RT Journal Article SR Electronic T1 Characterization of Drosophila Tyramine β-HydroxylaseGene and Isolation of Mutant Flies Lacking Octopamine JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 3900 OP 3911 DO 10.1523/JNEUROSCI.16-12-03900.1996 VO 16 IS 12 A1 Monastirioti, Maria A1 Linn, Jr., Charles E. A1 White, Kalpana YR 1996 UL http://www.jneurosci.org/content/16/12/3900.abstract AB Octopamine is likely to be an important neuroactive molecule in invertebrates. Here we report the molecular cloning of theDrosophila melanogaster gene, which encodes tyramine β-hydroxylase (TBH), the enzyme that catalyzes the last step in octopamine biosynthesis. The deduced amino acid sequence of the encoded protein exhibits 39% identity to the evolutionarily related mammalian dopamine β-hydroxylase enzyme. We generated a polyclonal antibody against the protein product of Tβh gene, and we demonstrate that the TBH expression pattern is remarkably similar to the previously described octopamine immunoreactivity inDrosophila. We further report the creation of null mutations at the Tβh locus, which result in complete absence of TBH protein and blockage of the octopamine biosynthesis.Tβh-null flies are octopamine-less but survive to adulthood. They are normal in external morphology, but the females are sterile, because although they mate, they retain fully developed eggs. Finally, we demonstrate that this defect in egg laying is associated with the octopamine deficit, because females that have retained eggs initiate egg laying when transferred onto octopamine-supplemented food.