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At least 667 records · Page 37Linked to original sources

Genomic analysis of immediate/early response to shear stress in human coronary artery endothelial cells.

The involvement of shear stress in the pathogenesis of vascular disease has motivated efforts to define the endothelial cell response to applied shear stress in vitro. A central question has been the mechanisms by which endothelial cells perceive and respond to changes in fluid flow. We have utilized cDNA microarrays to characterize the immediate/early genomic response to applied laminar shear stress (LSS) in primary cultures of human coronary artery endothelial cells (HCAECs). Cells were exposed, in a parallel plate flow chamber, to 0, 15, or 45 dyn/cm2 LSS for 1 h, and gene expression profiles were determined using human GEM1 cDNA microarrays. We find that a high proportion of LSS-responsive genes are transcription factors, and these are related by their involvement in growth arrest. These likely play a central role in the reprogramming of endothelial homeostasis following the switch from a static to a shear-stressed environment. LSS-responsive genes were also found to encode factors involved in vasoreactivity, signal transduction, antioxidants, cell cycle-associated genes, and markers of cytoskeletal function and dynamics.

Blotting, Northern↗

Genomic analysis of the vitellogenin locus in rainbow trout (Oncorhynchus mykiss) reveals a complex history of gene amplification and retroposon activity.

Vitellogenins (Vtg) are the major yolk proteins in most oviparous organisms. They are encoded by a small number of genes--between one and four depending on the species. Characterization of the Vtg region in the genome of the rainbow trout reveals unusual features, however, in that this locus contains twenty complete genes and ten pseudogenes per haploid genome. The Vtg genes differ from each other by insertion, deletion and rearrangement events, although, at the sequence level, they show a high degree of similarity. Fluorescent in situ hybridization (FISH), pulsed-field gel electrophoresis (PFGE) and Southern analysis indicate that all gene copies are contained in a single 1,500-kb region, and that most of the genes form tandem arrays separated by a conserved 4.5-kb intergenic region. The presence of large reiterated fragments indicates that this region has been subjected to several amplification events. The presence of a retroposon element (called 19) in Vtg intron 9 appears to be responsible for the silencing of at least nine of the ten pseudogenes. Two other incomplete retrotransposons (one LTR- and one LINE-type) and sequences derived from a HIV-like retrovirus are inserted into the conserved intergenic region, very close to the transcription start site. Their presence in all Vtg 5'-flanking regions suggests a possible role in gene amplification at this locus.

Animals↗

Towards Arabidopsis genome analysis: monitoring expression profiles of 1400 genes using cDNA microarrays.

cDNA microarrays containing 1443 Arabidopsis thaliana genes were analyzed for expression profiles in major organs of Arabidopsis plants. Novel expression profiles were identified for many coding sequences with putative gene identifications. Expression patterns of novel sequences provided clues to their possible functions. The results demonstrate how microarrays containing a large number of Arabidopsis genes can provide a powerful tool for plant gene discovery, functional analysis and elucidation of genetic regulatory networks.

Arabidopsis↗

Full-length genome analysis of HIV-1 subtype C utilizing CXCR4 and intersubtype recombinants isolated in South Africa.

The HIV-1 epidemic in South Africa is largely due to subtype C viruses, which preferentially use CCR5 as a coreceptor for infection. We describe full-length genome sequences of two CXCR4-utilizing HIV-1 subtype C viruses and two intersubtype recombinants from South Africa. Three of the viruses (99ZACM4, 99ZACM9, and 99ZASW7) were isolated in 1999 from AIDS patients in Johannesburg, and a fourth virus (98ZADu178) was isolated in Durban in 1998 from an asymptomatic female sex worker. Isolates 99ZASW7 and 99ZACM9 from Johannesburg were subtype C throughout the genome, 99ZASW7 used the CXCR4 coreceptor, and 99ZACM9 used both CCR5 and CXCR4. Isolate 98ZADu178 from Durban was a novel recombinant between subsubtype A2 and subtype C. The third isolate from Johannesburg, 99ZACM4, was a complex, novel recombinant with multiple breakpoints and contained segments of subtypes A, C, D, G, and K. These results establish the presence of intersubtype recombinants in South Africa, indicating that ongoing surveillance for other subtypes and recombinants is necessary.

