title: Involvement of the sieve element cytoskeleton in electrical responses to cold shocks.
abstract: This study dealt with the visualization of the sieve element (SE) cytoskeleton and its involvement in electrical responses to local cold shocks, exemplifying the role of the cytoskeleton in Ca(2+)-triggered signal cascades in SEs. High-affinity fluorescent phalloidin as well as immunocytochemistry using anti-actin antibodies demonstrated a fully developed parietal actin meshwork in SEs. The involvement of the cytoskeleton in electrical responses and forisome conformation changes as indicators of Ca(2+) influx was investigated by the application of cold shocks in the presence of diverse actin disruptors (latrunculin A and cytochalasin D). Under control conditions, cold shocks elicited a graded initial voltage transient, ΔV1, reduced by external La(3+) in keeping with the involvement of Ca(2+) channels, and a second voltage transient, ΔV2. Cytochalasin D had no effect on ΔV1, while ΔV1 was significantly reduced with 500 nm latrunculin A. Forisome dispersion was triggered by cold shocks of 4°C or greater, which was indicative of an all-or-none behavior. Forisome dispersion was suppressed by incubation with latrunculin A. In conclusion, the cytoskeleton controls cold shock-induced Ca(2+) influx into SEs, leading to forisome dispersion and sieve plate occlusion in fava bean (Vicia faba).
authors.affiliation: Plant Cell Physiology Group, Institute of Plant Physiology, Justus-Liebig-University, D-35390 Giessen, Germany. jens.hafke@bot1.bio.uni-giessen.de
authors.forename: Jens B
authors.initials: JB
authors.lastname: Hafke
authors.forename: Katrin
authors.initials: K
authors.lastname: Ehlers
authors.forename: Jens
authors.initials: J
authors.lastname: Föller
authors.forename: Sabina-Roxana
authors.initials: SR
authors.lastname: Höll
authors.forename: Stefanie
authors.initials: S
authors.lastname: Becker
authors.forename: Aart J E
authors.initials: AJ
authors.lastname: van Bel
mesh_terms: D000199:Actins / Q000502:physiology / Q000648:ultrastructure; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D058639:Cold-Shock Response / Q000502:physiology*; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000502:physiology*; D004594:Electrophysiology / Q000379:methods; D005456:Fluorescent Dyes / Q000032:analysis / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D010590:Phalloidine / Q000032:analysis / Q000378:metabolism; D053778:Thiazolidines / Q000494:pharmacology; D031307:Vicia faba / Q000187:drug effects / Q000502:physiology*
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D002121:Calcium Channel Blockers; D005456:Fluorescent Dyes; D053778:Thiazolidines; D010590:Phalloidine; D015638:Cytochalasin D; C037067:latrunculin A; D002118:Calcium