bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical effect on intensity ratios of K‐series x‐rays in vanadium, chromium and manganese compounds
Authors: Tamaki Yoichi 
Published: May 2005

AbstractKα and Kβ x‐ray fluorescence spectra of various V, Cr and Mn compounds were measured with a Bragg spectrometer. The relative intensities of the Kβ1,3, Kβ2, Kβ′ and Kβ″ lines with respect to the Kα line were determined to confirm the chemical effect on the Kβ/Kα intensity ratio obtained using a Si(Li) detector. Chemical effects on each component line are discussed with respect to the oxidation state of the metal ions. The relative importance of an increase in transition probabilities of the Kβ2 group (Kβ2 and Kβ″) was evaluated in the determination of the overall Kβ/Kα ratio.
Choice of optimum conditions for x‐ray excitation of elements with low atomic number
Authors: Pavlinsky G. V. , Dukhanin A. Yu. 
Published: May 2005

AbstractThe influence of the factors (window thickness, anode material and voltage on the x‐ray tube) that determine the x‐ray fluorescence intensity of elements with low atomic number (boron, carbon, nitrogen, oxygen, fluorine) is considered. The conditions for maximum x‐ray fluorescence intensity of the elements considered are greatly dependent on the matrix composition, as the ionization of an atom by the photo‐ and Auger electrons becomes significant. The calculations, performed for various matrices, show how the decrease in tube window thickness influences the x‐ray fluorescence intensity. Both the effective excitation by the primary radiation of the element measured and main matrix elements, providing high‐energy photo‐ and Auger electrons, should be taken into account when selecting the anode material. It was found that, in contrast to higher atomic number elements, the voltage increase at the tube contributes only insignificantly to the increase in the analytical signal for the elements considered. The software developed provide modelling of any analytical situation aimed at a quick selection of the optimum conditions for analysis of the elements being discussed.
Atomic level widths for x‐ray spectrometry
Authors: Campbell J. L. , Papp T. 
Published: May 2005

AbstractA self‐consistent set of level widths for the K–N7 subshells is assembled using literature experimental data from a variety of spectroscopic methods. In cases where Coster–Kronig processes contribute significantly, the widths differ from the predictions of the atomic single‐particle model; in the restricted regions where atomic many‐body predictions are available, the agreement is much better. The assembled widths will be useful to Si(Li) spectroscopists who wish to include natural width in the description of spectrometer lineshape; such inclusion will improve accuracy in both fundamental and analytical work. The present database is also of value in identifying where improvements to the currently incomplete knowledge of natural widths are most critical.
On the mechanism of exclusion of M2 double‐stranded RNA by L–A–E, double‐stranded RNA in Saccharomyces cerevisiae
Authors: Hannig Ernest M. , Leibowitz Michael J. , Wickner Reed B. 
Published: May 2005

AbstractL–A–E double‐stranded RNA (dsRNA), when introduced into cells carrying L–A–H and M2 dsRNAs, does not eliminate the L–A–H dsRNA, but (i) L–A–E does lower the copy number of L–A–H dramatically and (ii) L–A–E eliminates M2 dsRNA from the cell. That these two effects of L–A–E are related is shown by the fact that mutants of a strain carrying L–A–H and M2 selected for their resistance to exclusion of M2 by L–A–E [effect (ii)] have an altered L–A–H whose copy number is not lowered by L–A–E [effect (i)]. Although the L–A in K1 strains (L–A–HN in all cases examined) differs significantly both genetically and physically from the L–A in the K2 strain studied (L–A–H), the L–A–HN from the K1 strains can maintain M2 dsRNA, and the L–A–H from the K2 strains can maintain M1 dsRNA.
Mutations in ARS1 increase the rate of simple loss of plasmids in Saccharomyces cerevisiae
Authors: Strich Randy , Woontner Michael , Scott John F. 
Published: May 2005

AbstractAutonomously replicating sequence (ARS) elements are DNA sequences that promote extrachromosomal maintenance of plasmids in yeast. Mutations generated in vitro in the ARS1 region were examined for their effect on plasmid maintenance in a yeast centromeric plasmid. Our data show that mutations in the regions surrounding the ARS1 consensus sequence cause increases in the frequency of simple loss (1:0) event without affecting the rate of non‐disjunction (2:0). Removal of the consensus itself causes a drastic increase in the rate of simple loss. Sequences sensitive to mutagenesis were identified in each flanking region and differ with respect o their location and importance o ARS function. These results suggest that the role ARS1 plays in plasmid maintenance deals with the replication and/or localization of the plasmid in yeast.
PHO5 Upstream sequences confer phosphate control on the constitutive PHO3 gene
Authors: Bajwa Wajeeh , Rudolph Hans , Hinnen Albert 
Published: May 2005

