201
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Adelman ZN, Pledger D, Myles KM. Developing standard operating procedures for gene drive research in disease vector mosquitoes. Pathog Glob Health 2017; 111:436-447. [PMID: 29350584 PMCID: PMC6066849 DOI: 10.1080/20477724.2018.1424514] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Numerous arthropod species represent potential targets for gene-drive-based population suppression or replacement, including those that transmit diseases, damage crops, or act as deleterious invasive species. Containment measures for gene drive research in arthropods have been discussed in the literature, but the importance of developing safe and effective standard operating procedures (SOPs) for these types of experiments has not been adequately addressed. Concisely written SOPs link safe work practices, containment measures, institutional training, and research-specific protocols. Here we discuss information to be considered by principal investigators, biosafety officers, and institutional biosafety committees as they work together to develop SOPs for experiments involving gene drive in arthropods, and describe various courses of action that can be used to maintain the effectiveness of SOPs through evaluation and revision. The information provided herein will be especially useful to investigators and regulatory personnel who may lack extensive experience working with arthropods under containment conditions.
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Affiliation(s)
- Zach N. Adelman
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - David Pledger
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Kevin M. Myles
- Department of Entomology, Texas A&M University, College Station, TX, USA
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202
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Abstract
Self-propagating gene drive technologies have a number of desirable characteristics that warrant their development for the control of insect pest and vector populations, such as the malaria-transmitting mosquitoes. Theoretically easy to deploy and self-sustaining, these tools may be used to generate cost-effective interventions that benefit society without obvious bias related to wealth, age or education. Their species-specific design offers the potential to reduce environmental risks and aim to be compatible and complementary with other control strategies, potentially expediting the elimination and eradication of malaria. A number of strategies have been proposed for gene-drive based control of the malaria mosquito and recent demonstrations have shown proof-of-principle in the laboratory. Though several technical, ethical and regulatory challenges remain, none appear insurmountable if research continues in a step-wise and open manner.
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Affiliation(s)
| | - Roberto Galizi
- Department of Life Sciences, Imperial College London, London, UK
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203
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Spotlight on CRISPR in Strongyloides Parasitic Nematodes. Trends Parasitol 2017; 34:6-9. [PMID: 29174224 DOI: 10.1016/j.pt.2017.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 11/16/2017] [Indexed: 11/22/2022]
Abstract
Parasitic nematodes are biomedically and economically important, but many are genetically intractable which limits our understanding of their molecular and cellular biology. Gang et al. report CRISPR/Cas9 genome editing in parasites of the genus Strongyloides, generating both knock-outs and knock-ins, and demonstrated heritability of the modifications, a crucial advance in the field.
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204
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Trevisan M, Palù G, Barzon L. Genome editing technologies to fight infectious diseases. Expert Rev Anti Infect Ther 2017; 15:1001-1013. [PMID: 29090592 DOI: 10.1080/14787210.2017.1400379] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Genome editing by programmable nucleases represents a promising tool that could be exploited to develop new therapeutic strategies to fight infectious diseases. These nucleases, such as zinc-finger nucleases, transcription activator-like effector nucleases, clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated protein 9 (Cas9) and homing endonucleases, are molecular scissors that can be targeted at predetermined loci in order to modify the genome sequence of an organism. Areas covered: By perturbing genomic DNA at predetermined loci, programmable nucleases can be used as antiviral and antimicrobial treatment. This approach includes targeting of essential viral genes or viral sequences able, once mutated, to inhibit viral replication; repurposing of CRISPR-Cas9 system for lethal self-targeting of bacteria; targeting antibiotic-resistance and virulence genes in bacteria, fungi, and parasites; engineering arthropod vectors to prevent vector-borne infections. Expert commentary: While progress has been done in demonstrating the feasibility of using genome editing as antimicrobial strategy, there are still many hurdles to overcome, such as the risk of off-target mutations, the raising of escape mutants, and the inefficiency of delivery methods, before translating results from preclinical studies into clinical applications.
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Affiliation(s)
- Marta Trevisan
- a Department of Molecular Medicine , University of Padova , Padova , Italy
| | - Giorgio Palù
- a Department of Molecular Medicine , University of Padova , Padova , Italy
| | - Luisa Barzon
- a Department of Molecular Medicine , University of Padova , Padova , Italy
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205
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Abstract
Interest in developing gene drive systems to control invasive species is growing, with New Zealand reportedly considering the nascent technology as a way to locally eliminate the mammalian pests that threaten its unique flora and fauna. If gene drives successfully eradicated these invasive populations, many would rejoice, but what are the possible consequences? Here, we explore the risk of accidental spread posed by self-propagating gene drive technologies, highlight new gene drive designs that might achieve better outcomes, and explain why we need open and international discussions concerning a technology that could have global ramifications.
