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.
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Procedurally Robust Risk Assessment Framework for Novel Genetically Engineered Organisms and Gene Drives
19376Kuzma, J., Regulation and Governance, 15:1144-1165. 2021-11-29 17:13:52.
In this article, a new framework for improving risk assessments of novel genetically engineered organisms (GEOs) is developed and applied. The Procedurally Robust Risk Assessment Framework (PRRAF) provides a set of principles and criteria for assessing and enhancing risk assessment protocols for GEOs under conditions of high uncertainty. The application of PRRAF is demonstrated using the case of a genetically engineered mosquito designed to kill its wild population and therefore decrease disease transmission. Assessments for regulatory approval of this genetically engineered insect fall short of several PPRAF criteria under the principles of humility, procedural validity, inclusion, anticipation, and reflexivity. With the emergence of GEOs designed to spread in ecosystems, such as those with gene drives, it will become increasingly important for regulatory agencies and technology developers to bolster their risk analysis methods and processes prior to field testing. PRRAF can be used as a flexible guide for doing so within a variety of institutional, regulatory, and governance contexts.
CRISPR-based gene drives for combatting malaria: Need for an early stage technology assessment.
19374Liebert, W., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 17:09:24.
The potential power of CRISPR-based gene drives makes it necessary to engage in science and technology assessment already in early stages of research and development. In order to argue for efforts to address this urgent need, gene drives to combat malaria-transmitting mosquitoes are discussed using the concept of prospective technology assessment. First, development risks are described, followed by considerations about anticipatable risks and irreversible consequences, as well as unforeseeable effects and uncertainties. Afterwards, fundamental problems in connection with the development of gene drives against malaria mosquitoes are raised. Opportunities for shaping technology are briefly discussed, before alternatives, in particular the World Health Organization's elimination strategy, are considered. Finally, several normative questions are put forward.
AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application
19371Hendrichs, J. Pereira, R., Vreysen, M. J. B., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 17:04:54.
The concept of area-wide integrated pest management (AW-IPM), in which the total population of a pest in an area is targeted, is central to the effective control of such populations through the integration of genetic, biological and other pest suppression technologies. Insect movement, occurring sometimes over long distances, is generally underestimated. As a consequence, most conventional pest management is implemented as a localized or field-by-field, un-coordinated action against segments of a pest population, not taking in consideration insect movement, resulting very often in an unsustainable spiral of insecticide application and eventual resistance of the pest against the used insecticides. On the other hand, an AW-IPM approach adopts a preventive rather than a reactive strategy, whereby all individuals of the pest population are targeted in time and space and selecting a time when the pest populations are more vulnerable (e.g. during certain times of the year when the population densities are naturally low), requiring in the longer term fewer inputs and resulting in more cost-effective and sustainable pest management. It involves a coordinated effort over often larger areas, including not only agricultural, but also natural and other areas with pest presence. By addressing these sources of reinfestation in the surroundings of the agricultural areas, satisfactory pest control is achieved in the whole area and fewer control actions are required. This new textbook on AW-IPM assembles a series of selected papers that attempts to address various fundamental components of AW-IPM, e.g. the importance of relevant problem-solving research, the need for essential baseline data, the significance of integrating adequate tools for appropriate control strategies, and the value of pilot trials, etc. Of special interest are the numerous papers on pilot and operational programmes that pay special attention to practical problems encountered during the implementation of insect pest control programmes. A significant number of contributions to this book resulted from oral and poster presentations at the Third FAO/IAEA International Conference on “Area-wide Management of Insect Pests: Integrating the Sterile Insect and Related Nuclear and Other Techniques”, which was successfully held from 22-26 May 2017 at the Vienna International Centre, Vienna, Austria. The conference was attended by 360 delegates from 81 countries and six international organization. However, the book contributions were selected beyond the work presented at the conference and a number of experts dealing mainly with action programmes were invited to present their work in this publication
Synthetic sex ratio distorters based on CRISPR for the control of harmful insect populations
19369Fasulo, B., Meccariello, A., Papathanos, P. A., and Windbichler, N., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:55:38.
