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Gene expression in donor corneal endothelium.

OBJECTIVE: To report gene expression profiles of normal human corneal endothelium with microarray analysis and serial analysis of gene expression (SAGE). METHODS: Corneal endothelium was removed from normal human corneas obtained from eye banks. Total RNA was isolated and SAGE analysis was performed. The same RNA source was used to construct a complementary DNA library that was hybridized to microarrays containing 12 558 transcripts. RESULTS: A total of 9530 SAGE tags were sequenced, representing 4724 unique tags. Microarray analysis identified 542 distinct transcripts. A database of human corneal endothelial gene expression was compiled. Of the SAGE tags, 1720 matched known genes, 478 corresponded to expressed sequence tags, and 2526 had no known match to public databases. The 5 most abundantly expressed SAGE tags were cytochrome c oxidase subunit II, adenosine triphosphate synthase F(0) subunit 6, carbonic anhydrase XII, 12S ribosomal RNA, and ferritin, heavy polypeptide 1. Thirty-four percent of the transcripts (n = 1616) were specific to the corneal endothelium, when compared with other publicly available SAGE libraries. The 5 most abundant unique tags were keratin 12, angiopoietinlike factor, annexin A8, and 2 tags with no match to the database. Many endothelial pump function enzymes were confirmed, including several plasma membrane Na( +)/K(+) adenosine triphosphatases and a recently reported bicarbonate transporter. CONCLUSIONS: Corneal endothelial gene expression profiles by the current analysis provide an understanding of endothelial metabolism, structure, and function; enable comparisons to diseased endothelium; and provide baseline data that may lead to the discovery of novel endothelial genes.

Aged↗

Genetic relatedness of six North-Indian butterfly species (Lepidoptera :Pieridae) based on 16S rRNA sequence analysis.

The present work involves the assessment of level of genetic relatedness or divergence amongst the six North-Indian species of Lepidoptera belonging to family Pieridae and sub family Pierinae on the basis of sequence variation of 16S ribosomal RNA. The PCR amplified products of these species were directly sequenced using ABI Prism BigDye Terminator Sequencing Kits (Applied Biosystems). The multiple nucleotide sequence alignment analysis has revealed several differences across these species. Significantly high percentage of A + T base composition content ranging between 73.13% (Ixias pyrene ) and 79.20 % (Pieris brassica) was observed in studied species. The percentage divergence in the investigated species of Pieridae family varied from 5.5% to 21.7%. The two species of Catopsilia revealed minimum sequence divergence of only 5.5%, whereas the other two groups of Ixias and Pieris revealed 15.5% and 8.6% sequence divergence, respectively. Pieris canidia and Ixias pyrene are genetically most divergent (21.7%) amongst the studied lepidopteran species. Phylogenetic analysis based on 16S rRNA nucleotide sequence revealed grouping of six species of Lepidoptera in the form of two different clusters, each cluster being represented by two species from the same genera. The separate taxonomic grouping of these Indian species has been observed when compared with several species of Piernae and Coliadinae subfamilies from other country isolates.

Animals↗

In silico discovery of human natural antisense transcripts.

BACKGROUND: Several high-throughput searches for potential natural antisense transcripts (NATs) have been performed recently, but most of the reports were focused on cis type. A thorough in silico analysis of human transcripts will help expand our knowledge of NATs. RESULTS: We have identified 568 NATs from human RefSeq RNA sequences. Among them, 403 NATs are reported for the first time, and at least 157 novel NATs are trans type. According to the pairing region of a sense and antisense RNA pair, hNATs are divided into 6 classes, of which about 87% involve 5' or 3' UTR sequences, supporting the regulatory role of UTRs. Among a total of 535 NAT pairs related with splice variants, 77.4% (414/535) have their pairing regions affected or completely eliminated by alternative splicing, suggesting significant relationship of alternative splicing and antisense-directed regulation. The extensive occurrence of splice variants in hNATs and other multiple pairing patterns results in a one-to-many relationship, allowing the formation of complex regulation networks. Based on microarray data from Stanford Microarray Database, two hNAT pairs were found to display significant inverse expression patterns before and after insulin injection. CONCLUSION: NATs might carry out more extensive and complex functions than previously thought. Combined with endogenous micro RNAs, hNATs could be regarded as a special group of transcripts contributing to the complex regulation networks.

