Fig. 4: Epifluorescence and confocal microscopy-based PG insertion pattern in S. muelleri and C. steedae.

Phase contrast images (left panels), corresponding epifluorescence images (middle panels) and enlarged selected regions (right panels; the white frames indicate the selected regions) of S. muelleri (a) labeled with HADA, BADA and TADA for 1 h, 30 min and 30 min, respectively and of C. steedae (b) labeled with HADA, BADA and TADA for 1 h, 45 min and 45 min, respectively. Scale bars are 5 µm (middle panels) and 1 µm (right panels). c For two representative S. muelleri septa (septum 1 and septum 2, left and right panel), fluorescence of HADA, BADA and TADA was plotted onto the long axis. Scale bars are 5 µm (left and middle panel) and 1 µm (right panel). Source data are provided as a Source Data file. d Schematic representation of S. muelleri and C. steedae growth mode. e Confocal images of one C. steedae filament labeled with HADA, BADA and TADA for 1 h, 45 min and 45 min, respectively (top panels). Top left panel displays the filament from which the three septa shown in the bottom panels belong to. Middle panel shows the same filament rotated by 30° of which an enlarged region of interest (white frame) is shown in the top right panel; arrowheads point to nascent septa, asterisks to newly completed ones. Bottom panels: three septa at consecutive septation stages (septa 1–3 in top left panel) were rotated by 90° and ordered from the youngest to the oldest (left, middle and right panel, respectively). D distal, P proximal. Scale bars are 5 µm (left upper corner) and 1 µm. f Schematic representations of C. steedae septation mode (top view in left panel, side view in right panel). The results are representative of at least three independent analyses.