The insecticidal δ-endotoxin genes cry-1-1 and cry-1-2 derived from Bacillus thuringiensis var. kurstaki HD-1 were cloned, and their nucleotide sequences were determined. The nucleotide sequence of cry-1-1 was identical with the one reported by Schnepf et al. except for one base in the coding region. The coding regions of our two cloned toxin genes were not identical, but showed homology. More intensive variations in the sequences were observed in some regions, predominantly in the center of the coding region, 3’-terminal portion and 3’-flanking region. The differences in nucleotide sequences may have been mainly induced by base exchanges and deletions. Both translated products in E. coli were toxic to Bombyx mori larvae, but their insecticidal activities were considerably different.
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