Scholarly Literature

This is a database of scholarly literature that concentrates currently on natural and engineered selfish genetic elements (gene drives).  The latest are shown here.
Disclaimer>

Gene conversion generates evolutionary novelty that fuels genetic conflicts

3905
Daugherty, MDZ, Sarah E.,  Current Opinion in Genetics & Development,  58-59:49-54. 2019-01-03 00:00:00.
Genetic conflicts arise when the evolutionary interests of two genetic elements are not aligned. Conflicts between genomes (e.g. pathogen versus host) or within the same genome (e.g. internal parasitic DNA sequences versus the rest of the host genome) can both foster ‘molecular arms races’, in which genes on both sides of the conflict rapidly evolve due to bouts of adaptation and counter-adaptation. Importantly, a source of genetic novelty is needed to fuel these arms races. In this review, we highlight gene conversion as a major force in generating the novel alleles on which selection can act. Using examples from both intergenomic and intragenomic conflicts, we feature the mechanisms by which gene conversion facilitates the rapid evolution of genes in conflict.

Informed consent and community engagement in open field research: lessons for gene drive science

3945
Singh, JA,  BMC Medical Ethics,  20:54. 2019-01-03 00:00:00.
The development of the CRISPR/Cas9 gene editing system has generated new possibilities for the use of gene drive constructs to reduce or suppress mosquito populations to levels that do not support disease transmission. Despite this prospect, social resistance to genetically modified organisms remains high. Gene drive open field research thus raises important questions regarding what is owed to those who may not consent to such research, or those could be affected by the proposed research, but whose consent is not solicited. The precise circumstances under which informed consent must be obtained, and from whom, requires careful consideration. Furthermore, appropriate engagement processes should be central to any introduction of genetically modified mosquitos in proposed target settings.

Next-generation CRISPR-based gene drive supports genetic editing with selective precision

3885
Anonymous,  International Sugar Journal,  121:411-412. 2019-01-03 00:00:00.
New CRISPR-based gene drives and broader active genetics technologies are revolutionizing the way scientists engineer the transfer of specific traits from one generation to another.

Two minutes to midnight-what international law can do about genome editing

3925
Lee, TL,  Asian Journal of Wto & International Health Law and Policy,  14:227-265. 2019-01-03 00:00:00.
With its ability to transform the ecosystem, gene drives, a powerful genome-editing technology, poses nuanced regulatory challenges. In particular, as gene drives can override the normal rule of inheritance, where the impacts of gene-drive modified organisms on the environment could be irreversible, leading to a permanent population change. Moreover, as these gene-drive modified organisms are designed to spread to large populations, they can also penetrate national and geographic borders, with global implications. Insofar as gene drive applications could be both potentially beneficial as well as hazardous to the world, this article seeks to explore ways in which international law could provide a useful platform to engage the relevant stakeholders in general, and encourage responsible science in specific.

