Peng Guotao, Lin Sijie, Fan Zhengqiu, Wang Xiangrong
Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092, China.
Toxins (Basel). 2017 May 17;9(5):168. doi: 10.3390/toxins9050168.
An important goal of understanding harmful algae blooms is to determine how environmental factors affect the growth and toxin formation of toxin-producing species. In this study, we investigated the transcriptional responses of toxin formation gene () and key photosynthesis genes (, and of FACHB-905 in different nutrient loading conditions using real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR). Three physio-biochemical parameters (malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH)) were also evaluated to provide insight into the physiological responses of cells. We observed an upregulation of gene in nutrient-deficient conditions, especially in nitrogen (N) limitation condition, and the transcript abundance declined after the nutrient were resupplied. Differently, high transcription levels were seen in phosphorus (P) deficient treatments for key photosynthesis genes throughout the culture period, while those in N-deficient cells varied with time, suggesting an adaptive regulation of cells to nutrient stress. Increased contents of antioxidant enzymes (SOD and GSH) were seen in both N and P-deficient conditions, suggesting the presence of excess amount of free radical generation caused by nutrient stress. The amount of SOD and GSH continued to increase even after the nutrient was reintroduced and a strong correlation was seen between the MDA and enzyme activities, indicating the robust effort of rebalancing the redox system in cells. Based on these transcriptional and physiological responses of to nutrient loading, these results could provide more insight into blooms management and toxin formation regulation.
了解有害藻华的一个重要目标是确定环境因素如何影响产毒物种的生长和毒素形成。在本研究中，我们使用实时逆转录定量聚合酶链反应（RT-qPCR）研究了不同营养负荷条件下毒素形成基因（）和关键光合作用基因（FACHB-905的、和）的转录反应。还评估了三个生理生化参数（丙二醛（MDA）、超氧化物歧化酶（SOD）和谷胱甘肽（GSH）），以深入了解细胞的生理反应。我们观察到在营养缺乏条件下，特别是在氮（N）限制条件下，基因上调，重新供应营养后转录丰度下降。不同的是，在整个培养期间，关键光合作用基因在缺磷处理中的转录水平较高，而在缺氮细胞中的转录水平随时间变化，这表明细胞对营养胁迫有适应性调节。在缺氮和缺磷条件下，抗氧化酶（SOD和GSH）的含量均增加，这表明营养胁迫导致自由基产生过量。即使重新引入营养后，SOD和GSH的量仍继续增加，并且MDA与酶活性之间存在很强的相关性，这表明细胞在努力平衡氧化还原系统。基于对营养负荷的这些转录和生理反应，这些结果可以为藻华管理和毒素形成调控提供更多见解。
