Circular RNAs in honeybees
Markus Thamm, Markus Thamm , Christoph Erbacher , Clemens Thölken , Marcus Lechner
Behavioral Physiology & Sociobiology, University of Würzburg, Germany; Behavioral Physiology & Sociobiology, University of Würzburg, Germany ; Behavioral Physiology & Sociobiology, University of Würzburg, Germany ; Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Germany ; Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Germany
Apis mellifera represents an important model organism for social insects. Worker bees display behavioral plasticity, which is reflected by age-dependent task allocation. The young nurse bees and the older foragers who take care of the brood inside the hive and collect food from outside the hive, respectively, perform the most protruding tasks. A promising strategy is to analyze differences in gene expression in the brains of different worker bees. However, circular RNAs, which are produced in back splicing events, were not considered in this context so far. As of today, this group of non-coding RNAs was only known to exist in two other insects, Drosophila melanogaster and Bombyx mori. Members of this RNA species show an enhanced age-dependent accumulation in neural tissues. This interesting feature prompted us to investigate a potential role of circular RNAs in honeybee worker behavior. Using RNA-Seq with exonuclease enrichment, we identified numerous circular RNAs present in worker bee brains using RNA-Seq. Many of these RNAs show homologies to circRNAs found in flies and moths, indicating that circRNAs are a common feature among insects. Back splicing in honeybee brains occurs either towards the end of transcripts or in transcripts with a higher number of exons than average. For prominent candidates we have analyzed the abundance of circular transcripts in nurse and forager bee brains. Some transcripts are indeed expressed differentially, indicating a link to the social transition in honeybees.