Related Experiment Videos
[Ultrastructural study of the mycelium-yeast transition in Histoplasma capsulatum. I. Changes at 37 degrees C]
G Borgia1, A Tallarino, A Lambiase
1Clinica delle Malattie Infettive, II Facoltà Di Medicina e Chirurgia, Università di Napoli.
Abstract:
Ultrastructural changes observed during the first 24 hours of mycelium to yeast transition in the dimorphic fungus Histoplasma capsulatum are reported. During this period the plasma membrane becomes undulated and the cell wall loses its characteristic fibrous outer layer. At 8 h the ordered lamellar structure of the mitochondria is no longer apparent. 24 h after the temperature shift 70% of the cells are lysed. The remaining cells contain many cytoplasmic membrane structures; mitochondria are rarely observed. These morphological changes are probably correlated with the physiological events characteristic of mycelial to yeast transition.
Insights
The dimorphic fungus Histoplasma capsulatum undergoes significant ultrastructural changes during its transition from mycelium to yeast. These include cell lysis and alterations in cell wall and mitochondrial morphology.
Area of Science:
- Medical Mycology
- Cell Biology
- Fungal Pathogenesis
Background:
- Histoplasma capsulatum is a dimorphic fungus responsible for histoplasmosis.
- Understanding the morphological changes during its transition is crucial for disease control.
Purpose of the Study:
- To investigate the ultrastructural changes during the initial 24 hours of the mycelium to yeast transition in Histoplasma capsulatum.
- To correlate observed morphological alterations with physiological events.
Main Methods:
- Transmission electron microscopy was used to examine cellular morphology.
- Time-course analysis was performed over 24 hours following a temperature shift.
Main Results:
- Plasma membrane undulation and loss of the fibrous outer cell wall layer were observed.
- Mitochondrial lamellar structure disappeared by 8 hours.
- Significant cell lysis (70%) occurred by 24 hours, with remaining cells showing altered cytoplasmic structures and few mitochondria.
Conclusions:
- The study details key ultrastructural events during the Histoplasma capsulatum mycelium-to-yeast transition.
- Observed morphological changes likely reflect underlying physiological adaptations necessary for yeast-phase survival and pathogenesis.