Figure 3. The Dorsal-Venus Nuclear Gradient Is Dynamic, with Increasing Amplitude, Decreasing Basal Levels, and Constant Width.

(A) Snapshots of the Dorsal-Venus nuclear gradient for nuclear cycles 11–14 imaged at 150 μm using two-photon light-sheet microscopy. These snapshots were taken at peak values of the gradient amplitude for each nuclear cycle. Scale bar represents 50 μm.

(B) Quantification of the Dorsal-Venus nuclear gradient from snapshots shown in (A).

(C) Evolution of gradient amplitude (blue), basal levels (orange), and gradient width (red) from nuclear cycle 11 through gastrulation for the embryo shown in (A).

(D) Normalized gradient amplitude and basal levels from a single embryo zoomed in on time points between 53 and 41 min before gastrulation. The mitosis between nc 13 and 14 interphases takes place between ~50–46 min before gastrulation. The vertical dashed lines represent the time points depicted in the following panels.

(E–I) Snapshots of the Dorsal-Venus gradient at the time points shown in (D). The time points progress from the end of nc 13 interphase (E), the beginning of the following mitosis (F), the middle of mitosis (G), the end of mitosis (H), and the beginning of nc 14 interphase (I). Even in (H), a detectable ventral-to-dorsal gradient is present. Blue curves represent raw data. Red curves represent the Gaussian-like fit (Equation 1). See also Figure S1 and Movie S1.