Individual chromosomes are occupied as “chromosome territories (CTs)” within the nucleus. How are CTs spatially localized? What kind of factors can be involved to arrange their positioning? From studies for over two decades it has been revealed that the radial distribution of CTs from center to nuclear rim has the following characteristics. 1) It depends on the physical size and gene density of each CT; larger gene-poor CTs are located toward periphery and smaller gene-dense CTs are located into interior of the nucleus. 2) Evolutionarily syntenic chromosomal regions of CTs are inclined to localize the same radial positioning, but it is influenced by the pericentromeric heterochromatin. 3) Lamin asssociated domains (LADs) might be affected to be tethered near the nuclear rim. 4) Actin related protein 6 (Arp6), one of the ubiquitous components of chromatin remodeling complexes, has affected to global nuclear radial distribution of CTs. Arp6-knock out chicken DT40 cells have shown disturbed global nuclear architecture. In summary, spatial radial distribution of CTs can be affected strongly with physical properties whereas less affected with the status of gene expression or epigenetic factors. In the present study I focused on the gibbons showing the highest speed of chromosome evolution in mammals. Approximately over 90 evolutionary conserved breakpoints (ECBs) have been observed between human and gibbons. To investigate spatial organization in human and gibbons, radial 3D arrangements were analyzed by 3D-FISH with CTs, ECBs, and repetitive DNA sequences. The results showed Alu and LINE1 sequences were located near the nuclear center and periphery, respectively, however, centromeric satellite DNAs were detected as relatively stronger fluorescent signals near the center than those of periphery suggesting that radial 3D arrangements have reflected the different distributed number of repetitive elements between periphery and interior nuclear space. Organization of nuclear architecture from evolutionary views will be discussed.
Individual chromosomes are occupied as “chromosome territories (CTs)” within the nucleus. How are CTs spatially localized? What kind of factors can be involved to arrange their positioning? From studies for over two decades it has been revealed that the radial distribution of CTs from center to nuclear rim has the following characteristics. 1) It depends on the physical size and gene density of each CT; larger gene-poor CTs are located toward periphery and smaller gene-dense CTs are located into interior of the nucleus. 2) Evolutionarily syntenic chromosomal regions of CTs are inclined to localize the same radial positioning, but it is influenced by the pericentromeric heterochromatin. 3) Lamin asssociated domains (LADs) might be affected to be tethered near the nuclear rim. 4) Actin related protein 6 (Arp6), one of the ubiquitous components of chromatin remodeling complexes, has affected to global nuclear radial distribution of CTs. Arp6-knock out chicken DT40 cells have shown disturbed global nuclear architecture. In summary, spatial radial distribution of CTs can be affected strongly with physical properties whereas less affected with the status of gene expression or epigenetic factors. In the present study I focused on the gibbons showing the highest speed of chromosome evolution in mammals. Approximately over 90 evolutionary conserved breakpoints (ECBs) have been observed between human and gibbons. To investigate spatial organization in human and gibbons, radial 3D arrangements were analyzed by 3D-FISH with CTs, ECBs, and repetitive DNA sequences. The results showed Alu and LINE1 sequences were located near the nuclear center and periphery, respectively, however, centromeric satellite DNAs were detected as relatively stronger fluorescent signals near the cen ...
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