关键词: 意大利蜜蜂, 哺育蜂, 喙伸反应, 学习, 记忆, 基因, RNA-seq

Abstract: 【Aim】 This study aims to screen out the genes closely related to learning and memory in nurses of the Italian honey bee, Apis mellifera ligustica. 【Methods】 A. m. ligustica individuals at defined age (10-day-old nurses, 21-day-old nurses and 21-day-old foragers) in artificial bee colonies were collected, and the differences in learning and memory abilities of the three groups were determined using proboscis extension reflex (PER) assay. The gene expression levels in brains of the 10-day-old and 21-day-old nurses with and without learning ability were analyzed by RNA-seq technique, and the differentially expressed genes (DEGs) closely related to learning and memory were screened. The differentially expressed genes were subjected to GO and KEGG enrichment analysis. The expression levels of three DEGs randomly selected (the up-regulated genes TpnCⅢa and MED23, and down-regulated gene Pkc) in brains of the 10-day-old and 21-day-old nurses with and without learning ability were detected by qPCR. 【Results】 The results of PER assay showed that the learning ability of 21-day-old nurses of A. m. ligustica was significantly higher that of the 10-day-old nurses after they were trained five times, but the learning ability between the 21-day-old nurses and the 21-day-old foragers showed no significant difference. Similarly, the memory ability of the 21-day-old nurses was significantly higher than that of the 10-day-old nurses, but the memory ability between the 21-day-old nurses and 21-day-old foragers showed no significant difference. RNA-seq analysis demonstrated that 88 DEGs were closely related to learning and memory of nurses, with 18 genes up-regulated and 70 genes down-regulated. The results of GO enrichment showed that up-regulated DEGs were most enriched in the biological process classification, mainly in the related aspects of signal transduction, protein processing and modification. Down-regulated DEGs were also enriched in the biological process classification, mainly concentrated in the related aspects of transcription, signal transduction and protein biosynthesis, with significant enrichment in the related aspects of transcription. The KEGG enrichment showed that down-regulated DEGs were significantly enriched in phagosome, phototransduction, and AGE-RAGE signal pathway. The qPCR results showed that the expression trends of the differentially expressed genes TpnCⅢa, MED23 and Pkc in brains of the 10-day-old and 21-dayold nurses with and without learning ability were consistent with RNA-seq data. 【Conclusion】 The PER assay indicated that age is an important factor that affects the learning and memory abilities of A. m. ligustica nurses. This study obtained the change trends of gene expression and its enrichment analysis in the brain of nurses after learning train, providing a theoretical foundation for further research on the molecular mechanism of learning and memory of nurses.

Key words: Apis mellifera ligustica; nurses, proboscis extension reflex, learning, memory, gene, RNA-seq