Cytoskeleton in regenerating protoplasts and restoration of cell polarity in the yeast Saccharomyces cerevisiae

The actin cables and microtubules were disrupted during protoplasting in Sa ccharomyces cerevisiae cells. In the process of protoplast regeneration, th e cytoplasmic microtubules were the first to be restored; the actin patches remained regularly distributed under the surface of the growing protoplast . After the cell wall had been regenerated in a gelatine medium, the actin patches aggregated into clusters, which marked the site of bud development. An incomplete cell wall was the apparent cause for uncoupling between kary okinesis and cytokinesis. The presence of several nuclei in the cell gave r ise to several buds emerging simultaneously and was probably related to the ir random positions. in haploids, however, the axial type of budding was al so obvious in the reverting protoplasts. These observations suggest that ac tin is a structure involved in the restoration of polar growth during proto plast regeneration, and that the cell wail plays an important role in this process: in its absence, actin fails to polarise.