Differential gene expression between hygienic and non-hygienic honeybee (Apis mellifera L.) hives

Abstract

BackgroundHygienic behavior is a complex, genetically-based quantitative trait that serves as a key defense mechanism against parasites and diseases in Apis mellifera. Yet, the genomic basis and functional pathways involved in the initiation of this behavior are still unclear. Deciphering the genomic basis of hygienic behavior is a prerequisite to developing an extensive repertoire of genetic markers associated to the performance level of this quantitative trait. To fill this knowledge gap, we performed an RNA-seq on brain samples of 25 honeybees per hives from five hygienic and three non-hygienic hives.ResultsThis analysis revealed that a limited number of functional genes are involved in honeybee hygienic behavior. The genes identified, and especially their location in the honeybee genome, are consistent with previous findings. Indeed, the genomic sequences of most differentially expressed genes were found on the majority of the QTL regions associated to the hygienic behavior described in previous studies. According to the Gene Ontology annotation, 15 genes are linked to the GO-terms DNA or nucleotide binding, indicating a possible role of these genes in transcription regulation. Furthermore, GO-category enrichment analysis revealed that electron carrier activity is over-represented, involving only genes belonging to the cytochrome P450. Cytochrome P450 enzymes’ overexpression can be explained by a disturbance in the regulation of expression induced by changes in transcription regulation or sensitivity to xenobiotics. Over-expressed cytochrome P450 enzymes could potentially degrade the odorant pheromones or chemicals that normally signal the presence of a diseased brood before activation of the removal process thereby inhibit hygienic behavior.ConclusionsThese findings improve our understanding on the genetics basis of the hygienic behavior. Our results show that hygienic behavior relies on a limited set of genes linked to different regulation patterns (expression level and biological processes) associated with an over-expression of cytochrome P450 genes.

Deleterious Interaction Between Honeybees (Apis mellifera) and its Microsporidian Intracellular Parasite Nosema ceranae Was Mitigated by Administrating Either Endogenous or Allochthonous Gut Microbiota Strains

“…Total RNA for each sample (a pool of 5 bees per cage, 5 cages per experimental group) was extracted from intestinal honeybee using TRIzol R Reagent protocol from Invitrogen (Chomczynski, 1993) as described in Boutin et al (2015). Complementary DNA (cDNA) was synthesized using qScript TM cDNA SuperMix (Quanta Biosciences).…”

Functional characterization of CYP4G11—a highly conserved enzyme in the western honey bee Apis mellifera

“…Microarray‐based differential expression studies have implicated this gene in hygienic behavior (Le Conte et al, ); CYP4G11 transcripts were more abundant in bees displaying reduced hygienic behavior compared to their highly hygienic counterparts. Similar results were found using RNA‐seq (Boutin et al, ). CYP4G11 is down‐regulated in larvae of colonies infested with varroa mites (Gregorc et al, ) and up‐regulated in antennae of nurses and foragers that display varroa hygienic behavior (VSH) compared to antennae of bees that do not display these behaviors (Mondet et al, ).…”

Brood Affects Hygienic Behavior in the Honey Bee (Hymenoptera: Apidae)

“…Studies comparing adult workers with different selective breeding histories (henceforth referred to as colony "type") have reported behavioral (Masterman et al 2000;2001;Spivak et al 2003;Harbo and Harris 2009), genetic (Tsuruda et al 2012, Boutin et al 2015, Gempe et al 2016, Jiang et al 2016, and proteomic (Le Conte et al 2011, Parker et al 2012, Guarna et al 2017 differences between colony types. While many studies regarding hygienic behavior mechanisms (Aumeier and Rosenkranz 2001, Goode et al 2006, Mondet et al 2015) have focused on sensitivity and modulation of adult honey bee olfaction, less attention has been paid to the role of the olfactory signals that induce honey bee hygienic behavior.…”