Comparative ecotoxicity of three polluted industrial soils for the Collembola Folsomia candida

We tried to quantify the ecotoxicity of three industrial soil samples contaminated by different metals, using the Collembolan Folsomia candida as a biological model and mortality, growth and reproduction as parameters. The observed ecotoxicities are rather normal for the first such soil sample (aluminum factory) but are high for the second sample (ore treatment) and relatively low for the third one (zinc factory) considering its high metal concentrations. For these last two soil samples, an unusual ecotoxicity plotting is observed: two high ecotoxicity recordings fit with a low and high percentage of polluted soil to non-polluted soil and noticeably lower ecotoxicity recordings are observed between them. Chemical analyses of metals in pore waters show that arsenic probably explains part of such an unusual ecotoxicity curve. Otherwise, mortality and growth of the animals are less sensitive parameters than reproduction. Our experiments show that the results of the ecotoxicological assays of polluted soils are complex and difficult to interpre

Lead-induced DNA damage in Vicia faba root cells: Potential involvement of oxidative stress

Genotoxic effects of lead (0–20 µM) were investigated in whole-plant roots of Vicia faba L., grown hydroponically under controlled conditions. Lead-induced DNA damage in V. faba roots was evaluated by use of the comet assay, which allowed the detection of DNA strand-breakage and with the V. faba micronucleus test, which revealed chromosome aberrations. The results clearly indicate that lead induced DNA fragmentation in a dose-dependant manner with a maximum effect at 10 µM. In addition, at this concentration, DNA damage time-dependently increased until 12 h. Then, a decrease in DNA damages was recorded. The significant induction of micronucleus formation also reinforced the genotoxic character of this metal. Direct interaction of lead with DNA was also evaluated with the a-cellular comet assay. The data showed that DNA breakages were not associated with a direct effect of lead on DNA. In order to investigate the relationship between lead genotoxicity and oxidative stress, V. faba were exposed to lead in the presence or absence of the antioxidant Vitamin E, or the NADPH-oxidase inhibitor dephenylene iodonium (DPI). The total inhibition of the genotoxic effects of lead (DNA breakage and micronucleus formation) by these compounds reveals the major role of reactive oxygen species (ROS) in the genotoxicity of lead. These results highlight, for the first time in vivo and in whole-plant roots, the relationship between ROS, DNA strand-breaks and chromosome aberrations induced by lead

Effect of Calcium Deficiency on Growth and Leaf Acid Soluble Proteins of Tomato

The effects of temporary Ca (Ca) calcium deficiency lasting 2, 3, 4 or 5 d were investigated on tomato plants at the 6-leaf stage, grown hydroponically under controlled conditions. With 2, 3 or 4 d of Ca deficiency, the dry weight of the tomato leaves, shoots or roots was not different from control. A significant decrease in tomato growth, of up to 70%, appeared on the fifth day. Some visual symptoms were observed on the tomato leaves. The phenomenon concerned was an irreversible mechanism that led to plant death after 12 d, even when Ca was added to the root medium after 2, 3, 4 or 5 d. This is the first report of such a rapid and drastic effect of an essential macronutrient. Moreover, Ca content in leaves during root deprivation showed a decrease in all plants, related to a remobilization toward the apex. Ca could be considered as a partly mobile element: the observation of the youngest leaf limbs by transmission electronic microscopy after 4 d of treatment showed disorganized tissues in a necrotic zone, due to wall impairment related to C deficiency. During temporary Ca deficiency, acid soluble proteins were analyzed in leaves (SDS PAGE electrophoresis / Maldi-TOF). After 4 d of Ca deficiency, protein induction in young leaves was revealed. Three proteins were identified as pathogenesis related proteins (PR-1, PR-3, PR-7) and a threonine deaminase precursor was also found. It was also the first time that pathogenesis related (PR) protein appearance has been shown to be related to Ca deficiency. The PR proteins are generally elicited by pathogen attack. This phenomenon seems to be calcium dependent because other mineral stresses, such as potassium (K) deficiency or sodium (Na) excess, did not reveal acid soluble protein changes. The retranslocation of Ca to young tissue could entail eliciting effects via wall fragments leading to a plant response similar to the response to pathogen attac

