Changes in plant growth, Cd partitioning and xylem sap composition in two sunflower cultivars exposed to low Cd concentrations in hydroponics.

This study characterizes sunflower response to the levels of Cd encountered in moderately Cd-polluted soils. Two sunflower cultivars differing in their ability to sequestrate Cd in roots were exposed to low concentrations of Cd (0.5 nM or 100 nM) in hydroponics and sampled after 18 days (258 degree-days) when ten leaves were fully expanded. Plant growth, Cd uptake and partitioning among organs were monitored along with the ionomic (ICP-MS) and the metabolic (1H-NMR) composition of the xylem sap. Sunflower tolerance to Cd differed between the two cultivars. The cultivar with the highest ability to sequestrate Cd in roots (Kapllan) was more tolerant to Cd than the one with the lowest ability (ES RICA). The 23% penalization of plant growth observed at 100 nM in cultivar ES RICA was associated with reduced xylem loading fluxes of soluble sugars, perhaps pointing to disruption of carbohydrate metabolism. Retention of Cd in the stem was higher at 100 nM than at 0.5 nM in the Cd-sensitive cultivar ES RICA, which can be seen as a sunflower strategy to restrict the amount of Cd delivered to the leaves under Cd stress. No direct connection was found between the speciation of Cd in the xylem sap and the Cd translocation efficiency, although significant changes in the free ionic fraction of Cd were observed between the two cultivars at 0.5 nM. The relevance of these results in promoting the use of sunflower in phytomanagement of Cd-polluted soils is discussed.

Cadmium allocation to grains in durum wheat exposed to low Cd concentrations in hydroponics.

This study aims to characterize the response of durum wheat to different concentrations of Cd found in agricultural soils. One French durum wheat cultivar (i.e. Sculptur) was exposed to low concentrations of Cd (5 nM or 100 nM) in hydroponics. After anthesis, the plants were fed with a solution enriched with the stable isotope 111Cd to trace the newly absorbed Cd. Plants were sampled at anthesis and grain maturity to assess how plant growth, Cd uptake and partitioning among organs, as well as Cd remobilization, differed between the two Cd exposure levels. Durum wheat did not show any visual symptoms of Cd toxicity, regardless of which Cd treatment was applied. However, post-anthesis durum wheat growth was 14% penalized at 100 nM due to the large transpiration-based accumulation of Cd in leaves at this stage. The allocation of Cd to the grains was not restricted but enhanced at 100 nM compared to 5 nM. Both the root-to-shoot Cd translocation and the fraction of aboveground Cd allocated to grains were higher in plants exposed to 100 nM. Cadmium was remobilized exclusively from roots and stems, and remobilized Cd contributed on average to 40-45% of the Cd accumulated in mature grains, regardless of which Cd treatment was applied. The relevance of these results to decreasing the concentration of Cd in durum wheat grains is discussed.

Copper phytoavailability in vineyard topsoils as affected by pyoverdine supply.

Pyoverdine (Pvd) is a bacterial siderophore produced by some Pseudomonads species that can bind copper in addition to iron in soil. Pvd is expected to alter the dynamics and the ecotoxicity of Cu in vineyard soils. This study investigated the extent to which the mobility and the phytoavailability of Cu varied among vineyard soils with different pH and how they were affected by a supply of Pvd. Pvd was supplied (or not) to ten vineyard topsoils with pH ranging from 5.9 to 8.6 before metal was extracted with 0.005 M CaCl2. Cu mobility was assessed through its total concentration and Cu phytoavailability through its free ionic concentration measured in the CaCl2 extract. Cu mobility varied by a factor of six and Cu phytoavailability by a factor of 5000 among the soil samples. In the CaCl2 extract, the concentration of Cu2+ was not correlated with the concentration of total Cu but was correlated with pH. This revealed that Cu phytoavailability depends to a great extent on Cu complexation in soil pore water, the latter being highly sensitive to pH. Adding Pvd enhanced the mobility of Cu in the soils including in carbonate soils. The Pvd-mobilization factor for Cu varied from 1.4 to 8 among soils, linked to the availability of Fe and Al in the solid phase and to Pvd partitioning between the solid and the liquid phase. Adding Pvd reduced the concentration of Cu2+ in CaCl2 extract, which challenges the idea of using Pvd-producing bacteria to promote Cu phytoextraction.

