Filament ring formation in the dimorphic yeast Candida albicans

Area of Science:

• * Cell biology
• * Mycology
• * Microbial pathogenesis

Background:

• * Candida albicans exhibits dimorphism, switching between yeast (budding) and hyphal (mycelial) forms.
• * The mechanisms regulating these morphological transitions and cell division are not fully understood.
• * Septum formation is a critical event in cell division for fungi.

Purpose of the Study:

• * To investigate the role and characteristics of the filament ring during Candida albicans morphogenesis.
• * To determine the temporal and spatial dynamics of filament ring formation in budding versus mycelial growth.
• * To explore the relationship between the filament ring and chitinous septum formation.

Main Methods:

• * Culturing of Candida albicans stationary phase cells under specific pH conditions (pH 4.5 for budding, pH 6.5 for mycelia) at 37°C.
• * Microscopic observation and analysis of filament ring formation during different growth phases.
• * Sectioning and examination of filament ring structures in budding and mycelial cells.

Main Results:

• * A filament ring forms under the plasma membrane during both budding and mycelial growth in Candida albicans.
• * The filament ring appears earlier in budding cells (at mother cell-bud junction) than in mycelial cells (along the elongating hyphae).
• * Filament rings consist of approximately 11-12 equidistant filaments and disappear as the primary septum forms, suggesting a role in its placement.

Conclusions:

• * The filament ring is a key structure involved in regulating cell division and morphogenesis in Candida albicans.
• * Temporal and spatial differences in filament ring formation correlate with the commitment to budding or mycelial growth.
• * The filament ring likely plays a role in the positioning and formation of the chitin-containing septum.