Project description:We report the application of Chromosome Conformation Capture Carbon-copy (5C) to a 4.5 Mb stretch of the mouse X chromosome encompassing the X inactivation center locus. We uncover a series of discrete 200kb-1Mb topologically associating domains (TADs). These align with several domain-wide epigenomic features as well as co-regulated gene clusters. 5C analysis in EED and G9A mutants reveal that this segmental organisation in TADs does not relie on the underlying H3K27me3 or H3K9me2 blocks. Deletion of a boundary between two TADs leads to ectopic chromosomal contacts between them. Analysis of mESCs, mNPCs and MEFs suggest that the positioning of TADs on the chromosome is stable during cell differentiation though their internal organisation changes. Comparison of male (XY) and female (XX) differentiated cells highlights that the long-range chromosomal contacts within TADs are dampened on the inactive X compared to the active X. 5C oligonucleotides were designed around HindIII restriction site following an alternative scheme
Project description:Gene expression microarrays have made a profound impact in biomedical research. The diversity of platforms and analytical methods has made comparison of data from multiple platforms very challenging. In this study, we describe a framework for comparisons across platforms and laboratories. We have attempted to include nearly all the available commercial and “in-house” platforms. Using probe sequences matched at the exon level improved consistency of measurements across the different microarray platforms compared to annotation-based matches. Generally, consistency was good for highly expressed genes, and variable for genes with lower expression values as confirmed by QRT-PCR. Concordance of measurements was higher between laboratories on the same platform than across platforms. We demonstrate that, after stringent pre-processing, commercial arrays were more consistent than “in-house” arrays, and by most measures, one-dye platforms were more consistent than two-dye platforms. Keywords: cross platform microarrays