Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Molecular Sequence Annotation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed1998

Comparative analysis of 82 expressed sequence tags from a cattle ovary cDNA library.

In total, 82 ESTs were generated from 51 unique clones randomly selected from a cattle ovary cDNA library. Among these clones, 22 (42.1%) had 5' and/or 3' ends that matched with known human or other mammalian coding sequences, 18 (35.3%) matched human or other ESTs, and 11 (21.6%) represented novel transcripts with no significant match to any sequence in the databases. The relatively high frequency of ESTs with no matches in GenBank or dbEST indicates that bovine ovary may be a source of novel candidate genes for loci affecting cattle reproduction traits. Primers were designed for 11 ESTs that had human orthologs in GenBank. These ESTs were mapped to 10 bovine autosomes by PCR screening of a somatic cell hybrid panel. Among these 11 ESTs, 4 corresponded to genes previously mapped in humans and had chromosome assignments on the bovine map that were consistent with available comparative mapping data. Although the human orthologs of the remaining 7 mapped bovine ESTs have not been mapped, the human map location could be predicted on the basis of existing comparative mapping data. Because of the general utility of our approach for comparative genome analysis, we have termed it comparative mapping by annotation and sequence similarity (COMPASS). With the cost of large-scale EST sequencing becoming more affordable, and the rapid expansion of DNA databases, it is likely that COMPASS will be a preferred strategy for high throughput comparative mapping.

Animals↗
PubMed2006

DOCKGROUND resource for studying protein-protein interfaces.

MOTIVATION: Public resources for studying protein interfaces are necessary for better understanding of molecular recognition and developing intermolecular potentials, search procedures and scoring functions for the prediction of protein complexes. RESULTS: The first release of the DOCKGROUND resource implements a comprehensive database of co-crystallized (bound-bound) protein-protein complexes, providing foundation for the upcoming expansion to unbound (experimental and simulated) protein-protein complexes, modeled protein-protein complexes and systematic sets of docking decoys. The bound-bound part of DOCKGROUND is a relational database of annotated structures based on the Biological Unit file (Biounit) provided by the RCSB as a separated file containing probable biological molecule. DOCKGROUND is automatically updated to reflect the growth of PDB. It contains 67,220 pairwise complexes that rely on 14,913 Biounit entries from 34,778 PDB entries (January 30, 2006). The database includes a dynamic generation of non-redundant datasets of pairwise complexes based either on the structural similarity (SCOP classification) or on user-defined sequence identity. The growing DOCKGROUND resource is designed to become a comprehensive public environment for developing and validating new methodologies for modeling of protein interactions. AVAILABILITY: DOCKGROUND is available at http://dockground.bioinformatics.ku.edu. The current first release implements the bound-bound part.

Binding Sites↗
PubMed2004

Mammalian phylogenomics comes of age.

The relatively new field of phylogenomics is beginning to reveal the potential of genomic data for evolutionary studies. As the cost of whole genome sequencing falls, anticipation of complete genome sequences from divergent species, reflecting the major lineages of modern mammals, is no longer a distant dream. In this article, we describe how comparative genomic data from mammals is progressing to resolve long-standing phylogenetic controversies, to refine dogma on how chromosomes evolve and to guide annotation of human and other vertebrate genomes.

Animals↗
PubMed2005

A secondary structural model of the 28S rRNA expansion segments D2 and D3 for Chalcidoid wasps (Hymenoptera: Chalcidoidea).

We analyze the secondary structure of two expansion segments (D2, D3) of the 28S ribosomal (rRNA)-encoding gene region from 527 chalcidoid wasp taxa (Hymenoptera: Chalcidoidea) representing 18 of the 19 extant families. The sequences are compared in a multiple sequence alignment, with secondary structure inferred primarily from the evidence of compensatory base changes in conserved helices of the rRNA molecules. This covariation analysis yielded 36 helices that are composed of base pairs exhibiting positional covariation. Several additional regions are also involved in hydrogen bonding, and they form highly variable base-pairing patterns across the alignment. These are identified as regions of expansion and contraction or regions of slipped-strand compensation. Additionally, 31 single-stranded locales are characterized as regions of ambiguous alignment based on the difficulty in assigning positional homology in the presence of multiple adjacent indels. Based on comparative analysis of these sequences, the largest genetic study on any hymenopteran group to date, we report an annotated secondary structural model for the D2, D3 expansion segments that will prove useful in assigning positional nucleotide homology for phylogeny reconstruction in these and closely related apocritan taxa.

