Ribosomal DNA methylation in a flax genotroph and a crown gall tumour

Blundy, Keith S.; Cullis, Christopher A.; Hepburn, Angus G.

doi:10.1007/bf00015030

Cited by 24 publications

(12 citation statements)

References 21 publications

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“…The rDNA was highly resistant to Hpa II cleavage but was cleaved extensively by Msp I. Similar fractionation of rDNA by methylationsensitive restriction enzymes has been reported for several plant species [8,10,13,15,25,36,40,41 ]. Using the published sequences from the IGS of BMS [23] (or A619 [39]), the 18S gene of maize line W22 [21] and the 26S gene office [37] to provide a sequence of an entire repeat unit indicates that, on average, there would be approximately 70 CCGG sites per repeat unit present in maize and teosinte.…”

Section: Discussionmentioning

confidence: 56%

“…This conclusion is further supported by the evolutionary conservation of this region of undermethylation. Studies of numerous other plant rDNAs have identified the primary site of undermethylation at approximately 0.7-1.0kb upstream of the start of the 18S coding region [8,13,14,15,40,41]. Conservation of this general location of undermethylation also has been observed in Xenopus rDNA [6].…”

Section: Discussionmentioning

confidence: 86%

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Unmethylated regions in the intergenic spacer of maize and teosinte ribosomal RNA genes

Jupe

Zimmer

1990

Plant Mol Biol

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The restriction endonucleases Hpa II and Msp I were used to examine cytosine methylation in the ribosomal RNA genes (rDNA) of inbred lines of maize and species of teosinte. In all of the rDNAs examined, Msp I (not sensitive to mCpG) digestion yielded a distribution of lower molecular weight fragments indicative of multiple recognition sites. The majority of the rDNA arrays in an individual were inaccessible to Hpa II (sensitive to mCpG) cleavage, but a significant fraction (10-25%) was cleaved at least once by Hpa II into repeat unit length fragments (9.1 kbp). In some maize inbred lines, one or two additional fragment populations (less than 9.1 kbp in length) were also produced by Hpa II digestion. All of the unmethylated Hpa II sites mapped to the intergenic spacer (IGS), and the major unmethylated site was located approximately 800 bp 5' to the start of the 18S RNA coding sequence. An Eco RI polymorphism, present in the 26S gene of certain inbred lines and hybrids, was utilized to investigate the organization of unmethylated repeat units in the rDNA array. In double digest experiments with Hpa II/Eco RI, the fragments from repeat units with two Eco RI sites were sensitive to Hpa II digestion, whereas, the fragments from repeat units with a single Eco RI site were almost completely resistant to Hpa II digestion. Similar digestion patterns were also observed in Eco RII (sensitive to mCNG)/Eco RI digests. These results suggest that unmethylated and Eco RI polymorphic sites occur in the same repeat units.

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Section: Discussionmentioning

confidence: 56%

Section: Discussionmentioning

confidence: 86%

Unmethylated regions in the intergenic spacer of maize and teosinte ribosomal RNA genes

Jupe

Zimmer

1990

Plant Mol Biol

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“…However, other known mechanisms might play a role in our study as well, such as (a) a differential transposition of somatically active transposable elements, which have been described in, so far, both invertebrates and vertebrates [43,44] or (b) the presence of heritable changes involving DNA within a single generation that have been observed in the annual flax [45]. We cannot exclude from our consideration the possibility of environmentally induced changes of genome size, as these changes have been observed during cell culturing [46][47][48]. Also, observed genome size changes may have been associated (not necessarily directly selected for) with changes in cell volume and/or in karyoplasmatic ratio.…”

Section: Selection For Genome Size In Cyclamen?mentioning

confidence: 95%

Genome size microscale divergence of Cyclamen persicum in Evolution Canyon, Israel

et al. 2008

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Using DAPI flow cytometry, we examined genome size divergence of the Persian violet, Cyclamen persicum (Primulaceae) (2n=48) on close opposite slopes of Evolution Canyon (EC), Mt. Carmel, Israel. The range of genome size variation detected among measured cyclamens was 6.41% in relation to the smallest measured DNA content. Our data on C. persicum at EC showed that local variability in the 2C-value exists. Significantly less DNA was recorded in plants growing in one station of the African savannah-like south-facing slope (AS) but not in the remaining two stations of the same slope. We were not able to reject the null hypothesis that there are no significant interslope differences in the genome size between the temperate European garrigue-like north-facing slope (ES) and the drier AS. In spite of the nonsignificant interslope trend for the higher genome size in C. persicum, the data-fusion (meta-analysis) test using correlations between C-values in C. persicum, and earlier studied carob tree (Ceratonia siliqua), trifoil (Lotus peregrinus) and a beetle (Oryzaephilus surinamensis) and their distribution along the aridity gradient indicates a positive relationship between drought and genome size at the microsite.

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“…There are several studies indicating differential methylation of rDNA repeats and some evidence that hypomethylation Abbreviations: azaC=azacytidine; bp=basepairs; mC=methyl-ated cytosine; CpG=deoxycytidine-phosphate-deoxyguanosine; X (in CpXpG)= any deoxyribonucleoside of a specific region in the intergenic spacer could regulate the expression of the rDNA genes (Ellis et al 1983;von Kalm et al 1986;Blundy et al 1987;Jupe and Zimmer 1990). There may also be differences in the methylation status of the DNA of developed plant organs and dedifferentiated callus (Reddy et al 1988;LoSchiavo et al 1989;Brown 1989;Brown et al 1989;Vergara et al 1990).…”

Section: Introductionmentioning

confidence: 98%

5-Azacytidine-induced hypomethylation of tobacco HRS60 tandem DNA repeats in tissue culture

Bezděk

Koukalová

Brzobohatý

et al. 1991

Planta

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The methylation status and 5-azacytidine-induced hypomethylation of CCGG sites within a family of tandemly organized, highly repeated DNA sequences of the Nicotiana tabacum L. nuclear genome (HRS60 family) were studied. As shown by in-situ hybridization experiments, the HRS60 family is clustered in a few regions of some tobacco chromosomes. The DNAs of leaf-derived calli, leaf-derived calli cultured on media with 5-azacytidine, and leaves were cleaved with restriction endonucleases differing in the sensitivity to the methylation of cytosine. After electrophoresis and Southern blotting they were hybridized with the HRS60 probe. We show that (i) CpG dinucleotides, and partially also CpCpG trinucleotides, of the HRS60 family are methylated in DNAs of the non-treated calli and leaves, and (ii) that these DNA repeats are sensitive to the action of a hypomethylating drug, 5-azacytidine.

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Ribosomal DNA methylation in a flax genotroph and a crown gall tumour

Cited by 24 publications

References 21 publications

Unmethylated regions in the intergenic spacer of maize and teosinte ribosomal RNA genes

Unmethylated regions in the intergenic spacer of maize and teosinte ribosomal RNA genes

Genome size microscale divergence of Cyclamen persicum in Evolution Canyon, Israel

5-Azacytidine-induced hypomethylation of tobacco HRS60 tandem DNA repeats in tissue culture

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