ARC5 | Dynamin-like protein ARC5

Relationship between chloroplast proliferation and chloroplast volume.(A–B) Chloroplast number and cell volume in cotyledons of 3-day-old, dark-grown Arabidopsis thaliana seedlings illuminated for 0 hr (T0), 4 hr (T4), 24 hr (T24), and 96 hr (T96) in continuous white light (40 µmol/m2/s). (A) Chloroplast number per cell during de-etiolation. Error bars indicate ± SD (n = 6 for T0 and T4; seven for T24; five for T96). (B) Cell volume was quantified by the Labels analysis module of Amira software. Error bars indicate ± SD (n = 5–6). (C–D) Total proteins were extracted from T0–T96 seedlings, separated on SDS-PAGE, and transferred onto nitrocellulose. Proteins involved in plastid division (C, FtsZ; D, ARC5) and loading control (actin) were detected using specific antibodies (FtsZ2 antibody recognizes both FtsZ2-1 and FtsZ2-2). (E) Volume of dividing chloroplast at T24 and T96. Error bars indicate ± SD (n = 3). Further details of chloroplast proliferation in parallel with cell expansion are provided in Figure 8—figure supplement 1.Figure 8—source data 1.Quantitative data for chloroplast number, cell and chloroplast volumes.Quantitative data for chloroplast number, cell and chloroplast volumes.Chloroplast proliferation in parallel with cell expansion.SEM micrographs of 3-day-old, dark-grown Arabidopsis thaliana (Columbia) seedlings illuminated for 0 hr (T0; A), 4 hr (T4; B), 24 hr (T24; C), and 96 hr (T96; D) in continuous white light (40 ?mol/m2/s). Palisade (PA) and spongy (SP) cells are indicated. Scale bars: 15 ?m. (E) 3D reconstruction of a palisade cell at T24 after segmentation of chloroplasts and cell plasma membrane. (F–I) Confocal images of cotyledons of dark-grown seedlings at T24 (F), T48 (G), T72 (H), and T96 (I). Scale bars: 10 ?m. (J–M) TEM micrographs of cotyledon cells of dark-grown seedlings at T24 (J), T48 (K), T72 (L), and T96 (M). (J–K), scale bars: 2 ?m; L–M, scale bars: 5 µm. (N) Cell perimeter measured with Amira software using (red line). The Z-depth of each stack corresponds to 1 ?m. Relative chloroplast number per cell was counted using 2D TEM images (black line). Red error bars indicate ± SD (n = 17). Black error bars indicate ± SD (n = 3–4). (O) Single chloroplast volume quantified at T48 and T72. Data indicate mean ± SD (n = 5). (P) Examples of chloroplasts selected for the quantification of the volume of chloroplast in division at T24 and T96.