Juvenile American shad (Alosa sapidissima) experience a wide range of temperatures in rivers before migrating to the ocean. Temperatures in these freshwater environments can vary greatly spatially, seasonally, year-to-year, and can be impacted by anthropogenic factors such as power plant discharge or climate change. Currently, there is uncertainty concerning juvenile American shad thermal tolerance due to a lack of a well-controlled study. Here, we report results of laboratory experiments to establish the upper thermal tolerance and heat shock protein response of juvenile American shad exposed to gradually increasing temperatures. Upper thermal tolerance was determined to be 35 °C (median; range = 34–36 °C) when fish were acclimated to 25 °C and temperatures were raised 1 °C day⁻¹. Heat shock protein response was indicated by changes in branchial mRNA abundance of the inducible heat shock protein 90 alpha (hsp90α), which was significantly elevated (more than 5-fold increase) at 30 °C, and highest in fish that had reached their upper thermal maximum between 34 and 36 °C. Our findings indicate a higher upper thermal tolerance than previously reported for juvenile American shad, and an onset temperature of hsp90α induction at 30 °C, a temperature juvenile American shad commonly experience during summer months.

中文翻译：

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美洲美洲d（Alosa sapidissima）的上耐热性和热激蛋白反应。

美洲美洲sha（Alosa sapidissima）在迁移到海洋之前会在河流中经历多种温度变化。这些淡水环境中的温度每年，每年在空间，季节上都会有很大的变化，并可能受到人为因素的影响，例如电厂排放或气候变化。目前，由于缺乏良好的对照研究，有关美洲美洲少年对树皮的耐热性尚不确定。在这里，我们报告实验室实验的结果，以建立暴露于逐渐升高的温度的美洲美洲American的较高耐热性和热激蛋白响应。上部热耐受性被确定为35℃（中位数，范围34-36 =℃）时鱼驯化至25℃和温度提出了1℃天^-1。可诱导的热休克蛋白90 alpha（hsp90α）的分支mRNA丰度变化指示了热休克蛋白的反应，该变化在30°C时显着升高（增加了5倍以上），并且在达到其上限的鱼中最高最高温度在34至36°C之间。我们的发现表明，较高的耐​​热性比以前报道的美国青少年sha鱼高，并且热休克蛋白90α诱导的起始温度为30°C，这是美国青少年d鱼在夏季通常经历的温度。