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Biomedical subjects

H Delius

Publications and source records attributed to H Delius.

At least 109 records · Page 6Linked to original sources
PubMed1982

Two distant regions of the Epstein-Barr virus genome with sequence homologies have the same orientation and involve small tandem repeats.

The two regions of the Epstein-Barr virus genome (DSL and DSR) carrying homologous sequences at distant parts of the long unique region are described. Cleavage of cloned DNA containing the DSR region with restriction endonucleases revealed a so far unrecognized small tandem repeat of approximately 120 base pairs present in approximately 20 copies. Heteroduplexes of the DNA of two clones containing DSL and DSR respectively, visualized in the electron microscope by cytochrome c spreading, revealed that the region of homology is approximately 2.5 kb long, involves small tandem repeats, and has the same orientation in the viral genome. Mica adsorption of the heteroduplex showed, that the homologous region consists of approximately 1.5 kb with only partial homology including the small internal repeats and 0.9 kb with well-matched duplexes. When DNA containing the DSL region reanneals, it can give rise to two single-stranded loops of the same size at different positions suggesting the presence of a row of tandem repeats also in this region.

Base Sequence↗
PubMed1982

Halobacterium halobium phage øH.

Phage øH, a novel virus of the archaebacterium Halobacterium halobium, resembles in size and morphology two other Halobacterium phages. One-step growth curves show a 5.5 h eclipse, a latent period of 7 h, and an apparent burst size of 170. Phage øH contains linear, double-stranded DNA which has a molecular weight of 39 x 10 and a GC content of 65%. A packaging model accounting for the partial circular permutation and terminal redundancy of øH DNA is suggested. Partial homology of øH DNA with the DNA of H. halobium, predominantly with the AT-rich satellite DNA, was observed. The presence of minor restriction fragments of øH DNA which could be removed by purification of phage from single plaques suggests the existence of phage variants with rearranged DNA. A strain of H. halobium containing øH DNA was isolated which is resistant to infection by phage øH.

Journal Article↗
PubMed1982

Origin of replication in chloroplast DNA of Euglena gracilis located close to the region of variable size.

Chloroplast DNA (cpDNA), containing 10% replicative molecules, was isolated 2 h after onset of the dark period from cultures of Euglena gracilis strain Z. The DNA was digested with the restriction enzymes PvuII, SalI, BamHI, or EcoRI. Fragments that contained intact replicative loops were measured to determine the position of replicated sequences in relation to the restriction enzyme sites. It was found that replication starts at a unique position near one of the palindromic sequences I(2) (Koller and Delius, 1982a) which is located upstream (with respect to the direction of rRNA transcription) of the AT-rich region of variable size (Jenni et al., 1981; Schlunegger et al., in preparation). In the majority of cases DNA synthesis proceeds unidirectionally away from this region for 5000 nucleotides before it starts in the other direction (in the same sense as the rRNA transcription) through the Z-region and the second palindromic sequence.

Journal Article↗
PubMed1982

Nucleotide sequence of the immunity region of bacteriophage Mu.

The leftmost 1590 bp of Mu DNA covering the immunity region have been sequenced. This region encodes the cI repressor, the cII or ner function and the beginning of gene A. An open reading frame extends from position 863 to 342 on the l-strand corresponding to cI protein with a molecular weight of 19212. It is preceded by a sequence resembling a promoter. To the right of the HindIII site an open reading frame extends from position 1099 to 1323 corresponding to cII or ner protein (molecular weight of 8505) followed by the beginning of gene A at position 1328. Between position 863 and 1099 promoters for leftward and rightward transcription and operator-like structures can be recognized in the sequence. The promoter for rightward transcription overlaps with the HindIII site and coincides with a RNA polymerase binding site as demonstrated by electron microscopy.

Bacteriophage mu↗
PubMed1982

The organization of the chloroplast DNA in wheat and maize in the region containing the LS gene.

The DNAs of the plasmids pTac39 and pZmB1B, which contain the wheat chloroplast DNA BamHI fragment 2 and the maize chloroplast DNA BamHI fragment 9 respectively, were analysed by electron microscopy and by Northern blotting. Both plasmids contain the gene for the large subunit of ribulose bisphosphate carboxylase (LS gene). Comparison of the DNAs of the two species by partial denaturation and heteroduplex analysis shows extended homologies interspersed with a fine pattern of non-homology. On analysis of wheat-RNA X maize-DNA hybrids a region of non-homology at the 3' end of the LS mRNA of about 200 bases was found. Analysis of wheat DNA X RNA hybrids showed that the wheat LS mRNA contains 1700 +/- 50 bases and another hybrid, containing 2400 bases was also shown to occur in a position adjacent to that formed by the LS mRNA. Binding of Escherichia coli RNA polymerase and the start of transcription in vitro occurred at well-defined sites, which are located between or close to the positions where mRNA X DNA hybrids are found. A modified technique for the preparation and fractionation by electrophoresis of glyoxalated RNA is described.

