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  • photosynthesis  (88)
  • Saccharomyces cerevisiae  (81)
  • Springer  (169)
  • American Meteorological Society
  • 1995-1999  (85)
  • 1990-1994  (84)
  • 1940-1944
  • 1998  (85)
  • 1990  (84)
  • 1941
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  • 1995-1999  (85)
  • 1990-1994  (84)
  • 1940-1944
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  • 1
    Electronic Resource
    Electronic Resource
    The OGD1 gene, affecting 2-oxoglutarate dehydrogenase in S. cerevisiae, is closely linked to HIS5 on chromosome IX (1990)
    Springer
    Current genetics 17 (1990), S. 85-88 
    Details
    ISSN: 1432-0983
    Keywords: 2-oxoglutarate dehydrogenase ; Saccharomyces cerevisiae ; rad52-mediated chromosome loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ogd1 mutants of Saccharomyces cerevisiae are deficient in mitochondrial 2-oxoglutarate dehydrogenase activity; they cannot grow on glycerol and produce an increased amount of organic acids during growth on glucose as substrate. Using gamma ray-induced rad52-mediated chromosome loss the ogd1 mutation can be assigned to chromosome IX. Tetrad analysis of crosses between ogd1 and other markers on chromosome IX revealed that the OGD1 gene maps on the left arm of this chromosome 1.9 cM from his5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313254
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  • 2
    Electronic Resource
    Electronic Resource
    Cloning and sequencing of URA10, a second gene encoding orotate phosphoribosyl transferase in Saccharomyces cerevisiae (1990)
    Springer
    Current genetics 17 (1990), S. 105-111 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Orotate phosphoribosyl transferase ; Nucleotide sequence-5-phosphoribosyl 1-pyrophosphate (5PRPP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Orotate phosphoribosyl transferase (OPRTase) catalyses the transformation of orotate to OMP in the pyrimidine pathway. In the yeast Saccharomyces cerevisiae, the URA5 gene is known to encode this enzyme activity. In this paper we present the cloning and sequencing of a yeast gene, named URA10, encoding a second OPRTase enzyme. Comparison of the predicted amino acid sequences between URA5 and URA10 genes shows more than 75% similarity. These sequences have also been compared to those of Escherichia coli, Podospora anserina, Sordaria macrospora and Dictyostelium discoideum. Remarkable similarities in the primary structure of these proteins have been found. Gene disruption experiments revealed that URA10 gene expression is responsible for the leaky phenotype of a ura5 mutant. Assays of OPRTase activity in extracts from ura5 and ura10 mutants indicate that the URA10 product contributes only 20% of the total activity found in wild type cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312853
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation and properties of yeast mutants affected in farnesyl diphosphate synthetase (1990)
    Springer
    Current genetics 18 (1990), S. 41-46 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mutants ; Farnesyl diphosphate synthetase ; Ergosterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two yeast mutant strains auxotrophic for ergosterol and blocked in farnesyl diphosphate synthetase (EC 2.5.1.1) were isolated. Genetic analysis has shown that these mutant strains carry additional mutations in the ergosterol pathway besides erg20-1 and erg20-2 which affect FPP synthetase. The novel feature of these mutants is their ability to excrete prenyl alcohols (farnesol and geraniol). As geraniol is toxic for yeast cells, the above leaky mutations in FPP synthetase have to be associated with others in the sterol pathway, in order to slow down geraniol synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321113
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  • 4
    Electronic Resource
    Electronic Resource
    Expression of the Aspergillus niger glucose oxidase gene in A. niger, A. nidulans and Saccharomyces cerevisiae (1990)
    Springer
    Current genetics 18 (1990), S. 531-536 
    Details
    ISSN: 1432-0983
    Keywords: Glucose oxidase ; Aspergillus ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report the cloning of the Aspergillus niger glucose oxidase gene and its use to elevate glucose oxidase productivity in A. niger by increasing the gene dosage. In addition, the gene has been introduced into A. nidulans where it provides the novel capacity to produce glucose oxidase. A plasmid, in which DNA encoding the mature form of glucose oxidase was preceded by a Saccharomyces cerevisiae secretion signal, effected high-level production of extracellular glucose oxidase in this yeast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327024
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of chromosome loss on the leavening ability of Saccharomyces cerevisiae in dough (1990)
    Springer
    Current genetics 18 (1990), S. 401-403 
    Details
    ISSN: 1432-0983
    Keywords: Baking yeast ; Saccharomyces cerevisiae ; Dough leavening ; Benomyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To investigate the leavening ability of yeast in dough, chromosome loss was induced by benomyl treatment in YOY1037, a diploid between a baking strain and a laboratory strain, and its effect on the leavening ability was studied. When benomyl-treated cells were spread on plates with a dye indicator for ploidy, about 20% of the visible colonies were stained dark blue or dark purple; the rest stained pale blue, similar to the diploid YOY1037. Strains showing the MATα phenotype, and non-galactose fermenting strains, apparently having lost particular chromosomes, were observed only in those with darkcoloured colonies. Strains with dark-coloured colonies showed a wider range of leavening ability than did those with pale-coloured colonies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00309908
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  • 6
    Electronic Resource
    Electronic Resource
    Isolation and characterization of the Pichia stipitis xylitol dehydrogenase gene, XYL2, and construction of a xylose-utilizing Saccharomyces cerevisiae transformant (1990)
    Springer
    Current genetics 18 (1990), S. 493-500 
    Details
    ISSN: 1432-0983
    Keywords: Xylitol dehydrogenase gene ; Pichia stipitis ; Saccharomyces cerevisiae ; Xylose utilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A P. stipitis cDNA library in λgt11 was screened using antisera against P. stipitis xylose reductase and xylitol dehydrogenase, respectively. The resulting cDNA clones served as probes for screening a P. stipitis genomic library. The genomic XYL2 gene was isolated and the nucleotide sequence of the 1089 bp structural gene, and of adjacent non-coding regions, was determined. The XYL2 open-reading frame codes for a protein of 363 amino acids with a predicted molecular mass of 38.5 kDa. The XYL2 gene is actively expressed in S. cerevisiae transformants. S. cerevisiae cells transformed with a plasmid, pRD1, containing both the xylose reductase gene (XYL1) and the xylitol dehydrogenase gene (XYL2), were able to grow on xylose as a sole carbon source. In contrast to aerobic glucose metabolism, S. cerevisiae XYL1-XYL2 transformants utilize xylose almost entirely oxidatively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00327019
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  • 7
    Electronic Resource
    Electronic Resource
    A recessive mutant allele of the HNM1 gene of Saccharomyces cerevisiae is responsible for hyper-resistance to nitrogen mustard (1990)
    Springer
    Current genetics 18 (1990), S. 187-192 
    Details
    ISSN: 1432-0983
    Keywords: Mutagen hyper-resistance ; Nitrogen mustard ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A screening of haploid yeast strains for enhanced resistance to nitrogen mustard (HN2) yielded a recessive mutant allele, hnm1, that conferred hyper-resistance (HYR) to HN2. Diploids, homo- or heterozygous for the HNM1 locus, exhibit normal wild-type like resistance while homozygosity for hnm1 leads to the phenotype HYR to HN2. The hnm1 mutation could be found in yeast strains proficient or deficient in different DNA repair systems. In these mostly HN2-sensitive haploid repair-deficient mutants, hnm1 acted as a partial suppressor of HN2 sensitivity. All isolated recessive mutations conferring hyper-resistance belonged to a single complementations group. The HYR to HN2 phenotype was maximally expressed in growing cells and was associated with reduced mutability by HN2. HNM1 most probably controls uptake of HN2 which would be impaired in the hnm1 mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318378
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  • 8
    Electronic Resource
    Electronic Resource
    G418-resistance as a dominant marker and reporter for gene expression in Saccharomyces cerevisiae (1990)
    Springer
    Current genetics 18 (1990), S. 303-313 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; G418 resistance ; Gene cartridges ; Heterologous Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Coding sequence cartridges for aminoglycoside phosphotransferase (APT) were isolated from bacterial transposon Tn903. When incorporated into a heterologous gene construction utilising the PGK1 promoter and terminator, the heterologous APT gene provided a G418-resistance determinant that functioned efficiently as a dominant marker for yeast in both multiple- and single-copy. Transformant colonies on selective medium appeared rapidly, within 36–48 h, and growth rate of the transformed cells was normal. A simple and highly sensitive radiolabelling assay for APT enzyme activity was developed for use with crude cell protein extracts. Enzyme activity units were equated to the amount of APT protein present in the cells, and the APT protein was shown to be stable in yeast. Heterologous APT expression was 130-fold reduced compared with homologous PGK1. This resulted from an estimated two-fold decrease in mRNA level and a 65-fold decrease in translation efficiency. The latter was unaffected by AUG sequence context change, but corresponded with a high frequency of minor codons in the APT-coding sequence. APT can be used as a semi-quantitative reporter of gene expression, whose useful features are in vivo detection via the G418-resistance phenotype and powerful cell-free assay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318211
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  • 9
    Electronic Resource
    Electronic Resource
    When a glycolytic gene on a yeast 2μORI-STB plasmid is made essential for growth its expression level is a major determinant of plasmid copy number (1990)
    Springer
    Current genetics 17 (1990), S. 119-123 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Episomal plasmid ; Copy number control ; Plasmid maintenance ; Glycolytic enzyme levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study demonstrates how varying the promoter strength of an essential gene on a yeast 2μORI-STB YEp multicopy vector can influence vector copy levels. A phosphoglycerate kinase gene (PGK) on this plasmid was made essential for fermentative growth by transformation into a pgk - yeast strain. When in these PGK- transformants the requirement for PGK expression was the sole selective criterion for plasmid maintenance, PGK promoter activity was inversely related to vector copy levels. Plasmids with an efficiently-transcribed PGK gene were maintained at approximately one copy per cell, whereas those lacking the UAS that normally directs high basal PGK transcription levels were present at up to 10–15 copies. All cultures of these PGK+ transformants contained only a low proportion of pgk - cells. Since mitotic loss of the plasmid arrests growth through loss of a functional PGK allele, PGK confers high stability to the YEp vector in such a pgk - genetic background. In this system YEp vector levels are probably influenced by PGK transcription because high expression of PGK is needed in rapid fermentative growth. Remarkably, low plasmid PGK promoter activity caused PGK mRNA levels slightly higher than those found in yeast with normal PGK regulation. A higher plasmid copy number is therefore not the only factor counteracting the effects of low PGK transcription, and it is possible that PGK mRNA becomes more stable in response to inefficient PGK transcription.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312855
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  • 10
    Electronic Resource
    Electronic Resource
    Functional analysis of the sporulation-specific SPR6 gene of Saccharomyces cerevisiae (1990)
    Springer
    Current genetics 18 (1990), S. 293-301 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Sporulation ; Inessential genes ; Genome organization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The SPR6 gene of Saccharomyces cerevisiae encodes a moderately abundant RNA that is present at high levels only during sporulation. The gene contains a long open reading frame that could encode a hydrophilic protein approximately 21 kDa in size. This protein is probably produced by the yeast, because the lacZ gene of Escherichia coli is expressed during sporulation when fused to SPR6 in the expected reading frame. SPR6 is inessential for sporulation; mutants that lack SPR6 activity sporulate normally and produce viable ascospores. Nonetheless, the SPR6 gene encodes a function that is relevant to sporulating cells; the wild-type allele can enhance sporulation in strains that are defective for several SPR functions. SPR6 is located on chromosome V, 14.4 centimorgans centromere-distal to MET6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318210
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  • 11
    Electronic Resource
    Electronic Resource
    Interactions between the yeast mitochondrial and nuclear genomes: isogenic suppressive and hypersuppressive petites differ in their resistance to the alkaloid lycorine (1990)
    Springer
    Current genetics 17 (1990), S. 455-457 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Nucleo-mitochondrial interactions ; Mitochondrial status ; Lycorine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In a previous paper we have shown that the alkaloid lycorine inhibits growth of rho +, mit - and rho -, strains of Saccharomyces cerevisiae, whereas strains devoid of mitochondrial DNA (rho o) are resistant to more than 200 μg/ml of the alkaloid. In this report we show that hypersuppressive petites are almost as resistant as rho o mutants, whereas isogenic rho - petites, which have retained tained longer segments of the genome, are sensitive to the drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334527
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  • 12
    Electronic Resource
    Electronic Resource
    Evolutionary conservation of transcriptional machinery between yeast and plants as shown by the efficient expression from the CaMV 35S promoter and 35S terminator (1990)
    Springer
    Current genetics 17 (1990), S. 473-479 
    Details
    ISSN: 1432-0983
    Keywords: Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; CaMV 35S promoter ; CaMV 35S terminator ; Heterologous expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Complementation of fission yeast mutants by plant genomic libraries could be a promising method for the isolation of novel plant genes. One important prerequisite is the functioning of plant promoters and terminators in Schizosaccharomyces pombe and Saccharomyces cerevisiae. Therefore, we studied the expression of the bacterial β-glucuronidase (GUS) reporter gene under the control of the Cauliflower Mosaic Virus (CaMV) 35S promoter and 35S terminator. We show here that S. pombe initiates transcription at exactly the same start site as was reported for tobacco. The 35S CaMV terminator is appropriately recognized leading to a polyadenylated mRNA of the same size as obtained in plant cells transformed with the same construct. Furthermore, the GUS-mRNA is translated into fully functional GUS protein, as determined by an enzymatic assay. Interestingly, expression of the 35S promoter in the budding yeast S. cerevisiae was found to be only moderate and about hundredfold lower than in S. pombe. To investigate whether different transcript stabilities are responsible for this enormous expression difference in the two yeasts, the 35S promoter was substituted by the ADH (alcohol dehydrogenase) promoter from fission yeast. In contrast to the differential expression pattern of the 35S promoter, the ADH promoter resulted in equally high expression rates in both fission and budding yeast, comparable to the 35S promoter in S. pombe. Since the copy number of the 35S-GUS constructs differs only by a factor of two in the two yeasts, it appears that differential recognition of the 35S promoter is responsible for the different transcription rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313074
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  • 13
    Electronic Resource
    Electronic Resource
    The absence of introns in yeast mitochondria does not abolish mitochondrial recombination (1990)
    Springer
    Current genetics 17 (1990), S. 537-541 
    Details
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Mitochondria ; Intron-encoded proteins ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The respiratory competency of a yeast strain devoid of mitchondrial introns is quite normal. However, it may be asked whether intron-encoded proteins participate in metabolisms other than those of mitochondrial introns. Using strains without mitochondrial introns we have answered two questions. The first was: does the absence of intron-encoded proteins abolsh mitochondrial recombination? The second was: do mitochondrial introns and intron-encoded proteins play a part in mitochondrial DNA rearrangements induced by ethidium bromide (rho- production)? We have shown that the introns and intron-encoded proteins are not essential essential components of either phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00313085
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  • 14
    Electronic Resource
    Electronic Resource
    Fate of highly expressed proteins destined to peroxisomes in Saccharomyces cerevisiae (1990)
    Springer
    Current genetics 18 (1990), S. 23-27 
    Details
    ISSN: 1432-0983
    Keywords: Protein translocation ; Saccharomyces cerevisiae ; Peroxisomes ; Overexpression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Import of proteins into organelles usually requires a cis-acting targeting signal. Analysis of various hybrid proteins, consisting of mouse DHFR and parts of catalase A from Saccharomyces cerevisiae, revealed that fusion proteins containing the N-terminal 126 amino acids, or less, of catalase A remain in the cytosol whereas fusion proteins containing 140, or more, N-terminal amino acids of catalase A form large aggregates inside the cell. These protein bodies, which lack a surrounding membrane, copurified with peroxisomes on cell fractionation. The peroxisomal targeting signal of catalase A does not reside at the C-terminus or at the N-terminus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00321111
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  • 15
    Electronic Resource
    Electronic Resource
    Effect of nystatin, amphotericin B and amphotericin B methyl ester on Saccharomyces cerevisiae with different lipid composition (1990)
    Springer
    Mycopathologia 112 (1990), S. 165-172 
    Details
    ISSN: 1573-0832
    Keywords: Nystatin ; amphotericin B ; amphotericin B methyl ester ; polyene antibiotics ; yeast ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Saccharomyces cerevisiae was cultured under anaerobiosis in semi-complete medium to which either palmitoleic or oleic acid was added. Cells were grown at 20 °C or 30 °C. The levels of total lipids, total sterols, and phospholipids were higher in cells grown at 20 °C than at 30 °C. The effects of nystatin (NYS), amphotericin B (AMB), and amphotericin B methyl ester (AME) were evaluated by determining cell viability and liberation of intracellular compounds. The loss of cell viability is higher in the first 30 minutes of incubation with the drugs and is the same regardless of the type of cells obtained. Low molecular weight compounds and ions such as K+ are liberated a few minutes after incubation with the drugs whereas proteins and substances absorbing at 260 nm are liberated later. Phosphate liberation comes after K+ and before compounds of higher molecular weights.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00436649
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  • 16
    Electronic Resource
    Electronic Resource
    Cloning and sequence analysis of Histoplasma capsulatum glucosamine-6-phosphate synthase gene fragment (1998)
    Springer
    Mycopathologia 142 (1998), S. 67-70 
    Details
    ISSN: 1573-0832
    Keywords: l-glutamine ; fructose-6-phosphate amidotransferase ; Candida albicans ; fungi ; Saccharomyces cerevisiae ; Schizosaccharomyces pombe ; systemic mycoses chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The 3' part of the glucosamine-6-phosphate synthase gene from Histoplasma capsulatum was PCR amplified using degenerate primers designed from the known glucosamine-6-phosphate synthase gene sequences, cloned and sequenced. The computer analysis of the 676 bp sequence revealed the presence of two introns. The identities of the deduced amino acid sequence to the corresponding Saccharomyces cerevisiae and Candida albicans fragment are 65 and 63.8%, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006900321524
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  • 17
    Electronic Resource
    Electronic Resource
    Determination of the role of polyphosphate in transport-coupled phosphorylation in the yeast Saccharomyces cerevisiae (1990)
    Springer
    Antonie van Leeuwenhoek 57 (1990), S. 159-164 
    Details
    ISSN: 1572-9699
    Keywords: 2-Deoxy-D-glucose transport ; polyphosphate ; Saccharomyces cerevisiae ; sugar phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of polyphosphate in 2-deoxy-D-glucose transport was studied in yeast cells, pulse-labeled with [32P]orthophosphate, by comparing the concentrations and specific activities of polyphosphate, orthophosphate and 2-dGlc-phosphate. When 2-dGlc transport was measured under aerobic conditions, it appeared that polyphosphate replenished the orthophosphate pool, indicating that polyphosphate has, at least mainly, an indirect role in sugar phosphorylation. Also in cells with a reduced respiratory capacity, due to a treatment with antimycin A, no direct role for polyphosphate in 2-dGlc transport could be detected. Under these conditions, only a very limited breakdown of polyphosphate occurred, probably because of the small decrease in the orthophosphate concentration.
