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Biomedical subjects

J Gumpert

Publications and source records attributed to J Gumpert.

At least 37 records · Page 2Linked to original sources
PubMed1987

Electron microscopic and biophysical studies of liposome membrane structures to characterize similar features of the membranes of Streptomyces hygroscopicus.

To characterize the novel non-planar plasma membrane structure of bacteria (wafer structure), liposome membranes from the bacterial lipid mixture and individual lipid fractions were prepared and investigated by freeze-fracture electron microscopy, microcalorimetry and 31P-NMR spectroscopy. The phospholipid content of the membranes is essential for the formation of the non-planar membrane structure and there is no indication that the formation of the structure is connected with temperature-induced lipid phase transition processes. An exaggerated form of the wafer structure (raspberry structure) is also visible and additionally, in both cases, many small spherical vesicles are observed. We suggest that both membrane features of the liposomal and bacterial membranes are induced by these vesicles, forming a hexagonal or cubic organization of vesicles on the cytoplasmic surface of the biological membrane, and in between the multilamellae in the artificial membranes.

Calorimetry↗
PubMed1986

Phage adsorption and productive lysis in stable protoplast type L-forms of Bacillus subtilis and Streptomyces hygroscopicus.

Transferable productive lysis in stable protoplast type L-form cells of Bacillus subtilis was produced by 6 phages out of 14 strains virulent for the parent B. subtilis 170 and 1997. Most of these phages lytic for L-forms show the phi 29 morphology characteristic for the smallest B. subtilis phages containing double-stranded DNA. Among 31 actinophages, 23 of which were virulent for Streptomyces hygroscopicus, only SLE 109 and phi c 31 gave productive infection of the stable protoplast type L-form of S. hygroscopicus NG 33--354. Electron microscopic investigation and treatment by DNAse demonstrated that infection of L-form cells is an adsorption-injection process, and that it is not caused by transfection of free phage DNA or endocytotic uptake of phage particles. Because in both stable L-forms cell wall biosynthesis is blocked irreversibly the results allow the conclusion that specific receptors must be localized in the cytoplasmic membrane for those phages producing transferable lysis in protoplast type L-forms. Localization of receptors for certain phages in the cytoplasmic membrane seems to occur in many Gram-positive bacteria, but not in Gram-negative bacteria.

Adsorption↗
PubMed1986

Structures of liposome membranes as models for similar features of cytoplasmic membranes of bacteria.

To characterize a special kind of membrane structure, visible in the cytoplasmic membranes of a Streptomyces hygroscopicus strain, liposome membranes were prepared from their extracted lipid mixture and from their lipid fractions (phospholipids, glycolipids, neutral lipids) and investigated by freeze-fracture electron microscopy. Liposome membranes made of the extracted lipid mixture reveal this special membrane structure, named wafer structure, from its regular pattern of bulges (30-40 nm in diameter). That is the proof that this membrane feature is a lipid structure. Liposome membranes prepared from the lipid fractions show the wafer structure if they are made of the phospholipid fraction only or in combination of this fraction with one or both of the other lipid fractions, indicating that wafer structure formation is primarily connected with the phospholipid content of the membranes. The glycolipid- and neutral lipid fractions amplify this phospholipid structure only. Additional to the wafer structure a raspberry structure with bulges of 55-65 nm in diameter is visible in some case. Obviously both structures are related.

Cell Membrane↗
PubMed1985

Occurrence of squalene and dehydrosqualene in streptomycetes.

Squalene, dehydrosqualene and related hydrocarbons were found to constitute an essential part of the neutral lipid fraction extracted from mycelia and membranes of S. hygroscopicus, S. griseus and S. noursei. In comparison with the fraction of the triglycerides, these terpenoid compounds failed to incorporate (U-14C)-acetic acid throughout pulse labelling experiments. This suggested that the pertinent precursors were formed via alternative routes, for instance by catabolising branched-chain amino acids.

Acetates↗
PubMed1983

Ultrastructural characterization of core structures and paracrystalline inclusion bodies in L-form cells of streptomycetes.

Protoplast type L-form cells of Streptomyces hygroscopicus and S. griseus contain different types of inclusion bodies. Cytoplasmic cores and paracrystalline structures are peculiar inclusions which could not be observed in normal parent bacteria. The cytoplasmic cores are 1-4 micron long and 0.05-0.25 micron broad straight and stiff non-tubular structures consisting of homogeneous mode-rate electron opaque material. Paracrystalline inclusions have side-lengths between 0.2 and 0.5 micron and show a characteristic pattern of 15-20 nm thick straight dark lines and electron lucent intervening spaces of 20-30 nm. Both cytoplasmic cores and paracrystalline inclusions are apparently proteins. Their occurrence in L-form cells indicates an altered synthesis of one or several proteins in these cell types.

Cell Nucleus↗
PubMed1982

Fatty acid composition of lipids of Escherichia coli W 1655 F+ and its stable protoplast type L-form.

The comparative fatty acid analysis of extractable and non-extractable lipids of Escherichia coli W 1655 F+ and its stable protoplast type L-form shows quantitative as well as qualitative differences. From 10 different fatty acids obtained 16:0, 17:0 and 18:0 are present at about the same quantities in the lipid fractions of the bacterial and L-form. The absence of larger amounts of 12:0, 14:0, and 14:beta OH fatty acids in non-extractable L-form lipids reflects the loss of the cell wall in L-form cells. 16:1 fatty acid was found in L-form lipids only. This qualitative difference and the 2-3 times higher content of 18:1 in L-form lipids and the 7 times lower content of cyc 19:0 in extractable lipids of the L-form may be interpreted as alterations characteristic for the changed composition of the cytoplasmic membrane in L-form cells.

