Fig. 2

Fig. 2

Genome Activation Occurs over Time, Independent of the N/C Ratio

(A) Schematic illustrating the strategy to induce cell-cycle arrest by expressing chk1 in zebrafish embryos.

(B) Transmitted light microscopy picture of wild-type (WT) and chk1-injected embryos (+chk1) at different times (hours post-fertilization, hpf).

(C) Bar plot quantifying the number of cells in WT and chk1 (n = number of embryos analyzed).

(D) Single-nucleus confocal image of DAPI, Ser5P RNA Pol II, and transcription (Click-iT) in different conditions as indicated at 4 hpf (+Trip, incubated with triptolide). Click-iT signal intensity is presented in a heatmap color scale. Scale bar represents 5 μm.

(E) Box and whisker plots showing the mean fluorescence intensity for Click-iT signal in the conditions shown in (D) (^∗∗∗∗p < 0.0001; ^∗∗p = 0.0058; two-sample t test; WT [n = 129]; +chk1 [n = 21]; +chk1+triptolide [n = 15]).

(F) Biplot comparing intron expression levels of genes in chk1-injected embryos with and without triptolide treatment reveals genome activation occurs in chk1-injected embryos at 4 hpf. The solid black line represents the diagonal, and the dashed lines represent 4-fold change.

(G) Genome tracks representing normalized Click-iT-seq signal for examples of zygotic genes activated in chk1-injected embryos with (+chk1+triptolide) and without triptolide (+chk1). Reads per million (RPM) (STAR Methods).