Since the overall reproductive output of a population is typically determined by the fertility of its females, which are rate-limiting in gamete production, a successful way to genetically control a population should involve artificially biasing the sex ratio towards males. In male heterogametic species, this could be achieved by the expression of a transgene-encoded endonuclease during spermatogenesis that would target and "shred" the X chromosome at several loci. This would prevent the transmission of X chromosome bearing gametes to the progeny, generating only males. Recent developments in molecular and synthetic biology have provided genome editing tools with great potential to engineer the genome of different species. Given the targeting flexibility of CRISPR-based endonucleases, it may now be possible to test whether X chromosome shredding has the potential to become a universal strategy to genetically control a wide variety of insect pests, of both agricultural and public health relevance.
Combined sterile insect technique and incompatible insect technique: concept, study design, experience and lessons learned from a pilot suppression trial in Thailand
19367Kittayapong, P., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:50:12.
Climate change, rapid global transport and land use change leading to urbanization and agricultural intensification have facilitated disease emergence in vulnerable regions like Southeast Asia, and also the global expansion of vectors and vector-borne diseases into other regions like the Americas and Europe. Important vector-borne diseases, i.e. dengue, chikungunya, yellow fever, and Zika are transmitted by the major mosquito vector species, Aedes aegypti (L.) and Aedes albopictus (Skuse). Management of Ae. aegypti populations in countries endemic to these diseases, especially in Southeast Asia, is not sufficiently effective, resulting in high morbidity and mortality in the region. Insecticide resistance has become an important issue, causing failure in insecticide-based vector control. Innovative or alternative tools/approaches are needed to effectively reduce mosquito vector populations and consequently reduce the diseases they transmit. A trial integrating the environment-friendly Sterile Insect Technique (SIT) and the insect incompatible technique (IIT) was successfully carried out on a small-scale in a semi-rural setting in Thailand. In this chapter, we report on the design and methodology, as well as the experience and lessons learned from the baseline preparation and implementation of the pilot trial.
Barriers and facilitators of area-wide management including sterile insect technique application: The example of Queensland fruit fly
19365Mankad, A., Loechel, B., and Measham, P. F., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:44:16.
The area-wide management (AWM) of highly mobile insect pests such as tephritid fruit flies requires an integrated understanding of technical, social and institutional processes that drive a coordinated approach within a defined area. Furthermore, the success of an AWM programme is dependent upon the coordinated efforts of key stakeholders within the designated area (e.g. growers, community members). Yet, public views regarding AWM may not reflect those views held by scientists or stakeholders. Public considerations for acceptance are likely varied and multidimensional. A series of qualitative (phases 1-2) and quantitative (phase 3) studies examined stakeholder and community attitudes towards AWM to manage Queensland fruit fly Bactrocera tryoni (Froggatt) (Tephritidae) and the novel use of the Sterile Insect Technique (SIT) as a possible component of AWM. Research was conducted over three regions of varying pest prevalence, ranging from zero to endemic; participants included growers, extension officers, industry and government representatives, and members of the general public. Participants in this research were asked to consider potential barriers and facilitators to the widespread uptake of AWM integrating the SIT, including any relevant institutional-level factors. Combined data revealed potential social barriers to AWM and SIT uptake. Most notably, there were perceptions of low efficacy in successfully coordinating key social groups for the purposes of an AW-IPM approach, and a concern for the possibility of 'free-riders' within an areawide system. On the other hand, innovation complexity and observability of outcomes were important factors contributing to acceptance of AWM. Importantly, all participants were influenced by the attitudes and behaviours of important others. Participants also identified key facilitators that could assist in the uptake of AWM using the SIT. These facilitators include the importance of trustworthy information sources and harnessing the persuasive influence of community champions and central packing houses on commercial growers. Overall, there was high stated acceptance for the SIT, both on-farm and in towns, as long as SIT application was found to be economically feasible at individual farm or household level and the community was adequately consulted.
Putting the sterile insect technique into the modern integrated pest management toolbox to control the codling moth in Canada
19363Nelson, C., Esch, E., Kimmie, S., Tesche, M., and Philip, H. Arthur, S., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:38:40.
