Fig. 1
From: Uncovering the balance of forces driving microtubule aster migration in C. elegans zygotes
3D time-lapse microscopy of pronuclear migration and centration in the one-cell C. elegans embryo. a Pronuclei and centrosomes monitored with 3D time-lapse DIC and GFP fluorescence microscopy in embryos expressing GFP::TAC-1. Here and in other figures, representative DIC images are shown; centrosomes (green dots—z-projections), the female pronucleus (blue circle), and the male pronucleus (red circle) are represented; black crosses: pronuclei centers—z-projections. 0 s: pronuclear meeting unless specified otherwise; scale bars: 10 μm. b Schematics of forces acting on pronuclei during their migration. Here and in other figures, embryos are schematized with the female and male pronuclei (blue and red disks, respectively), centrosomes (green dots), microtubules (green lines), dynein motors (blue), and dynein anchors (light blue ellipses); arrows represent exerted forces. Anterior (A) and posterior (P) sides are indicated. c Average pronuclear and centrosome midpoint positions along the A–P axis as a function of time (n = 33, with S.E.M.). Here and thereafter, position on the A–P axis is represented in normalized coordinates (0: anterior; 1: posterior). d Absolute average pronuclear velocities as a function of the distance separating them, which decreases over time (n = 33, with S.E.M.). Velocities increase while pronuclei approach each other and then diminish when the male-asters complex and the female pronucleus get closer than ~15 μm from one another, probably because of steric hindrance effects. FMF force exerted between the male-asters complex and the female pronucleus, Fcort force exerted by cortical dynein, Fcent centering force, γF, γMAC drag coefficient of the female pronucleus and male-asters complex, respectively
