Poster: Cytoskeleton: Structure & Function
Abs #
1113: Rapid regulation of actin-dependent cytoplasmic motility by type II phytochrome in Vallisneria epidermal cells
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Presenter: |
Takagi, Shingo , shingot@bio.sci.osaka-u.ac.jp | Authors | Takagi, Shingo (A) Kong, Sam-Geun (B) Mineyuki, Yoshinobu (C) Furuya, Masaki (D) | | Affiliations: |
(A): Dept. Biol., Grad. Sch. Sci., Osaka Univ.
(B): Dept. Bot., Grad. Sch. Sci., Kyoto Univ.
(C): Dept. Biol. Sci., Grad. Sch. Sci., Hiroshima Univ.
(D): Hitachi Advanced Research Laboratory
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Using an infrared light microscope equipped with a custom-made dynamic image analyzer, we investigated the effects of light on actin-dependent cytoplasmic motility in epidermal cells of green leaves of the aquatic monocot .Vallisneria gigantea. Cytoplasmic motility was photoreversibly accelerated and decelerated by irradiation with red and far-red light of low fluence. Anti-phytochrome B antibody-responsive polypeptide(s) was detected in the leaf extract by immuno- and zinc-blot analyses and in cryosections of the epidermis by immunocytochemistry. The red-light-induced cytoplasmic motility did not occur uniformly in cytoplasm but took place in a patchy manner. The cytoplasmic motility was induced as early as a few seconds after the start of a pulse irradiation with red light. In a microbeam irradiation study, cytoplasmic motility was induced only in areas in the cytoplasm that were directly exposed to actinic light, while non-exposed neighboring areas were unaffected. The effect of microbeam irradiation was short-lived and disappeared within several minutes. Signal did not seem to be transmitted from an irradiated cell to its neighbors. While the anti-actin cytoskeleton reagents completely blocked the induction of cytoplasmic motility, treatment of the dark-adapted cells with Ca2+-chelating reagents induced the cytoplasmic motility even in darkness. From the results, we proposed a model for regulation of cytoplasmic motility by type II phytochrome as one of the earliest responses to a light stimulus in plant cells.
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