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    URL: http://dx.doi.org/10.1007/BF00403950
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  • 18
    Electronic Resource
    Electronic Resource
    Effect of a Teucrium polium L. extract on the growth and fatty acid composition of Saccharomyces cerevisiae and Yarrowia lipolytica (1998)
    Springer
    Antonie van Leeuwenhoek 73 (1998), S. 195-198 
    Details
    ISSN: 1572-9699
    Keywords: growth inhibition ; fatty acid composition ; Saccharomyces cerevisiae ; Yarrowia lipolytica ; Teucrium polium L. extract
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Aqueous Teucrium polium extract slightly inhibits the growth of Saccharomyces cerevisiae (Ki=0.029 [g/l]-1) and Yarrovia lipolytica (Ki=0.061 [g/l]-1). However, this extract causes important changes in the unsaturation degree (Δ/mol) of the cellular lipids. It moreover favours the increase of the linolenic acid concentration and the decrease of the oleic one in both species.
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    URL: http://dx.doi.org/10.1023/A:1000673426077
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  • 19
    Electronic Resource
    Electronic Resource
    Field measurements of gas exchange in Avicennia marina and Bruguiera gymnorrhiza (1998)
    Springer
    Mangroves and salt marshes 2 (1998), S. 99-107 
    Details
    ISSN: 1572-977X
    Keywords: conductance ; mangrove ; photosynthesis ; productivity ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diurnal gas exchange characteristics were measured simultaneously in two mangrove species, Avicennia marina and Bruguiera gymnorrhiza, over 7 d in summer (February–March), to compare their productivity. The study was undertaken in the Beachwood Mangroves Nature Reserve, Durban, South Africa, using fully expanded leaves of young and mature trees at the top of the canopy. Gas exchange was strongly influenced by photosynthetic photon flux density (PPFD), leaf temperature and the accompanying leaf to air vapour pressure deficit (Δ w). Carbon dioxide exchange was saturated at a PPFD of about 600 μmol m-2s-1 in B. gymnorrhiza compared to 800 μmol m-2s-1 in A. marina. Maximal CO2 exchange occurred between 12h00 and 14h00 and was consistently greater in A. marina (8.8 μmol m-2s-1) than in B. gymnorrhiza (5.3 mu;mol m-2s-1). Mean internal CO2 concentrations ( ci) were 260 μl l-1 in A. marina and 252 μl l-1 in B. gymnorrhiza. Photorespiratory activity was 32% in A. marina and 30% in B. gymnorrhiza. Mean water use efficiency (WUE) was 8.0 μmol mmol-1 in A. marina and 10.6 μmol mmol-1 in B. gymnorrhiza. Diurnal leaf water potentials ranged from –0.8 to –3.5 MPa and were generally lower in A. marina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009939523164
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  • 20
    Electronic Resource
    Electronic Resource
    Mangrove forest productivity and biomass accumulation in Hinchinbrook Channel, Australia (1998)
    Springer
    Mangroves and salt marshes 2 (1998), S. 191-198 
    Details
    ISSN: 1572-977X
    Keywords: canopy ; Hinchinbrook ; leaf area index ; mangrove ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Data on stand structure and rates of photosynthesis were used to estimate net canopy carbon fixation and carbon accumulation as living biomass in mangrove forests in Hinchinbrook Channel, Australia. Total annual canopy net carbon fixation was estimated to be about 29 t C ha−1 yr−1. This equates to about 204,000 t C yr−1 for all mangrove forests in Hinchinbrook Channel. Of this, only about 12% was stored as living plant biomass. Although it is not yet possible to present a robust carbon balance for mangrove trees, the remainder is presumably lost through plant respiration, litter fall, root turnover and exudation of organic compounds from roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009979610871
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  • 21
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    Genetic and molecular approaches to synthesis and action of the yeast killer toxin (1990)
    Springer
    Cellular and molecular life sciences 46 (1990), S. 193-200 
    Details
    ISSN: 1420-9071
    Keywords: Saccharomyces cerevisiae ; protein toxin ; yeast toxin precursor ; protease processing ; lectin ; (1→6)-β-D-glucan ; receptor ; resistant mutants ; spheroplasts ; ion-permeable channels ; site-directed mutagenesis ; toxin functional domains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The K1 killer toxin ofSaccharomyces cerevisiae is a secreted, virally-coded protein lethal to sensitive yeasts. Killer yeasts are immune to the toxin they produce. This killer system has been extensively examined from genetic and molecular perspectives. Here we review the biology of killer yeasts, and examine the synthesis and action of the protein toxin and the immunity component. We summarise the structure of the toxin precursor gene and its protein products, outline the proteolytic processing of the toxin subunits from the precursor, and their passage through the yeast secretory pathway. We then discuss the mode of action of the toxin, its lectin-like interaction with a cell wall glucan, and its probable role in forming channels in the yeast plasma membrane. In addition we describe models of how a toxin precursor species functions as the immunity component, probably by interfering with channel formation. We conclude with a review of the functional domains of the toxin structural gene as determined by site-directed mutagenesis. This work has identified regions associated with glucan binding, toxin activity, and immunity.
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    URL: http://dx.doi.org/10.1007/BF02027313
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  • 22
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    Expression of HIV-1nefin yeast causes membrane perturbation and release of the myristylated Nef protein (1998)
    Springer
    Journal of biomedical science 5 (1998), S. 203-210 
    Details
    ISSN: 1423-0127
    Keywords: Acquired immunodeficiency syndrome ; Human immunodeficiency virus ; Nef protein ; Myristylation ; Membrane permeabilisation ; Saccharomyces cerevisiae ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The human immunodeficiency virus type 1 (HIV-1) Nef protein is essential for AIDS pathogenesis, but its function remains highly controversial. During stresses such as growth in the presence of copper or at elevated temperature, myristylated Nef is released from yeast cells and, after extended culture in stationary phase, it accumulates in the supernatant as a dense membranous material that can be centrifuged into a discrete layer above the cell pellet. This material is unique to Nef-producing cells and represents a convenient source of Nef that may have application in further biological studies. Within the yeast cell, electron microscopic examination shows that Nef localises in novel, membrane-bound bodies. These data support the evidence for a role of Nef in membrane perturbation and suggest that there may be a similar localisation for myristylated Nef in HIV-1 infected cells.
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    Gene-conversion tract directionality is influenced by the chromosome environment (1998)
    Springer
    Current genetics 34 (1998), S. 269-279 
    Details
    ISSN: 1432-0983
    Keywords: Key words Double-strand breaks ; Heteroduplex DNA ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Spontaneous and double-strand break (DSB)-induced gene conversion in Saccharomyces cerevisiae was assayed using non-tandem chromosomal direct repeat crosses and plasmid × chromosome crosses. Each cross involved identical ura3 alleles marked with phenotypically silent restriction fragment length polymorphic (RFLP) mutations at approximately 100-bp intervals. DSBs introduced in vivo at HO sites in one allele stimulated recombination to Ura+ by more than two orders of magnitude. Spontaneous gene-conversion products were isolated from a related strain lacking a functional HO nuclease gene. The multiple markers did not appear to influence the frequency of direct repeat deletions for spontaneous or DSB-induced events. DSB-induced conversion reflected efficient mismatch repair of heteroduplex DNA. Conversion frequencies of equidistant markers on opposites sides of the DSB were similar in the direct repeat cross. In contrast, markers 5′ of the DSB (promoter-proximal) converted more often than 3′ markers in plasmid × chromosome crosses, a possible consequence of crossing-over associated with long conversion tracts. With direct repeats, bidirectional tracts (extending 5′ and 3′ of the DSB) occurred twice as often as in a plasmid × chromosome cross in which DSBs were introduced into the plasmid-borne allele. A key difference between the direct-repeat and plasmid×chromosome crosses is that the ends of a broken plasmid are linked, whereas the ends of a broken chromosome are unlinked. We tested whether linkage of ends influenced tract directionality using a second plasmid × chromosome cross in which DSBs were introduced into the chromosomal allele and found few bidirectional tracts. Thus, chromosome environment, but not linkage of ends, influences tract directionality. The similar tract spectra of the two plasmid × chromosome crosses suggest that similar mechanisms are involved whether recombination is initiated by DSBs in plasmid or chromosomal alleles.
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    URL: http://dx.doi.org/10.1007/s002940050396
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    The Saccharomyces cerevisiae gene PSO5/RAD16 is involved in the regulation of DNA damage-inducible genes RNR2 and RNR3 (1998)
    Springer
    Current genetics 34 (1998), S. 124-127 
    Details
    ISSN: 1432-0983
    Keywords: Key wordsPSO5/RAD16 ; Saccharomyces cerevisiae ; Nucleotide excision repair ; Oxidative stress ; Ribonucleotide reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of β-galactosidase from DNA damage-inducible RNR2-lacZ and RNR3-lacZ fusion constructs was compared in wild-type (WT) and pso5/rad16 mutant strains after treatment with five mutagens/oxidative stressors. While exposure to the mutagens UVC, 4NQO and H2O2 induced expression of the RNR2-lacZ and RNR3-lacZ fusion constructs in two WT strains, treatment with the two oxidative stressors tBOOH and paraquat did not. In the pso5-1 mutant induction of RNR2-lacZ was largely reduced after UVC and H2O2 while there was no significant induction of β-galactosidase expression after 4NQO treatment for this construct. For RNR3-lacZ there was strongly reduced expression of pso5-1 after UVC and 4NQO while H2O2 failed to induce expression of β-galactosidase. In the WT strains the ranking of the inducing power of the mutagens at 90% survival (as measured in the pso5-1 mutant) was 4NQO〉UVC〉H2O2. Though the WT strains were clearly more resistant that the pso5-1 mutant to the two oxidative stressors paraquat and tBOOH, these substances failed to significantly enhance expression of the RNR2-lacZ and RNR3-lacZ fusion constructs in both the WT and the pso5-1 mutant. Our data suggest that Pso5p/Rad16p has a function in the signal transducing pathway controlling DNA damage-inducible components of nucleotide excision repair.
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    URL: http://dx.doi.org/10.1007/s002940050376
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    Azf1p is a nuclear-localized zinc-finger protein that is preferentially expressed under non-fermentative growth conditions in Saccharomyces cerevisiae (1998)
    Springer
    Current genetics 34 (1998), S. 287-296 
    Details
    ISSN: 1432-0983
    Keywords: Key words Zinc-finger protein ; Nuclear localization ; Immuno electron microscopy ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In previous studies the AZF1 gene has been identified as a second high-copy number suppressor for a special mutant of the gene for the mitochondrial core enzyme of RNA polymerase. The first high-copy number suppressor of this mutant turned out to be the specificity factor MTF1 for mitochondrial transcription. Up to now, the influence of AZF1 on mitochondrial transcription, its precise localization in the cell and the regulation of its expression has not been determined. The putative protein contains a long stretch of poly-asparagine amino acids and a typical zinc-finger domain for DNA binding. These characteristic structural features were used to create the abbreviation AZF1 (Asparagine-rich Zinc Finger protein). An initial computer analysis of the sequence gave no conclusive results for the presence of a mitochondrial import sequence or a typical nuclear-targeting sequence. A recent more-detailed analysis identified a possible nuclear localization signal in the middle of the protein. Disruption of the gene shows no effect on plates with glucose-rich medium or glycerol. In this report a specific polyclonal antibody against Azf1p was prepared and used in cell-fractionation experiments and in electron-microscopic studies. Both of these clearly demonstrate that the AZF1 protein is localized exclusively in the nucleus of the yeast cell. Northern analysis for the expression of the AZF1 messenger RNA under different growth conditions was therefore performed to obtain new insights into the regulation of this gene. Together with the respective protein-expression analysis these data demonstrate that Azf1p is preferentially synthezised in higher amounts under non-fermentable growth conditions. Over-expression of Azf1p in the yeast cell does not influence the expression level of the mitochondrial transcription factor Mtf1p, indicating that the influence of Azf1p on the suppression of the special mitochondrial RNA polymerase mutant is an indirect one. Subcellular investigation of the deletion mutant by electron microscopy identifies specific ultrastructural cell-division defects in comparison to the wild-type.
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    URL: http://dx.doi.org/10.1007/s002940050398
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    Mitotic recombination and localized DNA double-strand breaks are induced after 8-methoxypsoralen and UVA irradiation in Saccharomyces cerevisiae (1998)
    Springer
    Current genetics 34 (1998), S. 30-42 
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    ISSN: 1432-0983
    Keywords: Key words Mitotic recombination ; DNA double-strand breaks ; Saccharomyces cerevisiae ; 8-Methoxypsoralen plus UVA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitotic recombination within the ARG4 gene of Saccharomyces cerevisiae was analysed after treatment of cells with the recombinogenic agent 8-methoxypsoralen (8-MOP) plus UVA. The appearance of DNA double-strand breaks (DSBs) in the ARG4 region during post-treatment incubation was also tested. The results obtained after 8-MOP plus UVA treatment indicate that in mitotic cells: (1) recombination at the ARG4 locus is increased 30 – 500 fold per survivor depending on the strains and the doses employed, (2) the increase of recombination results essentially from gene conversion events which involve the RV site located in the 5′ region of the ARG4 gene twice as often as the Bgl site at the 3′ end, (3) depending on 8-MOP/UVA dose, ectopic gene conversion is associated with reciprocal translocation, (4) DSBs occur preferentially in the ARG 5′ region during post-treatment incubation, as well as in other intergenic regions containing both promoters or/and terminators of transcription, and (5) changes in sequence content in the 5′ region of ARG4, which influences positions and frequencies of DSBs formed during repair, are correlated with a modification of the local chromatin structure.
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    Reciprocal translocation at duplicated RPL2 loci might cause speciation of Saccharomyces bayanus and Saccharomyces cerevisiae (1998)
    Springer
    Current genetics 33 (1998), S. 345-351 
    Details
    ISSN: 1432-0983
    Keywords: Key wordsSaccharomyces bayanus ; Saccharomyces cerevisiae ; Translocation ; Speciation ; Duplicated gene ; RPL2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By a genomic comparison of two sibling yeasts, Saccharomyces bayanus and S. cerevisiae, we previously demonstrated that chromosomes II and IV of S. cerevisiae were rearranged into chromosomes 12 and 14 of S. bayanus or vice versa. In the present study we have delimited the translocation break sites in chromosomes II and IV by Southern hybridization using DNA fragments of S. cerevisiae cosmid clones as probes. The results suggest that the reciprocal translocation of chromosomes II and IV had occurred at duplicated RPL2 loci. Furthermore, the translocation sites in S. bayanus were confirmed by the cloning and sequence analysis of the regions flanking RPL2 loci. Several genes in the regions flanking the RPL2 loci were present in the order expected for a translocation at these loci between the two species. These results indicated that the reciprocal translocation between chromosomes II and IV was generated by homologous recombination at duplicated RPL2 loci on the two chromosomes. Therefore, we propose that duplicated genes or duplicated regions play an important role in altering genomic organization during the speciation of S. bayanus and S. cerevisiae.
