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Biomedical subjects

S Klaus

Publications and source records attributed to S Klaus.

At least 91 records · Page 5Linked to original sources
PubMed1983

Double or triple sets of replication functions as inverted and direct repeats on in vitro reconstructed streptococcal MLS resistance plasmids.

In vitro rearrangement of plasmid pDB102 together with comparative studies of other streptococcal plasmids allowed the localization of replication and copy control functions on sequences which were present on pDB102 and its naturally occurring ancestor pSM19035 as duplicates in inverted orientation. Evidence is presented that neither the presence of duplicate replication regions nor their arrangement in inverted orientation was essential for plasmid survival. Among the in vitro reconstructed plasmids were several that stably carried two or three sets of replication and copy control functions either as inverted or direct repeats or both. A copy control mutation is described which led to a tenfold increase of copy number over that of the naturally occurring plasmid pSM19035.

Chromosomes, Bacterial↗
PubMed1983

DNA of the Streptomyces phage SH10: binding sites for Escherichia coli RNA polymerase and denaturation map.

Escherichia coli RNA polymerase bound to Streptomyces phage SH10 DNA was visualized by electron microscopy. Six specific binding sites were observed at map units 53, 85, 93, 97, 98, and 99 on the physical map of the 48 kb long genome. Electron microscopy of partially denatured SH10 DNA revealed a characteristic melting pattern of A + T-rich regions around map units 1, 3, 48, 52, and 99. A comparison of the denaturation map with the RNA polymerase binding sites indicates that three binding sites are located in the most A + T-rich regions, two in other early melting regions and one in a segment of higher DNA helix stability.

Bacteriophages↗
PubMed1983

Prenatal toxic effects of STS 557. I. Investigations in mice.

STS 557 was tested for adverse effects in mice by prenatal and postnatal investigations. Several doses of STS 557 and levonorgestrel as a standard were administered on days 3--7, 8--12, or 13--17 post coitum. Following administration on days 3--7 p.c. an increase of skeleton retardations and skeleton alterations was found.

Animals↗
PubMed1982

Inverted duplication in the genome of the temperate Streptomyces phage SH3.

The DNA of the temperate Streptomyces phage SH3 contains 100 base-pair long inverted repeats separated by a 940 base-pair long segment of DNA as revealed by electronmicroscopic analysis of snapback structures formed after rapid intrastrand reannealing of denatured DNA. The inverted repeat structure was found preferentially at map unit 22 of the circular physical map, in rare cases also in other positions, suggesting a movable character of this genetic element.

Bacteriophages↗
PubMed1981

Transduction in Streptomyces hygroscopicus mediated by the temperate bacteriophage SH10.

The temperate actinophage SH10 mediates generalized transduction in Streptomyces hygroscopicus at low frequency. The efficiency of transduction depends on the average phage input, age of outgrowing spores of the recipient and on the selective marker. The highest EOT was found for the auxotrophic mutants 21(phe-) and 5(try-) (4.2 x 10(-6) and 2.7 x 10(-6), respectively). Transduction of the thermosensitive mutant NG14-216 ts 35 was two orders of magnitude lower (2.5 x 10(-8)). The transductant colonies segregated into stable and unstable clones. Stable transductants were never found to be lysogenic for phage SH10.

Bacteriophages↗
PubMed1980

Experiences with a three step test scheme for embryotoxicity and teratogenicity.

Experiences with the three step teratological screening test for selection of teratogenic side effects are described. Step I: The prenatal examination of the foetuses may give indications of embryotoxicity, growth retardation and teratogenicity. Step II: The peri- and postnatal examination includes the duration of pregnancy, the delivery, the viability, the postnatal development and behaviour of the untreated offspring. In special cases the transplacental tumour induction may be studied. Step III: The fertility of the untreated offspring is examined and, in some cases, the generation test should be added.

Abnormalities, Drug-Induced↗
PubMed1979

Molecular characterization of the genomes of actinophages SH3, SH10, SH11, and SH12 infecting Streptomyces hygroscopicus.

Some physico-chemical properties of the DNAs released from the actinophages SH3, SH10, SH11, and SH12 are described. The four phage DNAs have a linear double-stranded secondary structure and are unique with respect to their high G.C contents which, from melting studies and buoyant density experiments, were found to be in the range of 68-73 mol-%. The DNA molecular weights were determined by sedimentation velocity experiments and by electron microscopic length measurements, the mean values of the two corresponding data sets being 34.0 x 10(6) (SH3), 26.7 x 10(6) (SH10), 26.1 x 10(6) (SH11), and 28.7 x 10(6) (SH12) with a mean relative error of +/- 5%. From different observations it was concluded that SH10 DNA, and possibly also SH11 and SH12 DNA, have cohesive ends and can undergo intramolecular or intermolecular association to form ring-like monomers or linear and ring-like multimers. Cleavage of the DNAs of SH3, SH10, SH11, and SH12 by EcoRI restriction endonuclease delivered two, one, zero, and two cleavage sites, respectively, and by BamHI restriction endonuclease eight, zero, zero, and zero cleavage sites, respectively.

Bacteriophages↗
PubMed1978

Characterization of the virulent actinophage S2.

The virulent actinophage S2 isolated from soil infects Streptomyces hygroscopicus 6599, S. lividans 66, and S. levoris 1331. Morphology of S2 was studied by electron microscopy. Influence of growth medium and temperature on multiplication of S2 has been studied qualitatively. S2 is more sensitive to UV irradiation on strain 66 than on 1331. In contrast to UV, hydroxylamine mutagenesis delivered 9 stable ts mutants which belong to 3 complementation groups. Most of the ts mutations isolated on 1331 were found to be host dependent, 8 of 9 mutants were found to be able to grow at 40 degrees C on strain 66 but none of them on 1331. Moreover 2 of the mutants were found to be much more heat sensitive in 6599 than in 1331, as indicated by the changes in half-life temperatures. The latent period of S2+ depends on temperature and germination state of the spores. Under optimal conditions we found 140 min. Ts2 and ts7 have been classified as a late and ts17 as an early mutant.

Bacteriophages↗
PubMed1978

[Development of swimming behavior in mice as a behavioral test in toxicology].

The development of the swimming behaviour in mice is described by 7 stages. The inbred strains and hybrids investigated showed differences in the progress of this development. In comparing the swimming behaviour of offspring from Cyclophosphamid- treated and untreated dams temporal differences have been registered, too. The swimming test is thought to be a suitable behavioural test within embryotoxicological investigations.

Animals↗