bluuebunny/crossref_metadata_2025 huggingface dataset:
RhodosporidiumBANNO: Dosiseffektbeziehungen, Mutageneffektivität und Mutantenspektrum bei der Induktion Auxotrophie verursachender Mutationen durch ultraviolettes Licht und N‐Methyl‐N′‐nitro‐N‐nitrosoguanidin
Authors: Böttcher F. , Samsonova I. A.
Published: July 2010

The kinetics, efficiency, and specificity of induction of forward mutations to auxotrophy by ultraviolet light (UV) and N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG) was examined in stationary phase cells ofRhodosporidium(Rhodotorula) wild strain Rgl.

In comparison to the spontaneous level the frequency of auxotrophic mutants was increased more than 1000 times by both mutagens, however, the mutagenic efficiency of MNNG was higher than that of UV. We found that the forward mutation rate is a linear function of the applicated UV and MNNG doses in the range to 600 J m−2or 25 mm x min, respectively.

The 35 studied biosynthetic pathways to amino acids, purines, pyrimidines, and vitamins are genetically blocked at different frequencies, but there is not any significant difference between UV and MNNG induced frequencies of mutants with a specific requirement. However, in difference to the approximately equal distribution of the MNNG‐inducednicmutants among the genetic blocks of the tryptophan‐nicotinamide pathway, UV‐inducednicmutants occurred with a higher frequency in the genes of the tryptophan pyrrolase and the 3‐hydroxykynureninase than in the genes of the other enzymes of the pathway.
Hemmung der Chitin‐Synthetase von Mucor rouxii in vitro durch Fungicide und andere Wirkstoffe
Authors: Lyr H. , Seyd W.
Published: July 2010

Comparative investigations on the inhibition of chitin synthetase of Mucor rouxii revealed that in contrast to results obtained in vivo, only few fungicides and other compounds inhibit the enzyme in vitro. Besides the well‐known effect of polyoxin D, an inhibition was demonstrated for terrazol, tridemorph, hinosan, and formulated preparations of dimilin (PH 60‐40, 60‐38). The latter preparations, however, showed growth inhibition also with fungal species which do not synthesize chitin and the pure compounds are ineffective.

Inhibition by phospholipase C, unsaturated fatty acids, and the reversibility of the inhibition caused by terrazol after addition of procain‐hydrochloride demonstrates that phospholipids are essential for the activity of the enzyme, whereas sterols seem to be ineffective. Action of trypsin, PCNB, pentachlorophenol, and some similar compounds results in significantly increased activity, which in the case of trypsin could be due to the hydrolysis of a protein inhibitor. Hinosan inhibits the enzyme indirectly in a still unexplored manner.
Manganese oxidation by an intracellular protein of a Pseudomonas species
Authors: Jung W. K. , Schweisfurth R.
Published: July 2010

Cultures of a Pseudomonas sp. strain MnB 1 produce an intracellular, managanese oxidizing protein (abbrev. as Mn ox. protein) during the stationary phase of growth. This protein is heat labile, can be inactivated by protease and has a pH‐optimum for manganese oxidation at pH 7.0. Mn2+ is oxidized only at concentrations below 3 · 10−5 M. The occurrence of the protein is not dependent on the presence of Mn2+, but is clearly related to the cessation of growth after the end of the exponential growth phase Oxygen, coenzymes, and low molecular weight components of the cell extract seem not to be involved in the rection as electron acceptors for the oxidation of Mn2+. Continued managanese oxidation by Mn ox. protein results in a progressive decrease in activity which corresponds to the amount of formed manganese oxide.
Steroidumwandelnde Enzyme aus Mikroorganismen IX. Affinitätschromatographische Präparation und Untersuchung des Apoenzyms einer 4‐En‐3‐oxosteroid: (Akzeptor)‐1‐en‐oxidoreduktase aus Nocardia opaca
Authors: Atrat P. , Deppmeyer V. , Hórhold C. , Móller L.
Published: July 2010

From the flavoenzyme, 4‐en‐3‐oxosteroid: (acceptor)‐1‐en‐oxidoreductase of Nocardia opaca, prosthetic group and apoenzyme were separated quantitatively by means of affinity chromatography in the presence of 2 M (NH4)2SO4 at pH 3.0. Subsequently the apoenzyme was eluted from affinity matrix by 0.01 M phosphate buffer, pH 8.0, whereas under these conditions the intact enzyme could not be eluted. The whole enzyme activity applied could be restored by incubation of the eluted apoenzyme with FAD. The binding strength of the apoenzyme to the immobilized steroid ligand is highly decreased in comparison to the native enzyme and can be interpreted by the action of rest hydrophobicity. That indicates the essential character of FAD for both ligand binding and transformation.
Influence of pesticides on the growth of cyanobacteria
Authors: Hutber G. N. , Rogers L. J. , Smith A. J.
Published: July 2010

Two unicellular and two filamentous cyanobacteira (blue‐green algae) were exposed under conditions optimal for photoautotrophic growth to eleven pesticides. Low concentrations (0.01 to 5 ppm) of diuron, atrazine, and paraquat inhibited growth. With MCPA, MCPP, 2,4‐D, milstem and ethrel, marked inhibitory effects were achieved only at concentrations above 100 ppm. Growth was inhibited by glyphosat, DDT, and thiram at intermediate concentrations. In some cases, the effective concentration of the pesticide varied considerably with the organism tested.
Effect of nutrients on the toxicity of pesticides carbofuran and hexachlorocyclohexane to blue‐green alga Nostoc muscorum
Authors: Kar S. , Singh P. K.
Published: July 2010