How do low doses of desferrioxamine B and EDTA affect the phytoextraction of metals in sunflower?

The aim of this study was to compare the efficiency of siderophore desferrioxamine B (DFOB) and EDTA in increasing the phytoextraction of metals in sunflower. A 28-day pot experiment was conducted in a metal-contaminated soil supplied with 200µmolkg-1 of DFOB or EDTA. Pore water was collected and pseudo-polarographic analyses were conducted to assess the impact of the two chelators on the mobility and speciation of metals in the liquid phase. Our results showed that DFOB is not an efficient mobilizing agent of divalent metals in soil. Adding DFOB selectively increased the mobility of trivalent metals while the supply of EDTA simultaneously increased the mobility of both trivalent and divalent metals. EDTA significantly reduced the labile fractions of Cd, Cu, (Pb) and Zn measured in the porewater. The labile concentration of Cd and Zn measured in presence of EDTA was even less than that measured in the control. As expected from the pore water analysis, the addition of DFOB did not affect the phytoextraction of any divalent metals. In contrast, the addition of EDTA enhanced Cu and Ni phytoextraction in sunflower 2.0 to 2.8 fold for Cu and 1.3 to 2.3 fold for Ni, depending on the cultivar. This result supports different hypotheses regarding the forms and the related pathways in which metals are taken up in presence of EDTA. Based on the results obtained for Ni, whose uptake is rate limited by its internalization across the cell membrane, the direct uptake of metal-EDTA complexes via the non-selective apoplastic pathway is hypothesized to contribute the most to the overall uptake of metals in presence of EDTA, even added at "low" concentrations.

Accumulation of Cd, Cu and Zn in shoots of maize (Zea mays L.) exposed to 0.8 or 20 nM Cd during vegetative growth and the relation with xylem sap composition.

This work focuses on the exposure of maize plants to nanomolar concentrations of Cd, which is relevant for agricultural soils cropped with food and feed plants. Maize plants were cultivated in nutrient solution at 0.8 or 20 nM Cd during the vegetative growth stages. No significant hormesis or toxic effects of Cd were observed on maize growth, but a decrease in the allocation of Cd to shoots between the 0.8 and 20 nM Cd exposures revealed that the plants already responded to these low concentrations of Cd according to a shoot Cd excluder strategy. The Cd, Cu and Zn concentrations in shoots decreased with time as the result of an early decrease in the root/shoot ratio and of a decrease in the coefficient of allocation to aboveground for Zn and Cd at 20 nM. As a consequence, shoots of young plants were richer in micronutrients Cu and Zn but also in toxic Cd. The rate of delivery of Cd, Cu and Zn from xylem sap was successfully used to predict the time course of concentrations of Cd, Cu and Zn in the shoot. However, it overestimated the actual concentrations of Cd in the shoot, presumably because the reallocation of this trace element from shoots back to roots was not taken into account.

Effect of pyoverdine supply on cadmium and nickel complexation and phytoavailability in hydroponics.

