bluuebunny/crossref_metadata_2025_split huggingface dataset:
A cytoplasmic factor involved in the expression of resistance to C8‐ATC in Saccharomyces cerevisiae
Authors: Misiewicz M. H. , Kotylak Z. 
Published: February 2007

AbstractA dozen mutants of Saccharomyces cerevisiae, resistant to C8‐ATC have been characterized. C8‐ATC was previously established as a biologically toxic compound. Frequency of mutants (10‐7) was typical for spontaneous mutations. One very stable mutant was characterized extensively. The genetical analysis revealed that resistance in this mutant was determined by single‐gene mutation. The rhoo cells, obtained by ethidium bromide (EB) mutagenesis of the resistant strain, were completely devoid of resistance. A large percentage of rho‐ cells, obtained by a moderate EB treatment of resistant cells were still able to express resistance to C8‐ATC. Therefore we hypothesized that, in our particular strain, a cytoplasmic factor is involved in nuclear determination of resistance.
Intracellular expression of hIFNα genes in Escherichia coli and Bacillus subtilis directed by staphylokinase signals
Authors: Breitling Reinhard , Gase Klaus , Behnke Detlev 
Published: February 2007

AbstractPortable expression units for intracellular formation of heterologous proteins in Escherichia coli and Bacillus subtilis were constructed by inserting the transcription and translation initiation signals of the staphylokinase sak42D gene into the polylinker of plasmid pUC18. Fusions with ATG‐gene cassettes coding for mature human interferons (hIFN) α1 and α2 resulted in intracellular expression of both proteins in E. coli. The 20 fold lower yield of hIFNα2 was not due to unfavorable mRNA secondary structure formation as ruled out by constructing a hybrid hIFNα1/α2 gene. Intracellular expression of IFNα1 in B. subtilis reached 6 x 104 IU/ml. Nuclease SI mapping of transcriptional start sites revealed differential promoter usage in E. coli and B. subtilis. In E. coli transcription from the sak42D promoter was drastically reduced by by transcription initiating from upstream lac and tet promoters. In contrast, in B. subtilis transcription proceeded exclusively from the sak42D promoter.
Cloning of the resistant EcoRII recognition site of phage T7 into an EcoRII‐sensitive plasmid makes the site susceptible to the restriction enzyme
Authors: Krüger Detlev H. , Prösch Susanna , Reuter Monika , Goebel Werner 
Published: February 2007

AbstractThe recognition sequence 5'‐CC(A/T)GG for EcoRII in the bacteriophage T7 genome is refractory to this restriction endonuclease, despite not bearing the specific (protective) methylation. Following the integration of this site as part of a 219 bp fragment (in which the recognition sequence is flanked by about 100 bp of T7 origin) into the EcoRII‐sensitive vector pUC18, the T7 site becomes susceptible to cleavage, too. The same is true of recombinant pBR322 plasmids containing the T7‐derived recognition site. The results show that the flanking sequences are not immediately responsible for the refractory behaviour of EcoRII sites and are in agreement with data according to which EcoRII requires the coordinated presence of at least two recognition sites in its DNA substrate.
Purification and properties of α‐amylase from Micrococcus varians
Authors: Adeleye Adeyemi I. 
Published: February 2007

AbstractAn extracellular α‐amylase from Micrococcus varians was partially purified (63 fold) by ammonium sulphate precipitation followed by dialysis and separated by molecular exclusion into three components with molecular weights ranging from approximately 14,000 to 56,000. The amylase had a pH optimum of 7.0 and apparent Km of approximately 0.5 mg ml‐1 for starch. The enzyme activity was stimulated by Ca2+ and Mg2+ ions. Optimum temperature was 45 °C while there was a complete absence of activity at 70 °C in 20 min. Ethylene diaminetetra acetic acid (EDTA) and iodoacetic acid (IA) inhibited the activity of the enzyme.
Amylase production by three Bacillus strains active at alkaline pH
Authors: Bezbaruah R. L. , Gogoi B. K. , Pillai K. R. , Nigam J. N. 
Published: February 2007

AbstractThermostable α‐amylases produced by three different strains of Bacillus species are reported. The organisms are isolated from soil. They are designated as Bacillus stearothermophilus A004, B. stearothermophilus AN002 and B. coagulans R3. The heat stable amylases produced by these organisms were partially purified and characterized. The temperature optimum for B. stearothermophilus A004 and B. stearothermophilus AN002 amylase is 80 °C, whereas the optimum temperature for amylase activity is 85 °C for B. coagulans R3. The amylases from all three strains show extremely broad pH ranges of activity (6.0–12.0). Furthermore, the α‐amylases from B. coagulans R3 retains 35% activity even at 0.1 n alkali solution. Action of these enzymes on starch produces glucose, maltose, maltotriose, maltotetrose and other higher oligosaccharides, indicating the α‐amylase nature of the three enzymes.
Some properties of the leucine‐biosynthesizing enzymes from Candida maltosa
Authors: Bode Rüdiger , Birnbaum Dieter 
Published: February 2007

