MMDB: 3D structure data in Entrez

Three-dimensional structures are now known for roughly half of all protein families. It is thus quite likely, in searching sequence databases, that one will encounter a homolog with known structure and be able to use this information to infer structure-function properties. The goal of Entrez's 3D structure database is to make this information accessible and useful to molecular biologists. To this end, Entrez's search engine provides three powerful features: (i) Links between databases; one may search by term matching in Medline((R)), for example, and link to 3D structures reported in these articles. (ii) Sequence and structure neighbors; one may select all sequences similar to one of interest, for example, and link to any known 3D structures. (iii) Sequence and structure visualization; identifying a homolog with known structure, one may view a combined molecular-graphic and alignment display, to infer approximate 3D structure. Entrez's MMDB (Molecular Modeling DataBase) may be accessed at: http://www.ncbi.nlm.nih.gov/Entrez/structure.html     

Statistical analysis and graphical representation the temporal and distributive properties of urodynamic data.

A collection of programs are described to analyze and display urodynamic data on a digital plotter. Utilizing a small programmable calculator, routines have been written to characterize the temporal and distributive properties of experimentally observed ureteral peristalses and associated urine output. The encoding pricipals used are designed to optimally use limited calculator memory.     

Complete sequences of mitochondria genomes of Aedes aegypti and Culex quinquefasciatus and comparative analysis of mitochondrial DNA fragments inserted in the nuclear genomes

We present complete sequences of the mitochondrial genomes for two important mosquitoes, Aedes aegypti and Culex quinquefasciatus, that are major vectors of dengue virus and lymphatic filariasis, respectively. The A. aegypti mitochondrial genome is 16,655 bp in length and that of C. quinquefasciatus is 15,587 bp, yet both contain 13 protein coding genes, 22 transfer RNA (tRNA) genes, one 12S ribosomal RNA (rRNA) gene, one 16S rRNA gene and a control region (CR) in the same order. The difference in the genome size is due to the difference in the length of the control region. We also analyzed insertions of nuclear copies of mtDNA-like sequences (NUMTs) in a comparative manner between the two mosquitoes. The NUMT sequences occupy ~0.008% of the A. aegypti genome and ~0.001% of the C. quinquefasciatus genome. Several NUMTs were found localized in the introns of predicted protein coding genes in both genomes (32 genes in A. aegypti but only four in C. quinquefasciatus). None of these NUMT-containing genes had an ortholog between the two species or had paralogous copies within a genome that was also NUMT-containing. It was further observed that the NUMT-containing genes were relatively longer but had lower GC content compared to the NUMT-less paralogous copies. Moreover, stretches of homologies are present among the genic and non-genic NUMTs that may play important roles in genomic rearrangement of NUMTs in these genomes. Our study provides new insights on understanding the roles of nuclear mtDNA sequences in genome complexities of these mosquitoes.     

Genome Reviews: standardizing content and representation of information about complete genomes

The Genome Reviews database provides up-to-date, standardized, and comprehensively annotated views of the genomic sequence of organisms with completely deciphered genomes. Currently, Genome Reviews contains information about the genomes of archaea, bacteria, and selected lower eukaryotes. Expansion to viral genomes and additional eukaryotes is planned. Genome Reviews is available for download in relational and flat file formats. In this paper, the rationale behind the creation of Genome Reviews, the approach taken in standardizing the data and its representation, and particular issues encountered in doing so are described.     

Complete mitochondrial genomes of three neobatrachian anurans: a case study of divergence time estimation using different data and calibration settings

We sequenced the whole mitochondrial (mt) genomes of three neobatrachian species: Japanese tree frog Hyla japonica, Japanese common toad Bufo japonicus, and narrow-mouthed toad Microhyla okinavensis. The gene arrangements of these genomes diverged from that of basal anurans (suborder Archaeobatrachia), but are the same as that of the members of derived frogs (i.e., superfamily Hyloidae and Ranoidae in suborder Neobatrachia), suggesting the one-time occurrence of a gene rearrangement event in an ancestral lineage of derived anurans. Furthermore, several distinct repeat motifs including putative termination-associated sequences (TASs) and conserved sequence blocks (CSBs) were observed in the control regions (CRs) of B. japonicus and H. japonica, while no repeat motifs were found in that of M. okinavensis. Phylogenetic analyses using both nucleotide and amino acid data of mt genes support monophyly of neobatrachians. The estimated divergence time based on amino acid data with multiple reference points suggests that the three living amphibian orders may have originated in the Carboniferous period, and that the divergences of anurans had occurred between the Permian and Tertiary periods. We also checked the influence of the data types and the settings of reference times on divergence time estimation. The resultant divergence times estimated from several datasets and reference time settings suggest that the substitution saturation of nucleotide data may lead to overestimated (i.e., older) branching times, especially for early divergent taxa. We also found a highly accelerated substitution rate in neobatrachian mt genes, and fast substitution possibly resulted in overestimation. To correct this erroneous estimation, it is efficient to apply several reference points among neobatrachians.     

