Spatial organization of large-scale chromatin domains in the nucleus: a magnified view of single chromosome territories.
We have analyzed the spatial organization of large scale chromatin domains in chinese hamster fibroblast, human lymphoid (IM-9), and marsupial kidney epithelial (PtK) cells by labeling DNA at defined stages of S phase via pulsed incorporation of halogenated deoxynucleosides. Most, if not all, chromosomes contribute multiple chromatin domains to both peripheral and internal nucleoplasmic compartments. The peripheral compartment contains predominantly late replicating G/Q bands, whereas early replicating R bands preferentially localize to the internal nucleoplasmic compartment. During mitosis, the labeled chromatin domains that were separated in interphase form a pattern of intercalated bands along the length of each metaphase chromosome. The transition from a banded (mitotic) to a compartmentalized (interphasic) organization of chromatin domains occurs during the late telophase/early G1 stage and is independent of transcriptional activation of the genome. Interestingly, generation of micronuclei with a few chromosomes showed that the spatial separation of early and late replicating chromatin compartments is recapitulated independently of chromosome number, even in micronuclei containing only a single chromosome. Our data strongly support the notion that the compartmentalization of large-scale (band size) chromatin domains seen in the intact nucleus is a magnified image of a similar compartmentalization occurring in individual chromosome territories.
Ferreira
J
J
Institute of Histology, Faculty of Medicine, 1699 Lisboa codex, Portugal.
Paolella
G
G
Ramos
C
C
Lamond
A I
AI
D000818:Animals; D002451:Cell Compartmentation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000648:ultrastructure; D002871:Chromosome Banding; D002875:Chromosomes / Q000737:chemistry / Q000648:ultrastructure*; D002877:Chromosomes, Human / Q000737:chemistry / Q000648:ultrastructure*; D006224:Cricetinae; D004247:DNA / Q000032:analysis*; D004261:DNA Replication; D006801:Humans; D007399:Interphase; D008394:Marsupialia
D002843:Chromatin; D004247:DNA