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    Functional analysis of upstream activating elements in the promoter of the FBP1 gene from Saccharomyces cerevisiae (1998)
    Springer
    Current genetics 33 (1998), S. 406-411 
    Details
    ISSN: 1432-0983
    Keywords: Key words Fructose-1 ; 6-bisphosphatase ; Catabolite repression ; Gluconeogenesis ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have investigated the effect of different carbon sources and of different mutations on the capacity of two elements, UAS1 and UAS2, from the promoter of the FBP1 gene to form specific DNA-protein complexes and to activate expression of a reporter gene. The complexes are observed with nuclear extracts from yeast derepressed on glycerol or ethanol. When hxk2 mutants are grown on glucose the nuclear extracts are able to complex UAS1 but not UAS2, while for wild-type cells grown on galactose only the complex with UAS2 is formed. In contrast, in vivo the operation of both UASs is high in ethanol, moderate to low in glycerol, and negligible in galactose; no expression is observed in glucose even in a hxk2 background. There is no effect of a MIG1 deletion, either in the formation of DNA-protein complexes or on the expression of reporter genes.
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    Molecular and biochemical analysis of Saccharomyces cerevisiae cox1 mutants (1998)
    Springer
    Current genetics 34 (1998), S. 138-145 
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    ISSN: 1432-0983
    Keywords: Key words Cytochrome c oxidase ; Saccharomyces cerevisiae ; Complex assembly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report on the molecular and biochemical analysis of a set of 13 respiratory deficient mutants of Saccharomyces cerevisiae which are specifically altered in COX1, the gene encoding the subunit Cox1p of cytochrome c oxidase. DNA sequence analysis shows that three are due to frameshift mutations, two to nonsense mutations, and eight to missense mutations. All, except the missense mutant S157L, have impaired electron transfer and respiratory activity. Analysis of the mitochondrial translation products shows that when Cox1p is absent, Cox2p and Cox3p are still synthesized. In the missense mutants, the steady state levels in the mitochondrial membranes of the three mitochondrially encoded subunits Cox1p, Cox2p and Cox3p and the nuclear-encoded subunit Cox4p are reduced. In the frameshift and nonsense mutants, Cox1p is absent and Cox2p, Cox3p and Cox4p are considerably decreased or undetectable. A comparison of the steady state levels of Cox1p through Cox4p in the COX1, COX2, COX3 and COX4 mutants shows the interdependance of the accumulation of these four subunits in the mitochondrial membranes.
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    Purification and characterization of a (R)-2,3-butanediol dehydrogenase from Saccharomyces cerevisiae (1990)
    Springer
    Archives of microbiology 154 (1990), S. 267-273 
    Details
    ISSN: 1432-072X
    Keywords: Yeast ; Saccharomyces cerevisiae ; (R)-2,3-Butanediol dehydrogenase ; Stereospecificity ; Gas chromatographic analysis of enantiomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A NAD-dependent (R)-2,3-butanediol dehydrogenase (EC 1.1.1.4), selectively catalyzing the oxidation at the (R)-center of 2,3-butanediol irrespective of the absolute configuration of the other carbinol center, was isolated from cell extracts of the yeast Saccharomyces cerevisiae. Purification was achieved by means of streptomycin sulfate treatment, Sephadex G-25 filtration, DEAE-Sepharose CL-6B chromatography, affinity chromatography on Matrex Gel Blue A and Superose 6 prep grade chromatography leading to a 70-fold enrichment of the specific activity with 44% yield. Analysis of chiral products was carried out by gas chromatographic methods via pre-chromatographic derivatization and resolution of corresponding diasteromeric derivatives. The enzyme was capable to reduce irreversibly diacetyl (2,3-butanediol) to (R)-acetoin (3-hydroxy-2-butanone) and in a subsequent reaction reversibly to (R,R)-2,3-butanediol using NADH as coenzyme. 1-Hydroxy-2-ketones and C5-acyloins were also accepted as substrates, whereas the enzyme was inactive towards the reduction of acetone and dihydroxyacetone. The relative molecular mass (M r) of the enzyme was estimated as 140 000 by means of gel filtration. On SDS-polyacrylamide gel the protein decomposed into 4 (identical) subunits of M r 35 000. Optimum pH was 6.7 for the reduction of acetoin to 2,3-butanediol and 7.2 for the reverse reaction.
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    Absence of glucose-induced cAMP signaling in the Saccharomyces cerevisiae mutants cat1 and cat3 which are deficient in derepression of glucose-repressible proteins (1990)
    Springer
    Archives of microbiology 154 (1990), S. 199-205 
    Details
    ISSN: 1432-072X
    Keywords: cAMP ; Cat mutants ; Glucose repression ; Glucose-induced ; Intracellular pH ; Ras ; Saccharomyces cerevisiae ; Signal transduction ; Trehalase ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Addition of glucose to derepressed cells of the yeast Saccharomyces cerevisiae induces a transient, specific cAMP signal. Intracellular acidification in these cells, as caused by addition of protonophores like 2,4-dinitrophenol (DNP) causes a large, lasting increase in the cAMP level. The effect of glucose and DNP was investigated in glucose-repressed wild type cells and in cells of two mutants which are deficient in derepression of glucose-repressible proteins, cat1 and cat3. Addition of glucose to cells of the cat3 mutant caused a transient increase in the cAMP level whereas cells of the cat1 mutant and in most cases also repressed wild type cells did not respond to glucose addition with a cAMP increase. The glucose-induced cAMP increase in cat3 cells and the cAMP increase occasionally present in repressed wild type cells however could be prevented completely by addition of a very low level of glucose in advance. In derepressed wild type cells this does not prevent the specific glucose-induced cAMP signal at all. These results indicate that repressed cells do not show a true glucose-induced cAMP signal. When DNP was added to glucose-repressed wild type cells or to cells of the cat1 and cat3 mutants no cAMP increase was observed. Addition of a very low level of glucose before the DNP restored the cAMP increase which points to lack of ATP as the cause for the absence of the DNP effect. These data show that intracellular acidification is able to enhance the cAMP level in repressed cells. The glucose-induced artefactual increase occasionally observed in repressed cells is probably caused by the fact that their low intracellular pH is only restored after the ATP level has increased to such an extent that it is no longer limiting for cAMP synthesis. It is unclear why the artefactual increases are not always observed. Measurement of glucose- and DNP-induced activation of trehalase confirmed the physiological validity of the changes observed in the cAMP level. Our results are consistent with the idea that the glucose-induced signaling pathway contains a glucose-repressible protein and that the protein is located before the point where intracellular acidification triggers activation of the pathway.
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    Growth of catalase A and catalase T deficient mutant strains of Saccharomyces cerevisiae on ethanol and oleic acid (1990)
    Springer
    Archives of microbiology 153 (1990), S. 513-517 
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    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Catalase A ; Catalase T ; β-Oxidation ; Microbodies ; H2O2-Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The parental strain (A+T+) of Saccharomyces cerevisiae and mutants, deficient in catalase T (A+T−), catalase A (A−T+) or both catalases (A−T−), grew on ethanol and oleic acid with comparable doubling times. Specific activities of catalase were low in glucose- and ethanol-grown cells. In the two oleic acid-grown A+-strains (A+T+ and A+T−) high catalase activities were found; catalase activity invariably remained low in the A−T+ strain and was never detected in the A−T− strain. The levels of β-oxidation enzymes in oleic acid-grown cells of the parental and all mutant strains were not significantly different. However, cytochrome C peroxidase activity had increased 8-fold in oleic acid grown A− strains (A−T+ and A−T−) compared to parental strain cells. The degree of peroxisomal proliferation was comparable among the different strains. Catalase A was shown to be located in peroxisomes. Catalase T is most probably cytosolic in nature and/or present in the periplasmic space.
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    Effects of ethanol on Saccharomyces cerevisiae as monitored by in vivo 31P and 13C nuclear magnetic resonance (1990)
    Springer
    Archives of microbiology 153 (1990), S. 384-391 
    Details
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Ethanol ; Acetic acid ; Cytoplasmic pH ; 31P-NMR ; 13C-NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell suspensions of a respiratory deficient mutant of Saccharomyces cerevisiae were monitored by in vivo 31P and 13C Nuclear Magnetic Resonance in order to evaluate the effect of ethanol in intracellular pH and metabolism. In the absence of an added energy source, ethanol caused acidification of the cytoplasm, as indicated by the shift to higher field of the resonance assigned to the cytoplasmic orthophosphate. Under the experimental conditions used this acidification was not a consequence of an increase in the passive influx of H+. With cells energized with glucose, a lower value for the cytoplasmic pH was also observed, when ethanol was added. Furthermore, lower levels of phosphomonoesters were detected in the presence of ethanol, indicating that an early event in glycolysis is an important target of the ethanol action. Acetic acid was identified as responsible for the acidification of the cytoplasm, in experiments where [13C]ethanol was added and formation of labeled acetic acid was detected. The intracellular and the extracellular concentrations of acetic acid were respectively, 30 mM and 2 mM when 0.5% (120 mM) [13C]ethanol was added.
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    Genetic mapping and biochemical analysis of mutants in the maltose regulatory gene of the MAL1 locus of Saccharomyces cerevisiae (1990)
    Springer
    Archives of microbiology 154 (1990), S. 544-549 
    Details
    ISSN: 1432-072X
    Keywords: Regulatory mutants ; Meiotic mapping ; Transcriptional regulation ; MAL genes ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The MAL1 locus of Saccharomyces cerevisiae comprises three genes necessary for maltose utilization: a regulatory (MALR), a maltose transport (MALT) and a maltase gene (MALS). A fine structure genetic map of the MAL1R gene was constructed and the order of mutations was confirmed by plasmid-mediated chromosomal recombination. The mutations cluster non-randomly within the 5′ half of the gene, where the putative DNA binding domain of the encoded protein is located. Only mutations mal1 R-22 and MAL1R-72 map in the 3′ terminal half of the gene; these mutations cause a different pattern of transcriptional regulation of plasmid-borne MAL6T genes. Experiments supporting a direct involvement of the MALR-encoded protein in carbon catabolite repression of MAL gene expression are reported.
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    Activation of the H+-ATPase in the plasma membrane of cells of Saccharomyces cerevisiae grown under mild copper stress (1998)
    Springer
    Archives of microbiology 171 (1998), S. 6-12 
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    ISSN: 1432-072X
    Keywords: Key words Plasma membrane H+-ATPase ; Saccharomyces cerevisiae ; Copper stress ; PMA1 ; PMA2 ; Gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cells of Saccharomyces cerevisiae exibited a more active plasma membrane H+-ATPase during growth in media supplemented with CuSO4 concentrations equal to or below 1 mM than did cells cultivated in the absence of copper stress. Maximal specific activities were found with 0.5 mM CuSO4. ATPase activity declined when cells were grown with higher concentrations up to 1.5 mM (the maximal concentration that allowed growth), probably due to severe disorganization of plasma membrane. Cu2+-induced maximal activation was reflected in an increase of V max (approximately threefold) and in the slight decrease of the K m for MgATP (from 0.93 ± 0.13 to 0.65 ± 0.16 mM). The expression of the gene encoding the essential plasma membrane ATPase (PMA1) was reduced with a dose-dependent pattern in cells grown with inhibitory concentrations of copper, while the weakly expressed PMA2 gene promoter was moderately more efficient in cells cultivated under mild copper stress (1.5-fold maximal activation). ATPase was activated by copper despite the slightly lower content of ATPase protein in the plasma membrane of Cu2+-grown cells and the powerful inhibitory effect of Cu2+ in vitro.
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    Yeast mitochondrial metabolism: From in vitro to in situ quantitative study (1998)
    Springer
    Molecular and cellular biochemistry 184 (1998), S. 67-79 
    Details
    ISSN: 1573-4919
    Keywords: Saccharomyces cerevisiae ; spheroplast ; permeabilization ; mitochondria ; oxidative phosphorylation ; porin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In this work, we first compared yeast mitochondrial oxidative metabolism at different levels of organization: whole cells (C), spheroplasts (S), permeabilized spheroplasts (PS) or isolated mitochondria (M). At present, S are more suitable for use than C for biochemical techniques such as fast extraction of metabolises and permeabilization. We show here that respiratory rates of S with various substrates are similar to C, which demonstrate that they are adapted to yeast bioenergetic studies. It appeared from ethanol metabolism ± NAD++ or NADH respiratory rates on PS that ethanol metabolism was largely cytosolic; moreover, the activity of NADH dehydrogenase was lesser in the case of PS than in S. By comparing PS and M, the biggest difference concerned the respiratory rates of pyruvate and pyruvate-malate, which were much lower for M. Thus mitochondria preparation caused an unidentified loss involved directly in pyruvate metabolism. When the respiratory rate was lowered as a consequence of a high kinetic control of oxidative activity upstream from the respiratory chain, a similar correlation between the increase in ATP/O and decrease in respiratory rate was observed. So, the intrinsic uncoupling of proton pumps is not a particularity of M. Secondly, we demonstrate the existence of a mechanism of retarded diffusion in yeast similar to that already observed in permeabilized mammalian cells for ADP. Such a mechanism also occurs in yeast for several respiratory substrates: the K0.5 for each substrate toward the respiration rate in PS always exceeds that for M. It is proposed that such a discrepancy is due to a restriction of metabolite movement across the outer mitochondrial membrane in permeabilized cells, i.e. regulation of the substrate permeability through porin channels. In the porin-deficient yeast mutant, the K0.5 for NADH is not significantly different in either M or PS and is comparable to that of the parent strain PS. This result confirms that this retarded diffusion is essentially due to the opening-closing of the porin channel.
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    URL: http://dx.doi.org/10.1023/A:1006830810440
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    Expression of a functionally active cardiac fatty acid-binding protein in the yeast, Saccharomyces cerevisiae (1990)
    Springer
    Molecular and cellular biochemistry 98 (1990), S. 69-74 
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    ISSN: 1573-4919
    Keywords: bovine heart fatty acid-binding protein ; H-FABPc ; heterologous gene expression ; Saccharomyces cerevisiae ; GALIO promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The unicellular eukaryotic microorganism, Saccharomyces cerevisiae, transformed with a plasmid containing a cDNA fragment encoding bovine heart fatty acid-binding protein (H-FABP) under the control of the inducible yeast GAL10 promoter, expressed FABP during growth on galactose. The maximum level of immunoreactive FABP, identical in size to native protein as judged from SDS-polyacrylamide gel electrophoresis, was reached after approximately 16 hours of induction. Analysis of particulate and soluble subcellular fractions showed that FABP was exclusively associated with the cytosol. FABP expressed in yeast cells was functional as was demonstrated by its capacity to bind 14C-oleic acid in an in vitro assay. Growth of the transformants on galactose as the carbon source was significantly retarded at 37°C. Whereas the fatty acid pattern of total lipids was not altered in transformed cells, desaturation of exogenously added 14C-palmitic acid was significantly reduced both at 30 and 37°C. The lowest percentage of radioactively labeled unsaturated fatty acids was found in the phospholipid fraction.
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    Comparison of biochemical effects produced by calcium ions and by monomers of polyacrylamide (acrylamide and bisacrylamide) on strains of Saccharomyces cerevisiae used for production of chiral synthons (1998)
    Springer
    Molecular and cellular biochemistry 178 (1998), S. 33-40 
    Details
    ISSN: 1573-4919
    Keywords: Saccharomyces cerevisiae ; NAD(P)H ; calcium ions ; cells immobilization ; oxygen consumption ; biotransformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The biochemical behaviour of four commercial strains of Saccharomyces cerevisiae was studied in the presence of calcium ions, acrylamide and bisacrylamide. Calcium ions at a concentration of 300 µM induced an increase of NAD(P)+ reduction in commercial Turkish and American strains, while in Chilean and Brazilian commercial strains, it diminished NAD(P)+ reduction. On the other hand, polyacrylamide monomers (acrylamide and bisacrylamide) induced a decrease of NAD(P)+ reduction in all strains studied in this paper. When membrane potential (ΔΨ) and oxygen consumption were measured in the presence of polyacrylamide monomers, a decrease of both was observed in all strains studied.
