Project description:While Apis cerana cerana, like Apis mellifera, undergoes a behavioral transition from in-hive nursing to outdoor foraging duties, nothing is known about the genes underlying this social signal-triggered aged-related transition in this species. Here, we simultaneously sequenced the head transcriptomes of the 7-day-old normal nurses (N7BY), 18- and 22-day-old normal foragers (N18CJ and N22CJ), 7-day-old precocious foragers (Tq7CJ) and 22-day-old overaged or reverted nurses (Tq22BY) of A. cerana cerana by RNA-seq and made a 3-tier comparison (from pairwise to group-wise and between-group) to unravel the genes associated with this transition. Six pairwise comparisons revealed 165-492 differentially expressed genes between nurses vs. foragers. Subsequent 3 group-wise and 1 between-group comparisons narrowed the transition-associated genes down to 18 nurse- and 41 forager-unique genes and 29 (14 and 15 genes upregulated in nurses and foragers, respectively) differentially expressed genes between the 3 types of foragers and 2 types of nurses. The uniquely expressed genes are usually low-abundance long noncoding RNAs, transcription factors, transcription coactivators, RNA-binding proteins, kinases or phosphatases involved in signaling transduction and/or gene expression regulation, whereas the differentially expressed genes are often high-abundance downstream genes that directly perform the tasks of nurses or foragers, such as major royal jelly proteins for nurses and the genes involved in sugar/protein digestion, lipids/fatty acids metabolism, plant allelochemicals detoxification and defense against pathogens and predators for foragers. Mapping of the clean reads to the published A. mellifera genome uncovered that the 3 types of foragers had a greater percentage of reads from annotated exons and intergenic regions, whereas the 2 types of nurses had a greater percentage of reads from introns. Taken together, these results suggest that the reciprocal nurse-forager behavioral transition of the A. cerana cerana is regulated by a social signal-triggered intron-exon/intergenic epigenetic shift and the resulted transcriptional shift of the nurse- and forager-associated genes.
