Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, 400715, China.
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Sciences, Southwest University, Chongqing, 400715, China.
Harmful Algae. 2023 May;124:102406. doi: 10.1016/j.hal.2023.102406. Epub 2023 Feb 18.
As a tropical filamentous cyanobacterium, Raphidiopsis raciborskii has attracted much attention due to its expansion and toxin production. However, the mechanisms of its expansion to temperate regions have not been studied in detail. To address the potential strategies, the physiological and metabolomic profiles of R. raciborskii FACHB 1096 isolated from a temperate lake in China were determined and measured at different temperatures (10 °C, 15 °C, 20 °C, 25 °C, and 32 °C). The results demonstrated that temperature significantly changed cell viability, chlorophyll a content, specific growth rate, Chl a fluorescence, and filamentous shape of R. raciborskii. Low temperature decreased cell viability, specific growth rate, and photosynthetic efficiency, while the proportion of akinete and carbon fixation per unit cell were significantly increased compared with high temperature (32 °C). A constructed unimodal model indicated that filament length, cell volume, and cell length/width of R. raciborskii were significantly reduced in both high and low temperature environments. Under low-temperature conditions, R. raciborskii suffered different degrees of oxidative damage and produced corresponding antioxidant substances to resist oxidative stress, suggesting that low temperature changes the metabolic level of the cells, causing the cells to gradually switch from development to defense. Metabolomic data further confirmed that temperature change induced shifts in metabolic pathways in R. raciborskii, including starch and sucrose metabolic pathways, glutathione metabolic pathways, and the pentose phosphate pathways (PPP), as well as metabolic pathways related to the tricarboxylic acid (TCA) cycle. Our results indicated that the trade-offs of R. raciborskii cells among the growth, cell size, and metabolites can be significantly regulated by temperature, with broad implications for its global expansion in temperate waterbodies.
作为一种热带丝状蓝藻，拉氏拟鱼腥藻由于其扩张和产生毒素而受到广泛关注。然而，其向温带地区扩张的机制尚未得到详细研究。为了解决这个问题，我们测定了分离自中国温带湖泊的拉氏拟鱼腥藻 FACHB 1096 在不同温度（10°C、15°C、20°C、25°C 和 32°C）下的生理和代谢组学特征。结果表明，温度显著改变了拉氏拟鱼腥藻的细胞活力、叶绿素 a 含量、比生长速率、Chl a 荧光和丝状形态。低温降低了细胞活力、比生长速率和光合作用效率，而与高温（32°C）相比，似囊体和单位细胞的碳固定比例显著增加。构建的单峰模型表明，拉氏拟鱼腥藻的丝状长度、细胞体积和细胞长度/宽度在高温和低温环境下均显著减小。在低温条件下，拉氏拟鱼腥藻受到不同程度的氧化损伤，并产生相应的抗氧化物质来抵抗氧化应激，这表明低温改变了细胞的代谢水平，使细胞逐渐从发育转向防御。代谢组学数据进一步证实，温度变化诱导了拉氏拟鱼腥藻代谢途径的变化，包括淀粉和蔗糖代谢途径、谷胱甘肽代谢途径和戊糖磷酸途径（PPP），以及与三羧酸（TCA）循环相关的代谢途径。我们的研究结果表明，温度可以显著调节拉氏拟鱼腥藻细胞在生长、细胞大小和代谢物之间的权衡，这对其在温带水体中的全球扩张具有广泛的意义。
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