Project description:Molecular mechanisms controlling specification and differentiation of distinct neuron subtypes in the cerebral cortex are not well understood. Corticothalamic projection neurons (CThPN) are a diverse set of neurons, critical for function of the neocortex, but little is known about the molecular mechansims controlling their development. We used microarrays to detail CThPN gene expression at 3 developmental time points. We then compared CThPN gene expression, with the gene expression of other neuron subtypes in the cerebral cortex at the same stages (previously described in Arlotta et a., 2005) CThPN were retrogradely label with fluorescent microespheres injected into the thalamus, and were FACS purified at 3 developmental stages for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Molecular mechanisms over differentiation and differential axonal targeting of distinct neuron subtypes in the cerebral cortex are beginning to be elucidated. These studies have focused on controls that specifically distinguish one subtype of neocortical projection neurons, e.g. corticospinal motor neurons (CSMN), from closely related corticothalamic projection neurons (CThPN) or intracortical callosal projection neurons (CPN). CSMN are located in layer V of the neocortex and make synaptic connections to motor output circuitry in the spinal cord and brainstem. CSMN axons form the corticospinal tract (CST), which is the major motor output pathway from the motor cortex and critically controls voluntary movement. CSMN somatotopically and precisely target specific segments along the rostrocaudal axis of the spinal cord, the molecular basis for which remains unknown. We used microarrays to examine gene expression differences between two CSMN subpopulations that target different levels of the spinal cord - CSMN-C (which extend axons to the brainstem and cervical spinal cord) and CSMN-L (which preferrrentially extend axons to the thoracic and lumbar spinal cord). We compared CSMN-C vs CSMN-L gene expression at 3 critical developmental time points (previously described in Arlotta et a., 2005)
Project description:Molecular mechanisms controlling specification and differentiation of distinct neuron subtypes in the cerebral cortex are not well understood. Corticothalamic projection neurons (CThPN) are a diverse set of neurons, critical for function of the neocortex, but little is known about the molecular mechansims controlling their development. We used microarrays to detail CThPN gene expression at 3 developmental time points. We then compared CThPN gene expression, with the gene expression of other neuron subtypes in the cerebral cortex at the same stages (previously described in Arlotta et a., 2005)
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:We use comprehensive and unsupervised transcriptome analyses to provide molecular classifications of sensory neurons in the mouse geniculate ganglion. 96 neurons were isolated on a C1 Fluodigm chip, underwent RNA-Seq, and iteratively clustered into sub-classes.