title: Phototropin-dependent biased relocalization of cp-actin filaments can be induced even when chloroplast movement is inhibited.
abstract: In a recent publication using an actin-visualized line of Arabidopsis (Ichikawa et al. 2011, ref. 11), we reported a detailed analysis with higher time resolution on the dynamics of chloroplast actin filaments (cp-actin filaments) during chloroplast avoidance movement and demonstrated a good correlation between the biased configuration of cp-actin filaments and chloroplast movement. However, we could not conclusively determine whether the reorganization of cp-actin filaments into a biased configuration preceded actual chloroplast movement (and, thus, whether it could be a cause of the movement). In this report, we present clear evidence that the reorganization of cp-actin filaments into a biased distribution is induced even in the absence of the actual movement of chloroplasts. When the cells were treated with 2,3-butanedione monoxime (BDM), a potent inhibitor of myosin ATPase, chloroplast motility was completely suppressed. Nevertheless, the disappearance and biased relocalization of cp-actin filaments toward the side of the prospective movement direction were induced by irradiation with a strong blue light microbeam. The results definitively indicate that the reorganization of cp-actin filaments is not an effect of chloroplast movement; however, it is feasible that the biased localization of cp-actin filaments is an event leading to chloroplast movement.
authors: Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo, Japan.
authors: Noboru
authors: N
authors: Yamada
authors: Noriyuki
authors: N
authors: Suetsugu
authors: Masamitsu
authors: M
authors: Wada
authors: Akeo
authors: A
authors: Kadota
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism / Q000528:radiation effects*; D002736:Chloroplasts / Q000528:radiation effects*; D003931:Diacetyl / Q000031:analogs & derivatives / Q000494:pharmacology; D008027:Light; D056949:Phototropins / Q000378:metabolism*
chemical_list: D056949:Phototropins; C004717:diacetylmonoxime; D003931:Diacetyl