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Biomedical subjects

M Pospísek

Publications and source records attributed to M Pospísek.

11 recordsLinked to original sources
PubMed2006

Immunity to killer toxin K1 is connected with the Golgi-to-vacuole protein degradation pathway.

Killer strains of Saccharomyces cerevisiae producing killer toxin K1 kill sensitive cells but are resistant to their own toxin. It is assumed that in the producer, an effective interaction between the external toxin and its plasma membrane receptor or the final effector is not possible on the grounds of a conformation change of the receptor or its absence in a membrane. Therefore, it is possible that some mutants with defects in intracellular protein transport and degradation can show a suicidal phenotype during K1 toxin production. We have examined these mutants in a collection of S. cerevisiae strains with deletions in various genes transformed by the pYX213+M1 vector carrying cDNA coding for the K1 toxin under the control of the GAL1 promoter. Determination of the quantity of dead cells in colony population showed that (1) the toxin production from the vector did not support full immunity of producing cells, (2) the suicidal phenotype was not connected with a defect in endocytosis or autophagy, (3) deletants in genes VPS1, VPS23, VPS51 and VAC8 required for the protein degradation pathway between the Golgi body and the vacuole exhibited the highest mortality. These results suggest that interacting molecule(s) on the plasma membrane in the producer might be diverted from the secretion pathway to degradation in the vacuole.

Cell Membrane↗
PubMed2002

An improved method for rapid ABO genotyping.

A method for ABO genotyping originally designed by Lee and Chang [3] and further developed by Akane et al. [7] has been even more simplified and improved. We obtained a rapid, robust, sensitive and low cost method for detection of sequence polymorphism of ABO glycosyltransferase gene by changing the MaeII restriction enzyme for its isoschizomer TaiI and by optimization of the condition during digestion and electrophoretic separation.

ABO Blood-Group System↗
PubMed2000

Antifungal properties of substituted 1-phenyl-5-mercaptotetrazoles and their oxidation product, 5-bis-(1-phenyltetrazolyl)disulfide.

The antifungal effect of substituted 1-phenyl-5-mercaptotetrazoles was tested with Candida tropicalis, C. pseudotropicalis, C. mogii, Trichosporon cutaneum, Cryptococcus albidus and S. cerevisiae. Candida strains exhibited the lowest sensitivity to the compounds; the most sensitive was S. cerevisiae. The MIC values ranged from 40 to > 1000 mg/mL. The antifungal effect of halogenated compounds decreased in the series of bromo > chloro > fluoro derivatives. The electrochemical oxidation of substituted 1-phenyl-5-mercaptotetrazole derivatives in an acetonitrile medium was studied as a model for the enzymic oxidation of the substance, including study of the effect of water, perchloric and trifluoromethanesulfuric acids on E1/2 and I1. 5-Bis-(1-phenyltetrazolyl)disulfide, the compound with no antifungal effect, has been identified as the main oxidation product of 1-phenyl-5-mercaptotetrazole.

Acetonitriles↗
PubMed1997

Ammonia mediates communication between yeast colonies.

Under certain growth conditions unicellular organisms behave as highly organized multicellular structures. For example, the fruiting bodies of myxobacteria and of the slime mould Dictyostelium discoideum form structures composed of non-dividing motile cells. Although non-motile, yeasts can create organized structures, colonies in which cells communicate and act in a coordinated fashion. Colony morphologies are characteristic for different species and strains. Here we describe that, in addition to short-range intracolony cell-cell communication, yeasts exhibit long-distance signals between neighbouring colonies. The volatile alkaline compound ammonia, transmitted by yeast colonies in pulses, has been identified as a substance mediating the intercolony signal. The first alkaline pulse produced by neighbouring colonies is non-directed and is followed by acidification of the medium. The second pulse seems to be enhanced and is oriented towards the neighbour colony. Ammonia signalling results in growth inhibition of the facing parts of both colonies. This phenomenon is observed in different yeast genera. The presence of amino acids in the medium is required for ammonia production. Colonies derived from the yeast Saccharomyces cerevisiae shr3 mutant, defective in localization of amino-acid permeases, do not produce detectable amounts of ammonia and do not exhibit asymmetric growth inhibition.

Amino Acids↗
PubMed1996

Isolation and characterization of a new dsRNA virus from Wickerhamia fluorescens.

Virus-like particles (VLPs) were isolated from the yeast Wickerhamia fluorescens strain CCY61-1-1. The VLPs are approximately 42 nm in diameter and contain only one species of dsRNA molecule. The apparent length of the dsRNA determined by native agarose gel electrophoresis was 4.6 kbp. Analysis of protein content of the VLPs showed them to contain one major capsid protein with an apparent molar mass of 74.5 kDa.

Capsid↗
PubMed1994

Isolation and characterization of the dsRNA virus from the yeast Endomyces magnusii.

Virus-like particles (VLPs) have been isolated from the yeast Endomyces magnusii. The VLPs measure 43 nm in diameter and contain six species of dsRNA (0.78, 0.83, 1.77, 1.84, 2.64, 4.30 kb respectively). E. magnusii produces a 'toxic' protein, which reduces the growth, and changes the colony morphology, of sensitive strains of Hansenula sp. growing on solid media. All strains of E. magnusii tested produced the 'toxin' and contained the VLPs. Current procedures of curing failed to destroy the ability to produce the 'toxin'.

Molecular Weight↗
PubMed1994

[Antibiotic activity of cortalcerone and its 7-diphenylhydrazone derivative].

The present paper investigates the antibiotic properties of the novel antifungal antibiotic agent cortalceron and its semisynthetic derivative cortalceron 7-diphenylhydrazone. The MIC values were assayed by the agar diffusion method. Cortalceron was found to weakly inhibit the growth of E. coli and B. subtilis. The growth of yeast was not influenced. On i.v. administration to mice [correction of rats], the agent produced breathing disorders and convulsions which later disappeared. The diphenylhydrazine derivative of cortalceron inhibited the growth of most yeasts tested as well.

Animals↗