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Affiliation(s)
- Kevin M. Esvelt
- MIT Media Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Neil J. Gemmell
- Department of Anatomy, University of Otago, Dunedin, New Zealand
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206
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Dearden PK, Gemmell NJ, Mercier OR, Lester PJ, Scott MJ, Newcomb RD, Buckley TR, Jacobs JME, Goldson SG, Penman DR. The potential for the use of gene drives for pest control in New Zealand: a perspective. J R Soc N Z 2017. [DOI: 10.1080/03036758.2017.1385030] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Peter K. Dearden
- Genomics Aotearoa, Bioprotection Research Centre, and Biochemistry Department, University of Otago, Dunedin, Aotearoa New Zealand
| | - Neil J. Gemmell
- Anatomy Department, University of Otago, Dunedin, Aotearoa New Zealand
| | - Ocean R. Mercier
- Te Kawa a Māui—School of Māori Studies, Victoria University of Wellington, Wellington, Aotearoa New Zealand
| | - Philip J. Lester
- School of Biological Sciences, Victoria University of Wellington, Wellington, Aotearoa New Zealand
| | - Maxwell J. Scott
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, USA
| | - Richard D. Newcomb
- The New Zealand Institute for Plant & Food Research Ltd, Auckland, Aotearoa New Zealand
- School of Biological Sciences, University of Auckland, Auckland, Aotearoa New Zealand
| | - Thomas R. Buckley
- School of Biological Sciences, University of Auckland, Auckland, Aotearoa New Zealand
- Landcare Research Ltd, Auckland, Aotearoa New Zealand
| | - Jeanne M. E. Jacobs
- AgResearch, Lincoln Research Centre, Christchurch, Aotearoa New Zealand
- Bioprotection Research Centre, Lincoln University, Canterbury, Aotearoa New Zealand
| | - Stephen G. Goldson
- Bioprotection Research Centre, Lincoln University, Canterbury, Aotearoa New Zealand
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207
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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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208
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Gene drives do not always increase in frequency: from genetic models to risk assessment. J Verbrauch Lebensm 2017. [DOI: 10.1007/s00003-017-1131-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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209
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Abstract
Driving endonuclease genes (DEGs) spread through a population by a non-Mendelian mechanism. In a heterozygote, the protein encoded by a DEG causes a double-strand break in the homologous chromosome opposite to where its gene is inserted and when the break is repaired using the homologue as a template the DEG heterozygote is converted to a homozygote. Some DEGs occur naturally while several classes of endonucleases can be engineered to spread in this way, with CRISPR-Cas9 based systems being particularly flexible. There is great interest in using driving endonuclease genes to impose a genetic load on insects that vector diseases or are economic pests to reduce their population density, or to introduce a beneficial gene such as one that might interrupt disease transmission. This paper reviews both the population genetics and population dynamics of DEGs. It summarises the theory that guides the design of DEG constructs intended to perform different functions. It also reviews the studies that have explored the likelihood of resistance to DEG phenotypes arising, and how this risk may be reduced. The review is intended for a general audience and mathematical details are kept to a minimum.
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Affiliation(s)
- H Charles J Godfray
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK.
| | - Ace North
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - Austin Burt
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, Berkshire, SL5 7PY, UK
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210
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Vella MR, Gunning CE, Lloyd AL, Gould F. Evaluating strategies for reversing CRISPR-Cas9 gene drives. Sci Rep 2017; 7:11038. [PMID: 28887462 PMCID: PMC5591286 DOI: 10.1038/s41598-017-10633-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/10/2017] [Indexed: 01/17/2023] Open
Abstract
A gene drive biases inheritance of a gene so that it increases in frequency within a population even when the gene confers no fitness benefit. There has been renewed interest in environmental releases of engineered gene drives due to recent proof of principle experiments with the CRISPR-Cas9 system as a drive mechanism. Release of modified organisms, however, is controversial, especially when the drive mechanism could theoretically alter all individuals of a species. Thus, it is desirable to have countermeasures to reverse a drive if a problem arises. Several genetic mechanisms for limiting or eliminating gene drives have been proposed and/or developed, including synthetic resistance, reversal drives, and immunizing reversal drives. While predictions about efficacy of these mechanisms have been optimistic, we lack detailed analyses of their expected dynamics. We develop a discrete time model for population genetics of a drive and proposed genetic countermeasures. Efficacy of drive reversal varies between countermeasures. For some parameter values, the model predicts unexpected behavior including polymorphic equilibria and oscillatory dynamics. The timing and number of released individuals containing a genetic countermeasure can substantially impact outcomes. The choice among countermeasures by researchers and regulators will depend on specific goals and population parameters of target populations.
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Affiliation(s)
- Michael R Vella
- North Carolina State University, Biomathematics Graduate Program, Department of Mathematics, Raleigh, 27695, USA
- North Carolina State University, Genetic Engineering and Society Center, Raleigh, 27695, USA
| | - Christian E Gunning
- North Carolina State University, Department of Entomology and Plant Pathology, Raleigh, 27695, USA
| | - Alun L Lloyd
- North Carolina State University, Biomathematics Graduate Program, Department of Mathematics, Raleigh, 27695, USA
- North Carolina State University, Genetic Engineering and Society Center, Raleigh, 27695, USA
| | - Fred Gould
- North Carolina State University, Genetic Engineering and Society Center, Raleigh, 27695, USA.
- North Carolina State University, Department of Entomology and Plant Pathology, Raleigh, 27695, USA.
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211
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Sun D, Guo Z, Liu Y, Zhang Y. Progress and Prospects of CRISPR/Cas Systems in Insects and Other Arthropods. Front Physiol 2017; 8:608. [PMID: 28932198 PMCID: PMC5592444 DOI: 10.3389/fphys.2017.00608] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/07/2017] [Indexed: 01/03/2023] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR) and the CRISPR-associated gene Cas9 represent an invaluable system for the precise editing of genes in diverse species. The CRISPR/Cas9 system is an adaptive mechanism that enables bacteria and archaeal species to resist invading viruses and phages or plasmids. Compared with zinc finger nucleases and transcription activator-like effector nucleases, the CRISPR/Cas9 system has the advantage of requiring less time and effort. This efficient technology has been used in many species, including diverse arthropods that are relevant to agriculture, forestry, fisheries, and public health; however, there is no review that systematically summarizes its successful application in the editing of both insect and non-insect arthropod genomes. Thus, this paper seeks to provide a comprehensive and impartial overview of the progress of the CRISPR/Cas9 system in different arthropods, reviewing not only fundamental studies related to gene function exploration and experimental optimization but also applied studies in areas such as insect modification and pest control. In addition, we also describe the latest research advances regarding two novel CRISPR/Cas systems (CRISPR/Cpf1 and CRISPR/C2c2) and discuss their future prospects for becoming crucial technologies in arthropods.
