Biomedical subjects

Folker Meyer

Publications and source records attributed to Folker Meyer.

29 records · Page 2Linked to original sources

PubMed2004

Comparing expression level-dependent features in codon usage with protein abundance: an analysis of 'predictive proteomics'.

Synonymous codon usage is a commonly used means for estimating gene expression levels of Escherichia coli genes and has also been used for predicting highly expressed genes for a number of prokaryotic genomes. By comparison of expression level-dependent features in codon usage with protein abundance data from two proteome studies of exponentially growing E. coli and Bacillus subtilis cells, we try to evaluate whether the implicit assumption of this approach can be confirmed with experimental data. Log-odds ratio scores are used to model differences in codon usage between highly expressed genes and genomic average. Using these, the strength and significance of expression level-dependent features in codon usage were determined for the genes of the Escherichia coli, Bacillus subtilis and Haemophilus influenzae genomes. The comparison of codon usage features with protein abundance data confirmed a relationship between these to be present, although exceptions to this, possibly related to functional context, were found. For species with expression level-dependent features in their codon usage, the applied methodology could be used to improve in silico simulations of the outcome of two-dimensional gel electrophoretic experiments.

Animals↗

PubMed2003

Construction and validation of a Sinorhizobium meliloti whole genome DNA microarray: genome-wide profiling of osmoadaptive gene expression.

Based on the complete Sinorhizobium meliloti genome sequence we established DNA microarrays as a comprehensive tool for systematic genome-wide gene expression analysis in S. meliloti 1021. For these PCR fragment-based microarrays, called Sm6kPCR, a collection of probes for the 6207 predicted protein-coding genes consisting of 6046 gene-specific PCR fragments and 161 70 mer oligonucleotides was arrayed in high density on glass slides. To obtain these PCR fragments primer pairs were designed to amplify internal gene-specific DNA fragments of 80-350 bp. Additionally, these primers were characterized by a 5' extension that allowed for reamplification using standard primers after the first amplification employing the specific primers. In order to ascertain the quality of the Sm6kPCR microarrays and to validate gene expression studies in S. meliloti parallel hybridizations based on RNA samples obtained from cells cultured under identical conditions were performed. In addition, gene expression in S. meliloti in response to an osmotic upshift imposed by the addition of 0.38 M NaCl was monitored. 137 genes were identified showing significant changes in gene expression resulting from the osmotic upshift. From these genes 52 were induced and 85 genes were repressed. Among the genes displaying different RNA levels some functional groups could be identified that are particularly remarkable. Repression was observed for 8 genes related to motility and chemotaxis, 7 genes encoding amino acid biosynthesis enzymes and 15 genes involved in iron uptake whereas 14 genes involved in transport of small molecules and 4 genes related to polysaccharide biosynthesis were induced.

Chromosome Mapping↗

PubMed2003

Building a BRIDGE for the integration of heterogeneous data from functional genomics into a platform for systems biology.

The flood of data acquired from the increasing number of publicly available genomes has led to new demands for bioinformatics software. With the growing amount of information resulting from high throughput experiments new questions arise that often focus on the comparison of genes, genomes, and their expression profiles. Inferring new knowledge by combining different kinds of "post-genomics" data obviously necessitates the development of new approaches that allow the integration of variable data sources into a flexible framework. In this paper, we describe our concept for the integration of heterogeneous data into a platform for systems biology. We have implemented a Bioinformatics Resource for the Integration of heterogeneous Data from Genomic Explorations (BRIDGE) and illustrate the usability of our approach as a platform for systems biology for two sample applications.

Algorithms↗

PubMed2003

Whole genome shotgun sequencing guided by bioinformatics pipelines--an optimized approach for an established technique.

While the sequencing of bacterial genomes has become a routine procedure at major sequencing centers, there are still a number of genome projects at small- or medium-size facilities. For these facilities a maximum of control over sequencing, assembling and finishing is essential. At the same time, facilities have to be able to co-operate at minimum costs for the overall project. We have established a pipeline for the distributed sequencing of Alcanivorax borkumensis SK2, Azoarcus sp. BH72, Clavibacter michiganensis subsp. michiganensis NCPPB382, Sorangium cellulosum So ce56 and Xanthomonas campestris pv. vesicatoria 85-10. Our pipeline relies on standard tools (e.g. PHRED/PHRAP, CAP3 and Consed/Autofinish) wherever possible, supplementing them with new tools (BioMake and BACCardI) to achieve the aims described above.

Algorithms↗

PubMed2003

Bioinformatics support for high-throughput proteomics.

In the "post-genome" era, mass spectrometry (MS) has become an important method for the analysis of proteome data. The rapid advancement of this technique in combination with other methods used in proteomics results in an increasing number of high-throughput projects. This leads to an increasing amount of data that needs to be archived and analyzed. To cope with the need for automated data conversion, storage, and analysis in the field of proteomics, the open source system ProDB was developed. The system handles data conversion from different mass spectrometer software, automates data analysis, and allows the annotation of MS spectra (e.g. assign gene names, store data on protein modifications). The system is based on an extensible relational database to store the mass spectra together with the experimental setup. It also provides a graphical user interface (GUI) for managing the experimental steps which led to the MS data. Furthermore, it allows the integration of genome and proteome data. Data from an ongoing experiment was used to compare manual and automated analysis. First tests showed that the automation resulted in a significant saving of time. Furthermore, the quality and interpretability of the results was improved in all cases.

Algorithms↗

PubMed2003

EMMA: a platform for consistent storage and efficient analysis of microarray data.

