Figure 1.

Mitochondrial dynamics during meiosis and sporulation in budding yeast. Nuclei (gray) and mitochondria (black) are depicted during mitosis, meiosis, and spore formation in S. cerevisiae (Esposito and Klapholz, 1981). The corresponding nuclear stage or mitochondrial stage (Miyakawa et al., 1984; and this study) is indicated below each diagram. Mitotically dividing cells contain tubular mitochondrial networks (mitosis). Mitochondrial tubules fragment after cells arrest in G₁ and prepare for meiosis and sporulation (stationary phase, presporulation). mtDNA and respiration are essential throughout this stage. During premeiotic S-phase (beginning of sporulation/pretetrad stage), mitochondrial fragments rejoin to form tubules. Throughout meiosis I and II (middle and end of sporulation/pretetrad stage), mitochondrial tubules associate with the lobes of the dividing nucleus. The organelles remain tubular through the end of meiosis II and during early tetrad formation (early tetrad). After tetrads mature, mitochondrial tubules fragment once again (late tetrad; day 12 of sporulation in this study).