Oxitec (United Kingdom)

Le projet de réforme de l’enseignement de Jean Zay en 1937 institutionnalise la notion d’orientation en France, avec l’instauration des classes d’orientation dès le primaire et la création d’un centre d’orientation professionnelle dans chaque département. Son objectif est de prolonger la scolarité des élèves de l’enseignement primaire dans des filières professionnelles sachant que jusqu’alors, 85 % d’une génération quittait l’école à 12 ans (Dhume & alii, 2011). Ainsi, dès son origine, l’orie...

This paper presents findings from a combined theoretical and computational thermal analysis of alternative heat removal concepts for an open-frame PM machine. The analysed machine design has been developed for propulsion of an unmanned aerial vehicle (UAV), which operates in a regime characterised by a high torque overload (×2.5) at take-off and a high efficiency (+95%) at high-altitude cruise operation. The thermal management of such a machine has a significant impact when balancing the design for a lightweight/compact solution. Here, direct air-cooling of the machine is analysed by focussing on the winding body that is the dominant heat source during the UAV's take-off phase. As the airflow into the machine body is generated by the forward motion of the UAV, a careful consideration needs to be taken when guiding the air through the machine body. In this analysis, alternative airflow channelling via the stator-winding assembly is investigated. The results suggest that the proposed motor design with reduced conductor slot utilisation and stator bore airflow guiding feature allows for achieving the required convection heat transfer coefficient (75W/m2K at 1m/s), which is 150% improvement as compared with a more conventional design with a good conductor slot utilisation. However, the reduced conductor volume needs to be compensated for by appropriately adjusting the machine outer diameter and profile during the initial design sizing exercise.

Previous genetic pest management (GPM) systems in diamondback moth (DBM) have relied on expressing lethal proteins ('effectors') that are 'cell-autonomous', that is, they do not leave the cell in which they are expressed. To increase the flexibility of future GPM systems in DBM, we aimed to assess the use of a non-cell-autonomous, invertebrate-specific, neurotoxic effector - the scorpion toxin AaHIT. This AaHIT effector was designed to be secreted by expressing cells, potentially leading to effects on distant cells, specifically neuromuscular junctions. Expression of AaHIT caused a 'shaking/quivering' phenotype that could be repressed by provision of an antidote (tetracycline): a phenotype consistent with the AaHIT mode-of-action. This effect was more pronounced when AaHIT expression was driven by the Hr5/ie1 promoter (82.44% of males, 65.14% of females) rather than Op/ie2 (57.35% of males, 48.39% of females). Contrary to expectations, the shaking phenotype and observed fitness costs were limited to adults in which they caused severe reductions in mean longevity (-81%) and median female fecundity (-93%). Quantitative polymerase chain reactions of AaHIT expression patterns and analysis of piggyBac-mediated transgene insertion sites suggest that restriction of the observed effects to the adult stages may be due to the influence of the local genomic environment on the tetO-AaHIT transgene. We demonstrated the feasibility of using non-cell-autonomous effectors within a GPM context for the first time in Lepidoptera, one of the most economically damaging orders of insects. These findings provide a framework for extending this system to other pest Lepidoptera and to other secreted effectors. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bactrocera oleae (Diptera: Tephritidae) remains a major pest of olive fruit production worldwide. Current pest management programs largely depend on chemical insecticides, resulting in high economic and environmental costs. Alternative pest control approaches are therefore highly desirable. We have created a conditional female-specific self-limiting strain of B. oleae (OX3097D-Bol) that could be applied for sustainable pest control. OX3097D-Bol olive fly carries a fluorescent marker (DsRed2) for identification and a self-limiting genetic trait that is repressed by tetracycline. In the absence of tetracycline, the tetracycline transactivator (tTAV) accumulates, resulting in female death at larvae and early pupal stages. The aim of this study was to evaluate the impact of genetically engineered OX3097D-Bol olive fly on three non-target organisms that either predate or parasitize olive flies, one from the guild of parasitoids (Psyttalia concolor) and two from the guild of predators (Pardosa spider species and the rove beetle Aleochara bilineata). No significant negative effect was observed on life history parameters, mortality and reproductive capacity of the non-target organisms studied. These results suggest that potential exposure to DsRed2 and tTAV gene products (e.g. mRNA and encoded proteins) would have a negligible impact on on-target organisms in the guilds or predators and parasitoids.

