bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of Saccharomyces cerevisiae cells accumulating Golgi organelles
Authors: Svoboda Augustin , Nečas Oldřich 
Published: February 2007

AbstractRestrictive phenotype of sec 7 mutant of Saccharomyces cerevisiae was examined by freezefracture electron microscopy. In accordance with previous findings (NOVICK et al. 1981) dictyosomes and middle‐size (200–600 nm) vesicles (BERKELEY bodies) were found to accumulate. Dictyosomes are formed by aggregated, flattened or dialted cisternae without associated secretory vesicles. After transfer to permissive conditions the dictyosomes disappear and are not detectable, just like in the wild type or in the permissive phenotype. Associated with the restrictive phenotype is an extended plasma membrane and tonoplasts with particlefree impressions.
Compartmentation of enzymes interconverting aclacinomycins in Streptomyces species AM 33352
Authors: Gräfe U. , Dornberger K. , Fleck W. F. , Freysoldt C. 
Published: February 2007

AbstractThe enzymatic interconversion of the aclacinomycins A (I), Y (II), and B (III) by Streptomyces spec. AM 33352/S 182 producing these aklavinone glycosides was investigated. The enzymes converting I to II and III, as well as vice versa, are located within different compartments separated by the cytoplasmic membrane.
Expression of the human interferon‐α1 gene under transcriptional and translational control of the speA gene
Authors: Laplace Frank , Hartmann Manfred , Klessen Christian , Tonew Marion , Malke Horst 
Published: February 2007

AbstractThe human gene for mature interferon‐α1 (IFN‐α1) was inserted in a new transcription‐translation fusion vector system based on the expression and secretion signals of the gene for type A streptococcal pyrogenic exotoxin, speA. As deduced from the known nucleotide sequences of the component elements, the encoded IFN‐α1 was a fusion protein carrying an N‐terminal extension of 17 amino acids. When inserted in appropriate vectors capable of replication in Escherichia coli, Bacillus subtilis and Streptococcus sanguis, this expression configuration directed the synthesis of antiviral activity in all 3 organisms, as judged by the cythopathic effect inhibition assay of Vesicular Stomatitis Virus. In E. coli JM101, IFN activity was found mainly in the cytoplasmic protein fraction whereas in the gram‐positive hosts, it was completely secreted into the culture medium.
Development of genetic maps of non‐conventional yeasts
Authors: Ogrydziak David M. 
Published: February 2007

AbstractNumerous methods based on classical genetics have been developed for the genetic mapping of yeasts. Recombinant DNA technology and technology for electrophoretic separation of chromosomes make new approaches possible. The state‐of‐the‐art in genetic mapping of Saccharomyces cerevisiae will be briefly reviewed. Then the availability and application of genetic mapping methods to non‐conventional yeasts will be surveyed. Development of the genetic maps of the asexual diploid Candida albicans and of the heterothallic yeast Yarrowia lipolytica will be discussed in more detail.
Replication and recombination in gene establishment in non‐Saccharomyces yeasts
Authors: Oliver Stephen G. 
Published: February 2007

AbstractA brief review is given on the establishment of recombinant DNA technology for non‐conventional yeasts. The availability of DNA delivery systems, selectable markers for identification of transformants, and the means of replicating and amplifying the recombinant DNA are discussed. Some of the existing transformation systems among non‐conventional yeasts are explained.
A gene‐cloning system for Kluyveromyces lactis and isolation of a chromosomal gene required for killer toxin production
Authors: Chen X. J. , Wésolowski‐Louvel M. , Tanguy‐Rougeau C. , Bianchi M. M. , Fabiani L. , Saliola M. , Falcone C. , Frontali L. , Fukuhara H. 
Published: February 2007

AbstractA transformation system derived from the circular plasmid pKD1 has been developed for Kluyveromyces lactis. The principle is essentially equivalent to that of the 2 μ/Saccharomyces cerevisiae transformation system. The main features of the system are presented. Using a pKD1‐based DNA bank of K. lactis, the KEX1 gene involved in the killer system was isolated by complementation.
Genetic control of Yarrowia lipolytica fatty acid synthetase biosynthesis and function
Authors: Schweizer Eckart , Köttig Hartmut , Regler Roger , Rottner Gerhard 
Published: February 2007

