Fig 5.

Calcein FRAP in Anabaena PCC 7120 wild type and the amiC mutants. After loading of calcein-AM into the cells of the indicated strains and washing in medium, one cell (arrowhead) was bleached by a laser beam and the recovery of fluorescence monitored at the confocal microscope at different time points after bleaching. Shown are confocal images before (Pre) and directly after bleaching as well as at later time points in seconds. (A, B) Anabaena PCC 7120 wild type (WT) and amiC1 mutant SR477 (A) and amiC2 mutant SR478 (B). The arrowheads indicate the bleached cell. (C, D) To quantify FRAP, the quarter-time of equilibration (t_1/4) was calculated for six wild-type filaments and eight SR478 filaments of independent measurements. t_1/4 could not be accurately calculated for SR477 mutant cells, as these cells showed no substantial recovery within the recorded 80-s time interval. All quantifications were calculated as described previously (16).