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Affiliation(s)
- Dan Sun
- Longping Branch, Graduate School of Hunan UniversityChangsha, China.,Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural SciencesBeijing, China
| | - Zhaojiang Guo
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural SciencesBeijing, China
| | - Yong Liu
- Longping Branch, Graduate School of Hunan UniversityChangsha, China
| | - Youjun Zhang
- Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural SciencesBeijing, China
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212
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Prowse TAA, Cassey P, Ross JV, Pfitzner C, Wittmann TA, Thomas P. Dodging silver bullets: good CRISPR gene-drive design is critical for eradicating exotic vertebrates. Proc Biol Sci 2017; 284:20170799. [PMID: 28794219 PMCID: PMC5563802 DOI: 10.1098/rspb.2017.0799] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/03/2017] [Indexed: 01/08/2023] Open
Abstract
Self-replicating gene drives that can spread deleterious alleles through animal populations have been promoted as a much needed but controversial 'silver bullet' for controlling invasive alien species. Homing-based drives comprise an endonuclease and a guide RNA (gRNA) that are replicated during meiosis via homologous recombination. However, their efficacy for controlling wild populations is threatened by inherent polymorphic resistance and the creation of resistance alleles via non-homologous end-joining (NHEJ)-mediated DNA repair. We used stochastic individual-based models to identify realistic gene-drive strategies capable of eradicating vertebrate pest populations (mice, rats and rabbits) on islands. One popular strategy, a sex-reversing drive that converts heterozygous females into sterile males, failed to spread and required the ongoing deployment of gene-drive carriers to achieve eradication. Under alternative strategies, multiplexed gRNAs could overcome inherent polymorphic resistance and were required for eradication success even when the probability of NHEJ was low. Strategies causing homozygotic embryonic non-viability or homozygotic female sterility produced high probabilities of eradication and were robust to NHEJ-mediated deletion of the DNA sequence between multiplexed endonuclease recognition sites. The latter two strategies also purged the gene drive when eradication failed, therefore posing lower long-term risk should animals escape beyond target islands. Multiplexing gRNAs will be necessary if this technology is to be useful for insular extirpation attempts; however, precise knowledge of homing rates will be required to design low-risk gene drives with high probabilities of eradication success.
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Affiliation(s)
- Thomas A A Prowse
- School of Mathematical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Phillip Cassey
- The Environment Institute and School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Joshua V Ross
- School of Mathematical Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Chandran Pfitzner
- The Environment Institute and School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Talia A Wittmann
- The Environment Institute and School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Paul Thomas
- The Environment Institute and School of Biological Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia
- The Robinson Research Institute, The University of Adelaide, Adelaide, South Australia 5005, Australia
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213
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Desalle R, Amato G. Conservation Genetics, Precision Conservation, and De-extinction. Hastings Cent Rep 2017; 47 Suppl 2:S18-S23. [DOI: 10.1002/hast.747] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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214
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Champer J, Reeves R, Oh SY, Liu C, Liu J, Clark AG, Messer PW. Novel CRISPR/Cas9 gene drive constructs reveal insights into mechanisms of resistance allele formation and drive efficiency in genetically diverse populations. PLoS Genet 2017; 13:e1006796. [PMID: 28727785 PMCID: PMC5518997 DOI: 10.1371/journal.pgen.1006796] [Citation(s) in RCA: 157] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 05/03/2017] [Indexed: 12/17/2022] Open
Abstract
A functioning gene drive system could fundamentally change our strategies for the control of vector-borne diseases by facilitating rapid dissemination of transgenes that prevent pathogen transmission or reduce vector capacity. CRISPR/Cas9 gene drive promises such a mechanism, which works by converting cells that are heterozygous for the drive construct into homozygotes, thereby enabling super-Mendelian inheritance. Although CRISPR gene drive activity has already been demonstrated, a key obstacle for current systems is their propensity to generate resistance alleles, which cannot be converted to drive alleles. In this study, we developed two CRISPR gene drive constructs based on the nanos and vasa promoters that allowed us to illuminate the different mechanisms by which resistance alleles are formed in the model organism Drosophila melanogaster. We observed resistance allele formation at high rates both prior to fertilization in the germline and post-fertilization in the embryo due to maternally deposited Cas9. Assessment of drive activity in genetically diverse backgrounds further revealed substantial differences in conversion efficiency and resistance rates. Our results demonstrate that the evolution of resistance will likely impose a severe limitation to the effectiveness of current CRISPR gene drive approaches, especially when applied to diverse natural populations.
