Sulla biochimica della fermentazione citrica da parte dell'Aspergillus niger

Summary In a strain ofAsp. niger grown inBernhauer medium, succinic-dehydrogenase activity decreased and asparticglutamic transaminase activity remained practically constant, while citric acid accumulated in the medium.     

Prevention of the formation of mycotoxins in whole wheat bread by citric acid and lactic acid (Mycotoxins in foodstuffs. IX)

Summary Additions of citric acid and lactic acid to whole wheat bread suppress the formation of aflatoxins byAspergillus parasiticus (0.5% citric acid, 0.75% lactic acid) and that of sterigmatocystin byA. versicolor (0.25 and 0.5% respectively).Acknowledgment. I thank Dr.R. Orth (Bundesforschungsanstalt für Ernährung, Karlsruhe, BRD) for the strain ofAspergillus versicolor.     

Über den Intermediär-Stoffwechsel vonAspergillus niger

Summary Oxalic acid is only dissimilated if other carbon sources are present (e.g. citric acid, succinic acid), whereas malonic acid is also dissimilated as a single component byA. niger. It is supposed that the latter is used by the mould not only energetically but also for building up cell substance.     

Über die Grenzen der metabolischen Adaptationsfähigkeit vonAspergillus niger

Summary The ability ofA. niger to assimilate malonic acid, which we consider to be the way both of obtaining energy (citric acid cycle) and of synthesizing cell substances (glyoxylic acid cycle), is reduced by substitution. While methyl malonic acid is quickly assimilated and ethyl malonic acid more slowly propyl-, dimethyl-, and diethyl malonic acid cannot be used by already formed molds.     

Über einen möglichen Weg der Biosynthese der Carotinoide beiMucor hiemalis

Summary Our experiments up to now lead us to the hypothesis, that the biosynthesis of carotenoids may be started on acetyl-coenzyme A. The condensation of two molecules of acetyl-coenzyme A leads to acetoacetyl-coenzyme A which can be regarded as the precursor of-methylcrotonic acid. For a long time the latter compound was postulated as the precursor of the natural isoprene derivatives. The participation of the citric acid cycle in the biosynthesis of carotenoids is discussed.     

Effects of alanine,glycine and glutamic acid on nitrogenous excretion byAmphiuma means liver in organ culture

Summary High concentrations (10 mM) of alanine, glycine, and glutamic acid in the culture medium had no effect on urea production inAmphiuma means liver in organ culture. Ammonia production was increased in media containing added alanine and glycine, but reduced in medium with added glutamic acid.We gratefully acknowledge the support of The Wellcome Trust.     

Light stimulated ‘shunt-metabolism’ succinate-α-ketoglutarate-isocitrate cycle and accumulation of citric acid inAspergillus niger

Summary Studies with light of the visible range had shown that light plays a significant role in the biosynthesis and accumulation of citric acid inAspergillus niger. Accumulation of¹⁴C-labelled carbon atoms in -ketoglutaric, isocitric, succinic and glycolic acids in the cultures grown under illumination suggest a probable shunt-metabolism leading to the succinate--ketoglutarate-isocitrate (SKI) cycle. This shunt metabolism minimizes the accumulation of citric acid in cultures due to depletion of intermediates.Acknowledgment. The authors wish to express their gratitude to the International Atomic Energy Agency, Vienna, Austria, for the financial assistance.     

Oxydation von Bernsteinsäure durch Leber akut urämischer Ratten

Summary The oxydative desamination of amino acids in the liver of acute uremic rats is increased. Simultaneously the citric acid cycle in the liver of these rats is stimulated. It is suggested that the ketone-acids formed by the increased amino acid degradation are removed by the activated citric acid cycle.

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5. Mitteilung über Untersuchungen der Rest-N-fraktionen bei Urämie

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Die vorliegende Arbeit wurde mit Unterstützung des Schweizerischen Nationalfonds durchgeführt.     

Die Wirkung der Askorbinsäure auf die Katalaseinduktion in Mikroorganismenkulturen

Summary Catalase activity ofStaphylococcus aureus increases the effect of ascorbic acid. Namely the ascorbic acid decreases the dissolved oxygen content of the medium, and low oxygen tension is the natural inducer of catalase synthesis.     

