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M G Murray

Publications and source records attributed to M G Murray.

16 recordsLinked to original sources
PubMed1992

Poliovirus antigenic hybrids simultaneously expressing antigenic determinants from all three serotypes.

We have constructed six hybrid polioviruses (PVs) modified to express PV type 2 and type 3 antigenic determinants on a PV type 1 (Mahoney) capsid. The hybrids were modified in neutralizing antigenic site (NAg) I and/or NAgII. They were viable, but impaired for growth in comparison to PV1 (Mahoney). Some hybrids modified to express type 2 and type 3 NAgI determinants simultaneously displayed some type 2 but no type 3 antigenicity (in addition to type 1 antigenicity associated with other antigenic sites). Hybrids modified to express a type 2 NAgI determinant and a type 3 NAgII determinant, or vice versa, displayed antigenic characteristics of all three serotypes, although expression of the modified NAgII determinant was weak. We conclude that it is possible to construct a viable hybrid PV simultaneously modified in NAgI and NAgII which expresses antigenic determinants of all three serotypes.

Amino Acid Sequence↗
PubMed1991

Phenotypic characterization of antigenic hybrids of poliovirus.

Three poliovirus hybrids, modified in neutralization antigenic sites (NAgs) I or II, were characterized for several phenotypic traits. The modifications to the capsid interfered with some stage of the life-cycle of the virus, since all three hybrids were growth-impaired in comparison to poliovirus type 1 (Mahoney) [PV1 (M)], the wild-type parent virus. All hybrids exhibited a reduced growth rate and a small-plaque phenotype, but they were not temperature sensitive. Furthermore, only one hybrid was slightly less stable to heating than the parent virus; the other two were as stable as the parent. Therefore, decreased thermal stability of the capsid is not an important cause of the poor growth characteristics of these hybrids.

Amino Acid Sequence↗
PubMed1991

When staff are assaulted. A nursing consultation support service.

Increasing patient to staff assaults led to the development of a Nursing Consultation Service, which can respond to the needs of assault victims and set the tone for institutional attitudes of nonblaming concern. A member of the consultation service meets with each known assault victim to review the incident, offer support, and provide assistance in addressing issues aroused by the incident. Implementation of this service and the use of a continuous monitor to track assault incidents is vital to highlight problem areas and develop assault prevention strategies.

Assertiveness↗
PubMed1988

Poliovirus host range is determined by a short amino acid sequence in neutralization antigenic site I.

The mouse-adapted strain of poliovirus type 2 (Lansing) induces fatal poliomyelitis in mice after intracerebral inoculation, whereas mice inoculated with poliovirus type 1 (Mahoney) show no signs of disease. Previous work indicated that the adaptation to mouse virulence is associated with the viral capsid proteins and that mutations in neutralization antigenic site I of poliovirus reduce neurovirulence of the Lansing strain in mice. The role of antigenic site I in mouse neurovirulence was further explored by constructing an antigenic hybrid virus. Six amino acids in antigenic site I of the Mahoney strain were replaced with a sequence specific for the Lansing strain by using a mutagenesis cartridge. The hybrid virus was neutralized by polyclonal antisera elicited by the type 1 and type 2 strains of poliovirus and by neutralizing monoclonal antibodies directed against antigenic site I of type 2 virus. The hybrid virus induced paralytic disease in mice, an observation demonstrating that a short sequence of amino acids in antigenic site I is an important determinant of poliovirus host range. Antigenic site I may be involved in attachment of poliovirus to cells of the mouse central nervous system.

Animals↗
PubMed1988

Poliovirus type 1/type 3 antigenic hybrid virus constructed in vitro elicits type 1 and type 3 neutralizing antibodies in rabbits and monkeys.

