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At least 307 records · Page 17Linked to original sources

Comparison of mouse Y-chromosomal repetitive sequences isolated from Mus musculus, M. spicilegus, and M. spretus.

The mouse Y chromosome is rich in repetitive sequences. We describe a new highly male-specific BALB/c mouse sequence named 142-5. The distribution of 142-5 related sequences, which appeared to be repeated at least 100 times in the male genome of Mus musculus, was visualized on the Y chromosome by in situ hybridization. Their accumulation patterns in the genus Mus showed that the sequences evolved quickly and suggested that they might prove useful for detecting genetic differences between closely related species. To test this hypothesis, we isolated 20 additional sequences from three mouse species (M. musculus, M. spicilegus, and M. spretus) and compared their nucleotide sequences using three different computer programs. It was found that the sequences were remarkably similar but could be divided into four subgroups, and that each species had a distinct set or sets of sequences that were amplified in the Y chromosome.

Animals↗

Impact of cytogenetic and molecular cytogenetic studies on hematologic malignancies.

Conventional cytogenetic analysis of chromosome abnormalities in hematologic malignancies is hampered by the low mitotic index and poor quality of metaphases. A range of techniques based on fluorescence in situ hybridization (FISH) has greatly enhanced the identification of non-random translocations and deletions, pinpointing regions which contain genes involved in leukemogenesis. One of the main advantages of FISH is its ability to use non-dividing interphase cells as DNA targets, enabling the screening of large numbers of cells and providing access to a variety of cells with different hematopoetic activity. Furthermore, multicolor FISH (SKY, M-FISH and CGH microarrays) combines the screening potential of cytogenetics with the accuracy of molecular genetics, allowing the visualization of the entire human genome in 24 different colors.

Chromosome Aberrations↗

Seven clusters in genomic triplet distributions.

In several recent papers new gene-detection algorithms were proposed for detecting protein-coding regions without requiring a learning dataset of already known genes. The fact that unsupervised gene-detection is possible is closely connected to the existence of a cluster structure in oligomer frequency distributions. In this paper we study the cluster structure of several genomes in the space of their triplet frequencies, using a pure data exploration strategy. Several complete genomic sequences were analyzed, using the visualization of tables of triplet frequencies in a sliding window. The distribution of 64-dimensional vectors of triplet frequencies displays a well-detectable cluster structure. The structure was found to consist of seven clusters, corresponding to protein-coding information in three possible phases in one of the two complementary strands and in the non-coding regions with high accuracy (higher than 90% on nucleotide level). Visualizing and understanding the structure allows to analyze effectively the performance of different gene-prediction tools. Since the method does not require extraction of ORFs, it can be applied even for unassembled genomes.

Algorithms↗

Genquire: genome annotation browser/editor.

UNLABELLED: We present a software package, Genquire, that allows visualization, querying, hand editing, and de novo markup of complete or partially annotated genomes. The system is written in Perl/Tk and uses, where possible, existing BioPerl data models and methods for representation and manipulation of the sequence and annotation objects. An adaptor API is provided to allow Genquire to display a wide range of databases and flat files, and a plugins API provides an interface to other sequence analysis software. AVAILABILITY: Genquire v3.03 is open-source software. The code is available for download and/or contribution at http://www.bioinformatics.org/Genquire

Chromosome Mapping↗

Nuclear RNA accumulations contain released transcripts and exhibit specific distributions with respect to Sm antigen foci.

RNA polymerase II transcripts accumulate within mammalian nuclei at distinct sites and exhibit varying morphology. Certain RNA species are organized in elongated structures, whereas others appear as dot-like concentrations. To analyze the status of the RNA within these accumulations, we investigated the composition of accumulations derived from Epstein-Barr virus (EBV) genes, human papilloma virus 18 (HPV18) open reading frames E6 and E7, as well as heat shock protein 89a (hsp89alpha) and 89beta (hsp89beta) genes. No differential distribution of exon and intron sequences within concentrations of EBV RNA could be observed. Whereas accumulations of hsp89alpha and hsp89beta always coincided with Sm antigen foci, the RNA of EBV and HPV18 never co-localized with these foci. This excludes Sm antigen foci as the only sites of splicing and suggests gene-specific variation in the nuclear localization of transcripts. Two sets of experiments were performed to assess whether transcripts in the RNA accumulations are in statu nascendi or products released from a discrete gene locus. Because RNA transcripts derived from EBV genes, which are located on both ends of the genome, were all distributed along the entire length of the RNA signals, they cannot be derived from a highly decondensed genomic DNA extending throughout elongated RNA accumulations. Furthermore, removal of labeled RNA sequences and subsequent visualization of DNA confirmed the confinement of the genomic sequences to a small subregion of the area occupied by accumulated RNA. Therefore, this study supports the view of RNA accumulations as a stream of molecules that delineate a path from a dot-like gene locus toward the nuclear envelope for export into the cytoplasm.

