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At least 19 recordsLinked to original sources
PubMed1975

[Ultrastructure of L forms. IV. L forms of nonagglutinating vibrios].

A study was made of the ultrastructure of stable L-forms of Nag vibrios aged 24 hours. Cells of all types of the L-forms had cytoplasmic membranes, and a three-layered structure, which was found not everywhere. Externally of the cytoplasmic membrane, in some areas of the individual cells there were revealed a plastic layer of cell wall and a basal membrane. However, in difference to bacterial forms of the vibryos, rigidity of the cell wall was disturbed, and the links between the cell wall and the cytoplasmic membrane were indetectable. There were regularly revealed lamellar of myelin-like membranous structures in the cytoplasm, which did not occur in bacterial forms, and also lamellar mesosomes. The latter were found in the sites of cell division. Viability of small bodies as the minimal reproductive forms of the L-cultures is confirmed by the presence in them of a nucleoid and of the binary division.

Basement Membrane↗
PubMed1975

[Ultrastructure of L-forms. II. L-forms of Listeria monocytogenes].

A study was made of ultrathin sections of the stable l-forms of listeria obtained under the action of penicillin in meat-peptone-liver broth. A marked cellular polymorphism was found in the L-form culture: within the same colony cells differed in size, shape and fine structure. It is supposed that polymorphism could be partially explained by a different plasticity and premeability of cytoplasmic membrane in different types of cells of the same L-colony. The three-layer structure of the membrane does not always display the same distinctness in various L-colony cells and also in different areas of the cell surface. Structureless material of low electron density, possibly a defective murein or its precursor, was revealed on the membrane surface. Electrondense inclusion bodies, mesosomes of ring-shaped or more complicated structure and two-contour vesicles were found in the cytoplasm. The cells multiplied by budding, by binary and anomalies division participation of mesosomes in this process was not proved by the L-forms.

Cell Wall↗
PubMedDate not supplied

[A comparative study of the oxidation processes in the cells of typical forms and L forms of Vibrio cholerae].

A comparative study of metabolic processes in cells of typical forms and L-forms of cholera vibrios has determined a change in the intensity of oxidative processes demonstrated through a decrease in the activity of respiration enzymes (dehydrogenases and diaphorases) and through a restricted transport of electrons along the respiration chain. The facts established evidence for the transition of L-transformed cells into a physiological state with a deficit of substrates and energy as well as with retarded processes of vital activity and repressed mechanisms of reparation of structural elements of a cell.

Glucosephosphate Dehydrogenase↗
PubMed1975

Purification and chemical properities of mouse liver lysosomal (L form) beta-glucuronidase.

The lysosomal form (L form) of beta-glucuronidase was purified 6,500-fold from the liver of C57BL/6J mice with high yield. Purified enzyme was homogeneous as judged by polyacrylamide gel electrophoresis in the presence or absence of sodium dodetcyl sulfate. The microsomal forms of beta-glucuronidase were spontaneously converted to the L form. The purified L form is a tetramer of molecular weight of 280,000 to 300,000, composedd of four identical subunits of 75,000 molecular weight. The enzyme contains a high content of arginine and glutamic acid and a very low content of sulfur-containing amino acids. Approximately 7% of the enzyme molecule is compose of carbohydrate. Sugars in the L form are glucosamine, mannose, galactose, and glucose. Sialic acid and fucose are absent in the enzyme.

Amino Acids↗
PubMed1975

[The ultrastructure of L-forms. III. The L-forms of S. typhi and Pr. vulgaris].

A marked polymorphism was revealed in the colonies of 5--7 day L-forms of S. typhi and Pr. vulgaris: among different types of the cells there prevailed spherical or oval forms with a distinct nucleoid. Three-layer cytoplasmic membranes--the site of formazan TNBT deposition in the reaction for succinic dehydrogenase--were detected on the greater part of the cell surface. Sometimes there were revealed on the surface of the membrane residues of the cell wall in the form of structureless material of low electron density or pieces of external membrane. Myelin-like structures, mesosomes of ring or lamellar structure and two-contour vesicles located directly in the cytoplasm were found in the cytoplasm. L-form cells displayed binary fission or reproduced by budding; in the latter case there formed elementary bodies surrounded by a three-layer membrane, not infrequently with a visible nucleoid and structures resembling mesosomes of the lamellar type.