Carboxy-Lyases↗
PubMed1982

Analysis of Mycoplasma hyorhinis genome by use of restriction endonucleases and by electron microscopy.

The chromosome of Mycoplasma hyorhinis was analyzed by using different restriction endonucleases and electron microscopy. It was found that restriction enzymes BstEII, XhoI, and SacI are the enzymes of choice for analysis and characterization of M. hyorhinis. The bands resulting from digestion of M. hyorhinis DNA with BstEII had apparent molecular weights ranging from 1.2 X 10(6) to 75 X 10(6). The apparent total molecular weight of DNA was calculated from the molecular weights of the individual bands and found to be 251 X 10(6). Electron microscopic contour length measurements of the largest DNA fragments verified the molecular weight values calculated from gel analysis. Electron microscopic contour length measurements of intact DNA of M. hyorhinis revealed a molecular weight of 5.4 +/- 5 X 10(8). The discrepancy between the values of molecular weight of M. hyorhinis DNA as determined by restriction enzyme analysis and contour length measurement is based on the fact that some of the DNA fragments which migrate as an apparent single band in the agarose gel really are double or multiple DNA fragments.

Base Sequence↗
PubMed1981

Transcription of sea urchin histone genes in Escherichia coli.

DNA fragments comprising units of the repeated histone genes form the sea urchins Psammechinus miliaris and Echinus esculentus were placed under the control of bacteriophage Lambda promoters by cloning into lambda replacement vectors. Although promoter-like regions exist within the cloned fragments, transcription of the histone genes is controlled mainly, but not exclusively, by lambda PL promoter. A transcription map of the cloned P. miliaris histone DNA fragment was obtained. The order of histone genes in E. esculentus was deduced from electron microscopic analyses of heteroduplexes with P. miliaris histone genes, and is similar to that in P. miliaris. Translation products of the transcripts have not been found in E. coli.

Animals↗
PubMed1981

The plaque-forming factor for mink lung cells present in cytomegalovirus and herpes-zoster virus stocks identified as Mycoplasma hyorhinis.

Previous investigation of the ability of cytomegalovirus and varicella-zoster virus to replicate in a variety of cell lines suggested that both virus types plaqued with high efficiency in mink lung cells. However, many of the virus isolates used appeared to be contaminated with mycoplasma. We now report that the observed cytopathic effect is due to a mycoplasma which grows lytically to high titre in mink lung cells, but is difficult to cultivate in cell-free media. The mycoplasma was plaque-purified and shown to contain DNA with a buoyant density of 1.684 g/ml, with restriction endonuclease patterns identical to the porcine mycoplasma M. hyorhinis. This was confirmed by serological identification.

Animals↗
PubMed1980

RNA-polymerase binding at the promoters of the rRNA genes of Escherichia coli.

The promoter region of two bacterial rRNA genes was investigated by electron-microscopic analysis of polymerase binding, transcription initiation and nitrocellulose filtration of RNA-polymerase-DNA complexes, using restriction endonuclease generated fragments of recombinant plasmids and a transducing phage. The following observations have been made: 1. Two transcription initiation sites have been located approximately 200 and 300 base pairs upstream from the beginning of the sequence coding for mature 16 S rRNA. 2. Polymerase binding at these sites can be observed electronmicroscopically and a 360 base-pair fragment containing these sites binds to nitrocellulose in the presence of RNA-polymerase. This complex dissociates even at moderately high (0.1-0.2 M) salt concentrations. Although transcription initiation is reported to be more frequent at the first of these sites, the binding is much stronger at the second site. 3. In the case of the rrnD gene, BamHI cleaves a few base pairs upstream from the first transcription start site. This cleavage destroys polymerase binding at this site but does not influence binding at the second site. 4. At higher polymerase/DNA ratio four weak but distinct and regularly spaced binding sites can be observed preceding the two initiation sites at approximately 1000, 820, 640 and 440 base pairs before the mature 16 S rRNA sequence. 5. An extremely strong binding site is located about 1300 base pairs upstream from the beginning of the 16 S rRNA sequence. Very little (if any) initiation occurs at this site. The possibility is discussed that the noninitiating binding sites preceding the two transcription start points might functionally belong to the promoter region.

Binding Sites↗
PubMed1980

Electron microscopic mapping and sequence analysis of the terminator for the early message of E. coli phage T7.

The terminator position of T7 early messenger RNA was determined by electron microscopic measurements. The end of the RNA was mapped at a position 18.9% from the left end of T7 DNA, and 145 +/- 25 nucleotides from the right end of the Hpa I fragment Q. The sequence of the Hpa I Q fragment was determined around this position, and a terminator-like structure was detected in position 193 to 169 from the right end of fragment Q.

Base Sequence↗