Autoantigens↗

Statistical Viewer: a tool to upload and integrate linkage and association data as plots displayed within the Ensembl genome browser.

BACKGROUND: To facilitate efficient selection and the prioritization of candidate complex disease susceptibility genes for association analysis, increasingly comprehensive annotation tools are essential to integrate, visualize and analyze vast quantities of disparate data generated by genomic screens, public human genome sequence annotation and ancillary biological databases. We have developed a plug-in package for Ensembl called "Statistical Viewer" that facilitates the analysis of genomic features and annotation in the regions of interest defined by linkage analysis. RESULTS: Statistical Viewer is an add-on package to the open-source Ensembl Genome Browser and Annotation System that displays disease study-specific linkage and/or association data as 2 dimensional plots in new panels in the context of Ensembl's Contig View and Cyto View pages. An enhanced upload server facilitates the upload of statistical data, as well as additional feature annotation to be displayed in DAS tracts, in the form of Excel Files. The Statistical View panel, drawn directly under the ideogram, illustrates lod score values for markers from a study of interest that are plotted against their position in base pairs. A module called "Get Map" easily converts the genetic locations of markers to genomic coordinates. The graph is placed under the corresponding ideogram features a synchronized vertical sliding selection box that is seamlessly integrated into Ensembl's Contig- and Cyto- View pages to choose the region to be displayed in Ensembl's "Overview" and "Detailed View" panels. To resolve Association and Fine mapping data plots, a "Detailed Statistic View" plot corresponding to the "Detailed View" may be displayed underneath. CONCLUSION: Features mapping to regions of linkage are accentuated when Statistic View is used in conjunction with the Distributed Annotation System (DAS) to display supplemental laboratory information such as differentially expressed disease genes in private data tracks. Statistic View is a novel and powerful visual feature that enhances Ensembl's utility as valuable resource for integrative genomic-based approaches to the identification of candidate disease susceptibility genes. At present there are no other tools that provide for the visualization of 2-dimensional plots of quantitative data scores against genomic coordinates in the context of a primary public genome annotation browser.

Chromosome Mapping↗

Evolving genomic metaphors: a new look at the language of DNA.

Recent genome-sequencing efforts have confirmed that traditional "good-citizen" genes (those that encode functional RNA and protein molecules of obvious benefit to the organism) constitute only a small fraction of the genomic populace in humans and other multicellular creatures. The rest of the DNA sequence includes an astonishing collection of noncoding regions, regulatory modules, deadbeat pseudogenes, legions of repetitive elements, and hosts of oft-shifty, self-interested nomads, renegades, and immigrants. To help visualize functional operations in such intracellular genomic societies and to better encapsulate the evolutionary origins of complex genomes, new and evocative metaphors may be both entertaining and research-stimulating.

Animals↗

SNPbox: web-based high-throughput primer design from gene to genome.

SNPbox is a modular software package that automates the design of PCR primers for large-scale amplification and sequencing projects in a standardized manner resulting in high-quality PCR amplicons with a low failure rate. Here, we present the SNPbox web server at http://www.SNPbox.org, which hosts the SNPbox web service as well as the data from SNPbox analysis of all Ensembl exons. The data of this genome-wide SNPbox application can be visualized in Ensembl's ContigView through a DAS (distributed annotation system) annotation server.

DNA Primers↗

Rapid method to characterize lactococcal bacteriophage genomes.

We present a rapid method to isolate and analyze bacteriophage DNA. Cells are infected and phage replication is allowed to proceed normally for 30 to 60 min. Prior to DNA packaging and cell bursts, the infected cells (1 ml) are harvested and lysed by using a combination of lysozyme and sodium dodecyl sulfate treatments. The total DNA recovered is enriched for phage genomes, and restriction fragments of the phage DNA can be readily visualized on agarose gels. This method was used to grossly compare the genomes of nine lactococcal phages isolated from different cheese plants at different times. The method was also used to visualize the inhibitory effects of pTR2030-induced abortive infection on the replication of phage nck202.31 in its homologous host, Lactococcus lactis NCK203.

