Fig. 1

Cell-Cell Adhesion and Goosecoid Expression Positively Correlate within the Prechordal Plate In Vivo

(A) Schematic representation of a 70% epiboly stage (7.5 hpf) embryo. Lateral view shows a section through the dorsal midline of the embryo. Ecto, ectoderm; IF, interstitial fluid; ppl, prechordal plate; pm, posterior axial mesendoderm; pam, paraxial mesendoderm.

(B) Schematic representation of a homotypic/homochronic transplantation assay.

(C) Representative images of ppl cells transplanted from a Tg(gsc::mEGFP) embryo injected with qDots into a Tg(gsc::mEGFP) non-injected embryo. Transplantation was performed at shield stage (6 hpf) and images were taken between 60% epiboly stage (6.5 hpf) and 70% epiboly stage (7.5 hpf). Scale bar, 50 μm.

(D) Representative images of cell-cell contact dynamics between transplanted and host ppl cells at 60% epiboly stage (6.5 hpf). Scale bar, 20 μm.

(E and F) Correlation between gsc::mEGFP expression rate and average contact duration (E) or average number of contacts (F) in ppl progenitors between 6.5 and 7.5 hpf. Transplanted cells were tracked for 60 min and average EGFP and qDots intensities were measured for each cell at 3 min intervals. The linear coefficient (Lc) of EGFP/qDots as a function of time was normalized by the median EGFP/qDots level of all transplanted cells at the first time point in the respective experiment, and used as a proxy of the level of endogenous gsc expression. Average ppl cell-cell contact duration and number were computed after tracking cell-cell contacts formed by each transplanted ppl cell for 60 min. n (cells), 34; 4 embryos. Pearson correlation (r) and relative p values (p) are shown. See also STAR MethodsSTAR Methods, Figure S1, and Movie S1.