Biomedical subjects

Steffen Hennig

Publications and source records attributed to Steffen Hennig.

13 recordsLinked to original sources

PubMed2006

A second generation radiation hybrid map to aid the assembly of the bovine genome sequence.

BACKGROUND: Several approaches can be used to determine the order of loci on chromosomes and hence develop maps of the genome. However, all mapping approaches are prone to errors either arising from technical deficiencies or lack of statistical support to distinguish between alternative orders of loci. The accuracy of the genome maps could be improved, in principle, if information from different sources was combined to produce integrated maps. The publicly available bovine genomic sequence assembly with 6x coverage (Btau_2.0) is based on whole genome shotgun sequence data and limited mapping data however, it is recognised that this assembly is a draft that contains errors. Correcting the sequence assembly requires extensive additional mapping information to improve the reliability of the ordering of sequence scaffolds on chromosomes. The radiation hybrid (RH) map described here has been contributed to the international sequencing project to aid this process. RESULTS: An RH map for the 30 bovine chromosomes is presented. The map was built using the Roslin 3000-rad RH panel (BovGen RH map) and contains 3966 markers including 2473 new loci in addition to 262 amplified fragment-length polymorphisms (AFLP) and 1231 markers previously published with the first generation RH map. Sequences of the mapped loci were aligned with published bovine genome maps to identify inconsistencies. In addition to differences in the order of loci, several cases were observed where the chromosomal assignment of loci differed between maps. All the chromosome maps were aligned with the current 6x bovine assembly (Btau_2.0) and 2898 loci were unambiguously located in the bovine sequence. The order of loci on the RH map for BTA 5, 7, 16, 22, 25 and 29 differed substantially from the assembled bovine sequence. From the 2898 loci unambiguously identified in the bovine sequence assembly, 131 mapped to different chromosomes in the BovGen RH map. CONCLUSION: Alignment of the BovGen RH map with other published RH and genetic maps showed higher consistency in marker order and chromosome assignment than with the current 6x sequence assembly. This suggests that the bovine sequence assembly could be significantly improved by incorporating additional independent mapping information.

Animals↗

PubMed2006

The DNA sequence, annotation and analysis of human chromosome 3.

After the completion of a draft human genome sequence, the International Human Genome Sequencing Consortium has proceeded to finish and annotate each of the 24 chromosomes comprising the human genome. Here we describe the sequencing and analysis of human chromosome 3, one of the largest human chromosomes. Chromosome 3 comprises just four contigs, one of which currently represents the longest unbroken stretch of finished DNA sequence known so far. The chromosome is remarkable in having the lowest rate of segmental duplication in the genome. It also includes a chemokine receptor gene cluster as well as numerous loci involved in multiple human cancers such as the gene encoding FHIT, which contains the most common constitutive fragile site in the genome, FRA3B. Using genomic sequence from chimpanzee and rhesus macaque, we were able to characterize the breakpoints defining a large pericentric inversion that occurred some time after the split of Homininae from Ponginae, and propose an evolutionary history of the inversion.

Animals↗

PubMed2005

Mutational analysis of the NPHP4 gene in 250 patients with nephronophthisis.

Nephronophthisis (NPH), a recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal disease in the first two decades of life. Mutations in three genes (NPHP1, 2, and 3) were identified as causative. Extrarenal manifestations are known, such as retinitis pigmentosa (Senior-Loken syndrome, SLS) and ocular motor apraxia type Cogan. Recently, we identified a novel gene (NPHP4) as mutated in NPH. To date, a total of only 13 different NPHP4 mutations have been described. To determine the frequency of NPHP4 mutations, we performed mutational analysis by direct sequencing of all 30 NPHP4 exons in 250 different patients with isolated NPH, SLS, or Cogan syndrome ascertained worldwide over 14 years. We identified 23 novel NPHP4 sequence variants in 26/250 different patients (10%). Interestingly, we detected homozygous or compound heterozygous mutations of NPHP4 in only 6/250 different patients (2.4%), but only one heterozygous NPHP4 sequence variant in 20/250 different patients (8%). In the six patients with two NPHP4 mutations, 5/8 mutations (63%) were likely loss-of-function mutations, whereas in the 20 patients with only one sequence variant, only 1/20 (5%) was a likely loss-of-function (i.e., truncating) mutation. We conclude that: i) two recessive mutations in NPHP4 are a rare cause of nephronophthisis; ii) single heterozygous NPHP4 sequence variants are three times more prevalent than two recessive mutations; iii) there is no genotype/phenotype correlation; iv) there must exist further genes causing nephronophthisis, since in 224/250 (90%) patients, no sequence variants in either of the four NPH genes were detected.

