Chromosome Territory Organization within the Nucleus

Quantitative analyses of the dynamic organization of chromosomes in cycling and postmitotic cells are indispensable attributes of a systematic approach, necessary to describe the structural basis of nuclear functions such as cell type-specific gene expression patterns. It is now known that this organization changes to a surprising extent during normal development, as well as normal and pathological cell differentiation. To set the stage, a brief account is provided of the origins of chromosome research, including the seminal observations that led Theodor Boveri to his concept of chromosome territories (CTs) in the early twentieth century. Compelling experimental proof is then provided in favor of CTs, which was obtained during the 1970s and 1980s. Thereafter, current evidence is described for nonrandom nuclear CT arrangements and various models of CT organization, which have been developed to date. The chapter is concluded with a vision to generate complete four-dimensional (4-D; space–time) maps of nuclear landscapes from a range of species selected from different parts of the evolutionary tree. The generation of such 4-D maps is important to distinguish evolutionary highly conserved features from species and cell type-specific peculiarities of nuclear architectures. Today, their generation has become possible based on a combination of three-dimensional (3-D) and 4-D light optical nanoscopy, 3-D electron microscopic approaches with new high-throughput genome-wide analyses of nonrandom DNA–DNA proximity patterns, as well as protein–protein and DNA–protein interactions within and between CTs. Keywords: Chromosome territory (CT) .; Chromatin domain (CD) .; Interchromatin compartment (IC) .; Perichromatin region (PR) .