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G L Wang

Publications and source records attributed to G L Wang.

At least 55 records · Page 3Linked to original sources
PubMed1996

The cloned gene, Xa21, confers resistance to multiple Xanthomonas oryzae pv. oryzae isolates in transgenic plants.

The cloned rice gene, Xa21, confers resistance to multiple pathogen isolates of Xanthomonas oryzae pv. oryzae in transgenic plants. The resistance phenotype was stably transmitted to T1 progeny and inherited as a single locus. The T1 progeny were tested for resistance to 32 X. oryzae pv. oryzae isolates from eight countries. Both the engineered line and the donor line showed resistance to 29 isolates and susceptibility to three isolates. The identical resistance spectrum of both lines indicates that the presence of a single member of a multigene family, Xa21, is sufficient to confer multi-isolate resistance. The results presented here have important implications for engineering disease resistance in crop plants.

Base Sequence↗
PubMed1996

Molecular basis of hypoxia-induced erythropoietin expression.

Erythropoietin gene (EPO) expression is activated by tissue hypoxia in renal peritubular interstitial fibroblasts and, to a lesser extent, in hepatocytes and ito cells of the liver. A hypoxia-inducible enhancer spanning approximately 50 bp within the 3'-flanking region of the EPO gene is required for transcriptional activation in hypoxic cells. Hypoxia-inducible factor 1 is a basic helix-loop-helix protein that binds at the 5' end of the enhancer. The binding of hypoxia-inducible factor 1 is absolutely required for enhancer function. Hepatocyte nuclear factor 4 is an orphan receptor that binds at the 3' end of the enhancer. The binding of hepatocyte nuclear factor 4 augments hypoxia-inducible transcription mediated by the enhancer but is not absolutely required for enhancer function. Factors binding to the enhancer may interact synergistically with factors binding to the EPO promoter to activate transcription in hypoxic cells. Indirect evidence suggests that oxygen tension may be sensed by a hemoprotein. In one model, the putative hemoprotein adopts different conformational states depending on whether O2 is bound. Another model proposes that the hemoprotein converts O2 to H2O2. The protein tyrosine kinase c-Src, GTP-binding protein Ras, and MAP kinase signal pathways have been implicated in hypoxia signal transduction, but no direct evidence links these pathways to EPO transcriptional activation.

Animals↗
PubMed1996

[The immunomodulatory effect of lentinan].

Lentinan (LTN) was extracted from Lentinus edodes (Berk) Sing with molecular weight of 5 x 10(5). The effects of lentinan on cellular immune function were studied in vivo by measuring the cellular delayed type hypersensitivity (DTH) to dinitrofluorobenzene (DNFB) in cyclophosphamide (Cy)-comprised mice. The effect of lentinan on T lymphocyte proliferation to Con A on splenocytes and T lymphocyte subpopulations on thymocytes and on splenocytes from normal mice were also evaluated. Moreover, the effect of LTN on production of tumor necrosis factor (TNF) from murine peritoneal macrophage was also tested. LTN was administered at doses of 1, 5 and 10 mg.kg-1.d-1. The following results were observed: LTN administration(X6) augmented the T lymphocyts proliferation to Con A in normal mice; LTN restorated the DTH to DNFB impaired by single Cy(200 mg.kg-1 and 80 mg.kg-1, ip) after using LTN for 8 or 5 d; LTN administration (X6) either decreased the percentage of L3T4+ (Th), Lyt2+ (Ts) in thymocytes or increased the percentage of L3T4+, Lyt2+ in splenocytes; LTN(X6) administration elicited release of TNF from M phi in the presence of lipoplysaccharide (LPS). These results indicate that the immunomodulating effect of LTN may be relevant to change of T cell subpopulation and increase of TNF production.

Adjuvants, Immunologic↗
PubMed1995

A receptor kinase-like protein encoded by the rice disease resistance gene, Xa21.

The rice Xa21 gene, which confers resistance to Xanthomonas oryzae pv. oryzae race 6, was isolated by positional cloning. Fifty transgenic rice plants carrying the cloned Xa21 gene display high levels of resistance to the pathogen. The sequence of the predicted protein, which carries both a leucine-rich repeat motif and a serine-threonine kinase-like domain, suggests a role in cell surface recognition of a pathogen ligand and subsequent activation of an intracellular defense response. Characterization of Xa21 should facilitate understanding of plant disease resistance and lead to engineered resistance in rice.

