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 24h 
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.