Algorithms↗

The phylogeny of Myxosporea (Myxozoa) based on small subunit ribosomal RNA gene analysis.

The phylogeny of the Myxosporea was studied using the small-subunit ribosomal RNA gene sequences. Maximum parsimony and Bayesian inference were used to determine myxosporean phylogenetic relationships. The analysis included 120 myxosporean sequences retrieved from GenBank and 21 newly obtained sequences of myxosporeans representing nine genera. Members of the genera Palliatus and Auerbachia were sequenced for the first time. The phylogenetic analysis supported a split of myxosporeans into two main lineages separating most of freshwater species from marine ones as described by previous authors. In addition to the two main lineages, a third lineage consisting of three species was found (Sphaerospora truttae, Sphaerospora elegans and Leptotheca ranae) and additional exceptions to the marine/freshwater myxosporean split were recognised (Sphaeromyxa hellandi, Sphaeromyxa longa and Myxidium coryphaenoideum). All three myxosporean lineages were characterised by specific lengths of SSU rDNA sequences. The lineage of marine myxosporeans split into five well-defined clades. They consisted of species with a similar site of infection and spore morphology and were referred as the Parvicapsula clade, the Enteromyxum clade, the Ceratomyxa clade, the marine Myxidium clade and the Kudoa clade, respectively. The inner topology of the freshwater clade was more complex but the trend to branch according to site of infection was observed in this clade as well. Due to the number of sequences available, a histozoic (Myxobolus clade) predominated. Interestingly, five morphologically different species infecting urinary bladder clustered within the histozoic (Myxobolus) clade. The phylogenetic trees derived from this study differ in a number of respects from the current taxonomy of the myxosporeans, which suggests that several currently utilised characters may be homoplasious or that reliance on a single gene tree may not adequately reflect the phylogeny of the group.

Animals↗

Cucumber mosaic virus satellite RNA (strain Y): analysis of sequences which affect systemic necrosis on tomato.

The location of a sequence within the Y satellite RNA of cucumber mosaic virus (CMV) that confers the ability to induce necrosis on tomato plants has been analysed using chimeric satellite RNAs. These recombinant RNA molecules contained parts of the Y (necrogenic) and Ra (benign) satellite RNAs and were inoculated into tomato plants together with CMV helper virus. From the composition of the recombinant satellite RNAs that induced necrosis it was concluded that, of the nucleotides which differ between Y and Ra satellite RNAs, those affecting necrosis are on the 3' side of nucleotide 259. The composition of satellite RNAs that failed to induce necrosis implies that at least some of the necrogenic positions are on the 3' side of nucleotide 311. The symptoms induced by mutated forms of Y and Ra satellite RNAs showed that nucleotide spacing between positions 322 and 323 and sequence identity at one or more of nucleotides 318, 323 or 325 affects the necrogenic potential of Y satellite RNA. The effect of a frameshifting mutation in Y satellite RNA and the location of the necrogenic sites relative to open reading frames in other satellite RNAs suggested that necrosis is not caused by polypeptides encoded in satellite RNA.

Base Sequence↗

Effect of aflatoxin B1-8,9-epoxide-DNA adducts on transcription of a supF gene fragment.

