Search results for "toxin"
showing 10 items of 1434 documents
Blockage of cell wall receptors for yeast killer toxin KT28 with antimannoprotein antibodies.
1990
Binding of yeast killer toxin KT28 to its primary cell wall receptor was specifically blocked with polyclonal antimannoprotein antibodies which masked all toxin-binding sites on the surface of sensitive yeast cells. By indirect immunofluorescence, it was shown that KT28 binds to the cell wall mannoprotein and that the toxin resistance of mannoprotein mutants (mnn) of Saccharomyces cerevisiae was due to a lack of killer toxin-binding sites within the yeast cell wall. Structural analysis of acetylated mannoprotein from KT28-resistant mutant strains identified the outer mannotriose side chains as the actual killer toxin-binding domains.
Molecular structure of the cell wall receptor for killer toxin KT28 in Saccharomyces cerevisiae
1988
The adsorption of the yeast killer toxin KT28 to susceptible cells of Saccharomyces cerevisiae was prevented by concanavalin A, which blocks the mannoprotein receptor. Certain mannoprotein mutants of S. cerevisiae that lack definite structures in the mannan of their cell walls were found to be resistant to KT28, whereas the wild-type yeast from which the mutants were derived was susceptible. Isolated mannoprotein from a resistant mutant was unable to adsorb killer toxin. By comparing the resistances of different mannoprotein mutants, information about the molecular structure of the receptor was obtained. At least two mannose residues have to be present in the side chains of the outer chain …
Genetic analysis of maintenance and expression of L and M double-stranded RNAs from yeast killer virus K28
1992
The killer phenotype expressed by Saccharomyces cerevisiae strain 28 differs from that of the more extensively studied K1 and K2 killers with respect to immunity, mode of toxin action and cell wall primary toxin receptor. We previously demonstrated that the M28 and L28 dsRNAs found in strain 28 are present in virus-like particles (VLPs) and that transfection with these VLPs is sufficient to confer the complete K28 phenotype on a dsRNA-free recipient cell. We also demonstrated that L28, like the L-A-H species in K1 killers, has [HOK] activity required for maintenance of M1-dsRNA, and predicted that M28 would share with M1 dependence on L-A for replication. We now confirm this prediction by g…
Mannoprotein of the yeast cell wall as primary receptor for the killer toxin of Saccharomyces cerevisiae strain 28.
1987
The killer toxin KT 28 of Saccharomyces cerevisiae strain 28 is primarily bound to the mannoprotein of the cell wall of sensitive yeasts. The mannoprotein of S. cerevisiae X 2180 was purified; gel filtration and SDS-PAGE indicated an estimated Mr of 185,000. The ability to bind killer toxin KT 28 increased during purification of the mannoprotein. Removing the protein part of the mannoprotein by enzymic digestion or removing the alkali-labile oligosaccharide chains by beta-elimination did not destroy the ability to bind killer toxin KT 28. However, binding activity was lost when the 1,6-alpha-linkages of the outer carbohydrate backbone were hydrolysed by acetolysis. The separated oligomannos…
Comparison of the killer toxin of several yeasts and the purification of a toxin of type K2
1984
A total of 13 killer toxin producing strains belonging to the genera Saccharomyces, Candida and Pichia were tested against each other and against a sensitive yeast strain. Based on the activity of the toxins 4 different toxins of Saccharomyces cerevisiae, 2 different toxins of Pichia and one toxin of Candida were recognized. The culture filtrate of Pichia and Candida showed a much smaller activity than the strains of Saccharomyces. Extracellular killer toxins of 3 types of Saccharomyces were concentrated and partially purified. The pH optimum and the isoelectric point were determined. The killer toxins of S. cerevisiae strain NCYC 738, strain 399 and strain 28 were glycoproteins and had a m…
Investigation of a Killer Strain of Zygosaccharomyces Bailii
1993
Summary: The yeast Zygosaccharomyces bailii strain 412 was found to liberate a killer toxin (KT412) lethal to sensitive strains of Saccharomyces cerevisiae and Candida glabrata. Culture supernatants of the killer strain were concentrated by ultrafiltration and the extracellular protein was purified by gel filtration and ion-exchange chromatography. Gel filtration and SDS-PAGE of the electrophoretically homogeneous killer protein indicated an apparent molecular mass of 10 kDa. The killer toxin KT412 is probably not glycosylated since it did not show any detectable carbohydrate structures. KT412 was bound to sensitive but not to resistant yeast cells. The mannan, and not the glucan, fraction …
Botulinum toxin in preparation of oral cavity for microsurgical reconstruction.
2010
CONCLUSIONS: Infiltration of botulinum toxin in the major salivary glands allows a temporary reduction of salivation that begins 8 days afterwards and returns to normal within 2 months. The inhibition of salivary secretion, carried out before the oral cavity reconstructive surgery, could allow a reduction of the incidence of oro-cutaneous fistulas and local complications. OBJECTIVES: Saliva stagnation is a risk factor for patients who have to undergo reconstructive microsurgery of the oral cavity, because of fistula formation and local complications in the oral cavity. The authors suggest infiltration of botulinum toxin in the major salivary glands to reduce salivation temporarily during th…
Squaraine Dyes for Photodynamic Therapy: Study of Their Cytotoxicity and Genotoxicity in Bacteria and Mammalian Cells¶‡
2007
Halogenated squaraine dyes are characterized by long wavelength absorption (>600 nm) and high triplet yields and therefore represent new types of photosensitizers that could be useful for photodynamic therapy. We have analyzed the cytotoxicity and genotoxicity of the bromo derivative 1, the iodo derivative 2 and the corresponding nonhalogenated dye 3 in the absence and presence of visible light. At concentrations of 1-2 microM, 1 and 2 reduced the cloning efficiency of AS52 Chinese hamster ovary cells to less than 1% under conditions that were well tolerated in the dark. Similarly, the proliferation of L5178Y mouse lymphoma cells was inhibited by photoexcited 1 and 2 with high selectivity. …
Evaluation of the genotoxic and cytochrome P450 monooxygenase‐inhibitory potential of dicuran on procaryotic and eucaryotic test systems
2000
The effect of the herbicide Dicuran 500 FL (formulated product) on the phenotypical and genotypical changes in procaryotic and eucaryotic organisms was investigated using short-term tests for detecting genotoxins. Since pesticides discharged in the water environment can modulate the mixed-function monooxygenases (MFO) detoxification system of water organisms, the in vivo and in vitro effects of Dicuran on hepatic cytochrome P450 (cyt P450) monooxygenase activities were also examined in juvenile carp (Cyprinus carpio L.). By measuring the activities of MFO in experimental carp exposed to Dicuran an attempt was made to establish whether Dicuran could be bioactivated by MFO into ultimate mutag…
Evaluation of mycotoxins and their metabolites in human breast milk using liquid chromatography coupled to high resolution mass spectrometry
2014
Humans can be exposed to mycotoxins through the food chain. Mycotoxins are mainly found as contaminants in food and could be subsequently excreted via biological fluids such as urine or human breast milk in native or metabolised form. Since breast milk is usually supposed as the only food for new-borns, the occurrence of mycotoxins in thirty-five human milk samples was evaluated by a newly developed method based on QuEChERS extraction and UHPLC-HRMS detection. The method described here allows the detection of target mycotoxins in order to determine the quality of this initial feeding. The method has been fully validated, with recoveries ranging from 64% to 93% and relative standard deviatio…