Fig. 2

Tg(dusp6:d2EGFP) expression is enriched in cells at the leading edge of the migrating parapineal. (A–H) Time series of thin confocal maximum projection (3 µm) of the brain of a live Tg(dusp6:d2EGFP)^pt6 (green) embryo (embryo no. 1 shown in Movie S1) expressing H2B-RFP protein (red) in cell nuclei at different stages of development (26, 28, 30, 32, 36, 40, 44, 48 hpf). The epiphysis and the parapineal are shown as white or yellow dotted circles. Tg(dusp6:d2EGFP) is also expressed in the presumptive habenulae, shown by an asterisk (*); two asterisks (**) indicate autofluorescence that appears from 44 hpf. Embryo view is dorsal, anterior is up. (Scale bars, 10 µm.) Position of Tg(dusp6:d2EGFP)⁺ cells relative to the mean position of all parapineal cells at different stages of parapineal migration are shown in SI Appendix, Fig. S3I. (I–N) Polar graph showing the distribution of Tg(dusp6:d2EGFP) cells per 45 °C semiquadrant (1–8) relative to the parapineal mean position (center) and the antero-posterior line at a given time point: 26 hpf (I), 28 hpf (J), 32 hpf (K), 36 hpf (L), 40 hpf (M), and 44 hpf (N). The radial axis (0–2, vertical scale, upper left) represents the mean number of Tg(dusp6:d2EGFP)⁺ parapineal cells per semiquadrant and per embryo (n = 4). At each specific time point, arrows show the orientation of migration for each of the four embryos [defined by the extrapolated line passing through the parapineal mean positions at T and at T + 2 h (for 26 hpf) or T + 4 h (28, 32, 36, 40, 44 hpf)]. The length of the arrow is proportional to the extrapolated distance migrated per hour. Anterior (Ant), posterior (Post), left and right orientations are shown in the I graph.