AbstractThe enzymes of the leucine pathway of Candida maltosa were investigated and the regulatory pattern was established. l‐leucine inhibited the α‐isopropylmalate (IPM) synthase, the first enzyme of the pathway. The inhibition was competitive with respect to α‐ketoisovalerate (Ki = 0.81 mm) and non‐competitive with respect to acetyl‐CoA. The Km values of the enzyme were estimated to be 0.57 mm for α‐ketoisovalerate and 0.064 mm for acetyl‐CoA. The Km values of the second enzyme, IPM dehydratase, were estimated to be 4.57, 0.57 and 1.79 for α‐IPM, β‐IPM and citraconate, respectively. The Km values of the β‐IPM dehydrogenase were calculated to be 0.42 mm for β‐IPM and 0.34 mm for NAD+. For this enzyme a novel regulatory pattern, its inhibition by l‐valine, was found. The inhibition was competitive with respect to β‐IPM (Ki = 1.7 mm) and non‐competitive with respect to NAD+.
Characterization of sectored colonies of a high‐yielding Claviceps purpurea strain
Authors: Didek‐Brumec Matjana , Gaberc‐Porekar Vladimira , Alačević Marija , Druškovič Blanka , Sočič Helena 
Published: February 2007

AbstractWhen sectored colonies of a high‐yielding Claviceps purpurea strain, producing ergotoxine alkaloids in submerged cultures, were investigated significant differences in surface morphology, mycelial differentiation, number of nuclei and in alkaloid production were established among sectors obtained after segregation. Biosynthetically most active sectors showed sclerotia‐like structure and a polynuclear state in cells, while low‐yielding sectors were composed mainly of undifferentiated hyphae with only few nuclei per cell. In cells of high productive sectors the content of DNA was about four times higher than in sectors of lower activity.
Assay of cellulolytic activity of cellulose‐decomposing fungi isolated from Egyptian soils
Authors: Moubasher A. H. , Mazen M. B. 
Published: February 2007

AbstractNinety two fungal species recovered on cellulose — Czapek's agar plates from Egyptian soils were assayed for their cellulolytic activities either at 28 °C (mesophilic) or at 45 °C (thermophilic or thermotolerant). The percentage increase of protein‐nitrogen over those of control was taken as a measure of this ability. At 28°C, the top species in cellulolytic activity were Penicillium oxalicum, Nectria haematococca, Gliocladium catenulatum, Myrothecium verrucaria and Aspergillus niger. The other species showed low, weak or non cellulalytic activity. At 45°C, the highest activity was manifested by Chactomium olivaceum, Sporotrichum thermophilum, Sepedonium chrysospermum, Aspergillus fumigatus, Humicola minima, Rhizomucor pusillus and Thermomyces lanugibnosus. All Penicillium species tested as well as some other fungal species were not capable of utilizing cellulsoe at 45°C.
Highly transformable mutants of Streptomyces aureofaciens containing restriction‐modification systems
Authors: Muchová Jana , Lacová Bibiána , Godány Andrej , Ševčíková Beatrica 
Published: February 2007

AbstractStreptomyces aureofaciens 13 is a mutant defective in chlortetracycline production. It was chosen as a potentially useful host for gene cloning in investigations of the organization of the biosynthetic genes for the tetracycline antibiotic pathway.From the Streptomyces aureofaciens 13 strain, three suitable clones were used for our work. The conditions for optimal formation and efficient transformation of protoplasts with plasmid DNAs have been determined. Transformation frequencies of about 104 to 105 per microgram of plasmid DNA were obtained when plasmids were isolated from Streptomyces strains. From the patterns of restriction enzyme digestion of plasmid DNA isolated from Streptomyces aureofaciens transformants, it was observed that the clones express modification systems which render plasmid DNAs resistant to cleavage by HindIII and EcoRI. Additionally, one of the clones produces the restriction endonuclease Sau13I (isoschizomer of SauI).The presence of the restriction‐modification system of Sau13I does not reduce the efficiency of plasmid transformation.
Growth and conidia production in race NG‐5/IA‐65 of Pyricularia oryzae Cav. in vitro
Authors: Awoderu V. A. , Esuruoso O. F. , Adeosun O. O. 
Published: February 2007

