Molecular Mechanism Underlying The Division Of Labour In Workers And Three Queen-like Genes Differential Expression In Apis Mellifera

Honey bee(Apis mellifera)was used in this study, and methyl-DNA immunoprecipitation combined with high-throughput sequencing (MeDIP-seq) was applied for the comparative methylome analysis of feeding queen larvae nurses, feeding worker larvae nurses, returning pollen foragers and reverted nurses, in addition, Digital Gene Expression tag profiling (DGE) was used to analyze the gene expression differences among these four workers. Furthermore, real-time PCR was used to analyze the expression differences of three queen-like genes (sir2histone deacetylase (sir2), histone deacetylase1(hdac1) and absent, small, or homeotic discs2(ash2)) among the female honey bees.For each sample of feeding queen larvae nurses (FQLN), feeding worker larvae nurses (FWLN), returning pollen foragers (RPF) and reverted nurses (RN), we obtained24,489,796raw reads via MeDIP-seq, and about80%of the reads were mapped and more than72%of the reads in each sample were uniquely mapped to the honey bee genome. Model-based Analysis of ChIP-Seq (MACS) was used to scan the methylated peaks in the genome, and for each sample, the coverage of methylated peaks in the genome was about14.5%. According to the results from the peak scanning, we analyzed the differentially methylated gene components among multiple samples. Comparing FQLN with FWLN, FWLN with RPF, FWLN with RN, RPF with RN, there were118,122,94and121differentially methylated gene components respectively.Using Apis mellifera transcripts and the honey bee genome as reference sequences, we analyzed the gene expression differences among these four samples via DGE. In total,5,950,226(FQLN),5,837,851(FWLN),6,069.314(RPF) and5,877,809(RN) clean tags were sequenced. There were673,874,822and710differential expressed genes detected between FQLN and FWLN, FWLN and RPF, FWLN and RN, RPF and RN respectively.Using real-time PCR, the relative expression levels of sir2, hdac1and ash2were examined in queens and workers at different developmental stages. The sir2, ash2, hdacl expression levels in newly emerged queens, laying queens and laying workers were significantly higher than those in newly emerged workers, nurses and foragers(P<0.05). Furthermore, these genes also had significantly higher expressions in queen pupae than in worker pupae(P<0.05). We conclude that these genes are possibly "queen-like" genes.