Figure 3.

The yellow pigment 3-OHK is stored in the fat bodies, circulated in the haemolymph and taken up from the haemolymph into yellow scales. The absorbance spectrum of (a) pure 3-OHK is similar to (b) fat body extract and (c) haemolymph, suggesting that 3-OHK is a major component of both. (d) There is a rapid increase of 3-OHK in the haemolymph (solid line) and the fat bodies (broken line) of late-stage pupae, as inferred from spectrophotometric analysis of the 380 nm absorbance peak. ¹⁴C-3-OHK injected into pupal haemolymph is incorporated specifically into yellow scales. (e) At a stage shortly preceding the appearance of yellow in the H. himera forewing band, (f) only low levels of ¹⁴C-3-OHK are incorporated around the edges of the band. At an intermediate stage of yellow development, when 3-OHK is observed only in the anterior portion of the forewing band, high levels of (h) ¹⁴C-3-OHK incorporation are perfectly correlated with (g) yellow pigmentation. (i–l) No incorporation of ¹⁴C-3-OHK was detected in red hindwing scales.