TABLE 2 .

Rates of calcein and 5-CF exchange between wild-type and mutant vegetative Anabaena cells^a

Anabaena strain	Mean R (s−1) ± SD (n)
	Calcein	5-CF
PCC 7120 (wild type)	0.097 ± 0.023 (18)	0.080 ± 0.013 (37)
CSVM34 (ΔsepJ)	0.023 ± 0.007 (12)	0.054 ± 0.007 (54)
CSVT22 (ΔfraC ΔfraD)	0.015 ± 0.003 (21)	0.017 ± 0.003 (42)
CSVM141 (ΔsepJ ΔfraC ΔfraD)	0.028 ± 0.006 (21)	0.022 ± 0.002 (84)

^aCalcein and 5-CF were loaded into cells of BG11-grown filaments of the strains indicated, the tracer was bleached in one cell, and the fluorescence recovery rate constant, R, was determined as described in Materials and Methods. Data are mean values ± SDs (12 to 84 filaments were analyzed for each strain and tracer). Student’s t tests indicate that differences in calcein transfer between strains PCC 7120 and CSVM34 and between PCC 7120 and CSVT22 are significant (P < 10⁻⁴) and the difference between CSVM141 and CSVT22 might also be significant (P = 0.04). Differences in 5-CF transfer between strains PCC7120 and CSVM34, PCC7120 and CSVT22, CSVM34 and CSVT22, and CSVM141 and CSVT34 are all significant (P < 10⁻⁵).