scholarly journals 341. Exogenous Plasmid DNA Sequences Differentially Affect Episomal Transgene Silencing in Liver and Muscle

2007 ◽  
Vol 15 ◽  
pp. S129
Keyword(s):  
Dna Sequences ◽  
Plasmid Dna ◽  
Transgene Silencing ◽  
Exogenous Plasmid

Introduction of exogenous DNA into Chlamydomonas reinhardtii by electroporation

1991 ◽  
Vol 11 (4) ◽  
pp. 2328-2332
Author(s):  
L E Brown ◽  
S L Sprecher ◽  
L R Keller
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Plasmid Dna ◽  
Cell Walls ◽  
Intact Cell ◽  
Exogenous Dna ◽  
Electrical Pulses ◽  
Exogenous Plasmid

The fate of exogenous DNA introduced into Chlamydomonas reinhardtii by electroporation was analyzed. With single and double electrical pulses, plasmids as large as 14 kb were introduced into cells with and without intact cell walls. Within hours after introduction, exogenous plasmid DNA was associated with nuclei isolated from cells; several weeks after introduction, exogenous DNA was stably integrated into the Chlamydomonas genome. These studies establish electroporation as a method for introducing DNA, and potentially other molecules, into C. reinhardtii.

scholarly journals Genetic Diversity of Xanthomonas campestris pv. vitians, the Causal Agent of Bacterial Leafspot of Lettuce

2003 ◽  
Vol 93 (5) ◽  
pp. 596-603 ◽  
Author(s):  
Jeri D. Barak ◽  
Robert L. Gilbertson
Keyword(s):  
Genetic Diversity ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Plasmid Dna ◽  
Xanthomonas Campestris ◽  
Rflp Analysis ◽  
Dna Probe ◽  
Internal Transcribed Spacer Region ◽  
Geographical Regions

Bacterial leafspot of lettuce (BLS), caused by Xanthomonas campes-tris pv. vitians, has become more prevalent in many lettuce-growing areas of the world over the past decade. To gain insight into the nature of these outbreaks, the genetic variation in X. campestris pv. vitians strains from different geographical locations was examined. All strains were first tested for pathogenicity on lettuce plants, and then genetic diversity was assessed using (i) gas-chromatographic analysis of bacterial fatty acids, (ii) polymerase chain reaction analysis of repetitive DNA sequences (rep-PCR), (iii) DNA sequence analysis of the internal transcribed spacer region 1 (ITS1) of the ribosomal RNA, (iv) restriction fragment length polymorphism (RFLP) analysis of total genomic DNA with a repetitive DNA probe, and (v) detection and partial characterization of plasmid DNA. Fatty acid analysis identified all pathogenic strains as X. campestris, but did not consistently identify all the strains as X. campestris pv. vitians. The rep-PCR fingerprints and ITS1 sequences of all pathogenic X. campestris pv. vitians strains examined were identical, and distinct from those of the other X. campestris pathovars. Thus, these characteristics did not reveal genetic diversity among X. campestris pv. vitians strains, but did allow for differentiation of X. campestris pathovars. Genetic diversity among X. campestris pv. vitians strains was revealed by RFLP analysis with a repetitive DNA probe and by characterization of plasmid DNA. This diversity was greatest among strains from different geographical regions, although diversity among strains from the same location also was detected. The results of this study suggest that these X. campestris pv. vitians strains are not clonal, but comprise a relatively homogeneous group.

scholarly journals Asbestos fibers mediate transformation of monkey cells by exogenous plasmid DNA.

1988 ◽  
Vol 85 (20) ◽  
pp. 7670-7674 ◽  
Author(s):  
J. D. Appel ◽  
T. M. Fasy ◽  
D. S. Kohtz ◽  
J. D. Kohtz ◽  
E. M. Johnson
Keyword(s):  
Plasmid Dna ◽  
Asbestos Fibers ◽  
Exogenous Plasmid

scholarly journals DNA interstrand cross-links promote chromosomal integration of a selected gene in human cells.

