Cytoplasmic composition contributes to nuclear size scaling in X. laevis embryo extracts. (A) Left: Based on the data presented in Fig. 1, C–E, maximum nuclear volume is plotted as a function of droplet volume for stage 10 embryo extract droplets (blue). Right: Nuclear-to-cytoplasmic (N/C) volume ratios were calculated by dividing maximum nuclear volume by droplet volume. A best-fit power regression curve is displayed for the droplet data. Also plotted are previously reported in vivo nuclear size scaling data and nuclear-to-cytoplasmic volume ratios for X. laevis stages 8 to 10.5 (Jevtić and Levy, 2015). (B) Stage 10 nuclei were isolated and resuspended in cytoplasmic extract from different embryonic stages. Extract droplets were incubated at room temperature. (C) At each time point, 10–168 nuclei were quantified (80 nuclei on average). The stage 10 extract data are the same shown in Fig. 1 C. (D) Stage 10 extract and nuclei were mixed with stage 5 cytoplasmic extract or egg extract at a 1:10 ratio. After a 2-h incubation, nuclei were fixed and stained with NPC antibody mAb414. Nuclear CS areas were measured and the fold change was calculated relative to the preincubation nuclear size. At least 700 nuclei were quantified for each condition. Data from two independent experiments are shown. Two-tailed Student’s t tests assuming equal variances; ***, P ≤ 0.001. Error bars represent SD.