Meeting Abstract
P2.92 Tuesday, Jan. 5 TbhR: A Novel Gene Family Related to Tyramine Beta-Hydroxylase LEHMAN, HK*; BERRY, N; BERTINO, S; BRODSKI, A; CHAPONIS, S; Hamilton College; Hamilton College; Hamilton College; Hamilton College; Hamilton College hlehman@hamilton.edu
In a previous study focused on age-related division of labor in honey bee colonies we have observed that octopamine (OA) may play a role in controlling behavioral plasticity in honey bees. OA is specifically elevated in the brains of forager bees; we detected higher levels of the OA synthetic enzyme tyramine beta-hydroxylase (Tbh) mRNA in forager bees relative to nurse bees and the locations of Tbh mRNA containing neurons are consistent with the location of OAergic neurons in the bee brain. In contrast, Tbh activity was not correlated to Tbh mRNA levels. Our results indicate that OA plays a role in controlling behavioral plasticity in honey bees, however our Tbh activity results remain puzzling. We have examined the possibility that another gene exists in insects that encodes a protein structurally similar to Tbh. A bioinformatic study was used to identify genes that encode proteins similar to tyramine beta-hydroxylase. We have discovered a novel group of genes contained in all insects examined to date that encodes an approximately 70 kDa protein with ca. 30% identity to Tbh. Insect tyramine beta-hydroxylase related protein (TbhR) has many structural similarities to Tbh and dopamine beta-hydroxylase, including conserved copper binding active sites and Cys residues necessary for intramolecular disulfide bonds. Furthermore, RT-PCR studies have revealed that TbhR mRNA is expressed very early during insect development and is present later in larvae, pupae and adults. Moreover, TbhR is widely expressed in the insect nervous system, gut, salivary glands and fat body tissues, and TbhR is located within specific regions of the insect optic lobes, antennal lobes and mushroom bodies. We speculate that TbhR encodes a novel protein with putative monoxygenase activity that may be vital for nervous system development.
