title: Molecular characterization of the gene feminizer in the stingless bee Melipona interrupta (Hymenoptera: Apidae) reveals association to sex and caste development.
abstract: In highly eusocial insects, development of reproductive traits are regulated not only by sex determination pathway, but it also depends on caste fate. The molecular basis of both mechanisms in stingless bees and possible interaction with each other is still obscure. Here, we investigate sex determination in Melipona interrupta, focusing on characterization and expression analysis of the feminizer gene (Mi-fem), and its association to a major component of caste determination, the juvenile hormone (JH). We present evidence that Mi-fem mRNA is sex-specifically spliced in which only the female splice variant encodes the full length protein, following the same principle known for other bee species. We quantified Mi-fem expression among developmental stages, sexes and castes. Mi-fem expression varies considerably throughout development, with higher expression levels in embryos. Also, fem levels in pupae and newly emerged adults were significantly higher in queens than workers and males. Finally, we ectopically applied JH in cocoon spinning larvae, which correspond to the time window where queen/worker phenotypes diverge. We observed a significantly increase in Mi-fem expression compared to control groups. Since up to 100% of females turn into queens when treated with JH (while control groups are composed mainly of workers), we propose that fem might act to regulate queens' development. Our findings provide support for the conserved regulatory function of fem in Melipona bees and demonstrate a significant correlation between key elements of sex and caste determination pathways, opening the avenue to further investigate the molecular basis of these complex traits.
authors.affiliation: Grupo de Pesquisas em Abelhas, Instituto Nacional de Pesquisas da Amazônia, Manaus 69080-971, AM, Brazil; Department of Livestock Population Genomics, Institute of Animal Science, University of Hohenheim, Stuttgart 70599, BW, Germany. Electronic address: diana.vieira.brito@gmail.com.
authors.forename: Diana V
authors.initials: DV
authors.lastname: Brito
authors.affiliation: Centro de Apoio Multidisciplinar, Universidade Federal do Amazonas, Manaus 69077-000, AM, Brazil.
authors.forename: Carlos Gustavo N
authors.initials: CG
authors.lastname: Silva
authors.affiliation: Department of Livestock Population Genomics, Institute of Animal Science, University of Hohenheim, Stuttgart 70599, BW, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Hasselmann
authors.affiliation: Grupo de Pesquisas em Abelhas, Instituto Nacional de Pesquisas da Amazônia, Manaus 69080-971, AM, Brazil.
authors.forename: Luciana S
authors.initials: LS
authors.lastname: Viana
authors.affiliation: Centro de Apoio Multidisciplinar, Universidade Federal do Amazonas, Manaus 69077-000, AM, Brazil.
authors.forename: Spartaco
authors.initials: S
authors.lastname: Astolfi-Filho
authors.affiliation: Grupo de Pesquisas em Abelhas, Instituto Nacional de Pesquisas da Amazônia, Manaus 69080-971, AM, Brazil.
authors.forename: Gislene A
authors.initials: GA
authors.lastname: Carvalho-Zilse
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001516:Bees / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D007605:Juvenile Hormones / Q000494:pharmacology; D007814:Larva / Q000235:genetics / Q000254:growth & development; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D019849:Sex Determination Processes
chemical_list: D007605:Juvenile Hormones; D012333:RNA, Messenger
keywords: Alternative splicing; Caste determination; Eusocial insects; Gene expression; JH signaling pathway; Sex determination