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Mechanisms of hyphal tip growth: tube dwelling amebae revisited
1Institut für Genetik, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada. brent@yorku.ca
Abstract:
Over 100 years ago, Reinhardt suggested that hyphal tip growth is comparable to ameboid movement inside a tube; the apical cytoplasm being protruded like a pseudopodium with the wall assembled on its surface. There are increasing data from hyphae which are explicable by this model. Fungi produce pseudopodia-like structures and their cytoplasm contains all of the major components implicated in pseudopodium production in animal cells. Most of these components are concentrated in hyphal tips and tip growth involves actin, a major component of pseudopodia. Together these data indicate that the essence of the ameboid model is still tenable. However, detailed mechanisms of tip growth remain too poorly known to provide definitive proof of the model and the behavior of the trailing cytoplasm indicates differences which are probably a response to the walled lifestyle.
Insights
Fungal hyphal tip growth may resemble ameboid movement, with cytoplasm protruding like a pseudopodium. While evidence supports this model, the exact mechanisms and walled lifestyle adaptations require further study.
Area of Science:
- Mycology
- Cell Biology
- Biophysics
Background:
- Reinhardt's 100-year-old hypothesis proposed fungal hyphal tip growth mimics ameboid movement within a tube.
- Fungal hyphae exhibit pseudopodia-like structures and possess key components for pseudopodium formation found in animal cells.
- Actin, a crucial component of pseudopodia, is abundant in fungal hyphal tips, supporting the ameboid model.
Purpose of the Study:
- To evaluate the tenability of the ameboid model for fungal hyphal tip growth.
- To explore the cellular mechanisms underlying fungal tip growth in relation to known ameboid processes.
- To identify differences in fungal tip growth potentially due to their unique walled structure.
Main Methods:
- Comparative analysis of fungal hyphal structures and components with animal cell ameboid movement mechanisms.
- Review of existing data on fungal hyphal tip growth, focusing on actin localization and cytoplasmic behavior.
- Examination of pseudopodia-like structures in fungi.
Main Results:
- Accumulating data support the fundamental aspects of the ameboid model for fungal hyphal growth.
- Key components for pseudopodium production are concentrated in fungal hyphal tips.
- The behavior of trailing cytoplasm suggests adaptations specific to the fungal walled lifestyle.
Conclusions:
- The core concept of the ameboid model for fungal hyphal tip growth remains plausible.
- Detailed mechanistic understanding of fungal tip growth is still incomplete.
- The walled nature of fungi likely influences cytoplasmic dynamics during tip growth, differentiating it from non-walled ameboid cells.