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Affiliation(s)
- Jackson Champer
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America
- * E-mail: (JC); (PWM)
| | - Riona Reeves
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America
| | - Suh Yeon Oh
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America
| | - Chen Liu
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America
| | - Jingxian Liu
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America
| | - Andrew G. Clark
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America
| | - Philipp W. Messer
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, NY, United States of America
- * E-mail: (JC); (PWM)
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215
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Marshall JM, Buchman A, Sánchez C HM, Akbari OS. Overcoming evolved resistance to population-suppressing homing-based gene drives. Sci Rep 2017; 7:3776. [PMID: 28630470 PMCID: PMC5476637 DOI: 10.1038/s41598-017-02744-7] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/18/2017] [Indexed: 12/18/2022] Open
Abstract
The recent development of a CRISPR-Cas9-based homing system for the suppression of Anopheles gambiae is encouraging; however, with current designs, the slow emergence of homing-resistant alleles is expected to result in suppressed populations rapidly rebounding, as homing-resistant alleles have a significant fitness advantage over functional, population-suppressing homing alleles. To explore this concern, we develop a mathematical model to estimate tolerable rates of homing-resistant allele generation to suppress a wild population of a given size. Our results suggest that, to achieve meaningful population suppression, tolerable rates of resistance allele generation are orders of magnitude smaller than those observed for current designs for CRISPR-Cas9-based homing systems. To remedy this, we theoretically explore a homing system architecture in which guide RNAs (gRNAs) are multiplexed, increasing the effective homing rate and decreasing the effective resistant allele generation rate. Modeling results suggest that the size of the population that can be suppressed increases exponentially with the number of multiplexed gRNAs and that, with four multiplexed gRNAs, a mosquito species could potentially be suppressed on a continental scale. We also demonstrate successful proof-of-principle use of multiplexed ribozyme flanked gRNAs to induce mutations in vivo in Drosophila melanogaster - a strategy that could readily be adapted to engineer stable, homing-based drives in relevant organisms.
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Affiliation(s)
- John M Marshall
- Divisions of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA, 94720, USA.
| | - Anna Buchman
- Department of Entomology, Center for Disease Vector Research, and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Héctor M Sánchez C
- Bioinformatics Research Group, School of Medicine, Tecnológico de Monterrey, Estado de México, 52926, México, USA
| | - Omar S Akbari
- Department of Entomology, Center for Disease Vector Research, and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA.
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216
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Ricciardi A, Blackburn TM, Carlton JT, Dick JT, Hulme PE, Iacarella JC, Jeschke JM, Liebhold AM, Lockwood JL, MacIsaac HJ, Pyšek P, Richardson DM, Ruiz GM, Simberloff D, Sutherland WJ, Wardle DA, Aldridge DC. Invasion Science: A Horizon Scan of Emerging Challenges and Opportunities. Trends Ecol Evol 2017; 32:464-474. [DOI: 10.1016/j.tree.2017.03.007] [Citation(s) in RCA: 193] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 03/08/2017] [Accepted: 03/14/2017] [Indexed: 01/03/2023]
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217
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Ritchie SA, Johnson BJ. Advances in Vector Control Science: Rear-and-Release Strategies Show Promise… but Don't Forget the Basics. J Infect Dis 2017; 215:S103-S108. [PMID: 28403439 DOI: 10.1093/infdis/jiw575] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Both chikungunya and Zika viruses have recently swept from Africa across the Pacific to the Americas, causing major outbreaks of disease in humans. In the meantime, dengue epidemics continue throughout the tropics. Traditional vector control programs based on strategies from 1950s and 1960s have been relatively ineffective in combating recent epidemics. In response, new methods involving the rearing and releasing of large numbers of mosquitoes to eliminate or modify local Aedes populations are being developed, with several currently conducting field releases in high-risk countries. These advances, include the release of Wolbachia-infected Aedes aegypti and Aedes albopictus, for either its virus-blocking capabilities, sterilization by cytoplasmic incompatibility, or both; the release of Aedes carrying dominant lethal genes, such as the OX513A strain of A. aegypti; and other emerging techniques, such as advancing gene-drive technologies, are summarized, as well as current stages of development and primary operational and regulatory hurdles. Although these technologies show great promise, none are ready for widespread rollout for cities of millions of people. Thus, efforts should be made to avoid methods such as space sprays that have failed and improve existing technologies to increase their efficacy.
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Affiliation(s)
- Scott A Ritchie
- College of Public Health, Medical and Veterinary Sciences and.,Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland Australia
| | - Brian J Johnson
- College of Public Health, Medical and Veterinary Sciences and.,Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland Australia
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218
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Taning CNT, Van Eynde B, Yu N, Ma S, Smagghe G. CRISPR/Cas9 in insects: Applications, best practices and biosafety concerns. JOURNAL OF INSECT PHYSIOLOGY 2017; 98:245-257. [PMID: 28108316 DOI: 10.1016/j.jinsphys.2017.01.007] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/28/2016] [Accepted: 01/12/2017] [Indexed: 05/13/2023]
Abstract
Discovered as a bacterial adaptive immune system, CRISPR/Cas9 (clustered, regularly interspaced, short palindromic repeat/CRISPR associated) is being developed as an attractive tool in genome editing. Due to its high specificity and applicability, CRISPR/Cas9-mediated gene editing has been employed in a multitude of organisms and cells, including insects, for not only fundamental research such as gene function studies, but also applied research such as modification of organisms of economic importance. Despite the rapid increase in the use of CRISPR in insect genome editing, results still differ from each study, principally due to existing differences in experimental parameters, such as the Cas9 and guide RNA form, the delivery method, the target gene and off-target effects. Here, we review current reports on the successes of CRISPR/Cas9 applications in diverse insects and insect cells. We furthermore summarize several best practices to give a useful checklist of CRISPR/Cas9 experimental setup in insects for beginners. Lastly, we discuss the biosafety concerns related to the release of CRISPR/Cas9-edited insects into the environment.
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Affiliation(s)
- Clauvis Nji Tizi Taning
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium.
| | - Benigna Van Eynde
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium
| | - Na Yu
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Weigang 1, Nanjing 210095, China
| | - Sanyuan Ma
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Guy Smagghe
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium.