Siderophores are chelators with a high selectivity for Fe(III) and a good affinity for divalent metals, including Cd(II) and Ni(II). Inoculation with siderophore-producing bacteria (SPB) has thus been proposed as an alternative to chelator supply in phytoremediation. Accurate assessments of the potential of this association require a dissection of the interaction of siderophores with metals at the soil-root interface. This study focuses on pyoverdine (Pvd), the main siderophore produced by Pseudomonas aeruginosa. We first assessed the ability of Pvd to coordinate Ni(II). The stability constant of Pvd-Ni(II) (log K (L'Ni) = 10.9) was found to be higher than that of Pvd-Cd(II) (log K (L'Cd) = 8.2). We then investigated the effect of a direct supply of Pvd on the mobilization, speciation, and phytoavailability of Cd and Ni in hydroponics. When supplied at a concentration of 50 µM, Pvd selectively promoted Ni mobilization from smectite. It decreased plant Ni and Cd contents and the free ionic fractions of these two metals, consistent with the free ion activity model. Pvd had a more pronounced effect for Ni than for Cd, as predicted from its coordination properties. Inoculation with P. aeruginosa had a similar effect on Ni phytoavailability to the direct supply of Pvd.

Remediation of sediment and water contaminated by copper in small-scaled constructed wetlands: effect of bioaugmentation and phytoextraction.

The use of plants and microorganisms to mitigate sediment contaminated by copper was studied in microcosms that mimic the functioning of a stormwater basin (SWB) connected to vineyard watershed. The impact of phytoremediation and bioaugmentation with siderophore-producing bacteria on the fate of Cu was studied in two contrasted (batch vs. semi-continuous) hydraulic regimes. The fate of copper was characterised following its discharge at the outlet of the microcosms, its pore water concentration in the sediment, the assessment of its bioaccessible fraction in the rhizosphere and the measurement of its content in plant tissues. Physico-chemical (pH, redox potential) and biological parameters (total heterotrophic bacteria) were also monitored. As expected, the results showed a clear impact of the hydraulic regime on the redox potential and thus on the pore water concentration of Cu. Copper in pore water was also dependent on the frequency of Cu-polluted water discharges. Repeated bioaugmentation increased the total heterotrophic microflora as well as the Cu bioaccessibility in the rhizosphere and increased the amount of Cu extracted by Phragmites australis by a factor of ~2. Sugar beet pulp, used as a filter to avoid copper flushing, retained 20% of outcoming Cu and led to an overall retention of Cu higher than 94% when arranged at the outlet of microcosms. Bioaugmentation clearly improved the phytoextraction rate of Cu in a small-scaled SWB designed to mimic the functioning of a full-size SWB connected to vineyard watershed. Highlights: Cu phytoextraction in constructed wetlands much depends on the hydraulic regime and on the frequency of Cu-polluted water discharges. Cu phytoextraction increases with time and plant density. Cu bioaccessibility can be increased by bioaugmentation with siderophore-producing bacteria.

Contrasting effects of pyoverdine on the phytoextraction of Cu and Cd in a calcareous soil.

Enhanced metal phytoextraction by the use of siderophore-producing bacteria (SPB) has received a lot of attention in the past decade. Bacterial siderophores are able to bind a wide range of metals other than iron and thus should enhance their phytoavailability in contaminated matrices. However, the impact of bacterial siderophores in the soil-plant transfer of metals is not yet fully elucidated, as underlined by the opposing results reported in the literature regarding the efficiency of coupling phytoextraction with bioaugmentation by SPB. The present study focuses on one bacterial siderophore, the pyoverdine (Pvd), produced by Pseudomonas aeruginosa. The coordination properties of Pvd towards Cd(II) and Cu(II) were determined and the effect of Pvd supply was assessed on (i) the mobility (CaCl2 extractions), (ii) the phytoavailability (DGT measurements) and (iii) the phytoextraction of Cd and Cu, in a calcareous soil. The stability constant of Pvd-Cu (KL'Cu=10(20.1)) was found much higher than that of Pvd-Cd (KL'Cd=10(8.2)). The major finding was the agreement observed between Pvd coordination properties and Pvd impact on metals phytoextraction. Pyoverdine, supplied at 250 µmol kg(-1) soil, enhanced the mobility, the phytoavailability and the phytoextraction of Cu while the fate of Cd was not affected. All these results were compared to those reported for chelate-assisted phytoextraction. Their relevance in using SPB for phytoremediation is discussed.

