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Results for “Genomic profiling”

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At least 937 records · Page 52Linked to original sources
PubMed2003

Paradoxical effects of a stress signal on pro- and anti-apoptotic machinery in HTLV-1 Tax expressing cells.

Adult T-cell leukemia (ATL) and HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP) are associated with Human T-cell lymphotropic virus type 1 (HTLV-1) infection. The viral transactivator, Tax is able to mediate the cell cycle progression by targeting key regulators of the cell cycle such as p21/waf1, p16/ink4a, p53, cyclins D1-3/cdk complexes, and the mitotic spindle checkpoint MAD apparatus, thereby deregulating cellular DNA damage and checkpoint control. Genome expression profiling of infected cells exemplified by the development of DNA microarrays represents a major advance in genome-wide functional analysis. Utilizing cDNA microarray analysis, we have observed an apparent opposing and paradoxical regulatory network of host cell gene expression upon the introduction of DNA damage stress signal. We find the apparent induction of cell cycle inhibitors, and pro- as well as anti-apoptotic gene expression is directly linked to whether cells are at either G1, S, or G2/M phases of the cell cycle. Specifically, a G1/S block is induced by p21/waf1 and p16/ink4a, while pro-apoptotic expression at S, and G2/M is associated with caspase activation, and anti-apoptotic gene expression is associated with up regulation of Bcl-2 family member, namely bfl-1 gene. Therefore, the microarray results indicating expression of both pro- and anti-apoptotic genes could easily be explained by the particular stage of the cell cycle. Mechanism and the functional outcome of induction for both pathways are discussed.

Apoptosis↗
PubMed2026

Genomic epidemiology and antimicrobial resistance profile of Shigella isolated from diarrhoea diseases in under-five children in Blantyre, Malawi.

Antimicrobial resistance (AMR) in Shigella is rising globally, complicating shigellosis management. Whole-genome sequence analysis (WGSA) has advanced our understanding of AMR and transmission dynamics, yet contemporary whole-genome sequencing data from Shigella in sub-Saharan Africa remain scarce. In this study, we applied WGSA to 27 Shigella isolates collected from children presenting with diarrhoea at Ndirande Health Centre in Malawi (2022-2023), as part of the Enterics for Global Health Shigella surveillance study. Serotyping, AMR profiling and phylogenetic analysis revealed Shigella sonnei as the dominant serogroup, with distinct genetic clustering relative to global reference strains among S. sonnei, Shigella flexneri and Shigella boydii. We identified 16 AMR genes linked to ten antimicrobial classes with qnrS1 and qnrB19 genes conferring resistance to fluoroquinolone, alongside IncFIB(K) and IncFII plasmid replicon markers. Importantly, no azithromycin resistance determinants were detected both genotypically and phenotypically, providing baseline evidence that warrants continued surveillance of current first-line treatment. However, the detection of fluoroquinolone resistance genes with plasmid replicon markers in the absence of phenotypic resistance might indicate a silent reservoir with epidemic potential. This is the first contemporary Shigella data from a large-scale diarrhoea disease surveillance study in Malawi, providing essential baseline information for guiding antibiotic treatment and future vaccine development efforts, contributing to the efforts to combat shigellosis in Malawi and other similar regions.

Humans↗
PubMed2002

Microarray analysis of bacterial pathogenicity.

The DNA microarray, a surface that contains an ordered arrangement of each identified open reading frame of a sequenced genome, is the engine of functional genomics. Its output, the expression profile, provides a genome wide snap-shot of the transcriptome. Refined by array-specific statistical instruments and data-mined by clustering algorithms and metabolic pathway databases, the expression profile discloses, at the transcriptional level, how the microbe adapts to new conditions of growth--the regulatory networks that govern the adaptive response and the metabolic and biosynthetic pathways that effect the new phenotype. Adaptation to host microenvironments underlies the capacity of infectious agents to persist in and damage host tissues. While monitoring the whole genome transcriptional response of bacterial pathogens within infected tissues has not been achieved, it is likely that the complex, tissue-specific response is but the sum of individual responses of the bacteria to specific physicochemical features that characterize the host milieu. These are amenable to experimentation in vitro and whole-genome expression studies of this kind have defined the transcriptional response to iron starvation, low oxygen, acid pH, quorum-sensing pheromones and reactive oxygen intermediates. These have disclosed new information about even well-studied processes and provide a portrait of the adapting bacterium as a 'system', rather than the product of a few genes or even a few regulons. Amongst the regulated genes that compose this adaptive system are transcription factors. Expression profiling experiments of transcription factor mutants delineate the corresponding regulatory cascade. The genetic basis for pathogenicity can also be studied by using microarray-based comparative genomics to characterize and quantify the extent of genetic variability within natural populations at the gene level of resolution. Also identified are differences between pathogen and commensal that point to possible virulence determinants or disclose evolutionary history. The host vigorously engages the pathogen; expression studies using host genome microarrays and bacterially infected cell cultures show that the initial host reaction is dominated by the innate immune response. However, within the complex expression profile of the host cell are components mediated by pathogen-specific determinants. In the future, the combined use of bacterial and host microarrays to study the same infected tissue will reveal the dialogue between pathogen and host in a gene-by-gene and site- and time-specific manner. Translating this conversation will not be easy and will probably require a combination of powerful bioinformatic tools and traditional experimental approaches--and considerable effort and time.

