Eukaryote transcription is controlled by regulatory DNA sequences and transcription factors, so transcriptional control of gene plays a pivotal role in gene expression. In this study, we identified the region of the CYP6B6 gene promoter of Helicoverpa armigera which responds to the plant secondary toxicant 2-tridecanone. Transient transfection assay results from five of stepwise deletion fragments linked to the luciferase reporter gene revealed that the promoter activity of each CYP6B6 fragment was significantly higher than that of their basal activity after the Sf9 cells were treated with 2-tridecanone. Among all, the fragment spanning −373 to +405 bp of the CYP6B6 promoter showed an obviously 2-tridecanone inducibility (P<0.0001), which might have the 2-tridecanone responsive element based on promoter activity. Electrophoretic mobility shift assays revealed that the nuclear protein extracted from midgut of the 6th instar larva of H. armigera, reared on 10 mg 2-tridecanone per gram artificial diet for 48 h, could specifically bind to the active region from −373 to 21 bp of the CYP6B6 promoter. The combination feature also appeared when using a shorter fragment from −292 to −154 bp of the CYP6B6 promoter. Taken together, we found a 2-tridecanone core responsive region between −292 and −154 bp of the CYP6B6 promoter. This may lead us to a better understanding of transcriptional mechanism of P450 gene and provide very useful information for the pest control.

Haemonchus contortus infections in small ruminants are of major economic importance worldwide. Heat shock proteins (HSPs) are a family of molecular chaperones that play important roles in the process of invasion and survival of nematodes. Although HSP70 has been identified in several parasitic nematodes, little is known of its distribution and function in Haemonchus contortus. The aims of this study were to characterize HSP70 from Haemonchus contortus (designed as Hc-hsp70), express Hc-hsp70 and analyse the promoter activity in Caenorhabditis elegans. Bioinformatic analysis revealed that the open reading frame of the Hc-hsp70 cDNA encodes a 646-amino acid peptide, which is highly conserved in comparison to HSP70 in other nematodes. Phylogenetic analysis indicated that H. contortus is closely related to Caenorhabditis. The 5′-flanking region promoted green fluorescence protein (GFP) expression in the intestine in all larval stages and adult with 2 expression patterns in C. elegans. Expression of Hc-hsp70 mRNA transcripts in C. elegans increased following 2, 4, 6 h of heat shock and peaked at 4 h. However, its expression induced down-regulation of hsp-1 of C. elegans. These results suggest that the H. contortus hsp70 might have a similar function to that of C. elegans hsp-1.

Green tea catechins are known to have hypocholesterolaemic effects in animals and human subjects. In the present study, we investigated the effects of green tea catechins on the mRNA level and promoter activity of hepatic cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in the conversion of cholesterol to bile acids, in human hepatoma cells. Real-time PCR assays showed that different catechins, ( − )-epicatechin gallate (ECG), ( − )-epigallocatechin-3-gallate (EGCG), ( − )-epigallocatechin (EGC) and ( − )-epicatechin (EC), up regulated the CYP7A1 mRNA level by 5·5-, 4·2-, 2·9- and 1·9-fold, respectively, compared with the control. The − 1312/+358 bp of the CYP7A1 promoter was subcloned into the pGL3 basic vector that includes luciferase as a reporter gene. ECG or EGCG significantly increased CYP7A1 promoter activity by 6·0- or 4·0-fold, respectively, compared with the control. Also, EGCG stimulated CYP7A1 at both mRNA level and promoter activity in a dose-dependent manner. These results suggest that the expression of the CYP7A1 gene may be directly regulated by green tea catechins at the transcriptional level.