Fig. 8. An aberrant cortical ER network persists after cycloheximide treatment in the ice2 mutant. (A) The cortical ER network remains abnormal upon cycloheximide treatment in the ice2 mutant. Diploid cells (strains SFNY1061 and SFNY1282) expressing the ER marker Hmg1p-GFP were grown in YPD at 30°C, treated with cycloheximide for 6 hours and analysed using fluorescence microscopy. Images were obtained from the periphery and centre of the cell. Arrowheads point to a continuous network displayed in wild-type mother cells (A, left). Arrows point to wild-type buds that display a normal cortical ER network (A, left) and to buds in ice2 cells that lack an intact cortical ER network (A, right). An abnormal ER network (arrowheads) is also observed in the mother cell of the ice2 mutant (A, right). (B) The mitochondrial structure remains intact in ice2 mutants displaying an aberrant cortical ER network. Mitochondrial distribution was studied using fluorescence microscopy in wild-type and ice2 cells expressing the ER marker Hmg1p-GFP (left). Mitochondria were visualized in cells transformed with plasmid SFNB798, which expresses the mitochondrial targeting sequence from the F₀ ATP synthase fused to RFP (middle). The differential-interference-contrast images (DIC) are located on the right. The distribution of mitochondria was determined in small buds with a volume of 4-13% of the mother.