Alternative strategies for mosquito-borne arbovirus control

3884
Achee, NLG, J. P.; Vatandoost, H.; Seixas, G.; Pinto, J.; Ching-Ng, L.; Martins, A. J.; Juntarajumnong, W.; Corbel, V.; Gouagna, C.; David, J. P.; Logan, J. G.; Orsborne, J.; Marois, E.; Devine, G. J.; Vontas, J.,  PLOS Neglected Tropical Diseases,  13:e0006822. 2019-01-02 00:00:00.
Mosquito-borne virusessuch as Zika, chikungunya, dengue fever, and yellow fever, among othersare of global importance. Although vaccine development for prevention of mosquito-borne arbovirus infections has been a focus, mitigation strategies continue to rely on vector control. However, vector control has failed to prevent recent epidemics and arrest expanding geographic distribution of key arboviruses, such as dengue. As a consequence, there has been increasing necessity to further optimize current strategies within integrated approaches and advance development of alternative, innovative strategies for the control of mosquito-borne arboviruses. Methods and findings This review, intended as a general overview, is one of a series being generated by the Worldwide Insecticide resistance Network (WIN). The alternative strategies discussed reflect those that are currently under evaluation for public health value by the World Health Organization (WHO) and represent strategies of focus by globally recognized public health stakeholders as potential insecticide resistance (IR)-mitigating strategies. Conditions where these alternative strategies could offer greatest public health value in consideration of mitigating IR will be dependent on the anticipated mechanism of action. Arguably, the most pressing need for endorsement of the strategies described here will be the epidemiological evidence of a public health impact. Conclusions As the burden of mosquito-borne arboviruses, predominately those transmitted by Aedes aegypti and A. albopictus, continues to grow at a global scale, new vector-control tools and integrated strategies will be required to meet public health demands. Decisions regarding implementation of alternative strategies will depend on key ecoepidemiological parameters that each is intended to optimally impact toward driving down arbovirus transmission. Author summary International public health workers are challenged by the burden of arthropod-borne viral diseases, to include mosquito-borne arboviruses transmitted by Aedes aegypti and A. albopictus due in part to lack of sustainable vector control and insecticide resistance (IR), as well as the inability to scale up and sustain existing interventions for prevention of urban epidemics. As a consequence, there has been increasing interest to advance the development of alternative methods. This review provides a general overview of alternative vector-control strategies under development for the control of arbovirus mosquito vectors and highlights how each could offer innovative public health value. Considerations to regulations, acceptance, and sustainability are also provided.

Biocontrol in Australia: Can a carp herpesvirus (CyHV-3) deliver safe and effective ecological restoration?

3924
Kopf, RKB, M.; Finlayson, C. M.; Hodges, K.; Humphries, P.; King, A.; Kingsford, R. T.; Marshall, J.; McGinness, H. M.; Thresher, R.; Vanderplasschen, A.,  Biological Invasions,  21:1857-1870. 2019-01-02 00:00:00.
The Australian Government is considering Cyprinid herpesvirus 3 (CyHV-3) for biocontrol of invasive common carp (Cyprinus carpio L.). We review the evidence-base for its potential ecological risks, benefits and effectiveness. Lower carp abundance may boost native fish biomass and improve water clarity, but there is little evidence available to suggest that the virus, alone or used in combination with other methods, can deliver effective or safe biocontrol. Further, the virus may already be present in Australia. Overseas, the virus has caused sporadic and localized mortalities of carp in lakes and rivers, but has generally had no long-term measurable effect on wild carp or native fish populations. The temperature range of disease (18-28 degrees C), unknown co-factors causing outbreaks, and predictable re-colonization and recruitment boom of immune and virus-resistant carp, following a biocontrol release, remain formidable and unmitigated barriers to success. CyHV-3 infection trials on Australian biota have unexplained high mortality rates of recreationally-important and threatened fishes, and the role of asymptomatic carriers remains uncertain. Finally, Australia has national and international obligations to ensure that there are no perverse outcomes from biocontrol actions. Despite political pressure, there is no environmental justification to rush the release of this virus. To achieve the Government goals of restoring native biodiversity we advocate that key uncertainties, risks and efficacy barriers first need to be addressed. It is only then that viral biocontrol could be considered a viable tool to complement broader ecological restoration strategies for Australia's waterways.

Evaluating the Probability of CRISPR-based Gene Drive Contaminating Another Species

