Expression of a nitric oxide synthase and nitric oxide levels in the development of queens and workers of Apis mellifera

Abstract

The castes of Apis mellifera differ in many aspects concerning anatomy, physiology and behavior, and these differences are crucial for providing efficiency in task performance, which are reproductive (queen) and maintenance of the hive (worker). The differentiation of the castes depends on the type of diet offered to the female larvae during the growth period, this resulting in differential responses in endocrine signaling pathways and regulation of gene expression. While the role of juvenile hormone in this process has been widely investigated already for decades, it was only once the complete sequence of the honey bee genome became available that analyses of other signaling pathways responding to external stimuli and those modulating growth rates of the body became feasible. These include the pathways for insulin/insulin-like signaling(IIS), target-of-rapamycin (TOR), hypoxia (HIF) and epidermal growth factor receptor (EGFR). Especially the hypoxia pathway presented very interesting features, as its three core genes were revealed as higher expressed in worker larvae, this indicating an endogenous hypoxia response. Attempting to understand the mechanisms of activation of this pathway and its connection with the other above mentioned ones we hypothesize that nitric oxide (NO) could exert such a mediator function. Thus, this project aims at investigating the involvement and role of NO signaling. The gene encoding a honey bee nitric oxide synthase (NOS ortholog has already been identified and annotated, and herein we will investigate its transcript levels throughout the critical larval stages for queen/worker differentiation using quantitative RT-PCR. Furtermore, the levels of nitric oxide in honey bee larvae will be quantified by means of a biochemical assay.