title: F-actin marks the rhizoid pole in living Pelvetia compressa zygotes.
abstract: Spatial and temporal changes in F-actin during polarity establishment in Pelvetia compressa zygotes were investigated using vital staining with rhodamine phalloidin (RP). F-actin was localized to a patch in the cortex of young zygotes. When unilateral light was applied to induce a growth axis (photopolarization) in a population of zygotes, the cortical F-actin patches localized at the shaded pole (rhizoid pole of growth axis). Treatments that prevented photopolarization prevented localization of F-actin patches to the shaded pole. When the direction of the light treatment was reversed, the previous growth axis was abandoned and a new axis was established in the opposite direction. The F-actin patch repositioned to the new rhizoid pole within minutes of light reversal, indicating that F-actin was an immediate marker of the nascent growth axis. Repositioning probably occurred by disassembly of the initial patch and reassembly of a new one. The patch grew in size as zygotes developed, eventually becoming a ring just prior to rhizoid outgrowth. The rhizoid emerged at the site of the F-actin ring and, following germination, the ring was located in the subapical zone of the elongating tip.
authors.affiliation: University of Utah, Department of Biology, 1400 East, Salt Lake City, UT 84112-0840, USA.
authors.forename: L
authors.initials: L
authors.lastname: Alessa
authors.forename: D L
authors.initials: DL
authors.lastname: Kropf
mesh_terms: D000199:Actins / Q000032:analysis / Q000378:metabolism* / Q000528:radiation effects; D020126:Brefeldin A / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D004136:Dinitrobenzenes / Q000494:pharmacology; D056890:Eukaryota / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D005306:Fertilization; D008027:Light; D010590:Phalloidine / Q000031:analogs & derivatives / Q000032:analysis; D012235:Rhodamines / Q000032:analysis; D012503:Saponins / Q000494:pharmacology; D013424:Sulfanilamides; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D015053:Zygote
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004136:Dinitrobenzenes; D012235:Rhodamines; D012503:Saponins; D013424:Sulfanilamides; D013844:Thiazoles; D053778:Thiazolidines; C067497:rhodamine B isothiocyanate phalloidin; D010590:Phalloidine; D020126:Brefeldin A; C012465:oryzalin; C037068:latrunculin B