Positional cloning of a cyromazine resistance gene in Drosophila melanogaster

Abstract

Cyromazine is an effective insecticide used to control dipteran insects. Its precise mode of action is yet to be determined, although it has been suggested that it interferes with the hormone system, sclerotization of the cuticle, or nucleic acid metabolism. To understand the way in which cyromazine acts, we have positionally cloned a cyromazine resistance gene from Drosophila melanogaster. Six cyromazine resistance alleles had previously been generated by ethyl methanasulphonate treatment. Two of these failed to complement each other and here we identify them as having independent non-sense mutations in CG32743, which is an ortholog of Smg1 of worms and mammals and encodes a phosphatidylinositol kinase-like kinase (PIKK). RNAi experiments confirm that cyromazine resistance can be achieved by knocking down CG32743. These are the first cyromazine resistant mutations identified at the nucleotide level. In mammals Smg1 phosphorylates P53 in response to DNA damage. This finding supports the hypothesis that cyromazine interferes with nucleic acid metabolism.

The biology of insecticidal activity and resistance

“…Resistant mutants can be readily mapped to a genomic interval of less than 5Mb using an appropriate selection of visible phenotypic markers (Bogwitz et al, 2005;Chen et al, 2006;Daborn et al, 2001). The location of the gene can be more closely defined using Pelement mapping strategies (Zhai et al, 2003).…”

SMG-8 and SMG-9, two novel subunits of the SMG-1 complex, regulate remodeling of the mRNA surveillance complex during nonsense-mediated mRNA decay

“…Finally, we revealed the biochemical nature of the SMG1C with two regulatory subunits, SMG-8 and SMG-9. In addition to NMD, SMG-1 is involved in genome surveillance, telomere maintenance, the suppression of TNFa-induced apoptosis and hyperoxia-induced p53 activation (Brumbaugh et al 2004;Chen et al 2006;Azzalin et al 2007;Gehen et al 2008;Oliveira et al 2008). Further analysis of the roles of the SMG1C will accelerate the understanding of the mechanism underlying the responses of cells against various stresses.…”

The insect growth regulator insecticide cyromazine causes earlier emergence in Drosophila melanogaster

“…It has been suggested that cyromazine may interfere with nucleotide synthesis (El-Oshar et al, 1985;Binnington et al, 1987;Binnington and Retnakaran, 1991;Bel et al, 2000;Chen et al, 2006). One biological outcome following the peak in 20E The data presented in this study suggest a connection between a cyromazine mode of action and the hormonal control of larval development.…”

“…Cyromazine inhibits growth and development of larval life stages of Diptera. Despite numerous biochemical and some genetic studies, the precise mode of cyromazine action remains undetermined (Miller et al, 1981;Turnbull and Howells, 1982;Bel et al, 2000, Daborn et al, 2000, Chen et al, 2006.…”