Radial distribution of interphase chromosome territories in the human lymphocyte nucleus is highly correlated with
their gene densities.
The individual chromosomes in the interphase nucleus are discretely observed
and highly compartmentalized called gchromosome territoriesh that are visualized
by threedimensional florescence in situ hybridization (3D-FISH) technique
using the chromosome specific DNA painting probes. Recent studies indicated
that the radial position of a given gchromosome territoryh is highly correlated
with its gene density, its size and replication timing. For example, human
chromosomes 18 and 19 territories, which are almost same size (76.1 Mb
and 63.8 Mb, respectively), show a different position in the lymphoblastoid
cell nuclei; the gene-poor, late replicating chromosome 18 territory (4.2
genes/Mb) is preferentially located at the nuclear periphery, while the
gene-rich and early replicating chromosome 19 territory (23.0 genes/Mb)
is found in the nuclear center.
The lower figure showed a partial gallery images from a human lymphoblastoid
cell nucleus after 3D-FISH with chromosome 18 (red) and chromosome 19 (green)
paintprobes. Nuclear DNA counterstain is shown in blue (scale bar indicates 5µm). Light optical serial sections with the z-axial interval of 200nm were recorded by confocal microscopy (Zeiss LSM510meta) and used for 3D reconstruction and image analyses. This topology has been quantitatively evaluated by the specific program and demonstrated the evolutionary conservation from the primate species as well as chicken cells. The functional relevance of the radial positioning has been discussed in various aspects in relation to the higher order nuclear architecture (See Tanabe H., Muller S., Neusser M., von Hase J., Calcagno E., CremerM., Solovei., Cremer C., and Cremer T. 2002: Proc Natl Acad. Sci. USA, 99: 4424~4429).
(Hideyuki Tanabe, Department of Biosystems Science, Schooi of Advanced
Sciences, The Graduate University for Advanced Studies (Sokendai). Shonan
Village, Hayama, Kanagawa 240-0193, Japan)