AbstractTo identify the sequences involved in the regulation of the yeast acid phosphatase gene (PHO5) we constructed a series of hybrid promoters. Increasing lengths of 5′‐flanking sequences of the PHO5 gene were placed in front of the TATA‐box of constitutively expressed acid phosphatase gene (PHO3).The PHO5/PHO3 promoter constructions were used to replace the entire PHO5, PHO3 gene cluster on chromosome II. Depending on the length of PHO5 5′‐flanking sequences present the PHO3 gene driven by the hybrid promoter could now be derepressed in response to inorganic phosphate (low Pi) exactly as the PHO5 wild type gene. A critical regulatory element was located between position −402 to −351 (upstream from ATG) and sequences further downstream (from −351 to −300) could increase transcriptional activation. The transcription levels of PHO3 were determined by northern blot analysis, under repressed (high Pi) and derepressed (low Pi) conditions which was paralleled by an increase in extra‐cellular acid phosphatase activity. Fully regulated promoter hybrids showed a 40‐fold induction of mRNA levels, comparable to wild type PHO5 promoter. S1‐nuclease protection experiments revealed that the PHO5 5′‐flanking sequences, placed in front of PHO3, did not change the PHO3 transcription initiation site/s.
Molecular cloning of chromosome I DNA from Saccharomyces cerevisiae: Isolation of the MAK16 gene and analysis of an adjacent gene essential for growth at low temperatures
Authors: Wickner Reed B. , Koh Theodore J. , Crowley Joan C. , O'Neil Judy , Kaback David B. 
Published: May 2005

AbstractMAK16 is an essential gene on chromosome I defined by the thermosensitive lethal mak16–1 mutation. MAK16 is also necessary for M double‐stranded RNA replication at the permissive temperature for cell growth. As part of an effort to clone all the DNA from chromosome I, plasmids that complemented both the temperature‐sensitive growth defect, and the M1 replication defects of mak16–1 strains were isolated from a plasmid YCp50: Saccharomyces cerevisiae recombinant DNA library. The two plasmids analysed contained overlapping inserts that hybridized proportionally to strains carrying different dosages of chromosome I. Furthermore, integration of a fragment of one of these clones occurred at a site linked to ade1, confirming that this clone was derived from the appropriate region of chromosome I. An open reading frame adjacent to MAK16 potentially coding for a 468 amino acid protein was defined by sequence analysis. 185 amino acids of this open reading frame were replaced with a 1·2 kb fragment carrying the S. cerevisiae URA3 gene by a one‐step gene disruption. The resulting strains grew at a rate indistinguishable from the wild type at 20°C, 30°C, or 37°C, but could not grow at 8°C. The deleted region is thus essential only at 8°C, and we name this gene LTE1 (low temperature essential).
Tryptophan accumulation in Saccharomyces cerevisiae under the influence of an artificial yeast TRP gene cluster
Authors: Prasad Rajendra , Niederberger Peter , Hütter Ralf 
Published: May 2005

AbstractPlasmid pME559, carrying all five yeast TRP genes, was constructed. This plasmid is a yeast/Escherichia coli shuttle vector based on pBR322 and 2 μm‐DNA sequences derived from plasmid pJDB207. We studied in yeast (i) the stability of the plasmid under selective and non‐selective conditions, (ii) expression of all five TRP genes and (iii) tryptophan accumulation in yeast transformants. These studies were conducted in comparison with an earlier construction, pME554, which differs from plasmid pME559 in the expression of the TRP1 gene and which carries the TRP2 wild type instead of the TRP2fbr mutant allele. For stable maintenance of the plasmids in yeast a selection was necessary. Plasmid pME559 displayed normal expression of all TRP genes, and enzyme levels on average 23‐fold higher than in the wild type strain were found. In comparison, the maximal tryptophan flux observed in such a plasmid‐carrying strain was about ten‐fold higher than the maximal flux capacity in the wild type strain.
Multiplicity of mechanisms of carbon catabolite repression involved in the synthesis of alcohol oxidase in the methylotrophic yeast Pichia pinus
Authors: Sibirny A. A. , Titorenko V. I. , Efremov B. D. , Tolstorukov I. I. 
Published: May 2005