Journal Article↗

Visualization of microarray results to assist interpretation.

Whole genome microarrays allow assessment of the profile of genes expressed under particular experimental conditions, including external stimuli such as pH or temperature, and internal changes brought about by deleting or over-expressing a gene. Such experiments produce large data sets, for which sophisticated analysis software is available. What is lacking are tools for analysing data sets from different experiments, in order to test and generate hypotheses about the links between regulatory networks. We describe here a method for presenting results from different experiments as a directed graph constructed using an automated graph drawing program xneato, enhanced by a logic program designed to cluster data and aid in the generation of hypotheses about possible gene interactions. A web-based front-end to the system has been constructed to explore and manipulate the graphical displays produced. Results of microarray experiments on Mycobacterium tuberculosis were used to develop and evaluate the visualization tool and initiate the development of an inference system for gene interactions based on such data. The GeneGraph project can be accessed at: zebrafish.doc.ic.ac.uk

Computer Graphics↗

A genome-wide in situ hybridization map of RNA-binding proteins reveals anatomically restricted expression in the developing mouse brain.

BACKGROUND: In eukaryotic cells, RNA-binding proteins (RBPs) contribute to gene expression by regulating the form, abundance, and stability of both coding and non-coding RNA. In the vertebrate brain, RBPs account for many distinctive features of RNA processing such as activity-dependent transcript localization and localized protein synthesis. Several RBPs with activities that are important for the proper function of adult brain have been identified, but how many RBPs exist and where these genes are expressed in the developing brain is uncharacterized. RESULTS: Here we describe a comprehensive catalogue of the unique RBPs encoded in the mouse genome and provide an online database of RBP expression in developing brain. We identified 380 putative RBPs in the mouse genome. Using in situ hybridization, we visualized the expression of 323 of these RBP genes in the brains of developing mice at embryonic day 13.5, when critical fate choice decisions are made and at P0, when major structural components of the adult brain are apparent. We demonstrate i) that 16 of the 323 RBPs examined show neural-specific expression at the stages we examined, and ii) that a far larger subset (221) shows regionally restricted expression in the brain. Of the regionally restricted RBPs, we describe one group that is preferentially expressed in the E13.5 ventricular areas and a second group that shows spatially restricted expression in post-mitotic regions of the embryonic brain. Additionally, we find a subset of RBPs that share the same complex pattern of expression, in proliferating regions of the embryonic and postnatal NS and peripheral tissues. CONCLUSION: Our data show that, in contrast to their proposed ubiquitous involvement in gene regulation, most RBPs are not uniformly expressed. Here we demonstrate the region-specific expression of RBPs in proliferating vs. post-mitotic brain regions as well as cell-type-specific RBP expression. We identify uncharacterized RBPs that exhibit neural-specific expression as well as novel RBPs that show expression in non-neural tissues. The data presented here and in an online database provide a visual filter for the functional analysis of individual RBPs.

Animals↗

Direct visualization of the clonal progression of primary cutaneous melanoma: application of tissue microdissection and comparative genomic hybridization.

Human cutaneous malignant melanoma progresses through a series of well defined clinical and histopathological stages. It has been assumed that the neoplastic progression of this disease advances from a common acquired nevus or dysplastic nevus through the primary radial growth phase (RGP), primary vertical growth phase (VGP), and finally to distant metastasis. However, it has never been directly shown that VGP is clonally derived from RGP. Furthermore, it has not been possible previously to conduct a detailed genetic analysis on pure tumor cells from archival material because the lesions are a heterogeneous mixture of normal and neoplastic cells, and the entire specimen must be excised and fixed for clinical diagnosis. This report describes a new approach designed to identify DNA copy number changes in tumor cells from a series of progressive primary stages of cutaneous melanoma archival biopsies. Under direct high-power visualization, cells are procured with a sterile needle from highly specific areas of the tissue section. DNA is extracted from microdissected cells (normal, RGP, and VGP), PCR amplified, fluorescently labeled, and examined by comparative genomic hybridization to determine DNA copy number changes. Data obtained from three representative cases suggest a clonal derivation of VGP cells from RGP. This approach could be useful in identifying the sequence of genetic changes in progressive cutaneous melanoma stages.

Aged↗

Imaging genome abnormalities in cancer research.