Chromatography, Gas↗
PubMed1982

Growth characteristics and ultrastructure of protoplast type L-forms from streptomycetes.

L-form colonies from S. hygroscopicus, S. griseus and S. levoris were isolated after incubation of lysozyme protoplasts on an osmotically stabilized complex agar medium. Unstable and stable L-forms grow on solid and in liquid media. L-form colonies are 5-10 times smaller than normal colonies and show a typical morphology for each species. In ultrathin sections L-form cells are characterized by nucleoid areas with typical core-like structures, by a ribosome-rich cytoplasm with different inclusion bodies, and by a cytoplasmic membrane. Because there are no cell wall structures L-forms of the three Streptomyces species belong to the protoplast type. Analysis of cell size and cell shape shows a variation in diameter and a cell propagation by regular and irregular division- and budding-like processes. Many L-form cells contain more than two chromosomes. The results are discussed with regard to the cellular organisation of streptomycetes and the nature of the stable L-form.

Cell Membrane↗
PubMed1982

Antimicrobial activities of daunorubicin and adriamycin derivatives on bacterial and protoplast type L-form cells of Bacillus subtilis 170, Escherichia coli B, and Proteus mirabilis VI. Structure--activity relationship.

The antibacterial activity of ten N-alkylated derivatives of daunorubicin and adriamycin as well as of 5-iminodaunorubicin has been tested by using Bacillus subtilis 170, Escherichia coli B, and Proteus mirabilis VI and their stable protoplast type L-forms in an agar diffusion test. Eight of the substances showed similar activities against B. subtilis and the L-forms of all test organisms, but no activity against the bacterial forms of E. coli and P. mirabilis. The cell wall of these gram-negative bacteria is responsible for this resistance by not allowing the antibiotics to enter the cells. The piperidino compound N-(CH2)5 daunorubicin shows 2-4 times higher activity against B. subtilis and all L-forms in comparison to daunorubicin and the other derivatives. Five of the substances were inactive against all test strains. Their inactivity seems to be associated with the larger substituents at the C-3' position. Relations between molecular structure and activity are discussed considering data about the interaction with DNA and the antitumor activity. Stable protoplast type L-forms and their bacterial forms represent a suitable and effective test system to screen for more effective substances and to get more information about their mode of action.

Bacillus subtilis↗
PubMed1982

[Physiological and cell biological characterization of the protease producer Thermoactinomyces vulgaris during prolonged culture in a stirred fermenter].

The physiological behaviour of Thermoactinomyces vulgaris - producing a thermostable serine-protease - was analyzed during fermentation. During 38 h the consumption of nutrients and oxygen as well as the rates of macromolecular and protease synthesis were measured. The morphological and ultrastructural changes of the mycelia were also studied. The mycelia grew exponentially for about 5 hours. After a short lag and a second slower growth phase, growth continued about linearly until the end, as was indicated by a constant rate of incorporation of labelled thymidine. However, at the same time a changing portion of hyphae - up to 45% - underwent lysis. According to the changing ratio of growing and lysing material, regarding the physiological activity of the culture the fermentation process could be divided into 4 periods. The formation of the protease started at the transition to the slow growth phase and continued linearly. The ability to produce the protease was attributed to a mycelium being formed after the shift down caused by limitation of supply of utilizable nitrogen compounds. The end of protease production 10 h later was correlated to a drastic decrease of the respiratory activity of the mycelia, probably caused by exhaustion of easily utilizable carbohydrates.

Amino Acids↗
PubMed1980

Light microscopic investigations on lysozyme- and penicillin-induced morphological changes in Erysipelothrix rhusiopathiae and on propagation of its protoplast type L-form.

Although lysozyme and penicillin are different in their molecular action on cell wall murein they produce similar morphological changes in Erysipelothrix rhusiopathiae grown on agar media. 2,000--5,000 micrograms/ml lysozyme and 0.1--2 IU/ml penicillin induce filament formation. Filaments are able to divide in rods, which shows that only cross wall formation and separation are inhibited. Higher doses of lysozyme (10,000 micrograms/ml) and penicillin (less than 1 IU/ml) inhibit cell wall synthesis and induce L-form growth. The propagation of this protoplast type L-form was investigated by microphotographic series in phase contrast microscope during L-form induction and in the stable L-form state. In both cases L-form cells propagate by formation and growth of small granular elements of about 0.2--0.6 micrometers in diameter, which spread in different directions in the agar medium. The multiplication process may be explained by the plasticity and flexibility of the L-form cell and its cytoplasmic membrane and by the structural and functional interaction between the "folded chromosome" and the surrounding cytoplasm.

Erysipelothrix↗
PubMed1978

Experimental pyelonephritis induced by L-forms of Proteus mirabilis in rats.

Pyelonephritis was produced in 75 white rats by applying a 24-hour ligature on the ureter and by intravenous injection of a suspension of 5X10(9) cells of a stable Proteus mirabilis L-form. Pyelonephritis was proved microscopically in 44% of the animals. The revertants of the introduced L-form play an etiological role in the development of the infection. The stability of the pathohistological findings makes this model suitable for the purpose of experimental chemotherapy.

Animals↗