A linearized template, obtained from the vector pGEM-3Zf(+) containing a supF gene fragment, was treated with aflatoxin B1-8,9-epoxide (AFB1 epoxide) and transcription in vitro was then studied. The template functions of both strands of the supF gene were similarly inhibited as shown by transcription with both T7 and SP6 RNA polymerases. This inhibition was dose-dependent and affected the elongation step more extensively than the initiation step. Gel electrophoretic analysis of RNA formed by T7 RNA polymerase indicated that template treated with different AFB1 epoxide doses yielded the same three major truncated RNA fragments. Sequence analysis showed that these major sites of RNA truncation occurred in the vicinity of adjacent guanine residues in the template.

Aflatoxin B1↗

Characterization and detection of plant trypanosomatids by sequence analysis of the small subunit ribosomal RNA gene.

The complete sequences of the genomic small subunit ribosomal RNA gene from two Phytomonas isolates: one associated with palm pathologies (P. cocos FGuiana) and one found in lactiferous plants with no apparent pathology (P. Euphorbe Senegal), were analyzed. Partial sequences from a number of other Phytomonas isolates were also determined. The sequences obtained were used to determine the phylogenetic relationships between Phytomonas and other trypanosomatids as well as within the genus Phytomonas. The analysis showed that the intraphloemic isolates associated with pathologies in palm trees formed a homogeneous group that diverged from the more heterogeneous group of non-pathogenic isolates found in latex plant. Sequence comparisons of the full and partial SSU rRNA gene, identified sequences which are specific to the genus Phytomonas and an EcoRI restriction nuclease site which specifically identifies the Phytomonas isolates associated with diseases in palm trees.

Animals↗

Rapid ribosomal RNA sequencing and the phylogenetic analysis of protists.

A newly described technique for rapidly obtaining the partial nucleotide sequence of ribosomal RNA is being applied to investigate phylogenetic relationships among living organisms. Alan Johnson and Peter Boverstock describe the importance of this method to parasitology in providing new information on the phylogenetic relationships of parasitic organisms previously placed in groups of convenience. The phylum Apicomplexo in particular, has been the object of much study using this technique, but the technology is likely to extend soon to the restructuring of the phylogenetic trees of many groups of parasites.

Journal Article↗

Parallel single-cell host immune profiling and pathogen genomic characterization in Klebsiella-associated sepsis: a pilot study.

OBJECTIVES: Sepsis is a life-threatening syndrome characterized by profound immune dysregulation and substantial biological heterogeneity. Here, we conducted a pilot study to explore host immune remodeling in Klebsiella-associated sepsis by combining single-cell RNA sequencing of peripheral blood mononuclear cells with whole-genome sequencing of the corresponding bloodstream isolates. METHODS: In this prospective observational pilot study, we analyzed peripheral blood mononuclear cells (PBMCs) from two patients with Klebsiella-associated sepsis and two healthy controls (HC) using single-cell RNA sequencing. PBMC composition, differential transcriptional responses, and pathway analysis were assessed across immune subsets. The corresponding bloodstream isolates were characterized by phenotypic antimicrobial susceptibility testing and whole-genome sequencing. RESULTS: Compared to HC, septic patients showed expansion of the myeloid compartment and contraction of the NK/T compartment. High-resolution analysis suggested shifts within lymphoid populations. At the transcriptional level, sepsis was associated with compartment-specific enrichment of interferon-related and host-defence pathways, as well as oxidative phosphorylation, ATP synthesis, and mitochondrial electron transport signatures across multiple PBMC subsets. Classical monocytes exhibited a coordinated decrease in MHC class II-related transcripts. The sepsis-associated isolates were identified as Klebsiella pneumoniae and Klebsiella variicola and were notable for overall antimicrobial susceptibility, limited resistomes, and absence of canonical hypervirulence determinants. CONCLUSION: Our data provide a preliminary description of immune remodeling during Klebsiella-associated sepsis and suggest that severe clinical disease may be associated with isolates lacking classical multidrug-resistance or hypervirulence features. These findings should be interpreted as preliminary and hypothesis-generating and require validation in larger cohorts with detailed clinical severity assessment.

