Chromatin Structure And Gene Regulation In Higher Plants

Spiker, Steven

doi:10.1016/s0065-2660(08)60040-1

Cited by 24 publications

(9 citation statements)

References 266 publications

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“…The Adhl gene undergoes a change in chromatin structure upon anaerobic induction, evidenced by an enhanced sensitivity to digestion by certain restriction endonucleases at sites upstream from the start of transcription (7). This observation is in agreement with the well-documented alterations in chromatin structure which occur in animal systems when genes undergo transcription or adopt a transcriptionally potent state (for reviews see 14,21,29,38). These changes are often manifested as an increased sensitivity to nucleases (30,34), a hypersensitivity to DNAase I digestion at specific sites that are usually upstream from the start of transcription (15,35,36), or a change in the arrangement of nucleosomes relative to the DNA sequence (17,26,37).…”

Section: Introductionsupporting

confidence: 77%

Insertion of the Mu1 transposable element into the first intron of maize Adh1 interferes with transcript elongation but does not disrupt chromatin structure

Vayda

Freeling

1986

Plant Mol Biol

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The presence of the Mu1 transposable element within the first intervening sequence of the maize Adh1 gene interfered with transcription through that gene. Insertion of the element did not have an apparent effect on transcription initiation or chromatin structure. In nuclei isolated from anaerobically induced roots, in which Adh1 is transcriptionally active, a subset of the Adh1 chromatin is arranged in a unique conformation characterized by a generalized sensitivity to nucleases, specific DNAase I sensitive sites and a nucleosome array distinct from the inactive configuration present in leaf nuclei. The chromatin organization of the Mu1-induced mutant alleles is indistinguishable from that of the progenitor Adh1-S allele and a point mutant allele that is null for ADH1 activity. The initiation of transcription also proved to be unaffected in these mutants. Nuclear runoff experiments indicated that Adh1 sequences upstream from the point of Mu1 insertion were transcribed normally, but sequences downstream to the insertion were drastically reduced relative to a reference gene expressed in anaerobic root nuclei. Thus, it was concluded that the defect in these Mu1-induced mutants does not reside at the level of gene accessibility or transcript initiation. Rather, Mu1 presents an impediment to the progress of the polymerase II complex during transcript elongation.

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Section: Introductionsupporting

confidence: 77%

Insertion of the Mu1 transposable element into the first intron of maize Adh1 interferes with transcript elongation but does not disrupt chromatin structure

Vayda

Freeling

1986

Plant Mol Biol

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“…Foreign DNA stably integrated in the nuclei of plants cells has been found to display normal chromatin structure (e.g. [11,59]), and to respond to changes in DNA methylation [ 1, 26, 48, and unpublished data from our lab]. Thus, the eventual state, both biochemical and functional, of the inserted transgene must result from interactions between the initially 'naked' foreign DNA and host (and donor?)…”

Section: Resolution Of the Molecular Factors Producing Transgene Exprmentioning

confidence: 99%

Transgene expression variability (position effect) of CAT and GUS reporter genes driven by linked divergent T-DNA promoters

1991

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Forty-five individually transformed clonal tobacco callus lines were simultaneously assayed for both chloramphenicol acetyltransferase (CAT) and beta-glucuronidase (GUS) activity resulting from expression of introduced reporter genes driven by the adjacent and divergent mannopine (mas) promoters. Excluding lines in which one or both of the enzyme activities was essentially zero, the activities of the reporter genes varied by as much as a factor of 136 (CAT) and 175 (GUS) between individual transformants. Superimposed upon the high degree of inter-clonal expression variability was an intra-clonal variability of 3-4-fold. The observed degree of intra-clonal reporter gene activity may be more extreme because of the regulatory characteristics of the mannopine promoters, but must still be addressed when considering the limitations of reporter gene-based analysis of transgene function and structure. There was no consistent correlation between the expression levels of the introduced CAT and GUS genes since the ratio of GUS to CAT activities (nmol min-1 mg-1) within individual lines varied from 0.05 to 49. Even divergent transcription from two directly adjacent promoter regions (both contained within a 479 bp TR-DNA fragment) is insufficient to guarantee concurrent expression of two linked transgenes. Our quantitative data were compared to published data of transgene expression variability to examine the overall distribution of expression levels in individual transformants. The resulting frequency distribution indicates that most transformants express introduced transgenes at relatively low levels, suggesting that a potentially large number of Agrobacterium-mediated transformation events may result in silent transgenes.

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“…These range from a less compact nucleosome structure with nuclease hypersensitive sites, as in the case of induced heat shock genes of Drosophila (30,34), to apparently nucleosome-free stretches of DNA when transcriptional activity is very high, as for example the ribosomal genes of the mouse P815 cell line (7). In addition, active or potentially active sequences in chromatin exhibit an enhanced sensitivity to digestion with a variety of nucleases (10,20,27,28). Integration of 'foreign' DNA, such as viral DNA, can alter the native chromatin structure of the host genome near the site of integration (4,25).…”

Section: Introductionmentioning

confidence: 99%

Chromatin structure of integrated T-DNA in crown gall tumors

1987

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We have investigated the chromatin structure of the integrated T-DNA in two N. tabacum crown gall tumor lines, and compared the results to those obtained in a previous study of the methylation patterns of these same integrated DNA sequences (Gelvin et al., Nucleic Acids Res. 11:159-174, 1983). The E9 octopine-type tumor contains a single copy of TL, whose transcription is essential for tumor maintenance, and 15-30 copies of TR, a non-essential region. The HT37#15 nopaline type teratoma contains a single copy of the nopaline T-DNA. All these integrated sequences can be found associated with nucleosomes, although the diffuse nature of the nucleosome bands on Southern transfers implies an 'open' chromatin conformation. In addition, all the sequences are more sensitive to digestion with deoxyribonuclease I than the bulk of the chromatin. We present evidence suggesting that, despite the previously published data that the majority of copies of the TR-DNA are highly methylated at the sequence CCGG whereas the TL-DNA is not, the majority of copies of the TR-DNA in the E9 tumor line are in the same chromatin conformation as TL. These data therefore suggest that most of the copies of TR-DNA are likely to be transcriptionally competent.

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Chromatin Structure And Gene Regulation In Higher Plants

Cited by 24 publications

References 266 publications

Insertion of the Mu1 transposable element into the first intron of maize Adh1 interferes with transcript elongation but does not disrupt chromatin structure

Insertion of the Mu1 transposable element into the first intron of maize Adh1 interferes with transcript elongation but does not disrupt chromatin structure

Transgene expression variability (position effect) of CAT and GUS reporter genes driven by linked divergent T-DNA promoters

Chromatin structure of integrated T-DNA in crown gall tumors

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