Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven ‘hotspots,’ seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a ‘fertile’ subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility.
Project description:To obtain the dynamic gene expression of myelinating Schwann cells, we have employed gene expression profiling microarray as a discovery platform to analyze the gene expression of Schwann cells in different stages of myelination in an DRG neuron and SC co-culture myelinating model. Rat Schwann cells and dorsal root ganglion (DRG) neurons were cocultured and induced myelination in DMEM medium containing 15% FBS, 50 ng/ml NGF and 50 μg/ml L-ascorbic acid for 21d. During the co-cultivation, myelinating SCs at different stages dissected by Laser microdissection (LMD) in myelination model (i.e. co-culture 1d, 3d, 7d, 14d, 21d), the Schwann cells without co-culture as control samples (i.e. co-culture 0d). The results from Euclidean distance matrix, principal component analysis, and hierarchical clustering indicated that 2 nodal transitions in temporal gene expressions could segregate 3 distinct transcriptional phases within the period of DRG/SC co-culture 21 days. The 3 phases were designated as “premyelination”, “myelination”, and “mature phase”, respectively, by referring to morphological observation of post co-culture changes and gene ontology (GO) analysis.