The Okanagan-Kootenay Sterile Insect Release (OKSIR) programme, in southern British Columbia, Canada, has been successfully applying the Sterile Insect Technique (SIT) as part of a sustainable areawide integrated pest management (AW-IPM) programme to control the codling moth Cydia pomonella L. in pome fruits in the region for over 20 years. Chemical, cultural and biological techniques that complement the SIT are also integrated into orchard and regional pest management plans by the programme and/or individual growers. The AW-IPM programme is supported by close monitoring of codling moth populations in orchards and adjacent urban properties; enforcing suppression of codling moth infestations in orchards and urban areas; removing derelict orchards, wild host trees and poorly managed host trees; and increasing public awareness and education. Successful collaboration between the OKSIR programme, the pome fruit industry, area residents and various government organizations has reduced codling moth populations by 94%, relative to pre-programme levels, and codling moth damage to less than 0.2% of fruit, in more than 90% of the orchards in the programme area. Local pesticide sales indicate a 96% reduction in the amount of active ingredient used against the codling moth since 1991. Implementing the SIT through an innovative social approach to local community-centred area-wide pest management has posed many challenges and created many learning opportunities. The codling moth mass-rearing facility in Osoyoos, British Columbia, has the capacity to produce 780 million sterile codling moths annually, but only a portion of that is used seasonally to treat 3400 hectares (ha) of pome fruit made up of small orchards intermixed with residential areas in the Okanagan Valley. As a result of climate change and increasing global trade, destructive insect pests are migrating to new habitats throughout the world. These new threats must be managed in ways that protect both the agrifood industries and the natural environments in which the industries operate. The OKSIR programme is an effective and easily transferred model to meet these challenges, especially as a supplement to other biological control methods. The programme is also a compelling model of success that can encourage other regions to use the SIT in their pest management toolbox to combat codling moth infestations across multiple local community jurisdictions using environment-friendly, cost-effective methods based on proven technology. The OKSIR programme is exploring the sale of surplus sterile moths, egg sheets or possible virus production as an opportunity to offset costs of incorporating additional area-wide approaches to combat other invasive pests.
Ecology, behaviour and area-wide control of the floodwater mosquito Aedes sticticus, with potential of future integration of the sterile insect technique
19361Lundstrom, J. O. Schafer, M. L. Kittayapong, P., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:33:24.
The strategy of aerial control of the floodwater mosquito Aedes sticticus (Meigen) in the floodplains of River Dalalven, central Sweden, was developed to directly address specific larval breeding areas in temporary flooded wet meadows and swamps. Using the Bti-based larvicide VectoBac G (R), a very strong reduction of larval abundance is achieved, resulting in a massive decrease of blood-seeking females that could otherwise spread from the wetlands to feast on blood from humans and animals within 5 km or more from the larval biotopes. However, there is also a political demand to reduce the usage of the control agent through hypothetical alternatives, such as cattle grazing and mowing of the meadows, as well as hydrological changes of the River Dalalven. An evaluation of these measures showed that they are either insufficient or unrealistic in reducing floodwater mosquito abundance. Thus, we searched for other potential population suppression methods. Using the criteria of efficacy, environmental neutrality and compatibility within an integrated suppression approach, we conclude that Sterile Insect Technique (SIT) and the Incompatibility Insect Technique (IIT) would qualify for a pilot-scale test of their feasibility for the integrated control of the floodwater mosquito Ae. sticticus. The SIT and the IIT are similar strategies involving the release of sterile males which mate with local fertile females and result in infertile eggs. Prerequisites for a sterile male strategy to control Ae. sticticus include: a laboratory colony of the species, a facility for mass-rearing of mosquitoes, the sterilisation of males, a transport strategy, a dispersal system, assay systems for several life stages, and a method capable of reducing the population of this superabundant species before commencing the sterile male release. One factor in favour of implementing the SIT or IIT against Ae. sticticus is that mating occurs in or near well-defined larval breeding areas with specific relation to flood events. Another factor in favour of the SIT or the IIT is the availability of existing methods to measure gender, larvae and egg abundance. Also, existing Bti-treatments can substantially lower the population size before sterile male release. Other prerequisites, like the successful colonization of Ae. sticticus will require more tests and adaptations of existing mosquito rearing protocols. A pilot study is suggested for an isolated study area, protected from reinvasion by Ae. sticticus-females and included in routine Bti-treatments.
Area-wide management of mediterranean fruit fly with the sterile insect technique in South Africa: New production and management techniques pay dividends
19358Venter, J. H., Baard, C. W. L., and Barnes, B. N., AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 16:27:01.