3904
Courtier-Orgogozo, VD, Antoine; Gouyon, Pierre-Henri; Boëte, Christophe,  bioRxiv,  776609:27. 2019-01-02 00:00:00.
The probability D that a given CRISPR-based gene drive element contaminates another, non-target species can be estimated by the following Drive Risk Assessment Quantitative Estimate (DRAQUE) Equation: D = (hyb+transf).express.cut.flank.immune.nonextinct withhyb = probability of hybridization between the target species and a non-target speciestransf = probability of horizontal transfer of a piece of DNA containing the gene drive cassette from the target species to a non-target species (with no hybridization)express = probability that the Cas9 and guide RNA genes are expressedcut = probability that the CRISPR-guide RNA recognizes and cuts at a DNA site in the new hostflank = probability that the gene drive cassette inserts at the cut siteimmune = probability that the immune system does not reject Cas9-expressing cellsnonextinct = probability of invasion of the drive within the population We discuss and estimate each of the seven parameters of the equation, with particular emphasis on possible transfers within insects, and between rodents and humans. We conclude from current data that the probability of a gene drive cassette to contaminate another species is not insignificant. We propose strategies to reduce this risk and call for more work on estimating all the parameters of the formula.CRISPRClustered Regularly Interspaced Short Palindromic RepeatsDRAQUEDrive Risk Assessment Quantitative EstimateHGThorizontal gene transferHTThorizontal transfer of transposable elementTEtransposable element

Two-By-One model of cytoplasmic incompatibility: Synthetic recapitulation by transgenic expression of cifA and cifB in Drosophila

3944
Shropshire, JDB, S. R.,  PLOS Genetics,  15:e1008221. 2019-01-02 00:00:00.
Wolbachia are maternally inherited bacteria that infect arthropod species worldwide and are deployed in vector control to curb arboviral spread using cytoplasmic incompatibility (CI). CI kills embryos when an infected male mates with an uninfected female, but the lethality is rescued if the female and her embryos are likewise infected. Two phage WO genes, cifA(wMel) and cifB(wMel) from the wMel Wolbachia deployed in vector control, transgenically recapitulate variably penetrant CI, and one of the same genes, cifA(wMel), rescues wild type CI. The proposed Two-by-One genetic model predicts that CI and rescue can be recapitulated by transgenic expression alone and that dual cifA(wMel) and cifB(wMel) expression can recapitulate strong CI. Here, we use hatch rate and gene expression analyses in transgenic Drosophila melanogaster to demonstrate that CI and rescue can be synthetically recapitulated in full, and strong, transgenic CI comparable to wild type CI is achievable. These data explicitly validate the Two-by-One model in wMel-infected D. melanogaster, establish a robust system for transgenic studies of CI in a model system, and represent the first case of completely engineering male and female animal reproduction to depend upon bacteriophage gene products. Author summary Releases of Wolbachia-infected mosquitos are underway worldwide because Wolbachia block replication of Zika and Dengue viruses and spread themselves maternally through arthropod populations via cytoplasmic incompatibility (CI). The CI drive system depends on a Wolbachia-induced sperm modification that results in embryonic lethality when an infected male mates with an uninfected female, but this lethality is rescued when the female and her embryos are likewise infected. We recently reported that the phage WO genes, cifA and cifB, cause the sperm modification and cifA rescues the embryonic lethality caused by the wMel Wolbachia strain deployed in vector control. These reports motivated proposal of the Two-by-One model of CI whereby two genes cause lethality and one gene rescues it. Here we provide unequivocal support for the model in the Wolbachia strain used in vector control via synthetic methods that recapitulate CI and rescue in the absence of a Wolbachia infections. Our results reveal the set of phage WO genes responsible for this powerful genetic drive system, act as a proof-of-concept that these genes alone can induce gene drive like crossing patterns, and establish methodologies and hypotheses for future studies of CI in Drosophila. We discuss the implications of the Two-by-One model towards functional mechanisms of CI, the emergence of incompatibility between Wolbachia strains, vector control applications, and CI gene nomenclature.

An introduction to the proceedings of the environmental release of engineered pests: Building an international governance framewor

5646
Brown, Z. S., L. Carter and F. Gould,  BMC Proceedings,  12:10. 2018-12-17 17:44:54.
In October 2016, a two-day meeting of 65 academic, government and industry professionals was held at North Carolina State University for early-stage discussions about the international governance of gene drives: potentially powerful new technologies that can be used for the control of pests, invasive species and disease vectors. Presenters at the meeting prepared seven manuscripts elaborating on the ideas raised. This BMC Proceedings issue presents the collection of these peer-reviewed manuscripts.

