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71.
Nucleotide pools of growing,synchronized and stressed cultures of Saccharomyces cerevisiae 总被引:6,自引:0,他引:6
Günther Ditzelmüller Wilfried Wöhrer Christian P. Kubicek Max Röhr 《Archives of microbiology》1983,135(1):63-67
High pressure liquid chromatography has been used to study the acid soluble nucleotide pool of Saccharomyces cerevisiae under different conditions of growth. ATP, ADP, AMP, NAD, GTP, UTP, UDP, CTP, CDP, and UDP-sugars plus UMP could be separated and were found in concentrations higher than 0.1 mumol per g yeast cell dry weight (= detection limit). During glucose-limited continuous culture the levels of individual nucleotides depended on the growth rate, which was most pronounced with pyrimidine (uridine, cytidine) nucleotides. The energy charge (E.C.) remained high (0.9) at all growth rates (0.07-0.3 h-1). During synchronized growth at a constant growth rate (0.11 h-1) almost all nucleotide levels and the E.C. remained at constant values with the only exception of UDP-sugars and UMP of which increased levels were found during the phase of budding. Under conditions of metabolic stress (addition of antimycin A, deoxyglucose plus iodoacetate) pronounced changes in the levels of purine (adenine and guanine) nucleotides and the E.C. were observed. All other nucleotides were less influenced by these conditions. Only under these conditions IMP accumulation was observed. The results strongly argue against the significance of purine nucleotide or E.C. measurements under viable conditions. In contrast, changes in the levels of pyrimidine nucleotides seem to be indicative of changes in the flux through the metabolic pathways where they act as coenzymes. 相似文献
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Christian Walther 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1974,90(1):71-73
Summary Using a method of focal drug application it is demonstrated that high potassium concentration, lanthanum, and black widow spider venom accelerate spontaneous transmitter release inTorpedo electric tissue.This investigation was supported by the Deutsche Forschungsgemeinschaft (Sonderforschungsbereich 138). Thanks are due to Dr. R. Martin and the staff of the Stazione Zoologica, Naples, for supplyingTorpedo, and Dr. N. Frontali, Rome, for a gift of frozen black widow spiders. 相似文献
75.
Christian U. Christensen 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1974,93(2):93-104
Summary A method has been developed which allows perfusion of the blood vessels in isolated pelvic skins ofB. bufo. The effect of various doses of vasotocin (AVT) on net water flux (inside medium 220 mOsM, outside medium 11 mOsM) and active sodium transport were compared in perfused and unperfused skins. The unstimulated water flux (Fig. 3) and the active sodium transport (Fig. 6) were unaffected by perfusion. The threshold for stimulation of water flux was between 0.01 and 0.1 nM vasotocin in perfused skins and between 0.1 and 1 nM in unperfused skins. The threshold for stimulation of active sodium transport was between 0.005 and 0.05 nM vasotocin in perfused skins and between 0.05 and 0.5 nM in unperfused skins. The maximal water flux through perfused skins, 4 l/cm2min, was obtained at 1 nM vasotocin. At 10 nM vasotocin the water flux was only 0.7 l/cm2min in unperfused skins. The maximal active sodium transport was approximately of the same magnitude in perfused and unperfused skins, at 0.5 mM and at 50 nM, respectively. 相似文献
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Zusammenfassung Mit Hilfe von autoradiographischen und elektrophoretischen Methoden wurde die Dottereinlagerung in den wachsenden Oocyten vonMusca domestica untersucht. Sie beginnt nach 30 min im Autoradiogramm sichtbar zu werden. Durch ihre Färbbarkeit und Markierung konnte die Dotterfraktion im Pherogramm von Ovar und Hämolymphe eines mittleren Wachstumsstadiums (Stadium 3) nachgewiesen werden. Nach Abschlu\ der Vitellogenese tritt sie in der Hämolymphe nicht mehr auf. Die Einlagerung der Dotterproteine wird durch Actinomycin gestört, dagegen läuft ihre Synthese nahezu unbeeinflu\t weiter. Die Transporthemmung kann als bisher unbekannter Nebeneffekt des Actinomycins gedeutet werden.
Synthesis of haemolymph proteine and the uptake of the yolk fraction in the oocyte during Actinomycin-treatment. (Studies onMusca domestica)
Summary By means of radioautographic and electrophoretic techniques yolk protein uptake in the growing oocytes ofMusca domestica was investigated. After 30 min yolk protein becomes visible in the radioautograms. By stainability and labeling the yolk fraction could be demonstrated in the pherogram of ovary and haemolymph in an intermediate developmental stage (stage 3). After the end of vitellogenesis it does not appear in the haemolymph. The yolk protein uptake is inhibited by Actinomycin, but the synthesis goes on nearly as normal. This inhibition can be interpretated as a new accessory effect of Actinomycin.相似文献
79.
The predominant spoilage fungi of dried and high-moisture prunes were members of the Aspergillus glaucus group and Xeromyces bisporus. Chrysosporium spp. were also important. At the mean pH of prune flesh (3.8) and at 25 C, X. bisporus grew at water activities (aw) down to 0.605, and Chrysosporium fastidium grew to 0.686. Germination was always followed by growth, but within the 120-day incubation period, the minimum aw permitting asexual sporulation was usually higher than that permitting germination. Sexual sporulation often required an even higher aw. The water requirements of aspergilli were appreciably greater at this pH than near neutrality, no species germinating below 0.738 aw. This was probably a consequence of a high spore-death rate during incubation at low aw and pH. 相似文献
80.
Summary The locomotory turns of the beetle Tenebrio molitor were recorded from free walking animals which were held in stationary position and orientation by means of a tread compensator. Striped patterns revolved around an animal elicit optomotor responses which undergo an inversion at smaller stripe widths. The position of the inversion point characterizes the resolving power of the motion detectors, and corresponds to a 6.5° average angle between the optical axes of interacting elements in the motion detecting device. This indirectly determined value is consistent with the anatomically measured 7° average angle between the axes of neighbouring ommatidia in the Tenebrio compound eye. 相似文献