Long-chain fatty acid uptake by skeletal myocytes: a confocal laser scanning microscopy study

Studies of regulation of free fatty acid (FFA) utilization by skeletal muscles have focused on plasma FFA delivery and on intracellular factors affecting FFA metabolism. The present study was conducted to directly analyse the uptake process of fatty acids into single myocytes. Cells were isolated from the rat flexor digitorum brevis muscle. Confocal laser scanning microscopy was utilized to analyse the uptake of the fluorescent fatty acid derivative 12-NBD-stearate, which is not metabolized by muscle tissue. Uptake represented a saturable function of the unbound fatty acid concentration in the medium (K _m 366 ± 118 nM, V _max 2.1 ± 0.3 AU/s) and depended on the medium sodium concentration. Reduced buffer pH increased initial uptake rates, whereas lactate (10 mM) had no effect. Membrane hyper- and depolarization decreased uptake rates. This study demonstrates for the first time kinetic data from isolated myocytes with evidence for a carrier-mediated transport mechanism for long-chain fatty acids. Received 31 March 1998; accepted 8 May 1998     

Inhibitory influence of acid citrate dextrose on the activity of dehydrogenase in erythrocytes

Zusammenfassung Der viel verwendete gerinnungshemmende Zusatz ACD (acid citric dextrose) vermindert die Aktivität der Glucose-6-Phosphat-Dehydrogenase und anderer Dehydrogenasen der Erythrozyten. Diese Wirkung kommt durch pH-Verschiebung zustande.     

L'acide borique,inhibiteur de la copulation gamétique chezAllomyces

Summary Addition of a tiny crystal of boric acid to a drop of buffered water containing male and female gametes ofEuallomyces javanicus completely inhibits copulation in this water mold.Pure gametophytic growth can thus be secured by addition of 1/15,000 boric acid to the starch-yeast extract medium.

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Communication annoncée mais non présentée au VIII^e Congrès international de Botanique, Paris 1954.     

β-(6-Bromopyridin-3-yl)alanine. A new plant growth regulator

Summary The heterocyclic amino acid, -(6-bromopyridin-3-yl)alanine [DL-a-amino--(6-bromopyridin-3-yl)propanoic acid], interferes with the morphological development of the cruciferArabidopsis thaliana when incorporated in the growth medium. It appears to overcome the normal apical dominance control mechanism within the seedling, producing multirather than single-stemmed plants.     

Regulation of ppApp synthesis during sporulation of a conditionally asporogenous rifampin mutant ofBacillus subtilis

Summary The intracellular synthesis of ppApp in a conditionally asporogenous rifampin-resistant mutant ofBacillus subtilis stimulated to sporulate in the Sterlini-Mandelstam (SM) medium supplemented with ppApp is negligible and comparable to that of the non-sporulating culture. The formic acid extract from the sporulating culture stimulates sporulation of the mutant in SM medium.This paper was presented at the Annual Meeting of the American Society for Microbiology in Dallas, Texas, in March 1981. This work was supported in part by a grant from Research Corporation, New York, N.Y., USA.     

The halophilic properties of pyruvate kinase fromVibrio costicola,a moderate halophile

Summary Pyruvate kinase fromVibrio costicola, a moderate halophile, appears to be adapted to functioning in the presence of salt. Its stability depends on the ionic strength of the medium. The amino acid composition resembles that of other halophilic enzymes. It is proposed that the halophilic pyruvate kinase utilizes preferentially the Mn⁺⁺ cofactor which forms more stable complexes in the presence of physiological concentration of salt.     

A quick and modified Winkler-method for measuring O2-concumption of aquatic animals

Summary A modified procedure for measuring O₂-consumption, based on Winkler-method, is described. Instead of KI and HCl (or H₂SO₄) triphenylmethane-dye leukoberbelinblue I and citric acid are used.Acknowledgment. Md. B. expresses his gratitude to DAAD (German Academic Exchange Service, Bonn) for awarding him a post-doctoral fellowship, during the tenure of which this investigation was carried out.     

Macronuclear response ofParamaecium multimicronucleatum tol-lysine

Summary A strain ofParamaecium multimicronucleatum was exposed to a medium containingl-lysine; the concentrations of the amino acid were 0.1%, 0.5% and 1.0% for different sets of experiments. In these two latter concentrations, the macronucleus of the ciliate broke down into innumerable small fragments, the microspheres. The micronuclei remained inert. The microspheres left the body of paramaecium as cell-free, self-duplicating entities constituted of DNA and RNA and enveloped by a protein coat. They had no nuclear membrane and they resembled the prokaryotes. Grown in culture medium with 0.1% horse serum, the microspheres transformed into small amoebae having typical eukaryotic features. These amoebae maintained a typical cyst-trophic cycle during the successive sub-cultures; they had no similarity with the paramaecia.     

Produktion von Acetylmethylkarbinol durch Aktinomyzeten

Summary The production of acetylmethylcarbinol by various strains of actinomycetes was established. The biosynthesis of acetylmethylcarbinol depends largely on the composition of the fermentation medium and on the presence of arsenite, which regulates the metabolism of pyruvic acid. In the case ofStreptomyces aureofaciens the stimulating effect of phosphate on the production of acetylmethylcarbinol gives a partial explanation of the well-known negative effect of phosphate on the biosynthesis of chlortetracycline.