Towards inclusive social appraisal: risk, participation and democracy in governance of synthetic biology

5642
Stirling, A., K. R. Hayes and J. Delborne,  BMC Proceedings,  12:15. 2018-12-17 17:05:25.
Frameworks that govern the development and application of novel products, such as the products of synthetic biology, should involve all those who are interested or potentially affected by the products. The governance arrangements for novel products should also provide a democratic mechanism that allows affected parties to express their opinions on the direction that innovation does or does not take. In this paper we examine rationales, obstacles and opportunities for public participation in governance of novel synthetic biology products. Our analysis addresses issues such as uncertainties, the considering of alternative innovations, and broader social and environmental implications. The crucial issues in play go beyond safety alone, to include contending social values around diverse notions of benefit and harm. The paper highlights the need for more inclusive social appraisal mechanisms to inform governance of Synthetic Biology and alternative products, and discusses a few practical methods to help achieve this goal.

Public engagement pathways for emerging GM insect technologies

5640
Burgess, M. M., J. D. Mumford and J. V. Lavery,  BMC Proceedings,  12(Suppl 8):12. 2018-12-17 17:02:52.
Policy and management related to the release of organisms generated by emerging biotechnologies for pest management should be informed through public engagement. Regulatory decisions can be conceptually distinguished into the development of frameworks, the assessment of the release of a specific modified organism, and implementation decisions such as location and timing. Although these decisions are often intertwined in practice, the negotiation takes place at different stages of technology development and suggests different roles for public engagement. Some approaches to public engagement are more appropriate for different purposes and situations, and it is not always obvious how to go about matching the approach to the purpose. In addition to the diverse technologies involved in generating modified organisms, there are diverse publics with particular interests and different kinds of knowledge. Institutional interests range from commercial development to public regulation and future uptake. Contextual features, such as agency mandates, may limit or structure the extent and approach to public engagement. Different convening groups (government agencies, public interest groups, academics, businesses) and the kind of decision that is being considered determine what kind of input is needed and how the engaging groups will be constituted. This paper considers how the context of the release of genetically modified insects for pest control requires expanding approaches to the design of the public engagement.

GM insect pests under the Brazilian regulatory framework: development and perspectives

5638
Andrade, P. P., M. A. da Silva Ferreira, M. S. Muniz and A. de Casto Lira-Neto,  BMC Proceedings,  12:15. 2018-12-17 17:00:23.
The emergence of new technologies for genetic modification has broadened the range of possible new products. The regulations of many countries that could benefit from these new products may not be prepared to assess risks and enable science-based decision-making. This is especially acute in the case of genetically modified insects with potential use in public health and agriculture. Modifications of the regulatory framework, sometimes necessary to allow a proper risk assessment of products from new technologies, are strongly influenced by political decisions derived from the balance of power and interest among stakeholders. This article discusses the genesis of the Brazilian regulatory framework, its applicability for the risk assessment of genetically modified insects and the scenarios that have shaped the two biosafety laws that established the basis for the use of modern biotechnology in the country. It is concluded that, for the adoption of the new technologies, it is important to carefully navigate the political tensions by seeking the engagement and empowerment of stakeholders supporting science-based decision-making in order to gather the necessary support for adoption of risk assessment as the basis for final decisions, allowing the use of new technologies.

Regulation of emerging gene technologies in India

5636
Ahuja, V.,  BMC Proceedings,  12:14. 2018-12-17 16:57:35.
In India, genetically modified organisms (GMOs) and the products thereof are regulated under the “Rules for the manufacture, use, import, export & storage of hazardous microorganisms, genetically engineered organisms or cells, 1989” (referred to as Rules, 1989) notified under the Environment (Protection) Act, 1986. These Rules are implemented by the Ministry of Environment, Forest and Climate Change, Department of Biotechnology and State Governments though six competent authorities. The Rules, 1989 are supported by series of guidelines on contained research, biologics, confined field trials, food safety assessment, environmental risk assessment etc.