Decontamination of a polychlorinated biphenyls-contaminated soil by phytoremediation-assisted bioaugmentation.

A 70 day pot experiment was conducted for the cleaning-up of a PCBs-contaminated soil (104 mg kg(-1) soil DW) using bioaugmentation with Burkholderia xenovorans LB400 (LB400) assisted or not by the use of tall fescue (Festuca arundinacea). The total cultivable bacteria of the soil were higher with the presence of plants. Real-time PCR showed that LB400 (targeting 16S-23S rRNA ITS) survived with abundance related to total bacteria (targeting 16S rRNA) being higher with fescue (up to a factor of three). Bioaugmentation had a positive effect on fescue biomass and more specifically on roots (by a factor of three). PCB dissipation (sum of congeners 28, 52, 101, 118, 153, 180) averaged 13 % (bioaugmented-planted) up to 32 % (non bioaugmented-planted), without any significant difference between treatments. Basically our results demonstrated that indigenous bacteria were able to dissipate PCBs (26.2 % dissipation). PCB dissipation was not related to the abundance of LB400 or to the total bacterial counts. Bioaugmentation or fescue altered the structure of the bacterial community of the soil, not the combination of both. Principal component analysis showed that bioaugmentation tended to improve the control of the process (lower variability in PCB dissipation). Opposite to that bioaugmentation increased the variability of the structure of the bacterial community.

Quantification of the 16S-23S rRNA internal transcribed spacers of Burkholderia xenovorans strain LB400 using real-time PCR in soil samples.

This study establishes a new real-time PCR assay (using SYBR Green™ detection) for the identification and the direct quantification of specific individual Burkholderia xenovorans strain LB400 from DNA samples of soil and sediment. Specific primers were designed to amplify a 190-bp fragment of the 16S-23S rRNA internal transcribed spacers (ITS) from LB400. The specificity of primers was evaluated using 21 strains. The detection limit of the real-time PCR was analysed on soil samples inoculated with LB400 and was of 6 copies (10(5)  CFU g(-1) of dry sample). The 16S-23S rRNA ITS primers developed in this work for rapid quantification of LB400 were validated. The assay allowed the quantification of LB400 as pure strain and among the indigenous microbial community in samples of soil and sediment (105-day experiment).

Herbicide mitigation in microcosms simulating stormwater basins subject to polluted water inputs.

Non-point source pollution as a result of wine-growing activity is of high concern. Stormwater basins (SWB) found downstream of vineyard watersheds could show a potential for the mitigation of runoff water containing herbicides. In this study, mitigation of vinery-used herbicides was studied in microcosms with a very similar functioning to that recorded in SWB. Mitigation efficiency of glyphosate, diuron and 3,4-dichloroaniline (3,4-DCA) was investigated by taking into account hydraulic flow rate, mitigation duration, bioaugmentation and plant addition. Mitigation efficiency measured in water ranged from 63.0% for diuron to 84.2% for 3,4-DCA and to 99.8% for glyphosate. Water-storage duration in the SWB and time between water supplies were shown to be the most influential factors on the mitigation efficiency. Six hours water-storage duration allowed an efficient sorption of herbicides and their degradation by indigenous microorganisms in 5 weeks. Neither bioaugmentation nor plant addition had a significant effect on herbicide mitigation. Our results show that this type of SWB are potentially relevant for the mitigation of these herbicides stemming from wine-growing activity, providing a long enough hydraulic retention time.

[Baropodometric analysis of the functional donor-site morbidity after gastrocnemius or soleus muscle-flap procedure]. / Analyse baropodométrique des séquelles fonctionnelles liées au prélèvement des lambeaux gastrocnémiens et soléaire.

