Localization of thein vivoandin vitrotranscription initiation site and comparative analysis of the flanking sequences in the two main size classes ofAscaris lumbricoidesrDNA

Briner, Giorgio; Müller, Eliane J.; Neuhaus, Heinz; Back, Eduard; Müller, Fritz; Tobler, Heinz

doi:10.1093/nar/15.16.6515

Cited by 6 publications

(7 citation statements)

References 44 publications

(20 reference statements)

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“…NucZeotide sequence of the region surrounding the putative transcription initiation site (TS) of IVS+ rDNA. The reference sequence of IVS-rDNA is taken from the cZone pAlr8, representing the main size cZass rDNA of 8.8 kb (26). NucZeotides are numbered with respect to the initiation site.…”

Section: Resultsmentioning

confidence: 99%

“…Of the coding regions, only the first 162 bp of the 18S rRNA gene have been analyzed, and a single pointmutation is found at position +464. However, the region which most probably contains the Pol I promoter (26) and surrounds the transcription initiation site (TS in Figures 2 and 3) from posi- C)…”

Section: Resultsmentioning

confidence: 99%

“…The HindIII subclone pClH (cf. Figure 2), truncated with different restriction enzymes, was assayed in a whole-cell in vitro extract from A. lumbricoides oogonia (26). Figure 4D shows, besides some non-specific end-to-end transcripts and RNA breakdown products, that the different fragments from IVS+ rDNA are correctly transcribed.…”

Section: Resultsmentioning

confidence: 99%

“…The rDNA templates from clones with and without an intervening sequence were transcribed in a whole-cell in vitro extract from A. lumbricoides oogonia, as described (26). After transcription, the RNA was purified and electrophoresed on 5% polyacrylamide gels as reported (26).…”

Section: In Vitro Transcriptionmentioning

confidence: 99%

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Type I-like Intervening sequences are found in the rDNA of the nematodeAscaris lumbricoides

et al. 1987

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The intervening sequences in the large ribosomal RNA gene of Ascaris lumbricoides var. suum show many similarities to the type I insertions, previously found only in some insect species. They include structural features, but also a presumed transcriptional inactivity in vivo: No transcript of the rDNA intervening sequence in A. lumbricoides could be detected in Northern and dot blot hybridizations. However, the primary structure of the Pol I promoter region is well conserved in interrupted and uninterrupted genes. Moreover, genes with an intervening sequence are correctly initiated in a whole-cell in vitro extract from Ascaris oogonia. Hence, the presence of the intervening sequence alone does not seem to account for a transcriptional inhibition in rRNA genes. As with the type I insertions of insect rDNA, some copies of the A. lumbricoides intervening sequence are also present in locations outside the rDNA cluster. About 50% of the extraribosomal copies are found in a repetitive sequence of the genome, and additional copies are inserted in unique sequences. These striking analogies to type I insertions are discussed, and lead to the conclusion that the two phenomena are undoubtedly related. This is the first report proving the presence of a type I-like insertion element outside of the class Insecta.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: In Vitro Transcriptionmentioning

confidence: 99%

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Type I-like Intervening sequences are found in the rDNA of the nematodeAscaris lumbricoides

et al. 1987

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“…High levels of luciferase activity were observed in Ascaris embryos transfected with a pGL-3͞AscUTR construct containing the Ascaris ribosomal RNA promoter (22)(23)(24) followed 3Ј with a 105-bp trans-splice acceptor from the vacuolar ATP synthase subunit gene (Fig. 3C) (15,(25)(26)(27)(28)(29).…”

Section: Expression Of a Marked Spliced Leader (Sl) Rna Gene Inmentioning

confidence: 99%

Transient expression of DNA and RNA in parasitic helminths by using particle bombardment

Davis

Parra

LoVerde

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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Parasitic helminths (worms belonging to several metazoan phyla) cause considerable morbidity and mortality in humans. They are an important veterinary problem, and they result in significant economic losses in animal grazing and agriculture. Experimental studies on parasitic helminths have been limited by a lack of parasite cell lines and methods for molecular genetic analyses. We evaluated particle bombardment (biolistics) as a strategy to introduce and express nucleic acids in these multicellular parasites. By using embryos of the parasitic nematode Ascaris as a model, we developed methods to introduce and express both DNA and RNA during several stages of Ascaris embryogenesis. Biolistic transfection will facilitate experimental strategies in Ascaris embryos complementing other biochemical tools available (e.g., in vitro whole-cell embryo extracts for transcription, RNA processing, and translation). Transfection experiments with adult schistosomes further suggest that the biolistic strategy should be applicable to a variety of other parasitic helminths. The development of these methods provides molecular genetic tools to study gene expression and the biology of a variety of types and developmental stages of important helminth parasites.

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Unusual transcription termination of the ribosomal RNA genes in Ascaris lumbricoides.

et al. 1990

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We studied termination of transcription of the ribosomal RNA genes in Ascaris lumbricoides, the first representative in the phylum of nemathelminthes analysed so far. RNase protection experiments in vivo reveal that the 3′ end of the precursor rRNA coincides with the end of mature 26S rRNA. Promoter‐containing miniplasmids are able to direct unique 3′ end formation in vitro at a site identical to that observed in vivo, whereas deletion of these sequences abolishes 3′ end formation throughout the entire spacer. A nuclear run‐on experiment in vitro confirms the drop of polymerase I concentration down‐stream of this site. The termination site for polymerase I transcription of the rDNA operon in A. lumbricoides is therefore unique, and located at the very end of the 26S rRNA gene.

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Localization of thein vivoandin vitrotranscription initiation site and comparative analysis of the flanking sequences in the two main size classes ofAscaris lumbricoidesrDNA

Cited by 6 publications

References 44 publications

Type I-like Intervening sequences are found in the rDNA of the nematodeAscaris lumbricoides

Type I-like Intervening sequences are found in the rDNA of the nematodeAscaris lumbricoides

Transient expression of DNA and RNA in parasitic helminths by using particle bombardment

Unusual transcription termination of the ribosomal RNA genes in Ascaris lumbricoides.

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