Fig. 1

Temperature-sensitive kit allele facilitates the selective removal or restoration of kit function. Lateral views of 2.5 days postfertilization (dpf) wild-type (A) and kit^j1e99 larvae reared continuously at the permissive temperature of 25°C (C) show melanocytes that have migrated into ventral (black arrowheads) and rostral (open arrowheads) positions. In contrast, melanocytes in 2.5-dpf kit^b5 null mutants (B) and kit^j1e99 mutants reared continuously at the restrictive temperature of 33°C (D) are largely restricted to the dorsal aspect of the neural tube (black arrowheads) and the region immediately posterior to the otic vesicle (open arrowheads). Dorsal view of 12-dpf kit^j1e99 larvae reared continuously at 25°C (E) shows that melanocytes persist through late larval development, similar to 12-dpf wild-type larvae (not shown). In contrast, 12-dpf kit^j1e99 larvae reared continuously at 33°C (F) are almost entirely devoid of all melanocytes, similar to 12 dpf kit^b5 larvae (not shown; [Parichy et al., 1999]. Animals in (E) and (F) were treated with epinephrine to contract melanosomes and reveal individual melanocytes. Scale bars: 500 μm (A–D), 100 μm (E, F).