Growth of Streptomyces bambergiensis and glucose isomerase biosynthesis

Summary Growth and glucose isomerase biosynthesis in Streptomyces bambergiensis ATCC 13879 have been studied under different conditions. Some data concerning correlation between cultivation conditions and elemental analysis of the cells are also presented.     

Influence of physiologically active substances of the soil humus on the activity of glucose-6-phosphate-dehydrogenase in pea (Pisum sativum L.) roots

The influence of phenolic and humic acids on the activity of glucose-6-phosphate-dehydrogenase in the roots of pea under aseptic conditions has been investigated. It seems clear that vanillic and protocatechuic acids inhibit the enzyme activity in the excised roots of pea, but their dry weight increases in relation to the control. Gallic acid stimulates the G-6-PD activity in the roots of whole plants. The humic acids influence neither the enzyme activity nor the dry weight of pea seedlings after short-term treatment.     

Some characteristics of mitochondrial multienzyme systems from rat liver mitochondria after heating of rats]

A character of rat liver mitochondria degradation after the heat treatment of animals is studied. It is found that mitochondria under the effect of elevated temperature do not considerably change their functional characteristics and thus they are capable to provide the normal rate of ATP synthesis, the rate of succinate oxidation being slightly increased. At the same time the heating caused the degradation of mitochondria which results in the decrease of their thermostability, in the increased susceptibility to lytic effect of trypsin and phospholipase D, and in the activation of succinate dehydrogenase and cytochrome c oxidase. The mitochondria degradation is due to the formation of "latent impairments" in the structure of mitochondria.     

Die submontanen krautreichen Buchenwälder auf Silikatböden der westlichen Tschechoslowakei

Die submontanen krautreichen Buchenwälder auf Silikatböden in der westlichen Tschechoslowakei (Tschechische Sozialistische Republik) zerfallen in vier Assoziationen: 1.Tilio cordatae-Fagetum Mráz 1960 em.Moravec 1977, 2.Tilio platyphylli-Fagetum Klika 1939, 3.Melico-Fagetum Seibert 1954 und 4.Carici pilosae-Fagetum Oberdorfer 1957. DasTilio cordatae-Fagetum ist an niedrigere Bergländer Mittel-, Süd- und Westböhmens gebunden. DasTilio platyphylli-Fagetum ist eine lokal bedingte Assoziation des Westteils des Gebirges ?eské st?edoho?í. DasMelico-Fagetum kommt in Nord- bis Ostböhmen und Nord- und Mittelmähren vor. DasCarici pilosae-Fagetum ist auf die Karpaten beschränkt (ausnahmsweise greift es auf den Ostrand des Böhmischen Hochlandes über). Die Buchenwälder des Hügellandes bei Jevany (Mittelböhmen) und des Gebirges ?elezné hory gehören, trotz dem Vorkommen in submontanen Lagen, demDentario enneaphylli-Fagetum Oberdorfer ex W. etA. Matuszkiewicz 1960 an. Die Zusammensetzung der Assoziationen ist durch pflanzensoziologische Tabellen belegt und ihre Verbreitung auf einer Punktkarte erfasst.     

Responses of epidermal diffusive conductance to simultaneous changes in two factors: Determination of interactions

Responses of the epidermal diffusive conductance (gep) to irradiance (I) during ontogeny of primary bean leaves or during their wilting were followed. Effects ofI, leaf age and leaf water potential (Ψw) as well as interactive effects (I × leaf age andI × Ψw) ongep were statistically significant.     

Partial purification of alpha-hemolysin inEscherichia coli

The present paper describes isolation and purification ofa-hemolysin ofEscherichia coli. The optimum production medium was found to be the Todd—Hewitt broth. Out of thirteen fractions obtained after separation on Sephadex G-200, two fractions possessed the highest relative specific activity.     

Dictyostelium myosin II heavy-chain kinase A is activated by heparin, DNA and acidic phospholipids and inhibited by polylysine, polyarginine and histones.

Dictyostelium myosin II heavy-chain kinase A (MHCK A) is activated by autophosphorylation. Heparin and DNA, as well as vesicles composed of phosphatidylserine or phosphatidylinositol, were found to increase the initial rate of MHCK A autophosphorylation 5-10-fold in a Ca(2+)-independent manner. The negatively charged molecules also increased the activity of the autophosphorylated MHCK A by about 2-fold. In contrast, positively charged polypeptides such as poly(D-lysine), poly(L-lysine), poly(L-arginine) and histones strongly inhibited (IC50 of 0.5 micrograms/ml) the activity of the active, autophosphorylated MHCK A. Similar levels of inhibition, on a weight basis, were observed for poly(L-lysine) fractions with molecular weights from 3800 to 150,000-300,000. The inhibition was competitive with respect to peptide substrate and mixed with respect to ATP. At much higher concentrations poly(L-lysine) also inhibited the ability of MHCK A to autophosphorylate. It is proposed that negatively charged compounds and autophosphorylation increase the activity of MHCK A by weakening the interaction between the catalytic domain and a positively charged autoinhibitory domain.     

Genome modifications in protoplast-derived tobacco plants: Contents of repetitive DNA sequences

Plasticity of the tobacco genome was studied by testing the DNAs of protoplast-derived regenerants with three different repetitive DNA sequences by the method of quantitative DNA/DNA hybridizations. A large population of 91 regenerants belonging to 35 different protoclones was analysed and a high degree of heterogeneity in the contents of the different DNA repeats was detected. The contents of middle repetitive sequences of two types were more stable or changed in the same direction, while the highly repetitive sequence varied independently and displayed a significant reduction in comparison with the two other sequences. Comparing the variation within the subpopulations of plants of the same clonal origin and the variation among the protoclones led to a conclusion that the pre-existing DNA variability in the starting plant material and/or thein vitro stress during the very early stages of protoclone regeneration played a decisive role in the formation of modified genomes in regenerants.     

Effect of stobadine on indomethacin- and ethanol-induced stomach lesions and gastric secretion.

Stobadine was found to inhibit the ulcerogenic activity of indomethacin in relation to the dose but was ineffective against the direct necrotizing action of ethanol. It also inhibited gastric acid secretion when administered intraduodenally. Although stobadine is considered to be a scavenger of free radicals, our results indicate that, under the given experimental conditions, it is rather the inhibition of gastric acid secretion that is responsible for its antiulcerogenic effect. The preliminary results do not allow the exclusion of other mechanisms for explaining its antiulcerogenic effect.