Fig. 3: Anaphase astral microtubules are required for the anaphase flows.
From: Cytoplasmic flow is a cell size sensor that scales anaphase
a, Time projection of mitochondria (Mito-GFP) and chromosomes (WGA). b,c, PIV analysis of the cell in a. The colour code represents flow velocity (b) and vorticity (c). Arrows, flow field. d, Flow velocity near the chromosomes in control (black line; n = 9 cells from 5 embryos) and latrunculin-B-treated cells (blue line; n = 9 cells from 5 embryos). e, Time projection of mitochondria and chromosomes after actin inhibition. Scale bars, 50 µm. f,g, PIV analysis of the cell in e. The colour code represents flow velocity (f) and vorticity (g). Arrows, flow field. h, Flow velocity near the chromosomes (control and latrunculin (lat.) B, n = 9 PIV measurements from 5 embryos; for each cell, there can be up to two PIV measurements corresponding to the sets of segregating chromosomes in the dividing cell) and chromosome velocity in control (n = 34 embryos) and latrunculin-B-treated (n = 5 embryos) embryos. i, Time projection of mitochondria and chromosomes of a control cell. Scale bar, 50 µm. j,k, PIV analysis of mitochondria in the region highlighted in i. Arrows, flow field; colour code (k), vortex size. Scale bar, 20 µm. l–o, PIV analysis of tubulin speckles (l and m) and EB3–GFP (n and o) in a region near the chromosomes, similar to the region in i. In l and n, overlay of the vector field with tubulin speckles and EB3-GFP, respectively. Arrows, flow field; colour code (m and o), vortex size. Scale bars, 10 µm. p, Velocity of flows of mitochondria near the chromosomes (n = 15 PIV measurements from 9 embryos), tubulin speckles (n = 4 cells from 4 embryos) and EB3 (n = 4 cells from 4 embryos). q, Snapshots of a metaphase cell before and after SBTub3-P activation (405 nm laser). α-tubulin-ATTO-565, microtubules. r, Time projection of mitochondria and chromosomes after SBTub3-P activation. Same cell as in q. Scale bars, 50 µm. s, PIV analysis of mitochondria of the same cell as in q and r. Arrows, magnitude and orientation of the flow field; colour code, flow velocity; grey mask, chromosomes. In r and s, flow pattern and velocity are abolished compared with the control in i. t,u, Flow vorticity (n = 15 and 6 PIV measurements from 10 and 3 embryos for the control and SBTub-3P, respectively; for each cell, there can be up to two vorticity measurements corresponding to the sets of segregating chromosomes in the dividing cell) (t) and chromosome velocity (control, n = 34 embryos; SBTub3-P, n = 8 embryos; P = 1.7 × 10−8) (u) in control and after SBTub3-P activation four-cell-stage embryos. Statistical significance was determined by two-tailed Mann–Whitney test. The error bars represent s.e.m. n.s., not significant; AO, anaphase onset.
