Transcriptional identification of differentially expressed genes associated with division of labour in Apis cerana cerana

Workers of Apis cerana cerana undergo an in-hive nursing to outdoor foraging transition, but the genes underlying this aged-related transition remain largely unknown. Here, we sequenced the head transcriptomes of its 7-day-old normal nurses, 18- and 22-day-old normal foragers, 7-day-old precocious foragers and 22-day-old over-aged nurses to unravel the genes associated with this transition. Mapping of the sequence reads to Apis mellifera genome showed 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. Pair- and group-wise comparisons of the 5 transcriptomes revealed 59 uniquely expressed genes (18 in nurse and 41 in forager) and 14 nurse- and 15 forager-upregulated genes. The uniquely expressed genes are usually low-abundance lncRNAs, transcription factors, transcription coactivators, RNA-binding proteins, kinases or phosphatases that are involved in signaling and/or regulation, whereas the nurse- or forager-upregulated genes are often high-abundance downstream genes that directly perform the tasks of nurses or foragers. Taken together, these results suggest that the nurse-forager transition is coordinated by a social signal-triggered epigenetic shift from introns to exons/intergenic regions and the resulted transcriptional shift between the nurse- and forager-associated genes. This article is protected by copyright. All rights reserved.