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  • Saccharomyces cerevisiae  (243)
  • maize  (201)
  • Springer  (444)
  • American Institute of Physics
  • Institute of Physics (IOP)
  • Springer Nature
  • 2010-2014
  • 1990-1994  (444)
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  • 1
    Electronic Resource
    Electronic Resource
    Adaptation of a Saccharomyces cerevisiae strain to high copper concentrations (1994)
    Springer
    BioMetals 7 (1994), S. 221-226 
    Details
    ISSN: 1572-8773
    Keywords: catalase ; copper resistance ; pH-dependent growth ; Saccharomyces cerevisiae ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A strain of Saccharomyces cerevisiae has been adapted to increasing concentrations of copper at two different pH values. The growth curve at pH 5.5 is characterized by a time generation increasing with the amount of added copper. A significant decrease of cell volume as compared with the control is also observed. At pH 3 the cells grow faster than at pH 5.5 and resist higher copper concentrations (3.8 against 1.2 mm). Experimental evidence indicates that, after copper treatment, the metal is not bound to the cell wall, but is localized intracellularly. A significant precipitation of copper salts in the medium was observed only at pH 5.5. Increased levels of superoxide dismutase (SOD) activity were observed in copper-treated cells and which persisted after 20 subsequent inocula in a medium without added metal. On the contrary, catalase activity was not stimulated by copper treatment and, hence, not correlated with SOD levels. The mechanism of copper resistance, therefore, probably involves a persistent induction of SOD, but not of catalase, and it is strongly pH-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149552
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  • 2
    Electronic Resource
    Electronic Resource
    Chimeric evolution of the 2-μm genome in Saccharomyces cerevisiae (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 363-368 
    Details
    ISSN: 1432-1432
    Keywords: Saccharomyces cerevisiae ; 2-μm circle ; DNA sequencing ; Horizontal transmission ; Site-specific recombination ; Selfish DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the nucleotide substitution pattern over the entire genome of two unique variants of the 6,300-bp selfish DNA (2 μm) plasmid in Saccharomyces cerevisiae. The DNA sequence of the left-unique region is identical among 2-μm variants, while the right-unique region shows substantial divergence. This chimeric pattern cannot be explained by neutral or Darwinian selection models. We propose that horizontal transmission of the 2-μm plasmid coupled with a directed, polarized gene conversion maintains the DNA sequence of the left-unique region, whereas the right-unique region is subject to random drift and Darwinian selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163153
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  • 3
    Electronic Resource
    Electronic Resource
    Mistranslation of human phosphoglycerate kinase in yeast in the presence of paromomycin (1994)
    Springer
    Current genetics 26 (1994), S. 95-99 
    Details
    ISSN: 1432-0983
    Keywords: Translational fidelity ; Paromomycin ; Stuttering ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Missense errors in the translation of mRNAs in Saccharomyces cerevisiae were screened by looking for charge heterogeneity of proteins on two-dimensional gels resulting from the substitution of charged and neutral amino acids. No such mistranslation was detected in wild-type yeast strains grown in the presence of the translational error-inducing antibiotic paromomycin. However, paromomycin-induced mistranslation of a heterologous mRNA, encoding human phosphoglycerate kinase expressed in yeast, was seen. We suggest that the combination of error-prone translation of a heterologous mRNA, and growth in the presence of paromomycin, leads to an accumulation of mistranslated proteins that can be detected by two-dimensional gel electrophoresis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313794
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  • 4
    Electronic Resource
    Electronic Resource
    Saccharomyces cerevisiae YDR1, which encodes a member of the ATP-binding cassette (ABC) superfamily, is required for multidrug resistance (1994)
    Springer
    Current genetics 26 (1994), S. 285-294 
    Details
    ISSN: 1432-0983
    Keywords: ABC superfamily ; Multidrug resistance ; Saccharomyces cerevisiae ; YDR1 gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A multidrug resistance gene, YDR1, of Saccharomyces cerevisiae, which encodes a 170-kDa protein of a member of the ABC superfamily, was identified. Disruption of YDR1 resulted in hypersensitivity to cycloheximide, cerulenin, compactin, staurosporine and fluphenazine, indicating that YDR1 is an important determinant of cross resistance to apparently-unrelated drugs. The Ydr1 protein bears the highest similarity to the S. cerevisiae Snq2 protein required for resistance to the mutagen 4-NQO. The drug-specificity analysis of YDR1 and SNQ2 by gene disruption, and its phenotypic suppression by the overexpressed genes, revealed overlapping, yet distinct, specificities. YDR1 was responsible for cycloheximide, cerulenin and compactin resistance, whereas, SNQ2 was responsible for 4-NQO resistance. The two genes had overlapping specificities toward staurosporine and fluphenazine. The transcription of YDR1 and SNQ2 was induced by various drugs, both relevant and irrelevant to the resistance caused by the gene, suggesting that drug specificity can be mainly attributed to the functional difference of the putative transporters. The transcription of these genes was also increased by heat shock. The yeast drug-resistance system provides a novel model for mammalian multidrug resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310491
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic effects of photoactivated psoralens during meiosis in DNA repair mutantpso3-1 ofSaccharomyces cerevisiae (1994)
    Springer
    Current genetics 25 (1994), S. 19-23 
    Details
    ISSN: 1432-0983
    Keywords: Psoralen ; DNA repair mutants ; Gene conversion ; Recombination ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of the DNA repair genePSO3 on photoactivated psoralen-induced meiotic recombination, gene conversion, reverse mutation, and on survival, was assayed in diploid strains ofSaccharomyces cerevisiae homozygous for the wild-type or thepso3-1 mutant allele. Sporulation was normal in thepso3-1 diploid. Wild-type and mutant strains had the same sensitivity to photoactivated monofunctional psoralen (3-CPs+UVA) in meiosis-uncommitted and meiosis-committed stages. The mutant showed higher sensitivity to photoactivated bifunctional psoralen (8-MOP+UVA) during all stages of the meiotic cycle. Mutation induction by 3-CPs+UVA or 8-MOP+UVA in meiosis-committed cells revealed no significant differences between wild-type and thepso3-1 mutant. The status of thePSO3 gene has no influence on the kinetics of induction of gene conversion and crossing-over after 3-CPs+UVA treatment in meiosis-committed cells: gene conversion was blocked while recombination was induced. After treatment with 8-MOP+UVA gene conversion was also blocked in both strains while crossing-over could only be observed in meiosis-committed wild-type cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712961
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  • 6
    Electronic Resource
    Electronic Resource
    New in-vivo cloning methods by homologous recombination in yeast (1994)
    Springer
    Current genetics 25 (1994), S. 180-183 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; In-vivo cloning ; Non-replicative vectors ; Homologous recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have devised a new strategy to clone DNA sequences from an yeast autonomously-propagating plasmid into a non-autonomous integrative vector by in-vivo recombination. The method consists of a first step in which the replicative plasmid carrying the DNA fragment of interest forms a co-integrate with the non-replicative plasmid by an induced in-vivo reciprocal exchange accompanied by gene conversion. The dimeric plasmid obtained is then purified and cut with an appropriate restriction enzyme and ligated independently to obtain the two intact monomeric plasmids, the original autonomous plasmid plus the new non-autonomous plasmid carrying the subcloned DNA fragment. The dimeric co-integrate can also serve as substrate for a second in-vivo reciprocal exchange that produces new autonomous plasmids carrying the desired DNA fragment. The technique considerably expands the applications of in-vivo cloning in yeast by complementing three important characteristics of previously published methods: (1) it can be used to clone into non-propagating vectors; (2) co-transformation experiments are not required; and (3) the intermediate co-integrate can be used to generate new types of autonomously-propagating plasmids directly. These characteristics are independent of whether the DNA insert is flanked by appropriate restriction sites or whether it does, or does not, express a detectable phenotype in yeast. The method is particularly useful for the cloning of large DNA fragments and can be used for plasmids from organisms other than yeasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309546
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  • 7
    Electronic Resource
    Electronic Resource
    Expression of the Saccharomyces cerevisiae CYT2 gene, encoding cytochrome c1 heme lyase (1994)
    Springer
    Current genetics 25 (1994), S. 291-298 
    Details
    ISSN: 1432-0983
    Keywords: Cytochrome c 1 ; Cytochrome c 1 heme lyase ; GRF2p ; Glucose repression ; HAPp ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we examine the expression of the Saccharomyces cerevisiae CYT2 gene, which encodes cytochrome c 1 heme lyase. This enzyme is required for covalent attachment of heme to apocytochrome c 1, a subunit of the mitochondrial respiratory chain. Transcription of the 1-kb CYT2 mRNA initiates at four prominent sites at a distance of 52–225 bp in front of the AUG start codon. The level of CYT2 mRNA is not influenced by the presence or absence of oxygen or of heme, but it is subject to carbonsource control. The concentration of the CYT2 mRNA is significantly reduced in glucose-grown cells as compared to cells grown under non-repressing conditions. Neither the HAPp activator proteins nor MIG1p, a repressor protein involved in glucose repression, seem to mediate this effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351480
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  • 8
    Electronic Resource
    Electronic Resource
    The Escherichia coli recA gene increases UV-induced mitotic gene conversion in Saccharomyces cerevisiae (1994)
    Springer
    Current genetics 25 (1994), S. 472-474 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; recA gene expression ; UV radiation ; Mitotic gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of the Escherichia coli RecA protein on mitotic recombination in the diploid D7 strain of Saccharomyces cerevisiae damaged by UV radiation was investigated. The D7 strain was transformed by two modified versions of the pNF2 plasmid: one, containing the ADH-1 promoter, and the other containing the recA gene tandemly arranged behind the ADH-1 promoter region. Immunological analysis proved the presence of the 38-kDa RecA protein in D7/pNF2ADHrecA transformants. We observed a positive effect of recA gene expression on mitotic gene conversion, mainly at higher doses of UV radiation. The results indicate that a RecA-like activity could participate in steps preceeding mitotic conversion events in yeast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351789
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  • 9
    Electronic Resource
    Electronic Resource
    ERV1 is involved in the cell-division cycle and the maintenance of mitochondrial genomes in Saccharomyces cerevisiae (1994)
    Springer
    Current genetics 26 (1994), S. 15-20 
    Details
    ISSN: 1432-0983
    Keywords: Cell-division cycle ; Mitochondrial genome ; Nuclear mutation ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In former studies it was found that the ERV1 gene is essential for cell viability and for the biogenesis of functional mitochondria. A temperature-sensitive nuclear mutant exhibits a severe reduction in all the mitochondrial transcripts. Elimination of the gene leads to growth arrest after a few cell divisions. The putative gene product bears the characteristics of a regulatory factor since it has low expression rate and a high content of charged amino acids. In this study it is further verified that the ERV1 gene alone is responsible for the observed cellular and mitochondrial defects. The 5′ region of the gene is analysed by DNA deletions and complementation studies. Expression of the gene under the control of the GAL1-10 promoter in a disruption strain of ERV1 allows a more detailed specification of its influence on mitochondrial and cellular functions. Immediate and complete loss of mitochondrial genomes is observed after the promoter has been shut off, whereas the yeast cells are still able to grow for a limited time under these conditions. Analysis of the cells by in-vivo DNA flurorescence demonstrates a specific arrest in the cell-division cycle as the terminal phenotype. To further characterize the temperature-sensitive allele of ERV1 the mutated gene has been isolated and sequenced. A single point mutation which leads to the exchange of a single amino acid is found in the reading frame.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326299
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  • 10
    Electronic Resource
    Electronic Resource
    The yeast nuclear gene MRP-L13 codes for a protein of the large subunit of the mitochondrial ribosome (1994)
    Springer
    Current genetics 26 (1994), S. 8-14 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Nuclear gene ; Mitochondria ; Mitochondrial ribosomal protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nuclear gene MRP-L13 of Saccharomyces cerevisiae, which codes for the mitochondrial ribosomal protein YmL13, has been cloned and characterized. It is a single-copy gene residing on chromosome XI. Its nucleotide sequence was found to be identical to that of the previously reported ORF YK105. A comparison of the predicted protein sequence of the MRP-L13 gene product and the actual N-terminal amino-acid sequence of the isolated YmL13 protein indicated that the mature protein is preceded by a mitochondrial signal peptide of 86 amino-acid residues, which is the longest among all known mitochondrial ribosomal proteins of S. cerevisiae. No sequence similarity was found to any other ribosomal protein in the current databases. The transcription of MRP-L13 was found to be repressed in the presence of glucose. Its protein product is not strictly essential for mitochondrial functions, but disruption of the gene by insertion of LEU2 noticeably affected cellular growth on non-fermentable carbon sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326298
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  • 11
    Electronic Resource
    Electronic Resource
    Antisense RNA regulation of the ILV2 gene in yeast: a correction (1994)
    Springer
    Current genetics 25 (1994), S. 289-289 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Inducible antisense gene ; Acetolactate synthase ; Bradytrophic phenocopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A previous report of the use of antisense RNA to regulate gene expression in yeast is incorrect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357175
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  • 12
    Electronic Resource
    Electronic Resource
    Isolation and characterization of three mutants with increased sensitivity to photoactivated 3-carbethoxypsoralen in Saccharomyces cerevisiae (1994)
    Springer
    Current genetics 25 (1994), S. 407-411 
    Details
    ISSN: 1432-0983
    Keywords: Psoralen sensitivity ; Saccharomyces cerevisiae ; DNA repair ; Oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The complementation and genetical analysis of yeast mutants sensitive to photoactivated 3-carbethoxy-psoralen define three novel recessive mutant alleles pso-5-1, pso6-1, and pso7-1. Their cross-sensitivity to UV254nm, radiomimetic mutagens, and to chemicals enhancing oxidative stress suggest that these mutants are either impaired in metabolic steps protecting from oxidative stress or in mechanisms of the repair of oxygen-dependent DNA lesions. None of the three novel mutant alleles block the induction of reverse mutation by photoactivated mono- and bi-functional psoralens, nitrogen mustards, or UV254nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351778
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  • 13
    Electronic Resource
    Electronic Resource
    Suppression of a mitochondrial point mutation in a tRNA gene can cast light on the mechanisms of 3′ end-processing (1994)
    Springer
    Current genetics 25 (1994), S. 451-455 
    Details
    ISSN: 1432-0983
    Keywords: tRNA processing ; Saccharomyces cerevisiae ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used a genetic approach to study the nuclear factors involved in the biogenesis of mitochondrial tRNAs. A point mutation in the mitochondrial tRNAAsp gene of Saccharomyces cerevisiae had previously been shown to result in a temperature-sensitive respiratory-deficient phenotype as a result of the absence of 3′ end-processing of the tRNAAsp. Analysis of mitochondrial revertants has shown that all revertants sequenced have a G-A compensatory change at position 53, which restores the hydrogen-bond with the mutated nucleotide. We then searched for nuclear suppressors to identify the nuclear gene(s) involved in mitochondrial tRNA 3′ end-processing. One such suppressor mutation was further characterized: it restores tRNAAsp maturation and growth at 36°C on glycerol medium in heterozygous diploids, but leads to a defective growth phenotype in haploids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351785
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  • 14
    Electronic Resource
    Electronic Resource
    Stabilization of methionine-rich protein in Saccharomyces cerevisiae: targeting of BZN protein into the peroxisome (1994)
    Springer
    Current genetics 26 (1994), S. 390-397 
    Details
    ISSN: 1432-0983
    Keywords: Overexpression ; Peroxisomes ; Saccharomyces cerevisiae ; Stabilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have constructed a gene coding for the 12-kDa intermediate form of the 2s methionine-rich protein from Bertholletia excelsa seeds. This protein, expressed intracellularly in yeast, is characterised by a 20-min balf-life. By adding 11 amino acids corresponding to the peroxisome-targeting sequence (PTSc) of luciferase, we have significantly increased its half-life. This stabilization allowed accumulation of the BZN protein into the peroxisome as judged by cell fractionation. Accumulation of the 12-kDa protein results in a significant increase of the total methionine content in yeast cells (30%) indicating that such a microorganism could represent a practicable protected shuttl for an animal-feed additive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309924
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  • 15
    Electronic Resource
    Electronic Resource
    Sequence analysis of three deficient mutants of cytochrome oxidase subunit I of Saccharomyces cerevisiae and their revertants (1994)
    Springer
    Current genetics 26 (1994), S. 546-552 
    Details
    ISSN: 1432-0983
    Keywords: Cytochrome oxidase ; Revertant ; Mitochondria ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three respiratory-deficient mutants of cytochrome oxidase subunit I in the yeast mitochondrion have been sequenced. They are located in, or near, transmembrane segment VI, the catalytic core of the enzyme. Respiratory-competent revertants have been selected and studied. The mutant V244M was found to revert at the same site in valine (wild-type), isoleucine or threonine. The revertants of the mutant G251R were of three types: glycine (wild-type), serine and threonine at position 251. A search for second-site mutations was carried out but none were found. Among 60 revertants tested, the mutant K265M was found to revert only to the wild-type allele.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309948
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  • 16
    Electronic Resource
    Electronic Resource
    Kinetic studies of killer toxin K1 binding to yeast cells indicate two receptor populations (1994)
    Springer
    Archives of microbiology 162 (1994), S. 211-214 
    Details
    ISSN: 1432-072X
    Keywords: Killer toxin ; Saccharomyces cerevisiae ; Toxin binding ; Cell wall receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A recently described new method for determination of killer toxin activity was used for kinetic measurenments of K1 toxin binding. The cells of the killer sensitive strain Saccharomyces cerevisiae S6 were shown to carry two classes of toxin binding sites differing widely in their half-saturation constants and maximum binding rates. The low-affinity and high-velocity binding component (K T1=2.6x109 L.U./ml, V max1=0.19 s-1) probably reflects diffusion-limited binding to cell wall receptors; the high-affinity and low-velocity component (K T2=3.2x107 L.U./ml, V max2=0.03 s-1) presumably indicates the binding of the toxin to plasma membrane receptors. Adsorption of most of the killer toxin K1 to the surface of sensitive cells occured within 1 min and was virtually complete within 5 min. The amount of toxin that saturated practically all cell receptors was about 600 lethal units (L.U.) per cell of S. cerevisiae S6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314477
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  • 17
    Electronic Resource
    Electronic Resource
    Effect of the new fluorescent brightener Rylux BSU on morphology and biosynthesis of cell walls in Saccharomyces cerevisiae (1994)
    Springer
    Archives of microbiology 161 (1994), S. 340-344 
    Details
    ISSN: 1432-072X
    Keywords: Rylux BSU ; Fluorescent brightener ; Cell walls ; Chitin synthase ; Glucan synthase ; Yeast ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rylux BSU, a new fluorescent brightener from the family of 4,4′-diaminostilbene-2,2′disulfonic acid derivatives, inhibited growth and cytokinesis of the yeast Saccharomyces cerevisiae. In the presence of 0.1–1 mg/ml Rylux BSU the cells grew in clumps, had irregular shape and were larger than controls. They formed apparently normal primary septa but their secondary septa and lateral cell walls, especially those in older cells, were abnormally thick with large deposits of amorphous wall material in the periplasmic spaces all over the cell surface. Chitin content in the cell walls of cells grown in the presence of Rylux BSU was increased 2 to 5 times in comparison to that of the controls and glucan content was reduced by up to 30%. In the in vitro assays with particulate membrane fractions, Rylux BSU acted as a non-competitive inhibitor of β-1,3-glucan synthase with inhibitory constant K i=1.75 mg/ml whereas the chitin synthase was inhibited to a much lesser extent. From the difference of the effects of Rylux BSU on the synthesis of chitin in vivo and in vitro it is concluded that the brightener interacts with chitin synthase only indirectly, possibly by influencing the properties of integral plasma membrane.
