Hyphal tip growth in Achlya. I. Cytoplasmic organization

Area of Science:

• * Mycology
• * Cell Biology
• * Biochemistry

Background:

• * The growing hyphal tips of fungi are crucial for growth and development.
• * Understanding the role of vesicles in fungal cell wall synthesis and secretion is important.

Purpose of the Study:

• * To characterize the apical vesicles in Achlya ambisexualis hyphae using electron microscopy and cytochemical techniques.
• * To identify potential markers for isolating specific vesicle populations.

Main Methods:

• * Electron microscopy was employed to examine the ultrastructure of hyphal apices.
• * Cytochemical staining techniques, including periodic acid-silver methenamine (PASM) and phosphotungstic acid-chromic acid (PTA-CrO3), were used.
• * Enzyme activity assays for IDPase and acid phosphatase were performed.

Main Results:

• * Two major classes of apical vesicles were identified based on size and cytochemical reactions.
• * Larger vesicles (approx. 150 nm) contained polysaccharide material (PASM-positive) and showed IDPase and acid phosphatase activity.
• * Smaller vesicles (approx. 80 nm), including coated vesicles, were PASM-negative and some displayed IDPase activity.
• * The Golgi apparatus was identified as a potential source for both vesicle classes.
• * Differential staining properties (PTA-CrO3) distinguished the two vesicle classes.

Conclusions:

• * Apical vesicles in Achlya ambisexualis exhibit distinct populations with unique cytochemical characteristics.
• * The IDPase activity and polysaccharide content of the 150-nm vesicles may serve as markers for their isolation.
• * This research provides insights into vesicle trafficking and function in fungal hyphal growth.