Mitochondria provide the energy for growing hypha of aerobic fungi. Therefore, mitochondria have to grow, to divide and to distribute as hyphae elongate. To study their behavior in vivo, we have expressed GFP in mitochondria of Aspergillus nidulans. We found that these organelles are organized as an intracellular network of interconnected tubular structures. Fluorescence video-microscopy revealed that the pattern of mitochondria changes constantly, small organelles bud off, migrate some distance and fuse at other places. To get insights into the molecular basis of the movement, different strategies were applied. Comparison of the effect of microtubule-destabilizing agents to actin-destabilizing agents suggests that a functional actin cytoskeleton is required for mitochondrial movement and morphology. In the presence of cytochalasin A mitochondria loose their tubular structure. To finally prove actin-dependent mitochondrial movement, we are currently trying to establish an in vitro motility assay using actin filaments and isolated mitochondria. In addition, a mutant screen was performed and 25 strains were isolated with defects in mitochondrial distribution. One mutant will be studied in more detail.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)