Wenzhou Key Laboratory of Sanitary Microbiology, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
Department of Medical Laboratory Technology, Xinyang Vocational and Technical College, Xinyang, Henan 464000, China.
Harmful Algae. 2022 Jan;111:102167. doi: 10.1016/j.hal.2021.102167. Epub 2021 Dec 23.
The HAB-forming, toxic dinoflagellate Karenia mikimotoi, previously found to benefit from ocean acidification (OA), was cultivated to investigate its transcriptional response to simulated OA for 30 generations. Batch cultures were grown under two CO concentrations, 450 (control) and 1100 (simulated OA) μatm, and physiological parameters [growth, pigments, catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD) activity], as well as transcriptomes (obtained via RNA-seq), were compared. Chlorophyll a (Chl a) and carotenoid (Caro) contents, as well as CAT and GR activities, were significantly increased under OA conditions. Transcriptomic analysis revealed 2,490 differentially expressed unigenes in response to OA, which comprised 1.54% of all unigenes. A total of 1,121 unigenes were upregulated, and 1,369 unigenes were downregulated in OA compared to control conditions. The downregulated expression of bicarbonate transporter and carbonic anhydrase genes was a landmark of OA acclimation. Key genes involved in energy metabolism, e.g., photosynthesis, tricarboxylic acid cycle, oxidative phosphorylation, and nitrogen metabolism, were highly upregulated under OA, contributing to increases in the Chl a (55.05%) and Caro (28.37%). The enhanced antioxidant enzyme activities (i.e. CAT, GR) and upregulated genes (i.e. glutathione peroxidase, ascorbate peroxidase, heat shock protein, 20S proteasome, aldehyde dehydrogenase, and apolipoprotein) benefit cells against the potential lower pH stress condition under OA. In addition, the downregulation of four genes associated with motility suggested that the preserved energy could further boost growth. In conclusion, the present study suggests that K. mikimotoi exhibits efficient gene expression regulation for the utilization of energy and resistance to OA-induced stress. Taken together, K. mikimotoi appeared as a tolerant species in response to OA. Thus, more extensive algal blooms that threaten marine organisms are likely in the future. These findings expand current knowledge on the gene expression of HAB-forming species in response to future OA.
产麻痹性贝毒的有毒甲藻米氏凯伦藻，先前被发现受益于海洋酸化（OA），本研究对其进行了 30 代的模拟 OA 培养，以研究其转录响应。在两种 CO 浓度下（450 个大气压（对照）和 1100 个大气压（模拟 OA））培养分批培养物，并比较了生理参数[生长、色素、过氧化氢酶（CAT）、谷胱甘肽还原酶（GR）和超氧化物歧化酶（SOD）活性]以及转录组（通过 RNA-seq 获得）。在 OA 条件下，叶绿素 a（Chl a）和类胡萝卜素（Caro）含量以及 CAT 和 GR 活性显著增加。转录组分析显示，有 2490 个差异表达的 unigene 对 OA 有响应，占所有 unigene 的 1.54%。与对照条件相比，OA 条件下共有 1121 个 unigene 上调，1369 个 unigene 下调。碳酸氢盐转运体和碳酸酐酶基因的下调表达是 OA 适应的标志。参与能量代谢的关键基因，如光合作用、三羧酸循环、氧化磷酸化和氮代谢，在 OA 下高度上调，导致 Chl a（55.05%）和 Caro（28.37%）增加。增强的抗氧化酶活性（即 CAT、GR）和上调的基因（即谷胱甘肽过氧化物酶、抗坏血酸过氧化物酶、热休克蛋白、20S 蛋白酶体、醛脱氢酶和载脂蛋白）使细胞受益于 OA 下潜在的更低 pH 应激条件。此外，与运动性相关的四个基因的下调表明，保留的能量可以进一步促进生长。总之，本研究表明，米氏凯伦藻在能量利用和抵抗 OA 诱导的应激方面表现出有效的基因表达调控。总之，米氏凯伦藻在应对 OA 时表现出较强的耐受性。因此，未来海洋生物可能会受到更多威胁的藻类大量繁殖。这些发现扩展了关于产麻痹性贝毒的有毒甲藻米氏凯伦藻在应对未来 OA 时的基因表达的现有知识。
