Evaluation of 4-nonylphenol and bisphenol A toxicity using multiple molecular biomarkers in the water flea Daphnia magna

Alkylphenols are well-known endocrine disruptors and may cause developmental and reproductive disorders in aquatic organisms. Daphnia magna is commonly used in ecotoxicological studies as a promising model species to investigate the effects of endocrine distruptors. In the present study, transcriptional modulation of eleven potential molecular indicators related to detoxification, antioxidant, development, and cellular stress was analyzed in D. magna exposed to different concentrations of bisphenol A (BPA) and 4-nonylphenol (4-NP) for 24 h and 48 h, using real-time qPCR. A hierarchical clustering analysis was applied to investigate relations among molecular markers depending on the compound, exposure duration, and concentration. Our findings suggested that GSH-related systems and stress proteins may be involved in cellular defense against BPA and 4-NP-mediated toxicity with different modes of action. Furthermore, these compounds may interrupt molting and reproduction in daphnids. In particular, D. magna GSH-related genes seem to be strongly affected by 4-NP exposure, indicating their potential as molecular biomarkers.