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I Pfeiffer

Publications and source records attributed to I Pfeiffer.

36 records · Page 2Linked to original sources
PubMed1998

Isolation of dsRNA-associated VLPs from the strain Cryptococcus hungaricus CBS 6569.

Double-stranded RNAs (dsRNAs) with molecular masses 1.7 and 5.0 kbp, respectively, were isolated from the strain Cryptococcus hungaricus CBS 6569. The dsRNAs were copurified with eicosahedric virus-like particles, 29 nm in diameter. This strain produced a protease-sensitive 'toxin' which inhibited the growth of strain C. hungaricus CBS 4214. The toxin had maximum activity at pH 3.7. The highest toxin amount was attained after a culture period of four days.

Cryptococcus↗
PubMed1998

Homothallic life cycle in the diploid red yeast Xanthophyllomyces dendrorhous (Phaffia rhodozyma).

Sexual activity was induced in the basidiomyceteous Phaffia rhodozyma (Xanthophyllomyces dendrorhous) by depletion of nitrogen from the culture medium. This activity involved both mating between two yeast cells and the formation of basidiospores. Mating is possibly started by a G1 phase arrest of the cell cycle, as in other yeasts. The life cycle exhibited homothallic features. Crosses between genetically marked strains, and pulse-field gel electrophoresis of the chromosomal DNA of cells derived from individual spores revealed evidence of karyogamy, meiosis and even recombination. The segregation ratio in tetrads pointed to diploid vegetative cells, which formed tetraploid zygotes and the immediate meiosis then gave rise to diploid progenies again. Apart from the type strain Phaffia rhodozyma CBS 5905, all the examined strains were able to sporulate.

Basidiomycota↗
PubMed1998

A novel method for hybridization of Saccharomyces species without genetic markers.

Protoplasts of Saccharomyces cerevisiae were inactivated by treatment with different concentrations of antifungal compounds for various periods. Of the 14 compounds tested, N-ethylmaleimide proved to be the most efficient. The inactivation effect was fully reproducible. The inactivated protoplasts could be reactivated and still function as fusion partners. They were fused with untreated protoplasts by polyethylene glycol treatment and produced viable hybrid cells. Nuclear and extrachromosomal genetic analysis and chromosome separation of the fusion products from fusion experiments involving inactivated and non-inactivated protoplasts revealed that N-ethylmaleimide did not affect either of the genomes and hence it was perfectly suited for the hybridization of any type yeast cells without genetic markers.

Cell Fusion↗
PubMed1996

Variability and inheritance of double-stranded RNA viruses in Phaffia rhodozyma.

The present survey demonstrates polymorphism in both the length and the number of double-stranded RNAs (dsRNAs) among six Phaffia rhodozyma strains. Strains with one-, three- and four-types of dsRNA molecules were found, while two strains proved to be dsRNA-free. Elongated icosahedral virus-like particles (VLPs) 34x26 nm in size were detected in strains carrying four- or three-types of dsRNAs. One 3.7-kb dsRNA molecule was found not to form part of the VLP genome. Transmission of the VLPs of strain ATCC 24203 was followed through the basidiospores during the sexual cycle. Cytoplasmic inheritance was observed.

Basidiomycota↗
PubMed1995

Further definition of the sequence and position requirements of the arginine control element that mediates repression and induction by arginine in Saccharomyces cerevisiae.

Repression or induction of the genes involved in arginine biosynthesis or catabolism, respectively, both require participation of the ArgRp/Mcm1p regulatory complex. Our previous work showed that those opposite effects were mediated by a similar arginine-responsive element of 23 nucleotides (that we now call ARC, for ARginine Control) situated close to the start of transcription in the repressed promoters and far upstream of the TATA-element in the induced promoters. To define more precisely the sequence and position requirements of the ARC element, we have now characterized by mutagenesis the promoter elements of the arginine-repressible ARG1 and ARG8 genes. We also identify a functional ARC in the CPA1 promoter, thereby confirming, in agreement with our previous mRNA pulse-labelling data, the participation of a transcriptional component in the arginine regulation of that gene otherwise submitted to a translational regulation. From the 12 ARC elements now characterized, we have derived a consensus sequence and show that such a synthetic element is able to mediate ArgRp/Mcm1p-dependent arginine regulation. An important new finding illustrated by ARG1 and CPA1, is that contrary to what all the previous data suggested, repression can be mediated by ARC elements located far upstream of the TATA-box. The new data suggest that the arginine repressor might inhibit transcription in an active process.

