Lanthanum- and cerium-induced oxidative stress in submerged Hydrilla verticillata plants

Shandong University of Technology College of Life Science Zibo 255049 China
Russian Journal of Plant Physiology (Impact Factor: 0.62). 01/2007; 54(5):693-697. DOI: 10.1134/S1021443707050184

ABSTRACT Oxidative stress was induced in 10-day treated with lanthanum and cerium Hydrilla verticillata plants. Low 10 μM concentrations did not exert harmful effects. The plants treated with higher concentrations showed higher
H2O2 content and lower chlorophyll and soluble protein contents as compared to control plants. At the same time, malondialdehyde
content rose with increasing concentrations of La and Ce. As La and Ce concentrations increased, superoxide dismutase and
catalase activities declined progressively, while peroxidase activity increased. Proline content decreased slightly at 10
μM La or Ce and then rose with higher concentrations. The results indicated that La and Ce caused oxidative damage as evidenced
by increased lipid peroxidation and decreased chlorophyll and protein levels.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cerium is one of the most abundant rare earth elements (REE) with an estimated average concentration in the Earth's crust of 66 μg g-1, which is equal to or greater than Ni and Pb. Hydroponic experiments were performed to examine the rhizotoxicity of Ce to cucumber (Cucumis sativa) seedlings and the effects of H+ and Ca2+ were also studied. Ce concentration that causes 50 % reduction in root elongation (IC50) was calculated and the values ranged from 0.29 μM at pH 6.0 with 0.20 mM Ca to > 2.0 μM at pH 4.5 with 2.00 mM Ca. Column leaching experiments were conducted and the partitioning coefficients (Kd) were calculated. Total metal concentrations in soils were measured before and after spiking and metal concentrations in soil solution (leachates) were also measured during 9 days of spiking and leaching. The results suggest that leaching is an important step after spiking soils in order to remove excess dissolved metals. Large Kd values indicate that Ce is strongly bound to soil particles and that the bioavailable Ce could be much lower than the total Ce. Phytotoxicity of Ce was examined by performing pot experiments. Cucumbers were grown in Ce-spiked soils for 14 days and a dose-response relationship was established. The results from the pot experiments suggest that Ce toxicity is similar to Zn and Ni with the IC50 ranging from 100 μg g-1 Ce for root growth to 2630 μg g-1 Ce for biomass. Bioaccumulation of Ce was also observed in Cucumis sativa, however, most Ce was found in the root and much less Ce was transferred to the leaf. Le cerium est un des éléments des terres-rares les plus abondants dans la croûte terrestre, sa concentration moyenne estimée est de 66 μg g-1, ce qui le rend comparable aux concentrations de Ni et ou de Pb. Des expériences en hydroponique ont été poursuivies pour étudier, sur les pousses de concombres (Cucumis sativa), les effets du pH et de la concentration du Ca sur la rhizotoxicité du Ce. La concentration de Ce qui occasionne 50% de réduction de la longueur des racines (IC50) a été établie comme passant de 0,29 uM Ce à pH 6 avec 0,20 mM Ca pour aller jusqu'à > 2 uM Ce à pH 4,5 avec 2,0 mM Ca. Des études de lessivage de colonnes ont été entreprises et les coefficients de partition (Kd) ont été calculés. Les concentrations de totales de métaux ont été mesurées avant et après l'addition de Ce et les concentrations dans les solutions de sol (lessivats) ont été enregistrées pour une durée de 9 jours. Les résultats montrent que le lessivage est une étape importante après avoir ajouté l'élément au sol de manière à enlever l'excès de métal qui est resté en solution après l'ajout initial. La valeur élevée des coefficients de partition (Kd) indique que beaucoup de Ce est fortement adsorbé sur la phase solide en comparaison avec ce qui se trouve en solution; ce qui expliquerait que le Ce biodisponible est bien moindre que le Ce total. La phytotoxicité du Ce a été étudiée lors d'une expérience en pots de culture. Les concombres ont été cultivés durant 14 jours dans des sols enrichis en Ce et leur réponse en fonction de la concentration présente a été établie. Les résultats de cette expérience en pots suggèrent que la toxicité du Ce est semblable à celle du Zn et Ni passant de 100 μg g-1 pour la croissance des racines à 2630 μg g-1 pour la biomasse. La bioaccumulation dans le plant de concombre a été observée mais la plupart du Ce mesuré l'a été dans les racines et beaucoup moins a été transféré dans l'appareil végétal.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Increasing amounts of lanthanum (La) is released into aquatic environments. However, little information is available on the influence of La on aquatic plants. In this study, physiological and ultrastructural responses of Hydrocharis dubia (Bl.) Backer leaves to elevated concentrations of La (up to 160 μM) were investigated. The accumulation of La was found to be increased in a concentration-dependent manner. La disturbed the intrinsic balance of nutrient elements (P, Mg, Ca, Fe, K, and Zn). Pigment content decreased with the rise of the La concentrations and the EC(50) value for chlorophyll was 20 μM on day 7. The antioxidants (superoxide dismutase, peroxidase, catalase, reduced ascorbate, and reduced glutathione) exhibited varied response to the La treatments. Malondialdehyde content enhanced gradually at all La concentrations. The enhancement in proline content was found in a concentration-dependent manner. The amounts of three polypeptides with apparent molecular weights of 61.9, 51.5, and 16.7 kDa, respectively, were gradually diminished, as well as one existing polypeptides with apparent molecular weight of 22.3 kDa, elevating in response to increasing La concentrations. Significant damage to the chloroplast, mitochondrion, and nucleus was imposed by La indicated a general disarray in the cellular functions. The negative effects of La on H. dubia unequivocally indicate that La could exert an adverse influence on aquatic ecosystem and should lead to a more careful discharge of such elements into water environment.
    Environmental Science and Pollution Research 05/2012; 19(9):3950-8. · 2.76 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to investigate the effects of rare earth elements (REEs) on horseradish, the distribution of the mineral elements and heavy metals in different organs of horseradish have been studied by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Meanwhile, three variable major parameters, namely the concentration of REEs, the type of REEs, and the growth stage of plant were chosen. The results indicated that the test REEs, Ce(III) and Tb(III), could be accumulated in leaves, stems and roots of horseradish. In addition, we found that the content of mineral elements was increased in horseradish treated with 20mgl(-1) of Ce(III), but not those with the 20mgl(-1) of Tb(III). Moreover, the content of mineral elements in horseradish was decreased with the increasing concentration of REEs (100, 300mgl(-1)). Furthermore, we found that there were the opposite effects on the content of the heavy metals in horseradish treated with REEs. Finally, we found that the effect of REEs on the accumulation of REEs, and the content of mineral elements or heavy metals of horseradish during vigorous growth stage, no matter positive or negative, was more obvious than that of the other growth stages. These results demonstrated that the distribution behaviors of mineral elements and heavy metals in horseradish can be affected by the type and concentration of REEs, and the growth period of plant.
    Chemosphere 09/2008; 73(3):314-9. · 3.14 Impact Factor