Fig. 1

Light and fluorescence microscopic images of Zygnema circumcarinatum SAG 698-1b. The algae contain two stellate chloroplasts and one nucleus (center position) in each unbranched filamentous cell (a-g). a overview of filaments, b individual filament showing two massive pyrenoids in each cell (three cells are shown), c-d indian ink stained cell illustrating the mucilage layer (indicated by red arrowheads), e autofluorescence, f PI staining, g merged image of (e) and (f). DIC (Differential Interference Contrast) images were taken with an Axio Imager 2 microscope (a) or a Zeiss Axiovert 200 M microscope (b-d) and fluorescent images were taken with a Nikon Confocal Microscope (e, f, g). Scale bars: a: 50 µm, b-d: 10 µm, e–f: 10 µm