Cell Nucleus Biogenesis, Structure and Function
409
cH11148/RCN
HSA11p
(a)
(b)
(c)
(f)
(g)
(d)
(e)
Fig. 7
The structure of chromosome territories. (a–c) show a high-resolution FISH
analysis to demonstrate the organization of chromosome territories. In this
example (a), the chromosome painting probe was generated from the short arm only of
chromosome 11 (HSA11p) and indirectly labeled using a green fluorescent dye.
Hybridization was also performed using a much shorter cosmid probe, to the
ubiquitously expressed
RCN
gene from the WAGR locus of human chromosome 11,
labeled with a red fluorescent dye. The relative positions of the red and green
fluorescence are shown in the grayscale images in (b) and (c). Note that the expressed
region is located close to the center of the chromosome territory and is separate from
the dense chromatin regions, in this primary human ±broblast. The bars are 2
.
5
µ
m.
From Mahy, N.L., Perry, P.E., Gilchrist, S., Baldock, R.A., Bickmore, W.A. (2002) Spatial
organization of active and inactive genes and noncoding DNA within chromosome
territories,
J. Cell Biol.
157
, 579–589, with permission of Rockefeller University Press.
(d–e) show the DNA foci that were labeled in HeLa cells at the onset of S-phase for
20 min or 10 h using Bromo-deoxyuridine. The samples were prepared 3 days later,
when only 25 to 50% of the chromosome territories within nuclei are labeled. (The loss
of labeling is determined by random segregation of the labeled and unlabeled
chromatids.) Note that the DNA foci (d) are seen to cluster into discrete nuclear
zones – these are chromosome territories – and that this zonal organization is much
more distinct when the chromosome are labeled throughout S-phase (e). Though these
samples are ±xed prior to immunostaining the same observations can be made on
living cells after introducing a fluorescent DNA precursor such as FITC-dUTP.
(Reproduced from Jackson, D.A., Pombo, A. (1998) Replicon clusters are stable units of
chromosome structure: evidence that nuclear organization contributes to the ef±cient
activation and propagation of S-phase in human cells,
J. Cell Biol.
140, 1285–1295 with
permission of Rockefeller University Press. (f–g) show models for the proposed long
and short-range architecture of chromosome territories. See Cremer, T., Cremer, C.
(2001) Chromosome territories, nuclear architecture and gene regulation in mammalian
cells,
Nat. Rev. Genet.
2
, 292–301 for details. Image courtesy of Gregar Kreth and
published with permission of Palgrave-Macmillan Publishing.) (See color plate p. xxx).
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