Lefebvre Sébastien, Mouget Jean-Luc, Loret Pascale, Rosa Philippe, Tremblin Gérard
Unité Mixte de Recherche 100 Ifremer-UCBN, Physiologie et écophysiologie des mollusques marins, Université de Caen Basse-Normandie, esplanade de la paix, 14032 Caen cedex, France.
J Photochem Photobiol B. 2007 Feb 1;86(2):131-9. doi: 10.1016/j.jphotobiol.2006.08.012. Epub 2006 Oct 9.
This study reports comparison of two techniques measuring photosynthesis in the ubiquitous diatom Skeletonema costatum, i.e., the classical oximetry and the recent modulated fluorimetry. Microalgae in semi-continuous cultures were exposed to five different environmental conditions simulating a seasonal effect with co-varying temperature, photoperiod and incident light. Photosynthesis was assessed by gross rate of oxygen evolution (P(B)) and the electron transport rate (ETR) measurements. The two techniques were linearly related within seasonal treatments along the course of the P/E curves. The light saturation intensity parameters (Ek and Ek(ETR)), and the maximum electron transport rate increased significantly with the progression of the season while the maximum light utilization efficiency for ETR (alpha(ETR)) was constant. By contrast, the maximum gross oxygen photosynthetic capacity (Pmax(B)) and the maximum light utilization efficiency for P(B) (alpha(B)) increased from December to May treatment but decreased from May to July treatment. Both techniques showed clear photoacclimation in microalgae with the progression of the season, as illustrated by changes in photosynthetic parameters. The relationship between the two techniques changed when high temperature, photoperiod and incident light were combined, possibly due to an overestimation of the PAR--averaged chlorophyll-specific absorption cross-section. Despite this change, our results illustrate the strong suitability of in vivo chlorophyll fluorimetry to estimate primary production in the field.
本研究报告了两种测量常见硅藻中肋骨条藻光合作用的技术的比较，即传统的血氧测定法和最新的调制荧光法。将半连续培养的微藻置于五种不同的环境条件下，模拟温度、光周期和入射光共同变化的季节效应。通过总放氧速率（P(B)）和电子传递速率（ETR）测量来评估光合作用。在季节性处理中，沿着P/E曲线，这两种技术呈线性相关。随着季节的推进，光饱和强度参数（Ek和Ek(ETR)）以及最大电子传递速率显著增加，而ETR的最大光利用效率（alpha(ETR)）保持不变。相比之下，最大总氧光合能力（Pmax(B)）和P(B)的最大光利用效率（alpha(B)）在12月至5月的处理中增加，但在5月至7月的处理中下降。随着季节的推进，两种技术都显示出微藻有明显的光适应现象，光合参数的变化说明了这一点。当高温、光周期和入射光同时出现时，两种技术之间的关系发生了变化，这可能是由于对PAR平均叶绿素比吸收截面的高估所致。尽管有这种变化，我们的结果表明活体叶绿素荧光法非常适合用于估算野外的初级生产力。
