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  • Column liquid chromatography  (495)
  • Triticum aestivum  (266)
  • photosynthesis  (212)
  • Zea mays  (193)
  • Fisheries
  • Inorganic Chemistry
  • Springer  (1,164)
  • 1990-1994  (1,164)
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Year
  • 101
    Electronic Resource
    Electronic Resource
    Comparison of selective agents for use with the selectable marker gene bar in maize transformation (1994)
    Springer
    Plant cell, tissue and organ culture 36 (1994), S. 1-7 
    Details
    ISSN: 1573-5044
    Keywords: bialaphos ; glufosinate ; phosphinothricin ; l-proline ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effectiveness of four phosphinothricin (PPT)-based selective agents were evaluated for use in maize transformation: glufosinate, bialaphos, Basta® and Herbiace®. Glufosinate and its commercial formulation, Basta®, were less effective in controlling growth of non-transgenic corn callus than the tripeptide, bialaphos, or its commercial formulation, Herbiace®. Addition of 25 mM l-proline had no significant effect on selection when using bialaphos. However, when l-proline was included with the selective agent glufosinate, selection was inhibited and callus growth was enhanced. At four weeks, callus growth on 0.3, 1.0 and 3.0 mg l-1 glufosinate in the presence of proline was 76, 43, and 21% of control growth, respectively, and in the absence of proline was only 32, 9, and 6% of control growth. Optimized selection protocols for Basta® and bialaphos yielded comparable numbers of transformants. Using these protocols, fertile transgenic plants were regenerated from transformed callus cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048308
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  • 102
    Electronic Resource
    Electronic Resource
    Genetic and environmental effects on abscisic acid accumulation in leaves of field-grown maize (1994)
    Springer
    Euphytica 78 (1994), S. 81-89 
    Details
    ISSN: 1573-5060
    Keywords: abscisic acid ; inheritance ; drought stress ; Zea mays ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study analyzes the components of phenotypic variation for abscisic acid (ABA) content in maize (Zea mays L.) leaves and the correlations with drought sensitivity index (DSI) and silk delay (SD), involved in the reaction to water deficit. Eight early- and seven medium-maturity inbreds were examined in field trials: in 1990 with low irrigation volume and in 1991 with low and high irrigation volumes. ABA concentration and DSI were investigated at growth stages (S) corresponding to stem elongation (S3), appearance of the first husks (S4), and mid-end of silking (S5). The ABA concentration was significantly higher in conditions of water deficit and in the later growth stage. The genetic component for ABA concentration attained higher relative values than those shown by DSI in the same growth stages and by SD; moreover, it increased from growth stage 3 to stage 5. The genotype × year and genotype × irrigation volume interactions were smaller for ABA concentration than for DSI and SD. The broad sense heritability on a plant basis, estimated in drought conditions, for ABA concentration ranged from 21.4 to 55.1% according to maturity group and growth stage. A wide variation was observed among lines for ABA concentration: the medium-maturity group showed a three-fold range (from 219 to 605 ng ABA g−1 dry weight). No clear relationships between ABA concentration, DSI and SD were found. These results indicate the feasibility of a selection for ABA concentration within segregating populations derived from crosses between the inbred lines herein tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021401
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  • 103
    Electronic Resource
    Electronic Resource
    Genetic basis of grain filling rate in wheat (Triticum aestivum L. emend. Thell.) (1994)
    Springer
    Euphytica 76 (1994), S. 33-44 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; genetic basis ; grain filling rate ; genetic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Grain filling rate in wheat (Triticum aestivum L. emend. Thell.) positively influences grain yield under a wide range of conditions. The effective utilization of this trait in breeding depends on an understanding of its genetic control. A study was, therefore, conducted to determine the genetic basis of grain filling rate in six crosses of wheat. Higher order genic interactions and/or linkage were important in the genetic regulation of grain filling rate (GFR) in the majority of crosses. Additive ([d]) and dominance ([h]) gene effects were important in the control of GFR in main ears (ME) and whole plant ears (WPE). Additive and additive × additive epistatic effects were the most important in the genetic control of GFR in last ears (LE). Location effects on genetic effects for GFR were significant (P 〈 0.05) in all ear types of some crosses except in ME. Genotype × environment interaction effects were important (P 〈 0.001) in LE and WPE. It was concluded that the inheritance of GFR is complex and is dependent on ear type. Breeding procedures that facilitate the exploitation of non-additive and additive gene effects were recommended for the genetic improvement of grain filling rate of wheat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024018
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  • 104
    Electronic Resource
    Electronic Resource
    Characterisation and origin of rust and powdery mildew resistance genes in VPM1 wheat (1994)
    Springer
    Euphytica 76 (1994), S. 53-61 
    Details
    ISSN: 1573-5060
    Keywords: stripe rust ; stem rust ; leaf rust ; powdery mildew ; common wheat ; environmental effects ; Puccinia striiformis ; Puccinia graminis ; Puccinia recondita ; Erysiphe graminis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The expression of rust resistances conferred by closely linked genes derived from VPM1 varied with environmental conditions and with genetic backgrounds. Under low light and low temperature conditions seedlings carrying Yr17 showed susceptible responses. Stem rust and leaf rust resistance genes Sr38 and Lr37 tended to confer more resistance at 17±2° C than at normal temperatures above 〉 20° C. These studies supported the hypothesis that Yr17, Lr37 and Sr38 were derived from Aegilops ventricosa, whereas Pm4b was probably derived from T. persicum. Studies on certain addition lines and parental stocks indicated that wheat cytoplasm may enhance the expression of Sr38.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024020
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  • 105
    Electronic Resource
    Electronic Resource
    Model studies of chlorophyll fluorescence reabsorption at chloroplast level under different exciting conditions (1994)
    Springer
    Photosynthesis research 40 (1994), S. 67-74 
    Details
    ISSN: 1573-5079
    Keywords: light conditions ; theoretical model ; barley leaf ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A theoretical model is presented describing the distortion of chlorophyll fluorescence spectra of a chloroplast or a group of chloroplasts by the effect of fluorescence reabsorption. Model calculations using the experimental data show that the primary reabsorption effect occurs already within one chloroplast and the spectral distortion depends significantly on the excitation regime of the chloroplast. A theoretical dependence of the distortion function, defined as a change in the F(685)/F(735) fluorescence band ratio, on the mean chlorophyll concentration in a chloroplast is predicted for different light excitation regimes. The distortion of measured chlorophyll fluorescence spectra at 77 K of chloroplast suspension adsorbed on filter papers of two strongly different diffusive reflectivities and at different mean chlorophyll concentrations are discussed with the help of the presented theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019046
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  • 106
    Electronic Resource
    Electronic Resource
    UV-B damage and protection at the molecular level in plants (1994)
    Springer
    Photosynthesis research 39 (1994), S. 475-489 
    Details
    ISSN: 1573-5079
    Keywords: DNA repair ; flavonoids ; gene expression ; oxidative stress ; photosynthesis ; promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Influx of solar UV-B radiation (280–320 nm) will probably increase in the future due to depletion of stratospheric ozone. In plants, there are several targets for the deleterious UV-B radiation, especially the chloroplast. This review summarizes the early effects and responses of low doses of UV-B at the molecular level. The DNA molecules of the plant cells are damaged by UV due to the formation of different photoproducts, such as pyrimidine dimers, which in turn can be combatted by specialized photoreactivating enzyme systems. In the chloroplast, the integrity of the thylakoid membrane seems to be much more sensitive than the activities of the photosynthetic components bound within. However, the decrease of mRNA transcripts for the photosynthetic complexes and other chloroplast proteins are among very early events of UV-B damage, as well as protein synthesis. Other genes, encoding defence-related enzymes, e.g., of the flavonoid biosynthetic pathway, are rapidly up-regulated after commencement of UV-B exposure. Some of the cis-acting nucleotide elements and trans-acting protein factors needed to regulate the UV-induced expression of the parsley chalcone synthase gene are known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014600
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  • 107
    Electronic Resource
    Electronic Resource
    Photosynthetic electrogenic events in native membranes ofChloroflexus aurantiacus. Flash-induced charge displacements within the reaction center-cytochromec 554 complex (1994)
    Springer
    Photosynthesis research 41 (1994), S. 135-143 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; electrometry ; membrane potential ; electron transfer ; charge displacement ; electrostatic ; Chloroflexus aurantiacus ; Rhodopseudomonas viridis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The thermophilic phototrophChloroflexus aurantiacus possesses a photosynthetic reaction center (RC) containing a pair of menaquinones as primary (QA) and secondary (QB) electron acceptors and a bacteriochlorophyll dimer (P) as a primary donor. A tetraheme cytochromec 554 with two high(H)- and two low(L)-potential hemes operates as an immediate electron donor for P. The following equilibrium Em,7 values were determined by ESR for the hemes in whole membrane preparations: 280 mV (H1), 150 mV (H2), 95 mV (L1) and 0 mV (L2) (Van Vliet et al. (1991) Eur. J. Biochem. 199: 317–323). Partial electrogenic reactions induced by a laser flash inChl. aurantiacus chromatophores adsorbed to a phospholipid-impregnated collodion film were studied electrometrically at pH 8.3. The photoelectric response included a fast phase of ΔΨ generation (τ 〈 10 ns, phase A). It was ascribed to the charge separation between P+ and QA − as its amplitude decreased both at high and low Eh values (Em,high=360±10 mV, estimated Em,low∼\s-160 mV) in good agreement with Em values for P/P+ and QA/QA − redox couples. A slower kinetic component appeared upon reduction of the cytochromec 554 hemes (phase C). With H1 reduced before the flash the amplitude of phase C was equal to 15–20% of that of phase A and its rise time was 1.2–1.3 μs: we attribute this phase to the electrogenic electron transfer from H1 to P+. Pre-reduction of H2 decreased the τ value to about 700–800 ns and increased the amplitude of phase C to 30–35% of that of phase A. Pre-reduction of L1 further accelerated phase C (up to τ of 500 ns) and induced a reverse electrogenic phase with τ of 12 μs and amplitude equal to 10% of phase A. Upon pre-reduction of L2 the rise time of phase C was decreased to about 300 ns and its amplitude decreased by 30%. The acceleration in the onset of phase C is explained by the acceleration of the rate-limiting H1 ⇒ P electrogenic reaction after reduction of the other hemes due to their electrostatic influence; a P-H1-(L1-L2)-H2 alignment of redox centers with an approximately rhombic arrangement of the cytochromec 554 hemes is proposed. The observed reverse phase is ascribed to the post-flash charge redistribution between the hemes. Redox titration of the amplitude of phase C yielded the Em,8.3 values of H1, H2 and L2 hemes: 340±10 mV for H1, 160±20 mV for H2 and −40±40 mV for L2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184153
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  • 108
    Electronic Resource
    Electronic Resource
    Pigment interactions in chlorosomes of various green bacteria (1994)
    Springer
    Photosynthesis research 41 (1994), S. 175-180 
    Details
    ISSN: 1573-5079
    Keywords: Chlorobium ; Chloroflexus ; chlorophyll ; light-harvesting ; photosynthesis ; resonance Raman
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Resonance Raman experiments were performed on different green bacteria. With blue excitation, i.e. under Soret resonance or preresonance conditions, resonance Raman contributions were essentially arising from the chlorosome pigments. By comparing these spectra and those of isolated chlorosomes, it is possible to evaluate how the latter retain their native structure during the isolation procedures. The structure of bacteriochlorophyll oligomers in chlorosomes was interspecifically compared, in bacteriochlorophyllc- and bacteriochlorophylle- synthesising bacteria. It appears that interactions assumed by the 9-keto carbonyl group are identical inChlorobium limicola, Chlorobium tepidum, andChlorobium phaeobacteroides. In the latter strain, the 3-formyl carbonyl group of bacteriochlorophylle is kept free from intermolecular interactions. By contrast, resonance Raman spectra unambiguously indicate that the structure of bacteriochlorophyll oligomers is slightly different in chlorosomes fromChloroflexus auranticus, either isolated or in the whole bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184158
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  • 109
    Electronic Resource
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    The formation and characterization of the in vitro polymeric aggregates of bacteriochlorophyllc homologs fromChlorobium limicola in aqueous suspension in the presence of monogalactosyl diglyceride (1994)
    Springer
    Photosynthesis research 41 (1994), S. 235-243 
    Details
    ISSN: 1573-5079
    Keywords: bacteriochlorophyll ; chlorosomeChlorobium limicola ; green bacteria ; photosynthesis ; monogalactosyl diglyceride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Artificial aggregates of bacteriochlorophyllc (BChlc) were formed in an aqueous medium in the presence of a lipid, monogalactosyl diglyceride (MGDG), and the optical properties of those aggregates were studied by absorption and circular dichroism (CD) mainly. Four BChlc homologs, ([E,E]BChlc F, [P,E]BChlc F, [E,M]BChlc F and [I,E]BChlc F), were isolated from the green photosynthetic bacteriumChlorobium limicola strain 6230. Above 0.0004%, MGDG induced a red-shift of the absorption maxima of BChlc aggregates. At 0.003% MGDG BChlc aggregates showed absorption maxima in the range of 724 to 745 (±3) nm with a shift of 12 to 24 (±3) nm depending on the homolog species. Four kinds of BChlc-MGDG aggregates showed characteristic CD spectra. [E,M]BChlc F gave rise to a CD spectrum similar to that of chlorosomes, while the other three gave spectra of opposite sign. These aggregates are sensitive to 1-hexanol treatment; in a saturating amount (0.85%) of 1-hexanol, all the homologs gave a monomer-like absorption spectrum peaking at 670nm. At an intermediate concentration (0.5%), [E,M]BChlc F showed an enhanced CD intensity, as observed in native chlorosomes. Resonance Raman spectra of the monomer-like BChlc samples indicated that the keto vibrational band at ca. 1640 cm−1 was considerably weakened by the 0.85% 1-hexanol treatment, however the 1680 cm−1 band characteristic of a free keto group did not appear. These results indicate that the artificial aggregates formed by purified BChlc homologs and MGDG are good models for studying chlorosomes structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184164
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  • 110
    Electronic Resource
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    Sensitivity of the relative Fpl level of chlorophyll fluorescence induction in leaves to the heat stress (1994)
    Springer
    Photosynthesis research 39 (1994), S. 201-204 
    Details
    ISSN: 1573-5079
    Keywords: automatic determination ; fluorescence parameters ; fluorometer ; induction curve ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The (Fpl-Fo)/Fv value of the fluorescence induction curve is shown to be a more suitable parameter to detect a wider range of heat stress damage to thylakoid membranes as compared to quantities t 1/2 (time of fluorescence rise from Fo to (Fo+Fm)/2 level) and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaacq% aHepaDaaaaaa!39D5!\[\overline \tau \] (the fluorescence induction time defined as the area above the induction curve normalized to Fv=1). A method for exact and automatic Fpl determination is presented. A break point in the quality and behaviour of the fluorescence induction curve of barley leaves incubated at 49°C was reached at the moment (about 240 s) when the transformation of PS II active (QB-reducing) to PS II inactive (QB-non-reducing) centres was completed. The meaning of the standard Fv and Fv/Fm parameter was then changed. The method of Fpl determination described here may help to increase the analytical value of the standard chlorophyll fluorometers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029387
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  • 111
    Electronic Resource
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    The role of iron in phytoplankton photosynthesis, and the potential for iron-limitation of primary productivity in the sea (1994)
    Springer
    Photosynthesis research 39 (1994), S. 275-301 
    Details
    ISSN: 1573-5079
    Keywords: chlorosis ; diagnostic ; flavodoxin ; iron-limitation ; photosynthesis ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Iron supply has been suggested to influence phytoplankton biomass, growth rate and species composition, as well as primary productivity in both high and low NO3 − surface waters. Recent investigations in the equatorial Pacific suggest that no single factor regulates primary productivity. Rather, an interplay of bottom-up (i.e., ecophysiological) and top-down (i.e., ecological) factors appear to control species composition and growth rates. One goal of biological oceanography is to isolate the effects of single factors from this multiplicity of interactions, and to identify the factors with a disproportionate impact. Unfortunately, our tools, with several notable exceptions, have been largely inadequate to the task. In particular, the standard technique of nutrient addition bioassays cannot be undertaken without introducing artifacts. These so-called ‘bottle effects’ include reducing turbulence, isolating the enclosed sample from nutrient resupply and grazing, trapping the isolated sample at a fixed position within the water column and thus removing it from vertical movement through a light gradient, and exposing the sample to potentially stimulatory or inhibitory substances on the enclosure walls. The problem faced by all users of enrichment experiments is to separate the effects of controlled nutrient additions from uncontrolled changes in other environmental and ecological factors. To overcome these limitations, oceanographers have sought physiological or molecular indices to diagnose nutrient limitation in natural samples. These indices are often based on reductions in the abundance of photosynthetic and other catalysts, or on changes in the efficiency of these catalysts. Reductions in photosynthetic efficiency often accompany nutrient limitation either because of accumulation of damage, or impairment of the ability to synthesize fully functional macromolecular assemblages. Many catalysts involved in electron transfer and reductive biosyntheses contain iron, and the abundances of most of these catalysts decline under iron-limited conditions. Reductions of ferredoxin or cytochrome f content, nitrate assimilation rates, and dinitrogen fixation rates are amongst the diagnostics that have been used to infer iron limitation in some marine systems. An alternative approach to diagnosing iron-limitation uses molecules whose abundance increases in response to iron-limitation. These include cell surface iron-transport proteins, and the electron transfer protein flavodoxin which replaces the Fe-S protein ferredoxin in many Fe-deficient algae and cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014588
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  • 112
    Electronic Resource
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    Molecular topology of the Photosystem II chlorophyll a binding protein, CP 43: Topology of a thylakoid membrane protein (1994)
