XB-ART-48018Anat Rec (Hoboken) September 1, 2013; 296 (9): 1453-61.
Exotic models may offer unique opportunities to decipher specific scientific question: the case of Xenopus olfactory system.
The fact that olfactory systems are highly conserved in all animal species from insects to mammals allow the generalization of findings from one species to another. Most of our knowledge about the anatomy and physiology of the olfactory system comes from data obtained in a very limited number of biological models such as rodents, Zebrafish, Drosophila, and a worm, Caenorhabditis elegans. These models have proved useful to answer most questions in the field of olfaction, and thus concentrating on these few models appear to be a pragmatic strategy. However, the diversity of the organization and physiology of the olfactory system amongst phyla appear to be greater than generally assumed and the four models alone may not be sufficient to address all the questions arising from the study of olfaction. In this article, we will illustrate the idea that we should take advantage of biological diversity to address specific scientific questions and will show that the Xenopus olfactory system is a very good model to investigate: first, olfaction in aerial versus aquatic conditions and second, mechanisms underlying postnatal reorganization of the olfactory system especially those controlled by tyroxine hormone.
PubMed ID: 23904180
Article link: Anat Rec (Hoboken)
Species referenced: Xenopus laevis
Genes referenced: gnao1
Article Images: [+] show captions
|Figure 1. General organization of the olfactory system. A: Waterborne or airborne odorant penetrate the mucus in which the cilia of the Olfactory Receptor Neurons (ORN) bathe. At this level, they bind the olfactory receptors (ORs) alone or with the help of Olfactory Binding Proteins (OBP) which may solubilize the insoluble odorants. Then, the olfactory signal is transduced by the ORN and transferred to the Olfactory Bulb via axons which go through the cribriform plate. At the level of the OB, all the ORN converge onto a small number of glomeruli, which are functional subunits. Local interneurons then shape the olfactory signal (reduction of noise and amplification) and output neurons export the signal towards the upper center of the olfactory cortex. B: General overview of the tadpole head. Amongst other cephalic organs, the olfactory system is visible without dissection thanks to the transparency of the epithelium. Thanks to injection of DiI (Red) in the left olfactory cavity and of DiO (green) in the right olfactory cavity, projections of ORN can be traced to the Olfactory Bulb.|
|Overview of the tadpole head., with several organ. The olfactory system is visible without dissection due to the transparency of the Xenopus epithelium. The injection of DiI (Red) in the left olfactory cavity/pit and of DiO (green) in the right olfactory cavity/pit, highlights projections of Olfactory nerve, which can be traced to the Olfactory Bulb, which projects from the anterior surface of the anterior forebrain, the telecephalon.|