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Articoli di riviste sul tema "Virus-induced enzymes"
1
Knobil, Katharine, Augustine M. K. Choi, Gordon W. Weigand e David B. Jacoby. "Role of oxidants in influenza virus-induced gene expression". American Journal of Physiology-Lung Cellular and Molecular Physiology 274, n. 1 (1 gennaio 1998): L134—L142. http://dx.doi.org/10.1152/ajplung.1998.274.1.l134.
Testo completoAbstract (sommario):
Influenza virus-induced epithelial damage may be mediated, in part, by reactive oxygen intermediates (ROIs). In this study, we investigated the role of ROIs in the influenza virus-induced gene expression of antioxidant enzymes and in the activation of nuclear factor-κB (NF-κB), an oxidant-sensitive transcriptional factor. Influenza virus infection increased production of intracellular ROIs in A549 pulmonary epithelial cells. Induction of manganese superoxide dismutase (MnSOD) mRNA correlated with increased MnSOD protein and enzyme activity. Influenza virus infection also activated NF-κB binding as determined by an electrophoretic mobility shift assay. Pretreatment of A549 cells with N-acetyl-l-cysteine attenuated virus-induced NF-κB activation and interleukin (IL)-8 mRNA induction but did not block induction of MnSOD mRNA. In contrast, pyrrolidine dithiocarbamate blocked activation of NF-κB and induction of MnSOD and IL-8 mRNAs. Treatment with pyrrolidine dithiocarbamate also markedly decreased virus-induced cell death. Thus oxidants are involved in influenza virus-induced activation of NF-κB, in the expression of IL-8 and MnSOD, and in virus-induced cell death.
2
Seo, Young-Jin, Celeste Blake, Stephen Alexander e Bumsuk Hahm. "Sphingosine 1-Phosphate-Metabolizing Enzymes Control Influenza Virus Propagation and Viral Cytopathogenicity". Journal of Virology 84, n. 16 (2 giugno 2010): 8124–31. http://dx.doi.org/10.1128/jvi.00510-10.
Testo completoAbstract (sommario):
ABSTRACT Sphingosine 1-phosphate (S1P)-metabolizing enzymes regulate the level of sphingolipids and have important biological functions. However, the effects of S1P-metabolizing enzymes on host defense against invading viruses remain unknown. In this study, we investigated the role of S1P-metabolizing enzymes in modulating cellular responses to influenza virus infection. Overexpression of S1P lyase (SPL), which induces the degradation of S1P, interfered with the amplification of infectious influenza virus. Accordingly, SPL-overexpressing cells were much more resistant than control cells to the cytopathic effects caused by influenza virus infection. SPL-mediated inhibition of virus-induced cell death was supported by impairment of the upregulation of the proapoptotic protein Bax, a critical factor for influenza virus cytopathogenicity. Importantly, influenza virus infection of SPL-overexpressing cells induced rapid activation of extracellular signal-regulated kinase (ERK) and STAT1 but not of p38 mitogen-activated protein kinase (MAPK), Akt, or c-Jun N-terminal kinase (JNK). Blockade of STAT1 expression or inhibition of Janus kinase (JAK) activity elevated the level of influenza virus replication in the cells, indicating that SPL protects cells from influenza virus via the activation of JAK/STAT signaling. In contrast to that of SPL, the overexpression of S1P-producing sphingosine kinase 1 heightened the cells' susceptibility to influenza virus infection, an effect that was reversed by the inhibition of its kinase activity, representing opposed enzymatic activity. These findings indicate that the modulation of S1P-metabolizing enzymes is crucial for controlling the host defense against infection with influenza virus. Thus, S1P-metabolizing enzymes are novel potential targets for the treatment of diseases caused by influenza virus infection.
3
Bornemann, Claus, e Hartmut Follmann. "Deoxyribonucleotide Synthesis in Phycovirus-Infected Green Algae. A New Virus-Induced Ribonucleotide Reductase". Zeitschrift für Naturforschung C 48, n. 1-2 (1 febbraio 1993): 113–18. http://dx.doi.org/10.1515/znc-1993-1-222.
Testo completoAbstract (sommario):
Infection of Chlorella-like green algae with freshwater phycoviruses is associated with a large and rapid demand for DNA precursors which cannot be met by the algal deoxyribonucleotide-synthesizing enzymes. We have demonstrated in these cells an up to ten-fold increase of the key enzyme, ribonucleotide reductase, 1-2 h post infection. The enzyme activity has been partially enriched from cell extracts. In vitro, it differs from that of uninfected algae in three characteristic parameters, viz. eight-fold higher resistance to millimolar hydroxyurea concentrations, much higher optimum concentration of an allosteric effector nucleotide, thymidine triphosphate, and an unusually low temperature optimum at 20 °C. We conclude that the large DNA phycoviruses, like Herpes and pox viruses, code for their own specific ribonucleotide reductase.
