| Abstract No.: | A-B1057 |
| Country: | Canada |
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| Title: | THE CHARACTERIZATION OF THREE NOVEL LIGAND GATED ION CHANNEL SUBUNITS – POTENTIAL PESTICIDE TARGETS?
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| Authors/Affiliations: | 1 Daniel Feingold*; 1 Joseph Dent;
1 McGill University, Department of Biology, Montreal, QC, Canada
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| Content: | Cys-loop ligand gated ion channels (Cys-loop LGIC) are pentameric neurotransmitter receptors that are ubiquitous in both vertebrate and invertebrate nervous systems. Their large diversity as well as their central role in mediating rapid synaptic transmission has made these channels attractive molecular targets for a number of pesticides. Despite the widespread use of such pesticides, issues regarding drug specificity and resistance continue to pose serious problems in regions that depend on pesticides for crop protection and prevention against disease. These concerns underscore the pressing need for the development of effective pesticides that pose minimal risk to non-target species and the environment.
Objectives: The goal of our study is to identify a molecular target for a novel class of pesticides that will be safe for non-target animals and have low environmental impact. We are characterizing three novel Cys- loop LGIC subunits - CG7589 and CG6927 and CG11340 – in the Drosophila melanogaster. These genes are of particular interest because they exhibit little homology among invertebrate species and do not possess any orthologs in vertebrate systems (Dent 2006). Consequently, pesticides that target channels formed by these genes are predicted to be safe and have low risk for cross-resistance with current pesticides.
Materials and Methods: In order to determine whether CG7589, CG6927 and CG11340 would be suitable pesticide targets, it is important to understand the functional role of these ion channel subunits in vivo. We generated deletions in our genes of interest via P-element excision mutagenesis in order to identify the impact of channel dysfunction on the overall fitness of the fly. Any mutant phenotype that negatively impacts fly viability and/or fertility would validate these channel subunits as putative pesticide targets. Expression profiles of these channel subunits will be established using reporter gene constructs that fuse the regulatory sites of our genes of interest to GFP. In addition, in situ hybridization experiments will be conducted in order to further characterize the tissue specific expression patterns of these genes. Lastly, electrophysiological experiments will serve to characterize the gating properties of the channels formed by these genes.
Results: We have successfully generated flies with deletions exclusively in CG7589 and CG6927. Preliminary evidence suggests that mutations in CG7589 are semi-lethal. Based on microarray studies, it has been determined that CG7589 is expressed in the midgut and tubules of adult flies, while CG6927 is expressed in the ovaries (see Flybase). We are currently exploring mutant phenotypes associated with these respective tissues.
Conclusion: Based on sequence homology of our genes of interest along with the potential semi-lethal phenotype associated with deletions exclusive to CG7589, these uncharacterized ion channel subunits may provide a promising molecular target for the development of a novel class of highly selective and efficient pesticides.
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