Figure 4. Expression and localization of oca2 mRNA during early Astyanax development.

A. Downregulation of oca2 transcript levels in cavefish (CF) relative to surface fish (SF) at 40 hours post-fertilization determined by RT-PCR amplification of a 975 bp sequence in the middle of the oca2 coding region. B-W. Localization of oca2 mRNA in surface fish embryos and larvae (B-P) and oca2 mRNA downregulation in cavefish embryos and larvae (Q-W) determined by in situ hybridization. B-I. Surface fish embryos viewed from the lateral (B, D, F, H) and dorsal-rostral (C, E, G, I) sides showing oca2 expression located bilaterally in cells adjacent to the dorsal midline at 12 (B, C), 13.5 (D, E), 14 (F, G) and 22 (H, I) hpf. J-N. Embryos viewed from the lateral side at 25 (J, K) and 60 (M, N) hpf. Diagonal line in K represents the approximate location of the section shown in L. M. A 60 hpf embryo raised in PTU with arrows showing from left to right oca2 expression in eyes, otic and pharyngeal regions, yolk sac, trunk dorsal region, and trunk ventral region respectively. N. Higher resolution image of an oca2 stained 60 hpf embryo showing the pigmented eye. O. Section through a 60 hpf oca2 stained embryo showing pigmentation in the RPE. P. Section through a 60 hpf PTU treated embryo showing oca2 staining in the unpigmented RPE. Q-W. Cavefish embryos viewed from a lateral side at 10 (Q), 13 (R), 13.5 (S), 14 (T), 28 (U), and 40 (V, W) hpf. Arrows in L, M, O, P and W show cells expressing oca2 mRNA. Scale bar in B is 250 µm; magnification is the same in B-J, M, and Q-W. K and W represent 2X magnifications of J and V respectively. Scale bar in L is 125 µm. Scale bars in N and O are 250 µm: magnification is the same in O and P.