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  • 1
    Electronic Resource
    Electronic Resource
    Molecular and physiological aspects of aflatoxin and sterigmatocystin biosynthesis by Aspergillus tamarii and A. ochraceoroseus (2000)
    Springer
    Applied microbiology and biotechnology 53 (2000), S. 605-609 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Until recently, only three species (Aspergillus flavus, A. parasiticus and A. nomius) have been widely recognized as producers of aflatoxin. In this study we examine aflatoxin production by two other species, A. tamarii and A. ochraceoroseus, the latter of which also produces sterigmatocystin. Toxin-producing strains of A. tamarii and A. ochraceoroseus were examined morphologically, and toxin production was assayed on different media at different pH levels using thin layer chromatography and a densitometer. Genomic DNA of these two species was probed with known aflatoxin and sterigmatocystin biosynthesis genes from A. flavus, A. parasiticus and A. nidulans. Under the high stringency conditions, A. tamarii DNA hybridized to all four of the A. flavus and A. parasiticus gene probes, indicating strong similarities in the biosynthetic pathway genes of these three species. The A. ochraceoroseus DNA hybridized weakly to the A. flavus and A. parasiticus verB gene probe, and to two of the three A. nidulans probes. These data indicate that, at the DNA level, the aflatoxin and sterigmatocystin biosynthetic pathway genes for A. ochraceoroseus are somewhat different from known pathway genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051664
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  • 2
    Electronic Resource
    Electronic Resource
    Generation of aflR disruption mutants of Aspergillus parasiticus (2000)
    Springer
    Applied microbiology and biotechnology 53 (2000), S. 680-684 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The aflR gene of Aspergillus parasiticus and A. flavus encodes a binuclear zinc-finger, DNA-binding protein, AflR, responsible for activating the transcription of all known aflatoxin biosynthetic genes including itself. Studies to determine how environmental and nutritional factors affect aflR expression and hence aflatoxin production in A. parasiticus have been difficult to perform due to the lack of aflR“knockout” mutants. Transformation of an O-methylsterigmatocystin (OMST)-accumulating strain of A. parasiticus with an aflR-niaD gene disruption vector resulted in clones harboring a recombinationally inactivated aflR gene which no longer produced OMST or aflR transcript. By transformation of this aflR disruptant strain with constructs containing mutated versions of the aflR promoter, we identified three cis-acting sites that were necessary for aflR function: an AflR-binding site, a PacC-binding site, and a G + A-rich site near the transcription start site of aflR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530000319
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  • 3
    Electronic Resource
    Electronic Resource
    ONSAGER'S RELATION AND THE NON-ISOTHERMAL DIFFUSION OF WATER VAPOR1 (1963)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 67 (1963), S. 126-129 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100795a030
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  • 4
    Electronic Resource
    Electronic Resource
    Plant Water Potential Gradients Measured in the Field by Freezing Point (1971)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 24 (1971), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A portable freezing point meter was used in the field to measure the water potential gradients in sunflower (Helianthus annuus), beans (Phaseolus vulgaris), corn (Zea mays), wheat (Triticum aestivum), pumpkin (Cucurbita pepo), potato (Solanum tuberosum), alfalfa (Medicago sativa), and sugarbeets (Beta vulgaris). The measurements were made between daybreak and sunrise, and again during the middle of the afternoon on days when the potential evapotranspiration varied between 6.5 and 8.0 mm of water.The gradients varied from a maximum of 0.2 bar per cm in a wheat, down to an undetectable value for pumpkin. Although most of the soil in the root zone was kept at potentials above –1 bar, the bulk of the root tissue had water potentials of –5 to –10 bars. Differences in water potential between shaded and unshaded leaves, and between leaf tissue and guttation fluid suggested a similar drop of several bars between xylem elements and the surrounding leaf tissue in some plant species. The implications of such drops are discussed with respect to plant water transport equations and pressure cell potential measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1971.tb03510.x
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  • 5
    Electronic Resource
    Electronic Resource
    High-frequency stable transformation of cotton (Gossypium hirsutum L.) by particle bombardment of embryogenic cell suspension cultures (2000)
    Springer
    Plant cell reports 19 (2000), S. 539-545 
    Details
    ISSN: 1432-203X
    Keywords: Key words Biolistic transformation ; Cotton ; Embryogenic cell suspension ; Gossypium hirsutum ; Stable expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable transformation of cotton (Gossypium hirsutum L.) at a high frequency has been obtained by particle bombardment of embryogenic cell suspension cultures. Transient and stable expression of the β-glucuronidase (GUS) gene was monitored in cell suspension cultures. Transient expression, measured 48 h after bombardment, was abundant, and stable expression was observed in over 4% of the transiently expressing cells. The high efficiency of stable expression is due to the multiple bombardment of rapidly dividing cell suspension cultures and the selection for transformed cells by gradually increasing the concentrations of the antibiotic Geneticin (G418). Southern analysis indicated a minimum transgene copy number of one to four in randomly selected plants. Fertile plants were obtained from transformed cell cultures less than 3 months old. However, transgenic and control plants from cell cultures older than 6 months produced plants with abnormal morphology and a high degree of sterility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050770
