Changes in the distribution of F-actin in the fission yeast Schizosaccharomyces pombe by arresting growth in distilled water: correlative studies with fluorescence and electron microscopy.
Freeze-substitution electron microscopy of Schizosaccharomyces pombe cells starved in distilled water was conducted to define ultrastructural counterparts of actin visualized by fluorescence microscopy using rhodamine-conjugated phalloidin (Rh-ph). Starvation in distilled water caused remarkable changes in actin distribution and ultrastructural changes in S. pombe. Fluorescence microscopy of the starved cells showed that the dots of actin at the growing ends became thick actin cables via an enlarged patched form of actin. These changes were reversible, and growth-arrested cells resumed their original pattern of actin distribution upon return to growth medium. Electron microscopy of starved cells showed bundles of thin filaments and clusters of filamentous balls in the cytoplasm, which corresponded to the actin cables and enlarged actin dots, respectively, as seen by fluorescence microscopy. Vesicles polarized at the growing cell ends were dispersed in the cytoplasm by distilled water treatment, indicating that actin organization plays a role in directing vesicle location.
Kanbe T, Akashi T, Tanaka K