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    The use of molecular modelling in the understanding of configurational specificity (R or S) in asymmetric reactions catalyzed by Saccharomyces cerevisiae or isolated dehydrogenases (1998)
    Springer
    Molecular and cellular biochemistry 178 (1998), S. 27-31 
    Details
    ISSN: 1573-4919
    Keywords: Saccharomyces cerevisiae ; microorganisms ; dehydrogenases ; acetoacetate ; molecular modelling ; enantiomeric excess ; biotransformation ; baker's yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This method gives a general ideal how to use crystallographic information of enzymes to understand reactions catalyzed by these biocatalysts, commonly used by biochemists to produce chiral products. The interactions of three acetoacetic esters with the enzymes L-lactate dehydrogenase and alcohol dehydrogenase were studied through molecular modelling computer program. These artificial substrates have been widely used to produce chiral synthons. Through this methodology it was possible to understand the conformational specificity of these enzymes with respect to the products and how these enzymes can be inhibited by modifying the structures of the artificial substrates. Also, it was possible to predict whether some type of artificial substrate will suffer reduction by cells that contain these dehydrogenases and what kind of configuration (R or S) the final product will have.
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    URL: http://dx.doi.org/10.1023/A:1006831902849
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    Genetic analysis of clathrin function in yeast (1990)
    Springer
    The journal of membrane biology 116 (1990), S. 93-105 
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    ISSN: 1432-1424
    Keywords: clathrin ; genetics ; Saccharomyces cerevisiae ; exocytosis ; endocytosis ; prohormone maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1007/BF01868668
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    Ground cover, photosynthetic rate and tuber yield of potato (Solanum tuberosum L.) crops from seed tubers with different physiological age modified by foliar applications of plant growth regulators (1998)
    Springer
    Potato research 41 (1998), S. 175-185 
    Details
    ISSN: 1871-4528
    Keywords: benzylaminopurine ; gibberellic acid ; senescence ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The modifying effects of applying the plant growth regulators (PGRs) benzylaminopurine (BAP), gibberellic acid (GA3) and BAP+GA3 on physiological age were studied. Two experiments with two cultivars, differing in rate of physiological ageing (medium-early Pampeana, medium-late Huinkul) and two storage systems were performed during 1988/89 and 1989/90 in two different potato areas of Argentina. In both seasons seed tubers stored in heaps reached an advanced physiological age at planting, compared with tubers from the cold store. Seed tubers of cv. Pampeana were older than those of Huinkul. compared with control crops, those sprayed with BAP maintained ground cover and photosynthesis for longer, and those sprayed with GA3 for a shorter period. Consequently tuber yield was decreased by GA3 in 1988/89, but in 1989/90 all crops treated with PGRs outyielded the control. BAP could overcome effects of advanced physiological age on crop senescence and tuber yield.
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    URL: http://dx.doi.org/10.1007/BF02358440
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    The Saccharomyces cerevisiaeSOM1 gene: heterologous complementation studies, homologues in other organisms, and association of the gene product with the inner mitochondrial membrane (1998)
    Springer
    Molecular genetics and genomics 257 (1998), S. 635-640 
    Details
    ISSN: 1617-4623
    Keywords: Key words Mitochondrial protein sorting ; Processing of Cox2 ; Kluyveromyces lactis ; Leishmania major ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The small nuclear gene SOM1 of Saccharomyces cerevisiae was isolated as a multicopy suppressor of a mutation in the IMP1 gene, which encodes the mitochondrial inner membrane peptidase subunit 1 (Imp1). Analysis revealed that Som1 and Imp1 are components of a mitochondrial protein export system, and interaction between these two proteins is indicated by the genetic suppression data. Here we describe the identification of a gene from Kluyveromyces lactis, which restores respiratory function to a S. cerevisiae SOM1 deletion mutant at 28° C. The sequence of the K. lactis gene predicts a protein product of 8.1-kDa, comprising 71 amino acid residues, with a putative mitochondrial signal sequence at its N-terminus. The protein is 50% identical to its S.cerevisiae counterpart. The expression pattern of a homologous sequence in Leishmania major suggests a more general role for SOM1 in mitochondrial biogenesis and protein sorting. The various Som1 proteins exhibit a highly conserved region and a remarkable pattern of cysteine residues. A protein of the expected size was transcribed and translated in vitro. The Som1 protein was detected in fractions of S. cerevisiae enriched for mitochondria and found to be associated with the inner mitochondrial membrane.
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    Growth-regulated formation of heteromeric complexes of the centromere and promoter factor, Cbf1p, in yeast (1998)
    Springer
    Molecular genetics and genomics 260 (1998), S. 417-425 
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    ISSN: 1617-4623
    Keywords: Key words Centromere and promoter factor 1 (Cpf1p) ; Protein-protein interaction ; Saccharomyces cerevisiae ; Environmental adaptations ; Transcriptional activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcriptional regulation of the yeast cytochrome c 1 gene (CYT1) in response to oxygen and carbon source is mediated by Hap1p and the Hap2 complex. Furthermore, the centromere-binding factor 1 (Cbf1p) associates with the CYT1 upstream region (UASCYT1), but its direct activation potential is insignificant. The possible role of Cbf1p as a modulator of transcriptional adaptation to changes in nutritional conditions was examined. In electrophoretic mobility shift assays (EMSA) using yeast nuclear extracts, Cbf1p was found to exist as homo- and heterodimers of processed subforms of 54 and 37 kDa. An additional 18-kDa version was the only species found in anaerobic cells grown under an atmosphere of purified nitrogen, but not when CO2 was used to establish anaerobiosis. All three dimers of the 37 and 54 kDa versions of Cbf1p that occurred in oxidatively growing cells gave rise to hetero-oligomeric complexes containing other as yet unidentified protein(s). Complex formation was not observed with extracts from cultures grown on high levels of glucose and was dependent on pre-assembly in the absence of target DNA. Pre-treatment with alkaline phosphatase enhanced formation of these higher-order complexes. The C-terminal 18-kDa segment of Cbf1p, which can undergo dimerization and bind DNA, does not induce supershifts after preincubation and is not influenced by dephosphorylation. We propose that the N-terminal domain is subject to carbon source- or growth-dependent phosphorylation/dephosphorylation events that result in differential recruitment of additional factors to promoters of genes that encode proteins required for non-fermentative growth.
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    URL: http://dx.doi.org/10.1007/s004380050912
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    Growth inhibition of Saccharomyces cerevisiae by the immunosuppressant leflunomide is due to the inhibition of uracil uptake via Fur4p (1998)
    Springer
    Molecular genetics and genomics 260 (1998), S. 102-107 
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    ISSN: 1617-4623
    Keywords: Key words Immunosuppressant ; Uracil permease ; FUR4 ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The immunosuppressant leflunomide inhibits cytokine-stimulated proliferation of lymphoid cells in vitro and also inhibits the growth of the eukaryotic microorganism Saccharomyces cerevisiae. To elucidate the molecular mechanism of action of the drug, two yeast genes which suppress the anti-proliferative effect when present in multiple copies were cloned and designated MLF1 and MLF2 for multicopy suppressor of leflunomide sensitivity. DNA sequencing analysis revealed that the MLF1 gene is identical to the FUR4 gene, which encodes a uracil permease and functions to import uracil efficiently. The MLF2 was found to be identical to the URA3 gene. Excess exogenous uracil also overcomes the anti-proliferative effect of leflunomide on yeast cells. Uracil prototrophy also conferred resistance to leflunomide. Uracil uptake was inhibited by leflunomide. Thus, the growth inhibition by leflunomide seen in a S. cerevisiae ura3 auxotroph is due to the inhibition of the entry of exogenous uracil via the Fur4 uracil permease.
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    Efficient initiation of S-phase in yeast requires Cdc40p, a protein involved in pre-mRNA splicing (1998)
    Springer
    Molecular genetics and genomics 260 (1998), S. 232-241 
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    ISSN: 1617-4623
    Keywords: Key words Cell cycle ; mRNA splicing ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The S. cerevisiae CDC40 gene was originally identified as a cell-division-specific gene that is essential only at elevated temperatures. Cells carrying mutations in this gene arrest with a large bud and a single nucleus with duplicated DNA content. Cdc40p is also required for spindle establishment or maintenance. Sequence analysis reveals that CDC40 is identical to PRP17, a gene involved in pre-mRNA splicing. In this paper, we show that Cdc40p is required at all temperatures for efficient entry into S-phase and that cell cycle arrest associated with cdc40 mutations is independent of all the known checkpoint mechanisms. Using immunofluorescence, we show that Cdc40p is localized to the nuclear membrane, weakly associated with the nuclear pore. Our results point to a link between cell cycle progression, pre-mRNA splicing, and mRNA export.
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    A screen for upstream components of the yeast protein kinase C signal transduction pathway identifies the product of the SLG1 gene (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 148-155 
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    ISSN: 1617-4623
    Keywords: Key words Protein kinase C ; Signal transduction ; Transposon mutagenesis ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We employed the constitutive BCK1-20 allele of the gene for the MAP kinase kinase kinase (MAPKKK) in the yeast Pkc signal transduction pathway to develop a genetic screen for mutants in genes encoding upstream components. Transposon mutagenesis yielded a mutant that was completely dependent on the active allele in the absence of osmotic stabilization. The transposon had integrated at the yeast SLG1 (HCS77) locus. This gene encodes a putative membrane protein. Haploid slg1 deletion strains are sensitive to caffeine, as expected for mutants in the Pkc pathway, as well as a variety of other drugs. The response to elevated temperatures and the dependence on osmotic stabilization depends on the genetic background. Thus, in the strain used for mutagenesis, disruption of SLG1 causes the cells to become non-viable in the absence of osmotic stabilization at both 30° C and 37° C. In a different genetic background this phenotype was not observed. Sensitivity of the haploid deletion mutants to caffeine can be partially suppressed by overexpression of genes for other components of the Pkc pathway, such as PKC1, SLT2, ROM2, and STE20. In addition, a SLG1-lacZ reporter construct shows higher expression in the presence of caffeine or magnesium chloride in a wild-type diploid background.
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    DNA replication is completed in Saccharomyces cerevisiae cells that lack functional Cdc14, a dual-specificity protein phosphatase (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 437-441 
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    ISSN: 1617-4623
    Keywords: Key words Dual-specificity phosphatase ; DNA synthesis ; Telophase ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Cdc14 protein encodes a dual-specificity protein phosphatase which functions in late mitosis, and considerable genetic evidence suggests a role in DNA replication. We find that cdc14 mutants arrested in late mitosis maintain persistent levels of mitotic kinase activity, suggesting that Cdc14 controls inactivation of this kinase. Overexpression of Sic1, a cyclin-dependent protein kinase inhibitor, is able to suppress telophase mutants such as dbf2, cdc5 and cdc15, but not cdc14. It does, however, force cdc14-arrested cells into the next cell cycle, in which an apparently normal S phase occurs as judged by FACS and pulsed-field gel electrophoretic analysis. Furthermore, in a promoter shut-off experiment, cells lacking Cdc14 appear to carry out a normal S phase. Thus Cdc14 functions mainly in late mitosis and it has no essential role in S phase.
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    A physical assay for detection of early meiotic recombination intermediates in Saccharomyces cerevisiae (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 512-520 
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    ISSN: 1617-4623
    Keywords: Key words Homologous recombination ; Double-strand breaks ; Recombination intermediate ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In most eukaryotic organisms, recombination events leading to exchanges between homologous chromosomes link the homologs in a manner that allows their proper attachment to the meiotic spindle. In the yeast Saccharomyces cerevisiae these exchanges are initiated in early prophase as double-strand breaks in the DNA. These breaks are processed through a series of intermediates to yield mature crossovers late in prophase. The following experiments were designed to monitor the appearance of the earliest recombinant DNA strands formed in this process. A polymerase chain reaction assay was devised that allows the detection of recombinant strands at a known initiation site for meiotic recombination. The time and rate of appearance of recombinant strands was found to coincide with commitment to recombination, demonstrating that DNA strands bearing sequences from both parental chromosomes are rapidly formed after the initiation of meiotic recombination.
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    Accumulation of β-tubulin-containing fibres in the cortical domain ofSaccharomyces cerevisiae spheroplasts (1998)
    Springer
    Protoplasma 202 (1998), S. 11-16 
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    ISSN: 1615-6102
    Keywords: GeneTUB2 ; Saccharomyces cerevisiae ; Antibody TU-14 ; Cortical β-tubulin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The distribution of microtubules inSaccharomyces cerevisiae was studied with the monoclonal antibody (mab) TU-14 against β-tubulin. Immunoblotting and immunoprecipitation experiments with a strain overexpressing Tub2p confirmed that the mab TU-14 specifically recognized Tub2p. By immunofluorescence microscopy, the mab TU-14 attached to all known tubulin structures labelled with the standard polyclonal anti-β-tubulin antibody 206-1. In addition, the mab TU-14 revealed cortical patches in wild-type cells and an abundant network of fibres in the cortex of spheroplasts cultivated in nutrient medium. These cortical fibres seemed to be specific to spheroplasts and suggest that the accumulated Tub2p is predominantly associated with the plasma membrane.
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    Effect of thiobencarb on growth and photosynthesis of the soil alga Protosiphon botryoides (Chlorophyta) (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 547-554 
    Details
    ISSN: 1573-5176
    Keywords: herbicide ; green alga ; growth ; nutrients ; photosynthesis ; it Protosiphon botryoides ; respiration ; Thiobencarb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of the herbicide thiobencarb (Saturn) were tested on the growth and physiology of the chlorophyte Protosiphon botryoides isolated from an Egyptian paddy. Assays were conducted using 16-day batch cultures. Chlorophyll and dry weight biomass yields were significantly reduced at 2–3 mg L-1 thiobencarb, and dark respiration increased and protein decreased significantly at 3 mg L-1. Reductions in exponential specific growth rate (μ) were generally small, but in some cases significant. Thiobencarb also slightly, but significantly, reduced the 77 K fluorescence parameter Fv/Fm, an indicator of maximum photosynthetic efficiency. No consistent dose-dependent changes occurred in chlorophyll per unit dry weight, total carbohydrate or gross photosynthetic capacity. Whereas half of the added thiobencarb was recovered from control (uninoculated) medium, it was largely absent from cells and culture medium after sixteen days, indicating biodegradation by the alga or associated bacteria. P. botryoides recovered fully within sixteen days following subculture in thiobencarb-free medium. Independently varying phosphate and nitrate nine-fold had no clear effect on the sensitivity of P. botryoides to thiobencarb.
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    Effects of increased atmospheric CO2 and N supply on photosynthesis, growth and cell composition of the cyanobacterium Spirulina platensis (Arthrospira) (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 461-469 
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    ISSN: 1573-5176
    Keywords: Cyanobacterium ; Spirulina platensis ; Arthrospira ; CO2 ; organic carbon ; nitrogen ; photosynthesis ; batch culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The consequences of the addition of CO2 (1%) in cultures of S. platensis are examined in terms of biomass yield, cell composition and external medium composition. CO2 enrichment was tested under nitrogen saturating and nitrogen limiting conditions. Increasing CO2 levels did not cause any change in maximum growth rate while it decreased maximum biomass yield. Protein and pigments were decreased and carbohydrate increased by high CO2, but the capability to store carbohydrates was saturated. C:N ratio remained unchanged while organic carbon released to the external medium was enhanced, suggesting that organic carbon release in S. platensis is an efficient mechanism for the maintenance of the metabolic integrity, balancing the cell C:N ratio in response to environmental CO2 changes. CO2 affected the pigment content: Phycocyanin, chlorophyll and carotenoids were reduced in around 50%, but the photosynthetic parameters were slightly changed. We propose that in S. platensis CO2 could act promoting degradation of pigments synthetised in excess in normal CO2 conditions, that are not necessary for light harvesting. Nitrogen assimilation was significantly not affected by CO2, and it is proposed that the inability to stimulate N assimilation by CO2 enrichment determined the lack of response in maximum growth rate.
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    Response of the tropical red seaweed Gracilaria cornea to temperature, salinity and irradiance (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 419-425 
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    ISSN: 1573-5176
    Keywords: Gracilaria cornea ; photosynthesis ; respiration ; chlorophyll ; phycoerythrin ; Florida ; salinity ; temperature ; irradiance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The agarophyte Gracilaria cornea, collected over 2.5 y in the Florida Keys, shows adaptations to oceanic salinities and subtropical to tropical water temperatures in its photosynthetic and respiratory responses as measured with a respirometer. No seasonal pattern in responses to irradiance, temperature, and salinity were evident between five collections over a 20-month period, indicating the tropical nature of the populations from Bahia Honda and Pigeon Keys. Concentrations of chlorophyll a (0.09 to 0.41 mg g d wt-1) and phycoerythrin (0.06 to 0.36 mg g d wt- 1) were low and reflect the low nutrient regime of the habitats, especially when compared to laboratory cultured plants. Compensation and saturation irradiances were also low (11–38 and 90–127 μmol photon m-2 s-1), indicating acclimation to lower irradiances in their shallow (1–2 m depth) habitats where turbidity can be high. In comparison with other subtropical and warm temperate species of Gracilaria, G. cornea had lower levels of pigment, but similarly high photosynthetic efficiency, demonstrating shade adaptation; it had only limited tolerance to salinities below 20‰ and temperatures below 15 °C. Thus, G. cornea from the Florida Keys in mariculture would require subtropical to tropical temperatures and stable oceanic salinities.