4
Martínez-Costas, José, Claudia González-López, Vikram N. Vakharia e Javier Benavente. "Possible Involvement of the Double-Stranded RNA-Binding Core Protein ςA in the Resistance of Avian Reovirus to Interferon". Journal of Virology 74, n. 3 (1 febbraio 2000): 1124–31. http://dx.doi.org/10.1128/jvi.74.3.1124-1131.2000.
Testo completoAbstract (sommario):
ABSTRACT Treatment of primary cultures of chicken embryo fibroblasts with a recombinant chicken alpha/beta interferon (rcIFN) induces an antiviral state that causes a strong inhibition of vaccinia virus and vesicular stomatitis virus replication but has no effect on avian reovirus S1133 replication. The fact that avian reovirus polypeptides are synthesized normally in rcIFN-treated cells prompted us to investigate whether this virus expresses factors that interfere with the activation and/or the activity of the IFN-induced, double-stranded RNA (dsRNA)-dependent enzymes. Our results demonstrate that extracts of avian-reovirus-infected cells, but not those of uninfected cells, are able to relieve the translation-inhibitory activity of dsRNA in reticulocyte lysates, by blocking the activation of the dsRNA-dependent enzymes. In addition, our results show that protein ςA, an S1133 core polypeptide, binds to dsRNA in an irreversible manner and that clearing this protein from extracts of infected cells abolishes their protranslational capacity. Taken together, our results raise the interesting possibility that protein ςA antagonizes the IFN-induced cellular response against avian reovirus by blocking the intracellular activation of enzyme pathways dependent on dsRNA, as has been suggested for several other viral dsRNA-binding proteins.
5
Hsiang, Tien-Ying, Chen Zhao e Robert M. Krug. "Interferon-Induced ISG15 Conjugation Inhibits Influenza A Virus Gene Expression and Replication in Human Cells". Journal of Virology 83, n. 12 (8 aprile 2009): 5971–77. http://dx.doi.org/10.1128/jvi.01667-08.
Testo completoAbstract (sommario):
ABSTRACT The ubiquitin-like ISG15 protein, as well as its conjugating enzymes, is induced by type I interferons (IFNs). Experiments using ISG15 knockout (ISG15−/−) mice established that ISG15 and/or its conjugation inhibits the replication of influenza A virus. However, in contrast to the virus inhibition results for mice, the rates of virus replication in ISG15+/+ and ISG15−/− mouse embryo fibroblasts in tissue culture were similar. Here we focus on human tissue culture cells and on the effect of ISG15 and/or its conjugation on influenza A virus gene expression and replication in such cells. We demonstrate that IFN-induced antiviral activity against influenza A virus in human cells is significantly alleviated by inhibiting ISG15 conjugation using small interfering RNAs directed against ISG15-conjugating enzymes. IFN-induced antiviral activity against influenza A virus protein synthesis was reduced 5- to 20-fold by suppressing ISG15 conjugation. The amounts of the viral proteins that were restored by these siRNA treatments were approximately 40 to 50% of the amounts produced in cells that were not pretreated with IFN. Further, we show that ISG15 conjugation inhibits influenza A virus replication 10- to 20-fold at early times after infection in human cells. These results show that ISG15 conjugation plays a substantial role in the antiviral state induced by IFN in human cells. In contrast, we show that in mouse embryo fibroblasts ISG15 conjugation not only does not affect influenza A virus replication but also does not contribute to the IFN-induced antiviral activity against influenza A virus gene expression.
6
Choi, A. M., K. Knobil, S. L. Otterbein, D. A. Eastman e D. B. Jacoby. "Oxidant stress responses in influenza virus pneumonia: gene expression and transcription factor activation". American Journal of Physiology-Lung Cellular and Molecular Physiology 271, n. 3 (1 settembre 1996): L383—L391. http://dx.doi.org/10.1152/ajplung.1996.271.3.l383.