The effects of various levels of nutrients like potassium phosphate (dibasic), calcium nitrate, and calcium chloride individually and in combinations were studied on the toxicity of the commonly used pesticides carbofuran and hexachlorocyclohexane (HCH) in growth medium to the N2‐fixing blue‐green alga Nostoc muscorum. It was observed that all these chemicals had some effects on toxicity. The toxicity of both carbofuran and HCH was reduced to some extent in the presence of higher concentrations of the nutrients when compared to normal levels of the chemicals in the medium. The higher doses of nutrients in combinations antagonized the effect of individual treatment and enhanced the toxicity of pesticides.
Alcohol‐induced switching over of metabolic flux in Streptomyces noursei JA0 3890b
Authors: Gräfe U. , Schade W. , Bocker H. , Thrum H.
Published: July 2010

Short‐chain alcohols, benzyl alcohol and Tween 20 were found capable of switching over the metabolic flux in Streptomyces noursei JA 3890b from the preference of oxidative deamination of alanine towards the reinforced acquisition of NH. These changes were correlated to the decrease of the ratio of saturated to olefinic fatty acids in the mycelium, suggesting that alcohols and other polar lipophilic compounds can interfere with the biosynthesis and the function of the cytoplasmic membrane in Streptomyces.
Agglutinationsverhalten von Hefen mit Lektinen
Authors: Meinhold I. , Gabert A. , Wünsche L. , Roth P.
Published: July 2010

Es wurden ca. 160 Hefestämme aus verschiedenen Familien, Gattungen und Arten der Ascomyceten. Deuteromyceten und Basidiomyceten bei konstanter Zellzahl und Lektinkonzentration auf ihre Agglutinierbarkeit durch Lektine getestet (Concanavalin A, Lens culinaris‐Hämagglutinin, Weizenkeimlingsagglutinin, Dolichos biflorus‐Agglutinin, Erdnuß‐Hämagglutinin, Ricinus communis‐Hämagglutinin). Dabei ergaben sich gruppenspezifische Agglutinationsmuster. Ein Stamm der Art Rhodosporidium toruloides kann durch Weizenkeimlingsagglutinin zur Agglutination gebracht werden.

Einige Hefestämme der Gattung Rhodotorula und Rhodosporidium lassen sich durch die untersuchten Lektine nicht agglutinieren. Sie besitzen offenbar gegenüber den anderen geprüften Hefen deutlich abweichende Zellwandstrukturen.
Unterschiedliche Empfindlichkeit der Phagen T3, T7, T4 und Lambda gegen Bleomycin und Phleomycin
Authors: Scholz D. , Meissner Ch. , Rosenthal H. A.
Published: July 2010

In contrast to phage lambda the phages T3, T7 and T4 are not inhibited by as much as 150 μg bleomycin/ml, while the chemically related antibiotic phleomycin increasingly inhibits the propagation of the phages in the order T4‐T3‐lambda. 20 μg phleomycin/ml inhibit T3 by 95%.

The resistance against bleomycin is surprising, because 10 μg BM/ml block completely the colony‐forming capacity of the host bacterium. The drug resistance of the phage growth correlates with the weak decrease of phage DNA synthesis, while the host cell DNA synthesis ceases rapidly. In accordance with these data is thein vivoinhibition ofEscherichia colicells and thein vitrodegradation of their DNA. However, a contradiction exists between thein vivoresistance of T3 and T4 and thein vitrosusceptibility of their DNA against nucleolytical fragmentation by bleomycin.

The mechanism of the insensitivity of T3, T7 and T4 against bleomycin is unknown.
Purification and properties of a fibrinolytic enzyme from Bacillus subtilis
Authors: Fayek K. I. , El‐Sayed Sanaa T.
Published: July 2010

A fibrinolytic enzyme obtained from B. subtilis was purified, using DEAE‐cellulose column chromatography, and gel filtration on Sephadex G‐100. The preparation was homogeneous as tested by gel filtration on Sephadex G‐200, and disc electrophoresis.

The molecular weight of this enzyme was 29.400 estimated by gel filtration on Sephadex G‐100. The optimum pH for enzyme activity was 7.2. Copper ions significantly increased enzyme activity, while Zn++ and Mn++ caused marked inhibition.
Regulation of NAD+‐ and NADP+‐linked isocitrate dehydrogenase in the obligate methylotrophic bacterium Pseudomonas W6
Authors: Hofmann K. H. , Babel W.
Published: July 2010

Cell‐free extracts of the obligate methanol‐utilizing bacterium Pseudomonas W6 catalyze the oxydation of isocitrate to α‐ketoglutarate in the presence of NAD+ and NADP+. After electro‐focusing of the crude extract of Pseudomonas W6 actually two distinct bands each of NAD+‐linked isocitrate dehydrogenase (NAD+‐IDH) and of NADP+‐linked isocitrate dehydrogenase (NADP+‐IDH) could be observed. The NAD+‐IDH was completely separated from the NADP+‐IDH by employing DEAE ion exchange chromatography and further purified by affinity chromatography using Cibacron blue F 3G‐A.

