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Genome surfing: using internet-based informatic tools toward functional genetic studies in mouse and humans.

The wealth of databases containing genomic information and the easy access via the internet can be an invaluable tool in performing genetic studies and identifying important sequences. This article provides an overview and specific methods for using these resources in both positional cloning and identifying candidate genes for diseases and phenotypes. The ability to apply information across the mouse and human species is stressed. Useful internet sites and their contents are identified and described, and some understanding of their current limitations is provided. As additional genomic definition accelerates, the use of these tools will become more essential in cutting edge research linking sequence and function in whole mammalian organisms.

Animals↗

Rice bioinformatics. analysis of rice sequence data and leveraging the data to other plant species.

Rice (Oryza sativa) is a model species for monocotyledonous plants, especially for members in the grass family. Several attributes such as small genome size, diploid nature, transformability, and establishment of genetic and molecular resources make it a tractable organism for plant biologists. With an estimated genome size of 430 Mb (Arumuganathan and Earle, 1991), it is feasible to obtain the complete genome sequence of rice using current technologies. An international effort has been established and is in the process of sequencing O. sativa spp. japonica var "Nipponbare" using a bacterial artificial chromosome/P1 artificial chromosome shotgun sequencing strategy. Annotation of the rice genome is performed using prediction-based and homology-based searches to identify genes. Annotation tools such as optimized gene prediction programs are being developed for rice to improve the quality of annotation. Resources are also being developed to leverage the rice genome sequence to partial genome projects such as expressed sequence tag projects, thereby maximizing the output from the rice genome project. To provide a low level of annotation for rice genomic sequences, we have aligned all rice bacterial artificial chromosome/P1 artificial chromosome sequences with The Institute of Genomic Research Gene Indices that are a set of nonredundant transcripts that are generated from nine public plant expressed sequence tag projects (rice, wheat, sorghum, maize, barley, Arabidopsis, tomato, potato, and barrel medic). In addition, we have used data from The Institute of Genomic Research Gene Indices and the Arabidopsis and Rice Genome Projects to identify putative orthologues and paralogues among these nine genomes.

Base Sequence↗

Developmental bioinformatics: linking genetic data to virtual embryos.

This paper discusses current efforts to produce databases of gene expression for the major model embryos used in developmental biology. The efforts to build these resources were motivated by the need for immediate internet access to all types of research data, and the production of these databases is a major and new challenge for bioinformatics. Thus far bioinformatics has mainly been concerned with textually oriented resources and data, much of it concerned with gene and protein sequences. Because the genetic basis of developmental biology is integrated with developmental anatomy, these databases require the use of images to link molecular data with spatial information. In order to standardise database formats, digital atlases of some model systems are being produced that include integrated anatomical descriptions and these are being linked to appropriate genetic data. Integrating such image-based, searchable data into databases makes new demands on the field of bioinformatics and we consider here the imaging modalities that are used to obtain information and we discuss in particular the production of 3D images from serial sections. Next, we consider how to integrate textual and spatial descriptions of gene expression and the key tool needed to make this possible, i.e. anatomical nomenclature. A short review of internet resources on developmental biology is also given and future prospects for the development of these databases are discussed.

Animals↗

Genomic sequencing reveals gene content, genomic organization, and recombination relationships in barley.

Barley (Hordeum vulgare L.) is one of the most important large-genome cereals with extensive genetic resources available in the public sector. Studies of genome organization in barley have been limited primarily to genetic markers and sparse sequence data. Here we report sequence analysis of 417.5 kb DNA from four BAC clones from different genomic locations. Sequences were analyzed with respect to gene content, the arrangement of repetitive sequences and the relationship of gene density to recombination frequencies. Gene densities ranged from 1 gene per 12 kb to 1 gene per 103 kb with an average of 1 gene per 21 kb. In general, genes were organized into islands separated by large blocks of nested retrotransposons. Single genes in apparent isolation were also found. Genes occupied 11% of the total sequence, LTR retrotransposons and other repeated elements accounted for 51.9% and the remaining 37.1% could not be annotated.

Chromosomes, Artificial, Bacterial↗

Trapping parasite secretory proteins in baker's yeast.