AbstractYarrowia lipolytica, like other lower fungi, has a fatty acid synthetase complex (FAS) with an α6β6 molecular structure. Both subunits are multifunctional proteins each with a molecular weight of more then 200000 daltons. A collection of FAS‐deficient2) Y. lipolytica mutants was isolated and characterized by both genetic complementation and enzyme activity measurements. It was found that the three acyl transferases (acetyl‐, malonyl‐ and palmityl‐transacylation) together with the enoyl reductase domain are located on subunit β and, therefore, are encoded by the gene locus FAS1. β‐Ketoacyl reductase, β‐ketoacyl synthase and acyl carrier protein functions are part of the FAS2‐encoded subunit α. Thus, the functional organization of FAS1 and FAS2 is identical in both yeasts, Saccharomyces cerevisiae and Yarrowia lipolytica. Nevertheless, the two yeasts differ significantly with respect to the intragenic complementation characteristics of fas1 and fas2 mutants. This finding is discussed in terms of a specific inter‐or intramolecular reaction mechanism within the oligomeric FAS complex. The pentafunctional Y. lipolytica FAS1 gene was isolated from a λgtll expression library using polyclonal antisera against the purified FAS complex. At present, sequencing of FAS1, which is more than 5 kilobases long, is almost completed. Available data indicate approx. 60 percent sequence homology together with an identical order of catalytic domains within subunit β of the two yeasts, Y. lipolytica and S. cerevisiae.
Genetic manipulation of non‐conventional yeasts by conventional and non‐conventional methods
Authors: Spencer J. F. T. , Spencer Dorothy M. , Reynolds Nicola 
Published: February 2007

AbstractIn recent years, yeasts other than those belonging to the species Saccharomyces cerevisiae and Schizosaccharomyces pombe have become increasingly important in industrial processes. Species such as Pichia stipitis, Hansenula polymorpha, Zygosaccharomyces rouxii, Saccharomyces exiguus, Torulaspora delbrueckii, Yarrowia lipolytica and others whose perfect stage is known, can be manipulated genetically by classical methods, but those belonging to the genera Candida (C. utilis, C. tropicalis, C. bombicola, C. zeylanoides, C. boidinii, etc.), Brettanomyces, Cryptococcus, Rhodotorula, and others of the different form genera, cannot be treated in this way. Some, such as Schwanniomyces and Debaryomyces spp., which have a perfect stage, are still difficult to manipulate by conventional means. Genetic manipulation of these yeasts can be approached from two points of view; the first involving improvement of strains by cross‐breeding within one species, and the second, the introduction of desirable genes from unrelated species and even from plants or animals.Two techniques are available for construction of industrially‐useful strains from these yeasts: protoplast fusion and transformation with chimaeric plasmids containing the gene(s) it is desired to introduce into the recipient strain. The methods for the latter procedure are well known but can be laborious and time‐consuming, especially if it is desired to introduce genes from plant or animal sources for production of enzymes, hormones, vaccines and similar products. Protoplast fusion is a simple technique which can be utilized in most laboratories and used for construction of improved yeast strains for brewing, baking, ethanol production and wine‐making, either by the fusion of desirable strains of the same species which do not sporulate, or by introduction of genes from non‐Saccharomyces species. Methods for fusion of species from different genera and isolation of the desired hybrids have been improved considerably in recent years. We have developed a method for isolation of strains carrying the desired genes by fusing a non‐Saccharomyces species with an auxotrophic strain of Saccharomces cerevisiae and selecting hybrids having the desired characteristics on appropriate media, after which the genes are transferred to the industrial strain by rare‐mating, repeated protoplast fusion, or classical mating as required. The advantages and limitations of the method are under investigation.
Identification by heteroduplex analysis of an invertible element (Min) common among IncM group plasmids
Authors: Karste Gunter , Adler Klaus , Klaus Siegfried , Tschäpe Helmut 
Published: February 2007

AbstractThe analysis of heteroduplexes between EcoRI digested DNA derived from IncM plasmids in the transfer‐off and in the transfer‐on state revealed an internal loop of about 1 kbp on a distinct large EcoRI fragment. The presence of an invertible element (Min) is suggested which enables the formation of conjugative piliat 30 °C, but switches off the pilus formation at 37 °C incubation temperature.
DNA fingerprinting of conjugative plasmids incompatible with R6K (IncX)
Authors: Prager Rita , Tietze Erhard , Tschäpe Helmut 
Published: February 2007

