Wan Xiukun, Yao Ge, Wang Kang, Liu Yanli, Wang Fuli, Jiang Hui
State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
Microorganisms. 2023 Aug 31;11(9):2216. doi: 10.3390/microorganisms11092216.
Some dinoflagellates cause harmful algal blooms, releasing toxic secondary metabolites, to the detriment of marine ecosystems and human health. Phosphorus (P) is a limiting macronutrient for dinoflagellate growth in the ocean. Previous studies have been focused on the physiological response of dinoflagellates to ambient P changes. However, the whole-genome's molecular mechanisms are poorly understood. In this study, RNA-Seq was utilized to compare the global gene expression patterns of a marine diarrheic shellfish poisoning (DSP) toxin-producing dinoflagellate, , grown in inorganic P-replete and P-deficient conditions. A total of 148 unigenes were significantly up-regulated, and 30 unigenes were down-regulated under 1/4 P-limited conditions, while 2708 unigenes were significantly up-regulated, and 284 unigenes were down-regulated under 1/16 P-limited conditions. KEGG enrichment analysis of the differentially expressed genes shows that genes related to ribosomal proteins, glycolysis, fatty acid biosynthesis, phagosome formation, and ubiquitin-mediated proteolysis are found to be up-regulated, while most of the genes related to photosynthesis are down-regulated. Further analysis shows that genes encoding P transporters, organic P utilization, and endocytosis are significantly up-regulated in the P-limited cells, indicating a strong ability of to utilize dissolved inorganic P as well as intracellular organic P. These transcriptomic data are further corroborated by biochemical and physiological analyses, which reveals that under P deficiency, cellular contents of starch, lipid, and toxin increase, while photosynthetic efficiency declines. Our results indicate that has evolved diverse strategies to acclimatize to low P environments. The accumulation of carbon sources and DSP toxins could provide protection for to cope with adverse environmental conditions.
一些甲藻会引发有害藻华，释放有毒的次生代谢产物，对海洋生态系统和人类健康造成损害。磷（P）是海洋中甲藻生长的一种限制性常量营养素。以往的研究主要集中在甲藻对环境磷变化的生理反应上。然而，其全基因组的分子机制却知之甚少。在本研究中，利用RNA测序技术比较了一种产生海洋腹泻性贝类中毒（DSP）毒素的甲藻在无机磷充足和磷缺乏条件下生长时的全局基因表达模式。在1/4磷限制条件下，共有148个单基因显著上调，30个单基因下调；而在1/16磷限制条件下，2708个单基因显著上调，284个单基因下调。对差异表达基因的KEGG富集分析表明，与核糖体蛋白、糖酵解、脂肪酸生物合成、吞噬体形成和泛素介导的蛋白水解相关的基因被上调，而大多数与光合作用相关的基因被下调。进一步分析表明，编码磷转运蛋白、有机磷利用和内吞作用的基因在磷限制细胞中显著上调，这表明该甲藻具有很强的利用溶解无机磷以及细胞内有机磷的能力。这些转录组数据得到了生化和生理分析的进一步证实，结果显示在磷缺乏条件下，淀粉、脂质和毒素的细胞含量增加，而光合效率下降。我们的结果表明，该甲藻已经进化出多种策略来适应低磷环境。碳源和DSP毒素的积累可以为该甲藻提供保护，以应对不利的环境条件。
