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A Toshkov

Publications and source records attributed to A Toshkov.

At least 37 records · Page 2Linked to original sources
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↗
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↗
PubMed1980

Histoautoradiographic studies of 3H-thymidine labelled Erysipelothrix rhusiopathiae introduced into albino mice.

S-forms of E. rhusiopathiae were cultivated in a 3H-thimidine-containing medium. A suspension washed three times in succession was intravenously injected into albino mice. At certain intervals liver, spleen and kidney were examinated by routine autoradiogrphy. Intact labelled bacteria were found as early as 5 min after administration in the blood capillaries, around cells of the RES and in some nuclei of hepatocytes. Later they are detected in the cytoplasm of micro- and macrophages, around megacaryocytes and in some of their nuclei. After 6 h the labelled population sharply decreases due to a very active reproduction and mortality of the initial population. The localisation of bacteria in liver nuclei and the spreading of S-forms of E. rhusiopathiae in comparison with the avirulent L-forms therefrom are discussed.

Animals↗