Project description:To quantify gene expression differences in olfactory epithelium between the mouse (Mus musculus) and the Nile rat (Arvicanthis niloticus), paired-end RNA sequencing (RNA-seq) was used to profile olfactory epithelium transcriptomes of six Nile rats and six mice (C57BL/6J) (one male and one female at the age of 8, 12, and 16 weeks for each species).
Project description:The olfactory epithelium contains two basal stem cell populations that facilitate the normally life-long ability for neuronal regeneration that is required for maintaining our sense of smell over the long term. Horizontal basal cells (HBCs) are generally quiescent and only become active after direct injury to the epithelium that kills more than just the olfactory sensory neurons (OSNs). Globose basal cells (GBCs) lie apical to HBCs and are solely responsible for the ongoing generation of olfactory neurons in the undamaged epithelium. Understanding how these two neurogenic stem cell populations are regulated as OSNs are replenished is hampered by a lack of robust culture models. Here, we report the development of a 3-dimensional organoid model that recapitulates the neurogenic cascade while maintaining both HBCs and GBCs in culture. We use this model to demonstrate that despite their relative quiescence, HBCs form a critical niche for the emergence and composition of the organoid.
Project description:A reduced sense of smell has been reported in people with cystic fibrosis (CF). These olfactory defects have largely been attributed to secondary manifestations of the disease, such as inflammation of the nasal mucosa. Here we show that CFTR, the gene responsible for CF, is expressed in proliferating olfactory human cells and that newborn CFTR null pigs display ultrastructural abnormalities in the olfactory epithelium and olfactory bulbs. In the absence of CFTR, olfactory sensory neurons still produce odor-evoked activity, but mutant animals display defective odor-guided suckling behavior after birth. Consistent with epithelial changes, we found a reduced expression of genes implicated in cell cycle and development in globose basal cells (GBCs), the neurogenic progenitor cells in the olfactory epithelium. Targeted sequencing revealed enhanced CFTR expression in the subpopulation of GBCs that is actively proliferating. Furthermore, CFTR loss caused a global reduction in the number of sensory neurons and altered olfactory receptors expression. Our findings highlight a previously unknown role of CFTR in olfactory system function by regulating progenitor cell proliferation in the olfactory epithelium.
Project description:A reduced sense of smell has been reported in people with cystic fibrosis (CF). These olfactory defects have largely been attributed to secondary manifestations of the disease, such as inflammation of the nasal mucosa. Here we show that CFTR, the gene responsible for CF, is expressed in proliferating olfactory human cells and that newborn CFTR null pigs display ultrastructural abnormalities in the olfactory epithelium and olfactory bulbs. In the absence of CFTR, olfactory sensory neurons still produce odor-evoked activity, but mutant animals display defective odor-guided suckling behavior after birth. Consistent with epithelial changes, we found a reduced expression of genes implicated in cell cycle and development in globose basal cells (GBCs), the neurogenic progenitor cells in the olfactory epithelium. Targeted sequencing revealed enhanced CFTR expression in the subpopulation of GBCs that is actively proliferating. Furthermore, CFTR loss caused a global reduction in the number of sensory neurons and altered olfactory receptors expression. Our findings highlight a previously unknown role of CFTR in olfactory system function by regulating progenitor cell proliferation in the olfactory epithelium.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:Expression profiling of mRNA abundance in the adult mouse olfactory epithelium during replacement of OSNs forced by the bilateral ablation of the olfactory bulbs. The experiment was done on 6 week old male C57Bl/6 mice. Olfactory epithelium tissue samples were collected on days 1, 5, and 7 after bulbectomy. The cellular processes activated by bulbectomy include apoptosis of mature olfactory sensory neurons, infiltration of macrophages and dendritic cells, stimulation of proliferation of basal cell progenitors, and differentation of new sensory neurons.