Molecular characterization of the gene feminizer in the stingless bee Melipona interrupta (Hymenoptera: Apidae) reveals association to sex and caste development. (November 2015)

• Record Type: Journal Article
• Authors: Brito, Diana V.; Silva, Carlos Gustavo N.; Hasselmann, Martin; Viana, Luciana S.; Astolfi-Filho, Spartaco; Carvalho-Zilse, Gislene A.
• Is Part Of: Insect biochemistry and molecular biology. Volume 66(2015:Nov.)
• Page Start: 24
• Page End: 30
• Publication Date: 2015-11
• Subjects: Gene expression -- Eusocial insects -- Alternative splicing -- Sex determination -- JH signaling pathway -- Caste determination; Insect biochemistry -- Periodicals; Insects -- Physiology -- Periodicals; Insects -- Molecular aspects -- Periodicals; Biochemistry -- Periodicals; Insectes -- Biochimie -- Périodiques; Insectes -- Composition -- Périodiques; Insectes -- Physiologie -- Périodiques; Insectes -- Aspect moléculaire -- Périodiques; Biochimie -- Périodiques; Biochemistry; Insect biochemistry; Insects -- Molecular aspects; Insects -- Physiology; Periodicals; 572.8157
• DOI: 10.1016/j.ibmb.2015.09.008
• Languages: English
• ISSNs: 0965-1748

Abstract

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. Graphical abstract: Highlights: Sex-specific transcripts of the feminizer ( fem ) gene are expressed in the stingless bee, Melipona interrupta . fem has a conserved role in sex determination of M . interrupta . fem expression fluctuates during development. Ectopic application of juvenile hormone in larvae increases fem expression. Key elements of sex and caste determination pathways in social insects are significantly correlated.