Figure 4.

mchr1a and mchr1b receptor gene expression in the adult zebrafish brain and mchr2 expression in the larval skin. A: mchr2 mRNA distribution (ISH) in the melanophores of a 2-dpf larva (lateral view, head to the left). Natural pigmentation was chemically inhibited by using PTU (see Materials and Methods). B: Natural pigmentation of a control larva at the same developmental stage without PTU treatment. Note how the black melanophore distribution resembles the mchr2 expression pattern. C–N: mchr1a mRNA brain distribution (ISH) in a rostrocaudal series of cross sections (telencephalon, C–E; diencephalon and mesencephalon, F–K; rhombencephalon, L–N). O–Z: mchr1b mRNA distribution (ISH) (telencephalon, O–Q; diencephalon and mesencephalon, R–X; rhombencephalon, Y,Z). No mchr1b mRNA was detected in the posterior rhombencephalon. Abbreviations of brain loci are as in the Figure 3 legend. Additional loci include the dorsal and ventral telencephalic areas (D, V), the medial, lateral, and posterior zones of D (Dm, Dl, Dp), the dorsal, medial, lateral, and ventral zones of V (Vd, Vm, Vl, Vv), the anterior thalamus (A), the anterior and posterior parvocellular preoptic nuclei (PPa, PPp), the ventrolateral and -medial thalamic nucleus (VL/VM), the valvula cerebelli (Va), the preglomerular nucleus (PGM), the perilemniscal nucleus (PL), the nucleus of the lateral lemniscus (NLL), the vagal motor neurons (NXm), the entopeduncular nucleus (EN), the optic tectum (TeO), and the descending octaval nucleus (DON). Scale bar = 100 μm in A,B; 200 μm in C–Z.