Concordance analysis of microbial genomes.

The set of proteins which are conserved across families of microbes contain important targets of new anti-microbial agents. We have developed a simple and efficient computational tool which determines concordances of putative gene products that show sets of proteins conserved across one set of user specified genomes and not present in another set of user specified genomes. The thresholds and the homology scoring criterion are selectable to allow the user to decide the stringency of the homologies. The system uses a relational database to store protein coding regions from different genomes, and to store the results of a complete comparison of all sequences against all sequences using the FASTA program. Using Web technology, the display of all the related proteins for a given sequence and calculation of multiple sequence alignments (using CLUSTALW) can be performed with the click of a button. The current database holds 97 365 sequences from 19 complete or partial genomes and 8798905 FASTA comparison results. A example concordance is presented which demonstrates that the target of the quinolone antibiotics could have been identified using this tool.     

Reticulate representation of evolutionary and functional relationships between phage genomes

Bacteriophage genomes show pervasive mosaicism, indicating the importance of horizontal gene exchange in their evolution. Phage genomes represent unique combinations of modules, each of them with a different phylogenetic history. The traditional classification, based on a variety of criteria such as nucleic acid type (single/double-stranded DNA/RNA), morphology, and host range, appeared inconsistent with sequence analyses. With the genomic era, an ever increasing number of sequenced phages cannot be classified, in part due to a lack of morphological information and in part to the intrinsic incapability of tree-based methods to efficiently deal with mosaicism. This problem led some virologists to call for a moratorium on the creation of additional taxa in the order Caudovirales, in order to let virologists discuss classification schemes that might better suit phage evolution. In this context, we propose a framework for a reticulate classification of phages based on gene content. Starting from gene families, we built a weighted graph, where nodes represent phages and edges represent phage-phage similarities in terms of shared genes. We then apply various measures of graph topology to analyze the resulting graph. Most double-stranded DNA phages are found in a single component. The values of the clustering coefficient and closeness distinguish temperate from virulent phages, whereas chimeric phages are characterized by a high betweenness coefficient. We apply a 2-step clustering method to this graph to generate a reticulate classification of phages: Each phage is associated with a membership vector, which quantitatively characterizes its membership to the set of clusters. Furthermore, we cluster genes based on their "phylogenetic profiles" to define "evolutionary cohesive modules." In virulent phages, evolutionary modules span several functional categories, whereas in temperate phages they correspond better to functional modules. Moreover, despite the fact that modules only cover a fraction of all phage genes, phage groups can be distinguished by their different combination of modules, serving the bases for a higher level reticulate classification. These 2 classification schemes provide an automatic and dynamic way of representing the relationships within the phage population and can be extended to include newly sequenced phage genomes, as well as other types of genetic elements.     

Microsatellites in different Potyvirus genomes: survey and analysis

Simple sequence repeats (SSRs) have been extensively used for various genetic and evolutionary studies in eukaryotic and prokaryotic organisms, while few relevant researches have been made in viruses. The Potyvirus is a fine system to study roles and evolution of SSRs in viruses. The densities, relative abundances, compositions and evolutionary inferences of SSRs in 45 different Potyvirus genomes have been analyzed in this study. Results showed that the densities and relative abundances of SSRs are similar in all those Potyvirus genomes. The number of SSRs decreases with an increase in the length of repeat unit. Dinucleotide repeats are the most abundant and followed by trinucleotide repeats, and the numbers of tetra-, penta- and hexanucleotide repeats are very small. Repeats of AC/CA, AG/GA and AAG/GAA predominate, whereas repeats of CG/GC, ATA and CAC are rare. The genome sizes of the Potyvirus species have little influence on the total number and relative abundance of SSRs. Our study suggested that the variety of SSRs may be related to the genome diversity of Potyvirus. Maybe Potyvirus and HIV genomes have the similar evolution mode and parallel evolution level.     

Complete nucleotide sequence of the sugarcane (Saccharum officinarum) chloroplast genome: a comparative analysis of four monocot chloroplast genomes.