Testo completoAbstract (sommario):
The pathogenesis of influenza virus infections of the lungs is in part mediated by oxidative stress. Such infections might therefore be expected to induce expression of stress-response genes and genes encoding antioxidant enzymes and to activate transcriptional regulatory proteins. Mice (C57B1/6 and C3H/HeJ) were infected intranasally with influenza virus A/PR/8/34 (H1N1). Expression of the genes encoding the antioxidant enzymes manganese superoxide dismutase (Mn- SOD), indoleamine-2, 3-dioxygenase (IDO), heme oxygenase-1, and glutathione peroxidase were increased in the lungs of virus-infected animals. Cu/ZnSOD and catalase mRNA were not induced by viral infection. Activation of the transcriptional regulatory proteins AP-1, C/EBP, and NF-kappa B (which are known to be affected by oxidant stress) was demonstrated by electrophoretic mobility shift assay after viral infection. In the case of MnSOD, despite increased gene expression enzyme activity was not increased. In contrast, for heme oxygenase-1 both mRNA and activity were increased. C3H/ HeJ and C57B1/6 mice, which are known to have different responses to other types of oxidant stress, also differed in their responses to viral infection. Induction of heme oxygenase-1 expression was greater in C57B1/6 mice than in C3H/ HeJ mice, although inhibiting this enzyme did not alter virus-induced mortality. In contrast, IDO was more strongly induced in C3H/HeJ mice. Activation of NF-kappa B was much more marked in C57B1/6 mice than in C3H/HeJ mice. Although virus replication and inflammatory responses were equivalent in the two strains, lung injury (as measured by wet-to-dry wt ratios) and mortality were greater in C3H/HeJ mice than in C57B1/6 mice, a difference that may be related to differing oxidant stress responses. Thus influenza pneumonia causes an oxidant stress response in the lungs, the nature of which is determined in part by the genetic background of the host.
7
Knoester, Marga. "Virus-Induced Gene Expression for Enzymes of Ethylene Biosynthesis in Hypersensitively Reacting Tobacco". Molecular Plant-Microbe Interactions 8, n. 1 (1995): 177. http://dx.doi.org/10.1094/mpmi-8-0177.
Testo completo
8
Staley, S., Marcela Smid, Sarah Dotters-Katz e Elizabeth Stringer. "Epstein–Barr Virus-Induced Mononucleosis as an Imitator of Severe Preeclampsia". American Journal of Perinatology Reports 07, n. 01 (gennaio 2017): e5-e7. http://dx.doi.org/10.1055/s-0036-1597265.
Testo completoAbstract (sommario):
Background In pregnancy, conditions presenting with hematologic abnormalities, transaminitis, and proteinuria pose diagnostic challenges in pregnancy. Case We present the case of an 18-year-old woman, G1P0, at 33 weeks' gestation with fever of unknown cause, who developed progressively elevated liver enzymes, proteinuria, and thrombocytopenia, due to Epstein–Barr virus (EBV) infection. Conclusion Acute infection with EBV should be included in the differential diagnosis of preeclampsia with severe features, particularly in the setting of fever. Supportive treatment and observation may prevent iatrogenic preterm birth.
9
Drecktrah, Daniel, e William J. Brown. "Phospholipase A2Antagonists Inhibit Nocodazole-induced Golgi Ministack Formation: Evidence of an ER Intermediate and Constitutive Cycling". Molecular Biology of the Cell 10, n. 12 (dicembre 1999): 4021–32. http://dx.doi.org/10.1091/mbc.10.12.4021.
Testo completoAbstract (sommario):
Evidence has been presented both for and against obligate retrograde movement of resident Golgi proteins through the endoplasmic reticulum (ER) during nocodazole-induced Golgi ministack formation. Here, we studied the nocodazole-induced formation of ministacks using phospholipase A2(PLA2) antagonists, which have been shown previously to inhibit brefeldin A–stimulated Golgi-to-ER retrograde transport. Examination of clone 9 rat hepatocytes by immunofluorescence and immunoelectron microscopy revealed that a subset of PLA2antagonists prevented nocodazole-induced ministack formation by inhibiting two different trafficking pathways for resident Golgi enzymes; at 25 μM, retrograde Golgi-to-ER transport was inhibited, whereas at 5 μM, Golgi-to-ER trafficking was permitted, but resident Golgi enzymes accumulated in the ER. Moreover, resident Golgi enzymes gradually redistributed from the juxtanuclear Golgi or Golgi ministacks to the ER in cells treated with these PLA2antagonists alone. Not only was ER-to-Golgi transport of resident Golgi enzymes inhibited in cells treated with these PLA2antagonists, but transport of the vesicular stomatitis virus G protein out of the ER was also prevented. These results support a model of obligate retrograde recycling of Golgi resident enzymes during nocodazole-induced ministack formation and provide additional evidence that resident Golgi enzymes slowly and constitutively cycle between the Golgi and ER.
10
Wijekoon, Champa P., e Peter J. Facchini. "Systematic knockdown of morphine pathway enzymes in opium poppy using virus-induced gene silencing". Plant Journal 69, n. 6 (28 dicembre 2011): 1052–63. http://dx.doi.org/10.1111/j.1365-313x.2011.04855.x.
Testo completoTesi sul tema "Virus-induced enzymes"
1
Torok, Valeria Anna. "Biological and molecular variation among isolates of pea seed borne mosaic virus". Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09pht686.pdf.
