Regulation Of The Expression Of Insecticidal Crystal Protein Gene Cry1D In Bacillus Thuringiensis

crylAb, cry1C and cry ID are three typical cryl class genes encoding protoxins in Bacillus thuringiensis subsp. aizawai strain HD-133. The expression of crylD is obviously different from that of crylAb in this strain. The main aim of the present work is to study on the regulation of crylD in order to investigate the reason for the low expression of cry ID in HD-133.(1) Amount and stability of cryW and crylAb mRNA in HD-133 were investigated. Northern blotting analysis showed that crylD mRNA was more stable than crylAb mRNA, however, crylD mRNA formed later 3h and less 3.7 times than crylAb mRNA during the mid-phase of sporulation. Moreover, crylAb mRNA could keep stable and large amount during the post-phase of sporulation. This suggested that difference of transcriptional efficiency and initiate time might be main reason for the difference of expression of crylAb and cry ID.(2) Influence of the promoter and upstream region on expression of cry ID was tested. Firstly, the PCR products of cry ID promoter and its upstream were obtained followed by the construction of shuttle plasmid containing crylD-lacZ. Then the crylD-lacZ was introduced into different hosts. Analysis of activity of p-galactosidase showed that the crylD and crylAb expressed differently in different hosts. Comparison of expression of crylD with crylAb in the same host revealed that different upstream and competition for