F. Else C. Sneller

VU University Amsterdam, Amsterdamo, North Holland, Netherlands

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Publications (7)22.83 Total impact

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    ABSTRACT: Cadmium (Cd) is a nonessential heavy metal that can be harmful at low concentrations in organisms. Therefore, it is necessary to decrease Cd accumulation in the grains of wheats aimed for human consumption. In response to Cd, higher plants synthesize sulphur-rich peptides, phytochelatins (PCs). PC–heavy metal complexes have been reported to accumulate in the vacuole. Retention of Cd in the root cell vacuoles might influence the symplastic radial Cd transport to the xylem and further transport to the shoot, resulting in genotypic differences in grain Cd accumulation. We have studied PC accumulation in 12-day-old seedlings of two cultivars of spring bread wheat (Triticum aestivum), and two spring durum wheat cultivars (Triticum turgidum var. durum) with different degrees of Cd accumulation in the grains. Shoots and roots were analysed for dry weight, Cd and PC accumulation. There were no significant differences between the species or the varieties in the growth response to Cd, nor in the distributions of PC chain lengths or PC isoforms. At 1 μM external Cd, durum wheat had a higher total Cd uptake than bread wheat, however, the shoot-to-root Cd concentration ratio was higher in bread wheat. When comparing varieties within a species, the high grain Cd accumulators exhibited lower rates of root Cd accumulation, shoot Cd accumulation, and root PC accumulation, but higher shoot-to-root Cd concentration ratios. Intraspecific variation in grain Cd accumulation is apparently not only explained by differential Cd accumulation as such, but rather by a differential plant-internal Cd allocation pattern. However, the higher average grain Cd accumulation in the durum wheats, as compared to the bread wheats, is associated with a higher total Cd accumulation in the plant, rather than with differential plant-internal Cd allocation. The root-internal PC chain length distributions and PC–thiol-to-Cd molar ratios did not significantly differ between species or varieties, suggesting that differential grain Cd accumulation is not due to differential PC-based Cd sequestration in the roots.
    Environmental and Experimental Botany 02/2003; DOI:10.1016/S0098-8472(02)00045-X · 3.00 Impact Factor
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    ABSTRACT: Phytochelatins (PCs) are a family of thiol-rich peptides, with the general structure (gamma-Glu-Cys)(n)()-Gly, with n = 2-11, induced in plants upon exposure to excessive amounts of heavy metals and some metalloids, such as arsenic. Two types of PC analyses are currently used, i.e., acid extraction and separation on HPLC with either precolumn derivatization (pH 8.2) with monobromobimane (mBBr) or postcolumn derivatization (pH 7.8) with Ellman's reagent [5, 5'-dithiobis(2-nitrobenzoic acid), DTNB]. Although both methods were satisfactory for analysis of Cd-induced PCs, formation of (RS)(3)-As complexes during extraction of As-induced PCs rendered the DTNB method useless. This paper shows that precolumn derivatization with mBBr, during which the (RS)(3)-As complexes are disrupted, provides a qualitative and quantitative analysis of both Cd- and As-induced PCs. In addition, derivatization efficiencies of both methods for the oligomers with n = 2-4 (PC(2)(-)(4)) are compared. Derivatization efficiency decreased from 71.8% and 81.4% for mBBr and DTNB derivatization, respectively, for PC(2) to 27.4% and 50.2% for PC(4). This decrease is most likely due to steric hindrance. Correction of measured thiol concentration is therefore advised for better quantification of PC concentrations in plant material.
    Journal of Agricultural and Food Chemistry 10/2000; 48(9):4014-9. · 3.11 Impact Factor
