bluuebunny/crossref_metadata_2025_split huggingface dataset:
Insulin‐like growth factor‐I ameliorates demyelination induced by tumor necrosis factor‐α in transgenic mice
Authors: Ye Ping , Kollias George , D'Ercole A. Joseph 
Published: February 2007

AbstractOur groups have reported that tumor necrosis factor‐α (TNF‐α) causes myelin damage and apoptosis of oligodendrocytes and their precursors in vitro and in vivo. We also have reported that insulin‐like growth factor‐I (IGF‐I) can protect cultured oligodendrocytes and their precursors from TNF‐α‐induced damage. In this study, we investigated whether IGF‐I can protect oligodendrocytes and myelination from TNF‐α‐induced damage in vivo by cross‐breeding TNF‐α transgenic (Tg) mice with IGF‐I Tg mice that overexpress IGF‐I exclusively in brain. At 8 weeks of age, compared with those of wild‐type (WT) mice, the brain weights of TNF‐α Tg mice were decreased by ∼20%, and those of IGF‐I Tg mice were increased by ∼20%. The brain weights of mice that carry both TNF‐α and IGF‐I transgenes (TNF‐α/IGF‐I Tg mice) did not differ from those of WT mice. As judged by histochemical staining and immunostaining, myelin content in the cerebellum of TNF‐α/IGF‐I Tg mice was similar to that in WT mice and much more than that in TNF‐α Tg mice. Consistently, Western immunoblot analysis showed that myelin basic protein (MBP) abundance in the cerebellum of TNF‐α/IGF‐I Tg mice was double that in TNF‐α Tg mice. In comparison with WT mice, the number of oligodendrocytes was decreased by ∼36% in TNF‐α Tg mice, whereas it was increased in IGF‐I Tg mice by ∼40%. Oligodendrocyte number in TNF‐α/IGF‐I Tg mice was almost twice that in TNF‐α Tg mice. Furthermore, IGF‐I overexpression significantly reduced TNF‐α‐induced increases in apoptotic cell number, active caspase‐3 abundance, and degradaion of MBP. Our results indicate that IGF‐I is capable of protecting myelin and oligodendrocytes from TNF‐α‐induced damage in vivo. © 2007 Wiley‐Liss, Inc.
Oxidative damage in nucleic acids and Parkinson's disease
Authors: Nakabeppu Yusaku , Tsuchimoto Daisuke , Yamaguchi Hiroo , Sakumi Kunihiko 
Published: February 2007

AbstractOxidative DNA lesions, such as 8‐oxoguanine (8‐oxoG), accumulate in nuclear and mitochondrial genomes during aging, and such accumulation can increase dramatically in patients with Parkinson's disease (PD). To counteract oxidative damage to nucleic acids, human and rodents are equipped with three distinct enzymes. One of these, MTH1, hydrolyzes oxidized purine nucleoside triphosphates, such as 8‐oxo‐2′‐deoxyguanosine triphosphate and 2‐hydroxy‐2′‐deoxyadenosine triphosphate, to their monophosphate forms. The other two enzymes are 8‐oxoG DNA glycosylase encoded by the OGG1 gene and adenine/2‐hydroxyadenine DNA glycosylase encoded by the MUTYH gene. We have shown a significant increase in 8‐oxoG in mitochondrial DNA as well as an elevated expression of MTH1, OGG1, and MUTYH in nigrostriatal dopaminergic neurons of PD patients, suggesting that the buildup of these lesions may cause dopamine neuron loss. We established MTH1‐null mice and found that MTH1‐null fibroblasts were highly susceptible to cell death caused by H2O2 characterized by pyknosis and electron‐dense deposits in the mitochondria, and that this was accompanied by an ongoing accumulation of 8‐oxoG in nuclear and mitochondrial DNA. We also showed that MTH1‐null mice exhibited an increased accumulation of 8‐oxoG in striatal mitochondrial DNA, followed by more extreme neuronal dysfunction after 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine administration than that of wild‐type mice. In conclusion, oxidative damage in nucleic acids is likely to be a major risk factor for Parkinson's disease, indicating that a solid understanding of the defense mechanisms involved will enable us to develop new strategies for protecting the brain against oxidative stress. © 2007 Wiley‐Liss, Inc.
Degradation of phenolic compounds by the yeast Candida tropicalis HP 15 I. Physiology of growth and substrate utilization
Authors: Krug M. , Ziegler H. , Straube G. 
Published: February 2007

