title: Honey bee (Apis mellifera) transferrin-gene structure and the role of ecdysteroids in the developmental regulation of its expression.
abstract: Social life is prone to invasion by microorganisms, and binding of ferric ions by transferrin is an efficient strategy to restrict their access to iron. In this study, we isolated cDNA and genomic clones encoding an Apis mellifera transferrin (AmTRF) gene. It has an open reading frame (ORF) of 2136 bp spread over nine exons. The deduced protein sequence comprises 686 amino acid residues plus a 26 residues signal sequence, giving a predicted molecular mass of 76 kDa. Comparison of the deduced AmTRF amino acid sequence with known insect transferrins revealed significant similarity extending over the entire sequence. It clusters with monoferric transferrins, with which it shares putative iron-binding residues in the N-terminal lobe. In a functional analysis of AmTRF expression in honey bee development, we monitored its expression profile in the larval and pupal stages. The negative regulation of AmTRF by ecdysteroids deduced from the developmental expression profile was confirmed by experimental treatment of spinning-stage honey bee larvae with 20-hydroxyecdysone, and of fourth instar-larvae with juvenile hormone. A juvenile hormone application to spinning-stage larvae, in contrast, had only a minor effect on AmTRF transcript levels. This is the first study implicating ecdysteroids in the developmental regulation of transferrin expression in an insect species.
authors.affiliation: Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3.900, Ribeirao Preto, 14040-901 SP, Brazil. admendes@rge.fmrp.usp.br
authors.forename: Adriana Mendes
authors.initials: AM
authors.lastname: do Nascimento
authors.forename: Virginie
authors.initials: V
authors.lastname: Cuvillier-Hot
authors.forename: Angel Roberto
authors.initials: AR
authors.lastname: Barchuk
authors.forename: Zilá Luz Paulino
authors.initials: ZL
authors.lastname: Simões
authors.forename: Klaus
authors.initials: K
authors.lastname: Hartfelder
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001516:Bees / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015152:Blotting, Northern; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D026461:Ecdysteroids / Q000502:physiology*; D004441:Ecdysterone / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D017344:Genes, Insect / Q000235:genetics*; D007605:Juvenile Hormones / Q000494:pharmacology / Q000502:physiology*; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D011679:Pupa / Q000254:growth & development / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014168:Transferrin / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D026461:Ecdysteroids; D007605:Juvenile Hormones; D014168:Transferrin; D004441:Ecdysterone