Characterization and expression of cytochrome p450 cDNA (CYP9AT2) in Chironomus riparius fourth instar larvae exposed to multiple xenobiotics

•Chironomus riparius cytochrome p450 (CrCYP9AT2) cDNA was characterized.•Studied the transcriptional modulation of CrCYP9AT2 gene.•CrCYP9AT2 expression varied upon exposure to environmental xenobiotics.•CrCYP9AT2 could be potentially used as a molecular biomarker.

We identified and characterized a CYP9 family gene, CrCYP9AT2, from Chironomus riparius, an eco-toxicologically important model organism. The 1978 base pair (bp) length CrCYP9AT2 cDNA has an open reading frame of 1587 bp encoding a putative 528 amino acid protein. There was 267 bp 5′ and 123 bp 3’ untranslated region with a polyadenylation signal site (AATAAA). The putative heme-binding cysteine at position 471 and the typical p450 signature sequence of 463-FGIGPRNCIG-473 were also present. The CrCYP9AT2 transcript was present in all life stages with the highest expression in larvae. The modulation of CrCYP9AT2 was studied using real-time polymerase chain reaction after 24 h exposure to cadmium chloride, benzo(a)pyrene; bisphenol A; nonylphenol; chlorpyrifos and ethinylestradiol. Significant up-regulation of CrCYP9AT2 gene was observed after exposure to Cd, B(a)P and CP. However, CrCYP9AT2 was significantly down-regulated after exposure to BPA, NP and EE.