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At least 685 records · Page 38Linked to original sources
PubMed2001

Genomic analysis of gamma-ray-induced germ-cell mutations at the b locus recovered from the medaka specific-locus test.

To study how gamma-ray-induced germ-cell mutations are fixed at the early embryonic stage of the next generation, genomic alterations in the b locus mutants (colorless melanophores) detected during development in the medaka specific-locus test (SLT) were analyzed. First, nine anonymous DNA markers linked to the b locus were cloned and mapped into the region extending about 47cM surrounding the b locus. Next, losses of paternal alleles of these DNA markers were examined in each of the 51 gamma-ray-induced b locus mutants obtained after irradiation of sperm or spermatids. In these mutants, 47 were dominant lethals, three were semi-viable and one was viable. All the mutants examined had large deletions surrounding the b locus. One viable mutant had an interstitial deletion, while all the semi-viable and dominant lethal ones appeared to have terminal deletions. Deletions extending about 20-35cM were the most frequently observed in 18 of the 51 mutants examined. The largest one extended more than 40cM. These results suggest that most of the gamma-ray induced germ cell mutations recovered as total specific-locus mutants were accompanied by large genomic deletions, which eventually led the mutant embryos to dominant lethality.

Animals↗
PubMed1995

Novel phosphotransferase system genes revealed by bacterial genome analysis--a gene cluster encoding a unique Enzyme I and the proteins of a fructose-like permease system.

Previous publications have demonstrated the presence of a cryptic gene encoding a novel Enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Recent Escherichia coli genome sequencing revealed a gene (ptsA) encoding a new Enzyme I homologue in the 89.1-89.3 centisome region. We have analysed this region, and here describe and characterize open reading frames (ORFs) encoding (1) a fused PTS Enzyme I-IIAFru homologue, (2) a glycerol dehydrogenase, (3) a transaldolase homologue, (4) two PTS IIBFru homologues, (5) a PTS IICFru homologue, and (6) homologues of pyruvate formate-lyase and its activating enzyme. Binary comparison scores, multiple alignments and phylogenetic trees establish the families of proteins to which each of the relevant ORFs belong. Identification of the putative products of this gene cluster leads to the proposal that several of the proteins encoded in this region function in anaerobic carbon metabolism.

Acetyltransferases↗
PubMed2006

Helicobacter pylori HopH (OipA) and bacterial pathogenicity: genetic and functional genomic analysis of hopH gene polymorphisms.

BACKGROUND: Expression of the Helicobacter pylori outer membrane protein HopH is regulated by phase variation within a CT dinucleotide repeat motif of the hopH gene. METHODS: To investigate the importance of HopH for bacterial pathogenicity, we performed a detailed functional genomic and population-based genetic characterization of this contingency locus. RESULTS: Sequencing of hopH in H. pylori strains from 58 patients revealed that the hopH "on" genotype is linked to bacterial virulence determinants, such as the vacAs1, vacAm1, babA2, and, most strongly, cagA genotypes. hopH mutagenesis resulted in reduced bacterial adherence to gastric epithelia in vitro. Complementation of hopH in trans restored the adherence properties of hopH mutants. Although HopH has been previously linked to proinflammatory epithelial signaling, hopH mutagenesis did not alter epithelial interleukin-8 secretion in vitro. Comparative epithelial gene-expression profiling by cDNA microarrays revealed no significant differences between the wild-type-specific and hopH mutant-specific transcriptomes. By contrast, a large set of genes was differentially regulated in a cag pathogenicity island-dependent manner. CONCLUSION: An in-frame hopH gene may be linked to gastroduodenal diseases because of its association with other virulence factors or increased bacterial adherence and colonization. The strong linkage with cagA indicates that HopH may contribute to the fitness of cagA-positive strains in vivo.

Adhesins, Bacterial↗
PubMed2003

A genomic analysis of the shade avoidance response in Arabidopsis.