Female↗

An iterated loop matching approach to the prediction of RNA secondary structures with pseudoknots.

MOTIVATION: Pseudoknots have generally been excluded from the prediction of RNA secondary structures due to its difficulty in modeling. Although, several dynamic programming algorithms exist for the prediction of pseudoknots using thermodynamic approaches, they are neither reliable nor efficient. On the other hand, comparative methods are more reliable, but are often done in an ad hoc manner and require expert intervention. Maximum weighted matching, an algorithm for pseudoknot prediction with comparative analysis, suffers from low-prediction accuracy in many cases. RESULTS: Here we present an algorithm, iterated loop matching, for reliably and efficiently predicting RNA secondary structures including pseudoknots. The method can utilize either thermodynamic or comparative information or both, thus is able to predict pseudoknots for both aligned and individual sequences. We have tested the algorithm on a number of RNA families. Using 8-12 homologous sequences, the algorithm correctly identifies more than 90% of base-pairs for short sequences and 80% overall. It correctly predicts nearly all pseudoknots and produces very few spurious base-pairs for sequences without pseudoknots. Comparisons show that our algorithm is both more sensitive and more specific than the maximum weighted matching method. In addition, our algorithm has high-prediction accuracy on individual sequences, comparable with the PKNOTS algorithm, while using much less computational resources. AVAILABILITY: The program has been implemented in ANSI C and is freely available for academic use at http://www.cse.wustl.edu/~zhang/projects/rna/ilm/ SUPPLEMENTARY INFORMATION: http://www.cse.wustl.edu/~zhang/projects/rna/ilm/

Algorithms↗

A double-labeling procedure for sequence analysis of picomole amounts of nonradioactive RNA fragments.

A double-labeling procedure for sequence analysis of nonradioactive polyribonucleotides is detailed, which is based on controlled endonucleolytic degradation of 3'-terminally (3H)-labeled oligonucleotide-(3') dialcohols and 5"-terminal analysis of the partial (3H)-labeled fragments following their separation according to chain length by polyethyleneimine- (PEI-)cellulose TLC and detection by fluorography. Undesired nonradioactive partial digestion products are eliminated by periodate oxidation. The 5'-termini are assayed by enzymic incorporation of (32p)-label into the isolated fragments, enzymic release of (32p)-labeled nucleoside-(5') monophosphates, two-dimensional PEI-cellulose chromatography, and autoradiography. Using this procedure, as little as 0.1 - 0.3 A260 unit of tRNA is needed to sequence all fragments in complete ribonuclease T1 and A digests, whereas radioactive derivative methods previously described by us1-4 required 4 - 6 A260 units.

Base Sequence↗

Sequence analysis of an artificial family of RNA-binding peptides.

Diverse peptide sequences recognizing the lambda boxB RNA hairpin were previously isolated from a library encoding the 22-residue lambda N peptide with random amino acids at positions 13-22 using mRNA display. We have statistically analyzed amino acid distributions in 65 unique sequences from rounds 11 and 12 of this selection and evaluated the resulting structural and functional predictions by alanine-scanning mutagenesis and circular dichroism spectrometry. This artificial sequence family has a consensus structure that continues the bent alpha helix of lambda N up to position 17 when bound to lambda boxB. A charge pair (E(14)R(15)) and hydrophobic patch (A(21)L(22) or V(21)L(22)) have important functional roles in this context. Notably, amino acid covariance reveals six specific pairs of random region positions with >95% significant linkage and strong overall helical (i+1, i+3, and i+4) couplings. The covariance analysis suggests that (1) the sequence context of every residue in each insert has been optimized, (2) selected sequences are local optima on a rugged fitness landscape, and (3) it is possible to detect more subtle structural features with artificial protein sequence families than natural homologs. Our results provide a framework for investigating the structures of in vitro selected proteins by functional minimization, reselection, and covariance analysis.