    Springer
    Photosynthesis research 40 (1994), S. 11-19 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; membrane protein ; protein structure ; light harvesting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used antibodies generated against synthetic peptides to determine the topology of the 43 kD chlorophyll a binding protein (CP 43) of Photosystem II. Based on the pattern of proteolytic fragments detected (on western blots) by peptide specific antibodies, a six transmembrane span topological model, with the amino and carboxyl termini located on the stromal membrane surface, is predicted. This structure is similar to that predicted for CP 47, a PS II chlorophyll a binding protein (Bricker T (1990) Photosynth Res 24: 1–13). The model is discussed in reference to the possible location of chlorophyll binding sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019041
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  • 113
    Electronic Resource
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    The Wageningen Rhizolab — a facility to study soil-root-shoot-atmosphere interactions in crops (1994)
    Springer
    Plant and soil 161 (1994), S. 275-287 
    Details
    ISSN: 1573-5036
    Keywords: crop growth ; gas exchange ; minirhizotrons ; nutrients ; photosynthesis ; respiration ; rhizotron ; root observation ; root growth ; water balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A research facility is described for the integrated study of soil-root-shoot-atmosphere relationships in crops. The Wageningen Rhizolab has been in use since 1990, and consists of two rows, each with eight below-ground compartments aligned along a corridor. A rain shelter automatically covers the experimental area at the start of rainfall. Compartments are 125 cm × 125 cm and 200 cm deep. Each compartment has a separate drip irrigation system. Crop canopy photosynthesis, respiration, and transpiration can be measured simultaneously and continuously on four out of eight compartments at a time. Each compartment can be filled with a selected soil material (repacked soil) and is accessible from the corridor over its full depth. Multiple sensors for measuring soil moisture status, electrical conductivity, temperature, soil respiration, trace gases and oxygen are installed in spatial patterns in accordance with the requirements of the experiments. Sensors are connected to control and data-acquisition devices. Likewise, provisions have been made to sample manually the soil solution and soil atmosphere. Root observation tubes (minirhizotrons) are installed horizontally at depth intervals ranging from 5 cm (upper soil layers) to 25 cm (below 1 m). The facility is at present in use to study growth and development of vegetation (crops) in relation to drought, nutrient status, soil-borne diseases, and underground root competition. One important application is the study of elevated CO2 concentration and climate change and the way they affect crops and their carbon economy. Growth and development of field grown vegetables and winter cover crops are also evaluated. The common aspect of those studies is to gain a better understanding of crop growth under varying environmental conditions, and to collect datasets that may help to improve mechanistic crop growth simulation models that can address suboptimal growth conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046399
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  • 114
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    Root movements: Towards an understanding through attempts to model the processes involved (1994)
    Springer
    Plant and soil 165 (1994), S. 293-300 
    Details
    ISSN: 1573-5036
    Keywords: gravitropism ; living systems theory ; nutation ; Phleum pratense L. ; simulation ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Roots have the ability to change the direction of their forward growth. Sometimes these directional changes are rapid, as in mutations, or they are slower, as in tropisms. The gravitational force is always present and roots have an efficient graviperception mechanism which enables them to initiate gravitropic movements. In trying to model and simulate the course of gravitropic root movements with a view to analyse the component processes, the following aspects of the plant's interaction with gravity have been considered: (1) The level of organization (organism, organ, cell) at which the movement process is expressed; (2) whether the gravity stimulation event is dynamic or static (i.e. whether or not physiologically significant displacements take place with respect to the gravity vector); (3) the sub-systems involved in movement and the processes which they regulate; (4) the mathematical characterization of the relevant sub-systems. A further allied topic is the nature of nutational movements and whether they are linked with gravitropic movements in some way. In considering how they can best be modelled, two types of nutational movements are proponed: stochastic nutation and circumnutation. Most, if not all, natural movements developed in response to static gravistimulation can be viewed as gravimorphisms. This applies at the levels of cell, organ and organism. However, when a system at any one of these levels experiences dynamic gravistimulation, because of its inherent homeostatic properties, it is induced to regenerate a state similar to that previously held. Thus, gravitropism is a regenerative gravimorphic process at the level of the organ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00008072
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  • 115
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    Effects of growth period, plant age and changes in solution aluminium concentrations on aluminium toxicity in wheat (1994)
    Springer
    Plant and soil 166 (1994), S. 21-30 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; growth period ; phosphorus ; plant age ; root length ; root width ; solution culture ; techniques ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of growth period (time between transplanting and harvesting), plant age at which aluminium (Al) was added to solution, changes in Al concentration, and solution culture techniques (monitoring and adjusting solution Al concentrations thrice weekly or weekly replacement of the solutions) were investigated using a low ionic strength (2.7×10−3 M) solution culture technique. The wheat (Triticum aestivum L.) cultivars Waalt (Al-tolerant) and Warigal (Al-sensitive), or the near isogenic lines bred from these cultivars (RR for the Al-tolerant line and SS for the Al-sensitive line) were grown. In all experiments and treatments, Al additions were required to maintain the nominal concentration. The decline in solution Al concentrations was partially attributed to formation of an Al-hydroxy-phosphate precipitate with an Al:P molar ratio of 2.8 to 4.0. Increasing the growth period from 14 to 28 days increased Al sensitivity in Warigal but not in Waalt. When plants were exposed to Al for the same time, increasing the age of the plants that Al was added to solution decreased sensitivity to Al. Differential Al tolerance between the two lines was evident when solutions were monitored thrice weekly or replaced weekly. However, the Al concentration required to reduce relative yield by a given amount when the solutions were replaced weekly was about twice that when the solutions were monitored. With a constant growth period of 28 days, increasing solution Al concentrations for 3 or more days resulted in decreased yields at harvest. The exact effect depended on the cultivar, plant part (tops or roots), when solution Al concentrations were increased and the duration of the increase. For example, increasing Al concentrations from 5 μM to 20 μM for 10 days reduced yield in the RR line by approximately 50% in the tops and 30% in the roots beyond the effect of 5 M but had no effect in the SS line due to yields already being low at 5 μM. Adding 10 μM Al to solution for 6 days at the beginning of the experiment reduced yield by 25% in the RR line and 50% in the SS line. In contrast, adding 10 μM Al for 6 days in the middle of the growth cycle had no effect on the RR line but reduced yield by approximately 25% in the SS line. These results show that growth period, the age of the plants at which Al is added and the technique used (monitored or weekly replacement) all need to be considered when comparing results from different experiments. These results also show that the Al concentrations in solution need to be regularly monitored in long term experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185477
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  • 116
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    Root growth and nitrate utilization of maize cultivars under field conditions (1994)
    Springer
    Plant and soil 163 (1994), S. 267-277 
    Details
    ISSN: 1573-5036
    Keywords: cultivar ; critical root length density ; field experiment ; nitrate ; N utilization ; root growth ; uptake rate ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a 2-year field study conducted on a high fertilized Gleyic Luvisol in Stuttgart-Hohenheim significant differences among 10 maize cultivars were observed in soil nitrate depletion. The different capability of the cultivars to utilize nitrate particularly from the subsoil was positively correlated with (a) shoot N uptake at maturity, and (b) root length density (Lv) in the subsoil layers at silking. “Critical root length densities” for nitrate uptake were estimated by (a) calculating uptake rates per unit root length (U), (b) subsequent calculation of needed nitrate concentration in soil solution (C1) to sustain calculated U according to the Baldwin formula, and (c) reducing measured Lv and proportionate increase of U until needed concentration equaled measured concentration. Uptake rate generally increased with soil depth. “Critical root length densities” for cultivar Brummi (high measured root length densities and soil nitrate depletion) at 60–90 cm depth ranged from 7 % (generative growth) to 28 % (vegetative growth) of measured Lv Measured root length density of each other cultivar was higher than “critical root length density” for Brummi indicating that the root system of each cultivar examined would have been able to ensure N uptake of Brummi. Positive relationships between root length density and nitrate utilization as indicated by correlation analysis therefore could not be explained by model calculations. This might be due to simplifying assumptions made in the model, which are in contrast to non-ideal uptake conditions in the field, namely irregular distribution of roots and nitrate in the soil, limited root/soil contact, and differences between root zones in uptake activity. It is concluded from the field experiment that growing of cultivars selected for high N uptake-capacity of the shoots combined with “high” root length densities in the subsoil may improve the utilization of a high soil nitrate supply.
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    URL: http://dx.doi.org/10.1007/BF00007976
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    Ultrastructural responses of root caps to the herbicides chlorsulfuron and metsulfuron methyl (1994)
    Springer
    Plant and soil 167 (1994), S. 127-134 
    Details
    ISSN: 1573-5036
    Keywords: herbicides ; chlorsulfuron ; metsulfuron methyl ; root cap ultrastructure ; root growth ; Pisum sativum ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Herbicide residues may affect seedlings during early stages of their development. We studied this possibility by the use of light and electron microscopy after incubation of germinating seeds ofPisum sativum L. andZea mays L. with different concentrations of chlorsulfuron and metsulfuron-methyl. By in vitro experiments, we have shown that both herbicides caused growth reduction of the very young roots, and severe ultrastructural alterations and injuries of the root caps of both species. Chlorsulfuron caused increase of electron-dense material in the vacuoles, cytoplasmic degeneration even in the inner secretory cell layers of the cap, and disruption of the amyloplast envelopes with release of the statolithic starch grains. In the initial cell complex of the root cap, the herbicides caused the formation of large concentric aggregates of the rough ER and wall disformations in the cells adjacent to this complex. Scanning electron microscopic observations revealed a decrease of the slime layer ensheathing the root cap and the subapical root surface. We conclude that even in early stages of seed germination, both herbicides seriously affect the gravity perception centre (consisting of the statocytes), and the secretory tissue of the root caps, thus probably disturbing the processes of gravitropism and the protective slime secretion of the roots.
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    URL: http://dx.doi.org/10.1007/BF01587607
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    C-band polymorphism and structural rearrangements detected in common wheat (Triticum aestivum) (1994)
    Springer
    Euphytica 78 (1994), S. 1-5 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; C-band polymorphism ; structural rearrangements ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Giemsa C-banding allows for the identification of all 21 chromosome pairs of hexaploid wheat. However, variation in banding patterns of individual chromosomes and structural rearrangements exist between different cultivars making chromosome identification more difficult. The paper summarizes the available data on C-band polymorphism and structural rearrangement present in wheat cultivars and germplasms.
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    URL: http://dx.doi.org/10.1007/BF00021392
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    The effect of temperature on seed set and embryo development in reciprocal crosses of wheat and barley (1994)
    Springer
    Euphytica 78 (1994), S. 53-58 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Hordeum vulgare ; barley ; intergeneric hybridization ; influence of temperature ; embryo development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of temperature on seed set and embryo development in reciprocal crosses of barley and wheat was assessed in crosses involving two spring barley varieties (Betzes, Martonvásári 50) and one wheat variety (Chinese Spring). Detached tillers placed in nutrient solution were pollinated in controlled environments at constant day-night temperature regimes (12, 15, 18 and 21° C) with a light intensity of 30,000 lux and a relative humidity of 80%. When barley was used as the female, lower temperatures (12 and 15° C) produced the maximum seed set, whereas for the reciprocal cross, the highest temperature (21° C) produced the best seed set in the Chinese Spring × Betzes combination. Low temperature retarded the embryo development. The highest numbers of hybrid plants were produced at 18° C and 21° C in the barley × wheat cross and in the wheat × barley cross, respectively. Embryos of about 1.5 mm length in the barley × wheat cross, and of about 1.0 mm length in the wheat × barley cross germinated successfully. The smallest embryo giving rise to hybrid plants was 0.57 mm in the barley × wheat cross and 0.51 mm in the wheat × barley cross.
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    URL: http://dx.doi.org/10.1007/BF00021397
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    Effects of nitrogen supply on the acclimation of photosynthesis to elevated CO2 (1994)
    Springer
    Photosynthesis research 39 (1994), S. 389-400 
    Details
    ISSN: 1573-5079
    Keywords: elevated CO2 ; nitrogen supply ; photosynthesis ; acclimation ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A common observation in plants grown in elevated CO2 concentration is that the rate of photosynthesis is lower than expected from the dependence of photosynthesis upon CO2 concentration in single leaves of plants grown at present CO2 concentration. Furthermore, it has been suggested that this apparent down regulation of photosynthesis may be larger in leaves of plants at low nitrogen supply than at higher nitrogen supply. However, the available data are rather limited and contradictory. In this paper, particular attention is drawn to the way in which whole plant growth response to N supply constitutes a variable sink strength for carbohydrate usage and how this may affect photosynthesis. The need for further studies of the acclimation of photosynthesis at elevated CO2 in leaves of plants whose N supply has resulted in well-defined growth rate and sink activity is emphasised, and brief consideration is made of how this might be achieved.
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    URL: http://dx.doi.org/10.1007/BF00014593
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    The influence of ammonia on the growth and photosynthesis of Ruppia drepanensis Tineo from Doñana National Park (SW Spain) (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 219-231 
    Details
    ISSN: 1573-5117
    Keywords: Ruppia drepanensis ; ammonia toxicity ; temperature effects ; photosynthesis ; growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a laboratory experiment, Ruppia drepanensis Tineo seedlings from a brackish marsh in Southern Spain were grown at 20 and 30 °C, at three different nitrogen levels. These levels were obtained by the addition of a slow release fertilizer (23% NH4NO3 by weight) to a sediment mixture of sand and clay (3:1). Several morphometric parameters were recorded during the first five weeks of the experiment, and photosynthesis and respiration were measured after 7 weeks of growth. Results showed a significant reduction of growth and development with increasing nitrogen and temperature levels. Dark respiration increased strongly at high nitrogen levels. At the same time, net photosynthesis at 250 and 500 µE m-2 s-1, Pm, Km and LCP were not affected by either factor. We attribute these phenomena to ammonia toxicity, since relatively high total ammonia (NH3 + NHf4 p+) levels were found in the interstitial water.
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    URL: http://dx.doi.org/10.1007/BF00026713
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    Environmental control of phytoplankton productivity in turbulent turbid systems (1994)
    Springer
    Hydrobiologia 289 (1994), S. 65-72 
    Details
    ISSN: 1573-5117
    Keywords: photosynthesis ; selective environments ; resuspension ; disturbance ; rivers ; shallow lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Factors affecting phytoplankton productivity are analysed in turbid systems, such as shallow lakes and rivers. When resuspension from the sediment or loading from the catchment significantly increases inorganic (non-algal) turbidity and hence light attenuation potentials for high production are not realised. Energy available for phytoplankton growth is strongly regulated by underwater light availability which depends on the critical mixing depth, fluctuating light intensities and algal circulation patterns. Higher production rates in shallow waters are often compensated by greater algal respiration due to higher water temperatures when compared to deeper lakes. Total daily integral production of turbulent, turbid environments can be predicted from a combination of easily measured variables such as maximum photosynthetic rates, algal biomass, surface irradiance and some measure of underwater light attenuation.
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    URL: http://dx.doi.org/10.1007/BF00007409
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    Light differentially regulates lateral and longitudinal auxin transport in the mesocotyl of etiolated maize seedlings (1994)
    Springer
    Plant growth regulation 14 (1994), S. 167-171 
    Details
    ISSN: 1573-5087
    Keywords: auxin-transport ; indoleacetic acid ; maize ; photoinhibition ; transport ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The uptake of IAA into excised mesocotyls of non-irradiated maize seedlings was linear up to a concentration of about 4×M and in this range there was a tight coupling between the IAA in the stele and the cortex. Prior irradiation with white light of intact seedlings unbalanced this coupling. Lateral and longitudinal transport were affected differently. In the stele, the effect of prior irradiation on longitudinal transport was multiphasic, with an initial stimulatory effect followed by a negative effect at longer prior irradiation times. The lateral transport from the stele to the cortex showed no stimulatory effect and appeared to be inhibited within at least 15 min. The effect of the prior irradiation on longitudinal transport in the stele appeared to be a high intensity effect. In contrast, the effect of the prior irradiation on the lateral transport from the stele to the cortex was saturated at much lower intensities. The data suggest that the light induced change in the lateral transport of IAA between the two tissues may be due to changes either in the number of open lateral transport channels/carriers or in the conductivity of these channels/carriers.
