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Aspergillus nidulans asexual development: making the most of cellular modules

2010; Elsevier BV; Volume: 18; Issue: 12 Linguagem: Inglês

10.1016/j.tim.2010.09.007

1878-4380

Oier Etxebeste, Aitor Garzia, Eduardo A. Espeso, Unai Ugalde,

Mycotoxins in Agriculture and Food

Asexual development in Aspergillus nidulans begins in superficial hyphae as the programmed emergence of successive pseudohyphal modules, collectively known as the conidiophore, and is completed by a layer of specialized cells (phialides) giving rise to chains of aerial spores. A discrete number of regulatory factors present in hyphae play different stage-specific roles in pseudohyphal modules, depending on their cellular localization and protein–protein interactions. Their multiple roles include the timely activation of a sporulation-specific pathway that governs phialide and spore formation. Such functional versatility provides for a new outlook on morphogenetic change and the ways we should study it. Asexual development in Aspergillus nidulans begins in superficial hyphae as the programmed emergence of successive pseudohyphal modules, collectively known as the conidiophore, and is completed by a layer of specialized cells (phialides) giving rise to chains of aerial spores. A discrete number of regulatory factors present in hyphae play different stage-specific roles in pseudohyphal modules, depending on their cellular localization and protein–protein interactions. Their multiple roles include the timely activation of a sporulation-specific pathway that governs phialide and spore formation. Such functional versatility provides for a new outlook on morphogenetic change and the ways we should study it. multinucleate fungal cell that extends exclusively through deposition of new material at the tip. Cellular compartments within a hypha are delimited (but not isolated) by cross-walls called septa. Septation proceeds after mitosis, when the cell reaches a determined volume. Lateral branches emerge from hyphae through new budding points. basal cell emerging from aerial hyphae that develops a thick two-layered wall. The outer layer is continuous with the rest of the mycelium whereas the inner is exclusive to this structure. The conidiophore stalk emerges from the foot cell. aerial branch that extends from the foot cell without septa. The diameter of a stalk reaches 4–5 μm, 1–2 μm wider than vegetative hyphae. The length of a stalk reaches a height of approximately 100 μm in A. nidulans. apical swelling at the tip of the conidiophore stalk that usually reaches a diameter of 10 μm. The vesicle harbors multiple nuclear divisions yielding 60–70 nuclei that align at the vesicle dome. Each nucleus will support the budding of one metula. cells that are formed after multiple budding from the vesicle surface. Each vesicular nucleus enters one developing metula, followed by the formation of a septum at its base. Metulae show limited apical extension (6 μm long and 2 μm wide), after which each undergoes apical budding to yield two phialides. sporogenous cell that produces a long chain of conidia (over 100) through mitosis and a specialized apical budding process. nonmotile, metabolically dormant spore generated by mitosis from a phialide. Conidia are dispersive propagules with low water content and a complex multilayered cell wall, distinctly different from that of vegetative hyphae.