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TAC-1, a regulator of microtubule length in the C. elegans embryo.

Regulation of microtubule growth is critical for many cellular processes, including meiosis, mitosis, and nuclear migration. We carried out a genome-wide RNAi screen in Caenorhabditis elegans to identify genes required for pronuclear migration, one of the first events in embryogenesis requiring microtubules. Among these, we identified and characterized tac-1 a new member of the TACC (Transforming Acidic Coiled-Coil) family [1]. tac-1(RNAi) embryos exhibit very short microtubules nucleated from the centrosomes as well as short spindles. TAC-1 is initially enriched at the meiotic spindle poles and is later recruited to the sperm centrosome. TAC-1 localization at the centrosomes is regulated during the cell cycle, with high levels during mitosis and a reduction during interphase, and is dependent on aurora kinase 1 (AIR-1), a protein involved in centrosome maturation. tac-1(RNAi) embryos resemble mutants of zyg-9, which encodes a previously characterized centrosomal protein of the XMAP215 family and was also found in our screen. We show that TAC-1 and ZYG-9 are dependent on one another for their localization at the centrosome, and this dependence suggests that they may function together as a complex. We conclude that TAC-1 is a major regulator of microtubule length in the C. elegans embryo.

Animals↗

Combination of 'omics' data to investigate the mechanism(s) of hydrazine-induced hepatotoxicity in rats and to identify potential biomarkers.

To gain novel insight into the molecular mechanisms underlying hydrazine-induced hepatotoxicity, mRNAs, proteins and endogenous metabolites were identified that were altered in rats treated with hydrazine compared with untreated controls. These changes were resolved in a combined genomics, proteomics and metabonomics study. Sprague-Dawley rats were assigned to three treatment groups with 10 animals per group and given a single oral dose of vehicle, 30 or 90 mg kg(-1) hydrazine, respectively. RNA was extracted from rat liver 48 h post-dosing and transcribed into cDNA. The abundance of mRNA was investigated on cDNA microarrays containing 699 rat-specific genes involved in toxic responses. In addition, proteins from rat liver samples (48 and 120/168 h post-dosing) were resolved by two-dimensional differential gel electrophoresis and proteins with changed expression levels after hydrazine treatment were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry peptide mass fingerprinting. To elucidate how regulation was reflected in biochemical pathways, endogenous metabolites were measured in serum samples collected 48 h post-dosing by 600-MHz 1H-NMR. In summary, a single dose of hydrazine caused gene, protein and metabolite changes, which can be related to glucose metabolism, lipid metabolism and oxidative stress. These findings support known effects of hydrazine toxicity and provide potential new biomarkers of hydrazine-induced toxicity.

Animals↗

Comparative integromics on BMP/GDF family.

WNT, Notch, FGF, Hedgehog and BMP signaling pathways network together during embryogenesis, tissue regeneration, and carcinogenesis. BMP2, BMP3, BMP4, BMP5, BMP6, BMP7, BMP8A, BMP8B, BMP10, BMP15, AMH, GDF1, GDF2, GDF3, GDF5, GDF6, GDF7, GDF8, GDF9, GDF10, GDF11, and GDF15 are BMP/GDF family genes within the human genome; however, transcriptional regulation of BMP/GDF family members by the canonical WNT signaling pathway remains unclear. We searched for the TCF/LEF-binding site within the promoter region of BMP/GDF family genes by using bioinformatics and human intelligence. Because four TCF/LEF-binding sites were identified within human GDF10 promoter, comparative genomics analyses on GDF10 orthologs were further performed. Chimpanzee GDF10 gene, encoding a 477-amino-acid protein, was identified within NW_112875.1 genome sequence. AY412135.1 was not the correct coding sequence for chimpanzee GDF10. Chimpanzee GDF10 showed 99.2%, 83.2% and 47.4% total amino-acid identity with human GDF10, mouse Gdf10 and human BMP3, respectively. RASGEF1A-GDF10-PRKG1 locus at human chromosome 10q11 and BMP3-PRKG2-RASGEF1B locus at human chromosome 4q21 were paralogous regions with insertions/deletions and recombination. Human GDF10 mRNA was expressed in fetal cochlea, fetal lung, testis, retina, pineal gland, other neural tissues, head and neck tumors, while mouse Gdf10 mRNA was expressed in fetal liver, inner ear, cerebellum, other neural tissues, prostate and blood vessels. Four TCF/LEF-binding sites in human GDF10 promoter were conserved in chimpanzee GDF10 promoter, but not in the mouse Gdf10 promoter; however, another TCF/LEF-binding site occurred in mouse Gdf10 promoter. Four bHLH-binding sites in human GDF10 promoter were conserved in chimpanzee GDF10 promoter, but only one in mouse Gdf10 promoter. Primate GDF10 promoters were divergent from mouse Gdf10 promoter. Because GDF10 was characterized as a potential target of canonical WNT signaling pathway in neural tissues, GDF10 is one of the targets of systems medicine, especially in the field of regenerative medicine.

