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Biomedical subjects

R Lurz

Publications and source records attributed to R Lurz.

116 records · Page 7Linked to original sources
PubMed1979

Arrangement of coding and intervening sequences of chicken lysozyme gene.

Hybrid phages that contain chicken lysozyme gene sequences have been isolated from a chicken DNA library. Two overlapping clones covering a region of 22 kilobase pairs around this gene have been studied by restriction mapping. Southern hybridization, and electron microscopic analysis of hybrids between lysozyme mRNA and the cloned cellular DNA. Three intervening sequences interrupt the lysozyme structural gene. The cellular gene is at least 3.9 kilobases long, about 6 times the length of the structural gene.

Animals↗
PubMed1979

In vitro core particle and nucleosome assembly at physiological ionic strength.

Nucleosome core particles have been efficiently assembled in vitro by direct interaction of histones and DNA at physiological ionic strength, as assayed by digestion with DNases, supercoiling of relaxed circular DNA, and electron microscopy. Reconstitution was achieved either by the simultaneous addition of all core histones, or by the sequential binding of H3 . H4 tetramer and H2A . H2B dimer to DNA. Micrococcal nuclease digestion and electron microscopy studies indicated that there is heterogeneity in the spacings at which core particles are assembly on the DNA. Length measurements of oligomeric DNA produced during the course of the digestion suggest that the core histone octamer can organize 167 (+/- 4) rather than 145 base pairs of DNA, the extra 20 base pairs being quickly digested. Binding of histone H1 to core particles resulted in the protection of about 165 base pairs of DNA from nuclease attack. Because the core histone octamer is fully dissociated into H3 . H4 tetramer and H2A . H2B dimer at physiological ionic strength, our results would suggest that in vivo core particle assembly may also occur by interaction of these two complexes on the nascent DNA.

Animals↗
PubMed1977

Electron microscopic investigation of the hydrogen-oxidizing acetate-forming anaerobic bacterium Acetobacterium woodii.

Acetobacterium woodii is a Gram-positive anaerobic nonsporeforming bacterium able to grow on H2 and CO2 as sole sources of energy. The product of fermentation is acetic acid. Fine structural analysis showed rod-shaped flagellated cells, and coccoid cells without flagella arranged predominantly in pairs and chains. The cell wall was found to be composed of three layers. The cell surface exhibited a periodic array of particles consisting of subunits. The cytoplasmic membrane showed particles either in random distribution or in a hexagonal pattern. Intracytoplasmic membranes were rarely observed, whereas inclusion bodies of varying shapes, predominantly in an uncommon disc-shape, could frequently be observed. Their content was dissolved in ultrathin sections indicating hydrophobic nature.

Acetates↗
PubMed1975

Electron microscopic characterization of Rhizobium bacteriophage 16-6-12 and its isolated deoxyribonucleic acid.

Bacteriophage 16-6-12 of Rhizobium lupini has a long, non-contractile tail and a head which is hexagonal in outline. The tail is 140 nm in length, 11 nm in diameter, and carries a short term fiber. Analysis of the tail structure by optical diffraction indicates that it is of the helical "stacked disc" type. After phenol-extraction from purified particles, the DNA of phage 16-6-12 can circularize in vitro. No significant difference in contour length was observed between the linear (14.34 plus or minus 0.28 mum) and circular (14.44 plus or minus 0.24 mum) forms of molecules. After partial denaturation with alkali an AT-GC-map was constructed, which shows an asymmetric distribution of AT- and GC-rich regions. It is concluded that this phage DNA can circularize due to the presence of cohesive ends and that it is not circularly permuted.

Bacteriophages↗
PubMedDate not supplied

Homologous cell-derived oncogenes in avian carcinoma virus MH2 and murine sarcoma virus 3611.

Retroviral oncogenes (v-onc) are derived from cellular genes (c-onc) which are highly conserved among different species. Retrovirus-transduced oncogenes are most commonly associated with the induction of haematopoietic tumours and sarcomas. The avian retrovirus Mill Hill no. 2 (MH2) was isolated from a spontaneous ovarian tumour of a chicken and is distinguished by the predominant induction of liver and kidney carcinomas in fowl. MH2 also induces transformation of fibroblasts, macrophages and epithelial cells in culture. The genome of MH2 contains two unrelated and independently expressed cell-derived oncogenes, v-mil and v-myc. Three other viral isolates among avian acute transforming retroviruses contain the v-myc oncogene, but only MH2 contains both v-myc and v-mil. Hence, some of the pathogenic specificities of MH2 may be due to the simultaneous expression of two oncogenes. The murine sarcoma virus 3611 (3611-MSV) isolated from a mouse carrying lung carcinoma and peritoneal tumours, induces fibrosarcomas in newborn mice and the transformation of fibroblasts and epithelial cells in culture. The oncogenic properties of 3611-MSV are due to the presence in its genome of a cell-derived oncogene termed v-raf. We report here that the two independently transduced oncogenes v-mil and v-raf are closely related and that they were apparently derived from homologous cellular genes of avian and mammalian species.

Animals↗