AbstractThe yeast Candida tropicalis HP 15 was able to utilize phenol up to concentrations of 2.5 g/l as a sole carbon and energy source. Phenol was metabolized via the β‐ketoadipate pathway by an inducible enzyme system.Besides phenol, resorcinol, quinol, hydroxyquinol, catechol, and to a lesser extend 4‐chloro‐catechol, protocatechuate, p‐cresol, m‐chlorophenol, and p‐chlorophenol were metabolized by the yeast. A total of 30 aromatic compounds were tested as substrates.
Eisenaufnahme durch Salmonella typhimurium‐Stämme unterschiedlicher epidemiologischer Herkunft
Authors: Rabsch W. , Reissbrodt R. 
Published: February 2007

AbstractAll Salmonella typhimurium strains tested were able to use iron from transferrin. In buffered nutrient broth — poor in iron‐content — the strains were tested in 59FeCl3 and 59Fe‐transferrin uptake in different growth phases. In the early log phase the strains are able to catch the 59Fe3+ in a very great amount as it is necessary for the growth. The content of 59Fe per cell was in the late log phase reduced until to a value, which seen to be enough for growth. The acquisition of 59Fe‐transferrin between the early and late log phase tested by 4 S. typhimurium strains was different.
Wachstumsuntersuchungen im substratlimitierten pH‐Auxostaten I. Bistabiles Wachstumsverhalten unter kaliumlimitierten Bedingungen
Authors: Büttner R. , Uebel B. , Genz I.‐L. , Köhler M. 
Published: February 2007

AbstractThe substrate‐limited pH‐auxostat as a new method of continuous culture is introduced. It is the feature of this method that two medium solutions are given to the culture. The first contains the limiting substrate only and flow to the culture with a constant rate. The second, which contains all other substrates, is given over the pH‐auxostat principle.A bistability in the growth of yeast under potassium‐limited conditions was found and discussed.
Maintenance of the recombinant plasmid pIJ2 in chemostat cultures of Streptomyces lividans 66 (pIJ2)
Authors: Roth M. , Noack D. , Geuther R. 
Published: February 2007

AbstractThe maintenance of the recombinant plasmid pIJ2 in chemostat cultures of Streptomyces lividans 66 (pIJ2) was investigated. The presence of the plasmid coding for a neomycin phosphotransferase was detected by plating samples from the continuous cultures on nonselective and selective agar medium containing neomycin.The plasmid was lost from the host strain under all conditions tested. However, the kinetics of the plasmid segregation from the chemostat populations were dependent on the growth‐limiting substrate of the medium, the dilution rate of the continuous culture and the cultivation temperature.Size differences between the original plasmid and plasmid DNA isolated from neomycin‐resistant clones after long‐term chemostat cultivation were not observed. In neomycin‐sensitive clones no extrachromosomal DNA was found.
Regulation of chorismate mutase, prephenate dehydrogenase and prephenate dehydratase of Candida maltosa
Authors: Bode R. , Melo C. , Birnbaum D. 
Published: February 2007