AbstractThe ability of Pyricularia oryzae to grow and sporulate under various artificial environmental conditions was investigated. The pathogen grew best on Potato Dextrose Agar and sporulated best on one percent Soluble Starch Yeast Extract Agar. Ammonium chloride medium as nitrogen source favoured its growth and conidia production. The pathogen utilized xylose, arabinose, starch, glucose and inulin for growth and conidia production. The minimum, optimum and maximum temperatures for growth and conidia production were 10°, 25° and 37°C. The humidity treatment increased conidia production from 8.0 × 103 to 18.4 × 103 conidia/ml. The optimal pH range for growth was 5.5–10.5 and 5.5–7.0 for conidia production. Exposing cultures to continuous artificial illumination enhanced conidia production.
Genetic studies of the ends of a lacked‐in Kappa prophage in Serratia marcescens by transductional and vegetative crosses
Authors: Steiger H. 
Published: February 2007

AbstractIn temperate phage x of Serratia marcescens several special features of different phages are combined. The unessential genes lI, iny, cII and, at least to some extent, even the integrase gene int are not subject to negative control by the repressor, the product of gene cIII. A genetic map of the prophage was established using defective, heat‐induced lysates of int− lysogens both in vegetative crosses with sus mutants of essential genes and in transduction of the four unessential genes to lysogenic recipients. Results from reciprocal four factor‐crosses concerning the order of the four genes had to be included. The four genes are located near the right end of the prophage, whereas cIII lies near its left end. In vegetative phage all five genes lie in an interval between the essential genes T and U, comprising 10% of x's genetic map. The right prophage end appears to face at least two trp cistrons, among them the gene encoding anthralinate synthetase.lI encodes a product that masks the phage receptors in the cell wall. The gene product of iny interferes with the growth of infecting phage y. The natural function of cII is still unknown, but some of its mutants display a cold‐sensitive phenotype, their plaques being clear at 30°C and turbid at 37°C. Bacteria with such prophages stop producing viable progeny when the cultures are shifted from 37°C to 30°C. These cold‐sensitive mutants are partly dominant and partly recessive.Analysing a virulent mutant, a gene ant encoding an antirepressor was discovered, but so far there is no evidence that it is regulated by an extra repressor. The gene is located relatively near the left prophage end.Evidence is presented that the exogenotes in transduction with the defective lysates continue to exist for some time after a first recombinational event.
Correlation between branching and elongation in germ tubes of Streptomyces granaticolor
Authors: Kretschmer S. 
Published: February 2007

AbstractWith four individual germ tubes (GTs), the distinct time of birth of branches was correlated to the kinetics of GT‐elongation. During the first three hours, corresponding to five doubling times, branching was suppressed. The time of birth of the first branch (tb1) coincided with the 5th step of the typical stepwise increase of the GT elongation rate (α). During this time, the quasi‐exponential kinetics of α changed to linear kinetics, which was attained either at the 5th of 6th α‐step. At the 5th step, the quotient of successive α‐values had been reduced from 2 at the beginning of outgrowth to 1.2.Once the first branch had been formed, further branches appeared as clusters (additional 2, 4, and 8 branches) at D‐intervals representing the doubling time of the hyphal length.The first branch appeard always in the vicinity of the spore. The average distance to the spore of 6.6 μm corresponded to four unit cells. At tb1, the unbranched region located between the first branch and the tip of the GTs was 42 μm long. The data concernning timing and location of the first branching in GTs suggest that initiation of branching was dependent on the accumulation of envelope precursors.
The ability of Armillariella mellea to transform cyclic monoterpenic alcohols and their acetates
Authors: Draczyńska‐Łusiak B. , Siewiński A. 
Published: February 2007

AbstractAn Armillariella mellea culture was found to transform trans‐ sobrerol to a very small extent, whereas menthol resisted its action altogether. Acetylation of both alcohols, on the other hand, reappointed their reactivity in the same A. mellea culture. Thus, trans‐sobrerol monoacetate and menthyl acetate underwent a two‐step transformation involving hydroxylation (preserving the acetate link) to 3‐acetoxy‐6,8‐p‐methen‐diol and 8‐hydroxymenthyl acetate, respectively, which were converted by hydrolysis to 3,6,8‐p‐menthen‐triol and 8‐hydroxymenthol, respectively.The transformation of racemic menthyl acetate was enantiospecific; (−) 8‐hydroxymenthol that was formed after 21 days contained 98% of enantiomer 1R, 3R, 4S.
Isolation of a double‐stranded RNA and a virus‐like particle from Geotrichum candidum
Authors: Matte O. , Chabalier C. , Ratomahenina R. , Bossy J. P. , Galzy P. 
Published: February 2007