Amino Acid Sequence↗

Effective analysis of genomic data.

High-throughput biotechnology has enabled genome-wide investigation of gene expression and has the potential to identify genes that have a role to play in focal cerebral ischemia, as well as many other interventions. The advent of this technology has also led to the generation of large amounts of expensive and complex expression data. One of the major problems with the generation of so much data is locating and extracting the relevant information to aid target identification and interpretation effectively and reliably. Statistical involvement is vital. Not only does it help to ensure effective extraction of information from the data, it also increases the likelihood that the data collected will embody the information about the differential expression of interest in the first place. The goal of this chapter is to recommend an effective process for investigating gene expression data. There are five stages in this process that we believe lead to reliable results when routinely applied to an expression dataset, once it has been appropriately generated and collected: (1) biological problem definition and design selection; (2) data examination, "preprocessing," and reexamination; (3) data analysis step I: screening for differentially expressed genes; (4) data analysis step II: verifying differential expression; and (5) biological verification, interpretation, and communication.

Computational Biology↗

Functional genomics of the cilium, a sensory organelle.

Cilia and flagella play important roles in many physiological processes, including cell and fluid movement, sensory perception, and development. The biogenesis and maintenance of cilia depend on intraflagellar transport (IFT), a motility process that operates bidirectionally along the ciliary axoneme. Disruption in IFT and cilia function causes several human disorders, including polycystic kidneys, retinal dystrophy, neurosensory impairment, and Bardet-Biedl syndrome (BBS). To uncover new ciliary components, including IFT proteins, we compared C. elegans ciliated neuronal and nonciliated cells through serial analysis of gene expression (SAGE) and screened for genes potentially regulated by the ciliogenic transcription factor, DAF-19. Using these complementary approaches, we identified numerous candidate ciliary genes and confirmed the ciliated-cell-specific expression of 14 novel genes. One of these, C27H5.7a, encodes a ciliary protein that undergoes IFT. As with other IFT proteins, its ciliary localization and transport is disrupted by mutations in IFT and bbs genes. Furthermore, we demonstrate that the ciliary structural defect of C. elegans dyf-13(mn396) mutants is caused by a mutation in C27H5.7a. Together, our findings help define a ciliary transcriptome and suggest that DYF-13, an evolutionarily conserved protein, is a novel core IFT component required for cilia function.

Animals↗

Subtyping of Mycoplasma pneumoniae isolates based on extended genome sequencing and on expression profiles.

Mycoplasma pneumoniae isolates from patients, collected over a period of 12 years in Germany, were characterized by various methods (parameters) including multilocus sequence typing, restriction fragment length polymorphisms, Western blotting with mono-specific antibodies directed against selected proteins or with polyspecific antibodies directed against the Triton X-114-soluble protein fraction, and two-dimensional gel electrophoresis. The results for 91 isolates from Germany, which were complemented with 14 isolates from the USA and 10 isolates from France, clearly showed that M. pneumoniae is a highly uniform species and that most of the isolates could be assigned to one of the two subtypes 1 and 2. The members of one subtype differ from the other with respect to the sequence of the P1 gene, the ORF6 gene, the P65 gene, and by a typical DNA restriction fragment pattern. We observed four isolates (variants), which seemed identical by the above mentioned criteria, but did not belong to either one of the two subtypes. They showed most of the subtype 2-specific features, but differed in the sequence of the P1 gene and showed a variation in the restriction fragment pattern. The appearance of subtype 1 or 2 over the last 12 years in Germany showed a dominance of subtype 1 between 1989 and 1996 and a dominance of subtype 2 between 1997 and 1998. The variant (neither subtype 1 nor subtype 2) was only detected in 1991 and 1995 but it had no epidemiological consequences.

