Scottish Association for Marine Science, Scottish Marine Institute, Oban PA37 1QA, UK; Marine Biological Section, Department of Biology, University of Copenhagen, Universitetsparken 4, Copenhagen Ø, DK-2100, Denmark.
Marine Scotland Science, 375 Victoria Road, Aberdeen AB11 9DB, UK.
Harmful Algae. 2016 Mar;53:135-144. doi: 10.1016/j.hal.2015.11.010. Epub 2016 May 3.
The dinoflagellate Alexandrium produces paralytic shellfish poisoning toxins. The genus is globally distributed, with Scottish waters being of particular interest due to the co-occurrence of different species and strains. In Scottish waters, Alexandrium was historically thought to be dominated by the highly toxic (Group I) Alexandrium fundyense. However, the morphologically indistinguishable (Group III) Alexandrium tamarense has recently also been found to co-occur, raising important questions in relation to Alexandrium biogeography. To begin to address these, we investigated Alexandrium growth, yield and toxin production in a range of temperature conditions characteristics of present and potential future conditions, using a recently developed flow cytometry method that allowed, for the first time, simultaneous enumeration of the cryptic species in co-culture. Experiments were undertaken in a range of temperatures (12, 15, 18 and 21°C) in the phosphate (P) limiting conditions that promotes A. fundyense toxicity. Cell/biomass yield was greater for A. tamarense at all temperatures, with observed growth rates varying with temperature. Growth rather and yield were different in mono- and co-culture with the outcome of these interactions also being temperature dependent. For toxic A. fundyense, GTX-3, STX and NEO were the dominant analogues, but total toxicity, toxicity per cell and the number of, and relative proportion of, toxin analogues changed in relation to the onset of P limitation and also as a function of temperature, with the highest toxin concentrations per cell being observed at 12°C. Toxin concentrations were approximately double in P limited stationary phase compared to exponential growth. Toxin concentrations were lower in the co-cultures, indicating inhibition of production in the presence of non-toxic A. tamarense. The strong performance of A. tamarense is in co-culture at odds with the historical understanding that Scottish waters were dominated by A. fundyense and indicates that changes in water temperatures, and also potentially alleopathic interactions, will influence Alexandrium populations and hence the PSP toxicity threat to humans from shellfish.
甲藻产生麻痹性贝类毒素。该属分布广泛，苏格兰水域因其不同物种和菌株的共存而特别引人注目。在苏格兰水域，历史上认为剧毒的（I 组）亚历山大藻丰度是主要存在的。然而，最近也发现形态上无法区分的（III 组）亚历山大藻塔玛也共存，这就提出了与亚历山大藻生物地理学有关的重要问题。为了开始解决这些问题，我们在一系列温度条件下（代表当前和潜在未来条件）研究了亚历山大藻的生长、产量和毒素产生，这些温度条件采用了最近开发的一种流式细胞术方法，该方法首次允许在共培养中同时对隐种进行计数。在磷酸盐（P）限制条件下（促进 A. fundyense 毒性），在一系列温度（12、15、18 和 21°C）下进行了实验。A. tamarense 在所有温度下的细胞/生物量产量都更高，观察到的生长速率随温度而变化。在单独培养和共培养中，生长和产量都不同，这些相互作用的结果也取决于温度。对于有毒的 A. fundyense，GTX-3、STX 和 NEO 是主要的类似物，但总毒素、毒素/细胞和毒素类似物的数量和相对比例随着 P 限制的开始以及温度的变化而变化，在 12°C 时观察到每个细胞的最高毒素浓度。与指数生长相比，在 P 限制的静止期，毒素浓度增加了大约两倍。在共培养中，毒素浓度较低，表明在无毒的 A. tamarense 存在下，毒素的产生受到抑制。A. tamarense 在共培养中的良好表现与历史上认为苏格兰水域主要由 A. fundyense 主导的观点相矛盾，这表明水温的变化，以及潜在的化感相互作用，将影响亚历山大藻种群，从而影响到人类因贝类而摄入 PSP 毒素的威胁。