Amino Acid Sequence↗

Development of a citrus genome-wide EST collection and cDNA microarray as resources for genomic studies.

A functional genomics project has been initiated to approach the molecular characterization of the main biological and agronomical traits of citrus. As a key part of this project, a citrus EST collection has been generated from 25 cDNA libraries covering different tissues, developmental stages and stress conditions. The collection includes a total of 22,635 high-quality ESTs, grouped in 11,836 putative unigenes, which represent at least one third of the estimated number of genes in the citrus genome. Functional annotation of unigenes which have Arabidopsis orthologues (68% of all unigenes) revealed gene representation in every major functional category, suggesting that a genome-wide EST collection was obtained. A Citrus clementina Hort. ex Tan. cv. Clemenules genomic library, that will contribute to further characterization of relevant genes, has also been constructed. To initiate the analysis of citrus transcriptome, we have developed a cDNA microarray containing 12,672 probes corresponding to 6875 putative unigenes of the collection. Technical characterization of the microarray showed high intra- and inter-array reproducibility, as well as a good range of sensitivity. We have also validated gene expression data achieved with this microarray through an independent technique such as RNA gel blot analysis.

Citrus↗

Yeast populations associated with Ghanaian cocoa fermentations analysed using denaturing gradient gel electrophoresis (DGGE).

The yeast populations associated with the fermentation of Ghanaian cocoa were investigated using denaturing gradient gel electrophoresis (DGGE). Samples were collected at 12-24 h intervals from heap and tray fermentations, at three different fermentation sites and different periods during the season. Eukaryotic universal primers were used to amplify a fragment of the 26S rRNA gene. The DGGE profiles were relatively complex, underlining that the fermentation of cocoa is a complex microbial process. The identities of selected fragments in the denaturing gels were revealed by sequencing. Hanseniaspora guilliermondii, Candida krusei and Pichia membranifaciens were detected from most fermentations, indicating their possible important role in the fermentation of Ghanaian cocoa. Saccharomyces cerevisiae and Candida zemplinina were almost exclusively detected during tray fermentations. The developed DGGE protocol was compared with traditional culture-based isolations. The results were comparable but slightly different, as one yeast species (C. zemplinina) was only detected using DGGE. On the other hand, Trichosporon asahii yielded only faint bands in the denaturing gels, despite the fact that it was detected using culture-based methods. Analysis of pure cultures showed that the targeted region of the 26S rRNA gene was poorly amplified in T. asahii, whereas all other investigated isolates were amplified efficiently using the chosen PCR approach. Cluster analysis revealed that the DGGE profiles clustered according to fermentation method and fermentation site. Furthermore, clustering according to progress in the fermentation was observed. The DGGE technique therefore seems to offer a relatively fast and reliable method for studying yeast population dynamics during cocoa fermentations.

Base Sequence↗

Asymptomatic urethritis and detection of HIV-1 RNA in seminal plasma.

OBJECTIVE: To define risk factors for detection of HIV-1 RNA in semen in men attending the two largest HIV clinics in the West Midlands. METHODS: 94 HIV-1 seropositive men at any stage of infection donated matched semen and blood samples. 36 subjects (38%) were on no antiretroviral treatment, 12 (13%) were on dual therapy, and 46 (49%) were on three or more drugs. Median CD4 count was 291 cells x 10(6)/l. 87 subjects underwent a urethritis screen (Gram stained urethral smear and culture for gonococcus, and LCR for Chlamydia trachomatis on first pass urine). Quantitative cell free HIV-1 RNA was determined by commercial nucleic acid sequence based assay with a lower detection limit of 800 copies/ml for semen and 400 copies/ml for blood. Independent risk factors for seminal HIV RNA detection were defined by logistic regression. RESULTS: In univariate analysis, subjects not taking antiretrovirals were 11 times more likely to shed HIV RNA (21/36 (58%) v 6/58 (10%); p < 0.0001). Seven subjects (8%) had urethritis (including one C trachomatis infection). Urethritis was significantly associated with detection of seminal HIV RNA (adjusted OR, 80.2; p = 0.006), as was blood plasma viral load (adj OR, 19.3 per factor 10 increase; p < 0.001) and age (adj OR, 1.16 per 1 year older; p = 0.001). Antiviral treatment status, absolute CD4 and CD8 count, clinical stage, treatment centre, ethnicity, and risk factor were not independent predictors. No subject with undetectable blood viral load had detectable seminal HIV RNA. CONCLUSION: Asymptomatic urethritis is independently associated with seminal HIV RNA shedding.