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    Dunaliella salina (Chlorophyta) with small chlorophyll antenna sizes exhibit higher photosynthetic productivities and photon use efficiencies than normally pigmented cells (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 515-525 
    Details
    ISSN: 1573-5176
    Keywords: Chlorophyll antenna size ; damage and repair cycle ; photon use efficiency ; photosynthesis ; photoinhibition ; Dunaliella salina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photon use efficiencies and maximal rates of photosynthesis in Dunaliella salina (Chlorophyta) cultures acclimated to different light intensities were investigated. Batch cultures were grown to the mid-exponential phase under continuous low-light (LL: 100 μmol photon m-2 s-1) or high-light (HL: 2000 μmol photon m-2 s-1) conditions. Under LL, cells were normally pigmented (deep green) containing ∼500 chlorophyll (Chl) molecules per photosystem II (PSII) unit and ∼250 Chl molecules per photosystem I (PSI). HL-grown cells were yellow-green, contained only 60 Chl per PSII and 100 Chl per PSI and showed signs of chronic photoinhibition, i.e., accumulation of photodamaged PSII reaction centers in the chloroplast thylakoids. In LL-grown cells, photosynthesis saturated at ∼200 μmol photon m-2 s-1 with a rate (Pmax) of ∼100 mmol O2 (mol Chl)-1 s-1. In HL-grown cells, photosynthesis saturated at much higher light intensities, i.e. ∼2500 μmol photon m-2 s-1, and exhibited a three-fold higher Pmax (∼300 mmol O2 (mol Chl)-1 s-1) than the normally pigmented LL-grown cells. Recovery of the HL-grown cells from photoinhibition, occurring prior to a light-harvesting Chl antenna size increase, enhanced Pmax to ∼675 mmol O2 (mol Chl)-1 s-1. Extrapolation of these results to outdoor mass culture conditions suggested that algal strains with small Chl antenna size could exhibit 2–3 times higher productivities than currently achieved with normally pigmented cells.
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    Light dependency of the photosynthetic recovery of Nostoc flagelliforme (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 51-53 
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    ISSN: 1573-5176
    Keywords: blue-green alga ; cyanobacterium ; Fv/Fmlight ; Nostoc flagelliforme ; photosynthesis ; rewetting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract PS II photochemical efficiency (Fv/Fm) of Nostoc flagelliforme was examined after rewetting in order to investigate the light-dependency of its photosynthetic recovery. Fv/Fm was not detected in the dark, but was immediately recognized in the light. Different levels of light irradiation (4, 40 and 400 µmol photon m2 s-1) displayed different effects on the recovery process of photosynthesis. The intermediate level led to the best recovery of photochemical efficiency; the low light required longer and the high light inhibited the extent of the recovered efficiency. It was concluded that the photosynthetic recovery of N. flagelliforme is both light-dependent and influenced by photon flux density.
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    Nitrogen availability influences the biochemical composition and photosynthesis of tank-cultivated Ulva rigida (Chlorophyta) (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 383-389 
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    ISSN: 1573-5176
    Keywords: ammonium ; C:N ratio ; tank culture ; dietary fibre ; fatty acids ; nitrogen ; photosynthesis ; Ulva rigida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Physiological and biochemical changes in relation to inorganic nitrogen availability were studied for tank-cultivated Ulva rigida grown under nitrogen- enriched and nitrogen-depleted seawater. U. rigida was initially cultivated in nitrogen-enriched seawater (daily concentrations of NH4+ and NO3- + NO2- ranged between 0.5–1.7 and 0.06–0.15 mg L-1, respectively), then transferred to nitrogen-depleted seawater where photosynthetic capacity decreased to zero after 23 d. At the time (14 d) when photosynthetic rates were lower than 2.0 μmol O2 g-1 FW min-1 and strong bleaching had occurred, some algae were returned to the initial nitrogen-enriched seawater to study recovery from N-limited growth. Data on biochemical composition (chlorophylls, ash, caloric content, fatty acids and dietary fibres) and colouration varied significantly depending on the nitrogen conditions. C:N ratios correlated significantly with biochemical parameters. Fatty acid (FA) synthesis continued during the N-starvation period; saturated and mono-unsaturated FA increased to a maximun of 72.2%, while poly-unsaturated fatty acids (PUFA) decreased to 27.7%. During the N-enriched recovery period, the reverse was found. C:N ratios above 10 correlated with carbohydrate synthesis as shown by the dietary fibre level. Under nitrogen enriched conditions, C:N ratios decreased along with a decrease in fibre level. Under controlled conditions, nitrogen represents a major influence on the development of intensive tank cultivation of Ulva rigida, not only by affecting parameters closely related to nitrogen metabolism but also some clearly influenced by carbon uptake.
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    Characterization of oligosaccharides from an antigenic mannan of Saccharomyces cerevisiae (1998)
    Springer
    Glycoconjugate journal 15 (1998), S. 815-822 
    Details
    ISSN: 1573-4986
    Keywords: Saccharomyces cerevisiae ; oligosaccharide structure ; antigenic glycoprotein ; mannan ; allergens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mannans of the yeast Saccharomyces cerevisiae have been implicated as containing the allergens to which bakers and brewers are sensitive and also the antigen recognized by patients with Crohn's disease. A fraction of S. cerevisiae mannan, Sc500, having high affinity for antibodies in Crohn's patients has been characterized by NMR spectroscopy followed by fragmentation using alkaline elimination, partial acid hydrolysis and acetolysis. The released oligosaccharides were separated by gel filtration on a Biogel P4 column and analyzed by fluorescence labeling, HPLC and methylation analysis. The relationship between structure and antigen activity was measured by competitive ELISA. The antigenic activity of the original high molecular weight mannan could be ascribed to terminal Manα1→3Manα1→2 sequences which are rarely found in human glycoproteins but were over-represented in Sc500 compared to other yeast mannans.
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    Unique response of Cyanophyceae to copper (1990)
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    Journal of applied phycology 2 (1990), S. 293-296 
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    ISSN: 1573-5176
    Keywords: heavy metal ; photosynthesis ; periphyton ; tolerance ; Cyanophyceae ; genetic adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was made of the tolerance to Cu of 11 strains of Cyanophyceae and 7 strains of eukaryotes. These had all been tested within 6 months after isolation for their photosynthetic activity when exposed to Cu (Takamuraet al., 1989) and had repeatedly been subcultured in the medium without Cu for 2 years. Photosynthetic measurements were made in two ways: precultured in medium without Cu or precultured (for one subculture) in medium containing Cu (645 μg 1−1). The results were compared with those obtained within 6 months of isolation. The tolerance of the eukaryotes did not change significantly in any case, but most strains of Cyanophyceae lost their tolerance to Cu within a few subcultures in medium without Cu; however tolerance recovered following one subculture in medium containing an intermediate level of Cu. This rapid adaptation cannot be explained by a constitutive mutation.
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    Effects of environmental parameters on net photosynthesis of a free-living brown seaweed,Cystoseira barbata formarepens: determination of optimal photosynthetic culture conditions (1990)
    Springer
    Journal of applied phycology 2 (1990), S. 281-287 
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    ISSN: 1573-5176
    Keywords: Cystoseira barbata ; photosynthesis ; light ; temperature ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The net photosynthesis of the Mediterranean brown seaweedCystoseira barbata f.repens is measured according to irradiance, temperature and salinity. There is not only, a good utilization of low light intensities (light-shade adaptation), but also a specific ability to use a broad range of irradiance, which corresponds in the photosynthesis-irradiance curves to a high initial slope and an extended light saturation level from 300 to 1500 μmol photon m−2 s−1; only very high irradiances induce photoinhibition. Maximum net photosynthesis occurred at temperatures ranging from 20 °C to 30 °C. The alga tolerates not only a low level of salinity, but also a slight increase in salinity; however, at more than 47.5 g 1−1 NaCl, oxygen exchange is significantly reduced. Light, temperature and salinity requirements are discussed, taking into account ecological considerations. Yields and quality of alginic acid are presented according to the irradiance and yearly evolutionin situ in order to aid future cultivation of this species.
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    Light response curves for Gelidium sesquipedale from different depths, determined by two methods: O2 evolution and chlorophyll fluorescence (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 295-301 
    Details
    ISSN: 1573-5176
    Keywords: Gelidium sesquipedale ; photosynthesis ; fluorescence ; light response curves ; pigments ; depth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthesis-light response curves of Gelidium sesquipedale from the west coast of Portugal (Cape Espichel) were determined at four different depths, 3, 10, 15 and 22 m. Data acquisition using chlorophyll a fluorescence methodology and oxygen electrode measurements were compared. Response curves were determined over an increasing range of irradiance values (I), from darkness to 900 μmol photon m-2 s-1 PAR. In general, light response curves obtained for G. sesquipedale showed a similar pattern whether determined by the chlorophyll fluorescence method or by oxygen evolution. The photosynthetic capacity of G. sesquipedale decreased with depth, as expected, revealing a ‘sun’ and ‘shade’ acclimation pattern, between shallow and deeper waters.
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    Effects of solar UV stress on chlorophyll fluorescence kinetics of intertidal macroalgae from southern Spain: a case study in Gelidium species (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 285-294 
    Details
    ISSN: 1573-5176
    Keywords: UV-radiation ; chlorophyll fluorescence ; photosynthesis ; stress tolerance ; electron transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photoinhibition and recovery kinetics after short exposure to solar radiation following three different irradiance treatments of irradiances (PAR, PAR+UVA and PAR+UVA+UVB) was assessed in two intertidal species of the genus Gelidium, Gelidium sesquipedale and G. latifolium, collected from Tarifa (southern Spain) using in vivo chlorophyll fluorescence (PAM fluorometry). After 3 h UV radiation exposure, optimal quantum efficiency (Fv/Fm) in G. sesquipedale decreased between 25 and 35% relative to the control. Under PAR alone, values decreased to 60%. In G. latifolium, photoinhibition did not exceed 40%. Similar results were found for the effective quantum yield (ΔF/Fm′), however, no marked differences in relation to light treatments were seen. When plants were shaded for recovery from stress, only in G. latifolium a significant increase in photosynthesis was observed (between 80 and 100% of control). In contrast, photosynthesis of G. sesquipedale suffered a chronic photoinhibition or photodamage under the three light irradiances. Full solar radiation (PAR+UVA+UVB) affected also the electron transport rate in both species. Here, initial slopes of electron transport vs. irradiance curves decreased up to 60% of controls. Although the recovery kinetic under PAR+UVA+UVB conditions was delayed in G. latifolium, after 24 h recovery this species reached significantly higher than G. sesquipedale. PAR impaired electron trasport only in G. sesquipedale. Overall, both species are characterized by different capacity to tolerate enhanced solar radiation. G. latifolium is a sun adapted plant, well suited to intertidal light conditions, whereas G. sesquipedale, growing at shaded sites in the intertidal zone, is more vulnerable to enhanced UV radiation.
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    Photosynthetic and population growth response of the test alga Selenastrum capricornutum Printz to zinc, cadmium and suspended sediment elutriates (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 145-151 
    Details
    ISSN: 1573-5176
    Keywords: 14C ; photosynthesis ; population growth ; Selenastrum capricornutum ; suspended sediment elutriate ; zinc ; cadmium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Short-term 14C-fixation (4 h) Selenastrum capricornutum algal toxicity tests were conducted with Cd (n=8), Zn (n=9) and suspended sediment aqueous elutriates (n=28) and the results were compared to those obtained in a 48 h population growth test. In order to provide more realistic experimental conditions, toxicity tests were carried out in prefiltered nutrient-spiked Lake Geneva water. The population growth inhibition test was significantly more sensitive than the14 C-fixation test for Cd (median EC50-4h and EC50-48h values of 600 and 118 µg L-1, respectively) whereas no significant difference was measured for Zn toxicity (median EC50-4h and EC50-48h values of 97 and 96 µg L-1, respectively). With suspended sediment aqueous elutriates, the relative sensitivity of the two different end points is sample dependent, with ratios of the EC25 for the14 C-fixation: population growth test ranging from 〈0.26 to 〉53.3. Elutriate toxicity shows no apparent relationship between the acute and chronic test, indicating that population growth inhibition cannot be derived directly or predicted from14 C-fixation. Both tests with their specific advantages and limitations provide valuable complementary information to measure the impact of single toxicants or complex mixtures on aquatic plants.
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    Reduced photoinhibition of a phycocyanin-deficient mutant of Synechocystis PCC 6714 (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 447-452 
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    ISSN: 1573-5176
    Keywords: dense algal suspension ; light-harvesting pigment ; photosynthesis ; Synechocystis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects on photoinhibition of light-harvesting pigments in microalgal cells were examined using the wild type and a phycocyanin- deficient mutant (PD-1) of Synechosystis PCC 6714. Mutant PD-1 showed higher resistance to high light than the wild type in terms of the decline of photosynthetic activity at any light intensity and with various cell densities. This suggests that the loss of productivity induced by high light intensity would be improved by reducing the content of light-harvesting pigments.
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    URL: http://dx.doi.org/10.1023/A:1008049901939
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    Strain selection in Gracilaria spp. 2. Selection for high and low temperature resistance in G. verrucosa sporelings (1990)
    Springer
    Journal of applied phycology 2 (1990), S. 163-171 
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    ISSN: 1573-5176
    Keywords: Gracilaria ; strain selection ; growth ; photosynthesis ; rubisco ; agar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A strain selection procedure using Gracilaria verrucosa gametophytic sporelings was found to be an efficient tool for the improvement of Gracilaria strains. Two strains, C-2 and A-18, which were isolated and grown clonally, showed higher growth rates under high and low temperature conditions, respectively, than the local Gracilaria conferta. Growth rate, photosynthesis and chlorophyll, which were measured under different temperature and photon flux densities, demonstrated an overall advantage of the selected strains over the wild type strains of both G. verrucosa and G. conferta. Growth rates were also generally in positive correlation with the carboxylase activity of Rubisco. The G. verrucosa wild type also had a 40% higher agar content than G. conferta. The selected strains thus showed higher potential for outdoor cultivation than local wild type populations.
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    Photosynthate production in laboratory cultures (UV conditioned and unconditioned) of Cryptomonas erosa under simulated doses of UV radiation (1998)
    Springer
    Aquatic ecology 32 (1998), S. 297-312 
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    ISSN: 1573-5125
    Keywords: cryptomonads ; macromolecular ; Phototron ; photosynthesis ; UV radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used a device called a Phototron to measure the effects of UV radiation on the cosmopolitan algae, Cryptomonas erosa, grown in continuous cultures. In the Phototron, we investigated changes in photosynthetic parameters (Pmax – specific production rate at optimal light intensity; α – initial slope of the linear portion of the Photosynthesis-Irradiance curve; and θ – the convexity or rate of bending) and carbon allocation as a function of irradiance at three different environmentally-realistic doses of UV radiation in unconditioned (no prior UV exposure) and conditioned algae (15 d previous UV exposure). For unconditioned control algae, Pmax-Total was lower, although not significantly, than the two highest UV treatments. For conditioned control algae, Pmax-Total was higher, although not significantly, than all UV treatments. Our data suggest that short term (4 h) exposure to low levels of UV (8.09 W m−2 unweighted) does not affect Pmax-Total in C. erosa, but does change the proportion of carbon allocated to lipids and proteins. Also, comparisons of lipids, polysaccharides and proteins as a percent of total carbon uptake between unconditioned and conditioned algae indicate that exposure history to UV radiation can have a negative impact on carbon allocation to lipids and proteins, in a wetland alga species that is crucial to the efficient transfer of energy through freshwater food webs.