A mass-rearing facility to produce sterile male Mediterranean fruit flies, Ceratitis capitata (Wiedemann), for a Sterile Insect Technique (SIT) programme in the Hex River Valley in the Western Cape Province started in the late 1990s. The programme was initially underfunded and could only produce about 5 million sterile male flies per week. The resultant aerial release rate of 500 sterile males/ha/week reduced wild Mediterranean fruit fly populations substantially, but not to sufficiently low levels. Due to financial considerations, in 2003 aerial releases were replaced with ground releases targeting all gardens, other hotspots and neglected host plants. It was clear that with more funding, fruit fly mass-rearing facility and field operations could be improved, better quality control could be implemented, and more and better quality male sterile flies could be produced and released. Increased government support in 2001 resulted in a larger mass-rearing facility, and further improvements included the implementation of a quality control management system and the introduction of a new genetic sexing strain (VIENNA 8). The resultant increase in the production of sterile Mediterranean fruit flies of better quality enabled the SIT programme to be systematically introduced to additional fruit production areas. The Mediterranean fruit fly SIT programme was privatised in 2003 and is now operated by FruitFly Africa (Pty) Ltd. In 2009 a new approach to funding was adopted with a renewable Memorandum of Understanding (MoU) between the Department of Agriculture, Forestry and Fisheries (DAFF) and the deciduous fruit and table grape industry. Under the MoU, the DAFF provides 50% of the necessary funding, while 50% is collected from growers through statutory levies. In 2010 a new state of the art mass-rearing facility became operational and subsequent improvements in production processes and facility maintenance resulted in improved fruit fly production and quality. By 2016 sterile male production had increased to 56 million flies per week. After 12 years of ground releases of sterile Mediterranean fruit flies, aerial releases were resumed in three main production areas, and, at the time of writing, include approximately 15 000 ha of commercial deciduous fruit and table grapes. As a result of this well-funded area-wide integrated pest management (AW-IPM) programme, average wild Mediterranean fruit fly populations in the SIT areas have decreased by as much as 73%. The South African Mediterranean fruit fly SIT programme now aims to manage some of the fruit production areas as areas of low pest prevalence. Increased funding and a stable income stream also enabled FruitFly Africa to apply early detection and rapid response programmes for invasive pests such as Bactrocera dorsalis in relevant areas.
The suppression of the False Codling Moth in South Africa using an AW-IPM approach with a SIT component
25890N. Boersma, AREA-WIDE INTEGRATED PEST MANAGEMENT: Development and Field Application, 2021-11-29 10:26:27.
The false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is native to subSaharan Africa, where it infests various commercial, and wild, fruit-bearing plants. This major pest is not present in the Americas, Europe, and Asia, and therefore has phytosanitary implications, which impose severe limitations on potential South African exports. Consequently, this pest represents a severe threat to the fruit industry of South Africa, in terms of socio-economic impacts on both fruit production and job security. Although the pest can be managed to some extent with insecticides, mating disruption, and orchard sanitation, a long-term environment-friendly solution was needed. This became more evident as T. leucotreta developed resistance to available insecticides, while stricter quarantine measures were enforced by importers of African citrus. In 2002, research commenced on an area-wide integrated pest management (AW-IPM) programme in conjunction with the development of the Sterile Insect Technique (SIT) for the false codling moth. Commercial sterile insect releases started in the 2007-2008 season over 1500 ha of citrus orchards in Citrusdal, Western Cape Province, but by 2017-2018 had gradually expanded to almost 19 000 ha in three different citrus producing regions of South Africa. The programme is currently owned by the Citrus Growers Association (CGA) that have contributed to the steady growth of the SIT programme in the citrus industry. Over the past ten years the status of T. leucotreta as a pest threat was systematically reduced in areas where the SIT was practiced on an area-wide basis, compared to non-release areas.
Wolbachia cifB induces cytoplasmic incompatibility in the malaria mosquito vector
19439K. L. Adams, D. G. Abernathy, B. C. Willett, E. K. Selland, M. A. Itoe and F. Catteruccia, Nature Microbiology, 6:1575-1582. 2021-11-26 20:50:59.
