Mitochondrial morphology in Basidiobolus haptosporus

Area of Science:

• Mycology
• Cell Biology
• Fungal Pathogenesis

Background:

• Young hyphal cells of Basidiobolus haptosporus display unique mitochondrial structures.
• These structures, termed annulate views, feature a central space with cytoplasmic components and other organelles.
• The consistent morphology suggests specific organelle interactions rather than random mitochondrial plasticity.

Purpose of the Study:

• To investigate the three-dimensional structure of unusual mitochondrial forms in Basidiobolus haptosporus.
• To explore the relationship between mitochondrial morphology and cellular environment, particularly nitrogen sources.
• To understand the spatial associations of organelles within young hyphal cells.

Main Methods:

• Electron microscopy of thin sections of Basidiobolus haptosporus hyphae.
• Three-dimensional reconstruction and projection of mitochondrial structures.
• Culturing the fungus on xanthine or its catabolites as sole nitrogen sources for comparative analysis.

Main Results:

• Three-dimensional projections suggest mitochondria adopt a goblet-shaped enclosure, with annulate views resulting from sectioning planes.
• Organelle associations, including lipid bodies, other mitochondria, and microbodies, are frequently observed within these structures.
• When grown on xanthine, microbody proliferation occurs, and annulate mitochondrial views disappear, with microbodies associating closely with mitochondria.

Conclusions:

• The observed annulate mitochondrial views are a consequence of sectioning planes through goblet-shaped mitochondria, indicative of close organelle associations in young hyphae.
• Cultivation on xanthine alters cellular composition, leading to microbody proliferation and a shift in mitochondrial morphology and associations.
• These findings highlight the dynamic interactions between organelles in Basidiobolus haptosporus under varying nutritional conditions.