Because the function of signal sequences has been conserved during evolution it has been possible to develop both bioinformatics resources to identify them and techniques to clone genes that encode secretory proteins. The latter entail insertion of heterologous signals upstream of signal peptide deleted reporter genes. We discuss the advantages of using Saccharomyces cerevisiae for signal sequence trap technology. The yeast protein-translocation system appears to be less discriminating than that of higher eukaryotes - for example, a Theileria parva cysteine protease gene containing a recessed, nonclassical signal allows access to the secretory pathway--and yeast technology could have general application in studying elements of parasite protein trafficking.

Algorithms↗

Phylogeography of the rock partridge (Alectoris graeca).

We used mitochondrial DNA control-region and microsatellite data to infer the evolutionary history and past demographic changes in 332 rock partridges (Alectoris graeca) sampled from throughout the species' distribution range, with the exception of the central Balkans region. Maternal and biparental DNA markers indicated concordantly that rock partridge populations are structured geographically (mtDNA phiST = 0.86, microsatellite FST = 0.35; RST = 0.31; P < 0.001). Phylogenetic analyses of 22 mtDNA haplotypes identified two major phylogroups (supported by bootstrap values = 93%), splitting partridges from Sicily vs. all the other sampled populations at an average Tamura-Nei genetic distance of 0.035, which corresponds to 65% of the average distance between closely related species of Alectoris. Coalescent estimates of divergence times suggested that rock partridges in Sicily were isolated for more than 200000 years. This deep subdivision was confirmed by multivariate, Bayesian clustering and population assignment analyses of microsatellite genotypes, which supported also a subdivision of partridges from the Alps vs. populations in the Apennines, Albania and Greece. Partridges in the Apennines and Albania-Greece were probably connected by gene flow since recently through a late Pleistocene Adriatic landbridge. Deglaciated Alps were probably colonized by distinct and, perhaps, not yet sampled source populations. Bottleneck and mismatch analyses indicate that rock partridges have lost variability through past population declines, and did not expand recently. Deglaciated areas could have been recolonized without any strong demographic expansion. Genetic data partially supported subspecies subdivisions, and allowed delimiting distinct conservation units. Rock partridges in Sicily, formally recognized as A. g. whitakeri, met the criteria for a distinct evolutionary significant unit.

Animals↗

MAO: a Multiple Alignment Ontology for nucleic acid and protein sequences.

The application of high-throughput techniques such as genomics, proteomics or transcriptomics means that vast amounts of heterogeneous data are now available in the public databases. Bioinformatics is responding to the challenge with new integrated management systems for data collection, validation and analysis. Multiple alignments of genomic and protein sequences provide an ideal environment for the integration of this mass of information. In the context of the sequence family, structural and functional data can be evaluated and propagated from known to unknown sequences. However, effective integration is being hindered by syntactic and semantic differences between the different data resources and the alignment techniques employed. One solution to this problem is the development of an ontology that systematically defines the terms used in a specific domain. Ontologies are used to share data from different resources, to automatically analyse information and to represent domain knowledge for non-experts. Here, we present MAO, a new ontology for multiple alignments of nucleic and protein sequences. MAO is designed to improve interoperation and data sharing between different alignment protocols for the construction of a high quality, reliable multiple alignment in order to facilitate knowledge extraction and the presentation of the most pertinent information to the biologist.

Databases, Genetic↗

Protein databases and software on BIONET.

BIONET provides databases, software, and networking/communications tools to over 2500 molecular biologists worldwide. Software for the analysis of nucleic acid and protein sequence data is provided by both IntelliGenetics and academic contributors. BIONET is currently implementing dedicated high speed servers for searching protein databases, as well as providing more flexible tools for protein structure recognition and prediction. In this review, protein databases and analysis software available on the BIONET resource are described, and progress in providing new tools for structure prediction, comparative sequence analysis, and pattern recognition using Artificial Intelligence (AI) techniques are summarized.

Amino Acid Sequence↗

A genome-based resource for molecular cardiovascular medicine: toward a compendium of cardiovascular genes.