The complete nucleotide sequence of the chloroplast genome of sugarcane (Saccharum officinarum) has been determined. It is a circular double-stranded DNA molecule, 141,182 bp in size, and is composed of a large single copy of 83,048 bp, a small single copy of 12,544 bp, and a pair of inverted repeat regions of 22,795 bp each. A comparative analysis among monocots showed that the sugarcane chloroplast genome was very similar to maize but not to rice or wheat. Between sugarcane and maize at the rps16-trnQ (UUG) region, however, a length polymorphism was identified. With regard to insertions/deletions equal to or longer than 5 bp, a total of 53 insertion and 31 deletion events were identified in the sugarcane chloroplast genome. Of the 84 loci identified, a pair of direct repeat sequences was located side by side in a tandem fashion in 47 loci (56.0%). A recombination event during plant evolution is discussed at two sites between the sugarcane and tobacco chloroplast genomes.     

ProGenExpress: Visualization of quantitative data on prokaryotic genomes

Background  

The integration of genomic information with quantitative experimental data is a key component of systems biology. An increasing number of microbial genomes are being sequenced, leading to an increasing amount of data from post-genomics technologies. The genomes of prokaryotes contain many structures of interest, such as operons, pathogenicity islands and prophage sequences, whose behaviour is of interest during infection and disease. There is a need for simple and novel tools to display and analyse data from these integrated datasets, and we have developed ProGenExpress as a tool for visualising arbitrarily complex numerical data in the context of prokaryotic genomes.     

Genome Information Broker (GIB): data retrieval and comparative analysis system for completed microbial genomes and more

Genome Information Broker (GIB) is a powerful tool for the study of comparative genomics. GIB allows users to retrieve and display partial and/or whole genome sequences together with the relevant biological annotation. GIB has accumulated all the completed microbial genome and has recently been expanded to include Arabidopsis thaliana genome data from DDBJ/EMBL/GenBank. In the near future, hundreds of genome sequences will be determined. In order to handle such huge data, we have enhanced the GIB architecture by using XML, CORBA and distributed RDBs. We introduce the new GIB here. GIB is freely accessible at http://gib.genes.nig.ac.jp/.     

iMapper: a web application for the automated analysis and mapping of insertional mutagenesis sequence data against Ensembl genomes

SUMMARY: Insertional mutagenesis is a powerful method for gene discovery. To identify the location of insertion sites in the genome linker based polymerase chain reaction (PCR) methods (such as splinkerette-PCR) may be employed. We have developed a web application called iMapper (Insertional Mutagenesis Mapping and Analysis Tool) for the efficient analysis of insertion site sequence reads against vertebrate and invertebrate Ensembl genomes. Taking linker based sequences as input, iMapper scans and trims the sequence to remove the linker and sequences derived from the insertional mutagen. The software then identifies and removes contaminating sequences derived from chimeric genomic fragments, vector or the transposon concatamer and then presents the clipped sequence reads to a sequence mapping server which aligns them to an Ensembl genome. Insertion sites can then be navigated in Ensembl in the context of genomic features such as gene structures. iMapper also generates test-based format for nucleic acid or protein sequences (FASTA) and generic file format (GFF) files of the clipped sequence reads and provides a graphical overview of the mapped insertion sites against a karyotype. iMapper is designed for high-throughput applications and can efficiently process thousands of DNA sequence reads. AVAILABILITY: iMapper is web based and can be accessed at http://www.sanger.ac.uk/cgi-bin/teams/team113/imapper.cgi.     

PDBML: the representation of archival macromolecular structure data in XML

Summary: The Protein Data Bank (PDB) has recently released versionsof the PDB Exchange dictionary and the PDB archival data filesin XML format collectively named PDBML. The automated generationof these XML files is driven by the data dictionary infrastructurein use at the PDB. The correspondences between the PDB dictionaryand the XML schema metadata are described as well as the XMLrepresentations of PDB dictionaries and data files. Availability: The current software translated XML schema fileis located at http://deposit.pdb.org/pdbML/pdbx-v1.000.xsd,and on the PDB mmCIF resource page at http://deposit.pdb.org/mmcif/.PDBML files are stored on the PDB beta ftp site at ftp://beta.rcsb.org/pub/pdb/uniformity/data/XML Contact: jwest{at}rcsb.rutgers.edu     

Sequence analysis of genes and genomes

A major step towards understanding of the genetic basis of an organism is the complete sequence determination of all genes in its genome. The development of powerful techniques for DNA sequencing has enabled sequencing of large amounts of gene fragments and even complete genomes. Important new techniques for physical mapping, DNA sequencing and sequence analysis have been developed. To increase the throughput, automated procedures for sample preparation and new software for sequence analysis have been applied. This review describes the development of new sequencing methods and the optimisation of sequencing strategies for whole genome and cDNA analysis, as well as discusses issues regarding sequence analysis and annotation.     

