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Some observations on carpospore adherence in Polysiphonia japonica Harvey

By 武男 沢田, 直 古賀, 賛平 内山, Takeo Sawada, Sunao Koga and Sanpei Uchiyama

Abstract

In order to investigate the mechanism of spore attachment in red algae, some observations and experiments were conducted. As the material, Polysiphonia japonica Harvey was chosen chiefly because of the following reasons; 1) Polysiphonia produces comparatively large spores which have the advantage of being closely observed through a microscope with a high-power objective, 2) this alga is available for such a long period in winter as repeated trials are possible, 3) since this is epiphytic to develop in abundance on some intertidal species of Sargassum, it is easy to obtain the material. Carpospores are preferable to tetraspores, for it is not necessary to examine material with a microscope whether it is sterile or not. A small glass vessel of 5×8×2.5 cm was made, and for one of its planes a thin glass plate of 5×8 cm, 0.13 -0.17 mm in thickness, was used so as to observe the inside spores horizontally. 1) Spores sink at an average speed of 93 μ/sec, that is 10.8 sec/mm. Though this speed is the fastest example among the reported ones, it is still slow enough to take time to reach a substratum. 2) When sinking spores touched the slide glass with a 45°-angle of slope, no spores were observed that adhered immediately, but they moved down instead. Moving progress of each spore was successfully observed with 7 instances, and time, distance, and speed were recorded. They usually moved down sliding, but sometimes rolling. Besides, 36 more instances were measured in which the moving of spores was not observed in succession from the beginning to the end. On many occasions spores moved down at a speed of approximately 1mm/min, but the speed was variable in each spore and even the same spore changed the speed irregularly. In most cases the range of speed was about between 0.5 and 1.5 mm/min, and here are two records with the longest time and distance confirmed; 7.2 mm in 18.9 minutes, 11.5 mm in 8.5 minutes. 3) The slide glass mentioned above was slid along its direction for 1 cm and back at different speeds 5 minutes after the spore stopped. In the case of a 10 mm/sec speed, no spores remained, but in the case of a 1 mm/sec, each one was still observed at its place. Since there are only a few results available, it can follow that some spores may settle on the glass in the stiring water with the speed of more than 10 mm/sec. 4) A slide glass was placed horizontally and was moved along its direction or vertically at the speed of 1 cm/sec at different interval after each spore touched it. Even in the case when the glass was moved just after a spore touched it, the spore remained there at a high rate. It is evident that the spores are embedded in mucilage which is released together with the spores.紅藻胞子の付着機構を追究する手段として,沈降してきた胞子が基盤に接触する前後の経過を観察し,また付着力に関する二,三の実験を行なつた.キブリイトグサの果胞子を対象としたが,これは大きさが大で観察が容易であることが主な理由の一つである. 1. 胞子の沈降速度は平均10.8sec/mmで従来の他種での報告よりは速いが,巨視的にみれば非常におそく,水の流動と共に長時間水中を浮遊する. 2. 45度の斜面上に落下した胞子はすぐ付着した例はなく,全て下方に流下した.その際の速度は不規則に増減したが,半数近くの平均速度は約1mm/min,多くのもので0.5~1.5mm/minであつた.特殊な例として時間では18分52秒以上,距離では11.5mm以上流下した例も観察した. 3. 斜面上で流下が止まつてから5分後にいろいろの速さで基盤を動かしたところ,10mm/secではもとの位置にとどまつていた例はなかつたが,1mm/secでは全てとどまつていた.しかし天然での生育状態や他種の例から考えて10mm/sec,もしくはそれ以上の流速でも,観察例を増せば付着する場合もあり得ると思われる. 4. 沈降してきた胞子が水平基盤上に接した瞬間,基盤を水平あるいは垂直に動かしても,大部分の胞子は基盤上の位置が変わらなかつた.果胞子と共にのう果から放出された粘液によつて埋められていた状態と考えられる

Topics: 紅藻, 胞子, 付着機構, キブリイトグサ, 果胞子, のう果, 粘液
Publisher: Faculty of Agriculture, Kyushu University
Year: 1972
OAI identifier: oai:catalog.lib.kyushu-u.ac.jp:2324/23081
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