BACKGROUND: Large-scale partial sequencing of cDNA libraries to generate expressed sequence tags (ESTs) is an effective means of discovering novel genes and characterizing transcription patterns in different tissues. To catalogue the identities and expression levels of genes in the cardiovascular system, we initiated large-scale sequencing and analysis of human cardiac cDNA libraries. METHODS AND RESULTS: Using automated DNA sequencing, we generated 43,285 ESTs from human heart cDNA libraries. An additional 41,619 ESTs were retrieved from public databases, for a total of 84,904 ESTs representing more than 26 million nucleotides of raw cDNA sequence data from 13 independent cardiovascular system-based cDNA libraries. Of these, 55% matched to known genes in the Genbank/EMBL/DDBJ databases, 33% matched only to other ESTs, and 12% did not match to any known sequences (designated cardiovascular system-based ESTs, or CVbESTs). ESTs that matched to known genes were classified according to function, allowing for detection of differences in general transcription patterns between various tissues and developmental stages of the cardiovascular system. In silico Northern analysis of known gene matches identified widely expressed cardiovascular genes as well as genes putatively exhibiting greater tissue specificity or developmental stage specificity. More detailed analysis identified 48 genes potentially overexpressed in cardiac hypertrophy, at least 10 of which were previously documented as differentially expressed. Computer-based chromosomal localizations of 1048 cardiac ESTs were performed to further assist in the search for disease-related genes. CONCLUSIONS: These data represent the most extensive compilation of cardiovascular gene expression information to date. They further demonstrate the untapped potential of genome research for investigating questions related to cardiovascular biology and represent a first-generation genome-based resource for molecular cardiovascular medicine.

Blotting, Northern↗

Go!Poly: A gene-oriented polymorphism database.

Human genome polymorphisms play a key role in defining the molecular basis of phenotypic differences between individuals in aspects such as disease susceptibility and drug responses. The database requirements for supporting the study of human genetic variation have been well recognized. In order to meet these needs, several generalized databases have been built. However, it is still hard for users to find gene-related variation data from these huge and sophisticated databases. In its role as a gene-oriented directory of polymorphism data, Go!Poly (Gene Oriented Polymorphism Database; http://61.139.84.5/gopoly/) utilizes two new highly curated and non-redundant resources, LocusLink (http://www.ncbi.nlm.nih.gov/LocusLink/) and RefSeq (http://www.ncbi.nlm.nih.gov/LocusLink/refseq.html), as the standard for identifying and positioning nucleotide variations. As a generalized polymorphism database, Go!Poly extracts human gene-linked sequence variations of all common types (SNP, insertion-deletion, simple tandem repeat, and complex nucleotides variations) from various public resources including scientific journals and internet resources, such as HGBASE (http://hgbase.cgr.ki.se) and dbSNP (http://www.ncbi.nlm.nih.gov/SNP/). The polymorphism data are then categorized into different gene loci, and the reference sequences given by LocusLink are used as positioning references. Through close integration with LocusLink, Go!Poly also provides facilitated connections among sequence data, gene name, and related biological information. This feature also makes Go!Poly easy to search and navigate. Future automated annotations and internal consistency checking may also benefit from this. Extensive efforts are being taken to make the polymorphism information generated by the Chinese scientific community available from this resource.

China↗

Analysis of the genetic diversity and the phylogenetic evolution of Chinese sheep based on Cyt b gene sequences.

The complete sequences of Cyt b gene from 20 individuals belonging to eight Chinese indigenous sheep breeds and one foreign breed were studied. The results showed that the hapolotype diversity of Chinese sheep breeds was 97.1%. The mean nucleotide composition of all the sequences was 27.1% T, 28.5% C, 31.4% A, and 13.0% G. The nucleotide diversity was 0.602%. A total of 43 mutation sites were detected, including 40 transitions and 3 transversions. Fu's test of selective neutrality showed that the sheep populations had no population demographic expansion (0.10 >P > 0.05). The different clustering methods, namely neighbor-joining, minimum evolution, and unweighted pair group method with arithmetic means, all showed a similar result, which indicated that Chinese local sheep had three maternal resources.

Animals↗

[Identification of bacteria through 16S rRNA sequencing: principles, methods and applications in clinical microbiology].