As a high throughput technique, microarray experiments produce large data sets, consisting of measured data, laboratory protocols, and experimental settings. We have implemented the open source platform EMMA to store and analyze these data. The system provides automated pipelines for data processing and has a modular architecture that can be easily extended. EMMA features detailed reports about spots and their corresponding measurements. In addition to routine data analysis algorithms, the system can be integrated with other components that contain additional data sources (e.g. genome annotation systems).

Algorithms↗

PubMed2003

Complete genome sequence and analysis of Wolinella succinogenes.

To understand the origin and emergence of pathogenic bacteria, knowledge of the genetic inventory from their nonpathogenic relatives is a prerequisite. Therefore, the 2.11-megabase genome sequence of Wolinella succinogenes, which is closely related to the pathogenic bacteria Helicobacter pylori and Campylobacter jejuni, was determined. Despite being considered nonpathogenic to its bovine host, W. succinogenes holds an extensive repertoire of genes homologous to known bacterial virulence factors. Many of these genes have been acquired by lateral gene transfer, because part of the virulence plasmid pVir and an N-linked glycosylation gene cluster were found to be syntenic between C. jejuni and genomic islands of W. succinogenes. In contrast to other host-adapted bacteria, W. succinogenes does harbor the highest density of bacterial sensor kinases found in any bacterial genome to date, together with an elaborate signaling circuitry of the GGDEF family of proteins. Because the analysis of the W. succinogenes genome also revealed genes related to soil- and plant-associated bacteria such as the nif genes, W. succinogenes may represent a member of the epsilon proteobacteria with a life cycle outside its host.

Bacterial Proteins↗

PubMed2003

The complete Corynebacterium glutamicum ATCC 13032 genome sequence and its impact on the production of L-aspartate-derived amino acids and vitamins.

The complete genomic sequence of Corynebacterium glutamicum ATCC 13032, well-known in industry for the production of amino acids, e.g. of L-glutamate and L-lysine was determined. The C. glutamicum genome was found to consist of a single circular chromosome comprising 3282708 base pairs. Several DNA regions of unusual composition were identified that were potentially acquired by horizontal gene transfer, e.g. a segment of DNA from C. diphtheriae and a prophage-containing region. After automated and manual annotation, 3002 protein-coding genes have been identified, and to 2489 of these, functions were assigned by homologies to known proteins. These analyses confirm the taxonomic position of C. glutamicum as related to Mycobacteria and show a broad metabolic diversity as expected for a bacterium living in the soil. As an example for biotechnological application the complete genome sequence was used to reconstruct the metabolic flow of carbon into a number of industrially important products derived from the amino acid L-aspartate.

Amino Acid Sequence↗

PubMed2003

GenDB--an open source genome annotation system for prokaryote genomes.

The flood of sequence data resulting from the large number of current genome projects has increased the need for a flexible, open source genome annotation system, which so far has not existed. To account for the individual needs of different projects, such a system should be modular and easily extensible. We present a genome annotation system for prokaryote genomes, which is well tested and readily adaptable to different tasks. The modular system was developed using an object-oriented approach, and it relies on a relational database backend. Using a well defined application programmers interface (API), the system can be linked easily to other systems. GenDB supports manual as well as automatic annotation strategies. The software currently is in use in more than a dozen microbial genome annotation projects. In addition to its use as a production genome annotation system, it can be employed as a flexible framework for the large-scale evaluation of different annotation strategies. The system is open source.

Amino Acid Sequence↗

PubMed2003

Transcriptional changes in response to arbuscular mycorrhiza development in the model plant Medicago truncatula.

Significant changes in root morphology and physiology during arbuscular mycorrhiza (AM) development are likely to be controlled by specific gene expression pattern in the host plant. Until now, little was known about transcriptional changes which occur AM-exclusively; that is, they do not occur during other root-microbe associations, nor are they induced by improved phosphate nutrition. In order to identify such AM-exclusive gene inductions of Medicago truncatula, we used a pool of different RNA samples as subtractor population in a suppressive subtractive hybridization (SSH) experiment. This approach resulted in the identification of a number of new AM-regulated genes. None of these genes were expressed in nonmycorrhiza roots or leaves. Electronic data obtained by comparison of the cDNA sequences to expressed sequence tag (EST) sequences from a wide range of cDNA libraries in the M. truncatula EST database (Gene Index, MtGI) support the mycorrhiza specificity of the corresponding genes, because sequences in the MtGI that were found to match the identified SSH-cDNA sequences originated exclusively from AM cDNA libraries. The promoter of one of those genes, MtGst1, showing similarities to plant glutathione-S-transferase (GST) encoding genes, was cloned and used in reporter gene studies. In contrast to studies with the potato GST gene PRP, MtGst 1 promoter activity was detected in all zones of the root cortex colonized by Glomus intraradices, but nowhere else.

Base Sequence↗

PubMed2002

PathFinder: reconstruction and dynamic visualization of metabolic pathways.

MOTIVATION: Beyond methods for a gene-wise annotation and analysis of sequenced genomes new automated methods for functional analysis on a higher level are needed. The identification of realized metabolic pathways provides valuable information on gene expression and regulation. Detection of incomplete pathways helps to improve a constantly evolving genome annotation or discover alternative biochemical pathways. To utilize automated genome analysis on the level of metabolic pathways new methods for the dynamic representation and visualization of pathways are needed. RESULTS: PathFinder is a tool for the dynamic visualization of metabolic pathways based on annotation data. Pathways are represented as directed acyclic graphs, graph layout algorithms accomplish the dynamic drawing and visualization of the metabolic maps. A more detailed analysis of the input data on the level of biochemical pathways helps to identify genes and detect improper parts of annotations. As an Relational Database Management System (RDBMS) based internet application PathFinder reads a list of EC-numbers or a given annotation in EMBL- or Genbank-format and dynamically generates pathway graphs.

Bacillus subtilis↗