Wolbachia, a maternally inherited intracellular bacterial species, can manipulate host insect reproduction by cytoplasmic incompatibility (CI), which results in embryo lethality in crosses between infected males and uninfected females. CI is encoded by two prophage genes, cifA and cifB. Wolbachia, coupled with the sterile insect technique, has been used in field trials to control populations of the dengue vector Aedes albopictus, but CI-inducing strains are not known to infect the malaria vector Anopheles gambiae. Here we show that cifA and cifB can induce conditional sterility in the malaria vector An. gambiae. We used transgenic expression of these Wolbachia-derived genes in the An. gambiae germline to show that cifB is sufficient to cause embryonic lethality and that cifB-induced sterility is rescued by cifA expression in females. When we co-expressed cifA and cifB in male mosquitoes, the CI phenotype was attenuated. In female mosquitoes, cifB impaired fertility, which was overcome by co-expression of cifA. Our findings pave the way towards using CI to control malaria mosquito vectors.
Wolbachia reduces virus infection in a natural population of Drosophila
19437R. Cogni, S. D. Ding, A. C. Pimentel, J. P. Day and F. M. Jiggins, Communications Biology, 4:1327. 2021-11-25 20:42:30.
Wolbachia is a maternally transmitted bacterial symbiont that is estimated to infect approximately half of arthropod species. In the laboratory it can increase the resistance of insects to viral infection, but its effect on viruses in nature is unknown. Here we report that in a natural population of Drosophila melanogaster, individuals that are infected with Wolbachia are less likely to be infected by viruses. By characterising the virome by metagenomic sequencing and then testing individual flies for infection, we found the protective effect of Wolbachia was virus-specific, with the prevalence of infection being up to 15% greater in Wolbachia-free flies. The antiviral effects of Wolbachia may contribute to its extraordinary ecological success, and in nature the symbiont may be an important component of the antiviral defences of insects.
Propagation of seminal toxins through binary expression gene drives can suppress polyandrous populations
19953J. Hurtado, S. Revale and L. M. Matzkin, bioRxiv, 2021.11.23.469777. 2021-11-24 09:48:59.
Gene drives can be highly effective in controlling a target population by disrupting a female fertility gene. To spread across a population, these drives require that disrupted alleles be largely recessive so as not to impose too high of a fitness penalty. We argue that this restriction may be relaxed by using a double gene drive design to spread a split binary expression system. One drive carries a dominant lethal/toxic effector alone and the other a transactivator factor, without which the effector will not act. Only after the drives reach sufficiently high frequencies would individuals have the chance to inherit both system components and the effector be expressed. We explore through mathematical modeling the potential of this design to spread dominant lethal/toxic alleles and suppress populations. We show that this system could be implemented to spread engineered seminal proteins designed to kill females, making it highly effective against polyandrous populations.Competing Interest StatementThe authors have declared no competing interest.
Tubulin post-translational modifications in meiosis
19433T. Akera, Seminars in Cell & Developmental Biology, 2021-11-23 20:29:32.
Haploid gametes are produced from diploid parents through meiosis, a process inherent to all sexually reproducing eukaryotes. Faithful chromosome segregation in meiosis is essential for reproductive success, although it is less clear how the meiotic spindle achieves this compared to the mitotic spindle. It is becoming increasingly clear that tubulin post-translational modifications (PTMs) play critical roles in regulating microtubule functions in many biological processes, and meiosis is no exception. Here, I review recent advances in the understanding of tubulin PTMs in meiotic spindles, especially focusing on their roles in spindle integrity, oocyte aging, and non-Mendelian transmission.
Evaluation of Transgenic Aedes aegypti L. Strain in India: A Friendly Mosquito
19979P. B. Patil, K. K. Yadav, S. K. Dasgupta, U. B. Zehr, S. R. Barwale and B. Char, Genetically Modified and other Innovative Vector Control Technologies, 2021-11-21 11:56:31.
