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2 edition of Studies on DNA sequences directing ribosomal transcription in Xenopus laevis found in the catalog.

Studies on DNA sequences directing ribosomal transcription in Xenopus laevis

Duncan Richard Smith

Studies on DNA sequences directing ribosomal transcription in Xenopus laevis

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Published by Portsmouth Polytechnic, Dept. of Biological Sciences in Portsmouth .
Written in English


Edition Notes

Statementby Duncan Richard Smith.
ID Numbers
Open LibraryOL14855563M

promoter mutants microinjected into late stage Xenopus oocytes, we have determined DNA sequences required for the transcription of this gene and we have identified proteins that bind to these regulatory sequences. A negative element lies between positions and malian UBF can function in Xenopus ribosomal dried and autoradiographed overnight or silver-stained [19]. XUBF transcription nor the Xenopzrs UBF (xUBF) in mam- was partially purified from a X. laevis tissue culture line as described (Read et al., submitted). For Southern analyses, 5pg DNA from a X. malian transcription [3,7]. A cloned repeat of Xenopus Zaevis satellite I DNA was tested for the ability to form stable complexes with tRNA transcription factors in vitro. In template exclusion studies, the satellite I DNA competed efficiently with a tRNA gene for binding of yeast RNA polymerase III transcription by: 2. The DNA helix rewinds once the transcription bubble has moved along. What does the termination step in transcription rely on? the terminator region present at the end of the reading frame. the RNA polymerase is removed and the helix completely rewinds, and the transcribed mRNA is released.

This chapter reviews the basis for the current view of eukaryotic tRNA promoters and transcription machinery, and discusses studies of mechanistic and regulatory strategies. Recent insights into the nature of the polymerase III transcription machinery give substance to these speculations and suggest a specific role for 5' flanking promoter by:


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Studies on DNA sequences directing ribosomal transcription in Xenopus laevis by Duncan Richard Smith Download PDF EPUB FB2

The DNA sequences required for efficient initiation of transcription of the Xenopus transcription factor IIIA (TFIIIA) gene were determined by microinjecting a series of deletion and linker substitution mutants into Xenopus oocyte by: Studies on DNA sequences directing ribosomal transcription in Xenopus laevis Author: Smith, D.

ISNI: Awarding Body: Portsmouth Polytechnic Current Institution: University of Portsmouth Date of Award: Availability of Full Text. Transcription of a cloned Xenopus laevis ribosomal DNA (rDNA) fragment, microinjected into Xenopus oocytes, is initiated at the in vivo 40S pre-ribosomal RNA (pre-rRNA) site (±2 bp) by RNA polymerase I.

An X. laevis RNA polymerase I promoter has been mapped by studying the transcription of in vitro rDNA mutants in the oocyte by: The ribosomal DNA spacer in Xenopus laevis was shown in previous studies to be involved in regulating the expression of the ribosomal genes.

Here transcription enhancement by this spacer has been studied in some detail, to fully identify the sequences involved and to determine their relative importance in this by: These ends hybridize specifically to a bp fragment of ribosomal DNA.

The nucleotides encoding the 5′ end of the 40S RNA were located more precisely by two methods. The nucleotide sequence of the initiation and termination sites for ribosomal rna transcription in x.

laevis: CellCited by: DNA CLONING and the direct visualisation of chromatin transcription by electron microscopy provide useful details of the structure and function of genes, but the value of these techniques would be. Abstract. In contrast to somatic cells, Xenopus oocytes accumulate large numbers of ribosomes for their subsequent use in early embryogenesis (Davidson, ).

To accommodate the need for ribosomal RNAs, the genes encoding the large ribosomal RNAs (i.e., 18 S, 28 S, and S rRNA) are amplified in the oocyte to yield about 2 × 10 6 extrachromosomal copies per nucleus (Brown and Weber, b Author: Angela Krämer.

The ribosomal DNA spacer in Xenopus laevis was shown in previous studies to be involved in regulating the expression of the ribosomal genes. Boseley P, Moss T, Mächler M, Portmann R, Birnstiel M. Sequence organization of the spacer DNA in a ribosomal gene unit of Xenopus laevis. Cell.

May; 17 (1)– Sollner-Webb B, Reeder RH. The nucleotide sequence of the initiation and termination sites for ribosomal RNA transcription in X. laevis. Cell. Oct; 18 (2)–Cited by: Volumenumber 2 FEBS LETTERS October PREPARATION OF COMPLEMENTARY DNA TO 5 S RIBOSOMAL RNA FROM XENOPUS LAEVIS Glenn E.