The NAD+‐IDH was inhibited by a high energy charge, whereas the NADP+‐IDH was found to be independent of energy charge. Consequently the NAD+‐IDH showed the control behaviour of an enzyme of an energy‐generating sequence which, however, equally fulfils a catabolic and an anabolic function. With respect to the inhibition by reduced pyridine nucleotides and α‐ketoglutarate differences between NAD+‐IDH and NADP+‐IDH were also found. Only the NADP+‐linked enzyme exhibited a feedback inhibition by its reaction products α‐ketoglutarate and NADPH. This control behaviour gives evidence for the biosynthetic function of the NADP+‐IDH. These results confer an amphibolic character to the sequence from citrate to α‐ketoglutarate in the incomplete citric‐acid cycle of Pseudomonas W6.
Control by phospho‐adenosinediphospho‐ribose of NADP‐dependent isocitrate dehydrogenase and 6‐phosphogluconate dehydrogenase in Streptomyces griseus
Authors: Gräfe U. , Bormann E. J. , Truckenbrodt G.
Published: July 2010

The metabolic function of NAD(P)‐glycohydrolase in the streptomycyin‐producing Streptomyces griseus was investigated. Phospho‐adenosinediphospho‐ribose, the product of NAD(P)‐glycohydrolase reaction was shown to interfere as a competitive inhibitor not only with the glucose‐6‐phosphate dehydrogenase (Voronina et al. 1978) but also with the NADP‐dependent isocitrate and 6‐phospho‐gluconate dehydrogenases. Inhibition kinetics were studied with isocitrate dehydrogenase from pig heart and 6‐phosphogluconate dehydrogenase from yeast as well as with mycelial extracts of a mutant of S. griseus lacking NAD(P)‐glycohydrolase.
Study of inulase from Debaryomyces phaffii Capriotti
Authors: Demeulle S. , Guiraud J. P. , Galzy P.
Published: July 2010

Debaryomyces phaffii posesses an inulinase activity which can be induced by growth on β‐fructosidase and particularly on inulin. The enzyme is located in the cell wall but is easily excreted into the culture medium. Maximum activity on inulin is observed at pH 4 and 50°C. The Km on inulin is 1.2 · 10−2 m. The enzyme breaks down inulin by splitting off terminal fructosyl units and it is active on sucrose and raffinose.
Regulation of phenol degradation in Pseudomonas putida
Authors: Janke D. , Pohl R. , Fritsche W.
Published: July 2010

In order to characterize the ability of Pseudomonas putida (Trevisan 1889) Migula 1895 strain H to degrade various mono‐ and diphenolic aromatic compounds, respiratory activities towards phenol, catechol, and the cresol isomers were determined. The following rates of oxygen uptake (Qo2) were obtained with resting phenol‐grown cells: phenol – 229, o‐cresol – 231, m‐cresol – 43, p‐cresol – 200, catechol – 262. All these compounds were oxidized by a two‐phase‐kinetics, the first phase is characterized by a higher oxidation rate than the second. The oxidation of phenol as well as of p‐cresol was found to be substrate‐inhibited at concentrations above 0.25 mM. A Ki‐value of 100 mg/I was calculated for phenol oxidation. The phenol‐degrading enzyme system is induced, probably coordinatively, by phenol and the cresol isomers. In strain H the degradation of phenol is carried out simultaneously with the assimilation of natural carbohydrates like glucose and sodium pyruvate. Aniline as well as sodium benzoate, though not metabolized by strain H, cause a concentration‐dependent inhibition of phenol degradation in resting phenol‐grown cells of that strain. The mechanism of this inhibition is discussed.
Möglichkeiten zur gezielten Manipulation der Genexpression des mikrobiellen Sekundärstoffwechsels
Authors: Gräfe U.
Published: July 2010

The present review deals with some theoretical and applied aspects of directed manipulations of control mechanisms governing the expression of microbial secondary metabolism. In attempting to make broad generalizations, the production of secondary metabolites is discussed in terms of the cellular differentiation of relevant organisms. On the basis of the actual information about the regulation of microbial idiolite synthesis, some potential ways for the quantitative and the qualitative improvement of secondary metabolite production are discussed. A number of examples demonstrate the effectiveness of rational strategies of strain development, e. g., the removal of non‐specific repressions of secondary metabolism by environmental factors, the excessive production of precursors due to altered control of intermediary metabolism, the increased resistance of producer organism against the autotoxicity of some idiolites, the deletion of alternative pathways of the primary and secondary metabolism, manipulations concerning the product spectrum, the deletion of feedback mechanisms, and elimination of degradating pathways in the secondary metabolism etc.

The scope and limitations of rational strategies of strain improvement by genetic and physiologic manipulations are subjected to final discussion.
Further studies on a temperature‐sensitive mutant of Escherichia coli with defective repair capacity
Authors: Morfiadakis Irene , Geissler E.
Published: July 2010

A temperature‐sensitive mutant of E. coli, WG24, was studied with respect to its sensitivity to photodynamic action, its capacity to perform host controlled reactivation, and its sensitivity to transduction at elevated temperatures. Mutant cells are much more sensitive than wild type cells to photodynamic action by thiopyronine and visible light at elevated temperatures. As well defined rec mutants, WG24 cells are less able to reactivate UV irradiated λc phages at elevated temperatures, while their ability to repair T1 phages is less impaired. Mutant cells cannot be transduced to T6 resistance at a detectable rate at elevated temperature. It is concluded, therefore, that some rec gene carries a ts mutation in this mutant.
Enzymes of glucose isomerization in various microorganisms
Authors: Suekane M. , Iizuka H.
Published: July 2010

Screening tests for glucose‐isomerizing strains of various type, reference and laboratory strains of bacteria including actinomycetes, and yeasts were carried out. The ability to convert glucose to fructose was found to be widely distributed among various microorganisms. It was shown that glucose‐isomerizing ability was most prevalent in the genera Aerobacter and Escherichia, but was not found in the bacterial genera belonging to the order Pseudomonadales. Although their activities were not very high (probably due to unsuitable culture conditions) more than 70% of the actinomycetes and 60% of the yeasts grown on xylose possessed glucose‐isomerizing activity.
Zusammensetzung der Mikroorganismenpopulation im ungeschützten Fermentationsprozeß
Authors: Wünsche L. , Sattler K. , Gradova N. B. , Meinhold I. , Hedlich R. , Brendler W. , Uhlig H. , Rodionova G. S. , Saikina A. I.
Published: July 2010

