| The mandibular glands are a pair of exocrine glands located in the hand of worker bees,their principal biological function is to secrete fatty acids as a major component of royal jelly(RJ)for both larval nutrition and alarm pheromone synthesis.10-hydroxy-2-decenoic acid(10-HDA)is among the most abundant fatty acids secreted by mandibular glands and regarded as the most important criterion in RJ quality assesment.High royal jelly producing bees(RJBs,Apis mellifera liguatica)were bred in China for improving the production of RJ.The bred,RJB,can produce 10 times higher RJ than the Italian bees(ITBs,Apis mellifera liguatica).With the increasing of RJ production,the 10-HDA content of RJ has declined to certain extent.However,a molecular mechanism of phosphoproteome in regulating mandibular glands’ development and functionality in RJBs and ITBs is not yet reported.This study was based on liquid chromatography-mass/mass phosphoproteomics and bioinformatics methods.To reveal the mechanism of phosphoproteome in regulating mandibular glands’ development,we compared mandibular glands’ phosphoproteome differences between RJBs and ITBs in newly emerged,nurse and forager bee ages.The numbers of phosphoproteins identified in RJBs(509,554 and 460 in newly emerged,nurse and forager bees,respectively)were significantly higher than the corresponding ages in ITBs(483,499 and 387 in newly emerged,nurse and forager bees,respectively),illustrating that RJBs’ mandibular gland phosphorylation regulation network is likely more complicated than that of ITBs.The results showed that similar phosphoproteome profiling across gland development of RJBs and ITBs,suggesting that the phosphoproteins perform similar biological function to ensure gland development and secretion activity.The comparison of phosphoproteome at each stage of both RJBs and ITBs revealed significant differences between the two lines.At each stage of ITB,the phosphoproteome involves in energy metabolism for various life activities of the glands through enhancing protein synthesis and processing.During the newly emerged stage,the phosphoproteome in RJBs is mainly to support the basic development of gland through regulating RNA processing based on spliceosome and cytoskeletal proteins,which provides material basis for the RJ secretion behavior of nurse bees.After long-term selection for high royal jelly production,both lines have adapted distinct gland phosphoproteome programs.During nurse bee stage of RJBs,it is mainly involved in pyruvate dehydrogenase related energy metabolism pathways,fatty acid synthesis and various signal transduction pathway within cells to improve the glands’ 10-HDA secretion and energy supply during high royal jelly production for maintaining the nutritional function of royal jelly.During the forager stage,phosphorylation is most associated with synthesis of new proteins related to stress response for adapting the transformation of glandular functions during foraging behavior.This may help morphological and functional changes of mandibular glands’ in RJB foragers,strengthening the synthesis of transport proteins to promote the release of alarm pheromones to adapt to the external environment and supporting the synthesis of ubiquitin to regulate apoptosis process during forager bee aging.RJBs and ITBs have shaped different phosphoproteome signatures to maintain mandibular gland development and function between adult bees of the same age.The most profound divergence occurred during the nurse stage,in which RJBs might increase the ability of fatty acid synthesis of the glands to ensure the basic function of royal jelly.The data help us gain a novel understanding of the molecular underpinnings that drive enhanced royal jelly production in RJBs at the level of protein modification. |
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