Adolescent↗

PubMed2004

GOblet: a platform for Gene Ontology annotation of anonymous sequence data.

GOblet is a comprehensive web server application providing the annotation of anonymous sequence data with Gene Ontology (GO) terms. It uses a variety of different protein databases (human, murines, invertebrates, plants, sp-trembl) and their respective GO mappings. The user selects the appropriate database and alignment threshold and thereafter submits single or multiple nucleotide or protein sequences. Results are shown in different ways, e.g. as survey statistics for the main GO categories for all sequences or as detailed results for each single sequence that has been submitted. In its newest version, GOblet allows the batch submission of sequences and provides an improved display of results with the aid of Java applets. All output data, together with the Java applet, are packed to a downloadable archive for local installation and analysis. GOblet can be accessed freely at http://goblet.molgen.mpg.de.

Animals↗

PubMed2004

A first generation physical map of the medaka genome in BACs essential for positional cloning and clone-by-clone based genomic sequencing.

In order to realize the full potential of the medaka as a model system for developmental biology and genetics, characterized genomic resources need to be established, culminating in the sequence of the medaka genome. To facilitate the map-based cloning of genes underlying induced mutations and to provide templates for clone-based genomic sequencing, we have created a first-generation physical map of the medaka genome in bacterial artificial chromosome (BAC) clones. In particular, we exploited the synteny to the closely related genome of the pufferfish, Takifugu rubripes, by marker content mapping. As a first step, we clustered 103,144 public medaka EST sequences to obtain a set of 21,121 non-redundant sequence entities. Avoiding oversampling of gene-dense regions, 11,254 of EST clusters were successfully matched against the draft sequence of the fugu genome, and 2363 genes were selected for the BAC map project. We designed 35mer oligonucleotide probes from the selected genes and hybridized them against 64,500 BAC clones of strains Cab and Hd-rR, representing 14-fold coverage of the medaka genome. Our data set is further supplemented with 437 results generated from PCR-amplified inserts of medaka cDNA clones and BAC end-fragment markers. Our current, edited, first generation medaka BAC map consists of 902 map segments that cover about 74% of the medaka genome. The map contains 2721 markers. Of these, 2534 are from expressed sequences, equivalent to a non-redundant set of 2328 loci. The 934 markers (724 different) are anchored to the medaka genetic map. Thus, genetic map assignments provide immediate access to underlying clones and contigs, simplifying molecular access to candidate gene regions and their characterization.

Animals↗

PubMed2003

Expression profiling of human idiopathic dilated cardiomyopathy.

OBJECTIVE: To investigate the global changes accompanying human dilated cardiomyopathy (DCM) we performed a large-scale expression screen using myocardial biopsies from a group of DCM patients with moderate heart failure. By hierarchical clustering and functional annotation of the deregulated genes we examined extensive changes in the cellular and molecular processes associated to DCM. METHODS: The expression profiles were obtained using a whole genome covering library (UniGene RZPD1) comprising 30336 cDNA clones and amplified RNA from myocardiac biopsies from 10 DCM patients in comparison to tissue samples from four non-failing, healthy donors. RESULTS: By setting stringent selection criteria 364 differentially expressed, sequence-verified non-redundant transcripts were identified with a false discovery rate of <0.001. Numerous genes and ESTs were identified representing previously recognised, as well as novel DCM-associated transcripts. Many of them were found to be upregulated and involved in cardiomyocyte energetics, muscle contraction or signalling. Two hundred and twenty-two deregulated transcripts were functionally annotated and hierarchically clustered providing an insight into the pathophysiology of DCM. Data was validated using the MLP-deficient mouse, in which several differentially expressed transcripts identified in the human DCM biopsies could be confirmed. CONCLUSIONS: We report the first genome-wide expression profile analysis using cardiac biopsies from DCM patients at various stages of the disease. Although there is a diversity of links between the cytoskeleton and the initiation of DCM, we speculate that genes implicated in intracellular signalling and in muscle contraction are associated with early stages of the disease. Altogether this study represents the most comprehensive and inclusive molecular portrait of human cardiomyopathy to date.

