Linked Life Data

2620827

Source:http://linkedlifedata.com/resource/pubmed/id/2620827

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12A
pubmed:dateCreated
1990-3-27
pubmed:abstractText
We used fluorescence in situ hybridization to examine the products of early DNA sequence amplification events in CHO cells. Nine independent populations of cells were selected for resistance to 0.4 microM methotrexate (MTX), and mitotic chromosome spreads were hybridized to a mixture of cloned cosmids representing approximately 273 kb of contiguous DNA sequence from the dihydrofolate reductase (DHFR) locus. Of the nine populations, eight contain cells that have amplified the DHFR domain. Cells in the remaining population displayed only the two single-copy loci on chromosomes 2 and Z2. Of the eight amplificants, one carries amplified DHFR genes on chromosome 2, six on chromosome Z2, and one on an unidentified chromosome. Some cultures carry additional amplified genes on other chromosomes, probably resulting from bridge/breakage/fusion cycles or translocations. In six of the eight amplificants, both single-copy parental loci are detected at their original positions, and amplicon clusters are situated at least 50 megabases (Mb) away on the same chromosome arm, often at the termini. Amplification occurred at or close to the original site of the DHFR gene in only one population. Our results are not consistent with models in which initial amplification events occur by over-replication of the parental locus followed by recombination in loco. Because amplified DHFR sequences occur most often on the same chromosome arm as the parental DHFR gene but at a considerable distance from it, our results are most compatible with either sister chromatid exchange between widely separated sites or with a form of conservative intrachromosomal duplication analogous to transposition in bacteria.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0890-9369
pubmed:author
pubmed:issnType
Print
pubmed:volume
3
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1913-25
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Early dihydrofolate reductase gene amplification events in CHO cells usually occur on the same chromosome arm as the original locus.
pubmed:affiliation
Biomedical Sciences Division, Lawrence Livermore National Laboratory, California 94550.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't