Figure 4.

77 K Fluorescence Emission Spectra of S. elongatus Cells Treated with Betaine.

Cells were dark adapted for 15 min (A) and (C) or incubated under blue light illumination (85 photons m⁻² s⁻¹) for 5 min (B) and (D). 77 K spectra were measured (dashed lines). Then, samples were taken after 5 min incubation with betaine (1 M) and measured (blue lines). Finally, State I (A) and (C) or State II (B) and (D) was tentatively induced by blue light illumination (85 µM photons m⁻² s⁻¹) or darkness, respectively, for 5 min more (red lines). The excitation was done at 430 nm (A) and (B) or 590 nm (C) and (D). Normalization was done at 800 nm, and the spectra are the average of at least three independent biological replicates.