AbstractThe enzymes of the phenylalanine‐tyrosine pathway were partially purified from Candida maltosa and the regulatory patterns were established. Chorismate mutase (Mr 63,000), prephenate dehydrogenase (Mr 75,000) and prephenate dehydratase (Mr 88,000) were separated from each other. The formation of chorismate mutase was only regulated by a general control of amino acid biosynthesis, whereas the synthesis of prephenate dehydrogenase and prephenate dehydratase was constitutive. Both chorismate mutase and prephenate dehydrogenase were activated by tryptophan and by methylated or fluorinated tryptophan analogues. l‐tyrosine as well as α‐methyl‐dl‐tyrosine inhibited the activity of both enzymes. Prephenate dehydratase activity was stimulated by l‐tryptophan and by methylated tryptophan derivatives and inhibited by d‐tryptophan or 5‐fluorotryptophan. In contrast to chorismate mutase, the double‐reciprocal curves of substrate saturation of which were hyperbolical (positive cooperativity), prephenate dehydrogenase and prephenate dehydratase showed linear curves of substrate saturation, indicating normal Mi‐chaelis kinetics.
Bacterial resistance to streptothricins
Authors: Haupt I. , Thrum H. 
Published: February 2007

AbstractResistance to streptothricin was studied in bacteria with different resistance mechanisms. The laboratory‐induced streptothricin‐resistant mutant E. coli A19 Stcr 2/2/1 showed a high level of cross‐resistance to aminoglycosides and other miscoding inducing antibiotics. In contrast, amino‐glycosid‐resistant E. coli strains with plasmid‐determined aminoglycoside modifying enzymes were sensitive to streptothricin. Enzymatic inactivation of streptothricin by acetylation was demonstrated for the streptothricin producing Streptomyces noursei, strain NG13. This strain showed no cross‐resistance to miscoding inducing aminoglycosides.
Synthese der alkalischen Phosphatase in einem stringent und relaxed kontrollierten Stamm von Escherichia coli nach Aminosäuren‐ und Phosphatlimitation
Authors: Hecker M. , Schroeter A. 
Published: February 2007

AbstractSynthesis of alkaline phosphatase in Escherichia coli is derepressed under phosphate starvation in the stringent strain CP78 as well as in its relaxed counterpart CP79. During limitation of phosphate as well as of amino acids a decrease of enzyme activity is observed, especially in the relaxed strain, which can not produce ppGpp under this conditions.After phosphate limitation synthesis of ppGpp is not stimulated and the kinetics of RNA synthesis is similar in both strains.We suggest that ppGpp is not directly involved in the regulation of gene expression during phosphate starvation.
Immobilisierung partikelgebundener Aldehyddehydrogenase aus Acinetobacter calcoaceticus EB 104
Authors: Klossek P. , Kirchner M. , Kurth J. 
Published: February 2007

AbstractParticle‐bound aldehyde dehydrogenase from Acinetobacter calcoaceticus was attached to octylsepharose by hydrophobic membrane proteins without previous solubilization. To optimize this method, the influence of the pH‐value of immobilization, ammonium sulfate concentration, presence of tensides, and some other substances on relative activity and yield was investigated. Best results were obtained when immobilization was carried out for 1–2 h at 4°C in 2moles/l KCl, pH 7.5. The optimum pH for storage was 9.0 and the maximum half‐life 40 days at 4°C or 18 days at 25°C.
Conjugation of tomatine with l(+)‐lactic acid by Nocardia restricta
Authors: Komel R. , Karlovšek M. 
Published: February 2007

AbstractNocardia restricta conjugates tomatines with l(+)‐lactic acid, which represents a new mode of bioconversion of steroid glycosides. The specifity in cell‐free homogenate was not restricted to α‐tomatine, since δ‐tomatine was transformed to the conjugated metabolite as well. It was shown with inhibitors of protein synthesis that the enzymes responsible for this reaction are constitutive. By using protoplasts and centrifugation it was found that the conjugating activity and the reaction products were bound to the membrane part of the 10,000 × g sediment of the cell‐free homogenate. Possible mechanisms as well as the biological significance of this reaction are discussed.
Wechselwirkungen zwischen Lektinen und Mikroorganismen I. Bestimmung der Agglutinationsgeschwindigkeit durch Extinktionsmessungen: Agglutination von Hefezellen (Saccharomyces cerevisiae H155) durch Concanavalin A
Authors: Flemming Ch. , Gabert A. , Flemming Ingeborg 
Published: February 2007

