Determining which octopamine receptor links appetite and fluctuating trehalose levels in the honey bee

Official URL: https://risc01.sabanciuniv.edu/record=b2583874_(Table of contents)

For foraging honey bees, fluctuating energy demands are high because at times they must sustain flight which is energetically expensive. Therefore, they provide an ideal model for studying how an organism can precisely regulate their appetite. Trehalose is the main sugar found in the hemolymph of the honey bee. The fluctuating level of this sugar was investigated to determine if there is a connection with the octopamine (OA) level in the brain. First, we manipulated the hemolymph sugar levels using thorax sugar injections and found that they were most effective in the forager age class, which corresponded with the largest changes in appetite across all age classes. The lowering of trehalose levels corresponded with an increase in octopamine levels in the honey bee brain. The appetite regulation observed was independent of the glucose-insulin signaling pathway as indicated by ILP1 and ILP2 gene expression. Based on these results, I designed a CRISPR-cas9 plasmid to knockdown the octopamine beta receptor subtype-2 to determine its role in appetite regulation. The fura-2 biosensor measured calcium signaling and the presence of octopamine receptors in a newly established Ame711 cell line. In future work, I will test baculovirus’ transduction efficiency using the Ame711 honey bee cell line to determine its transduction efficiency before using it as a vector to deliver the CRISPR-cas9 complex in vivo. In summary, using these newly developed tools, identifying whether there is a causal link between octopamine and appetite regulation in the honey bee will be possible.