Animals↗
PubMed2002

Deductions about the number, organization, and evolution of genes in the tomato genome based on analysis of a large expressed sequence tag collection and selective genomic sequencing.

Analysis of a collection of 120,892 single-pass ESTs, derived from 26 different tomato cDNA libraries and reduced to a set of 27,274 unique consensus sequences (unigenes), revealed that 70% of the unigenes have identifiable homologs in the Arabidopsis genome. Genes corresponding to metabolism have remained most conserved between these two genomes, whereas genes encoding transcription factors are among the fastest evolving. The majority of the 10 largest conserved multigene families share similar copy numbers in tomato and Arabidopsis, suggesting that the multiplicity of these families may have occurred before the divergence of these two species. An exception to this multigene conservation was observed for the E8-like protein family, which is associated with fruit ripening and has higher copy number in tomato than in Arabidopsis. Finally, six BAC clones from different parts of the tomato genome were isolated, genetically mapped, sequenced, and annotated. The combined analysis of the EST database and these six sequenced BACs leads to the prediction that the tomato genome encodes approximately 35,000 genes, which are sequestered largely in euchromatic regions corresponding to less than one-quarter of the total DNA in the tomato nucleus.

Arabidopsis↗
PubMed2001

Genome cartography through domain annotation.

The evolutionary history of eukaryotic proteins involves rapid sequence divergence, addition and deletion of domains, and fusion and fission of genes. Although the protein repertoires of distantly related species differ greatly, their domain repertoires do not. To account for the great diversity of domain contexts and an unexpected paucity of ortholog conservation, we must categorize the coding regions of completely sequenced genomes into domain families, as well as protein families.

Animals↗
PubMed2005

Natural antisense as potential regulator of alternative initiation, splicing and termination.

In humans an estimated 35-60% of genes are alternatively spliced. A large number of genes also show alternative initiation or termination. Regulation of these processes is still poorly understood. For alternative splicing it is believed that the relative concentration of certain proteins and the presence of certain regulatory elements are the key factors determining alterations in splicing pattern. However, there is evidence that antisense RNA might be part of the regulatory processes. Antisense RNA molecules could bind to the target pre-mRNA in a sequence-specific fashion, sterically blocking targeted splice sites and redirecting the spliceosome to available and unhindered splice sites. Here we describe an in silico investigation to identify human sense/antisense pairs with alternative initiation or termination in the sense gene and where only one of the isoforms overlaps the antisense transcript. Alternatively spliced genes with antisense transcripts covering the alternatively used splice site are also identified. Our analyses are based on the ASAP splicing annotation database from UCLA, the antisense transcripts data from Yelin et al., 2003, and the H-invitational full-length cDNA database from JBIRC, Japan. These data gives new insight into the complexity of genomic organization and provide candidate loci for experimentalists to study antisense mediated regulation of alternative initiation, splicing and termination. Our result contains 468 clusters with this characteristic genomic organization and can be found at http://aistar.bii.a-star.edu.sg/.

Alternative Splicing↗
PubMed1994

Fast identification of repetitive elements in biological sequences.

We have developed a fast filtering method for searching repetitive sequences in databases that allows the simultaneous identification of different families of repetitive elements during the same scanning. It discriminates between repetitive elements and non-related sequences by comparing the frequencies of k-words found in both groups of sequences. The distance used to sort out the sequences is based on a weighting of the k-words, which is obtained by performing a correspondence analysis on learning sets of correctly chosen sequences. The identification of Alu elements in human sequences is given as an illustration of the method. The Alu sequences are divided in four distinct groups of elements: the left and right monomers located on the direct and on the complementary strands. The results obtained on the test sets show that a very good discrimination is achieved with a word length of 6 b.p. Indeed, only 0.5% of the non-Alu sequences were incorrectly predicted as Alu elements for a threshold value allowing the identification of all Alu monomers. The misclassification of the different Alu monomers (1.4%) in the four groups of examples occurs only when the left and the right monomers are in the same orientation. Moreover, during the scanning of 63 GenBank sequences longer than 10 Kb, all the Alu elements were correctly identified (616 elements) and only a few non-Alu sequences were wrongly predicted as Alu elements (22 fragments). There is a real need for this kind of method since most of the repetitive elements are not annotated in the database entries. This method can then be used for a systematic screening of new sequences before their insertion in databases. It can also allow the creation of specific databases devoted to repetitive elements, which is a required step for any further analysis of those elements.

