The Mechanisms Underlying α-Amanitin Resistance in Drosophila melanogaster: A Microarray Analysis

The rapid evolution of toxin resistance in animals has important consequences for the ecology of species and our economy. Pesticide resistance in insects has been a subject of intensive study, however, very little is known about how Drosophila species became resistant to natural toxins with ecological relevance, such as α-amanitin that is produced in deadly poisonous mushrooms. Here we performed a microarray study to elucidate the genes, chromosomal loci, molecular functions, biological processes, and cellular components that contribute to the α-amanitin resistance phenotype in Drosophila melanogaster. We suggest that toxin entry blockage through the cuticle, phase I and II detoxification, sequestration in lipid particles, and proteolytic cleavage of α-amanitin contribute in concert to this quantitative trait. We speculate that the resistance to mushroom toxins in Drosophila melanogaster and perhaps in mycophagous Drosophila species has evolved as a cross-resistance to pesticides or other xenobiotic substances. In the study presented here, we had a total of 3 experimental conditions using 2 stocks of Drosophila melanogaster: 5 biological replicates of the Canton-S stock raised on non-toxic food (CS), 5 biological replicates of the α-amanitin resistant Ama-KTT/M/2 stock raised on non-toxic food (KTT), and 6 biological replicates of the the α-amanitin resistant Ama-KTT/M/2 stock raised on food containing the LC-50 concentration of α-amanitin for this stock (KTT-LC50). For each of biological replicate, we extracted total RNA from a pooled 10 larvae in the late third instar.