The morphology of antennal lobe projection neurons is controlled by a POU-domain transcription factor Bmacj6 in the silkmoth Bombyx mori

Toru Shimada,Shigehiro Namiki,Ryohei Kanzaki,Tsuguru Fujii

doi:10.1038/s41598-017-14578-4

Abstract

How to wire a neural circuit is crucial for the functioning of the nervous system. Here, we describe the neuroanatomy of the olfactory neurons in the spli mutant strain of silkmoth (Bombyx mori) to investigate the function of a transcription factor involved in neuronal wiring in the central olfactory circuit. The genomic structure of the gene Bmacj6, which encodes a class IV POU domain transcription factor, is disrupted in the spli mutant. We report the neuroanatomical abnormality in the morphology of the antennal lobe projection neurons (PNs) that process the sex pheromone. In addition to the mis-targeting of dendrites and axons, we found axonal bifurcation within the PNs. These results indicate that the morphology of neurons in the pheromone processing pathway is modified by Bmacj6.

Highlights

The functioning of the central nervous system depends on the proper wiring of individual neurons
The dendrites are confined within the toroid glomerulus and extraglomerular innervation, the process that extends outside the glomerulus, is rare in the projection neurons (PNs)
We have previously reported the dendritic distribution of macroglomerular complex (MGC) PNs, and they have wide-field branches along the mediolateral axis with multiple dendritic shafts (Fig. 1) (Figs 3 and 4 in17)

Summary

Introduction

The functioning of the central nervous system depends on the proper wiring of individual neurons. The molecular mechanisms underlying neuronal wiring have been well investigated in the olfactory system of Drosophila melanogaster. There are few studies about the genetic basis of neuronal wiring for other insect species. We investigate the olfactory system of the silkmoth, Bombyx mori, which has been used as a model for studying sex pheromone communication systems in moths. Based on comparability with Drosophila, we choose B. mori as a reference species for studying neuronal wiring[5]. To examine the function of Bmacj[6] on the neuronal development of the PNs in B. mori, we obtained the single cell morphology of the PNs in the brains of the silkmoth spli mutant using intracellular staining with a sharp-glass microelectrode. Comparing normal moth strain morphology with mutant morphology, we identify the neuroanatomical abnormality of neurons in the spli mutant of B. mori

Methods

Results

Conclusion