title: Identification and characterisation of a silkworm ABC transporter gene homologous to Drosophila white.
abstract: In the silkworm, Bombyx mori, many eye- and egg-colour mutations affecting the synthesis and accumulation of ommochrome pigments have been described. In order to understand the pigment precursor transporters involved, ABC transporter genes homologous to the Drosophila white gene were isolated from the silkworm. Reverse transcriptase-polymerase chain reactions (RT-PCR) using embryonic mRNA amplified three cDNA fragments, named Bmwh1, Bmwh2 and Bmwh3 that showed homology to the white gene. Since Bmwh3 shows the highest degree of sequence identity and a similar expression pattern to the Drosophila homologue, we characterised this gene further. A 2667-bp Bmwh3 cDNA isolated from an embryonic library has one ORF encoding a polypeptide of 687 amino acids. The predicted protein has one ATP-binding domain, six transmembrane-spanning segments and high similarity to the Drosophila WHITE protein. Southern analysis indicates that Bmwh3 is a single-copy gene. Polyadenylated Bmwh3 transcripts about 2.7 kb long were detected in eggs, Malpighian tubules and pupal heads, but not in testes, posterior silk glands or fat body cells. The level of Bmwh3 mRNA was reduced in w3 and w3ol mutants but normal in other egg- and eye-colour mutants, suggesting that Bmwh3 correspond to the w3 locus. Genetic analysis was used to map the cloned gene to chromosome 10.
authors.affiliation: Department of Insect Genetics and Breeding, National Institute of Sericultural and Entomological Sciences, Tsukuba, Ibaraki, Japan.
authors.forename: E G
authors.initials: EG
authors.lastname: Abraham
authors.forename: H
authors.initials: H
authors.lastname: Sezutsu
authors.forename: T
authors.initials: T
authors.lastname: Kanda
authors.forename: T
authors.initials: T
authors.lastname: Sugasaki
authors.forename: T
authors.initials: T
authors.lastname: Shimada
authors.forename: T
authors.initials: T
authors.lastname: Tamura
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics* / Q000254:growth & development; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D029721:Drosophila Proteins; D005127:Eye Color / Q000235:genetics; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva; D008969:Molecular Sequence Data; D009154:Mutation; D010063:Ovum / Q000502:physiology; D017386:Sequence Homology, Amino Acid
chemical_list: D018528:ATP-Binding Cassette Transporters; D029721:Drosophila Proteins; D005136:Eye Proteins; D019476:Insect Proteins; C059254:w protein, Drosophila