TABLE 4.
Characteristics of variable fluorescence (QA reduction and QA− reoxidation) of PS I-less strains measured in darkness in the presence of KCNa
| Genotype of strain | A (KCN) (AU) | A (increase) (AU) | t1/2 (increase) (s) | Fmax (AU) | t1/2 (decay) (s) |
|---|---|---|---|---|---|
| Parent | 0.39 ± 0.17 | 0.29 ± 0.12 | 35.3 ± 7.0 | 4.2 ± 1.0 | 2.5 ± 0.5 |
| ΔndbA | 0.44 ± 0.23 | 0.36 ± 0.20 | 44.3 ± 17.3 | 4.3 ± 1.0 | 2.3 ± 0.3 |
| ΔndbB | 0.38 ± 0.16 | 0.39 ± 0.17 | 44.8 ± 18.3 | 3.9 ± 0.7 | 1.8 ± 0.4 |
| ΔndbC | 0.30 ± 0.16 | 0.27 ± 0.06 | 33.7 ± 4.9 | 4.0 ± 1.1 | 2.1 ± 0.3 |
| ΔndbA ΔndbB | 0.29 ± 0.23 | 0.40 ± 0.28 | 41.4 ± 26.0 | 3.6 ± 1.0 | 1.4 ± 0.2 |
| ΔndbA ΔndbC | 0.28 ± 0.13 | 0.28 ± 0.23 | 39.8 ± 24.6 | 3.7 ± 1.2 | 1.8 ± 0.4 |
| ΔndbB ΔndbC | 0.20 ± 0.10 | 0.27 ± 0.12 | 41.6 ± 17.9 | 3.6 ± 1.1 | 1.7 ± 0.4 |
| ΔndbA ΔndbB ΔndbC | 0.31 ± 0.17 | 0.42 ± 0.37 | 42.0 ± 26.3 | 3.7 ± 1.2 | 1.7 ± 0.3 |
Values given are averages ± standard deviations from at least four determinations. Chlorophyll fluorescence of whole cells was measured in 10 mM HEPES–NaOH (pH 7.4) in the presence of 5 mM KCN. The amplitude of the immediate increase upon addition of KCN [A (KCN)], the amplitude and kinetics (t1/2) of the subsequent noninstantaneous and nonlinear increase in variable fluorescence [A (increase) and t1/2 (increase), respectively], the Fmax upon illumination with actinic light, and the t1/2 of decay after actinic illumination [t1/2 (decay)] are indicated. See Fig. 4 for an example of the experimental data from which these values were determined. AU, arbitrary units.