DNA damage and transcriptional changes induced by tributyltin (TBT) after short in vivo exposures of Chironomus riparius (Diptera) larvae

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology Vol. 158; no. 2; pp. 57 - 63
• Main Authors: Morales, Mónica, Martínez-Paz, Pedro, Ozáez, Irene, Martínez-Guitarte, José Luis, Morcillo, Gloria
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2013
• Subjects: adverse effects; Animals; Chironomidae - drug effects; Chironomidae - genetics; Chironomus riparius; Diptera; DNA; DNA damage; DNA Damage - drug effects; ecdysone; Ecdysone-responsive genes; Endocrine disruptors; Endocrine Disruptors - toxicity; gene expression regulation; genes; genotoxicity; hormones; hsp70; Insect Proteins - genetics; insects; Larva - drug effects; Larva - genetics; larvae; mechanism of action; Nuclear receptor genes; Receptors, Estrogen - genetics; Receptors, Steroid - genetics; reproduction; reverse transcriptase polymerase chain reaction; transcription (genetics); Trialkyltin Compounds - toxicity; tributyltin; Vitellogenin; Vitellogenins - genetics; Endocrine disruptors; Ecdysone-responsive genes; hsp70; Vitellogenin; Nuclear receptor genes
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cbpc.2013.05.005

Tributyltin (TBT) is a widespread environmental contaminant in aquatic systems whose adverse effects in development and reproduction are related to its well-known endocrine-disrupting activity. In this work, the early molecular effects of TBT in Chironomus riparius (Diptera) were evaluated by analyzing its DNA damaging potential and the transcriptional response of different endocrine-related genes. Twenty-four-hour in vivo exposures of the aquatic larvae, at environmentally relevant doses of TBT, revealed genotoxic activity as shown by significant increases in DNA strand breaks quantified with the comet assay. TBT was also able to induce significant increases in transcripts from the ecdysone receptor gene (EcR), the ultraspiracle gene (usp) (insect ortholog of the retinoid X receptor), the estrogen-related receptor (ERR) gene and the E74 early ecdysone-inducible gene, as measured by real-time RT-PCR. In contrast, the expression of the vitellogenin (vg) gene remained unaltered, while the hsp70 gene appeared to be down-regulated. The ability of TBT to up-regulate hormonal target genes provides the first evidence, at genomic level, of its endocrine disruptive effects and also suggests a mechanism of action that mimics ecdysteroid hormones in insects. These data reveal for the first time the early genomic effects of TBT on an insect genome.