A single identified glomerulus in the zebrafish olfactory bulb carries the high-affinity response to death-associated odor cadaverine

Abstract

The death-associated odor cadaverine, generated by bacteria-mediated decarboxylation of lysine, has been described as the principal activator of a particular olfactory receptor in zebrafish, TAAR13c. Low concentrations of cadaverine activated mainly TAAR13c-expressing olfactory sensory neurons, suggesting TAAR13c as an important element of the neuronal processing pathway linking cadaverine stimulation to a strongly aversive innate behavioral response. Here, we characterized the initial steps of this neuronal pathway. First we identified TAAR13c-expressing cells as ciliated neurons, equivalent to the situation for mammalian taar genes, which shows a high degree of conservation despite the large evolutionary distance between teleost fishes and mammals. Next we identified the target area of cadaverine-responsive OSNs in the olfactory bulb. We report that cadaverine dose-dependently activates a group of dorsolateral glomeruli, at the lowest concentration down to a single invariant glomerulus, situated at the medial border of the dorsolateral cluster. This is the first demonstration of a single stereotyped target glomerulus in the fish olfactory system for a non-pheromone odor. A mix of different amines activates many glomeruli within the same dorsolateral cluster, suggesting this area to function as a general amine response region.

Morphology and immunohistochemistry of the olfactory organ in the bloodfin tetra, Aphyocharax anisitsi (Ostariophysi: Characidae)

“…Gαolf is a mature ORN marker and that in zebrafish it allowed the recognition of the dendrite knobs of cORNs (Dieris et al, 2017), Gαolf antiserum was useful to identify cORNs in A. anisitsi. In addition, the ir-OMP ORNs exhibited the same morphology and location as cORNs identified by the histological study, similar to that observed in D. rerio (Sato et al, 2007) and…”

Olfactory sensory neurons mediate ultrarapid antiviral immune responses in a TrkA-dependent manner

“…TrkA-Dependent Manner. Studies in fish have demonstrated that pERK staining and c-fos gene expression are suitable markers of neuronal activation upon odorant exposure in the OO and CNS (23,24). However, whether viruses activate neurons in the OO and OB has not been investigated.…”

Trace Amines and Their Receptors

“…Trace Amines and Their Receptors project to dorsolateral glomeruli of the olfactory bulb, evoking innate avoidance behavior (Hussain et al, 2013;Dieris et al, 2017). Structure-activity analysis indicated that TAAR13c has a preference for medium-sized diamines containing an odd number of carbons and contains a nonclassic monoamine recognition pocket with two distinct cation recognition sites (Hussain et al, 2013).…”

“…Neurons expressing a functional TAAR do not express other TAARs or olfactory receptors, whereas neurons expressing a TAAR pseudogene may express a second TAAR (Liberles and Buck, 2006;Johnson et al, 2012;Pacifico et al, 2012). Expressed TAAR proteins are found in the olfactory cilia, the site of odor detection, and axons project to distinct glomeruli within the dorsomedial domain of the olfactory bulb (Pacifico et al, 2012;Dieris et al, 2017), although this may be developmentally regulated in some species (Gliem et al, 2009;Shao et al, 2017). Like classic olfactory receptor neurons, TAAR neurons express G olf and related signaling proteins, and inhibition of adenylyl cyclase blocks the odor-related responses of TAAR neurons (Liberles and Buck, 2006;Ferrero et al, 2012;Zhang et al, 2013).…”