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219
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Abstract
CRISPR/Cas9 genome editing technology has taken the research world by storm since its use in eukaryotes was first proposed in 2012. Publications describing advances in technology and new applications have continued at an unrelenting pace since that time. In this Review, we discuss the application of CRISPR/Cas9 for creating gene mutations - the application that initiated the current avalanche of interest - and new developments that have largely answered initial concerns about its specificity and ability to introduce new gene sequences. We discuss the new, diverse and rapidly growing adaptations of the CRISPR/Cas9 technique that enable activation, repression, multiplexing and gene screening. These developments have enabled researchers to create sophisticated tools for dissecting the function and inter-relatedness of genes, as well as noncoding regions of the genome, and to identify gene networks and noncoding regions that promote disease or confer disease susceptibility. These approaches are beginning to be used to interrogate complex and multilayered biological systems and to produce complex animal models of disease. CRISPR/Cas9 technology has enabled the application of new therapeutic approaches to treating disease in animal models, some of which are beginning to be seen in the first human clinical trials. We discuss the direct application of these techniques to rheumatic diseases, which are currently limited but are sure to increase rapidly in the near future.
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Affiliation(s)
- Gary J Gibson
- Henry Ford Hospital, Bone and Joint Center, 6135 Woodward Avenue, Detroit, Michigan 48202, USA
| | - Maozhou Yang
- Henry Ford Hospital, Bone and Joint Center, 6135 Woodward Avenue, Detroit, Michigan 48202, USA
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220
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Gemmell NJ, Tompkins DM. Gene Drives and Rodent Control: Response to Piaggio et al. Trends Ecol Evol 2017; 32:314-315. [PMID: 28359574 DOI: 10.1016/j.tree.2017.03.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 03/07/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Neil J Gemmell
- Department of Anatomy, University of Otago, PO Box 56, Dunedin, New Zealand.
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221
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Affiliation(s)
- Floyd A Reed
- Department of Biology, University of Hawai'i at Mānoa, Honolulu, Hawai'i 96822
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222
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Requirements for Driving Antipathogen Effector Genes into Populations of Disease Vectors by Homing. Genetics 2017; 205:1587-1596. [PMID: 28159753 PMCID: PMC5378115 DOI: 10.1534/genetics.116.197632] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/20/2017] [Indexed: 12/15/2022] Open
Abstract
There is a need for new interventions against the ongoing burden of vector-borne diseases such as malaria and dengue. One suggestion has been to develop genes encoding effector molecules that block parasite development within the vector, and then use the nuclease-based homing reaction as a form of gene drive to spread those genes through target populations. If the effector gene reduces the fitness of the mosquito and does not contribute to the drive, then loss-of-function mutations in the effector will eventually replace functional copies, but protection may nonetheless persist sufficiently long to provide a public health benefit. Here, we present a quantitative model allowing one to predict the duration of protection as a function of the probabilities of different molecular processes during the homing reaction, various fitness effects, and the efficacy of the effector in blocking transmission. Factors that increase the duration of protection include reducing the frequency of pre-existing resistant alleles, the probability of nonrecombinational DNA repair, the probability of homing-associated loss of the effector, the fitness costs of the nuclease and effector, and the completeness of parasite blocking. For target species that extend over an area much larger than the typical dispersal distance, the duration of protection is expected to be highest at the release site, and decrease away from there, eventually falling to zero, as effector-less drive constructs replace effector-containing ones. We also model an alternative strategy of using the nuclease to target an essential gene, and then linking the effector to a sequence that restores the essential function and is resistant to the nuclease. Depending upon parameter values, this approach can prolong the duration of protection. Our models highlight the key design criteria needed to achieve a desired level of public health benefit.
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223
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Unckless RL, Clark AG, Messer PW. Evolution of Resistance Against CRISPR/Cas9 Gene Drive. Genetics 2017; 205:827-841. [PMID: 27941126 PMCID: PMC5289854 DOI: 10.1534/genetics.116.197285] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 12/01/2016] [Indexed: 11/18/2022] Open
Abstract
CRISPR/Cas9 gene drive (CGD) promises to be a highly adaptable approach for spreading genetically engineered alleles throughout a species, even if those alleles impair reproductive success. CGD has been shown to be effective in laboratory crosses of insects, yet it remains unclear to what extent potential resistance mechanisms will affect the dynamics of this process in large natural populations. Here we develop a comprehensive population genetic framework for modeling CGD dynamics, which incorporates potential resistance mechanisms as well as random genetic drift. Using this framework, we calculate the probability that resistance against CGD evolves from standing genetic variation, de novo mutation of wild-type alleles, or cleavage repair by nonhomologous end joining (NHEJ)-a likely by-product of CGD itself. We show that resistance to standard CGD approaches should evolve almost inevitably in most natural populations, unless repair of CGD-induced cleavage via NHEJ can be effectively suppressed, or resistance costs are on par with those of the driver. The key factor determining the probability that resistance evolves is the overall rate at which resistance alleles arise at the population level by mutation or NHEJ. By contrast, the conversion efficiency of the driver, its fitness cost, and its introduction frequency have only minor impact. Our results shed light on strategies that could facilitate the engineering of drivers with lower resistance potential, and motivate the possibility to embrace resistance as a possible mechanism for controlling a CGD approach. This study highlights the need for careful modeling of the population dynamics of CGD prior to the actual release of a driver construct into the wild.
