bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proteins tightly bound to DNA and DNA‐synthesizing activity of nucleoids from Escherichia coli
Authors: Gaziev A. I. , Fomenko Ludmila A. , Zakrzhevskaya Dina T. , Petrov S. I. 
Published: February 2007

AbstractMembrane‐attached nucleoids were isolated from E. coli and separated from proteins by 2 m NaCl. Desintegration of such nucleoids by ultrasound and subsequent centrifugation resulted in the formation of two fractions: a sediment (fraction I) and a supernatant (fraction II). The protein:DNA ratio of fraction I was equal to 27 and was different from that to fraction II (2.6). More than 70% of the proteins not dissociating at 2 m NaCl and bound to DNA of both fractions were polypeptides with molecular weights (Mw) of 31,000–23,000 daltons (31–23 Kdal).After pulse labelling of the cells with [3H]‐thymidine, the specific radioactivity of newly synthesized DNA associated with fraction I was shown to be considerably higher than that of fraction II. The analysis of DNA‐synthesizing activities in fractions I and II showed that both nucleoid fractions contained DNA polymerase I.After dissolving the two fractions in 8 m urea – 0.15% sodium dodecylsulphate (SDS) they were chromatographed on hydroxyapatite. DNA‐protein complexes were obtained that did not dissociate at 4 m guanidine. HCI – 5 m urea and 1% SDS. The main protein of the complexes was a 31 Kdal polypeptide tightly bound to DNA.
The production of 3aα‐H‐4α‐(3′‐propionic acid)‐5α‐hydroxy‐7aβ‐methylhexahydro‐1‐indanone‐δ‐lactone by Nocardia restricta mutants
Authors: Miclo A. , Germain P. , Lefebvre G. 
Published: February 2007

AbstractTwo mutants of Nocardia restricta breakdown androst‐4‐ene‐3,17‐dione into 3aα‐H‐4α‐(3′‐propionic acid)‐5α‐hydroxy‐7aβ‐methylhexahydro‐l‐indanone‐δ‐lactone. The metabolic intermediates formed are very different in each mutant. One uses certain aromatic compounds very slowly. A degradation pathway for steroids by Nocardia restricta has been proposed.
The purification and activities of an alkaline protease of Aspergillus clavatus from Nigerian poultry feeds
Authors: Ogundero V. W. , Osunlaja S. O. 
Published: February 2007

AbstractOptimal growth and extracellular protease production by Aspergillus clavatus Des. was recorded at 30 °C and between days 5 and 7 of the 8‐day incubation period. Purification of this enzyme was achieved by a combination of ultrafiltration, alcoholic precipitation and fractionation on DEAEcellulose and Sephadex‐G.200. A single peak of an alkaline protease was subsequently obtained with a 9‐fold increase in specific activity and a final recovery value of 26.2%.The enzyme had optimal activity at 37 °C and a pH of 7.8. The enzyme did not degrade leucine amide, hippurylphenylalanine and hippurylarginine indicating lack of exo‐protease activity. However, endo‐protease activity led to a rapid hydrolysis of gelatin with optimal activity at 40 °C and pH 7.8. The high incidence of A. Clavatus on Nigerian poultry feeds vis‐a‐vis the potential health risks posed to farm animals is discussed.
Degradation of phenolic compounds by the yeast Candida tropicalis HP 15. II. Some properties of the first two enzymes of the degradation pathway
Authors: Krug M. , Straube G. 
Published: February 2007

AbstractThe first two enzymes of the phenol degradation pathway were determined and characterized in crude extracts from Candida tropicalis HP 15. The phenol hydroxylase (EC 1.14.13.7) was a stable NADPH2‐ and FAD‐dependent enzyme with a pH‐optimum of 7.6 to 8.0 and a broad substrate specificity. Influence of ultrasound rapidly reduced the enzyme activity.The catechol 1,2‐oxygenase (EC 1.13.1.1) had a broad pH‐optimum between 7.5 and 9.6 and a limited substrate specificity. Two active protein bands indicating the presence of two isofunctional enzymes were detectable after electrophoretic separation of crude and partially purified extracts on polycrylamide gels and specific staining for catechol 1,2‐oxygenase activity.
Purification and properties of an acylamide amidohydrolase (E. C. 3.5.1.4) with a wide activity spectrum from Brevibacterium sp. R 312
Authors: Thiery A. , Maestracci M. , Arnaud A. , Galzy P. , Nicolas M. 
Published: February 2007

