Transcriptional activity of detoxification genes is altered by ultraviolet filters in Chironomus riparius

Ultraviolet (UV) filters are compounds used to prevent the damage produced by UV radiation in personal care products, plastics, etc. They have been associated with endocrine disruption, showing anti-estrogen activity in vertebrates and altering the ecdysone pathway in invertebrates. Although they have attracted the attention of multiple research teams there is a lack of data about how animals activate detoxification systems, especially in invertebrates. Here, analysis of the effects of two UV filters, benzophenone-3 (BP3) and 4-methylbenzylidene camphor (4MBC), on the transcriptional activity of nine genes covering the three steps of the detoxification process has been performed. Four cytochrome P450 genes belonging to different members of this family, five GST genes, and the multidrug resistance protein 1 (MRP1) gene were studied by RT-PCR to analyze their transcriptional activity in fourth instar larvae exposed to the UV filters for 8 and 24 h. The obtained results show a differential response with downregulation of the different Cyp450s tested by 4MBC while BP3 seems not to modify their expression. On the other hand, some of the GST genes were affected by one or other of the filters, showing a less homogenous response. Finally, MRP1 was activated by both filters but at different times. These results demonstrate for first time that UV filters alter the expression of genes involved in the different steps of the detoxification process and that they can be processed by phase I enzymes other than Cyp450s. They also suggest that UV filters affect biotransformation processes, compromising the ability of the individual to respond to chemical stress, so further research is needed to know the extent of the damage that they can produce in the resistance of the cell to chemicals.