Plants respond to the proximity of neighboring vegetation by elongating to prevent shading. Red-depleted light reflected from neighboring vegetation triggers a shade avoidance response leading to a dramatic change in plant architecture. These changes in light quality are detected by the phytochrome family of photoreceptors. We analyzed global changes in gene expression over time in wild-type, phyB mutant, and phyA phyB double mutant seedlings of Arabidopsis in response to simulated shade. Using pattern fitting software, we identified 301 genes as shade responsive with patterns of expression corresponding to one of various physiological response modes. A requirement for a consistent pattern of expression across 12 chips in this way allowed more subtle changes in gene expression to be considered meaningful. A number of previously characterized genes involved in light and hormone signaling were identified as shade responsive, as well as several putative, novel shade-specific signal transduction factors. In addition, changes in expression of genes in a range of pathways associated with elongation growth and stress responses were observed. The majority of shade-responsive genes demonstrated antagonistic regulation by phyA and phyB in response to shade following the pattern of many physiological responses. An analysis of promoter elements of genes regulated in this way identified conserved promoter motifs potentially important in shade regulation.

Arabidopsis↗
PubMed2003

msDNA-St85, a multicopy single-stranded DNA isolated from Salmonella enterica serovar Typhimurium LT2 with the genomic analysis of its retron.

Bacterial reverse transcriptase is responsible for the production of a small satellite DNA-RNA complex called multicopy single-stranded DNA (msDNA) that has been found in a wide variety of Gram-negative bacteria. Here we describe the isolation and characterization of a novel msDNA, msDNA-St85, from Salmonella enterica serovar Typhimurium LT2. We determined the nucleotide sequence of msDNA-St85 and the location of retron-St85 on the chromosome that is responsible for msDNA-St85 production by analyzing the complete genomic sequence of S. typhimurium LT2. It was found that the G+C content and the codon usage of retron-St85 were significantly different from those of the S. typhimurium genome, indicating that retron-St85 was probably acquired recently in this bacterium. This is the first report for identification of an msDNA in the genus Salmonella with the complete description and analysis of its retron.

Amino Acid Sequence↗
PubMed1996

Genome analysis of adenovirus type 3 isolated in Japan.

Adenovirus type 3 (Ad3) isolates, isolated from 45 patients with acute conjunctivitis during the year 1990 in Japan, were studied by DNA restriction enzyme analysis with restriction endonucleases recognizing 6-bp sequences (BamHI, SmaI, HindIII, BglII) and endonucleases recognizing 5- or 4-bp sequences (HinfI and TaqI). All 45 isolates of Ad3 were identified as the genome type Ad3f by six endonucleases. They were further classified into three varieties by HinfI, varieties H1 (87.5%), H2 (8.9%), and H3 (2.2%), and into five varieties by TaqI, varieties T1 (75.6%), T2 (13.3%), T3 (2.2%), T4 (4.5%), and T5 (8.9%). The use of HinfI and TaqI was sufficient to distinguish six subgenome types: types Ad3fH1T1, Ad3fH1T2, Ad3fH1T4, Ad3fH1T5, Ad3fH2T1, and Ad3fH3T3. Among them, Ad3fH1T1 was predominant in areas where the virus is epidemic. The study showed that the same Ad3 genome type, genome type Ad3f, caused acute viral conjunctivitis even in different areas in Japan. The source and the route of infection were suggested to be common in areas where the virus is epidemic.

Adenovirus Infections, Human↗
PubMed1998

Genomic analysis of DUSP6, a dual specificity MAP kinase phosphatase, in pancreatic cancer.

DUSP6 (alias PYST1), one of the dual-specificity tyrosine phosphatases, is localized on 12q21, one of the regions of frequent allelic loss in pancreatic cancer. This gene is composed of three exons, and two forms of alternatively spliced transcripts are ubiquitously expressed. Although no mutations were observed in 26 pancreatic cancer cell lines, reduced expressions of the full-length transcripts were observed in some cell lines, which may suggest some role for DUSP6 in pancreatic carcinogenesis.

Blotting, Southern↗
PubMed2004

Whole genome analysis of the OsGRF gene family encoding plant-specific putative transcription activators in rice (Oryza sativa L.).