AbstractAn amidase with a wide activity spectrum was purified from the Brevibacterium sp. R 312 and studied. The purification was performed by precipitating the proteins of the supernatant fraction obtained after centrifugation of sonicated cells. The resulting proteins were submitted to a gel filtration step followed by DEAE‐Sephadex ion exchange chromatography and then by another gel filtration process. The purified amidase had a molecular weight of 180,000 and was composed of four subunits of the same molecular weight (43,000 + 2,000). Its isoelectric point was 3.5. This enzyme was able to hydrolyze a large number of amides into their corresponding organic acids and it also possessed an acyl transferase activity.
Self‐resistance of the nourseothricin‐producing strain Streptomyces noursei
Authors: Haupt I. , Thrum H. , Noack D. 
Published: February 2007

AbstractThe nourseothricin producer Streptomyces noursei is resistant to its own antibiotic in submerged as well as in surface culture. The strain shows no cross‐resistance to miscoding inducing aminoglycoside antibiotics. Cell free extracts of Streptomyces noursei inactivate nourseothricin by enzymatic acetylation. The pattern of cross‐resistance of Streptomyces noursei correlates well with the substrate specificity of the nourseothricin acetyltransferase. Furthermore, the acetyltransferase activity parallels the resistance level in nourseothricin‐producing strains and nonproducing mutants. The results suggest that the nourseothricin acetyltransferase is important in the self‐defence strategy of the nourseothricin‐producing strain.
Physiological studies on pBR 322 DNA amplification in an Escherichia coli relA strain
Authors: Hecker M. , Schroeter A. , Mach F. 
Published: February 2007

AbstractAmino acid limitation leads in E. coli relA cells which cannot synthesize guanosine tetraphosphate (ppGpp) under these conditions to an amplification of pBR 322 DNA. We previously proposed that ppGpp produced in E. coli relA+ cells subjected to amino acid limitation inhibits pBR 322 DNA replication (Hecker et al. 1983).In further experiments it was established that an E. coli relA strain shows plasmid amplification during amino acid limitation (arginine, threonine, leucine or histidine) only in the presence of sufficient concentrations of phosphate, ammonia and glucose. Plasmid amplification does not occur if ammonia or phosphate is depleted. We suggest that glucose, ammonia and phosphate are needed for nucleotide and deoxynucleotide synthesis as the essential prerequisite for plasmid amplification.The activity of β‐lactamase was determined as an indicator for the expression of plasmid‐encoded genes. The enzyme activity remains on a low level during plasmid amplification because of arginine exhaustion. A remarkable increase in the activity of β‐lactamase was observed after resumption of growth of relA cells containing amplified plasmid DNA. The plasmid content decreased as the cells continued to grow. We found that plasmid amplification and expression of plasmid‐localized genes are opposite reactions which do not occur at the same time.
Bioconversion of steroids by Cochliobolus lunatus. I. Transformation of Reichstein's compound S with cell‐free preparations of Cochliobolus lunatus
Authors: Hörhold Cläre , Undisz Katrin , Groh H. , Sahm Renate , Schade W. , Komel R. 
Published: February 2007

AbstractSteroid 11β‐hydroxylase activity and 20β‐hydroxy‐steroid dehydrogenase activity were found in the cell‐free crude extract of Cochliobolus lunatus. It was possible to separate these two enzymatic activities by centrifugation at 100,000 X g. The 20β‐hydroxy‐steroid dehydrogenase activity remained in the supernatant while the 11β‐hydroxylase activity was present in the sediment. 11β‐hydroxylation was clearly inhibited by CO.
Screening among nocardioform bacteria for strains able to degrade aniline and monochloroanilines
Authors: Janke D. , Schukat B. , Prauser H. 
Published: February 2007

AbstractA total of 106 strains of nocardioform bacteria were chosen from the IMET Culture Collection and checked for their ability to degrade aniline. Among them only four Rhodococcus strains proved to be capable of removing aniline from a liquid mineral salts medium devoid of any other carbon and nitrogen source. This capability was found to be due to total degradation of the aromatic substrate via the β‐ketoadipate pathway which is initiated by the action of inducible oxygenating enzymes. Without any exception, the ring‐cleaving enzymes induced during cell precultivation with aniline were pyrocatechases of the “ordinary” type.None of the four aniline‐assimilating Rhodococcus strains could utilize any of the monochloroaniline isomers as the sole carbon and energy source for growth. However, resting aniline‐grown cells of these strains mediated the turnover of 2‐ and 3‐chloroaniline in the presence of chloramphenicol. The respective rates were substantially higher (31 to 59% as compared with the unsubstituted aniline) when glucose was provided as the additional carbon substrate. In contrast, 4‐chloroaniline turnover occurred with low rates (3–6%), even in the presence of glucose. With all of the four Rhodococcus strains under study, 3‐chloroaniline turnover resulted in chloride levels which corresponded to an almost stoichiometric dechlorination of the substrate. 2‐Chloroaniline, however was only partially dechlorinated even in the presence of glucose indicating that certain chlorinated metabolite(s) was (were) accumulated in the respective incubation media.
Growth and autolysis of the ascomycete Hypomyces ochraceus. Metabolism of U‐14C‐l‐leucine, 2‐14C‐dl‐threonine and U‐14C‐l‐aspartic acid
Authors: Röber B. , Riemay K. H. , Hilpert A. 
Published: February 2007

