Hyphae of ascomycetes and basidiomycetes are compartmentalized by septa. Septa contain a central pore which allows for cytoplasmic streaming and translocation of organelles. Upon damage septa can be closed. In basidiomycetes, septa are plugged by electron dense material. Evidence indicates that the septal pore cap is involved in this plugging process. The core of the septal pore cap of Schizophyllum commune is comprised of the proteins SPC33 and SPC14. In ascomycetes, septa are closed by Woronin Bodies. The core of these peroxisome-like organelles consists of the HEX1 protein. Recently, we showed that septa are not only plugged upon mechanical damage. Septa can also be closed during vegetative growth. The incidence is affected by the environmental conditions. Septa of S. commune tend to be open in the absence of glucose. In contrast, they close when exposed to high temperature, hypertonic conditions, or to an antibiotic. By changing the temperature conditions, it was shown that plugging was reversible. In Aspergillus oryzae, hypertonic or low pH stress tends to close septa. On the other hand, low and high temperature, hypotonic conditions and high pH open more septa. We have shown that Woronin Bodies are responsible for the plugging of septa during vegetative growth. In contrast, localization of AoSO at septa highly increases the incidence of septal opening. Septal closure by Woronin Bodies and AoSO localization were shown to be reversible. Our data imply that S. commune and A. oryzae can regulate their intercompartmental cytoplasmic continuity by reversible closure of their septa.
Full conference title:
26th Fungal Genetics Conference
- Fungal Genetics Conference 26th (2005)