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    URL: http://dx.doi.org/10.1007/BF00303590
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  • 18
    Electronic Resource
    Electronic Resource
    Kinetic studies of killer toxin K1 binding to yeast cells indicate two receptor populations (1994)
    Springer
    Archives of microbiology 162 (1994), S. 211-214 
    Details
    ISSN: 1432-072X
    Keywords: Key words     Killer toxin ; Saccharomyces cerevisiae ; Toxin binding ; Cell wall receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      A recently described new method for determination of killer toxin activity was used for kinetic measurements of K1 toxin binding. The cells of the killer sensitive strain Saccharomyces cerevisiae S6 were shown to carry two classes of toxin binding sites differing widely in their half-saturation constants and maximum binding rates. The low-affinity and high-velocity binding component (K T1 = 2.6 × 109 L.U./ml, V max1 = 0.19 s– 1) probably reflects diffusion-limited binding to cell wall receptors; the high-affinity and low-velocity component (K T2 = 3.2 × 107 L.U./ml, V max2 = 0.03 s– 1) presumably indicates the binding of the toxin to plasma membrane receptors. Adsorption of most of the killer toxin K1 to the surface of sensitive cells occured within 1 min and was virtually complete within 5 min. The amount of toxin that saturated practically all cell receptors was about 600 lethal units (L.U.) per cell of S. cerevisiae S6.
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    URL: http://dx.doi.org/10.1007/BF00314477
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  • 19
    Electronic Resource
    Electronic Resource
    Phytate dephosphorylation by free and immobilized cells ofSaccharomyces cerevisiae (1994)
    Springer
    Journal of industrial microbiology and biotechnology 13 (1994), S. 30-34 
    Details
    ISSN: 1476-5535
    Keywords: Phytate ; Saccharomyces cerevisiae ; Polyacrylamide gel ; Inositol phosphates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Saccharomyces cerevisiae in the form of baker's yeast, cells cultivated on a yeast extract-peptone-glucose medium, as well as cells immobilized in 18% (w/v) polyacrylamide gel showed the ability to hydrolyze 1.727 mM sodium phytate solution at 45°C, pH 4.6, in a stirred tank reactor. Seventy percent yield of dephosphorylation was observed after 2 h using a baker's yeast concentration of 5.8 g dry matter per 100 ml. Hydrolytic activity at 1.8–2.0 μM Pi min−1 was observed between 1st and 3rd h of the reaction in cells cultured 24 or 48 h. No inhibition by the substrate was found at sodium phytate concentrations of 0.587–1.727 mM. After 1.5 h of hydrolysis a single, well distinguished peak ofmyo-inositol-triphosphate was the main product found. By means of immobilization the stability of the biocatalyst was enhanced 3.3-fold and reached its half-life at 64 ninety-minute runs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569659
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  • 20
    Electronic Resource
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    Evolution of C6, C8 and C10 acids and their ethyl esters in cells and musts during fermentation with threeSaccharomyces cerevisiae races (1994)
    Springer
    Journal of industrial microbiology and biotechnology 13 (1994), S. 269-272 
    Details
    ISSN: 1476-5535
    Keywords: Wine ; Yeasts ; Fatty acids ; Ethyl esters ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The evolution of the cell and must contents of three short-chain fatty acids (C6, C8 and C10) and their ethyl esters during fermentations withSaccharomyces cerevisiae racescerevisiae, bayanus andcapensis were studied. The former is a fermentative yeast and the last two are ‘flor’ film yeasts. The acid concentrations in the musts increased throughout the alcoholic fermentations, and maximum cell concentrations of the fatty acids were reached after 48 h of fermentation. Maximum ester concentrations in the cells were attained after 48–72 h of fermentation. In the musts, ethyl octanoate and ethyl decanoate reached a peak also at this point, and ethyl hexanoate after 10 days. After 134 days,S. cerevisiae racecapensis formed a thick ‘flor’ film whileS. cerevisiae racebayanus developed a thin film andS. cerevisiae racecerevisiae formed no film. At this point, acid contents remained constant in the wines produced byS. cerevisiae racescerevisiae andbayanus, and decreased in those obtained with racecapensis. The ethyl ester contents tended to decrease with the exception of ethyl decanoate in the fermentations carried out byS. cerevisiae racescerevisiae andbayanus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569727
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  • 21
    Electronic Resource
    Electronic Resource
    Characterization of four new β-tubulin genes and their expression during male flower development in maize (Zea mays L.) (1994)
    Springer
    Plant molecular biology 24 (1994), S. 295-315 
    Details
    ISSN: 1573-5028
    Keywords: β-tubulin ; microtubules ; maize ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four different β-tubulin coding sequences were isolated from a cDNA library prepared from RNA from maize seedling shoots. The four genes (designated tub4, tub6, tub7 and tub8) represented by these cDNA clones together with the tub1 and tub2 genes reported previously encode six β-tubulin isotypes with 90–97.5% amino acid sequence identity. Results from phylogenetic analysis of 17 β-tubulin genes from monocot and dicot plant species indicated that multiple extant lines of β-tubulin genes diverged from a single precursor after the appearance of the two major subfamilies of α-tubulin genes described previously. Hybridization probes from the 3′ non-coding regions of six β-tubulin clones were used to quantify the levels of corresponding tubulin transcripts in different maize tissues including developing anthers and pollen. The results from these dot blot hybridization experiments showed that all of the β-tubulin genes were expressed in most tissues examined, although each gene showed a unique pattern of differential transcript accumulation. The tub1 gene showed a high level of transcript accumulation in meristematic tissues and almost no accumulation in the late stages of anther development and in pollen. In contrast, the level of tub4 transcripts was very low during early stages of male flower development but increased markedly (more than 100 times) during the development of anthers and in pollen. Results from RNAse protection assays showed that this increased hybridization signal resulted from expression of transcripts from one or two genes closely related to tub4. The tub4-related transcripts were not present in shoot tissue. Transcripts from the tub2 gene accumulated to very low levels in all tissues examined, but reached the highest levels in young anthers containing microspore mother cells. RNAse protection assays were used to measure the absolute levels of α- and β-tubulin transcripts in seedling shoot and in pollen. The α-tubulin gene subfamily I genes (tua1, tua2, tua4) contributed the great majority of α-tubulin transcripts in both shoot and pollen. Transcripts from the β-tubulin genes tub4, tub6, tub7, and tub8 were predominant in shoot, but were much less significant than the tub4-related transcripts in pollen.
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    URL: http://dx.doi.org/10.1007/BF00020169
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    Addition of A- and U-rich sequence increases the splicing efficiency of a deleted form of a maize intron (1994)
    Springer
    Plant molecular biology 24 (1994), S. 449-463 
    Details
    ISSN: 1573-5028
    Keywords: AU-rich ; intron ; maize ; splicing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant introns are generally short (〈200 nt) and AU-rich, and an elevated AU content is necessary for efficient splicing. Further, an intron in some plant genes enhances gene expression by a post-transcriptional mechanism that results in an increase of cytoplasmic mRNA. The specific intron features responsible for efficient splicing and enhancement are not well characterized in plants. Internal deletions of up to 80% of two maize introns, Adh1 intron 1 and maize actin intron 3, indicate that large segments of these introns are dispensable for normal function. However, extensive deletion (〉75%) of Adh1 intron 1 diminishes both intron enhancement and splicing efficiency. This finding suggests that there are internal sequence motifs required for intron function, and that these motifs are redundant. We attempted to repair a deletion-impaired Adh1 intron 1 variant by adding back either oligomers of defined sequence content or fragments of maize internal intron sequence. The addition of AU-rich oligomers improved splicing efficiency and in one example, a U-rich oligomer activated a cryptic 3′ splice acceptor. We also found that replacing the region proximal to the Adh1 intron 1 3′ acceptor with U-rich sequence improved splicing. We found that adding G- and C-rich oligomers did not improve intron function, but a C-rich oligomer activated a cryptic 3′ acceptor. The addition of internal intron sequence to an impaired intron improved splicing, and in one case, resulted in the activation of a cryptic 3′ acceptor. We present evidence that U-rich sequence immediately upstream of the 3′ splice junction increases splicing efficiency and contributes to, but does not uniquely specify, 3′ acceptor AG choice.
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    URL: http://dx.doi.org/10.1007/BF00024113
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    Isolation and characterization of a multienzyme complex containing DNA replicative enzymes from mitochondria ofS. cerevisiae (1994)
    Springer
    Molecular biology reports 20 (1994), S. 135-141 
    Details
    ISSN: 1573-4978
    Keywords: mitochondria ; multienzyme complex ; replication ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A 40 S multienzyme complex containing mtDNA polymerase was isolated from mitochondria ofS. cerevisiae by density gradient centrifugation and by gel filtration chromatography. Besides DNA polymerase, RNA polymerase, primase, 3′→5′ exonuclease and an ATPase activities were found to be associated with it. The presence of some of these enzymes were confirmed by Western blot. This high molecular weight multienzyme complex containing DNA has most of the attributes of a putative replisome.
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    URL: http://dx.doi.org/10.1007/BF00990545
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  • 24
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    Differential transcription of plastome-encoded genes in the mesophyll and bundle-sheath chloroplasts of the monocotyledonous NADP-malic enzyme-type C4 plants maize and Sorghum (1994)
    Springer
    Plant molecular biology 25 (1994), S. 669-679 
    Details
    ISSN: 1573-5028
    Keywords: C4 photosynthesis ; maize ; plastid gene expression ; Sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transcription of plastome-encoded genes in mesophyll and bundle-sheath chloroplasts of the monocotyledonous NADP-malic enzyme-type C4 species Zea mays L. (maize) and Sorghum bicolor (L.) Moench. was investigated. RNA accumulation and transcription were assayed starting from isolated mesophyll and bundle-sheath chloroplasts and using quantitative northern and run-on transcription analysis. Determination of the mesophyll to bundle-sheath ratios of transcript abundance in maize and Sorghum chloroplasts showed that the mRNAs of the plastome-encoded photosystem II genes analysed (psbA, psbB, psbD, psbH and psbE/F) varied from 2.5- to 4.0-fold (maize) and 3.1- to 5.2-fold (Sorghum), respectively. The rbcL transcript, in contrast, was more abundant in bundle-sheath chloroplasts of both species, about 3-fold in maize and more than 10-fold in Sorghum. On the other hand, transcripts of genes encoding the 16S ribosomal RNA (r16) and subunits of photosystem I (psaA) and the cytochrome b/f complex (petB, petA) accumulated to similar levels in both types of chloroplasts. Determination of absolute transcript levels for rbcL and psbA in chloroplasts from maize and Sorghum demonstrated that for both genes, the mesophyll to bundle-sheath differences in transcript abundance were more pronounced in Sorghum. Measurements of the transcriptional activities of rbcL and psbA showed that the transcription rate of rbcL is higher in bundle-sheath chloroplasts while psbA is more actively transcribed in mesophyll chloroplasts. The differences in the transcription rates between the two chloroplast types were again more pronounced in Sorghum, thus reflecting the differences between maize and Sorghum in the relative levels of the rbcL and psbA transcripts. However, although transcription rate and mRNA abundance are correlated, they did not exactly match one another. This indicates additional regulation of transcript abundance at the level of RNA stability.
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    URL: http://dx.doi.org/10.1007/BF00029605
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    Structure and function of selectable and non-selectable transgenes in maize after introduction by particle bombardment (1994)
    Springer
    Plant molecular biology 25 (1994), S. 951-961 
    Details
    ISSN: 1573-5028
    Keywords: Cell biology ; epigenetics ; maize ; transformation ; transgenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zea mays transformants produced by particle bombardment of embryogenic suspension culture cells of the genotype A188 × B73 and selected on kanamycin or bialaphos were characterized with respect to transgene integration, expression, and inheritance. Selection on bialaphos, mediated by thebar orpat genes, was more efficient than selection on kanamycin, mediated by thenptII gene. Most transformants contained multicopy, single locus, transgene insertion events. A transgene expression cassette was more likely to be rearranged if expression of that gene was not selected for during callus growth. Not all plants regenerated from calli representing single transformation events expressed the transgenes, and a non-selectable gene (uidA) was expressed in fewer plants than was the selectable transgene. Mendelian inheritance of transgenes consistent with transgene insertion at a single locus was observed for approximately two thirds of the transformants assessed. Transgene expression was typically, but not always, predictable in progeny plants-transgene silencing, as well as poor transgene transmission to progeny, was observed in some plant lines in which the parent plants had expressed the transgene.