AbstractA simple photometric method for the determination of the agglutination rate of cells by lectins in a continuously stirred suspension is presented. Besides the agglutination rate the method allows the estimation of an average degree of agglutination, i.e. the number of cells per aggregate. The influence of the Con A‐concentration, cell number, temperature, and pH on the agglutination rate of Saccharomyces cerevisiae H155 have been studied.The results are of good reproducibility and, therefore, the methods is suitable to describe interactions between cell‐bound receptors and receptor‐specific proteins, e.g. lectins and antibodies.
Regulation of lipid biosynthesis in Chlorella kessleri by clomiphene
Authors: Řezanka T. , Lívanský K. , Podojil M. 
Published: February 2007

AbstractDuring autotrophic cultivation of the alga Chlorella kessleri clomiphene1) regulated both the quantitative and qualitative production of lipids (sterols, hydrocarbons and fatty acids). Their content decreased to 57% as compared with the production of sterols in cultures without clomiphene. The production of hydrocarbons and fatty acids was similar to that on the control.Among the sterols the variety of which enhanced the presence of clomiphene, those prevailed which carried either a double bond in position 8 or were devoid of it in position 22. In the mixture of hydrocarbons a significant increase was observed towards n‐heptadecane production. Oleic acid predominated among fatty acids.
Detection of two ornithine carbamoyltransferases in a phaseolotoxin‐producing strain of Pseudomonas syringae pv. phaseolicola
Authors: Jahn O. , Sauerstein J. , Reuter G. 
Published: February 2007

AbstractThe phaseolotoxin‐producing Pseudomonas syringae pv. phaseolicola strain 1321 contains two ornithine carbamoyltransferases which differ in resistance to phaseolotoxin. Whereas ornithine carbamoyltransferase 1 (OCT 1) is inhibited at low concentrations of phaseolotoxin, ornithine carbamoyltransferase 2 (OCT 2) is insensitive to phaseolotoxin. The activity of the insensitive enzyme is correlated with the amount of toxin formed.
The temperature profiles of growth, thermal death and ethanol tolerance of the xylose‐fermenting yeast Candida shehatae
Authors: Lucas Candida , Van Uden N. 
Published: February 2007

AbstractThe temperature profile of growth and thermal death of the xylose‐fermenting yeast Candida shehatae was dissociative. The Arrhenius plot of growth lacked a descending supraoptimal branch and the specific growth rate at the maximum temperature for growth (around 31°C) was not significantly different from its values at the other temperatures studied (down to 20°C). Ethanol enhanced thermal death by increasing its entropy of activation (entropy coefficient 16.1 entropy units mol−1)−1). The temperature profile of ethanol tolerance with respect to growth displayed a temperature plateau (10–17.5°C) of maximum ethanol tolerance (limit 6% v/v of ethanol) while the toxic effects of ethanol increased on either side of the plateau depressing the maximum temperature for growth from 31 to 17.5°C and increasing the minimum temperature for growth from 2.5 to 10°C.
pH‐linked control of energy charge in Acetobacter methanolicus sp. MB 70
Authors: Loffhagen N. , Babel W. 
Published: February 2007

AbstractThe influence of the extracellular pH on the adenylate system of the acidophilic Acetobacter methanolicus sp. MB 70 was investigated.The ATP level was maintained over a pH range from 3.0 to 6.0. An increased endogenous respiration was observed after a raise of the pH from 4.0 upwards.Above pH 6.0 the level of ATP decreased and the level of ADP and even more that of AMP increased. This resulted in a drop of the energy charge from 0.78 to values below 0.2. At pH 4.0 the level of ATP and AMP decreased only after prolonged incubation without an external energy source but the energy charge remained constant at about 0.7. In the range of external pH values where the energy charge is maintained the intracellular pH value is expected to be stable. The investigation of the reasons for the displacement of this range to low extracellular pH values may help to more profoundly understand the phenomenon of acidophily.
Katabole Repression bei aerobem und O2‐limitiertem Wachstum — energetische und stoffliche Bilanz des Kohlenhydratmetabolismus bei Hefen
Authors: Röber B. 
Published: February 2007

