EFFECT OF CRY1A δ‐ENDOTOXINS OF BACILLUS THURINGIENSIS ON Mg+‐ATPASE IN THE COLUMNAR CELLS OF BOMBYX MORI MIDGUT

Abstract The effects of Cry1A δendotoxins from Bacillus thringiensis subsp. kurstaki HD‐1 on the activity of M2+‐dependent ATPase in the columnar cells (CC) of Sombyx mori were examined. Cytochemical localization showed a strong M$ ‘ ‐ATPase activity on the apical brush border of CC and even on the peritrophic membrane, but not on the goblet cells except slight activity on their interdigitated valves. Although overdose toxins were imposed to the larvae and resulted in serious cellular pathological changes in the treated midgut in vim, no obvious reduction of the M2+‐ATPase activity on the CC membrane was observed. This may exclude the M2+ ATPase on the CC brush border membrane to be the potential natural channel modulated by B‐endotoxins of B. thuringiensis or a target of the toxin during larval intoxication.