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See detailZinc triggers a complex transcriptional and post-transcriptional regulation of the metal homeostasis gene FRD3 in Arabidopsis relatives
Charlier, Jean_Benoit; Polese, Catherine; Nouet, Cécile ULg et al

in Journal of Experimental Botany (2015)

In Arabidopsis thaliana, FRD3 (Ferric Chelate Reductase Defective 3) plays a central role in metal homeostasis. FRD3 is among a set of metal homeostasis genes that are constitutively highly expressed in ... [more ▼]

In Arabidopsis thaliana, FRD3 (Ferric Chelate Reductase Defective 3) plays a central role in metal homeostasis. FRD3 is among a set of metal homeostasis genes that are constitutively highly expressed in roots and shoots of Arabidopsis halleri, a zinc hyperaccumulating and hypertolerant species. Here, we examined the regulation of FRD3 by zinc in both species to shed light on the evolutionary processes underlying the evolution of hyperaccumulation in A. halleri. We combined gene expression studies with the use of GUS and GFP reporter constructs to compare the expression profile, transcriptional and post-transcriptional regulation of FRD3 in both species. The AtFRD3 and AhFRD3 genes display a conserved expression profile. In A. thaliana, alternative transcription initiation sites from two promoters determine transcript variants which are differentially regulated by zinc supply in roots and shoots to favour the most highly translated variant under zinc excess conditions. In A. halleri, a single transcript variant with higher transcript stability and enhanced translation has been maintained. The FRD3 gene thus undergoes complex transcriptional and post-transcriptional regulation in Arabidopsis relatives. Our study reveals that a diverse set of mechanisms underlie increased gene dosage in the A. halleri lineage and illustrates how an environmental challenge can alter gene regulation. [less ▲]

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See detailFunctional analysis of the three HMA4 copies of the metal hyperaccumulator Arabidopsis halleri
Nouet, Cécile ULg; Charlier, Jean-Benoit; Carnol, Monique ULg et al

in Journal of Experimental Botany (2015), in press

In Arabidopsis halleri, the AhHMA4 gene has an essential function in Zn/Cd hypertolerance and hyperaccumulation by mediating root to shoot translocation of metals. Constitutive high expression of AhHMA4 ... [more ▼]

In Arabidopsis halleri, the AhHMA4 gene has an essential function in Zn/Cd hypertolerance and hyperaccumulation by mediating root to shoot translocation of metals. Constitutive high expression of AhHMA4 results from a tandem triplication and cis-activation of the promoter of all three copies. The three AhHMA4 copies possess divergent promoter sequences, but highly conserved coding sequences, and display identical expression profiles in the root and shoot vascular system. Here, we expressed an AhHMA4::GFP fusion under the control of each three A. halleri HMA4 promoters in a hma2hma4 double mutant of Arabidopsis thaliana to individually examine the function of each A. halleri AhHMA4 copy. The protein localized non-polarly at the plasma membrane of the root pericycle cells of both A. thaliana and A. halleri. The expression of each AhHMA4::GFP copy complemented the severe Zn deficiency phenotype of the hma2hma4 mutant by restoring root-to-shoot translocation of zinc. However, each copy had different impact on metal homeostasis in the A. thaliana genetic background: AhHMA4 copies 2 and 3 were more highly expressed and provided higher Zn tolerance in roots and accumulation in shoots than copy 1, whereas AhHMA4 copy 3 also increased Cd tolerance in roots. Our data suggest a certain extent of functional differentiation among the three A. halleri HMA4 copies, stemming from differences in expression levels rather than in expression profile. HMA4 is a key node of the Zn homeostasis network and small changes in expression level can have major impact on Zn allocation to root or shoot tissues. [less ▲]

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See detailTree species diversity effects on soil microbial biomass, diversity and activity across European forest types
Carnol, Monique ULg; Baeten, Lander; Bosman, Bernard ULg et al

Conference (2014, December)

Increasing tree species diversity in forests might contribute to ecosystem-service maintenance, as well as to the reconciliation of regulating, provisioning and supporting services within the frame of ... [more ▼]

Increasing tree species diversity in forests might contribute to ecosystem-service maintenance, as well as to the reconciliation of regulating, provisioning and supporting services within the frame of multifunctional and sustainable forestry. Individual tree species influence biogeochemical cycling through element deposition (throughfall, litterfall), and through microbial activities in the soil. Yet, the influence of mixing tree species on these ecosystem processes is unclear, in particular concerning the microbial diversity and activity in soils. Here we synthesize results from the Exploratory Platform of the FunDivEUROPE project (http://www.fundiveurope.eu/). This network of 209 comparative plots covering a tree diversity gradient of 1 to 5 tree species was established in existing mature forests in 6 European regions. These six focal regions represent a gradient of major European forest types from boreal to Mediterranean forests. We analysed the impact of tree species diversity and the role of other controlling factors on the metabolic diversity of soil bacteria (BIOLOG Ecoplate), soil microbial biomass (fumigation-extraction) and potential nitrification (shaken soil slurry) in the forest floor and the upper organo-mineral soil horizon. Mean values of microbial biomass carbon ranged from 240 (Poland) to 1762 (Germany) mg kg-1 in the forest floor and from 4197 (Italy) to 11207 (Finland) mg kg-1 in the upper organo-mineral horizon. Tree diversity and soil water content were important controlling factors. Statistical models predict microbial biomass to increase in both horizons by 7-8% with each step increase in tree diversity. Metabolic diversity of soil bacteria (% of substrates used) showed high variability both within and between sites. Further results analysed with mixed linear models will be presented and discussed. [less ▲]

