ИСТИНА

A stored product pest, Tenebrio molitor, is sensitive to Cry3Aa toxin from Bacillus thuringiensis (Bt). Larvae digest protein initially with cysteine peptidases in the anterior midgut and further with serine peptidases in the posterior midgut, and the latter activate Bt Cry protoxins and are a determining factor in toxicity and resistance. We evaluated the effect of Cry3Aa protoxin on the expression of cysteine and serine peptidase genes in the midgut of T. molitor larvae. High-throughput sequencing was used to obtain EST databases from midguts of one month old T. molitor larvae fed either a control diet or diet containing 0.1% Cry3Aa for 12 and 24 h. In addition, the temporal expression of peptidase genes was investigated by microarray analysis. Bt intoxication significantly impacted the expression of serine peptidases, potentially important in protoxin processing, while the insect maintained the production of critical digestive cysteine peptidases. We hypothesize that the insect may be attempting to decrease toxicity while maintaining efficient protein digestion.