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    URL: http://dx.doi.org/10.1007/BF00025219
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    Effects of homobrassinolide application on plant metabolism and grain yield under irrigated and moisture-stress conditions of two wheat varieties (1994)
    Springer
    Plant growth regulation 14 (1994), S. 173-181 
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    ISSN: 1573-5087
    Keywords: homobrassinolide ; irrigated ; membrane stability ; moisture-stress ; nitrate reductase activity ; photosynthesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Homobrassinolide (BR) was applied either as a seed treatment or foliar spray to two contrasting wheat varieties, viz. C306 (drought tolerant) and HD2329 (drought susceptible), to examine its effects on plant metabolism and grain yield under irrigated and moisture-stress/rainfed conditions. BR application resulted in increased relative water content, nitrate reductase activity, chlorophyll content and photosynthesis under both conditions. BR application also improved membrane stability (lower injury). These beneficial effects resulted in higher leaf area, biomass production, grain yield and yield related parameters in the treated plants. All the treatments were significantly better than the untreated control. Generally, 0.05 ppm either as a seed treatment or foliar spray was more effective than the 0.01 ppm treatment. The drought-tolerant genotype C306 showed more response to BR application under moisture-stress/rainfed condition than HD 2329. Increased water uptake, membrane stability and higher carbon dioxide and nitrogen assimilation rates under stress seemed to be related to homobrassinolide-induced drought tolerance.
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    URL: http://dx.doi.org/10.1007/BF00025220
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    Development and ecological importance of phytoplankton in a large lowland river (River Meuse, Belgium) (1994)
    Springer
    Hydrobiologia 289 (1994), S. 139-155 
    Details
    ISSN: 1573-5117
    Keywords: potamoplankton ; regulated river ; transport of carbon and nutrients ; photosynthesis ; respiration ; dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ecological importance of the River Meuse phytoplankton with regard to carbon and nutrient transport has been examined in two reaches of the Belgian course of the river. Field measurements of total particulate organic carbon (POC), particulate organic nitrogen (PON) and particulate phosphorus (PP) show that the large autochtonous production of organic matter strongly affects the carbon and nutrient budget of the aquatic system. During the growing season, phytoplankton accounts for nearly 60% of the POC and dominates the PON. Calculations of the carbon and oxygen budget in the upper reach of the Belgian Meuse demonstrates that the ecosystem is autotrophic, i.e. that autochtonous FPOM (fine particulate organic matter) production is the major carbon input. This suggests that in large lowland rivers, primary production (P) may exceed community respiration (R), i.e. P:R〉1, whereas they are assumed to be heterotrophic (P:R〈1) in the River Continuum concept. The question of maintenance of phytoplankton in turbid mixed water columns is also addressed, and the case of the River Meuse is treated on the basis of studies of photosynthesis and respiration (ETS measurements). The results suggest that the potamoplankton may show some low-light acclimation, through an increase of chlorophyll a relative to biomass, when it comes to deep downstream reaches, and that algal respiration rate may be reduced. A simulation of the longitudinal development of the algal biomass shows the different phases of algal growth and decline along the river and brings support to the ‘importation hypothesis’ for explaining maintenance of potamoplankton in the downstream reaches.
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    URL: http://dx.doi.org/10.1007/BF00007415
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    An active Mehler-peroxidase reaction sequence can prevent cyclic PS I electron transport in the presence of dioxygen in intact spinach chloroplasts (1994)
    Springer
    Photosynthesis research 41 (1994), S. 429-437 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; ascorbate peroxidase ; Mehler reaction ; cyclic PS I ; chlorophyll fluorescence ; 9-aminoacridine fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous measurements of 9-aminoacridine (9-AA) fluorescence quenching, O2-uptake and chlorophyll fluorescence of intact spinach chloroplasts were carried out to assess the relationship between the transthylakoidal ΔpH and linear electron flux passing through Photosystem II. Three different types of O2-dependent electron flow were investigated: (1) Catalysed by methyl viologen; (2) in the absence of a catalyst and presence of an active ascorbate peroxidase (Mehler-peroxidase reaction); (3) in the absence of a catalyst and with the ascorbate peroxidase being inhibited by KCN (Mehler reaction). The aim of this study was to assess the relative contribution of ΔpH-formation which is not associated with electron flow through Photosystem II and, which should reflect Photosystem I cyclic flow under the different conditions. The relationship between the extent of 9-AA fluorescence quenching and O2-uptake rate was found to be almost linear when methyl viologen was present. In the absence of methyl viologen (Mehler reaction) an increase of 9-AA fluorescence quenching to a value of 20% at low light intensities was associated with considerably less O2-uptake than in the presence of methyl viologen, indicating the involvement of cyclic flow. These findings are in agreement with a preceding study of Kobayashi and Heber (1994). However, when no KCN was added, such that the complete Mehler-peroxidase reaction sequence was operative, the relationship between 9-AA fluorescence quenching and the flux through PS II, as measured via the chlorophyll fluorescence parameter ΔF/Fm′ × PAR, was identical to that observed in the presence of methyl viologen. Under the assumption that methyl viologen prevents cyclic flow, it is concluded that there is no significant contribution of cyclic electron flow to ΔpH-generation in intact spinach chloroplasts.
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    URL: http://dx.doi.org/10.1007/BF02183045
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    Ethylene as promoter of wheat grain maturation and ear senescence (1994)
    Springer
    Plant growth regulation 15 (1994), S. 107-112 
    Details
    ISSN: 1573-5087
    Keywords: aminoethoxyvinylglycine ; ear senescence ; ethephon ; ethylene ; grain maturation ; silver thiosulfate ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This work was aimed at testing the involvement of ethylene in the maturation of grain and senescence of the foliar structures of the wheat inflorescence. Whole wheat ears emitted ethylene to the atmosphere. From pre-anthesis, ethylene emission progressively increased from 0.76 nl g−1FW h−1 to a peak 1.53 nl g−1FW h−1 at the hard dough stage of the grains, to fall to a minimum of 0.10 nl g−1FW h−1 at the dormant seed stage. Ethephon increased the ethylene release, hastened the process of grain maturation and senescence of the ears. Aminoethoxyvinylglycine and silver thiosulfate produced the opposite effects. It is concluded that ethylene plays a role in grain maturation and in the senescence of the green bracts of the inflorescence.
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    URL: http://dx.doi.org/10.1007/BF00024098
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    Long-chain free fatty acids: Semiochemicals for host location by western corn rootworm larvae (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 3335-3344 
    Details
    ISSN: 1573-1561
    Keywords: Diabrotica virgifera virgifera ; fatty acids ; linoleic acid ; oleic acid ; stearic acid ; semiochemical ; attractants ; western corn rootworm ; host location ; Coleoptera ; Chrysomelidae ; Zea mays ; kairomone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A bioassay-driven sequential fractionation scheme was used to isolate fractions of a crude dichloromethane maize seedling extract behaviorally active to larvae of the western corn rootworm,Diabrotica virgifera virgifera LeConte. (Z,Z)-9,12-Octadecadienoic (linoleic) acid, (Z)-9-octadecenoic (oleic) acid, and octadecanoic (stearic) acid were identified from a purified fraction of maize extract that was attractive to western corn rootworm larvae in choice tests with equal levels of carbon dioxide on both sides of the choice. When synthetic linoleic, oleic, and stearic acids were tested together in the amounts and proportions found in the attractive fraction (1000, 800, and 300 ng of linoleic, oleic, and stearic acids, respectively), significantly more western corn rootworm larvae were found on the side with synthetic free fatty acids plus carbon dioxide than on the side with carbon dioxide alone. Results of the choice-test bioassays were not significantly different when the synthetic blend of free fatty acids was substituted for the purified maize fraction. Neither the purified extract nor the synthetic blend was behaviorally active in preliminary single-choice experiments without carbon dioxide. Linoleic, oleic, and stearic acids were also tested individually in the choice test bioassay with carbon dioxide on both sides of the choice to determine a dose-response curve. Linoleic and oleic acid each had one dose that was significantly attractive in conjunction with carbon dioxide on both sides of the choice, but stearic acid was not active in the doses tested.
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    URL: http://dx.doi.org/10.1007/BF02033730
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    Effects of two sesquiterpene lactones isolated fromArtemisia annua on physiology ofLemna minor (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 969-978 
    Details
    ISSN: 1573-1561
    Keywords: Artemisinin ; arteannuic acid ; photosynthesis ; respiration ; chlorophyll ; Lemna minor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effects of artemisinin and arteannuic acid extracted fromArtemisia annua on the physiology ofLemna minor were evaluated. Changes in frond production, growth, dry weight, and chlorophyll content ofL. minor were determined. Photosynthesis and respiration were evaluated with a differential respirometer. Artemisinin (5 µM) inhibitedL. minor frond production and dry weight 82 and 83%, relative to methanol controls. Chlorophyll content was reduced 44% by artemisinin (2.5 µM). Arteannuic acid (10 µM) was less active, inhibiting frond production 61% and reducing chlorophyll content 66% at 5 µM. Artemisinin (1 µM) reducedL. minor photosynthesis 30% and 2.5 µM reduced respiration 39%. Arteannuic acid had no significant effect on photosynthesis or respiration at the levels tested.
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    Effectiveness of two partially acidulated rock phosphates, coastal superphosphate and Ecophos, compared with North Carolina reactive rock phosphate and superphosphate (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 29-45 
    Details
    ISSN: 1573-0867
    Keywords: coastal superphosphate ; Ecophos ; North Carolina rock phosphate ; ordinary (single) superphosphate ; partially acidulated rock phosphate (PARP) ; reactive rock phosphate ; relative effectiveness ; residual value ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effectiveness of coastal superphosphate, a partially acidulated rock phosphate (PARP) made from apatite, and Ecophos, a PARP made from calcium iron aluminium (crandallite millisite) rock phosphate, was compared in pot experiments with the effectiveness of ordinary superphosphate (OSP) and North Carolina reactive apatite rock phosphate (NCRP). There were three experiments using different lateritic soils collected in Western Australia. Fertilizer effectiveness was measured using yield of dried wheat (Triticum aestivum) tops grown for 28 days. Three successive crops were grown. The phosphorous (P) fertilizers were applied and mixed with the soils before sowing the first crop. In addition, OSP was added to extra pots before sowing crops 2 and 3 in order to measure the effectiveness of the original P fertilizers relative to freshly-applied OSP for these crops. As measured using plant yield, coastal superphosphate was the most effective P fertilizer for three crops on an acidic peaty sand (pH water 5.0). Relative to freshly-applied OSP, it was 154% as effective for crop 1, 75% as effective for crop 2, and 36% as effective for crop 3. Corresponding values for Ecophos were 44, 29 and 19%, and for NCRP, 77, 67 and 29%, with the original OSP treatment being 61 and 56% as effective for crops 2 and 3. For three crops on a lateritic gravel loam (pH 6.5), both coastal superphosphate and OSP were the most effective fertilizers, and were equally effective for crop 1, and relative to freshly-applied OSP, were about 31% as effective for crop 2, and 16 and 21 % as effective for crop 3. Corresponding values for Ecophos were 47,15 and 11%, and NCRP, 33,15 and 5%. For two crops in a loamy sand (pH 5.4), OSP was the most effective fertilizer, and, relative to fresh OSP, it was 36% as effective for crop 2. Relative to fresh OSP, the effectiveness for crops 1 and 2 of coastal superphosphate was 57 and 18%, for Ecophos 71 and 27%, and for NCRP 50 and 36%.
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    Photosynthetic electron transport and anaerobic metabolism in purple non-sulfur phototrophic bacteria (1994)
    Springer
    Antonie van Leeuwenhoek 66 (1994), S. 151-164 
    Details
    ISSN: 1572-9699
    Keywords: purple non-sulfur bacteria ; Rhodobacter ; photosynthesis ; CO2 fixation ; anaerobic respiration ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Purple non-sulfur phototrophic bacteria, exemplifed byRhodobacter capsulatus andRhodobacter sphaeroides, exhibit a remarkable versatility in their anaerobic metabolism. In these bacteria the photosynthetic apparatus, enzymes involved in CO2 fixation and pathways of anaerobic respiration are all induced upon a reduction in oxygen tension. Recently, there have been significant advances in the understanding of molecular properties of the photosynthetic apparatus and the control of the expression of genes involved in photosynthesis and CO2 fixation. In addition, anaerobic respiratory pathways have been characterised and their interaction with photosynthetic electron transport has been described. This review will survey these advances and will discuss the ways in which photosynthetic electron transport and oxidation-reduction processes are integrated during photoautotrophic and photoheterotrophic growth.
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    Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 311-329 
    Details
    ISSN: 1572-9699
    Keywords: photosynthesis ; chlorophyll ; bacteriochlorophyll ; reaction center ; electron transfer ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.
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    URL: http://dx.doi.org/10.1007/BF00872216
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    Evaluation for resistance to Pyrenophora tritici-repentis in Aegilops tauschii Coss. and synthetic hexaploid wheat amphiploids (1994)
    Springer
    Genetic resources and crop evolution 41 (1994), S. 27-34 
    Details
    ISSN: 1573-5109
    Keywords: Aegilops tauschii ; synthetic wheats ; tan spot resistance ; Pyrenophora tritici-repentis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A total of 59 diploid Aegilops tauschii Coss. (syn. Aegilops sguarrosa auct. non L.) and 39 synthetic hexaploid wheat accessions were evaluated for reaction to Pyrenophora tritici-repentis (Died.) Drechs. in a controlled environment, and classified using a disease rating system based on lesion type. 27 Ae. tauschii and 20 synthetic wheats were found to be resistant to tan spot disease. The overall mean disease ratings of Ae. tauschii and the synthetic wheat lines scored on a scale of 1 (resistant) to 5 (susceptible) were 1.80 and 2.38, respectively. Synthetic wheats generally showed a decrease in resistance, although several lines of synthetic wheat expressed a higher resistance than the diploid parents. Five synthetic wheat lines exhibited higher resistance than the standard resistant common wheat cultivar ‘Red Chief’.
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    Powdery mildew resistance in Aegilops tauschii coss. and synthetic hexaploid wheats (1994)
    Springer
    Genetic resources and crop evolution 41 (1994), S. 151-158 
    Details
    ISSN: 1573-5109
    Keywords: Triticum aestivum ; Aegilops tauschii (syn. Ae. squarrosa) ; Erysiphe graminis f. sp. tritici resistance genes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A collection of 400 Ae. tauschii (syn. Ae. squarrosa) Coss. accessions were screened for powdery mildew resistance based on the response patterns of 13 wheat cultivars/lines possessing major resistance genes to nine differential mildew isolates. 106 accessions showed complete resistance to all isolates, and 174 accessions revealed isolate-specific resistance, among which were 40 accessions exhibiting an identical response pattern as wheat cultivar ‘Ulka/*8Cc’ which is known to possess resistance gene Pm2. Expression of both complete and isolate-specific resistance from Ae. tauschii was observed in some synthetic hexaploid wheats derived from four mildew susceptible T. durum Desf. parents, each crossed with five to 38 resistant diploid Ae. tauschii accessions. Synthetic amphiploids involving different combinations of T. durum and Ae. tauschii generally showed a decrease in resistance compared with that expressed by the Ae. tauschii parental lines.
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    URL: http://dx.doi.org/10.1007/BF00051631
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    Relationships among American and Spanish populations of maize (1994)
    Springer
    Euphytica 79 (1994), S. 149-161 
    Details
    ISSN: 1573-5060
    Keywords: maize ; germplasm ; cluster analysis ; landraces ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two experiments were carried out with two objectives. First, to establish the phenetic relationships among the maize (Zea mays L.) landraces from Galicia (Northwestern Spain) maintained at the Misión Biológica de Galicia. Second, to assess the resemblance between a collection of Spanish populations (including the landraces from Galicia) and a set of US Corn Belt varieties. For the first objective 73 varieties from Galicia, along with 9 hybrid checks, were grown in 9×9 simple lattices at two locations for two years. For the second objective 131 populations from the US Corn Belt and Spain, along with 9 hybrid checks, were grown for three years in unreplicated experiments. Cluster analyses were carried out with the first principal components that accounted for a significant amount of the total variation. Four groups were found among the landraces from Galicia. The populations from Spain and America were classified as belonging to nine main groups. The replicated experiment was more accurate than the unreplicated one. However, it is concluded that an unreplicated test grown in several environments is accurate enough to detect the main groups, although some inaccuracies should be expected.
