Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.31 (beta-glucuronidase)
 7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the efficacy of using the Escherichia coli lac operator-repressor system to control plant gene expression. The lacI gene was modified to allow optimal expression in plant cells and then placed downstream of the cauliflower mosaic virus (CaMV) 35S RNA promoter. This construct was introduced into tobacco plants by leaf disc transformation. Transgenic tobacco plants synthesized significant quantities of LacI protein (up to 0.06% of total soluble protein). We have used the E.coli beta-glucuronidase gene (gus) as the reporter gene by placing it downstream of the maize chlorophyll a/b binding protein (CAB) gene promoter. Lac operators were introduced into several positions within the CAB promoter and operator-free plasmid was used as control. Repression was assessed by comparing the transient expression from CAB-operator-gus reporter constructs in protoplasts expressing lac protein, with that in control cells not expressing the repressor. Repression varied between 10 and 90% with different operator positions. Transient assays were also performed in the presence of the inducer, isopropyl-beta-D-thiogalactoside (IPTG). In lacI protoplasts the presence of IPTG manifested itself in a 4.2-fold relief of repression. The study was extended to show regulation of expression in stable transformants. Tobacco transformants harbouring a CAB-operator-gus reporter construct and the lacI gene were shown to have repressed GUS levels, but in the presence of IPTG, repression was relieved 15-fold. We conclude that the lac repressor can enter the plant cell nucleus, find its cognate operator sequence in the chromatin to form a repressor--operator complex and effectively block transcription of a downstream gene.
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PMID:Control of gene expression in tobacco cells using a bacterial operator-repressor system. 156 43

Plasmid vectors designed to facilitate the genetic manipulation of African swine fever virus (ASFV) are described. Our results demonstrate that the beta-glucuronidase enzyme (GUS) can be used to follow gene expression in ASFV-infected cells. Infectious plaques formed by ASFV expressing GUS are visually detectable, thus providing a simple and highly sensitive method for the selection of ASFV recombinants. These and previous results have allowed us to construct two chimeric gene cassettes that constitute the basic tools for the generation of vectors to carry out the deletion of multiple target sequences from the ASFV genome. These cassettes, formed by: (a) a virus promoter; (b) the coding sequence of a reporter gene, either Lac Z or gusA; and (c) a strong signal for the 3' end formation of ASFV mRNAs, can be easily isolated by endonuclease restriction from their corresponding plasmid vectors. A general insertion/coexpression plasmid vector, pEPV2, has also been constructed. pEPV2 facilitates the insertion of foreign genes, together with the Lac Z reporter, into the thymidine kinase locus of ASFV. The functionality of pEPV2 has been tested by generating a recombinant ASFV expressing the luciferase gene. The vectors presented in this report constitute the first reported set of tools for the genetic manipulation of ASFV.
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PMID:Vectors for the genetic manipulation of African swine fever virus. 761 41

A special recombinant of Autographa californica multicapsid nuclear polyhedrosis virus (AcNPV) was designed to study the early histopathological events of baculovirus infection in Spodoptera exigua larvae. This recombinant contained a Drosophila melanogaster heat shock 70 promoter driving an Escherichia coli beta-galactosidase (Lac-Z) reporter gene to monitor the presence of early viral gene expression and a second reporter gene, the E. coli beta-glucuronidase (GUS) gene, under control of the very late AcNPV p10 promoter to monitor viral replication. In S. exigua larvae, permissive Spodoptera spp. cultured cells, and nonpermissive D. melanogaster cultured cells early viral gene expression was indicated by the appearance of Lac-Z as early as 3 hr p.i. Late viral gene expression was indicated by the appearance of GUS and occurred only in the permissive cultured cells and larvae. Early and late viral gene expression could be detected simultaneously using differential enzyme histochemistry. Analysis of infected S. exigua larvae revealed that midgut columnar cells and, at a low frequency, midgut regenerative cells were the primary sites of infection. Parental nucleocapsids were apparently transported through columnar cells to underlaying regenerative cells before virus replication and progeny production. Infection of tissues beside the midgut epithelium was not detected prior to viral replication within the midgut, suggesting that infection of the midgut is an important prelude to systemic infection.
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PMID:Passage of Autographa californica nuclear polyhedrosis virus through the midgut epithelium of Spodoptera exigua larvae. 1183 15