关键词: 唾液腺, 蛋白质组, 蜂王浆高产蜜蜂, 意大利蜜蜂, 蜂王浆, 分泌性蛋白

Abstract:

【Objective】The objective of this study is to investigate the proteome profile of the postcereberal gland (PGld) and thoracic gland (ThGld) between high royal jelly producing bees (Apis mellifera liguatica, RJBs) and Italian bees (Apis mellifera liguatica, ITBs) with the aim of revealing the molecular basis of salivary gland regulating royal jelly production, and to provide a basis for analyzing the high-yield mechanism of royal jelly.【Method】PGld and ThGld were dissected from nurse bees of RJBs and ITBs. After protein extraction and enzyme digestion, the peptide samples were analyzed by liquid chromatography coupled with tandem mass spectrometry. Furthermore, the mass spectral data were qualified and quantified by MaxQuant software, and the following bioinformatic analysis was conducted using Perseus software, prediction of secretory protein was achieved by SignalP database, biological process and KEGG pathway were enriched by Cluego software.【Result】Totally 2 335 proteins were identified in salivary glands of RJBs and ITBs nurse bees, including 1 823 proteins in PGld and 1 922 proteins in ThGld. The expression profiles of the core proteins in the PGld and ThGld of RJBs and ITBs were similar, mainly involved in RNA metabolism, nucleic acid metabolism, ATP metabolism, protein translation, translation regulation and catabolism. The principal component analysis (PCA) showed that the molecular basis of salivary gland of RJBs and ITBs had exerted varying extent of differentiation during the selective breeding. Quantitatively, the PGld of ITBs and RJBs expressed 254 and 333 up-regulated proteins, respectively, corresponding to the small molecule and carbohydrate metabolism pathway in ITBs, and the organic nitrogen compound synthesis, cell redox homeostasis, amino acid metabolism in RJBs. Those proved that the protein synthesis, amino acid metabolism and energy supply of salivary gland cells in RJBs were more active than ITBs. In the same way, the up-regulated expressions of 412 and 162 proteins were detected in the ThGld of ITBs and RJBs, respectively, which involved in the pathways of oxidative phosphorylation, translation regulation in ITBs, and oxidative phosphorylation, response to toxic substances in RJBs, indicating that the level of resistance of RJBs ThGld cells was increased. A total of 43 secretory proteins were identified in the salivary glands of RJBs and ITBs, in which 15 were detected in royal jelly. Major royal jelly proteins 1, 2, 3, 4, 5 and 7 were detected in PGld and ThGld, indicating that both of the glands were involved in the synthesis of royal jelly main protein. The identification of α-glucosidase related to nectar transformation and odorant binding proteins 3, 13, 17 and 21 involved in the synthesis and release of chemical pheromones in both PGld and ThGld indicated their basic function of nectar transformation and pheromone synthesis. The enhanced expression of major royal jelly proteins 1, 2, 3 and 7, hexamerin 70a and 110, odorant binding proteins 3, 13, 17 and 21, transferrin and apolipophorin-III-like protein in the salivary gland of RJBs demonstrated that the synthesis of pheromone and royal jelly protein was stronger than ITBs.【Conclusion】The core proteome with similar pattern in salivary glands of RJBs and ITBs ensures the synthesis and secretion of royal jelly protein, pheromone and invertase. Molecular variation between the salivary glands of RJBs and ITBs was developed after long-term selective breeding. Relative to ITBs, the salivary glands of RJBs enhance the ability of protein synthesis, amino acid metabolism, cell energy supply and stress resistance, and upregulate the expression of most secretory proteins, which benefits to a better protein synthesis system with promising efficiency and lasting, and contributes to the high producing of royal jelly.

Key words: salivary gland, proteome, high royal jelly producing bee, Italian bee, royal jelly, secretory protein