Fig. 2

Toxicity and biological activities of EY mutant toxin in the presence and absence of calcofluor. Larvae were fed with toxin inclusion bodies of wild-type Cry4Ba and EY mutant toxin at 5, 25 and 50 μg/ml, E. coli cells expressing Cry4Ba, and E. coli cells harbouring expressing plasmid pUC12. Percent mortality was represented as the mean + SEM (a). PM perturbation ability of Cry4Ba toxin was evaluated by feeding the larvae with PM impermeable 2000 kDa dextran (conjugated with FITC) alone or in combination with wild-type Cry4Ba and EY mutant toxin at their LC₉₀ concentrations. Percent PM permeability was represented as % of larvae with fluorescent signal outside the gut lumen after one h treatment (b). The tissue sections of treated larvae were immuno-stained with mouse anti-Cry4Ba monoclonal antibody and HRP-linked anti-mouse immunoglobulins (c). LC₅₀ and LC₉₀ of EY mutant toxin were determined after 24 h treatment in the presence or absence of calcofluor and presented as μg/ml ± SEM (d). The lines point out the BBMV that are positively stained with wild-type Cry4Ba and EY mutant toxins. Control is untreated larval gut tissue. Abbreviations: L, lumen; BBMV, brush border microvilli