A novel CYP450 gene (CYP4V18) of the shrimp Penaeus schmitti Burkenroad, 1936 (Decapoda, Dendrobranchiata): cloning and down-regulation of CYP4V18 expression by the imidazole derivative KK-42

The CYP4 family is the most ancient and diversified group of P450 and some members are associated with ecdysteroid metabolism in arthropods. In an attempt to research the possible molecular mechanism of KK-42 action on Penaeus schmitti Burkenroad, 1936, one CYP4 cDNA sequence from the hepatopancreas was first cloned and its spatiotemporal expressions were analysed using real-time PCR, and the haemolymph 20-hydroxyecdysone (20E) level was measured by reverse-phase high-performance liquid chromatography. Results showed that the full-length cDNA contains a 1545 bp open reading frame encoding a predicted protein of 515 amino acids named CYP4V18 by the P450 nomenclature committee. The highest cyp4v18 mRNA level was detected in hepatopancreas. Compared with that of the KK-42 treatment group, the hepatopancreas cyp4v18 expression in the control group increased to >72.3%, even 187.7% () on day 6. The haemolymph 20E levels increased slightly in KK-42-treated shrimps compared to that in controls during the experimental stage. The results show that the hepatopancreas CYP4V18 is not involved in 20E biosynthesis, and likely plays other roles in the shrimp, P. schmitti.