AbstractRadiorespirometry during aerobic and O2‐limited growth with Candida maltosa H and mutants oxidizing glucose specifically labelled with 14C in carbon atoms 1–4, 6 or universally labelled demonstrated the simultaneous operation of the pentosephosphate pathway, tricarboxylic cycle and pyruvate decarboxylation (Röber and Reuter 1984a). Therefore, material and energy balances are developed for product formation and biomass production by Candida maltosa H and mutant strains using 14C‐glucose, 14C‐fructose, 14C‐mannose as sole source of carbon and energy or glucose/mannose as a mixed substrate.Measured values of 14C‐incorporation into 14CO2, 14C‐biomass and 14C‐product are used to obtain estimates of biomass energetic yield, of the fraction of substrate energy evolved as heat, of Y0, of the P/O‐quotient and of the ATP synthesis. Aerobic growth on glucose resulted in repression of the tricarboxylic cycle (strain H, mutant H3). An increased efficiency of the utilization of the substrate energy was found during O2‐limited growth of the mutant strains based on the increased hexose catabolism via tricarboxylic cycle and increased P/O quotients. Mutant strains showed no or less product formation with fructose or mannose as the sole source of carbon and energy under aerobic growth conditions.
Lysine biosynthesis in the yeast Candida maltosa: properties of some enzymes and regulation of the biosynthetic pathway
Authors: Schmidt H. , Bode R. , Lindner M. , Birnbaum D. 
Published: February 2007

AbstractFour enzymes of the lysine biosynthetic pathway of Candida maltosa were investigated and the regulatory pattern was established. α‐Aminodipate reductase (Mr 160,000), saccharopine reductase (Mr 90,000) and saccharopine dehydrogenase (Mr 45,000) were separated from each other. Homocitrate synthase was sensitive to the separation methods used. The formation of saccharopine reductase was constitutive, whereas the synthesis of homocitrate synthase, α‐aminoadipate reductase and saccharopine dehydrogenase were regulated by the general control of amino acid biosynthesis. l‐Lysine (Ki = 5.0 mm), l‐thialysine (Ki = 15 mm) and dl‐α‐aminoadipate (Ki = 5.1 mm) inhibited homocitrate synthase, the first enzyme of the pathway. The inhibition was competitive with respect to 2‐oxoglutarate. The Km‐values of the enzyme were estimated to be 0.033 mm for acetyl‐CoA and 0.025 mm for 2‐oxoglutarate. The Michaelis constants of the α‐aminoadipate reductase were calculated to be 0.20 mm for α‐aminoadipate, 0.50 mm for ATP, 0.10 mm for NADPH and 3.8 mm for MgCl2. The Km‐values of the saccharopine reductase were 0.55 mm for saccharopine and 0.13 mm for NADP+, respectively. The values of the saccharopine dehydrogenase were estimated to be 1.6 mm for l‐lysine, 0.66 mm for 2‐oxoglutarate and 0.23 mm for NADH. Furthermore, a number of amino acids were found to be effectors of the enzyme reactions.
Enrichment of mutants of Rhodosporidium toruloides by the use of inositol starvation
Authors: Tully M. 
Published: February 2007

AbstractInositol‐requiring mutants of strains of Rhodosporidium toruloides were isolated and the frequency of isolation of auxotrophic and catabolic mutants from them was measured after starvation for inositol. Mutants can be isolated at frequencies up to 31 times greater than those of mutagenized cultures without enrichment.
Rapid isolation of bacterial proteinases by column chromatography on sawdust
Authors: Šafařík I. 
Published: February 2007