Aedes aegypti L. is a primary vector of dengue and is also responsible for transmission of other arboviral diseases including chikungunya, yellow fever, and Zika virus worldwide. India is attributed with as much as 34% of the global burden of dengue infection as per the recent reports. It is generally acknowledged controlling the vector population in the environment is the key to effectively curb the transmission of vector-borne diseases. Existing conventional methods for controlling the vector populations are not alone sufficient for reducing populations below disease transmission thresholds and would need integration of innovative strategies. With the advancement in modern biotechnology, scientists have been trying to explore the use of genetically engineered insects for their potential use in area-wide method for vector control. One among such strains being widely tested is OX513A Ae. aegypti strain termed as Friendly™ mosquitoes, a genetically engineered strain with a repressible dominant homozygous lethal gene construct and DsRed2 fluorescent marker gene. Male adults of OX513A strain are intended to suppress the wild population of Ae. aegypti in the released environment by population suppression strategy. The lethal gene renders mating events between OX513A males and wild-type females unsuccessful by passing a copy of gene to all the progeny of mated female adults leading to the death of the progeny during development stages in the absence of repressor antidote tetracycline. This OX513A strain was reviewed and recommended for carefully planned pilot deployment and randomized control trials with epidemiological outcomes to build evidence for routine programmatic use against Ae. aegypti-borne diseases by World Health Organization’s Vector Control Advisory Group in the year 2016. The strain is being tested globally in different countries including India for its efficacy and has been deregulated in Brazil for its use in vector control program. This chapter reviews our research investigations conducted on transgenic OX513A Ae. aegypti strain and its potential for use in dengue vector control in India.
Containment Strategies for Synthetic Gene Drive Organisms and Impacts on Gene Flow
L. Pei and M. Schmidt, GENE FLOW: Monitoring, Modeling and Mitigation, 2021-11-19 10:22:14.Gene drives, particularly synthetic gene drives, may help to address some important challenges, by efficiently altering specific sections of DNA in entire populations of wild organisms. Here we review the current development of the synthetic gene drives, especially those RNA-guided synthetic gene drives based on the CRISPR nuclease Cas. Particular focuses are on their possible applications in agriculture (e.g. disease resistance, weed control management), ecosystem conservation (e.g. evasion species control), health (e.g. to combat insect-borne and fungal infections), and for basic research in model organisms (e.g. Saccharomyces, fruit fly, and zebra fish). The physical, chemical, biological, and ecological containment strategies that might help to confine these gene drive-modified organisms are then explored. The gene flow issues, those from gene drive-derived organisms to the environment, are discussed, while possible mitigation strategies for gene drive research are explored. Last but not least, the regulatory context and opinions from key stakeholders (regulators, scientists, and concerned organizations) are reviewed, aiming to provide a more comprehensive overview of the field.
Historical perspective and new avenues to control the myiasis-causing fly Cochliomyia hominivorax in Uruguay.
23386Fresia P, Pimentel S, Iriarte V, Marques L, Durán V, Saravia A, Novas R, Basika T, Ferenczi A, Castells D, Saporiti T, Cuore U, Losiewicz S, Fernández F, Ciappesoni G, Dalla-Rizza M and M. A., Agrociencia Uruguay, 25:e974. 2021-11-18 07:43:36.
Mosca de la bichera’ or simply ‘bichera’ are common names given in Uruguay and the region to the primary myiasis-causing species Cochliomyia hominivorax, the New World Screwworm (NWS) fly (Diptera: Calliphoridae). Myiasis happens when dipteran larvae infest live animals at least during some developmental phase to feed on host’s flesh and fluids. For the NWS fly it is mandatory that all three larvae phases develop on living tissues of warm-blooded vertebrates, including humans. Unsurprisingly, this parasitic behavior causes great profit losses to the livestock industry and is also considered a neglected public health issue. NWS is endemic from the tropics and subtropics of the Americas, but has been eradicated from North and Central America through a Sterile Insect Technique (SIT) based Area Wide – Integrated Pest Management (AW-IPM) program that lasted more than 50 years
A Household-Based Survey to Understand Factors Influencing Awareness, Attitudes and Knowledge towards Wolbachia-Aedes Technology
19435L. T. Soh, Z. Ong, K. Vasquez, I. Chen, X. Li, W. Niah, C. Panchapakesan, A. Sheldenkar, S. Sim, L. C. Ng and M. O. Lwin, International Journal of Environmental Research and Public Health, 18. 2021-11-15 20:37:00.
In 2016, Singapore introduced the release of male Wolbachia-Aedes mosquitoes to complement vector control efforts and suppress Aedes aegypti mosquitoes in selected study sites. With ongoing expansion of Project Wolbachia-Singapore to cover larger areas, a household-based survey was conducted between July 2019 to February 2020 in two Project Wolbachia study sites using a structured questionnaire, to evaluate current sentiments and assess the need for enhanced public messaging and engagement. The association of factors that influence awareness, attitudes, and knowledge towards the use of Wolbachia-Aedes technology was analysed using Pearson's Chi-square test and binary logistic regression. Of 500 respondents, 74.8% were aware of Project Wolbachia-Singapore. Comparatively, the level of knowledge on Wolbachia-Aedes technology was lower, suggesting knowledge gaps that require enhanced communication and messaging to address misinformation. Longer exposure to the project predicted greater awareness, whereas higher education levels predicted higher knowledge levels. Younger age groups and higher education levels were associated with high acceptance towards the project. High levels of trust and acceptance towards the project were also observed across the population. The public's positive perception of the project is a testament to the effective public communication undertaken to date and will facilitate programme expansion.