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    ABSTRACT: Phytochelatins (PCs) are a family of thiol-rich peptides, with the general structure (gamma-Glu-Cys)(n)-Gly, with n = 2-11, induced in plants upon exposure to excessive amounts of heavy metals and some metalloids, such as arsenic. Two types of PC analyses are currently used, i.e., acid extraction and separation on HPLC with either precolumn derivatization (pH 8.2) with nronobromobimane (mBBr) or postcolumn derivatization (pH 7.8) with Ellman's reagent [5,5'-dithiobis(2-nitrobenzoic acid), DTNB]. Although both methods were satisfactory for analysis of Cd-induced PCs, formation of (RS)(3)-As complexes during extraction of As-induced PCs rendered the DTNB method useless. This paper shows that precolumn derivatization with mBBr, during which the (RS)(3)-As complexes are disrupted, provides a qualitative and quantitative analysis of both Cd- and As-induced PCs. In addition, derivatization efficiencies of both methods for the oligomers with n = 2-11 (PC2-4) are compared. Derivatization efficiency decreased from 71.8% and 81.4% for mBBr and DTNB derivatization, respectively, for PC2 to 27.4% and 50.2% for PC4. This decrease is most likely due to steric hindrance. Correction of measured thiol concentration is therefore advised for better quantification of PC concentrations in plant material.
    Journal of Agricultural and Food Chemistry 09/2000; 48(9):4014-4019. DOI:10.1021/jf9903105 · 3.11 Impact Factor
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    ABSTRACT: The mixture effects of arsenate and cadmium were studied in Silene vulgaris (Moench) Garcke. The results show that the toxicity of the mixtures, measured as inhibition of root elongation, increased with increasing concentrations, ranging from nonadditive or slightly additive to synergistic. The elements did not influence each other's uptake. This was as expected, considering the differences in uptake mechanisms between both elements. Concentrations of detoxifying phytochelatins (PCs) were additive, with respect to both external and root-internal metal concentrations. However, at high exposure concentrations, the plants metabolism collapsed, resulting in very low PC concentrations.
    Environmental Toxicology and Chemistry 01/2000; 19(12):2982 - 2986. DOI:10.1002/etc.5620191219 · 2.83 Impact Factor
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    ABSTRACT: The results presented in this paper describe the short- and long-term toxicity of arsenate in Silene vulgaris. Short-term toxicity, measured as inhibition of root elongation, depended on phosphate nutrition, arsenate being much less toxic at high phosphate supply. At low phosphate levels more arsenic was taken up by the plants. Under chronic exposure, toxicity (measured as inhibition of biomass production) did not increase with time. In addition, the accumulation of phytochelatins (PCs) as a function of toxicity and duration of exposure was studied. Short-term PC accumulation (over a 3 d period) was positively correlated with exposure. Isolation of peptide complexes from prolongedly exposed plants showed that PC2, PC3 and PC4 were present, although the latter not until at least 3 d exposure. Arsenic co-eluted mainly with PC2 and PC3. Fractions containing PC4 were devoid of As, probably due to dissociation of the complexes during extraction or elution. The breakdown of PCs after arresting As exposure was very slow. This could explain the continuous accumulation of PCs throughout longer periods of As exposure.
    New Phytologist 10/1999; 144(2):223 - 232. DOI:10.1046/j.1469-8137.1999.00512.x · 6.55 Impact Factor
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    ABSTRACT: Phytochelatins (PCs) are known to detoxify heavy metals in plants. This study aimed to investigate the possibility of using PCs as a biomarker for chronic Cd toxicity in Silene vulgaris. For this purpose, the effects of Cd on growth rate, related to plant weight, and the PC concentrations were recorded throughout the bigger part of the vegetative phase. The lowest concentrations of Cd used, 1 and 2 M, inhibited plant growth rates by 30 and 50%, respectively, independent of the weight of the exposed plants. Above an exposure concentration of 2 M Cd, the toxic effect increased with plant weight. At 3.5 M Cd, the plant growth rates were inhibited up to 90%. Further increases of the exposure concentration did not produce additional inhibition. Root PC concentrations correlated with growth inhibition only at the lower Cd concentrations, i.e. up to 2 M Cd. Above this concentration the correlation was lost.
    Ecotoxicology 05/1999; 8(3):167-175. DOI:10.1023/A:1026440213649 · 2.50 Impact Factor
  • Biologia Plantarum 01/1994; 36(1). DOI:10.1007/BF02931126 · 1.74 Impact Factor