AbstractThe effect of various carbon compounds on the synthesis of alcohol oxidase in a medium with methanol was studied in the wild type strain of Pichia pinus as well as in gcr1 and ecr1 mutants defective in glucose and ethanol repression of methanol metabolic enzymes, respectively. Compounds repressing the synthesis of alcohol oxidase in the wild type strain were divided into four groups. Repression of alcohol oxidase by compounds of the first group (glucose, fructose, mannose, galactose, L‐sorbose and xylose) was impaired only in the gcr1 mutant and that by compounds of the second group (ethanol, acetate, 2‐oxoglutarate and erythritol) only in the ecr1 mutant. Repression by compounds of the third group (malate, dihydroxyacetone) was not impaired in both these regulatory mutants and that by compounds of the fourth group (succinate, fumarate, L‐arabinose, sorbitol, salicin, xylitol and cellobiose) was partially reduced in both gcr1 and ecr1 strains.Mutation gcr1 causes a significant decrease in phosphofructokinase activity. It also led to a six‐ to seven‐fold increase in intracellular pools of glucose‐6‐phosphate and fructose‐6‐phosphate and to a two‐fold decrase in the intracellular pool of fructose‐1,6‐bisphosphate. In ecr1 strains, a decrese in 2‐oxoglutarate dehydrogenase activity accompanied by an increae in activities of NAD‐ and NADP‐dependent isocitrate dehydrogenases and NAD‐ and NADP‐dependent glutamate dehydrogenases was demonstrated. The intracellular pool of 2‐oxoglutarate was increased 2·5‐fold in ecr1 strains. Genes GCR1 and ECR1 are not linked.The mechanisms of catabolite repression of alcohol oxidase in methylotrophic yeasts are discussed.
Effects of yeast suspension density on the accumulation ratio of transported solutes
Authors: Kotyk A. 
Published: May 2005

AbstractThe previously described effect of cell suspension density on metabolic and transport phenomena in yeast, apparently caused by inhibition by dissolved carbon dioxide, is also observed with the accumulation ratio of both sugars and amino acids where not only a kinetic but also an energetic factor comes into play. Unlike all previously measured metabolic and transport parameters, the dependence of the accumulation ratio on suspension density is not monotonic but shows a pronounced maximum in the range of 4–8 mg dry wt/ml, depending on yeast species and on cultivation conditions. In Rhodotorula gracilis and in Lodderomyces elongisporus it is not due to CO2 but is semiquantitatively related to the proton‐motive force across the plasma membrane as well as to the intracellular ATP content. It is observed both in oxygen and in argon, over a wide range of pH values and of temperatures, but it is suppressed by metabolic inhibitors. It is expressed only in a range of transported solute concentrations between about 0·1 and 10 mM.
Changes in robosomal properties during adenylate deprivation in the cells of Kluyveromyces lactis
Authors: Ishiguro Junpei , Azuma Yukimasa , Uritani Masahiro , Miyasaki Masazumi 
Published: May 2005

AbstractIn an adenine‐requiring mutant strain of the yeast, Kluyveromyces lactis the intracellular content of ATP is one‐third to one‐fifth that in a protophic wild strain under growing conditions. The quantitatives difference becomes rather small in resisting stationary‐phase cells. Temporary changes in the two‐dimensional protein patterns of mutant ribosomes occur when the ATP content during the transition phase of growth. The transfer of exponentially growing cells to a synthetic complete medium void of adenine induces the same changes in mutant ribosomes within several hours. Identification of robosomal proteins by two‐dimensional gel electrophoresis indicated all changeable proteins (at least five proteins) to belong to 40S ribosomal subunits. The mutant ribosomes prepared from the transitio‐phase cells have much lower activity (below 60%) for poly(U)‐directed polyphenylalanine synthesis than those in exponentially growing or resisting stationary‐phase cells. Thus, changes in ribosomal components associated with the differences in ribosomes activity in a cell‐free system were noted in the adenylate‐deprived cells of K. lactix.
Yeast flocculation: Quantification
Authors: Stratford M. , Keenan M. H. J. 
Published: May 2005

AbstractYeast flocculation is an orthokinetic process dependent upon mechanical agitation for all quantitative measurements. From several methods which were assessed, orbital shaking was selected as being the most practical as well as producing the most meaningful results.Quantitative measurements of flocculation were made in terms of minimum agitation threshold, initial rate, extent of flocculation at equilibrium and flocculated particle size at equilibrium. All these parameters were strain dependent. Critical cell density functions were formed if agitation was limiting regardless of how the agitation was imposed, and are unlikely to be related to bond strength.
The subcellular location of 4‐aminobutyrate aminotransferase in Candida boidinii and its probable role in the breakdown of putrescine and spermidine
Authors: Large Peter J. , Robertson Anne 
Published: May 2005

