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Biomedical subjects

R Hull

Publications and source records attributed to R Hull.

At least 163 records · Page 9Linked to original sources
PubMed1986

The sequence of carnation etched ring virus DNA: comparison with cauliflower mosaic virus and retroviruses.

Carnation etched ring virus (CERV) DNA comprises 7932 bp. CERV primer binding sites and overall genome organization are similar to those of the related cauliflower mosaic virus (CaMV). The six open reading frames of CERV showed amino acid homology (50-80%) with CaMV ORFs I-VI; no homologues of CaMV ORFs VII or VIII were found. CERV ORFs 1-5 interface each other with the sequence ATGA. The comparison of CERV ORF5 with CaMV ORFV highlighted regions which show homologies to retrovirus gag/pol protease, RNase H and DNA polymerase domains; the possibility that the DNA polymerase domain comprises two subdomains, operating off different templates, is discussed. Both CERV and CaMV ORFs I have sequence homology to tobacco mosaic virus P30 and plastocyanin.

Journal Article↗
PubMed1986

Chromosomal map position of genes encoding P adhesins in uropathogenic Escherichia coli.

Escherichia coli isolates from upper urinary tract infections frequently express adherence to human uroepithelium and D-mannose-resistant hemagglutination of human erythrocytes. Such adherence is usually associated with P pili encoded by the pap operon(s). In this paper, we report approximate chromosomal map positions for two copies of the pap operon. Only one copy expressed an adhesin capable of D-mannose-resistant hemagglutination, although both expressed P-related antigen.

Adhesins, Escherichia coli↗
PubMed1985

Isolation of a fraction from cauliflower mosaic virus-infected protoplasts which is active in the synthesis of (+) and (-) strand viral DNA and reverse transcription of primed RNA templates.

Sub-cellular fractions, isolated from cauliflower mosaic virus (CaMV)-infected turnip protoplasts, are capable of synthesising CaMV DNA in vitro on an endogenous template and of reverse transcribing oligo dT-primed cowpea mosaic virus RNA. The activity was not detected in mock-inoculated protoplasts. In vitro-labelled DNA hybridized to single-stranded M13 clones complementary to the putative origins of (-) and (+) strand CaMV DNA synthesis and to restriction endonuclease fragments encompassing more than 90% of the CaMV genome. The synthesis of (-) and (+) strand DNA appeared asymmetric. The template(s) for in vitro CaMV DNA synthesis are in a partially nuclease-resistant form. Fractions capable of in vitro CaMV DNA synthesis contained CaMV RNA both heterogeneous and as discrete species; they also contained a range of different sizes of CaMV DNA. Several lines of evidence indicate that this range of in vitro-labelled CaMV DNA, extending from 0.6kb to 8.0kb in length, represents elongating (-) strand DNA. These are discussed in relation to their role as possible replicative intermediates.

Cloning, Molecular↗
PubMed1985

Mitochondrial modulation of maternally transmitted antigen: analysis of cell hybrids.

Maternally transmitted antigen (Mta) is a murine cell surface class I-like antigen that is defined by specific cytotoxic lymphocyte reactivity. Mta is unique in that its expression requires cooperation between genetic elements both in the Qa/Tla region of chromosome 17 and in the cytoplasm. In view of the known cytoplasmic, and thus maternal, inheritance of mitochondria, we have directly assessed their potential involvement in Mta expression. The mitochondria-specific lethal dye rhodamine 6G (R6G) was used to control the input of mitochondria into cell hybrids. The parental lines, one of BALB/c and one of NZB origin, were known to differ in Mta and mtDNA phenotype. Our data show that most control BALB/c-NZB hybrids expressed the BALB/c Mta phenotype and likewise contained only BALB/c-type mtDNA. The NZB Mta phenotype was not coexpressed in the control hybrids. However, when the mitochondrial contribution from BALB/c was prevented by R6G treatment, the majority of the resultant hybrids expressed only the NZB Mta type and likewise contained only NZB mtDNA. The exceptional R6G-treated hybrids that continued to express the BALB/c Mta phenotype likewise contained only BALB/c mtDNA. Thus, in every case the mtDNA phenotype correlated with the Mta phenotype of the cells. Together, the data support the remarkable conclusion that mitochondria modulate the phenotypic expression of a cell surface molecule.

Animals↗
PubMed1985

Contribution of the traT gene to serum resistance among clinical isolates of enterobacteriaceae.

Antimicrobial resistance plasmids containing the traT gene confer resistance to serum bactericidal activity upon some laboratory strains of Escherichia coli. We have examined the DNA of Enterobacteriaceae from human extraintestinal infections to determine the frequency of traT-like genes. DNA sequences homologous with traT were found among 58% of Escherichieae but among none of the Klebsielleae or Proteeae tested and were found as frequently among serum-sensitive E. coli as among serum-resistant strains. Sequences related to traT were always associated with large plasmids. The potential contribution of traT-containing plasmids to serum resistance of clinical isolates is discussed.

Blood Bactericidal Activity↗
PubMed1985

Multiple forms of genes in pyelonephritogenic Escherichia coli encoding adhesins binding globoseries glycolipid receptors.

Earlier studies have shown that the majority of Escherichia coli isolates from urinary tract infections which possess a D-mannose-resistant adhesin contain gene sequences homologous to the pap pilus gene sequences encoded on the recombinant plasmid pRHU845. In this report, several E. coli isolates from urinary tract infections were examined to determined the arrangement of pap-related sequences. Copies of gene sequences homologous to the entire pap operon were found to exist at multiple sites in the chromosomes of some strains. The position of the pap operon(s) with respect to adjacent sequences was also found to be variable.

