Abstract
BackgroundHoneybee development consists of four stages: embryo, larva, pupa and adult. Embryogenesis, a key process of cell division and differentiation, takes 3 days in honeybees. However, the embryonic transcriptome and the dynamic regulation of embryonic transcription are still largely uncharacterized in honeybees, especially in the Asian honeybee (Apis cerana). Here, we employed high-quality RNA-seq to explore the transcriptome of Asian honeybee embryos at three ages, approximately 24, 48 and 72 h (referred to as Day1, Day2 and Day3, respectively).ResultsNine embryo samples, three from each age, were collected for RNA-seq. According to the staging scheme of honeybee embryos and the morphological features we observed, our Day1, Day2 and Day3 embryos likely corresponded to the late stage four, stage eight and stage ten development stages, respectively. Hierarchical clustering and principal component analysis showed that same-age samples were grouped together, and the Day2 samples had a closer relationship with the Day3 samples than the Day1 samples. Finally, a total of 18,284 genes harboring 55,646 transcripts were detected in the A. cerana embryos, of which 44.5% consisted of the core transcriptome shared by all three ages of embryos. A total of 4088 upregulated and 3046 downregulated genes were identified among the three embryo ages, of which 2010, 3177 and 1528 genes were upregulated and 2088, 2294 and 303 genes were downregulated from Day1 to Day2, from Day1 to Day3 and from Day2 to Day3, respectively. The downregulated genes were mostly involved in cellular, biosynthetic and metabolic processes, gene expression and protein localization, and macromolecule modification; the upregulated genes mainly participated in cell development and differentiation, tissue, organ and system development, and morphogenesis. Interestingly, several biological processes related to the response to and detection of light stimuli were enriched in the first-day A. cerana embryogenesis but not in the Apis mellifera embryogenesis, which was valuable for further investigations.ConclusionsOur transcriptomic data substantially expand the number of known transcribed elements in the A. cerana genome and provide a high-quality view of the transcriptome dynamics of A. cerana embryonic development.
Highlights
Honeybee development consists of four stages: embryo, larva, pupa and adult
Asian honeybees have several advantages over European honeybees: (1) Asian honeybees have a good resistance to low temperatures that can be lethal to European honeybees [8]; (2) Asian honeybees are better able to collect honey in sporadic nectar sources and have a longer honey collection period [9]; (3) Asian honeybees are more active and more suitable to raise in mountain areas; and (4) Asian honeybees possess a strong resilience to the ectoparasitic mite [10], which has a catastrophic effect on the population of European honeybees [11]
Embryo stage determination In the embryo slice analysis, large morphological differences were observed among the embryo samples collected at 24, 48 and 72 h after the honeybee queens were placed in the egg- and brood-free honeycombs of their own hives
Summary
Honeybee development consists of four stages: embryo, larva, pupa and adult. Embryogenesis, a key process of cell division and differentiation, takes 3 days in honeybees. The embryonic transcriptome and the dynamic regulation of embryonic transcription are still largely uncharacterized in honeybees, especially in the Asian honeybee (Apis cerana). We employed high-quality RNA-seq to explore the transcriptome of Asian honeybee embryos at three ages, approximately 24, 48 and 72 h (referred to as Day, Day and Day, respectively). The best-known honeybees are the European honeybee (Apis mellifera) and Asian honeybee (Apis cerana). Both European and Asian honeybees are eusocial flying insects that have a great impact on the global ecological environment and can be domesticated for honey production and crop pollination [3, 4]. Compared to Asian honeybees, European honeybees are more widely used around the globe and can produce more honey products. Asian honeybees have several advantages over European honeybees: (1) Asian honeybees have a good resistance to low temperatures that can be lethal to European honeybees [8]; (2) Asian honeybees are better able to collect honey in sporadic nectar sources and have a longer honey collection period [9]; (3) Asian honeybees are more active and more suitable to raise in mountain areas; and (4) Asian honeybees possess a strong resilience to the ectoparasitic mite [10], which has a catastrophic effect on the population of European honeybees [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