An accompanying flora of the production strains always develops in each unprotected continuous fermentation process. In the process of production of fodder biomass from gas oil the high specific growth rate provides sufficient selection advantages to the production strain Lodderomyces elongisporus “D” EH 15 against substrate competitors. The accompanying flora uses products of metabolism and lysis as carbon and energy sources. The concentration of these compounds in the medium and consequently the development of the accompanying flora depends on the process conditions. During a period of more than ten years the taxonomic‐diagnostic and technological properties of the production strain Lodderomyces elongisporus “D” EH 15 did not change, caused by the permanent selection stress in the continuous fermentation process.
Microbiological implications of electric field effects III. Stimulation of yeast protoplast fusion by electric field pulses
Authors: Weber H. , Förster W. , Jacob H.‐E. , Berg H.
Published: July 2010

Prototrophic colonies could be selected on minimal medium after mixing of protoplasts from diauxotrophic mutants of the yeasts Saccharomycopsis lipolytica and/or Lodderomyces elongisporus and treatment with polyethylene glycol (PEG) in the presence of calcium chloride. This is the result of protoplast fusion and complementation of auxotrophic deficiencies. Under identical conditions an electric field pulse in the μs‐range applied via an electric discharge to the protoplast‐PEG mixture resulted in a drastic enhancement of the protoplast fusion rate. The presence of polyethylene glycol was demonstrated to be a prerequisite for fusion in this case, too. The frequency of hybrid formation detected as prototrophic colonies could be increased in the case of intraspecific fusion at initial electric field strengths between 2.5 and 5 kV · cm−1. The application of an electric field pulse of proper strength and duration to a yeast protoplast suspension turned out to be a more effective tool in production of fusion products than conventional methods. Large numbers of parasexual hybrids for different selection programmes in yeast genetics and for industrial purpose may be delivered by this technique.
Einsatz der automatischen Bildanalyse beim Screening von leistungsfähigen Selektanten Turimycin‐bildenderStreptomyces‐Stämme
Authors: Mühlig P. , Freysoldt Christiane , Bradler Gertraud , Kühne Ch.
Published: July 2010

The growth of the surface colonies on solid media is studied with the image analyzing system QUANTIMET 720 M controlled by a PDP 11 computer. For the bacterial strainStreptomyces hygroscopicusJA 6599 a new differential equation describing the kinetic behaviour of the area of the colony is suggested

It is shown that this time dependence of area describes more realistically the experiment than the function resulting from PIRT'S model. Two new constants arise from the growing curve, α describes the profile of density of the colony andk0is correlated to the growing constant of the colony. Both parameters can be correlated to the amount of antibiotics produced and, therefore, it is possible to use this information for the selection procedure of the colonies. A uniform criterion for selection was found for each colony of two mutants of the turimycin‐producing strainStreptomyces hygroscopicusJA 6599, which reads:The quality of the selection criterion of surface colonies with higher productivity is dependent on the mean value of the growing parameters of all colonies under investigation

Limitations of the selection method arise from the need for great uniformity of environmental conditions, growth medium and a homogeneous spore suspension, which have to consist of a large amount of single spores in order to assure a reproducible growing curve of the colonies. For the last condition a special technique is pointed out.
Enzyme induction in Streptomyces hydrogenans. Comparison of the effects of different steroids to increase the activity of 3α, 20β‐hydroxysteroid dehydrogenase and of 3β, 17β‐hydroxysteroid dehydrogenase
Authors: Bauer Brigitte , Träger L.
Published: July 2010

After cultivation of Streptomyces hydrogenans in the presence of different steroids the activity of both 3α,20β‐hydroxysteroid dehydrogenase and 3β, 17β‐hydroxysteroid dehydrogenase was determined in the cell homogenate of the microorganism. By comparing the efficacy of the steroids to increase enzyme activities, steroids could be divided into 3 groups: a) steroids which stimulated preferentially the activity of 3α,20β‐hydroxysteroid dehydrogenase (e. g., corticosterone), b) steroids which stimulated preferentially 3β,17β‐hydroxysteroid dehydrogenase (estradiol‐17β), and c) those behaving intermediately (e. g., progesterone, 5α‐dihydrotestosterone). Highest 3β, 17β‐hydroxysteroid dehydrogenase activity could be measured 2 h after addition of 5α‐dihydrotestosterone to the culture medium. The activity of 3α, 20β‐hydroxysteroid dehydrogenase, however, increased continuously up to 4 h. 3α,20β‐hydroxysteroid dehydrogenase and 3β,17β‐hydroxysteroid dehydrogenase syntheses seemed to be controlled by steroids in a non‐coordinate manner.
β‐1.3.‐1.4‐Glucanase in spore‐forming microorganisms. VI. Genetic instability of β‐glucanase production in a high‐producer strain of Bacillus amyloliquefaciens grown in a chemostat
Authors: Borriss R. , Noack D. , Geuther R.
Published: July 2010

A Bacillus amyloliquefaciens strain high‐producing for β‐1.3‐1.4‐glucanase has gradually lost the ability to produce this enzyme during long‐time continuous cultivation, independent of the culture conditions. Mutant strains isolated after long‐term cultivation exhibited changed behavior concerning extracellular enzyme formation and sporulation. By agarose gel electrophoresis of alkaline DNA extracts isolated from original and mutant strains we demonstrate that the observed pleiotropic phenomena are not caused by the loss of a complete plasmid present in the original strain. From extracts of both the original and mutant strains plasmid DNAs with approximately the same molecular weight of about 35 Mdal were isolated.
Effect of medium treatment on microbial degradation of sterols by Nocardia
Authors: Komel R.
Published: July 2010

