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Biomedical subjects

O A Chernova

Publications and source records attributed to O A Chernova.

17 recordsLinked to original sources

[Interaction of Mycoplasma with immune system of animals and humans].

Mycoplasmal infections of animals and human belong to latent or chronic ones, being commonly accompanied with immunodeficiency symptoms. The following topics are discussed in this review: 1) a direct influence of mycoplasmas on the immune system cells with an interference and compression of the functional activity of these; 2) influence of mycoplasmas on the immune system via cytokine induction; 3) mitogenes and mitogenic action of mycoplasmas; 4) the role of mycoplasmas in the development of autoimmune processes. Basic host immune response to mycoplasma is presented in diagrams.

Animals↗

Topoisomerase I-recognition-like sites in mycoplasma genomes.

Repeated nucleotide sequences fitting the motif TGTTTGAAAAACTGA have been found in the Mycoplasma bovis genome. The tetradecamer sequences are also in spacer regions of rRNA operons of some species of Mollicutes. The sequences look like the DNA sites recognized by topoisomerase I from Tetrahymena pyriformis. Imperfect copies of the sequences are known to be in genomes of viruses, lower and higher eukaryotes.

Animals↗

[Mycoplasmas].

Structural peculiarities of the mycoplasmas--the smallest prokaryotic organisms--are reviewed, in addition to their complicated relationships with the eukaryotic cells and with the whole organisms of plants and animals.

Animals↗

[The Mycoplasma genome].

A review is presented of the available data on the nature of chromosomal and extrachromosomal DNA of Mollicutes (mycoplasmas)--the smallest and simplest procaryotic organisms.

Base Sequence↗

[Detection and identification of Mycoplasma infections by DNA hybridization].

Infection of cell cultures by mycoplasmas can be detected by hybridization of the DNA of suspected cell cultures with recombinant plasmids containing fragments of the mycoplasma DNA. The test is very sensitive and allows detection of as little as 1 ng of mycoplasmal DNA, roughly equivalent to the DNA amount of 10(6) mycoplasmas. This approach turns out to be effective for detection and identification of mycoplasmas in clinical material, plant and insect tissues. A set of DNA probes for detection of mycoplasmas infecting cell cultures by dot hybridization has been constructed. This set consists of specific DNA probes and universal DNA probe. Recombinant plasmids, pAl32, pMa13, pMh9, containing specific DNA fragments of Acholeplasma-laidlawii, Mycoplasma arginini, Mycoplasma hominis (the prevalent mycoplasma contaminants of home cell cultures) are species-specific DNA probes. Recombinant plasmid pMg16 containing rRNA genes of Mycoplasma gallisepticum is the universal DNA probe for detection of any mycoplasma (or any prokaryote) contaminations. These two classes of DNA probes may be considered as complementing each other. These 32P labeled probes do not hybridize with eukaryotic DNA. The set of DNA probes allows not only to detect infection of cell cultures by mycoplasmas but also to identify the species of mycoplasmas and to evaluate the multiplicity of mycoplasma infection.

Animals↗

[Adaptive reactions of mycoplasmas in vitro: "viable but unculturable forms" and nanocells of Acholeplasma laidlawii].

The adaptation of Acholeplasma laidlawii to conditions unfavorable for growth has been found to be accompanied by cell transformation into special morphological structures known as ultramicroforms (nanocells). The ratio of the cells of the two morphological types in the population depended on the growth conditions. Nanocells retained viability for a long time under conditions unfavorable for growth and showed resistance to stressors. Reduction in the cell size occurred due to unequal division, which involved the loss of cytoplasmic material. A. laidlawii ultramicroforms (nanocells) were able to restore proliferative activity and to revert to their initial vegetative form; they measured less than 0.2 microm and are the smallest cells known at present. Nanocells formed in vitro under exposure to abiogenic stressors may correspond to the A. laidlawii minibodies observed in infected plants upon exposure to biogenic stressors. The transformation of A. laidlawii cells into ultramicroforms was accompanied by condensation of the nucleoid, a change in the polypeptide spectrum, and a change in the availability of rRNA operons for in vitro amplification. All these changes are indicative of reorganization of the genetic and metabolic systems of mycoplasmas.

Acholeplasma laidlawii↗