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    URL: http://dx.doi.org/10.1007/BF00023586
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    Genetic variation for resistance to low-temperature photoinhibition of photosynthesis in maize (Zea mays L.) (1994)
    Springer
    Euphytica 80 (1994), S. 85-93 
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    ISSN: 1573-5060
    Keywords: maize ; Zea mays ; photoinhibition ; photosynthesis ; low-temperature adaptation ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sixty-seven inbred lines of maize were evaluated for resistance to low-temperature photoinhibition of photosynthesis, using a pulse-modulated chlorophyll fluorescence technique. The evaluation procedure was based on leaf discs, which were exposed to a high irradiance (1000 µmol/m2/s) at 7°C. The efficiency of open PSII reaction centres as a reflection of overall photosynthesis was measured before and after a photoinhibition-inducing treatment. Exposure of leaf discs to photoinhibitory condition for 2, 4, and 8 hours resulted in an efficiency reduction of 30, 53 and 83%, respectively. Testing of inbred lines showed large differences for photoinhibition susceptibility. The difference in photosynthetic efficiency between the most extreme lines after a treatment of eight hours was 39%. Resistance to photoinhibition was shown to be relevant under cool field conditions. It proved to be a trait strongly amenable to selection.
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    URL: http://dx.doi.org/10.1007/BF00039302
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    Genetics of leaf rust resistance in 13 accessions of the Watkins wheat collection (1994)
    Springer
    Euphytica 80 (1994), S. 151-155 
    Details
    ISSN: 1573-5060
    Keywords: leaf rust resistance ; Puccinia recondita ; Triticum aestivum ; wheat ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The inheritance of leaf rust resistance was studied in 13 accessions of the A.E. Watkins wheat collection. Eight of the accessions (V409, V624, V628, V712, V731, V734, V745, and V855) were shown to have gene Lr33 and four of these (V409, V624, V628, and V731) also have LrW. Accessions V624 and V338 have LrB, and V377 and V488 have Lr11. V46 has an unidentified gene that gives an intermediate level of resistance. V860 has a partially dominant gene that gives a fleck reaction to avirulent isolates in the seedling stage. This gene is different from LrW and may be previously unidentified. It has been assigned the temporary gene symbol LrW2. In addition to seedling-effective genes, V46, V731, and V745 may have Lr34 and V745 may have Lr13. The adult-plant resistance in V488, V624, and V860 could not be identified. Seedling gene LrW2 and some of the adult-plant resistance should be useful sources of resistance.
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    URL: http://dx.doi.org/10.1007/BF00039311
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    Evolution of virulence patterns in yellow rust races and its implications for Ereeding for resistance in wheat in Kenya (1994)
    Springer
    Euphytica 80 (1994), S. 165-170 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia striiformis ; yellow rust ; durable resistance ; race-specific resistance ; residual resistance ; races ; virulence, Kenya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Virulence patterns of yellow rust isolates collected in Kenya between 1986–1989 were compared with earlier results. The number of virulence factors per race and the range in virulence factors both increased considerably. Before 1976 races carried on average 4.5 to 5.0 virulence factors, whereas the races after 1986 had a mean of 6.5 virulence factors. The range in the number of virulence factors increased from some seven to eight in the first period to 12 in the second out of the 17 evaluated. In the period 1986–1989 another three virulence factors (2, 9 and A) were assessed. All three occurred at a high frequency. Virulence neutralizing the resistance genes Yr2, Yr2+, Yr6, Yr6+, Yr7, Yr7+, Yr8, Yr9, Yr9+ and those in the cultivars Anza (A), Strubes Dickkopf (SD) and Suwon92/Omar (SU) occurred at a high frequency, while virulence for Yr3V, Yr4+, Yr5, CV and SP (resistance in Carstens V and Spaldings Prolific resp.) were not found. The remaining three virulence factors for Yr1, 10 and 3N were rare. In the past ten years the resistance of most released cultivars became ineffective in less than six years. They were shown to carry race-specific major resistance genes such as Yr7+, Yr9+, SD and A. However, in the field, the resistance of the cultivars was not completely neutralized. A residual resistance, ranging from moderate to fairly high, was observed in all cultivars in which the major gene resistances were neutralized by corresponding virulence genes. Other wheat cultivars such as Africa Mayo, Kenya Kudu, Enkoy, Kenya Leopard, Bounty, Frontatch, Bonny and Kenya Plume appeared to keep their resistance over a condiserable period of time. They are considered to be durably resistant to the Kenyan yellow rust populations. This form of resistance, together with the residual resistance, can be recommended for use in breeding programmes.
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    URL: http://dx.doi.org/10.1007/BF00039647
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    Interaction of analogues of substrate with NADP-malic enzyme from maize leaves (1994)
    Springer
    Photosynthesis research 39 (1994), S. 67-73 
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    ISSN: 1573-5079
    Keywords: Zea mays ; C4-photosynthesis ; decarboxylation ; NADP-ME type ; l-malate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of structural analogues of l-malate was studied on NADP-malic enzyme purified from Zea mays L. leaves. Among the compounds tested, the organic acids behaved as more potent inhibitors at pH 7.0 than at pH 8.0, suggesting that the dimeric form was more susceptible to the inhibition than the tetrameric form of the enzyme. Oxalate, ketomalonate, hydroxymalonate, malonate, oxaloacetate, tartrate, α-hydroxybutyrate, α-ketobutyrate, α-ketoglutarate and α-hydroxyglutarate exhibited linear competitive inhibition with respect to the substrate l-malate at pH 8.0. On the other hand, glyoxylate and glycolate turned out to be non-competitive inhibitors, while glycolaldehyde, succinate, fumarate, maleate and β- and γ-hydroxybutyrate had no effect on the enzyme activity, at the concentrations assayed. These results suggest that the extent of inhibition was dependent on the size of the analogues and that the presence of an 1-carboxyl group along with a 2-hydroxyl or 2-keto group was important for binding of the substrate analogue to the enzyme.
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    URL: http://dx.doi.org/10.1007/BF00027144
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    Optimal acclimation of the C3 photosynthetic system under enhanced CO2 (1994)
    Springer
    Photosynthesis research 39 (1994), S. 401-412 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; elevated CO2 ; source-sink interactions ; Rubisco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A range of studies of C3 plants have shown that there is a change in both the carbon flux and the pattern of nitrogen allocation when plants are grown under enhanced CO2. This paper examines evidence that allocation of nitrogen both to and within the photosynthetic system is optimised with respect to the carbon flux. A model is developed which predicts the optimal relative allocation of nitrogen to key enzymes of the photosynthetic system as a function of CO2 concentration. It is shown that evidence from flux control analysis is broadly consistent with this model, although at high nitrogen and under certain conditions at low nitrogen experimental data are not consistent with the model. Acclimation to enhanced CO2 is also assessed in terms of resource allocation between photosynthate sources and sinks. A means of assessing the optimisation of this source-sink allocation is proposed, and several studies are examined within this framework. It is concluded that C3 plants probably possess the genetic feedback mechanisms required to efficiently ‘smooth out” any imbalance within the photosynthetic system caused by a rise in atmospheric CO2.
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    URL: http://dx.doi.org/10.1007/BF00014594
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    Biochemical and molecular basis for impairment of photosynthetic potential (1994)
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    Photosynthesis research 39 (1994), S. 453-462 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; Rubisco ; ozone ; oxidative stress ; rbcS mRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ozone induces reductions in net photosynthesis in a large number of plant species. A primary mechanism by which photosynthesis is reduced is through impact on carbon dioxide fixation. Ozone induces loss in Rubisco activity associated with loss in concentration of the protein. Evidence is presented that ozone may induce oxidative modification of Rubisco leading to subsequent proteolysis. In addition, plants exposed to ozone sustain reduction in rbcS, the mRNA for the small subunit of Rubisco. This loss in rbcS mRNA may lead to a reduced potential for synthesis of the protein. The regulation of O3-induced loss of Rubisco, and implications of the decline in this protein in relation to accelerated senescence are discussed.
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    URL: http://dx.doi.org/10.1007/BF00014598
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    Reminiscence about‘Chloropseudomonas ethylicum’ and the FMO-protein (1994)
    Springer
    Photosynthesis research 41 (1994), S. 3-5 
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    ISSN: 1573-5079
    Keywords: bacteriochlorophylla-protein ; green sulfur bacteria ; Prosthecochloris aestuarii ; Chlorobium limicola ; photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In 1961 the green sulfur bacterium-containing mixed culture known as‘Chloropseudomonas ethylicum’ was brought to Brookhaven National Laboratory (USA) from Moscow State University (USSR). The water-soluble bacteriochlorophylla-protein (FMO-protein) was extracted, purified and characterized by absorption and circular dichroism spectroscopy, by X-ray crystallography and by primary structure determination.
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    URL: http://dx.doi.org/10.1007/BF02184138
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    Rates of vectorial proton transport supported by cyclic electron flow during oxygen reduction by illuminated intact chloroplasts (1994)
    Springer
    Photosynthesis research 41 (1994), S. 419-428 
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    ISSN: 1573-5079
    Keywords: 9-aminoacridine fluorescence ; cyclic electron transport ; Mehler reaction ; photosynthesis ; photosystems ; transthylakoid proton gradient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The light-dependent quenching of 9-aminoacridine fluorescence was used to monitor the state of the transthylakoid proton gradient in illuminated intact chloroplasts in the presence or absence of external electron acceptors. The absence of appreciable light-dependent fluorescence quenching under anaerobic conditions indicated inhibition of coupled electron transport in the absence of external electron acceptors. Oxygen relieved this inhibition. However, when DCMU inhibited excessive reduction of the plastoquinone pool in the absence of oxygen, coupled cyclic electron transport supported the formation of a transthylakoid proton gradient even under anaerobiosis. This proton gradient collapsed in the presence of oxygen. Under aerobic conditions, and when KCN inhibited ribulose bisphosphate carboxylase and ascorbate peroxidase, fluorescence quenching indicated the formation of a transthylakoid proton gradient which was larger with oxygen in the Mehler reaction as electron acceptor than with methylviologen at similar rates of linear electron transport. Apparently, cyclic electron transport occured simultaneously with linear electron transport, when oxygen was available as electron acceptor, but not when methylviologen accepted electrons from Photosystem I. The ratio of cyclic to linear electron transport could be increased by low concentrations of DCMU. This shows that even under aerobic conditions cyclic electron transport is limited in isolated intact chloroplasts by excessive reduction of electron carriers. In fact, P700 in the reaction center of Photosystem I remained reduced in illuminated isolated chloroplasts under conditions which resulted in extensive oxidation of P700 in leaves. This shows that regulation of Photosystem II activity is less effective in isolated chloroplasts than in leaves. Assuming that a Q-cycle supports a H+/e ratio of 3 during slow linear electron transport, vectorial proton transport coupled to Photosystem I-dependent cyclic electron flow could be calculated. The highest calculated rate of Photosystem I-dependent proton transport, which was not yet light-saturated, was 330 μmol protons (mg chlorophyll h)−1 in intact chloroplasts. If H+/e is not three but two proton transfer is not 330 but 220 μmol (mg Chl H)−1. Differences in the regulation of cyclic electron transport in isolated chloroplasts and in leaves are discussed.
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    URL: http://dx.doi.org/10.1007/BF02183044
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    Pigment orientation changes accompanying the light state transition in Synechococcus sp. PCC 6301 (1994)
    Springer
    Photosynthesis research 40 (1994), S. 35-44 
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    ISSN: 1573-5079
    Keywords: allophycocyanin ; chlorophyll a ; linear dichroism ; phycobilisome ; photosynthesis ; state transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Low temperature (77 K) linear dichroism spectroscopy was used to characterize pigment orientation changes accompanying the light state transition in the cyanobacterium, Synechococcus sp. PCC 6301 and those accompanying chromatic acclimation in Porphyridium cruentum in samples stabilized by glutaraldehyde fixation. In light state 2 compared to light state 1 intact cells of Synechococcus showed an increased alignment of allophycocyanin parallel to the cells' long axis whereas the phycobilisomethylakoid membrane fragments exhibited an increased allophycocyanin alignment parallel to the membrane plane. The phycobilisome-thylakoid membrane fragments showed less alignment of a short wave-length chlorophyll a (Chl a) Qy transition dipole parallel to the membrane plane in state 2 relative to state 1. To aid identification of the observed Chl a orientation changes in Synechococcus, linear dichroism spectra were obtained from phycobilisome-thylakoid membrane fragments isolated from red light-grown (increased number of PS II centres) and green light-grown (increased number of PS I centres) cells of the red alga Porphyridium cruentum. An increased contribution of short wavelength Chl a Qy transition dipoles parallel to the long axis of the membrane plane was directly correlated with increased levels of PS II centres in red light-grown P. cruentum. Our results indicate that the transition to state 2 in cyanobacteria is accompanied by an increase in the orientation of allophycocyanin and a decrease in the orientation of Chl a associated with PS II with respect to the thylakoid membrane plane.
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    URL: http://dx.doi.org/10.1007/BF00019043
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    Photoinhibition of photosynthesis in chilled potato leaves is not correlated with a loss of Photosystem-II activity (1994)
    Springer
    Photosynthesis research 40 (1994), S. 75-92 
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    ISSN: 1573-5079
    Keywords: chilling temperature ; oxygen toxicity ; photoinhibition ; photosynthesis ; photosystems ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When 23 °C-grown potato leaves (Solanum tuberosum L.) were irradiated at 23 °C with a strong white light, photosynthetic electron transport and Photosystem-II (PS II) activity were inhibited in parallel. When the light treatment was given at a low temperature of 3 °C, the photoinhibition of photosynthesis was considerably enhanced, as expected. Surprisingly, no such stimulation of photoinhibition was observed with respect to the PS II function. A detailed functional analysis of the photosynthetic apparatus, using in-vivo fluorescence, absorbance, oxygen and photoacoustic measurements, and artificial electron donors/acceptors, showed a pronounced alteration of PS I activity during light stress at low temperature. More precisely, it was observed that both the pool of photooxidizeable reaction center pigment (P700) of PS I and the efficiency of PS I to oxidize P700 were dramatically reduced. Loss of P700 activity was shown to be essentially dependent on atmospheric O2 and to require a continued flow of electrons from PS II, suggesting the involvement of the superoxide anion radical which is produced by the interaction of O2 and the photosynthetic electron-transfer chain through the Mehler reaction. Mass spectrometric measurements of O2 exchange by potato leaves under strong illumination did not reveal, however, any stimulation of the Mehler reaction at low temperature, thus leading to the conclusion that O2 toxicity mainly resulted from a chilling-induced inhibition of the scavenging system for O2-radicals. Support for this interpretation was provided by the light response of potato leaves infiltrated with an inhibitor (diethyldithiocarbamate) of the chloroplastic Cu-Zn superoxide dismutase. It was indeed possible to simulate the differential inhibition of the PS II photochemical activity and the linear electron transport observed during light stress at low temperature by illuminating at 23 °C diethyldithiocarbamate-poisoned leaves. The experimental data presented here suggests that (i) the previously reported resistance of PS I to photoinhibition damage in-vivo is not an intrinsic property of PS I but results from efficient protective systems against O2 toxicity, (ii) PS I is photoinhibited in chilled potato leaf due to the inactivation of this PS I defence system and (iii) PS I is more sensitive to superoxide anion radicals than PS II.
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    Sixty years in algal physiology and photosynthesis (1994)
    Springer
    Photosynthesis research 40 (1994), S. 207-221 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; unicellular algae ; ion effects ; manganese ; blue light ; synchronized growth ; algal mass cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This personal perspective records research experiences in chemistry and biology at four German universities, two before and two after World War II. The research themes came from cytophysiology of green unicellular algae, in particular their photosynthesis. The function of inorganic ions in photosynthesis and dark respiration was investigated at different degrees of specific mineral stress (deficiencies), and the kinetics of recovery followed after the addition of the missing element. Two types of recovery of photosynthesis were observed: indirect restitution via growth processes and immediate normalisation. From the latter case (K+, phosphate, Mn++) the effect of manganese was emphasized as its role in photosynthetic O2 evolution became established during our research. Other themes of our group, with some bearing on photosynthesis were: synchronization of cell growth by light-dark change and effects of blue (vs. red) light on the composition of green cells. Some experiences in connection with algal mass cultures are included. Discussion of several editorial projects shows how photosynthesis, as an orginally separated field of plant biochemistry and biophysics, became included into general cell physiology and even ecophysiology of green plants. The paper contains an appreciation of the authors' main mentor Kurt Noack (1888–1963) and of Ernst Georg Pringsheim (1881–1970), founder of experimental phycology.
