Figure 2.

Detection of DNase Activities during TE Differentiation.

Samples of protein extracts (10 μg of protein per lane) from Zinnia cells cultured for various periods in TE-inductive medium (D) or a control medium (Cp) were separated by SDS-PAGE using denatured calf thymus DNA as a substrate. After preincubation in 10 mM Tris-HCl, pH 7.5, containing 1 mM EDTA for 1 h, gels were incubated for another 12 h in different reaction buffers: 25 mM sodium acetate–acetic acid buffer, pH 5.5, containing 5 mM ZnSO₄ (A) or 10 mM Tris-HCl, pH 7.5, containing 10 mM CaCl₂ and 10 mM MgCl₂ (B). Background substrate was stained with ethidium bromide to visualize DNase bands. The predicted molecular mass of each band is presented in kD.