Toxin variability during the cell cycle of the dinoflagellate Alexandrium fundyense
Toxin variability during the cell cycle of the dinoflagellate Alexandrium fundyense
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DOI：
10.4319/lo.1997.42.5_part_2.1178
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发表时间：
1997-07
影响因子：
4.5
通讯作者：
G. Taroncher-Oldenburg;D. Kulis;D. Anderson
中科院分区：
文献类型：
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作者：
G. Taroncher-Oldenburg;D. Kulis;D. Anderson
有毒甲藻Alexandrium fundyense Balech的培养在48h内被诱导两次同步分裂，在此间隔之前、期间和之后，每隔2 h监测一次毒素含量、毒素组成和其他几个生理参数，持续94h。毒素的产生是不连续的，受光诱导，并且总是在细胞周期的G1期内特定的时间范围内发生。在G1期早期的8-10h内，特定的毒素产生率为正，而在间期和有丝分裂的剩余时间内，∼的产毒率降至零。毒素成分分析表明，在一个世代时间内，所有麻黄毒素衍生物的细胞浓度都遵循相似的增加、稳定和下降的模式。可以建立一个假设的衍生物之间相互转化的序列，C2是第一个出现的化合物。在实验的第一个24小时内，种群的一个子集的分裂和随后的培养完全同步，表明这种甲藻的细胞周期存在两个转换点。第一个过渡点在G1的开始，依赖于光，并将细胞保持在类似G0的周期中。G1末尾的第二个块点依赖于大小，并阻止G1中的细胞。我们提出了一个真菌细胞周期的模型，在该模型中，细胞周期的进展可以在位于G1的两个不同的转换点停止，而毒素的产生在G1期由光诱导。将毒素产生限制在细胞周期的相对较短的部分，为比较正在和不正在合成毒素的细胞提供了一种工具。
Cultures of the toxic dinoflagellate Alexandrium fundyense Balech were subjected to conditions that induced two synchronized divisions over a period of 48 h. Before, during, and after this interval, toxin content, toxin composition, and several other physiological parameters were monitored every 2 h for 94 h. Toxin production was discontinuous, induced by light, and always occurred during a defined time frame within the G1 phase of the cell cycle. Specific toxin production rates were positive for a period of ∼8–10 h in early G1 and dropped to zero for the remainder of the interphase and mitosis. Analysis of toxin composition showed that cellular concentrations of all the saxitoxin derivatives followed a similar pattern of increase, stabilization, and decrease throughout one generation time. A putative sequence of interconversions between the derivatives could be established, with C2 as the first compound to appear. Division of a subset of the population during the first 24 h of the experiment and the ensuing total synchrony of the culture suggest the existence of two transition points in the cell cycle of this dinoflagellate. The first transition point, at the beginning of G1, is light‐dependent and holds the cells in a G0‐like period. The second block point at the end of G1 is size‐dependent and arrests the cells in G1. We propose a model of the cell cycle of A. fundyense in which progression through the cell cycle can be arrested at two different transition points located in G1 and toxin production is induced by light during G1. The restriction off toxin production to a relatively short segment of the cell cycle provides a tool for comparing cells that are and are not synthesizing toxin.