Female↗

Genomic analysis II: isolation of high molecular weight heteroduplex DNA following differential methylase protection and Formamide-PERT hybridization.

Understanding the nature of DNA sequence differences among individuals is important to the understanding of fundamental questions in biology. To analyze such differences in complex genomes new approaches must be developed. We report two new techniques which aid in this effort. First, we have developed a modification of the Phenol Emulsion Reassociation Technique (PERT) that allows hybridization of long (20 kb and longer) single copy heteroduplex DNA fragments from human genomic DNAs. Secondly, by using a differential methylase protection technique we have shown that double methylase resistant heteroduplex DNA molecules can be size fractionated away from reannealed single methylase resistant homoduplex DNA molecules. These methods will be useful in obtaining DNA from chromosomal subregions linked to the inheritance of a specific trait or condition as described in the preceding paper and could also be used to create a map of the chromosomal subregion which includes the gene for the trait.

DNA↗

Complete sequence and evolutionary genomic analysis of the Pseudomonas aeruginosa transposable bacteriophage D3112.

Bacteriophage D3112 represents one of two distinct groups of transposable phage found in the clinically relevant, opportunistic pathogen Pseudomonas aeruginosa. To further our understanding of transposable phage in P. aeruginosa, we have sequenced the complete genome of D3112. The genome is 37,611 bp, with an overall G+C content of 65%. We have identified 53 potential open reading frames, including three genes (the c repressor gene and early genes A and B) that have been previously characterized and sequenced. The organization of the putative coding regions corresponds to published genetic and transcriptional maps and is very similar to that of enterobacteriophage Mu. In contrast, the International Committee on Taxonomy of Viruses has classified D3112 as a lambda-like phage on the basis of its morphology. Similarity-based analyses identified 27 open reading frames with significant matches to proteins in the NCBI databases. Forty-eight percent of these were similar to Mu-like phage and prophage sequences, including proteins responsible for transposition, transcriptional regulation, virion morphogenesis, and capsid formation. The tail proteins were highly similar to prophage sequences in Escherichia coli and phage Phi12 from Staphylococcus aureus, while proteins at the right end were highly similar to proteins in Xylella fastidiosa. We performed phylogenetic analyses to understand the evolutionary relationships of D3112 with respect to Mu-like versus lambda-like bacteriophages. Different results were obtained from similarity-based versus phylogenetic analyses in some instances. Overall, our findings reveal a highly mosaic structure and suggest that extensive horizontal exchange of genetic material played an important role in the evolution of D3112.

Bacteriophages↗

Genetics of postzygotic isolation in Eucalyptus: whole-genome analysis of barriers to introgression in a wide interspecific cross of Eucalyptus grandis and E. globulus.

The genetic architecture of hybrid fitness characters can provide valuable insights into the nature and evolution of postzygotic reproductive barriers in diverged species. We determined the genome-wide distribution of barriers to introgression in an F(1) hybrid of two Eucalyptus tree species, Eucalyptus grandis (W. Hill ex Maiden.) and E. globulus (Labill.). Two interspecific backcross families (N = 186) were used to construct comparative, single-tree, genetic linkage maps of an F(1) hybrid individual and two backcross parents. A total of 1354 testcross AFLP marker loci were evaluated in the three parental maps and a substantial proportion (27.7% average) exhibited transmission ratio distortion (alpha = 0.05). The distorted markers were located in distinct regions of the parental maps and marker alleles within each region were all biased toward either of the two parental species. We used a Bayesian approach to estimate the position and effect of transmission ratio distorting loci (TRDLs) in the distorted regions of each parental linkage map. The relative viability of TRDL alleles ranged from 0.20 to 0.72. Contrary to expectation, heterospecific (donor) alleles of TRDLs were favored as often as recurrent alleles in both backcrosses, suggesting that positive and negative heterospecific interactions affect introgression rates in this wide interspecific pedigree.