Amino Acid Sequence↗
PubMed1995

Effect of protein kinase and phosphatase inhibitors on expression of hypoxia-inducible factor 1.

Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric bHLH-PAS protein essential for erythropoietin gene transcription in hypoxic cells. Here we show that both 2-aminopurine and sodium fluoride, inhibitors of serine/threonine kinases and phosphatases, respectively, interfered with the hypoxic induction of HIF-1 DNA-binding activity and expression of HIF-1 alpha and HIF-1 beta(ARNT) subunits. Genistein, an inhibitor of tyrosine kinases, completely blocked the synthesis of both HIF-1 subunits as well as HIF-1 DNA-binding activity. Sodium orthovanadate, an inhibitor of tyrosine phosphatases increased the basal level of HIF-1 proteins and HIF-1 activity. These data suggest that protein phosphorylation events play an important role in the hypoxia signal-transduction pathway that leads to synthesis of HIF-1 alpha and HIF-1 beta proteins and the induction of HIF-1 DNA-binding activity.

2-Aminopurine↗
PubMed1995

Effect of altered redox states on expression and DNA-binding activity of hypoxia-inducible factor 1.

Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric basic helix-loop-helix (bHLH)-PAS DNA-binding protein tightly regulated by cellular oxygen tension. Cellular redox states are related to hypoxia by changes in the expression of redox regulated genes and the generation of reactive oxygen intermediates. Here, we provide evidence that alteration of cellular redox states by treating cells with H2O2 or dithiothreitol impairs hypoxia signaling mechanisms and the expression of HIF-1 alpha protein in hypoxic cells. In addition, HIF-1 DNA-binding activity in vitro is sensitive to oxidizing reagents diamide and H2O2 and the alkylating agent N-ethylmaleimide. The activity of N-ethylmaleimide-inactivated HIF-1 can be partially restored by addition of nuclear extract from nonhypoxic cells.

Alkylating Agents↗
PubMed1995

Hypoxia-inducible factor 1 is a basic-helix-loop-helix-PAS heterodimer regulated by cellular O2 tension.

Hypoxia-inducible factor 1 (HIF-1) is found in mammalian cells cultured under reduced O2 tension and is necessary for transcriptional activation mediated by the erythropoietin gene enhancer in hypoxic cells. We show that both HIF-1 subunits are basic-helix-loop-helix proteins containing a PAS domain, defined by its presence in the Drosophila Per and Sim proteins and in the mammalian ARNT and AHR proteins. HIF-1 alpha is most closely related to Sim. HIF-1 beta is a series of ARNT gene products, which can thus heterodimerize with either HIF-1 alpha or AHR. HIF-1 alpha and HIF-1 beta (ARNT) RNA and protein levels were induced in cells exposed to 1% O2 and decayed rapidly upon return of the cells to 20% O2, consistent with the role of HIF-1 as a mediator of transcriptional responses to hypoxia.

Amino Acid Sequence↗
PubMed1995

Metaphase and interphase fluorescence in situ hybridization mapping of the rice genome with bacterial artificial chromosomes.

Fluorescence in situ hybridization (FISH) is a powerful tool for physical mapping in human and other mammalian species. However, application of the FISH technique has been limited in plant species, especially for mapping single- or low-copy DNA sequences, due to inconsistent signal production in plant chromosome preparations. Here we demonstrate that bacterial artificial chromosome (BAC) clones can be mapped readily on rice (Oryza sativa L.) chromosomes by FISH. Repetitive DNA sequences in BAC clones can be suppressed efficiently by using rice genomic DNA as a competitor in the hybridization mixture. BAC clones as small as 40 kb were successfully mapped. To demonstrate the application of the FISH technique in physical mapping of plant genomes, both anonymous BAC clones and clones closely linked to a rice bacterial blight-resistance locus, Xa21, were chosen for analysis. The physical location of Xa21 and the relationships among the linked clones were established, thus demonstrating the utility of FISH in plant genome analysis.

Animals↗
PubMed1995

DNA binding and transcriptional properties of wild-type and mutant forms of the homeodomain protein Msx2.