Poliovirus exists as three stable serotypes (PV-1, PV-2, and PV-3). These viruses display three antigenic sites each, designated N-AgI, N-AgII, and N-AgIII. When mice are immunized with poliovirus, N-AgI is the major neutralization antigenic site for PV-3, whereas N-AgII and N-AgIII are immunodominant over N-AgI for PV-1. To study the relationship between structure and antigenicity, a hybrid virus was constructed in which N-AgI of PV-1 was replaced by N-AgI of PV-3. PV-3- and PV-1-specific antisera, including those elicited by PV-3 in primates, neutralized the hybrid virus. Injection of the hybrid virus into rabbits or into primates resulted in the production of antisera that neutralized both PV-1 and PV-3. The data show that sequence replacement at N-AgI of poliovirus is compatible with viral proliferation, an observation useful for the development of multivalent picornavirus vaccines.

Amino Acid Sequence↗
PubMed1987

Nucleotide sequence and characterization of a gene encoding the phytochrome polypeptide from Avena.

We have isolated and characterized a gene encoding the phytochrome polypeptide of Avena. Based on nucleotide sequence identity with previously sequenced cDNA clones this gene is designated as type 3 (phy3). The gene is about 5.9 kb long with six exons and five introns, one each of the latter in the 5' and 3'-untranslated regions. The largest exon encodes the entire 74-kDa, chromophore-bearing, N-terminal domain of the photo-receptor postulated to be directly involved in its mechanism of action. The transcription start point, identified by mung-bean nuclease digestion, is located 24 to 35 bp downstream from a tandem TATA box. Sequence elements homologous to a number of motifs implicated as upstream regulatory elements in other genes are present in the 5'-flanking DNA of phy3. Particularly intriguing are three elements at positions -140, -470 and -650. These elements share homology with the 'GT' motif postulated to be a component of the light-regulatory element of genes encoding the small subunit of ribulose bisphosphate carboxylase.

Bacteriophage lambda↗
PubMed1986

A second virus-encoded proteinase involved in proteolytic processing of poliovirus polyprotein.

The poliovirus polyprotein is cleaved at three different amino acid pairs. Viral polypeptide 3C is responsible for processing at the most common pair (glutamineglycine). We have found that a cDNA fragment encoding parts of the capsid protein region (P1) and the nonstructural protein region (P2), and including the P1-P2 processing site (tyrosine-glycine), can be expressed in E. coli. The translation product was correctly processed. Disruption of the coding sequence of 2A, a nonstructural polypeptide mapping carboxy-terminal to the tyrosine-glycine cleavage site, by linker mutagenesis or deletion, prevented processing. Deletion of the adjacent polypeptide 2B had no such effect. Antibodies against 2A specifically inhibited processing at the 3C'-3D' processing site (tyrosine-glycine) in vitro. We conclude that poliovirus encodes the second proteinase 2A, which processes the polyprotein at tyrosine-glycine cleavage sites.

Capsid↗
PubMed1986

Nucleic acid quantitation by continuous flow fluorometry.

A system for rapid and sensitive fluorometric measurement of nucleic acids is described. Samples can be analyzed virtually as fast as they can be injected into the analyzer (three to five per minute). 5-microliter samples ranging in concentration from 0.05 to 40 micrograms/ml can be measured accurately. The sample can easily be recovered.

Autoanalysis↗
PubMed1986

Use of sodium trichloroacetate and mung bean nuclease to increase sensitivity and precision during transcript mapping.

An improved method for mapping RNA transcript boundaries by the nuclease protection technique is presented. This method exploits the large (greater than 20 degrees C) difference in the thermal stability of RNA:DNA and DNA:DNA duplexes in concentrated chaotropic salt solutions. At 45 degrees C in 3.0 M sodium trichloroacetate RNA:DNA hybridization is very efficient but DNA:DNA duplexes remain completely denatured. For many applications, this solvent system can eliminate the need to prepare probes that are free of competing or irrelevant DNA molecules. Fifty- to 100-fold more RNA:DNA hybridization is observed when reassociation is performed in 3.0 M sodium trichloroacetate than in solutions containing high concentrations of formamide. A comparison of the use of S1 nuclease or mung bean nuclease suggests that mung bean nuclease can produce more precise and less ambiguous nuclease protection patterns.

