Fig. 1 Markers of differentiating habenular neurons are delayed by constant darkness. (A) Zebrafish embryos were raised in 14/10 light/dark (LD) or constant darkness (DD) conditions beginning at 5 min post-fertilization. (B–E) Expression of kctd12.1 initiates in the habenular nuclei (black arrows) at 38 h post-fertilization (hpf) in LD but does not initiate until 48 hpf in DD. (F–M) Similarly, expression of kctd12.2 and cadps2 initiates earlier in LD than in DD conditions. Insets in F–I are magnified views of the left habenula. (N–O) By contrast, expression of nrp1a in the habenular nuclei (white arrowheads) is not delayed by DD conditions; (P–S) nor is otx5 expression in the pineal and parapineal or gfi1 expression in the parapineal (black arrows). All views are dorsal except for frontal views in B–E and lateral views in F–I. Scale bar = 50 μm except for insets in F–I (25 μm).
Reprinted from Developmental Biology, 358(1), de Borsetti, N.H., Dean, B.J., Bain, E.J., Clanton, J.A., Taylor, R.W., and Gamse, J.T., Light and melatonin schedule neuronal differentiation in the habenular nuclei, 251-61, Copyright (2011) with permission from Elsevier. Full text @ Dev. Biol.