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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 | 2016/11 |
| 形態種別 | 研究論文 |
| 査読 | 査読あり |
| 標題 | A New Morphological Type of Volvox from Japanese Large Lakes and Recent Divergence of this Type and V-ferrisii in Two Different Freshwater Habitats |
| 執筆形態 | その他 |
| 掲載誌名 | PLOS ONE |
| 出版社・発行元 | PUBLIC LIBRARY SCIENCE |
| 巻・号・頁 | 11(11),pp.e0167148 |
| 著者・共著者 | Hisayoshi Nozaki,Noriko Ueki,Nanako Isaka,Tokiko Saigo,Kayoko Yamamoto,Ryo Matsuzaki,Fumio Takahashi,Ken-ichi Wakabayashi,Masanobu Kawachi |
| 概要 | Volvox sect. Volvox is characterized by having unique morphological characteristics, such as thick cytoplasmic bridges between adult somatic cells in the spheroids and spiny zygote walls. Species of this section are found from various freshwater habitats. Recently, three species of Volvox sect. Volvox originating from rice paddies and a marsh were studied taxonomically based on molecular and morphological data of cultured materials. However, taxonomic studies have not been performed on cultured materials of this section originating from large lake water bodies. We studied a new morphological type of Volvox sect. Volvox ("Volvox sp. Sagami), using cultured materials originating from two large lakes and a pond in Japan. Volvox sp. Sagami produced monoecious sexual spheroids and may represent a new morphological species; it could be clearly distinguished from all previously described monoecious species of Volvox sect. Volvox by its small number of eggs or zygotes (5-25) in sexual spheroids, with short acute spines (up to 3 mu m long) on the zygote walls and elongated anterior somatic cells in asexual spheroids. Based on sequences of internal transcribed spacer (ITS) regions of nuclear ribosomal DNA (rDNA; ITS-1, 5.8S rDNA and ITS-2) and plastid genes, however, the Volvox sp. Sagami lineage and its sister lineage (the monoecious species V. ferrisii) showed very small genetic differences, which correspond to the variation within a single biological species in other volvocalean algae. Since V. ferrisii was different from Volvox sp. Sagami, by having approximately 100-200 zygotes in the sexual spheroids and long spines (6-8.5 mu m long) on the zygote walls, as well as growing in Japanese rice paddies, these two morphologically distinct lineages might have diverged rapidly in the two different freshwater habitats. In addition, the swimming velocity during phototaxis of Volvox sp. Sagami spheroids originating from large lakes was significantly higher than that of V. ferrisii originating from rice paddies, suggesting adaptation of Volvox sp. Sagami to large water bodies. |
| DOI | 10.1371/journal.pone.0167148 |
| ISSN | 1932-6203 |
| PMID | 27880842 |