OsGRF1 (Oryza sativa GROWTH-REGULATING FACTOR1) is a rice gene encoding a putative novel transcriptional regulator. We identified and characterized eleven homologs of OsGRF1 in the rice genome. All twelve OsGRF proteins have two highly conserved regions, the QLQ (Gln, Leu, Gln) and WRC (Trp, Arg, Cys) domains, and sequences reminiscent of transcription factors. OsGRF genes were preferentially expressed in young and growing tissues, and applied gibberellic acid (GA3) enhanced the expression of seven OsGRF genes. In situ hybridization showed high levels of OsGRF1 transcripts in the shoot apical meristem and in cells surrounding the vasculature of the intercalary meristem. In a GAL4-based yeast assay, the C-terminal region of OsGRF1 was found to have transactivation activity. These results indicate that OsGRF1 acts as a transcriptional activator. Based on the in situ expression pattern of OsGRF1, we postulate that it may be involved in regulating vegetative growth in rice.

DNA, Complementary↗
PubMed2004

Whole-genome analysis of temporal gene expression during foregut development.

We have investigated the cis-regulatory network that mediates temporal gene expression during organogenesis. Previous studies demonstrated that the organ selector gene pha-4/FoxA is critical to establish the onset of transcription of Caenorhabditis elegans foregut (pharynx) genes. Here, we discover additional cis-regulatory elements that function in combination with PHA-4. We use a computational approach to identify candidate cis-regulatory sites for genes activated either early or late during pharyngeal development. Analysis of natural or synthetic promoters reveals that six of these sites function in vivo. The newly discovered temporal elements, together with predicted PHA-4 sites, account for the onset of expression of roughly half of the pharyngeal genes examined. Moreover, combinations of temporal elements and PHA-4 sites can be used in genome-wide searches to predict pharyngeal genes, with more than 85% accuracy for their onset of expression. These findings suggest a regulatory code for temporal gene expression during foregut development and provide a means to predict gene expression patterns based solely on genomic sequence.

Animals↗
PubMed2004

Genomic analysis of regulatory network dynamics reveals large topological changes.

Network analysis has been applied widely, providing a unifying language to describe disparate systems ranging from social interactions to power grids. It has recently been used in molecular biology, but so far the resulting networks have only been analysed statically. Here we present the dynamics of a biological network on a genomic scale, by integrating transcriptional regulatory information and gene-expression data for multiple conditions in Saccharomyces cerevisiae. We develop an approach for the statistical analysis of network dynamics, called SANDY, combining well-known global topological measures, local motifs and newly derived statistics. We uncover large changes in underlying network architecture that are unexpected given current viewpoints and random simulations. In response to diverse stimuli, transcription factors alter their interactions to varying degrees, thereby rewiring the network. A few transcription factors serve as permanent hubs, but most act transiently only during certain conditions. By studying sub-network structures, we show that environmental responses facilitate fast signal propagation (for example, with short regulatory cascades), whereas the cell cycle and sporulation direct temporal progression through multiple stages (for example, with highly inter-connected transcription factors). Indeed, to drive the latter processes forward, phase-specific transcription factors inter-regulate serially, and ubiquitously active transcription factors layer above them in a two-tiered hierarchy. We anticipate that many of the concepts presented here--particularly the large-scale topological changes and hub transience--will apply to other biological networks, including complex sub-systems in higher eukaryotes.

Algorithms↗
PubMed2006

Complete genome analysis of 33 ecologically and biologically diverse Rift Valley fever virus strains reveals widespread virus movement and low genetic diversity due to recent common ancestry.

