Fig. 2.

Effect of FtsZ2-1 overexpression on chloroplast division and cell-cycle progression in asynchronously cultured C. merolae. (A) Schematic diagram of the culture conditions. The control GFP heat-inducible (GFP) or FtsZ heat-inducible (FtsZ OX) cells cultured at 42 °C under light were transferred to dark to stop cell growth and entrance into the S phase. Then GFP or FtsZ from the transgene was expressed by two rounds of heat shock at 50 °C for 1 h. (B) Immunoblot analyses showing the change in the levels of the chloroplast-division proteins FtsZ2-1, DRP5B, and PDR1 and the M-phase marker H3S10ph in GFP and FtsZ OX cells. The GFP and FtsZ OX samples were blotted on the same membrane. (C) Microscopic images of GFP and FtsZ OX cells 1 and 24 h after the onset of heat-shock treatment. (Upper) Cells immunostained with the anti–FtsZ2-1 antibody. (Lower) DAPI-stained images of DNA. Green, immunostained FtsZ2-1 (the GFP expressed in the GFP cell cytosol had been extracted before the antibody reaction; thus the green fluorescence specifically indicates FtsZ2-1); magenta, autofluorescence of the chloroplast; cyan, DNA stained with DAPI. The images obtained by fluorescence and phase-contrast microscopy are overlaid. (Scale bars: 5 µm.) The arrowheads indicate the cells that possess a single chloroplast and two nuclei. Two independent experiments produced similar results. The results from one experiment are shown.