA
| | - Gili Greenbaum
- Department of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem, Jerusalem, Israel
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2
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Hay BA, Oberhofer G, Guo M. Engineering the Composition and Fate of Wild Populations with Gene Drive. ANNUAL REVIEW OF ENTOMOLOGY 2021; 66:407-434. [PMID: 33035437 DOI: 10.1146/annurev-ento-020117-043154] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Insects play important roles as predators, prey, pollinators, recyclers, hosts, parasitoids, and sources of economically important products. They can also destroy crops; wound animals; and serve as vectors for plant, animal, and human diseases. Gene drive-a process by which genes, gene complexes, or chromosomes encoding specific traits are made to spread through wild populations, even if these traits result in a fitness cost to carriers-provides new opportunities for altering populations to benefit humanity and the environment in ways that are species specific and sustainable. Gene drive can be used to alter the genetic composition of an existing population, referred to as population modification or replacement, or to bring about population suppression or elimination. We describe technologies under consideration, progress that has been made, and remaining technological hurdles, particularly with respect to evolutionary stability and our ability to control the spread and ultimate fate of genes introduced into populations.
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Affiliation(s)
- Bruce A Hay
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA; ,
- St. John's College, University of Cambridge, Cambridge CB2 1TP, United Kingdom
| | - Georg Oberhofer
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA; ,
| | - Ming Guo
- Departments of Neurology and Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA;
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3
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Naegeli H, Bresson J, Dalmay T, Dewhurst IC, Epstein MM, Guerche P, Hejatko J, Moreno FJ, Mullins E, Nogué F, Rostoks N, Sánchez Serrano JJ, Savoini G, Veromann E, Veronesi F, Bonsall MB, Mumford J, Wimmer EA, Devos Y, Paraskevopoulos K, Firbank LG. Adequacy and sufficiency evaluation of existing EFSA guidelines for the molecular characterisation, environmental risk assessment and post-market environmental monitoring of genetically modified insects containing engineered gene drives. EFSA J 2020; 18:e06297. [PMID: 33209154 PMCID: PMC7658669 DOI: 10.2903/j.efsa.2020.6297] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Advances in molecular and synthetic biology are enabling the engineering of gene drives in insects for disease vector/pest control. Engineered gene drives (that bias their own inheritance) can be designed either to suppress interbreeding target populations or modify them with a new genotype. Depending on the engineered gene drive system, theoretically, a genetic modification of interest could spread through target populations and persist indefinitely, or be restricted in its spread or persistence. While research on engineered gene drives and their applications in insects is advancing at a fast pace, it will take several years for technological developments to move to practical applications for deliberate release into the environment. Some gene drive modified insects (GDMIs) have been tested experimentally in the laboratory, but none has been assessed in small-scale confined field trials or in open release trials as yet. There is concern that the deliberate release of GDMIs in the environment may have possible irreversible and unintended consequences. As a proactive measure, the European Food Safety Authority (EFSA) has been requested by the European Commission to review whether its previously published guidelines for the risk assessment of genetically modified animals (EFSA, 2012 and 2013), including insects (GMIs), are adequate and sufficient for GDMIs, primarily disease vectors, agricultural pests and invasive species, for deliberate release into the environment. Under this mandate, EFSA was not requested to develop risk assessment guidelines for GDMIs. In this Scientific Opinion, the Panel on Genetically Modified Organisms (GMO) concludes that EFSA's guidelines are adequate, but insufficient for the molecular characterisation (MC), environmental risk assessment (ERA) and post-market environmental monitoring (PMEM) of GDMIs. While the MC,ERA and PMEM of GDMIs can build on the existing risk assessment framework for GMIs that do not contain engineered gene drives, there are specific areas where further guidance is needed for GDMIs.
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Oberhofer G, Ivy T, Hay BA. Gene drive and resilience through renewal with next generation Cleave and Rescue selfish genetic elements. Proc Natl Acad Sci U S A 2020; 117:9013-9021. [PMID: 32245808 PMCID: PMC7183144 DOI: 10.1073/pnas.1921698117] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gene drive-based strategies for modifying populations face the problem that genes encoding cargo and the drive mechanism are subject to separation, mutational inactivation, and loss of efficacy. Resilience, an ability to respond to these eventualities in ways that restore population modification with functional genes, is needed for long-term success. Here, we show that resilience can be achieved through cycles of population modification with "Cleave and Rescue" (ClvR) selfish genetic elements. ClvR comprises a DNA sequence-modifying enzyme such as Cas9/gRNAs that disrupts endogenous versions of an essential gene and a recoded version of the essential gene resistant to cleavage. ClvR spreads by creating conditions in which those lacking ClvR die because they lack functional versions of the essential gene. Cycles of modification can, in principle, be carried out if two ClvR elements targeting different essential genes are located at the same genomic position, and one of them, ClvRn+1, carries a Rescue transgene from an earlier element, ClvRnClvRn+1 should spread within a population of ClvRn, while also bringing about a decrease in its frequency. To test this hypothesis, we first show that multiple ClvRs, each targeting a different essential gene, function when located at a common chromosomal position in Drosophila We then show that when several of these also carry the Rescue from a different ClvR, they spread to transgene fixation in populations fixed for the latter and at its expense. Therefore, genetic modifications of populations can be overwritten with new content, providing an ongoing point of control.
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Affiliation(s)
- Georg Oberhofer
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Tobin Ivy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Bruce A Hay
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125;
- St John's College, University of Cambridge, CB2 1TP Cambridge, United Kingdom
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5
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Cash SA, Robert MA, Lorenzen MD, Gould F. The impact of local population genetic background on the spread of the selfish element Medea-1 in red flour beetles. Ecol Evol 2020; 10:863-874. [PMID: 32015850 PMCID: PMC6988536 DOI: 10.1002/ece3.5946] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 11/24/2019] [Accepted: 11/27/2019] [Indexed: 12/18/2022] Open
Abstract
Selfish genetic elements have been found in the genomes of many species, yet our understanding of their evolutionary dynamics is only partially understood. A number of distinct selfish Medea elements are naturally present in many populations of the red flour beetle (Tribolium castaneum). Although these Medea elements are predicted by models to increase in frequency within populations because any offspring of a Medea-bearing mother that do not inherit at least one Medea allele will die, experiments demonstrating an increase in a naturally occurring Medea element are lacking. Our survey of the specific Medea element, M1, in the United States showed that it had a patchy geographic distribution. From the survey, it could not be determined if this distribution was caused by a slow process of M1 colonization of discrete populations or if some populations lacked M1 because they had genetic factors conferring resistance to the Medea mechanism. We show that populations with naturally low to intermediate M1 frequencies likely represent transient states during the process of Medea spread. Furthermore, we find no evidence that genetic factors are excluding M1 from US populations where the element is not presently found. We also show how a known suppressor of Medea can impair the increase of M1 in populations and discuss the implications of our findings for pest-management applications of Medea elements.