Testo completoAbstract (sommario):
Corrigendum inserted at the back. Includes bibliographical references (leaves 133-158). Ch. 1. General introduction -- ch. 2. General materials and methods -- ch. 3. Biological characterisation of Australian PSbMV isolates -- ch. 4. Developing nucleic acid based diagnostics for PSbMV -- ch. 5. Detection of PSbMV isolates by RT-PCR and RFLP analysis -- ch. 6. Developing an internal control for PSbMV RT-PCR -- ch. 7. Molecular analysis of the PSbMV VPG -- ch. 8. PSbMV sequence and phylogenetic analysis -- ch. 9. General discussion Sixteen pea seed borne mosaic virus (PSbMV) isolates were collected between 1995 and 1998. These isolates were biologically distinct yet serologically indistinguishable. The conclusion is that PSbMV is widespread and occurs at a low incidence in Australia. Reports sequence information on new isolates of PSbMV which has allowed genomic regions to be identified which distinguish PSbMV pathotypes and isolates; and, to the development of PSbMV nucleic acid hybridisation and RT-PCR assays.
2
Oh, Jun Seok. "Critical Roles of Cytomegalovirus-Induced Natural Killer Cells in Chronic Hepatitis C Virus Infection and Rituximab-Mediated Cancer Therapy". Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36228.
Testo completoAbstract (sommario):
Natural Killer (NK) cells, members of the innate lymphoid cells (ILCs), are known to play an important role in the defense against foreign cells and abnormal host cells that have arisen due to viral infection or cancer inducing mutations. The typical immune response of NK cells involves the release of cytotoxic granules containing perforin and granzyme, and the secretion of immune-regulatory cytokines such as interferon gamma (IFN-γ). Unlike the adaptive lymphocytes such as T cells and B cells, NK cells do not require prior sensitization, enabling them to initiate an immune response much faster. This unique feature of NK cells is made possible by the utilization of an array of germline encoded receptors; but on the other hand, it limits NK cells ability to respond against rapidly evolving pathogens. NK cells overcome this shortcoming with an antibody-assisted process called antibody dependent cellular cytotoxicity (ADCC).
A novel subset of human NK cells, which displays potent and broad antiviral responsiveness in concert with virus-specific antibodies, was recently discovered in cytomegalovirus positive (CMV+) individuals. This NK cell subset, called g-NK cell, was characterized by a deficiency in the expression of FcεRIγ, an adaptor protein that associates with CD16 which enables ADCC. Surprisingly, despite this deficiency, g-NK cells displayed an enhanced ADCC as compared to their conventional counterparts. Furthermore, having a long-lasting memory-like NK-cell phenotype suggests a role for g-NK cells in chronic infections.
This study investigates the importance of g-NK-cells in clinical settings, first by investigating whether the presence of g-NK cells is associated with the magnitude of liver disease during chronic hepatitis C virus (HCV) infection. Analysis of g-NK cell proportions and function in the peripheral blood mononuclear cells (PBMCs) of healthy controls and chronic HCV subjects showed that chronic HCV subjects had slightly lower proportions of g-NK cells, while having similarly enhanced ADCC responses compared to conventional NK cells. Notably, among CMV+ chronic HCV patients, lower levels of liver enzymes and fibrosis were found in those possessing g-NK cells. g-NK cells were predominant among the CD56neg NK cell population often found in chronic HCV patients, suggesting their involvement in the immune response against HCV.
Rituximab is a chimeric anti-CD20 antibody used to treat B cell lymphoma patients; and studies have suggested that its efficacy is associated with the ADCC potency and CD16 affinity. Since g-NK cells are characterized by their superior ADCC compared to their conventional counterpart, I decided to investigate whether the presence of g-NK cells can improve the effectiveness of rituximab against malignant B cells in the context of lymphoma and leukemia. The analysis of g-NK cells’ ADCC response against rituximab-coated lymphoma cell lines and B cells from a CLL patient indicated a superior ADCC by g-NK cells compared to their conventional NK cell counterparts.
Taken together, for the first time, my findings indicate that the presence of g-NK cells in CMV+ individuals is associated with milder liver disease in chronic HCV infection. In addition, an enhanced ADCC response by g-NK cells upon encountering rituximab coated target cells suggests the beneficial roles of g-NK cells, and opens an avenue for novel therapeutic approaches where g-NK cells can be utilized to treat persistent diseases such as chronic viral infection and cancer.
3
Black, Margaret E. "Structural and functional dissection of the vaccinia virus thymidine kinase enzyme". Thesis, 1991. http://hdl.handle.net/1957/37105.
Testo completoAbstract (sommario):
Thymidine kinase is a key enzyme in the nucleotide salvage pathway,
catalyzing the production of dTMP from thymidine and ATP. In order to
identify the structural features of the TK protein and/or primary amino
acid sequences which contribute to the catalytic and regulatory activities of
this enzyme, an in vitro transcription and translation system has been used
in concert with protein engineering techniques for the production and
phenotypic characterization of mutant and wild-type TK enzymes. Because
of discrepancies in the literature regarding the quaternary structure of the
VVTK, the native molecular weight and quaternary structure was
determined to be an 80kDa homotetrameric enzyme by glycerol gradient
fractionation, gel filtration and glutaraldehyde cross-linking analyses.
