FIGURE 7.

Restoration of the phenotype of lutein accumulation by transgenic expression of Cameo2. A, organization of the transgenic vector used. ITR, inverted terminal repeats of piggyback; term, SV40 terminator, 3xP3, eye-specific promoter. B, silk glands of the GAL4/UAS (Ser1-GAL4/UAS-Cameo2) line, which was supposed to express Cameo2 in the middle silk gland by the binary system (30), and the GAL4 line as a control. The stage was W0. We confirmed similar stronger colorations in the GAL4/UAS line than the GAL4 line by observation of eight larvae of the GAL4/UAS line and 10 larvae of the GAL4 line. C, a representative chart of the reverse-phase HPLC analysis of carotenoid composition of the middle silk gland in the transgenic larvae. The stage was W0. Detection was at 474 nm. Peak positions 1, 2, 3, 4, 5, 6, and 7 correspond to the elution of 3′-dehydrolutein, 13-cis-lutein, unknown lutein derivative, lutein (trans lutein), zeaxanthin, 9-cis-lutein, and β-carotene, respectively. β-Carotene was barely detectable in the middle silk gland of the GAL4/UAS line. D, lutein concentration in the middle silk gland of the GAL4/UAS line and the GAL4 line (mean, S.E.; n = 3). The stage was W0. Statistical significance (p < 0.01) was analyzed by Student's t test. E, cocoon colors of the GAL4/UAS and GAL4 lines. All individuals analyzed in B–E exhibited the yellow hemolymph. Scale bar, 1 cm. F, model of the transport pathway for lutein in the larvae of the C and +^C allele strains. Lutein is transported into the tissues where both Cameo2 and CBP express. Cameo2 in the internal organs would act as the lipophorin receptor and/or the membrane lutein transporter. See “Discussion” for details.