Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The gene expression of nine phages of the T7 group was compared after infection of Escherichia coli B(P1). With the exception of phage 13a which grew normally, all of them infected E. coli B(P1) abortively. Differences were found in the efficiency of host killing which ranged from 100% for phage 13a to 37% for phage A1122. Infection by T7 prevented colony formation by about 70% of the cells but they showed filamentous growth until about 2 h after infection. It was shown by SDS-polyacrylamide gel electrophoresis and autoradiography of [35S]methionine-labelled phage-coded proteins that all phages except for 13a showed measurable expression only of the early genes. No correlation was observed between killing capacity and the pattern of gene expression, and the ability to hydrolyse S-adenosyl-methionine (SAM, a cofactor for the P1 restriction endonuclease) by means of a phage-coded SAMase. Mixed infection of E. coli B(P1) with 13a and T7 yielded mixed progeny indistinguishable from that observed after mixed infection of the normal host E. coli B. Genetic crosses with amber mutants of 13a and T7 showed that the 13a marker opo+ (overcomes P one), required for growth on B(P1), is located in the early region, to the left of gene 1 (RNA polymerase gene).
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PMID:Inhibition of gene expression of T7-related phages by prophage P1. 304 52

Waterfowl are the natural reservoirs of avian influenza viruses (AIVs), from which the virus can spread to other species including humans, poultry, and swine. For the surveillance of AIV in their natural reservoir, most laboratories initially screen the samples using real-time reverse-transcriptase-polymerase chain reaction because of its high speed and sensitivity. Thereafter, virus isolation is used to isolate viruses from positive samples. Although many studies point to the need of testing both cloacal and oropharyngeal (OP) samples in AIV surveillance programs, most laboratories focus only on cloacal samples. This study was undertaken to determine the utility of OP samples as target samples in AIV surveillance programs under a strict cold chain of samples from the field to the laboratory. A total of 16 AIV (15.1%) were isolated from the 106 OP samples examined. Upon subtyping, four hemagglutinin subtypes (H1, H3, H4, and H6) and three neuraminidase subtypes (N1, N2, and N8) were detected in nine different combinations. Mixed infection with two different subtypes was found in four samples. No AIVs were isolated from the corresponding cloacal samples. These results highlight the fact that testing of properly frozen OP samples could add value to the understanding of the epidemiology and ecology of AIV in waterfowl populations.
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PMID:Improved method for the isolation and sub-typing of avian influenza viruses from oropharyngeal samples of ducks. 2201 43