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若林 憲一 所属 京都産業大学 生命科学部 産業生命科学科 職種 教授 |
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| 言語種別 | 英語 |
| 発行・発表の年月 | 2016/05 |
| 形態種別 | 研究論文 |
| 査読 | 査読あり |
| 標題 | Eyespot-dependent determination of the phototactic sign in Chlamydomonas reinhardtii |
| 執筆形態 | その他 |
| 掲載誌名 | PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA |
| 出版社・発行元 | NATL ACAD SCIENCES |
| 巻・号・頁 | 113(19),pp.5299-5304 |
| 担当区分 | 責任著者 |
| 著者・共著者 | Noriko Ueki,Takahiro Ide,Shota Mochiji,Yuki Kobayashi,Ryutaro Tokutsu,Norikazu Ohnishi,Katsushi Yamaguchi,Shuji Shigenobu,Kan Tanaka,Jun Minagawa,Toru Hisabori,Masafumi Hirono,Ken-ichi Wakabayashi |
| 概要 | The biflagellate green alga Chlamydomonas reinhardtii exhibits both positive and negative phototaxis to inhabit areas with proper light conditions. It has been shown that treatment of cells with reactive oxygen species (ROS) reagents biases the phototactic sign to positive, whereas that with ROS scavengers biases it to negative. Taking advantage of this property, we isolated a mutant, lts1-211, which displays a reduction-oxidation (redox) dependent phototactic sign opposite to that of the wild type. This mutant has a single amino acid substitution in phytoene synthase, an enzyme that functions in the carotenoid-biosynthesis pathway. The eyespot contains large amounts of carotenoids and is crucial for phototaxis. Most lts1-211 cells have no detectable eyespot and reduced carotenoid levels. Interestingly, the reversed phototactic-sign phenotype of lts1-211 is shared by other eyespot-less mutants. In addition, we directly showed that the cell body acts as a convex lens. The lens effect of the cell body condenses the light coming from the rear onto the photoreceptor in the absence of carotenoid layers, which can account for the reversed-phototactic-sign phenotype of the mutants. These results suggest that light-shielding property of the eyespot is essential for determination of phototactic sign. |
| DOI | 10.1073/pnas.1525538113 |
| ISSN | 0027-8424 |
| PMID | 27122315 |