1989 ◽  
Vol 9 (7) ◽  
pp. 2897-2905 ◽  
Author(s):  
J M Vos ◽  
P C Hanawalt
Keyword(s):  
Dna Sequences ◽  
Plasmid Dna ◽  
Simian Virus 40 ◽  
Transcription Unit ◽  
Dna Lesions ◽  
Cross Linking ◽  
Chromosomal Integration ◽  
Nonhomologous Recombination ◽  
Interstrand Cross Links ◽  
Cross Links

We have used integrative pSV2 plasmids to learn how DNA lesions affect nonhomologous recombination with human chromosomes. Enhanced stable transformation of fibrosarcoma cells with a selectable gene was observed after chemical modification of the plasmid DNA; thus, cells transfected with plasmid pSV2-gpt carrying photoadducts of the cross-linking agent 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT) yielded four- to sevenfold-higher levels of Gpt+ transformants than were obtained with untreated plasmid. The enhancement due to HMT interstrand cross-links was at least as great as that due to the monoadducts. DNA hybridization analysis indicated that the enhanced transformation frequency resulted from an increased number of cells carrying integrated plasmid sequences rather than from a higher copy number per transformant. The enhancement was not seen with a plasmid missing the sequences flanking the minimal simian virus 40 gpt transcription unit. Cotransfection with untreated and HMT-treated plasmids suggested that the HMT-containing DNA interacted preferentially with some cellular factor that promoted chromosomal integration of the plasmid DNA. It is concluded that (i) interstrand cross-linking as well as intrastrand DNA adducts promote nonhomologous recombination in human chromatin and (ii) DNA sequences flanking the selectable genes are the targets for such recombinational events.

scholarly journals Nonreciprocal exchanges of information between DNA duplexes coinjected into mammalian cell nuclei.

1985 ◽  
Vol 5 (1) ◽  
pp. 59-69 ◽  
Author(s):  
K R Folger ◽  
K Thomas ◽  
M R Capecchi
Keyword(s):  
Homologous Recombination ◽  
Dna Sequences ◽  
Plasmid Dna ◽  
Mammalian Cells ◽  
Recombinant Dna ◽  
Dna Duplexes ◽  
Dna Molecules ◽  
Cell Nuclei ◽  
High Concentration ◽  
Length Polymorphisms

We have examined the mechanism of homologous recombination between plasmid molecules coinjected into cultured mammalian cells. Cell lines containing recombinant DNA molecules were obtained by selecting for the reconstruction of a functional Neor gene from two plasmids that bear different amber mutations in the Neor gene. In addition, these plasmids contain restriction-length polymorphisms within and near the Neor gene. These polymorphisms did not confer a selectable phenotype but were used to identify and categorize selected and nonselected recombinant DNA molecules. The striking conclusion from this analysis is that the predominant mechanism for the exchange of information between coinjected plasmid molecules over short distances (i.e., less than 1 kilobase) proceeds via nonreciprocal homologous recombination. The frequency of homologous recombination between coinjected plasmid molecules in cultured mammalian cells is extremely high, approaching unity. We demonstrate that this high frequency requires neither a high input of plasmid molecules per cell nor a localized high concentration of plasmid DNA within the nucleus. Thus, it appears that plasmid molecules, once introduced into the nucleus, have no difficulty seeking each other out and participating in homologous recombination even in the presence of a vast excess of host DNA sequences. Finally, we show that most of the homologous recombination events occur within a 1-h interval after the introduction of plasmid DNA into the cell nucleus.

The distribution of homologous enterococcal plasmid DNA sequences in human faecal isolates

1992 ◽  
Vol 73 (2) ◽  
pp. 131-135 ◽  
Author(s):  
T. Watanabe ◽  
H. Kumata ◽  
M. Sasamoto ◽  
M. Shimizu-Kadota
Keyword(s):  
Dna Sequences ◽  
Plasmid Dna
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