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    URL: http://dx.doi.org/10.1007/BF00014669
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    Partial sequencing and mapping of clones from two maize cDNA libraries (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1085-1101 
    Details
    ISSN: 1573-5028
    Keywords: cDNA clones ; EST sequencing ; maize ; RFLP mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As one component of a maize genome project, we report the analysis of a number of randomly selected cDNAs, by a combination of measuring mRNA expression, ‘single-pass’ sequencing (SPS), and genome mapping. Etiolated seedling (490) and membrane-free polysomal endosperm cDNA clones (576) were evaluated for their transcription levels by hybridizing with a probe prepared from total mRNA and categorized as corresponding to abundantly or rarely expressed mRNAs and as either constitutive or tissue-specific. A total of 313 clones from the two libraries were submitted to ‘single-pass’ sequencing from the presumed 5′ end of the mRNA and the nucleotide sequence compared with the GenBank database. About 61% of the clones showed no significant similarities within GenBank, 14% of the clones exhibited a high degree of similarity, while the remaining 25% exhibited a lesser degree of similarity. The chromosomal location of more than 300 clones was determined by RFLP mapping using standard populations. The results demonstrate that a combination of analyses provides synergistic information in eventually deducing the actual function of these types of clones.
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    URL: http://dx.doi.org/10.1007/BF00040691
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    Cloning of an Arabidopsis thaliana cDNA coding for farnesyl diphosphate synthase by functional complementation in yeast (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1867-1873 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis thaliana ; cDNA ; complementation ; erg20-2 yeast mutant ; farnesyl diphosphate synthase ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA encoding farnesyl diphosphate synthase, an enzyme that synthesizes C15 isoprenoid diphosphate from isopentenyl diphosphate and dimethylallyl diphosphate, was cloned from an Arabidopsis thaliana cDNA library by complementation of a mutant of Saccharomyces cerevisiae deficient in this enzyme. The A. thaliana cDNA was also able to complement the lethal phenotype of the erg20 deletion yeast mutant. As deduced from the full-length 1.22 kb cDNA nucleotide sequence, the polypeptide contains 343 amino acids and has a relative molecular mass of 39689. The predicted amino acid sequence presents about 50% identity with the yeast, rat and human FPP synthases. Southern blot analyses indicate that A. thaliana probably contains a single gene for farnesyl diphosphate synthase.
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    URL: http://dx.doi.org/10.1007/BF00019499
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    Non-systemic expression of a stress-responsive maize polyubiquitin gene (Ubi-1) in transgenic rice plants (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1007-1012 
    Details
    ISSN: 1573-5028
    Keywords: cell cycle ; maize ; non-systemic expression ; polyubiquitin gene ; stress response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used the promoter, 1st exon and 1st intron of the maize polyubiquitin gene (Ubi-1) for rice transformation experiments and revealed the characteristic expression of Ubi-1 gene: (1) Ubi-1 gene is not regulated systemically but rather individual cells respond independently to the heat or physical stress; (2) Ubi-1 gene changes its tissue-specific expression in response to stress treatment; (3) the expression of Ubi-1 gene is dependent on cell cycle.
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    URL: http://dx.doi.org/10.1007/BF00028868
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  • 29
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    Isolation and characterisation of a maize cDNA that complements a 1-acyl sn-glycerol-3-phosphate acyltransferase mutant of Escherichia coli and encodes a protein which has similarities to other acyltransferases (1994)
    Springer
    Plant molecular biology 26 (1994), S. 211-223 
    Details
    ISSN: 1573-5028
    Keywords: maize ; 1-acyl-sn-glycerol-3-phosphate acyltransferase ; complementation cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We selected cDNA plasmid clones that corrected the temperature-sensitive phenotype of Escherichia coli strain JC201, which is deficient in 1-acyl-sn-glycerol-3-phosphate acyltransferase activity. A plasmid-based maize endosperm cDNA library was used for complementation and a plasmid that enabled the cells to grow at 44°C on ampicillin was isolated. Addition of this plasmid (pMAT1) to JC201 restored 1-acyl-sn-glycerol-3-phosphate acyltransferase activity to the cells. Total phospholipid labelling showed that the substrate for the enzyme, lysophosphatidic acid, accumulated in JC201 and was further metabolised to phosphatidylethanolamine in complemented cells. Membranes isolated from such cells were able to convert lysophosphatidic acid to phosphatidic acid in acyltransferase assays. The cDNA insert of pMAT1 contains one long open reading frame of 374 amino acids which encodes a protein of relative molecular weight 42 543. The sequence of this protein is most similar to SLC1, which is thought to be able to acylate glycerol at the sn-2 position during synthesis of inositol-containing lipids. Homologies between the SLC1 protein, the 1-acyl-sn-glycerol-3-phosphate acyltransferase of E. coli (PlsC) and the maize ORF were found with blocks of conserved amino acids, whose spacing was conserved between the three proteins, identifiable.
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    URL: http://dx.doi.org/10.1007/BF00039533
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    In vivo analysis of intron processing using splicing-dependent reporter gene assays (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1785-1795 
    Details
    ISSN: 1573-5028
    Keywords: intron ; maize ; splicing ; vectors ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanisms of intron recognition and processing have been well-studied in mammals and yeast, but in plants the biochemistry of splicing is not known and the rules for intron recognition are not clearly defined. To increase understanding of intron processing in plants, we have constructed new pairs of vectors, pSuccess and pFail, to assess the efficiency of splicing in maize cultured cells. In the pFail series we use translation of pre-mRNA to monitor the amount of unspliced RNA. We inserted an ATG codon in the Bz2 (Bronze-2) intron in frame with luciferase: this construct will express luciferase activity only when splicing fails. In the pSuccess series the spliced message is monitored by inserting an ATG upstream of the Bz2 intron in frame with luciferase: this construct will express luciferase activity only when splicing succeeds. We show here, using both the wild-type Bz2 intron and the same intron with splice site mutations, that the efficiency of splicing can be estimated by the ratio between the luciferase activities of the vector pairs. We also show that mutations in the unique U-rich motif inside the intron can modulate splicing. In addition, a GC-rich insertion in the first exon increases the efficiency of splicing, suggesting that exons also play an important role in intron recognition and/or processing.
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    URL: http://dx.doi.org/10.1007/BF00019492
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    Molecular and physiological evaluation of transgenic tobacco plants expressing a maize phosphoenolpyruvate carboxylase gene under the control of the cauliflower mosaic virus 35S promoter (1994)
    Springer
    Transgenic research 3 (1994), S. 287-296 
    Details
    ISSN: 1573-9368
    Keywords: C4-plant ; maize ; phosphoenolpyruvate carboxylase ; quantum yield ; transgenic tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of maize (Zea mays) phosphoenolpyruvate carboxylase (PEPC) gene constructs in transgenic tobacco plants (Nicotiana tabacum) was studied. Where transcription was under the control of a CaMV 35S promoter, maize PEPC transcripts of the correct size were detected. Western blot analysis indicated that the transgenic plants contained about twice as much PEPC as non-transformed plants. Furthermore, the enzymatic activity of PEPC in the leaves of these transgenic plants was up to twice as high as that in non-transformed plants. Two forms of PEPC with different kinetic properties were identified in leaf extracts of the transgenic plants: one form (the maize isoform) gave a high apparentK m value for phosphoenolpyruvate (PEP) and a high maximum activity, and the other (the tobacco isoform) exhibited a low apparentK m value for PEP and a low maximum activity. These biochemical differences resulted in several significant physiological changes in the transgenic plants: (1) the growth rate of the transgenic plants was lower than that of non-transgenic plants: (2) chlorophyll content per leaf area was relatively lower in the transgenic plants; and (3) the quantum yield of photosynthesis in the transgenic plants was not affected by changes in leaf temperature.
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    URL: http://dx.doi.org/10.1007/BF01973588
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    Cerulenin-resistant mutants of Saccharomyces cerevisiae with an altered fatty acid synthase gene (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 90-96 
    Details
    ISSN: 1617-4623
    Keywords: Cerulenin ; Saccharomyces cerevisiae ; Fatty acid synthase ; β-Ketoacyl synthase ; Drug resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cerulenin, an antifungal antibiotic produced by Cephalosporium caerulens, is a potent inhibitor of fatty acid synthase in various organisms, including Saccharomyces cerevisiae. The antibiotic inhibits the enzyme by binding covalently to the active center cysteine of the condensing enzyme domain. We isolated 12 cerulenin-resistant mutants of S. cerevisiae following treatment with ethyl methanesulfonate. The mechanism of cerulenin resistance in one of the mutants, KNCR-1, was studied. Growth of the mutant was over 20 times more resistant to cerulenin than that of the wild-type strain. Tetrad analysis suggested that all mutants mapped at the same locus, FAS2, the gene encoding the α subunit of the fatty acid synthase. The isolated fatty acid synthase, purified from the mutant KNCR-1, was highly resistant to cerulenin. The cerulenin concentration causing 50% inhibition (IC50) of the enzyme activity was measured to be 400 μM, whereas the IC50 value was 15 μM for the enzyme isolated from the wild-type strain, indicating a 30-fold increase in resistance to cerulenin. The FAS2 gene was cloned from the mutant. Sequence replacement experiments suggested that an 0.8 kb EcoRV-HindIII fragment closely correlated with cerulenin resistance. Sequence analysis of this region revealed that the GGT codon encoding Gly-1257 of the FAS2 gene was altered to AGT in the mutant, resulting in the codon for Ser. Furthermore, a recombinant FAS2 gene, in which the 0.8 Kb EcoRV-HindIII fragment of the wild-type FAS2 gene was replaced with the same region from the mutant, when introduced into FAS2-defective S. cerevisiae complemented the FAS2 pheno-type and showed cerulenin resistance. These data indicate that one amino acid substitution (Gly → Ser) in the α subunit of fatty acid synthase is responsible for the cerulenin resistance of the mutant KNCR-1.
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    Positive and negative transcriptional regulation by the yeast GAL11 protein depends on the structure of the promoter and a combination of cis elements (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 301-312 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Transcriptional regulation ; Chromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract GAL11 was first identified as a gene required for full expression of some galactose-inducible genes that are activated by GAL4, and it was subsequently shown to be necessary for full expression of another set of genes activated by RAP1/GRFl/TUF. Genetic analysis suggests that GAL11 functions as a coactivator, mediating the interaction of sequence-specific activators with basal transcription factors. To test this hypothesis, we first tried to identify functional domains by deletion analysis and found that the 866–910 region is indispensable for function. Using reporters bearing various upstream activating sequences (UAS) and different core promoter structures, we show that the involvement of GAL11 in transcriptional activation varies with the target promoter and the particular combination of cis elements. Gel electrophoresis in the presence of chloroquine shows that GAL11 affects the chromatin structure of a circular plasmid. Based on these findings, the role of GAL 11 in regulation of transcription, including an alteration in chromatin structure, is discussed.
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    URL: http://dx.doi.org/10.1007/BF00290110
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    SCM2, a tryptophan permease in Saccharomyces cerevisiae, is important for cell growth (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 260-268 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Amino acid permeases ; Transport ; Tryptophan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract SCM2, a novel gene encoding a yeast tryptophan permease, was cloned as a high-copy-number suppressor of cse2-1. The cse2-1 mutation causes cold sensitivity, temperature sensitivity and chromosome missegregation. However, only the cold-sensitive phenotype of cse2-1 cells is suppressed by SCM2 at high copy. SCM2 is located on the left arm of yeast chromosome XV, adjacent to SUP3 and encodes a 65 kDa protein that is highly homologous to known amino acid permeases. Four out of five disrupted scm2 alleles (scm2Δ1-Δ4) cause slow growth, whereas one disrupted allele (scm2Δ5) is lethal. Cells with both the scm2Δ1 and trp1-Δ101 mutations exhibit a synthetic cold-sensitive phenotype and grow much more slowly at the permissive temperature than cells with a single scm2Δ1 or trp1-Δ101 mutation. A region of the predicted SCM2 protein is identical to the partial sequence recently reported for the yeast tryptophan permease TAP2, indicating that SCM2 and TAP2 probably encode the same protein.
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    The Saccharomyces cerevisiae SGE1 gene product: a novel drug-resistance protein within the major facilitator superfamily (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 287-294 
    Details
    ISSN: 1617-4623
    Keywords: Drug sensitivity ; Saccharomyces cerevisiae ; Major facilitator superfamily ; Drug expulsion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several pleiotropic drug sensitivities have been described in yeast. Some involve the loss of putative drug efflux pumps analogous to mammalian P-glycoproteins, others are caused by defects in sterol synthesis resulting in higher plasma membrane permeability. We have constructed a Saccharomyces cerevisiae strain that exhibits a strong crystal violet-sensitive phenotype. By selecting cells of the supersensitive strain for normal sensitivity after transformation with a wild-type yeast genomic library, a complementing 10-kb DNA fragment was isolated, a 3.4-kb subfragment of which was sufficient for complementation. DNA sequence analysis revealed that the complementing fragment comprised the recently sequenced SGE1 gene, a partial multicopy suppressor of gal11 mutations. The supersensitive strain was found to be a sge1 null mutant. Overexpression of SGE1 on a high-copy-number plasmid increased the resistance of the supersensitive strain. Disruption of SGE1 in a wild-type strain increased the sensitivity of the strain. These features of the SGE1 phenotype, as well as sequence homologies of SGE1 at the amino acid level, confirm that the Sge1 protein is a member of the drug-resistance protein family within the major facilitator superfamily (MFS).
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    PDR3, a new yeast regulatory gene, is homologous toPDR1 and controls the multidrug resistance phenomenon (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 501-511 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Transcription factor ; Zinc finger ; Multidrug resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheSaccharomyces cerevisiae PDR3 gene, located near the centromere of chromosome II, has been completely sequenced and characterised. Mutationspdr3-1 andpdr3-2, which confer resistance to several antibiotics can be complemented by a wild-type allele of the PDR3 gene. The sequence of the wild-typePDR3 gene revealed the presence of a long open reading frame capable of encoding a 976-amino acid protein. The protein contains a single Zn(II)2Cys6 binuclear-type zinc finger homologous to the DNA-binding motifs of other transcriptional activators from lower eukaryotes. Evidence that the PDR3 protein is a transcriptional activator was provided by demonstrating that DNA-bound LexA-PDR3 fusion proteins stimulate expression of a nearby promoter containing LexA binding sites. The use of LexA-PDR3 fusions revealed that the protein contains two activation domains, one localised near the N-terminal, cysteine-rich domain and the other localised at the C-terminus. The salient feature of the PDR3 protein is its similarity to the protein coded byPDR1, a gene responsible forpleiotropicdrugresistance. The two proteins show 36% amino acid identity over their entire length and their zinc finger DNA-binding domains are highly conserved. The fact that the absence of both PDR1 and PDR3 (simultaneous disruption of the two genes) enhances multidrug sensitivity strongly suggests that the two transcriptional factors have closely related functions.
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    Two adjacent nuclear genes, ISF1 and NAM7/UPF1, cooperatively participate in mitochondrial functions in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 49-56 
    Details
    ISSN: 1617-4623
    Keywords: Nuclear suppressor gene ; Mitochondrial functions ; Glucose repression ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We previously isolated a nuclear 5.7 kb genomic fragment carrying the NAM7/UPF1 gene, which is able to suppress mitochondrial splicing deficiency when present in multiple copies. We show here that an immediately adjacent gene ISF1 (Increasing Suppression Factor) increases the efficiency of the NAM7/UPF1 suppressor activity. The ISF1 gene has been independently isolated as the MBR3 gene and comparison of the ISF1 predicted protein sequence with data libraries revealed a significant similarity with the MBRI yeast protein. The ISF1 and NAM7 genes are transcribed in the same direction, and RNase mapping allowed the precise location of their termini within the intergenic region to be determined. The ISF1 gene is not essential for cell viability or respiratory growth. However as for many mitochondrial genes, ISF1 expression is sensitive to fermentative repression; in contrast expression of the NAM7 gene is unaffected by glucose. We propose that ISF1 could influence the NAM7/UPF1 function, possibly at the level of mRNA turnover, thus modulating the expression of nuclear genes involved in mitochondrial biogenesis.