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See detailMetabolic diversity and microbial biomass in forest soils across climatic and tree species diversity gradients
Carnol, Monique ULg; Bosman, Bernard ULg; Vanoppen, Astrid et al

Poster (2013, August)

The biogeochemical cycling in forest ecosystems is highly dependent on the interactions between plants and soil. Tree species affect element cycling through deposition in throughfall, litterfall ... [more ▼]

The biogeochemical cycling in forest ecosystems is highly dependent on the interactions between plants and soil. Tree species affect element cycling through deposition in throughfall, litterfall, microbial activities in soil and rhizosphere processes. Tree species diversification has been suggested for maintaining forest ecosystem services and combining provisioning and supporting services within multifunctional and sustainable forestry. However, the understanding of the role of biodiversity in forests is unclear, in particular concerning the microbial diversity and activity in soils. Here we synthesize results from measurements of bacterial metabolic diversity and microbial biomass in soils sampled in the 209 plots of the Exploratory Platform of the FunDivEUROPE project (http://www.fundiveurope.eu/). This Exploratory Platform is a network of comparative plots of 1-5 tree species established in existing mature forest in 6 countries. These six focal regions represent important European forest types along the gradient from boreal forest to Mediterranean forest. We analysed the impact of tree species richness and the role of other controlling factors on the metabolic diversity of soil bacteria and on microbial biomass. [less ▲]

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See detailAssessment of the functional role of tree diversity: the multi-site FORBIO experiment
Verheyen, Kris; Ceunen, Kris; Ampoorter, Evy et al

in Plant Ecology and Evolution (2013), 146(1), 26-35

Context – During the last two decades, functional biodiversity research has provided strong support for the hypothesis that more biodiverse ecosystems have the potential to deliver more and better ... [more ▼]

Context – During the last two decades, functional biodiversity research has provided strong support for the hypothesis that more biodiverse ecosystems have the potential to deliver more and better services. However, most empirical support for this hypothesis comes from simple structured communities that are relatively easy to manipulate. The impact of forest biodiversity on forest ecosystem functioning has been far less studied. Experiment design – In this paper, we present the recently established, large-scale FORBIO experiment (FORest BIOdiversity and Ecosystem Functioning), specifically designed to test the effects of tree species diversity on forest ecosystem functioning. FORBIO’s design matches with that of the few other tree diversity experiments worldwide, but at the same time, the FORBIO experiment is unique as it consists of a similar experimental set-up at three sites in Belgium (Zedelgem, Hechtel-Eksel and Gedinne) with contrasting edaphic and climatological c haracteristics. This design will help to provide answers to one of the most interesting unresolved questions in functional biodiversity research, notably whether the effects of complementarity on ecosystem functioning decrease in less stressful and more productive environments. At each site, FORBIO consists of 41 to 44 plots (127 plots in total) planted with monocultures and mixtures up to four species, selected from a pool of five site-adapted, functionally different tree species. When allocating the treatments to the plots, we maximally avoided any possible covariation between environmental factors. Monitoring of ecosystem functioning already started at the Zedelgem and Gedinne sites and will start soon in Hechtel-Eksel. Multiple processes are being measured and as the trees grow older, we plan to add even more processes. Expected results – Not only basic science, but also forest management will benefit from the results coming from the FORBIO experiment, as FORBIO is, for instance, also a test case for uncommon, not well-known tree species mixtures. To conclude, FORBIO is an important ecosystem experiment that has the potential to deliver badly needed insights into the multiple relationships between biodiversity and ecosystem functioning, which will be valuable for both science and practice. [less ▲]

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See detailDo we need to standardize extraction procedures for community level physiological profiling?
Carnol, Monique ULg; Bosman, Bernard ULg; Malchair, Sandrine ULg

Poster (2011, July)

Microorganisms are essential regulators of soil functioning, as they are involved in many crucial processes such as organic matter decomposition, nutrient cycling, soil structure and fertility. Currently ... [more ▼]