The rate of transformation of cholesterol by Nocardia sp. is affected by the culture medium composition as well as by the way it has been treated before inoculation. When 1% of peptone was sterilized separately and afterwards added to the basic medium, the transformation of cholesterol to bisnorchola‐1,4‐dienic acid, as well as further aerobic degradation, was accelerated by a factor of 2. If this enriched medium was kept at rest overnight, the rate of transformation was lowered to half. Heating of additional peptone together with a basic medium resulted only in a slight diminution of the transformation of the preceding 4‐ene metabolite to the final 1,4‐diene when compared with a normal basic medium without any additive.
Growth characteristics and ultrastructure of protoplast type L‐forms from Streptomycetes
Authors: Gumpert J.
Published: July 2010

L‐form colonies from S. hygroscopicus, S. griseus and S. levoris were isolated after incubation of lysozyme protoplasts on an osmotically stabilized complex agar medium. Unstable and stable L‐forms grow on solid and in liquid media. L‐form colonies are 5–10 times smaller than normal colonies and show a typical morphology for each species. In ultrathin sections L‐form cells are characterized by nucleoid areas with typical core‐like structures, by a ribosome‐rich cytoplasm with different inclusion bodies, and by a cytoplasmic membrane. Because there are no cell wall structures L‐forms of the three Streptomyces species belong to the protoplast type.

Analysis of cell size and cell shape shows a variation in diameter and a cell propagation by regular and irregular division‐ and budding‐like processes. Many L‐form cells contain more than two chromosomes.

The results are discussed with regard to the cellular organisation of streptomycetes and the nature of the stable L‐form.
Antimicrobial activities of daunorubicin and adriamycin derivatives on bacterial and protoplast type L‐from cells of Bacillus subtilis 170, Escherichia coli B, and Proteus mirabilis VI. Structure — activity relationship
Authors: Gumpert J. , Dornberger K. , Smith T. H.
Published: July 2010

The antibacterial activity of ten N‐alkylated derivatives of daunorubicin and adriamycin as well as of 5‐iminodaunorubicin has been tested by using Bacillus subtilis 170, Escherichia coli B, and Proteus mirabilis VI and their stable protoplast type L‐forms in an agar diffusion test. Eight of the substances showed similar activities against B. subtilis and the L‐forms of all test organisms, but no activity against the bacterial forms of E. coli and P. mirabilis. The cell wall of these gram‐negative bacteria is responsible for this resistance by not allowing the antibiotics to enter the cells. The piperidino compound N‐(CH2)5 daunorubicin shows 2‐4 times higher activity against R. subtilis and all L‐forms in comparison to daunorubicin and the other derivatives. Five of the substances were inactive against all test strains. Their inactivity seems to be associated with the larger substituents at the C‐3′ position. Relations between molecular structure and activity are discussed considering data about the interaction with DNA and the antitumor activity. Stable protoplast type L‐forms and their bacterial forms represent a suitable and effective test system to screen for more effective substances and to get more information about their mode of action.
Enzymatische Untersuchungen zur Citrat‐Isocitrat‐Akkumulation bei Hefen mit Glucose als C‐Quelle
Authors: Franke‐Rinker D. , Behrens U. , Nöckel E.
Published: July 2010

The connection between the kinetics of citrate‐isocitrate overproduction bySaccharomycopsis lipolyticain glucose media and the specific activities of the enzymes being related to overproduction has been investigated. The specific activities of citrate synthase, aconitate hydratase, NAD+‐ linked and NADP+‐linked isocitrate dehydrogenase decline significantly after exhaustion of the nitrogen source, whereas the activity of the pyruvate carboxylase remains relatively constant and corresponds to changes of the production rate. The results are compared with those obtained by fermentations inn‐alkane media and discussed in relation to mechanisms of overproduction.
Nucleosidpolyphosphate: Vorkommen, Metabolismus und Funktion
Authors: Riedel K.
Published: July 2010

Procaryotes have regulatory systems allowing to vary the metabolism in response to nutritional variations, to reduce the growth, and to start development. Nucleoside polyphosphates are mediators of coordinated alterations of metabolism.

In this review, after a brief recall of the characteristics of the stringent response, the occurrence, determinations, and the metabolism of the nucleoside polyphosphates are presented. The representation of the pleiotropic effects includes the regulation of the protein synthesis and of the protein synthesis apparatus, of the protein turnover, of the N‐ and carbohydrate metabolism, of the formation of cell membranes and cell walls as well as the possible function of the development.
Effektorwirkung von sauerstoffhaltigen C1‐Verbindungen bei der Kultivierung des methanotrophen Bakterienstammes GB 25
Authors: Schneider J. D. , Wendlandt K.‐D. , Brühl E. , Mirschel G.
Published: July 2010

Addition of oxygen‐containing C1‐compounds to chemostat cultures of GB 25 increases both the yield of biomass and the specific growth rate. At optimum concentrations the catalytic activity of these compounds increases with increasing growth rates. Their influence on maintenance coefficients and maximum yield coefficients decreases in the order CH3OH > CO2 > HCOOH > HCHO. This result together with spectrophotometric NADH determinations suggests that the NADH pool determines the balance between the assimilatory and oxidative utilization of formaldehyde.
Sequential processes of phosphate limitation and of phosphate release in streptomycin fermentations
Authors: Müller P. J. , Christner A. , Ozegowski J. H.
Published: July 2010

The significance of the sequential processes of phosphate limitation and of phosphate release from medium constituents is demonstrated in technical streptomycin fermentations. The phosphate limitation initiated the streptomycin synthesis as well as the formation of phosphatases and protease. In later periods of the process the phosphate release influences especially the enzyme formation.
Influence of phosphate concentration on the respiratory activity of Azotobacter vinelandii
Authors: Haldenwang L. , Behrens U.
Published: July 2010

