Transcriptome differences in the hypopharyngeal gland between Western Honeybees (Apis mellifera) and Eastern Honeybees (Apis cerana)

Abstract

BackgroundApis mellifera and Apis cerana are two sibling species of Apidae. Apis cerana is adept at collecting sporadic nectar in mountain and forest region and exhibits stiffer hardiness and acarid resistance as a result of natural selection, whereas Apis mellifera has the advantage of producing royal jelly. To identify differentially expressed genes (DEGs) that affect the development of hypopharyngeal gland (HG) and/or the secretion of royal jelly between these two honeybee species, we performed a digital gene expression (DGE) analysis of the HGs of these two species at three developmental stages (newly emerged worker, nurse and forager).ResultsTwelve DGE-tag libraries were constructed and sequenced using the total RNA extracted from the HGs of newly emerged workers, nurses, and foragers of Apis mellifera and Apis cerana. Finally, a total of 1482 genes in Apis mellifera and 1313 in Apis cerana were found to exhibit an expression difference among the three developmental stages. A total of 1417 DEGs were identified between these two species. Of these, 623, 1072, and 462 genes showed an expression difference at the newly emerged worker, nurse, and forager stages, respectively. The nurse stage exhibited the highest number of DEGs between these two species and most of these were found to be up-regulated in Apis mellifera. These results suggest that the higher yield of royal jelly in Apis mellifera may be due to the higher expression level of these DEGs.ConclusionsIn this study, we investigated the DEGs between the HGs of two sibling honeybee species (Apis mellifera and Apis cerana). Our results indicated that the gene expression difference was associated with the difference in the royal jelly yield between these two species. These results provide an important clue for clarifying the mechanisms underlying hypopharyngeal gland development and the production of royal jelly.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-744) contains supplementary material, which is available to authorized users.

The rise and fall of major royal jelly proteins during a honeybee (Apis mellifera) workers' life

“…This is in accord with the general notion that mrjps are higher expressed in brood‐feeding nurse bees than in foragers (Klaudiny et al, ; Kubo et al, ; Ohashi et al, ). However, whereas all other mrjps do have their highest transcript abundance during the nurse bee period, mrjp6 shows highest abundance at day 20 (Table ) in accordance with previous studies reporting on a significantly higher expression of mrjp6 in forager compared to nurse bee heads and HGs (Buttstedt et al, ; Liu et al, ). In the brain, mrjp6 expression does not show any caste‐related modulation supported by Hernández et al () who did not detect differences in MRJP6 between brains of nurses and foragers.…”

Quantitative analysis of the genes affecting development of the hypopharyngeal gland in honey bees (Apis mellifera L.)

“…Our results revealed that the relative expression levels of the SV2C, eIF-4E, PDK1, IMP, CGNP and TGF-βR1 genes were reduced from nurse to forager, which is consistent with our previous DGE analysis (Liu et al, 2014), suggesting that our previous DGE results are reliable.…”

“…Both the present study and our prior observation (Liu et al, 2014) suggested that the expression levels of eIF-4E, CGNP, IMP and TGF-βR1 expressing higher at newly emerged worker, nurse and reversed nurse stages compared to forager stage which is in parallel with the physiological conditions of HGs: the HGs grew rapidly at newly emerged worker stage and synthesized a large amount of royal jelly at the nurse stage, so many genes related to the biological metabolism and cell growth over expressed at these two stages and then reduced their expression quickly at forager stage in view of the degeneration of HGs and the cell apoptosis. However, the HGs re-growed and speeded up biological metabolism at reversed nurse stage lead to increased expression of many relevant genes.…”

“…Actually in our previous study, PDK1 declined continuously all the time (Liu et al, 2014). Hence we speculated that PDK1 has the function of controlling the lifespan of HGs.…”

“…Previously, we performed a digital gene expression (DGE) analysis of the HGs at three developmental stages (newly emerged worker, nurse and forager) between Apis mellifera and Apis cerana, the two sibling honeybee species representing the most typical subspecies for western and eastern bee, respectively, with the aim of searching for the DEGs affecting the development of HG and/or the RESEARCH ARTICLE -BEES Jiangxi Agricultural University, Nanchang, Jiangxi, China secretion of royal jelly (Liu et al, 2014). As a result, synaptic vesicle glycoprotein 2C (SV2C) was found to be expressed significantly high amounts in nurses among three developmental stages in both species and it was significantly higher in HGs of Apis mellifera than that of Apis cerana at the nurse stage.…”