Fig. 2

Analysis of Epithelial Cell Turnover by Multicolor Labeling and Live Imaging

(A) Brightfield view of adult zebrafish caudal fin. Inset depicts the alternating pattern of bony ray (black arrows) and interray tissues. Red box indicates areas where the z stacked confocal images were captured. Scale bars, 1 mm.

(B) Multicolor labeling of adult fin epithelium. Superficial epithelial cells (SECs) on the fin surface label with one of ∼70 unique colors (see Experimental Procedures for details). Scale bars, 50 μm.

(C) Examples of SEC color dynamics during their presence on the fin surface. 33 representative cells are shown here, illustrating color stability over several days.

(D) Quantitative analysis showing color stability over time. The distance between the median color of each trajectory and its value at all times was calculated and aligned to their first appearance. Color distance is relatively high at early time points because of weak intensity upon first appearance but stabilizes after the first 48 hr. The green line represents the mean of trajectories (n = 87).

(E) Quantitative analysis indicating changes in SEC size over time. Single-cell trajectories were aligned with respect to their first appearance on fin surface for comparison. Each line represents an independent trajectory with a black cross at the end indicating cell loss (n = 186 from four animals). The green line represents the mean of trajectories (n = 186).

(F) Quantitative analysis showing average SEC lifespan under homeostatic conditions (n = 87, 32, 37, and 30 from four animals). Distribution of cell lifespan was measured as the duration of complete trajectories (from first appearance to loss). Bars indicate mean ± SD to indicate the spread of subjects.

(G) Large-scale surveillance of SEC loss over time. Percentage of cell loss events was plotted as the sum of the missing cell number divided by the total cell number at day 0 (n = 1077, 992, 854, and 719 from four animals), which could rise above 100% over an extended time period.