Complete mitochondrial genomes of five skippers (Lepidoptera: Hesperiidae) and phylogenetic reconstruction of Lepidoptera

We sequenced mitogenomes of five skippers (family Hesperiidae, Lepidoptera) to obtain further insight into the characteristics of butterfly mitogenomes and performed phylogenetic reconstruction using all available gene sequences (PCGs, rRNAs, and tRNAs) from 85 species (20 families in eight superfamilies). The general genomic features found in the butterflies also were found in the five skippers: a high A + T composition (79.3%–80.9%), dominant usage of TAA stop codon, similar skewness pattern in both strands, consistently length intergenic spacer sequence between tRNA^Gln and ND2 (64–87 bp), conserved ATACTAA motif between tRNA^{Ser (UCN)} and ND1, and characteristic features of the A + T-rich region (the ATAGA motif, varying length of poly-T stretch, and poly-A stretch). The start codon for COI was CGA in four skippers as typical, but Lobocla bifasciatus evidently possessed canonical ATG as start codon. All species had the ancestral arrangement tRNA^Asn/tRNA^{Ser (AGN)}, instead of the rearrangement tRNA^{Ser (AGN)}/tRNA^Asn, found in another skipper species (Erynnis). Phylogenetic analyses using all available genes (PCGs, rRNAS, and tRNAs) yielded the consensus superfamilial relationships ((((((Bombycoidea + Noctuoidea + Geometroidea) + Pyraloidea) + Papilionoidea) + Tortricoidea) + Yponomeutoidea) + Hepialoidea), confirming the validity of Macroheterocera (Bombycoidea, Noctuoidea, and Geometroidea in this study) and its sister relationship to Pyraloidea. Within Rhopalocera (butterflies and skippers) the familial relationships (Papilionidae + (Hesperiidae + (Pieridae + ((Lycaenidae + Riodinidae) + Nymphalidae)))) were strongly supported in all analyses (0.98–1 by BI and 96–100 by ML methods), rendering invalid the superfamily status for Hesperioidea. On the other hand, current mitogenome-based phylogeny did not find consistent superfamilial relationships among Noctuoidea, Geometroidea, and Bombycoidea and the familial relationships within Bombycoidea between analyses, requiring further taxon sampling in future studies.     

Complete mitochondrial genome sequence of D. littoralis (Diptera: Drosophilidae). Comparative analysis of mitochondrial genomes in the Drosophila virilis group

An analysis of the complete sequence of the mitochondrial genome (mt-genome) of D. littoralis is presented. Its basic characteristics, such as size, nucleotide composition, gene order, and the degree of purifying selection pressure on different parts of the genome are given. The details of the structure of proteinencoding genes and tRNA genes are discussed. The structure of nonencoding regions (control region and intergenic spacers) of mtDNA of the virilis group is given. Fragments of the mt-genes atp6 and cox3 were found in the nuclear genome of D. virilis. The evolutionary history of the mitochondrial and nuclear sequences of these genes indicates that the process of formation of mt-pseudogenes is currently taking place and is associated with the activity of retrotransposons.     

Bacterial evolution: Jittery genomes.

Recent studies of long-term experimental populations of bacteria have revealed the actual progression of evolutionary change and how rates of phenotypic evolution can be decoupled from rates of genomic evolution.     

WWW and the aerobiologist: operating instructions

For several years now, the World Wide Web (WWW) has left the realm of information technology and represents a fundamental everyday working tool for a wide variety of disciplines. Aerobiology, though a newcomer in this virtual space, is proceeding at a fast pace towards the creation of an easily accessible and effective information network. The web gives access to text, imagery, movie and sound with relatively low-cost and user-friendly interfaces conceived as graphical magazines. A practical way to start navigating and looking for information is to operate a ‘search engine’ which is a large database containing addresses on a wide spectrum of subjects. As an alternative, a few selected sites exist that can initialize your search by providing a thematic list of addresses. After leaving the entry ‘port’ you are directed from site to site and eventually end up with a lot more information than you initially thought. Excerpts: information on public and private institutions, access to databases and image catalogs, bibliographical information, overview of monitoring networks, directions on national and international research programs, news (calendar of meetings, courses, etc.). Information is provided for the non-expert user who asks himself the key questions: ‘Where do I start to browse the net?’ or ‘Can I become a provider of information on the net and, if so, is it terribly difficult?’ The idea is that everybody can in principle become a ‘surfer’ or a ‘provider’ dedicating a reasonable amount of time and effort to the task. What one ends up with is an easy-to-use and powerful tool that is already helping the whole aerobiological community to pursue its goals and reach out for necessary interdisciplinary approaches to unsolved scientific issues. The server AEROBIOLOGY INTERNATIONAL (http://www.fisbat.bo.cnr.it/AERO/) is presented as an example on how to proceed with the creation of a new server and its management.