Spatial organization of nucleic acid sequences within cells.

High-resolution in situ hybridization has allowed the distribution of specific nucleic acids to be visualized within cells. This has revealed the extent to which nucleic acids exhibit intracellular spatial organization. Hybridization of nonisotopically labeled probes can be detected with high resolution using fluorescence or alkaline phosphatase for light microscopy or colloidal gold for electron microscopy. Results of this approach have shown that messenger RNAs for specific proteins, nuclear transcripts, or the gene for those transcripts all can exhibit non-random intracellular locations. Actin mRNA can be seen localized in the periphery of motile cells, just proximal to the lamellipodia. Highly localized distributions of EBV primary transcripts can be visualized in some cases creating an elongated track of specific RNA. These nuclear transcripts could be seen associated with the nuclear matrix. Further evidence indicates that the genes from which specific RNAs derive may themselves show defined spatial organization. This work sheds light on a level of cellular organization indicating that nucleic acid sequences contain spatial positioning information and therefore can influence the genesis of cellular structure and function.