Abstract4‐Aminobutyrate aminotransferase (EC 2.6.1.19) was elevated in activity by 20‐ to 40‐fold in cells of the yeast Candida boidinii grown on spermidine, putrescine, 4‐acetamidobutyrate and 4‐aminobutyrate compared with activities detected in cells grown on ammonium, methylamine or 6‐aminohexanoate, confirming previous suggesions that it plays a key role in polyamine breakdown. Other enzymes of the proposed route of polymine breakdown were found to be non‐coordinately induced or derepressed during growth on spermidine or its putative breakdown intermediates. The enzyme was not sedimented from spheroplast lysates at 100 000 × g, and it is concluded that it is conclded that it is probably cytosoilc in its subcellular location (although the data do not exclude the possiblity of its being vacuolar).
Yeast flocculaiton: A dynamic equilibrium
Authors: Stratford Malcolm , Coleman Heather P. , Keenan Michael H. J. 
Published: May 2005

AbstractThe steady state in yeast flocculation is a dynamic equilibrium between flocculated and dispersed yeast cells. The free cell concentraiton is directly proportional to the total cell concentration and may be expressed as an equilibrium constant. Increased agitation decreases floc size and equlibrium constant whilst increasing floc‐surface area and free cell concentration. Values of equilibrium constant are influenced by agitation in a complex relationship probably involving the floc‐surface area and floc momentum.Inhibition of flocculation by mannose and low pH is reversible and becomes greater with increased agitation. Both these inhibitions appear consistent with a weakening of flocculent bond strength by these inhibitors.
A non‐conserved sequence in the 5′ region of the CYH2 intron from saccharomyces cerevisiae controls splicing efficiency of the pre‐mRNA
Authors: Swida Ulrike , Thüroff Eduardo , Steindert Edith , Käufer Norbert F. 
Published: May 2005

AbstractThe CYH2 gene from Saccharomyces cerevisiae containing one 510 bp intron is spliced inefficiently. We have shown previoulsy that a non‐conserved sequence within the intron is responsible for this low splicing efficiency. Using synthetic oligonucleotides comprising the identified region we show in this report that a very short region contains the specificity to act negatively on the splicing efficiency of the CYH2 gene. Furthermore, this sequence influences the splicing efficiency only when it is placed close to the 5′ splice site of the gene. Investigations with chimeric CYH2/β‐actin genes show that this sequence acts independent from its natural surroundings. We propose that this sequence might interact with splicing factor(s).
Structure and expression of yeast DPR1, a gene essential for the processing and intracellular localiation of ras proteins
Authors: Goodman Lauri E. , Perou Charles M. , Fujiyama Asao , Tamanoi Fuyuhiko 
Published: May 2005

AbstractThe ras protein represent a unique example of membrane proteins which apparently do not utilize the secretory pathway for their membrane localization. Instead, it is belived that palmaitic acid, covalently attached to the protein, acts as an anchor to the membranes. Recent identification of yeast mutants defective in the processing of the ras proteins has provideda novel approach for defining these biosynthetic process. We report here the charcterization of yeast DPR1, a gene essential for the processing of the ras proteins. The sequence of the gene indicates that it encodes a protein of 431 amino acids which contains no significant homology with any known proteins. It is a relatively hydrophilic protein of cysteine. The DPR1 gene product product has been identified in a cell‐free translation system as a proteinhaving an apparent molecular weight of 43 hd. This represents the first step in the translation system as a protein having an apparent molecular weight of 43 kd. This represents the first step in the investigation of a novel protein‐processing pathway, one that id distinct from the secretory pathway.
Genetic analysis in the methylotrophic yeast Hansenula polymorpha
Authors: Gleeson Martin A. , Sudbery Peter E. 
Published: May 2005

AbstractTechniques are described for the induction, isolation, and characterization of mutants of Hansenula polymorpha. In addition, techniques for controlled passage through the life cycle and genetic analyses, including complementation, tetrad and random spore analysis, have been developed and used to assign mutants to 62 complementation groups. We report that organism conforms to the expected genetics of a homothallic yeast and displays a Mendelian segregation of genes through meiosis. Preliminary mapping data are presented indicating linkage of three genes on a single linkage fragment. Enymatic analysis of methanol‐non‐utilizing mutants identified one class which is totally deficient in the key assimilatroy enzyme, dihydroxyacetone synthase.
Yeast KEX2 protease and mannosyltransferase I are localized to distinct compartments of the secretory pathway
Authors: Cunningham Kyle W. , Wickner William T. 
Published: May 2005

