title: Localization of actin filaments on mitotic apparatus in tobacco BY-2 cells.
abstract: Actin filaments are among the major components of the cytoskeleton, and participate in various cellular dynamic processes. However, conflicting results had been obtained on the localization of actin filaments on the mitotic apparatus and their participation in the process of chromosome segregation. We demonstrated by using rhodamine-phalloidin staining, the localization of actin filaments on the mitotic spindles of tobacco BY-2 cells when the cells were treated with cytochalasin D. At prophase, several clear spots were observed at or near the kinetochores of the chromosomes. At anaphase, the actin filaments that appeared to be pulling chromosomes toward the division poles were demonstrated. However, as there was a slight possibility that these results might have been the artifacts of cytochalasin D treatment or the phalloidin staining, we analyzed the localization of actin filaments at the mitotic apparatus immunologically. We cloned a novel BY-2 alpha-type actin cDNA and prepared a BY-2 actin antibody. The fluorescence of the anti-BY-2 actin antibody was clearly observed at the mitotic apparatus in both non-treated and cytochalasin D-treated BY-2 cells during mitosis. The facts that similar results were obtained in both actin staining with rhodamine-phalloidin and immunostaining with actin antibody strongly indicate the participation of actin in the organization of the spindle body or in the process of chromosome segregation. Furthermore, both filamentous actin and spindle bodies disappeared in the cells treated with propyzamide, which depolymerizes microtubules, supporting the notion that actin filaments are associated with microtubules organizing the spindle body.
authors.affiliation: Cryobiosystem Research Center, Iwate University, Morioka, Iwate 020-8550, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yasuda
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Kanda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koiwa
authors.forename: Kayoko
authors.initials: K
authors.lastname: Suenaga
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Kidou
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Ejiri
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology; D006801:Humans; D008938:Mitosis; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism*; D014026:Nicotiana / Q000166:cytology*
chemical_list: D000199:Actins; D001549:Benzamides; D015638:Cytochalasin D; C001059:pronamide