Genes regulating development and behavior exhibited altered expression in Drosophila melanogaster exposed to bisphenol A: use of real-time quantitative PCR (qRT-PCR) and droplet digital PCR (ddPCR) in genotoxicity study

Toxicity of bisphenol A on morphological and life-history traits of model insect Drosophila melanogaster was reported in our previous work. In the present study, we have analyzed the adversity of bisphenol A on the reproductive behavior of adult and on the expression of selected genes in the larva and adult stage of fruit fly exposed to bisphenol A (0.007 g/2 ml. or 3.5 mg/ml), in addition to determination of LC50 value of bisphenol A in larva and pupal stage. We employed both the quantitative reverse transcriptase PCR and droplet digital PCR for analyzing the expression profile of seven genes namely, decapentaplegic, vestigial, wingless, foraging, insulin-like receptor, doublesex, and fruitless. We found bisphenol A has more adverse effects on male sexual behavior than females. Moreover, we observed significant downregulation of all the selected genes in treated larvae except, fruitless in male where it showed significant upregulation. On contrary among the treated adult flies, significant downregulation of all target genes in both sexes is evident, except, doublesex and fruitless in males which showed significant upregulation. We did not observe any deviation of male: female sex ratio from 1:1 under bisphenol A exposure. All these results suggest bisphenol A adversely affects the optimum functioning of genes which are involved in the regulation of metabolic pathways, behavioral pattern, stress response, endocrine homeostasis, neural functioning, and the development of the specific organ in Drosophila melanogaster. Our result not only provides a foundation to study further the bisphenol A toxicity on different pivotal genes in Drosophila but also suggests the use of the droplet digital PCR technology in toxicity measurement at the molecular level in eukaryotic model systems.