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.