Aedes aegypti is the principal vector of several important arboviruses. Among the methods of vector control to limit transmission of disease are genetic strategies that involve the release of sterile or genetically modified non-biting males (Alphey 2014), which has generated interest in manipulating mosquito sex ratios (Gilles et al. 2014; Adelman and Tu 2016). Sex determination in Ae. aegypti is controlled by a non-recombining Y chromosome-like region called the M locus (Craig et al. 1960), yet characterisation of this locus has been thwarted by the repetitive nature of the genome (Hall et al. 2015). In 2015, an M locus gene named Nix was identified that displays the qualities of a sex determination switch (Hall et al. 2015). With the use of a whole-genome BAC library, we amplified and sequenced a ~200kb region containing this male-determining gene. In this study, we show that Nix is comprised of two exons separated by a 99kb intron, making it an unusually large gene. The intron sequence is highly repetitive and exhibits features in common with old Y chromosomes, and we speculate that the lack of recombination at the M locus has allowed the expansion of repeats in a manner characteristic of a sex-limited chromosome, in accordance with proposed models of sex chromosome evolution in insects.

The insertion of exogenous genetic cargo into insects using transposable elements is a powerful research tool with potential applications in meeting food security and public health challenges facing humanity. piggyBac is the transposable element most commonly utilized for insect germline transformation. The described efficiency of this process is variable in the published literature, and a comprehensive review of transformation efficiency in insects is lacking. This study compared and contrasted all available published data with a comprehensive data set provided by a biotechnology group specializing in insect transformation. Based on analysis of these data, with particular focus on the more complete observational data from the biotechnology group, we designed a decision tool to aid researchers' decision‐making when using piggyBac to transform insects by microinjection. A combination of statistical techniques was used to define appropriate summary statistics of piggyBac transformation efficiency by species and insect order. Publication bias was assessed by comparing the data sets. The bias was assessed using strategies co‐opted from the medical literature. The work culminated in building the Goldilocks decision tool, a Markov‐Chain Monte‐Carlo simulation operated via a graphical interface and providing guidance on best practice for those seeking to transform insects using piggyBac.

BACKGROUNDOX513A is a genetically engineered strain of Aedes aegypti carrying a repressible, dominantly inherited transgene that confers lethality in immature heterozygous progeny. Released male OX513A adults have proven to be effective for the localised suppression of wild Ae. aegypti, highlighting its potential in vector control. Mating and life-table assessments were used to compare OX513A with reared Ae. aegypti strains collected from New Delhi and Aurangabad regions in India.RESULTSMating proportions of New Delhi females versus males of OX513A or New Delhi strains were 0.52 and 0.48 respectively, indicating no discrimination by females against either strain, and males of both strains were equally competitive. Developmental time from first instar to adult emergence was significantly longer for OX513A (10.7 ± 0.04 days) than for New Delhi (9.4 ± 0.04 days) and Aurangabad strains (9.1 ± 0.04 days). Differences in mean longevities, female reproductive parameters and population growth parameters between the strains were non-significant.CONCLUSIONSThe laboratory study demonstrates that only minor life-table variations of limited biological relevance exist between OX513A and Indian Ae. aegypti populations, and males had equal potential for mating competitiveness. Thus, results support the OX513A strain as a suitable candidate for continued evaluation towards sustainable management of Ae. aegypti populations in India. © 2014 Gangabishan Bhikulal Investment and Trading Limited. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Abstract This chapter focuses on sterile insect technique (SIT) improvement through the use of conditional dominant lethal genes, which can be used for sterilization and/or sex separation. When these conditional lethal genes are transgenes, i.e. constructed using recombinant DNA methods with at least some exogenous DNA, they are invariably associated with heritable markers. The application of sterile-male method as part of an integrated pest management system and its role in resistance management are described. Field experiences with genetically engineered plant insect pests and mosquitoes are mentioned. The potential of conditional lethal systems as the basis for genetic control of a wide range of pest insects is shown. This is driven partly by the inherently attractive properties of sterile-male methods in terms of effectiveness and low environmental impact, and partly by the potential for genetics-based improvements to classical SIT available through modern methods, especially genetic engineering.

Culex quinquefasciatus mosquitoes have been successfully genetically modified only once, despite the efforts of several laboratories to transform and establish a stable strain. We have developed a transient gene expression method, in Culex, that delivers plasmid DNA directly to the mosquito haemolymph and additional tissues. We were able to express DsRed2 fluorescent protein in adult Cx. quinquefasciatus mosquitoes by injecting plasmids directly into their thorax. The expression of DsRed2 in adult Cx. quinquefasciatus mosquitoes is an important stepping stone to genetic transformation and the potential use of new control strategies and genetic interactions.