Adult↗

PubMed2003

Automated Gene Ontology annotation for anonymous sequence data.

Gene Ontology (GO) is the most widely accepted attempt to construct a unified and structured vocabulary for the description of genes and their products in any organism. Annotation by GO terms is performed in most of the current genome projects, which besides generality has the advantage of being very convenient for computer based classification methods. However, direct use of GO in small sequencing projects is not easy, especially for species not commonly represented in public databases. We present a software package (GOblet), which performs annotation based on GO terms for anonymous cDNA or protein sequences. It uses the species independent GO structure and vocabulary together with a series of protein databases collected from various sites, to perform a detailed GO annotation by sequence similarity searches. The sensitivity and the reference protein sets can be selected by the user. GOblet runs automatically and is available as a public service on our web server. The paper also addresses the reliability of automated GO annotations by using a reference set of more than 6000 human proteins. The GOblet server is accessible at http://goblet.molgen.mpg.de.

Animals↗

PubMed2003

Genome-wide array analysis of normal and malformed human hearts.

BACKGROUND: We present the first genome-wide cDNA array analysis of human congenitally malformed hearts and attempted to partially elucidate these complex phenotypes. Most congenital heart defects, which account for the largest number of birth defects in humans, represent complex genetic disorders. As a consequence of the malformation, abnormal hemodynamic features occur and cause an adaptation process of the heart. METHODS AND RESULTS: The statistical analysis of our data suggests distinct gene expression profiles associated with tetralogy of Fallot, ventricular septal defect, and right ventricular hypertrophy. Applying correspondence analysis, we could associate specific gene functions to specific phenotypes. Furthermore, our study design allows the suggestion that alterations associated with primary genetic abnormalities can be distinguished from those associated with the adaptive response of the heart to the malformation (right ventricular pressure overload hypertrophy). We provide evidence for the molecular transition of the hypertrophic right ventricle to normal left ventricular characteristics. Furthermore, we present data on chamber-specific gene expression. CONCLUSIONS: Our findings propose that array analysis of malformed human hearts opens a new window to understand the complex genetic network of cardiac development and adaptation. For detailed access, see the online-only Data Supplement.

Adaptation, Physiological↗

PubMed2003

Generation, annotation, evolutionary analysis, and database integration of 20,000 unique sea urchin EST clusters.

Together with the hemichordates, sea urchins represent basal groups of nonchordate invertebrate deuterostomes that occupy a key position in bilaterian evolution. Because sea urchin embryos are also amenable to functional studies, the sea urchin system has emerged as one of the leading models for the analysis of the function of genomic regulatory networks that control development. We have analyzed a total of 107,283 cDNA clones of libraries that span the development of the sea urchin Strongylocentrotus purpuratus. Normalization by oligonucleotide fingerprinting, EST sequencing and sequence clustering resulted in an EST catalog comprised of 20,000 unique genes or gene fragments. Around 7000 of the unique EST consensus sequences were associated with molecular and developmental functions. Phylogenetic comparison of the identified genes to the genome of the urochordate Ciona intestinalis indicate that at least one quarter of the genes thought to be chordate specific were already present at the base of deuterostome evolution. Comparison of the number of gene copies in sea urchins to those in chordates and vertebrates indicates that the sea urchin genome has not undergone extensive gene or complete genome duplications. The established unique gene set represents an essential tool for the annotation and assembly of the forthcoming sea urchin genome sequence. All cDNA clones and filters of all analyzed libraries are available from the resource center of the German genome project at http://www.rzpd.de.

Animals↗

PubMed2003

New evidence for genome-wide duplications at the origin of vertebrates using an amphioxus gene set and completed animal genomes.