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    URL: http://dx.doi.org/10.1023/A:1009911811188
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    Characterization and transcriptional regulation of the Synechocystis PCC 6803 petH gene, encoding ferredoxin-NADP+ oxidoreductase: involvement of a novel type of divergent operator (1998)
    Springer
    Plant molecular biology 36 (1998), S. 353-363 
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    ISSN: 1573-5028
    Keywords: ferredoxin-NADP+ oxidoreductase ; petH ; divergent operator ; antisense mRNA ; phosphoribulokinase ; prk Synechocystis PCC 6803 ; photosynthesis ; cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The petH gene, encoding ferredoxin-NADP+ oxidoreductase (FNR), has been characterised in the unicellular cyanobacterium Synechocystis PCC 6803. Its product, FNR, was heterologously produced and functionally characterized. The start-site of the monocystronic petH transcript was mapped 523 bp upstream of the predicted PetH initiation codon, resulting in an unusually large 5′-untranslated region. The 5′ end of the petH transcript is situated within the open reading frame of phosphoribulokinase (encoded by prk), which is transcribed in opposite orientation with respect to petH. The transcription start site of the prk transcript was mapped 219 bp upstream of the initiation codon, resulting in a 223 bp antisense region between both transcripts. Under many conditions the expression of both genes (i.e. petH and prk) is co-regulated symmetrically at the transcriptional level, as was concluded from both northern hybridization experiments and from primer extension analyses; it became uncoupled, however, when specifically petH expression was stimulated, independent of prk expression, by stressing the Synechocystis cells with high salt concentrations. A model for a new type of bidirectional operator, regulating the expression of petH and prk, is proposed.
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    Interactive effects of elevated carbon dioxide and growth temperature on photosynthesis in cotton leaves (1998)
    Springer
    Plant growth regulation 26 (1998), S. 33-40 
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    ISSN: 1573-5087
    Keywords: carbohydrates ; elevated CO2 ; Gossypium hirsutum L. ; interaction ; photosynthesis ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cotton (Gossypium hirsutum L., cv DPL 5415) plants were grown in naturally lit environment chambers at day/night temperature regimes of 26/18 (T-26/18), 31/23 (T-31/23) and 36/28 °C (T-36/28) and CO2 concentrations of 350 (C-350), 450 (C-450) and 700 μL L-1 (C-700). Net photosynthesis rates, stomatal conductance, transpiration, RuBP carboxylase activity and the foliar contents of starch and sucrose were measured during different growth stages. Net CO2 assimilation rates increased with increasing CO2 and temperature regimes. The enhancement of photosynthesis was from 24 μmol CO2 m-2 s-1 (with C-350 and T-26/18) to 41 μmol m-2 s-1 (with C-700 and T-36/28). Stomatal conductance decreased with increasing CO2 while it increased up to T-31/23 and then declined. The interactive effects of CO2 and temperature resulted in a 30% decrease in transpiration. Although the leaves grown in elevated CO2 had high starch and sucrose concentrations, their content decreased with increasing temperature. Increasing temperature from T-26/18 to 36/28 increased RuBP carboxylase activity in the order of 121, 172 and 190 μmol mg-1 chl h-1 at C-350, C-450 and C-700 respectively. Our data suggest that leaf photosynthesis in cotton benefited more from CO_2 enrichment at warm temperatures than at low growth temperature regimes.
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    The influence of Verticillium dahliae and drought on potato crop growth. 1. effects on gas exchange and stomatal behaviour of individual leaves and crop canopies (1990)
    Springer
    European journal of plant pathology 96 (1990), S. 273-289 
    Details
    ISSN: 1573-8469
    Keywords: Canopy enclosure ; stomatal conductance ; light response curve ; light use efficiency ; photosynthesis ; Solanum tuberosum L. ; transpiration ; water use efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Aardappelplanten (Solanum tuberosum L.) cv.Saturna werden onderworpen aan stress als gevolg vanVerticillium dahliae en droogte. In vroege stadia van de groei werden stomataire geleiding, transpiratie en netto fotosynthese bij lichtverzadiging (PAR〉300 W m−2) gemeten aan individuele bladeren en met een mobiel instrumentarium met behulp van gewaskappen. Er werden geen significante verschillen gevonden in de waarden van de stomataire geleiding en de gasuitwisslingskarakteristieken als gevolg vanV. dahliae-besmetting tot een maand na opkomst. Daarna leidde infectie metV. dahliae tot een afname van de stomataire geleiding, transpiratie en netto fotosynthese, speciaal bij oudere bladeren en bij planten die meer aan zonlicht waren blootgesteld. Soms vertoondeV. dahliae interactie met droogte en bleken beide effecten minder dan optelbaar. De hoge waarden van de variatiecoëfficiënten maakten een groot aantal metingen per behandeling noodzakelijk; dit was vooral het geval bij metV. dahliae geïnfecteerde planten hetgeen aantoont datV. dahliae vooral in het begin van de groei niet alle bladeren in gelijke mate aantast. Door de matigende invloed van de integratie van alle bladlagen en mogelijk doordat de bovenste bladeren werden gestimuleerd, werd de totale gewasfotosynthese in mindere mate beïnvloed doorV. dahliae dan de individuele bladfotosynthese. De bovenste niet geïnfecteerde bladeren bleken verantwoordelijk voor het grootste gedeelte van de gewas-fotosynthese. De resultaten tonen aan, dat volgend op een infectie metV. dahliae, de fotosynthese reeds in een vroeg stadium van de groei wordt verminderd als een gevolg van droogtestress in de bladeren.
    Notes: Abstract Potato (Solanum tuberosum L.) plants cv.Saturna were subjected to infection withVerticillium dahliae and drought stress. At the early stages of growth, stomatal conductance, transpiration and net photosynthesis were measured at light saturation (PAR〉300 m−2) on individual leaves and with mobile field equipment with the aid of field enclosures. No significant changes in stomatal conductance and gas exchange characteristics occurred as a result ofV. dahliae instomatal conductance, transpiration and and photosynthetic rates, especially on older leaves and on plants exposed to direct sunlight for a longer period of time. In combination with drought,V. dahliae only occasionally showed interaction; their effects being less than additive. High values of coefficients of variatoon necessitated a high number of measurements per treatment; the more so in the inoculated plants which shows thatV. dahliae seems to affect certain leaves while not affecting others early in growth. Crop photosynthesis was less reduced byV. dahliae than individual leaf photosynthesis due to the levelling effect of integration over the whole canopy and possibly through a stimulation of the top leaves. The upper non-affected leaves are responsible for the bulk of photosynthetic crop activity. The results indicate that following an infection withV. dahliae photosynthesis is reduced early in growth as a result of drought stress in the leaves.
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    Ty RNA levels determine the spectrum of retrotransposition events that activate gene expression in Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 220 (1990), S. 213-221 
    Details
    ISSN: 1617-4623
    Keywords: Ty elements ; Saccharomyces cerevisiae ; Retrotransposon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To learn more about the variety of Ty elements capable of activating gene expression, we characterized 206 spontaneous Ty transpositions that activate the promoterless gene his3Δ4. Most of the Ty elements appear to be full-length, although a few deleted elements were recovered. Over 95% of the insertions belong to the Ty1 family, and the rest are Ty2 elements. The excessive number of Ty1 transpositions was unexpected because there are only 2-fold more Ty1 than Ty2 elements in the yeast strains used in the selection. However, there is 20-fold more Ty1 than Ty2 RNA present in these yeast strains. This difference in RNA level explains the greater number of Ty1 verses Ty2 transpositions at his3Δ4, because Ty elements transpose through an RNA intermediate. A similar association between the Ty transcript level and transpositional activation of his3Δ4 is obtained in cells expressing GAL1-promoted Ty2-H556 or Ty2-917 elements, but only if the element does not contain a marker. Genetically marked Ty2-H556NEO and-917NEO elements transpose into and activate his3Δ4 with the same efficiency as the previously characterized Ty1H3NEO element, but are underrepresented relative to the levels of TyNEO transcript. We also found that chromosomal Ty transcripts are even more abundant than previously estimated and comprise about 1% of total cellular RNA.
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    Conjugative transfer and autonomous replication of a promiscuous IncQ plasmid in the cyanobacterium Synechocystis PCC 6803 (1990)
    Springer
    Molecular genetics and genomics 221 (1990), S. 129-133 
    Details
    ISSN: 1617-4623
    Keywords: Bacterial conjugation ; Cyanobacteria ; IncQ plasmids ; Saccharomyces cerevisiae ; DNA methylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The promiscuous IncQ plasmid pKT210 (Cmr, Smr) is efficiently transferred by transpecific conjugation from Escherichia coli to the facultatively heterotrophic cyanobacterium Synechocystis PCC6803 when mobilized by a helper plasmid coding for IncP transfer functions. The IncQ plasmid is stably maintained in the cyanobacterium as an autonomously replicating multicopy plasmid with no detectable structural alterations and can be recovered by transformation back to E. coli when using a mcrA mcrB host. Thus, the replicative host-range of IncQ plasmids extends beyond purple bacteria to the distinct procaryotic taxon of cyanobacteria, allowing the use of these small plasmids as convenient cloning vectors in Synechocystis PCC6803 and presumably also in cyanobacteria that are not amenable to genetic transformation. In contrast, an IncQ plasmid bearing the TRP1 gene of Saccharomyces cerevisiae failed to replicate when transferred to that yeast by transformation.
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    A GCN4 protein recognition element is not sufficient for GCN4-dependent regulation of transcription in the ARO7 promoter of Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 224 (1990), S. 57-64 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; AR07 gene ; Chorismate mutase ; GCN4 ; Transcriptional regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The gene AR07 encodes the monofunctional enzyme chorismate mutase, a branch point enzyme in the aromatic amino acid biosynthetic pathway in Saccharomyces cerevisiae. We investigated the transcription of the AR07 gene. Three 5′ ends at positions − 36, − 56 and − 73 and the 3′ end of the transcripts 146 bp downstream of the translational stop codon were mapped. As in the promoters of other aromatic amino acid biosynthetic genes, a recognition element for the GCN4 transcriptional activator of amino acid biosynthesis is located 425 base pairs (bp) upstream of the first transcriptional start point. This element binds GCN4 specifically in vitro. Northern analysis and determination of the specific enzyme activity reveals however, that the element is not sufficient to mediate transcriptional regulation by GCN4 in vivo. We thus suggest that in addition to a consensus sequence capable of binding the GCN4 protein other factors like, for example, chromatin structure, determine whether a recognition site for a transcription factor functions as an upstream activation sequence.
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    A yeast mutant, PRP20, altered in mRNA metabolism and maintenance of the nuclear structure, is defective in a gene homologous to the human gene RCC1 which is involved in the control of chromosome condensation (1990)
    Springer
    Molecular genetics and genomics 224 (1990), S. 72-80 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Splicing ; Nuclear structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report on the characterization of the yeast prp20-1 mutant. In this temperature-sensitive mutant, multiple steps of mRNA metabolism are affected. The prp20-1 mutant strain showed alterations in mRNA steady-state levels, defective mRNA splicing and changes in transcription initiation or termination when shifted from the permissive to the non-permissive temperature. In addition, a change in the structure of the nucleus in these cells became apparent. Electron microscopy revealed an altered structure of the nucleoplasm of prp20-1 mutant cells when grown at the no-permissive temperature that was not observed in cells grown at the permissive temperature or in wild-type cells. The wild-type PRP20 gene was isolated and sequenced. The putative PRP20 protein has a molecular weight of 52 kDa. We found that the PRP20 gene is identical to the yeast SRM1 gene (Clark and Sprague 1989). In addition, the PRP20 protein sequence shows significant sequence similarity to the human RCC1 protein (Ohtsubo et al. 1987). This protein has been implicated in the control of chromosome condensation. Based on the phenotype of the prp20-1 mutant and the observed sequence similarity to the human RCC1 protein, we postulate that the yeast PRP20 protein is involved in the control of nuclear organization.
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    The MSS51 gene product is required for the translation of the COX1 mRNA in yeast mitochondria (1990)
    Springer
    Molecular genetics and genomics 224 (1990), S. 111-118 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Translation ; Splicing ; Paromomycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The MSS51 gene product has been previously shown to be involved in the splicing of the mitochondrial pre-mRNA of cytochrome oxidase subunit I (COX1). We show here that it is specifically required for the translation of the COX1 mRNA. Furthermore, the paromomycin-resistance mutation (P inf454 supR ) which affects the 15 S mitoribosomal RNA, interferes, directly or indirectly, with the action of the MSS51 gene product. Possible roles of the MSS51 protein on the excision of COX1 introns are discussed.
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    Induction of “General Control” and thermotolerance in cdc mutants of Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 224 (1990), S. 257-263 
    Details
    ISSN: 1617-4623
    Keywords: General Control ; Thermotolerance ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Saccharomyces cerevisiae starvation for a single amino acid activates the transcription of a set of genes belonging to different amino acid biosynthetic pathways (General Control, GC). We show that mutants affected in GC regulation are also affected in their response to thermal stress. Moreover, growth conditions that are known to induce heat shock proteins induce the GC response. However, unlike heat shock proteins, the transcriptional activator of GC, GCN4, is not induced after a short exposure to heat, and in gcn mutant strains induction of heat resistance is normal.
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    The UGA3 gene regulating the GABA catabolic pathway in Saccharomyces cerevisiae codes for a putative zinc-finger protein acting on RNA amount (1990)
    Springer
    Molecular genetics and genomics 220 (1990), S. 269-276 
    Details
    ISSN: 1617-4623
    Keywords: GABA ; Saccharomyces cerevisiae ; Transcription ; DNA sequence ; Zinc finger
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The UGA3 gene of Saccharomyces cerevisiae is required for 4-aminobutyric acid (GABA)-dependent induction of the UGA1, UGA2 and UGA4 genes which encode the two GABA catabolic enzymes and a GABA-specific permease, respectively. Measurements of UGA1-specific transcripts show that induction of UGA1 correlates with accumulation of its RNA and requires a functional UGA3 gene. A 2 kb DNA fragment complementing the uga3 mutation was isolated and shown to contain the UGA3 gene. The primary structure of the UGA3 encoded protein was deduced from the DNA sequence, and contains an N-terminal, cysteine-rich motif similar in sequence to regions found in other fungal regulatory proteins and which are supposed to form zinc finger structures involved in DNA binding. Mutations were identified in the UGA3 genes isolated from uninducible and constitutive uga3 alleles. One case of intragenic complementation between two uninducible uga3 mutants is reported, indicating a possible oligomeric structure for UGA3. The role of UGA3 is discussed in relation to its genetic properties and its predicted structure.
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    Regulation of chorismate mutase in Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 220 (1990), S. 283-288 
    Details
    ISSN: 1617-4623
    Keywords: Chorismate mutase ; Saccharomyces cerevisiae ; Repression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Saccharomyces cerevisiae ARO7 gene was cloned by screening a wild-type gene bank for complementation of an aro7 auxotrophic mutant. In vitro mutagenesis of the isolated plasmid (pJFB1) gave several transformants resistant to levels of the phenylalanine analogue 2-thienylalanine inhibitory to the wild-type transformant. Chorismate mutase assays indicated that two of the mutants (J14-26IV6 and J14-26IV9) were resistant to feedback inhibition by tyrosine displayed by wild-type strains. Analysis of the effect of other aromatic amino acids on chorismate mutase activity showed that tryptophan counteracted this inhibition. Analysis of the effect of tyrosine in the growth medium on enzyme activity indicated that the wild-type ARO7 gene was repressed by tyrosine, a phenomenon not previously reported. Two of the 2-thienylalanine resistant mutants (J14-26IV3 and J14-26IV9) appeared to be resistant to this repression. Transcriptional analysis confirmed that the level of ARO7 transcript decreased with increasing tyrosine concentration. In stain J14-26IV9 the ARO7 transcript level was not affected. J14-26IV9, therefore, appears to be a double mutant, resistant to both feedback inhibition and repression by tyrosine.
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    Differential regulation of STA genes of Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 222 (1990), S. 87-96 
    Details
    ISSN: 1617-4623
    Keywords: Glucoamylase ; Sporulation ; Saccharomyces cerevisiae ; Saccharomyces cerevisiae var. diastaticus ; STA genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The single glucoamylase gene (SGA1) of the yeast Saccharomyces cerevisiae is expressed exclusively during the sporulation phase of the life cycle. Enzymatic studies and nucleic acid sequence comparisons have shown that the SGA1 glucoamylase is closely related to the secreted enzymes of S. cerevisiae var. diastaticus. The latter are encoded by any of three unlinked STA genes, which have been proposed to derive from the ancestral SGA1 form by genomic rearrangement. We show that the regulation of SGA1 is distinct from that of the other members of the STA gene family. SGA1 expression did not respond to STA10, the primary determinant of glucoamylase expression from STA2. Unlike STA2, SGA1 was not regulated directly by the mating type locus. Expression of SGA1 depended on the function of the MAT products in supporting sporulation and not on the formation of haploid progeny spores or on the composition of the mating type locus per se. We conclude that the STA genes acquired regulation by STA10 and MAT by the genomic rearrangements that led to their formation. This regulation is thus distinct from that of the ancestral SGA1 gene.
