# olf413 an octopamine biogenesis pathway gene is required for axon growth and pathfinding during embryonic nervous system development in Drosophila melanogaster

## TL;DR

This study shows that the olf413 gene is essential for octopamine production and proper development of the nervous system in fruit fly embryos.

## Contribution

The study identifies a novel developmental role for an octopamine biosynthesis gene in axon growth and pathfinding.

## Key findings

- olf413 is required for octopamine biogenesis and its loss leads to reduced octopamine levels.
- Loss of olf413 causes embryonic lethality and defects in axon growth, pathfinding, and branching.
- The gene shows enhancer activity in the embryonic nervous system and somatic muscle bundles.

## Abstract

Neurotransmitters have been extensively studied as neural communication molecules. Genetic associations discovered, and indirect intervention studies in Humans and mammals have led to a general proposition that neurotransmitters have a role in structuring of neuronal network during development. olf413 is a Drosophila gene annotated as coding for dopamine beta-monooxygenase enzyme with a predicted function in octopaminergic pathway. The biological function of this gene is very little worked out. In this study we investigate the requirement of olf413 gene function for octopamine biogenesis and developmental patterning of embryonic nervous system.

In our study we have used the newly characterized neuronal specific allele olf413SG1.1, and the gene disruption strain olf413MI02014 to dissect out the function of olf413. olf413 has an enhancer activity as depicted by reporter GFP expression, in the embryonic ventral nerve cord, peripheral nervous system and the somatic muscle bundles. Homozygous loss of function mutants show reduced levels of octopamine, and this finding supports the proposed function of the gene in octopamine biogenesis. Further, loss of function of olf413 causes embryonic lethality. FasII staining of these embryos reveal a range of phenotypes in the central and peripheral motor nerves, featuring axonal growth, pathfinding, branching and misrouting defects. Our findings are important as they implicate a key functional requirement of this gene in precise axonal patterning events, a novel developmental role imparted for an octopamine biosynthesis pathway gene in structuring of embryonic nervous system.