Phylogenetic relationships among prokaryotes can be inferred from comparisons of their 16S rRNA (or 16S rDNA) sequences. This has had an enormous repercussion on bacterial taxonomy, leading to the currently applied system of classification, and allowing a rapid and precise identification of bacteria. In clinical microbiology, molecular identification based on 16S rDNA sequencing is applied fundamentally to bacteria whose identification by means of other types of techniques turns out impossible, difficult, or requires a lot of time. Amplification of the gene to be sequenced uses preferably DNA extracted from a bacterial pure culture, but can be achieved also directly from a clinical sample. The latter has led to the discovery of new pathogens. Bearing in mind its potential, as the technical resources improve and the prize becomes more competitive, the identification based on 16S rDNA sequencing will certainly find a wider application in the clinical microbiology laboratory.

DNA Primers↗

Odorant receptor expressed sequence tags demonstrate olfactory expression of over 400 genes, extensive alternate splicing and unequal expression levels.

BACKGROUND: The olfactory receptor gene family is one of the largest in the mammalian genome. Previous computational analyses have identified approximately 1,500 mouse olfactory receptors, but experimental evidence confirming olfactory function is available for very few olfactory receptors. We therefore screened a mouse olfactory epithelium cDNA library to obtain olfactory receptor expressed sequence tags, providing evidence of olfactory function for many additional olfactory receptors, as well as identifying gene structure and putative promoter regions. RESULTS: We identified more than 1,200 odorant receptor cDNAs representing more than 400 genes. Using real-time PCR to confirm expression level differences suggested by our screen, we find that transcript levels in the olfactory epithelium can differ between olfactory receptors by up to 300-fold. Differences for one gene pair are apparently due to both unequal numbers of expressing cells and unequal transcript levels per expressing cell. At least two-thirds of olfactory receptors exhibit multiple transcriptional variants, with alternative isoforms of both 5' and 3' untranslated regions. Some transcripts (5%) utilize splice sites within the coding region, contrary to the stereotyped olfactory receptor gene structure. Most atypical transcripts encode nonfunctional olfactory receptors, but can occasionally increase receptor diversity. CONCLUSIONS: Our cDNA collection confirms olfactory function of over one-third of the intact mouse olfactory receptors. Most of these genes were previously annotated as olfactory receptors based solely on sequence similarity. Our finding that different olfactory receptors have different expression levels is intriguing given the one-neuron, one-gene expression regime of olfactory receptors. We provide 5' untranslated region sequences and candidate promoter regions for more than 300 olfactory receptors, valuable resources for computational regulatory motif searches and for designing olfactory receptor microarrays and other experimental probes.

Alternative Splicing↗

Population structure of loggerhead shrikes in the California Channel Islands.

The loggerhead shrike (Lanius ludovicianus), a songbird that hunts like a small raptor, maintains breeding populations on seven of the eight California Channel Islands. One of the two subspecies, L. l. anthonyi, was described as having breeding populations on six of the islands while a second subspecies, L. l. mearnsi, was described as being endemic to San Clemente Island. Previous genetic studies have demonstrated that the San Clemente Island loggerhead shrike is well differentiated genetically from both L. l. anthonyi and mainland populations, despite the fact that birds from outside the population are regular visitors to the island. Those studies, however, did not include a comparison between San Clemente Island shrikes and the breeding population on Santa Catalina Island, the closest island to San Clemente. Here we use mitochondrial control region sequences and nuclear microsatellites to investigate the population structure of loggerhead shrikes in the Channel Islands. We confirm the genetic distinctiveness of the San Clemente Island loggerhead shrike and, using Bayesian clustering analysis, demonstrate the presence and infer the source of the nonbreeding visitors. Our results indicate that Channel Island loggerhead shrikes comprise three distinct genetic clusters that inhabit: (i) San Clemente Island, (ii) Santa Catalina Island and (iii) the Northern Channel Islands and nearby mainland; they do not support a recent suggestion that all Channel Island loggerhead shrikes should be managed as a single entity.

Animals↗

Strategic grouping in the spatial span memory task.

Spatial short-term memory performance was examined in relation to participants' strategies. A total of 20 adult participants viewed and reproduced sequences of locations that varied in length (five, six, seven, or eight locations) and spatial separability (a manipulation of the configurations). In trial-by-trial self-reports, participants described five types of strategies. Chunking the spatial sequences into groups of three or four locations was the sole strategy associated with increased accuracy. Participants demonstrated considerable variability in the strategies that they selected, suggesting that cognitive resources are allocated to strategy selection, execution, and monitoring in the spatial span task. Spatially separable sequences were more accurately recalled than nonseparable sequences, independent of strategic grouping, suggesting two levels of grouping in the spatial span task.

