RESUMO
Like all other insects, two key signalling pathways [Toll and immune deficiency (Imd)] regulate the induction of honey bee immune effectors that target microbial pathogens. Amongst these effectors are antimicrobial peptides (AMPs) that are presumed to be produced by the nuclear factors kappa B (NF-κB) Dorsal and Relish from the Toll and Imd pathways, respectively. Using in silico analysis, we previously proposed that the honey bee AMP defensin-1 was regulated by the Toll pathway, whereas hymenoptaecin was regulated by Imd and abaecin by both the Toll and Imd pathways. Here we use an RNA interference (RNAi) assay to determine the role of Dorsal in regulating abaecin and defensin-1. Honey bees have two dorsal genes (dorsal-1 and dorsal-2) and two splicing isoforms of dorsal-1 (dorsal-1A and dorsal-1B). Accordingly, we used both single and multiple (double or triple) isoform knockdown strategies to clarify the roles of dorsal proteins and their isoforms. Down-regulation of defensin-1 was observed for dorsal-1A and dorsal-2 knockdowns, but abaecin expression was not affected by dorsal RNAi. We conclude that defensin-1 is regulated by Dorsal (Toll pathway).
Assuntos
Peptídeos Catiônicos Antimicrobianos/metabolismo , Abelhas/genética , Defensinas/metabolismo , Genes de Insetos , Imunidade Inata , Proteínas de Insetos/metabolismo , Sequência de Aminoácidos , Animais , Abelhas/imunologia , Abelhas/metabolismo , Escherichia coli , Expressão Gênica , Paenibacillus larvae , Pupa/metabolismo , Interferência de RNARESUMO
The honey bee queen and worker castes are a model system for developmental plasticity. We used established expressed sequence tag information for a Gene Ontology based annotation of genes that are differentially expressed during caste development. Metabolic regulation emerged as a major theme, with a caste-specific difference in the expression of oxidoreductases vs. hydrolases. Motif searches in upstream regions revealed group-specific motifs, providing an entry point to cis-regulatory network studies on caste genes. For genes putatively involved in reproduction, meiosis-associated factors came out as highly conserved, whereas some determinants of embryonic axes either do not have clear orthologs (bag of marbles, gurken, torso), or appear to be lacking (trunk) in the bee genome. Our results are the outcome of a first genome-based initiative to provide an annotated framework for trends in gene regulation during female caste differentiation (representing developmental plasticity) and reproduction.