title: Carotenoid silk coloration is controlled by a carotenoid-binding protein, a product of the Yellow blood gene.
abstract: Mechanisms for the uptake and transport of carotenoids, essential nutrients for humans, are not well understood in any animal system. The Y (Yellow blood) gene, a critical cocoon color determinant in the silkworm Bombyx mori, controls the uptake of carotenoids into the intestinal mucosa and the silk gland. Here we provide evidence that the Y gene corresponds to the intracellular carotenoid-binding protein (CBP) gene. In the Y recessive strain, the absence of an exon, likely due to an incorrect mRNA splicing caused by a transposon-associated genomic deletion, generates a nonfunctional CBP mRNA, resulting in colorless hemolymph and white cocoons. Enhancement of carotenoid uptake and coloration of the white cocoon was achieved by germ-line transformation with the CBP gene. This study demonstrates the existence of a genetically facilitated intracellular process beyond passive diffusion for carotenoid uptake in the animal phyla, and paves the way for modulating silk color and lipid content through genetic engineering.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakudoh
authors.forename: Hideki
authors.initials: H
authors.lastname: Sezutsu
authors.forename: Takeharu
authors.initials: T
authors.lastname: Nakashima
authors.forename: Isao
authors.initials: I
authors.lastname: Kobayashi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Fujimoto
authors.forename: Keiro
authors.initials: K
authors.lastname: Uchino
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Banno
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Iwano
authors.forename: Hideaki
authors.initials: H
authors.lastname: Maekawa
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kataoka
authors.forename: Kozo
authors.initials: K
authors.lastname: Tsuchida
mesh_terms: D000483:Alleles; D000818:Animals; D030801:Animals, Genetically Modified; D012831:Bombyx / Q000235:genetics / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003116:Color; D005786:Gene Expression Regulation; D049750:Genome, Insect / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010641:Phenotype; D047011:Silk / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D019476:Insect Proteins; D047011:Silk; D002338:Carotenoids