Adhesins, Escherichia coli↗
PubMed1985

Construction and comparison of recombinant plasmids encoding type 1 fimbriae of members of the family Enterobacteriaceae.

The genes encoding type 1 fimbriae of Salmonella typhimurium, Enterobacter cloacae, and Serratia marcescens were cloned in Escherichia coli. All transformants possessing recombinant plasmids were shown to be fimbriate and demonstrated mannose-sensitive hemagglutinating activity. A comparison of the physical maps of these plasmids revealed little similarity among them, although plasmids encoding type 1 fimbriae of Escherichia coli and Klebsiella pneumoniae appeared similar with respect to restriction enzyme sites. The fimbrial gene cluster ranged in size from 5.5 to 9.0 kilobase pairs as determined by transposon mutagenesis. Plasmid-containing E. coli strains were shown to produce species-specific fimbrial antigens with little or no cross-reactivity between genera. Therefore, it was presumed that each plasmid contained the gene encoding the fimbrial subunit. Complementation was not detected between nonfimbriate insertion mutants of different species but was seen with mutants of the same species.

Antigens, Bacterial↗
PubMed1984

Influence of adhesins on the interaction of Escherichia coli with human phagocytes.

The fitness between bacterial adhesins and target cell receptors, determining bacterial adherence to epithelial cells in urinary tract infections, was shown to influence also the interaction with human polymorphonuclear leukocytes (PMNL). Two sets of homogenic strains, constructed to express either, both, or none of the globotetraosylceramide-sensitive (GS) adhesins specific for globoseries glycolipid receptors or the mannose-sensitive (MS) adhesins inhibited by alpha-methyl mannoside were compared regarding charge, hydrophobicity, and binding to PMNL. The mutants of a hydrophilic pyelonephritis strain required MS adhesins for binding to and activation of the PMNL. Removal of the MS adhesins from the mutant carrying both MS and GS adhesins abolished chemiluminescence and binding. A pronounced chemiluminescence reaction was induced by the hydrophobic strain without GS or MS adhesins . Transformants of this strain expressing the MS adhesin bound to and activated the PMNL. Poor binding and activation were found with mutants and transformants carrying only the GS adhesins . The improved reactivity after coating of the PMNL with the appropriate receptor glycolipid supported the previously reported absence of globoseries glycolipids in those cells as the reason for the refractoriness to bacteria with GS adhesins . The mechanism of binding, which improves epithelial cell adhesion, may prevent binding to PMNL, thus improving the survival of Escherichia coli in the kidney.

Adhesins, Escherichia coli↗
PubMed1984

Difference in susceptibility to gram-negative urinary tract infection between C3H/HeJ and C3H/HeN mice.

The difference in susceptibility to urinary tract infection between C3H/HeJ and C3H/HeN mice was tested for with gram-negative strains differing in lipopolysaccharide composition. Recently, impaired clearance of Escherichia coli from the kidney of C3H/HeJ compared to C3H/HeN mice was shown to be correlated with the LPS low responsiveness. In this study, a difference in clearance from the kidneys of C3H/HeJ and C3H/HeN mice was found only with lipopolysaccharide-containing bacteria. Gram-positive bacteria, e.g., Staphylococcus saprophyticus and Streptococcus agalactiae, were recovered in essentially equal numbers from the kidneys of mice of both strains. In contrast, of the lipopolysaccharide-containing strains used, all persisted in higher numbers in the kidneys of C3H/HeJ mice than in the kidneys of C3H/HeN mice. Variations in the O side chain did not eliminate this difference. E. coli Hu734 O75+K5+ and the rfb- mutant O75-K5+ remained in similar numbers in C3H/HeJ mice, although O75-K5+ was eliminated more rapidly in C3H/HeN mice. The core structure did not affect the differential persistence in the two mouse strains. The rfb mutants with R1-R4 cores were eliminated after 24 h from the C3H/HeN mice, but remained in significant numbers in the kidneys of C3H/HeJ mice. Even the Re mutant of Salmonella minnesota persisted in low numbers in C3H/HeJ mice. The relative bacterial recovery from either mouse strain was related to the overall virulence of the infecting bacterial strain, but the difference between C3H/HeJ and C3H/HeN mice was associated with responsiveness to parts of lipopolysaccharide common to the bacterial strains tested.

Animals↗
PubMed1983

Characterisation of cauliflower mosaic virus DNA forms isolated from infected turnip leaves.

Several different forms of cauliflower mosaic virus (CaMV) DNA were detected in nucleic acid preparations from CaMV-infected turnip leaves. As well as supercoiled and open-circular molecules, various linear DNA structures were identified. The relative amounts of these DNA forms varied in plants infected with different CaMV isolates. Restriction enzyme mapping and one- and two-dimensional gel electrophoresis revealed the presence of linear molecules apparently formed by breaks in the second strand at each of the three discontinuities. Two major linear DNA forms are double-stranded over part of their length and appear to have single-stranded extensions of the -strand of variable length. Since these DNA forms are not produced during extraction and probably exist as unencapsidated or partially encapsidated molecules, they may represent intermediates either in DNA replication or in virion assembly.

DNA Restriction Enzymes↗