| Honeybee is the main pollination insect in nature and is very important for agricultural development and ecological diversity.However,in recent years,biological and abiotic pathogenic factors such as microsporidiosis and insecticides have posed a threat to the health of bees.The fungal pathogen microsporidia(Nosema ceranae)is one of the major factors that cause the death of honeybees in some parts of the world.N.ceranae infection in Apis mellifera L.affects the behavior and memory ability of honeybees,increases energy consumption of bees,and causes energy stress.At the same time,its infection causes bees precocity and become forager earlier,which interferes with the normal social division of bees.Hypopharyngeal glands(HPGs)located in frontal area of head of worker bees,and secret royal jelly.Protein synthesis ability in HPGs of honeybee exhibits the highest activity when honeybees age of 8-16 days old,the gland reaches full development in 9 days old.In this study,we investigate the effect of N.ceranae infection on the genes expression and physiological response of bee’s HPGs.The main consists of transcript sequencing,measuring acinar size of HPGs,testing total protein content and the activity of metabolic enzyme in HPGs,those enzymes include amylase,glucosidase,glucose oxidase and a-glucose.Based on these results to understand molecular and physiological mechanism employed by the parasite N.ceranae to manipulate the nurse bees premature.In this experiment,each bee in treatment group was fed 2 μ1 50%sugar water containing 0.5 ×105 N ceranae,while the control group was fed 2 μl 50%sugar water,9,12 and 15 days after treatment honeybee samples were collected,respectively.Anatomy the royal jelly glands of 9 days old bee for transcriptome sequencing analysis use RNA-Seq technology.Measuring acinar size,the total protein content and enzyme activity of hypopharyngeal gland in different age,and qPCR was used to analysis the expression of royal jelly protein gene in different age.Gene expression at transcriptome levels showed 285 differentially expressed between control bees and N.ceranae infected bees,and 279 genes were up-regulated in the infected bees,then,these different expressed genes showed a similar trend in different age of honeybees.Compared to the control group,royal jelly gland acinar volume,total protein concentration of treatment group was significantly reduced and the expression of the major royal jelly proteins(MRJPs)genes was decreased.The influence of N.ceranae on enzyme activity of amylase,glycosidase enzymes,glucose oxidase and α-glucosidase were different in different ages,the overall change is enzyme activity increased in the treatment group.Amylase activity increased significantly at the 9 days in the infected bees,glucose oxidase and a-glucosidase activity were higher than the control group at the age of 12 day in the treated.The results showed that N.ceranae infection caused changes in the gene expression,decreased total protein concentration,and increased enzyme activity of the honeybee’s hypopharyngeal glands.N.ceranae infection promotes the bee royal jelly glands early atrophy and stop nurse larva,it is consistency with previous results that N.ceranae infection leading to early maturity and change nurse bees to forager.In addition,the up-regulation of encoding genes for juvenile hormone-binding protein and neuropeptides in the hemolymph may also be a regulatory mechanism for premature maturation of honeybees caused by N.ceranae infection. |
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