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Affiliation(s)
- Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York 14853
| | - Philipp W Messer
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York 14853
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224
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Piaggio AJ, Segelbacher G, Seddon PJ, Alphey L, Bennett EL, Carlson RH, Friedman RM, Kanavy D, Phelan R, Redford KH, Rosales M, Slobodian L, Wheeler K. Is It Time for Synthetic Biodiversity Conservation? Trends Ecol Evol 2017; 32:97-107. [DOI: 10.1016/j.tree.2016.10.016] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 10/20/2016] [Accepted: 10/27/2016] [Indexed: 12/17/2022]
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225
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Allendorf FW. Genetics and the conservation of natural populations: allozymes to genomes. Mol Ecol 2017; 26:420-430. [DOI: 10.1111/mec.13948] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/28/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Fred W. Allendorf
- Division of Biological Sciences University of Montana Missoula MT 59812 USA
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226
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227
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Dennehy JJ. Evolutionary ecology of virus emergence. Ann N Y Acad Sci 2016; 1389:124-146. [PMID: 28036113 PMCID: PMC7167663 DOI: 10.1111/nyas.13304] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 10/24/2016] [Accepted: 11/09/2016] [Indexed: 12/22/2022]
Abstract
The cross-species transmission of viruses into new host populations, termed virus emergence, is a significant issue in public health, agriculture, wildlife management, and related fields. Virus emergence requires overlap between host populations, alterations in virus genetics to permit infection of new hosts, and adaptation to novel hosts such that between-host transmission is sustainable, all of which are the purview of the fields of ecology and evolution. A firm understanding of the ecology of viruses and how they evolve is required for understanding how and why viruses emerge. In this paper, I address the evolutionary mechanisms of virus emergence and how they relate to virus ecology. I argue that, while virus acquisition of the ability to infect new hosts is not difficult, limited evolutionary trajectories to sustained virus between-host transmission and the combined effects of mutational meltdown, bottlenecking, demographic stochasticity, density dependence, and genetic erosion in ecological sinks limit most emergence events to dead-end spillover infections. Despite the relative rarity of pandemic emerging viruses, the potential of viruses to search evolutionary space and find means to spread epidemically and the consequences of pandemic viruses that do emerge necessitate sustained attention to virus research, surveillance, prophylaxis, and treatment.
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Affiliation(s)
- John J Dennehy
- Biology Department, Queens College of the City University of New York, Queens, New York and The Graduate Center of the City University of New York, New York, New York
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228
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Cao HX, Wang W, Le HTT, Vu GTH. The Power of CRISPR-Cas9-Induced Genome Editing to Speed Up Plant Breeding. Int J Genomics 2016; 2016:5078796. [PMID: 28097123 PMCID: PMC5206445 DOI: 10.1155/2016/5078796] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/17/2016] [Accepted: 11/01/2016] [Indexed: 12/26/2022] Open
Abstract
Genome editing with engineered nucleases enabling site-directed sequence modifications bears a great potential for advanced plant breeding and crop protection. Remarkably, the RNA-guided endonuclease technology (RGEN) based on the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) is an extremely powerful and easy tool that revolutionizes both basic research and plant breeding. Here, we review the major technical advances and recent applications of the CRISPR-Cas9 system for manipulation of model and crop plant genomes. We also discuss the future prospects of this technology in molecular plant breeding.
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Affiliation(s)
- Hieu X. Cao
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, Gatersleben, 06466 Stadt Seeland, Germany
| | - Wenqin Wang
- School of Agriculture and Biology, Shanghai Jiaotong University, 800 Dong Chuan Road, Shanghai 200240, China
| | - Hien T. T. Le
- Institute of Genome Research, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Vietnam
| | - Giang T. H. Vu
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, Gatersleben, 06466 Stadt Seeland, Germany
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229
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Affiliation(s)
- Anna K. Lindholm
- Department of Evolutionary Biology and Environmental Studies, University of
Zurich, Winterthurerstrasse 190, Zurich, Switzerland
| | - Tom A.R. Price
- Institute of Integrative Biology, University of Liverpool, Crown Street,
Liverpool, UK
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230
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Westra ER, Dowling AJ, Broniewski JM, van Houte S. Evolution and Ecology of CRISPR. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2016. [DOI: 10.1146/annurev-ecolsys-121415-032428] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Edze R. Westra
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Andrea J. Dowling
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Jenny M. Broniewski
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
| | - Stineke van Houte
- Environment and Sustainability Institute and Centre for Ecology and Conservation, Biosciences, University of Exeter, Tremough Campus, Penryn TR10 9FE, United Kingdom;
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231
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Fondong VN, Nagalakshmi U, Dinesh-Kumar SP. Novel Functional Genomics Approaches: A Promising Future in the Combat Against Plant Viruses. PHYTOPATHOLOGY 2016; 106:1231-1239. [PMID: 27392181 DOI: 10.1094/phyto-03-16-0145-fi] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Advances in functional genomics and genome editing approaches have provided new opportunities and potential to accelerate plant virus control efforts through modification of host and viral genomes in a precise and predictable manner. Here, we discuss application of RNA-based technologies, including artificial micro RNA, transacting small interfering RNA, and Cas9 (clustered regularly interspaced short palindromic repeat-associated protein 9), which are currently being successfully deployed in generating virus-resistant plants. We further discuss the reverse genetics approach, targeting induced local lesions in genomes (TILLING) and its variant, known as EcoTILLING, that are used in the identification of plant virus recessive resistance gene alleles. In addition to describing specific applications of these technologies in plant virus control, this review discusses their advantages and limitations.