Adhesins, Bacterial↗

Effects of the pesticide thiuram: genome-wide screening of indicator genes by yeast DNA microarray.

Although there have been studies on the toxicity of the pesticide thiuram, the present study is the first one to attempt to integrate a whole genomic response using microarray technology. From the DNA microarray experiment it was found that exposure to thiuram led to alterations of gene expression in yeast cells and that many genes involved in detoxification and stress response were highly induced. The induced genes were classified according to the MIPS yeast database. The induction of genes concerned with folding and proteolysis reflects the protein denaturing and degradation effects of the thiuram treatment The induction of genes involved in redox and defense against reaction oxygen species also suggests that thiuram has other effects, such as oxidative stress. Genes classified for carbohydrate metabolism and energy were also highly induced, and these gene products may play the role of providing the energy for the detoxification mechanism. In addition, in view of the induction of some genes involved in DNA repair, thiuram potentially causes DNA damage. Therefore, as stated in previous reports, thiuram is a potential positive toxic chemical. On the other hand, YKL071W, YCR102C, YLR303W, and YLL057C were selected based on the result of a DNA microarray experiment and used for the promoter activity assay. Thiuram treatment affected the promoter of these genes, indicating that this technique could be used for the selection of biomarker candidates.

Biomarkers↗

Development of an integrated laboratory information management system for the maize mapping project.

MOTIVATION: The development of an integrated genetic and physical map for the maize genome involves the generation of an enormous amount of data. Managing this data requires a system to aid in genotype scoring for different types of markers coming from both local and remote users. In addition, researchers need an efficient way to interact with genetic mapping software and with data files from automated DNA sequencing. They also need ways to manage primer data for mapping and sequencing and provide views of the integrated physical and genetic map and views of genetic map comparisons. RESULTS: The MMP-LIMS system has been used successfully in a high-throughput mapping environment. The genotypes from 957 SSR, 1023 RFLP, 189 SNP, and 177 InDel markers have been entered and verified via MMP-LIMS. The system is flexible, and can be easily modified to manage data for other species. The software is freely available. AVAILABILITY: To receive a copy of the iMap or cMap software, please fill out the form on our website. The other MMP-LIMS software is freely available at http://www.maizemap.org/bioinformatics.htm.

Chromosome Mapping↗

Reprogramming of the human atrial transcriptome in permanent atrial fibrillation: expression of a ventricular-like genomic signature.

Atrial fibrillation is associated with increased expression of ventricular myosin isoforms in atrial myocardium, regarded as part of a dedifferentiation process. Whether reexpression of ventricular isoforms in atrial fibrillation is restricted to transcripts encoding for contractile proteins is unknown. Therefore, this study compares atrial mRNA expression in patients with permanent atrial fibrillation to atrial mRNA expression in patients with sinus rhythm and to ventricular gene expression using Affymetrix U133 arrays. In atrial myocardium, we identified 1434 genes deregulated in atrial fibrillation, the majority of which, including key elements of calcium-dependent signaling pathways, displayed downregulation. Functional classification based on Gene Ontology provided the specific gene sets of the interdependent processes of structural, contractile, and electrophysiological remodeling. In addition, we demonstrate for the first time a prominent upregulation of transcripts involved in metabolic activities, suggesting an adaptive response to increased metabolic demand in fibrillating atrial myocardium. Ventricular-predominant genes were 5 times more likely to be upregulated in atrial fibrillation (174 genes upregulated, 35 genes downregulated), whereas atrial-specific transcripts were predominantly downregulated (56 genes upregulated, 564 genes downregulated). Overall, in fibrillating atrial myocardium, functional classes of genes characteristic of ventricular myocardium were found to be upregulated (eg, metabolic processes), whereas functional classes predominantly expressed in atrial myocardium were downregulated (eg, signal transduction and cell communication). Therefore, dedifferentiation with adoption of a ventricular-like signature is a general feature of the fibrillating atrium.