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Affiliation(s)
- Sarah A. Cash
- Graduate Program in GeneticsDepartment of Biological SciencesNorth Carolina State UniversityRaleighNorth Carolina
- W. M. Keck Center for Behavioral BiologyNorth Carolina State UniversityRaleighNorth Carolina
| | - Michael A. Robert
- Department of Mathematics, Physics, and StatisticsUniversity of the SciencesPhiladelphiaPennsylvania
| | - Marcé D. Lorenzen
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth Carolina
| | - Fred Gould
- W. M. Keck Center for Behavioral BiologyNorth Carolina State UniversityRaleighNorth Carolina
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth Carolina
- Genetic Engineering and Society CenterNorth Carolina State UniversityRaleighNorth Carolina
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Cash SA, Lorenzen MD, Gould F. The distribution and spread of naturally occurring Medea selfish genetic elements in the United States. Ecol Evol 2019; 9:14407-14416. [PMID: 31938528 PMCID: PMC6953677 DOI: 10.1002/ece3.5876] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 10/31/2019] [Accepted: 11/05/2019] [Indexed: 01/01/2023] Open
Abstract
Selfish genetic elements (SGEs) are DNA sequences that are transmitted to viable offspring in greater than Mendelian frequencies. Medea SGEs occur naturally in some populations of red flour beetle (Tribolium castaneum) and are expected to increase in frequency within populations and spread among populations. The large-scale U.S. distributions of Medea-4 (M4) had been mapped based on samples from 1993 to 1995. We sampled beetles in 2011-2014 and show that the distribution of M4 in the United States is dynamic and has shifted southward. By using a genetic marker of Medea-1 (M1), we found five unique geographic clusters with high and low M1 frequencies in a pattern not predicted by microsatellite-based analysis of population structure. Our results indicate the absence of rigid barriers to Medea spread in the United States, so assessment of what factors have limited its current distribution requires further investigation. There is great interest in using synthetic SGEs, including synthetic Medea, to alter or suppress pest populations, but there is concern about unpredicted spread of these SGEs and potential for populations to become resistant to them. The finding of patchy distributions of Medea elements suggests that released synthetic SGEs cannot always be expected to spread uniformly, especially in target species with limited dispersal.
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Affiliation(s)
- Sarah A. Cash
- Program in GeneticsDepartment of Biological SciencesNorth Carolina State UniversityRaleighNCUSA
| | - Marce D. Lorenzen
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNCUSA
| | - Fred Gould
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNCUSA
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Abstract
Synthetic gene drives may soon be used to suppress or eliminate populations of disease vectors, pathogens, invasive species, and agricultural pests. Recent proposals have focused on using Z-linked gene drives to control species with ZW sex determination, which include Lepidopteran pests, parasitic trematodes, and cane toads. These proposals include Z-linked 'W-shredders', which would suppress populations by cleaving the W chromosome and causing females to produce only sons, as well as Z-linked female-sterilizing gene drives. Here, I use eco-evolutionary simulations to evaluate the potential of some proposed Z-linked gene drives, and to produce recommendations regarding their design and use. The simulations show that W-shredders are likely to be highly effective at eradicating populations provided that resistance to W-shredding cannot evolve. However, W-shredder alleles can invade populations from very low frequencies, making it difficult to eliminate specific populations while leaving nearby populations untouched; this issue may restrict their possible uses.
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Affiliation(s)
- Luke Holman
- School of BioSciences, The University of Melbourne, Melbourne, Victoria 3010, Australia
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Barrett LG, Legros M, Kumaran N, Glassop D, Raghu S, Gardiner DM. Gene drives in plants: opportunities and challenges for weed control and engineered resilience. Proc Biol Sci 2019; 286:20191515. [PMID: 31551052 PMCID: PMC6784734 DOI: 10.1098/rspb.2019.1515] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 09/06/2019] [Indexed: 02/07/2023] Open
Abstract
Plant species, populations and communities are under threat from climate change, invasive pathogens, weeds and habitat fragmentation. Despite considerable research effort invested in genome engineering for crop improvement, the development of genetic tools for the management of wild plant populations has rarely been given detailed consideration. Gene drive systems that allow direct genetic management of plant populations via the spread of fitness-altering genetic modifications could be of great utility. However, despite the rapid development of synthetic tools and their enormous promise, little explicit consideration has been given to their application in plants and, to date, they remain untested. This article considers the potential utility of gene drives for the management of wild plant populations, and examines the factors that might influence the design, spread and efficacy of synthetic drives. To gain insight into optimal ways to design and deploy synthetic drive systems, we investigate the diversity of mechanisms underlying natural gene drives and their dynamics within plant populations and species. We also review potential approaches for engineering gene drives and discuss their potential application to plant genomes. We highlight the importance of considering the impact of plant life-history and genetic architecture on the dynamics of drive, investigate the potential for different types of resistance evolution, and touch on the ethical, regulatory and social challenges ahead.
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Affiliation(s)
- Luke G. Barrett
- CSIRO Agriculture and Food, Canberra, Australian Capital Territory, Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, Australian Capital Territory, Australia
| | - Mathieu Legros
- CSIRO Agriculture and Food, Canberra, Australian Capital Territory, Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, Australian Capital Territory, Australia
| | | | - Donna Glassop
- CSIRO Agriculture and Food, Canberra, Australian Capital Territory, Australia
| | - S. Raghu
- CSIRO Health and Biosecurity, Brisbane, Queensland, Australia
| | - Donald M. Gardiner
- CSIRO Agriculture and Food, Canberra, Australian Capital Territory, Australia
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9
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Oberhofer G, Ivy T, Hay BA. Cleave and Rescue, a novel selfish genetic element and general strategy for gene drive. Proc Natl Acad Sci U S A 2019; 116:6250-6259. [PMID: 30760597 PMCID: PMC6442612 DOI: 10.1073/pnas.1816928116] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
There is great interest in being able to spread beneficial traits throughout wild populations in ways that are self-sustaining. Here, we describe a chromosomal selfish genetic element, CleaveR [Cleave and Rescue (ClvR)], able to achieve this goal. ClvR comprises two linked chromosomal components. One, germline-expressed Cas9 and guide RNAs (gRNAs)-the Cleaver-cleaves and thereby disrupts endogenous copies of a gene whose product is essential. The other, a recoded version of the essential gene resistant to cleavage and gene conversion with cleaved copies-the Rescue-provides essential gene function. ClvR enhances its transmission, and that of linked genes, by creating conditions in which progeny lacking ClvR die because they have no functional copies of the essential gene. In contrast, those who inherit ClvR survive, resulting in an increase in ClvR frequency. ClvR is predicted to spread to fixation under diverse conditions. To test these predictions, we generated a ClvR element in Drosophila melanogasterClvRtko is located on chromosome 3 and uses Cas9 and four gRNAs to disrupt melanogaster technical knockout (tko), an X-linked essential gene. Rescue activity is provided by tko from Drosophila virilisClvRtko results in germline and maternal carryover-dependent inactivation of melanogaster tko (>99% per generation); lethality caused by this loss is rescued by the virilis transgene; ClvRtko activities are robust to genetic diversity in strains from five continents; and uncleavable but functional melanogaster tko alleles were not observed. Finally, ClvRtko spreads to transgene fixation. The simplicity of ClvR suggests it may be useful for altering populations in diverse species.
