Project description:The mesencephalic dopaminergic (mDA) cell system is composed by two major groups of projecting cells in the Substantia Nigra (A9 neurons) and the Ventral Tegmental Area (A10 cells). A9 neurons form the nigrostriatal pathway and are involved in regulating voluntary movements and postural reflexes. Their selective degeneration leads to Parkinsons disease (PD). We used cDNA microarrays and nanoCAGE technology coupled with Laser Capture Microdissection (LCM) to characterize the intrinsic physiological properties of A9 DA neurons. Surprisingly, we found that these cells express alpha- and beta- chains of haemoglobin. Here we report that globin-immunoreactivity decorates the majority of A9 DA neurons, a subpopulation of cortical and hippocampal astrocytes as well as mature oligodendrocytes. This pattern of expression was confirmed in different mouse strains, in rat and human. This is the first report showing that haemoglobin is expressed in the Substantia Nigra of human post mortem brain. Our data suggest that the most famed oxygen-carrying globin is not exclusively restricted to the blood, but it may play a role in the normal physiology of the brain as well as in neurodegenerative disorders. To investigate the biological effects of globin expression, alpha- and beta- chains of mouse hemoglobin were overexpressed in MN9D dopaminergic neuroblastoma cell lines. RNA from 4 replicates each of over-expressing cells and of control samples, for a total of 8 samples, were hybridized on Affymetrix GeneChip Mouse Genome 430A 2.0 Arrays. Hybridization of one of the control samples did not pass quality assessment and the sample was therefore excluded from further analysis.
Project description:The mesencephalic dopaminergic (mDA) cell system is composed by two major groups of projecting cells in the Substantia Nigra (A9 neurons) and the Ventral Tegmental Area (A10 cells). A9 neurons form the nigrostriatal pathway and are involved in regulating voluntary movements and postural reflexes. Their selective degeneration leads to Parkinson’s disease (PD). We used cDNA microarrays and nanoCAGE technology coupled with Laser Capture Microdissection (LCM) to characterize the intrinsic physiological properties of A9 DA neurons. Surprisingly, we found that these cells express alpha- and beta- chains of haemoglobin. Here we report that globin-immunoreactivity decorates the majority of A9 DA neurons, a subpopulation of cortical and hippocampal astrocytes as well as mature oligodendrocytes. This pattern of expression was confirmed in different mouse strains, in rat and human. This is the first report showing that haemoglobin is expressed in the Substantia Nigra of human post mortem brain. Our data suggest that the most famed oxygen-carrying globin is not exclusively restricted to the blood, but it may play a role in the normal physiology of the brain as well as in neurodegenerative disorders.
Project description:Our recent single-cell sequencing of most adult Drosophila circadian neurons indicated notable and unexpected heterogeneity. To address whether other populations are similar, we sequenced a large subset of adult brain dopaminergic neurons. Their gene expression heterogeneity is similar to that of clock neurons, i.e., both populations have two to three cells per neuron group. There was also unexpected cell-specific expression of neuron communication molecule messenger RNAs: G protein–coupled receptor or cell surface molecule (CSM) transcripts alone can define adult brain dopaminergic and circadian neuron cell type. Moreover, the adult expression of the CSM DIP-beta in a small group of clock neurons is important for sleep. We suggest that the common features of circadian and dopaminergic neurons are general, essential for neuronal identity and connectivity of the adult brain, and that these features underlie the complex behavioral repertoire of Drosophila.
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:Translational research is commonly performed in the C57B6/J mouse strain, chosen for its genetic homogeneity and phenotypic uniformity. Here, we evaluate the suitability of the white-footed deer mouse (Peromyscus leucopus) as a model organism for aging research, offering a comparative analysis against C57B6/J and diversity outbred (DO) Mus musculus strains. Our study includes comparisons of body composition, skeletal muscle function, and cardiovascular parameters, shedding light on potential applications and limitations of P. leucopus in aging studies. Notably, P. leucopus exhibits distinct body composition characteristics, emphasizing reduced muscle force exertion and a unique metabolism, particularly in fat mass. Cardiovascular assessments showed changes in arterial stiffness, challenging conventional assumptions and highlighting the need for a nuanced interpretation of aging-related phenotypes. Our study also highlights inherent challenges associated with maintaining and phenotyping P. leucopus cohorts. Behavioral considerations, including anxiety-induced responses during handling and phenotyping assessment, pose obstacles in acquiring meaningful data. Moreover, the unique anatomy of P. leucopus necessitates careful adaptation of protocols designed for Mus musculus. While showcasing potential benefits, further extensive analyses across broader age ranges and larger cohorts are necessary to establish the reliability of P. leucopus as a robust and translatable model for aging studies.
Project description:In genomes of modern fish and amphibia α- and β- globin genes are grouped at a single locus that may resemble the ancestral one and is syntenic to α-globin locus of modern warm-blooded vertebrates. In Danio rerio, the major locus of α/β globin genes comprises two subclusters, one of them harboring genes expressed in adult and the other – genes expressed in embryonic and larval erythrocytes. The results of our previous study suggested that the adult subcluster of this locus has evolved into α-globin gene domain of vertebrate animals. Here we studied how adult and embryo-larval genes of Danio rerio major globin gene locus are repressed in fibroblasts. The results obtained suggest that that at least some of the globin genes present within the adult subcluster are repressed by Polycomb similarly to human α-globin genes. Furthermore, within two α/β gene pairs repression of α-type and β-type genes appears to be mediated by different mechanisms as increasing the level of histone acetylation can activate transcription of only β-type genes.
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.