Abstract
Two Choristoneura fumiferana glutathione S‐transferase cDNAs were cloned from a cDNA library constructed using mRNA from the midgut cell line, CF‐203. These cDNAs (__Cf__GST2, __Cf__GST3) encoded two structurally different proteins with a predicted molecular mass of 21 and 24 kDa, respectively, which was confirmed through protein expression in a bacterial system. Quantitative reverse‐transcription PCR analyses revealed that the transcripts of these two genes were present in the epidermis, fat body, and midgut of the 6th instar larvae. __Cf__GST2 was expressed in the fat body when the insects were close to pupal molting, while it was constantly expressed in the other two tissues during the 6th instar stage. __Cf__GST3 gene was expressed highly and constantly in all of the tissues throughout the 6th instar stage. Immunohistochemistry analysis demonstrated that __Cf__GST2 and __Cf__GST3 proteins were present mainly in the fat body and epidermis and no protein was detected in the midgut. __Cf__GST2 and __Cf__GST3 were different from __Cf__GST reported before (Feng et al., 1999: Insect Biochem Mol Biol 29:779–793) in amino acid sequence, expression pattern, and responsiveness to tebufenozide. Arch. Insect Biochem. Physiol. 66:146–157, 2007. © 2007 Wiley‐Liss, Inc.