Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China.
Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China; School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Harmful Algae. 2020 Jul;97:101868. doi: 10.1016/j.hal.2020.101868. Epub 2020 Jul 10.
Gymnodinium catenatum is able to produce paralytic shellfish toxins (PSTs) and was responsible for a massive bloom in the Taiwan Strait, East China Sea, in June 2017, which resulted in serious human poisoning and economic losses. To understand the origin of the bloom and determine the potential for blooms in subsequent years, water and sediment samples collected in the Taiwan Strait from 2016 to 2019 were analyzed for cells and cysts using light microscopy (LM) and/or quantitative polymerase chain reaction (qPCR). The morphology of both cells and cysts from the field and cultures was examined with LM and scanning electron microscopy (SEM). Large subunit (LSU) and/or internal transcribed spacer (ITS)-5.8S rRNA gene sequences were obtained in 13 isolates from bloom samples and five strains from cysts. In addition, cells of strains TIO523 and GCLY02 (from the Taiwan Strait and Yellow Sea of China, respectively) were subjected to growth experiments, and cysts from the field were used for germination experiments under various temperatures. Our strains shared identical LSU and ITS-5.8S rRNA gene sequences with those from other parts of the world, and therefore belonged to a global population. A low abundance of G. catenatum cells were detected during most of the sampling period, but a small bloom was encountered in Quanzhou on June 8, 2018. Few cysts were observed in 2016 but a marked increase was observed after the bloom in 2017, with a highest density of 689 cysts cm. Cysts germinated at temperatures between 14 and 23 °C with a final germination rate over 93%. Strains TIO523 and GCLY02 displayed growth at temperatures between 17 and 26 °C and 14 and 26 °C, respectively, with both strains displaying the highest growth rate of ca. 0.5 divisions d at 23 °C. The PSTs of the three strains and cysts from the sediments were analyzed by liquid chromatography with tandem mass spectrometry (LC-MS/MS). All strains were able to produce PSTs, which were dominated by N-sulfocarbamoyl C toxins (C1/2, 53.0-143.5 pg cell) and decarbamoyl gonyautoxins (dcGTX2/3, 26.7-52.1 pg cell), although they were not detected in cysts. However, hydroxybenzoyl (GC) toxins were detected in both cells and cysts. Our results suggested that the population in the Taiwan Strait belonged to a warm water ecotype and has a unique toxin profile. Our results also suggested that the persistence of cells in the water column may have initiated the bloom.
链状裸甲藻能够产生麻痹性贝类毒素（PSTs），并于 2017 年 6 月在中国台湾海峡和东海引发了大规模水华，导致严重的人类中毒和经济损失。为了了解水华的起源，并确定未来几年发生水华的可能性，我们对 2016 年至 2019 年在台湾海峡采集的水样和沉积物样本进行了细胞和胞囊的分析，采用的方法有：光学显微镜（LM）和/或实时定量聚合酶链反应（qPCR）。通过 LM 和扫描电子显微镜（SEM）对野外和培养的细胞和胞囊的形态进行了检查。从水华样本中获得了 13 株藻株和 5 株胞囊的大亚基（LSU）和/或内部转录间隔区（ITS）-5.8S rRNA 基因序列。此外，对来自台湾海峡的菌株 TIO523 和 GCLY02（中国黄海）的细胞进行了生长实验，对野外采集的胞囊在不同温度下进行了萌发实验。我们的菌株与来自世界其他地区的菌株具有相同的 LSU 和 ITS-5.8S rRNA 基因序列，因此属于一个全球种群。在大部分采样期间，检测到的链状裸甲藻细胞丰度较低，但在 2018 年 6 月 8 日在泉州遇到了一次小型水华。2016 年观察到的胞囊较少，但 2017 年水华后观察到胞囊数量明显增加，密度最高达 689 个胞囊 cm。胞囊在 14 至 23°C 之间萌发，最终萌发率超过 93%。TIO523 和 GCLY02 株在 17 至 26°C 和 14 至 26°C 之间生长，在 23°C 时生长速度最快，约为 0.5 分裂 d。通过液相色谱-串联质谱法（LC-MS/MS）对三株藻株和沉积物中的胞囊进行了 PST 分析。所有菌株都能够产生 PSTs，以 N-磺酰基碳酰胺 C 毒素（C1/2，53.0-143.5 pg 细胞）和去甲碳酰基 gonyautoxins（dcGTX2/3，26.7-52.1 pg 细胞）为主，尽管在胞囊中未检测到。然而，在细胞和胞囊中都检测到了羟基苯甲酰基（GC）毒素。我们的研究结果表明，台湾海峡的种群属于温水生态型，具有独特的毒素特征。我们的研究结果还表明，水柱中细胞的持续存在可能引发了水华。