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    URL: http://dx.doi.org/10.1007/BF00277347
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    Characterization of the Saccharomyces cerevisiae nuclear gene CYB3 encoding a cytochrome b polypeptide of respiratory complex II (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 708-716 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Mitochondria ; Cytochrome b ; Complex II ; HAP2/3/4
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Computer-assisted structural analysis of the predicted product of the previously described open reading frame (ORF) YKL4 located on the left arm of chromosome XI of Saccharomyces cerevisiae revealed a high degree of similarity (〉50%) to bovine cytochrome b 560, the sdhC polypeptide of the Escherichia coli succinate dehydrogenase (SDH) complex and the protein specified by ORF137 located on the chloroplast DNA of Marchantia polymorpha. Disruption of the yeast gene severely impaired mitochondrial function, while Northern analysis showed it to be subject to catabolite repression. Deletion analysis of the CYB3 promoter identified a single HAP2/3/4-binding element that is necessary and sufficient for carbon source-dependent transcriptional regulation. These experiments also suggested the presence of additional, as yet unidentified, transcriptional control elements, both negative and positive. Taken together, these data lead us to conclude that the CYB3 gene encodes the yeast homolog of the bovine cytochrome b 560 component of complex II of the mitochondrial electron transport chain.
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    URL: http://dx.doi.org/10.1007/BF00283426
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    Functional analysis of the zinc cluster domain of the CYP1 (HAP1) complex regulator in heme-sufficient and heme-deficient yeast cells (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 699-707 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; CYP1(HAP1) protein ; Electron transport ; Oxygen and heme regulation ; Trans regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract CYP1 determines the expression of several genes whose transcription is heme-dependent in yeast. It exerts regulatory functions even in the absence of heme, usually considered to be its effector. It mediates both positive and negative effects, depending on the target gene and on the redox state of the cell. In the presence of heme, it binds through a cysteine-rich domain in which a histidine residue occupies the position of the sixth and essential cysteine of the otherwise classical zinc cluster DNA-binding domain exemplified by GAL4. We constructed specific missense mutations in the potential CYP1 zinc cluster domain by site-directed mutagenesis and looked for regulatory effects of the mutated proteins under specific physiological conditions. We show that CYP1 does belong to the zinc cluster regulatory family since a sixth essential cysteine residue is indeed present, albeit at a modified position when compared to the consensus sequence. We also show that the amino acid preceding the first cysteine residue of the DNA-binding domain critically affects the efficiency of regulation both in the presence and in the absence of heme: mutations known to affect DNA binding under heme-sufficient conditions also affect regulation under heme-deficient conditions. We therefore surmise that regulation under hemedeficient conditions is dependent upon DNA binding.
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    URL: http://dx.doi.org/10.1007/BF00283425
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    MBR1 and MBR3, two related yeast genes that can suppress the growth defect of hap2, hap3 and hap4 mutants (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 575-583 
    Details
    ISSN: 1617-4623
    Keywords: Multicopy suppressors ; HAP2/3/4 activation complex ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two new yeast genes, named MBR1 and MBR3, were isolated as multicopy suppressors of the growth defect of a strain lacking the HAP2 transcriptional activator. Both genes when overexpressed can also suppress the growth defect of hap3 and hap4 null mutants. However, overexpression of MBRI cannot substitute for the HAP2/3/4 complex in activation of the CYC1 gene. Nucleotide sequencing of MBR1 and MBR3 revealed that these two genes encode serine-rich, hydrophilic proteins with regions of significant homology. The functional importance of one of these conserved regions was shown by mutagenesis. Disruption of MBR1 leads to a partial growth defect on glycerol medium. Disruption of MBR3 has no major effect but the double disruptant shows a synthetic phenotype suggesting that the MBR1 and MBR3 gene products participate in common function.
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    URL: http://dx.doi.org/10.1007/BF00284206
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    Identification of a sporulation-specific promoter regulating divergent transcription of two novel sporulation genes in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 661-672 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Meiosis Sporulation ; Divergent promoter ; Developmental regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Promoters that control gene expression in Saccharomyces cerevisiae only in a sporulation-specific manner have previously been isolated from a genomic yeast DNA library fused to a promoterless Escherichia coli lacZ gene. Two novel sporulation-specific genes, SPS18 and SPS19, were isolated using this technique. These genes are divergently controlled by the same promoter but with SPS18 expressed at four times the level of SPS19. Deletion analysis has shown that the promoter elements that exert sporulation control on each of the genes overlap, having a common 25 bp sequence located within the intergenic region. SPS18 encodes a 34-KDa protein of 300 amino acids that contains a putative zinc-binding domain and a region of highly basic residues that could target the protein to the nucleus. SPS19 encodes a 31-KDa protein of 295 amino acids, which has a peroxisomal targeting signal (SKL) at its C terminus; this protein belongs to the family of non-metallo short-chain alcohol dehydrogenases. A null mutation deleting the intergenic promoter prevented expression of both genes, and when homozygous in diploids, reduced the extent of sporulation four-fold; the spores that did form were viable, but failed to become resistant to ether, and were more sensitive to lytic enzymes. This phenotype reflects a defect in spore wall maturation, indicating that the product of at least one of the genes functions during the process of spore wall formation. Therefore these genes belong to the class of late sporulation-specific genes that are sequentially activated during the process of meiosis and spore formation.
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    Use of synthetic lethal mutants to clone and characterize a novel CTP synthetase gene in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 431-439 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Duplicate genes ; Synthetic lethal mutants ; CTP synthetase ; Pyrimidine biosynthetic pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the pyrimidine biosynthetic pathway, CTP synthetase catalyses the conversion of uridine 5′-triphosphate (UTP) to cytidine 5′-triphosphate (CTP). In the yeast Saccharomyces cerevisiae, the URA7 gene encoding this enzyme was previously shown to be nonessential for cell viability. The present paper describes the selection of synthetic lethal mutants in the CTP biosynthetic pathway that led us to clone a second gene, named URA8, which also encodes a CTP synthetase. Comparison of the predicted amino acid sequences of the products of URA7 and URA8 shows 78% identity. Deletion of the URA8 gene is viable in a haploid strain but simultaneous presence of null alleles both URA7 and URA8 is lethal. Based on the codon bias values for the two genes and the intracellular concentrations of CTP in strains deleted for one of the two genes, relative to the wild-type level, URA7 appears to be the major gene for CTP biosynthesis. Nevertheless, URA8 alone also allows yeast growth, at least under standard laboratory conditions.
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    URL: http://dx.doi.org/10.1007/BF00281793
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    Temperature-sensitive mutants of hsp82 of the budding yeast Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 517-527 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; HSP82 ; Random in vitro mutagenesis ; Temperature-sensitive mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The budding yeast Saccharomyces cerevisiae has two HSP90-related genes per haploid genome, HSP82 and HSC82. Random mutations were induced in vitro in the HSP82 gene by treatment of the plasmid with hydroxylamine. Four temperature-sensitive (ts) mutants and one simultaneously is and cold-sensitivie (cs) mutant were then selected in a yeast strain in which HSC82 had previously been disrupted. The mutants were found to have single base changes in the coding region, which caused single amino acid substitutions in the HSP82 protein. All of these mutations occurred in amino acid residues that are well conserved among HSP90-related proteins of various species from Escherichia coli to human. Various properties including cell morphology, macromolecular syntheses and thermosensitivity were examined in each mutant at both the permissive and nonpermissive temperatures. The mutations in HSP82 caused pleiotropic effects on these properties although the phenotypes exhibited at the nonpermissive temperature varied among the mutants.
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    The hypo-osmolarity-sensitive phenotype of the Saccharomyces cerevisiae hpo2 mutant is due to a mutation in PKC1, which regulates expression of β-glucanase (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 641-648 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Cell wall ; Protein kinase C ; β-Glucanase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To obtain more information about the cell wall organization of Saccharomyces cerevisiae, we have developed a novel screening system to obtain cell wall-defective mutants, using a density gradient centrifugation method. Nine hypo-osmolarity-sensitive mutants were classified into two complementation groups, hpo1 and hpo2. Phase contrast microscopic observation showed that mutant cells bearing lesions at either locus became abnormally large. A gene that complemented the mutant phenotype of hpo2 was cloned and sequenced. This gene turned out to be identical to PKC1, which encodes the yeast homologue of mammalian protein kinase C. Complementation tests with pkc1Δ showed that hpo2 is allelic to pkc1. To study the reason for the fragility of hpo2 cells, cell wall was isolated and the glucan was analyzed. The amount of alkali, acid-insoluble glucan, which is responsible for the rigidity of the cell wall, was reduced to about 30% that of the wild-type cell and this may be the major cause of the fragility of the hpo2 mutant cell. Analysis of total wall proteins in hpo2 mutant cells on SDS-polyacrylamide gels revealed that a 33 kDa protein was overproduced two- to threefold relative to the wild-type level. This 33 kDa protein was identified as a β-glucanase, encoded by BGL2. Disruption of BGL2 in the hpo2 mutant partially rescued the growth rate defect. This suggests that the PKC1 kinase cascade regulates BGL2 expression negatively and overproduction of the β-glucanase is partially responsible for the growth defect. Since the bgl2 disruption did not rescue the hypo-osmolarty-sensitive phenotype of the hpo2 mutant, PKC1 must negatively regulate other enzymes involved in the biosynthesis and metabolism of the cell wall.
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    Polyubiquitin gene expression contributes to oxidative stress resistance in respiratory yeast (Saccharomyces cerevisiae) (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 358-362 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Oxidative stress ; High temperature viability ; Ubiquitin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract UBI4, the polyubiquitin gene of Saccharomyces cerevisiae, is expressed at a low level in vegetative cells, yet induced strongly in response to starvation, cadmium, DNA-damaging agents and heat shock. UBI4 is also expressed at a higher basal level in cells growing by respiration as compared to glucose-repressed cells growing by fermentation. This higher UBI4 expression of respiratory cultures probably helps to counteract the greater oxidative stress of respiratory growth. The effects of inactivating UBI4 on high temperature viability are more marked with respiratory cultures. Also loss of UBI4 leads to a considerably increased rate of killing of respiring cells by hydrogen peroxide, whereas the same gene inactivation has relatively little effect on the peroxide sensitivity of cells in which mitochondrial functions are repressed. This is the first study to reveal that ubiquitin levels in cells can influence their ability to withstand oxidative stress.
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    Open reading frames in the antisense strands of genes coding for glycolytic enzymes in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 363-368 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Glycolysis ; Phosphoglucose isomerase ; Antisense ; Double-strand coding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Open reading frames longer than 300 bases were observed in the antisense strands of the genes coding for the glycolytic enzymes phosphoglucose isomerase, phosphoglycerate mutase, pyruvate kinase and alcohol dehydrogenase I. The open reading frames on both strands are in codon register. It has been suggested that proteins coded in codon register by complementary DNA strands can bind to each other. Consequently, it was interesting to investigate whether the open reading frames in the antisense strands of glycolytic enzyme genes are functional. We used oligonucleotide-directed mutagenesis of the PGI1 phosphoglucose isomerase gene to introduce pairs of closely spaced base substitutions that resulted in stop codons in one strand and only silent replacements in the other. Introduction of the two stop codons into the PGI1 sense strand caused the same physiological defects as already observed for pgi1 deletion mutants. No detectable effects were caused by the two stop codons in the antisense strand. A deletion that removed a section from − 31 by to + 109 by of the PGI1 gene but left 83 bases of the 3′ region beyond the antisense open reading frame had the same phenotype as a deletion removing both reading frames. A similar pair of deletions of the PYK1 gene and its antisense reading frame showed identical defects. Our own Northern experiments and those reported by other authors using double-stranded probes detected only one transcript for each gene. These observations indicate that the antisense reading frames are not functional. On the other hand, evidence is provided to show that the rather long reading frames in the antisense strands of these glycolytic enzyme genes could arise from the strongly selective codon usage in highly expressed yeast genes, which reduces the frequency of stop codons in the antisense strand.
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    The archaebacterial membrane protein bacterio-opsin is expressed and N-terminally processed in the yeast Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 183-188 
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    ISSN: 1617-4623
    Keywords: Bacterio-opsin ; Expression ; Yeast ; Saccharomyces cerevisiae ; Membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The bop gene codes for the membrane protein bacterio-opsin (BO), which on binding all-trans-retinal, constitutes the light-driven proton pump bacteriorhodopsin (BR) in the archaebacterium Halobacterium salinarium The designation H. salinarium instead of the former designation H. halobium is used throughout this paper following the classification of Tindall (1992) . This gene was cloned in a yeast multi-copy vector and expressed in Saccharomyces cerevisiae under the control of the constitutive ADH1 promoter. Both the authentic gene and a modified form lacking the precursor sequence were expressed in yeast. Both proteins are incorporated into the membrane in S. cerevisiae. The presequence is thus not required for membrane targeting and insertion of the archaebacterial protein in budding yeast, or in the fission yeast Schizosaccharomyces pombe, as has been shown previously. However, in contrast to S. pombe transformants, which take on a reddish colour when all-trans-retinal is added to the culture medium as a result of the in vivo regeneration of the pigment, S. cerevisiae cells expressing BO do not take on a red colour. The precursor of BO is processed to a protein identical in size to the mature BO found in the purple membrane of Halobacterium. The efficiency of processing in S. cerevisiae is dependent on growth phase, as well as on the composition of the medium and on the strain used. The efficiency of processing of BR is reduced in S. pombe and in a retinal-deficient strain of H. salinarium, when retinal is present in the medium.
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    Heterospecific cloning of Arabidopsis thaliana cDNAs by direct complementation of pyrimidine auxotrophic mutants of Saccharomyces cerevisiae. I. Cloning and sequence analysis of two cDNAs catalysing the second, fifth and sixth steps of the de novo pyrimidine biosynthesis pathway (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 23-32 
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    ISSN: 1617-4623
    Keywords: Arabidopsis thaliana ; Saccharomyces cerevisiae ; Complementation ; Aspartate transcarbamylase ; Orotate phosphoribosyl transferase ; Orotidine-5′-phosphate decarboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An Arabidopsis thaliana cDNA library was used to complement Saccharomyces cerevisiae pyrimidine auxotrophic mutants. Mutants in all but one (carbamylphosphate synthetase) of the six steps in the de novo pyrimidine biosynthetic pathway could be complemented. We report here the cloning, sequencing and computer analysis of two cDNAs encoding the aspartate transcarbamylase (ATCase; EC 2.1.3.2) and orotate phosphoribosyltransferase-orotidine-5′-phosphate decarboxylase (OPRTase-OMP-decase; EC 2.4.2.10, EC 4.1.1.23) enzymes. These results confirm the presence in A. thaliana of a bifunctional gene whose product catalyses the last two steps of the pyrimidine biosynthetic pathway, as previously suggested by biochemical studies. The ATCase encoding cDNA sequence (PYRB gene) shows an open reading frame (ORF) of 1173 by coding for 390 amino acids. The cDNA encoding OPRTase-OMPdecase (PYRE-F gene) shows an ORF of 1431 by coding for 476 amino acids. Computer analysis of the deduced amino acid sequences of both cDNAs shows the expected high similarity with the ATCase, ornithine transcarbamylase (OTCase; EC 2.1.3.3), OPRTase and OMPdecase families. This heterospecific cloning approach increases our understanding of the genetic organization and interspecific functional conservation of the pyrimidine biosynthetic pathway and underlines its usefulness as a model for evolutionary studies.
