Olfactory Sensory Neuron Morphotypes in the Featherback Fish, Notopterus notopterus (Osteoglossiformes: Notopteridae)

Tissue Microenvironments in the Nasal Epithelium of Rainbow Trout (Oncorhynchus mykiss) Define Two Distinct CD8α+ Cell Populations and Establish Regional Immunity

Mucosal surfaces require balancing different physiological roles and immune functions. To effectively achieve multifunctionality, mucosal epithelia have evolved unique microenvironments that create unique regional immune responses without impairing other normal physiological functions. Whereas examples of regional immunity are known in other mucosal epithelia, to date, no immune microenvironments have been described in the nasal mucosa, a site where the complex functions of olfaction and immunity need to be orchestrated. In this study we identified the presence of CD8α⁺ cells in the rainbow trout (Oncorhynchus mykiss) nasal epithelium. Nasal CD8α⁺ cells display a distinct phenotype suggestive of CD8⁺ T cells with high integrin β₂ expression. Importantly, nasal CD8α⁺ cells are located in clusters at the mucosal tip of each olfactory lamella but scattered in the neuroepithelial region. The grouping of CD8α⁺ cells may be explained by the greater expression of CCL19, ICAM-1, and VCAM-1 in the mucosal tip compared with the neuroepithelium. Whereas viral Ag uptake occurred via both tip and lateral routes, tip-resident MHC class II⁺ cells are located significantly closer to the lumen of the nasal cavity than are their neuroepithelial counterparts, therefore having quicker access to invading pathogens. Our studies reveal compartmentalized mucosal immune responses within the nasal mucosa of a vertebrate species, a strategy that likely optimizes local immune responses while protecting olfactory sensory functions.

Transcriptomic profiles of the upper olfactory rosette in cultured and wild Senegalese sole (Solea senegalensis) males

The aims of this study were the characterization of the upper olfactory epithelium of cultured and wild Senegalese sole mature males at histological and transcriptomic (using RNA-Seq) level. No significant differences in tissue structure, cell types and cellular distribution pattern (olfactory sensory neurons) were identified between cultured and wild specimens. Deep transcriptomic analysis showed 2387 transcripts were differentially expressed between cultured and wild groups. A detailed analysis identified the differentially expressed transcripts included some olfactory receptors (OR, TAAR and V2R-like) and transcripts related with the control of reproduction such as the brain aromatase cytochrome P450 and tachykinin-3. Also a wide set of genes related with lipid sensing, metabolism and transport were differentially expressed and these transcripts were often down-regulated in cultured fish. Furthermore, cultured males presented a higher expression of genes related with goblet cells and mucin production that modulates innate and adaptive immune responses. All these changes in gene expression could be explained by different nutritional status and diet preference. The different expression of transcripts related to olfaction, reproduction, nutrient sensing and immune system demonstrate distinct differences in functionalities between cultured and wild soles providing new clues about the sexual dysfunction in this species.