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    Gene nomenclature recommendations for green photosynthetic bacteria and heliobacteria (1994)
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    Photosynthesis research 41 (1994), S. 27-28 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; reaction center ; green bacteria ; heliobacteria ; gene ; chlorosome ; cytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recommendations are given for naming of genes coding for reaction center, antenna and electron transport proteins in green photosynthetic bacteria and heliobacteria
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    URL: http://dx.doi.org/10.1007/BF02184142
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    Redox effects on the bacteriochlorophyll α-containing Fenna-Matthews-Olson protein fromChlorobium tepidum (1994)
    Springer
    Photosynthesis research 41 (1994), S. 89-96 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; Chlorobium tepidum ; antenna ; bacteriochlorophylla protein ; energy transfer ; chlorosome ; green bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The BChla-containing Fenna-Matthews-Olson (FMO) protein from the green sulfur bacteriumChlorobium tepidum was purified and characterized. Fluorescence spectra indicate that efficient excited state quenching occurs at neutral or oxidizing redox potentials. The major fluorescence lifetime at room temperature is approximately 60 ps in samples that are in neutral or oxidizing conditions, and approximately 2 ns in samples where the strong reductant sodium dithionite has been added. A similar change is observed in pump-probe picosecond absorbance difference experiments, where the long life time component increases after dithionite addition. A 16 Gauss wide EPR signal with g factor =2.005 is observed in samples without dithionite. This signal largely disappears upon addition of dithionite. Dithionite induces large reversibile changes in the 77 K absorbance spectra of the purified FMO protein and in whole cells. These results indicate that the FMO protein contains redox active groups, which may be involved in the regulation of energy transfer. Room temperature circular dichroism and low temperature absorption spectra show that dithionite also induces conformational or structural changes of the FMO protein complex.
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    Responses to drought and flooding in tropical forage grasses (1994)
    Springer
    Plant and soil 164 (1994), S. 97-105 
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    ISSN: 1573-5036
    Keywords: alcohol dehydrogenase ; drought ; flooding ; photosynthesis ; tropical grasses ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Long dry seasons or permanent flooding, typical of tropical savannas, severely limit the growth of pasture plants. This study compares the responses of water relations, carbon assimilation and alcohol dehydrogenase (ADH) activity to drought and flooding in four perennial C4 grasses: the tufted or caespitose Hyparrhenia rufa and Andropogon gayanus (CIAT 621) and the stoloniferous Brachiaria mutica and Echinochloa polystachya. Plants of the four species were subjected to medium term flooding (20–25 days) and moderate drought in a greenhouse. Leaf water potential (Ψ), stomatal conductance (Gs) and photosynthesis rate (Pn) were measured throughout the experiment and ADH activity was measured in flooded and control plants. Moderate drought produced similar effects in all grasses reducing Gs which caused reduced Pn. Net photosynthesis compensation point was reached at the lowest Ψ in A. gayanus which was considered as the most drought tolerant. The responses to flooding varied across species. Andropogon gayanus and H. rufa showed early stomatal closure without concurrent decrease in Ψ and leaf turgor. This low Gs was responsible of reduced Pn and growth rate. There was a slight increase of Gs in the middle of the flooding period and both grasses recovered pre-stress Gs and Pn after drainage. ADH activity increased markedly only in A. gayanus under flooding suggesting that this grass was the most flood-sensitive. Stomatal aperture, Pn and ADH activity in B. mutica and E. polystachya were not affected by flooding. The higher flood-tolerance in these grasses might be attributed to enhanced oxygen diffusion to the roots through the hollow stolons, development of advantitious rootlets and large aerenchyma in the roots which compensate for the reduction of soil oxygen and permit the maintenance of root activity.
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    Rotation of maize with cowpea improves yield and nutrient use of maize compared to maize monocropping in an alfisol in the northern Guinea Savanna of Ghana (1994)
    Springer
    Plant and soil 160 (1994), S. 171-183 
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    ISSN: 1573-5036
    Keywords: allelopathy ; crop rotation ; nitrogen utilization ; root growth ; soil nitrate depletion ; Vigna unguiculata ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the northern Guinea Savanna of Ghana (1984–1987) a field experiment was conducted to study the reasons for beneficial effects of rotating maize (Zea mays) and cowpea (Vigna unguiculata) on yield and N and P use of maize. The treatments included two cropping systems, maize monocropping and maize/cowpea rotation, two levels of nitrogen (0 and 80 kg N ha-1 as urea) and two levels of phosphorus application (0 and 60 kg ha-1 P as Volta phosphate rock). Yields and nutrient accumulation of maize were larger in rotation than in monocropping, independent of the N and P level. Fertilizer application (N and P) increased yields of maize in both cropping systems to the same extent. Nitrate contents of the soil after cowpea and after maize monoculture were comparable at the beginning of the cropping period. Also, potential nitrogen mineralization was only slightly larger after cowpea in the unfertilized plots. However, soil nitrate of fertilized plots was similar or even higher under monocropping than under crop rotation, especially in deeper soil layers and at the end of the cropping period. This indicates that in addition to the availability of mineral N, its use by the plants was limiting for the productivity of maize. Root length densities of maize were significant lower in monocropped maize than in maize grown in rotation. Soil physical parameters (infiltration, bulk density, aggregate stability and water capacity) showed a significant deterioration compared to a bush fallow plot, but differed only slightly between the cropping systems. Also in a pot experiment maize growth was much better in the soil from the crop rotation than from the monocropping plots, provided P was eliminated as the main growth-limiting factor. Since this effect persisted in spite of N application and optimization of soil physical properties by mixing the soil with polystyrol it is concluded that the results indicate that yield decline in maize monocropping might be due to allelopathic effects.
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    Carbon translocation to the rhizosphere of maize and wheat and influence on the turnover of native soil organic matter at different soil nitrogen levels (1994)
    Springer
    Plant and soil 161 (1994), S. 233-240 
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    ISSN: 1573-5036
    Keywords: C distribution ; native soil organic matter ; rhizosphere ; root released carbon ; wheat ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat and maize were grown in a growth chamber with the atmospheric CO2 continuously labelled with 14C to study the translocation of assimilated carbon to the rhizosphere. Two different N levels in soil were applied. In maize 26–34% of the net assimilated 14C was translocated below ground, while in wheat higher values (40–58%) were found. However, due to the much higher shoot production in maize the total amount of carbon translocated below ground was similar to that of wheat. At high N relatively more of the C that was translocated to the root, was released into the soil due to increased root respiration and/or root exudation and subsequent microbial utilization and respiration. The evolution rate of unlabelled CO2 from the native soil organic matter decreased after about 25 days when wheat was grown at high N as compared to low N. This negative effect of high N in soil was not observed with maize.
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    URL: http://dx.doi.org/10.1007/BF00046394
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    A fluorimetric assay for determining variation of lysine in wheat gliadin proteins (1994)
    Springer
    Euphytica 76 (1994), S. 97-100 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; high performance liquid chromatography ; HPLC ; nutrition ; wheat breeding ; lysine content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An effective method for estimating lysine in wheat gliadin proteins could contribute to increasing lysine in wheat. Wheat gliadin proteins were separated and collected by reverse phase high performance liquid chromatography (RP-HPLC). A fluorimetric assay with o-phthalaldehyde (OPA) was used to determine the lysine content of wheat gliadin proteins. The OPA reagent reacts specifically with the amino group of lysine in protein. Twenty fractions of wheat gliadins were collected and analyzed by the fluorimetric assay. Nine of these fractions were also analyzed for lysine content by an amino acid analyzer. The results obtained from the fluorimetric assay were significantly related to the results obtained from the amino acid analyzer (R=0.93 for quadratic regression of the nine selected gliadin fractions). Lysine content of the wheat gliadins varied from 0.6 to 1.4 percent of the protein. This study determined that the fluorimetric assay could accurately estimate lysine in wheat gliadin proteins. Identification of high-lysine gliadin subunits could be implemented into a program of breeding for increased lysine in wheat.
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    URL: http://dx.doi.org/10.1007/BF00024025
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    Combining abilities of in vitro traits in wheat (Triticum aestivum L.) immature embryo cultures (1994)
    Springer
    Euphytica 76 (1994), S. 169-175 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; combining ability ; in vitro culture ; genotypic and phenotypic correlations ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Combining ability for six in vitro culture traits in wheat were studied in a 8×8 diallel cross (excluding reciprocals). Specific combining ability effects (sca) were significant for all six traits derived from immature embryos on two media protocols, whereas general combining ability (gca) variances were significant only for five of them. Furthermore, based on ratios obtained by comparing the ratio of K2 gca to K2 sca, sca was more important than gca for all six traits. Genetic correlations between shoot formation and other in vitro traits, except callus weight and root formation, were higher in magnitude than the corresponding phenotypic correlations estimates, indicating the importance of genetic effects.
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    URL: http://dx.doi.org/10.1007/BF00022161
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    Gene action and heritability for photosynthetic activity in two wheat crosses (1994)
    Springer
    Euphytica 76 (1994), S. 235-238 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; photosynthesis ; gene action ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Gene action and heritability for photosynthetic activity were estimated from generation means in two wheat crosses during two stages (5 th leaf and flag leaf between 2 and 5 days after anthesis). Six generations were available for each cross: parents (P1 and P2), F1, F2 and backcrosses (BC1 and BC2). Correlations between some morphophysiological characters and photosynthetic activity of the flag leaf was also determined. The joint scaling test described by Mather & Jinks was used to determine the gene action. It showed that them; [d]; [h]; [i], [l] (mean, additivity, dominance, additive x additive interallelic interaction effects, dominance x dominance interallelic interaction effects) model fits the two crosses at both measurement times. All the model genetic components were significant for the flag leaf, however for the 5 th leaf only [h]; [i] and [l] were significant. The presence of additive and additive x additive effects suggested the possibility of selecting for this character using the flag leaf so as to obtain pure inbred lines. Dominance effects [h] were negative and dominance x dominance effects [l] were positive. Broad sense heritability values were medium to low. There were no correlations between the studied morphophysiological characters and the photosynthetic activity.
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    URL: http://dx.doi.org/10.1007/BF00022168
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    Genetic control of frost tolerance in wheat (Triticum aestivum L.) (1994)
    Springer
    Euphytica 77 (1994), S. 277-282 
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    ISSN: 1573-5060
    Keywords: Wheat ; frost tolerance ; diallel cross ; monosomics ; Triticum aestivum ; chromosome substitutions ; wild species ; somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The frost tolerance of winter wheat is one component of winter hardiness. If seedlings are frost resistant, it means that they can survive the frost effect without any considerable damage. To study the genetic control of frost tolerance, an artificial freezing test was used. Frost tolerance is controlled by an additive-dominance system. The results of diallel analyses indicate the importance of both additive and non-additive gene action in the inheritance of this character. The dominant genes act in the direction of lower frost tolerance and the recessive genes in the direction of a higher level of frost tolerance. The results of monosomic and substitution analyses show that at least 10 of the 21 pairs of chromosomes are involved in the control of frost tolerance and winter hardiness. Chromosomes 5A and 5D have been implicated most frequently. The geneFr1 (Frost 1) was located on the long arm of chromosome 5A. Crosses between cultivars, chromosome manipulation and the induction of somaclonal variation may be suitable methods for broadening the gene pool for frost tolerance.
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    URL: http://dx.doi.org/10.1007/BF02262642
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    Properties of maternal haploid maize plants and potential application to maize breeding (1994)
    Springer
    Euphytica 79 (1994), S. 13-18 
    Details
    ISSN: 1573-5060
    Keywords: Zea mays ; haploid induction ; maternal haploids ; inducer line ZMS ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Presented are the results of a two-year study of haploid maize plants in the field. The haploids were produced with the aid of inducer line ZMS. In total, 604 and 1030 haploids were obtained and studied in the first and second years, respectively. Tassels of haploid plants were found to be almost completley sterile. Fertility of ears was studied by pollinating them with the pollen from diploid inbred lines, the cross resulting in almost all of the haploid ears carrying kernels. On average 27.4 kernels per ear of haploid plant were obtained in the first year of study and 26.3 in the second. These gave rise to normal diploid plants. This property allows genotypes selected at the level of haploid plants to be involved in breeding process. Unusual plants were found among haploids, phenotypically resembling homozygous lines. It was assumed that the plants had resulted from spontaneous chromosome doubling in haploids. The results of comparative studies of progenies of unusual plants and inbred lines derived from the same synthetic population are presented.
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    URL: http://dx.doi.org/10.1007/BF00023571
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    The derivation of compensating translocations involving homoeologous group 3 chromosomes of wheat and rye (1994)
    Springer
    Euphytica 79 (1994), S. 75-80 
    Details
    ISSN: 1573-5060
    Keywords: intergeneric gene transfer ; misdivision ; rye ; Secale cereale ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The Sr27 translocation in WRT238 was found to consist of chromosome arms 3RS of rye and 3AS of common wheat. An attempt was made to purposely produce compensating translocations having 3RS and a wheat homoeologous group 3L arm. To achieve this, plants, double monosomic for 3R and a wheat homoeologous group 3 chromosome, were irradiated (7.5 Gy gamma rays) or left untreated before being used to pollinate stem rust susceptible testers. Segregation for stem rust resistance was studied to identify F2 families with Sr27-carrying translocated chromosomes, these were confirmed by means of C-banding. Compensating translocations 3RS3AL and 3RS3BL) were obtained readily and at similar frequencies from untreated and irradiated plants (respectively, 7.2% and 9.3%). Both translocation types have impaired transmission and segregate approximately 3: 2 (present: absent) in the F2.
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    Coleoptile tiller development is associated with fast early vigour in wheat (1994)
    Springer
    Euphytica 80 (1994), S. 119-124 
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    ISSN: 1573-5060
    Keywords: coleoptile tiller ; Triticum aestivum ; vigour ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Faster canopy development in temperate cereals can result in more efficient utilization of wate, light and nutrients if these are in limited supply. It can also result in more competitive plants and less use of herbicides. The possible importance of the coleoptile tiller for increasing early vigour in wheat (Triticum aestivum L.) was determined for twelve F4 lines in two experiments. Each F4 line was chosen for variation in the presence and absence of a coleoptile tiller in plants in the previous generation; each F4 line was traced to a single F2 plant from a multiple convergent cross of sixteen parents. Eight plants of each of the F4 lines were grown in a single row in both experiments. Just after the coleoptile tiller appeared, plants within each line were classified into one of two groups; one group contained plants with large coleoptile tillers whereas the other group had either small coleoptile tillers or none at all. Leaf expansion rates were determined non-destructively at regular intervals, and plants were harvested to determine leaf and tiller characteristics when there were about five mainstem leaves. There was substantial variation in the leaf area of the coleoptile tiller both between groups and among lines. In both experiments plants with a large coleoptile tiller had 24–30% more leaf area and dry weight than plants selected with a small or absent coleoptile tiller up to the final harvest. Leaf expansion rates (increase in leaf area per day) were 25 to 35% greater in the large coleoptile tiller selections from the time tillers first appeared to the time of harvest, whereas the relative leaf expansion rate (increase in leaf area per unit of leaf area present per day) of the large selections was significantly greater than the small selections only at the time of appearance of the coleoptile tiller and just after. There was no evidence that the early appearance of a coleoptile tiller was associated with the largest seedlings or that it inhibited the growth of later tillers. It is concluded that selection for the appearance of a large coleoptile tiller should improve the early vigour of temperate cereals.
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    URL: http://dx.doi.org/10.1007/BF00039306
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    Singlet oxygen production in thylakoid membranes during photoinhibition as detected by EPR spectroscopy (1994)
    Springer
    Photosynthesis research 39 (1994), S. 191-199 
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    ISSN: 1573-5079
    Keywords: photoinhibition ; photosynthesis ; protein degradation ; singlet oxygen ; TEMP (2,2,6,6-tetramethylpiperidine) ; thylakoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Exposure of isolated spinach thylakoids to high intensity illumination (photoinhibition) results in the well-characterized impairment of Photosystem II electron transport, followed by degradation of the D1 reaction centre protein. In the present study we demonstrate that this process is accompanied by singlet oxygen production. Singlet oxygen was detected by EPR spectroscopy, following the formation of stable nitroxide radicals from the trapping of singlet oxygen with a sterically hindered amine TEMP (2,2,6,6-tetramethylpiperidine). There was no detectable singlet oxygen production during anaerob photoinhibition or in the presence of sodium-azide. Comparing the kinetics of the loss of PS II function and D1 protein with that of singlet oxygen trapping suggests that singlet oxygen itself or its radical product initiates the degradation of D1.
