The relationship between sister-chromatid exchange and perturbations in DNA replication in mutant EM9 and normal CHO cells

Repetitive DNA sequences have been implicated in the mediation of DNA rearrangement in mammalian cells. We have tested this hypothesis by using a dihydrofolate reductase (DHFR) expression vector into which candidate sequences were inserted. DHFR- Chinese hamster ovary (CHO) cells were transfected with this vector, the amplification of which was then selected for by methotrexate (MTX) exposure. Cells transfected with the vector alone (and resistant to 0.02 or 1.0 microM MTX) or with a poly(dG-dT) insert (and resistant to 0.05 or 1.0 microM MTX) showed little change in chromosome aberrations or sister chromatid exchange frequencies. In contrast, transfection of DHFR- CHO cells with a vector containing either of two distinct 0.34-kilobase human alphoid DNA segments (and selection to 0.05 to 10.0 microM MTX) showed an approximately 50% increase in chromosome number and marked changes in chromosome structure, including one or two dicentric or ring forms per cell. The sister chromatid exchange frequency also increased, to more than double the frequency of that in cells transfected without insert or those containing poly(dG-dT). In situ hybridization of one 0.34-kilobase insert in some cells suggested clustering of homologous sequences in structurally abnormal recipient CHO cell chromosomes. The approach described provides an introduction to a unique means for a coordinate molecular and cytological study of dynamic changes in chromosome structure.

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The Relationship between Dioxin Congeners in the Breast Milk of Vietnamese Women and Sister Chromatid Exchange

International Journal of Molecular Sciences ◽

10.3390/ijms15057485 ◽

2014 ◽

Vol 15 (5) ◽

pp. 7485-7499 ◽

Cited By ~ 3

Author(s):

Hiroyuki Suzuki ◽

Teruhiko Kido ◽

Rie Okamoto ◽

Dang Nhu ◽

Muneko Nishijo ◽

...

Keyword(s):

Breast Milk ◽

Sister Chromatid ◽

Sister Chromatid Exchange ◽

Vietnamese Women ◽

The Relationship

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Chromosome instability associated with human alphoid DNA transfected into the Chinese hamster genome

Molecular and Cellular Biology ◽

10.1128/mcb.8.9.3611-3618.1988 ◽

1988 ◽

Vol 8 (9) ◽

pp. 3611-3618

Author(s):

M W Heartlein ◽

J H Knoll ◽

S A Latt

Keyword(s):

Sister Chromatid ◽

Dna Sequences ◽

Cho Cells ◽

Sister Chromatid Exchange ◽

Mammalian Cells ◽

Chromosome Structure ◽

Chromosome Instability ◽

Chinese Hamster ◽

Alphoid Dna ◽

Sister Chromatid Exchange Frequency

Repetitive DNA sequences have been implicated in the mediation of DNA rearrangement in mammalian cells. We have tested this hypothesis by using a dihydrofolate reductase (DHFR) expression vector into which candidate sequences were inserted. DHFR- Chinese hamster ovary (CHO) cells were transfected with this vector, the amplification of which was then selected for by methotrexate (MTX) exposure. Cells transfected with the vector alone (and resistant to 0.02 or 1.0 microM MTX) or with a poly(dG-dT) insert (and resistant to 0.05 or 1.0 microM MTX) showed little change in chromosome aberrations or sister chromatid exchange frequencies. In contrast, transfection of DHFR- CHO cells with a vector containing either of two distinct 0.34-kilobase human alphoid DNA segments (and selection to 0.05 to 10.0 microM MTX) showed an approximately 50% increase in chromosome number and marked changes in chromosome structure, including one or two dicentric or ring forms per cell. The sister chromatid exchange frequency also increased, to more than double the frequency of that in cells transfected without insert or those containing poly(dG-dT). In situ hybridization of one 0.34-kilobase insert in some cells suggested clustering of homologous sequences in structurally abnormal recipient CHO cell chromosomes. The approach described provides an introduction to a unique means for a coordinate molecular and cytological study of dynamic changes in chromosome structure.

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