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    URL: http://dx.doi.org/10.1007/BF00283028
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    Molecular basis for determining the sensitivity of eucaryotes to the antimitotic drug rhizoxin (1990)
    Springer
    Molecular genetics and genomics 222 (1990), S. 169-175 
    Details
    ISSN: 1617-4623
    Keywords: Aspergillus nidulans ; Schizosaccharomyces pombe ; Saccharomyces cerevisiae ; Drug resistance ; β-tubulin mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rhizoxin, an antibiotic, exhibits potent anti-mitotic activity against most eucaryotic cells including those of higher vertebrates, plants and fungi by binding to β-tubulin. ThebenA gene of three independently isolated rhizoxin-resistant (Rhir) mutants ofAspergillus nidulans was cloned, sequenced and compared with that of the wild-type, rhizoxin-sensitive (Rhis) strain. In all three Rhir mutants, the AAC codon for Asn-100 of thebenA β-tubulin gene was altered to ATC, coding for Ile. Sequence displacement experiments confirmed that the substitution of Ile for Asn-100 confers resistance to rhizoxin in this organism. The amino acid sequences of β-tubulin surrounding the 100th amino acid residue from the N-terminus including Asn-100 are highly conserved with a few exceptions. The fission yeastSchizosaccharomyces pombe and the budding yeastSaccharomyces cerevisiae are naturally occurring Rhir organisms whose β-tubulin genes encode Ile and Val respectively at the 100th amino acid residue. The Ile-100 ofS. pombe and the Val-100 ofS. cerevisiae were altered to Asn using site-directed mutagenesis and gene displacement techniques. The resultant haploid strains of these two yeasts uniquely expressing β-tubulin (Asn-100) instead of β-tubulin (Ile-100 or Val-100) were found to be Rhis. Haploid yeast expressing β-tubulin (Asn-100) is normal except for its sensitivity to rhizoxin. These results suggest that rhizoxin resistance has a common basis in both naturally occurring species and experimentally selected mutants in the substitution of Ile or Val for Asn-100 in β-tubulin.
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    URL: http://dx.doi.org/10.1007/BF00633814
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    Correct splicing of modified introns of a Rhizopus proteinase gene in Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 11-16 
    Details
    ISSN: 1617-4623
    Keywords: Rhizopus aspartic proteinase ; Splicing of intron ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The intron of the Rhizopus aspartic proteinase gene (RNAP-I) was modified by in vitro mutagenesis and examined for its splicing efficiency in Saccharomyces cerevisiae. The wild-type intron of the RNAP-I gene was not spliced at all in spite of its structural similarity to introns of S. cerevisiae. The primary transcript of the RNAP-I gene was converted to correctly translatable mRNA only when the complete consensus sequence of S. cerevisiae introns (i.e. 5″-GTATGT-----TACTAAC-----TAG-3″) was introduced into its intron, although the efficiency of splicing was low. It is also shown that transformants carrying the RNAP-I gene with the complete consensus sequence of S. cerevisiae introns produce active RNAP-I protein.
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    URL: http://dx.doi.org/10.1007/BF00315791
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    Expression in Saccharomyces cerevisiae of a gene associated with cytoplasmic male sterility from maize: Respiratory dysfunction and uncoupling of yeast mitochondria (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 24-32 
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    ISSN: 1617-4623
    Keywords: Cochliobolus heterostrophus race T disease ; Maize cytoplasmic male sterility ; Mitochondria ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We asked whether the mitochondrial T-urf13 gene, associated with the male sterility phenotype of T cytoplasm in maize, can be expressed in Saccharomyces cerevisiae and whether this expression can mimic the effects observed in maize. We introduced the universal code equivalent of the T-urf13 gene into the S. cerevisiae nucleus by transformation and directed its translation product into mitochondria by means of a fusion with the targeting presequence from Neurospora crassa ATPase subunit 9. We show that expression of the universal code equivalent of the T-urf13 gene in the yeast nucleus does indeed mimic its effects in maize: respiratory growth of yeast is inhibited, respiration-deficient cytoplasmic mutants accumulate and NADH oxidation of isolated mitochondria is uncoupled. All these effects are observed only if the mitochondrial targeting peptide and methomyl or HmT toxin are present.
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    URL: http://dx.doi.org/10.1007/BF00315793
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    Deletion analysis of domain independence in the TRP1 gene product of Neurospora crassa (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 49-57 
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    ISSN: 1617-4623
    Keywords: Neurospora crassa ; Heterologous gene expression ; Saccharomyces cerevisiae ; Domain independence ; TRP1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The trifunctional TRP1 gene from Neurospora crassa (N-TRP1) was subcloned into the yeast-Escherichia coli shuttle vector YEp13 and expressed in Saccharomyces cerevisiae. The three activities of the N-TRP1 gene product were detected in yeast mutants that lacked either N-(5′-phosphoribosyl) anthranilate (PRA) isomerase or both the glutamine amidotransferase function of anthranilate synthase and indole-3-glycerol phosphate (InGP) synthase. The protein was detected on immunoblots only as the full length 83 kda product indicating that the trifunctional gene product was expressed in yeast primarily in a fully active, undegraded form. By placing the subcloned N-TRP1 gene under the control of the inducible PHO5 promoter from yeast, the expression of all three activities was increased to more than ten fold that of wild-type yeast and the overproduced protein could be visualized by SDS-polyacrylamide gel electrophoresis of crude extract and Coomassie Blue staining. Using the expression system described the effect of selective deletion of regions of the coding sequence of the N-TRP1 gene on expression of the three activities was tested. Expression of either the F- or C-domains, catalyzing respectively the PRA isomerase or InGP synthase activities, did not depend on the presence of the other domain in the active polypeptide. Furthermore, normal dimer formation occurred with a protein active for InGP synthase in a deletion derivative lacking most of the PRA isomerase domain, ruling out the hypothesis that interaction between the active site regions for PRA isomerase and InGP synthase accounted for dimer formation in the trifunctional product.
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    HSP12, a new small heat shock gene of Saccharomyces cerevisiae: Analysis of structure, regulation and function (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 97-106 
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    ISSN: 1617-4623
    Keywords: Heat shock ; Saccharomyces cerevisiae ; Stationary phase ; cAMP ; Thermotolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have isolated a new small heat shock gene, HSP12, from Saccharomyces cerevisiae. It encodes a polypeptide of predicted Mr 12 kDa, with structural similarity to other small heat shock proteins. HSP12 gene expression is induced several hundred-fold by heat shock and on entry into stationary phase. HSP12 mRNA is undetectable during exponential growth in rich medium, but low levels are present when cells are grown in minimal medium. Analysis of HSP12 expression in mutants affected in cAMP-dependent protein phosphorylation suggests that the gene is regulated by cAMP as well as heat shock. A disruption of the HSP12 coding region results in the loss of an abundant 14.4 kDa protein present in heat shocked and stationary phase cells. It also leads to the induction of the heat shock response under conditions normally associated with low-level HSP12 expression. The HSP12 disruption has no observable effect on growth at various temperatures, nor on the ability to acquire thermotolerance.
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    The RHC21 gene of budding yeast, a homologue of the fission yeast rad21 +gene, is essential for chromosome segregation (1998)
    Springer
    Molecular genetics and genomics 257 (1998), S. 149-156 
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    ISSN: 1617-4623
    Keywords: Key words Chromosome segregation ; Nocodazole ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Saccharomyces cerevisiae gene RHC21 is a homologue of the fission yeast rad21 +gene, which affects the sensitivity of cells to γ-irradiation and is essential for cell growth in S. pombe. Disruption of the RHC21 gene showed that it is also essential in S. cerevisiae. To examine its function in cell growth further, we have isolated temperature-sensitive mutants for the RHC21 gene and characterized one of them, termed rhc21-sk16. When this mutant was incubated at 36° C, the percentage of large-budded cells was increased. Most of the large-budded cells had aberrant nuclear structures, such as unequally extended nuclear DNA with incompletely elongated spindles across the mother-daughter neck or only in a mother cell. Furthermore, a circular minichromosome is more unstable in the mutant than in the wild-type, even at 25° C. Flow cytometry showed that the bulk of DNA replication takes place normally at the restrictive temperature in the mutant. These results indicated that the RHC21 gene is required for proper segregation of the chromosomes. In addition, we found that the mutant is sensitive not only to UV radiation and γ-rays but also to the antimicrotubule agent nocodazole at 25° C. This suggests that the RHC21 gene is involved in the microtubule function. We discuss how the RHC21 gene product may be involved in chromosome segregation and microtubule function.
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    URL: http://dx.doi.org/10.1007/s004380050634
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    Ste50p is involved in regulating filamentous growth in the yeast Saccharomyces cerevisiae and associates with Ste11p (1998)
    Springer
    Molecular genetics and genomics 259 (1998), S. 29-38 
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    ISSN: 1617-4623
    Keywords: Key words Pheromone response ; Pseudohyphal development ; Signal modulation ; STE50/STE11 ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract STE50 is required to sustain pheromone-induced signal transduction in S. cerevisiae. Here we report that Ste50p is involved in regulating pseudohyphal development. Both of these processes are also dependent on Ste11p. Deletion of STE50 leads to defects in filamentous growth, which can be suppressed by overproduction of Ste11p. Overexpression of STE11 also suppresses the mating defects of ste50 mutants. We have analysed the physical association between Ste50p and Ste11p in extracts of cells harvested under various conditions. A Ste11p-Ste50p complex can be isolated from extracts of cells in which the pheromone response has been activated, as well as from normally growing cells. Formation of the Ste50p-Ste11p complex does not require Gα, Gβ, Ste20p or Ste5p. Oligomerisation of Ste11p is shown to be independent of activation of the pheromone response pathway, and occurs in the absence of Ste50p. We conclude that Ste50p is necessary for Ste11p activity in at least two differentiation programmes: mating and filamentous growth.
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    URL: http://dx.doi.org/10.1007/s004380050785
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    Oligomers of the Cdc7/Dbf4 protein kinase exist in the yeast cell (1998)
    Springer
    Molecular genetics and genomics 259 (1998), S. 429-436 
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    ISSN: 1617-4623
    Keywords: Key words Protein phosphorylation ; Allosteric regulation ; DNA replication ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cdc7/Dbf4 protein kinase is required for the initiation of DNA replication in Saccharomyces cerevisiae. Cdc7/Dbf4 protein kinase is not a cyclin-dependent kinase (CDK), but is regulated in a similar fashion in that the Cdc7 kinase subunit is inactive in the absence of the regulatory subunit Dbf4. In contrast to what is known about CDKs, Cdc7/Dbf4 protein kinase is shown to be an oligomer in the cell in this report. Genetic data that support this claim include interallelic complementation between several cdc7ts alleles and the cdc7T281A allele and also the results of experiments using the two-hybrid system with Cdc7 in both DNA-binding and transactivation domain plasmids. A molecular interaction between two different Cdc7 molecules was shown by using a HA-tagged Cdc7 protein that differs in size from the wild-type Cdc7 protein: an anti-HA antibody immunoprecipitates both proteins in appproximately equal stoichiometry. Analysis of the native molecular weight of Cdc7/Dbf4 protein kinase is consistent with oligomerization of the Cdc7 protein in that complexes of about 180 and 300 kDa were found. Oligomers of Cdc7 protein may exist for the purpose of allosteric regulation or to allow phosphorylation of multiple substrate protein molecules.
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    URL: http://dx.doi.org/10.1007/s004380050833
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    Interchromosomal and intrachromosomal recombination in rad 18 mutants of Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 222 (1990), S. 25-32 
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    ISSN: 1617-4623
    Keywords: Intrachromosomal and interchromosomal recombination ; Saccharomyces cerevisiae ; RAD18
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The frequency of intra- and interchromosomal recombination was determined in RAD18 and rad18 deletion and rad18-3 mutant strains. It was found that spontaneous interchromosomal recombination at trp5, his1, ade2, and MAT was elevated 10- to 70-fold in the rad18-3 and rad18Δ mutants as compared to the RAD + strains. On the other hand the frequencies of spontaneous intrachromosomal recombination for the his3Δ3′, his3Δ5′ and the his4C −, his4A − duplications and for heterothallic mating type switching were only marginally elevated in the rad18 deletion mutant, and recombination between ribosomal DNA repeats was only 2-fold elevated in the rad18-3 mutant. These differences may be due to a haploid versus diploid specific difference. However interchromosomal recombination was elevated 40-fold and intrachromosomal recombination was only marginally (1.5-fold) elevated in a diploid homozygous for rad18Δ, arguing against a haploid versus diploid specific difference. Possible explanations for the difference in the elevated levels of intra- versus interchromosomal spontaneous recombination are discussed.
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    DNA sequence elements required for transcription initiation of the Schizosaccharomyces pombe ADH gene in Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 407-416 
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    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Schizosaccharomyces pombe ; Transcription initiation ; ADH gene ; TATA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The roles of the TATA element and sequences near the mRNA initiation site in specifying the location of initiation sites in Saccharomyces cerevisiae were examined, using the Schizosaccharomyces pombe ADH gene. The importance of spacing was demonstrated by analysis of a series of deletions that removed from 8–50 bp between the TATA element and ATG translation initiation site of this gene. Primer extension mapping showed that increasing deletion length is associated with a progressive shift downstream in the location of the initiation sites. The distance of a given site from the promoter affected the relative ability of the site to be utilized for initiation. For this gene, a permissive region for transcription initiation exists between 55 and 125 bases downstream of the TATA element, and a zone of 75–115 bases allows maximal usage of an initiation site. The presence of a TATA sequence was shown to be necessary in S. cerevisiae for maintaining the location of this “window” of initiation. The TATA sequence is essential for function of the gene in S. pombe. This gene, as well as the majority of the 63 S. cerevisiae genes surveyed, uses initiation sites which fit a PyAA/T(Pu) consensus. Cis-acting mutations were recovered which restored ADH activity to a deletion allele that initiates its mRNAs downstream of the ATG. DNA sequence and transcript analysis with these mutants confirmed the requirement of proper spacing and conformity of initiation sites to the PyAA/T(Pu) consensus for efficient transcript initiation.
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    TUF factor binds to the upstream region of the pyruvate decarboxylase structural gene (PDC1) of Saccharomyces cerevisiae (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 449-456 
    Details
    ISSN: 1617-4623
    Keywords: Saccharomyces cerevisiae ; Gene regulation ; TUF ; Pyruvate decarboxylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The upstream activation site of the pyruvate decarboxylase gene, PDC1, of Saccharomyces cerevisiae contains an RPG box, and mediates the increase in expression of a PDC1-lacZ fusion gene during growth on glucose. Oligonucleotide replacement experiments indicate that the RPG box functions as an absolute activator of expression, but other elements (possibly CTTCC repeats) are required for carbon source regulation, and maximal expression. Gel retardation and oligonucleotide competition experiments suggest that the DNA binding factor TUF interacts with the RPG box in the upstream region of PDC1. Binding of TUF factor is not carbon source dependent in in vitro experiments, and is probably not responsible for glucose induction of PDC1 expression.
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    Synthesis of glutamine, glycine and 10-formyl tetrahydrofolate is coregulated with purine biosynthesis in Saccharomyces cerevisiae (1998)
    Springer
    Molecular genetics and genomics 259 (1998), S. 246-255 
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    ISSN: 1617-4623
    Keywords: Key words Transcription factors Bas1p/Bas2p ; GLN1/SHM2/MTD1 ; Adenine repression ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glutamine, glycine and 10-formyl tetrahydrofolate are consumed during de novo purine biosynthesis. We have found that, in Saccharomyces cerevisiae, synthesis of these cosubstrates is coregulated with synthesis of enzymes of the purine biosynthetic pathway. Analysis of three genes required for synthesis of glutamine, glycine and 10-formyl tetrahydrofolate (GLN1, SHM2 and MTD1, respectively) shows that their expression is repressed by adenine and requires the transcription factors Bas1p and Bas2p. Northern analysis reveals that regulation of SHM2 and MTD1 expression by adenine takes place at the transcriptional level. We also show that Bas1p and Bas2p bind in vitro to the promoters of the SHM2 and MTD1 genes, and that mutations in the consensus Bas1p binding sequences strongly affect expression of these genes in vivo. Finally, we have found that a SHM2-lacZ fusion is expressed at a significantly higher level in a bas2-2 disrupted strain than in bas1-2 or bas1-2 bas2-2 mutant strains. The BAS1-dependent, BAS2-independent expression of SHM2-lacZ suggests that, in the absence of Bas2p, Bas1p can interact with another protein partner to activate SHM2 expression.
