Chromatid-type aberrations induced by AluI in Chinese hamster ovary cells

Intrachromosomal localization of breakpoints induced by the restriction endonucleases AluI and BamHI in Chinese hamster ovary cells treated in S phase of the cell cycle

The restriction endonucleases (REs) AluI and BamHI were electroporated into Chinese hamster ovary (CHO) cells during S phase of the cell cycle and breakpoints in G-banded metaphases were mapped to Giemsa-light or -dark bands or to band junctions. The majority of AluI- and BamHI-induced breakpoints were located in Giemsa-light bands. Both REs induced similar distributions of breakpoint clusters. The localization pattern of S phase-induced breakpoints in CHO cells is similar to the pattern of G1-induced breakpoints reported earlier. These data show that breakpoint localization for both REs is independent of the cell cycle stage (G1 or S) in which aberrations are induced and give further support to the hypothesis that nuclease hypersensitive regions (NHRs) associated with active genes play an important role in the distribution of breakpoints.

Exposure of CHO cells to AluI: comparison of chromosomal aberrations and cell survival

Chinese hamster ovary (CHO) cells were exposed to various doses of the restriction endonuclease AluI in the presence of 2.2 M glycerol. Some of the cells were cultured for analysis of chromosomal aberrations and some for analysis of colony-forming ability. Cell killing is mainly mediated by chromosomal aberrations.