Department of Marine Ecology, College of Marine Life Science, Ocean University of China, Qingdao 266003, China.
Pilot Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
Toxins (Basel). 2021 Sep 8;13(9):629. doi: 10.3390/toxins13090629.
Impacts of ocean acidification (OA) on noncalcifying organisms and the possibly responsible mechanism have aroused great research interests with the intensification of global warming. The present study focused on a noxious, noncalcifying, bloom-forming dinoflagellate, (), and its variation of growth patterns exposed to different periods of seawater acidification with stressing gradients was discussed. The dinoflagellates under short-time acidifying stress (2d) with different levels of CO presented significant growth inhibition ( < 0.05). The cell cycle was obviously inhibited at S phase, and the photosynthetic carbon fixation was also greatly suppressed ( < 0.05). Apoptosis was observed and the apoptotic rate increased with the increment of CO. Similar tendencies were observed in the key components of mitochondrial apoptotic pathway (the mitochondrial membrane potential (MMP), Caspase-3 and -9, and Bax/Bcl-2 ratio). However, under prolonged stressing time (8 d and 15 d), the growth of dinoflagellates was recovered or even stimulated, the photosynthetic carbon fixation was significantly increased ( < 0.05), the cell cycle of division presented little difference with those in the control, and no apoptosis was observed ( > 0.05). Besides, acidification adjusted by HCl addition and CO enrichment resulted in different growth performances, while the latter had a more negative impact. The results of present study indicated that (1) the short-time exposure to acidified seawater led to reduced growth performance via inducing apoptosis, blocking of cell cycle, and the alteration in photosynthetic carbon fixation. (2) had undergone adaptive changes under long-term exposure to CO induced seawater acidification. This further demonstrated that has strong adaptability in the face of seawater acidification, and this may be one of the reasons for the frequent outbreak of red tide. (3) Ions that dissociated by the dissolved CO, instead of H itself, were more important for the impacts induced by the acidification. This work thus provides a new perspective and a possible explanation for the dominance of during the occurrence of HABs.
海洋酸化（OA）对非钙化生物的影响及其可能的作用机制，随着全球变暖的加剧，引起了人们的极大研究兴趣。本研究集中于一种有毒的、非钙化的、形成赤潮的甲藻（），并讨论了其在不同酸化胁迫时间下生长模式的变化。在不同 CO 水平的短期酸化胁迫（2d）下，甲藻的生长受到显著抑制（<0.05）。细胞周期在 S 期明显受到抑制，光合作用碳固定也受到很大抑制（<0.05）。观察到细胞凋亡，且随着 CO 的增加，凋亡率增加。在线粒体凋亡途径的关键成分（线粒体膜电位（MMP）、Caspase-3 和 -9 以及 Bax/Bcl-2 比值）中也观察到类似的趋势。然而，在长时间的胁迫下（8d 和 15d），甲藻的生长得到恢复甚至受到刺激，光合作用碳固定显著增加（<0.05），分裂的细胞周期与对照组相比没有差异，也没有观察到细胞凋亡（>0.05）。此外，通过 HCl 添加和 CO 富集来酸化海水会导致不同的生长表现，而后者的影响更为负面。本研究结果表明：（1）短期暴露于酸化海水中会通过诱导细胞凋亡、阻断细胞周期和改变光合作用碳固定来降低生长性能。（2）在长期暴露于 CO 诱导的酸化海水中，甲藻经历了适应性变化。这进一步证明了在面对海水酸化时，甲藻具有很强的适应性，这可能是赤潮频繁爆发的原因之一。（3）由溶解的 CO 离解的离子，而不是 H 本身，对酸化引起的影响更为重要。这项工作为赤潮发生时甲藻的优势提供了一个新的视角和可能的解释。