Cell Division↗
PubMed1978

L-forms of Pseudomonas aeruginosa. 3. The serological cross-reactions among stable L-forms of Pseudomonas aeruginosa, L-form of Streptococcus pyogenes and mycoplasmas.

The serological cross-reactions among stable L-forms of Pseudomonas aeruginosa, or of Streptococcus pyogenes and mycoplasmas were investigated in passive hemagglutination (PHA) and agar gel diffusion tests. (1) PHA active fraction which reacts most strongly with homologous serum was obtained from the sodium dodecyl sulfate soluble fraction of L-form membrane after disruption by Braun cell homogenizer. (2) Antiserum prepared against L-forms in rabbits showed high-level stimulation of PHA antibodies, while it showed little stimulation of agglutinating antibodies. (3) In PHA and agar gel diffusion tests, antiserum to L-form of P. aeruginosa strain IFO-3,455 reacted with L-form of strain N-10, which is serologically different in serotype from strain IFO-3,455. Furthermore, the two L-forms of P. aeruginosa cross-reacted with a L-form of S. pyogenes. 4) L-forms of P. aeruginosa and S. pyogenes did not react with five strains of mycoplasmas in PHA and agar gel diffusion tests.

Antigens, Bacterial↗
PubMed1975

D-alanyl-D-alanine carboxypeptidase in the bacterial form and L-form of Proteus mirabilis.

Membranes of the bacterial form and the stable and unstable L-forms of Proteus mirabilis contain LD and DD-carboxypeptidase. The DD-carboxypeptidase is inhibited non-competitively by penicillin G. The enzyme of the bacterial form is highly penicillin-sensitive (Ki - 4 X 10(-9) M penicillin G). Inhibition is only partly reversible by treatment with penicillinase or by dialysis against buffer. In contrast, the DD-carboxypeptidase of the unstable L-form, grown in the presence of penicillin, is 175-fold less penicillin-sensitive (Ki = 7 X 10(7) M penicillin G). Inhibition is completely reversed by penicillinase or dialysis. After inhibition by penicillin and subsequent reactivation the penicillin sensitivity of the bacterial DD-carboxtpeptidase is similar to the sensitivity of the enzyme of the unstable L-form. The hypothesis is proposed that P. mirabilis contains two DD-carboxypeptidases of different penicillin sensitivity and with different mechanisms of penicillin binding. Peptidoglycan synthesis in the cell walls of the unstable L-form is probably carried out with the help of only one DD-carboxypeptidase, viz. the completely reactivatable enzyme with the lower penicillin sensitivity.

Alanine↗
PubMed1976

Klebsiella L-forms: effect of growth as L-form on virulence of reverted Klebsiella pneumoniae.

A strain of Klebsiella pneumoniae virulent for mice was serially passaged in vitro as a penicillin-induced L-form. Periodically, the L-form was reverted to the bacterial form by removal of penicillin, and the revertant was tested for virulence. Virulence was gradually reduced, and after 109 passages the revertant was totally avirulent. Virulence was not restored by 40 passages of the revertant through mouse peritoneum. The revertant grew less vigorously and did not infect mice when inoculated subcutaneously; in contrast, the parental form was found in all tissues examined. After phagocytosis in vitro or in vivo, the revertant survived but did not increase in numbers, whereas the parental form did increase in numbers. The revertant had a much smaller capsule than did the parental form. Immunization with the live revertant resulted in type-specific protection against infection with the parental form.

Animals↗
PubMed1976

[Ultrastructure of L forms. Report 5. localization of dehydrogenase activity in L form cells].

A study was made of deposition of diformazan TNBT and TCNBT in the presence of succinate and without it in stable L-forms of Str. pyogenes group A, St. aureus and L. monocytogenes. Diformazan proved to deposit on the cytoplasmic membrane, in the lamellar mesosomes and myelin-like structures and also on individual intracellulor membranes not forming special membrane organoids. Diformazan was localized on the membranes mostly asymmetrically, on the cytoplasmic membrane-on its internal side, and on the ring-like intracellulor membranes- externally. Localization of diformazan on the ring-like membranes is atributed to the fact that ring-like membranous structures in the L-forms formed as a result of invagination of the cytoplasmic membrane in the same way as bacterial mesosomes. Since L-form cells could not be released of endogenous substrates by the methods elaborated for bacteria, cytological data did not permit to ascertain dehydrogenases, responsible for asymmetrical localization of diformazan on the L-form membranes. On the basis of these data one can judge only the sum total activity of dehydrogenases in different membranes.

