Abstract Thallium (Tl) is the most toxic metal for mammals, likely due to its chemical similarity to the bioessential potassium (K). The biogeochemical cycle of Tl is susceptible to perturbation from a number of anthropogenic activities. Tl accumulation in the food chain may cause chronic Tl poisoning from dietary intake for human beings. However, Tl accumulation in the marine biosphere has largely been overlooked because high concentrations of K are thought to inhibit any uptake of Tl by organisms. Here, for the first time, high accumulation of Tl in the cytosol by the ubiquitous and abundant marine phytoplankton Emiliania huxleyi was found, making it readily transferable to higher trophic levels. Dose-response and physiological data were presented from a range of 9 species of phytoplankton under a wide range of Tl concentrations (1 ng L−1 to 1 mg L−1), spanning modern open ocean concentrations of 10–20 ng L−1, and higher concentrations in the coastal and fresh waters. Of all phytoplankton studied here, the cyanobacteria Synechococcus and the haptophytes Isochrysis galbana and Pavlova granifera have the largest tolerance to Tl toxicity, while the chlorophyte Micromonas pusilla has the least tolerance to elevated Tl. Haptophytes, especially isochrysidales, accumulated significantly more Tl intracellularly (up to 300-fold higher) than chlorophytes, making them good candidates for Tl bioremediation studies. Potassium transporters from E. huxleyi are found to be different from all other phytoplankton in this study based on analyses of the proteome. Since Tl is well known to be taken into cells by mistake through potassium channels, the difference of K channels in E. huxleyi may be responsible for its highest accumulation of Tl. As one of the most widely distributed phytoplankton in the ocean, the bioaccumulation of Tl in E. huxleyi may transfer and concentrate through the marine food chain and have significant impacts on the Tl biogeochemical cycle in the modern ocean.

中文翻译：

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铊与海洋浮游植物的相互作用

摘要 铊 (Tl) 是对哺乳动物毒性最大的金属，可能是由于其与生物必需钾 (K) 的化学相似性。Tl 的生物地球化学循环容易受到许多人为活动的干扰。Tl 在食物链中的积累可能会导致人类因饮食摄入而导致慢性 Tl 中毒。然而，海洋生物圈中的 Tl 积累在很大程度上被忽视了，因为高浓度的 K 被认为会抑制生物体对 Tl 的任何吸收。在这里，首次发现无处不在且丰富的海洋浮游植物 Emiliania huxleyi 在细胞质中大量积累 Tl，使其易于转移到更高的营养水平。剂量反应和生理数据来自 9 种浮游植物在各种 Tl 浓度（1 ng L-1 至 1 mg L-1）下的范围，涵盖现代公海浓度 10-20 ng L-1 ，在沿海和淡水中浓度更高。在这里研究的所有浮游植物中，蓝藻聚球藻和触生植物 Isochrysis galbana 和 Pavlova granifera 对 Tl 毒性的耐受性最大，而叶绿体 Micromonas pusilla 对升高的 Tl 耐受性最低。触生植物，尤其是异鞭藻类，在细胞内积累的 Tl 明显多于叶绿体（高达 300 倍），使它们成为 Tl 生物修复研究的良好候选者。来自 E 的钾转运蛋白。根据蛋白质组分析，在本研究中发现 huxleyi 与所有其他浮游植物不同。由于众所周知 Tl 会通过钾通道错误地进入细胞，因此 E. huxleyi 中 K 通道的差异可能是其最高的 Tl 积累的原因。作为海洋中分布最广泛的浮游植物之一，E. huxleyi中Tl的生物积累可能通过海洋食物链转移和浓缩，对现代海洋中的Tl生物地球化学循环产生重大影响。