The peripheral olfactory system of vertebrates contains olfactory receptor neurons (ORNs) that convey infor-mation to the central nervous system. In teleosts three types of ORNs have been identified denominated cili-ated, microvillous, and crypt neurons. Crypt neurons can be distinguished on the basis of their morphology, the expression of different families of odorant receptor molecules, the presence of receptors for neurotrophic factors, the occurrence of cytosolic Ca2+-binding proteins and ion channels, and the central projections to the central nervous system. The zebrafish is an attractive model for studying the cellular and molecular basis of behaviours in which the olfaction plays a key role. S100 protein and the ion channel TRPV4 have been de-tected in heterogeneous olfactory cells and both are candidates to be present in crypt neurons. Here we have investigated the occurrence of S100 protein and TRPV4 in the olfactory crypt neurons of adult zebrafish (Danio rerio) using double immunofluorescence associated to laser confocal microscopy. Calretinin (CR) was used as a specific marker for all crypt neurons. An additional ultrastructural study was carried out. CR positive cells were found in the sensory segment of olfactory lamellae while S100 positivity was restricted to a subpopula-tion of superficial mature crypt neurons, and non mature crypt cells were CR+/S100P-. Therefore, the acquisi-tion of S100 protein is an evidence of crypt neurons maturation. Conversely TRPV4 identified ORNs but never co-localise with CR, thus excluding the presence of this ion channel in the crypt neurons. The functional sig-nificance of these findings remains to be elucidated.

Mature olfactory crypt neurons in adult zebrafish express S100 pro-tein and lack TRPV4

GUERRERA, Maria Cristina;ABBATE, Francesco;GERMANA', Antonino
2013-01-01

Abstract

The peripheral olfactory system of vertebrates contains olfactory receptor neurons (ORNs) that convey infor-mation to the central nervous system. In teleosts three types of ORNs have been identified denominated cili-ated, microvillous, and crypt neurons. Crypt neurons can be distinguished on the basis of their morphology, the expression of different families of odorant receptor molecules, the presence of receptors for neurotrophic factors, the occurrence of cytosolic Ca2+-binding proteins and ion channels, and the central projections to the central nervous system. The zebrafish is an attractive model for studying the cellular and molecular basis of behaviours in which the olfaction plays a key role. S100 protein and the ion channel TRPV4 have been de-tected in heterogeneous olfactory cells and both are candidates to be present in crypt neurons. Here we have investigated the occurrence of S100 protein and TRPV4 in the olfactory crypt neurons of adult zebrafish (Danio rerio) using double immunofluorescence associated to laser confocal microscopy. Calretinin (CR) was used as a specific marker for all crypt neurons. An additional ultrastructural study was carried out. CR positive cells were found in the sensory segment of olfactory lamellae while S100 positivity was restricted to a subpopula-tion of superficial mature crypt neurons, and non mature crypt cells were CR+/S100P-. Therefore, the acquisi-tion of S100 protein is an evidence of crypt neurons maturation. Conversely TRPV4 identified ORNs but never co-localise with CR, thus excluding the presence of this ion channel in the crypt neurons. The functional sig-nificance of these findings remains to be elucidated.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/2548031
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