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Affiliation(s)
- Georg Oberhofer
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Tobin Ivy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Bruce A Hay
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
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10
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Abstract
Background Aedes aegypti is an important mosquito vector that transmits arboviruses that cause devastating diseases including Zika, dengue fever, yellow fever and chikungunya. Improved understanding of gene regulation in the early development of Ae. aegypti will facilitate genetic studies and help the development of novel control strategies of this important disease vector. Results In this study, we demonstrated through transgenic assays that the promoter of an endogenous early zygotic gene KLC2 could drive gene expression in the syncytial blastoderm and early cellular blastoderm, which is a stage that the developing germline and the rest of embryo are accessible to genetic manipulation. An unexpected expression of the reporter gene in transgenic male testes was also observed. Further analysis confirmed the expression of the endogenous KLC2 in the testes, which was not detected in the previous RNA sequencing data. Conclusions Our finding provided a new promoter element that can be used in future genetic studies and applications in Ae. aegypti. Moreover, our transgenic reporter assays showed that cautions are needed when interpreting RNA sequencing data as transient or tissue-specific transcription may go undetected by RNAseq. Electronic supplementary material The online version of this article (10.1186/s13071-018-3210-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wanqi Hu
- Department of Biochemistry, Virginia Tech, 303 Fralin, Blacksburg, VA, 24061, USA.,Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Zhijian Jake Tu
- Department of Biochemistry, Virginia Tech, 303 Fralin, Blacksburg, VA, 24061, USA. .,Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, 24061, USA.
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11
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Gantz VM, Akbari OS. Gene editing technologies and applications for insects. CURRENT OPINION IN INSECT SCIENCE 2018; 28:66-72. [PMID: 30551769 PMCID: PMC6296244 DOI: 10.1016/j.cois.2018.05.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 05/09/2023]
Abstract
Initially discovered in bacteria, CRISPR-based genome editing endonucleases have proven remarkably amenable for adaptation to insects. To date, these endonucleases have been utilized in a plethora of both model and non-model insects including diverse flies, bees, beetles, butterflies, moths, and grasshoppers, to name a few, thereby revolutionizing functional genomics of insects. In addition to basic genome editing, they have also been invaluable for advanced genome engineering and synthetic biology applications. Here we explore the recent genome editing advancements in insects for generating site-specific genomic mutations, insertions, deletions, as well as more advanced applications such as Homology Assisted Genome Knock-in (HACK), potential to utilize DNA base editing, generating predictable reciprocal chromosomal translocations, and development gene drives to control the fate of wild populations.
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Affiliation(s)
- Valentino M Gantz
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92092, USA; Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, USA
| | - Omar S Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92092, USA; Tata Institute for Genetics and Society, University of California, San Diego, La Jolla, CA 92093, USA.
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12
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Buchman AB, Ivy T, Marshall JM, Akbari OS, Hay BA. Engineered Reciprocal Chromosome Translocations Drive High Threshold, Reversible Population Replacement in Drosophila. ACS Synth Biol 2018. [PMID: 29608276 DOI: 10.1101/088393] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Replacement of wild insect populations with transgene-bearing individuals unable to transmit disease or survive under specific environmental conditions using gene drive provides a self-perpetuating method of disease prevention. Mechanisms that require the gene drive element and linked cargo to exceed a high threshold frequency in order for spread to occur are attractive because they offer several points of control: they bring about local, but not global population replacement; and transgenes can be eliminated by reintroducing wildtypes into the population so as to drive the frequency of transgenes below the threshold frequency required for drive. Reciprocal chromosome translocations were proposed as a tool for bringing about high threshold population replacement in 1940 and 1968. However, translocations able to achieve this goal have only been reported once, in the spider mite Tetranychus urticae, a haplo-diploid species in which there is strong selection in haploid males for fit homozygotes. We report the creation of engineered translocation-bearing strains of Drosophila melanogaster, generated through targeted chromosomal breakage and homologous recombination. These strains drive high threshold population replacement in laboratory populations. While it remains to be shown that engineered translocations can bring about population replacement in wild populations, these observations suggest that further exploration of engineered translocations as a tool for controlled population replacement is warranted.
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Affiliation(s)
- Anna B Buchman
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Tobin Ivy
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - John M Marshall
- School of Public Health , University of California , Berkeley , California 94720 , United States
| | - Omar S Akbari
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Bruce A Hay
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
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13
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Buchman AB, Ivy T, Marshall JM, Akbari OS, Hay BA. Engineered Reciprocal Chromosome Translocations Drive High Threshold, Reversible Population Replacement in Drosophila. ACS Synth Biol 2018; 7:1359-1370. [PMID: 29608276 DOI: 10.1021/acssynbio.7b00451] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Replacement of wild insect populations with transgene-bearing individuals unable to transmit disease or survive under specific environmental conditions using gene drive provides a self-perpetuating method of disease prevention. Mechanisms that require the gene drive element and linked cargo to exceed a high threshold frequency in order for spread to occur are attractive because they offer several points of control: they bring about local, but not global population replacement; and transgenes can be eliminated by reintroducing wildtypes into the population so as to drive the frequency of transgenes below the threshold frequency required for drive. Reciprocal chromosome translocations were proposed as a tool for bringing about high threshold population replacement in 1940 and 1968. However, translocations able to achieve this goal have only been reported once, in the spider mite Tetranychus urticae, a haplo-diploid species in which there is strong selection in haploid males for fit homozygotes. We report the creation of engineered translocation-bearing strains of Drosophila melanogaster, generated through targeted chromosomal breakage and homologous recombination. These strains drive high threshold population replacement in laboratory populations. While it remains to be shown that engineered translocations can bring about population replacement in wild populations, these observations suggest that further exploration of engineered translocations as a tool for controlled population replacement is warranted.