MORRIS and Trevor J. BEEBEE School of Biological Sciences, University of Sussex, Palmer, Cited by: 4. Abstract. Xenopus laevis is an important reference model organism used in many vertebrate studies. Gene mapping in X. laevis, in comparison to other reference organisms, is in its early studies have been conducted to localize DNA sequences on X.

laevis chromosomes. Primed in situ labeling (PRINS) is a recently developed innovative tool that has been used to locate specific DNA Cited by: 4. Location of the genes for 5S ribosomal RNA in Xenopus laevis.

Abstract. In situ hybridization of 5S RNA and cRNA transcribed in vitro from Xenopus laevis 5S DNA shows that 5S DNA is localized Studies on DNA sequences directing ribosomal transcription in Xenopus laevis book or near the telomere region of the long arm of many, if not all, of the X.

laevis by: ribosomal gene transcription in Xenopus laevis Paul Labhart I and Ronald H. Reeder Fred Hutchinson Cancer Research Center, Division of Basic Sciences, Seattle, Washington USA Two sites, T2 and T3, in the ribosomal gene spacer of Xenopus laevis both direct RNA 3'-end formation 15 bp upstream of the conserved box sequence GACTTGC.

Rare individuals of Xenopus laevis exhibit frequent initiation of transcription in the spacers of oocyte ribosomal DNA (rDNA).

Using electron microscopy we have characterized spacer transcription in such an individual and have confirmed that the sites of transcription initiation correspond to the imperfectly duplicated promoters ("Bam islands") present in the X. laevis rDNA by: ► TFIIIA functions as specific transcription factor for 5S rRNA genes ► TFIIIA zinc-fingers bind both 5S rDNA and the 5S rRNA gene product with high affinity.

► Sequence comparison suggests co-evolution of TFIIIA protein and 5S rRNA genes. ► TFIIIA availability is highly regulated to ensure cell-specific amounts of 5S by: Mapping of a Sequence Essential for the Nuclear Transport of the Xenopus Ribosomal Transcription Factor xUBF Using a Simple Coupled Translation-Transport and Acid Extraction Approach May DNA.

The Xenopus egg extract has become the gold standard for in vitro studies of metazoan DNA replication. We have used this system to study the mechanisms that ensure rapid and complete DNA.

The X. laevis ribosomal DNA spacer contains duplicated RNA polymerase I ”spacer promoters“ and an array of repeated 60 81 bp promoter-related sequences. The latter have been shown to enhance transcription from a 40S preribosomal RNA promoter in we present evidence that at least one spacer promoter is also necessary for efficient by:   A pentadeconucleotide, TGCCTCCCGAGTGCA, appeared twice within nucleotides upstream the putative initiation site.

No such characteristic sequences were found downstream this site. Little similarity was found in the upstream of the transcription initiation site between the mouse, Xenopus laevis and Saccharomyces cerevisiae by:   The complete sequence of nucleotide Xenopus laevis mitochondrial genome has been determined.

A comparison of this amphibian mitochondrial genomic sequence with those of the mammalian mitochondrial genomes reveals a similar gene order and compact genomic by: Localization of Repetitive DNA Sequences on in vitro Xenopus laevis Chromosomes by Primed in situ Labeling (PRINS) Article in Journal of Heredity 96(5) September with 19 Reads.

In the first, electron microscopic R-loop mapping of human genomic DNA, enriched for ribosomal sequences, is used to analyze the distribution of length variants of rDNA repeat units from a single. Abstract.

The complete sequence of nucleotide Xenopus laevis mitochondrial genome has been determined. A comparison of this amphibian mitochondrial genomic sequence with those of the mammalian mitochondrial genomes reveals a similar gene order and compact genomic organization.

indicated that the binding site of Xenopus laevis ribosomal protein L5 is dispersed widely along the entire 5S rRNA molecule.

The interaction of L5 with 5S rRNA may be dependent on the overall contribution of multiple contacts, rather than any particular site. The experimental data from these studies indicate that the specific protein-nucleic.

The time course of meiotic amplification of nucleolar DNA in Xenopus laevis oocytes has been studied autoradiographically. We find that the process is first detectable in zygotene nuclei less than 7 days after the end of premeiotic S-phase. It is completed 3 1/2 weeks later, towards the end of pachytene.

Premeiotic S-phase lasts for 1–2 by:   Abstract. With the aid of a novel poly-dA tailing-partial restriction technique and Sl-protection mapping, the 5′ terminal coding sequence for the 4OS precursor ribosomal RNA of Xenopus laevis has been exactly identified.

