Figure 6.

Developmental time course of cellulose synthase activity. Membranes were prepared from the wild type (●), the dcsA⁻ mutant strain DG1128 (■), and the dcsA⁺ rescue strain TL128 (▴) at various times during development, and the specific activity of cellulose synthase was determined. The specific activity in cells of the dcsA⁻ strain was at or below background at all times. This was true as well for the DG1099 insertional mutant and for TL127, the strain with the new dcsA⁻ allele created by homologous recombination (data not shown). No activity was detected in amoebae or early-developing stages of TL128, even though the gene was being expressed, as shown by Northern blot analysis, and the protein was present, as shown by Western blot analysis. The low level of incorporation seen in membranes from amoebae was shown to be amylase-sensitive (see Results).