Vol. 9, Issue 11, 3147-3159, November 1998

The Three-dimensional Study of Chromosomes and Upstream Binding Factor-immunolabeled Nucleolar Organizer Regions Demonstrates Their Nonrandom Spatial Arrangement during Mitosis

Christophe Klein, Thierry Cheutin, Marie-Françoise O'Donohue, Lawrence Rothblum,^* Hervé Kaplan, Adrien Beorchia, Laurent Lucas, Laurent Héliot, and Dominique Ploton

Unité 314 Institut National de la Santé et de la Recherche Médicale, Laboratoire Pol Bouin and IFR 53, 51092 Reims Cedex France; and  ^*Geisinger Clinic, S. and J. Weis Center for Research, Danville, Pennsylvania 17822

The volumic rearrangement of both chromosomes and immunolabeled upstream binding factor in entire well-preserved mitotic cells was studied by confocal microscopy. By using high-quality three-dimensional visualization and tomography, it was possible to investigate interactively the volumic organization of chromosome sets and to focus on their internal characteristics. More particularly, this study demonstrates the nonrandom positioning of metaphase chromosomes bearing nucleolar organizer regions as revealed by their positive upstream binding factor immunolabeling. During the complex morphogenesis of the progeny nuclei from anaphase to late telophase, the equal partitioning of the nucleolar organizer regions is demonstrated by quantification, and their typical nonrandom central positioning within the chromosome sets is revealed.