Atrial Fibrillation↗

Genome analyses of Streptomyces peucetius ATCC 27952 for the identification and comparison of cytochrome P450 complement with other Streptomyces.

We have determined the genome sequence of 8.7 Mb chromosome of Streptomyces peucetius ATCC 27952, which produces clinically important anthracycline chemotherapeutic agents of the polyketide class of antibiotics, daunorubicin and doxorubicin. The cytochrome P450 (CYP) superfamily is represented by 19 sequences in the S. peucetius. Among those, 15 code for functional genes, whereas the remaining four are pseudo genes. CYPs from S. peucetius are phylogenetically close to those of Streptomyces amermitilis. Four CYPs are associated with modular PKS of avermectin and two with doxorubicin biosynthetic gene cluster. CYP252A1 is the new family found in S. peucetius, which shares 38% identity to CYP51 from Streptomyces coelicolor A3 (2). Nine CYPs from S. peucetius are found in the cluster containing various regulatory genes including rar operon, conserved in S. coelicolor A3 (2) and Streptomyces griseus. Although two ferredoxins and four ferredoxin reductases have been identified so far, only one ferredoxin reductase was found in the cluster of CYP147F1 in S. peucetius. To date, 174 CYPs have been described from 45 Streptomyces species in all searchable databases. However, only 18 CYPs are clustered with ferredoxin. The comparative study of cytochrome P450s, ferredoxins, and ferredoxin reductases should be useful for the future development and manipulation of antibiotic biosynthetic pathways.

Amino Acid Sequence↗

ExpressYourself: A modular platform for processing and visualizing microarray data.

DNA microarrays are widely used in biological research; by analyzing differential hybridization on a single microarray slide, one can detect changes in mRNA expression levels, increases in DNA copy numbers and the location of transcription factor binding sites on a genomic scale. Having performed the experiments, the major challenge is to process large, noisy datasets in order to identify the specific array elements that are significantly differentially hybridized. This normally requires aggregating different, often incompatible programs into a multi-step pipeline. Here we present ExpressYourself, a fully integrated platform for processing microarray data. In completely automated fashion, it will correct the background array signal, normalize the Cy5 and Cy3 signals, score levels of differential hybridization, combine the results of replicate experiments, filter problematic regions of the array and assess the quality of individual and replicate experiments. ExpressYourself is designed with a highly modular architecture so various types of microarray analysis algorithms can readily be incorporated as they are developed; for example, the system currently implements several normalization methods, including those that simultaneously consider signal intensity and slide location. The processed data are presented using a web-based graphical interface to facilitate comparison with the original images of the array slides. In particular, Express Yourself is able to regenerate images of the original microarray after applying various steps of processing, which greatly facilities identification of position-specific artifacts. The program is freely available for use at http://bioinfo.mbb.yale.edu/expressyourself.

Algorithms↗

Theme discovery from gene lists for identification and viewing of multiple functional groups.

BACKGROUND: High throughput methods of the genome era produce vast amounts of data in the form of gene lists. These lists are large and difficult to interpret without advanced computational or bioinformatic tools. Most existing methods analyse a gene list as a single entity although it is comprised of multiple gene groups associated with separate biological functions. Therefore it is imperative to define and visualize gene groups with unique functionality within gene lists. RESULTS: In order to analyse the functional heterogeneity within a gene list, we have developed a method that clusters genes to groups with homogenous functionalities. The method uses Non-negative Matrix Factorization (NMF) to create several clustering results with varying numbers of clusters. The obtained clustering results are combined into a simple graphical presentation showing the functional groups over-represented in the analyzed gene list. We demonstrate its performance on two data sets and show results that improve upon existing methods. The comparison also shows that our method creates a more simplified view that aids in discovery of biological themes within the list and discards less informative classes from the results. CONCLUSION: The presented method and associated software are useful for the identification and interpretation of biological functions associated with gene lists and are especially useful for the analysis of large lists.

Cluster Analysis↗

Visualizing information across multidimensional post-genomic structured and textual databases.

