Fig. 3

bonaparte is required non-autonomously to melanophores.

(A,B) bonaparte melanophores consistently formed wild-type stripes in melanophore-free nacre (bonaparte⁺) hosts (n = 8). Shown are low magnification (A) and higher magnification (B) views of the same individual. (C–F) bonaparte mutant melanophores consistently formed larger and denser spots when adjacent to wild-type (GFP⁺) myotome and hypodermal cells. Shown is a single individual. Melanophores were more spread and patches were larger (arrows in C) and such patches were found above wild-type (GFP⁺) muscle (n = 3) (D). In this individual, no wild-type melanophores developed, but muscle and epidermis occurred in both overlapping and non-overlapping regions and patches of bonaparte mutant melanophores corresponded more closely to the location of muscle than of epidermis. Distributions are shown schematically in E; hm, hypodermal cells and muscle; epi, epidermis; mel, melanophores; irid, iridophores. Melanophore patches were identified by the greater density and more spread morphology of melanophores in fish prior to epinephrine treatment, which causes melanosome translocation towards cell bodies facilitating GFP detection in melanophores and other tissues. The individual shown has not yet fully contracted melanosomes in all melanophores. (F) In transverse section, melanophores (arrow) were adjacent to GFP⁺ muscle (m) as well as a thin layer of hypodermal cells (h), that cannot be seen in whole mount. Scale bars: in (C), 100 μm for (C–E); in F, 100 μm.