During the segment period, more complex and dynamic cellular bioelectric signals occurred at the tissue level. (A–F) Segmentation period (bud stage-6 somite stage, 1 h intervals, Supplementary Video S10). Somites and the posterior region of the embryo had an increased level of fluorescence. White arrows point to the somites. Note the relatively low fluorescent signals within the head region. (G–L) Left lateral time-lapse images of 10–16 somite zebrafish embryos (Supplementary Video S11). White arrowsheads point to the strong hyperpolarization of somites. Blue arrows point to Vm signals in the developing heart. (M–R) Dorsal view time-lapse images of 10–16 somite zebrafish embryos. White arrowheads indicate somite regions with strong hyperpolarization (Supplementary Video S12). (S) Embryo with positions of ROIs (1–7) used to calculate mean fluorescence and corresponding ∆FAdj. (T) ∆FAdj over time of ROIs in panel (S). All colored lines represent the change in fluorescence intensity of the designated ROI at each time point. Signals appeared to increase over time as somites became more developed. The number of fluctuations also increased as more somites were generated. (U) The mean ∆FAdj for each ROI for the entire duration of the time-lapse video. ROIs 1–2 showed the least amount of activity (most anterior somites), ROIs 3–5 showed the most activity (middle age somites), and ROIs 6–7 showed a moderate amount of activity (youngest somites/presomitic mesoderm/tailbud region). Asterisks indicate a statistical significance of p < 0.001. NS, not statistically significant. Scale Bar= 250 µm.
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