Rift Valley fever (RVF) virus is a mosquito-borne RNA virus responsible for large explosive outbreaks of acute febrile disease in humans and livestock in Africa with significant mortality and economic impact. The successful high-throughput generation of the complete genome sequence was achieved for 33 diverse RVF virus strains collected from throughout Africa and Saudi Arabia from 1944 to 2000, including strains differing in pathogenicity in disease models. While several distinct virus genetic lineages were determined, which approximately correlate with geographic origin, multiple exceptions indicative of long-distance virus movement have been found. Virus strains isolated within an epidemic (e.g., Mauritania, 1987, or Egypt, 1977 to 1978) exhibit little diversity, while those in enzootic settings (e.g., 1970s Zimbabwe) can be highly diverse. In addition, the large Saudi Arabian RVF outbreak in 2000 appears to have involved virus introduction from East Africa, based on the close ancestral relationship of a 1998 East African virus. Virus genetic diversity was low (approximately 5%) and primarily involved accumulation of mutations at an average of 2.9 x 10(-4) substitutions/site/year, although some evidence of RNA segment reassortment was found. Bayesian analysis of current RVF virus genetic diversity places the most recent common ancestor of these viruses in the late 1800s, the colonial period in Africa, a time of dramatic changes in agricultural practices and introduction of nonindigenous livestock breeds. In addition to insights into the evolution and ecology of RVF virus, these genomic data also provide a foundation for the design of molecular detection assays and prototype vaccines useful in combating this important disease.

Animals↗
PubMed2007

Genomic analysis of the phosphotransferase system in Clostridium botulinum.

Clostridium botulinum is capable of fermenting carbohydrates, but there have been no detailed studies of the uptake of sugars and related substrates. In bacteria, a common and often predominant system of carbohydrate uptake is the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS). This multi-protein complex catalyses a group translocation involving both uptake and phosphorylation of carbohydrates, and is also known to play an important role in environmental sensing and metabolic regulation. The genome of C. botulinum encodes 15 PTSs which have a similar domain structure to the PTS in other bacteria. Based on phylogenetic relationships and analysis of gene clusters, the C. botulinum PTS appears to be involved in the uptake of hexoses, hexose derivatives and disaccharides. C. botulinum also contains the components of PTS-associated regulatory mechanisms which have been characterised in other bacteria. It therefore seems likely that the PTS plays a significant, and previously unrecognised, role in the physiology of this bacterium.

Biological Transport↗
PubMed2002

Whole-genome analysis of genes regulated by the Bacillus subtilis competence transcription factor ComK.

The Bacillus subtilis competence transcription factor ComK is required for establishment of competence for genetic transformation. In an attempt to study the ComK factor further, we explored the genes regulated by ComK using the DNA microarray technique. In addition to the genes known to be dependent on ComK for expression, we found many genes or operons whose ComK dependence was not known previously. Among these genes, we confirmed the ComK dependence of 16 genes by using lacZ fusions, and three genes were partially dependent on ComK. Transformation efficiency was significantly reduced in an smf disruption mutant, although disruption of the other ComK-dependent genes did not result in significant decreases in transformation efficiency. Nucleotide sequences similar to that of the ComK box were found for most of the newly discovered genes regulated by ComK.

Bacillus subtilis↗
PubMed2005

[Comparative genomic analysis of vibrio cholerae El Tor preseventh and seventh pandemic strains isolated in various periods].

Genetic organization of 52 Vibrio cholerae El Tor biotype preseventh and seventh pandemic strains isolated in various periods was studied by PCR assay and DNA-DNA hybridization. It was established that the genome of most ancient of analyzed strains isolated from a diarrhea patient in 1910 was devoid of CTX and RS1 prophages, vibrio pathogenicity islands (VPI and VPI-2), and pandemic islands (VSP-1 and VSP-2) that contain key virulence genes. The appearance of pathogenic properties in cholera vibrios for the first time causing a local outbreak of cholera in 1937 is connected with the acquisition of VPI and CTX that carried genes tcpA and ctx-AB, respectively, which are responsible for the colonization of small intestine and encode the production of cholera toxin. The appearance of seventh pandemic agent for cholera was shown to correlate with the acquisition by its precursor of two additional blocks of genes VSP-1 and VSP-2. This finding strongly supports the involvement of these genes in formation of the pandemic potential in strains. Molecular typing methods allowed elucidation of differences in the genetic organization between prepandemic and pandemic strains. The detected variability of the genome of contemporary virulent strains may be a reason for the occurrence of etiological agent for cholera with new properties.

Base Sequence↗