Gene drive research: Why it matters

The Royal Society,  Royal Society Statement,  2018-11-18 19:59:59.
Gene drives are systems that bias the inheritance of a particular DNA sequence. Many such systems occur naturally and scientists are now investigating the potential to develop new ones using synthetic biology techniques. Synthetic gene drives are being developed for a range of purposes that would benefit humanity, but it is not possible at this stage to know whether the benefits outweigh the risks. Further research will help to reduce uncertainties and characterise potential risks and benefits. It is important that any research that does proceed is appropriately governed and combined with public debate. The Royal Society therefore recommends that the UN Convention on Biological Diversity avoid the adoption of any position that would support an international moratorium on gene drive research, including experimental field trials.

Ecological effects on underdominance threshold drives for vector control

16267
D. Khamis, C. El Mouden, K. Kura and M. B. Bonsall,  Journal of Theoretical Biology,  456:1-15. 2018-11-07 16:39:27.
Here, ecological and epidemiological dynamics are coupled to a model of mosquito genetics to investigate theoretically the impact of different types of underdominance gene drive on disease prevalence. We model systems with two engineered alleles carried either on the same pair of chromosomes at the same locus or homozygously on different pairs at different loci, genetic lethality that affects both sexes or only females, and bi-sex or male-only releases.

Population Consequences of Releasing Sex-Reversed Fish: Applications and Concerns

11500
C. Wederkind,  Sex Control in Aquaculture,  Chp 8:179-188. 2018-11-02 20:38:44.
Sex differentiation is generally more labile in gonochoristic fish than it is, for example, in birds and mammals. Environmentally induced sex reversal is, therefore, often possible, and creates genotype‐phenotype mismatches that can be useful in population management. Interestingly, sex chromosomes of fish are typically not significantly decayed (i.e., all types of offspring of sex‐reversed individuals may be viable, including YY and WW individuals that can then often be sex reversed again). Releasing sex‐reversed fish, or releasing untreated YY and WW offspring of sex‐reversed fish, into natural populations can, therefore, affect the sex ratio of the population in the following generations and, hence, affect population growth.

Sex Control in Aquaculture: Concept to Practice

11497
H.P. Wang and Z.G. Shen,  Sex Control in Aquaculture,  2018-11-02 20:26:50.
Understanding sex determining (SD) mechanisms and related concepts in a wide range of fish species is critical for sex control and large‐scale monosex production in aquaculture, in which monosex culture is superior to mixed‐sex culture. Establishment of phenotypic sex is triggered by SD factor(s), modulated by complex molecular networks, and influenced by environmental conditions, steroid hormones, and endocrine disrupting chemicals. Temperature‐dependent sex determination (TSD) presents in fish, and the feature has been applied to monosex production in several fish species, since many downstream aspects of TSD are shared with genotypic sex determination (GSD). Although SD genes have been identified in some fish, the complex molecular networks involved in sex differentiation remain unclear. Large‐scale monosex production could be achieved in the third generation with sex‐linked markers (SLMs), and in the fourth generation with no available SLMs in fish with a XY or ZW SD mode. There is a great potential for producing large‐scale breeding systems for females in much less time if gynogenesis and sex reversal of XX‐females are combined. In addition, atypical genotypes (YY and WW) have the potential to serve as a biological tools to control invasive species in natural waters. In this chapter, we briefly review the concepts and practices of sex control in fish and aquaculture, based on the achievements during the past two decades.

