Table 2.

Cell–cell exchange coefficients for calcein in filaments of Anabaena sp. PCC7120

Measurement	Mean exchange coefficient (s−1) (±s.d.)
1. Wild-type vegetative cells in nitrate-grown filaments	0.021±0.011
2. Wild-type vegetative cells after 16 h of nitrate deprivation	0.057±0.039
3. Wild-type vegetative cells after 96 h of nitrate deprivation	0.28±0.12
4. Wild-type (vegetative cells to heterocysts) after 96 h of nitrate deprivation	0.035±0.012
5. ΔfraG vegetative cells in nitrate-grown filaments	0.007±0.008
6. ΔfraG vegetative cells after 16 h of nitrate deprivation	0.002±0.002
t-Tests indicate that E is significantly different in (1) and (2) (P=0.008); (2) and (3) (P=0.00002); (3) and (4) (P=0.0015); (1) and (5) (P=0.004); (2) and (6) (P=0.004); (4) and (5) (P=0.00008).