It is also becoming possible, and will likely MX69 nmr be necessary, to develop mathematical models that take advantage of increasingly powerful computing power to encompass the true complexity of qE. It will be important that these models be capable of making falsifiable predictions that enable differentiation between different mechanisms of qE. Such developments should provide valuable, as understanding a detailed mechanism of qE would profoundly extend our understanding of the regulation of biological energy transduction and will likely provide useful design principles for the regulation of light harvesting in fluctuating light conditions. Acknowledgments We thank Matt Brooks, Alizée Malnoë,

and Anna Schneider for helpful comments on the manuscript and Doran Bennett and Eleonora De Re for helpful discussions. This work was supported by the Director, Office of Science, Office of Basic Energy

Sciences of the US Department of Energy under Contract DEAC02-05CH11231 and the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the US Department of Energy through Grant DE-AC03-76SF000098. EJ S-G was supported by a National Science Foundation Graduate Research Fellowship. Open AccessThis article is distributed under ARS-1620 mouse the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. Appendix A: Pulse amplitude modulated fluorescence A typical PAM trace of a wild type leaf of A. thaliana is shown in Fig. 2. At the beginning of the PAM trace, the actinic light source is off. Then, a 1-s learn more saturating flash is applied, and the maximum fluorescence measured during the flash is called F m. Using a simplified definition of chlorophyll quantum yield described in Ahn et al. (2009) and Hendrickson et al. (2005), we can write F m as $$ F_\rm m \propto \varPhi_F,F_\rm m

= \frack_\rm Fk_\rm F + k_\rm IC + k_\rm ISC, $$ (7)where \(\varPhi_F,F_\rm m\) is the fluorescence quantum yield during the measurement of F m and k F, k IC, and k ISC are the rate constants of decay for fluorescence, internal conversion, and intersystem crossing, respectively (Ahn et al. 2009). There, rate constant for photochemistry at the RC in the denominator Lepirudin is equal to 0 because the saturating pulse closes all RCs and temporarily blocks photochemistry. After the actinic light, bar at top of plot, is turned on, a saturating pulse is applied every minute. The actinic light remains on for 10 min, followed by darkness for 10 min. The maximum fluorescence yield during each of these pulses is called \(F_\rm m^\prime,\) $$ F_\rm m^\prime \propto \varPhi_F,F_\rm m^\prime = \frack_\rm Fk_\rm NPQ(T) + k_\rm F + k_\rm IC + k_\rm ISC, $$ (8)where k NPQ is the rate constant for dissipation by NPQ.