Inhibitory effect of metals on animal and plant glutathione transferases.

Glutathione transferases (GSTs) represent a widespread enzyme superfamily in eukaryotes and prokaryotes catalyzing different reactions with endogenous and xenobiotic substrates such as organic pollutants. The latter are often found together with metal contamination in the environment. Besides performing of essential functions, GSTs protect cells by conjugation of glutathione with various reactive electrophiles.

Fungi from metal-polluted streams may have high ability to cope with the oxidative stress induced by copper oxide nanoparticles.

Increased commercialization of products based on metal oxide nanoparticles increases the likelihood that these nanoparticles will be released into aquatic environments, thus making relevant the assessment of their potential impacts on aquatic biota. Aquatic fungi are distributed worldwide and play a key role in organic matter turnover in freshwater ecosystems. The present study investigated the impacts of copper oxide spherical nanoparticles (CuO-NPs; <50 nm powder, 5 levels ≤200 mg/L) on cellular targets and antioxidant defenses in 5 fungal isolates collected from metal-polluted or nonpolluted streams.

Physiological responses to nanoCuO in fungi from non-polluted and metal-polluted streams.

Nanocopper oxide (nanoCuO) is among the most widely used metal oxide nanoparticles which increases their chance of being released into freshwaters. Fungi are the major microbial decomposers of plant litter in streams. Fungal laccases are multicopper oxidase enzymes that are involved in the degradation of lignin and various xenobiotic compounds.

The major function of a metallothionein from the aquatic fungus Heliscus lugdunensis is cadmium detoxification.

A spring from a former copper shale mine in the area of Mansfelder Land, Germany, shows extremely high transition metal ion concentrations, i.e. 40mM Zn(II), 208μM Cu(II), 61μM As(V), and 25μM Cd(II).

Identification of phytochelatins in the cadmium-stressed conjugating green alga Micrasterias denticulata.

Aquatic environments like peat bogs are affected by anthropogenic metal input into the environment. These ecosystems are inhabited by unicellular green algae of the class Zygnematophyceae. In this study the desmid Micrasterias denticulata was stressed with 600 nM Cd, 10 μM Cr and 300 nM Cu for 3 weeks.

The relevance of compartmentation for cysteine synthesis in phototrophic organisms.

In the vascular plant Arabidopsis thaliana, synthesis of cysteine and its precursors O-acetylserine and sulfide is distributed between the cytosol, chloroplasts, and mitochondria. This compartmentation contributes to regulation of cysteine synthesis. In contrast to Arabidopsis, cysteine synthesis is exclusively restricted to chloroplasts in the unicellular green alga Chlamydomonas reinhardtii.

Fungi in freshwaters: ecology, physiology and biochemical potential.

Research on freshwater fungi has concentrated on their role in plant litter decomposition in streams. Higher fungi dominate over bacteria in terms of biomass, production and enzymatic substrate degradation. Microscopy-based studies suggest the prevalence of aquatic hyphomycetes, characterized by tetraradiate or sigmoid spores.

Quantification of phytochelatins in Chlamydomonas reinhardtii using ferrocene-based derivatization.

A method for the identification and quantification of canonic and isoforms of phytochelatins (PCs) from Chlamydomonas reinhardtii was developed. After disulfide reduction with tris(2-carboxyethyl)phosphine (TCEP) PCs were derivatized with ferrocenecarboxylic acid (2-maleimidoyl)ethylamide (FMEA) in order to avoid oxidation of the free thiol functions during analysis. Liquid chromatography (LC) coupled to electrospray mass spectrometry (ESI-MS) and inductively coupled plasma-mass spectrometry (ICP-MS) was used for rapid and quantitative analysis of the precolumn derivatized PCs.

Chiral separation of the β2-sympathomimetic fenoterol by HPLC and capillary zone electrophoresis for pharmacokinetic studies.

The development of methods for the separation of the enantiomers of fenoterol by chiral HPLC and capillary zone electrophoresis (CZE) is described. For the HPLC separation precolumn fluorescence derivatization with naphthyl isocyanate was applied. The resulting urea derivatives were resolved on a cellulose tris(3,5-dimethylphenylcarbamate)-coated silica gel column employing a column switching procedure.

Regulation of sulfate assimilation in Physcomitrella patens: mosses are different!

Sulfur is an essential nutrient, taken up as sulfate from soil, reduced and incorporated into bioorganic compounds in plant cells. The pathway of sulfate assimilation is highly regulated in a demand-driven manner in seed plants. To test the evolutionary conservation of the regulatory mechanisms, we analyzed regulation of the pathway in the model for basal plants, the moss Physcomitrella patens.

Analytical approach for characterization of cadmium-induced thiol peptides--a case study using Chlamydomonas reinhardtii.

Phytochelatins (PC) were described earlier to play a role in metal detoxification in Chlamydomonas reinhardtii but were not clearly identified. The focus of this case study was to identify PC synthesized by C. reinhardtii exposed to Cd.

Interaction of heavy metals with the sulphur metabolism in angiosperms from an ecological point of view.