The triceps surae muscle is a major donor-site for muscle-flap to cover soft-tissue defects of the leg. There are very limited datas on the functional donor-site morbidity in the literature. From a retrospective study on 14 patients, we realized a baropodometric analysis comparing the operated lower limb with the healthy non operated side and a functional evaluation by a questionary. The modified functional score of Kitatoka was good (87/100). Ninety percent of the patients were able to resume a professional activity and 2/3 to resume the sport. The baropodometric analysis did not show statistically significant difference of propulsion and absorption between the healthy side and the operated side, but a modification of the programming of the step. The absence of important functional donor-site morbidity is probably bound to a compensation of the remaining triceps surae muscles and/or to mechanisms of adaptation. Our study confirms the little functional donor-site morbidity of the partial triceps surae muscle-flap procedure. These flaps remain a good solution for the coverage of the soft-tissue defects of the leg.

Comparison of two experimental speciation methods with a theoretical approach to monitor free and labile Cd fractions in soil solutions.

This work focused on the suitability of two techniques to monitor cadmium speciation in soil solutions collected during a 7-day incubation of a contaminated soil. Anodic stripping voltammetry (ASV) and ion exchange were performed on soil solutions collected daily and results were compared with calculations obtained with the speciation software Visual MINTEQ. The electrochemically labile Cd fraction was greater than the exchange-estimated free Cd fraction during the first 6 days, after which it decreased sharply during the last 2 days to reach values close to the exchange-estimated free Cd fraction. Further investigations showed that the increase in pH was mainly responsible for the reduction. However, calculations performed with Visual MINTEQ software clearly demonstrated that a change in the nature of organic matter and/or its complexing capacity also needed to be taken into consideration.

Cadmium speciation assessed by voltammetry, ion exchange and geochemical calculation in soil solutions collected after soil rewetting.

Analytical techniques and speciation models have been developed to characterize the speciation of Cd in soil solution. They provide an estimate of operationally defined species of Cd that need to be compared, especially for soil solutions highly concentrated in organic matter as are the solutions collected after soil rewetting. This work deals with the comparison between the speciation of Cd measured by anodic stripping voltammetry (ASV) and ion exchange and the speciation of Cd calculated using Visual MINTEQ. The aim of this study was to quantify and explain the differences in Cd speciation observed between the three approaches. Cd speciation was assessed in soil solutions collected 4, 8, 24, 48, 96 and 144h after the rewetting of an air-dried contaminated soil. To optimize the computed speciation of Cd, other physico-chemical parameters were followed (e.g. pH, ionic strength and the concentrations of major anions, major cations and dissolved organic carbon) and a brief characterisation of dissolved organic matter (DOM) was performed. The discrepancy between model predictions and analytical measurements highlighted the need for caution in the interpretation of geochemical speciated data for Cd. The major result of this study was that a characterization of DOM based on its specific UV-absorbance at 254 nm improved the accuracy of model predictions. Another finding is that labile Cd complexes, even organic, may have been included in the electrochemically labile fraction of Cd measured by ASV.

Temporal evolution of redox processes and free Cd dynamics in a metal-contaminated soil after rewetting.

Soil testing procedures to address metals bioavailability currently use air-dried soil rewetted almost until saturation. Such practices may influence the redox state of soil and the related dynamics of metals. To assess this potential impact, a metal-contaminated soil was air-dried and rewetted to 90% water holding capacity. We monitored over a 21-day incubation period the temporal changes of soil redox potential and solution Cd concentration (either total or free). Other physico-chemical parameters were followed notably pH, ionic strength (I) and the concentrations of NO(3)(-), Mn, Fe and SO(4)(2-) in solution. Soil redox potential showed the progressive establishment of strong reducing conditions in soil, in agreement with the temporal changes of NO(3)(-), Mn, Fe and SO(4)(2-) concentrations. It decreased by 13 pe units over the culture period leading to sulphate-reducing conditions (pe<-3) within only 21days. Solution Cd concentration increased transitorily over the first 100-150h of incubation (2-fold increase) in relation with the parallel increase in the concentration of competing cations for adsorption (Ca, Mg). It steeply decreased over the last 300h of incubation (30-fold decrease) as a result of Cd precipitation as Cd sulphides. This biphasic evolution of Cd dynamics was related to the temporal changes of Cd resupply from the solid phase. Using the technique of DGT we described the kinetics of Cd resupply over time and needed to invoke the existence of two pools of Cd.

