Development of biomarker for detecting silver nanoparticles exposure using a GAL4 enhancer trap screening in Drosophila

- Long-term exposure of AgNPs at low doses (0.1-1 μg/mL) but not Ag ions affects lifespan of Drosophila.
- Isolation of a GAL4 enhancer trap line (M95) as a sensitive biomarker of AgNPs.
- M95 flies are more sensitive to AgNPs and dry starvation compared to the control flies.
- AgNPs treatment up-regulates the JNK signaling in Drosophila.
- The basal level of p-JNK is elevated in M95 compared to control.

Silver nanoparticles (AgNPs) have been widely used in commercial goods ranging from medical devices to home appliances. Their widespread application increase the risk related to their potential toxicity. Although several studies showed their acute hazardous effects on living animals, our understanding of chronic effects of AgNPs exposed by the environment we encounter in our everyday lives is still very limited. This is partly because of the lack of versatile animal model system for studying AgNPs effects on terrestrial animals including human. In this study, we used Drosophila model to study AgNPs toxicity in terrestrial animals, and found that long-term exposure of AgNPs, but not Ag ions, at low level (0.1 and 1 μg/mL) significantly shortened the lifespan. By taking advantage of the power of Drosophila genetics, we also isolated a GAL4 enhancer trap line called M95, in which the expression of GAL4 is up-regulated in response to ingestion of AgNPs at concentrations as low as 0.1 μg/mL. Interestingly M95 flies showed significantly increased tolerance to both AgNPs treatment and dry starvation probably due to up-regulation of JNK signaling. These findings suggest not only that M95 may be a very useful biomarker of AgNPs because of its high sensitivity and tolerance to AgNPs, but also that Drosophila may be a versatile terrestrial invertebrate model for studying the effects of AgNPs on human health.