Development and use of a piggyBac-based jumpstarter system in Drosophila suzukii

Expansion of the genetic toolbox for manipulation of the global crop pest Drosophila suzukii: Isolation and assessment of eye colour mutant strains

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), commonly called spotted wing Drosophila, is an important agricultural pest recognised worldwide. D. suzukii is a pest of soft-skinned fruits as females can lay eggs in ripening fruit before harvest. While strains for genetic biocontrol of D. suzukii have been made, the development of transgenic D. suzukii strains and their further screening remain a challenge partly due to the lack of phenotypically trackable genetic-markers, such as those widely used with the model genetic organism D. melanogaster. Here, we have used CRISPR/Cas9 to introduce heritable mutations in the eye colour genes white, cinnabar and sepia, which are located on the X, second and third chromosomes, respectively. Strains were obtained, which were homozygous for a single mutation. Genotyping of the established strains showed insertion and/or deletions (indels) at the targeted sites. A strain homozygous for mutations in cinnabar and sepia showed a pale-yellow eye colour at eclosion but darkened to a sepia colour after a week. The fecundity and fertility of some of the cinnabar and sepia strains were comparable with the wild type. Although white mutant males were previously reported to be sterile, we found that sterility is not fully penetrant and we have been able to maintain white-eyed strains for over a year. The cinnabar, sepia and white mutant strains developed in this study should facilitate future genetic studies in D. suzukii and the development of strains for genetic control of this pest.

Evaluation of Additional Drosophila suzukii Male-Only Strains Generated Through Remobilization of an FL19 Transgene

Drosophila suzukii (D. suzukii) (Matsumura, 1931; Diptera: Drosophilidae), also known as spotted wing Drosophila, is a worldwide pest of fruits with soft skins such as blueberries and cherries. Originally from Asia, D. suzukii is now present in the Americas and Europe and has become a significant economic pest. Growers largely rely on insecticides for the control of D. suzukii. Genetic strategies offer a species-specific environmentally friendly way for suppression of D. suzukii populations. We previously developed a transgenic strain of D. suzukii that produced only males on a diet that did not contain tetracycline. The strain carried a single copy of the FL19 construct on chromosome 3. Repeated releases of an excess of FL19 males led to suppression of D. suzukii populations in laboratory cage trials. Females died as a consequence of overexpression of the tetracycline transactivator (tTA) and tTA-activated expression of the head involution defective proapoptotic gene. The aim of this study was to generate additional male-only strains that carried two copies of the FL19 transgene through crossing the original line with a piggyBac jumpstarter strain. Males that carried either two chromosome 3 or a singleX-linked transgene were identified through stronger expression of the red fluorescent protein marker gene. The brighter fluorescence of the X-linked lines was likely due to dosage compensation of the red fluorescent protein gene. In total, four X-linked lines and eleven lines with two copies on chromosome 3 were obtained, of which five were further examined. All but one of the strains produced only males on a diet without tetracycline. When crossed with wild type virgin females, all of the five two copy autosomal strains examined produced only males. However, the single copy X-linked lines did not show dominant female lethality. Five of the autosomal lines were further evaluated for productivity (egg to adult) and male competition. Based on these results, the most promising lines have been selected for future population suppression experiments with strains from different geographical locations.

A conditional female lethal system for genetic suppression of the global fruit crop pest Drosophila suzukii

BACKGROUND

Drosophila suzukii (Matsumura, 1931, Diptera: Drosophilidae) is a global pest of soft-skinned fruits such as blueberries, cherries and raspberries. Also known as spotted-wing drosophila, D. suzukii is native to Asia but is now widely distributed in the Americas and Europe, and presents a serious challenge for growers. Genetic control strategies offer an environmentally friendly approach for the control of D. suzukii.

RESULTS

In this study, we developed transgenic strains of D. suzukii that carry dominant conditional female lethal transgenes. When raised in the absence of tetracycline, female D. suzukii die. We show that repeated releases of an excess of transgenic males can suppress D. suzukii populations in laboratory cage trials.

CONCLUSION

Our data suggest that the transgenic strain could provide an effective approach for control of this invasive pest of soft-skinned fruits.

Genetically Encoded CRISPR Components Yield Efficient Gene Editing in the Invasive Pest Drosophila suzukii

Originally from Asia, Drosophila suzukii Matsumura is a global pest of economically important soft-skinned fruits. Also commonly known as spotted wing drosophila, it is largely controlled through repeated applications of broad-spectrum insecticides by which resistance has been observed in the field. There is a pressing need for a better understanding of D. suzukii biology and for developing alternative environmentally friendly methods of control. The RNA-guided Cas9 nuclease has revolutionized functional genomics and is an integral component of several recently developed genetic strategies for population control of insects. Here, we describe genetically modified strains that encode three different terminators and four different promoters to express Cas9 robustly in both the soma and/or germline of D. suzukii. The Cas9 strains were rigorously evaluated through genetic crossing to transgenic strains that encode single-guide RNAs targeting the conserved X-linked yellow body and white eye genes. We find that several Cas9/gRNA strains display remarkably high editing capacity. Going forward, these tools will be instrumental for evaluating gene function in D. suzukii and may even provide tools useful for the development of new genetic strategies for control of this invasive species.

Novel application of adipose-derived mesenchymal stem cells via producing antiangiogenic factor TSP-1 in lung metastatic melanoma animal model

Human adipose tissue derived mesenchymal stem cells (hAD-MSC_S) with suppressive immunogenicity, homing to injury, inflammatory, and cancer sites can be suitable for gene therapy. PiggyBac (PB) is a type of transposon vector applied in mammalian systems and could overcome some limitations of other transposon and viral vectors. In this study, the therapeutic potential hAD-MSCs expressing thrombospondin-1 (TSP-1) is assessed through tail vein injection in C57BL/6 models bearing melanoma mice. Twenty days after injection, antiangiogenic effects and number of activated T. cells are assessed by Immunohistochemistry (IHC) method. Apoptosis value is analyzed by tunnel assay. Mice survival and numbers of nodules in mice lungs also are assessed. By western blotting, value of TSP-1, Bax and Bcl2 expression are assessed. The result revealed that hAD-MSCs_.TSP-1 can inhibit angiogenesis and induce apoptosis and activated T. cells in a significant manner in C57BL/6 mice models bearing melanoma. Survival also significantly increased and number of nodules decreased, value of Bax and TSP-1 expression increased and value of Bcl2 expression decreased. In conclusion, our result showed that hAD-MSC. TSP-1 can be applied as an effective delivery vehicle in lung metastatic melanoma therapy.