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Affiliation(s)
- Anna B Buchman
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Tobin Ivy
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
| | - John M Marshall
- School of Public Health , University of California , Berkeley , California 94720 , United States
| | - Omar S Akbari
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
| | - Bruce A Hay
- Division of Biology and Biological Engineering , California Institute of Technology , Pasadena , California 91125 , United States
- Division of Biological Sciences , University of California , San Diego , California 92161 , United States
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14
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Benedict MQ, Burt A, Capurro ML, De Barro P, Handler AM, Hayes KR, Marshall JM, Tabachnick WJ, Adelman ZN. Recommendations for Laboratory Containment and Management of Gene Drive Systems in Arthropods. Vector Borne Zoonotic Dis 2018; 18:2-13. [PMID: 29040058 PMCID: PMC5846571 DOI: 10.1089/vbz.2017.2121] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Versatile molecular tools for creating driving transgenes and other invasive genetic factors present regulatory, ethical, and environmental challenges that should be addressed to ensure their safe use. In this article, we discuss driving transgenes and invasive genetic factors that can potentially spread after their introduction into a small proportion of individuals in a population. The potential of invasive genetic factors to increase their number in natural populations presents challenges that require additional safety measures not provided by previous recommendations regarding accidental release of arthropods. In addition to providing physical containment, invasive genetic factors require greater attention to strain management, including their distribution and identity confirmation. In this study, we focus on insects containing such factors with recommendations for investigators who are creating them, institutional biosafety committees charged with ensuring safety, funding agencies providing support, those managing insectaries handling these materials who are responsible for containment, and other persons who will be receiving insects-transgenic or not-from these facilities. We give specific examples of efforts to modify mosquitoes for mosquito-borne disease control, but similar considerations are relevant to other arthropods that are important to human health, the environment, and agriculture.
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Affiliation(s)
- Mark Q Benedict
- 1 Entomology Branch, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia
| | - Austin Burt
- 2 Life Sciences, Imperial College London , Ascot, United Kingdom
| | - Margareth L Capurro
- 3 Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo , Sao Paulo, Brazil
- 4 National Institute of Science and Technology in Molecular Entomology , National Council of Scientific and Technological Development (INCT-EM/CNPq), Rio de Janeiro, Brazil
| | | | - Alfred M Handler
- 6 USDA-ARS, Center for Medical, Agricultural, and Veterinary Entomology , Gainesville, Florida
| | | | - John M Marshall
- 8 Divisions of Biostatistics and Epidemiology, School of Public Health, University of California , Berkeley, California
| | - Walter J Tabachnick
- 9 Florida Medical Entomology Laboratory, Department of Entomology and Nematology, University of Florida , Vero Beach, Florida
| | - Zach N Adelman
- 10 Department of Entomology, Texas A&M University , College Station, Texas
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15
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Edgington MP, Alphey LS. Conditions for success of engineered underdominance gene drive systems. J Theor Biol 2017; 430:128-140. [PMID: 28728996 PMCID: PMC5562440 DOI: 10.1016/j.jtbi.2017.07.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 06/20/2017] [Accepted: 07/15/2017] [Indexed: 12/02/2022]
Abstract
Engineered underdominance is one of a number of different gene drive strategies that have been proposed for the genetic control of insect vectors of disease. Here we model a two-locus engineered underdominance based gene drive system that is based on the concept of mutually suppressing lethals. In such a system two genetic constructs are introduced, each possessing a lethal element and a suppressor of the lethal at the other locus. Specifically, we formulate and analyse a population genetics model of this system to assess when different combinations of release strategies (i.e. single or multiple releases of both sexes or males only) and genetic systems (i.e. bisex lethal or female-specific lethal elements and different strengths of suppressors) will give population replacement or fail to do so. We anticipate that results presented here will inform the future design of engineered underdominance gene drive systems as well as providing a point of reference regarding release strategies for those looking to test such a system. Our discussion is framed in the context of genetic control of insect vectors of disease. One of several serious threats in this context are Aedes aegypti mosquitoes as they are the primary vectors of dengue viruses. However, results are also applicable to Ae. aegypti as vectors of Zika, yellow fever and chikungunya viruses and also to the control of a number of other insect species and thereby of insect-vectored pathogens.
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Affiliation(s)
| | - Luke S Alphey
- The Pirbright Institute, Ash Road, Woking, Surrey, GU24 0NF, UK
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16
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Lindholm AK, Dyer KA, Firman RC, Fishman L, Forstmeier W, Holman L, Johannesson H, Knief U, Kokko H, Larracuente AM, Manser A, Montchamp-Moreau C, Petrosyan VG, Pomiankowski A, Presgraves DC, Safronova LD, Sutter A, Unckless RL, Verspoor RL, Wedell N, Wilkinson GS, Price TA. The Ecology and Evolutionary Dynamics of Meiotic Drive. Trends Ecol Evol 2016; 31:315-326. [DOI: 10.1016/j.tree.2016.02.001] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/29/2016] [Accepted: 02/01/2016] [Indexed: 12/24/2022]
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17
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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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18
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Reid W, O'Brochta DA. Applications of genome editing in insects. CURRENT OPINION IN INSECT SCIENCE 2016; 13:43-54. [PMID: 27436552 DOI: 10.1016/j.cois.2015.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 09/23/2015] [Accepted: 11/01/2015] [Indexed: 05/14/2023]
Abstract
Insect genome editing was first reported 1991 in Drosophila melanogaster but the technology used was not portable to other species. Not until the recent development of facile, engineered DNA endonuclease systems has gene editing become widely available to insect scientists. Most applications in insects to date have been technical in nature but this is rapidly changing. Functional genomics and genetics-based insect control efforts will be major beneficiaries of the application of contemporary gene editing technologies. Engineered endonucleases like Cas9 make it possible to create powerful and effective gene drive systems that could be used to reduce or even eradicate specific insect populations. 'Best practices' for using Cas9-based editing are beginning to emerge making it easier and more effective to design and use but gene editing technologies still require traditional means of delivery in order to introduce them into somatic and germ cells of insects-microinjection of developing embryos. This constrains the use of these technologies by insect scientists. Insects created using editing technologies challenge existing governmental regulatory structures designed to manage genetically modified organisms.
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Affiliation(s)
- William Reid
- Institute for Bioscience and Biotechnology Research, Department of Entomology, 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.