High-resolution in situ analysis of Cas9 germline transcript distributions in gene-drive Anopheles mosquitoes
19324G. Terradas, A. Hermann, A. A. James, W. McGinnis and E. Bier, G3-Genes Genomes Genetics, 2021-11-15 14:20:36.
Gene drives are programmable genetic elements that can spread beneficial traits into wild populations to aid in vector-borne pathogen control. Two different drives have been developed for population modification of mosquito vectors. The Reckh drive (vasa-Cas9) in Anopheles stephensi displays efficient allelic conversion through males but generates frequent drive-resistant mutant alleles when passed through females. In contrast, the AgNosCd-1 drive (nos-Cas9) in Anopheles gambiae achieves almost complete allelic conversion through both genders. Here, we examined the subcellular localization of RNA transcripts in the mosquito germline. In both transgenic lines, Cas9 is strictly coexpressed with endogenous genes in stem and premeiotic cells of the testes, where both drives display highly efficient conversion. However, we observed distinct colocalization patterns for the two drives in female reproductive tissues. These studies suggest potential determinants underlying efficient drive through the female germline. We also evaluated expression patterns of alternative germline genes for future gene-drive designs.
Transmission distortion and genetic incompatibilities between alleles in a multigenerational mouse advanced intercross line
19320D. Arends, S. Kärst, S. Heise, P. Korkuc, D. Hesse and G. A. Brockmann, Genetics, 2021-11-15 14:07:56.
While direct additive and dominance effects on complex traits have been mapped repeatedly, additional genetic factors contributing to the heterogeneity of complex traits have been scarcely investigated. To assess genetic background effects, we investigated transmission ratio distortions (TRDs) of alleles from parent to offspring using an advanced intercross line (AIL) of an initial cross between the mouse inbred strains C57BL/6NCrl (B6N) and BFMI860-12 (BFMI). 341 males of generation 28 and their respective 61 parents and 66 grandparents were genotyped using Mega Mouse Universal Genotyping Arrays (MegaMUGA). TRDs were investigated using allele transmission asymmetry tests, and pathway overrepresentation analysis was performed. Sequencing data was used to test for overrepresentation of non-synonymous SNPs in TRD regions. Genetic incompatibilities were tested using the Bateson-Dobzhansky-Muller two-locus model. 62 TRD regions were detected, many in close proximity to the telocentric centromere. TRD regions contained 44.5% more non-synonymous SNPs than randomly selected regions (182 vs. 125.9 ± 17.0, P < 1x10-4). Testing for genetic incompatibilities between TRD regions identified 29 genome-wide significant incompatibilities between TRD regions (P(BF) < 0.05). Pathway overrepresentation analysis of genes in TRD regions showed that DNA methylation, epigenetic regulation of RNA, and meiotic/meiosis regulation pathways were affected independent of the parental origin of the TRD. Paternal BFMI TRD regions showed overrepresentation in the small interfering RNA (siRNA) biogenesis and in the metabolism of lipids and lipoproteins. Maternal B6N TRD regions harbored genes involved in meiotic recombination, cell death, and apoptosis pathways. The analysis of genes in TRD regions suggests the potential distortion of protein-protein interactions influencing obesity and diabetic retinopathy as a result of disadvantageous combinations of allelic variants in Aass, Pgx6 and Nme8. Using an AIL significantly improves the resolution at which we can investigate TRD. Our analysis implicates distortion of protein-protein interactions as well as meiotic drive as the underlying mechanisms leading to the observed TRD in our AIL. Furthermore, genes with large amounts of non-synonymous SNPs located in TRD regions are more likely to be involved in pathways that are related to the phenotypic differences between the parental strains. Genes in these TRD regions provide new targets for investigating genetic adaptation, protein-protein interactions, and determinants of complex traits such as obesity.
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