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    URL: http://dx.doi.org/10.1007/BF00029386
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    Changes in the antenna size of Photosystem I and Photosystem II in Synechococcus sp. strain PCC 7942 grown in the presence of SANDOZ 9785 — a Photosystem II inhibitor (1994)
    Springer
    Photosynthesis research 41 (1994), S. 303-313 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; excitation energy ; herbicide ; photochemical apparatus ; photosynthesis ; pyridazinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract SANDOZ 9785, also known as BASF 13.338, is a pyridazinone derivative that inhibits Photosystem II (PS II) activity leading to an imbalance in the rate of electron transport through the photosystems. Synechococcus sp. strain PCC 7942 cells grown in the presence of sublethal concentration of SANDOZ 9785 (SAN 9785) for 48 hours exhibited a 20% decrease in Chl a per cell. However, no changes were observed in the content of phycocyanin per cell, the size of the phycobilisomes or in the PS II:PS I ratio. From an estimate of PS II electron transport rate under varying light intensities and spectral qualities and analysis of room temperature Chl a fluorescence induction, it was deduced that growth of Synechococcus PCC 7942 in the presence of SAN 9785 leads to a redistribution of excitation energy in favour of PS II. Though the redistribution appears to be primarily caused by changes affecting the Chl a antenna of PS II, the extent of energetic coupling between phycobilisomes and PS II is also enhanced in SAN 9785 grown Synechococcus PCC 7942 cells. There was a reduction in the effective size of PS I antenna based on measurement of P700 photooxidation kinetics. These results indicate that when PS II is partially inhibited, the structure of photosynthetic apparatus alters to redistribute the excitation energy in favour of PS II so that the efficiency of utilization of light energy by the two photosystems is optimized. Our results suggest that under the conditions used, drastic structural changes are not essential for redistribution of excitation energy between the photosystems.
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    URL: http://dx.doi.org/10.1007/BF00019408
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    Acclimation of photosynthesis to increasing atmospheric CO2: The gas exchange perspective (1994)
    Springer
    Photosynthesis research 39 (1994), S. 351-368 
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    ISSN: 1573-5079
    Keywords: CO2 enrichment ; gas exchange ; greenhouse effect ; photosynthesis ; responses to CO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nature of photosynthetic acclimation to elevated CO2 is evaluated from the results of over 40 studies focusing on the effect of long-term CO2 enrichment on the short-term response of photosynthesis to intercellular CO2 (the A/Ci response). The effect of CO2 enrichment on the A/Ci response was dependent on growth conditions, with plants grown in small pots (〈 5 L) or low nutrients usually exhibiting a reduction of A at a given Ci, while plants grown without nutrient deficiency in large pots or in the field tended to exhibit either little reduction or an enhancement of A at a given Ci following a doubling or tripling of atmospheric CO2 during growth. Using theoretical interpretations of A/Ci curves to assess acclimation, it was found that when pot size or nutrient deficiency was not a factor, changes in the shape of A/Ci curves which are indicative of a reallocation of resources within the photosynthetic apparatus typically were not observed. Long-term CO2 enrichment usually had little effect or increased the value of A at all Ci. However, a minority of species grown at elevated CO2 exhibited gas exchange responses indicative of a reduced amount of Rubisco and an enhanced capacity to metabolize photosynthetic products. This type of response was considered beneficial because it enhanced both photosynthetic capacity at high CO2 and reduced resource investment in excessive Rubisco capacity. The ratio of intercellular to ambient CO2 (the Ci/Ca ratio) was used to evaluate stomatal acclimation. Except under water and humidity stress, Ci/Ca exhibited no consistent change in a variety of C3 species, indicating no stomatal acclimation. Under drought or humidity stress, Ci/Ca declined in high-CO2 grown plants, indicating stomata will become more conservative during stress episodes in future high CO2 environments.
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    URL: http://dx.doi.org/10.1007/BF00014591
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    Effects of UV-B radiation on photosynthesis and growth of terrestrial plants (1994)
    Springer
    Photosynthesis research 39 (1994), S. 463-473 
    Details
    ISSN: 1573-5079
    Keywords: global climate change ; ozone depletion ; photosynthesis ; Photosystem II ; productivity ; UV-B radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The photosynthetic apparatus of some plant species appears to be well-protected from direct damage from UV-B radiation. Leaf optical properties of these species apparently minimizes exposure of sensitive targets to UV-B radiation. However, damage by UV-B radiation to Photosystem II and Rubisco has also been reported. Secondary effects of this damage may include reductions in photosynthetic capacity, RuBP regeneration and quantum yield. Furthermore, UV-B radiation may decrease the penetration of PAR, reduce photosynthetic and accessory pigments, impair stomatal function and alter canopy morphology, and thus indirectly retard photosynthetic carbon assimilation. Subsequently, UV-B radiation may limit productivity in many plant species. In addition to variability in sensitivity to UV-B radiation, the effects of UV-B radiation are further confounded by other environmental factors such as CO2, temperature, light and water or nutrient availability. Therefore, we need a better understanding of the mechanisms of tolerance to UV-B radiation and of the interaction between UV-B and other environmental factors in order to adequately assess the probable consequences of a change in solar radiation.
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    State adaptations in the cyanobacterium Synechcoccus 6301 (PCC): Dependence on light intensity or spectral composition? (1994)
    Springer
    Photosynthesis research 40 (1994), S. 107-117 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; state adaptations ; shade adaptation ; cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A profile of high light to intense self-shading conditions was constructed using a white light source and cultures of the cyanobacterium Synechococcus 6301; this profile approximates to a natural self-shading gradient of decreasing light intensity and PS II/PS I excitation ratio. Samples of S.6301 were placed along this profile and allowed to state adapt. To separate the effects of light intensity and wavelength on state adaptation, samples were also placed in a shade profile produced by a white light source and neutral density filters. After adaptation, samples were fixed in their resulting state by the addition of glutaraldehyde, and fluorescence measurements were made at 35° C or –160 °C. It is concluded: 1. Under conditions of deep shade (〈5 μmol m−2s−1 PAR) and weak shade (〉200 μmol m−2s−1 PAR), cells adapt to a low PS II fluorescence state (state 2); in moderate shade (20–60 μmol m−2s−1PAR) cells adapt to a high PS II fluorescence state (state 1). We suggest these findings provide evidence for the operation of different factors on the control of state adaptations in cyanobacteria; one set operates at low light and another at high light intensities. 2. Under conditions of self-shading, there is little evidence to support the contention that state adaptations in cyanobacteria are produced by wavelength-dependent changes in the PS II/PS I excitation ratio, instead, it appaers they are produced by changes in the intensity of incident irradiation. 3. The observed fluorescence changes do not appear to involve major changes in the phycobilisome sensitisation of PS II and PS I. Instead, it appears that these changes are effected by alterations in ΦF of PS II (i.e. changes in PS II excitation density caused by alterations in the rate constants controlling spillover to PS I, photochemistry, fluorescence emission or thermal deactivation.
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    An enzyme and13C-NMR study of carbon metabolism in heliobacteria (1994)
    Springer
    Photosynthesis research 41 (1994), S. 75-88 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; carbon assimilation ; photosynthetic bacteria ; citric-acid cycle ; pyruvate synthase ; fermentation ; heliobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Heliobacteria are a group of anoxygenic phototrophs that can grow photoheterotrophically in defined minimal media on only a limited range of organic substrates as carbon sources. In this study the mechanisms which operate to assimilate carbon and the routes employed for the biosynthesis of cellular intermediates were investigated in a newHeliobacterium strain, HY-3. This was achieved using two approaches (1) by measuring the activities of key enzymes in cell-free extracts and (2) by the use of13C nuclear magnetic resonance (NMR) spectroscopy to analyze in detail the labelling pattern of amino-acids of cells grown on [13C] pyruvate and [13C] acetate.Heliobacterium strain HY-3 was unable to grow autotrophically on CO2/H2 and neither (ATP)-citrate lyase nor ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBPcase) were detectable in cell-free extracts. The enzyme profile of pyruvate grown cells indicated the presence of a pyruvate:acceptor oxidoreductase at high specific activity which could convert pyruvate to acetyl-Coenzyme A. No pyridine nucleotide dependent pyruvate dehydrogenase complex activity was detected. Of the citric-acid cycle enzymes, malate dehydrogenase, fumarase, fumarate reductase and an NADP-specific isocitrate dehydrogenase were readily detectable but no aconitase or citrate synthase activity was found. However, the labelling pattern of glutamate in long-term 2-[13C] acetate incorporation experiments indicated that a mechanism exists for the conversion of carbon from acetyl-CoA into 2-oxoglutarate. A 2-oxoglutarate:acceptor oxidoreductase activity was present which was also assayable by isotope exchange, but no 2-oxoglutarate dehydrogenase complex activity could be detected. Heliobacteria appear to use a type of incomplete reductive carboxylic acid pathway for the conversion of pyruvate to 2-oxoglutarate but are unable to grow autotrophically using this metabolic route due to the absence of ATP-citrate lyase.
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    Spectroscopic evidence for the presence of an iron-sulfur center similar to Fx of Photosystem I inHeliobacillus mobilis (1994)
    Springer
    Photosynthesis research 41 (1994), S. 115-123 
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    ISSN: 1573-5079
    Keywords: photosynthesis ; bacteriochlorophyll ; electron acceptor ; iron-sulfur center ; Photosystem I ; heliobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Treatment of membranes ofHeliobacillus mobilis with high concentrations of the chaotropic agent urea resulted in the removal of the iron-sulfur centers FA and FB from the reaction center, as indicated by EPR spectra under strongly reducing conditions. In urea-treated membranes, transient absorption measurements upon a laser flash indicated a recombination between the photo-oxidized primary donor P798+ and a reduced acceptor with a time constant of 20 ms at room temperature. Benzylviologen, vitamin K-3 and methylene blue were found to accept electrons from the reduced acceptor efficiently. A differential extinction coefficient of 225–240 mM−1 cm−1 at 798 nm was determined from experiments in the presence of methylene blue. Transient absorption difference spectra between 400 and 500 nm in the presence and absence of artificial acceptors indicated that the electron acceptor involved in the 20 ms recombination has an absorption spectrum similar to that of an iron-sulfur center. This iron-sulfur center was assigned to be analogous to FX of Photosystem I. Our results provide evidence in support of the presence of FX in heliobacteria, which was proposed on the basis of the reaction center polypeptide sequence (Liebl et al. (1993) Proc. Natl. Acad. Sci. USA 90: 7124–7128). Implications for the electron transfer pathway in the reaction center of heliobacteria are discussed.
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    Molecular organization of bacteriochlorophyll in chlorosomes of the green photosynthetic bacteriumChloroflexus aurantiacus: Studies of fluorescence depolarization accompanied by energy transfer processes (1994)
    Springer
    Photosynthesis research 41 (1994), S. 181-191 
    Details
    ISSN: 1573-5079
    Keywords: energy transfer ; green bacteria ; photosynthesis ; picosecond spectroscopy ; pigment system ; (Chloroflexus aurantiacus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Examination was made of changes in fluorescence polarization plane by energy transfer in the chlorosomes of the green photosynthetic bacterium,Chloroflexus aurantiacus. Fluorescence anisotropy in the picosecond (ps) time region was analyzed using chlorosomes suspended in solution as well as those oriented in a polyacrylamide gel. When the main component of BChlc was preferentially excited, the decay of fluorescence anisotropy was found to depend on wavelength. In the chlorosome suspension, the anisotropy ratio of BChlc changed from 0.31 to 0.24 within 100 ps following excitation. In the baseplate BChla region, this ratio decreased to a negative value (−0.09) from the initial 0.14. In oriented samples, the degree of polarization remained at 0.68 for BChlc, and changed from 0.25 to −0.40 for the baseplate BChla by excitation light whose electric vector was parallel to the longest axis of chlorosomes. In the latter case, there was a shift from 0.30 to −0.55 by excitation perpendicular to the longest axis. Time-resolved fluorescence polarization spectra clearly indicated extensive changes in polarization plane accompanied by energy transfer. The directions of polarization plane of emission from oriented samples were mostly dependent on chlorosome orientation in the gel but not on that of the polarization plane of excitation light. Orientations of the dipole moment of fluorescence components was consistent with that of absorption components as determined by the linear dichroism (Matsuura et al. (1993) Photochem. Photobiol. 57: 92–97). A model for molecular organization of BChlc anda in chlorosomes is proposed based on anisotropic optical properties.
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    Evolution of heliobacteria: Implications for photosynthetic reaction center complexes (1994)
    Springer
    Photosynthesis research 41 (1994), S. 285-294 
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    ISSN: 1573-5079
    Keywords: heliobacteria ; reaction center ; photosynthesis ; 16S rRNA sequence ; cyanobacteria ; Gram-positive bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolutionary position of the heliobacteria, a group of green photosynthetic bacteria with a photosynthetic apparatus functionally resembling Photosystem I of plants and cyanobacteria, has been investigated with respect to the evolutionary relationship to Gram-positive bacteria and cyanobacteria. On the basis of 16S rRNA sequence analysis, the heliobacteria appear to be most closely related to Gram-positive bacteria, but also an evolutionary link to cyanobacteria is evident. Interestingly, a 46-residue domain including the putative sixth membrane-spanning region of the heliobacterial reaction center protein shows rather strong similarity (33% identity and 72% similarity) to a region including the sixth membrane-spanning region of the CP47 protein, a chlorophyll-binding core antenna polypeptide of Photosystem II. The N-terminal half of the heliobacterial reaction center polypeptide shows a moderate sequence similarity (22% identity over 232 residues) with the CP47 protein, which is significantly more than the similarity with the Photosystem I core polypeptides in this region. An evolutionary model for photosynthetic reaction center complexes is discussed, in which an ancestral homodimeric reaction center protein (possibly resembling the heliobacterial reaction center protein) with 11 membrane-spanning regions per polypeptide has diverged to give rise to core of Photosystem I, Photosystem II, and of the photosynthetic apparatus in green, purple, and heliobacteria.
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    The photoproduction of superoxide radicals and the superoxide dismutase activity of Photosystem II. The possible involvement of cytochrome b559 (1994)
    Springer
    Photosynthesis research 41 (1994), S. 327-338 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; Photosystem II ; superoxide radical ; superoxide dismutase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the present study the light induced formation of superoxide and intrinsic superoxide dismutase (SOD) activity in PS II membrane fragments and D1/D2/Cytb559-complexes from spinach have been analyzed by the use of ferricytochrome c (cyt c(III)) reduction and xanthine/xanthine oxidase as assay systems. The following results were obtained: 1.) Photoreduction of Cyt c (III) by PS II membrane fragments is induced by addition of sodium azide, tetracyane ethylene (TCNE) or carbonylcyanide-p-trifluoromethoxy-phenylhydrazone (FCCP) and after removal of the extrinsic polypeptides by a 1M CaCl2-treatment. This activity which is absent in control samples becomes completely inhibited by the addition of exogenous SOD. 2.) The TCNE induced cyt c(III) photoreduction by PS II membrane fragments was found to be characterized by a half maximal concentration of c1/2=10 μM TCNE. Simultaneously, TCNE inhibits the oxygen evolution rate of PS II membrane fragments with c1/2≈ 3 μM. 3.) The photoproduction of O2 − is coupled with H+-uptake. This effect is diminished by the addition of the O2 −-trap cyt c(III). 4.) D1/D2/Cytb559-complexes and PS II membrane fragments deprived of the extrinsic proteins and manganese exhibit no SOD-activity but are capable of producing O2 − in the light if a PS II electron donor is added. Based on these results the site(s) of light induced superoxide formation in PS II is (are) inferred to be located at the acceptor side. A part of the PS II donor side and Cyt b559 in its HP-form are proposed to provide an intrinsic superoxide dismutase (SOD) activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00019410
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    Thermoluminescence as a probe of Photosystem II in intact leaves: Non-photochemical fluorescence quenching in peas grown in an intermittent light regime (1994)
    Springer
    Photosynthesis research 41 (1994), S. 371-379 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; chlorophyll fluorescence ; high energy-state quenching ; calcium release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have measured thermoluminescence (TL) and chlorophyll fluorescence from leaves of peas grown under an intermittent light regime (IML) and followed changes in those leaves during greening. IML peas show low variable fluorescence and a certain capacity for reversible non-photochemical quenching. It has been suggested that reversible quenching may be caused by pH-dependent release of Ca2+ from Photosystem II (PS II) (Krieger and Weis (1992) Photosynthetica 27: 89–98). Under conditions in which reversible non-photochemical quenching occurs, a TL band at around 50 °C is observed, in the presence of DCMU, in IML leaves. A band in this temperature range has previously been observed in PS II depleted of Ca2+ (Ono and Inoue (1989) Biochimica et Biophysica Acta 973: 443–449). The 50 °C band disappears upon dark adaptation. In mature leaves, no significant band is seen at 50 °C. It is concluded that, in IML leaves, reversible quenching may be related to the release of Ca2+ from Photosystem II. However, it seems that in the mature system, under most conditions, such release does not contribute significantly to quenching
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    URL: http://dx.doi.org/10.1007/BF02183039
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    Measurements of mesophyll conductance, photosynthetic electron transport and alternative electron sinks of field grown wheat leaves (1994)
    Springer
    Photosynthesis research 41 (1994), S. 397-403 
    Details
    ISSN: 1573-5079
    Keywords: electron transport rate ; mesophyll conductance to CO2 diffusion ; photosynthesis ; photorespiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic electron transport drives the carbon reduction cycle, the carbon oxidation cycle, and any alternative electron sinks such as nitrogen reduction. A chlorophyll fluorescence— based method allows estimation of the total electron transport rate while a gas-exchange-based method can provide estimates of the electron transport needed for the carbon reduction cycle and, if the CO2 partial pressure inside the chloroplast is accurately known, for the carbon oxidation cycle. The gas-exchange method cannot provide estimates of alternative electron sinks. Photosynthetic electron transport in flag leaves of wheat was estimated by the fluorescence method and gasexchange method to determine the possible magnitude of alternative electron sinks. Under non-photorespiratory conditions the two measures of electron transport were the same, ruling out substantial alternative electron sinks. Under photorespiratory conditions the fluorescence-based electron transport rate could be accounted for by the carbon reduction and carbon oxidation cycle only if we assumed the CO2 partial pressure inside the chloroplasts to be lower than that in the intercellular spaces of the leaves. To further test for the presence of alternative electron sinks, carbon metabolism was inhibited by feeding glyceraldehyde. As carbon metabolism was inhibited, the electron transport was inhibited to the same degree. A small residual rate of electron transport was measured when carbon metabolism was completely inhibited which we take to be the maximum capacity of alternative electron sinks. Since the alternative sinks were small enough to ignore, the comparison of fluorescence and gas-exchange based methods for measuring the rate of electron transport could be used to estimate the mesophyll conductance to CO2 diffusion. The mesophyll conductance estimated this way fell as wheat flag leaves senesced. The age-related decline in photosynthesis may be attributed in part to the reduction of mesophyll conductance to CO2 diffusion and in part to the estimated decline of ribulose 1,5-bisphosphate carboxylase amount.