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19
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Lainhart W, Bickersmith SA, Nadler KJ, Moreno M, Saavedra MP, Chu VM, Ribolla PE, Vinetz JM, Conn JE. Evidence for temporal population replacement and the signature of ecological adaptation in a major Neotropical malaria vector in Amazonian Peru. Malar J 2015; 14:375. [PMID: 26415942 PMCID: PMC4587789 DOI: 10.1186/s12936-015-0863-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 08/23/2015] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The major Neotropical malaria vector, Anopheles darlingi, was reintroduced into the Iquitos, Loreto, Peru area during the early 1990s, where it displaced other anophelines and caused a major malaria epidemic. Since then, case numbers in Loreto have fluctuated, but annual increases have been reported since 2012. METHODS The population genetic structure of An. darlingi sampled before and after the introduction of long-lasting insecticidal nets (LLINs) was investigated to test the hypothesis of temporal population change (2006 vs. 2012). Current samples of An. darlingi were used to test the hypothesis of ecological adaptation to human modified (highway) compared with wild (riverine) habitat, linked to forest cover. In total, 693 An. darlingi from nine localities in Loreto, Peru area were genotyped using 13 microsatellite loci. To test the hypothesis of habitat differentiation in An. darlingi biting time patterns, HBR and EIR, four collections of An. darlingi from five localities (two riverine and three highway) were analysed. RESULTS Analyses of microsatellite loci from seven (2006) and nine settlements (2012-2014) in the Iquitos area detected two distinctive populations with little overlap, although it is unclear whether this population replacement event is associated with LLIN distribution or climate. Within the 2012-2014 population two admixed subpopulations, A and B, were differentiated by habitat, with B significantly overrepresented in highway, and both in near-equal proportions in riverine. Both subpopulations had a signature of expansion and there was moderate genetic differentiation between them. Habitat and forest cover level had significant effects on HBR, such that Plasmodium transmission risk, as measured by EIR, in peridomestic riverine settlements was threefold higher than in peridomestic highway settlements. HBR was directly associated with available host biomass rather than forest cover. CONCLUSIONS A population replacement event occurred between 2006 and 2012-2014, concurrently with LLIN distribution and a moderate El Niño event, and prior to an increase in malaria incidence. The likely drivers of this replacement cannot be determined with current data. The present-day An. darlingi population is composed of two highly admixed subpopulations, which appear to be in an early stage of differentiation, triggered by anthropogenic alterations to local habitat.
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Affiliation(s)
- William Lainhart
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, NY, USA.
- Wadsworth Center, New York State Department of Health, Griffin Laboratory, 5669 State Farm Road, Building 1, Room 101, Slingerlands, NY, 12159, USA.
| | - Sara A Bickersmith
- Wadsworth Center, New York State Department of Health, Griffin Laboratory, 5669 State Farm Road, Building 1, Room 101, Slingerlands, NY, 12159, USA.
| | - Kyle J Nadler
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, NY, USA.
| | - Marta Moreno
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
| | | | - Virginia M Chu
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, NY, USA.
- Wadsworth Center, New York State Department of Health, Griffin Laboratory, 5669 State Farm Road, Building 1, Room 101, Slingerlands, NY, 12159, USA.
| | | | - Joseph M Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
- Instituto de Medicine Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru.
| | - Jan E Conn
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, NY, USA.
- Wadsworth Center, New York State Department of Health, Griffin Laboratory, 5669 State Farm Road, Building 1, Room 101, Slingerlands, NY, 12159, USA.
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20
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Olson KE, Franz AWE. Advances in genetically modified Aedes aegypti to control transmission of dengue viruses. Future Virol 2015. [DOI: 10.2217/fvl.15.38] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ABSTRACT Dengue viruses (DENV) are mosquito-borne viruses that infect millions of humans each year. DENVs are endemic in tropical regions of the world and maintained in a transmission cycle between mosquito vectors (Aedes aegypti) and humans. DEN disease control relies on vector control approaches that have had limited success and are difficult to sustain. Genetically modified mosquitoes (GMM) may be an alternative control strategy to limit DENV transmission. GMM-based control strategies include: conditional expression of a dominant lethal gene (RIDL) to reduce vector populations; and introgression of antipathogen (AP) genes into wild-type vectors for population replacement. In this review, we describe novel GMM-based strategies to limit DENV transmission and discuss potential hurdles to their successful implementation in the field.
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Affiliation(s)
- Ken E Olson
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Alexander WE Franz
- Department of Veterinary Pathobiology, 303 Connaway Hall, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
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21
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Franz AWE, Balaraman V, Fraser MJ. Disruption of dengue virus transmission by mosquitoes. CURRENT OPINION IN INSECT SCIENCE 2015; 8:88-96. [PMID: 26120563 PMCID: PMC4480767 DOI: 10.1016/j.cois.2014.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Current control efforts for mosquito-borne arboviruses focus on mosquito control involving insecticide applications, which are becoming increasingly ineffective and unsustainable in urban areas. Mosquito population replacement is an alternative arbovirus control concept aiming at replacing virus-competent vector populations with laboratory-engineered incompetent vectors. A prerequisite for this strategy is the design of robust anti-pathogen effectors that can ultimately be genetically driven through a wild-type population. Several anti-pathogen effector concepts have been developed that target the RNA genomes of arboviruses such as dengue virus in a highly sequence-specific manner. Design principles are based on long inverted-repeat RNA triggered RNA interference, catalytic hammerhead ribozymes, and trans-splicing Group I Introns that are able to induce apoptosis in virus-infected cells following splicing with target viral RNA.
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Affiliation(s)
- Alexander W E Franz
- Department of Veterinary Pathobiology, 303 Connaway Hall, College of Veterinary Medicine, University of Missouri, Columbia MO, 65211, United States of America
| | - Velmurugan Balaraman
- Department of Veterinary Pathobiology, 303 Connaway Hall, College of Veterinary Medicine, University of Missouri, Columbia MO, 65211, United States of America
| | - Malcolm J Fraser
- Department of Biological Sciences, 218 Galvin Life Science Bldg., University of Notre Dame, South Bend IN, 46617, United States of America
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22
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Robert MA, Okamoto KW, Gould F, Lloyd AL. Antipathogen genes and the replacement of disease-vectoring mosquito populations: a model-based evaluation. Evol Appl 2014; 7:1238-51. [PMID: 25558284 PMCID: PMC4275095 DOI: 10.1111/eva.12219] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 08/27/2014] [Indexed: 12/25/2022] Open
Abstract
Recently, genetic strategies aimed at controlling populations of disease-vectoring mosquitoes have received considerable attention as alternatives to traditional measures. Theoretical studies have shown that female-killing (FK), antipathogen (AP), and reduce and replace (R&R) strategies can each decrease the number competent vectors. In this study, we utilize a mathematical model to evaluate impacts on competent Aedes aegypti populations of FK, AP, and R&R releases as well as hybrid strategies that result from combinations of these three approaches. We show that while the ordering of efficacy of these strategies depends upon population life history parameters, sex ratio of releases, and switch time in combination strategies, AP-only and R&R/AP releases typically lead to the greatest long-term reduction in competent vectors. R&R-only releases are often less effective at long-term reduction of competent vectors than AP-only releases or R&R/AP releases. Furthermore, the reduction in competent vectors caused by AP-only releases is easier to maintain than that caused by FK-only or R&R-only releases even when the AP gene confers a fitness cost. We discuss the roles that density dependence and inclusion of females play in the order of efficacy of the strategies. We anticipate that our results will provide added impetus to continue developing AP strategies.
