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At least 487 records · Page 27Linked to original sources

Endocarditis caused by Haemophilus parainfluenzae identified by 16S ribosomal RNA sequencing.

Haemophilus parainfluenzae, a human commensal, is an infrequent cause of serious disease. A case of endocarditis caused by this organism in a five year old boy with complex congenital heart disease is reported. The course of this disease was very aggressive, leading to heart failure, disseminated intravascular coagulation and multiorgan failure in spite of appropriate antibiotics and surgical intervention. The difficulties in the detection and identification of H parainfluenzae using conventional culture based technology, and the potential role of molecular techniques, are highlighted.

Anti-Bacterial Agents↗

fRNAdb: a platform for mining/annotating functional RNA candidates from non-coding RNA sequences.

There are abundance of transcripts that code for no particular protein and that remain functionally uncharacterized. Some of these transcripts may have novel functions while others might be junk transcripts. Unfortunately, the experimental validation of such transcripts to find functional non-coding RNA candidates is very costly. Therefore, our primary interest is to computationally mine candidate functional transcripts from a pool of uncharacterized transcripts. We introduce fRNAdb: a novel database service that hosts a large collection of non-coding transcripts including annotated/non-annotated sequences from the H-inv database, NONCODE and RNAdb. A set of computational analyses have been performed on the included sequences. These analyses include RNA secondary structure motif discovery, EST support evaluation, cis-regulatory element search, protein homology search, etc. fRNAdb provides an efficient interface to help users filter out particular transcripts under their own criteria to sort out functional RNA candidates. fRNAdb is available at http://www.ncrna.org/

Base Sequence↗

RNA sequences controlling the initiation and transfer of duck hepatitis B virus minus-strand DNA.

Hepadnaviruses replicate by reverse transcription of an RNA pregenome. Reverse transcription initiates within the stem-loop (SL) of the epsilon RNA packaging signal and is discontinuous: the nascent minus-polarity DNA is transferred to direct repeat 1 (DR1) at the 3' end of the pregenomic RNA prior to extensive elongation. In this study we analyzed the initiation and transfer of duck hepatitis B virus minus-strand DNA by using functional viral polymerase expressed in yeast cells. We extensively mutagenized both DR1 and the SL and observed the effects on reverse transcription initiation and on the transfer and subsequent extension of minus-strand DNA. Our results indicate that sequences throughout the SL affect initiation and that minus-strand DNAs initiated at three locations within the SL are competent for transfer to DR1. A short region of homology between the 5' end of minus-strand DNA and DR1 was necessary but not sufficient to direct the transfer and subsequent extension reactions. This homology was tolerant of minor substitutions, and 2 nucleotides of homology mediated transfer accurately. Mutations had greater detrimental effects on transfer and subsequent extension of minus-strand DNA when they were placed in DR1 than when they were placed in the SL. Efficient transfer of minus-strand DNA from a mutant SL to DR2 was observed in the yeast system. The hexanucleotide AAUUAC was identified as the primary cis element of the transfer acceptor, but this element was also insufficient to independently specify the acceptor location. Therefore, additional information, possibly positional context or unrecognized RNA secondary structure, is required.

Base Sequence↗

[Detection of anti-HEV IgG and analysis of partial HEV RNA sequence].

OBJECTIVES: To investigate HEV infection in swine and the genotype relationship between swine and human HEV. METHODS: Anti-HEV IgG antibody was detected in the sera of swine using enzyme linked immunoassay (EIA), and HEV RNA was amplified by reverse transcription nested polymerase chain reaction (RT-nPCR). The Vector NTI Suite 7 and TreeView softwares were used for nucleotide sequences phylogenetic analysis of HEV isolated from human and swine. RESULTS: The anti-HEV IgG positive rate was 16.67% (18/108). Among the 18 anti-HEV IgG positive sera, 2 sequences (11.11%, called S18 and S43, respectively) of HEV ORF1 (102-387bp) were amplified, with the identity of 99% between them. They had 76% to 77%, 78%, 76% to 79%, 85% to 86%, 77%, 80%, 79% and 75% - 79% homology at the nucleotide level with human HEV genotypes 1 to 8, respectively. One (S18) of them was also amplified out in ORF2 region (5,994-6 297bp) and showed 76% to 78%, 74%, 74% to 77%, and 85% to 94% identity with human HEV genotypes 1 to 4 at the nucleotide level, respectively. CONCLUSION: HEV sequences isolated from swine belong to human HEV genotype 4.

Animals↗

Self-catalyzed cyclization of the intervening sequence RNA of Tetrahymena: inhibition by methidiumpropyl.EDTA and localization of the major dye binding sites.