AbstractThe autolytic process observed in fungi has been divided into three different phases A 1, A 2, A 3. Each of which is characterized by specific metabolic evants. Recently, we characterized these phases by means of 14C‐d‐glucose. In this communication we report on the uptake and conversion of 14C‐labelled amino acids. These amino acids were rapidly taken up by the fungal mycelium and incorporated into cellular pools. During autolysis phase A 1 these amino acids were still used for protein synthesis. The autolytic process resembled a turnover process during this first phase. At this time the mycelium still exhibited high metabolic activity. The second phase, A 2 was characterized by a rapid intracellular degradation of compartmental material and accompanied by oxidation of the products formed. This was reflected by an increasing 14CO2 production. During phase A 3 products of intracellular degradation and possibly compounds from autolysing hyphae were still taken up by intact, i. e. living compartments of the hyphae and converted to heat and CO2.Almost no radioactive material was released into the medium during the last two phases. Metabolically active compartments or parts of the hyphae were present during the whole process of autolysis of fungal batch culture, .i e. even at the end of phase A 3.
Mercury methylation by bacteria
Authors: Trevors J. T. 
Published: February 2007

AbstractBacteria capable of methylating Hg2+ have been isolated from sediment, water, soil and the gastrointestinal tract of humans. However, very little is known about the physiology and genetics of the mechanisms controlling Hg2+ methylation. Mercury methylation can be either chromosomal or plasmid‐encoded in bacteria. In addition, the extent of nonbiological methylation is not well understood in environmental samples, where there are numerous physical, chemical and biological factors that control the methylation process.It is known that methylation of Hg2+ is mediated by a series of enzymatic reactions that are also responsible for the anaerobic evolution of methane. However, under highly reduced environments the reaction can also occur nonbiologically. It is possible that certain bacteria use methylation as a resistance/detoxification mechanism.
Chemoautotrophic growth of Thiocystis violacea, Chromatium gracile and C. vinosum in the dark at various O2‐concentrations
Authors: Kämpf Charlotte , Pfennig N. 
Published: February 2007

AbstractThe influence of various O2‐concentrations on chemoautotrophic growth was determined in the range from microaerobic to aerobic conditions. Chromatium vinosum D, Thiocystis violacea 2311 and Chromatium gracile 25‐1 were grown chemoautotrophically using consecutively repeated batch cultures. Rapid growth of all three strains occurred only under microaerobic conditions. The fastest growth (μ = 0.058) was obtained with Chromatium gracile 25‐1 grown in the presence of 1 mg O2 · 1−1. For optimal chemoautotrophic growth sulfur‐containing cells had to be supplied continuously with extracellular electron donor. Multiplication of thiocystis violacea 2311 and Chromatium gracile 25‐1 was significantly inhibited after several cell generations, while Chromatium vinosum D could be grown unlimited. In case of the latter bacterium any given O2‐concentration determined a unique growth rate and a unique specific bchl α content. The analysis of absorption spectra of whole cells revealed that different pigment complexes were regulated separately by oxygen. Growth yields were not dependent on the O2‐concentration. A growth yield of 12 g dry cell mass per mol of thiosulfate oxidized was determined for Chromatium vinosum D growing in the micro‐ to semiaerobic O2‐concentration range. When compared to phototrophically grown cells, the catalase content of chemotrophically grown cells was 2 times lower while the maximal specific respiration rate of the cells was 7 times higher. The ecological significance of the kinetics of chemotrophic growth under various growth conditions is discussed.
Developmental studies of Claviceps paspali seed cultures for the submerged production of lysergic acid derivatives
Authors: Sočič H. , Gaberc‐Porekar V. , Pertot E. , Puc A. , Miličić S. 
Published: February 2007