Increasing attention is focusing on chromosomal and genome structure in cancer research due to the fact that genomic instability plays a principal role in cancer initiation, progression and response to chemotherapeutic agents. The integrity of the genome (including structural, behavioral and functional aspects) of normal and cancer cells can be monitored with direct visualization by using a variety of cutting edge molecular cytogenetic technologies that are now available in the field of cancer research. Examples are presented in this review by grouping these methodologies into four categories visualizing different yet closely related major levels of genome structures. An integrated discussion is also presented on several ongoing projects involving the illustration of mitotic and meiotic chromatin loops; the identification of defective mitotic figures (DMF), a new type of chromosomal aberration capable of monitoring condensation defects in cancer; the establishment of a method that uses Non-Clonal Chromosomal Aberrations (NCCAs) as an index to monitor genomic instability; and the characterization of apoptosis related chromosomal fragmentations caused by drug treatments.

Journal Article↗

Tumor cytogenetics revisited: comparative genomic hybridization and spectral karyotyping.

Fluorescence in situ hybridization techniques allow the visualization and localization of DNA target sequences on the chromosomal and cellular level and have evolved as exceedingly valuable tools in basic chromosome research and cytogenetic diagnostics. Recent advances in molecular cytogenetic approaches, namely comparative genomic hybridization and spectral karyotyping, now allow tumor genomes to be surveyed for chromosomal aberrations in a single experiment and permit identification of tumor-specific chromosomal aberrations with unprecedented accuracy. Comparative genomic hybridization utilizes the hybridization of differentially labeled tumor and reference DNA to generate a map of DNA copy number changes in tumor genomes. Comparative genomic hybridization is an ideal tool for analyzing chromosomal imbalances in archived tumor material and for examining possible correlations between these findings and tumor phenotypes. Spectral karyotyping is based on the simultaneous hybridization of differentially labeled chromosome painting probes (24 in human), followed by spectral imaging that allows the unique display of all human (and other species) chromosomes in different colors. Spectral karyotyping greatly facilitates the characterization of numerical and structural chromosomal aberrations, therefore improving karyotype analysis considerably. We review these new molecular cytogenetic concepts, describe applications of comparative genomic hybridization and spectral karyotyping for the visualization of chromosomal aberrations as they relate to human malignancies and animal models thereof, and provide evidence that fluorescence in situ hybridization has developed as a robust and reliable technique which justifies its translation to cytogenetic diagnostics.

Animals↗

Molecular characterization of the red visual pigment gene of the American chameleon (Anolis carolinensis).

The red sensitive visual pigment of the American chameleon, Anolis carolinensis, is unique in having absorption maximum some 50 nm further into the red than any other terrestrial vertebrate examined. We report here the isolation and sequence determination of the genomic DNA clone for the Anolis red visual pigment gene. Phylogenetic analysis shows that this gene is most closely related to the gecko green and chicken red visual pigment genes. We identified nine Anolis-specific amino acid replacements, seven of which reside in transmembrane domains and might contribute to the red-shift of the Anolis visual pigments.

Amino Acid Sequence↗

MethTools--a toolbox to visualize and analyze DNA methylation data.

The Bisulfite Genomic Sequencing technique has found wide acceptance for the generation of DNA-methylation maps with single-base resolution. The method is based on the selective deamination of cytosine to uracil (and subsequent conversion to thymine via PCR), whereas 5-methylcytosine residues remain unchanged. Methylation maps are created by the comparison of bisulfite converted sequences with the untreated genomic sequence. 'MethTools' is a collection of software tools that replaces the time-consuming manual comparison process, generates graphical outputs of methylation patterns and methyl-ation density, estimates the systematic error of the experiment and searches for conserved methylated nucleotide patterns. The programs are written in Perl 5 and C, and the source code can be downloaded. All tools run independently but the programs are interfaced. Thus, a script can perform the entire analysis procedure automatically. In addition, a web-based remote analysis service is offered. Both the source code and the remote analysis are available at http://genome.imb-jena.de/methtools/

Animals↗

Visualizing chromatin and chromosomes in living cells.

The dynamic organization of eukaryotic genomes in cell nuclei recently came into the focus of research interest. The kinetics of genome dynamics can be addressed only by approaches involving live cell microscopy. Different methods are available to visualize chromatin, specific chromatin fractions, or individual chromosome territories within nuclei of living mammalian cells. Appropriate labeling procedures as well as cell chamber systems and important controls for live cell microscopy are described.

Animals↗