title: Nuclear scaffold organization in the X-ray sensitive Chinese hamster mutant cell line, xrs-5.
abstract: Nuclear organization was probed in the radiation-sensitive Chinese hamster ovary CHO) cell line, xrs-5, and compared with parental CHO K1 cells using the resinless section technique and DNase I digestions. The resinless section data showed no gross morphological differences in core filaments from the nuclear scaffolds of unirradiated CHO K1 and xrs-5 cells. However, the nuclear scaffolds of irradiated xrs-5 cells (1 Gy) had significantly increased ground substance. Irradiated and unirradiated CHO K1 cell nuclear scaffolds were morphologically identical. These data suggest that both CHO K1 and xrs-5 cell nuclear scaffolds had internal nuclear scaffolding networks that could provide DNA attachment sites. The rate of DNase I digestion of unirradiated CHO K1 and xrs-5 was not significantly different, but the extent of digestion was greater in unirradiated CHO K1 cells that in xrs-5 cells suggesting that less xrs-5 cell chromatin at DNA attachment points is accessible to the enzyme DNase I. The extents of digestion in irradiated (1 Gy) CHO K1 and xrs-5 cell nuclei also differed but the relationship was reversed. The irradiated xrs-5 cell samples were digested to a greater extent compared with CHO K1 cells. These chromatin digestion data suggest that the matrix attachment regions in xrs-5 cells are different from CHO K1 cells. The different DNA attachment organization in the xrs-5 cells may play a role in modulating radiation sensitivity.
authors.affiliation: Northern Illinois University, Department of Biological Sciences, DeKalb 60115.
authors.forename: L S
authors.initials: LS
authors.lastname: Yasui
authors.forename: T J
authors.initials: TJ
authors.lastname: Fink
authors.forename: A M
authors.initials: AM
authors.lastname: Enrique
mesh_terms: D000818:Animals; D016466:CHO Cells / Q000528:radiation effects*; D002467:Cell Nucleus / Q000648:ultrastructure*; D002843:Chromatin / Q000528:radiation effects; D006224:Cricetinae; D003850:Deoxyribonuclease I / Q000494:pharmacology; D009154:Mutation; D014965:X-Rays
chemical_list: D002843:Chromatin; D003850:Deoxyribonuclease I