S63845 cell line Finally, at 1,022 μmol/(m2 s) of 440-nm light (bottom curve), Y(II) is suppressed to values close to zero during illumination and the recovery upon darkening displays two phases separated by a wide plateau, with 50-min dark-recovery amounting to 49 % only. After 12-h dark-recovery, the Y(II) of all samples except for the one illuminated at 1,170 μmol/(m2 s) recovered to values close to the original F v/F m (see inset of Fig. 9).

The red curve in Fig. 9 shows the responses observed when almost identical PAR(II) of 625-nm light is applied (1,088 μmol/(m2 s)) as in the measurement with the intermediate 440-nm intensity (419 μmol/(m2 s)). Hence, at equal PAR(II), the responses of 440- and 625-nm quanta are very AMN-107 in vivo similar, even when applied

over a longer period of time. At the end of illumination the Y(II) with 625 nm is just marginally higher than with 440 nm, similarly as in the LC-recordings of Fig. 8. There are, however, remarkable differences in the dark-recovery kinetics. After 625-nm illumination, the dark-recovery of Y(II) is distinctly faster than after 440-nm illumination, amounting to 97 % after 50 min. This shows clearly that the PS II turnover is not the only parameter affecting the quantum yield of PS II. Obviously, 440 nm selleck chemicals can lower the PS II quantum yield by an additional mechanism, which is induced at high light intensity and still is effective after 50-min dark-recovery. Concluding discussion and

outlook The presented data demonstrate that the new multi-color-PAM is more than just another PAM fluorometer offering various colors of light. The new dimension of this device relates to the precision, flexibility, and speed, with which the various colors of light can be applied, with the main aim of obtaining quantitative information on the rate of wavelength-dependent charge-separation in PS II reaction centers. This aim was reached via new developments at the levels of opto-electronics, microprocessor-based firmware and user software. Recent technical progress in LED technology made it possible to develop an extremely powerful miniature light source, which provides all the essential FER light qualities, for which in former days a whole bench of high-power light sources and flash-discharge lamps (or lasers) would have been required. With six separate colors of ML, six colors of AL (also serving for ST and MT flashes) and FR light, a total of 13 independent light sources are integrated on the 10 × 10 mm area of the multi-color-COB array. Such compact design enables optimal coupling of the light source to the 10 × 10 mm sample cuvette, assuring identical optical pathways of the various types of light. Close to optimal optical conditions are possible by use of low cell densities, as excellent signal/noise ratios are obtained at 200–300 μg Chl/L, where light-intensity gradients are negligibly small.