The intervening sequence (IVS) excised from the rRNA precursor of Tetrahymena thermophila is converted to a covalently closed circular RNA in the absence of proteins in vitro. This self-catalyzed cyclization reaction is inhibited by the intercalating dye methidiumpropyl.EDTA (MPE; R.P. Hertzberg and P.B. Dervan (1982) J. Am. Chem. Soc. 104, 313-315). The MPE binding sites have been localized by mapping the sites of MPE.Fe(II) cleavage of the IVS RNA. There are three major binding sites within the 414 nucleotide IVS RNA. Two of these sites coincide with the A.B and 9L.2 pairings. These are structural elements that are conserved in all group I introns and are implicated as being functionally important for splicing. We propose that interaction of MPE with these sites is responsible for dye inhibition of cyclization. The reactions of MPE.Fe(II) with an RNA of known structure, tRNAPhe, and with the IVS RNA were studied as a function of temperature, ionic strength and ethidium concentration. Based on the comparison of the reaction with these two RNAs, we conclude that the dye is a very useful probe for structural regions of large RNAs, while it provides more limited structural information about the small, compact tRNA molecule.

Animals↗

A human RNase E-like activity that cleaves RNA sequences involved in mRNA stability control.

We have detected an endoribonucleolytic activity in human cell extracts that processes the Escherichia coli 9S RNA and outer membrane protein A (ompA) mRNA with the same specificity as RNase E from E. coli. The human enzyme was partially purified by ion-exchange chromatography, and the active fractions contained a protein that was detected with antibodies shown to recognize E. coli RNase E. RNA containing four repeats of the destabilizing motif AUUUA and RNA from the 3' untranslated region of human c-myc mRNA were also found to be cleaved by E. coli RNase E and its human counterpart in a fashion that may suggest a role of this activity in mammalian mRNA decay. It was also found that RNA containing more than one AUUUA motif was cleaved more efficiently than RNA with only one or a mutated motif. This finding of a eukaryotic endoribonucleolytic activity corresponding to RNase E indicates an evolutionary conservation of the components of mRNA degradation systems.

Base Sequence↗

Absence of hepatitis C virus and detection of hepatitis G virus/GB virus C RNA sequences in the semen of infected men.

The identification of hepatitis C virus (HCV) in semen remains controversial and that of hepatitis G virus (HGV) or GB virus C (GBV-C) has never been investigated. Serum and semen from 90 anti-HCV-positive drug users were tested (27 infected with HIV) for HCV and HGV/GBV-C RNAs by polymerase chain reaction (PCR) assay, hybridization, and sequence analysis. Semen was processed into round cells, seminal plasma, and spermatozoa. Fifty-six patients were HCV-viremic, but HCV-RNA was not identified in their seminal fractions. However, PCR inhibitors were found in the semen of 34 of these men. Twenty-eight patients had HGV/GBV-C RNA in their blood and for 24 of them, ejaculates were available for analysis. HGV/GBV-C RNA was found in the seminal plasma of 6 of 12 samples free from PCR inhibitors. These results agree with the low risk of sexual transfer of HCV and provide preliminary evidence for the presence of HGV/GBV-C in semen.

AIDS-Related Opportunistic Infections↗

Improved laboratory diagnosis of bacterial and fungal infections in patients with hematological malignancies using PCR and ribosomal RNA sequence analysis.

During October 1999 to November 2000, 98 blood culture specimens from the same number of febrile episodes originating from 49 patients with hematological malignancies were examined for the presence of eubacteria and fungi based on 16S rRNA gene and the 5.8, 18 and 28S rRNA combined with in vitro PCR amplification and sequencing, in addition to conventional blood culture laboratory techniques. Nineteen of the samples were associated with positive blood cultures. Eubacterial (16S rRNA) PCR detected bacterial DNA in 26 febrile episodes, i.e. in an additional 7 febrile episodes than blood-culture alone. The species identified by partial 16S rRNA gene sequencing were as follows Staphylococcus spp (n = 6), Staphylococcus epidermidis (n = 5), Acinetobacter spp (n = 5), Escherichia coli (n = 2), Enterobacter agglomerans (n = 2), Campylobacter spp (n = 1), Citrobacter spp (n = 1), Corynebacterium spp (n = 1), Enterobacter faecium (n = 1), Ralstonia spp (n = 1), Acidovorax spp. (n = 1) and Stenotrophomonas maltophilia (n = 1). Gram-positive bacteria were found in 12/27 (44.6%) and gram-negative bacteria were found in 15/27 (55.6%). After optimization of a PCR-based fungal detection method, none of the febrile episodes were shown to be attributable to fungi. The results of this study suggest that fungi are not common causal agents of febrile episodes in patients with a hematological malignancy at this centre and that molecular techniques can augment cultural methods in the diagnosis of causal agents of bacteremia in patients, so that appropriate antibiotic regimens may be commenced in patients with culture-negative episodes of infection.