MOTIVATION: Visualizing relationships among biological information to facilitate understanding is crucial to biological research during the post-genomic era. Although different systems have been developed to view gene-phenotype relationships for specific databases, very few have been designed specifically as a general flexible tool for visualizing multidimensional genotypic and phenotypic information together. Our goal is to develop a method for visualizing multidimensional genotypic and phenotypic information and a model that unifies different biological databases in order to present the integrated knowledge using a uniform interface. RESULTS: We developed a novel, flexible and generalizable visualization tool, called PhenoGenesviewer (PGviewer), which in this paper was used to display gene-phenotype relationships from a human-curated database (OMIM) and from an automatic method using a Natural Language Processing tool called BioMedLEE. Data obtained from multiple databases were first integrated into a uniform structure and then organized by PGviewer. PGviewer provides a flexible query interface that allows dynamic selection and ordering of any desired dimension in the databases. Based on users' queries, results can be visualized using hierarchical expandable trees that present views specified by users according to their research interests. We believe that this method, which allows users to dynamically organize and visualize multiple dimensions, is a potentially powerful and promising tool that should substantially facilitate biological research. AVAILABILITY: PhenogenesViewer as well as its support and tutorial are available at http://www.dbmi.columbia.edu/pgviewer/ CONTACT: Lussier@dbmi.columbia.edu.

Computer Graphics↗

High-throughput classification of yeast mutants for functional genomics using metabolic footprinting.

Many technologies have been developed to help explain the function of genes discovered by systematic genome sequencing. At present, transcriptome and proteome studies dominate large-scale functional analysis strategies. Yet the metabolome, because it is 'downstream', should show greater effects of genetic or physiological changes and thus should be much closer to the phenotype of the organism. We earlier presented a functional analysis strategy that used metabolic fingerprinting to reveal the phenotype of silent mutations of yeast genes. However, this is difficult to scale up for high-throughput screening. Here we present an alternative that has the required throughput (2 min per sample). This 'metabolic footprinting' approach recognizes the significance of 'overflow metabolism' in appropriate media. Measuring intracellular metabolites is time-consuming and subject to technical difficulties caused by the rapid turnover of intracellular metabolites and the need to quench metabolism and separate metabolites from the extracellular space. We therefore focused instead on direct, noninvasive, mass spectrometric monitoring of extracellular metabolites in spent culture medium. Metabolic footprinting can distinguish between different physiological states of wild-type yeast and between yeast single-gene deletion mutants even from related areas of metabolism. By using appropriate clustering and machine learning techniques, the latter based on genetic programming, we show that metabolic footprinting is an effective method to classify 'unknown' mutants by genetic defect.

Cells, Cultured↗

MARS: microarray analysis, retrieval, and storage system.

BACKGROUND: Microarray analysis has become a widely used technique for the study of gene-expression patterns on a genomic scale. As more and more laboratories are adopting microarray technology, there is a need for powerful and easy to use microarray databases facilitating array fabrication, labeling, hybridization, and data analysis. The wealth of data generated by this high throughput approach renders adequate database and analysis tools crucial for the pursuit of insights into the transcriptomic behavior of cells. RESULTS: MARS (Microarray Analysis and Retrieval System) provides a comprehensive MIAME supportive suite for storing, retrieving, and analyzing multi color microarray data. The system comprises a laboratory information management system (LIMS), a quality control management, as well as a sophisticated user management system. MARS is fully integrated into an analytical pipeline of microarray image analysis, normalization, gene expression clustering, and mapping of gene expression data onto biological pathways. The incorporation of ontologies and the use of MAGE-ML enables an export of studies stored in MARS to public repositories and other databases accepting these documents. CONCLUSION: We have developed an integrated system tailored to serve the specific needs of microarray based research projects using a unique fusion of Web based and standalone applications connected to the latest J2EE application server technology. The presented system is freely available for academic and non-profit institutions. More information can be found at http://genome.tugraz.at.

Algorithms↗

Genome analysis and functional characterization of the E2 and RING-type E3 ligase ubiquitination enzymes of Arabidopsis.

