Department of Biology, University of Oslo, Post Office Box 1027, Blindern, 0316 Oslo, Norway.
Oecologia. 2011 Apr;165(4):837-46. doi: 10.1007/s00442-010-1863-2. Epub 2010 Dec 12.
Alkaline phosphatase (AP) is a potential biomarker for phosphorus (P) limitation in zooplankton. However, knowledge about regulation of AP in this group is limited. In a laboratory acclimation experiment, we investigated changes in body AP concentration for Daphnia magna kept for 6 days at 10, 15, 20 and 25 °C and fed algae with 10 different molar C:P ratios (95-660). In the same experiment, we also assessed somatic growth of the animals since phosphorus acquisition is linked to growth processes. Overall, non-linear but significant relationships of AP activity with C:P ratio were observed, but there was a stronger impact of temperature on AP activity than of P limitation. Animals from the lowest temperature treatment had higher normalized AP activity, which suggests the operation of biochemical temperature compensation mechanisms. Body AP activity increased by a factor of 1.67 for every 10 °C decrease in temperature. These results demonstrate that temperature strongly influences AP expression. Therefore, using AP as a P limitation marker in zooplankton needs to consider possible confounding effects of temperature. Both temperature and diet affected somatic growth. The temperature effect on somatic growth, expressed as the Q (10) value, responded non-linearly with C:P, with Q(10) ranging between 1.9 for lowest food C:P ratio and 1.4 for the most P-deficient food. The significant interaction between those two variables highlights the importance of studying temperature-dependent changes of growth responses to food quality.
碱性磷酸酶 (AP) 是浮游动物磷限制的潜在生物标志物。然而，人们对该类群中 AP 的调控知之甚少。在一项实验室驯化实验中，我们研究了在 10、15、20 和 25°C 下饲养 6 天并喂食具有 10 种不同摩尔 C:P 比（95-660）的藻类的大型溞的体内 AP 浓度变化。在相同的实验中，我们还评估了动物的体生长情况，因为磷的获取与生长过程有关。总的来说，观察到 AP 活性与 C:P 比之间存在非线性但显著的关系，但温度对 AP 活性的影响强于磷限制。来自最低温度处理的动物具有更高的归一化 AP 活性，这表明存在生化温度补偿机制的作用。温度每降低 10°C，AP 活性就会增加 1.67 倍。这些结果表明温度强烈影响 AP 的表达。因此，在浮游动物中使用 AP 作为磷限制标志物需要考虑温度的可能混杂影响。温度和饮食都影响体生长。以 Q(10) 值表示的温度对体生长的影响与 C:P 呈非线性关系，Q(10) 值在最低食物 C:P 比时为 1.9，在最缺磷的食物时为 1.4。这两个变量之间的显著相互作用突出了研究温度依赖性变化对食物质量的生长响应的重要性。
