School of Biological Sciences, University of Queensland , Brisbane QLD 4072 , Australia.
Biol Open. 2012 Sep 15;1(9):897-903. doi: 10.1242/bio.2012950. Epub 2012 Jul 20.
For the embryos and tadpoles of amphibian species, exposure to ultraviolet-B radiation (UVBR) can be lethal, or cause a variety of sublethal effects. Low temperatures enhance the detrimental effects of UVBR and this is most likely because the enzyme-mediated processes involved in the repair of UVBR-induced damage function less effectively at low temperatures. Whether these repair processes are also impaired, and thus the negative effects of UVBR similarly enhanced, at high temperatures is not known, but is an ecologically relevant question to ask given that organisms that inhabit environments where the temperature fluctuates widely on a daily timescale are likely to experience high doses of UVBR when temperatures are high. Here we examined the thermal-dependence of UVBR effects in the context of an ecologically-relevant fluctuating UVBR and temperature regime to test the hypothesis that exposure to peak UVBR levels while the temperature is high (35°C) is more detrimental to embryonic and larval Limnodynastes peronii than exposure to peak UVBR levels while the temperature is moderate (25°C). Embryos exposed to peak UVBR levels at 35°C hatched 10 h later than those exposed to peak UVBR levels at 25°C and, as tadpoles, were smaller and consequently swam more slowly but, in an environment with predators, exhibited no difference in survival time. There was also no effect of experimental treatment on the hatching success of embryos, nor on the post-hatch survival of tadpoles. These findings, therefore, are not sufficiently strong to support our hypothesis that high temperatures enhance the negative effects of UVBR in embryonic and larval amphibians.
对于两栖动物物种的胚胎和蝌蚪来说，暴露在紫外线-B 辐射（UVBR）下可能是致命的，或者会导致各种亚致死效应。低温会增强 UVBR 的有害影响，这很可能是因为参与修复 UVBR 诱导损伤的酶介导过程在低温下的效果较差。在高温下，这些修复过程是否也会受到损害，从而使 UVBR 的负面影响同样增强，目前尚不清楚，但这是一个具有生态相关性的问题，因为那些生活在温度每天波动很大的环境中的生物，当温度升高时，很可能会受到大量的 UVBR 照射。在这里，我们在一个与生态相关的 UVBR 和温度波动的环境中检查了 UVBR 效应的热依赖性，以检验这样一个假设，即在温度较高（35°C）时暴露于峰值 UVBR 水平对 Limnodynastes peronii 的胚胎和幼体比在温度适中（25°C）时暴露于峰值 UVBR 水平更具危害性。在 35°C 时暴露于峰值 UVBR 水平的胚胎比在 25°C 时暴露于峰值 UVBR 水平的胚胎晚孵化 10 小时，而且作为蝌蚪，它们更小，因此游得更慢，但在有捕食者的环境中，它们的存活时间没有差异。实验处理对胚胎的孵化成功率以及幼体孵化后的存活率也没有影响。因此，这些发现还不足以支持我们的假设，即高温会增强紫外线-B 在胚胎和幼体两栖动物中的负面影响。