Lead Uptake, Toxicity, and Detoxification in Plants

Lead has gained considerable attention as a persistent toxic pollutant of concern, partly because it has been prominent in the debate concerning the growing anthropogenic pressure on the environment. The purpose of this review is to describe how plants take lead up and to link such uptake to the ecotoxicity of lead in plants. Moreover, we address the mechanisms by which plants or plant systems detoxify lead. Lead has many interesting physico-chemical properties that make it a very useful heavy metal. Indeed, lead has been used by people since the dawn of civilization. Industrialization, urbanization, mining, and many other anthropogenic activities have resulted in the redistribution of lead from the earth’s crust to the soil and to the environment. Lead forms various complexes with soil components, and only a small fraction of the lead present as these complexes in the soil solution are phytoavailable. Despite its lack of essential function in plants, lead is absorbed by them mainly through the roots from soil solution and thereby may enter the food chain. The absorption of lead by roots occurs via the apoplastic pathway or via Ca2+-permeable channels. The behavior of lead in soil, and uptake by plants, is controlled by its speciation and by the soil pH, soil particle size, cation-exchange capacity, root surface area, root exudation, and degree of mycorrhizal transpiration. After uptake, lead primarily accumulates in root cells, because of the blockage by Casparian strips within the endodermis. Lead is also trapped by the negative charges that exist on roots’ cell walls. Excessive lead accumulation in plant tissue impairs various morphological, physiological, and biochemical functions in plants, either directly or indirectly, and induces a range of deleterious effects. It causes phytotoxicity by changing cell membrane permeability, by reacting with active groups of different enzymes involved in plant metabolism and by reacting with the phosphate groups of ADP or ATP, and by replacing essential ions. Lead toxicity causes inhibition of ATP production, Lead Uptake, Toxicity, and Detoxification in Plants 131 lipid peroxidation, and DNA damage by over production of ROS. In addition, lead strongly inhibits seed germination, root elongation, seedling development, plant growth, transpiration, chlorophyll production, and water and protein content. The negative effects that lead has on plant vegetative growth mainly result from the following factors: distortion of chloroplast ultrastructure, obstructed electron transport, inhibition of Calvin cycle enzymes, impaired uptake of essential elements, such as Mg and Fe, and induced deficiency of CO2 resulting from stomatal closure. Under lead stress, plants possess several defense strategies to cope with lead toxicity. Such strategies include reduced uptake into the cell; sequestration of lead into vacuoles by the formation of complexes; binding of lead by phytochelatins, glutathione, and amino acids; and synthesis of osmolytes. In addition, activation of various antioxidants to combat increased production of lead-induced ROS constitutes a secondary defense system

Can we predict community-wide effects of herbicides from toxicity tests on macrophyte species?

Macrophyte communities play an essential role in the way freshwater ecosystems function. It is thus of great concern to understand how environmental factors, especially anthropogenic ones, influence their composition and diversity. The aim of this study was to examine whether the effects of a herbicide mixture (50% atrazine, 35% isoproturon, 15% alachlor) on single macrophyte species can be used to predict its impact at a community level. In a first experiment we tested the sensitivity of six species (Azolla filiculoides, Ceratophyllum demersum, Elodea canadensis, Lemna minor, Myriophyllum spicatum and Vallisneria spiralis) grown separately and exposed to 0.6–600 gL−1 of the herbicide mixture. In a second experiment, conducted in microcosms, we tested the effects of herbicides on macrophyte assemblages composed of the same six species exposed to 0, 6 or 60 gL−1 of the herbicide mixture. Species grown separately exhibited growth inhibition at 60 and 600 gL−1. At 600 gL−1 the sensitivity differed significantly between species. V. spiralis was the most resistant species, C. demersum, M. spicatum and E. canadensis exhibited intermediate sensitivities, and A. filiculoides and L. minor were the most sensitive species. In microcosms, community biomass and Shannon evenness index were reduced after 8 weeks at 60 gL−1. Communities also exhibited changes in their composition: the relative and absolute abundance of C. demersum increased at 6 gL−1, while the relative abundance of V. spiralis increased at 60 gL−1. These results are in agreement with the individual responses of these species to the herbicides. It is therefore concluded that short-term effects of herbicides on simple macrophyte communities can be predicted from the sensitivity of individual species. However, further investigations are required to examine whether longer term effects can be predicted as well, especially in more complex communities

Herbicide effects on freshwater benthic diatoms: Induction of nucleus alterations and silica cell wall abnormalities

Benthic diatoms are well known bio-indicators of river pollution by nutrients (nitrogen and phosphorus). Biological indexes, based on diatom sensitivity for non-toxic pollution, have been developed to assess the water quality.Nevertheless, they are not reliable tools to detect pollution by pesticides. Many authors have suggested that toxic agents, like pesticides, induce abnormalities of the diatom cell wall (frustule). High abnormal frustule abundances have been reported in natural diatom communities sampled in streams contaminated by pesticides. However, no direct link was found between the abundances of abnormal frustules in these communities and the pesticide concentrations in stream water. In the present study, a freshwater benthic diatomcommunity, isolated fromnatural biofilm and cultured under controlled conditions, was treated with a known genotoxic herbicide, maleic hydrazide (MH). Cells were exposed to three concentrations of MH (5×10−6, 10−6, 10−7 M) for 6 h followed by a 24 h-recovery time. After MH treatments, nucleus alterations were observed: abnormal nucleus location, micronucleus, multinuclear cell or disruption of the nuclear membrane. A dose-dependent increase of nuclear alterations was observed. The difference between the control (9.65 nuclear alterations per 1000 cells observed (9.65‰), S.D. = 4.23) and the highest concentrations (29.40‰, S.D. = 8.49 for 10−6Mand 35.96‰, S.D. = 3.71 for 5×10−6 M)was statistically significant (Tukey test, P < 0.05). Diatoms also exhibited frustules with deformed morphology and abnormal ornamentation. Significantly increased abundances of abnormal frustules were observed for the highest concentrations (10−6 and 5×10−6 M; Tukey test, P < 0.05). These two parameters tended to increase together (Pearson correlation = 0.702, P < 0.05). The results suggest that the induction of abnormal frustules could be associated with the genotoxic effects of MH. The alterations observed could be related to the effects of MH on the synthesis of the proteins involved in frustule formation or in the regulation of the cytoskeleton of the diatom cells