Adult↗

New generation pharmacogenomic tools: a SNP linkage disequilibrium Map, validated SNP assay resource, and high-throughput instrumentation system for large-scale genetic studies.

Since public and private efforts announced the first draft of the human genome last year, researchers have reported great numbers of single nucleotide polymorphisms (SNPs). We believe that the availability of well-mapped, quality SNP markers constitutes the gateway to a revolution in genetics and personalized medicine that will lead to better diagnosis and treatment of common complex disorders. A new generation of tools and public SNP resources for pharmacogenomic and genetic studies--specifically for candidate-gene, candidate-region, and whole-genome association studies--will form part of the new scientific landscape. This will only be possible through the greater accessibility of SNP resources and superior high-throughput instrumentation-assay systems that enable affordable, highly productive large-scale genetic studies. We are contributing to this effort by developing a high-quality linkage disequilibrium SNP marker map and an accompanying set of ready-to-use, validated SNP assays across every gene in the human genome. This effort incorporates both the public sequence and SNP data sources, and Celera Genomics' human genome assembly and enormous resource ofphysically mapped SNPs (approximately 4,000,000 unique records). This article discusses our approach and methodology for designing the map, choosing quality SNPs, designing and validating these assays, and obtaining population frequency ofthe polymorphisms. We also discuss an advanced, high-performance SNP assay chemisty--a new generation of the TaqMan probe-based, 5' nuclease assay-and high-throughput instrumentation-software system for large-scale genotyping. We provide the new SNP map and validation information, validated SNP assays and reagents, and instrumentation systems as a novel resource for genetic discoveries.

Alleles↗

BayGenomics: a resource of insertional mutations in mouse embryonic stem cells.

The BayGenomics gene-trap resource (http://baygenomics.ucsf.edu) provides researchers with access to thousands of mouse embryonic stem (ES) cell lines harboring characterized insertional mutations in both known and novel genes. Each cell line contains an insertional mutation in a specific gene. The identity of the gene that has been interrupted can be determined from a DNA sequence tag. Approximately 75% of our cell lines contain insertional mutations in known mouse genes or genes that share strong sequence similarities with genes that have been identified in other organisms. These cell lines readily transmit the mutation to the germline of mice and many mutant lines of mice have already been generated from this resource. BayGenomics provides facile access to our entire database, including sequence tags for each mutant ES cell line, through the World Wide Web. Investigators can browse our resource, search for specific entries, download any portion of our database and BLAST sequences of interest against our entire set of cell line sequence tags. They can then obtain the mutant ES cell line for the purpose of generating knockout mice.

Animals↗

Barley disease resistance gene analogs of the NBS-LRR class: identification and mapping.

The majority of verified plant disease resistance genes isolated to date are of the NBS-LRR class, encoding proteins with a predicted nucleotide binding site (NBS) and a leucine-rich repeat (LRR) region. We took advantage of the sequence conservation in the NBS motif to clone, by PCR, gene fragments from barley representing putative disease resistance genes of this class. Over 30 different resistance gene analogs (RGAs) were isolated from the barley cultivar Regatta. These were grouped into 13 classes based on DNA sequence similarity. Actively transcribed genes were identified from all classes but one, and cDNA clones were isolated to derive the complete NBS-LRR protein sequences. Some of the NBS-LRR genes exhibited variation with respect to whether and where particular introns were spliced, as well as frequent premature polyadenylation. DNA sequences related to the majority of the barley RGAs were identified in the recently expanded public rice genomic sequence database, indicating that the rice sequence can be used to extract a large proportion of the RGAs from barley and other cereals. Using a combination of RFLP and PCR marker techniques, representatives of all barley RGA gene classes were mapped in the barley genome, to all chromosomes except 4H. A number of the RGA loci map in the vicinity of known disease resistance loci, and the association between RGA S-120 and the nematode resistance locus Ha2 on chromosome 2H was further tested by co-segregation analysis. Most of the RGA sequences reported here have not been described previously, and represent a useful resource as candidates or molecular markers for disease resistance genes in barley and other cereals.

Amino Acid Sequence↗