Yes we can! Exciting progress and prospects for controlling invasives on islands and beyond

7964
D. Simberloff, B. Keitt, D. Will, N. Holmes, E. Pickett and P. Genovesi,  Western North American Naturalist,  78:942-958. 2018-10-22 14:34:34.
Eradication and maintenance management of island invasive species have long histories, and incremental improvements of existing technologies plus occasional novel approaches have led to more challenging targets and increased success rates in certain categories. Many nonnative mammals have been eradicated from islands, as have several nonnative birds, insects, and plants. Hundreds of rat populations have been eliminated, with a success rate over 80%, and islands over 10,000 ha are now feasible targets. Mouse eradication has proven more challenging, but aerial broadcast of anticoagulant toxins has led to increased success. Carnivore eradication-especially of feral housecats and foxes-has been frequently attempted with a recent success rate over 90%. Eradication of herbivores-primarily goats, rabbits, wild boar, and boar/pig hybrids-has been attempted almost 200 times, with a success rate over 90%. Trends in mammal eradication include more frequent attempts and higher success rates on larger islands and inhabited islands, as well as attempts targeting multiple invasive species. Documented conservation gains from island mammal eradications are numerous. For insects, about two-thirds of some 50 island attempts have succeeded, and most targeted agricultural pests. No summary statistics exist on island plant eradications, but several small infestations have been eradicated. Several insect and plant island invaders have been maintained at low densities by biological control, and plants have been controlled short of eradication by herbicides, often combined with physical or mechanical means. Failures in both eradication and maintenance management on islands often result from insufficient long-term commitment of resources. Excitement and controversy abound over the prospect that new techniques relying on molecular genetic tools-especially RNA-guided gene drives-may permit eradication or maintenance management of nonnative invaders in situations that have previously appeared extremely difficult or infeasible. Island populations of invertebrates, small mammals, and some plants are particularly propitious targets.

Multiple loci of small effect confer wide variability in efficiency and resistance rate of CRISPR gene drive

11267
J. Champer, Z. Wen, A. Luthra, R. Reeves, J. Chung, C. Liu, Y. L. Lee, J. Liu, E. Yang, P. W. Messer and A. G. Clark,  bioRxiv,  447615. 2018-10-19 19:06:27.
Gene drives could allow for control of vector-borne diseases by directly suppressing vector populations or spreading genetic payloads designed to reduce pathogen transmission. CRISPR homing gene drives work by cleaving wild-type alleles, which are then converted to drive alleles by homology-directed repair, increasing the frequency of the drive in a population. However, resistance alleles can form when end-joining repair takes place in lieu of homology-directed repair. Such alleles cannot be converted to drive alleles, which would halt the spread of a drive through a population. To investigate the effects of natural genetic variation on resistance formation, we developed a CRISPR homing gene drive in Drosophila melanogaster and crossed it into the genetically diverse Drosophila Genetic Reference Panel (DGRP) lines, measuring several performance parameters. Most strikingly, resistance allele formation post-fertilization in the early embryo ranged from 7% to 79% among lines and averaged 42±18%. We performed a Genome-Wide Association Study (GWAS) using our results in the DGRP lines and found that the resistance and conversion rates were polygenic, with several genetic polymorphisms showing relatively weak association. RNAi knockdown of several of these genes confirmed their effect, but their small effect sizes implies that their manipulation will yield only modest improvements to the efficacy of gene drives.

Invasion Success and Management Strategies for Social Vespula Wasps

13740
P. J. Lester and J. R. Beggs,  Annual Review of Entomology,  64:51-71. 2018-09-26 19:38:03.
Three species of Vespula have become invasive in Australia, Hawai'i, New Zealand, and North and South America and continue to spread. Economically, their main negative effect is associated with pollination and the apicultural industry. Climate change is likely to exacerbate their impacts in many regions. Although investigated extensively, no effective biological control agents have yet been found. Emerging technologies such as gene drives are under consideration.

« First ‹ Previous 1 72 80 81 82 83 84 92 118 Next › Last »