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利用苏云金芽胞杆菌cry1A启动子上游区的不同突变体，观测对BtⅠ-lacZ融合基因表达的影响。结果发现，突变上游弯曲区，导致Btl-lacZ在菌株80-21中的酶活性大幅度下降，均比未突变的上游区降低2～2．5倍。而在菌株HD133-5中却出现相反的结果，即上游弯曲区的突变导致BtⅠ-lacZ的表达比未突变体增高。如果同时突变弯曲区和反向重复区，则BtⅠ-lacZ在菌株80-21中表达增强或下降的幅度大大减少。这表明，在crylA启动子上游区，不同位点在转录调控上的作用不同，这种调控作用也因菌株的差异而改变。
Different mutants in the upstream region of the cry1A promoter of B. thuringiensis were used to observe the effects on BtI-lacZ fusion gene expression. As a result, it was found that mutating the upstream bending region resulted in a significant decrease in the enzymatic activity of Btl-lacZ in strain 80-21, which was 2 to 2.5 times lower than that in the non-mutated upstream region. However, the opposite result was found in strain HD133-5, that is, the mutation in the upstream bending zone resulted in the increase of BtI-lacZ expression compared with the non-mutant. If both the bending region and the inverted repeat region are mutated, the extent of increase or decrease of BtI-lacZ expression in strain 80-21 is greatly reduced. This indicates that in the upstream region of the crylA promoter, the roles of different sites in transcriptional regulation are different, and this regulation is also changed due to the difference of the strains.