Linked Life Data

1191189

Source:http://linkedlifedata.com/resource/pubmed/id/1191189

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1976-1-26
pubmed:abstractText
The molecular weight of native DNA has been accurately determined by the use of a semiautomated sucrose gradient system. A mondisperse size distribution (speed dependence free) of eighth-of-a-chromatid pieces [1.7 S 10(10) daltons, with 95% confidence (fiducial) limits of +/- 48%] was found. This size has been confirmed by viscoelastometry. Ionizing radiation rapidly breaks each of these pieces into about 21 subunits (again monodisperse) of 8 X 10(8) daltons each. With increaseing dose (greater than 2 krad) the subunits are themselves randomly broken down into even smaller pieces. Postirradiation incubation at 37 degrees C permits the cells to repair both DNA double-strand breaks and intersubunit linkages at the same dose-independent rate (T37) of about 55 min, the same rate as found in Micrococcus radiodurans. The repair data are compatible with a first-order-kinetics repair system, analogous to the post-UV excision-repair system, which becomes saturated at high doses (greater than 60 krad). Specially constructed "enzyme" gradients show that the linkages contain at least two protein molecules each covalently bound to the end of a subunit and linking the subunits together by a disulfide bond(s). Correlation of cell survival and DNA break kinetics yields two possible models. These are that the two-thirds of the lethal events which are due to improperly or unrepaired double-strand breaks result from either (1) a misrepair frequency of 3.5 X 10(-3) (rather high for a mutation frequency) or (2) the induction of a double-strand break in a single eighth-of-a-chromatid unit which is essential for survival but which cannot be repaired, possibly because the unit contains the double-strand break repair system gene(s).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0090-5542
pubmed:author
pubmed:issnType
Print
pubmed:volume
5B
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
677-83
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
1975
pubmed:articleTitle
The repair of DNA double-strand breaks in mammalian cells and the organization of the DNA in their chromosomes.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.