Alleles↗

Identification of diagnostic proteins in Mycobacterium avium subspecies paratuberculosis by a whole genome analysis approach.

Mycobacterium avium subspecies paratuberculosis (M. paratuberculosis) is an economically significant veterinary pathogen that causes Johne's disease in cattle and sheep. There is a critical need for improved diagnostic tests to detect M. paratuberculosis infection in these animals. As with many other animal diseases, efforts need to be concentrated on the development of simple, rapid, noninvasive tests that can be performed by veterinarians or animal producers without expensive laboratory equipment. With the genome sequence of M. paratuberculosis now complete, we have taken a different strategy to identify novel proteins that are present uniquely in M. paratuberculosis and are antigenic in the context of infected cattle. Through a whole genome comparison of M. paratuberculosis with other sequenced mycobacterial genomes, we identified a collection of more than 90 genes that are present uniquely in M. paratuberculosis. This list has been further trimmed to 39 after amplification using polymerase chain reaction of unique genes using the genomic deoxyribonucleic acid template from several mycobacterial species and isolates. A selection of the remaining genes has been cloned and expressed in Escherichia coli and purified by affinity chromatography. Successfully purified proteins were analyzed using sera from rabbits immunized with M. paratuberculosis. Furthermore, to identify antigens in the context of disease, sera from cattle with Johne's disease as well as healthy control cattle are used in immunoassays. Using this methodology, we identified the first protein antigens specific to M. paratuberculosis.

Animals↗

Combined transcriptome and genome analysis of single micrometastatic cells.

In human cancer, early systemic spread of tumor cells is recognized as a leading cause of death. Adjuvant therapies are administered to patients after complete resectioning of their primary tumors to eradicate the few residual and latent metastatic cells. These therapeutic regimens, however, are currently designed without direct information about the presence or nature of the latent cells. To address this problem, we developed a PCR-based technique to analyze the transcriptome of individual tumor cells isolated from the bone marrow of cancer patients. From the same cells, genomic aberrations were identified by comparative genomic hybridization. The utility of this approach for understanding the biology of occult disseminated cells and for the identification of new therapeutic targets is demonstrated here by the detection of frequent extracellular matrix metalloproteinase inducer (EMMPRIN; CD147) expression which was verified by immunostaining.

Cell Cycle↗

Whole-genome analysis of Oryza sativa reveals similar architecture of two-component signaling machinery with Arabidopsis.

The two-component system (TCS), which works on the principle of histidine-aspartate phosphorelay signaling, is known to play an important role in diverse physiological processes in lower organisms and has recently emerged as an important signaling system in plants. Employing the tools of bioinformatics, we have characterized TCS signaling candidate genes in the genome of Oryza sativa L. subsp. japonica. We present a complete overview of TCS gene families in O. sativa, including gene structures, conserved motifs, chromosome locations, and phylogeny. Our analysis indicates a total of 51 genes encoding 73 putative TCS proteins. Fourteen genes encode 22 putative histidine kinases with a conserved histidine and other typical histidine kinase signature sequences, five phosphotransfer genes encoding seven phosphotransfer proteins, and 32 response regulator genes encoding 44 proteins. The variations seen between gene and protein numbers are assumed to result from alternative splicing. These putative proteins have high homology with TCS members that have been shown experimentally to participate in several important physiological phenomena in plants, such as ethylene and cytokinin signaling and phytochrome-mediated responses to light. We conclude that the overall architecture of the TCS machinery in O. sativa and Arabidopsis thaliana is similar, and our analysis provides insights into the conservation and divergence of this important signaling machinery in higher plants.

Amino Acid Sequence↗

Comparative genomic analysis of sequences sampled from a small region on soybean (Glycine max) molecular linkage group G.

