Fig. 2. Immunoreactivity to histamine is reduced in white, brown, scarlet, ebony and white; ebony relative to Oregon-R wild-type flies. Frozen 10 µm frontal sections immunolabeled with anti-CSP (B,E,H,K,N.Q) or anti-histamine (A,D,G,J,M,P), and the corresponding merged double label anti-CSP (green) and anti-histamine (magenta; C,F,I,L,O,R). (A–C) Oregon R wild-type; (D–F) white, (G–I) brown, (J–L) scarlet, (M–O) ebony and (P–R) white; ebony. Relative to the wild-type, the histamine immunosignal is reduced in the laminas of all mutants. The signal is similarly reduced for CSP, in the optic lobe and central brain in white, brown and largely lost in white; ebony mutants. Overlap between the expression patterns is complete only in the laminas of wild-type. Scale bar, 100 µm.