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    URL: http://dx.doi.org/10.1007/BF02183042
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    Changes in the photosynthetic light response curve during leaf development of field grown maize with implications for modelling canopy photosynthesis (1994)
    Springer
    Photosynthesis research 42 (1994), S. 217-225 
    Details
    ISSN: 1573-5079
    Keywords: photosynthesis ; leaf age ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the photosynthetic light-response curve during leaf development were determined for the fourth leaf of maize crops sown on 23 April and 10 June. Temperatures were unusually mild during late spring/early summer and neither crop experienced chilling damage. The concept of thermal time was used to take into account the effects of different temperature regimes on developmental stage, thereby enabling photosynthetic light-response data to be combined for both crops to describe the general response. Large variations in the upper asymptote (Asat) and convexity (Θ) of the light-response curve occurred during leaf development, but the maximum quantum yield of CO2 assimilation remained relatively constant throughout. Dark respiration rates showed a small but significant decrease with leaf age and generally ranged between 5 and 10% of Asat. A simple mathematical model was developed to assess the sensitivity of daily leaf photosynthesis (AL) to reductions in the Asat, Θ and the initial slope (Φ) of the light-response curve at different stages of leaf development. On bright sunny days, and at all developmental stages, AL was ca. twice as sensitive to reductions in Asat than to reductions in Φ and Θ. In overcast conditions, however, all three parameters contributed significantly to reductions in leaf photosynthesis, although the contribution of Φ was greatest during early leaf growth, while older leaves were most sensitive to depressions in Asat. The implications of these results for modelling the sensitivity of canopy photosynthesis to chill-induced photoinhibition of the light-response curve are discussed.
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    URL: http://dx.doi.org/10.1007/BF00018264
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    Calcium-dependent asymmetric movement of 3H-indole-3-acetic acid across gravistimulated isolated root caps of maize (1994)
    Springer
    Plant growth regulation 14 (1994), S. 235-242 
    Details
    ISSN: 1573-5087
    Keywords: auxin transport ; calcium ; gravitropism ; root cap ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract There is evidence that the cap is the initial site of lateral auxin redistribution during the gravitropic response of roots. We tested this further by comparing asymmetric auxin redistribution across the tips of gravistimulated intact roots, decapped roots, isolated root caps and isolated apical sections taken from decapped roots. Gravistimulation caused asymmetric (downward) auxin movement across the tips of intact roots and isolated root caps but not across the tips of decapped roots or across isolated apical root segments. Naphthylphthalamic acid and pyrenoylbenzoic acid, inhibitors of polar auxin transport, inhibited asymmetric auxin redistribution across gravistimulated isolated root caps and across the tips of gravistimulated intact roots. For intact roots there was a positive correlation between the extent of inhibition of assymmetric auxin redistribution by polar auxin transport inhibitors and the extent of inhibition of asymmetric calcium chelating agent, ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, also caused parallel inhibition of asymmetric auxin redistribution and gravitropic curvature and this effect was reversed by subsequent treatment with calcium. The results support the hypothesis that the cap is a site of early development of auxin asymmetry in gravistimulated roots and that calcium plays an important role in the development of lateral auxin redistribution.
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    URL: http://dx.doi.org/10.1007/BF00024798
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    The barbs (Barbus spp.) of Lake Tana: a forgotten species flock? (1994)
    Springer
    Environmental biology of fishes 39 (1994), S. 1-22 
    Details
    ISSN: 1573-5133
    Keywords: Cyprinids ; Ethiopia ; Morphotypes ; Food-niche ; Biodiversity ; Feeding ; Evolution ; Fisheries ; Resource partitioning ; Piscivory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis In October–December 1990, the large barbs (Barbus) that contribute more than 35% of the catch in lake Tana (northern Ethiopia) were studied. Previous authors (Rüppell 1837, Boulenger 1902,1911, Bini 1940) described from 6 to 23 (sub)species for the lake. Banister (1973) lumped all of these into one subspecies: Barbus intermedius intermedius Rüppell,1837. We found that the Lake Tana Barbus could be readily categorized in at least 13 discrete morphotypes, some of which were already distinguished by local fishermen. None of the known descriptions are adequate to distinguish the barbs unambiguously, which is important for monitoring and management of developing fisheries. Intermediates between morphotypes were rare (〈 10%). By applying canonical discriminant analysis on a set of 17 morphometric characters (including some directly associated with feeding) our initial morphotype-distinction was confirmed. Also, differences between the morphotypes in distribution, related to depth and substratum were found, as well as differences in intestinal contents, a key to the food-niche. The high number of piscivorous morphotypes (8 out of 13) was striking as piscivory is relatively rare among cyprinids. Piscivory was found to be highly correlated with morphological (feeding related) characters. The presence of discrete morphotypes, that also differ in food-niche and distribution, strongly suggests that several distinct populations exist, that may be (partly or completely) reproductively segregated. Knowledge about these populations, that may represent separate units of fish stock, is of crucial importance for the management of sustainable fisheries and protection of the biodiversity in Lake Tana. It is possible that several species or even a unique cyprinid species flock are present, that urgently need protection.
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    URL: http://dx.doi.org/10.1007/BF00004751
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    The homoeologous relationships of the arms of wheat chromosomes 2A and 2D to chromosome 2B and their effect on homoeologous pairing (1994)
    Springer
    Chromosome research 2 (1994), S. 275-279 
    Details
    ISSN: 1573-6849
    Keywords: C-banding ; homoeologous pairing ; homoeologous relationships ; pairing genes ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Homoeologous relationships between the arms of wheat group 2 chromosomes were analysed by studying homoeologous pairing in wheat—rye hybrids. Chromosomes 2A and 2D were identified using telocentrics 2AS, 2DS or 2DL. The remaining wheat chromosomes and their arms were identified by C-banding. Wheat chromosomes in the hybrids were derived from plants which were heterozygous(Ph1/ph1b) and monotelocentric for 2AS, 2DS or 2DL. In these plants, chromosome 2B and the telocentric showed regular bivalent pairing. From the results of homoeologous pairing in wheat—rye hybrids, normal homoeologous relationships between 2AS, 2BS and 2DS, as well as between 2AL, 2BL and 2DL, were deduced. There was no evidence that wheat group 2 chromosomes were involved in evolutionary chromosome rearrangements. The existence of a pairing promoter gene on chromosome arm 2DS was supported.
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    URL: http://dx.doi.org/10.1007/BF01552721
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    Determination of sugars by liquid chromatography with post-column catalytic derivatization and fluorescence detection (1994)
    Springer
    Chromatographia 38 (1994), S. 12-16 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carbohydrates ; Post-column fluorescence derivatization ; Post column catalytic reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the determination of reducing sugars such as fructose and glucose and nonreducing sugar such as sucrose by high performance liquid chromatography followed by an acidic hydrolysis and a derivatization with benzamidine has been developed. After separation of sugars on a gel column packed with a polymer-based cation exchange material (Sugar-Pak I, Waters-Millipore), the sucrose is first hydrolysed in a solid phase reactor to convert it into reducing subunits. A post-column fluorigenic reaction with benzamidine under alkaline condition allows the selective determination of both natural and converted reducing carbohydrates. This procedure has proven to be selective (fluorigenic detection) and highly sensitive (allowing detection as little as picomoles amounts), reproducible and linear over a broad range of concentrations: 5×10−4 to 1.0×10−2 M. The applicability of this method to natural matrices such as plant extracts and beverages is also described. The sugar content of a barley extract has been determined and compared with a specific enzymatic test. The determined sugar content of natural and commercial lemon juices as well as of Cola beverages has been compared with those found by the conventional LC refractive index analytical procedure. In all cases, the results were comparable and were within the experimental errors of the methods.
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    URL: http://dx.doi.org/10.1007/BF02275720
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    Chromatography of esculin from stems and bark ofAesculus hippocastanum L. for consecutive vegetative periods (1994)
    Springer
    Chromatographia 38 (1994), S. 766-770 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Densitometry ; Spectrophotometry of extracts ; Esculin, fraxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Coumarin glucosides, esculin and fraxin, were determined in several older and younger layers of stems ofAesculus hippocastanum L. by three methods (TLC-densitometry, TLC-extraction and spectrophotometric determinations, HPLC) during the vegetative period (May–October). Variation of their content during these months is discussed.
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    URL: http://dx.doi.org/10.1007/BF02269634
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    Rapid method for determination of phenylurea herbicides in milk (1994)
    Springer
    Chromatographia 38 (1994), S. 88-92 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenylurea herbicides ; Milk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed for the determination of thirteen phenylurea herbicide residues in milk. It involves one-step solvent extraction of the milk with methanol by ultrasonication. The extract is cleaned up on an Amberchrom resin cartridge. Reversed-phase, gradient elution, high-performance liquid chromatography with UV detection at 242 nm is used to analyse the residues. The recovery of thirteen phenylurea pesticides is quantitative, ranging from 71.4% to 97.9% for the individual herbicides investigated at concentrations around 0.05 mg kg−1 and from 65.1% to 95.6% around 0.005 mg kg−1. The method is not associated with any of the emulsion problems common to conventional solvent extraction, which considerably reduce the sample clean-up process compared with existing methods.
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    URL: http://dx.doi.org/10.1007/BF02275732
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    Lipid class analysis by normal phase high performance liquid chromatography, development and optimization using multivariate methods (1994)
    Springer
    Chromatographia 38 (1994), S. 317-324 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Lipid class analysis ; Experimental design and optimization ; Chemometrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A general method for the analysis of lipid classes by liquid chromatography has been developed using a multivariate optimization strategy to target optimal system conditions. The method was validated using a ruggedness test in the form of a Plackett-Burman design thereby exploring the immediate region around the optimum to ensure stable analytical conditions. Detection and quantitation were optimized by a factorial design in the light scattering detector parameters thus ensuring maximum detector response. This method was found to be suitable for a broad range of lipid sources from vegetable and animal origin, examples of the separation achieved are given for oat kernel, soybean and bovine milk lipids.
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    URL: http://dx.doi.org/10.1007/BF02269774
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    Determination of catecholamines as aminochromes by micellar liquid chromatography with thermal lens spectrophotometric detection (1994)
    Springer
    Chromatographia 38 (1994), S. 365-372 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid chromatography ; Determination of catecholamines ; Aminochromes ; Thermal lens spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The determination of catecholamines (CAs) using micellar liquid chromatography with thermal lens spectrophotometric detection has been studied. CAs are oxidized with hexacyanoferrate(III) to aminochromes which are separated with a mobile phase of 0.05 M sodium dodecyl sulphate, 7% propanol and 0.03 M citrate buffer, pH 4.8, on a partially endcapped C18 column. The aminochrome-micelles and aminochrome-stationary phase association constants are evaluated. Using the 488 nm line of an Ar+ laser with 250 mW pump power the limits of detection are about 4 ng mL−1. The technique is applied to the determination of unconjugated CAs in urine using isoproterenol as internal standard.
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    URL: http://dx.doi.org/10.1007/BF02269782
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    Control of adsorption and solubility in gradient high-performance liquid chromatography. Part 2: Sudden-transition gradient elution of styrene/ethyl methacrylate copolymers (1994)
    Springer
    Chromatographia 38 (1994), S. 559-565 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Copoly(styrene/ethyl methacrylate) ; Gradient elution, sudden transition ; Precipitation chromatography of polymers ; Solubility of polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Copolymers from styrene and ethyl methacrylate have been separated according to composition by methanol gradients on a cyanopropyl column after injection inton-heptane and a subsequent rapid increase of dichloromethane (DCM) concentration from zero to a constant value in the range from 10 to 40%. Retention and resolution in sudden-transition gradients increased with decreasing DCM concentration. The gradient rate was varied between 2.5 and 7.5%/min with optimum resolution at 2.5% min. At a level of 20% DCM and a gradient rate of 5%/min, the separation of a mixture of five copolymers in a sudden-transition gradient was the same as with the corresponding common gradient, i.e., with injection into a mixture ofn-heptane and 20% DCM. Elution was also achieved at a level of 20% DCM by continuous addition of tetrahydrofuran (THF) instead of methanol. With THF, the peaks appeared later than with methanol in spite of the fact that methanol is a non-solvent and THF a good solvent for the polymers investigated. This indicates that elution was, in the first instance, caused by the polarity of the eluent. The elution characteristics of the copolymers in the system heptane/methanol at constant DCM concentration were basically similar to the already known characteristics iniso-octane/methanol at constant THF concentrations.
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    URL: http://dx.doi.org/10.1007/BF02277154
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    Ligand-exchange chromatography of amino acid enantiomers and its application to the biotransformation of DL-aspartic acid byPseudomonas dacunhae (1994)
    Springer
    Chromatographia 39 (1994), S. 15-22 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand exchange ; Amino acid enantiomers ; DL-aspartic acid ; Pseudomonas dacunhae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the D and L enantiomers of eighteen essential α amino acids has been investigated by ligand-exchange chromatography (LEC). The effect of column temperature on the retention times and resolution of individual amino acid enantiomers has been studied by varying the temperature from 25 to 50 °C for a mobile phase containing Cu2+ ions. By use of a temperature of 50 °C and Zn2+ in the mobile phase, eight of the eighteen amino acid enantiomers can be resolved sufficiently well for practical application. Only phenylalamine, tyrosine, and tryptophan can be separated by use of Ni2+ as complexation metal at 50 °C. LEC has been used to monitor the decarboxylation of racemic DL-aspartic acid byPseudomonas dacunhae. Analysis of DL amino acid enantiomers in different media was performed at column temperatures of 30 and 50°C by addition of 0.125 mM Cu2+ to the aqueous mobile phase. It was found that the analytical performance is most dependent on the identity of the metal used for complexation; the concentration of the metal was of secondary importance and the column temperature less important still.
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    Retention and selectivity of aromatic hydrocarbons with mono-substituted polar groups in ternary RP-HPLC systems (1994)
    Springer
    Chromatographia 39 (1994), S. 67-70 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase systems ; Ternary eluents ; Mono-substituted aromatics ; Retention and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The variation in selectivity for aromatic hydrocarbons with mono-substituted polar groups is investigated in ternary mobile-phase systems on C18 stationary phases. The dependence of log k′ on the proportions of two modifiers was determined for the solutes within the concentration range of ternary systems obtained by mixing two binary eluents: methanol + water and tetrahydrofuran + water or acetonitrile + water and tetrahydrofuran + water. The nature of the relationships is explained in terms of molecular shape, molecular interactions between solute and extracted modifier and the ordering of solvated ligands on the stationary phase.
