Localization of chromosome breakpoints induced by DNase I in Chinese hamster ovary (CHO) cells.
DNase I was electroporated into S-phase CHO cells and induced chromosome breakpoints were localized in G-banded metaphases. More than 75% of breakpoints mapped to Giemsa-light bands, 18% to Giemsa-dark bands and about 7% to band junctions. Chromosome breakpoint clusters produced by DNase I colocalized with chromosome breakpoints induced by the restriction endonucleases AluI and BamHI in the G1- and S-phases of the cell cycle in CHO cells. Digestion of metaphase spreads with AluI, BamHI and DNase I produced G-bands, indicating that G-light bands are more sensitive to endonuclease action. The possible role of nuclease-sensitive sites in active chromatin as selective targets for the induction of chromosome breakpoints by these endonucleases is discussed.
Folle
G A
GA
División de Citogenética Humana y Microscopía Cuantitativa, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, C.P. 11600, Montevideo, Uruguay. folle@iibce.edu.uy
Boccardo
E
E
Obe
G
G
D000818:Animals; D016466:CHO Cells; D002871:Chromosome Banding; D019457:Chromosome Breakage; D002875:Chromosomes / Q000378:metabolism; D006224:Cricetinae; D015245:Deoxyribonuclease BamHI / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D018274:Electroporation; D016196:S Phase / Q000235:genetics
D015245:Deoxyribonuclease BamHI; C024669:endodeoxyribonuclease AluI; D003850:Deoxyribonuclease I; D015252:Deoxyribonucleases, Type II Site-Specific