Irie Ryunosuke, Mikami Koji
Fisheries Promotion Division, Agriculture, Forestry and Fisheries Department, Oita Prefectural Government, 3-1-1 Otemachi, Oita 870-8501, Japan.
Department of Integrative Studies of Plant and Animal Production, School of Food Industrial Sciences, Miyagi University, 2-2-1 Hatatate, Taihaku-ku, Sendai 982-0215, Japan.
Plants (Basel). 2025 Jul 15;14(14):2194. doi: 10.3390/plants14142194.
In the marine red alga , filamentous phases of the life cycle, e.g., the conchocelis (sporophyte) and conchosporangium (conchosporophyte), proliferate by tip growth. In this study, we investigated the possible involvement of phosphoinositide turnover and actin polymerization in the spontaneous initiation and tip growth of new branches in isolated single-celled conchocelis cells using pharmacological treatments. Treatment with LY294002 and U73122, specific inhibitors of phosphoinositide-phosphate 3-kinase and phospholipase C, respectively, reduced side-branch formation and inhibited the elongation of branches. In addition, two inhibitors of the actin cytoskeleton, cytochalasin B (CCB) and latrunculin B (LAT-B), had similar effects on tip growth. However, CCB did not alter the branching rate of single-celled conchocelis, whereas LAT-B did. As CCB and LAT-B affect actin polymerization through different mechanisms, this result suggests differences in the contributions of actin polymerization to branch initiation versus tip growth. These findings demonstrate the critical and diverse functional roles played by phosphoinositide turnover and actin polymerization in the regulation of the initiation and maintenance of tip growth in the conchocelis phase of .
在海洋红藻中，生命周期的丝状阶段，例如壳孢子体（孢子体）和壳孢子囊（壳孢子体），通过顶端生长进行增殖。在本研究中，我们使用药理学处理方法，研究了磷酸肌醇代谢和肌动蛋白聚合在分离的单细胞壳孢子体细胞中新分支的自发起始和顶端生长过程中可能发挥的作用。分别用磷酸肌醇 - 磷酸3 - 激酶和磷脂酶C的特异性抑制剂LY294002和U73122处理，可减少侧枝形成并抑制分支伸长。此外，肌动蛋白细胞骨架的两种抑制剂，细胞松弛素B（CCB）和拉春库林B（LAT - B），对顶端生长具有类似的作用。然而，CCB并未改变单细胞壳孢子体的分支率，而LAT - B则有此作用。由于CCB和LAT - B通过不同机制影响肌动蛋白聚合，这一结果表明肌动蛋白聚合对分支起始和顶端生长的贡献存在差异。这些发现证明了磷酸肌醇代谢和肌动蛋白聚合在调控壳孢子体阶段顶端生长的起始和维持过程中所起的关键且多样的功能作用。