Computer-assisted alignment of the predicted amino acid sequences
derived from cellular and poxvirus TK genes identified seven highly-conserved
domains distributed throughout the VVTK polypeptide
(domains I-VII). Domain I (amino acid residues 11-18 ) exhibits a high
degree of similarity to both ATP and GTP binding site consensus sequences,
although the VVTK utilizes only ATP as a phosphate donor. Site directed
mutagenesis and ATP-agarose affinity chromatography techniques were
employed to confirm that this region was responsible for ATP binding and
to determine which amino acids were essential for efficient binding.
The TK gene (tdk) from E. coli was isolated and sequenced to serve as
a prokaryotic enzyme with which to compare VVTK. The alignment
revealed only 23% shared identity with VVTK and, interestingly, the
identical and similar residues were clustered into three of the seven
domains identified previously (domains I, III and VII).
Preliminary evidence supports domain III (residues 78-90) as a
putative magnesium binding site and that a highly conserved cysteine
residue (cysteine 170) within domain VII (residues 168-171) may be a
component of the catalytic site. Secondary structure alignment between
Herpes Simplex Virus (HSV) TK and monkeypox TK (a close relative of
VVTK) revealed that the putative nucleoside binding site of HSVTK aligns
with residues within domain IV. Replacement of a VVTK residue (Q114)
with the corresponding residue of HSVTK (an aspartic acid) greatly alters
the substrate specificity and dTTP sensitivity of VVTK.Graduation date: 1991
4
Hu, Chih-Chieh, e 胡智傑. "The role of proline synthesis enzymes under stresses via virus-induced gene silencing in tobacco". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/84132531497829537955.
Testo completoAbstract (sommario):
碩士國立臺灣大學
農業化學研究所
96
Proline accumulation is wide spread phenomenon in stressed plants. Proline could be synthesized with Δ1-pyrroline-5-carboxylate synthetase (P5CS) from glutamate and with ornithine-δ-aminotransferase (OAT) from ornithine in plants. It dose don not know well about the role of P5CS and OAT in stressed plants. The aim of this thesis is to investigate which enzyme is more important for proline synthesis, and what is the possible function of these enzymes in response to abiotic stress. We used Tobacco mosaic virus (TMV) as vector with the insertion of proline metabolized related gene fragments to decrease the expression of P5CS (TMV-antiP5CS) , OAT (TMV-antiOAT), or both of P5CS and OAT (TMV-antiP5CS＋antiOAT) in 10 weeks old tobacco via the mechanism of VIGS (virus-induced gene silencing). The tobacco leaf discs taking form first and second leaf above the inoculated leaf were treated with 29％PEG (polyethylene glycol), 100 μM abscisic acid (ABA), or 50 μM CdCl2 to mimic three abiotic stresses. Under PEG treatment, the proline level of tobacco leaf discs inoculated with TMV-P5CS or TMV-OAT decreased about 80-90％ and 5-15％ respectively. The changes of proline level under ABA or Cd treatment were similar to PEG treatment. It is suggests that P5CS could be the major enzyme for proline accumulation under heavy metal stress. In order to investigate the possible function of P5CS and OAT expression in stressed plant, the chlorophyll and MDA content of leaf discs treated with VIGS were analyzed. The degradation of chlorophyll in TMV-antiP5CS inoculated tobacco leaf discs was faster than in TMV-GFP under PEG treatment. But the degradation in TMV-antiOAT was slower than in TMV-GFP. There was no difference in MDA content among all VIGS treated plant under stresses. It is noticed that the content of polyamine increased in TMV-antiOAT inoculated tobacco leaf discs under osmotic stress. In summary, P5CS is the major enzyme of proline accumulation under osmotic stress, ABA or heavy metal stress. OAT participates the proline accumulation only in osmotic stress. Under osmotic stress, inhibiting P5CS pathway can improve the rate of chlorophyll degradation. But inhibiting OAT pathway can delay the rate of chlorophyll degradation that migh be related to the increase of polyamine content in tobacco leaf discs.
5
Bao, Kogan K. "Kinetic analysis of avian sarcoma virus integrase in the presteady-state". Thesis, 2002. http://hdl.handle.net/1957/30239.
Testo completoAbstract (sommario):
Integrase catalyzes insertion of a retroviral genome into the host chromosome.
Following reverse transcription, integrase binds specifically to the ends of the duplex retroviral
DNA, endonucleolytically cleaves two nucleotides from each 3'-end (the processing activity),
and inserts these ends into the host DNA (the joining activity) in a concerted manner.
