title: Microfilament distribution in protonemata of the moss Ceratodon.
abstract: Microfilaments were visualized in dark-grown protonemata of the moss Ceratodon to assess their possible role in tip growth and gravitropism. The relative effectiveness of rhodamine phalloidin (with or without m-maleimidobenzoyl-N-hydroxysuccinimide ester (MBS)) and of immunofluorescence (using the C4 antibody) was evaluated for actin localization in the same cell type. Using immunofluorescence, microfilaments were primarily in an axial orientation within the apical cell. However, a more complex network of microfilaments was observed using rhodamine phalloidin after MBS pretreatment, especially when viewed by confocal laser scanning microscopy. This method revealed a rich three dimensional network of fine microfilaments throughout the apical cell, including the extreme apex. Although there were numerous internal microfilaments, peripheral microfilaments were more abundant. No major redistribution of microfilaments was detected after gravistimulation. The combination of MBS, rhodamine phalloidin, and confocal laser scanning microscopy preserves and reveals microfilaments remarkably well and documents perhaps the most extensive F-actin network visualized to date in any tip-growing cell.
authors.affiliation: Department of Plant Biology, The Ohio State University, Columbus, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Walker
authors.forename: F D
authors.initials: FD
authors.lastname: Sack
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D000199:Actins / Q000032:analysis / Q000648:ultrastructure; D019068:Bryopsida / Q000737:chemistry / Q000254:growth & development / Q000648:ultrastructure*; D003432:Cross-Linking Reagents; D005404:Fixatives; D005456:Fluorescent Dyes; D005557:Formaldehyde; D018522:Gravitropism; D018613:Microscopy, Confocal / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods*; D010590:Phalloidine / Q000031:analogs & derivatives*; D011108:Polymers; D011309:Preservation, Biological / Q000379:methods*; D012235:Rhodamines; D013194:Staining and Labeling / Q000379:methods; D013388:Succinimides
chemical_list: D000199:Actins; D003432:Cross-Linking Reagents; D005404:Fixatives; D005456:Fluorescent Dyes; D011108:Polymers; D012235:Rhodamines; D013388:Succinimides; C072252:m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester; D010590:Phalloidine; D005557:Formaldehyde; C003043:paraform