Fig. 4

Effect of Ca²⁺ inhibitors on cytosolic Ca²⁺ concentrations and cellulase production after DMF addition. A Fluorescence indicating LaCl₃ and EGTA effects on the cytosolic Ca²⁺ burst induced by DMF. T. reesei QM6a was cultured in liquid Mandels’ medium for ~ 32 h, transformed to fresh MM with 0% or 1% DMF and 0 or 5 mM LaCl₃/EGTA, and cultivated for 48 to 60 h. For detection, 50 μM Fluo-3 AM was used, and fluorescence intensity was monitored using automatic inverted fluorescence microscopy. Green fluorescence represents free cytosolic Ca²⁺. DIC, differential interference contrast. CK, not treated with inhibitors LaCl₃/EGTA. B Comparative fluorescence ratios indicating LaCl₃ and EGTA effects on the cytosolic Ca²⁺ burst induced by DMF. The x-axis represents different treatments with DMF and inhibitors, and the y-axis represents Ca²⁺ fluorescence ratios measured by CLSM. C, D CMCase/biomass activity (C) and pNPCase/biomass activity (D) were examined after T. reesei QM6a was cultured in medium with different DMF and inhibitor treatments. E, F The expression levels of cbh1 (E) and egl1 (F) in T. reesei QM6a were analyzed after culture in medium with various DMF and inhibitor treatments. Blue bar, no DMF was added to the medium; red bar, 1% (v/v) DMF was added to the medium. Values are the mean ± SD of the results from three independent experiments. Different letters indicate significant differences between the columns (p < 0.05, Duncan’s multiple-range test)