Adolescent↗

Intron-encoded small nucleolar RNAs: new RNA sequence variants and genomic loci.

Three small nucleolar RNAs (snoRNAs) whose 5' termini are monophosphorylated, termed E1, E2 and E3, were reported earlier, and E1 and E3 are encoded in pre-mRNA gene introns. In the present work, the ends of these snoRNAs were identified by analysis of terminal mononucleotides, and heterogeneity was observed at the 3' ends of E1 and E2 RNAs. Two new E1 RNA species were detected in HeLa cells by cDNA cloning. Four novel human genomic loci were identified that have E1 or E3 sequence homology. The sequence CTAGAGCACYSAATCTGGAT (where S = C or G and Y = C or T), that is present three nucleotides downstream from the coding region of an E1 RNA-encoding gene, lies in the same location in a different human genomic locus (which has a E1-homology sequence whose expression has not been detected yet), suggesting that this sequence may be functional.

Base Sequence↗

Rapid RNA sequencing: nucleases from Staphylococcus aureus and Neurospora crassa discriminate between uridine and cytidine.

Using end-labelled RNA, significant changes in base specificity of three nucleases have been detected under defined conditions. Staphylococcus aureus nuclease at pH 3.5 without Ca++ cleaves all Pyr-N bonds more uniformly and efficiently than RNase A, without any preference for Pyr-A bonds. At pH 7.5 in 10 mM Ca++ this enzyme cleaves all N-C and N-G bonds slowly, whereas N-U and N-A bonds are hydrolyzed rapidly. Hence, the base at the 3'- or at the 5'-side of a phosphodiester bond can determine the base specificity of S. aureus nuclease. - In absence of urea, Neurospora crassa endonuclease cleaves all phosphodiester bonds, but leaves all C-N bonds intact in 7 M urea. - RNase U2 at pH 3.5 cleaves A-N bonds more efficiently than at pH 5.0.

Base Sequence↗

RNA sequence requirements for NasR-mediated, nitrate-responsive transcription antitermination of the Klebsiella oxytoca M5al nasF operon leader.

In Klebsiella oxytoca, enzymes required for nitrate assimilation are encoded by the nasFEDCBA operon. Nitrate and nitrite induction of nasF operon expression is determined by a transcriptional antitermination mechanism, in which the nasR gene product responds to nitrate or nitrite and overcomes transcription termination at the factor-independent terminator site located in the nasF upstream leader region. Previous studies led to the hypothesis that the NasR protein mediates transcription antitermination through interaction with nasF leader RNA. Here, we report a DNA sequence comparison that reveals conserved 1:2 and 3:4 RNA secondary structures in the nasF leader RNAs from two Klebsiella species. Additionally, we found that specific binding of the NasR protein to nasF leader RNA was stimulated by nitrate and nitrite. We combined mutational analysis, in vivo and in vitro antitermination assays, and an RNA electrophoretic mobility shift assay to define regions in the nasF leader that are essential for antitermination and for NasR-RNA interaction. Formation of the 1:2 stem structure and the specific sequence of the 1:2 hexanucleotide loop were required for both nitrate induction and for NasR-RNA interaction. Mutations in the 1:2 stem-loop region that abolished nitrate induction also interfered with NasR-leader RNA interaction. Finally, nucleotide alterations or additions in the linker region between the 1:2 and 3:4 stem-loops were deleterious to nasF operon induction but not to NasR-leader RNA interaction. We hypothesize that NasR protein recognizes the 1:2 stem-loop structure in the nasF leader RNA to mediate transcription antitermination in response to nitrate or nitrite.

Bacterial Proteins↗

Spontaneous rearrangements in RNA sequences.

The ability of RNAs to spontaneously rearrange their sequences under physiological conditions is demonstrated using the molecular colony technique, which allows single RNA molecules to be detected provided that they are amplifiable by the replicase of bacteriophage Qbeta. The rearrangements are Mg2+-dependent, sequence-non-specific, and occur both in trans and in cis at a rate of 10(-9) h(-1) per site. The results suggest that the mechanism of spontaneous RNA rearrangements differs from the transesterification reactions earlier observed in the presence of Qbeta replicase, and have a number of biologically important implications.

Allolevivirus↗

Analysis of spleen focus-forming virus-specific RNA sequences coding for spleen focus-forming virus-specific glycoprotein with a molecular weight of 55,000 (gp55).

