Metaphase chromosome and nucleoid differences between CHO-K1 and its radiosensitive derivative xrs-5
- Argonne National Lab., IL (United States)
- Chicago Univ. Medical Center, Chicago, IL (United States). Dept. of Radiation and Cellular Oncology
- Chicago Univ. Medical Center, Chicago, IL (United States). Dept. of Surgical Pathology
- Veterans Administration Hospital, Hines, IL (United States). Dept. of Radiotherapy
The Chinese hamster ovary (CHO) cell line xrs-5 is a radiation-sensitive mutant isolated from CHO-K1 cells. The radiation sensitivity is associated with a defect in DNA double-strand break rejoining. Chromatin structure also appears altered in xrs-5 cells compared to the parental CHO-K1 cells. Metaphase chromosomes from xrs-5 are more condensed in appearance than CHO-K1 chromosomes. The overcondensed look is not the result of colcemid sensitivity. Electron microscopy studies suggest that xrs-5 metaphase chromosomes have larger loops of chromatin extending out from the chromosome core. There are also differences between CHO-K1 and xrs-5 cells in the size and fluorescence pattern of ethidium bromide-stained nucleoid preparations. These results suggest that there is a fundamental difference between CHO-K1 and xrs-5 in either the organization of the supercoiled loops of DNA attached to the nuclear matrix or in the nature of the proteins that attach the DNA to the matrix. These alterations in chromosome structure may underlie, in part, the radiation sensitivity of xrs-5 cells.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38; FG02-86ER60408
- OSTI ID:
- 10149006
- Report Number(s):
- ANL/BIM/PP-73350; ON: DE94011494; BR: HA0201010/HA0202020
- Resource Relation:
- Other Information: PBD: May 1992
- Country of Publication:
- United States
- Language:
- English
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