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    The simultaneous determination of L-697, 661, a HIV-1 specific reverse transcriptase inhibitor, and its 6-hydroxy metabolite in human plasma via column-switching high performance liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 79-84 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; HIV type 1 reverse transcriptase inhibitor ; Acquired immune deficiency syndrome ; L-697, 661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the determination of L-697, 661, a human immunodeficiency virus type 1 reverse transcriptase inhibitor, and its 6-hydroxy metabolite in plasma is described. Following analyte isolation via solid phase extraction, samples are analyzed by HPLC using a column switching system. Column switching allows each analyte to be simultaneously analyzed under isocratic reverse phase conditions in a run time of 21 minutes. The assay was linear in the concentration range of 10–500 ng/mL for each analyte when 1 mL aliquots of plasma were extracted. The assay has been fully validated and utilized for human pharmacokinetic studies.
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    URL: http://dx.doi.org/10.1007/BF02320463
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    Reversed phase behaviour of high molecular mass polystyrenes in ethyl acetate solvent mixtures (1994)
    Springer
    Chromatographia 39 (1994), S. 663-667 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polystyrene ; Ethyl acetate ; Dichloromethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reversed phase behaviour of high molecular mass polystyrenes was investigated on C18 bonded phase columns with ethyl acetate-methanol and ethyl acetateacetonitrile mobile phases. The results are compared with the corresponding dichloromethane mobile phases. The ethyl acetate-methanol mobile phase showed anomalous elution behaviour, similar to other previously investigated solvent combinations with methanol. The ethyl acetate-acetonitrile mobile phase showed no anomalous behaviour, increased retention and, elution over a wider composition range compared with the dichloromethane-acetonitrile system. However, resolution between adjacent molecular masses was considerably worse.
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    Simultaneous quantitative measurement of a new platelet activating factor antagonist (BN 50730) and its two main metabolites in human plasma and urine by LC-MS (1994)
    Springer
    Chromatographia 39 (1994), S. 228-238 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; LC/MS coupling ; Particle Beam interface ; Plasma and urine samples ; BN50730 and its metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and sensitive assay has been developed for the quantitative measurement of a new platelet activating factor antagonist (BN50730), and its two main metabolites (BN50727 and BN50922), at the picomole level in human plasma and urine. The three compounds of interest and the internal standard (BN50765) were measured by combined LC-negative chemical ionization MS. A simple solid-liquid extraction procedure was used to isolate the parent drug and the two metabolites. The MS was tuned to monitor the intense ionm/z 333 generated in the ion source by a dissociative capture process. The assay was on 1 ml plasma or 0.1 ml urine and the quantitation limit was calculated as 1 ng·ml−1. The very low relative standard deviations and mean percentages of error calculated for within-day or between-day repeatability assays demonstrate the ruggedness of the technique for routine determination in biological fluids. Some preliminary results on the pharmacokinetics of the parent drug and its two main metabolites illustrate the applicability of this method.
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    URL: http://dx.doi.org/10.1007/BF02274505
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    Generation of split-flow micro-gradients for capillary HPLC (1994)
    Springer
    Chromatographia 39 (1994), S. 279-284 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary columns for LC ; Micro-gradient generation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The generation of a micro-gradient for micro HPLC capillary columns is described. The system used is a modified and improved version of a split flow gradient elution device. Gradient tests have been performed and have shown good reproducibility under all conditions. The system has been successfully coupled with a particle beam LC-MS interface and the analysis of a mixture of twenty seven basic or neutral pesticides is reported.
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    URL: http://dx.doi.org/10.1007/BF02274514
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    Salt effects in anion exchange displacement chromatography: Comparison of pentosan polysulfate and dextran sulfate displacers (1994)
    Springer
    Chromatographia 39 (1994), S. 409-418 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-exchange chromatography ; Protein purification ; Pentosan polysulfate displacers ; Dextran sulfate displacers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Experimental studies were carried out to investigate the utility of pentosan polysulfate as a low molecular weight polyelectrolyte displacer for the purification of proteins in anion-exchange displacement systems. In addition, the influence of mobile phase salt concentration on displacer efficacy, protein-protein resolution, and displacement development were studied for several anionic displacers. It was found that while large polyelectrolytes (50 kd dextran sulfate) were efficient displacers for a wide range of salt concentrations, relatively small polyelectrolytes (3 kd pentosan polysulfate) were seen to act as an efficient displacer only under conditions of high salt micro-environments. In addition, for proteins exhibiting similar affinities, zone mixing at the protein-protein boundary was found to be quite sensitive to the salt concentration. Finally, displacement chromatography was successfully implemented for the separation of proteins from milk whey.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278755
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    Separation of chlamydosporol epimers by reversed-phase HPLC using commercial solvent optimisation software (1994)
    Springer
    Chromatographia 39 (1994), S. 443-447 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mycotoxins ; Chlamydosporol epimers ; Solvent optimisation ; Fusarium species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two epimers of the mycotoxin chlamydosporol were separated by HPLC on an RP-18 column using a quaternary mobile phase consisting of water (79.1%), methanol (10.0%), acetonitrile (10.4%) and tetrahydrofuran (0.5%), with a flow rate of 1 ml min−1. This optimal composition of mobile phase, with which the resolution value for the two epimers (1 and2) was 2.73 with retention times of 5.88 and 7.12 min, respectively, was achieved by the application of Philips Solvent Optimisation Software PU 6100. The presence of free silanols on the stationary phase was shown to be an essential requirement for the separation of the chlamydosporol epimers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278760
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    Determination of tacrolimus (FK 506) in whole blood using liquid chromatography and fluorescence detection (1994)
    Springer
    Chromatographia 39 (1994), S. 490-496 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Precolumn derivatization ; Dansylhydrazine ; Fluorescence detection ; Tacrolimus (FK 506) in blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and selective liquid chromatographic method, using precolumn derivatization with dansylhydrazine followed by fluorescence detection, has been developed for the determination of tacrolimus (FK 506) in whole blood. After haemolysis, whole blood samples are extracted with diethyl ether and derivatized. After on-line removal of excess dansylhydrazine on a C18 precolumn, the derivative is loaded on to a C18 clean-up column, and a heart cut is subsequently transferred to a graphitized carbon column, where the final separation takes place. The method requires 1 ml of sample and has a limit of quantitation of 3 ng/ml. At the 15 ng/ml level the precision isca 10%, and the response is linear from the limit of quantitation toca 200 ng/ml of FK 506 in whole blood. The capacity of the method is 50 samples/day and about 1000 1-ml samples can be analyzed without changing either clean-up or separation column. Finally, the applicability of the method for therapeutic drug monitoring is shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278767
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  • 190
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    Spectroscopic studies of butylphenyl, mono-ol and perfluorinated bonded phases (1994)
    Springer
    Chromatographia 39 (1994), S. 520-528 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; New bonded phases ; 13C and29Si CP-MAS NMR ; DRIFT ; ESCA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A variety of olefins were bonded to silaceous supports through a hydride modified substrate. The products were then examined by13C and29Si solid state-NMR with cross-polarization (CP) and magic angle spinning (MAS). Information about the surface was also obtained by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and the related photoelectron spectroscopic technique (ESCA). Carbon analysis on bonded silicas was carried out and surface coverage was calculated. Confirmation of the organic groups bound to the silica support was possible. The hydride intermediate is shown to be a versatile material for bonding a wide variety of organic moieties to silica surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268274
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  • 191
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    Analysis of isomers of cholesteryl acetate hydroperoxides by HPLC and GC-ITDMS (1994)
    Springer
    Chromatographia 39 (1994), S. 577-580 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography-mass spectrometry ; Column liquid chromatography ; Cholesteryl acetate ; Hydroperoxide formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic, high performance liquid chromatographic and GC-ion trap detector mass spectrometric analyses of the hydroperoxides formed during thermal peroxidation of cholesteryl acetate, are reported and discussed. The hydroperoxides were separated from the thermal-oxidised mixture by solid-phase extraction, fractionated and individually collected by HPLC. Each hydroperoxide was then chemically reduced with NaBH4 to a hydroxy-derivative. The GC and MS characteristics of hydroxy- and TMS-derivatives were compared against available standards. Only 7β-hydroperoxide and 7α-hydro-peroxide of cholesteryl acetate were found, as reported in the literature for cholesterol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268282
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  • 192
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    Retention behavior of aromatic hydrocarbons in reversed-phase liquid chromatography with ion-exchange-induced stationary phases (1994)
    Springer
    Chromatographia 39 (1994), S. 597-601 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-exchange-induced stationary phase ; Retention behavior ; Aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behavior of aromatic hydrocarbons on anion-exchangers modified with alkylsulfate or alkanesulfonate has been examined by column liquid chromatography. Several parameters affected the retention of analytes, involving concentration of the modifier in the mobile phase, its alkyl chain length and mobile phase composition. Stationary phases modified with a reagent having longer alkyl chains achieved better column efficiency. The separation factor achieved on ion-exchange-induced stationary phases foro-terphenyl and triphenylene was larger than that on alkyl-bonded silica gel.
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    URL: http://dx.doi.org/10.1007/BF02268286
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  • 193
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    Application of liquid chromatography-particle beam mass spectrometry and gas chromatography-mass spectrometry for the identification of metabolites of polycyclic aromatic hydrocarbons (1994)
    Springer
    Chromatographia 38 (1994), S. 781-788 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Particle beam MS detection ; Polycyclic aromatic metabolites ; Biodegradation in water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two liquid chromatography-particle beam mass spectrometry (LC-PBMS) systems have been used for analysis of polycyclic aromatic hydrocarbon metabolites in water samples from a biological decomposition model experiment. The results were compared with those obtained by classical gas chromatography-mass spectrometry. Evaluation of spectral data indicated the presence of six main metabolites; 1H,3H-naphtho [1,8-cd]pyran-1,3-dione, 1-(hydroxymethyl)naphthalene, and 1,2-acenaphthenedione were identified by use of standard substances and spiking experiments. Enrichment of the investigated water samples with online pre-column (C18) concentration, freeze-drying, and solvent extraction led to similar results with only slight differences. The application of microbore separation columns proved to be a promising tool in particle beam LC-MS measurements.
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    URL: http://dx.doi.org/10.1007/BF02269637
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  • 194
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    Efficiency of porous hydrophilic polymer-based packing materials in chromatographic analysis of drugs existing with polypeptide (1994)
    Springer
    Chromatographia 38 (1994), S. 177-182 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrophilic polymer-based packing material ; Direct injection of serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A size monodispersed restricted-access polymeric packing material has been prepared through a simple and easy one-step method of co-polymerization of glycerol monomethacrylate and glycerol dimethacrylate with cyclohexanol as prorogen. A typical seeded polymerization (two step swelling and polymerization method) in an aqueous medium gave a 90 % yield of porous beads which could be utilized as a packing material in high performance liquid chromatography (HPLC) without any size classification due to the excellent size monodispersity. A BET measurement and size exclusion chromatography in either tetrahydrofuran or water revealed that the prepared material had only small pores (around 100 Å in diameter). It showed ample hydrophobicity for the separation of hydrophilic drug molecules in 10% aqueous acetonitrile buffer, while polypeptides such as bovine serum albumin were excluded and eluted before the void volume of the column with quantitative recovery.
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    URL: http://dx.doi.org/10.1007/BF02290333
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    Selective and sensitive analysis of 1-nitropyrene in diesel exhaust particulate extract by multidimensional HPLC (1994)
    Springer
    Chromatographia 38 (1994), S. 199-206 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nitro-PAHs ; Diesel particulate extract ; Column switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A multicolumn (MC) HPLC method for the determination of 1-nitropyrene (1-NP) at trace-levels via on-line reduction to 1-aminopyrene and fluorescence detection is presented. On the first column, packed with a pyrenebutyric acid amide stationary phase, the nitro-derivatives of PAHs are strongly retained and separated from other matrix components. The nitro-PAHs-containing fractions are transferred onto a RP18-column via stepwise gradient elution and finally separated according to their various lipophilicities and sizes. To increase the overall selectivity and sensitivity of the multidimensional method (MD-HPLC system) post-column, on-line reduction of the nitro-PAHs to the respective amino-PAHs via a short catalysis column is performed thus enhancing the sensitivity significantly (to low pg levels). The applicability of this method for the determination of trace amounts of 1-NP in real samples (diesel particulate extracts) is demonstrated.
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    URL: http://dx.doi.org/10.1007/BF02290337
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    Molecular shape recognition capability of liquid-crystal bonded phases in reversed-phase high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 295-303 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Liquid crystal phases ; Molecular shape recognition ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic retention behaviour of two liquidcrystal bonded phases have been evaluated using polycyclic aromatic hydrocarbons (PAHs) as the probe samples in reversed-phase high performance liquid chromatography (RP-HPLC). The results clearly indicate that these phases have better planarity and shape recognition capabilities than commercially-avaialble polymeric octadecylsilica (ODS) phases whose strong planarity and shape selectivities were found earlier. It can also be concluded from the chromatographic observations that the shape recognition capability of these phases is dependent on both mobile phase composition and column temperature, but that the effect of mobile phase and temperature on the shape selectivity work independently. The retention behaviour can be explained by changes in the phase structure with changes of eluent composition and temperature.
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    URL: http://dx.doi.org/10.1007/BF02269771
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  • 197
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    In-line derivatization method for fluorometric determination of catecholamines by high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 591-594 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; In-line derivatization ; Fluorometric determination ; Catecholamines in urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fluorometric method has been developed for the determination of norepinephrine, epinephrine and dopamine by high-performance liquid chromatography. Catecholamines extracted from urine were separated by reversed-phase chromatography with an alkaline mobile phase (pH 8.0, 20 mM sodium tetraborate containing 30 mM 1-butaneboronic acid) and were fluorometrically detected (Ex 400 nm and EM 475 nm) via in-line derivatization at high temperature (100 °C). Retention times for norepinephrine, epinephrine, dopamine and isoproterenol as an internal standard were 8, 10, 13 and 28 min, respectively. Calibration curves for these compounds were linear from 4 to 100 ng/ml standard solution. The detection limit (signalto noise ratio=3) for norepinephrine, epinephrine and dopamine was 0.1, 0.2 and 0.8 ng. The assay of catecholamines in human urine is also described.
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    URL: http://dx.doi.org/10.1007/BF02277159
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    Determination of glutathione in pharmaceuticals and cosmetics by HPLC with UV and fluorescence detection (1994)
    Springer
    Chromatographia 39 (1994), S. 23-28 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glutathione ; Pharmaceuticals and cosmetics ; Pre-chromatographic derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A selective HPLC determination of reduced glutathione (GSH) in pharmaceutical and cosmetic formulations is described based on prechromatographic derivatization with 4-(6-methylnaphthalen-2-yl)-4-oxo-2-buteneoic acid. The derivatization reaction is rapid under mild reaction conditions (10 min at ambient temperature and pH 7.5) and the excess reagent can be removed by liquid-liquid extraction. The thiol adducts were chromatographed on a C-8 column using 0.05 M triethylammonium phosphate (pH 4.0) — acetonitrile 68∶32 (v/v), as the mobile phase; UV and fluorescence detection (lem 450 nm, lexc 300 nm) were both used. The structure of the thiol adducts was confirmed by1H and13C NMR spectra using sodium methanethiolate as thiol nucleophile.
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    URL: http://dx.doi.org/10.1007/BF02320453
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  • 199
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    Retention parameters of aromatic hydrocarbons with mono-substituted polar groups in binary RP-HPLC systems (1994)
    Springer
    Chromatographia 39 (1994), S. 51-61 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase systems ; Binary eluents ; Mono-substituted aromatics ; Retention and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capacity factor (k′) values of aromatic hydrocarbons with mono-substituted polar-groups are correlated for reversed-phase systems involving stationary phases with C18 or C4 ligands chemically bonded to silica and a binary aqueous eluent containing modifiers: methanol, acetonitrile, tetrahydrofuran, isopropanol, dioxane or dimethoxyethane. The relative retention variations of the solutes are interpreted with special consideration of their interactions with non-polar stationary phases and the molecular structure of the modifiers and solutes. Rules for retention and selectivity optimisation in RP-HPLC systems are given.
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    URL: http://dx.doi.org/10.1007/BF02320458
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    System peaks in single column ion chromatography (SCIC) with indirect spectrophotometric detection (1994)
    Springer
    Chromatographia 39 (1994), S. 713-718 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; System peaks ; Indirect detection ; Anions and cations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The most popular eluents for SCIC are organic acids and their salts with one or more kinds of ion taking part in the elution process. These ions compete for ion-exchange equilibria. After an injection, the equilibria are disturbed and a re-equilibration process occurs resulting in extraneous peaks (system peak). A mechanism based on these aspects is proposed which is used successfully in the interpretation of the effects of sample properties and eluent parameters on system peaks. Experiments in the analysis of both cations and anions have been carried out to support this mechanism with eluents comprising two kinds of eluent ions. An equation for capacity factors in such systems is also derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274588
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