Table I. Summary of t1/2 and percentages of mobile fraction for histone-GFP constructs measured in control and low-light conditions

t1/2 and mobile fraction were calculated based on the estimation of parameters of the adopted FRAP model (see “Materials and Methods”). For each plant organ, histone dynamics were measured in control and stress conditions. All values are averages of at least four sets of single-cell FRAP data (the number of cells is shown in parentheses). High and low values of t1/2 indicate low and high protein mobility, respectively. Mobile fraction indicates the percentage of the total protein pool not involved in stable interactions with chromatin. The presented values reflect characteristics of histone mobility during the first 70 s of the experiment. For histones whose fluorescence intensity does not reach a plateau within 70 s (Fig. 4), extending the time of measurement could result in higher t1/2 and lower mobile fraction estimates. A dash indicates that the parameters were not measured.

TreatmentHistonet1/2Mobile Fraction
RootHypocotylMeristemLeafRootHypocotylMeristemLeaf
s%
ControlH1.112.2 ± 0.8 (2)6.2 ± 0.6 (2)16.2 ± 1.3 (4)6.8 ± 0.5 (7)73.9 ± 1.9 (2)91.1 ± 3.4 (2)63.7 ± 2.0 (4)86.1 ± 2.4 (7)
H1.221.3 ± 1.8 (10)21.1 ± 1.3 (7)22.3 ± 4.0 (4)16.8 ± 1.2 (9)43.0 ± 1.5 (10)77.9 ± 2.0 (7)29.5 ± 2.2 (4)72.3 ± 2.0 (9)
H1.33.4 ± 0.3 (11)97.1 ± 3.4 (11)
H2B25.7 ± 4.4 (6)23.5 ± 5.2 (6)13.1 ± 2.6 (10)14.8 ± 1.9 (4)64.8 ± 5.0 (6)35.3 ± 3.4 (6)38.5 ± 2.7 (10)23.1 ± 1.1 (4)
StressH1.110.3 ± 0.8 (11)8.5 ± 0.5 (8)15.2 ± 0.8 (10)8.4 ± 0.5 (5)72.4 ± 2.0 (11)86.0 ± 1.9 (8)71.1 ± 1.4 (10)86.3 ± 2.1 (5)
H1.215.6 ± 1.0 (10)15.1 ± 0.6 (5)14.8 ± 2.2 (7)19.4 ± 1.3 (6)73.3 ± 1.7 (10)80.2 ± 1.2 (5)23.1 ± 1.2 (7)74.4 ± 2.0 (6)
H1.32 ± 0.3 (10)1.3 ± 0.2 (6)1.0 ± 0.1 (5)3.0 ± 0.2 (13)99.7 ± 6.7 (10)100.0 ± 10.0 (6)99.8 ± 10.7 (5)100.0 ± 2.6 (13)
H2B24.9 ± 4.2 (10)12.2 ± 0.8 (6)29.4 ± 5.1 (9)23.6 ± 3.1 (5)48.6 ± 3.7 (10)33.3 ± 0.8 (6)47.3 ± 4.0 (9)47.4 ± 2.7 (5)