Formazans↗
PubMed1976

Bacteriocin production by group a streptococcal L-forms.

L-forms induced from a bacteriocin-producing strain of group A streptococcus retained both the ability to produce the streptococcin and producer strain immunity to the homologous bacteriocin. L-forms of a spontaneously cured (bacteriocin negative) derivative of this same strain failed to produce streptococcin but were sensitive to its action.

Bacteriocins↗
PubMed1978

Cell wall characteristics of Pseudomonas aeruginosa and its carbenicillin-induced L-form.

L-forms of Pseudomonas aeruginosa were induced and cultured on a medium supplemented with carbenicillin. Morphological studies of the passaged variant revealed the presence of a triple-layered cell wall similar to that found in the parent species. Furthermore, the L-form was found to be more susceptible to gentamicin, kanamycin, tetracycline and colistin sulphate. Chemical analysis of the lipopolysaccharide fraction showed a difference in phosphorus content, and changes in cell wall envelope fatty acid content were also exhibited. It is suggested that these differences may influence the transport of certain antibiotics through the cell wall.

Anti-Bacterial Agents↗
PubMed1979

Studies of colicin action on wall-less stable L-forms of Escherichia coli. I. Degree of attachment and of killing effect on rods and stable L-form cells.

Escherichia coli strains B and K12 W 1655 F+ are able to bind more lethal units of colicins E2, E3, G, H, Ia, and K+ X per one stable L-form cell (of the protoplast type) than per one rod cell; colicin D is bound in a higher amount on E. coli B rods. This pattern remains unchanged, if the same colicins are attached on chloroform-killed cells of both forms. Rods of both E. coli strains are more sensitive to colicins D, E2, E3, K + X (as--in the strain B--to colicin Ia) than cells of the respective L-forms. In the strain W 1655 F+ both cell forms are equally highly sensitive to colicin Ia. The stable L-forms of both strains are much more sensitive to colicins G and H than the rods. Thus the Gram-negative cell wall decreases the probability of a colicin molecule to get attached to its receptor in the cytoplasmic membrane. On the other hand, in E. coli cells the attachment of most colicin molecules to the wall receptors increases the probability of their biological effect. There is no such effect of the wall-attachment on the action of colicins G or H. The strain B is tolerant to colicin E2, while being resistant to E3; thus the cytoplasmic membrane receptor sites for them are not identical.

Adsorption↗
PubMed1978

Effects of magnesium, calcium, and serum on reversion of stable L-forms.

The L-form of Agromyces ramosus was stable in the absence of penicillin when transferred on heart infusion agar containing NaCl and serum. It reverted to its bacterial form, however, when magnesium replaced the serum in this medium. On a dilute medium containing NaCl but lacking serum, the L-form died out unless calcium, magnesium, or serum was added. It grew as the L-form in the presence of calcium of serum but reverted to the bacterial form in the presence of magnesium. Reversion also occurred when magnesium was added to the dilute medium containing serum. Calcium interfered with or prevented the magnesium-induced reversion. The revertant bacterial form resulting from these studies was not NaCl sensitive, as was the case of the bacterial revertant of this organism produced in soil (A. H. Horwitz and L. E. Casida, Jr., Can. J. Microbiol, 24:50--55, 1978).

Bacteria↗
PubMed1992

Effect of Ca2+ and K+ on the intracellular pH of an Escherichia coli L-form.

The L-form NC7, derived from Escherichia coli K12, grew in a complex medium containing 0.2 M-CaCl2 as osmotic stabilizer, but not at pH values above 7.8. The cessation of growth at alkaline pH was not due to cell death. In complex media containing K+ or Na+, the L-form grew ove a wide pH range. Growth at alkaline pH was inhibited by 1 mM-amiloride, indicating that Na+/H+ antiport activity was required for growth at alkaline pH. The internal pH (pHi) of the L-form in media containing K+, Na+ or Ca2+ was constant at about 7.8 to 8.0 at external pH (pHo) values of 7.2 and 8.2. The rates of O2 consumption by intact cells, lactate oxidation by membrane vesicles from cells grown in Ca(2+)-containing medium, and cell division were all strongly repressed under alkaline conditions.

Amiloride↗