| Worker bees of Apis cerana cerana normally nurse larva and clean nests at the age of 1 to 18 days but begin to forage outside when they are 15 to 18days old.In the case of no enough foragers or only nurses in a colony,young nurses become foragers prematurely and old bees continue to nurse larva.Such age-independent reciprocal transitions between nurses and foragers suggest the presence of age-independent unique expression profiles for each of the two types of worker bees.In order to identify the age-independent and uniquely-expressed gene profiles of the nurses and foragers,I marked a group of worker bees just emerged from a single colony and randomly placed them into two different colonies with a mated queen laying eggs in each of them:a normal colony with normal development of foragers and nurses,and a colony with normal number of nurses but without foragers,which we called single-cohort colony.One-day old newly-emerged worker bees(N1EM),normal nurses(N7BY),and normal foragers(N18CJ and N22CJ)were collected from the normal colony at the corresponding time points,whereas precocious foragers(Tq7CJ)were obtained from the colony without foragers.When the eggs and larvae in thesingle-cohort colony developed into pupae,I took the comb out of the single-cohort colony and introduce another comb with eggs to the colony without nurses.I collected over-aged nurses(Tq22BY)from this colony when the marked bees performed the activity of nursing.Total RNA were extracted from the above six age-different nurses or foragers and sequenced by Illumina hiseq 2000 to yield 6 digital gene expression(DGE)profiles called N1EM(1-day old newly-emerged worker bees,not capable of nursing or foraging),N7BY(7-day old normal nurses),Tq7CJ(precocious foragers),N18CJ(18-day old normal foragers),N22CJ(22-day old normal foragers)and Tq22BY(22-day old over-aged nurses),respectively.The total numbers of clean reads were 11459815 for N1EM,13628575 for N7BY,15344756 for Tq7CJ,10539625 for N18CJ,12576088 for N22CJ and 16895454 for Tq22BY.And the mapping rate of the 6 DGEs to the Apis cerana reference genome are 87.06%,84.1%,86.19%,85.2%,90.65%and 85.15%,respectively.Compared with the 7-day old normal nurses(N7BY),the 18-day old normal foragers(N18CJ)had a total of 415 genes differentially expressed(229 down-regulated and 186 up-regulated).Although their ages were the same(7-day old),374 and 118(total 492)genes were down-and up-regulated,respectively,inthe 7-day old precocious foragers(Tq7CJ)relative to those in the 7-day old normal nurses(N7BY).While they were both nurses,there were 263 differential expressed genes(116 up-and 147-down regulated in Tq22BY,respectively)between the over-aged nurses(Tq22BY)and the normal nurses(N7BY).There were 228(65 down-and 163 up-regulated in Tq22BY)differentially expressed genes between the 22-day old normal foragers(N22CJ)and the over-aged nurses(Tq22BY)although their ages were the same.Compared with the 7-day old precocious foragers(Tq7CJ),the normal foragers(N18CJ and N22CJ)had156 genes differentially expressed.Comparison of all nurses with all foragers regardless of their ages identified 169 genes uniquely expressed in all the nurses and 103 gens uniquely expressed in all the foragers.Among the 169 nurses-specific genes are mainly transportproteins.They are enriched in the following pathways:ribosome,protein processing in endoplasmic reticulum and protein export.The 103 foragers-specific genes belong to phospholipase,kinase,protein and some fatty esters.They participated in the following pathways:ribosome,metabolic pathways,proteinprocessing in endoplasmic reticulum.We can lay a solid foundation for explaining the molecular mechanism of division of labor through the comparision and analysis of honeybee head DGEs.And the obtaining sequence informations could enrich the genome database of Apis cerana cerana greatly at the same time. |
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