AbstractMetabolic pattern of mycelial Claviceps paspali seed cultures during the submerged cultivation was established. By comparing it with conidial and mycelial Claviceps purpurea strains it was found that the biosynthesis of RNA, DNA, and proteins followed a similar course in all Claviceps strains, so the fall of RNA content in mycelium may be considered a general biochemical indicator for optimally developed inoculum. But, two different patterns of carbohydrate and lipid metabolism were observed one for condial and one for mycelial strains.
Effect of oxygen Iimitation on the content of n‐hexadecane‐inducible cytochrome P‐450 in Acinetobacter calcoaceticus strain EB 104
Authors: Sharychev A. A. , Matyashova R. N. , Losinov A. B. , Asperger O. , Kleber H.‐P. 
Published: February 2007

AbstractThe content of cytochrome P‐450 as a function of oxygen supply was studied during growth of Acinetobacter on n‐hexadecane in batch cultures at constant pH. and agitation. The rate of growth and the content of cytochrome P‐450 were not affected as long as the dissolved oxygen tension ranged above 3 to 5% of saturation. The amount of cytochrome P‐450 increased when the oxygen tension declined to zero. Cytochrome P‐450 levels of about 0.3 to 0.4 nmol/mg protein, i.e. a more than a threefold increase, were observed under conditions where oxygen supply was strictly limited and allowed to maintain only a minimum of metabolism or growth. Limited oxygen supply exerted a special effect on the induction of the cytochrome P‐450 as concluded from an increasing ratio between cytochrome P‐450 and cytochrome o, and from the absence of cytochrome d in cells with elevated content of cytochrome P‐450. The increased formation of cytochrome P‐450 was a reversible process.
Introduction of oxygen function into isoprenoid systems by means of Botrytis cinerea (Persoon)
Authors: Dmochowska‐Gladysz J. , Kolek T. , Siewiński A. , Derdziński K. , Zabża A. , Nespiak A. 
Published: February 2007

AbstractThe introduction of oxygen functions into (±)‐1‐(2′,2′,3′‐trimethyl‐3′ ‐cyclopenten‐1′ ‐yl)‐propan‐2‐one [(±)‐1a], (±)‐1‐(2′,2′,3′,‐trimethyl‐3′‐cyclopenten‐1′ ‐yl)‐butan‐2‐one [(±)‐1b], and (±)‐1‐ (2′, 3′, 3′‐trimethyl‐3′ ‐cyclopenten‐1′ ‐yl)‐pentan‐2‐one [(±)‐1c)] by Botrytis cinerea was carried out by hydroxylation in α position with respect to the double bond, or by epoxidation of the double bond itself. The main products had the hydroxy group at the methyl on the double bond. Simultaneously, a hydroxylation at the C′‐5 position in 1a and 1b was observed. In 1e, an additional hydroxylation occurred at the C‐4 position of the side chain. All the reactions were enantiospecific.
Restriction enzyme map of cryptic plasmid accompanying pR711b and pR409; identity of pR409 and pR388
Authors: Heidorn Jacqueline V. , Valentine Carrie R. I. 
Published: February 2007

AbstractA reference strain containing the IncW plasmid, pR409, was found to contain also a cryptic, conjugative plasmid, here named pJR15. After the separation of the two plasmids into different strains of bacteria, pR409 was found to have an identical restriction enzyme map to the IncW plasmid, pR388. Both pR409 and pR388 were isolated from the same hospital in London and confer sulphonamide and trimethoprim resistance. Orginally pR409 was reported to confer resistance to tetracycline, but this was not confirmed by the Plasmid Reference Center. pR409 appears to represent another isolate of pR388 in a different host background. The restriction enzyme map of the cryptic plasmid, pJR15 (39 kb), has been determined. pJR15 was found compatible with plasmids from 15 different incompatibility groups and has been found also in the reference strain of the IncD plasmid, pR711b. The HindIII and BglII digests of pR711 b are shown. The possible presence of the conjugative plasmid, pJR15, should be examined for studies on the sex pili or chromosomal mobilization properties of pR711b.
A new killer brewing yeast capable of degrading dextrin and starch
Authors: Janderová B. , Davaasurengijn T. , Vondrejs V. , Bendová O. 
Published: February 2007

AbstractHybrid strains able to ferment dextrins and to produce killer toxin were constructed by induced protoplast fusion of the brewing strain Saccharomyces uvarum P9 with two different strains of Saccharomyces sp.: the killer strain S. cerevisiae T 158 C and strain S. diastaticus (CCT 21‐49‐9‐a donor of dex genes). Hybrid strains decrease the amount of dextrins in fermented wort and are capable of eliminating heavy contaminations by sensitive strains of Saccharomyces sp.
DNA rearrangements associated with instability of an arginine gene in Streptomyces coelicolor A3(2)
Authors: Flett Fiona , Platt Jacqueline , Cullum J. 
Published: February 2007