AbstractProteolytic enzymes produced by some strains of Bacillus sp. were isolated by column chromatography on sawdust. Ballast proteins were eluted with water while the adsorbed proteinases were eluted with 1 m sodium chloride solution. The specific activities of proteinases increased 54‐ to 70‐fold after chromatography.
Effects of mercuric chloride on akinete germination and sporulation in Pithophora oedogonia (Mont.) Wittrock (Cladophorales, Chlorophyceae)
Authors: Chaudhary B. R. , Singh H. V. 
Published: February 2007

AbstractThe effect of mercuric chloride on akinete germination and sporulation with respect to time lapse and extent was studied in Pithophora oedogonia (Mont.) Wittrock (Cladophorales, Chlorophyceae). At HgCl2 concentrations from 1.25 to 45 mg/l akinetes showed progressive delay in the initiation and reduction in the extent of germination. HgCl2 concentrations of 60 mg/l and above proved to be completely lethal to the spores as they failed to germinate. The time necessary for the initiation of akinete formation and the percentage sporulation also decreased with an increase in the concentration of HgCl2 from 1.25 to 45 mg/l where spore germination was encountered. Inactivation of enzymes and metabolic inhibition seemed to be the cause of spore lethality.
Transductional analysis of the cysII region of Pseudomonas aeruginosa
Authors: Schelenz H.‐J. , Günther E. , Herrmann H. , Schatte L. 
Published: February 2007

AbstractThe close linkage between hisI and mutations of the cysII group in Pseudomonas aeruginosa was confirmed by mapping experiments with new mutants. All mutants of the cysII group were blocked in the cysteine biosynthesis before sulfite (this include the mutant cys‐5605 which had previously been mapped by Mee and Lee, 1969). Most of the sulfite requiring cys mutants belonged to this group.The farthest distance between two mutations of the cysII group was calculated by the Wu formula to be approximately 2.5 kbp. We, therefore, suggest that more than one gene of the cysteine pathway may be located within this region.
Isolation and properties of mutants of Streptomyces noursei resistant to benzyl alcohol
Authors: Gräfe U. , Reinhardt G. , Friedrich W. , Bormann E. J. 
Published: February 2007

AbstractStable mutants resitant to benzyl alcohol (= Balr) were selected from natural colony populations of several strains of S. noursei JA 3890 b. Irrespective of the absence of aerial mycelium formation the majority of the Balr mutants produced the same amount of nourseothricin as their parental strains. The Balr derivative 2/8 showed a higher production of biomass and lipids than its ancestor BF32 under standard conditions of growth. In the presence of increasing concentrations of benzyl alcohol in the medium (0–0.2%), growth of this Balr strain was more resistant to the toxic agent, and the lipid content dropped more slowly concomitant with aberrant alterations of the composition of fatty acids. The results suggest that Balr strains represent regulatory mutants whose occurrence in natural populations has been caused either by changes at the level of pleiotropic gene functions or by several, independent genetic alterations.
Temporal relationship of diploidization and haploidization in the yeast Yarrowia lipolytica
Authors: Kurischko Cornelia , Weber H. 
Published: February 2007

AbstractBy means of special selective conditions we analyzed the temporal relationship of diploidization and haploidization in the yeast Yarrowia lipolytica. These processes could be divided into several steps. Twelve hours after mixing parental strains dissociation products of unstable heterokaryons are selectable. Four hours later karyogamy takes place as shown by isolation of mitotic recombinants. At this time spontaneous haploidization starts which leads to an enrichment of haploid and aneuploid segregants in the cell population. A high portion of chimeric clones which represents the dynamics of segregation were selected at time intervals 16, 23 and 29 hours.We concluded that an unstable heterokaryon should be a connecting link between sexual and parasexual processes in Y. lipolytica.
Butylmaduramycin, a new antibiotic from Actinomadura rubra
Authors: Strauss D. G. , Baum M. , Fleck W. F. 
Published: February 2007

AbstractButylmaduramycin, a new derivative of maduramycin was isolated from the culture medium of a mutant strain of Actinomadura rubra. This communication describes some biological and physicochemical characteristics of the new antibiotic.