Additionally, it has been observed that integrase can catalyze the removal of inserted viral ends
(the disintegration activity) in vitro. Presteady-state experiments were performed using synapsed
substrates to probe the processing reaction and a disintegration substrate to determine the
number of protomers in a functional multimeric complex. In single-turnover studies, a novel
"splicing" reaction was observed that revealed complications with accurate quantification of
enzymatic activity using the synapsed substrates. The splicing reaction was further used to gain
insight into the selection of nucleophiles and electrophiles at the binding site. To reduce the
complexity introduced by the integrase-catalyzed splicing reaction, 5'-5' reverse-polarity
synapsed substrates were designed that were not susceptible to the splicing reaction and that
allowed direct comparison of LTR ends simultaneously bound at the active site. Analysis of the
presteady-state assays using these reverse-polarity substrates revealed that the concurrent binding
of the biologically relevant U3/U5 combination of viral ends facilitates maximal activity of the
processing reaction. A disintegration substrate was used in presteady-state active site titrations to
determine a reaction stoichiometry of four integrase protomers per one substrate molecule for
the disintegration reaction. A tetrameric active complex was then confirmed using atomic force
microscopy to image integrase-DNA complexes during the first catalytic turnover. The
observed increase of the tetramer population in the presence of substrate DNA demonstrates that
the binding of the disintegration substrate induces assembly of the active tetramer and suggests
that tetramer assembly may be an integral and dynamic component of the catalytic pathway.Graduation date: 2003
6
Torok, Valeria Anna. "Biological and molecular variation among isolates of pea seed borne mosaic virus / Valeria Anna Torok". Thesis, 2001. http://hdl.handle.net/2440/21692.
Testo completoAbstract (sommario):
Corrigendum inserted at the back.Includes bibliographical references (leaves 133-158).
xvi, 158 leaves : ill., col. map ; 30 cm.
Sixteen pea seed borne mosaic virus (PSbMV) isolates were collected between 1995 and 1998. These isolates were biologically distinct yet serologically indistinguishable. The conclusion is that PSbMV is widespread and occurs at a low incidence in Australia. Reports sequence information on new isolates of PSbMV which has allowed genomic regions to be identified which distinguish PSbMV pathotypes and isolates; and, to the development of PSbMV nucleic acid hybridisation and RT-PCR assays.
Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2001
7
Kim, JuHyun. "Organization of the T4 dNTP synthetase complex at DNA replication sites". Thesis, 2005. http://hdl.handle.net/1957/29969.
Testo completoAbstract (sommario):
With respect to a multienzyme complex of deoxyribonucleoside triphosphate
(dNTP) synthesis somehow juxtaposed with DNA replication sites, our laboratory
has demonstrated the existence of a multienzyme complex in T4-infected E. coli,
named the T4 dNTP synthetase complex, but the idea of direct linkage of dNTP
synthesis to DNA replication and organization of the complex has not been well
established. This study had two objectives. The first objective was to test the specific
hypothesis that gp32, the single-stranded DNA binding protein encoded by gene 32,
plays a role in recruiting enzymes of dNTP synthesis to the replisome and in
organizing the dNTP synthetase complex. By use of two newly created gene 32
mutants along with several experimental approaches, DNA-cellulose
chromatography, coimmunoprecipitation, and glutathione-S-transferase pull downs,
interactions of gp32 with thymidylate synthase (gptd), ribonucleotide reductase
(gpnrdA/B), and E. coli NDP kinase have been identified. These results support the
hypothesis that gp32 helps to recruit enzymes of dNTP synthesis to DNA replication
sites.
As the second objective, I investigated contributions of two host proteins, E. coli
nueleoside diphosphate kinase (NDP kinase) and adenylate kinase (Adk), to the
organization of the complex. As an important step to understand roles of E. coli NDP
kinase in the complex, I identified direct interactions of E. coli NDP kinase with
gpnrdA/B, dCMP hydroxymethylase (gp42), and dihydrofolate reductase (gpfrd) by
means of coimmunoprecipitation and glutathione-S-transferase pull-down
experiments. Interestingly, these interactions were influenced by the presence of
substrate nucleotides or an analog for E. coli NDP kinase, suggesting that metabolite
flux may affect the preference of E. coli NDP kinase binding to enzymes in the
complex in vivo. Meanwhile, Adk involvement in DNA precursor synthesis has been
suggested, particularly in phage T4-infected E. coli, from observations of increased
thermostability of temperature-sensitive Adk in situ. The involvement of E. coil Adk
in the complex was demonstrated by identifying some proteins of the T4 dNTP
synthetase complexgp42, dNMP kinase (gpl), gpfrd, and E. coli NDP
kinasedirectly interacting with Adk, implying that E. coil Adk would be properly
located in the complex to efficiently carry out the conversion of dNDPs to dNTPs.
This implication was supported by measurements of T4 DNA synthesis.