The 2R hypothesis predicting two genome duplications at the origin of vertebrates is highly controversial. Studies published so far include limited sequence data from organisms close to the hypothesized genome duplications. Through the comparison of a gene catalog from amphioxus, the closest living invertebrate relative of vertebrates, to 3453 single-copy genes orthologous between Caenorhabditis elegans (C), Drosophila melanogaster (D), and Saccharomyces cerevisiae (Y), and to Ciona intestinalis ESTs, mouse, and human genes, we show with a large number of genes that the gene duplication activity is significantly higher after the separation of amphioxus and the vertebrate lineages, which we estimate at 650 million years (Myr). The majority of human orthologs of 195 CDY groups that could be dated by the molecular clock appear to be duplicated between 300 and 680 Myr with a mean at 488 million years ago (Mya). We detected 485 duplicated chromosomal segments in the human genome containing CDY orthologs, 331 of which are found duplicated in the mouse genome and within regions syntenic between human and mouse, indicating that these were generated earlier than the human-mouse split. Model based calculations of the codon substitution rate of the human genes included in these segments agree with the molecular clock duplication time-scale prediction. Our results favor at least one large duplication event at the origin of vertebrates, followed by smaller scale duplication closer to the bird-mammalian split.

Animals↗

PubMed2002

Comparative and evolutionary analysis of the rhesus macaque extended MHC class II region.

The sequence-based map of a part of the rhesus macaque major histocompatibility complex (MHC) extended class II region is presented. The sequenced region encompasses 67,401 bp and contains the SACM2L, RING1, FABGL and KE4 genes, as well as the HTATSF1-like and ZNF-like pseudogenes. Similar to human, but different from rat and mouse, no class I genes are found in the SACM2L- RING1 interval. The rhesus macaque extended MHC class II region shows a high degree of conservation of exonic as well as intronic and intergenic sequences compared with the respective human region. It is concluded that this particular genomic organization of the extended class II region-i.e., the absence of class I genes and the presence of the HTATSF1-like and ZNF-like pseudogenes-can be traced back to a common ancestor of humans and rhesus macaques about 23 million years ago.

Animals↗

PubMed2002

Mutations in DNAH5 cause primary ciliary dyskinesia and randomization of left-right asymmetry.

Primary ciliary dyskinesia (PCD, MIM 242650) is characterized by recurrent infections of the respiratory tract due to reduced mucociliary clearance and by sperm immobility. Half of the affected offspring have situs inversus (reversed organs), which results from randomization of left-right (LR) asymmetry. We previously localized to chromosome 5p a PCD locus containing DNAH5, which encodes a protein highly similar to the Chlamydomonas gamma-dynein heavy chain. Here we characterize the full-length 14-kb transcript of DNAH5. Sequence analysis in individuals with PCD with randomization of LR asymmetry identified mutations resulting in non-functional DNAH5 proteins.

Animals↗

PubMed2002

Construction of a 'unigene' cDNA clone set by oligonucleotide fingerprinting allows access to 25 000 potential sugar beet genes.

Access to the complete gene inventory of an organism is crucial to understanding physiological processes like development, differentiation, pathogenesis, or adaptation to the environment. Transcripts from many active genes are present at low copy numbers. Therefore, procedures that rely on random EST sequencing or on normalisation and subtraction methods have to produce massively redundant data to get access to low-abundance genes. Here, we present an improved oligonucleotide fingerprinting (ofp) approach to the genome of sugar beet (Beta vulgaris), a plant for which practically no molecular information has been available. To identify distinct genes and to provide a representative 'unigene' cDNA set for sugar beet, 159 936 cDNA clones were processed utilizing large-scale, high-throughput data generation and analysis methods. Data analysis yielded 30 444 ofp clusters reflecting the number of different genes in the original cDNA sample. A sample of 10 961 cDNA clones, each representing a different cluster, were selected for sequencing. Standard sequence analysis confirmed that 89% of these EST sequences did represent different genes. These results indicate that the full set of 30 444 ofp clusters represent up to 25 000 genes. We conclude that the ofp analysis pipeline is an accurate and effective way to construct large representative 'unigene' sets for any plant of interest with no requirement for prior molecular sequence data.

Arabidopsis↗