Patterns of major divergence between the internal transcribed spacers of ribosomal DNA in Xenopus borealis and Xenopus laevis, and of minimal divergence within ribosomal coding regions.

Furlong, Judith C.; Maden, B.E.H.

doi:10.1002/j.1460-2075.1983.tb01442.x

Cited by 65 publications

(21 citation statements)

References 32 publications

(33 reference statements)

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“…When this sequence is compared with the corresponding rice one, the regions adjacent to the 3' end of 17S rDNA and near the 5' end of 5.8S rDNA are highly conserved, while the middle parts are divergent. Such a divergency has been observed even in closely related species between X. borealis and X. laevis (3) and between mouse and rat (10). ITS sequences are not conserved during evolution.…”

Section: Its1mentioning

confidence: 97%

Nucleotide sequence of the 17S–25S spacer region from rice rDNA

1985

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The nucleotide sequence of a spacer region between rice 17S and 25S rRNA genes (rDNAs) has been determined. The coding regions for the mature 17S, 5.8S and 25S rRNAs were identified by sequencing terminal regions of these rRNAs. The first internal transcribed spacer (ITS1), between 17S and 5.8S rDNAs, is 194-195 bp long. The second internal transcribed spacer (ITS2), between 5.8S and 25S rDNAs, is 233 bp long. Both spacers are very rich in G+C, 72.7% for ITS1 and 77.3% for ITS2. The 5.8S rDNA is 163-164 bp long and similar in primary and secondary structures to other eukaryotic 5.8S rDNAs. The 5.8S rDNA is capable of interacting with the 5' terminal region of 25S rDNA.

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Section: Its1mentioning

confidence: 97%

Nucleotide sequence of the 17S–25S spacer region from rice rDNA

1985

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“…Sequence variation was also related to the secondary structure of the ITS-2 precursor rRNA, predicted using the MuFold program [15,16] available on GenBank  and based on comparisons with the secondary structures for other species of strongylid nematodes [17][18][19][20]. Included in the structural analyses were 20 bases from the 3'-end of the 5.8S rRNA gene and 20 bases from the 5'-end of the 28S rRNA gene, which have been shown to covalently bond to one another (e.g., [21]) and are considered important for the overall folding pattern [17][18][19][20].…”

Section: Dna Sequencing and Prediction Of Precursor Rrna Secondary Stmentioning

confidence: 99%

Single-strand conformation polymorphism analysis of genetic variation inLabiostrongylus longispicularis from kangaroos

et al. 2001

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Single-strand conformation polymorphism (SSCP) analysis was employed to screen for sequence heterogeneity in the second internal transcribed spacer (ITS-2) of ribosomal (r) DNA of Labiostrongylus longispicularis, a parasitic strongylid nematode occuring in some species of kangaroo in different geographical regions of Australia. The results showed that most of the nematodes screened had different SSCP profiles, which were subsequently shown to correspond to polymorphisms and/or an indel in the ITS-2 sequence. These variable sites related mainly to unpaired regions of the predicted secondary structure of the precursor rRNA molecule. SSCP profiles could be used to distinguish L. longispicularis in Macropus robustus robustus (New South Wales) from L. longispicularis in Macropus robustus erubescens and Macropus rufus (South Australia). This difference corresponded to a transversional change in the ITS-2 sequence at alignment position 82. The study demonstrated clearly the effectiveness of SSCP analysis for future large-scale population genetic studies of L. longispicularis in order to test the hypothesis that L. longispicularis from different geographical regions represents multiple sibling species.

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“…The relative spacing of the conserved elements in the X.borealis sequence with respect to that of X.laevis implies that insertions and deletions have played a major role in ITS sequence divergence (5). A similar conclusion has been reached for the ITS regions of rat and mouse (6).…”

Section: Introductionmentioning

confidence: 56%

“…As in the ITS regions (5), there are substantial length differences between the respective divergent tracts in the ETS regions of the two species ( figure 4). This implies a history of insertions and deletions during divergence, which in turn suggests a lack of sequence-specific function in these regions.…”

Section: Divergent Tracts and Length Differencesmentioning

confidence: 97%

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The external transcribed spacer and preceding region ofXenopus borealisrDNA: comparison with the corresponding region ofXenopus laevisrDNA

et al. 1983

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We report sequence data from a cloned rDNA unit from Xenopus borealis, extending leftwards from the 18S gene to overlap a region previously sequenced by R.Bach, B.Allet and M.Crippa (Nucleic Acids Research 9,[5311][5312][5313][5314][5315][5316][5317][5318][5319][5320][5321][5322][5323][5324][5325][5326][5327][5328][5329][5330].Comparison with data from other species of Xenopus leads to the inference that the transcription initiation site in X.borealis is in the newly sequenced region and not, as was previously thought, in the region sequenced earlier.The X.borealis external transcribed spacer thus defined is some 612 nucleotides long, about 100 nucleotides shorter than in X.laevis. The X.borealis and X.laevis external transcribed spacers show a pattern of extensive but interrupted sequence divergence, with a large conserved tract starting about 100 nucleotides downstream from the transcription initiation site and shorter conserved tracts elsewhere.The regions in between the conserved tracts differ in length between the respective external transcribed spacers indicating that insertions and deletions have contributed to their divergence, as previously inferred for the internal transcribed spacers.Much of the overall length difference is in the region flanking the 18S gene, where there are also length microheterogeneities in X.laevis rDNA.As in X.laevis, the transcribed spacer sequences flanking the 18S gene in X.borealis contain no major tracts of mutual complementarity. The accumulated data on transcribed spacers in Xenopus render it unlikely that processing of ribosomal precursor RNA involves interaction between the regions flanking 18S RNA.

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Patterns of major divergence between the internal transcribed spacers of ribosomal DNA in Xenopus borealis and Xenopus laevis, and of minimal divergence within ribosomal coding regions.

Cited by 65 publications

References 32 publications

Nucleotide sequence of the 17S–25S spacer region from rice rDNA

Nucleotide sequence of the 17S–25S spacer region from rice rDNA

Single-strand conformation polymorphism analysis of genetic variation inLabiostrongylus longispicularis from kangaroos

The external transcribed spacer and preceding region ofXenopus borealisrDNA: comparison with the corresponding region ofXenopus laevisrDNA

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