Animals↗
PubMed1988

Analysis of genome segments from six different isolates of bluetongue virus using RNA-RNA hybridisation: a generalised coding assignment for bluetongue viruses.

Nucleic acid probes prepared directly from bluetongue virus (BTV) genomic double-stranded RNA (dsRNA) have been used to identify the functionally equivalent genome segments from six distinct isolates of BTV after their separation in both agarose and polyacrylamide gel electrophoresis systems. Variations in the rate, and in one case the order, of migration of the equivalent genome segments from different viruses was detected in the polyacrylamide gel system. However, the genomic dsRNA profiles of eleven BTV isolates were found to be identical when analysed by agarose gel electrophoresis. Functionally equivalent genome segments from the six viruses that were analysed were found to migrate in identical relative positions in this gel system. From these data we propose a modified version of the protein coding assignments published for BTV 1 South Africa (Mertens et al., 1984) in which the identification of the genome segments would be based upon their order of migration in the agarose rather than the polyacrylamide gel system. The modified coding assignments, unlike the original assignments, would be applicable to all of those viruses analysed and appear likely to be valid for all normal BTV isolates.

Bluetongue virus↗
PubMed2000

Extensive intra-tumor heterogeneity in primary human glial tumors as a result of locus non-specific genomic alterations.

Genomic changes are a hallmark of the neoplastic process. These range from alterations at specific loci and defined karyotypic changes which influence tumor behavior to generalized alterations exemplified by microsatellite instability. Generalized genomic changes within a tumor would be evidence in favor of the mutator hypothesis which postulates a role for such extensive changes during tumorigenesis. In this report, we have used the DNA fingerprinting technique of randomly amplified polymorphic DNA (RAPD) analysis to study genomic alterations within primary human astrocytic tumors (gliomas) in a locus non-specific manner. The RAPD fingerprinting profile of consecutive segments of tumors 2 mm across was studied; 17 astrocytic (high- and low-grade) tumors were sectioned end to end. Tissue from 50 consecutive sections, 40 microm thick (total 2 mm across), was pooled and taken to be a tumor compartment. DNA was subjected to RAPD amplification by 15 random 10-mer primers. A tumor segment was taken to have a DNA fingerprinting pattern different from others in the same specimen when its RAPD profile differed from others by at least one band of one RAPD reaction. All but one of the tumors showed compartments with a unique genetic profile, indicating genomic instability leading to widespread intra-tumor genetic heterogeneity. Eight tumors were also studied for loss of heterozygosity (LOH) of the p53 and D17S379 loci in the different segments as examples of alteration of specific tumor influencing loci. Three showed LOH of p53, which was limited to only one compartment of each tumor. The extensive intra-tumor genetic instability detected in this study is suggestive of the overall high rate of change in the genomes of tumors including those of a lower grade. It is hypothesized that some of these altered clones, which manifest as zones of heterogeneity in a solid tumor, may accumulate changes at loci known to influence tumor behavior, and thus clinical outcome.

Brain Neoplasms↗
PubMed2004

SGMD: the Soybean Genomics and Microarray Database.

The Soybean Genomics and Microarray Database (SGMD) attempts to provide an integrated view of the interaction of soybean with the soybean cyst nematode and contains genomic, EST and microarray data with embedded analytical tools allowing correlation of soybean ESTs with their gene expression profiles. SGMD provides analytical tools to mine the microarray data quickly by integrating many analysis methods within the database itself. The expression profiles of genes at time intervals during the first 8 days of nematode invasion is searchable by gene name or GenBank accession number. Recent developments include the addition of a searchable database for soybean cyst nematode ESTs and photographs of the invasion process at time points examined using microarrays. SGMD is completely accessible from the web at: http://psi081.ba.ars.usda.gov/SGMD/default.htm.

Computational Biology↗
PubMed2006

Sex-specific expression of alternative transcripts in Drosophila.