The 32S RNA of the Friend strain of spleen focus-forming virus (SFFV) contains two sets of sequences: about half is specific to SFFV, and the other half is in common with the sequence of the helper lymphatic leukemia virus. Fingerprinting analysis of RNase T1 oligonucleotides showed that the SFFV-specific sequences were located in two distinct regions: in the 3' half and near the 5' terminus of the genome. Translation of SFFV RNA in a cell-free system yielded three SFFV-specific polypeptides: two main products with molecular weights of about 47,000 (P47) and 16,000 (P16) and a variable amount of a product with a molecular weight of 40,000 (P40). P47 was translated from polyadenylic acid-containing fragments of 1,500 to 3,000 nucleotides with SFFV-specific sequences from the 3' half of the genome, whereas P16, which contained peptides in common with those of P47, was synthesized by smaller RNA. P47 formed in vitro was found to be structurally related to the protein portion of a glycoprotein, gp55, specifically found in SFFV-infected cells in vitro. It is concluded from the results that a defective env gene containing SFFV-specific sequences in the 3' half of the genome codes for SFFV-specific gp55.

Animals↗

Polyadenylated RNA sequences which are reduced in concentration following auxin treatment of soybean hypocotyls.

Previous work has shown that any effect of exogenous auxin on gene expression in soybean hypocotyl tissue must be restricted to a relatively small fraction of the polyadenylated RNA. However, kinetic hybridization analysis with cDNA probes revealed that a minor abundant class of sequences is markedly reduced in concentrations in the auxin-treated polyadenylated RNA. Recombinant plasmids containing copies of polyadenylated RNA species were constructed using the G-C tailing procedure and clones of auxin-regulated sequences were detected by differential in situ hybridization with cDNA of polyadenylated RNA from auxin-treated or untreated hypocotyls. Although the 12 clones which were selected all contained different size inserts, and were therefore independent, 11 of these apparently hybridized to just two different RNA species. The rate constant of the auxin-sensitive abundant component of the untreated polyadenylated RNA/DNA hybridization was similar to that of the reaction between the two major groups of clones and untreated polyadenylated RNA. This indicates that these cloned sequences are homologous with that cDNA fraction. The twelfth clone is thought to be representative of a group of less abundnt auxin-regulated polyadenylated mRNA species which had been detected in an earlier analysis of the in vitro translation products of soybean hypocotyl RNA. Both the timing and the extent of the influence of auxin on the relative concentration of these cloned sequences are quite consistent with a close relationship between growth regulation by auxin and its effects on gene expression.

Base Sequence↗

DNA and RNA sequencing utilizing phosphorothioate chemistry.

A method for nucleic acid sequencing has been developed based on the observation that phosphorothioate diesters are hydrolysed by treatment with 2-iodoethanol in a solution of aqueous ethanol. For DNA sequencing, primed single-stranded M13 DNA is polymerised with the Klenow fragment of DNA polymerase I in the presence of the three normal deoxyribonucleotide triphosphates and one alpha-phosphorothioate derivative. This is followed by treatment with 2-iodoethanol, precipitation of the DNA fragments and analysis by polyacrylamide electrophoresis. RNA transcribed from plasmids containing the SP6 RNA polymerase promoter is sequenced by including the alpha-phosphorothioate derivative of the ribonucleotide triphosphates in the polymerisation and treating the product with iodoethane. The cleavage reaction involves alkylation of the sulfur atom to form the phosphorothioate triester and hydrolysis catalysed by an adjacent hydroxyl group.

Base Sequence↗

Detection of enterovirus-specific RNA sequences in explanted myocardium biopsy specimens from patients with dilated or ischemic cardiomyopathy.

Enteroviral RNA (EV-RNA) was detected in endomyocardial tissue by means of retrotranscription and polymerase chain reaction (RT-PCR) followed by slot-blot hybridization. The myocardial biopsy specimens studied were taken at the time of heart transplantation from 15 patients with dilated cardiomyopathy (DCM) and from 10 patients with ischemic cardiomyopathy (ICM). Specimens from 18 (72%) of the 25 patients were positive for EV-RNA, whereas no control specimens (myocardial specimens from 29 healthy organ donors and atrial specimens from 15 patients with acute myocardial infarction treated by anatomic bypass) yielded evidence of EV-RNA. The rates of EV-RNA detection for the two groups requiring heart transplantation did not differ significantly (66.7% vs. 80.0%; chi 2 test). Our findings support a link between enteroviral infection in both DCM and ICM and suggest a pathogenic role for the enteroviruses.

Adult↗

Self-ligating RNA sequences on the antigenome of human hepatitis delta virus.

A 179-base fragment of RNA from the 1,679-base antigenome of hepatitis delta virus can not only self-cleave but, when the ends of the resultant fragments are brought into apposition by base pairing to another RNA, also self-ligate. Thus, processing events needed for genome replication in vivo may be strictly RNA mediated.

Hepatitis Delta Virus↗