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    Sequence of the HAP3 transcription factor of Kluyveromyces lactis predicts the presence of a novel 4-cysteine zinc-finger motif (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 96-106 
    Details
    ISSN: 1617-4623
    Keywords: HAP3 ; Saccharomyces cerevisiae ; Kluyveromyces lactis ; Zinc finger ; Carbon source regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Kluyveromyces lactis homologue of the Saccharomyces cerevisiae HAP3 gene was isolated by functional complementation of the respiratory-deficient phenotype of the S. cerevisiae hap3::HIS4 strain SHY40. The KlHAP3 gene encodes a protein of 205 amino acids, of which the central B-domain of 90 residues is highly homologous to HAP3 counterparts of S. cerevisiae and higher eukaryotes. The protein contains a novel 4-cysteine zinc-finger motif and we propose by analogy that all other homologous HAP3 proteins contain the same motif, with the position containing the third cysteine being occupied by a serine residue. In contrast to the situation in S. cerevisiae, disruption of the KlHAP3 gene in K. lactis does not result in a respiratory-deficient phenotype and the growth of the null strain is indistinguishable from wild type. There is also no effect on the expression of the carbon source-regulated KlCYC1 gene, suggesting either a different role for the HAP2/3/4 complex, or the existence of a different mechanism of carbon source regulation. Sequence verification of the S. cerevisiae HAP3 locus reveals that, just as in K. lactis, a long open reading frame (ORF) is present upstream of the HAP3 gene. These highly homologous ORFs are predicted to have at least eight membrane-spanning fragments, but do not show significant homology to any known sequence present in databases. The ScORFX gene is transcribed in the opposite direction to ScHAP3, but, in contrast to an earlier report by Hahn et al. (1988), the transcripts of the two genes do not overlap. The model proposed by these authors, in which the ScHAP3 gene is regulated by an anti-sense non-coding mRNA, is therefore not correct.
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    Expression of human poly(ADP-ribose) polymerase in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 686-693 
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    ISSN: 1617-4623
    Keywords: Yeast ; Saccharomyces cerevisiae ; Poly(ADP-ribose) polymerase ; DNA repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The coding sequence for human poly(ADP-ribose) polymerase was expressed inducibly in Saccharomyces cerevisiae from a low-copy-number plasmid vector. Cell free extracts of induced cells had poly(ADPribose) polymerase activity when assayed under standard conditions; activity could not be detected in non-induced cell extracts. Induced cells formed poly(ADP-ribose) in vivo, and levels of these polymers increased when cells were treated with the alkylating agent N-methyl-N′-nitro-N-nitrosoguanidine (MNNG). The cytotoxicity of this agent was increased in induced cells, and in vivo labelling with [3H]adenine further decreased their viability. Increased levels of poly(ADP-ribose) found in cells treated with the alkylating agent were not accompanied by lowering of the NAD concentration.
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    A new yeast gene, HTR1, required for growth at high temperature, is needed for recovery from mating pheromone-induced G1 arrest (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 107-116 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; ts mutant ; Recovery ; HTR1 ; MCS1/SSD1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new temperature-sensitive mutant of Saccharomyces cerevisiae was isolated. Arrested cells grown at the nonpermissive temperature were of dumb-bell shape and contained large vacuoles. A DNA fragment was cloned based on its ability to complement this temperature sensitivity. The HTR1 gene encodes a putative protein of 93 kDa without significant homology to any known proteins. The gene was mapped between ade5 and lys5 on the left arm of chromosome VII. The phenotype of the gene disruptant appeared to be strain-specific; disruption of the gene in strain W303 caused the cells to become temperature sensitive. The arrested phenotype here was similar to that of the original is mutant and cells in G2/M phase predominated at high temperature. Another disruptant in a strain YPH background grew slowly at high temperature due to slow progression through G2/M phase, and morphologically abnormal (elongated) cells accumulated. A single-copy suppressor that alleviated the temperature-sensitive defects in both strains was identified as MCS1/SSD1. The wild-type strains W303 and YPH are known to carry defective MCS1/SSD1 alleles; hence HTR1 may function redundantly with MCS1/SSD1 to suppress the temperature-sensitive phenotypes. In addition, based on a halo bioassay, the disruptant strains appeared to be defective in recovery from, or adaptive response to G1 arrest mediated by mating pheromone, even at the permissive temperature. Thus the gene has at least two functions and is designated HTR1 (required for high temperature growth and recovery from G1 arrest induced by mating pheromone).
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    Two subclasses of guanine exchange factor (GEF) domains revealed by comparison of activities of chimeric genes constructed from CDC25, SDC25 and BUD5 in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 167-176 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Cell cycle ; Bud site selection ; Guanine exchange factor ; Ras
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Guanine Exchange Factor (GEF) activity for Ras proteins has been associated with a conserved domain in Cdc25p, Sdc25p in Saccharomyces cerevisiae and several other proteins recently found in other eukaryotes. We have assessed the structure-function relationships between three different members of this family in S. cerevisiae, Cdc25p, Sdc25p and Bud5p. Cdc25p controls the Ras pathway, whereas Bud5p controls bud site localization. We demonstrate that the GEF domain of Sdc25p is closely related to that of Cdc25p. We first constructed a thermosensitive allele of SDC25 by specifically altering amino acid positions known to be changed in the cdc25-1 mutation. Secondly, we constructed three chimeric genes from CDC25 and SDC25, the products of which are as active in the Ras pathway as are the wild-type proteins. In contrast, similar chimeras made between CDC25 and BUD5 lead to proteins that are inactive both in the Ras and budding control pathways. This difference in the ability of chimeric proteins to retain activity allows us to define two subclasses of structurally different GEFs: Cdc25p and Sdc25p are Ras-specific GEFs, and Bud5p is a putative GEF for the Rsr1/Bud1 Rap-like protein.
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    Inactivation of SSM4, a new Saccharomyces cerevisiae gene, suppresses mRNA instability due to rna14 mutations (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 323-333 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; mRNA decay Poly(A) tail ; Ty transposition ; SSM4 gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Decay rates of mRNAs depend on many elements and among these, the role of the poly(A) tail is now well established. In the yeast Saccharomyces cerevisiae, thermosensitive mutations in two genes, RNA14 and RNA15, result in mRNAs having shorter poly(A) tails and reduced half-life. To identify other components interacting in the same process, we have used a genetic approach to isolate mutations that suppress the thermosensitivity of an rna14 mutant strain. Mutations in a single locus, named SSM4, not only suppress the cell growth phenotype but also the mRNA instability and extend the short mRNA poly(A) tails. The frequency of appearance and the recessive nature of these mutations suggested that the suppressor effect was probably due to a loss of function. We failed to clone the SSM4 gene directly by complementation, owing to its absence from gene banks; it later emerged that the gene is toxic to Escherichia coli, but we have nevertheless been able to clone the SSM4 sequence by Ty element transposition tagging. Disruption of the SSM4 gene does not affect cell viability and suppresses the rna14 mutant phenotypes. The protein encoded by the SSM4 gene has a calculated molecular mass of 151 kDa and does not contain any known motif or show homology with known proteins. The toxicity of the SSM4 gene in E. coli suggests that a direct biochemical activity is associated with the corresponding protein.
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    Genetic interaction between the Ras-CAMP pathway and the Dis2s1/Glc7 protein phosphatase in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 257-262 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Protein phosphatase ; Ras-cAMP pathway ; DIS2S1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Saccharomyces cerevisiae DIS2S1/GLC7 gene encodes a type 1 protein phosphatase indispensable for cell proliferation. We found that introduction of a multicopy DIS2S1 plasmid impaired growth of cells with reduced activity of the cAMP-dependent protein kinase. In order to understand further the interaction between the two enzymes, a temperature-sensitive mutation in the DIS2S1 gene was isolated. The mutant accumulated less glycogen than wild type at the permissive temperature, indicating that activity of the Dis2s1 protein phosphatase is attenuated by the mutation. Furthermore, the dis2s1 ts mutation was shown to be suppressed by a multicopy plasmid harboring PDE2, a gene for cAMP phosphodiesterase. These results indicate that the Ras-cAMP pathway interacts genetically with the DIS2S1/GLC7 gene.
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    Stress-induced transcriptional activation mediated by YAP1 and YAP2 genes that encode the Jun family of transcriptional activators in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 250-256 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Transcriptional activator ; AP-1 ; Stress response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Saccharomyces cerevisiae YAP2 gene encoding an AP-1-like transcriptional activator protein was cloned by selection for genes that confer pleiotropic drug resistance when present in high copy number. The novel YAP2 gene encodes a protein of 45827 daltons and is homologous in part to a known transcriptional activator protein encoded by YAP1/PDR4/SNQ3/PAR1. Homology was found only in both terminal regions. The N-terminal portion contains a region rich in basic amino acids, followed by a “leucine zipper” motif. Overexpression of YAP2 led to the induction of expression of an AP-1 recognition element (ARE)-dependent promoter. The yap1 disruptant has been shown to be sensitive to H2O2. In this study, we demonstrated that the yap1 disruptant is also unable to grow in medium containing 150 μM cadmium, whereas the yap2 disruptant exhibited no significant phenotypes. However, YAP2 in high copy number did suppress cadmium sensitivity, but not H2O2 sensitivity of the yap1 disruptant. YAP1 was able to mediate both cadmium- and H2O2-induced transcriptional activation of an ARE-dependent promoter. A high-copy-number plasmid bearing YAP2 mediated cadmium-induced transcriptional activation of this promoter. The inductions were prevented by the antioxidant N-acetyl-l-cysteine.
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    The 3′ → 5′ exonucleases of both DNA polymerases δ and ε participate in correcting errors of DNA replication in Saccharomyces cerevisiae (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 289-296 
    Details
    ISSN: 1617-4623
    Keywords: DNA polymerases ε and δ ; 3′ → 5′ Exonuclease ; Replication errors ; Spontaneous mutations ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA polymerases II (ε) and III(δ) are the only nuclear DNA polymerases known to possess an intrinsic 3′ → 5′ exonuclease in Saccharomyces cerevisiae. We have investigated the spontaneous mutator phenotypes of DNA polymerase δ and ε 3′ → 5′ exonuclease-deficient mutants, pol3-01 and pol2-4, respectively. pol3-01 and pol2-4 increased spontaneous mutation rates by factors of the order of 102 and 101, respectively, measured as URA3 forward mutation and his7-2 reversion. Surprisingly, a double mutant pol2-4 pol3-01 haploid was inviable. This was probably due to accumulation of unedited errors, since a pol2-4/pol2-4 pol3-01/pol3-01 diploid was viable, with the spontaneous his7-2 reversion rate increased by about 2 × 103-fold. Analysis of mutation rates of double mutants indicated that the 3′ → 5′ exonucleases of DNA polymerases δ and ε can act competitively and that, like the 3′ → 5′ exonuclease of DNA polymerase δ the 3′ → 5′ exonuclease of DNA polymerase ε acts in series with the PMS1 mismatch correction system. Mutational spectra at a URA3 gene placed in both orientations near to a defined replication origin provided evidence that the 3′ → 5′ exonucleases of DNA polymerases δ and ε act on opposite DNA strands, but were in sufficient to distinguish conclusively between different models of DNA replication.
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    A novel method for efficient expression cloning of fungal enzyme genes (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 253-260 
    Details
    ISSN: 1617-4623
    Keywords: Recombinant DNA ; Saccharomyces cerevisiae ; Endo-β-glucanase ; Endo-xylanase ; Heterologous expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have developed a method for fast and efficient isolation of enzyme genes from filamentous fungi by combining the ability of Saccharomyces cerevisiae to express heterologous genes with the utilisation of sensitive and reliable enzyme assays. A cDNA library from the fungus Humicola insolens was constructed in a S. cerevisiae/Escherichia coli shuttle vector in E. coli. Sub-pools of the library were subsequently screened for enzyme activity in S. cerevisiae. More than 130 clones were identified as positive in either an endo-β-glucanase or an endo-xylanase assay. Based on a partial characterization of the DNA sequence of the individual clones, they could be grouped into five distinct types of endo-β-glucanases and three types of endo-xylanases. A representative cDNA from each type was sub-cloned in an Aspergillus vector and expressed in A. oryzae. The new cloning method may be an important alternative to traditional cloning methods based on amino acid sequence information.
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    URL: http://dx.doi.org/10.1007/BF00301060
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    Efficient UV stimulation of yeast integrative transformation requires damage on both plasmid strands (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 308-314 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Integrative plasmids ; Recombinational structures ; UV irradiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nature of UV-induced pre-recombinational structures was studied using transformation of Saccharomyces cerevisiae cells with non-replicative plasmids. Transformation by double-stranded plasmids irradiated with UV was stimulated up to 50-fold, and both plasmid integration and conversion of the mutated chromosomal selective gene were found to be equally increased. The stimulation observed with such ‘totally’ irradiated plasmids was not found with plasmids bearing lesions in only one strand. This effect is attributed to the formation by excision repair of recombinogenic structures consisting of a pyrimidine dimer opposite a gap. When single-stranded integrative plasmids were irradiated, their transforming potential was decreased but the proportion of transformants that arose by gene conversion, rather than by plasmid integration, was increased from 8% to 49% as a function of the UV dose. Possible reasons why single-strand UV lesions favour gene conversion are discussed.
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    Shared control of maltose induction and catabolite repression of the MAL structural genes in Saccharomyces (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 622-630 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Yeast Catabolite repression ; Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maltose utilization in yeast requires the presence of any one of the five unlinked, homologous MAL loci. Transcription of the two structural genes MALT (permease) and MALS (maltase) is induced by maltose and catabolite-repressed by glucose. MAL6T and MAL6S share a common 5′ intergenic sequence; deletion studies within this sequence revealed a bi-directionally functioning upstream activation sequence (UASM) consisting of four 11bp homologous sites. Activation of these sites by the MALR protein results in the coordinate expression of MAL6T and MAL6S. The basal promoter activates MALS expression to a greater extent than MALT and is located in a region that overlaps UASM. Deletion of several subsites within the UASM has an asymmetric effect on MAL gene expression, having a greater affect on MALT than on MALS. Catabolite repression of MAL6T and MAL6S by glucose is controlled at several levels. Using disruption mutants, the positively acting MAL1R protein was also found to play a role in catabolite repression of MAL6T and MAL6S.
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    RPK1, an essential yeast protein kinase involved in the regulation of the onset of mitosis, shows homology to mammalian dual-specificity kinases (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 641-653 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; RPK1 gene ; Protein kinase ; DNA replication ; Initiation of mitosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the sequence of RPK1 (for Regulatory cell Proliferation Kinase), a new Saccharomyces cerevisiae gene coding for a protein with sequence similarities to serine/threonine protein kinases. The protein sequence of 764 amino acids includes an amino-terminal domain (residues 1–410), which may be involved in regulation of the kinase domain (residues 411–764). The catalytic domain of Rpkl is not closely related to other known yeast protein kinases but exhibits strong homology to a newly discovered group of mammalian kinases (PYT, TTK, esk) with serine/threonine/tyrosine kinase activity. Null alleles of RPK1 are lethal and thus this gene belongs to the small group of yeast protein kinase genes that are essential for cell growth. In addition, eliminating the expression of RPK1 gives rise to the accumulation of non-viable cells with less than a 1 N DNA content suggesting that cells proceed into mitosis without completion of DNA synthesis. Therefore, the Rpkt kinase may function in a checkpoint control which couples DNA replication to mitosis. The level of the RPK1 transcript is extremely low and constant throughout the mitotic cycle. However it is regulated during cellular differentiation, being decreased in α-factor-treated a cells and increased late in meiosis in a/α diploids. Taken together, our results suggest that Rpk1 is involved in a pathway that coordinates cell proliferation and differentiation.
