Figure 3.

Host-independency for Fm7001 in vivo filamentation. Merged GFP fluorescence and chlorophyll autofluorescence (red) and bright field micrographs of (A) Synechocystis, (B) Anabaena or (C) Fischerella cells expressing YFP-Fm7001. Cells were either grown in (A,B) BG11 or (C) BG11 without copper and then induced with 0.5 µM CuSO₄. (C) Micrographs were taken before induction of yfp-fm7001 expression (without induction) and 18 h, 36 h or 7 d post induction. White triangles point to selected YFP-Fm7001 filament-like strings within the cells. Notably, unlike in Anabaena and Fischerella, Fm7001-GFP induced a swollen morphotype in E. coli and a subpopulation of Synechocystis cells (Supplementary Fig. 1E). (B) Maximum intensity projection of a Z-stack. Scale bars: (A,B) 5 µm, (C) 10 µm.