DNA↗
PubMed1984

Use of a recombination-deficient phage lambda system to construct wheat genomic libraries.

The poor cloning efficiency of wheat (Triticum aestivum cv. Yamhill) DNA in conventional cloning vectors has previously prevented the preparation of complete genomic libraries. We show here that while wheat DNA does not clone efficiently using the vector Ch4A, it can be cloned efficiently using Ch32. Ch32 clones are red- gam+ and therefore can be propagated on recombination-deficient hosts. These results suggest that instability of wheat sequences in conventional lambda vector systems has frustrated previous attempts to prepare libraries.

Bacteriophage lambda↗
PubMed1983

DNase I sensitivity of transcriptionally active genes in intact nuclei and isolated chromatin of plants.

We have investigated the DNase I sensitivity of transcriptionally active DNA sequences in intact nuclei and isolated chromatin from embryos of wheat (Triticum aestivum L.). Nuclei or isolated chromatin was incubated with DNase I, and the extent of DNA digestion was monitored as percentage acid solubility. The resistant DNA and DNA from sham-digested controls were used to drive reassociation reactions with cDNA populations corresponding to either total poly(A)+RNA from unimbibed wheat embryos or polysomal poly(A)+RNA from embryos that had imbibed for 3 hr. Sequences complementary to either probe were depleted in DNase I-resistant DNA from nuclei and from chromatin isolated under low-ionic-strength conditions. This indicates that transcriptionally active sequences are preferentially DNase I sensitive in plants. In chromatin isolated at higher ionic strength, cDNA complementary sequences were not preferentially depleted by DNase I treatment. Therefore, the chromatin structure that confers preferential DNase I sensitivity to transcriptionally active genes appears to be lost when the higher-ionic-strength method of preparation is used. Treatment of wheat nuclei with DNase I causes the release of four prominent nonhistone chromosomal proteins that comigrate with wheat high mobility group proteins on NaDodSO4 gels.

Cell Nucleus↗
PubMed1980

Rapid isolation of high molecular weight plant DNA.

A method is presented for the rapid isolation of high molecular weight plant DNA (50,000 base pairs or more in length) which is free of contaminants which interfere with complete digestion by restriction endonucleases. The procedure yields total cellular DNA (i.e. nuclear, chloroplast, and mitochondrial DNA). The technique is ideal for the rapid isolation of small amounts of DNA from many different species and is also useful for large scale isolations.

DNA↗
PubMed1978

DNA sequence organization in the pea genome.

The reassociation kinetics of pea (Pisum sativum L.) DNA fragments (300 nucleotides) were measured with hydroxylapatite. The most slowly reassociating fragments do so with a rate constant of 2 X 10(-4) L mol-1s-1, as determined from experiments with total DNA as well as with a tracer enriched for slowly renaturing sequences. This rate is about 1000 times slower than that observed for Escherichia coli DNA included as an internal kinetic standard, indicating a kinetic complexity of 4.5 X 10(9) nucleotide pairs or 4.6 pg of DNA per haploid nucleus. This estimate is in good agreement with previous chemical and cytophotometric measurements. The majority (85%) of the 300 nucleotide fragments contain repetitive sequences. While the reassociation of repetitive DNA could be modeled with two theoretical second-order components, the data did not specify a unique solution. The reassociation kinetics of isolated high- and low-frequency fractions indicate that repetitive sequence families in pea DNA probably cover a broad range of frequencies ranging from 100 to 10 000 or more copies per haploid genome. Single-copy sequences account for about 30% of the DNA, but because of extensive interpersion of repetitive sequences only about 15% of 300 nucleotide fragments reassociate with single-copy kinetics. From studies of hydroxylapatite binding as a function of fragment length, we conclude that the major class of single-copy sequences has a modal length of about 300 nucleotides. Long tracer reassociation kinetics indicate that sequences with an apparent repetition frequency of about 10 000 copies are interspersed at intervals of less than 1300 nucleotides throughout 75% of the genome. At a detection limit of about 3%, we find no single-copy sequences longer than 1000 nucleotides.

DNA↗