Abstract14 conjugative plasmids originated from different bacterial hosts and geographical sources were identified as members of the incompatibility group IncX with R6K as the reference plasmid. In spite of their close genetic relatedness (transfer and incompatibility properties), their molecular sizes ranged between 39 and 77 kb and DNA fingerprinting with endonucleases such as EcoRI, EcoRV, BamHI, Bg/I, Bg/II, PstI and Sa/I revealed a great variety of fragment patterns.
Radiorespirometric analysis of glucose dissimilation in Rhodococcus sp. An 117 and An 213
Authors: Schukat B. , Janke D. 
Published: February 2007

AbstractRadiorespirometric experiments were carried out by incubating various types of resting cells of either Rhodococcus sp. An 117 or Rhodococcus sp. An 213 under aerobic conditions with differentially labelled glucose. The results obtained indicate the constitutive nature of glucose catabolism in both these strains, i.e. there was no principle shift in glucose dissimilation during cell growth with different carbon substrates. On the basis of the observed ratios of percentage (cumulative) 14CO2‐formation from (6‐14C)glucose and (1‐14)glucose, the glycolytic EMP‐pathway was calculated to be the predominant catabolic route being operative to an extent of about 95% (strain An 117) and 78% (strain An 213).
The role of iron in the growth and hemolysin (Streptolysin S) production in Streptococcus pyogenes
Authors: Griffiths Bertie B. , McClain Oza 
Published: February 2007

AbstractFour strains of Streptococcus pyogenes were propagated at 37 °C in a reduced iron medium supplemented with Fe3+‐citrate to give concentrations of 1 through 11 micrograms per milliliter, in order to observe the effects of iron on growth and on the vitro production of Streptolysin S. Both growth and hemolysin production were observed to be influenced by medium iron concentration of which 1.2 μg per ml of iron was critical. Hemolysin was produced during the exponential phase of the growth cycle with maximum yield as the organism entered the stationary phase. Hemolytic activity (which was accepted as the ability of the hemolysin to lyse sheep erythrocytes) fell below detectable levels as the organisms entered fully into the stationary phase (9–10 hours post incubation). Serum (bovine, human, chicken) was observed to have a high stabilizing effect on the hemolysin.
Einsatz der Phenol‐Wasser‐Extraktion zur Isolierung des gruppenspezifischen Polysaccharidkomplexes aus B‐Streptokokken
Authors: Mehl M. , Starke R. , Möckel Claudia , Presber W. 
Published: February 2007

AbstractThe group specific polysaccharide of Group B streptococci was isolated either by means of phenol‐water extraction or by Lancefield extraction procedures. Two groups of rabbits were immunized with these substances to induce polyclonal antibodies. The phenol‐water extract induced antisera had a significantly higher titer against B streptococci than against A‐, D‐ and G streptococci in the agglutination reaction. The B‐specific titers in rabbits immunized with phenol‐water extract were significantly higher than those obtained in the rabbits immunized with Lancefield extract.In counter immunoelectrophoresis, only the antisera prepared by immunization with phenol‐water extract reacted with standard antigen from group B streptococci. The serological specificity of the phenolwater extract antigen isolated from B streptococci was confirmed by counterimmunoelectrophoresis. The antigen was a heterologous fraction with a molecular mass of 8 × 104 − 2 × 106 Dalton.
Transfer of Rhizobium leguminosarum Sym plasmids to R. meliloti and stability of resident and transferred plasmids
Authors: Miksch G. , Lentzsch P. 
Published: February 2007

AbstractThe recombinant symbiotic (Sym) plasmids pIJ1008 and pIJ1019 and the natural Sym plasmid pJB5JI of Rhizobium leguminosarum were transferred to derivatives of the Rhizobium meliloti strain Rm41 and to local wild strains of R. meliloti to investigate their transfer frequency and stability. Transfer to the latter strains was only successful through two‐step conjugations, i.e. transfer to a compatible R. meliloti strain followed by transfer to wild strains. The transferred Sym plasmids and the resident plasmids of R. meliloti with a molecular weight up to approximately 300 Md showed instability, resulting in the elimination of the latter, whereas the R. meliloti megaplasmids and their symbiotic properties were maintained. The natural plasmid pJB5JI was stable in free living transconjugants as well as those in symbiosis with alfalfa or pea. The two recombinant Sym plasmids showed deletions or structural changes dependending on the genotype of the recipient and the transferred plasmids. During symbiosis these plasmids may be further deleted or completely eliminated. The consequences for gene transfer programs are discussed in the paper.
Whole cell immobilization of D‐glucose isomerase enzyme on glass support
Authors: Shukla G. L. , Prabhu K. A. 
Published: February 2007

