The dynamic structure of Spitzenkörpers of Trichosporon asahii examined by the fluorescent probe FM4-64

Abstract The Spitzenkörper is a dynamic and specialized multicomponent cell complex present in the tips of hyphal cells. The amphiphilic styryl dye FM4-64 was found to be ideal for imaging the dynamic changes of the apical vesicle cluster within growing hyphal tips. It is widely used as a marker of endocytosis and to visualize vacuolar membranes. Here we performed uptake experiments using FM4-64 to study the dynamic of the Spitzenkörper in Trichosporon asahii. We observed that Spitzenkörpers were present at the tip of the budding site of the spore, blastospore, and the germ tube of T. asahii. We also found that Spitzenkörpers were present at the tip of the hyphae as well as the subapical regions. Cytochalasin D, an inhibitor of actin polymerization, leads to abnormal Spitzenkörper formation and loss of cell polarity.

The Architecture of Fungal Cells / 대한의진균학회지

The Kingdom fungus has a unique structure and organization. Recent advances in electron microscopy and use of specific cytochemical technique enable the ultrastructures to be visualized. The hypha is a tube-like structure with a rigid wall, containing a moving slug of protoplasm. Hypha grows only at the tapered apical tip region, which is called extension zone. Extreme tip area has apical vesicle cluster which is responsible for tip growth. Unique fungal structure, Spitzenk rper, is thought to be a central region of the apical vesicle cluster. Most hyphal structures except the species belong to Zygomycetes have septa. But the septum is not completely blocked and it has different types of opening pores. The simple septal pores with Woronin bodies, which are found in Ascomycetes and Deuteromycetes, can be plugged in two different mechanisms. During normal differentiation the pores become occluded by a gradual deposition of plugged material. Loss of cytoplasm from damaged hyphae can be reduced and blocked by the rapid occlusion of septal pores by Woronin bodies or hexagonal crystal bodies. Septal sealing in Basidiomycetes which have dolipore septum is made by the rapid formation of electron-dense pore plugs. The shape of the fungal cell is the shape of fungal wall. Fungal walls appear to be composed of layers, which are thought to merge into one another to form one structure. The cytoskeleton consists of microtubules and microfilaments with motor proteins, and they seems to act together in the fungal cells.