Astaxanthin and lutein compete for accumulation into the middle silk gland via Yellow cocoon gene (C)-dependent control and produce a red cocoon of Bombyx mori

摘要

Newly ecdysed fifth instar larvae of the Bombyx mori strain N4 were divided into three groups and fed one of three different diets until they began spinning a cocoon. One group was fed the basal diet, in which carotenoids consisted mainly of lutein (53.3μg/g wet) and β-carotene (14.4μg/g wet), while the two other groups were fed the basal diet supplemented with astaxanthin from AstaREAL? or capsanthin from paprika-red?. High performance liquid chromatography was performed to identify the carotenoids in lipophorin, the middle silk glands, and the cocoons. Lutein, as well as astaxanthin and capsanthin, was accumulated in the cocoons after feeding with the astaxanthin- or capsanthin-supplemented diet. Quantitative analysis of the strain N4 and c10 demonstrated competitive accumulation in the cocoon between lutein and astaxanthin. In fifth instar larvae of the white cocoon producer, the strain c05 fed a diet containing lutein and astaxanthin, however, they produced only white cocoon. These results indicated that lutein and astaxanthin transport share common pathways, and that the delivery system in the silkworm can mediate the transfer and accumulation of carotenoids which are not derived from mulberry leaves, such as astaxanthin and capsanthin.