Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA.
Microb Ecol. 2012 Nov;64(4):1000-7. doi: 10.1007/s00248-012-0085-z. Epub 2012 Jul 6.
As ocean temperatures rise, investigations into what the physiological effects will be on the symbiotic microalga Symbiodinium, and how these may play into the cnidarian bleaching response, have highlighted the contribution of reactive oxygen species (ROS). Previous studies have laid this groundwork using a limited number of Symbiodinium phylotypes, and so this study aims to expand this understanding by exploring the effects of sub-lethal elevated temperatures on the physiological response of seven genetically distinct types of Symbiodinium, including A1, B1, B2, C1, D, E1, and F2. The production of ROS (at 26 °C, 29 °C, 30 °C, and 31 °C) and activity of the antioxidants catalase (CAT) and superoxide dismutase (SOD) (at 26 °C and 31 °C) were measured as indicators of sensitivity or tolerance to heat stress. Symbiodinium types B1 and C1 were the most thermally sensitive, with C1 producing the highest amount of ROS at elevated temperatures. Types A1 and F2 were tolerant, having no increase in ROS production, and were the only types to increase both CAT and SOD activity with temperature stress. Type B2 had decreased ROS production and elevation of CAT activity, while type E1 had decreased levels of ROS production at elevated temperatures. Type D was the only Symbiodinium type to remain unaffected by elevated temperatures. These results are consistent with previous findings of relative sensitivity or tolerance to elevated temperatures, specifically with regards to types A1, B1, and F2. The inclusion of types B2, C1, D, and E1 provides further new evidence of how types differ in their thermal responses, suggesting differing mechanisms exist in the Symbiodnium response to higher temperature and highlighting the importance of establishing symbiont identity when exploring the response of intact associations to this type of stress.
随着海洋温度的升高，对共生微藻 Symbiodinium 的生理影响以及这些影响如何影响刺胞动物白化反应的研究强调了活性氧物质（ROS）的作用。以前的研究已经使用有限数量的 Symbiodinium 类群为此奠定了基础，因此本研究旨在通过探索七种遗传上不同类型的 Symbiodinium（包括 A1、B1、B2、C1、D、E1 和 F2）在亚致死高温下对生理反应的影响来扩展这一认识。ROS 的产生（在 26°C、29°C、30°C 和 31°C 时）和抗氧化剂 CAT 和 SOD 的活性（在 26°C 和 31°C 时）被测量为对热应激敏感或耐受的指标。Symbiodinium 类型 B1 和 C1 对热最敏感，C1 在高温下产生最多的 ROS。A1 和 F2 型具有耐受性，ROS 产生没有增加，并且是唯一随温度应激增加 CAT 和 SOD 活性的类型。B2 型的 ROS 产生减少，CAT 活性升高，而 E1 型在高温下的 ROS 产生水平降低。D 型是唯一不受高温影响的 Symbiodinium 型。这些结果与以前关于升高温度的相对敏感性或耐受性的发现一致，特别是与 A1、B1 和 F2 类型有关。B2、C1、D 和 E1 类型的加入提供了更多关于它们对热响应的差异的新证据，这表明在 Symbiodinum 对更高温度的响应中存在不同的机制，并强调了在探索完整关联对这种类型的应激的反应时确定共生体身份的重要性。