Algorithms↗
PubMed2006

Development of bioinformatic tools to support EST-sequencing, in silico- and microarray-based transcriptome profiling in mycorrhizal symbioses.

The great majority of terrestrial plants enters a beneficial arbuscular mycorrhiza (AM) or ectomycorrhiza (ECM) symbiosis with soil fungi. In the SPP 1084 "MolMyk: Molecular Basics of Mycorrhizal Symbioses", high-throughput EST-sequencing was performed to obtain snapshots of the plant and fungal transcriptome in mycorrhizal roots and in extraradical hyphae. To focus activities, the interactions between Medicago truncatula and Glomus intraradices as well as Populus tremula and Amanita muscaria were selected as models for AM and ECM symbioses, respectively. Together, almost, 20.000 expressed sequence tags (ESTs) were generated from different random and suppressive subtractive hybridization (SSH) cDNA libraries, providing a comprehensive overview of the mycorrhizal transcriptome. To automatically cluster and annotate EST-sequences, the BioMake and SAMS software tools were developed. In connection with the eNorthern software SteN, plant genes with a predicted mycorrhiza-induced expression were identified. To support experimental transcriptome profiling, macro- and microarray tools have been constructed for the two model mycorrhizae, based either on PCR-amplified cDNAs or 70mer oligonucleotides. These arrays were used to profile the transcriptome of AM and ECM roots under different conditions, and the data obtained were uploaded to the ArrayLIMS and EMMA databases that are designed to store and evaluate expression profiles from DNA arrays. Together, the EST- and transcriptome databases can be mined to identify candidate genes for targeted functional studies.

Computational Biology↗
PubMed2026

A novel reusable transcriptome-wide association study workflow used to map key genes linked to important cattle traits.

Transcriptome-wide association studies (TWAS) are a powerful approach for studying the genes underlying complex traits by directly integrating GWAS and gene expression datasets. In cattle, they have been previously applied to identify genes driving fertility, milk production, and health. However, these studies have also highlighted several challenges, from difficulties in reproducing these complex analyses to limitations from poor genotype calls, especially when called directly from RNA sequencing data. To address these and other challenges, for the H2020 BovReg Project, we have developed a streamlined, species-agnostic, and reusable Nextflow TWAS workflow to integrate transcriptomic and GWAS summary statistic datasets. Our workflow first generates accurate genotype calls and gene expression prediction models from transcriptomic datasets and then applies these tools to impute gene expression levels into GWAS cohorts, enabling the association of genes with traits of interest. We explore optimal strategies for calling genetic variants directly from transcriptomic data and illustrate that using imputation approaches specifically designed for low-pass sequencing data can improve variant calling over previously adopted methods. We demonstrate the utility of our TWAS workflow by applying it to both novel and publicly available GWAS cohorts for cattle, detecting novel gene-trait associations for complex traits. Using a new transcriptome annotation of the cattle genome generated for the BovReg project we also illustrate how previously un-assayable associations can be detected. The results and the workflow we present, provide a new resource for the community and contribute to a better understanding of the molecular drivers of complex traits in cattle with the goal of eventually leveraging this information in future breeding decisions.

Animals↗
PubMed1999

The PIR-International Protein Sequence Database.

The Protein Information Resource (PIR; http://www-nbrf.georgetown. edu/pir/) supports research on molecular evolution, functional genomics, and computational biology by maintaining a comprehensive, non-redundant, well-organized and freely available protein sequence database. Since 1988 the database has been maintained collaboratively by PIR-International, an international association of data collection centers cooperating to develop this resource during a period of explosive growth in new sequence data and new computer technologies. The PIR Protein Sequence Database entries are classified into superfamilies, families and homology domains, for which sequence alignments are available. Full-scale family classification supports comparative genomics research, aids sequence annotation, assists database organization and improves database integrity. The PIR WWW server supports direct on-line sequence similarity searches, information retrieval, and knowledge discovery by providing the Protein Sequence Database and other supplementary databases. Sequence entries are extensively cross-referenced and hypertext-linked to major nucleic acid, literature, genome, structure, sequence alignment and family databases. The weekly release of the Protein Sequence Database can be accessed through the PIR Web site. The quarterly release of the database is freely available from our anonymous FTP server and is also available on CD-ROM with the accompanying ATLAS database search program.