Attachment of ubiquitin to substrate proteins is catalyzed by the three enzymes E1, E2 (ubiquitin conjugating [UBC]), and E3 (ubiquitin ligase). Forty-one functional proteins with a UBC domain and active-site cysteine are predicted in the Arabidopsis (Arabidopsis thaliana) genome, which includes four that are predicted or shown to function with ubiquitin-like proteins. Only nine were previously characterized biochemically as ubiquitin E2s. We obtained soluble protein for 22 of the 28 uncharacterized UBCs after expression in Escherichia coli and demonstrated that 16 function as ubiquitin E2s. Twelve, plus three previously characterized ubiquitin E2s, were also tested for the ability to catalyze ubiquitination in vitro in the presence of one of 65 really interesting new gene (RING) E3 ligases. UBC22, UBC19-20, and UBC1-6 had variable levels of E3-independent activity. Six UBCs were inactive with all RINGs tested. Closely related UBC8, 10, 11, and 28 were active with the largest number of RING E3s and with all RING types. Expression analysis was performed to determine whether E2s or E3s were expressed in specific organs or under specific environmental conditions. Closely related E2s show unique patterns of expression and most express ubiquitously. Some RING E3s are also ubiquitously expressed; however, others show organ-specific expression. Of all the organs tested, RING mRNAs are most abundant in floral organs. This study demonstrates that E2 diversity includes examples with broad and narrow specificity toward RINGs, and that most ubiquitin E2s are broadly expressed with each having a unique spatial and developmental pattern of expression.

Arabidopsis↗

Rapid evolution of a recently retroposed transcription factor YY2 in mammalian genomes.

YY2 was originally identified due to its unusual similarity to the evolutionarily well-conserved zinc finger gene YY1. In this study, we have determined the evolutionary origin and conservation of YY2 using comparative genomic approaches. Our results indicate that YY2 is a retroposed copy of YY1 that has been inserted into another gene locus named Mbtps2 (membrane-bound transcription factor protease site 2). This retroposition is estimated to have occurred after the divergence of placental mammals from other vertebrates based on the detection of YY2 only in the placental mammals. The N- and C-terminal regions of YY2 have evolved under different selection pressures. The N-terminal region has evolved at a very fast pace with very limited functional constraints, whereas the DNA-binding, C-terminal region still maintains a sequence structure very similar to that of YY1 and is also well conserved among placental mammals. In situ hybridizations using different adult mouse tissues indicate that mouse YY2 is expressed at relatively low levels in Purkinje and granular cells of cerebellum and in neuronal cells of cerebrum, but at very high levels in testis. The expression levels of YY2 are much lower than those of YY1, but the overall spatial expression patterns are similar to those of Mbtps2, suggesting a possible shared transcriptional control between YY2 and Mbtps2. Taken together, the formation and evolution of YY2 represent a very unusual case where a transcription factor was first retroposed into another gene locus encoding a protease and survived with different selection schemes and expression patterns.

Amino Acid Sequence↗

From transcriptomics to bibliomics.

BACKGROUND: Current biological investigations tend to operate with genomes, instead of genes as during the last century. It is possible to compare entire genomes, transcriptomes or proteomes, using alphanumeric data corresponding to the differential expression levels of thousands of genes. What remains difficult is to link array results to factual or bibliographical data and retrieve information that is highly structured and - in Shannon's sense - rare. MATERIAL/METHODS: We have developed a tool, Documentation and Information LIBrary (DILIB), that enables us to retrieve, organize and analyze huge amounts of data available on the Internet and related to microarray experiments. DILIB can link hundreds of differentially expressed genes - through their Single Identifier or GenBank accession number - to hundreds of Medline records, and can retrieve, analyze, and compare automatically thousands of non-trivial descriptors related to gene clusters. RESULTS: As exemplified with frequency comparison of MEdical Subject Headings and Registry Number descriptors, we reanalyzed the involvement of 'integrin', 'interleukin' and 'CD Antigens' in mesotheliomas. Thus, DILIB allowed us to: (i). associate literature to expressed genes, (ii). link functional transcriptomes in various experiments, (iii). associate specific descriptors to experiments, (iv). define new research areas, and eventually (v). find new functions for co-expressed genes. CONCLUSIONS: We propose a new concept, 'bibliomics', representing a subset of high quality and rare information, retrieved and organized by systematic literature-searching tools from existing databases, and related to a subset of genes functioning together in '-omic' sciences.

Databases, Genetic↗