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Affiliation(s)
- Michael A Robert
- Department of Mathematics and Biomathematics Graduate Program, North Carolina State University Raleigh, NC, USA ; Department of Biology and Department of Mathematics and Statistics, University of New Mexico Albuquerque, NM, USA
| | - Kenichi W Okamoto
- Department of Entomology, North Carolina State University Raleigh, NC, USA
| | - Fred Gould
- Department of Entomology, North Carolina State University Raleigh, NC, USA ; Fogarty International Center, National Institutes of Health Bethesda, MD, USA
| | - Alun L Lloyd
- Department of Mathematics and Biomathematics Graduate Program, North Carolina State University Raleigh, NC, USA ; Fogarty International Center, National Institutes of Health Bethesda, MD, USA
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23
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Medusa: a novel gene drive system for confined suppression of insect populations. PLoS One 2014; 9:e102694. [PMID: 25054803 PMCID: PMC4108329 DOI: 10.1371/journal.pone.0102694] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Accepted: 06/23/2014] [Indexed: 01/03/2023] Open
Abstract
Gene drive systems provide novel opportunities for insect population suppression by driving genes that confer a fitness cost into pest or disease vector populations; however regulatory issues arise when genes are capable of spreading across international borders. Gene drive systems displaying threshold properties provide a solution since they can be confined to local populations and eliminated through dilution with wild-types. We propose a novel, threshold-dependent gene drive system, Medusa, capable of inducing a local and reversible population crash. Medusa consists of four components - two on the X chromosome, and two on the Y chromosome. A maternally-expressed, X-linked toxin and a zygotically-expressed, Y-linked antidote results in suppression of the female population and selection for the presence of the transgene-bearing Y because only male offspring of Medusa-bearing females are protected from the effects of the toxin. At the same time, the combination of a zygotically-expressed, Y-linked toxin and a zygotically-expressed, X-linked antidote selects for the transgene-bearing X in the presence of the transgene-bearing Y. Together these chromosomes create a balanced lethal system that spreads while selecting against females when present above a certain threshold frequency. Simple population dynamic models show that an all-male release of Medusa males, carried out over six generations, is expected to induce a population crash within 12 generations for modest release sizes on the order of the wild population size. Re-invasion of non-transgenic insects into a suppressed population can result in a population rebound; however this can be prevented through regular releases of modest numbers of Medusa males. Finally, we outline how Medusa could be engineered with currently available molecular tools.
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24
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Gokhale CS, Reeves RG, Reed FA. Dynamics of a combined Medea-underdominant population transformation system. BMC Evol Biol 2014; 14:98. [PMID: 24884575 PMCID: PMC4068157 DOI: 10.1186/1471-2148-14-98] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 04/28/2014] [Indexed: 01/16/2023] Open
Abstract
Background Transgenic constructs intended to be stably established at high frequencies in
wild populations have been demonstrated to “drive” from low
frequencies in experimental insect populations. Linking such population
transformation constructs to genes which render them unable to transmit pathogens
could eventually be used to stop the spread of vector-borne diseases like malaria
and dengue. Results Generally, population transformation constructs with only a single transgenic
drive mechanism have been envisioned. Using a theoretical modelling approach we
describe the predicted properties of a construct combining autosomal Medea and
underdominant population transformation systems. We show that when combined they
can exhibit synergistic properties which in broad circumstances surpass those of
the single systems. Conclusion With combined systems, intentional population transformation and its reversal can
be achieved readily. Combined constructs also enhance the capacity to
geographically restrict transgenic constructs to targeted populations. It is
anticipated that these properties are likely to be of particular value in
attracting regulatory approval and public acceptance of this novel technology.
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Affiliation(s)
- Chaitanya S Gokhale
- Department of Evolutionary Theory, Max Planck Institute for Evolutionary Biology, August Thienemann Str-2, 24306 Plön, Germany.
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25
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Carvalho DO, Costa-da-Silva AL, Lees RS, Capurro ML. Two step male release strategy using transgenic mosquito lines to control transmission of vector-borne diseases. Acta Trop 2014; 132 Suppl:S170-7. [PMID: 24513036 DOI: 10.1016/j.actatropica.2013.09.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/21/2013] [Accepted: 09/26/2013] [Indexed: 12/27/2022]
Abstract
Mosquitoes are responsible for the transmission of pathogens that cause devastating human diseases such as malaria and dengue. The current increase in mean global temperature and changing sea level interfere with precipitation frequency and some other climatic conditions which, in general, influence the rate of development of insects and etiologic agents causing acceleration as the temperature rises. The most common strategy employed to combat target mosquito species is the Integrated Vector Management (IVM), which comprises the use of multiple activities and various approaches to preventing the spread of a vector in infested areas. IVM programmes are becoming ineffective; and the global scenario is threatening, requiring new interventions for vector control and surveillance. Not surprisingly, there is a growing need to find alternative methods to combat the mosquito vectors. The possibility of using transgenic mosquitoes to fight against those diseases has been discussed over the last two decades and this use of transgenic lines to suppress populations or to replace them is still under investigation through field and laboratory trials. As an alternative, the available transgenic strategies could be improved by coupling suppression and substitution strategies. The idea is to first release a suppression line to significantly reduce the wild population, and once the first objective is reached a second release using a substitution line could be then performed. Examples of targeting this approach against vectors of malaria and dengue are discussed.
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26
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Akbari OS, Papathanos PA, Sandler JE, Kennedy K, Hay BA. Identification of germline transcriptional regulatory elements in Aedes aegypti. Sci Rep 2014; 4:3954. [PMID: 24492376 PMCID: PMC3912481 DOI: 10.1038/srep03954] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 01/16/2014] [Indexed: 12/18/2022] Open
Abstract
The mosquito Aedes aegypti is the principal vector for the yellow fever and dengue viruses, and is also responsible for recent outbreaks of the alphavirus chikungunya. Vector control strategies utilizing engineered gene drive systems are being developed as a means of replacing wild, pathogen transmitting mosquitoes with individuals refractory to disease transmission, or bringing about population suppression. Several of these systems, including Medea, UD(MEL), and site-specific nucleases, which can be used to drive genes into populations or bring about population suppression, utilize transcriptional regulatory elements that drive germline-specific expression. Here we report the identification of multiple regulatory elements able to drive gene expression specifically in the female germline, or in the male and female germline, in the mosquito Aedes aegypti. These elements can also be used as tools with which to probe the roles of specific genes in germline function and in the early embryo, through overexpression or RNA interference.
