The crowded nucleus

The principles that determine the organization of the nucleus have become clearer in recent years, largely because of new insights into polymer, colloid, and soft-matter science. Macromolecules, together with the giant linear polymers that form the chromosomes, are confined at high concentrations within the nuclear envelope and their interactions are influenced strongly by short-range depletion or entropic forces which are negligible in dilute systems, in addition to the more familiar van der Waals, electrostatic, steric, hydrogen bonding, and hydrophobic forces. The studies described in this volume are consistent with the model that this complex and concentrated mixture of macromolecules is maintained in a delicate equilibrium by quite simple although unsuspected physicochemical principles. The sensitivity of this equilibrium to perturbation may underlie the controversies about the existence of a nuclear matrix or scaffold. In this volume, we underline the importance for cell biologists of being familiar with current work in colloid, polymer, soft matter, and nanoscience. This chapter presents a brief background to the aspects of the nucleus that are considered in detail in subsequent chapters.