AbstractThe KEX2 protease (product of the KEX2 gene) functions late in the secretory pathway of Saccharomyces cerevisiae by cleaving the polypeptide chains of prepro‐killer toxin and prepro‐α‐factor at paired basic amino acid residues. The intracellular vesicles containing KEX2 protease sedimented in density gradients to a position distinct from those containing mannosyltransferase I (product of the MNN1 gene), a marker enzyme for the Golgi complex. The recovery of intact compartments containing these enzymes approached 80% after sedimentation. We propose that the KEX2 protease and mannosyltransferase I reside within distinct compartments.
Increase in gene expression by respiratory‐deficient mutation
Authors: Kaisho Yoshihiko , Yoshimura Koji , Nakahama Kazuo 
Published: May 2005

AbstractRespiratory‐deficient mutants (rho− cells) of Saccharomyces cerevisiae produced about 10 times as much human(h‐) lysozyme as did wild‐type strains (rho+ cells) when the GAL10 promoter was used in an expression plasmid with the h‐lysozyme gene. Introduction of intact mitochondria into the rho− cells resulted in a significant decrease in the production of h‐lysozyme, indicating that the rho− mutation increased the expression of the h‐lysozyme gene. The copy number of the expression plasmid was not responsible for the increased expression. The level of h‐lysozyme mRNA in the rho− cells was also much higher than that in the rho+ cells especially at the stationary phase. The increased expression of the h‐lysozyme gene was also observed when a glyceraldehyde‐3‐phosphate dehydrogenase gene promoter and the PHO5 promoter were used in the expression plasmid. The rho− mutation also increased the expression of the PHO5 gene under the control of the HIS5 promoter in a plasmid and the ACT1 gene in the yeast chromosome, but did not increase the expression of the ribosomal RNA gene. In contrast to the rho− mutants, pet mutants did not show higher gene expression compared with wild‐type strains.
Induction of cytochrome P‐450 and catalase activity in Saccharomyces cerevisiae by UV and X‐ray irradiation. Possible role for cytochrome P‐450 in cell protection against oxidative damage
Authors: Morichetti E. , Cundari E. , Del Carratore R. , Bronzetti G. 
Published: May 2005

AbstractCytochrome P‐450 was induced both in the diploid wild‐type D7 strain and in two isogenic DNA‐repair‐deficient strains (rad3 and rad56) of Saccharomyces cerevisiae following UV‐ and X‐irradiation. The induction occurred only in logarithmic growth phase cells and it was transient showing a peak 3 h after irradiation. The maximal amount of cytochrome P‐450 was directly proportional to the radiation does applied. Under the same experimental conditions an increase of the catalase activity was also observed, suggesting that activated oxygen species produced by irradiation might be implicated in the induction of both enzymes. The sensitivity to H2O2 of cells containing high cytochrome P‐450 levels was enhanced when this enzyme was specifically inhibited by tetrahydrofuran and metyrapone. This supports the hypothesis that cytochrome P‐450, as well as catalase, might be involved in cell protection against oxidative damage.
Saccharomyces cerevisiae mutants defective in chromosome segregation
Authors: McGrew Jeffrey T. , Xiao Zhixiong , Fitzgerald‐Hayes Molly 
Published: May 2005

AbstractWe have devised a genetic screen to identify trans‐acting factors involved in chromosome transmission in yeast. This approach was designed to potentially identify a subset of genes encoding proteins that interact with centromere DNA. It has been shown that mutations in yeast centromere DNA cause aberrant chromosome segregation during mitosis and meiosis. We reasoned that the function of an altered centromere should be particularly sensitive to changes in factors with which it interacts. We constructed a disomic strain containing one copy of chromosome III with a wild‐type centromere and one copy of chromosome III bearing the SUP11 gene and a mutant CEN3. This strain forms white colonies with red sectors due to nondisjunction of the chromosome bearing the mutant centromere. After mutagenesis we picked colonies that exhibited increased nondisjunction of the mutant chromosome as evidenced by increased red‐white sectoring. Using this approach, we have isolated three trans‐acting chromosome nondisjunction (cnd) mutants that are defective in maintaining chromosomes during mitosis in yeast.