Morphological Changes in Mitochondria, Mitochondrial Nucleoids, and Actin Cytoskeleton during the Transition from Anaerobic to Aerobic Culture in the Yeast Saccharomyces cerevisiae

Abstract

We examined the morphological changes in mitochondria, mitochondrial nucleoids (mt-nucleoids), and the actin cytoskeleton in the yeast Saccharomyces cerevisiae during the transition from anaerobic to aerobic culture by immunofluorescence microscopy, DAPI staining, and rhodamine-phalloidin staining. The cells grown anaerobically to the stationary phase contained a small number of mitochondria, 7.3 per cell on average. When cells were transferred to aerobic culture, mitochondria began to elongate within 1 h and divided into smaller spherical mitochondria within 8 h. The number of mitochondria per cell on average was 29.4 at 4 h, 52.8 at 6 h, and 71.8 at 8 h. These morphological changes in mitochondria required respiratory activity and coincided well with those of the mt-nucleoids. In addition, we found that the rapid conversion of the cortical actin patches from the large aggregates to the small patches occurred during the transition from anaerobic to aerobic culture.