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. 2022 Oct 10;23(11):e55251. doi: 10.15252/embr.202255251

Figure 5. Non‐diffusive nuclear centring and high cytoplasmic viscosity in 2‐cell embryos.

Figure 5

  • A
    Representative time‐lapse images of 2‐cell embryos cultured with SiR‐DNA to label nuclei (white circles) and microinjected with oil droplets (yellow circles). Time is shown as h:min relative to maximal nuclear displacement.
  • B
    Plot of the distances between oil droplets and nuclei to the cell centre over time (n = 14 oil‐nucleus pairs).
  • C
    Representative time‐lapse images of prophase I‐arrested oocytes (upper panel, dashed circles outline nuclei) (n = 16 oocytes) and 2‐cell embryos microinjected with H2B‐RFP to label DNA (n = 14 embryos) following treatment with MyoVin‐1. Time is shown as h post‐drug addition.
  • D
    MSD analysis of nuclear displacement during re‐centring (n = 26 blastomeres). Power‐law slopes of 1 and 2 are drawn for comparison.
  • E
    Top panel: an example of fluorescent bead distribution in a 2‐cell embryo. Lower panel: an example of region imaged for bead tracking at high temporal resolution.
  • F, G
    Trajectories of bead movement over a 20‐s duration in oocytes (F, n = 217 beads from 23 oocytes) and 2‐cell embryos (n = 277 beads from 26 embryos). Each coloured line represents a single bead track.
  • H
    MSD plot of beads in oocytes (n = 217 beads from 23 oocytes) and 2‐cell embryos (n = 277 beads from 26 embryos). Power‐law slopes of 1, 0.5 and 0.1 are drawn for comparison.
  • I
    Results obtained from MSD analysis. α represents the slope of the log–log fit of the MSD curve using the first 25% (100 data points). D represents the diffusion coefficient estimated from the linear fit of the MSD curve.

Data information: Scale bar = 20 μm in A, C, E, except 2 μm in the lower panel of E. In (B), data are shown as mean ± SEM. In (D, H), the ensemble‐averaged MSDs are shown.

Source data are available online for this figure.