Higher levels of organization in the interphase nucleus of cycling and differentiated cells

The review examines the structured organization of interphase nuclei using a range of examples from the plants, animals, and fungi. Nuclear organizati on is shown to be an important phenomenon in cell differentiation and devel opment. The review commences by examining nuclei in dividing cells and show s that the organization patterns can be dynamic within the time frame of th e cell cycle. When cells stop dividing, derived differentiated cells often show quite different nuclear organizations. The developmental fate of nucle i is divided into three categories. (i) The first includes nuclei that unde rgo one of several forms of polyploidy and can themselves change in structu re during the course of development. Possible function roles of polyploidy is given. (ii) The second is nuclear reorganization. without polyploidy, wh ere nuclei reorganize their structure to form novel arrangements of protein s and chromosomes. (iii) The third is nuclear disintegration linked to prog rammed cell death. The role of the nucleus in this process is described The review demonstrates that recent methods to probe nuclei for nucleic acids and proteins, as well as to examine their intranuclear distribution in vivo , has revealed much about nuclear structure. It is clear that nuclear organ ization can influence or be influenced by cell activity and development. Ho wever, the full functional role of many of the observed phenomena has still to be fully realized.