AbstractWhole cell immobilization of Lactobacillus sp. cells for D‐glucose isomerase activity was done by taking well washed cell slurries of bacteria, coating them on rough surfaces of glass rods or glass slides, drying them at 50 °C to 55 °C under infra red lamp and finaly treating with polyvinyl alcohol. The immobilized glucose isomerase activity of cells showed remarkable change in pH optimum, thermal stability, Km and Vmax values as compared to free enzyme of cells. The immobilized enzyme system was employed in the conversion of glucose to fructose using concentrates of amylase‐treated corn starch and cellulase‐treated bagasse cellulose.
Experimentelle Untersuchungen zur in vitro‐IFN‐Induktion durch verschiedene Polynucleotide in humanen Zellkultur‐Systemen
Authors: Glück B. , Meister W.‐V. , Witkowski W. , Stelzner A. , Hoffmann S. 
Published: February 2007

AbstractSeveral polynucleotides were tested for interferon induction in comparison with the standard Poly (IC) in human diploid fibroblasts and in human leukocyte suspensions.We received high IFN‐titre following superinduction of the polynucleotides in human fibroblasts.These results show that under superinduction conditions partly 3 times more interferon is induced in comparison with the standard inductor Poly (IC).The tested concentration of 10 μg/ml polynucleotides did not result in any IFN yields or only in very low ones in human leukocytes, which were only within the range of detectability.
Critical steps in degradation of chloroaromatics by rhodococci I. Initial enzyme reactions involved in catabolism of aniline, phenol and benzoate by Rhodococcus sp. An 117 and An 213
Authors: Janke D. , Al‐Mofarji T. , Straube G. , Schumann P. , Prauser H. 
Published: February 2007

AbstractTwo bacterial isolates (i.e. strains An 117 and An 213) capable of growing with aniline, phenol as well as benzoate as the sole carbon and energy source were studied with respect to (i) their taxonomic position, (ii) the enzyme reactions which initiate catabolism of the respective aromatic compounds, and (iii) the general type of regulation of the respective enzymes.Both isolates were established to be representatives of the actinomycete‐genus Rhodococcus. Experiments with resting cells and cell‐free extracts, respectively, revealed that in the two strains under study catabolism of each of the unsubstituted aromatic compounds occurs via the β‐ketoadipate pathway (with catechol as the central metabolite) due to the action of inducible enzymes. Although being potent inducers of the ring‐cleaving catechol 1,2‐dioxygenase in strains An 117 and An 213, all of the monochlorinated derivatives of aniline, phenol and benzoate, respectively, failed to support cell growth of the organisms. Cis, cis‐muconic acid proved to be non‐metabolizable by resting An 117 and An 213 cells, although substantial (inducible) muconate cycloisomerase activity was detectable in crude extracts prepared from the respective cell preparations. NADPH‐depending phenol hydroxylase activity could be demonstrated in crude extracts from phenol‐grown An 117 and An 213 cells. Evidence is presented that in both Rhodococcus strains under study substantial de novo synthesis of at least the initial aromatics‐oxygenating enzymes can be induced by phenol and aniline, respectively, even in the presence of either succinate (An 117) or acetate (An 213) which are known to be ortho‐pathway catabolites.
Characterization of a thermosensitive mutant of Streptomyces hygroscopicus defective in both DNA and RNA syntheses
Authors: Süss F. , Frunder B. , Klaus S. , Noack D. 
Published: February 2007

AbstractA stable temperature sensitive mutant of Streptomyces hygroscopicus JA6599 defective in both DNA and RNA syntheses is described. The mutant ts35 is characterized by an immediate stop of DNA synthesis and continued protein synthesis after transfer to restrictive temperature. The reinitiation of DNA synthesis begins immediately after a return to the permissive temperature. This kinetics of macromolecular synthesis at restrictive temperature appears to share similarities with a defect in the DNA elongation process, as described for Escherichia coli (CARL 1970, HANNA and CARL 1975).The simultaneous stop of both DNA and RNA syntheses may be caused by an additional mutational event affecting also the RNA synthesis. The data were discussed with respect to similar results in E. coli.
Mycoflora of air‐conditioners dust from Riyadh, Saudi Arabia
Authors: Bagy M. M. K. , Gohar Y. M. 
Published: February 2007