Eight DNA markers spanning an interval of approximately 10 centimorgans (cM) on soybean (Glycine max) molecular linkage group G (MLG-G) were used to identify bacterial artificial chromosome (BAC) clones. Twenty-eight BAC clones in eight distinct contiguous groups (contigs) were isolated from this genome region, along with 59 BAC clones on 17 contigs homoeologous to those on MLG-G. BAC clones in four of the MLG-G contigs were also digested to produce subclones and detailed physical maps. All of the BAC-ends were sequenced, as were the subclones, to estimate proportions in different sequence categories, compare similarities among homoeologs, and explore microsynteny with Arabidopsis. Homoeologous BAC contigs were enriched in repetitive sequences compared with those on MLG-G or the soybean genome as a whole. Fingerprint and cross-hybridization comparisons between MLG-G and homoeologous contigs revealed cases of highly similar physical organization between soybean duplicates, as did DNA sequence comparisons. Twenty-seven out of 78 total sequences on soybean MLG-G showed significant similarity to Arabidopsis. The homologs mapped to six compact genome segments in Arabidopsis, with the longest containing seven homologs spanning two million base pairs. These results extend previous observations of large-scale duplication and selective gene loss in Arabidopsis, suggesting that networks of conserved synteny between Arabidopsis and other angiosperm families can stretch over long physical distances.

Arabidopsis↗

Genomic analysis of the mouse protamine 1, protamine 2, and transition protein 2 gene cluster reveals hypermethylation in expressing cells.

To understand the role of chromatin structure in the expression of the mouse protamine 1, protamine 2, and transition protein 2 genes during spermatogenesis, we have examined the genomic organization of this cluster of "haploid-specific" genes. As seen in the human genome, protamine 2, transition protein 2, and approximately 2.8 kb of a CpG island, hereafter called CpG island-dTP2, were clustered in a small region. Methylation analyses of this region have demonstrated that i) unlike most other tissue-specific genes, the protamine 1, protamine 2, and transition protein 2 genes were located in a large methylated domain in round spermatids, the cell type where they are transcribed, ii) the protamine 1 gene was only partially methylated in somatic cells and in testes from 7-day-old mice, and iii) the approximately 2 kb upstream and downstream of the CpG island-dTP2 were only partially methylated in somatic tissues. DNase I analysis revealed the presence of at least five strong DNase I hypersensitive sites over the CpG island-dTP2 in somatic tissues, but not in germ cells, and sequence analysis indicated that the CpG island-dTP2 is homologous to a CpG island located approximately 10.6 kb downstream of the human transition protein 2 gene. Although the nature of a CpG island-dTP2 and the function of a CpG island-dTP2-containing somatic tissue-specific DNase I hypersensitive sites in close proximity to the germ cell-specific gene cluster are unclear, the "open" chromatin structure of the CpG island-dTP2 may be responsible for the partial methylation pattern of the flanking sequences including the transition protein 2 gene in somatic tissues.

Animals↗

Evolutionary conservation of chymotrypsinogen gene: genomic analysis and protein modeling.

Chymotrypsinogen is widely present in various animal pancreases. To study evolutionary relationship of chymotrypsinogen gene in species, we used a cDNA probe of human prechymotrypsinogen to investigate the species distribution of chymotrypsinogen gene, and designed oligodeoxynucleotide primers to investigate the genomic organization in the three domains of active sites. The genomic analyses showed that chymotrypsinogen gene is evolutionary conserved in species. On the basis of the deduced amino acid residues, a three-dimensional model for human chymotrypsinogen was further built by computer graphics. The model showed high similarity to the X-ray crystal structure of bovine chymotrypsinogen A, thus, demonstrated that the three-dimensional structure is more conserved in evolution than protein sequences.

Animals↗

Identification of vaccine candidate antigens from a genomic analysis of Porphyromonas gingivalis.

Porphyromonas gingivalis is a key periodontal pathogen which has been implicated in the etiology of chronic adult periodontitis. Our aim was to develop a protein based vaccine for the prevention and or treatment of this disease. We used a whole genome sequencing approach to identify potential vaccine candidates. From a genomic sequence, we selected 120 genes using a series of bioinformatics methods. The selected genes were cloned for expression in Escherichia coli and screened with P. gingivalis antisera before purification and testing in an animal model. Two of these recombinant proteins (PG32 and PG33) demonstrated significant protection in the animal model, while a number were reactive with various antisera. This process allows the rapid identification of vaccine candidates from genomic data.

Amino Acid Sequence↗