AbstractA virus‐like particle (VLP) of 42 nm diameter was isolated from the lipolytic microorganism Geotrichum candidum. The VLP contains a linear double‐stranded RNA molecule of 1.70 μm in length. Proteins of VLP were studied by polyacryl amide gel electrophoresis.
Localization of the steroid 1‐dehydrogenase in Rhodococcus erythropolis IMET 7030 by immunoelectron microscopy
Authors: Wagner B. , Atrat P. G. , Clark‐Curtiss J. E. , Wagner M. 
Published: February 2007

AbstractThe steroid 1‐dehydrogenase of Rhodococcus erythropolis IMET 7030, an active steroid‐transforming strain, was localized by immunogold labelling both in cells induced with 17‐alpha‐methyl‐testosterone and in noninduced cells. The labelling intensity was much higher in induced cells than in noninduced cells, indicating increased enzyme production in the case of induction.Using the postembedding procedure, the main portion of the enzyme was found in the peripheral region of the cytoplasm. A considerable amount was bound in clusters to the inner side of the cytoplasmic membrane. The enzyme was also detected in channels connecting the cytoplasm with the cell surface.By means of the preembedding labelling, a few gold clusters could be detected on the cell surface. The significance of this observation was discussed.
Invasion of wood by basidiomycetous fungi VI. Quantitative but not qualitative differences in the pathovirulence of pathogenic and saprophytic decay fungi
Authors: Gramss G. 
Published: February 2007

AbstractWood dowels sterilely overgrown with test mycelia of pathogenic and saprophytic basidiomycetous wood‐decay fungi, respectively, were inserted into drill holes in the stems of 3 hardwood (Fagus sylvatica, Betula verrucosa, Sorbus aucuparia) and 1 softwood tree species (Picea abies). The host trees 40‐120 mm in diameter were part of the light‐starved understory of a timber forest. Eighteen to 52 months after inoculation the trees were dissected and the colonized stemwood was microbio‐logically examined. Extension growth and survival of the test mycelia in trees of known vitality were taken as a basis for fungal pathovirulence rating. Basidiomycetous wood‐decay fungi reach at best the status of physiologically facultative pathogens. They only colonized trees of the lowest vitality classes in the understory. For the expected range of pathovirulence, an appropriate host tree to be chosen had a proper range of vitality which expressed itself in a crown volume of 5 to 70% that of the crown of a free‐standing tree and a width of the current annual growth ring from 0.5 to 2.5 mm in dependence of the tree species. Increasingly moribund trees with low crown volumes and narrow growth rings favoured an unlimited mycelial expansion and survival, while in vital trees fungal expansion gradually came to a standstill within 18 to 52 months, frequently combined with an active killing of both the pathogenic and saprophytic mycelia. Development of pathogenic test mycelia much more depended on the choice of an appropriate host tree species than did development of saprophytic test mycelia. The stem colonization by several late saprophytes was nearly as extensive and durable as the stem colonization by notorious tree pathogens. Pathosism in wood‐decay basidiomycetes appeared thus to be a quantitative rather than a qualitative feature. For the dieback of the basidiomycetous test mycelia in the live stem reasons such as wood substrate depletion or antagonistic microbial activities could be excluded. The dieback rate of the test mycelia however was clearly enhanced in trees of increasing vitality, and it was enhanced with prolonged host‐fungus interaction times. In comparison with sound dominant trees, the endophyte incidence in the sapwood of moribund P. abies trees was not increased. At the instant of tree death or crown decapitation however a severe colonization with blue stain and soft rot fungi was observed that exerted considerable antagonism on test mycelia low in kratovirulence. The implication of this antagonistic action for the colonization of dying trees by pathogenic decay fungi are discussed.
Application of newly synthesized detergents in the side chain degradation of plant sterols by Mycobacterium fortuitum
Authors: Atrat P. G. , Koch B. , Szekalla B. , Hörhold‐Schubert C. 
Published: February 2007