AbstractUsing the hair baiting technique, 6 genera and 14 species were collected on SABOURAUD'S dextrose agar from 37 dust samples from air‐conditioners. The most common fungi were Chrysosporium tropicum, C. indicum, C. keratinophilum, Aspergillus flavus followed by Acremonium strictum and Scopulariopsis brevicaulis.Using the dilution‐plate method, 26 genera and 52 species were collected from 37 dust samples on glucose‐(23 genera and 45 species) and cellulose‐(18 genera and 34 species) CZAPEK'S agar at 28 °C. The most prevalent species were Aspergillus niger, A. flavus, Penicillium chrysogenum, Stachybotrys chartarum, Ulocladium atrum, Mucor racemosus and Fusarium solani and A. niger, A. flavus, Trichoderma viride, P. chrysogenum, Ulocladium atrum, Chaetomium globosum, C. spirale, Stachybotrys chartarum and Mucor racemosus on the two media, respectively.
Regulation of metabolic branch points of aromatic amino acid biosynthesis in Pichia guilliermondii
Authors: Koll P. , Bode R. , Birnbaum D. 
Published: February 2007

AbstractThe regulatory properties of the enzymes involved in the aromatic amino acid biosynthesis of Pichia guilliermondii were investigated and compared with the regulatory pattern found in other yeast species. 3‐Deoxy‐D‐arabino‐heptulosonate‐7‐phosphate (DAHP) synthase, anthranilate synthase, chorismate mutase and prephenate dehydrogenase are key regulatory enzymes in P. guilliermondii. Two distinctly regulated isozymes of DAHP synthase, the initial pathway enzyme, which is inhibited by tyrosine or phenylalanine were separated by DEAE‐cellulose chromatography and were characterized. Tryptophan is an excellent feedback inhibitor of anthranilate synthase, the first definite step in tryptophan biosynthesis. There are two controlled enzymes within the specific synthesis of phenylalanine and tyrosine, chorismate mutase and prephenate dehydrogenase. Chorismate mutase exhibits a balanced allosteric responsivity to phenylalanine and tyrosine, when these are used as inhibitor; tryptophan acts as an allosteric activator. Tyrosine is an effective inhibitor of prephenate dehydrogenase, whereas the activity of prephenate dehydratase is not affected by any of the aromatic amino acids. The synthesis of the enzymes in the yeast was not repressed by any single exogenous aromatic amino acids, nor by combinations of the same.
Nachweis und Charakterisierung einer konstitutiven Lävansucrase und einer epigenetisch regulierten Saccharase in Pseudomonas syringae pv. phaseolicola
Authors: Sauerstein J. , Reuter G. 
Published: February 2007

AbstractPseudomonas syringae pv. phaseolicola, a plant pathogenic pseudomonad, possesses two sucrose‐splitting enzymes, a levansucrase and a sucrase. The levansucrase is found both extracellularly and intracellularly, and enzyme synthesis is independent of the carbon source. In addition to levansucrase, cells grown on sucrose contain a sucrase. The two sucrose‐splitting enzymes differ in their optimum pH value and optimum temperature as well as in their substrate specificities.
Calcium and the biological activities of two Streptomyces species isolated from the rhizosphere of soybean plants
Authors: Kamel Zeinat , Khalil Mary S. , Shalaby Ahmed M. 
Published: February 2007

AbstractCareful examination of the characteristics of both organisms revealed that we are dealing with Streptomyces violaceochromogenes and Streptomyces glaucescens. Calcium chloride decreased the permeability of both organisms as indicated by the low total nitrogen content of their media compared to the controls. Small doses of calcium nitrate suppressed the permeability of S. violaceochromogenes and increased that of S. glaucescens whereas the larger doses were stimulatory for both organisms. Calcium nitrate had similar effects on S. violaceochromogenes only without affecting S. glaucescens. The stimulatory effects of calcium gradually faded with increased concentration. Calcium chloride increased the proteolytic activity in S. violaceochromogenes media; a phenomenon that was apparent in S. glaucescens media only in the case of the larger doses. Calcium nitrate suppressed the proteolytic activity in S. glaucescens media. The cellulolytic activity of both organisms was suppressed by calcium but amylases were initiated in S. glaucescens media. Those of S. violaceochromogenes were arrested with the lower levels of calcium but the larger doses restored or stimulated their activity.