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  • 6
    Electronic Resource
    Electronic Resource
    Inhibition of fungal growth in planta and in vitro by transgenic tobacco expressing a bacterial nonheme chloroperoxidase gene (2000)
    Springer
    Plant cell reports 19 (2000), S. 333-338 
    Details
    ISSN: 1432-203X
    Keywords: Key words Chloroperoxidase ; Disease resistance ; Haloperoxidase ; Reactive oxygen species ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Transgenic tobacco plants producing chloroperoxidase (CPO-P), encoded by a novel gene from Pseudomonas pyrrocinia, were obtained by Agrobacterium-mediated transformation. Successful transformation was shown by PCR, Southern, northern and western blot analyses, and assays of CPO-P enzyme activity. Extracts from plants transformed with the CPO-P gene significantly reduced Aspergillus flavus colonies by up to 100% compared with extracts from control plants transformed with pBI121. Compared with controls, the transformed plants showed increased disease resistance in planta against a fungal pathogen, Colletotrichum destructivum, the causal agent of tobacco anthracnose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050736
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  • 7
    Electronic Resource
    Electronic Resource
    Isolation and characterization of experimentally induced, aflatoxin biosynthetic pathway deletion mutants of Aspergillus parasiticus (1999)
    Springer
    Applied microbiology and biotechnology 51 (1999), S. 808-812 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A plasmid vector (pDEL2) was engineered for the purpose of introducing a deletion within the aflatoxin (AF) biosynthetic gene cluster of Aspergillus parasiticus. The vector was constructed by PCR amplification of a region of the AF gene cluster from an A. parasiticus isolate that had undergone an aberrant recombinational event during transformation with a norA-niaD gene disruption vector. This recombinational event resulted in the deletion of an approximately 6-kb region of the AF gene cluster and accumulation of the AF precursor averantin (AVN). Northern hybridization analysis confirmed that the deletion event resulted in no detectable transcription of the norA gene or the AF biosynthetic genes, avnA, verA, and ver-1. Transformation of A. parasiticus RHN1 with pDEL2 resulted in 16% of the transformants accumulating AVN. Southern hybridization analysis of randomly selected AVN-accumulating transformants indicated that all had undergone a double-crossover homologous, recombinational event resulting in the 6-kb norA to avnA deletion within the AF gene cluster. Aflatoxin precursor feeding studies performed on one of the AVN-accumulating, RHN1(pDEL2) transformants confirmed that the enzyme activities associated with the deleted genes were no longer present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051466
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  • 8
    Electronic Resource
    Electronic Resource
    RuP2 pool size indicated by CO2 assimilation following the abrupt loss of light (1986)
    Springer
    Photosynthesis research 8 (1986), S. 123-132 
    Details
    ISSN: 1573-5079
    Keywords: light stress ; photosynthesis ; RuP2 carboxylase ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Measurement of the changes in CO2 uptake by single leaves following the abrupt onset of darkness were made on sugarbeets (Beta vulgaris L.) and (Phaseolus vulgaris L.) The shape of the CO2 dark response curve was analyzed with respect to the reaction kinetics of CO2, RuP2 and RuP2 carboxylase. It was concluded that the net uptake of CO2 in the dark from a 1% O2 atmosphere can be approximately related to the pool size of the RuP2 substrate in the chloroplasts of C3 plants. This information was combined with CO2 levels and decay rates of the response curves to infer changes in carboxylase activity. Preliminary data are presented showing the relative concentration changes in RuP2 as light intensity decreases and as water stress increases. The method may prove useful in studies of plant response to environmental stresses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035243
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  • 9
    Electronic Resource
    Electronic Resource
    Calculation of CO2 gas phase diffusion in leaves and its relation to stomatal resistance (1981)
    Springer
    Photosynthesis research 2 (1981), S. 185-194 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; plant stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new theory and experimental method was developed to measure the diffusion resistance to CO2 in the gas phase of mesophyll leaf tissue. Excised leaves were placed in a chamber and their net evaporation and CO2 assimilation rates measured at two different ambient pressures. These data were used to calculate CO2 gas phase diffusion resistances. A variety of field grown leaves were tested and the effects of various experimental errors considered. Increasing the gas phase diffusion resistance decreased transpiration more than it decreased CO2 assimilation. It was concluded that gas phase diffusion resistance associated with CO2 assimilation may sometimes be 100 or 200 s·m-1 greater than the resistance implied by transpiration rates. This may be due to longer path lengths for the CO2 diffusion, constricted in places by the shape and arrangement of mesophyll cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00032357
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  • 10
    Electronic Resource
    Electronic Resource
    Discussion on ‘condensation and isothermal water transfer in cement mortar: Part II — transient condensation of water vapor’ by J. F. Daïan (1990)
    Springer
    Transport in porous media 5 (1990), S. 207-208 
    Details
    ISSN: 1573-1634
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00144604
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