Amino Acid Sequence↗
PubMed2004

Formin homology 2 domains occur in multiple contexts in angiosperms.

BACKGROUND: Involvement of conservative molecular modules and cellular mechanisms in the widely diversified processes of eukaryotic cell morphogenesis leads to the intriguing question: how do similar proteins contribute to dissimilar morphogenetic outputs. Formins (FH2 proteins) play a central part in the control of actin organization and dynamics, providing a good example of evolutionarily versatile use of a conserved protein domain in the context of a variety of lineage-specific structural and signalling interactions. RESULTS: In order to identify possible plant-specific sequence features within the FH2 protein family, we performed a detailed analysis of angiosperm formin-related sequences available in public databases, with particular focus on the complete Arabidopsis genome and the nearly finished rice genome sequence. This has led to revision of the current annotation of half of the 22 Arabidopsis formin-related genes. Comparative analysis of the two plant genomes revealed a good conservation of the previously described two subfamilies of plant formins (Class I and Class II), as well as several subfamilies within them that appear to predate the separation of monocot and dicot plants. Moreover, a number of plant Class II formins share an additional conserved domain, related to the protein phosphatase/tensin/auxilin fold. However, considerable inter-species variability sets limits to generalization of any functional conclusions reached on a single species such as Arabidopsis. CONCLUSIONS: The plant-specific domain context of the conserved FH2 domain, as well as plant-specific features of the domain itself, may reflect distinct functional requirements in plant cells. The variability of formin structures found in plants far exceeds that known from both fungi and metazoans, suggesting a possible contribution of FH2 proteins in the evolution of the plant type of multicellularity.

Actins↗
PubMed2006

Stolbur phytoplasma genome survey achieved using a suppression subtractive hybridization approach with high specificity.

Phytoplasmas are unculturable bacterial plant pathogens transmitted by phloem-feeding hemipteran insects. DNA of phytoplasmas is difficult to purify because of their exclusive phloem location and low abundance in plants. To overcome this constraint, suppression subtractive hybridization (SSH) was modified and used to selectively amplify DNA of the stolbur phytoplasma infecting a periwinkle plant. Plasmid libraries were constructed, and the origins of the DNA inserts were verified by hybridization and PCR screenings. After a single round of SSH, there was still a significant level of contamination with plant DNA (around 50%). However, the modified SSH, which included a second round of subtraction (double SSH), resulted in an increased phytoplasma DNA purity (97%). Results validated double SSH as an efficient way to produce a genome survey for microbial agents unavailable in culture. Assembly of 266 insert sequences revealed 181 phytoplasma genetic loci which were annotated. Comparative analysis of 113 kbp indicated that among 217 protein coding sequences, 83% were homologous to "Candidatus Phytoplasma asteris" (OY-M strain) genes, with hits widely distributed along the chromosome. Most of the stolbur-specific SSH sequences were orphan genes, with the exception of two partial coding sequences encoding proteins homologous to a mycoplasma surface protein and riboflavin kinase.

Bacterial Proteins↗
PubMed2006

Identification and analysis of the mouse basic/Helix-Loop-Helix transcription factor family.

The basic/Helix-Loop-Helix (bHLH) proteins are a family of transcription factors that regulates a variety of biological processes. Based on a previously defined consensus motif, we identified the complete set of bHLH protein family from the mouse proteome databases and carried out a series of bioinformatics analysis. As results, 124 mouse bHLH proteins were identified in this study, and 28 of them were additional bHLH proteins beyond the previous report. These 124 mouse bHLH proteins were classified into groups from A to F by the nomenclature and phylogenetic analysis. Statistic analysis of the Gene Ontology annotation of these proteins showed that the bHLH proteins tend to perform functions related to cell differentiation and development. Gene function enrichment analysis among six groups illuminated that the proteins in certain group tend to have special biology functions, so that the molecular function of the uncharacterized proteins in groups could be inferred.

Amino Acid Sequence↗
PubMed1997

In search of differentially expressed genes and proteins.