Microorganisms are essential regulators of soil functioning, as they are involved in many crucial processes such as organic matter decomposition, nutrient cycling, soil structure and fertility. Currently, there is a growing interest in functional diversity, such as the number and type of substrates used for energy metabolism (CLPP-community level physiological profiling). Such metabolic diversity of heterotroph soil bacteria is frequently investigated through Biolog Ecoplates, containing 31 of the most useful carbon sources for the soil community. The metabolic diversity of soil bacteria might be an interesting biological indicator of soil quality, and also a useful tool for investigating the link between land use change, climate warming, soil carbon, microbial diversity and activity. Methods related to Biolog-CLPP reported in the literature differ in the suspension medium and extraction method, the type and density of inoculums, the inoculation procedures and conditions of incubations. For example, various combinations of extraction methods and suspension media are being used for the first bacterial extraction step. Despite such methodological differences, Biolog-CLPP data are often compared across studies. The development of a standardised method for Biolog-CLPP is however essential improving the relevance and significance of results across studies. In this work, we investigated the influence of extraction procedures on microbial extraction efficiency for further use in CLPP. The microbial extraction efficiency was tested by plate counts for a total of twelve combinations of three suspension media and four extraction methods. The experiment was performed on four soils differing in organic matter content. The aims of this study were to: • Synthesize extraction procedures used for Biolog-CLPP • Measure the effect of extraction procedures on microbial extraction efficiency (plate counts) in four soil types • Investigate a possible interaction between the suspension media and the extraction method used • Evaluate whether a standardized extraction procedure can be recommended across soil types [less ▲]

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See detail20 ans d'études dans 2 bassins versants boisés en Ardenne
Guillaume, Patricia; Bosman, Bernard ULg; Bazgir, Masoud et al

Diverse speeche and writing (2011)

En Région wallonne, de nombreux sols forestiers se caractérisent par un pH faible et une pauvreté en Ca, P et surtout Mg. Depuis 1991, dans le cadre d’études sur le dépérissement forestier et l’impact de ... [more ▼]

En Région wallonne, de nombreux sols forestiers se caractérisent par un pH faible et une pauvreté en Ca, P et surtout Mg. Depuis 1991, dans le cadre d’études sur le dépérissement forestier et l’impact de mesures de gestion forestière, le laboratoire d’Ecologie Végétale et Microbienne (ULg) étudie l’évolution des concentrations et des flux en éléments minéraux dans les principaux compartiments de deux bassins versants. Ce triptyque résume une partie de ces recherches. [less ▲]

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See detailElement removal in harvested tree biomass: scenarios for critical loads in Wallonia, south Belgium
Bosman, Bernard ULg; Remacle, Jean; Carnol, Monique ULg

in Water, Air & Soil Pollution : Focus (2001), 1

The critical load concept is now widely used as a tool for developing emission control policies in Europe. As a signatory country of the Convention of Long-Range Transboundary Air Pollution, critical ... [more ▼]

The critical load concept is now widely used as a tool for developing emission control policies in Europe. As a signatory country of the Convention of Long-Range Transboundary Air Pollution, critical loads for acidity, nutrient nitrogen, nitrogen and sulphur have been calculated for the Flemish and Walloon regions in Belgium. This paper describes the methodology used for estimating critical loads for forest soils in the Walloon region according to the Steady-State Mass Balance equations. As an example the methodology was applied to the catchment `Waroneu', situated in a sensitive area of the Haute Ardenne. Main input parameters to the equations were derived from precipitation and runoff data of the catchment study. Improved estimates of nitrogen uptake (Nu) and base cation uptake (BCu) were obtained by intensive sampling of Picea abies and Quercus robur trees. Nutrient contents (Ca, Mg, K, N) and nutrient to nitrogen ratios of Picea abies reflected the poor soil quality at a site with high N deposition. Quercus robur nutrient contents increased from stem to higher order branches with a high proportion of nutrients located in the bark. However the simulation of stem only harvesting had a minor effect on critical loads. Measured wood densities were lower than reported literature values with a main effect on Nu and BCu estimates. The use of recommended default values and/or data derived from the experimental site resulted in a wide range of critical loads, some of which were largely overestimated. Results demonstrated the importance of site specific data for critical load calculations. [less ▲]

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See detailIncreased plasma malondialdehyde associated with cerebellar structural defects.
RAMAEKERS, Vincent ULg; Bosman, Bernard ULg; Jansen, G. A. et al

in Archives of disease in childhood (1997), 77(3), 231-4

BACKGROUND: Malondialdehyde (MDA) in plasma is regarded as an indicator for increased lipid peroxidation. METHOD: Measurements of MDA concentrations in plasma were compared among healthy children (n = 31 ... [more ▼]

BACKGROUND: Malondialdehyde (MDA) in plasma is regarded as an indicator for increased lipid peroxidation. METHOD: Measurements of MDA concentrations in plasma were compared among healthy children (n = 31), patients with neurological disorders or epileptic syndromes (n = 15), and children with pontocerebellar structural defects (n = 31), where the cause or genetic defect remained unknown. RESULTS: In healthy children the median MDA value was 5.86 nmol/ml (mean (SD) value: 6.25 (1.97), range: 3.76-11.19). For the group with various neurological disorders or epilepsy, the values were similar with the median value at 5.66 nmol/ml (range 0.22-10.86). Compared with healthy controls and the neurological/ epileptic group, the 31 children with pontocerebellar structural defects had significantly increased MDA values with a median value at 11.29 nmol/ml (mean (SD) value: 11.62 (3.27), range 3.65-19.22). IMPLICATION: These findings of increased plasma MDA in the majority of children with pontocerebellar structural defects of unknown origin raised the question whether increased lipid peroxidation leads to prenatal and postnatal pontocerebellar maldevelopment or degeneration. [less ▲]

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