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    Four hydrophobic amino acid residues in the C-terminal effector domain of the yeast Mig1p repressor are important for its in vivo activity (1998)
    Springer
    Molecular genetics and genomics 260 (1998), S. 269-279 
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    ISSN: 1617-4623
    Keywords: Key words MIG1 ; Glucose repression ; Kluyveromyces marxianus ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Mig1 repressor is a zinc finger protein that mediates glucose repression in yeast. Previous work in Saccharomyces cerevisiae has shown that two domains in Mig1p are required for repression: the N-terminal zinc finger region and a C-terminal effector domain. Both domains are also conserved in Mig1p homologs from the distantly related yeasts Kluyveromyces lactis and K. marxianus, and these Mig1 proteins can fully replace the endogenous Mig1p in S. cerevisiae. We have now made a detailed analysis of the conserved C-terminal effector domain in Mig1p from K. marxianus, using expression in S. cerevisiae to monitor its function. First, a series of small deletions were made within the effector domain. Second, an alanine scan mutagenesis was carried out across the effector domain. Third, double, triple and quadruple mutants were made that affect certain residues within the effector domain. Our results show that four conserved residues within the effector domain, three leucines and one isoleucine, are particularly important for its function in vivo. The analysis further revealed that while the C-terminal effector domain of KmMig1p mediates a seven- to nine-fold repression of the reporter gene, a five- to sixfold residual effect also exists that is independent of the C-terminal effector domain. Similar results were obtained when the corresponding mutations were made in ScMig1p. Moreover, we found that mutations in these residues affect the interaction between Mig1p and the general corepressor subunit Cyc8p (Ssn6p). Modeling of the C-terminal effector domain using a protein of known structure suggests that it may be folded into an α-helix.
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    Involvement of histidine permease (Hip1p) in manganese transport in Saccharomyces cerevisiae (1998)
    Springer
    Molecular genetics and genomics 259 (1998), S. 541-548 
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    ISSN: 1617-4623
    Keywords: Key words Manganese ; Divalent cations ; Transport ; HIP1 ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a search for components involved in Mn2+ homeostasis in the budding yeast Saccharomyces cerevisiae, we isolated a mutant with modifications in Mn2+ transport. The mutation was found to be located in HIP1, a gene known to encode a high-affinity permease for histidine. The mutation, designated hip1–272, caused a frameshift that resulted in a stop codon at position 816 of the 1812-bp ORF. This mutation led to Mn2+ resistance, whereas the corresponding null mutation did not. Both hip1–272 cells and the null mutant exhibited low tolerance to divalent cations such as Co2+, Ni2+, Zn2+, and Cu2+. The Mn2+ phenotype was not influenced by supplementary histidine in either mutant, whereas the sensitivity to other divalent cations was alleviated by the addition of histidine. The cellular Mn2+ content of the hip1–272 mutant was lower than that of wild type or null mutant, due to increased rates of Mn2+ efflux. We propose that Hip1p is involved in Mn2+ transport, carrying out a function related to Mn2+ export.
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    Identification and characterisation of an RPD3 homologue from maize (Zea mays L.) that is able to complement an rpd3 null mutant of Saccharomycescerevisiae (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 288-296 
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    ISSN: 1617-4623
    Keywords: Key wordsZea mays ; Saccharomyces cerevisiae ; Gene regulation ; Histone deacetylase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In mammals, yeast and Drosophila, the histone deacetylase RPD3 proteins can alter the expression of genes involved in fundamental biological processes by affecting the degree of acetylation of histones and changing chromatin structure. Here we report the isolation of a cDNA sequence encoding an RPD3 homologue from maize, which is able to complement the phenotype of an rpd3 null mutant of the yeast Saccharomyces cerevisiae. The expression of the corresponding gene(s) was assessed in different maize tissues. The number of homologous loci was estimated by Southern hybridisation to be in the range of two to three, and the chromosomal location of one of these loci was determined. Phylogenetic analysis and tests for relative divergence rates, using related RPD3 sequences from different species, were performed, and suggest that different polymorphic forms of RPD3-like proteins that evolve at distinct rates are present in the species considered.
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    The involvement of the RAD6 gene in starvation-induced reverse mutation in Saccharomyces cerevisiae (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 546-552 
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    ISSN: 1617-4623
    Keywords: Key words Adaptive mutation ; DNA repair ; Saccharomyces cerevisiae ; Starvation ; RAD6
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The accumulation of Ade+ revertants during adenine starvation and Trp+ revertants during tryptophan starvation in haploid polyauxotrophic strains of Saccharomyces cerevisiae occurs in a time-dependent manner. Accumulation of revertants is enhanced in Rad6− strains, suggesting that starvation-induced reversion is influenced by some of the RAD6 gene functions. The higher frequency of adaptive reversions in Rad6− strains is somewhat influenced by, but does not totally depend on, the genetic background. Therefore, the RAD6 gene product is involved in maintaining a low level not only of spontaneous mutation but also of starvation-induced reversion. The starvation-induced Ade+ and Trp+ reversions both appear to be adaptive. The analysis of growth characteristics and the genotype of revertants shows a difference between early and late-appearing revertants. These results support the hypothesis that the adaptivity of starvation-induced reversion is based on the selective fixation of random mutations, and particularly on transcription-enhanced repair and/or mutagenesis processes.
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    Identification, cloning and characterization of a derepressible Na+-coupled phosphate transporter in Saccharomyces cerevisiae (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 628-638 
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    ISSN: 1617-4623
    Keywords: Key words Phosphate transport ; PHO89 ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on the high sequence homology between the yeast ORF YBR296c (accession number P38361 in the SWISS-PROT database) and the PHO4 gene of Neurospora crassa, which codes for a Na+/Pi cotransporter with twelve putative transmembrane domains, the YBR296c ORF was considered to be a promising candidate gene for a plasma membrane-bound phosphate transporter in Saccharomyces cerevisiae. Therefore, this gene, here designated PHO89, was cloned and a set of deletion mutants was constructed. We then studied their Pi uptake activity under different conditions. We show here that a transport activity displayed by PHO89 strains under alkaline conditions and in the presence of Na+ is absent in pho89 null mutants. Moreover, when the pH was lowered to pH 4.5 or when Na+ was omitted, this activity decreased significantly, reaching values close to those exhibited by the Δpho89 mutant. Studies of the acid phosphatase activity of these strains, as well as promoter sequence analysis, suggest that expression of the PHO89 gene is under the control of the PHO regulatory system. Northern analysis shows that this gene is only transcribed under conditions of Pi limitation. This is, to our knowledge, the first demonstration that the PHO89 gene codes for the Na+/Pi cotransporter previously characterized by kinetic studies, and represents the only Na+-coupled secondary anion transport system so far identified in S. cerevisiae. Pho89p has been shown to have an apparent Km of 0.5 μM and a pH optimum of 9.5, and is highly specific for Na+; activation of transport is maximal at a Na+ concentration of 25 mM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380050776
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  • 94
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    Isolation and characterization of the membrane-bound cytochrome c-554 from the thermophilic green photosynthetic bacterium Chloroflexus aurantiacus (1990)
    Springer
    Photosynthesis research 23 (1990), S. 29-38 
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    ISSN: 1573-5079
    Keywords: cytochrome c ; photosynthesis ; photosynthetic bacteria ; electron transport ; Chloroflexus aurantiacus ; green bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The membrane-bound photooxidizable cytochrome c-554 from Chloroflexus aurantiacus has been purified. The purified protein runs as a single heme staining band on SDS-PAGE with an apparent molecular mass of 43 000 daltons. An extinction coefficient of 28 ± 1 mM−1 cm−1 per heme at 554 nm was found for the dithionite-reduced protein. The potentiometric titration of the hemes takes place over an extended range, showing clearly that the protein does not contain a single heme in a well-defined site. The titration can be fit to a Nernst curve with midpoint potentials at 0, +120, +220 and +300 mV vs the standard hydrogen electrode. Pyridine hemochrome analysis combined with a Lowry protein assay and the SDS-PAGE molecular weight indicates that there are a minimum of three, and probably four hemes per peptide. Amino acid analysis shows 5 histidine residues and 29% hydrophobic residues in the protein. This cytochrome appears to be functionally similar to the bound cytochrome from Rhodopseudomonas viridis. Both cytochrome c-554 from C. aurantiacus and the four-heme cytochrome c-558-553 from R. viridis appear to act as direct electron donors to the special bacteriochlorophyll pair of the photosynthetic reaction center. They have a similar content of hydrophobic amino acids, but differ in isoelectric point, thermodynamic characteristics, spectral properties, and in their ability to be photooxidized at low temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00030060
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  • 95
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    The effect of leaf size on mutual shading and cultivar differences in soybean leaf photosynthetic capacity (1990)
    Springer
    Photosynthesis research 23 (1990), S. 67-72 
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    ISSN: 1573-5079
    Keywords: leaf size ; light ; photosynthesis ; shading ; soybeans ; specific leaf weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the basis of the negative relationship between leaf size and photosynthetic rate per unit of area among five cultivars of soybeans. Exposure of developing mainstem leaves to light, and sizes and light saturated photosynthesis rates of those leaves at maturity were compared in cultivars grown in field plots for two years at Beltsville, Maryland, USA. Plants were grown both in stands at 2.5 cm by 1 m spacing and as isolated plants. While cultivar differences in leaf size were large and consistent in both planting arrangements, significant cultivar differences in light saturated photosynthetic rates were found only in plants grown in stands. Similarly, leaf size was significantly correlated with specific leaf weight only for plants grown in stands. The mainstem apex and developing mainstem leaves experienced more severe shading in large-leaved cultivars than in small-leaved cultivars when plants were grown in stands. Thus, cultivar differences in photosynthetic capacity were probably a consequence of differences in the exposure of developing leaves to light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00030064
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  • 96
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    On the nature of the photosynthetic energy storage monitored by photoacoustic spectroscopy (1990)
    Springer
    Photosynthesis research 23 (1990), S. 313-318 
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    ISSN: 1573-5079
    Keywords: thylakoid membranes ; electron transfer ; photoacoustic spectroscopy ; energy storage ; photosynthesis ; plastoquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic energy storage yield of uncoupled thylakoid membranes was monitored by photoacoustic spectroscopy at various measuring beam intensities. The energy storage rate as evaluated by the half-saturation measuring beam intensity (i50) was inhibited by 3-(3,4-dichlorophenyl)-1,1 dimethylurea, by heat inactivation or by artificial electron acceptors specific for photosystem I or photosystem II; and was activated by electron donors to photosystem I. The reactions involving both photosystems were all characterized by a similar maximal energy storage yield of 16±2 percent. The data could be interpreted if we assumed that the energy storage elicited by the photosystems at 35 Hz is detected at the level of the plastoquinone pool.
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    URL: http://dx.doi.org/10.1007/BF00034861
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  • 97
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    Retrospective of a botanist (1990)
    Springer
    Photosynthesis research 25 (1990), S. 77-82 
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    ISSN: 1573-5079
    Keywords: autobiography ; chloroplast structure ; chloroplast proteins ; chloroplast lipids ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An autobiographic report of studies on the elucidation of the structure of the chloroplast is presented here. It deals with the discovery of the lamellar structure of chloroplasts by polarization-microscopy, the representation of their layer-like structure with the ultraviolet microscope and the results obtained by the electron-microscope leading to the discovery of the structural elements of the lamellar system. These lamellar structures were in the form of vesicles, and were named thylakoids. Isolation of the chloroplasts made it possible to determine their chemical composition. Amphiphilic lipids, together with water, create bimolecular layers and, therefore, are responsible for the structure of the thylakoid-membranes. The role of membrane proteins was emphasized. The isolation of the individual polypeptides was possible after dissociation in sodium-dodecyl-sulfate. Antisera to these polypeptides were used to localize them in the membrane. These antisera are able to inhibit special steps in the electron transport. Our results of the spectroscopic examination of photosynthetic membrane components are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035456
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  • 98
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    A reassessment of the use of herbicide binding to measure photosystem II reaction centres in plant thylakoids (1990)
    Springer
    Photosynthesis research 24 (1990), S. 109-113 
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    ISSN: 1573-5079
    Keywords: atrazine ; diuron ; photosystem II ; photosynthesis ; thylakoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The binding of the herbicide atrazine to thylakoid membranes is often used to quantify Photosystem II reaction centres. Two atrazine binding sites, with high and low affinities, have been observed on the D1 and D2 polypeptides of Photosystem II, respectively (McCarthy S., Jursinic P. and Stemler A. (1988) Plant Physiol. 86S:46). We have observed that the accessibility of the low-affinity binding sites is variable, being limited in freshly isolated thylakoids or in fresh frozen-thawed thylakoids, but increasing during storage of the membranes on ice. In contrast, the accessibility of the high-affinity binding sites, which are titratable at low concentrations (〈 500 nM) of herbicide, is much less variable, although the dissociation constant is greatly influenced by ethanol. We conclude that to quantify Photosystem II reaction centres by atrazine binding, it is sufficient and more reliable to assay only the high-affinity binding sites.
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    URL: http://dx.doi.org/10.1007/BF00032650
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  • 99
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    Nucleotide sequence and expression of the two genes encoding D2 protein and the single gene encoding the CP43 protein of Photosystem II in the cyanobacterium synechococcus sp. PCC 7002 (1990)
    Springer
    Photosynthesis research 24 (1990), S. 137-150 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; photosynthesis ; psbC gene ; psbD gene ; translational start codon ; overlapping genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The unicellular photoheterotrophic cyanobacterium Synechococcus sp. PCC 7002 was shown to encode two genes for the Photosystem II reaction center core protein D2 and one gene for the reaction center chlorophyhll-binding protein CP43. These three genes were cloned and their DNA sequences determined along with their flanking DNA sequences. Northern hybridization experiments show that both genes which encode D2, psbD1 and psbD2, are expressed at roughly equivalent levels. For each of the two psbD genes, there are 18 nucleotide differences among the 1059 nucleotides which are translated. The DNA sequences surrounding the coding sequences are nearly 70% divergent. Despite the DNA sequence differences in the genes, the proteins encoded by the two genes are predicted to be identical. The proteins encoded by psbD1 and psbD2 are ∼92% homologous to other sequenced cyanobacterial psbD genes and ∼86% homologous to sequenced chloroplast-encoded psbD genes. The single gene for CP43, psbC, overlaps the 3′ end of psbD1 and is co-transcribed with it. Results from previous sequencing of psbC genes encoded by chloroplasts suggest that the 5′ end of the psbC gene overlaps the 3′ end of the coding sequence of psbD by ∼50 nucleotides. In Synechococcus sp. PCC 7002, the methionine codon previously proposed to be the start codon for psbC is replaced by an ACG (threonine) codon. We propose an alternative start for the psbC gene at a GTG codon 36 nucleotides downstream from the threonine codon. This GTG codon is preceded by a consensus E. coli-like ribosome binding sequence. Both the GTG start codon and its preceding ribosome binding sequence are conserved in all psbC genes sequenced from cyanobacteria and chloroplasts. This suggests that all psbC genes start at this alternative GTG codon. Based on this alternative start codon, the gene product is ∼85% identical to other cyanobacterial psbC gene products and ∼77% identical to eucaryotic chloroplast-encoded psbC gene products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032594
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  • 100
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    Effect of photon flux density on inorganic carbon accumulation and net CO2 exchange in a high-CO2-requiring mutant of Chlamydomonas reinhardtii (1990)
    Springer
    Photosynthesis research 24 (1990), S. 245-252 
    Details
    ISSN: 1573-5079
    Keywords: inorganic carbon transport ; light ; Chlamydomonas ; CO2 exchange ; photorespiration ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of photon flux density on inorganic carbon accumulation and photosynthetic CO2 assimilation was determined by CO2 exchange studies at three, limiting CO2 concentrations with a ca-1 mutant of Chlamydomonas reinhardiii. This mutant accumulates a large internal inorganic carbon pool in the light which apparently is unavailable for photosynthetic assimilation. Although steady-state photosynthetic CO2 assimilation did not respond to the varying photon flux densities because of CO2 limitation, components of inorganic-carbon accumulation were not clearly light saturated even at 1100 μmol photons m-2 s-1, indicating a substantial energy requirement for inorganic carbon transport and accumulation. Steady-state photosynthetic CO2 assimilation responded to external CO2 concentrations but not to changing internal inorganic carbon concentrations, confirming that diffusion of CO2 into the cells supplies most of the CO2 for photosynthetic assimilation and that the internal inorganic carbon pool is essentially unavailable for photosynthetic assimilation. The estimated concentration of the internal inorganic carbon pool was found to be relatively insensitive to the external CO2 concentration over the small range tested, as would be expected if the concentration of this pool is limited by the internal to external inorganic carbon gradient. An attempt to use this CO2 exchange method to determine whether inorganic carbon accumulation and photosynthetic CO2 assimilation compete for energy at low photon flux densities proved inconclusive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032312
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