Direct estimation of functional PSII reaction center concentration and PSII electron flux on a volume basis: a new approach to the analysis of Fast Repetition Rate fluorometry (FRRf) data
Direct estimation of functional PSII reaction center concentration and PSII electron flux on a volume basis: a new approach to the analysis of Fast Repetition Rate fluorometry (FRRf) data
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DOI：
10.4319/lom.2012.10.142
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发表时间：
2012-03-01
影响因子：
2.7
通讯作者：
Geider, Richard J.
中科院分区：
文献类型：
--
作者：
Oxborough, Kevin;Moore, C. Mark;Geider, Richard J.
浮游植物初级生产力最常通过碳 - 14同化作用来测量，不过诸如氧 - 2交换等不太直接的方法也有被采用。这些方法是侵入性的，需要将瓶子培养长达24小时。作为一种替代方法，快速重复率荧光测定法（FRRf）已在水生系统内广泛的时间和空间尺度上被用于估算单位体积的光系统II（PSII）电子通量（JV(PSII)），它通常与光合氧 - 2释放密切相关。使用FRRf的一个主要限制源于需要采用一种独立的方法来确定功能性光系统II反应中心的浓度（[RCII]）；这一要求使得FRR荧光计无法作为独立仪器用于电子传递的估算。在本研究中，我们基于一个简单的假设，对FRRf数据的分析采取了一种新方法；即在一组给定的环境条件下，对于所有浮游植物类群，RCII荧光发射和光化学的速率常数之比处于一个狭窄的范围内。我们提出了一个简单的方程，它由已确立的FRRf算法推导而来，仅从暗FRRf数据就能确定[RCII]。我们还描述了一种全新的估算JV(PSII)的算法，该算法不需要确定[RCII]，并且对于RCII之间连接的异质性模型是有效的。文中给出了经验性的支持证据。这些数据来自对多种微藻的FRR测量，同时还有对[RCII]的独立测量。文中还讨论了可能的误差来源，特别是在营养胁迫条件下的误差来源。
Phytoplankton primary productivity is most commonly measured by C-14 assimilation although less direct methods, such as O-2 exchange, have also been employed. These methods are invasive, requiring bottle incubation for up to 24 h. As an alternative, Fast Repetition Rate fluorometry (FRRf) has been used, on wide temporal and spatial scales within aquatic systems, to estimate photosystem II (PSII) electron flux per unit volume (JV(PSII)), which generally correlates well with photosynthetic O-2 evolution. A major limitation of using FRRf arises from the need to employ an independent method to determine the concentration of functional photosystem II reaction centers ([RCII]); a requirement that has prevented FRR fluorometers being used, as stand-alone instruments, for the estimation of electron transport. Within this study, we have taken a new approach to the analysis of FRRf data, based on a simple hypothesis; that under a given set of environmental conditions, the ratio of rate constants for RCII fluorescence emission and photochemistry falls within a narrow range, for all groups of phytoplankton. We present a simple equation, derived from the established FRRf algorithm, for determining [RCII] from dark FRRf data alone. We also describe an entirely new algorithm for estimating JV(PSII), which does not require determination of [RCII] and is valid for a heterogeneous model of connectivity among RCIIs. Empirical supporting evidence is presented. These data are derived from FRR measurements across a diverse range of microalgae, in parallel with independent measurements of [RCII]. Possible sources of error, particularly under nutrient stress conditions, are discussed.