AbstractStreptomyces coelicolor A3(2) gives rise to spontaneous chloramphenicol sensitive mutants at a frequency of about 0.3% per spore. These mutants are often genetically unstable and give rise to arginine auxotrophs (Arg−) at frequencies of 1–7% per spore. These Arg− mutants usually lack the enzyme argininosuccinate synthetase (one exception was found that lacked ornithine carbamoyltransferase) and were shown to have deleted the corresponding argG gene by hybridisation analysis using a cloned S. cattleya argG gene. The Arg− strains also showed a variety of different DNA amplification and deletion events in a region homologous to an amplified DNA sequence found in spontaneous Arg− mutants in S. lividans 66.
Increase of nucleoid size with increasing age of hyphal region in vegetative mycelia of Streptomyces granaticolor
Authors: Kretschmer Sigrid , Kummer Christel 
Published: February 2007

AbstractIn mycelia of Streptomyces granaticolor grown in liquid cultures the distribution of DNA was surveyed by staining and autoradiographic methods. The frequency of stained nucleoids was rather similar in young and old hyphal regions. However, the size of the nucleoids increased with the age of a hyphal region. The degree of heterogeneity in nucleoid size was particularly high during slow growth. In the autoradiograms silver grains (3H‐thymidine label) were also heterogeneously distributed along the hyphae. Calculation of the average number of silver grains per nucleoid revealed that the amount of DNA per nucleoid was 1.6 times higher in the more distant subapical regions than within the 35 μm long apical region.From a chase experiment it became obvious that the DNA segregated in a normal manner only within the apical region. When the chase lasted for one doubling time, the frequency of silver grains was reduced to 50% only within the about 30 μm long apical region. The label incorporated subapieally remained almost constant, therefore, indicating a lack of normal segregation. Only about 10% of the label was lost by branching. The lack of segregation of sister nucleoids after repeated rounds of replication was found to be responsible for the increase of nucleoid size within subapieal hyphal regions.
The role of copper(I)‐nicotinic acid complex on kojic acid biosynthesis by Aspergillus flavus
Authors: Megalla S. E. , Nassar A. Y. , Gohar M. A. S. 
Published: February 2007

AbstractAddition of cooper‐monovalent‐nicotinic acid complex to a synthetic medium specific for kojie acid production by Aspergillus flavus enhanced the production by about 47%. The substance is proposed to act via a biochemical utilization of the copper(I)‐B3 complex in a manner similar to that of the naturally utilized nicotinic acid. NAD and NADP like carriers with higher reactivity have been predicted.According to this prediction the biosynthetic route of kojic acid has been interpreted on the basis of a model proposed by BAJPAI et al. (1981). In this model the enzymes participating are dependent on NAD and NADP (glucose dehydrogenase and gluconate dehydrogenase) as well as on other reduction processes.
Transactivation of several genes of two native Serratia prophages after superinfection by phage kappa
Authors: Steiger H. , Garbe T. , Güleke R. , Gencic Simonida 
Published: February 2007

AbstractSerratia marcescens HY bacteria must be lysogenic with either prophage y or ψ to make it possible for phage χ to form plaques unless they carry a so‐called ink mutation. Genes in y and ψ termed any and anp were identified that after infection of ink+ cells are necessary for an effective propagation of these phages as well as of coinfecting χ phage. When χ infects y and/or ψ‐Iysogenic cells it transactivates the respective prophage genes by means of two early genes termed tay and tap. It appears that on infection of nonlysogenic ink+ cells χ damps its own development, provided the regulatory region of the responsible gene is undermethylated. After χ infection duly to achieve the special methylation of this region seems to be the function of any and anp.There are some more genes in y and ψ prophage under the control of tay and tap, concerning in both cases a Dam methylation (recognition sequence GATC) of χ DNA, a recombination proneness under restricting conditions of χ DNA not modified by the modification enzyme of HY, and the χ plaque size. By hybridization studies a region of homology common to y and ψ was demonstrated which from its size might comprise all the transactivated genes. The view is supported by genetic data indicating an affinity among the any and anp genes.Investigation of various any mutants were indicative of DNA inversions in this region of the y genome. Surprisingly some of the any mutants had become sensitive in their plaque forming ability to an inhibitory activity exerted by prophage ψ. Mutants of ψ unable to interfere but still able to lysogenize were isolated. A model is presented accounting for the formation of pleiotropic and nonpleiotropic mutations with Any phenotype and their reversion types. Possible functions of the y genes and their counterparts in ψ are discussed.