Msx2 is a mammalian homeodomain protein that is expressed during craniofacial development. A proline-to-histidine substitution at residue 148 of human Msx2 results in an autosomal dominant form of craniosynostosis. In this study, both wild-type and mutant Msx2 were shown to specifically bind to a DNA sequence previously identified as a high-affinity binding site for the related homeodomain protein Msx1. In co-transfection assays both wild-type and mutant Msx2 repressed reporter gene transcription in a dose-dependent but binding-site-independent manner. These results provide evidence that Msx2 is a transcriptional repressor and suggest that the mutant form of Msx2 may exert its pathophysiologic effects on craniofacial development by a gain-of-function mechanism.

Base Sequence↗
PubMed1995

Purification and characterization of hypoxia-inducible factor 1.

Hypoxia-inducible factor 1 (HIF-1) is a DNA-binding protein that activates erythropoietin (Epo) gene transcription in Hep3B cells subjected to hypoxia or cobalt chloride treatment. HIF-1 DNA binding activity is also induced by hypoxia or cobalt in non-Epo-producing cells, suggesting a general role for HIF-1 in hypoxia signal transduction and transcriptional regulation. Here we report the biochemical purification of HIF-1 from Epo-producing Hep3B cells and non-Epo-producing HeLa S3 cells. HIF-1 protein was purified 11,250-fold by DEAE ion-exchange and DNA affinity chromatography. Analysis of HIF-1 isolated from a preparative gel shift assay revealed four polypeptides. Peptide mapping of these HIF-1 components demonstrated that 91-, 93-, and 94-kDa polypeptides had similar tryptic maps, whereas the 120-kDa polypeptide had a distinct profile. Glycerol gradient sedimentation analysis suggested that HIF-1 exists predominantly in a heterodimeric form and to a lesser extent as a heterotetramer. Partially purified HIF-1 bound specifically to the wild-type HIF-1 binding site from the EPO enhancer but not to a mutant sequence that lacks hypoxia-inducible enhancer activity. UV cross-linking analysis with purified HIF-1 indicated that both subunits of HIF-1 contact DNA directly. We conclude that in both cobalt chloride-treated HeLa cells and hypoxic Hep3B cells HIF-1 is composed of two different subunits: 120-kDa HIF-1 alpha and 91-94-kDa HIF-1 beta.

Base Sequence↗
PubMed1995

Construction of a rice bacterial artificial chromosome library and identification of clones linked to the Xa-21 disease resistance locus.

A bacterial artificial chromosome (BAC) library consisting of 11,000 clones with an average DNA insert size of 125 kb was constructed from rice nuclear DNA. The BAC clones were stable in E. coli after 100 generations of serial growth. Transformation of the BAC clones by electroporation into E. coli was highly efficient and increased with decreasing size of the DNA inserts. The library was evaluated for the presence of organellar, repeated, and telomeric sequences. A very low percentage (< 0.3%) of the library consisted of chloroplast and mitochondrial clones. Eighteen BACs were identified that hybridized with an Arabidopsis telomere repeat. Sixteen BACs hybridized with the AA genome-specific repetitive sequence pOs48. Twelve clones were isolated that hybridized with three DNA markers linked to the Xa-21 disease resistance locus. The results indicate that the BAC system can be used to clone and manipulate large pieces of plant DNA efficiently.

Arabidopsis↗
PubMed1995

Some fluorescent properties of non-enzymic transamination and measurement of the relative molecular mass of protein.

A procedure for transaminating proteins and removing the transaminated N-terminal residue has been used for studying structure-function relationship of protein (Dixon and Fields 1972, Meth. Enzymol. 25, 409-419). We show that it is convenient for measuring the relative molecular masses of proteins by measuring the glycine formed from glyoxylate during such transamination. Quinoxaline derivatives have been synthesized by the reaction of 2-oxo acids from amino acids reacting with o-phenylenediamine. 2-Oxo acids transaminated from amino acids fluoresced at around 405 nm, depending on the nature of residual side groups. The emission maximum of 3-benzyl-2-hydroxy-quinoxaline from the reaction of o-phenylenediamine with phenylpyruvate was at 363 nm. The fluorescent derivatives have been used to study conformational changes of peptides and to detect whether or not N-termini of proteins were blocked.

Glycine↗
PubMed1994

Transcriptional regulation of genes encoding glycolytic enzymes by hypoxia-inducible factor 1.