Azotobacter vinelandii was grown in batch cultures supplied with ammonia as an N‐source and phosphate at limiting concentration. After phosphate depletion the respiratory rate was affected in a characteristic way. The oxygen consumption during growth and the phase following growth was substantially higher than in cultures amply supplied with phosphate. It is suggested that phosphate limitation impairs the oxidative phosphorylation and stimulates the substrate phosphorylation which leads to a higher degree of respiratory NAD(P)H oxidation due to changes in the branched electron transport system.
Ultrastructural characterization of core structures and paracrystalline inclusion bodies in L‐form cells of streptomycetes
Authors: Gumpert J.
Published: July 2010

Protoplast type L‐form cells of Streptomyces hygroscopicus and S. griseus contain different types of inclusion bodies. Cytoplasmic cores and paracrystalline structures are peculiar inclusions which could not be observed in normal parent bacteria. The cytoplasmic cores are 1–4 μm long and 0.05–0.25 μm broad straight and stiff non‐tubular structures consisting of homogeneous moderate electron opaque material. Paracrystalline inclusions have side‐lengths between 0.2 and 0.5 μm and show a characteristic pattern of 15–20 nm thick straight dark lines and electron lucent intervening spaces of 20–30 nm. Both cytoplasmic cores and paracrystalline inclusions are apparently proteins. Their occurrence in L‐form cells indicates an altered synthesis of one or several proteins in these cell types.
Ciprofloxacin up‐regulates tendon cells to express matrix metalloproteinase‐2 with degradation of type I collagen
Authors: Tsai Wen‐Chung , Hsu Chih‐Chin , Chen Carl P.C. , Chang Hsiang‐Ning , Wong Alice M.K. , Lin Miao‐Sui , Pang Jong‐Hwei S.
Published: July 2010

Ciprofloxacin‐induced tendinopathy and tendon rupture have been previously described, principally affecting the Achilles tendon. This study was designed to investigate the effect of ciprofloxacin on expressions of matrix metalloproteinases (MMP)‐2 and ‐9, tissue inhibitors of metalloproteinase (TIMP)‐1 and ‐2 as well as type I collagen in tendon cells. Tendon cells intrinsic to rat Achilles tendon were treated with ciprofloxacin and then underwent MTT (tetrazolium) assay. Real‐time reverse‐transcription polymerase chain reaction (RT‐PCR) and Western blot analysis were used, respectively, to evaluate the gene and protein expressions of type I collagen, and MMP‐2. Gelatin zymography was used to evaluate the enzymatic activities of MMP‐2 and ‐9. Reverse zymography was used to evaluate TIMP‐1 and ‐2. Immunohistochemical staining for MMP‐2 in ciprofloxacin‐treated tendon explants was performed. Collagen degradation was evaluated by incubation of conditioned medium with collagen. The results revealed that ciprofloxacin up‐regulated the expression of MMP‐2 in tendon cells at the mRNA and protein levels. Immunohistochemistry also confirmed the increased expressions of MMP‐2 in ciprofloxacin‐treated tendon explants. The enzymatic activity of MMP‐2 was up‐regulated whereas that of MMP‐9, TIMP‐1 or TIMP‐2 was unchanged. The amount of secreted type I collagen in the conditioned medium decreased and type I collagen was degraded after ciprofloxacin treatment. In conclusion, ciprofloxacin up‐regulates the expressions of MMP‐2 in tendon cells and thus degraded type I collagen. These findings suggest a possible mechanism of ciprofloxacin‐associated tendinopathy. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:67–73, 2011
Short‐time clay‐mineral evolution in a soil chronosequence in Oléron Island (France)
Authors: Caner Laurent , Joussein Emmanuel , Salvador‐Blanes Sébastien , Hubert Fabien , Schlicht Jean‐Frédéric , Duigou Nelly
Published: July 2010

Major weathering sequences in soils are well established; however, knowledge on rates of mineral transformations remains unknown, because it is often difficult to date precisely soil processes. This work was carried out on soils developed on recent (< 188 y) sand dunes on the W coast of Oléron Island (France). The coast has been protected against marine and wind erosion by constructing five consecutives barriers close to the coastline since 1820 (1820, 1864, 1876, 1889, 1948) defining the maximum age of the soil parent material, as before the areas between the barriers were under water. Soils on the older dunes have low clay content (> 94% of sand) and exhibit a bleached E horizon that overlies a yellowish brown B horizon. The process responsible for their formation is podzolization promoted by the high permeability of the material and complexing organic matter produced by coniferous vegetation. Initial mineralogy of C horizons is homogenous and constituted of chlorite, illite, illite/smectite mixed‐layer minerals, and kaolinite, quartz, calcite (≈ 8% related to shell fragments), and feldspars. The initial clay‐mineral assemblage of the E horizons is dominated by illite (well‐crystallized WCI and poorly crystallized PCI) and chlorite. With progressive podzolization, poorly crystallized illite is first transformed to illite/smectite mixed‐layer minerals and in a further step into smectite. In addition, transformation of well‐crystallized illite leads to formation of ordered illite/smectite mixed‐layer minerals in the E horizons, which is not commonly described in soils. In the B horizons, illite/smectite mixed‐layer minerals are present with traces of smectite, as well as Al and Fe oxi‐hydroxides as revealed by DCB and oxalate chemical extractions. This chronosequence illustrates that over short distances and short time (< 188 y) intense mineral weathering and soil development occur. Major clay‐mineral changes occur between 132 and 188 y in agreement with development of the pine forest producing acidic litter.
Synthesis of New Polysialic Acid Derivatives
Authors: Su Yi , Kasper Cornelia , Kirschning Andreas , Dräger Gerald , Berski Silke
Published: July 2010

In this paper we report the first synthesis of novel polysialic acid derivatives which is initiated by treatment of polysialic acid with EDC‐HCl to yield the inter‐residual δ‐lactone. Subsequent reaction with amines or hydrazine gives the corresponding polysialic acid amides and hydrazide. Alkylation of the tetrabutylammonium salt of polysialic acid yields polysialic acid esters. In contrast a variety of N‐derivatives of polysialic acid can be prepared starting from deacetylated polysialic acid. The N‐derivatives prepared in this communication can be used for the Cu‐catalyzed as well as Cu‐free “click” chemistry.