Since the promoter sequence for the 4OS RNA should lie close to its 5′ terminal coding sequence, we are able to conclude that the “Bam-Island” sequence reduplication Cited by:   In this study, we have located the sites of transcription initiation and termination on a cloned fragment of ribosomal DNA from X.

laevis, and have sequenced the surrounding nucleotides. As reported previously (Reeder, Sollner-Webb and Wahn, ), about 25% of the 40S rRNA precursor molecules isolated from oocytes have polyphosphate 5' termini Cited by: Sequence organization of the spacer DNA in a ribosomal gene unit of Xenopus laevis.

Boseley P, Moss T, Mächler M, Portmann R, Birnstiel M. A detailed restriction map was constructed for a cloned Xenopus laevis rDNA fragment containing the nontranscribed spacer (NTS) and external transcribed spacer (ETS) together with a portion of both the 18S and 28S rRNA by: However, in oöcytes from a wide variety of animals, this nucleolar DNA is selectively amplified and accumulated in the nucleus free of the chromosomes (Gall, ).

In Xenopus laevis, the best studied example, almost three-quarters of the nuclear DNA in a diplotene oöcyte codes exclusively for ribosomal RNA (Brown and Dawid, ). The extra Cited by: 8. Cellular regulation of ribosomal DNA transcription: Both rat and Xenopus UBF1 stimulate rDNA transcription in 3T3 fibroblasts, Nucleic Acids Research,pp.27/4, DOI: /nar/Cited by: GTC-3 ′ to amplify sequences – to +60 of the Xenopus laevis ribosomal promoter (26).

Construction of UBF expression constructs A number of full-length and mutant rat and Xenopus UBF expression constructs were used in this study (Fig. 1B).

pCMV-rUBF1 was generated by PCR from the rat UBF1 cDNA (27)Cited by: Hello. We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.

Abstract. Axeldb is a database storing and integrating gene expression patterns and DNA sequences identified in a large-scale in situ hybridization study in Xenopus laevis embryos. The data are organised in a format appropriate for comprehensive analysis, and enable comparison of images of expression pattern for any given set of by:   We have studied the protein components and nucleic acid sequences involved in stably activating the ribosomal DNA (rDNA) template and in directing accurate transcription of mammalian rRNA genes.

Two protein components are necessary to catalyze rDNA transcription, and these have been extensively purified. Abstract.

A novel RNA polymerase I (RPI) driven reporter gene has been used to investigate the in vivo role of the architectural ribosomal transcription factor UBF in gene activation and species specificity.

It is shown that the level of UBF overexpression in NIH3T3 cells leads to a proportionate increase in the activities of both reporter and endogenous ribosomal by: The major 5s DNA component in the genome of Xenopus laevis contains the structural genes cod- ing for the most abundant form of oocyte 5s ribosomal RNA.

This 5S RNA is synthesized in high yield in growing oocytes, but not in somatic cells of the frog. The oocyte 5s DNA consists of repeat. Pseudogenes are nonfunctional segments of DNA that resemble functional arise as superfluous copies of functional genes, either directly by DNA duplication or indirectly by reverse transcription of an mRNA transcript.

Pseudogenes are usually identified when genome sequence analysis finds gene-like sequences that lack regulatory sequences needed for transcription or.

Genetic studies. While Xenopus laevis is the most commonly used species for developmental biology studies, genetic studies, especially forward genetic studies, can be complicated by their pseudotetraploid genome.

Xenopus tropicalis provides a simpler model for genetic studies, having a diploid genome. Gene expression knockdown techniquesClass: Amphibia. This chapter reviews the methods that have been successfully used to date for the identification of RNA modification and editing enzymes.

The development of recombinant DNA and RNA techniques and techniques for chemical synthesis of DNA and RNA offers adequate alternatives for obtaining synthetic or semisynthetic unmodified or partially modified RNA substrates suitable for analyzing enzymatic Cited by: Abstract.

The RNA of the mature oocyte of Xenopus laevis has been studied in many laboratories and more extensively characterized than that of any other oocyte. Some of the information which has been developed relative to this RNA is summarized briefly in the paragraphs by: 1. Start studying Chapter Biology.

Learn vocabulary, terms, and more with flashcards, games, and other study tools. attaches DNA sequences at the ends of eukaryotic chromosomes -enzyme that prevents chromosome shortening by attaching many copies of a DNA repeat sequence to the ends of chromosomes the first tRNA, and ribosomal.Little was known about the function of the nucleolus untilwhen a study of nucleoli by John Gurdon and Donald Brown in the African clawed frog Xenopus laevis generated increasing interest in the function and detailed structure of the nucleolus.appears to be less important DNA sequence.

However the spacing between the UCE and the core is critical. Thus in vivo the two elements probably operate in concert to promote efficient transcription by RNA polymerase I. The Xenopus laevis rDNA promoter has been shown by deletion mapping experiments to lie between residues to +6 (9,10).