Use of protoplasts in the improvement of filamentous fungi I. Mutagenization of protoplasts ofOudemansiella mucida

Summary The mutagenic action of ultraviolet light and of N-methyl-N-nitro-N-nitrosoguanidine (NTG) on protoplasts of the basidiomyceteOudemansiella mucida has been evaluated. Since the fungus does not form imperfect spores, we tested the possibilities of using protoplast mutagenesis for improving mucidin-producing strains ofOudemansiella mucida. Protoplasts ofOudemansiella mucida proved to be a convenient starting material for strain improvement and their mutagenization enabled us to obtain not only higher-producing strains, but also auxotrophic mutants, which were used for protoplast fusion experiments.     

Veredelung der Walnuss und anderer Holzarten in der Zeit der echten Winterruhe

Im Verlaufe der Arbeit ist festgestellt worden, dass es nach einer Sprossverletzung von Holzarten in der echten Winterruhe unter günstigen Bedingungen zu einer Aufhebung der Teilungshemmung der Zellen der meristematischen Gewebe in der Nähe der Wunde kommt. Die Kambiumzellen in einer Entfernung einiger mm von der Stelle der Verletzung und die übrigen intakten Gewebe des Sprosses sowie seine Knospen verbleiben im Ruhezustand. Bei einem Veredlungsvorgang in der Ruhezeit verwachsen unter günstigen Bedingungen, insbesondere der Temperatur und Feuchtigkeit, die Veredlungskomponenten ohne dass Knospen an den Pfropfreisern oder den Unterlagen ausschlagen. Die auf Grund dieser Unterlage ausgearbeitete Veredlungsart der Walnussbäume hat sich praktisch bewährt. Auf einem Quadratmeter Vermehrungshaus- oder Erwärmungskammerfläche erzielen bei 26°C und einer hohen relativen Luftfeuchte im Laufe von drei Wochen cca 500 Walnussveredlungen ein Verwachsen. Die Veredlungen werden im Keller oder in einem frostfreien Raume eingeschlagen und im Frühjahre ohne Schutz nicht ausgetrieben in der Baumschule aufgepflanzt. Der Prozentteil der verwachsenden veredelten Pflanzen ist hoch.     

Ecological and production characteristics of the undergrowth of mountain forests

In deciduous and coniferous mountain forests the ecological analysis and biomass production have been studied with a view to the indication parameters of plants for estimating the ecological spectrum and the production capacity of the herbaceous layer. The linkage of natural conditions and the investigated ecological factors was confirmed in comparison with forest communities of the colline belt. The main quantitative and production parameters and theoretical aspects from the ecological analysis of biotopes have been verified by means of theEllenberg method. The establishment of the productivity index makes the estimation of total production possible in conjunction with phytocenological research.     

Membrane potentials in respiring and respiration-deficient yeasts monitored by a fluorescent dye

Changes in fluorescence of 3,3′-dipropylthiodicarbocyanine iodide which had been equilibrated with suspensions of the wild-type yeast Saccharomyces cerevisiae and of respiration-deficient mutants were followed. The changes have been attributed to changes of yeast membrane potentials, since the fluorescence with wild-type yeast could be affected in a predictable manner by uncouplers and the pore-forming agent nystatin. As in other systems, a rise of steady-state fluorescence was ascribed to depolarization and a drop of the fluorescence to hyperpolarization. (1) A considerable rise in steady-state fluorescence was brought about by addition of antimycin A or some other mitochondrial inhibitors to respiring cells. A major part of the composite membrane potential monitored in intact yeast cells appeared to be represented by the membrane potential of mitochondria. (2) Addition of D-glucose and of other substrates of hexokinase, including non-metabolizable 2-deoxy-D-glucose, induced a two-phase response of fluorescence, indicating transient depolarization followed by repolarization. Such a response was not elicited by other sugars which had been reported to be transported into the cells by a glucose carrier or by D-galactose in galactose-adapted cells. The depolarization was explained by electrogenic ATP exit from mitochondria to replenish the ATP consumed in the hexokinase reaction and the repolarization by subsequent activation of respiration. (3) In non-respiring cells only a drop in fluorescence was induced by glucose and this was ascribed to an ATP-dependent polarization of the plasma membrane. (4) Steady-state fluorescence in suspensions of respiration-deficient mutants, lacking cytochrome a, cytochrome b, or both, was high and remained unaffected by uncouplers and nystatin. This indicates that membranes of the mutants may have been entirely depolarized. A partial polarization, apparently restricted to the plasma membrane, could be achieved by glucose addition.     

Ubiquitin metabolism in Chlamydomonas reinhardtii following cold shock

The present work characterizes parameters of ubiquitin turnover in Chlamydomonas reinhardtii Dangeard growing under constant temperature conditions and after an exposure to cold shock. The ratio of free and conjugated ubiquitin to total protein and the rate constant of ubiquitin synthesis and conjugation increased about 2-fold during the first 4 h after cold treatment, whereas the rate constant of ubiquitin degradation reached its maximum 8 h after treatment. The half-life of ubiquitin calculated from the constant of degradation decreased from 6 h to 3.5 h during the first 4 h after completion of the cold treatment. The rate constant of ubiquitin deconjugation did not change after cold treatment. The ratio of free to conjugated ubiquitin decreased temporarily to approximately 8 immediately after cold treatment and increased back to its original value of about 11 at 2 h after cold treatment. These observations raise questions regarding the regulatory mechanisms of ubiquitin synthesis and degradation.     

Phenolic meroterpenoids from the basidiomycete Albatrellus ovinus

From the lipophilic fraction of fresh Albatrellus ovinus, the following substances were isolated and identified: E,E-5-methyl-2-(3,7,11 -trimet     

Possible interrelationship between gluconeogenesis and ketogenesis in the liver

Effeects of various ketogenic substrates on gluconeogenesis from lactate were examined. D,L-3-Hydroxybutyrate (5 mM) stimulated gluconeogenesis by 41%, the effect being the same as that of 5 mM acetate (49%). No stimulating effect of acetoacetate was observed; conversely, acetoacetate (up to 40 mM) partially or completely abolished the observed stimulating effects of acetate, oleate, and 3-hydroxybutyrate. The results suggest that, in intact liver cells, pyruvate is transported into mitochondria in exchange for acetoacetate and that an interrelationship between gluconeogenesis and ketogenesis at the level of mitochondrial pyruvate carrier may exist in the liver.     

Ionophores and intact cells I. Valinomycin and nigericin act preferentially on mitochondria and not on the plasma membrane of Saccharomyces cerevisiae

Valinomycin and nigericin prevented growth of 13 strains of the yeast Saccharomyces cerevisiae on non-fermentable substrate glycerol without affecting much fermentative growth on glucose. The two antibiotics did not induce swelling and lysis of yeast protoplasts in potassium acetate and did not modify uptake and release of Rb⁺ by the yeast cells. Both antibiotics were taken up by yeast cells at a relatively low rate. Nigericin accelerated the glucose-induced changes of fluorescence of a cyanine dye absorbed by yeast cells, which had been previously ascribed to a depolarization-repolarization cycle of the mitochondrial membrane. The data suggest that valinomycin and nigericin act as ionophores in the inner mitochondrial membrane and not in the plasma membrane of intact yeast cells.