Fig. 3.

Rpb4 affects cell separation and morphology. Cells expressing rpb4 from either the P3nmt1 or P81nmt1 promoter were analyzed by microscopy. a Cells grown in EMM in the absence of thiamine (promoter ‘on’) at 32°C appear like normal, wild-type cells. b When grown in the presence of thiamine (promoter ‘off’), cells expressing rpb4 from the P3nmt1 promoter appear normal, while those expressing rpb4 under the P81nmt1 promoter display defects in cell morphology and septation. Multiple phenotypes including elongated cells with single or multiple septa and growth by branching are evident. c Cells expressing rpb4 under the P81nmt1 promoter were analyzed by fluorescence microscopy in the presence of thiamine. DAPI staining revealed single nuclei in each cell compartment, while calcofluor staining showed septa (some of them aberrant) separating the cell compartments. d Control cells and mutants showing similar phenotypes as cells expressing rpb4 under the P81nmt1 promoter cells. From left to right: wild-type cells, sep1 deletion mutants, ace2 deletion mutants and sep1 ace2 double deletion mutants