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Affiliation(s)
- Vincent N Fondong
- First author: Department of Biological Sciences, Delaware State University, Dover; second author: Department of Plant Biology, College of Biological Sciences, University of California, Davis; and third author: Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis
| | - Ugrappa Nagalakshmi
- First author: Department of Biological Sciences, Delaware State University, Dover; second author: Department of Plant Biology, College of Biological Sciences, University of California, Davis; and third author: Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis
| | - Savithramma P Dinesh-Kumar
- First author: Department of Biological Sciences, Delaware State University, Dover; second author: Department of Plant Biology, College of Biological Sciences, University of California, Davis; and third author: Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis
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232
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Port F, Bullock SL. Augmenting CRISPR applications in Drosophila with tRNA-flanked sgRNAs. Nat Methods 2016; 13:852-4. [PMID: 27595403 PMCID: PMC5215823 DOI: 10.1038/nmeth.3972] [Citation(s) in RCA: 257] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 08/02/2016] [Indexed: 12/25/2022]
Abstract
We present tRNA-based vectors for producing multiple clustered regularly interspaced short palindromic repeats (CRISPR) single guide RNAs (sgRNAs) from a single RNA polymerase II or III transcript in Drosophila. The system, which is based on liberation of sgRNAs by processing flanking tRNAs, permits highly efficient multiplexing of Cas9-based mutagenesis. We also demonstrate that the tRNA-sgRNA system markedly increases the efficacy of conditional gene disruption by Cas9 and can promote editing by the recently discovered RNA-guided endonuclease Cpf1.
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Affiliation(s)
- Fillip Port
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Simon L Bullock
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
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233
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Perkin LC, Adrianos SL, Oppert B. Gene Disruption Technologies Have the Potential to Transform Stored Product Insect Pest Control. INSECTS 2016; 7:insects7030046. [PMID: 27657138 PMCID: PMC5039559 DOI: 10.3390/insects7030046] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 09/01/2016] [Accepted: 09/09/2016] [Indexed: 12/26/2022]
Abstract
Stored product insects feed on grains and processed commodities manufactured from grain post-harvest, reducing the nutritional value and contaminating food. Currently, the main defense against stored product insect pests is the pesticide fumigant phosphine. Phosphine is highly toxic to all animals, but is the most effective and economical control method, and thus is used extensively worldwide. However, many insect populations have become resistant to phosphine, in some cases to very high levels. New, environmentally benign and more effective control strategies are needed for stored product pests. RNA interference (RNAi) may overcome pesticide resistance by targeting the expression of genes that contribute to resistance in insects. Most data on RNAi in stored product insects is from the coleopteran genetic model, Tribolium castaneum, since it has a strong RNAi response via injection of double stranded RNA (dsRNA) in any life stage. Additionally, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) technology has been suggested as a potential resource for new pest control strategies. In this review we discuss background information on both gene disruption technologies and summarize the advances made in terms of molecular pest management in stored product insects, mainly T. castaneum, as well as complications and future needs.
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Affiliation(s)
- Lindsey C Perkin
- Center for Grain and Animal Health Research, Agricultural Research Service, USDA, 1515 College Avenue, Manhattan, KS 66502, USA.
| | - Sherry L Adrianos
- Center for Grain and Animal Health Research, Agricultural Research Service, USDA, 1515 College Avenue, Manhattan, KS 66502, USA.
| | - Brenda Oppert
- Center for Grain and Animal Health Research, Agricultural Research Service, USDA, 1515 College Avenue, Manhattan, KS 66502, USA.
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234
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Zamanian M, Andersen EC. Prospects and challenges of CRISPR/Cas genome editing for the study and control of neglected vector-borne nematode diseases. FEBS J 2016; 283:3204-21. [PMID: 27300487 PMCID: PMC5053252 DOI: 10.1111/febs.13781] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/05/2016] [Accepted: 06/13/2016] [Indexed: 01/19/2023]
Abstract
Neglected tropical diseases caused by parasitic nematodes inflict an immense health and socioeconomic burden throughout much of the developing world. Current estimates indicate that more than two billion people are infected with nematodes, resulting in the loss of 14 million disability-adjusted life years per annum. Although these parasites cause significant mortality, they primarily cause chronic morbidity through a wide range of severe clinical ailments. Treatment options for nematode infections are restricted to a small number of anthelmintic drugs, and the rapid expansion of anthelmintic mass drug administration raises concerns of drug resistance. Preservation of existing drugs is necessary, as well as the development of new treatment options and methods of control. We focus this review on how the democratization of CRISPR/Cas9 genome editing technology can be enlisted to improve our understanding of the biology of nematode parasites and our ability to treat the infections they cause. We will first explore how this robust method of genome manipulation can be used to newly exploit the powerful model nematode Caenorhabditis elegans for parasitology research. We will then discuss potential avenues to develop CRISPR/Cas9 editing protocols in filarial nematodes. Lastly, we will propose potential ways in which CRISPR/Cas9 can be used to engineer gene drives that target the transmission of mosquito-borne filarial nematodes.
