4b); #selleck chemicals llc randurls[1|1|,|CHEM1|]# interestingly, these variations were less marked for dgd1 than for the WT. Interpretation of these results is beyond the scope of this study. The only aspect of the temperature dependence that we want to point out is the strong decrease of the average lifetime above 50°C (reaching 83 ps at 65°C). For dgd1 the same sharp drop in τave occurs at lower temperatures and begins at around 45°C (Fig. 4b). Fig. 4 a Chlorophyll a fluorescence decay traces

for isolated thylakoid membranes from WT (thick line) and dgd1 (dashed line), recorded by TCSPC. The presented curves are the sums of five independent measurements on different preparations. The excitation wavelength is 430 nm, and the emission is recorded at 688 nm at 25°C. The corresponding fits (fluorescence lifetimes (τ) and relative amplitudes, given in brackets) are also presented. b Temperature dependence of the average fluorescence lifetime for the WT (filled square) and dgd1 (open circle). Details about the fitting procedure are described in “Materials and methods”. The lines (solid for WT and dashed for dgd1) serve as a guide to the eye. The average lifetime values and their standard errors are determined from five independent experiments Lipid matrix: lipid packing and membrane permeability In order to study the global physical

SB-715992 clinical trial properties of the lipid matrix of thylakoids, two methods were applied: (i) time-resolved fluorescence of MC540 in thylakoid membranes, which reports on the packing of the lipid molecules; and (ii) electrochromic absorbance transients on whole leaves, which probe the energization and the permeability of thylakoid membranes. Partition of MC540 in thylakoid membranes Using the three-exponential

model for the analysis of the fluorescence decay of MC540 (see also “Materials and methods”), lifetimes of 0.19–0.23 ns (Fig. 5a), 0.66–1.08 ns (Fig. 5b), and 1.71–2.15 ns (Fig. 5c) were obtained; the lifetimes shorten with the increase of temperature. In this article, they are referred to as 200-ps, 1-ns, and 2-ns components, respectively. Fig. 5 Temperature dependencies of the parameters, obtained after the analysis of the fluorescence decays recorded for MC540 in WT and dgd1 thylakoid membranes. a–c Lifetime Tobramycin components (blue symbols) and their respective amplitudes in WT (full black symbols) and dgd1 (open black symbols). d Weighted average lifetimes of the two long-lived components for WT (filled circle) and dgd1 (open circle). The samples were thermostated for 10 min at each temperature before starting the measurements. For further details for the fitting model see also “Materials and methods” and text As shown in Fig. 5a–c, the relative amplitudes of the different lifetime components of MC540 differ for WT and dgd1.