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    Response of root mRNA population to sulphate shortage in maize seedlings (1994)
    Springer
    Plant and soil 162 (1994), S. 309-313 
    Details
    ISSN: 1573-5036
    Keywords: in vitro translation ; maize ; nutrient stress proteins ; Poly(A)+RNA ; sulphate deprivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots of ten-days-old seedlings obtained from a maize hybrid grown in complete or in sulphate-deprived medium were used to extract Poly(A)+RNA. The response to sulphate deprivation, which is known to increase the uptake capacity up to ten times, was manifested also by the expression of three mRNA species, as shown by the in vitro translation of the mRNA population. One hour after transfer to complete nutrient medium all three mRNAs were still present.
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    Plagiogravitropism of maize roots (1994)
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    Plant and soil 165 (1994), S. 327-332 
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    ISSN: 1573-5036
    Keywords: gravitropism ; maize ; nodal roots ; plagiogravitropism ; seminal roots ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The direction of root growth can be studied by analyzing the trajectories of roots growing in soil. Both the primary seminal root and nodal roots of maize attain a preferred, or liminal, angle of growth that deviates from the vertical. These roots are said to be plagiogravitropic. Experiments using plants grown in soil-filled boxes revealed that the primary seminal root is truly plagiogravitropic. It shows both positive and negative gravitropism in response to gravity stimuli and tends to maintain its direction even after growing around obstacles. These are experimental results suggesting that plagiogravitropic growth is controlled by internal factors. The orientation of the grain affects the establishment of the liminal angle of the primary seminal root, and both the position of their node of origin and the root diameter are closely related to the plagiogravitropic behaviour of nodal roots. Several external factors are also known to influence plagiogravitropism. Low soil water content causes a decrease in the angle of growth and soil mechanical resistance suppresses the gravitropic curvature. Plagiogravitropic behaviour of both seminal and nodal roots plays a significant role in shaping the root system.
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    Genetic and environmental effects on abscisic acid accumulation in leaves of field-grown maize (1994)
    Springer
    Euphytica 78 (1994), S. 81-89 
    Details
    ISSN: 1573-5060
    Keywords: abscisic acid ; inheritance ; drought stress ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study analyzes the components of phenotypic variation for abscisic acid (ABA) content in maize (Zea mays L.) leaves and the correlations with drought sensitivity index (DSI) and silk delay (SD), involved in the reaction to water deficit. Eight early- and seven medium-maturity inbreds were examined in field trials: in 1990 with low irrigation volume and in 1991 with low and high irrigation volumes. ABA concentration and DSI were investigated at growth stages (S) corresponding to stem elongation (S3), appearance of the first husks (S4), and mid-end of silking (S5). The ABA concentration was significantly higher in conditions of water deficit and in the later growth stage. The genetic component for ABA concentration attained higher relative values than those shown by DSI in the same growth stages and by SD; moreover, it increased from growth stage 3 to stage 5. The genotype × year and genotype × irrigation volume interactions were smaller for ABA concentration than for DSI and SD. The broad sense heritability on a plant basis, estimated in drought conditions, for ABA concentration ranged from 21.4 to 55.1% according to maturity group and growth stage. A wide variation was observed among lines for ABA concentration: the medium-maturity group showed a three-fold range (from 219 to 605 ng ABA g−1 dry weight). No clear relationships between ABA concentration, DSI and SD were found. These results indicate the feasibility of a selection for ABA concentration within segregating populations derived from crosses between the inbred lines herein tested.
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    Feedback control of gene expression (1994)
    Springer
    Photosynthesis research 39 (1994), S. 427-438 
    Details
    ISSN: 1573-5079
    Keywords: acetate ; glucose ; maize ; metabolic repression ; photosynthetic genes ; transcription regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although feedback regulation of photosynthesis by carbon metabolites has long been recognized and investigated, its underlying molecular mechanisms remain unclear. The recent discovery that glucose and acetate trigger global repression of maize photosynthetic gene transcription provides the first direct evidence that a fundamental mechanism is used for feedback regulation of photosynthesis in higher plants. The metabolic repression of photosynthetic genes has now been found in many higher plants and is likely universal. It overrides other regulation by light, tissue type and developmental stage, and serves potentially as the molecular basis of interactions between sink and source tissues. Using simplified and convenient cellular systems and transgenic plants, the study of metabolic regulation of gene expression offers an excellent opportunity for the understanding of global and coordinate gene control and metabolite-mediated signal transduction in higher plants.
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    Evaluation of parameters describing the root system architecture of field grown maize plants (Zea mays L.) (1994)
    Springer
    Plant and soil 164 (1994), S. 155-167 
    Details
    ISSN: 1573-5036
    Keywords: axile roots ; maize ; nodal roots ; root length ; root system ; seminal roots ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this work was to study elongation curves of maize axile roots throughout their elongation period under field conditions. Relationships between their elongation rate and the extension rate of their branched region were also studied. Maize, early-maturing cultivar Dea, was grown on a deep, barrier-free clay loam (depth 1.80m). Trenches were dug during four periods until after silking and axile roots were excavated. Parameters measured were total length and the lengths of basal and apical unbranched zones. The rank of the bearing phytomer and general data about the carrying plant were also recorded. Results showed that axile roots from lower phytomers had similar elongation rates irrespective of the rank of the carrying phytomer. This elongation rate declined with root age. A monomolecular elongation model was fitted to the experimental data. Elongation was much slower in roots from upper phytomers. A rough linear relationship was found between the elongation rate of axile roots and the length of the apical unbranched zone. This result suggests that laterals appeared on a root segment a constant time after it was formed. Possible mechanisms with may account for the declining elongation rate with root age (increasing distance from aerial parts or adverse environmental conditions in deep soil layers) and variability between individual roots are also discussed.
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    Evaluation of parameters describing the root system architecture of field grown maize plants (Zea mays L.) (1994)
    Springer
    Plant and soil 164 (1994), S. 169-176 
    Details
    ISSN: 1573-5036
    Keywords: branching ; growth ; lateral roots ; maize ; root morphology ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The architecture of the root system is related to its water and mineral uptake. In this paper, the number, growth, and branching of first-order lateral roots are studied on field grown maize (early maturing cultivar ‘Dea’), mainly in relation to the depth and to the rank of the bearing phytomer. The soil was a deep clay loam, without any barrier until 1.80 m. The branching density was studied along axile roots until 1.40 m from the base, on a sample of individually excavated axile roots. A strong gradient of density was shown: the mean branching density decreased from 12 roots.cm−1 near the base to 4 roots.cm−1 at a 60 cm depth. Seminal roots were less densely branched than nodal roots. The mean difference was about 4 roots.cm−1. The length and branching density of lateral roots were studied on mature parts of the root systems where the growth and branching of the laterals were completed, using samples extracted from large soil monoliths. The length distribution of lateral roots was highly asymmetrical, for every source phytomer (mean: 25 mm; median: 16 mm). Many lateral roots were very short, and only 2 % reached a length higher than 10 cm. Only 29 % of all the laterals bore second-order lateral roots. Vigorous laterals branched more systematically and more profusely: the branching density varied from 2 to 5 roots.cm−1 according to the length of the mother lateral root. Both the number and length of lateral roots appeared to be affected by the soil bulk density which varied with the depth.
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    Amino-acid influx at the soil-root interface of Zea mays L. and its implications in the rhizosphere (1994)
    Springer
    Plant and soil 163 (1994), S. 1-12 
    Details
    ISSN: 1573-5036
    Keywords: amino-acids ; maize ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of the study was to investigate the ability of intact Zea mays. L. roots to regulate the amount of free amino-acids present in the rhizosphere. Using metabolic inhibitors it was demonstrated that the release of amino-acids from the root occurred by passive diffusion, whilst free amino-acids outside the root could be re-captured by an active transport mechanism. The influx of amino-acids into the root was shown to be relatively independent of spatial location along the root and was little affected by the presence of other organic compounds in solution. It was deduced from root concentration gradients that the main site of amino-acid exudation was at root tips. Amino-acid uptake by the root was shown to be independent of both inorganic-N concentration and the presence of other organic solutes in solution. A computer simulation model was constructed to assess the contribution of organic-N uptake (acidic, basic and neutral amino-acids) to the plant's N budget, in comparison to the inorganic solutes NO3 and NH4. Simulations of N uptake from a 0.5 mm radius rhizosphere indicated that when inorganic-N concentrations in soil were limiting (≤0.1 μmoles cm-3 soil), the uptake of amino-N accounted for up to 90% the total N taken up by the roots. In situations where fertilizer inputs are high, and levels of organic matter in soil are low, the contribution of amino-N might still be expected to form 〈30% of the total N taken up by the root system. It was concluded that the uptake of amino-acids from the rhizosphere may be important in both N nutrition and in the minimization of root C and N losses to the soil. Consequently this may be important in governing the size of the rhizosphere microbial population.
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    Light differentially regulates lateral and longitudinal auxin transport in the mesocotyl of etiolated maize seedlings (1994)
    Springer
    Plant growth regulation 14 (1994), S. 167-171 
    Details
    ISSN: 1573-5087
    Keywords: auxin-transport ; indoleacetic acid ; maize ; photoinhibition ; transport ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake of IAA into excised mesocotyls of non-irradiated maize seedlings was linear up to a concentration of about 4×M and in this range there was a tight coupling between the IAA in the stele and the cortex. Prior irradiation with white light of intact seedlings unbalanced this coupling. Lateral and longitudinal transport were affected differently. In the stele, the effect of prior irradiation on longitudinal transport was multiphasic, with an initial stimulatory effect followed by a negative effect at longer prior irradiation times. The lateral transport from the stele to the cortex showed no stimulatory effect and appeared to be inhibited within at least 15 min. The effect of the prior irradiation on longitudinal transport in the stele appeared to be a high intensity effect. In contrast, the effect of the prior irradiation on the lateral transport from the stele to the cortex was saturated at much lower intensities. The data suggest that the light induced change in the lateral transport of IAA between the two tissues may be due to changes either in the number of open lateral transport channels/carriers or in the conductivity of these channels/carriers.
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    Comparative isozyme polymorphisms of north American eastern gamagrass,Tripsacum dactyloides var.dactyloides and maize,Zea mays L. (1994)
    Springer
    Genetica 94 (1994), S. 77-83 
    Details
    ISSN: 1573-6857
    Keywords: isozymes ; Tripsacum ; maize ; wide hybridizations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Random samples, consisting of at least 100 individual seedlings, were taken from the diploid (2n=2x=36) eastern gamagrass (Tripsacum dactyloides var.dactyloides) and assayed to determine which of 12 enzyme marker loci and isozyme systems would be most informative in providing satisfactory resolution of both maize andTripsacum isozyme systems. For comparison, eight maize inbreds were included in the study to aid evaluation and comparison of the various isozyme systems. In addition, evaluations were conducted to identify if the identified optimum isozyme system could be used to detectTripsacum introgression in maize following a maize ×Tripsacum backcrossing scheme. Using the established isozyme techniques for maize (Zea mays L.), theAdh, Pgd, Cat, Est, B-Glu, Got, Idh, Tpi isozyme systems detected no polymorphism among theTripsacum individuals assayed. TheEst andB-Glu systems forTripsacum were unscorable due to poor staining and resolution. TheAcp, Mdh, Pgm, andPhi isozyme systems were found to be satisfactory markers for differentiating between eastern gamagrass individuals as well as detectingTripsacum introgression in maize. The availability of useful isozyme systems which can simultaneously provide significant isozyme resolution of maize,Tripsacum and maize-Tripsacum backcross hybrids, on a single gel system, will be useful for the detection of marker assistedTripsacum introgression into maize. In addition, the identification of a set of variable biochemical markers should also assist breeding, selection and genetic manipulations in eastern gamagrass.
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    Light inducibility and tissue specificity of theR gene family in maize (1994)
    Springer
    Genetica 94 (1994), S. 225-234 
    Details
    ISSN: 1573-6857
    Keywords: anthocyanin ; maize ; helix-loop-helix ; tissue specificity ; paramutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The red and purple anthocyanin pigments of plants are visible genetic markers and their spatial and temporal accumulation is strictly regulated. Anthocyanin biosynthesis is also modulated by environmental factors such as light and temperature. Thus this process represents an appealing model system for the study of gene regulation, as well as for studying developmental biology. In maize, the pattern of pigmentation of the plant is controlled by theR, Sn andB genes, a small family of HLH transcription factors. Here we report the pattern of light induction and tissue specific expression of the regulatory and structural genes involved in this biosynthesis. TwoSn alleles differing in their light response have been considered and analyzed by Northern andin situ hybridization experiments. An unusual phenomenon of interaction between the homologousR andSn genes leading to a partial gene silencing is reported. We hypothesize a model in which silencing is achieved through methylation of specific sites.
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    Microbiological changes in mawè during natural fermentation (1994)
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    World journal of microbiology and biotechnology 10 (1994), S. 410-413 
    Details
    ISSN: 1573-0972
    Keywords: Enterobacteriaceae ; fermentation ; lactic acid bacteria ; maize ; mawè ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lactic acid bacteria increased from 3.2 × 106 and 1.6 × 107 c.f.u./g (wet wt) to 2 × 109 and 1.6 × 109 c.f.u./g after 12 to 24 h of fermentation of home-produced mawè (a dough produced from dehulled maize) and commercial mawè, respectively. In commercial mawè, the yeast count increased from 1.3 × 105 to 2.5 × 107 c.f.u./g after 48 h of fermentation before decreasing, whereas in the home-produced mawè it increased from 2.5 × 104 to 3.2 × 107 c.f.u./g after 72 h of fermentation; the dominant yeasts were mainly Candida krusei, although C. kefyr, C. glabrata and Saccharomyces cerevisiae were also present. Enterobacteriaceae counts increased slightly during the initial stage ofthe fermentation, but decreased below the detection level after 24 to 48 h. Enterobacter cloacae was mostly found in commercial mawè and Escherichia coli mostly in homeproduced mawè.
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    Alley cropping and mulching withErythrina poeppigiana (Walp.) O. F. Cook andGliricidia sepium (Jacq.) Walp.: effects on maize/weed competition (1994)
    Springer
    Agroforestry systems 25 (1994), S. 119-134 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; Erythrina poeppigiana ; Gliricidia sepium ; weeds ; maize ; mulch ; weed competition ; weed reduction potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potential of allye cropping systems to sustain a high productivity with low external inputs and the reduction of maize/weed competition through weed suppression in different alley cropping and sole-cropped mulched systems was studied in Costa Rica at CATIE. Data were recorded eight years after establishment of the experiment. Plant residues ofErythrina poeppigiana trees (10 t/ha dry matter) planted at 6 by 3 m reduced weed biomass by 52%, whileGliricidia sepium trees (12 t/ha dry matter) planted at 6 by 0.5 m reduced weed biomass by 28%, in comparison to controls.Erythrina had a considerable impact on grass weeds, whileGliricidia reduced the incidence of some dicot weeds. Weed competition significantly reduced maize yield in all systems. Nevertheless weed suppression contributed to the higher maize grain yield underErythrina andGliricidia alley cropping of 3.8 t per hectare as opposed to the unmulched control yield of 2.0 t per hectare.
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    Evaluation of phytotoxic effects ofGliricidia sepium (Jacq.) Walp prunings on maize and cowpea seedlings (1994)
    Springer
    Agroforestry systems 26 (1994), S. 249-254 
    Details
    ISSN: 1572-9680
    Keywords: phytotoxicity ; cowpea ; Gliricidia sepium prunings ; maize ; seedlings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phytotoxic effects ofGliricidia prunings were tested on maize seedlings in the laboratory and on maize and cowpea seedlings in the field. In the laboratory test, growth of maize seedlings was significantly depressed by addition of leachate ofGliricidia prunings. In the field, leaf, chlorosis of maize and cowpea seedlings occurred when mulched withGliricidia prunings; number of affected leaves increased with increasing mulch rate. Maize was more susceptible than cowpea. This phytotoxic effect, however, did not reduce growth of maize and cowpea seedlings in the field. ApplyingGliricidia mulch one week before planting eliminated the phytotoxic effects on maize.