Taken together, this research strongly supports the idea of connection of dNTP
synthesis to DNA replication and allows us to take a step toward understanding the
organization of the complex at DNA replication sites.Graduation date: 2005
8
侯品全. "Investigation of the roles of polyamine biosynthetic enzymes in growth and developmental programs in Nicotiana benthamiana by virus-induced gene silencing". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/66899268862920599309.
Testo completoAbstract (sommario):
碩士國立彰化師範大學
生物學系
101
Polyamines are implicated in a wide array of fundamental processes in plants such as adaptation and tolerance to environmental stresses. However, their roles in plant growth and developmental programs have not been fully elucidated. In this study, Nicotiana benthamiana was used as a model plants to investigate the roles of polyamine biosynthesis in developmental programs. Genes encoding polyamine biosynthesis enzymes were knocking down by using the VIGS (virus-induced gene silencing) strategies. Analysis of plant growth and development programs was carried out in these gene-silencing plants. Subcellular localization of the polyamine biosynthesis enzyme labeled with green fluorescent protein was performed to observe the localization and deduce the mechanism of action. The effects of VIGS on gene expression level were validated by RT-PCR. When compared with the vector-control lines, the expression of genes encoding diamine synthase ADC (arginine decarboxylase), ODC (ornithine decarboxylase) and synthase triamine SPDS (spermidine) was significantly decreased. In NbSPDS-silenced plants, the growth and developmental programs were impaired such as dwarfing, delayed flowering, abnormal style development and reduced the number of fruit capsules. The NbADC- and NbODC-silenced plants exhibited normal morphology. By RT-PCR analysis of polyamine gene expression in different tissues, it was found that NbADC gene was expressed in young leaves, flowers, roots and shoot apex. The expression of NbODC and NbSPDS genes were relatively higher in flower and shoot apex. HPLC analysis of polyamine content showed that the content of spermidine was decreased in the NbSPDS-silenced plants when compared with the vector-control plants. In summary, this study suggests that spermidine plays an important role in the regulation of growth and developmental programs in plants.
9
Wu, Wei-Zhi, e 吳偉誌. "Investigating the roles of polyamine-spermidine biosynthetic enzyme and nitric oxide in root growth of Nicotiana benthamiana by virus-induced gene silencing". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/r5ae94.
Testo completoAbstract (sommario):
碩士國立彰化師範大學
生物學系
102
Polyamines and the biosynthesis of the corresponding enzymes have been implicated in environmental stresses and plant growth. Another NO (Nitric oxide) is a highly diffusible gaseous free radical involved in plant stress-related substance. However, the roles of polyamine and nitric oxide in root growth have not been fully elucidated. In this study, Nicotiana benthamiana was used as a model plants to investigate the roles of polyamine in root growth. Genes encoding polyamine biosynthesis enzymes were knocking down by using the virus-induced gene silencing (VIGS) strategies. Analysis of root growth was carried out in the spermidine synthase (SPDS)-silenced plants. In NbSPDS-silenced plants, it was observed that the number of lateral roots was decreased as compared to vector-control plants. The effects of VIGS on gene expression level were validated by using reverse transcription-PCR. The expression of genes encoding Tobacco rattle virus (TRV) coat protein was detected in the VIGS-treated root tissues. When compared with the vector-control lines, the expression of NbSPDS gene was significantly decreased. The NO level was higher in the NbSPDS-silenced plants than that of vector-control and wild-type plants. High performance liquid chromatography analysis of polyamine content showed that the content of spermidine was decreased in the NbSPDS-silenced plants as compared to the vector-control plants. Moreover, the VIGS technology was apply for abiotic stress. In summary, this study suggests that spermidine may play important roles in root growth.
Libri sul tema "Virus-induced enzymes"
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Morrison, J. M. Virus induced enzymes. Chichester, West Sussex, England: J. Wiley, 1991.
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Black, Margaret E. Structural and functional dissection of the vaccinia virus thymidine kinase enzyme. 1991.
Cerca il testo completoCapitoli di libri sul tema "Virus-induced enzymes"
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Hodgson, H. J. F. "Viral hepatitis—clinical aspects". In Oxford Textbook of Medicine, 2452–60. Oxford University Press, 2010. http://dx.doi.org/10.1093/med/9780199204854.003.152101_update_002.
Testo completoAbstract (sommario):
There are five major hepatitis viruses—A, B, C, D, and E—with the clinical picture depending on the severity of the inflammation induced in the liver, and on whether the virus is cleared from the liver or persists long-term. Acute icteric hepatitis, characterized by jaundice and right upper quadrant abdominal tenderness, is the commonest clinically recognized consequence of infection. This is generally a self-limited condition with low mortality and complete recovery: only hepatitis B and C have the propensity to cause chronic viral hepatitis. Typically, hepatocellular enzyme levels in blood are prominently raised at the time of the onset of symptoms, whilst the serum alkaline phosphatase level is only slightly increased. Specific diagnosis is made by serological testing for particular viruses. Uncomplicated cases recover spontaneously; there is no proven therapy to enhance recovery, but alcohol and potentially hepatotoxic drugs should be withdrawn. Fulminant hepatic failure caused by viral hepatitis has 80% mortality and should be treated (if possible) by orthotopic liver transplantation....
