Abstract:
:Exposure of Chinese hamster cells to reduced oxygen partial pressure results in a marked enhancement in the frequency of methotrexate resistance and dihydrofolate reductase gene amplification. The frequency of enhanced resistance is a function of the length of exposure to hypoxic conditions and the time after recovery from hypoxia when cells are plated into methotrexate-containing medium. Hypoxia results in an inhibition of DNA synthesis; upon return to normal oxygen atmosphere, greater than 60% of cells in S phase at the time hypoxia was started subsequently undergo overreplication of DNA within a single cell cycle. The cells with the increased frequency of gene amplification are derived from this subset of overreplicated cells. These results are discussed within the context of the hypoxic state of many solid tumors and the high frequency of aneuploidy, chromosomal aberrations, and spontaneously occurring resistances to a number of cancer chemotherapeutic agents.
journal_name
Proc Natl Acad Sci U S Aauthors
Rice GC,Hoy C,Schimke RTdoi
10.1073/pnas.83.16.5978subject
Has Abstractpub_date
1986-08-01 00:00:00pages
5978-82issue
16eissn
0027-8424issn
1091-6490journal_volume
83pub_type
杂志文章abstract::In this study we examine how the introduction of a reference lottery with nonrandom outcomes alters the way in which choices among pairs of lotteries are made, even if it does not alter the choices. We use different domains (some of the lotteries produce gains, other losses) and different contexts (one member of the p...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0530279100
更新日期:2003-03-18 00:00:00
abstract::The improvement of motor behavior, based on experience, is a form of learning that is critically dependent on the cerebellum. A well studied example of cerebellar motor learning is short-term saccadic adaptation (STSA). In STSA, information on saccadic errors is used to improve future saccades. The information optimiz...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0706032105
更新日期:2008-05-20 00:00:00
abstract::During reverse transcription of retroviral RNA, synthesis of (-) strand DNA is primed by a cellular tRNA that anneals to an 18-nt primer binding site within the 5' long terminal repeat. For (+) strand synthesis using a (-) strand DNA template linked to the tRNA primer, only the first 18 nt of tRNA are replicated to re...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.14.7210
更新日期:1997-07-08 00:00:00
abstract::Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades link...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1812092116
更新日期:2019-03-12 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1508920113
更新日期:2016-02-23 00:00:00
abstract::Selective blockade of gene expression by designed small molecules is a fundamental challenge at the interface of chemistry, biology, and medicine. Transcription factors have been among the most elusive targets in genetics and drug discovery, but the fields of chemical biology and genetics have evolved to a point where...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1312473110
更新日期:2013-09-24 00:00:00
abstract::Habitat loss and disease are main drivers of global amphibian declines, yet the interaction between them remains largely unexplored. Here we show that paradoxically, habitat loss is negatively associated with occurrence, prevalence, and infection intensity of the chytrid fungus Batrachochytrium dendrobatidis (Bd) in a...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1014497108
更新日期:2011-06-14 00:00:00
abstract::Chloroplasts have evolved from a cyanobacterial endosymbiont and been retained for more than 1 billion years by coordinated chloroplast division in multiplying eukaryotic cells. Chloroplast division is performed by ring structures at the division site, encompassing both the inside and the outside of the two envelopes....
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0802412105
更新日期:2008-09-30 00:00:00
abstract::Some patients with a lesion to the primary visual cortex (V1) show "blindsight": the remarkable ability to guess correctly about attributes of stimuli presented to the blind hemifield. Here, we show that blindsight can be induced in normal observers by using transcranial magnetic stimulation of the occipital cortex bu...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0500834102
更新日期:2005-07-26 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1807067115
更新日期:2018-11-06 00:00:00
abstract::Single-stranded DNA oligonucleotides can achieve targeted base-pair substitution with modest efficiency but high precision. We show that "oligo targeting" can be used effectively to study missense mutations in DNA mismatch repair (MMR) genes. Inherited inactivating mutations in DNA MMR genes are causative for the canc...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1520813113
更新日期:2016-04-12 00:00:00
abstract::U2 snRNP auxiliary factor 65 kDa (U2AF(65)) is a general splicing factor that contacts polypyrimidine (Py) tract and promotes prespliceosome assembly. In this report, we show that U2AF(65) stimulates alternative exon skipping in spinal muscular atrophy (SMA)-related survival motor neuron (SMN) pre-mRNA. A stronger 5' ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1500639112
更新日期:2015-08-11 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1418733111
更新日期:2014-12-02 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1424435112
更新日期:2015-04-21 00:00:00
abstract::The polypeptide precursor pr76 to the internal viral group specific (gs) antigen proteins of Rous sarcoma virus, synthesized in a cell-free system of ascites cells, has been processed in vitro into the viral proteins by purified viral protein p15 as well as by disrupted Rous sarcoma virus. Disrupted Rauscher murine le...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.74.3.911
更新日期:1977-03-01 00:00:00
abstract::The SKW-3 cell line, which was established from the malignant cells of a patient with T-cell chronic lymphocytic leukemia, is characterized by a translocation involving chromosome 8 (band q24) and chromosome 14 (band q11) [t(8;14)(q24;q11)]. To determine the position of the gene encoding the alpha chain of the T-cell ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.10.3439
更新日期:1986-05-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.6.2242
更新日期:1992-03-15 00:00:00
abstract::Yawn contagion in humans has been proposed to be related to our capacity for empathy. It is presently unclear whether this capacity is uniquely human or shared with other primates, especially monkeys. Here, we show that in gelada baboons (Theropithecus gelada) yawning is contagious between individuals, especially thos...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0910891106
更新日期:2009-11-17 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2002-01-22 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0506160102
更新日期:2005-09-13 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1300127110
更新日期:2013-02-19 00:00:00
abstract::It is well accepted that the induction of endothelial cell (EC) adhesion molecules is a critical component in acute inflammatory responses as well as allogeneic interactions in vascularized allografts and, possibly, atherogenesis. The "inflammatory triad" of interleukin 1 (IL-1), tumor necrosis factor, and lipopolysac...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.9.3994
更新日期:1994-04-26 00:00:00
abstract::The grand partition function for a long linear system of alternating alpha and beta sequences with the restraint of a fixed number, N(alphabeta), of alphabeta boundaries depends in an extremely simple way on the alpha-sequence and beta-sequence grand partition functions, xi(alpha) and xi(beta). When the restraint is r...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.69.5.1165
更新日期:1972-05-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.252763799
更新日期:2003-02-18 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1503653112
更新日期:2015-07-28 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.64.1.381
更新日期:1969-09-01 00:00:00
abstract::The rationale for genome-wide association study (GWAS) results is sequence variation in cis-regulatory elements (CREs) modulating a target gene's expression as the major cause of trait variation. To understand the complete molecular landscape of one of these GWAS loci, we performed in vitro reporter screens in cardiom...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1808734116
更新日期:2019-05-28 00:00:00
abstract::In the presence of the S polypeptide, maize chloroplast DNA-dependent RNA polymerase preferentially transcribes sequences within the 2200-nucleotide-pair-long maize chloroplast chromosome fragment Eco [unk] from a supercoiled chimeric plasmid cloned in Escherichia coli [Jolly, S. O. & Bogorad, L. (1980) Proc. Natl. Ac...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.78.6.3423
更新日期:1981-06-01 00:00:00