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G Burger

Publications and source records attributed to G Burger.

At least 109 records · Page 6Linked to original sources
PubMed1976

Extrachromosomal inheritance in Schizosaccharomyces pombe. I. Evidence for an extrakaryotically inherited mutation conferring resistance to antimycin.

In crosses of [ANTr8] with auxotrophic strains, resistance to antimycin segregates almost 50:50 in random spore analysis with a slight preponderance for the sensitivity allele. Tetrad analysis, however, shows all possible types of tetrads (2:2; 3:1; 1:3; 4:0; 0:4 resistant versus sensitive) with an excess of 2:2 segregations and sectoring of colonies on antimycin medium indicating an extrachromosomal mode of inheritance. The overall ratio of resistant versus sensitive spores is the same as compared with random spore data. Using a mutant blocked in meiosis (mei 1) mitotic segregation of stable diploids is achieved, leading to a ratio of 20% resistant to 80% sensitive clones. Possible reasons for the bias in transmission of the resistance determinant is discussed.

Antimycin A↗
PubMed1976

Extrachromosomal inheritance in Schizosaccharomyces pombe. II. Evidence for extrakaryotically inherited respiratory deficient mutants.

In contrast to the wild-type, mutant [ANTr8] is able spontaneously to throw off stable respiratory deficient mutants. The frequency of these mutants is considerably enhanced by treatment with ethidium bromide (EB) or the azo-dye Janus green (JG). An unstable cell state with a petite-like phenotype is found in both mutant [ANTr8] and wild-type after EB-treatment. However, only in the mutant is this unstable cell state followed by the appearance of stable respiratory deficient (RD) mutants. Formation of microcolonies is observed both in [ANTr8] and wild-type. RD mutants were isolated after EB treatment. Three of them (mit-12, mit-25, and mit-30) were analyzed and mit-25 characterized in more detail.

Ascomycota↗
PubMed1976

Nephelometric density adjustment of leptospiral antigen.

In testing leptospirosis by microagglutination, reproducibility of the results is affected by population age and germ concentration. These undersirable factors can be avoided if antibody identification is made with cultures incubated for 7 to 21 days and adjusted to 50 X 10(6) leptospires per millilitre. Most suitable for the purpose is an analogue mode based on nephelometry and the probability theory. The obtained statistical data furnish calculated and tabulated apparatus values which are used for standardizing with the aid of a newly developed nepheloflask with compression-spring stirrer.

Agglutination Tests↗
PubMed1975

Studies on the mechanism of electron transport in the bc1-segment of the respiratory chain in yeast. II. The binding of antimycin to mitochondrial particles and the function of two different binding sites.

1. In mitochondrial particles antimycin binds to two separate specific sites with dissociation constants KD1 less than 4 - 10(-13) M and KD2 = 3 - 10(-9) M, respectively. 2. The concentrations of the two antimycin binding sites are about equal. The absolute concentration for each binding site is about 100 - 150 pmol per mg of mitochondrial protein. 3. Antimycin bound to the stronger site mainly inhibits NADH-and succinate oxidase. Binding of antimycin to the weaker binding site inhibits the electron flux to exogenously added cytochrome c after blocking cytochrome oxidase by KCN. 4. Under certain conditions cytochrome b and c1 are dispensible components for antimycin-sensitive electron transport. 5. A model of the respiratory chain in yeast is proposed which accounts for the results reported here and previously. (Lang, B., Burger, G., and Bandlow, W. (1974) Biochim. Biophys. Acta 368, 71-85).

Antimycin A↗
PubMed1975

Studies on the mechanism of electron trasport in the bc1-segment of the respiratory chain in yeast. III. Isolation and characterization of an antimycin resistant mutant ANT 8 in Schizosaccharomyces pombe.

1. A mutant (ANT 8) of Schizosaccharomyces pombe which shows resistance to antimycin both in vivo and in vitro is characterized biochemically and genetically. 2. In crosses of ANT 8 with auxotrophic strains, resistance to antimycin segregates 2:2 indicating that resistance is conferred by a single nuclear gene. Diploids heterozygous for the resistance gene, however, show segregation of the resistance and sensitivity during mitosis. Possible reasons for this segregation are discussed. 3. Compared with the wild type, the NADH oxidase of ANT 8 requires 13 times as much antimycin for 95% inhibition. After addition of ubiquinone-3, electron transport which is less sensitive to antimycin is found only in the mutant. 4. The resistance of the mutant ANT 8 si due to the much weaker binding of antimycin to mitochondria. As in the wild type, two antimycin binding sites can be separated by binding studies. From the inhibition curves it is evident that binding of antimycin to oxidized mitochondrial particles does not correspond with its inhibitory effect on the partly reduced enzyme in kinetic studies. 5. The peak of the b-cytochrome absorbing at 560.2 nm at 77 degrees K in the wild type is shifted to 561 nm in the mutant. 6. A special preparation method for mutant mitochondrial particles is described, yielding highly active enzymes and CO-insensitive cytochromes. 7. The results are discussed with reference to the components in our model of the respiratory chain, which may be responsible for this type of resistance.

Antimycin A↗
PubMed1975

[The result-sequence method (sequence analysis) in leptospira research. 3. Communication: The bilateral sequential test (de Boer, Armitage) for testing the difference of mean values of two binomial distributions (author's transl)].

The influence of the liver-activated and non-activated cytostatic drug Cyclophosphamid on the respiration of Leptospira biflexa semaranga Veldrat S 173 was tested in three different concentrations by group-sequential testing of two relative frequencies in a two-sided test-reading. The conditioned probability theta = 0.82 results from thetan = 0.40 and thetaa = 0.75. On account of a practicable sample size, we choose theta' = 0.80 (activated form superior) and theta'' = 0.20 (non-activated form superior). The test-adjusted level of significance is alpha = 0.05 less than beta = 0.10. The expected values for the number of discordant pairs are Etheta' = Etheta'' = 13, Etheta = 1/1 = 14 and Ethetamax = 16. The acceptance inspection performed by control chart and tabulated reference figures results - in comparison with conventional procedures - in savings of discordant pairs of 65 per cent (concentration 10(-4) g/ml) in a decision in favour of activated form, of 65 per cent (concentration 10(-8) g/ml) in an equal efficiency of both states of Cyclophosphamid and of 10 per cent (concentration 10(-11) g/ml) in a non-significant difference. Taking into consideration all unrestrictedly selected pairs, the duration of the experiment takes only 4.25 months instead of 6.75 if the statistical data analysis is not performed conventionally, but group-sequentially instead.

Cyclophosphamide↗