Differential bulbar and extrabulbar projections of diverse olfactory receptor neuron populations in the adult zebrafish (Danio rerio)

Abstract

Immunohistochemical methods were used to characterize the expression of two calcium-binding proteins, calretinin (CR) and S100, in the olfactory rosette of the adult zebrafish. These proteins are expressed in different sets of sensory neurons, and together represent a large proportion of these cells. Double immunofluorescence for CR and Gα(olf) protein, and CR immunoelectron microscopy, indicated that most CR-immunoreactive (ir) cells were ciliary neurons. Differential S100- and CR-ir projections to glomerular fields of the olfactory bulb were also observed, although these projections overlap in some glomeruli. Application of the carbocyanine dye DiI to either S100-ir or CR-ir glomerular regions led to labeling of cells mostly similar to S100-ir and CR-ir neurons, respectively. Instead, these bulbar regions project to similar telencephalic targets. On the other hand, antibodies against keyhole limpet hemocyanin (KLH)-stained numerous sensory cells in the olfactory rosette, including cells that were CR- and S100-negative. This antiserum also stained most primary bulbar projections and revealed extrabulbar olfactory primary projections coursing to the ventral area of the telencephalon through the medial olfactory tract. This extrabulbar projection was confirmed by tract-tracing with DiI. A loose association of this extrabulbar primary olfactory projection and the catecholaminergic populations of the ventral area was also observed with double tyrosine hydroxylase/KLH-like immunohistochemistry. Comparison between KLH-like-ir pathways and the structures revealed by FMRFamide immunohistochemistry (a marker of terminal ganglion cells and fibers) indicated that the KLH-like-ir extrabulbar projection was different from the terminal nerve system. The significance of the extrabulbar olfactory projection of zebrafish is discussed.

Catecholaminergic connectivity to the inner ear, central auditory, and vocal motor circuitry in the plainfin midshipman fish porichthys notatus

“…On Western blots it does not react with dopamine-betahydroxylase, phenylalanine hydroxylase, trytophan hydroxylase, dehydropteridine reductase, sepiapterin reductase or phenethanolamine-N-methyl transferase (manufacturer's data). Western blot analysis of rat and fish brain extracts, including midshipman, show similar expected bands of 59-63kDa (Adrio et al, 2011;Carrera et al, 2012;Gayoso et al, 2011;Goebrecht et al, 2014;manufacturer's data). This antibody stains the appropriate pattern (i.e., known CA populations of neurons and projection patterns) in all brain regions as previously documented in midshipman and other fish species (Carrera et al, 2012;Goebrecht et al, 2014;Kuscha et al, 2012;McLean and Fetcho, 2004a) and other vertebrates (e.g., Hayes et al, 2011;Nakano et al, 2009).…”

Superficial neuromasts facilitate non-visual feeding by larval striped bass (Morone saxatilis)

“…-4-(4-(dibutylamino)styryl) pyridinium dibromide] is taken up by intact superficial neuromasts on zebrafish larvae, causing them to fluoresce brightly, whereas ablated neuromasts show partial or no fluorescence ). In addition, we assessed the effect of neomycin on neuromast innervation, taste buds and olfactory cells using immunocytochemical staining of two calcium binding proteins found in sensory cells, S100 and calretinin, and also tubulin (Gayoso et al, 2011;Germanà et al, 2007;Levanti et al, 2008).…”

Development of the Terminal Nerve System in the Shark <b><i>Scyliorhinus canicula</i></b>

“…However, the terminal nerve discovered by Locy [1905] in elasmobranchs is not labeled after application of tracers to the olfactory organ [Yáñez et al, 2011;present results]. The same holds true for the GnRH/ NPY/FMRF immunoreactive terminal ganglion neurons of teleosts and other vertebrates [Fujita et al, 1991;Gayoso et al, 2011]. Moreover, the cells of origin of the EBOPs of bony fishes and amphibians were located in the olfactory epithelium and resemble other olfactory neurons in both morphology and neurochemical features [Hofmann and Meyer, 1992;Anadón et al, 1995;Huesa et al, 2000;Pinelli et al, 2004;Gayoso et al, 2011].…”

“…In addition, our results may also shed some light on a controversy about the nature of the terminal nerve. Immunohistochemical studies and tract-tracing experiments from the olfactory mucosa in various vertebrates (lampreys, sturgeons, teleosts, amphibians) have revealed primary projections bypassing the OB and coursing to the basal telencephalon and hypothalamus [Demski and Northcutt, 1981;Hofmann and Meyer, 1989;Fujita et al, 1991;Riddle and Oakley, 1992;Hofmann and Meyer, 1995;Pinelli et al, 2004;Gayoso et al, 2011]. Some authors have considered that these extrabulbar olfactory projections (EBOPs) form part of the terminal nerve [Hofmann and Meyer, 1989;von Bartheld, 2004], although they are not found in elasmobranchs, which possess the archetypical terminal nerve [Locy, 1905].…”