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    The effects of alley cropping withLeucaena leucocephala and of different management practices on the productivity of maize and soil chemical properties in lowland coastal Kenya (1994)
    Springer
    Agroforestry systems 27 (1994), S. 31-51 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; leucaena mulch ; dairy cattle slurry ; maize ; cowpea ; lowland coastal tropics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of leucaena hedgerows, mulching with leucaena foliage (0,50 and 100% of harvested foliage), cowpea intercropping and adition of dairy cattle slurry (55 t ha−1 per maize crop) on the yield of maize from a sandy soil were assessed. The four-year results from five maize crops are reported. Except in the first year, yields of maize grain and stover were significantly reduced by 30% in the presence of leucaena hedgerows. Use of leucaena mulch eliminated this effect; application of all the harvested leucaena mulch (100%) increased the total maize grain yield of the five crops by 44% over sole maize. Hedgerow and mulching management required an additional 36 mandays labour ha−1 which was more than compensated by the increased maize yields. Furthermore leucaena hedgerows substantially depressed the growth of weeds between cropping seasons. Intercropping with cowpea significantly depressed yields of maize grain and stover when both crops were sown together, but not in later seasons when cowpea was sown four weeks after the maize. Application of slurry increased the total yields of maize grain and stover by 35 and 37%, respectively. The grain yield of maize in leucaena hedgerow treatments fertilized with slurry did not respond to application of more than 50% of leucaena foliage, which suggested that half of the foliage could be spared for feeding to livestock. The cumulative yield of maize grain from the highest yielding organic system was 85% of the yield from the fertilizer treatment. The study, which is continuing, demonstrates that large increases in agricultural productivity are possible through the intercropping of maize with woody forage and grain legumes and the integration of dairy cattle production into the system. It thus shows the importance of exploiting crop/livestock interactions.
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    URL: http://dx.doi.org/10.1007/BF00704833
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    Relationships among American and Spanish populations of maize (1994)
    Springer
    Euphytica 79 (1994), S. 149-161 
    Details
    ISSN: 1573-5060
    Keywords: maize ; germplasm ; cluster analysis ; landraces ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two experiments were carried out with two objectives. First, to establish the phenetic relationships among the maize (Zea mays L.) landraces from Galicia (Northwestern Spain) maintained at the Misión Biológica de Galicia. Second, to assess the resemblance between a collection of Spanish populations (including the landraces from Galicia) and a set of US Corn Belt varieties. For the first objective 73 varieties from Galicia, along with 9 hybrid checks, were grown in 9×9 simple lattices at two locations for two years. For the second objective 131 populations from the US Corn Belt and Spain, along with 9 hybrid checks, were grown for three years in unreplicated experiments. Cluster analyses were carried out with the first principal components that accounted for a significant amount of the total variation. Four groups were found among the landraces from Galicia. The populations from Spain and America were classified as belonging to nine main groups. The replicated experiment was more accurate than the unreplicated one. However, it is concluded that an unreplicated test grown in several environments is accurate enough to detect the main groups, although some inaccuracies should be expected.
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    URL: http://dx.doi.org/10.1007/BF00023586
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    Genetic variation for resistance to low-temperature photoinhibition of photosynthesis in maize (Zea mays L.) (1994)
    Springer
    Euphytica 80 (1994), S. 85-93 
    Details
    ISSN: 1573-5060
    Keywords: maize ; Zea mays ; photoinhibition ; photosynthesis ; low-temperature adaptation ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sixty-seven inbred lines of maize were evaluated for resistance to low-temperature photoinhibition of photosynthesis, using a pulse-modulated chlorophyll fluorescence technique. The evaluation procedure was based on leaf discs, which were exposed to a high irradiance (1000 µmol/m2/s) at 7°C. The efficiency of open PSII reaction centres as a reflection of overall photosynthesis was measured before and after a photoinhibition-inducing treatment. Exposure of leaf discs to photoinhibitory condition for 2, 4, and 8 hours resulted in an efficiency reduction of 30, 53 and 83%, respectively. Testing of inbred lines showed large differences for photoinhibition susceptibility. The difference in photosynthetic efficiency between the most extreme lines after a treatment of eight hours was 39%. Resistance to photoinhibition was shown to be relevant under cool field conditions. It proved to be a trait strongly amenable to selection.
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    URL: http://dx.doi.org/10.1007/BF00039302
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    Response of vesicular-arbuscular mycorrhizas of maize to various rates of P addition to different rooting zones (1994)
    Springer
    Plant and soil 158 (1994), S. 119-128 
    Details
    ISSN: 1573-5036
    Keywords: maize ; P placement ; P supply ; rooting zone ; VAM colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Colonization of plant roots by vesicular-arbuscular mycorrhizal fungi is known to be reduced as the phosphorus nutrition of the plant is increased. It is generally accepted that the concentration of P in the plant rather than the soil regulates VAM colonization. Whether it is the shoot P concentration, the mean P concentration in the root system or the P concentration in the specific root being colonized is not known, but is of agronomic significance because fertilizer P is frequently applied in concentrated zones which would be expected to result in higher P concentration in roots growing in the fertilized zone than in the remainder of the root system. Growth chamber and field experiments were conducted to determine the effect on colonization of supplying varying amounts of P to different portions of the rooting zone. In growth chamber studies using a split-pot technique, the proportion of maize (Zea mays L.) root length containing arbuscules in a high-P zone was lower than that of roots of the same plant growing in a low- or medium-P zone. Root P concentration was higher in the high-P zone. In a field experiment conducted over a two-year period, VAM colonization of roots of young maize plants growing in fertilized soil was affected differently than that of roots growing outside the fertilized zone. A small addition of fertilizer P increased colonization of roots in the fertilized soil, but further additions resulted in an abrupt decline followed by a slower further decline, although colonization was not eliminated even by rates of 1600 μg P g-1 soil. Colonization of roots growing outside the fertilized zone declined gradually with increasing P addition but the overall decline was less than for roots in the fertilized zone. The data support the hypothesis that it is P concentration in the portion of the root system being colonized rather than the general P status of the plant which regulates VAM colonization. The agronomic implication of this is that, although a fertilizer band may reduce VAM colonization of roots in the band volume, roots growing outside this volume may be well colonized so the mycorrhizal symbiosis may be an important contributor to P nutrition.
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    URL: http://dx.doi.org/10.1007/BF00007924
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    Stably transformed cell lines from protoplasts of maize endosperm suspension cultures (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 39-46 
    Details
    ISSN: 1573-5044
    Keywords: endosperm cell culture ; maize ; protoplast ; transformation ; zeins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts were isolated from Zea mays (L.) A69Y endosperm suspension cultures and transformed by polyethylene glycol mediated DNA uptake with chimaeric gene constructs containing β-glucuronidase (GUS) or neomycin phosphotransferase II (NPTII); GUS-expressing and Kanamycin-resistant cultures were recovered. The transformed cells showed integration of the introduced foreign genes into genomic DNA and maintained their ability to synthesize endosperm-specific reserve proteins (zeins). No deletion or rearrangement of zein genes were observed in transformed cultures. Stable transformation of cultured maize endosperm cells may therefore represent a new methodological approach for the study of the transcriptional regulation of endosperm-expressed genes.
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    URL: http://dx.doi.org/10.1007/BF00048115
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    Properties of maternal haploid maize plants and potential application to maize breeding (1994)
    Springer
    Euphytica 79 (1994), S. 13-18 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; haploid induction ; maternal haploids ; inducer line ZMS ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Presented are the results of a two-year study of haploid maize plants in the field. The haploids were produced with the aid of inducer line ZMS. In total, 604 and 1030 haploids were obtained and studied in the first and second years, respectively. Tassels of haploid plants were found to be almost completley sterile. Fertility of ears was studied by pollinating them with the pollen from diploid inbred lines, the cross resulting in almost all of the haploid ears carrying kernels. On average 27.4 kernels per ear of haploid plant were obtained in the first year of study and 26.3 in the second. These gave rise to normal diploid plants. This property allows genotypes selected at the level of haploid plants to be involved in breeding process. Unusual plants were found among haploids, phenotypically resembling homozygous lines. It was assumed that the plants had resulted from spontaneous chromosome doubling in haploids. The results of comparative studies of progenies of unusual plants and inbred lines derived from the same synthetic population are presented.
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    URL: http://dx.doi.org/10.1007/BF00023571
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    Changes in the photosynthetic light response curve during leaf development of field grown maize with implications for modelling canopy photosynthesis (1994)
    Springer
    Photosynthesis research 42 (1994), S. 217-225 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; leaf age ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the photosynthetic light-response curve during leaf development were determined for the fourth leaf of maize crops sown on 23 April and 10 June. Temperatures were unusually mild during late spring/early summer and neither crop experienced chilling damage. The concept of thermal time was used to take into account the effects of different temperature regimes on developmental stage, thereby enabling photosynthetic light-response data to be combined for both crops to describe the general response. Large variations in the upper asymptote (Asat) and convexity (Θ) of the light-response curve occurred during leaf development, but the maximum quantum yield of CO2 assimilation remained relatively constant throughout. Dark respiration rates showed a small but significant decrease with leaf age and generally ranged between 5 and 10% of Asat. A simple mathematical model was developed to assess the sensitivity of daily leaf photosynthesis (AL) to reductions in the Asat, Θ and the initial slope (Φ) of the light-response curve at different stages of leaf development. On bright sunny days, and at all developmental stages, AL was ca. twice as sensitive to reductions in Asat than to reductions in Φ and Θ. In overcast conditions, however, all three parameters contributed significantly to reductions in leaf photosynthesis, although the contribution of Φ was greatest during early leaf growth, while older leaves were most sensitive to depressions in Asat. The implications of these results for modelling the sensitivity of canopy photosynthesis to chill-induced photoinhibition of the light-response curve are discussed.
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    URL: http://dx.doi.org/10.1007/BF00018264
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    Lysine inhibition of Saccharomyces cerevisiae: role of repressible L-lysine ε-aminotransferase (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 572-575 
    Details
    ISSN: 1573-0972
    Keywords: Growth inhibition ; L-lysine ε-aminotransferase ; nitrogen limitation ; α-oxoadipic acid ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Lysine added to grain mashes under nitrogen-limiting conditions (as in most industrial fermentations) inhibited growth of Saccharomyces cerevisiae. This inhibition was relieved by raising the assimilable nitrogen content. Lysine-induced inhibition is not mediated through accumulation of α-oxoadipic acid, an intermediate of lysine metabolism which accumulates by a back up of intermediates in de novo synthesis. Lysine degradation is regulated by the synthesis of L-lysine ε-aminotransferase, an enzyme that catalyses the first step in one of three possible routes of lysine degradation (not previously reported in S. cerevisiae). Synthesis is repressed under nitrogenlimiting conditions, but derepressed when excess assimilable nitrogen is available. Derepression results in degradation of lysine and decreases inhibitory effects on growth. The toxic compound appears to be lysine itself.
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    Survey for parasites ofSesamia calamistis (Lep.: Noctuidae) andEldana saccharina (Lep.: Pyralidae) in southwestern Nigeria (1994)
    Springer
    BioControl 39 (1994), S. 367-376 
    Details
    ISSN: 1573-8248
    Keywords: Insect parasitoid ; parasitic nematode ; stem borer ; maize ; West Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Des enquêtes sur le terrain ont été effectuées entre 1990 et 1992 en vue d'étudier les espèces présentes et l'abondance relative des parasites des lépidoptères foreurs des tigesSesamia calamistis Hampson etEldana saccharina Walker dans des champs de maïs du sud-ouest du Nigéria. Parmi les espèces de parasitoïdes découvertes sur les deux foreurs de tiges figuraient les parasitoïdes des larves et pupes,Sturmiopsis parasitica Curran (Diptera: Tachinidae) etBrachymeria feae Masi (Hymenoptera: Chalcididae), ainsi que le parasitoïde des larves,Dolichogenidea polaszeki Walker (Hymenoptera: Braconidae). Des attaques du braconidéCotesia sesamiae (Cameron) ont été observées surS. calamistis. L'hyperparasitoïdeExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) a été observé sur une pupe deS. parasitica. Des nématodes parasites appartenant àMermis sp. et/ouHexamermis sp. ont été observés sur des larves des deux foreurs des tiges. Dans l'ensemble, le parasitisme larvaire était faible avec des valeurs comprises entre 4.2 et 22.8% pourS. calamistis, et 1.2 et 13% pourE. saccharina. Parmi les parasitoïdes observés, l'espèce la plus courante étaitS. parasitica. Des attaques de quatre hyménoptères parasitoïdes des oeufs ont été observées surS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, etTrichrogrammatoidea eldanae Viggiani (Trichogrammatidae). Les oeufs étaient parasités à des valeurs comprises entre 0 et 33%. L'unique parasitoïde des oeufs observé surE. saccharina étaitT. applanatus Bin et Johnson (Scelionidae) qui ne provoquait qu'un parasitisme de 5%.
    Notes: Abstract Field surveys were conducted during 1990–92 to document the relative abundance of different species of parasites of the lepidopterous stem borersSesamia calamistis Hampson andEldana saccharina Walker in maize fields in southwestern Nigeria. Species of parasitoids detected on both stem borers included the larvalpupal parasitoidsSturmiopsis parasitica Curran (Diptera: Tachinidae) andBrachymeria feae Masi (Hymenoptera: Chalcididae), and the larval parasitoidDolichogenidea polaszeki Walker (Hymenoptera: Braconidae). The braconidCotesia sesamiae (Cameron) was found attackingS. calamistis. The hyperparasitoidExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) was detected on a pupa ofS. parasitica. Parasitic nematodes belonging toMermis sp. and/orHexamermis sp. were found infesting larvae of both stem borers. Overall, larval/pupal parasitization levels at Ibadan were low and ranged from 4.2 to 22.8% forS. calamistis and 1.2 to 13% forE. saccharina. Of the parasites found,S. parasitica was the most common, followed by nematodes. Four hymenopteran egg parasitoids were found attackingS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, andTrichogrammatoidea eldanae Viggiani (Trichogrammatidae). Egg parasitization ranged from 13.4 to 41.5%. The only egg parasitoid detected onE. saccharina wasTelenomus applanatus Bin and Johnson, which inflicted only 5% parasitization.
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    Production ofNosema marucae for biological control of cereal stem borers (1993)
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    Entomologia experimentalis et applicata 67 (1993), S. 143-148 
    Details
    ISSN: 1570-7458
    Keywords: Nosema marucae ; microsporidium ; production ; biological control ; cereal stem borer ; Chilo partellus ; maize ; sorghum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a study covering 3 years, experiments were carried out in order to determine the feasibility of producing a microsporidian pathogenNosema marucae in the spotted stalkborerChilo partellus. A maximum yield of 4.9×108 spores/larva (equivalent to 3.1×1010 spores/g fresh larval body weight) was obtained in 3rd instar larvae. It is considered that the production is inexpensive and can be readily adapted for small scale pathogen propagation systems in the tropics.
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    URL: http://dx.doi.org/10.1007/BF02386519
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    Distribution of second generation European corn borer,Ostrinia nubilalis, egg masses in field corn and relationship to subsequent tunneling damage (1993)
    Springer
    Entomologia experimentalis et applicata 68 (1993), S. 15-23 
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    ISSN: 1570-7458
    Keywords: insecta ; Ostrinia nubilalis ; egg distribution ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between second generation European corn borer (Ostrinia nubilalis Hübner) egg mass numbers and subsequent field corn damage, as measured by stalk cavity numbers, was studied in 79 fields in northeastern North Carolina over three years. A mean of 0.028 egg masses per plant (645 egg masses/23400 plants) was found over the course of the study. Significant differences in oviposition rate were detected between fields and years. Ca. 85% of egg masses were deposited in a five leaf zone surrounding the primary ear; of these, 89% were found on the lower four leaves in this zone. Egg masses appeared to be distributed randomly within fields but at low rates of incidence, and oviposition was relatively uniform between sampling areas within individual fields. Under moderate to high oviposition pressure (mean number of egg masses per plant over the duration of the oviposition period 〉ca. 0.02), eggs laid during the early phases of the oviposition period account for more subsequent stalk damage than eggs laid during the later phases of the oviposition period. Variations in second generation egg mass numbers accounted for ca. 70% of variation in stalk cavity numbers.