Atti di convegni sul tema "Virus-induced enzymes"
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Vlahos, Ross, Selcuk Yatmaz, Huei J. Seow, Rosa C. Gualano, Zi X. Wong, Peter J. Crack, Steven Bozinovski e Gary P. Anderson. "The Antioxidant Enzyme Glutathione Peroxidase-1 (GPx-1) Reduces Influenza A Virus-Induced Lung Inflammation". In American Thoracic Society 2011 International Conference, May 13-18, 2011 • Denver Colorado. American Thoracic Society, 2011. http://dx.doi.org/10.1164/ajrccm-conference.2011.183.1_meetingabstracts.a2754.
Testo completoRapporti di organizzazioni sul tema "Virus-induced enzymes"
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Meir, Shimon, Michael Reid, Cai-Zhong Jiang, Amnon Lers e Sonia Philosoph-Hadas. Molecular Studies of Postharvest Leaf and Flower Abscission. United States Department of Agriculture, 2005. http://dx.doi.org/10.32747/2005.7696523.bard.
Testo completoAbstract (sommario):
Original objectives: Understanding the regulation of abscission competence by exploring the nature and function of auxin-related gene expression changes in the leaf and pedicelAZs of tomato (as a model system), was the main goal of the previously submitted proposal. We proposed to achieve this goal by using microarray GeneChip analysis, to identify potential target genes for functional analysis by virus-induced gene silencing (VIGS). To increase the potential of accomplishing the objectives of the previously submitted proposal, we were asked by BARD to show feasibility for the use of these two modern techniques in our abscission system. Thus, the following new objectives were outlined for the one-year feasibility study: 1.to demonstrate the feasibility of the VIGS system in tomato to perform functional analysis of known abscission-related genes; 2. to demonstrate that by using microarray analysis we can identify target genes for further VIGS functional analysis. Background to the topic: It is a generally accepted model that auxin flux through the abscission zone (AZ) prevents organ abscission by rendering the AZ insensitive to ethylene. However, the molecular mechanisms responsible for acquisition of abscission competence and the way in which the auxin gradient modulates it are still unknown. Understanding this basic stage of the abscission process may provide us with future tools to control abscission for agricultural applications. Based on our previous study, performed to investigate the molecular changes occurring in leaf and stem AZs of MirabillisJalapaL., we have expanded our research to tomato, using genomic approaches that include modern techniques for gene discovery and functional gene characterization. In our one-year feasibility study, the US team has established a useful system for VIGS in tomato, using vectors based on the tobacco rattle virus (TRV), a Lcreporter gene for silencing (involved in regulation of anthocyanin biosynthesis), and the gene of interest. In parallel, the Israeli team has used the newly released Affymetrix Tomato GeneChip to measure gene expression in AZ and non-AZ tissues at various time points after flower removal, when increased sensitivity to ethylene is acquired prior to abscission (at 0-8 h), and during pedicelabscission (at 14 h). In addition, gene expression was measured in the pedicel AZ pretreated with the ethylene action inhibitor, 1-methylcyclopropene (1-MCP) before flower removal, to block any direct effects of ethylene. Major conclusions, solutions and achievements: 1) The feasibility study unequivocally established that VIGS is an ideal tool for testing the function of genes with putative roles in abscission; 2) The newly released Affymetrix Tomato GeneChip was found to be an excellent tool to identify AZ genes possibly involved in regulation and execution of abscission. The VIGS-based study allowed us to show that TAPG, a polygalacturonase specifically associated with the tomato AZ, is a key enzyme in the abscission process. Using the newly released Affymetrix Tomato GeneChip we have identified potential abscission regulatory genes as well as new AZ-specific genes, the expression of which was modified after flower removal. These include: members of the Aux/IAAgene family, ethylene signal transduction-related genes, early and late expressed transcription factors, genes which encode post-translational regulators whose expression was modified specifically in the AZ, and many additional novel AZ-specific genes which were previously not associated with abscission. This microarray analysis allowed us to select an initial set of target genes for further functional analysis by VIGS. Implications: Our success in achieving the two objectives of this feasibility study provides us with a solid basis for further research outlined in the original proposal. This will significantly increase the probability of success of a full 3-year project. Additionally, our feasibility study yielded highly innovative results, as they represent the first direct demonstration of the functional involvement of a TAPG in abscission, and the first microarray analysis of the abscission process. Using these approaches we could identify a large number of genes involved in abscission regulation, initiation and execution, and in auxin-ethylene cross-talk, which are of great importance, and could enable their potential functional analysis by VIGS.