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Affiliation(s)
- Omar S Akbari
- 1] Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA [2]
| | - Philippos A Papathanos
- 1] Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA [2]
| | - Jeremy E Sandler
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
| | - Katie Kennedy
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
| | - Bruce A Hay
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
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27
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Alphey L, McKemey A, Nimmo D, Neira Oviedo M, Lacroix R, Matzen K, Beech C. Genetic control of Aedes mosquitoes. Pathog Glob Health 2014; 107:170-9. [PMID: 23816508 DOI: 10.1179/2047773213y.0000000095] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Aedes mosquitoes include important vector species such as Aedes aegypti, the major vector of dengue. Genetic control methods are being developed for several of these species, stimulated by an urgent need owing to the poor effectiveness of current methods combined with an increase in chemical pesticide resistance. In this review we discuss the various genetic strategies that have been proposed, their present status, and future prospects. We focus particularly on those methods that are already being tested in the field, including RIDL and Wolbachia-based approaches.
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Affiliation(s)
- Luke Alphey
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, UK.
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28
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Novel Genetic and Molecular Tools for the Investigation and Control of Dengue Virus Transmission by Mosquitoes. CURRENT TROPICAL MEDICINE REPORTS 2014; 1:21-31. [PMID: 24693489 DOI: 10.1007/s40475-013-0007-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Aedes aegypti is the principal vector of dengue virus (DENV) throughout the tropical world. This anthropophilic mosquito species needs to be persistently infected with DENV before it can transmit the virus through its saliva to a new vertebrate host. In the mosquito, DENV is confronted with several innate immune pathways, among which RNA interference is considered the most important. The Ae. aegypti genome project opened the doors for advanced molecular studies on pathogen-vector interactions including genetic manipulation of the vector for basic research and vector control purposes. Thus, Ae. aegypti has become the primary model for studying vector competence for arboviruses at the molecular level. Here, we present recent findings regarding DENV-mosquito interactions, emphasizing how innate immune responses modulate DENV infections in Ae. aegypti. We also describe the latest advancements in genetic manipulation of Ae. aegypti and discuss how this technology can be used to investigate vector transmission of DENV at the molecular level and to control transmission of the virus in the field.
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29
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Abstract
Genetics can potentially provide new, species-specific, environmentally friendly methods for mosquito control. Genetic control strategies aim either to suppress target populations or to introduce a harm-reducing novel trait. Different approaches differ considerably in their properties, especially between self-limiting strategies, where the modification has limited persistence, and self-sustaining strategies, which are intended to persist indefinitely in the target population and may invade other populations. Several methods with different molecular biology are under development and the first field trials have been completed successfully.
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Affiliation(s)
- Luke Alphey
- Oxitec Limited, Oxford OX14 4RX, United Kingdom;
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30
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The developmental transcriptome of the mosquito Aedes aegypti, an invasive species and major arbovirus vector. G3-GENES GENOMES GENETICS 2013; 3:1493-509. [PMID: 23833213 PMCID: PMC3755910 DOI: 10.1534/g3.113.006742] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mosquitoes are vectors of a number of important human and animal diseases. The development of novel vector control strategies requires a thorough understanding of mosquito biology. To facilitate this, we used RNA-seq to identify novel genes and provide the first high-resolution view of the transcriptome throughout development and in response to blood feeding in a mosquito vector of human disease, Aedes aegypti, the primary vector for Dengue and yellow fever. We characterized mRNA expression at 34 distinct time points throughout Aedes development, including adult somatic and germline tissues, by using polyA+ RNA-seq. We identify a total of 14,238 novel new transcribed regions corresponding to 12,597 new loci, as well as many novel transcript isoforms of previously annotated genes. Altogether these results increase the annotated fraction of the transcribed genome into long polyA+ RNAs by more than twofold. We also identified a number of patterns of shared gene expression, as well as genes and/or exons expressed sex-specifically or sex-differentially. Expression profiles of small RNAs in ovaries, early embryos, testes, and adult male and female somatic tissues also were determined, resulting in the identification of 38 new Aedes-specific miRNAs, and ~291,000 small RNA new transcribed regions, many of which are likely to be endogenous small-interfering RNAs and Piwi-interacting RNAs. Genes of potential interest for transgene-based vector control strategies also are highlighted. Our data have been incorporated into a user-friendly genome browser located at www.Aedes.caltech.edu, with relevant links to Vectorbase (www.vectorbase.org)
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32
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Clayton AM, Cirimotich CM, Dong Y, Dimopoulos G. Caudal is a negative regulator of the Anopheles IMD pathway that controls resistance to Plasmodium falciparum infection. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2013; 39:323-332. [PMID: 23178401 PMCID: PMC3892953 DOI: 10.1016/j.dci.2012.10.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/11/2012] [Accepted: 10/12/2012] [Indexed: 06/02/2023]
Abstract
Malaria parasite transmission depends upon the successful development of Plasmodium in its Anopheles mosquito vector. The mosquito's innate immune system constitutes a major bottleneck for parasite population growth. We show here that in Anopheles gambiae, the midgut-specific transcription factor Caudal acts as a negative regulator in the Imd pathway-mediated immune response against the human malaria parasite Plasmodium falciparum. Caudal also modulates the mosquito midgut bacterial flora. RNAi-mediated silencing of Caudal enhanced the mosquito's resistance to bacterial infections and increased the transcriptional abundance of key immune effector genes. Interestingly, Caudal's silencing resulted in an increased lifespan of the mosquito, while it impaired reproductive fitness with respect to egg laying and hatching.
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Affiliation(s)
| | | | | | - George Dimopoulos
- Corresponding author. Address: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe Street, Baltimore, MD 21205, USA. Tel.: 1-443-287-0128. Fax: 1-410-955-0105.
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Akbari OS, Matzen KD, Marshall JM, Huang H, Ward CM, Hay BA. A synthetic gene drive system for local, reversible modification and suppression of insect populations. Curr Biol 2013; 23:671-7. [PMID: 23541732 DOI: 10.1016/j.cub.2013.02.059] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 12/18/2012] [Accepted: 02/27/2013] [Indexed: 01/12/2023]
Abstract
Replacement of wild insect populations with genetically modified individuals unable to transmit disease provides a self-perpetuating method of disease prevention but requires a gene drive mechanism to spread these traits to high frequency. Drive mechanisms requiring that transgenes exceed a threshold frequency in order to spread are attractive because they bring about local but not global replacement, and transgenes can be eliminated through dilution of the population with wild-type individuals. These features are likely to be important in many social and regulatory contexts. Here we describe the first creation of a synthetic threshold-dependent gene drive system, designated maternal-effect lethal underdominance (UD(MEL)), in which two maternally expressed toxins, located on separate chromosomes, are each linked with a zygotic antidote able to rescue maternal-effect lethality of the other toxin. We demonstrate threshold-dependent replacement in single- and two-locus configurations in Drosophila. Models suggest that transgene spread can often be limited to local environments. They also show that in a population in which single-locus UD(MEL) has been carried out, repeated release of wild-type males can result in population suppression, a novel method of genetic population manipulation.