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    Effects of nitrification inhibitors and time and rate of slurry and fertilizer N application on silage maize yield and losses to the environment (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 267-277 
    Details
    ISSN: 1573-0867
    Keywords: animal manure ; leaching ; maize ; nitrification inhibitor ; nitrogen recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with silage maize during eight years on a sandy soil in The Netherlands, showed that dicyandiamide (DCD) addition to autumn-applied cattle slurry retarded nitrification, thus reducing nitrate losses during winter. Spring-applied slurry without DCD, however, was on average associated with even lower losses and higher maize dry matter yields. Economically optimum supplies of mineral N in the upper 0.6 m soil layer in spring (EOSMN), amounted to 130–220 kg ha−1. Year to year variation of EOSMN could not be attributed to crop demand only. According to balance sheet calculations on control plots, apparent N mineralization between years varied from 0.36 to 0.94 kg ha−1 d−1. On average, forty percent of the soil mineral N (SMN) supply in spring, was lost during the growing season. Hence, the amounts of residual soil mineral N (RSMN) were lower than expected. Multiple regression with SMN in spring, N crop uptake and cumulative rainfall as explanatory variables, could account for 79 percent of the variation in RSMN. Postponement of slurry applications to spring and limiting N inputs to economically optimum rates, were insufficient measures to keep the nitrate concentration in groundwater below the EC level for drinking water.
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    Effect on maize growth of the interaction between increased nitrogen availability and competition with trees in alley cropping (1993)
    Springer
    Agroforestry systems 21 (1993), S. 239-249 
    Details
    ISSN: 1572-9680
    Keywords: Erythrina ; Gliricidia ; alley cropping ; maize ; competition ; nitrogen availability ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize growing next toErythrina hedgerows had 44% lower biomass (p〈0.01) and 35% lower N content (p〈0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p〈0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize. Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture. A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.
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    The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia. III. Effects on soil chemical and physical properties (1993)
    Springer
    Agroforestry systems 21 (1993), S. 117-132 
    Details
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
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    Cloning and expression of Hormoconis resinae glucoamylase P cDNA in Saccharomyces cerevisiae (1993)
    Springer
    Current genetics 24 (1993), S. 38-44 
    Details
    ISSN: 1432-0983
    Keywords: Glucoamylase ; Gene cloning ; Hormoconis resinae ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA coding for glucoamylase P of Hormoconis resinae was cloned using a synthetic oligonucleotide probe coding for a peptide fragment of the purified enzyme and polyclonal anti-glucoamylase antibodies. Nucleotide-sequence analysis revealed an open reading frame of 1848 base pairs coding for a protein of 616 amino-acid residues. Comparison with other fungal glucoamylase amino-acid sequences showed homologies of 37–48%. The glucoamylase cDNA, when introduced into Saccharomyces cerevisiae under the control of the yeast ADC1 promoter, directed the secretion of active glucoamylase P into the growth medium.
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    Normal mitochondrial structure and genome maintenance in yeast requires the dynamin-like product of the MGM1 gene (1993)
    Springer
    Current genetics 24 (1993), S. 141-148 
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    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Dynamin ; Mitochondria ; GTP binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation and characterization of MGM1, and yeast gene with homology to members of the dynamin gene family, is described. The MGM1 gene is located on the right arm of chromosome XV between STE4 and PTP2. Sequence analysis revealed a single open reading frame of 902 residues capable of encoding a protein with an approximate molecular mass of 101 kDa. Loss of MGM1 resulted in slow growth on rich medium, failure to grow on non-fermentable carbon sources, and loss of mitochondrial DNA. The mitochondria also appeared abnormal when visualized with an antibody to a mitochondrial-matrix marker. MGM1 encodes a dynamin-like protein involved in the propagation of functional mitochondria in yeast.
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    Molecular cloning of the PEL1 gene of Saccharomyces cerevisiae that is essential for the viability of petite mutants (1993)
    Springer
    Current genetics 24 (1993), S. 307-312 
    Details
    ISSN: 1432-0983
    Keywords: Growth control ; Genetic mapping ; Molecular cloning ; Nucleo-mitochondrial interaction ; Saccharomyces cerevisiae ; Viability of petites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The PEL1 gene of Saccharomyces cerevisiae is essential for the cell viability of mitochondrial petite mutants, for the ability to utilize glycerol and ethanol on synthetic medium, and for cell growth at higher temperatures. By tetrad analysis the gene was assigned to chromosome III, centromere proximal of LEU2. The PEL1 gene has been isolated and cloned by the complementation of a pel1 mutation. The molecular analysis of the chromosomal insert carrying PEL1 revealed that this gene corresponds to the YCL4W open reading frame on the complete DNA sequence of chromosome III. The putative Pel1 protein is characterized by a low molecular weight of approximately 17 kDa, a low codon adaptation index, and a high leucine content.
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    Sequence analysis of a Papaver somniferum L. mitochondrial DNA fragment promoting autonomous plasmid replication in Saccharomyces cerevisiae and Kluyveromyces lactis (1993)
    Springer
    Current genetics 24 (1993), S. 366-367 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Papaver somniferum L. ; ARS ; Mitochondrial DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The minimal fragment of mitochondrial DNA from Papaver somniferum L. (poppy) able to promote autonomous plasmid replication in the yeast Saccharomyces cerevisiae was sequenced. Sequence analysis of the 917-bp MK4/8 DNA fragment revealed a high AT content, and the presence of two 12-bp sequences differing from the ARS core consensus of S. cerevisiae only by a T and C insertion, respectively. The mitochondrial insert contains a further six 11-bp sequences with one mismatch to the S. cerevisiae core consensus, more then 20 related sequences with two base pair exchanges, numerous direct and inverted repeats, and many copies of a sequence motif called the ARS box. The original 4.2-kb mitochondrial DNA fragment, as well as the minimal 917-bp subfragment in vector pFL1-E (a variant of YIP5, lacking an origin of replication in yeast), were then tested for their ability to replicate autonomously in another fungus, Kluyveromyces lactis.
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    URL: http://dx.doi.org/10.1007/BF00336790
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  • 92
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    The ogd1 and kgd1 mutants lacking 2-oxoglutarate dehydrogenase activity in yeast are allelic and can be differentiated by the cloned amber suppressor (1993)
    Springer
    Current genetics 24 (1993), S. 377-381 
    Details
    ISSN: 1432-0983
    Keywords: 2-Oxoglutarate dehydrogenase ; Molecular cloning ; Saccharomyces cerevisiae ; Sequencing ; Suppressor ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activity of mitochondrial 2-oxoglutarate dehydrogenase in S. cerevisiae can be impaired either by the ogd1 or the kgd1 mutation. The OGD1 gene and two suppressor genes were isolated by complementation of the ogd1 mutant. The complementation of the kdg1 mutant by the OGD1 gene, an allelism test, and meiotic mapping, revealed that the ogd1 and kgd1 mutations are allelic. The two mutations were differentiated by the cloned suppressor gene which was able to partially complement ogd1, but not kgd1. The molecular analysis of the suppressor gene revealed its identity with the natural tRNA CAG Gln gene found in the upstream region of URA10.
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    URL: http://dx.doi.org/10.1007/BF00351844
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  • 93
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    Use of reporter genes for the isolation and characterisation of different classes of sporulation mutants in the yeast Saccharomyces cerevisiae (1993)
    Springer
    Current genetics 24 (1993), S. 451-454 
    Details
    ISSN: 1432-0983
    Keywords: Yeast ; Saccharomyces cerevisiae ; Sporulation mutants ; Reporter genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Reporter genes consisting of sporulation-specific promoters fused to lacZ were used as markers to monitor the sporulation pathway of the yeast Saccharomyces cerevisiae. Strains transformed with these lacZ gene fusions expressed β-galactosidase (assayable on plates using the substrate 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside, X-gal) in a sporulation-dependent manner. Mutagenesis experiments performed on transformed strains resulted in the recovery of a number of novel sporulation mutants. Three classes of mutants were obtained: those which overexpressed the reporter gene under sporulation conditions, those which did not express the gene under any conditions, and those which expressed the gene in vegetative cells not undergoing sporulation. On the basis of the blue colony-colour produced in the presence of X-gal these have been described as superblue, white, and blue vegetative mutants, respectively. These were further characterised using earlier reporter genes and other marker systems. This study established that the multicopy reporter plasmids chosen do not interfere with sporulation; they are valid tools for monitoring the pathway and they provide a way to isolate mutations not readily selected by other markers.
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    URL: http://dx.doi.org/10.1007/BF00351856
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  • 94
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    Physical mapping of the MEL gene family in Saccharomyces cerevisiae (1993)
    Springer
    Current genetics 24 (1993), S. 461-464 
    Details
    ISSN: 1432-0983
    Keywords: Chromosome fragmentation ; MEL gene family ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nine members, MEL2–MEL10, of the MEL gene family coding for α-galactosidase were physically mapped to the ends of the chromosomes by chromosome fragmentation. Genetic mapping of the genes supported the location of all the MEL genes in the left arm of their resident chromosomes.
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    URL: http://dx.doi.org/10.1007/BF00351706
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  • 95
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    Parameters affecting lithium acetate-mediated transformation of Saccharomyces cerevisiae and development of a rapid and simplified procedure (1993)
    Springer
    Current genetics 24 (1993), S. 455-459 
    Details
    ISSN: 1432-0983
    Keywords: Yeast ; Saccharomyces cerevisiae ; Transformation ; Plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have compared a number of procedures for the transformation of whole cells of the yeast Saccharomyces cerevisiae and assessed the effects of dimethylsulphoxide (DMSO) or ethanol, both of which have been reported to enhance transformation efficiency. We find that simplified methods benefit from the addition of one of these compounds, and although differences are observed between strains as to the more beneficial reagent, peak transformation efficiency is, in general obtained with 10% DMSO or 10% EtOH. Increases of between six- and 50-fold are observed, despite a reduction in cell viability, and at this concentration the two compounds are not additive in their effects. The optimum level appears to depend on a balance between improved DNA uptake and reduced cell viability. As a result of this work we present a straightforward and rapid transformation procedure.
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    URL: http://dx.doi.org/10.1007/BF00351857
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  • 96
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    Evolutionary conservation of genomic sequences related to the GGP1 gene encoding a yeast GPI-anchored glycoprotein (1993)
    Springer
    Current genetics 23 (1993), S. 19-21 
    Details
    ISSN: 1432-0983
    Keywords: Glycosylphosphatidylinositol anchored-protein ; Southern analysis ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The GGP1 gene encodes the only GPI-anchored glycoprotein (gp115) that has been purified todate in the budding yeast Saccharomyces cerevisiae. It is a single-copy gene whose deduced amino-acid sequence shares no significant homology to any other known protein. In this paper we report a Southern hybridization analysis of genomic DNA from different eukaryotic organisms to identify homologues of the GGP1 gene. We have analyzed DNA prepared from a unicellular green alga (Chlamydomonas eugametos), from two distantly related yeast species (Candida cylindracea and Schizosaccharomyces pombe), and from the common bean Phasoleus vulgaris. The moderate stringency of the experimental conditions and the high specificity of the probes used indicate that a single-copy of GGP1-related sequences exists in all these eukaryotic organisms. The chromosomal localization of the GGP1 gene in S. cerevisiae has also been determined.
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    URL: http://dx.doi.org/10.1007/BF00336744
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  • 97
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    The STA2 and MEL1 genes of Saccharomyces cerevisiae are idiomorphic (1993)
    Springer
    Current genetics 23 (1993), S. 92-94 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Gene mapping ; Idiomorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The STA2 (glucoamylase) gene of Saccharomyces cerevisiae has been mapped close to the end of the left arm of chromosome II. Meiotic analysis of a cross between a haploid strain containing STA2, and another strain carrying the melibiase gene MEL1 (which is known to be at the end of the left arm of chromosome II) produced parental ditype tetrads only. Since there is no significant DNA sequence similarity between the STA2 and MEL1 genes, or their respective flanking regions, we conclude that these two genes are carried by separate non-hybridizing sequences of chromosomal DNA, either of which can reside at the end of the left arm of chromosome II. By analogy with the mating-type locus of Neurospora crassa, we suggest that the STA2 and MEL1 genes are idiomorphs with respect to one another.
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    URL: http://dx.doi.org/10.1007/BF00336753
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  • 98
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    Molecular cloning of the yeast OPI3 gene as a high copy number suppressor of the cho2 mutation (1993)
    Springer
    Current genetics 23 (1993), S. 95-101 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Phospholipid synthesis ; Phospholipid-N-methyltransferase ; Mutant ; Over-expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By functional complementation of the auxotrophic requirements for choline of a cdg1, cho2 double-mutant, by transformation with a genomic DNA library in a high copy number plasmid, two different types of complementing DNA inserts were identified. One type of insert was earlier shown to represent the CHO2 structural gene. In this report we describe the molecular and biochemical characterization of the second type of complementing activity. The transcript encoded by the cloned gene was about 1000-nt in length and was regulated in response to the soluble phospholipid precursors, inositol and choline. A gene disruption resulted in no obvious growth phenotype at 23°C or 30°C, but in a lack of growth at 37°C in the presence of monomethylethanolamine. Null-mutants exhibited an inositol-secretion phenotype, indicative of mutations in the lipid biosynthetic pathway. Complementation analysis, biochemical analysis of the phospholipid methylation pathway in vivo, and comparison of the restriction pattern of the cloned gene to published sequences, unequivocally identified the cloned gene as the OPI3 gene, encoding phospholipid-N-methyltransferase in yeast. When present in multiple copies the OPI3 gene efficiently suppresses the phospholipid methylation defect of a cho2 mutation. As a result of impaired synthesis of phosphatidylcholine, the INO1-deregulation phenotype is abolished in cho2 mutants transformed with the OPI3 gene on a high copy number plasmid. Taken together, these data demonstrate a significantly overlapping specificity of the OPI3 gene product for three sequential phospholipid methylation reactions in the de novo Ptd-Cho biosynthetic pathway.
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    URL: http://dx.doi.org/10.1007/BF00352006
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  • 99
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    Epitope-tagging vectors designed for yeast (1993)
    Springer
    Current genetics 23 (1993), S. 181-183 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; c-myc epitope ; Fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to facilitate the process of epitope-tagging of yeast proteins, we have constructed two Saccharomyces cerevisiae-Escherichia coli shuttle vectors that allow fusion of a sequence encoding an epitope of the human c-myc protein at the 3′ end of any gene. An example of the use of this technique is presented.
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    URL: http://dx.doi.org/10.1007/BF00352019
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  • 100
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    Genetic and molecular analysis of REC114, an early meiotic recombination gene in yeast (1993)
    Springer
    Current genetics 23 (1993), S. 295-304 
    Details
    ISSN: 1432-0983
    Keywords: Meiosis ; Meiotic recombination ; Saccharomyces cerevisiae ; REC114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four new meiotic recombination genes were previously isolated by selecting for mutations that rescue the meiotic lethality of rad52 spo13 strains. One of these genes, REC114, is described here, and the data confirm that REC114 is a meiosis-specific recombination gene with no detectable function in mitosis. REC114 is located on chromosome XIII approximately 4,9 cM from CIN4. The nucleotide sequence reveals an open reading frame of 1262 bp, consensus intron splice sites close to the 3′ end, and indicates that the second exon codes for only seven amino acids. In the promoter region, a URS1 consensus sequence (TGGGCGGCTA), identical to the URS1 found in the promoter of SPO16, is present 93 bp upstream of the translation start site. Northern-blot hybridization demonstrates that REC114 is transcribed only during meiosis and that it is not expressed in the absence of the IME1 gene product, even when IME2 is constitutively expressed.
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    URL: http://dx.doi.org/10.1007/BF00310890
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