Adult↗

Systematics of the ascomycetous yeasts assessed from ribosomal RNA sequence divergence.

Extent of divergence in partial nucleotide sequences from large and small subunit ribosomal RNAs was used to estimate genetic relationships among ascomycetous yeasts and yeastlike fungi. The comparisons showed four phylogenetically distinct groups comprised of the following taxa: Group 1. The budding yeasts Saccharomyces, Saccharomycopsis, Debaryomyces, Metschnikowia, Saturnospora, and Lipomyces, and the yeastlike genera Ascoidea, Cephaloascus, Dipodascus, Dipodascopsis, and Galactomyces; Group 2. Eremascus, Emericella and Ceratocystis; Group 3. Taphrina and Protomyces; Group 4. Schizosaccharomyces. Because of the genetic relationships indicated by sequence analysis, Group 1 taxa are retained in the order Endomycetales, and Schizosaccharomyces is retained in the Schizosaccharomycetales Prillinger et al. ex Kurtzman.

Ascomycota↗

Quantum dot-conjugated hybridization probes for preliminary screening of siRNA sequences.

In the present study, we describe the design and fabrication of quantum dot-conjugated hybridization probes and their application to the development of a comparatively simple and rapid procedure for the selection of highly effective small-interfering RNA (siRNA) sequences for RNA interference (RNAi) in mammalian cells, for example, siRNAs with high accessibility and affinity to the respective mRNA target. A single-stranded siRNA was conjugated with a quantum dot and used as a hybridization probe. The target mRNA was amplified in the presence of Cy5-labeled nucleotides, and Cy5-mRNA served as a hybridization sample. The formation of siRNA/mRNA duplexes during a comparatively short hybridization time (1 h) was used as a criterion for the selection of highly effective, target-specific siRNA sequences. The accessibility and affinity of the siRNA sequence for the target mRNA site were determined by fluorescence resonance energy transfer (FRET) between a quantum dot (donor) and a fluorescent dye molecule (Cy5, acceptor) localized at an appropriate distance from each other when hybridization occurred. The FRET signal was observed only when there was high accessibility between an antisense siRNA and a sense mRNA and did not appear in the case of mismatch siRNAs. Moreover, the amplitude of the FRET signal significantly correlated with the specific effect of siRNA on the expression of the target mRNA and protein, determined in native cells by RT-PCR and immunoblot analysis, respectively.

Base Sequence↗

Large-scale gene expression profiling of discrete brain regions: potential, limitations, and application in genetics of aggressive behavior.

Many behavioral geneticists are interested in unraveling the molecular mechanisms underlying aggressive behavior. So far, most scientists have based their search for aggression-related genes on a preliminary functional hypothesis. Large-scale gene expression profiling techniques, such as serial analysis of gene expression (SAGE) and DNA microarrays, now enable the screening of expression levels of thousands of genes simultaneously, allowing the identification of new candidate aggression-related genes expressed in brain and thus the generation of new hypotheses. However, expression profiling in the brain is challenging, as brain is a complex heterogeneous tissue where large numbers of genes are expressed and relatively small changes in gene expression occur. In this special issue, we focus on the principles of SAGE and DNA microarrays, as well as their advantages and disadvantages and application to analysis in brain tissue in order to identify aggression-related genes.

Aggression↗