Figure 8.
Expression of mannuronan C-5-epimerase in L. digitata protoplast cultures. A, Epimerase activity in the culture medium, as measured with the [5-3H] poly-mannuronate assay. Samples were assayed in triplicates. Error bars = sds. B, Epimerase expression in protoplasts, as detected by northern blot and RT-PCR, as in Figure 7. C, Western blot of proteins from the protoplast culture medium. Proteins (2.1 μg lane–1) were separated by 12% (w/v) SDS-PAGE, transferred onto a nylon membrane, and probed with an antiserum made against two peptides of ManC5-E6 (shown in Fig. 2). Incubation of the blot with pre-immune serum did not reveal any nonspecific cross-reaction (data not shown).