Arginine↗
PubMed1995

Isoenzyme, restriction fragment length polymorphism, and random amplified polymorphic DNA characterization of Phaffia rhodozyma Miller et al.

The validity of the species concept was examined with strains of Phaffia rhodozyma by comparing the isoenzyme profiles, ribosomal DNAs, and random amplified polymorphic DNA (RAPD) patterns of the strains. The isoenzyme profiles appeared to be more stable than the RAPD patterns or the electrophoretic karyotypes determined previously (A. Nagy, N. Garamszegi, C. Vágvölgyi, and L. Ferenczy, FEMS Microbiol. Lett., in press). The ribosomal DNA patterns revealed only a limited degree of variability, while RAPD analysis proved to be the most useful method for differentiating the strains studied. Strain CBS 5905T (T = type strain) produced characteristic RAPD patterns, which were different from those produced by the other strains. However, despite the high degree of variability observed, the isoenzyme data and the slightly variable ribosomal DNA hybridization profiles confirmed that the strains which we examined belong to one species.

Base Sequence↗
PubMed1990

Environmental influences on the sensitization by drugs measured in peripheral blood lymphocyte chromatin.

An "allergo-kinetic" method was introduced, which measures early changes of nuclear chromatin structure of lymphocyte subpopulations. The method is used as an in vitro test for drug allergy. The comparison of data from two sampling places (Budapest-Esztergom) shows the following results: The drug allergy scores (obtained from T-cells) may reflect environmental influences on the population under study. During the 13 months period after Atomic Reactor accident in Chernobyl, both the frequency of severe skin manifestations and that of organ manifestations (without skin lesions) increased. The ratio of negative test results decreased in both of drug allergic patient groups (small town = Esztergom, large city = Budapest)--tendency to polysensibilization. The scores obtained in drug related groups of generalized urticaria and Quincke's oedema increased significantly within 13 months after accident followed by a normalization in the subsequent year.

Accidents↗
PubMed1986

Chromatin activation of blood lymphocytes detected by polarization microscopy and cytophotometry.

Blood lymphocytes exhibit chromatin activation upon incubation with substances to which a person is allergic. Chromatin activation can be detected by polarization microscopy. In this work, different methods of evaluating lymphocyte chromatin activation were compared in nine drug-allergic and in eight control subjects. All drug allergics had skin or mucosal involvement, ranging from localized minor herpetic lesions and purpurae through wheal and circumscribed bullous lesions to serum sickness as the most severe form. The mean path difference as the measure of nuclear birefringence was obtained by a polarization microscope using both white light and 551 +/- 7 nm monochromatic light. The equation of Brace-Köhler for converting compensation into path difference for each single cell was used in calculator programs. The values were compared with readings of a cytophotometer operated in transmission mode. Allergy "scores", deriving from the analysis of chromatin activation kinetics due to serial drug dilutions, were also compared using both methods. The results indicate a linear relationship between monochromatic and white light compensation readings and an exponential relationship between mean path difference and mean transmission values at different background amplifications. Operation of the photometer at 25.8% background amplification gave the best correlating results. The two methods gave identical results for the presence (ten tests) or absence (eight tests) of allergy.

Adolescent↗
PubMed1977

Diagnostic value of endoscopic retrograde cholangio-pancreatography in biliodigestive anastomoses.

Endoscopic retrograde cholangio-pancreatography performed in patients with bilodigestive anastomosis may furnish not only reliable radiograms revealing abnormal morphology of the two duct system but allows also endoscopic investigation of the stoma, which is often of equal diagnostic value in such patients. The size of the anastomosis is of crucial importance in such complications as cholangitis and secondary bile stone formation. In a significant portion of patients with biliodigestive anastomoses, i.e. in 75% of the present patient material, a morphologic abnormality could be demonstrated offering in many if not most cases the possibility of a surgical correction and eventual cure of the symptoms.

Adult↗