The metabolism of sulphur in angiosperms is reviewed under the aspect of exposure to ecologically relevant concentrations of sulphur, heavy metals and metalloids. Because of the inconsistent use of the term 'metal tolerance', in this review the degree of tolerance to arsenic and heavy metals is divided into three categories: hypotolerance, basal tolerance and hypertolerance. The composition of nutrient solutions applied to physiological experiments let see that the well-known interactions of calcium, sulphate and zinc supply with uptake of heavy metals, especially cadmium are insufficiently considered.

Fungi in a heavy metal precipitating stream in the Mansfeld mining district, Germany.

Fungal growth on alder leaves was studied in two heavy metal polluted streams in central Germany. The aim of the study was to examine previously observed differences in leaf decomposition rates, heavy metal precipitation and fungal involvement in these processes at the microscopic level. Ergosterol analyses indicated that neither habitat was optimal for fungi, but leaves exposed at the less polluted site (H8) decomposed rapidly and were colonized externally and internally by fungi and other microorganisms.

Sulphate assimilation under Cd2+ stress in Physcomitrella patens--combined transcript, enzyme and metabolite profiling.

Cd(2+) causes disturbance of metabolic pathways through severe damage on several levels. Here we present a comprehensive study of Cd(2+)-mediated effects on transcript, enzyme and metabolite levels in a plant without phytochelatin (PC). The moss Physcomitrella patens (Hedw.

Stress response in two strains of the aquatic hyphomycete Heliscus lugdunensis after exposure to cadmium and copper ions.

Biochemical responses to cadmium (Cd2+) and copper (Cu2+) exposure were compared in two strains of the aquatic hyphomycete (AQH) Heliscus lugdunensis. One strain (H4-2-4) had been isolated from a heavy metal polluted site, the other (H8-2-1) from a moderately polluted habitat. Conidia of the two strains differed in shape and size.

Species-specific Cd-stress response in the white rot basidiomycetes Abortiporus biennis and Cerrena unicolor.

The effect of cadmium (Cd) on fungal growth, Cd bioaccumulation and biosorption, and on the formation of potential heavy metal response indicators such as thiols, oxalate, and laccase was investigated in the white rot fungi Cerrena unicolor andAbortiporus biennis. Only the highest Cd concentration employed (200 microM) inhibited growth of C. unicolor, whereas already lower Cd concentrations caused decreasing mycelia dry weights in A.

Biotransformation of 1-naphthol by a strictly aquatic fungus.

The aquatic hyphomycete Heliscus lugdunensis belongs to a group of exclusively aquatic mitosporic fungi with an only scarcely explored potential to oxidatively attack xenobiotic compounds, and was used to study the biotransformation of the environmental pollutant metabolite 1-naphthol. H. lugdunensis metabolized approximately 74% of 1-naphthol within 5 days.

Cadmium induces a novel metallothionein and phytochelatin 2 in an aquatic fungus.

Cadmium stress response was measured at the thiol peptide level in an aquatic hyphomycete (Heliscus lugdunensis). In liquid culture, 0.1 mM cadmium increased the glutathione (GSH) content and induced the synthesis of additional thiol peptides.

Cadmium and zinc response of the fungi Heliscus lugdunensis and Verticillium cf. alboatrum isolated from highly polluted water.

The aquatic hyphomycete Heliscus lugdunensis and the terrestrial fungus Verticillium cf. alboatrum, both isolated from a highly polluted surface water, were investigated for their tolerance against Cd and Zn. Hl-H4 showed a 50% growth inhibition at 0.

Quantification of metallothionein-like proteins in the mussel Mytilus galloprovincialis using RP-HPLC fluorescence detection.

A HPLC-fluorescence method, using the fluorophore SBD-F (ammonium-7-fluorobenz-2-oxa-1,3-diazole-4-sulfonate), was adapted for the quantification of metallothioneins and their isoforms from the Moroccan mussel Mytilus galloprovincialis. The method was first optimized using a rabbit liver metallothionein. The effects of EDTA, tris(2-carboxyethyl)phosphine, and SBD-F on the labeling efficiency were studied.

Effects of heavy metals on the nitrogen metabolism of the aquatic moss Fontinalis antipyretica L. ex Hedw. A 15N tracer study.

The assessment of pollution in aquatic systems necessitates an accurate indication of toxicity of heavy metals for organisms and ecosystems. We used the stable nitrogen isotope 15N to estimate the influence of the heavy metals Cd, Pb and Zn on the synthesis of nitrogen-containing fractions in the aquatic moss Fontinalis antipyretica. This method permits conclusions concerning inhibitory effects of these heavy metals on the assimilation of nitrogen and the biosynthesis of amino acids and proteins.

Coumarins give misleading absorbance with Ellman's reagent suggestive of thiol conjugates.

In the course of a screening for phytochelatins in cadmium-exposed bryophytes in the terrestrial mosses Polytrichum formosum and Atrichum undulatum we detected compounds with absorption properties and retention times similar to phytochelatins when applying the commonly used standard method RP-HPLC and post-column derivatization with thiol-specific DTNB (Ellman) reagent. Moreover, as with phytochelatins known in other plants, the concentrations of these compounds increased slightly after Cd stress. The concentration of the precursor glutathione (gamma-ECG), however, increased in the presence of Cd.