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Formation of Poly(propylene)‐Based Biocomposite Films and Their Use in the Attachment of Methylene Blue
Authors: Cavallo Jesica A. , Gomez Cesar G. , Strumia Miriam C.
Published: July 2010

Biocomposite PP‐g‐PAAc‐CS films based on PP were generated and utilized as support of methylene blue, a thiazidic dye. Using a photograft polymerization of acrylic acid, the PP film was functionalized with carboxyl groups (PP‐g‐PAAc), which attached chitosan by electrostatic bond. A longer poly(acrylic acid) chain or a higher CS immobilization temperature led to a higher chain interpenetration and crosslinking reaction. Immobilized MB confirmed to possess redox activity from its reaction with ascorbic acid, where the dye decomposition rate ($R'_{\rm d} $) increases together with the chain interpenetration, then decreasing with the increase in the crosslinking degree.

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Polarizability of DNA Block Copolymer Nanoparticles Observed by Electrostatic Force Microscopy
Authors: Sowwan Mukhles , Faroun Maryam , Mentovich Elad , Ibrahim Imad , Haboush Shayma , Alemdaroglu Fikri Emrah , Kwak Minseok , Richter Shachar , Herrmann Andreas
Published: July 2010

In this study, DNA block copolymer (DBC) micelles with a polystyrene (PS) core and a single‐stranded (ss) DNA shell were doped with ferrocene (Fc) molecules. Tapping mode atomic force microscopy (AFM) was used to study the morphology of the doped and undoped block copolymer aggregates. We show that introducing Fc molecules into the hydrophobic core does not affect the structural properties such as shape or size. In contrast, doping with Fc significantly changes the micelles' electrical properties, namely their polarizability. Electrostatic force microscopy (EFM) measurements reveal that the undoped micelles show no significant polarization signal, while the Fc‐doped aggregates exhibit strongly enhanced polarizability. Furthermore, the nucleic acid moieties were utilized in combination with complementary ssDNA strands to assemble single particles into linear arrays of DBC nanoobjects. The ability to tune the electrostatic properties of the polymer core and the presence of nucleic acids might open the way for using these bioorganic nanoparticles as building blocks for nanoelectronic or biosensing devices.

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Multicomponent Phase Change Microfibers Prepared by Temperature Control Multifluidic Electrospinning
Authors: Wang Nü , Chen Hongyan , Lin Ling , Zhao Yong , Cao Xinyu , Song Yanlin , Jiang Lei
Published: July 2010

Multicomponent phase change microfibers, which can storage and release thermal energy in a stepwise manner, are firstly prepared through a facile one‐step multifluidic compound‐jet electrospinning with temperature control. The multiresponsive effect benefits from a special multichannel tubular microstructure that could controllably encapsulate different phase change materials into the channels independently. Aside from the fabrication of multicomponent phase change microfibers, the melt multifluidic compound‐jet electrospinning is promising for applications related to microencapsulation and multifunctional material fields.

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Effect of Finite Extensibility on the Equilibrium Chain Size
Authors: Miao Bing , Vilgis Thomas A. , Poggendorf Stefanie , Sadowski Gabriele
Published: July 2010

We investigate the finite‐extensibility effect on the equilibrium size of a single polymer chain by using a Flory‐type calculation. The finite extensibility of the chain is effectively taken into account by modifying the Gaussian stretching energy to a non‐Gaussian form which recovers the harmonic spring behavior in the limit of weak stretch and diverges when the chain extension approaches the total contour length. In general, the finite extensibility decreases the equilibrium size of the chain compared to that obtained from Flory's classic theory, due to a steeper free energy or effective potential of the chain generated by the finite‐extensibility effect. It is illustrated clearly that, for a chain with a short contour length and/or with strong repulsions between monomers, the finite‐extensibility correction is important and necessary to be taken into account. A typical system where the finite extensibility plays an important role is suggested to be the highly charged and highly crosslinked hydrogel.

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Measurement of alveolar oxygen partial pressure in the rat lung using Carr‐Purcell‐Meiboom‐Gill spin–spin relaxation times of hyperpolarized 3He and 129Xe at 74 mT
Authors: Kraayvanger Ryan J. , Bidinosti Christopher P. , Dominguez‐Viqueira William , Parra‐Robles Juan , Fox Matthew , Lam Wilfred W. , Santyr Giles E.
Published: July 2010

