Genome-wide analysis of hepatic gene silencing in mammalian cell hybrids.

Silencing of tissue-specific gene expression in mammalian somatic cell hybrids is a well-documented epigenetic phenomenon which is both profound (involving a large number of genes) and enigmatic. Our aim was to utilize whole-genome microarray analyses to determine the true extent of gene silencing on a genomic level. By comparing gene expression profiles of hepatoma×fibroblast cell hybrids with those of parental cells, we have identified over 300 liver-enriched genes that are repressed at least 5-fold in the cell hybrids, the majority of which are repressed at least 10-fold.

(±)-3-Carb-oxy-2-(imidazol-3-ium-1-yl)-propanoate.

The title compound, C(7)H(8)N(2)O(4), crystallizes as a zwitterion, with mol-ecules organized into mol-ecular sheets via carbox-yl-carboxyl-ate and N(+)-H⋯carboxyl-ate contacts. These sheets are constructed from translationally related mol-ecules that further link to neighboring motifs via π-stacking [centroid-centroid distance 3.504 (3) Å] and weak C-H⋯O contacts.