DMSO induces the formation of microfilament bundles in nuclei of zoospores of Phytophthora infestans (Mont.) De Bary (Oomycetes, Pythiaceae).

Cytoskeletons of zoospores of the fungus Phytophthora infestans (Mont.) De Bary treated with dimethylsulfoxide (DMSO) were studied by electron microscopy. High concentrations of DMSO (greater than or equal to 5%) resulted in lysis of the cells and disturbances of the microtubule pattern of flagellar axonemes.

Structural changes within mixed populations of microtubules and protofilament ribbons caused by dilution and cold incubation.

By means of electron microscopy we have investigated the influence of dilution and cold incubation (0 degree C) on mixed populations of tubulin assemblies consisting of microtubules (MTs) and protofilament ribbons with C- and S-shaped profiles formed in the presence of glycerol. Dilution results in a partial disappearance of ribbons, whereas cold incubation causes a decrease of the percentage of MTs in favour of C-ribbons, probably produced by splitting of MT ends. In the case of dilution, we assume a lower dynamic stability of ribbons compared with MTs, which was already observed during long-time incubation of mixed population (Böhm et al.

Effect of sodium chloride on the structure of tubulin assemblies.

By use of a taxol-containing assembly medium, it has been demonstrated that the mean protofilament number of microtubule populations is significantly lower at elevated NaCl concentrations. Assembly of microtubule protein, i.e.

Determination of the protofilament number in microtubules by templates.

We have used microtubules (MTs) and double-walled microtubules (dwMTs), both fragmented, as templates for MT formation from phosphocellulose-purified tubulin. In both cases the mean protofilament number of the nucleated MTs corresponds to that of the templates. The results confirm the observations of Scheele et al.

Structural comparison of assemblies from brain microtubule proteins of different vertebrates.

Formerly, we reported for microtubule protein (MTP), i.e. tubulin plus microtubule-associated proteins (MAPs), from porcine brain that the protofilament number of microtubules and the percentage of aberrant assemblies depend on taxol and MAP activity (Böhm et al.

Total RNA content of brain cells of inbred mice reared under different conditions.

AB/Jena, DBA/2Jena, C57B1/6 Jena inbred mice and ABD2F1- and B6D2F4-hybrid mice either were reared communally and weaned at day 30 or were reared by isolated mothers and weaned at day 21 (I21). On day 50 the total RNA content of pyramidal brain cells of male offspring was determined by cytophotometry. The studied brain areas were the frontal pole of cerebral cortex (FCC) and the CA1 region of the dorsal hippocampus (DHI).

Model for the feedback control system of bacterial growth. II. Growth in continuous culture.

A mathematical model is developed that describes substrate limited bacterial growth in a continuous culture and that is based upon the conceptual framework elaborated in a previous paper for describing the feedback control system of cell growth [S. Bleecken, (1988). J.

Immunoelectron microscopy of Bacillus subtilis cells secreting human interferon alpha 1 or staphylokinase.

Post-embedding labelling techniques with colloidal gold-IgG or -protein A complexes were used to determine the subcellular location of IFN alpha 1 and staphylokinase secreted from Bacillus subtilis GB500 cells. Both proteins were present in the cytoplasma and the cell envelope pointing to a posttranslational mode of translocation across the cytoplasmic membrane. 5- to 10-fold higher concentrations of gold particles per 0.

Modeling survival of experimentally virus-infected laboratory animals--exploration of the survival diagram.

In a recent paper (Sühnel & Veckenstedt, 1989, J. theor. Biol.

Novel shuttle vectors for improved streptokinase expression in streptococci and bacterial L-forms.

Novel shuttle vectors of small size and increased copy number capable of replication in Escherichia coli, L-forms of Proteus mirabilis, and streptococci were constructed from a streptococcal erythromycin-resistant plasmid and an Escherichia coli phasmid. The streptokinase gene, skc, was inserted into one of them, and skc expression was studied in Streptococcus sanguis, Streptococcus lactis, and in an L-form strain (LVI) of Proteus mirabilis. The new streptokinase shuttle plasmid, pMLS10 (7.

Determination of gold-labelled surface receptors on single cells by X-ray microanalysis.

A standardless X-ray microanalytical procedure has been developed to determine the number of gold-labelled surface receptors on whole single cells. The effect of the injection of K2PtCl4 into mice on gold-labelled concanavalin A (Con A) receptors on peritoneal macrophages was examined with an energy dispersive X-ray detector in an SEM. The numbers of gold particles seen in electron micrographs and estimated by fluorescence photometric measurements of fluorescein isothiocyanate-labelled Con A receptors were correlated with the X-ray microanalytical results.

Cationic anticancer drugs and their modes of action.