Lead-induced genotoxicity to Vicia faba L.roots in relation with metal cell uptake and initial speciation

Formation of organometallic complexes in soil solution strongly influence metals phytoavailability. However, only few studies deal with the influence of metalspeciation both on plant uptake and genotoxicity. In the present study, Viciafaba seedlings were exposed for 6 h in controlled hydroponic conditions to 5 μM of lead nitrate alone and chelated to varying degrees by different organic ligands. Ethylenediaminetetraacetic acid and citric acid were, respectively, chosen as models of humic substances and low weight organic acids present in natural soil solutions. Visual Minteq software was used to estimate free lead cations concentration and ultimately to design the experimental layout. For all experimental conditions, both micronucleus test and measure of leaduptake by plants were finally performed. Chelation of Pb by EDTA, a strong chelator, dose-dependently increased the uptake in V. faba roots while its genotoxicity was significantly reduced, suggesting a protective role of EDTA. A weak correlation was observed between total lead concentration absorbed by roots and genotoxicity (r2=0.65). In contrast, a strong relationship (r2=0.93) exists between Pb2+ concentration in exposure media and genotoxicity in the experiment performed with EDTA. Citric acid induced labile organometallic complexes did not demonstrate any significant changes in leadgenotoxicity or uptake. These results demonstrate that metalspeciation knowledge could improve the interpretation of V. fabagenotoxicity test performed to test soil quality

Thidiazuron-induced shoot organogenesis from mature leaf explants of scented Pelargonium capitatum cultivars

Shoot organogenesis from mature leaf tissues of two scented Pelargonium capitatum cultivars, ‘Attar of Roses’ and ‘Atomic Snowflake’, grown in the greenhouse, were optimized in the presence of thidiazuron (TDZ). The protocol involved preculture of leaf sections on basal Murashige and Skoog (MS) medium supplemented with 10 lM TDZ, 4.4 lM of 6-benzyladenine (BA) and 5.4 lM a-naphtaleneacetic acid (NAA) for a period of 2 weeks and followed by subculture of explants to a fresh medium containing 4.4 lM BA and 5.4 lM NAA. Frequency of regeneration reached approximately 93% for both cultivars, with the induction of more than 100 shoots per explant. Regenerated plantlets were rooted on half-strength MS medium supplemented with 4.4 mM sucrose and 8.6 lM of Indole-3-acetic acid (IAA). All regenerated shoots from both cultivars developed roots when transferred to organic soil mix, acclimatized, and successfully transferred to greenhouse conditions. When regenerated shoots were transferred to hydroponic conditions, frequency of survival was 76.2 and 61.9% for ‘Attar of Roses’ and ‘Atomic Snowflake’, respectively

Multi-residues analysis of pre-emergence herbicides in fluvial sediments : application to the mid-Garonne River

Contamination of man and ecosystems by pesticides has become a major environmental concern. Whereas many studies exist on contamination from agriculture, the effects of urban sources are usually omitted. Fluvial sediment is a complex matrix of pollutants but little is known of its recent herbicide content. This study proposes a method for a fast and reliable analysis of herbicides by employing the accelerated solvent extractor (ASE). The aim of the study is to show the impact of a major town (Toulouse) on the herbicide content in the river. In this study, three herbicide families (i.e. s-triazine, substituted ureas and anilides) were analysed in fluvial sediment fractions at 11 sampling sites along the mid-Garonne River and its tributaries. River water contamination by herbicides is minor, except for at three sites located in urban areas. Among the herbicidal families studied, urban and suburban areas are distinguished from rural areas and were found to be the most contaminated sites during the study period, a winter low-water event. The herbicide content of the coarse sediment fractions is about one third of that found in the fine fractions and usually ignored. The distribution of pesticide concentrations across the whole range of particle sizes was investigated to clarify the role of plant remains on the significant accumulation in the coarse fractions

Giemsa versus acridine orange staining in the fish micronucleus assay and validation for use in water quality monitoring

This study concerns a comparative analysis of the acridineorange and Giemsastaining procedures for the fish erythrocyte micronucleusassay. The goal was to optimize the assay in the context of field watermonitoring. Fish (Carassius carassius) were exposed to a reference genotoxic agent, cyclophosphamide monohydrate 5 mg l−1 for 2, 4, and 6 days before testing. Slides from each individual were scored using the two procedures. The results show that the assay was more sensitive when acridineorange was used. When slides were Giemsa stained, the presence of ambiguous artefacts, leading to false positives and increasing random variance, reduced the contrast between exposed and control samples. AcridineOrangestaining was then applied in the context of waterqualitymonitoring. Fish were exposed for 4 days to water sampled in two hydrological contexts: basal flow and spring flood. The results show that exposure to spring flood water in an agricultural stream can induce mutagenicity