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Affiliation(s)
- Mostafa Zamanian
- Department of Molecular BiosciencesNorthwestern UniversityEvanstonILUSA
| | - Erik C. Andersen
- Department of Molecular BiosciencesNorthwestern UniversityEvanstonILUSA
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235
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microRNA-309 targets the Homeobox gene SIX4 and controls ovarian development in the mosquito Aedes aegypti. Proc Natl Acad Sci U S A 2016; 113:E4828-36. [PMID: 27489347 DOI: 10.1073/pnas.1609792113] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Obligatory blood-triggered reproductive strategy is an evolutionary adaptation of mosquitoes for rapid egg development. It contributes to the vectorial capacity of these insects. Therefore, understanding the molecular mechanisms underlying reproductive processes is of particular importance. Here, we report that microRNA-309 (miR-309) plays a critical role in mosquito reproduction. A spatiotemporal expression profile of miR-309 displayed its blood feeding-dependent onset and ovary-specific manifestation in female Aedes aegypti mosquitoes. Antagomir silencing of miR-309 impaired ovarian development and resulted in nonsynchronized follicle growth. Furthermore, the genetic disruption of miR-309 by CRISPR/Cas9 system led to the developmental failure of primary follicle formation. Examination of genomic responses to miR-309 depletion revealed that several pathways associated with ovarian development are down-regulated. Comparative analysis of genes obtained from the high-throughput RNA sequencing of ovarian tissue from the miR-309 antagomir-silenced mosquitoes with those from the in silico computation target prediction identified that the gene-encoding SIX homeobox 4 protein (SIX4) is a putative target of miR-309. Reporter assay and RNA immunoprecipitation confirmed that SIX4 is a direct target of miR-309. RNA interference of SIX4 was able to rescue phenotypic manifestations caused by miR-309 depletion. Thus, miR-309 plays a critical role in mosquito reproduction by targeting SIX4 in the ovary and serves as a regulatory switch permitting a stage-specific degradation of the ovarian SIX4 mRNA. In turn, this microRNA (miRNA)-targeted degradation is required for appropriate initiation of a blood feeding-triggered phase of ovarian development, highlighting involvement of this miRNA in mosquito reproduction.
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236
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Wolff JN, Tompkins DM, Gemmell NJ, Dowling DK. Mitonuclear interactions, mtDNA-mediated thermal plasticity, and implications for the Trojan Female Technique for pest control. Sci Rep 2016; 6:30016. [PMID: 27443488 PMCID: PMC4956753 DOI: 10.1038/srep30016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/29/2016] [Indexed: 01/27/2023] Open
Abstract
Pest species pose major challenges to global economies, ecosystems, and health. Unfortunately, most conventional approaches to pest control remain costly, and temporary in effect. As such, a heritable variant of the Sterile Insect Technique (SIT) was proposed, based on the introduction of mitochondrial DNA mutations into pest populations, which impair male fertility but have no effects on females. Evidence for this "Trojan Female Technique" (TFT) was recently provided, in the form of a mutation in the mitochondrial cytochrome b gene (mt:Cyt-b) of Drosophila melanogaster which reduces male fertility across diverse nuclear backgrounds. However, recent studies have shown that the magnitude of mitochondrial genetic effects on the phenotype can vary greatly across environments, with mtDNA polymorphisms commonly entwined in genotype-by-environment (G × E) interactions. Here we test whether the male-sterilizing effects previously associated with the mt:Cyt-b mutation are consistent across three thermal and three nuclear genomic contexts. The effects of this mutation were indeed moderated by the nuclear background and thermal environment, but crucially the fertility of males carrying the mutation was invariably reduced relative to controls. This mutation thus constitutes a promising candidate for the further development of the TFT.
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Affiliation(s)
- Jonci N. Wolff
- School of Biological Sciences, Monash University, Victoria, 3800, Australia
| | | | - Neil J. Gemmell
- Allan Wilson Centre for Molecular Ecology and Evolution, Department of Anatomy, University of Otago, Dunedin 9016, New Zealand
| | - Damian K. Dowling
- School of Biological Sciences, Monash University, Victoria, 3800, Australia
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237
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Johnson JA, Altwegg R, Evans DM, Ewen JG, Gordon IJ, Pettorelli N, Young JK. Is there a future for genome-editing technologies in conservation? Anim Conserv 2016. [DOI: 10.1111/acv.12273] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- J. A. Johnson
- Department of Biological Sciences; Institute of Applied Sciences; University of North Texas; Denton TX USA
| | - R. Altwegg
- Statistics in Ecology, Environment and Conservation; Department of Statistical Sciences, and African Climate and Development Initiative; University of Cape Town; Cape Town South Africa
| | - D. M. Evans
- School of Biology; Newcastle University; Newcastle upon Tyne UK
| | - J. G. Ewen
- Institute of Zoology; Zoological Society of London; London UK
| | - I. J. Gordon
- Division of Tropical Environments and Societies; James Cook University; Townsville Australia
| | - N. Pettorelli
- Institute of Zoology; Zoological Society of London; London UK
| | - J. K. Young
- USDA-NWRC-Predator Research Facility; Department of Wildland Resources; Utah State University; Logan UT USA
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238
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Genetically-modified insects to combat vector-borne diseases — curtain rise or fall? Nat Rev Genet 2016; 17:123. [DOI: 10.1038/nrg.2016.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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239
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Reegan AD, Ceasar SA, Paulraj MG, Ignacimuthu S, Al-Dhabi NA. Current status of genome editing in vector mosquitoes: A review. Biosci Trends 2016; 10:424-432. [DOI: 10.5582/bst.2016.01180] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Appadurai Daniel Reegan
- Division of Vector Control, Entomology Research Institute, Loyola College
- Department of Zoology, Madras Christian College
| | | | | | - Savarimuthu Ignacimuthu
- Division of Vector Control, Entomology Research Institute, Loyola College
- Division of Molecular Biology, Entomology Research Institute, Loyola College
- International Scientific Partnership Program, Deanship of Research, King Saud University
| | - Naif Abdullah Al-Dhabi
- Department of Botany and Microbiology, Addiriyah chair for Environmental Studies, College of Science, King Saud University
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