Article Abstract:
Cry9Ca1 is an insecticidal crystal protein from Bacillus thuringiensis serovar tolworthi that is active against lepidopteran insects from the families Pyralidae, Plutellidae, Sphingidae, and Noctuidae, among others. The protein has specific receptor-binding features and a wide range of activity. It is the first to be active against cutworms but has no activity against some beetles. Cry1Ab5 recognizes a receptor different from that recognized by Cry9Ca1, in Ostrinia nubilalis and Plutella xylostella. In Spodoptera exigua and P. xylostella, Cry9Ca1 binds to the same receptor as Cry1Cax, though with lower affinity.
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Article Abstract:
A two-step method to stably integrate an extra crystal protein gene into Bacillus thuringiensis chromosomes may have general applicability to increasing the bacterium's insecticidal activity. The aizawai strain cryIC gene was first integrated into the kurstaki strain HD73 chromosome, which contains only one crystal gene. This decreased the chances of the homologous recombination event disrupting a resident cry gene. By generalized transduction, the integrated cryIC gene was then transfered to kurstaki strains with multiple cry genes.
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Article Abstract:
A protein called CryIIIC produced by Bacillus thuringiensis was found to have silent activity against Colorado potato beetle larvae. The protein is contained in bipyramidal crystals and is made up of a single chain with a trypsin-resistant toxic core moiety of 72 kDa. Insecticidal activity is expressed only after in vitro solubilization and proteolytic activation. The native crystals are nontoxic. The gene coding for CryIIIC was also sequenced. Relatively low homology was found between CryIIIC and the other Cry proteins.
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