[Family caregivers and hereditary muscular disorders: association between burden, quality of life and mental health]. / Les aidants familiaux des personnes myopathes: liaisons entre charge de soins, qualité de vie et santé mentale.

OBJECTIVE: The analysis of caregiver difficulties seems important to define the life of the patient. The aim of the study was to evaluate the burden of perceived care, health-related quality of life, and mental health of family caregivers who care for patients with hereditary neuromuscular disease. MATERIALS AND METHOD: Fifty-nine family caregivers were investigated in the course of multidisciplinary consultations in Reims, France, between April 2002 and February 2005. Burden of perceived care, mental functioning and mental health were measured by answers to an burden interview instrument (Zarit Burden Inventory, ZBI), a health-related quality of life questionnaire (the SF-36 and General Health Questionnaire-12 items [GHQ-12]), and an instrument quantifying anxiety and depression (Hospital Anxiety and Depression scale [HAD]). The domain scores of the SF-36 were compared with those of the general population. Non-parametric correlations between scores were calculated. RESULTS: Thirty-five parents, 20 spouses, a sister, a grandmother and two friends cared for patients with hereditary myopathy. The average age of caregivers was 50+/-11 years; 81% were women. Ten percent of the caregivers had above-normal scores on the HAD scale, One-third perceived a significant reduction in health-related quality of life, and more half expressed a moderate or important burden according to their answers on the ZBI. Depression occurred in a great proportion of the caregivers, and they showed reduced health-related quality of life as compared with the general population. CONCLUSION: Taking into account these results, it appears useful to set up a specific support for family caregivers of patients with hereditary myopathy.

MMG measurement: a high-sensitivity microphone-based sensor for clinical use.

High-sensitivity human muscle-vibration measurement (MMG) sensor adapted to clinical use is presented. The muscle vibration phenomenon is modeled and investigated to optimize the measurement technique. The sensor uses an acoustic impedance adaptation technique to convert the skin surface vibration in terms of acoustic pressure, which is sensed by a microphone. The device is calibrated and gives the real amplitude of the vibration. It is also well fitted to measure other physiological vibrations in the 2 Hz-1 KHz range.

Noncontact MMG Sensor Based on the Optical Feedback Effect in a Laser Diode.

An optical interferometric MMG sensor is presented. It uses the feedback effect in a laser diode to measure the vibration generated by the MMG at the skin surface. Its key features are noncontact measurement, high sensitivity, and extended bandwidth toward low frequencies (≈1 Hz). Furthermore, as it is able to recover with a good accuracy the shape of vibrations ranging from 1 µm peak-to-peak, the MMG is expressed in the physiological unit (micrometer) rather than the sensor dependent unit. The MMG measurement conditions are reviewed through a clinical protocol, including the perturbation causes. This probe is compared with a classical microphone based sensor, and thereby the influence of the coupling between the muscle and a contact sensor is demonstrated. © 1998 Society of Photo-Optical Instrumentation Engineers.

[The urorectal syndrome caused by abdomen-levator incoordination in children]. / Le syndrome urorectal par incoordination abdomino-lévatorienne chez l'enfant.

We have studied thirty four children (mean age 6.6 years) with severe functional constipation, associated or not with encopresis. In twenty three cases the defecography showed a persistent anorectal angle due to failure of puborectalis sling relaxation during defecation straining. Voiding disorders, unknown to parents, but demonstrated by obstructive uroflowmetry, are also seen in nineteen of these children. Therefore is definite a true urorectal outlet obstruction syndrome by spastic pelvic floor mechanism. The exact etiologic factor of these functional abnormalities remains undefined. All children were managed by biofeedback training. A satisfactory result (with six months follow up), has obtained in fourteen cases.