Variable thermal emission and chlorophyll fluorescence in photosystem II particles.

Abstract

In photosynthetic systems, the absorbed light energy is used to generate electron transport or it is lost in the form of fluorescence and thermal emission. While fluorescence can be readily measured, the detection of thermal deactivation processes can be achieved by the photoacoustic technique. In that case, the pressure wave generated by the thermal deactivations in a sample irradiated with modulated light is detected by a sensitive microphone. The relationships between the yield of fluorescence and thermal emissions measured simultaneously were analyzed by using a spinach photosystem II (PSH)-enriched preparation. It is shown that the quenching of fluo- In the photosynthetic apparatus, the absorbed light energy is either used to generate electron transport that is initiated by charge separation at the level of photosystems I and II (PSI and PSII), or the energy is lost through fluorescence and thermal emission. Fluorescence can be readily measured, but photoacoustic (PA) spectroscopy has been advantageously used to study the thermal deactivation processes in photosynthetic materials (1). In that case, a solid or semisolid sample is irradiated with modulated light in a closed cell. The thermal deactivations generate a periodic heat flow in the The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. surrounding gas medium that produces a pressure wave transduced into an electric signal by a sensitive microphone. Most usefully, the difference between the thermal emission yields ofactive and inactive samples allows the determination of the photochemical energy-storage yield (2). In most studies, the inactive sample with closed reaction centers was obtained by superimposition of a nonmodulated background light of saturating intensity on the low-intensity modulated measuring beam (3-6). The energy-storage yield has been correlated with the electron transport status (7,8), and it was suggested that electron transfer from water to the plastoquinone (PQ) pool was responsible for the stored energy (8-10).Similarly, part of the fluorescence emission (the so-called variable fluorescence) is closely related to the redox state of the secondary acceptors QA and QB in PSII and therefore is greatly influenced by the electron transport status (11). Thus, a strong interdependence between the yield of energy storage and the yield of variable fluorescence can be suggested (10). The correlation between chlorophyll (Chl) fluorescence and the PA signal has been studied in intact leaves (12, 13). However, the interpretations were complicated by the participation of PSI in the thermal signal and by a photobaric contribution due to oxygen evolution.A PSII submembrane fraction depleted of PSI should constitute the simplest model to study the relationship between variable fluorescence emission and thermal energy storage. The thermal emission behavior of such preparations has been...

Frequently asked questions about chlorophyll fluorescence, the sequel

“…Finally, P680 + is a strong quencher of Chl a fluorescence (Steffen et al 2005) and this effect allows the study of the different redox states (S states) the oxygen-evolving complex of PSII, due to the fact that the lifetime of P680 + is S state dependent. All of these things taken together could turn Chl a fluorescence into a indecipherable signal, but thanks to the development of specific protocols, and by using complementary techniques, the different effects can be separated, turning Chl a fluorescence into a powerful tool for the study of photosynthesis: quenching analysis (Bradbury and Baker 1981; Quick and Horton 1984; Schreiber et al 1986), JIP test (Strasser and Strasser 1995; Strasser et al 2004), non-photochemical quenching (NPQ) (Demmig and Winter 1988; Horton and Hague 1988), electron transport rate (ETR) (Genty et al 1989; Krall and Edwards 1990), rapid light curves (RLCs) (White and Critchley 1999; Ralph and Gademann 2005), flash-induced fluorescence (Robinson and Crofts 1983; de Wijn and van Gorkom 2001; Bouges-Bocquet 1980, Ioannidis et al 2000), dark-adaptation kinetics of OJIP transients (Bukhov et al 2001; Schansker et al 2005), Chl a fluorescence and photoacoustic spectroscopy (Buschmann and Koscányi 1989; Snel et al 1990; Allakhverdiev et al 1994; Bukhov et al 1997), Chl a fluorescence and 820-nm absorbance/transmission (Klughammer and Schreiber 1994; Schansker et al 2003), Chl a fluorescence and delayed fluorescence (Goltsev et al 2012; Kalaji et al 2012a), imaging (Nedbal and Whitmarsh 2004; Hideg and Schreiber 2007; Lichtenthaler et al 2007; Gorbe and Calatayud 2012), the actinic light wavelength dependence of photosynthesis (Schreiber et al 2012) and more recently attention has been paid to statistic aspects of the measurements of parameters (e.g., Bussotti et al 2011a). The photosynthetic literature is huge with many topics studied such as plant breeding (Baker and Rosenqvist 2004; Kalaji and Pietkiewicz 2004; Kalaji and Guo 2008), seed vigor and seed quality assessment (Jalink et al 1998; Dell’Aquila et al 2002; Konstantinova et al 2002), fruit and vegetable quality determination and postharvest processing control (Merz et al 1996; Nedbal et al 2000), senescence (Adams et al 1990a; Kotakis et al 2014), climate change effects (Ashraf and Harris 2004) and a variety of algae (Gorbunov et al 1999; Antal et al …”

Reconstruction of the Water‐Oxidizing Complex in Manganese‐Depleted Photosystem II Preparations Using Mononuclear Manganese Complexes

“…The photoacoustic-measuring beam was provided from a 150 W xenon lamp (ILC Technology, Sunnydale, CA) as reported (45)(46)(47). The intensity of this measuring beam (680 nm, 35 Hz) was 3 W m-2.…”

“…Simultaneous fluorescence and photoacoustic measurements were performed using a laboratory-constructed instrument composed of a photoacoustic cell (MTEC Photoacoustics Inc., Ames, IA) in combination with a PAM-101 chlorophyll fluorometer (Walz, Effeltrich, Germany) as previously described (45). The photoacoustic-measuring beam was provided from a 150 W xenon lamp (ILC Technology, Sunnydale, CA) as reported (45)(46)(47).…”

“…The DT20 samples (200 pL. 200 pg Chl/mL) were prepared by aspiration onto a nitrocellulose filter following a procedure described in detail elsewhere (45)(46)(47)(48)(49).…”

The correlation between the induction kinetics of the photoacoustic signal and chlorophyll fluorescence in barley leaves is governed by changes in the redox state of the photosystem II acceptor side. A study under atmospheric and high CO2concentrations

“…Hence, numerous studies have revealed strong correlations between the kinetic and magnitude of both signals (for examples see Havaux 1988;Allakhverdiev et al 1994;Markovic and Carpentier 1995). In dark-adapted intact leaves, the fast increase in chlorophyll fluorescence that follows the onset of actinic light was found to proceed simultaneously with a decline in the 0,-dependent component of the PA signal (Malkin 1987;Havaux 1988;Vredenberg et al 1992).…”