title: The tip growth apparatus of Aspergillus nidulans.
abstract: Hyphal tip growth in fungi is important because of the economic and medical importance of fungi, and because it may be a useful model for polarized growth in other organisms. We have investigated the central questions of the roles of cytoskeletal elements and of the precise sites of exocytosis and endocytosis at the growing hyphal tip by using the model fungus Aspergillus nidulans. Time-lapse imaging of fluorescent fusion proteins reveals a remarkably dynamic, but highly structured, tip growth apparatus. Live imaging of SYNA, a synaptobrevin homologue, and SECC, an exocyst component, reveals that vesicles accumulate in the Spitzenkörper (apical body) and fuse with the plasma membrane at the extreme apex of the hypha. SYNA is recycled from the plasma membrane by endocytosis at a collar of endocytic patches, 1-2 mum behind the apex of the hypha, that moves forward as the tip grows. Exocytosis and endocytosis are thus spatially coupled. Inhibitor studies, in combination with observations of fluorescent fusion proteins, reveal that actin functions in exocytosis and endocytosis at the tip and in holding the tip growth apparatus together. Microtubules are important for delivering vesicles to the tip area and for holding the tip growth apparatus in position.
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Naimeh
authors.initials: N
authors.lastname: Taheri-Talesh
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Horio
authors.forename: Lidia
authors.initials: L
authors.lastname: Araujo-Bazán
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Dou
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Espeso
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Peñalva
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Osmani
authors.forename: Berl R
authors.initials: BR
authors.lastname: Oakley
mesh_terms: D000199:Actins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D001233:Aspergillus nidulans / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D001542:Benomyl / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D003572:Cytochalasins / Q000494:pharmacology; D004705:Endocytosis; D005089:Exocytosis; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D025301:Hyphae / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D053778:Thiazolidines / Q000494:pharmacology; D014335:Tropomyosin / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003572:Cytochalasins; D005656:Fungal Proteins; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; D053778:Thiazolidines; D014335:Tropomyosin; C031218:cytochalasin A; D049452:Green Fluorescent Proteins; C037068:latrunculin B; D001542:Benomyl