Fig. 4: Imaging intracellular endosymbiont Synechococcus by fluorescent microscopy.

a pTIRF microscopic images of Synechococcus cells, control yeast cells, and chimeric cells that were grown under selection conditions (Ex. = 561 nm; Em. = 653/95 nm). Panels are merged images of pTIRF (yellow) and brightfield microscopy (gray). The experiment was repeated three times independently with similar results. b Fluorescence confocal microscopy images of control yeast cells and chimeric cells, which were grown under selection conditions. The yeast cell wall was stained with Con A-FITC (green, Ex.  = 488 nm; Em. = 510/20 nm) and the presence of cyanobacteria was monitored by cyanobacterial fluorescence (red, Ex. = 561 nm; Em. = 650/20 nm). Based on these images, it is possible that multiple cyanobacterial cells could be present in some of the yeast cells. The experiment was repeated three times independently with similar results. c Panel a and b are cyanobacterial samples imaged by Transmission Electron Microscopy (TEM) and Panels c–f are fusions imaged by TEM. Yellow arrows show characteristic cyanobacterial structures within the cytoplasm of the yeast cells. The experiment was repeated twice independently with similar results.