Hypoxia-inducible factor 1 (HIF-1) activates erythropoietin gene transcription in Hep3B cells subjected to hypoxia. HIF-1 activity is also induced by hypoxia in non-erythropoietin-producing cells, suggesting a more general regulatory role. We now report that RNAs encoding the glycolytic enzymes aldolase A (ALDA), phosphoglycerate kinase 1 (PGK1), and pyruvate kinase M were induced by exposure of Hep3B or HeLa cells to inducers of HIF-1 (1% O2, cobalt chloride, or desferrioxamine), whereas cycloheximide blocked induction of glycolytic RNAs and HIF-1 activity. Oligonucleotides from the ALDA, PGK1, enolase 1, lactate dehydrogenase A, and phosphofructokinase L (PFKL) genes, containing sequences similar to the HIF-1 binding site in the erythropoietin enhancer, specifically bound HIF-1 present in crude nuclear extracts or affinity-purified preparations. Sequences from the ALDA, PFKL, and PGK1 genes containing HIF-1 binding sites mediated hypoxia-inducible transcription in transient expression assays. These results support the role of HIF-1 as a mediator of adaptive responses to hypoxia that underlie cellular and systemic oxygen homeostasis.

Base Sequence↗
PubMed1994

Transcription of Djun from D. melanogaster is positively regulated by DTF-1, AP-1, and CREB binding sites.

Djun is the homolog of the mammalian proto-oncogene jun in D. melanogaster, where it encodes a component of an AP-1-like nuclear DNA binding protein, or transcription factor. Djun, unlike its vertebrate counterparts, contains an intron in its 5' noncoding region. The expression of Djun in cultured Schneider line 2 cells is controlled by multiple cis-acting elements in its promoter region and the 5' noncoding region of the transcription unit. A 43-bp 5' upstream promoter region is necessary for the transcription activity of Djun. Deletion of this fragment decreased transcriptional activity by 67-fold. This region includes a TATA box and a sequence similar to the Drosophila transcription factor 1 (DTF-1) consensus sequence (GCAACAT/GC/C). A large DNase I footprint covering both the DTF-1 binding site and the TATA box was detected in this region when incubated with nuclear extract from Drosophila embryos, suggesting interactions with related transcription factors. This 43-bp sequence alone, containing the DTF-1 binding site and TATA box, however, is not sufficient for transcription activity. An 80-bp sequence including the start of transcription has considerable basal activity. An intragenic region containing an AP-1 site and a CRE site modulates or fine tunes activity of the promoter. Its activity as an enhancer is reduced when moved upstream in either orientation. An extragenic region containing two AP-1 sites similarly affects promoter activity.

Animals↗
PubMed1994

RFLP mapping of genes conferring complete and partial resistance to blast in a durably resistant rice cultivar.

Moroberekan, a japonica rice cultivar with durable resistance to blast disease in Asia, was crossed to the highly susceptible indica cultivar, CO39, and 281 F7 recombinant inbred (RI) lines were produced by single seed descent. The population was evaluated for blast resistance in the greenhouse and the field, and was analyzed with 127 restriction fragment length polymorphism (RFLP) markers. Two dominant loci associated with qualitative resistance to five isolates of the fungus were tentatively named Pi-5(t) and Pi-7(t). They were mapped on chromosomes 4 and 11, respectively. To identify quantitative trait loci (QTLs) affecting partial resistance, RI lines were inoculated with isolate PO6-6 of Pyricularia oryzae in polycyclic tests. Ten chromosomal segments were found to be associated with effects on lesion number (P < 0.0001 and LOD > 6.0). Three of the markers associated with QTLs for partial resistance had been reported to be linked to complete blast resistance in previous studies. QTLs identified in greenhouse tests were good predictors of blast resistance at two field sites. This study illustrates the usefulness of RI lines for mapping a complex trait such as blast resistance and suggests that durable resistance in the traditional variety, Moroberekan, involves a complex of genes associated with both partial and complete resistance.

Chromosome Mapping↗
PubMed1994

Bilateral progressive obliterative retinal vasculitis.

In this paper, 10 cases of a special type of retinal vasculitis are reported, which was characterized by progressive obliteration of vessels in both eyes, developed from the periphery to the posterior ploy, and was complicated by vitreous hemorrhage (5 eyes) and neovascular glaucoma (5 eyes) in later stage. The visual acuity was 0.05 in 10 eyes (50%). Argon laser photocoagulation seemed to be able to retard the natural course of the disease. Fundus changes, differential diagnosis and treatment etc are discussed in detail.

Adult↗