A great challenge for modern cell biology is the successful examination of the co-expression of thousands of genes under physiological or pathological conditions and how the expression patterns define the different states of a single cell, tissue or a microorganism. Gene expression can be analyzed today on a large scale by advanced technical approaches for differential screening of proteins and mRNAs. The identification of differentially expressed mRNAs has been successfully applied to understand gene function and the underlying molecular mechanism(-s) of differentiation, development and disease state. Analysis of gene expression by the systematic mapping of thousands of proteins present in a cell or tissue can be achieved by the use of two-dimensional (2D) gel electrophoresis, quantitative computer image analysis, and protein identification techniques. In this article, we comment on some of these techniques and try to stress their advantages and drawbacks. We show how data from RNA/DNA mapping, sequence information from genome projects and protein pattern profiling can be linked with each other and annotated. These comprehensive approaches permit the study of differential gene and protein expressions in cells or tissues.

Animals↗
PubMed2001

Identification of a 350-kDa ClpP protease complex with 10 different Clp isoforms in chloroplasts of Arabidopsis thaliana.

A 350-kDa ClpP protease complex with 10 different subunits was identified in chloroplast of Arabidopsis thaliana, using Blue-Native gel electrophoresis, followed by matrix-assisted laser desorption ionization time-of-flight and nano-electrospray tandem mass spectrometry. The complex was copurified with the thylakoid membranes, and all identified Clp subunits show chloroplast targeting signals, supporting that this complex is indeed localized in the chloroplast. The complex contains chloroplast-encoded pClpP and six nuclear-encoded proteins nCpP1-6, as well as two unassigned Clp homologues (nClpP7, nClpP8). An additional Clp protein was identified in this complex; it does not belong to any of the known Clp genes families and is here assigned ClpS1. Expression and accumulation of several of these Clp proteins have never been shown earlier. Sequence and phylogenetic tree analysis suggests that nClpP5, nClpP2, and nClpP8 are not catalytically active and form a new group of Clp higher plant proteins, orthologous to the cyanobacterial ClpR protein, and are renamed ClpR1, -2, and -3, respectively. We speculate that ClpR1, -2, and -3 are part of the heptameric rings, whereas ClpS1 is a regulatory subunit positioned at the axial opening of the ClpP/R core. Several truncations and errors in intron and exon prediction of the annotated Clp genes were corrected using mass spectrometry data and by matching genomic sequences with cDNA sequences. This strategy will be widely applicable for the much needed verification of protein prediction from genomic sequence. The extreme complexity of the chloroplast Clp complex is discussed.

Adenosine Triphosphatases↗
PubMed2003

Annotation of bacterial genomes using improved phylogenomic profiles.

MOTIVATION: Phylogenomic profiling is a large-scale comparative genomic method used to infer protein function from evolutionary information first described in a binary form by Pellegrini et al. (1999). Here, we propose improvements of this approach including the use of normalized Blastp bit scores, a normalization of the matrix of profiles to take into account the evolutionary distances between bacteria, the definition of a phylogenomic neighborhood based on continuous pairwise distances between genes and an original annotation procedure including the computation of a p-value for each functional assignment. RESULTS: The method presented here increases the number of Ecocyc enzymes identified as being evolutionarily related by about 25% with respect to the original binary form (absent/present) method. The fraction of 'false' positives is shown to be smaller than 20%. Based on their phylogenomic relationships, genes of unknown function can then be automatically related to annotated genes. Each gene annotation predicted is associated with a p-value, i.e. its probability to be obtained by chance. The validity of this method was extensively tested on a large set of genes of known function using the MultiFun database. We find that 50% of 3122 function attributions that can be made at a p-value level of 10(-11) correspond to the actual gene annotation. The method can be readily applied to any newly sequenced microbial genome. In contrast to earlier work on the same topic, our approach avoids the use of arbitrary cut-off values, and provides a reliability estimate of the functional predictions in form of p-values.

Algorithms↗
PubMed2006

Electrophysiological analysis of neuronal and muscle function in C. elegans.

The nematode Caenorhabditis elegans provides numerous experimental advantages for the identification and characterization of genes required for the function of the nervous system. These advantages include forward and reverse genetic tractability, a relatively simple body plan with an invariant cellular lineage, and a fully sequenced and well-annotated genome. However, one limitation of C. elegans is the relative scarcity of electrophysiological data from excitable cells. To address this limitation, high-resolution cellular techniques for probing the roles of specific gene products in the C. elegans nervous system have been recently developed. This chapter will provide an overview of the technical requirements for patch-clamp electrophysiological analysis of C. elegans neurons and muscle cells, as well as provide some illustrative examples of insights gained from the pairing of electrophysiological techniques with molecular and genetic analysis.

Animals↗