AbstractNewly synthesized detergents of polyoxyethylene polyoxypropylene co‐polymers (o‐EOPO), polyoxyethylene polyoxypropylene adducts of the diethylene triamine (DETA‐EOPO), and steroidal detergents (SDD) stimulate significantly side chain degradation of plant sterols referring to both the sterol degradation and the formation of the product, 9α‐hydroxy‐androsta‐4‐ene‐3,17‐dione (9 OH‐AD), by Mycobacterium fortuitum NRRL‐B‐8119. Highest stimulative effects were observed with derivatives of the DETA‐EOPO group. Using compounds of the Co‐EOPO group optimal sterol transformation rates were found for polymers with a polyoxypropylene domain of 1400–2000 in molecular weight and with a polyoxyethylene content of 20–50%. Mostly efficient steroidal detergents tested were the 4‐cholesten‐3‐(O‐carboxymethyl)‐oxime and the amino acid adducts of sterol‐3β‐chlorocarbonates.Detergents were favourably applied as pre‐formed sterol‐detergent complexes (9:1/w:w) in submers fermentation procedures. By treating harvested resting cells of M. fortuitum with derivatives of Co‐EOPO or DETA‐EOPO a considerable activation of the cells takes place concerning the sterol degradation and the formation of 9 OH‐AD at a high yield in subsequent transformation process on buffer.In solubilization experiments we revealed that there is no correlation between the detergent mediated solubilization of the hydrophobic sterol substrate in the aqueous medium and the transformation activity of the bacterial cells.The detergents are assumed to interact with a multicomponent mesophase (FMCM) which is placed between cells and sterol surface and mediates the transport.
Effect of cosubstrates on the dechlorination of selected chlorophenolic compounds by Rhodococcus erythropolis 1CP
Authors: Gorlatov S. N. , Golovleva L. A. 
Published: February 2007

AbstractEffects of aromatic and nonaromatic cosubstrates on the rate of 2,4‐dichlorophenol degradation by R. erythropolis 1CP were studied under growth and nongrowth conditions. Glucose and maltose were found to accelerate 2,4‐dichlorophenol (initial conc. 50 mg/l) dechlorination from 11 days to 24 and 20 h, respectively. The stimulating effect was observed within the range of glucose concentration of 0.5 – 2.0 g/l in the medium. Ascorbic acid at a concentration of 10–70 mg/l as a nongrowth substrate also increased the decomposition of 2,4‐dichlorophenol, though at a lower degree than glucose. Experiments with washed cells showed the limiting stage of chlorophenol degradation by R. erythropolis 1CP to be, possibly, aromatic ring dechlorination after its hydroxylation. As an additional source of electrons, glucose introduced into suspensions of washed cells grown on 3‐hydroxybenzoate made it possible to eliminate the bottleneck in 2,4‐dichlorophenol metabolism by significantly accelerating dechlorination of 3,5‐dichlorocatechol. Based on the experimental and literature data, the enzyme systems involved in 2,4‐dichlorophenol degradation by the culture R. erythropolis 1CP are assumed to be nonspecific.
Neighbour restoration: A possible explanation for some “broken” survival curves of UV‐irradiated Escherichia coli K12 cells
Authors: Bernardo‐Filho M. , Leitao A. C. , Alcantara‐Gomes R. 
Published: February 2007

AbstractSurvival curves for UV irradiation of five non‐filamenting strains of E. coli K12 decrease exponentially at moderate levels of radiation but are broken at high levels of radiation. That is, it appears a change in the slope of survival curves, featuring a tail.As this phenomenon was observed with strains bearing uvrA and recA mutations it must be independent of the products of these genes.Experiments with isolated surviving colonies and synchronized cultures eliminated genetic and phenotypic heterogeneity as reasons for the tails in the survival curves.UV survival increased 10‐ to 15‐fold when UV‐irradiated cells were plated either with cells unable to grow in the plating medium or with bacterial cell‐free extracts.We suggest that factors related to the high cell densities used to obtain survival curves at high radiation levels (neighbour restoration) could be responsible for the survival increases, generating the tailed survival curves.
Immunoelectronmicroscopic study of the nucleoid structure of hydrogen bacteria
Authors: Mogilnaya Olga A. , Kiselyova Elena V. , Medvedeva Svetlana E. , Puzir Alexey P. , Guseynov Oleg A. , Kulyba Natalia N. , Kozlov A. V. 
Published: February 2007

AbstractElectron microscopical studies of the nucleoid structure of hydrogen bacteria using ultrahin sections and spread DNA from bacterial cell lysates revealed a different DNA packaging in the cell. A compact state of the major part of DNA at all growth stages and stability of nucleosome‐like structures were shown. The use of antibodies to HU protein of E. coli labelled by protein A‐colloidal gold demonstrated the immunological relationship between HU protein of E. coli and histone‐like proteins of Alcaligenes eutrophus and their possible role in the nucleosome‐like DNA packaging in procariotic genome.