BACKGROUND: Many genes produce multiple transcripts due to alternative splicing or utilization of alternative transcription initiation/termination sites. This 'transcriptome expansion' is thought to increase phenotypic complexity by allowing a single locus to produce several functionally distinct proteins. However, sex, genetic and developmental variation in the representation of alternative transcripts has never been examined systematically. Here, we describe a genome-wide analysis of sex-specific expression of alternative transcripts in Drosophila melanogaster. RESULTS: We compared transcript profiles in males and females from eight Drosophila lines (OregonR and 2b, and 6 RIL) using a newly designed 60-mer oligonucleotide microarray that allows us to distinguish a large proportion of alternative transcripts. The new microarray incorporates 7,207 oligonucleotides, satisfying stringent binding and specificity criteria that target both the common and the unique regions of 2,768 multi-transcript genes, as well as 12,912 oligonucleotides that target genes with a single known transcript. We estimate that up to 22% of genes that produce multiple transcripts show a sex-specific bias in the representation of alternative transcripts. Sexual dimorphism in overall transcript abundance was evident for 53% of genes. The X chromosome contains a significantly higher proportion of genes with female-biased transcription than the autosomes. However, genes on the X chromosome are no more likely to have a sexual bias in alternative transcript representation than autosomal genes. CONCLUSION: Widespread sex-specific expression of alternative transcripts in Drosophila suggests that a new level of sexual dimorphism at the molecular level exists.

Alternative Splicing↗
PubMed2006

Basic microarray analysis: strategies for successful experiments.

Microarrays offer a powerful approach to the analysis of gene expression that can be used for a wide variety of experimental purposes. However, several types of microarray platforms are available. In addition, microarray experiments are expensive and generate complicated data sets that can be difficult to interpret. Success with microarray approaches requires a sound experimental design and a coordinated and appropriate use of statistical tools. Here, the advantages and pitfalls of utilizing microarrays are discussed, as are practical strategies to help novice users succeed with this method that can empower them with the ability to assay changes in gene expression at the whole-genome level.

Computational Biology↗
PubMed2002

Microarray-based copy number and expression profiling in dedifferentiated and pleomorphic liposarcoma.

Sixteen dedifferentiated and pleomorphic liposarcomas were analyzed by comparative genomic hybridization (CGH) to genomic microarrays (matrix-CGH), cDNA-derived microarrays for expression profiling, and by quantitative PCR. Matrix-CGH revealed copy number gains of numerous oncogenes, i.e., CCND1, MDM2, GLI, CDK4, MYB, ESR1, and AIB1, several of which correlate with a high level of transcripts from the respective gene. In addition, a number of genes were found differentially expressed in dedifferentiated and pleomorphic liposarcomas. Application of dedicated clustering algorithms revealed that both tumor subtypes are clearly separated by the genomic profiles but only with a lesser power by the expression profiles. Using a support vector machine, a subset of five clones was identified as "class discriminators." Thus, for the distinction of these types of liposarcomas, genomic profiling appears to be more advantageous than RNA expression analysis.

Algorithms↗
PubMed2001

Degenerate oligonucleotide primed-polymerase chain reaction-based array comparative genomic hybridization for extensive amplicon profiling of breast cancers : a new approach for the molecular analysis of paraffin-embedded cancer tissue.

We have developed a protocol for degenerate oligonucleotide-primed-polymerase chain reaction-based array comparative genomic hybridization (array CGH) that, when combined with a laser microdissection technique, allows the analysis of cancer cell populations isolated from routine, formalin-fixed, paraffin-embedded tissue samples. Comparison of copy number changes detected by degenerate oligonucleotide-primed-polymerase chain reaction-based array CGH to those detected by conventional array CGH or fluorescence in situ hybridization, demonstrated that amplifications can be reliably detected. Using a genomic microarray containing 57 oncogenes, we screened a total of 28 breast cancer samples and obtained a detailed amplicon profile that is the most comprehensive to date in human breast cancer. The array CGH method described here will allow the genetic analysis of paraffin-embedded human cancer materials for example in the context of clinical trials.

Breast Neoplasms↗
PubMed2002

"Omic" approaches for unraveling signaling networks.

Signaling pathways are crucial for cell differentiation and response to cellular environments. Recently, a large number of approaches for the global analysis of genes and proteins have been described. These have provided important new insights into the components of different pathways and the molecular and cellular responses of these pathways. This review covers genomic and proteomic (collectively referred to as "omic") approaches for the global analysis of cell signaling, including gene expression profiling and analysis, protein-protein interaction methods, protein microarrays, mass spectroscopy and gene-disruption and engineering approaches.

Animals↗
PubMedDate not supplied

Parallel molecular genetic analysis.

We describe recent progress in parallel molecular genetic analyses using DNA microarrays, gel-based systems, and capillary electrophoresis and utilization of these approaches in a variety of molecular biology assays. These applications include use of polymorphic markers for mapping of genes and disease-associated loci and carrier detection for genetic diseases. Application of these technologies in molecular diagnostics as well as fluorescent technologies in DNA analysis using immobilized oligonucleotide arrays on silicon or glass microchips are discussed. The array-based assays include sequencing by hybridization, cDNA expression profiling, comparative genome hybridization and genetic linkage analysis. Developments in non microarray-based, parallel analyses of mutations and gene expression profiles are reviewed. The promise of and recent progress in capillary array electrophoresis for parallel DNA sequence analysis and genotyping is summarized. Finally, a framework for decision making in selecting available technology options for specific molecular genetic analyses is presented.

DNA↗