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Affiliation(s)
- Omar S Akbari
- Division of Biology, MC 156-29, California Institute of Technology, Pasadena, CA 91125, USA
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Godfray HCJ. Mosquito ecology and control of malaria. J Anim Ecol 2012; 82:15-25. [DOI: 10.1111/1365-2656.12003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 09/01/2012] [Indexed: 11/30/2022]
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Abstract
Gene drive systems are genetic elements capable of spreading into a population even if they confer a fitness cost to their host. We consider a class of drive systems consisting of a chromosomally located, linked cluster of genes, the presence of which renders specific classes of offspring arising from specific parental crosses unviable. Under permissive conditions, a number of these elements are capable of distorting the offspring ratio in their favor. We use a population genetic framework to derive conditions under which these elements spread to fixation in a population or induce a population crash. Many of these systems can be engineered using combinations of toxin and antidote genes, analogous to Medea, which consists of a maternal toxin and zygotic antidote. The majority of toxin–antidote drive systems require a critical frequency to be exceeded before they spread into a population. Of particular interest, a Z-linked Medea construct with a recessive antidote is expected to induce an all-male population crash for release frequencies above 50%. We suggest molecular tools that may be used to build these systems, and discuss their relevance to the control of a variety of insect pest species, including mosquito vectors of diseases such as malaria and dengue fever.
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Affiliation(s)
- John M Marshall
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
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Tkachuk A, Kim M, Kravchuk O, Savitsky M. A new powerful method for site-specific transgene stabilization based on chromosomal double-strand break repair. PLoS One 2011; 6:e26422. [PMID: 22022613 PMCID: PMC3195726 DOI: 10.1371/journal.pone.0026422] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 09/26/2011] [Indexed: 12/20/2022] Open
Abstract
Transgenic insects are a promising tool in sterile insect techniques and population replacement strategies. Such transgenic insects can be created using nonautonomous transposons, which cannot be transferred without a transposase source. In biocontrol procedures where large numbers of insects are released, there is increased risk of transgene remobilization caused by external transposase sources that can alter the characteristics of the transgenic organisms lead horizontal transgene transfer to other species. Here we describe a novel, effective method for transgene stabilization based on the introduction of directed double-strand breaks (DSB) into a genome-integrated sequence and their subsequent repair by the single-strand annealing (SSA) pathway. Due to the construct's organization, the repair pathway is predictable, such that all transposon and marker sequences can be deleted, while preserving integration of exogenous DNA in the genome. The exceptional conservation of DNA repair pathways makes this method suitable for a broad range of organisms.
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Affiliation(s)
- Artem Tkachuk
- Group of Telomere Biology, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Maria Kim
- Group of Telomere Biology, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Oksana Kravchuk
- Group of Telomere Biology, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Mikhail Savitsky
- Group of Telomere Biology, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Center for Medical Studies of Oslo University, Moscow, Russia
- * E-mail:
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Marshall JM. The toxin and antidote puzzle: new ways to control insect pest populations through manipulating inheritance. Bioeng Bugs 2011; 2:235-40. [PMID: 21876382 DOI: 10.4161/bbug.2.5.15801] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Insects carry out essential ecological functions, such as pollination, but also cause extensive damage to agricultural crops, and transmit human diseases such as malaria and dengue fever. Advances in insect transgenesis are making it increasingly feasible to engineer genes conferring desirable phenotypes, and gene drive systems are required to spread these genes into wild populations. Medea provides one solution, being able to spread into a population from very low initial frequencies through the action of a maternally-expressed toxin linked to a zygotically-expressed antidote. Several other toxin-antidote combinations are imaginable that distort the offspring ratio in favor of a desired transgene, or drive the population towards an all-male crash. We explore two such systems--Semele, which is capable of spreading a desired transgene into an isolated population in a confined manner; and Merea, which is capable of inducing a local population crash when located on the Z chromosome of a Lepidopteron pest.
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Affiliation(s)
- John M Marshall
- Division of Biology, California Institute of Technology, Pasadena, California, USA.
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Abstract
Cytoplasmic incompatibility induced by inherited intracellular bacteria of arthropods, and Medea elements found in flour beetles, are both forms of postsegregation distortion involving the killing of embryos in order to increase the ratio of progeny that inherit them. The recently described peel-zeel element of Caenorhabditis elegans also uses this mechanism; like Medea the genes responsible are in the nuclear genome but it shares a paternal mode of action with the bacteria. The peel-1 gene has now been shown to encode a potent toxin that is delivered by sperm, and rescued by zygotic transcription of the linked zeel-1. The predominance of self-fertilization in C. elegans has produced an unusual distribution pattern for a selfish genetic element; further population and functional studies will shed light on its evolution. The element might also have potential for use in disease control.
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Ward CM, Su JT, Huang Y, Lloyd AL, Gould F, Hay BA. Medea selfish genetic elements as tools for altering traits of wild populations: a theoretical analysis. Evolution 2010; 65:1149-62. [PMID: 21062278 DOI: 10.1111/j.1558-5646.2010.01186.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
One strategy for controlling transmission of insect-borne disease involves replacing the native insect population with transgenic animals unable to transmit disease. Population replacement requires a drive mechanism to ensure the rapid spread of linked transgenes, the presence of which may result in a fitness cost to carriers. Medea selfish genetic elements have the feature that when present in a female, only offspring that inherit the element survive, a behavior that can lead to spread. Here, we derive equations that describe the conditions under which Medea elements with a fitness cost will spread, and the equilibrium allele frequencies are achieved. Of particular importance, we show that whenever Medea spreads, the non-Medea genotype is driven out of the population, and we estimate the number of generations required to achieve this goal for Medea elements with different fitness costs and male-only introduction frequencies. Finally, we characterize two contexts in which Medea elements with fitness costs drive the non-Medea allele from the population: an autosomal element in which not all Medea-bearing progeny of a Medea-bearing mother survive, and an X-linked element in species in which X/Y individuals are male. Our results suggest that Medea elements can drive population replacement under a wide range of conditions.
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Affiliation(s)
- Catherine M Ward
- Division of Biology, MC156-29, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
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