The new paradigm: integrating genomic function and nuclear architecture.

A new view of the cell nucleus is emerging based on the functional dynamics of nuclear architecture. The striking structural preservation of a variety of genomic processes on the nuclear matrix provides an important approach for correlating nuclear form and function. In situ labeling coupled with three-dimensional microscopy and computer imaging techniques shows that DNA replication and transcription sites are organized into higher-order units, or "zones," in the cell nucleus. The dynamic interplay and "re-zoning" of replication and transcription regions during the cell cycle may form the structural basis for the elaborate global coordination of replicational and transcriptional programs in the mammalian cell.