This report focuses on two groups of cationic cancerostatics, anthracycline antibiotics and 1,4-benzoquinone-guanylhydrazone-thiosemicarbazone (ambazone), lining up biophysical and biochemical effects on the level of membranes and membrane constituents. The interaction of both drugs with multilamellar liposomes consisting of phosphatidylcholine used as a simple model membrane system could be ensured by means of steady state and nanosecond time-resolved fluorometric investigations. The biochemical effect on membranes is underlined by the inhibition of the neuraminidase activity of the Sendai virus, modification of the CAMP phosphodiesterase activity of leukemia L 1210 cells of mice and reduction of the lymphocyte blast transformation.

Variation of DNA sequence specificity of DNA-oligopeptide binding ligands related to netropsin: imidazole-containing lexitropsins.

CD binding studies of nonintercalative oligopeptides related to netropsin, named lexitropsins, have been carried out with synthetic duplex DNAs and natural DNA. While netropsin possesses a high dA.dT sequence specificity, these ligands show a progressive lowering of the ability to bind to dA.

Pharmacokinetics of the progestin dienogest (STS 557) in rabbits.

Disposition and excretion of the progestin Dienogest (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one, STS 557) were investigated in female rabbits. Following single and repeated administration of the tritium-labelled compound the plasma concentration courses of total radioactivity (Dienogest + metabolites) and of the parent drug alone were estimated and also the urinary and fecal excretion of total radioactivity. From these data basic pharmacokinetic parameters were calculated.

Molecular mechanics and X-ray crystal structure investigations on conformations of 11 beta substituted 4,9-dien-3-one steroids.

The influence of 11 beta-phenyl substitution upon 4,9-dien-3-one steroid-backbone conformations is calculated by means of the MM2p molecular mechanics scheme. In the case of steroids having a 13 beta configuration, the lowest strain energy is always evaluated for the conformational combination of rings A(inverted) B(normal) while, moreover, the 11 beta substitution increases the relative stability of the conformation A(normal) B(normal) compared to the nonsubstituted compound. Introduction of the 11 beta substituent causes some bowing of the energy-minimum structures in the A-ring region toward the beta side.

Structural differences between histone H1 molecules from sea urchin (Strongylocentrotus intermedius) sperm and calf thymus: hydrodynamic and c.d. studies.

Comparative sedimentation, diffusion and circular dichroism (c.d.) measurements have been performed on two histones H1 from sperm of the sea urchin Strongylocentrotus intermedius (H1S) and from calf thymus (H1T), at a high salt concentration of M NaCl.

Heterologous signal peptide processing in fusion interferon synthesis by engineered L-forms of Proteus mirabilis.

A recombinant DNA Proteus mirabilis L-form expression system, LVI (pJS127), was used to synthesize human fusion interferon alpha 1 (f-IFN-alpha 1). In the expression plasmid used, the complete coding sequence of IFN-alpha 1 was linked to the streptococcal speA promoter and the 5' end of the speA structural gene including its signal sequence coding region. LVI (pJS127) was capable of complete secretion into the culture medium of biologically active f-IFN-alpha 1 whose identity was confirmed by immunological and chemical evidence.

Streptokinase mutations relieving Escherichia coli K-12 (prlA4) of detriments caused by the wild-type skc gene.

A novel phenotype is described for Escherichia coli K-12 carrying the prlA4 allele determining a membrane component of the protein export mechanism. It is manifest as transformation deficiency for plasmids containing the cloned group C streptococcal streptokinase gene, skc. Streptokinase plasmid mutations relieving the prlA4 strain of this deficiency fell into three classes.

Complete secretion of activable bovine prochymosin by genetically engineered L forms of Proteus mirabilis.

To circumvent problems encountered in the synthesis of active chymosin in a number of bacteria and fungi, a recombinant DNA L-form expression system that directed the complete secretion of fully activable prochymosin into the extracellular culture medium was developed. The expression plasmid constructions involved the in-frame fusion of prochymosin cDNA minus codons 1 to 4 to streptococcal pyrogenic exotoxin type A gene (speA') sequences, including the speA promoter, ribosomal binding site, and signal sequence and five codons of mature SpeA. Secretion of fusion prochymosin enzymatically and immunologically indistinguishable from bovine prochymosin was achieved after transformation of two stable protoplast type L-form strains derived from Proteus mirabilis.

Modeling survival of experimentally virus-infected laboratory animals.

Although survival analysis is a well-established mathematical discipline, there seem to be almost no attempts in survival modeling for experimentally virus-infected laboratory animals. We have taken up a stochastic approach originally developed by Shortley in the sixties and have applied it to three different types of experimental data: to virus titer determination, to the dose dependence of the mean survival time and to single survival curves. Experience concerning parameter estimation is reported and new ways of working with the model parameters are proposed.

Arsenical resistance of growth and phosphate control of antibiotic biosynthesis in Streptomyces.

Twenty-six wild-type Streptomyces strains tested for resistance to arsenate, arsenite and antimony(III) could be divided into four groups: those resistant only to arsenite (3) or to arsenate (2) and those resistant (8) or sensitive (13) to both heavy metals. All strains were sensitive to antimony. The structural genes for the ars operon of Escherichia coli were subcloned into various Streptomyces plasmid vectors.