Morphogenetic Studies of the Drosophila DA1 Ventral Olfactory Projection Neuron

Hung-Chang Shen,Sao-Yu Chu,Tsai-Chi Hsu,Hung-Hsiang Yu,Jia-Yi Wei,Pei-Chi Chung

doi:10.1371/journal.pone.0155384

Abstract

In the Drosophila olfactory system, odorant information is sensed by olfactory sensory neurons and relayed from the primary olfactory center, the antennal lobe (AL), to higher olfactory centers via olfactory projection neurons (PNs). A major portion of the AL is constituted with dendrites of four groups of PNs, anterodorsal PNs (adPNs), lateral PNs (lPNs), lateroventral PNs (lvPNs) and ventral PNs (vPNs). Previous studies have been focused on the development and function of adPNs and lPNs, while the investigation on those of lvPNs and vPNs received less attention. Here, we study the molecular and cellular mechanisms underlying the morphogenesis of a putative male-pheromone responding vPN, the DA1 vPN. Using an intersection strategy to remove background neurons labeled within a DA1 vPN-containing GAL4 line, we depicted morphological changes of the DA1 vPN that occurs at the pupal stage. We then conducted a pilot screen using RNA interference knock-down approach to identify cell surface molecules, including Down syndrome cell adhesion molecule 1 and Semaphorin-1a, that might play essential roles for the DA1 vPN morphogenesis. Taken together, by revealing molecular and cellular basis of the DA1 vPN morphogenesis, we should provide insights into future comprehension of how vPNs are assembled into the olfactory neural circuitry.

Highlights

Ensembles of neurons are linked into complex neural circuits in the nervous system in which animals use them to process environmental information, e.g., light, sound and odors, etc., for survival and offspring reproduction
We identified R95B09- GAL4 (Bloomington stock number (BL) 47276) which labels a single DA1 ventral PNs (vPNs) together with background neurons in brain regions outside of the antennal lobe (AL) [7]. For this DA1 vPN, the dense dendritic innervation was clearly seen in the DA1 glomerulus at the AL, while some loose dendritic arborizations were detected in the ventral AL
We sought to identify whether R95B09-GAL4 labels the DA1 vPN throughout morphogenesis since GAL4 lines may label neurons in a transient and yet complex pattern over the course of development that makes them unsuitable for examining the effects of genetic perturbation on the development of neurons of interest (e.g., a group of dorsal neurons that project their neurites ventrally to the middle of the central brain and bifurcate their neurites medially and laterally to the midline and optic lobes can be seen from early larval to early pupal stages, but they gradually diminished after mid-late pupal stage (Fig 1G–1I))

Summary

Introduction

Ensembles of neurons are linked into complex neural circuits in the nervous system in which animals use them to process environmental information, e.g., light, sound and odors, etc., for survival and offspring reproduction. Odorant signals are modulated by LNs, and relayed by PNs to higher olfactory centers, e.g., mushroom body and lateral horn (LH), for further decoding of the olfactory information [2] These PNs and LNs are derived from at least five neural stem cells; the derived neurons include three clusters of PNs (anterodorsal PNs (adPNs in the ALad lineage), ventral PNs (vPNs in the ALv1 lineage), and lateroventral PNs (in the ALlv lineage)), a set of ventral LNs (in the ALv2 lineage), and a lateral population of mixed PNs and LNs (in the ALl1 lineage) [3]. Revealing the molecular and cellular mechanisms underlying the morphogenesis of vPNs and lvPNs will advance our understanding of how multiple populations of neurons are integrated into the functional olfactory system during development

Methods

Results

Conclusion