Regional measurement of alveolar oxygen partial pressure can be obtained from the relaxation rates of hyperpolarized noble gases, 3He and 129Xe, in the lungs. Recently, it has been demonstrated that measurements of alveolar oxygen partial pressure can be obtained using the spin–spin relaxation rate (R2) of 3He at low magnetic field strengths (<0.1 T) in vivo. R2 measurements can be achieved efficiently using the Carr‐Purcell‐Meiboom‐Gill pulse sequence. In this work, alveolar oxygen partial pressure measurements based on Carr‐Purcell‐Meiboom‐Gill R2 values of hyperpolarized 3He and 129Xe in vitro and in vivo in the rat lung at low magnetic field strength (74 mT) are presented. In vitro spin–spin relaxivity constants for 3He and 129Xe were determined to be (5.2 ± 0.6) ×10−6 Pa−1 sec−1 and (7.3 ± 0.4) ×10−6 Pa−1 s−1 compared with spin‐lattice relaxivity constants of (4.0 ± 0.4) ×10−6 Pa−1 s−1 and (4.3 ± 1.3) × 10−6 Pa−1 s−1, respectively. In vivo experimental measurements of alveolar oxygen partial pressure using 3He in whole rat lung show good agreement (r2 = 0.973) with predictions based on lung volumes and ventilation parameters. For 129Xe, multicomponent relaxation was observed with one component exhibiting an increase in R2 with decreasing alveolar oxygen partial pressure. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Time‐resolved bolus‐chase MR angiography with real‐time triggering of table motion
Authors: Johnson Casey P. , Haider Clifton R. , Borisch Eric A. , Glockner James F. , Riederer Stephen J.
Published: July 2010

Time‐resolved bolus‐chase contrast‐enhanced MR angiography with real‐time station switching is demonstrated. The Cartesian acquisition with projection reconstruction‐like sampling (CAPR) technique and high 2D sensitivity encoding (SENSE) (6× or 8×) and 2D homodyne (1.8×) accelerations were used to acquire 3D volumes with 1.0‐mm isotropic spatial resolution and frame times as low as 2.5 sec in two imaging stations covering the thighs and calves. A custom real‐time system was developed to reconstruct and display CAPR frames for visually guided triggering of table motion upon passage of contrast through the proximal station. The method was evaluated in seven volunteers. High‐spatial‐resolution arteriograms with minimal venous contamination were consistently acquired in both stations. Real‐time stepping table contrast‐enhanced MR angiography is a method for providing time‐resolved images with high spatial resolution over an extended field‐of‐view. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Computational modelling of shaped metal deposition
Authors: Anca Andrés , Fachinotti Víctor D. , Escobar‐Palafox Gustavo , Cardona Alberto
Published: July 2010

Shaped metal deposition (SMD) is a novel process for rapid prototyping that employs tungsten inert gas (TIG) welding controlled by a robot inside an inert gas chamber to build parts by successive layer deposition. This process can be enhanced through modelling and control. Industries are interested in developing systematized models to explain observed phenomena and to predict processing conditions for process planning and optimization. In this work, thermal and mechanical finite element (FE) modelling of SMD is presented. The thermal problem is solved with linear tetrahedral finite FEs that take into account the liquid/solid phase change phenomenon. The mechanical problem is solved with hexahedral elements with tri‐linear interpolation of displacements and constant interpolation of mean stresses (Q1– P0). Special techniques to account for material addition were developed, based on activation/deactivation of FEs. Numerical tests were conducted to determine the heat source model parameters. An experiment using Ti‐6Al‐4V material was developed to validate the formulation. The test consisted of a TIG‐wash procedure (arc passing without wire feeding to preheat the plate) followed by a single welding layer. The results, including temperatures and residual displacements, are compared with those obtained with the finite element method (FEM) code. Finally, a multilayer SMD numerical example is presented. Copyright © 2010 John Wiley & Sons, Ltd.
A Cartesian ghost‐cell multigrid Poisson solver for incompressible flows
Authors: Ma Z. H. , Qian L. , Causon D. M. , Gu H. B. , Mingham C. G.
Published: July 2010

In this paper, a simple Cartesian ghost‐cell multigrid Poisson solver is proposed for simulating incompressible fluid flows. The flow field is discretized efficiently on a rectangular mesh, in which solid bodies are immersed. A small number of ghost mesh cells and their symmetric image cells are distributed in the vicinity of the solid boundary. With the aid of the ghost and image cells, the Dirichlet and Neumann boundary conditions can be implemented effectively. Chorin's fractional‐step projection method is adopted for the coupling of velocity and pressure for the solution of the Navier–Stokes equations. Point‐wise Gauss–Seidel iteration is used to solve the pressure Poisson equation. To speed up the convergence of the solution to the corresponding linear system, sub‐level coarse meshes embedded with ghost and image cells are also introduced and operated in a sequential V‐cycle. Several test cases including the classical ideal incompressible flow around a cylinder, a lid‐driven cavity flow and viscous flow past a fixed/rotating cylinder are presented to demonstrate the accuracy and efficiency of the current approach. Copyright © 2010 John Wiley & Sons, Ltd.
Lucayan–Taíno burials from Preacher's cave, Eleuthera, Bahamas
Authors: Schaffer W. C. , Carr R. S. , Day J. S. , Pateman M. P.
Published: July 2010

In March 2007, three prehistoric skeletons were excavated and analysed from Preacher's Cave on the northern aspect of the island of Eleuthera in the Bahama archipelago. The human skeletal remains represent two males and one female dating toAD800–1300. The first is a female in the 30s with mild osteoarthritis of the joints and spine and several healed fractures who may have been an important community elder. The second is a male in the 20s with Schmorl's nodes who may have been a shaman or even a victim of interpersonal violence. The third is a male in the mid to late 20s also with marginal osteoarthritis of the joints and spine who may have been a ceremonial leader and village headman. The high incidence of carious lesions implies a cariogenic diet possibly rich in starchy foodstuffs or even fructose. The presence of grave goods and plaited mats suggest that at least two individuals may have been of high status. This study emphasises the significance of caves to Lucayan–Taíno mythology, cosmology and mortuary practice. Copyright © 2010 John Wiley & Sons, Ltd.