Expression Pattern of nos1 in the Developing Nervous System of Ray-Finned Fish

Abstract


 Fish have colonized nearly all aquatic niches, making them an invaluable resource to understand vertebrate adaptation and gene family evolution, including the evolution of complex neural networks and modulatory neurotransmitter pathways. Among ancient regulatory molecules, the gaseous messenger nitric oxide (NO) is involved in a wide range of biological processes. Because of its short half-life, the modulatory capability of NO is strictly related to the local activity of nitric oxide synthases (Nos), enzymes that synthesize NO from L-arginine, making the localization of Nos mRNAs a reliable indirect proxy for the location of NO action domains, targets, and effectors. Within the diversified actinopterygian nos paralogs, nos1 (alias nnos) is ubiquitously present as a single copy gene across the gnathostome lineage, making it an ideal candidate for comparative studies. To investigate variations in the NO system across ray-finned fish phylogeny, we compared nos1 expression patterns during the development of two well-established experimental teleosts (zebrafish and medaka) with an early branching holostean (spotted gar), an important evolutionary bridge between teleosts and tetrapods. Data reported here highlight both conserved expression domains and species-specific nos1 territories, confirming the ancestry of this signaling system and expanding the number of biological processes implicated in NO activities.

Evolution of the nitric oxide synthase family in vertebrates and novel insights in gill development

“…Therefore, we examined the expression patterns of nos genes during gar development. As expected, nos1 was expressed in several regions of the developing nervous system (electronic supplementary material, figure S3, and [21]). By contrast, nos2 expression was not detected during the developmental stages covered in the present study, i.e.…”

Exposure of Zebrafish Embryos to Urea Affects NOS1 Gene Expression in Neuronal Cells

“…This observation seems to agree with previous evidence in ray-finned fish, where the expression pattern of NOS1 has been described to be dynamic during development. Studies of whole-mount in situ hybridization in fish embryos showed that at 24 h post-fertilization (hpf) nos1-positive cells are highly present in dorsal telencephalon and in pallium, which represent the main neurogenesis regions of developing fish; then, at 72 hpf, nos1 expression appears also in the olfactory bulbs, mesencephalon, cerebellum, and rhombencephalon, while at 5 days post-fertilization (dpf), nos1 signal spreads in different areas within the forebrain [53].…”

Nitric Oxide Function and Nitric Oxide Synthase Evolution in Aquatic Chordates

“…In ray-finned fish, early expression of Nos1 mRNA in the CNS has been shown [ 55 , 91 , 104 , 146 ]. In adult teleosts, peripheral organs contain Nos1, as in mammals [ 147 , 148 ].…”

“…Although the distribution of Nos1-expressing cells seems to be conserved in most teleosts, with a high degree of detection in the telencephalon and diencephalon and reduced expression in more caudal brain regions [ 55 , 155 ], diversity of function can be observed. For example, in the African cichlid fish Astatotilapia burtoni , Nos1-expressing cells were found in the inner nuclear layer and from the olfactory bulbs to the hindbrain, including within specific nuclei involved in decision-making, sensory processing, neuroendocrine regulation, and the expression of social behaviors [ 156 ].…”