Cadmium uptake and subcellular compartmentation in the ectomycorrhizal fungus Paxillus involutus were investigated using radiotracer flux analyses. Concentration-dependent Cd2+-uptake kinetics characterized by a smooth, non-saturating curve that could be dissected into linear saturable components. The linear-uptake kinetic component was interpreted as representing binding of Cd to apoplastic components, whereas remaining result carrier-mediated transport across plasma membrane....

Summary External hyphae, which play a key role in nitrogen nutrition of trees, are considered as the absorbing structures ectomycorrhizal symbiosis. Here, we have cloned and characterized Hebeloma cylindrosporum AMT1 , GLNA GDHA genes, encode third ammonium transporter, glutamine synthetase an NADP‐dependent glutamate dehydrogenase respectively. Amt1 can fully restore pseudohyphal growth defect Saccharomyces cerevisiae mep2 mutant, this is first evidence that heterologous member Mep/Amt...

The gene encoding a superoxide dismutase (PiSOD) was cloned by suppressive subtractive hybridization from cDNA library of the ectomycorrhizal fungus, Paxillus involutus , grown under cadmium‐stress conditions. encoded protein presumed to be localized in peroxisomes because it contained C‐terminal peroxisomal localization peptide (SKL) and lacked an N‐terminal mitochondrial transit peptide. Complementation Escherichia coli SOD null strain that is unable grow presence paraquat or cadmium...

Heterologous expression of the yeast triple Mep mutant has enabled first molecular characterization AMT/MEP family members in an ectomycorrhizal fungus. External hyphae, which play a key role nitrogen nutrition trees, are considered as absorbing structure symbiosis and therefore studies on ammonium transport hyphae urgently needed. The kinetic properties AMT2 AMT3 from Hebeloma cylindrosporum were studied Saccharomyces cerevisiae . Expression HcAmts restored retention within cells. did not...

Glutamine synthetase (GS) and NADP-dependent glutamate dehydrogenase (NADP-GDH) play a key role in nitrogen assimilation the ectomycorrhizal fungus Laccaria laccata (Scop. ex Fr. Cke) strain S 238. The two enzymes were purified to apparent electrophoretic homogeneity by three-step procedure involving diethylaminoethyl (DEAE)-Trisacryl affinity chromatography, DEAE-5PW fast protein liquid chromatography. This purification scheme resulted 23 62% recovery of initial activity for GS NADP-GDH,...

summary In order to investigate the relative contribution of glutamine synthetase and NADP‐glutamate dehydrogenase assimilation ammonium (NH 4 + ) by spruce ectomycorrhizas, changes in free amino acid content kinetics 15 N incorporation into acids were measured together with effect specific enzyme inhibitors. Exposure detached ectomycorrhizas ( NH 2 SO showed that greatest flow enters amido group glutamine. Label was also detected glutamic acid, alanine γ‐aminobutyric acid. Large amounts...

summary The ammonia assimilation enzyme glutamate dehydrogenase as studied in extracts of spruce ( Picea excelsa L.) roots, mycelium a mycorrhizal fungus Hebeloma sp.) and associated ectomycorrhizas. Evidence from reactions crude extracts, electrophoretic patterns immunological tests Using antibodies raised against purified NADP‐GDH Cenococcum geophilum Fr. consistently showed that NADP‐dependent GDH was active Histochemical studies some activity with the Hartig net. By contrast, fungal...

Variation within the internal transcribed spacer (ITS) of ribosomal RNA gene 15 isolates representing seven European Armillaria species, was examined by sequencing PCR‐amplified products. The analysis an 744‐bp region showed that 5.8S appeared to be highly conserved in and other Basidiomycetes Ascomycetes, whereas ITS1 especially ITS2 spacers exhibited polymorphisms due base substitutions, insertions or deletions up eight nucleotides. An initial dendrogram for full sequence drawn using...

The kinetics, energetics and specificity of a general amino acid transporter were studied in the ectomycorrhizal fungus Paxillus involutus (Batsch) Fr. uptake acids showed features characteristic active transport. After correction for non-mediated transport component, kinetics glutamate, glutamine, alanine aspartate measured over wide concentration range followed simple Michaelis-Menten saturation curves. apparent K m derived from Eadie-Hofstee plots ranged 7 μM to 27 glutamate....

A hemagglutinating and hemolytic lectin (PSL) has been isolated from carpophores of the parasitic mushroom Laetiporus sulfureus by affinity chromatography on Sepharose. Its molecular weight, as determined both gel filtration electrophoresis in non-denaturing conditions, is about 190,000 its structure tetrameric, with two distinct types subunits (about 60,000 36,000). It appeared homogeneous HPLC but exhibited microheterogeneity isoelectric focusing. Hapten inhibition assay indicated that...

Using [(14)C]methylamine as an analogue of ammonium, the kinetics and energetics NH(4)(+) transport were studied in ectomycorrhizal fungus, Paxillus involutus (Batsch) Fr. The apparent half-saturation constant (K(m)) maximum uptake rate (V(max)) for carrier-mediated derived from Eadie-Hofstee transformation 180 µM 380 nmol (mg dry wt)(-1) min(-1,) respectively. Both pH dependence inhibition by protonophores indicate that methylamine P. was dependent on electrochemical H(+) gradient....

SUMMARY The nicotinamide adenine dinucleotide phosphate‐specific glutamate dehydrogenase (L‐gluta‐mate: NADP + oxido‐reductase, ECI .4.1 .4) of the ectomycorrhizal Ascomycete Cenococcum graniforme was purified twofold to electrophoretic homogeneity. native enzyme shown have a molecular weight 320000 and be composed six identical subunits with 48 000. pH optimum for animating reaction 7.6 NADP‐GDH showed negative co‐operativity respect ammonia ( K m1 :2mM, m2 :8 mM). m values α‐ketoglutarate...

Mycorrhizas of <em>Pinus sylvestris</em>, collected from zinc wastes in Poland and France were investigated using transmission electron microscope (TEM) scanning (SEM) equipped with energy dispersion spectroscopy (EDS) loss (EELS). At both sites, mycorrhizas <em>Hebeloma</em> the most frequent, however, they often characterised by a sparse or only locally developed fungal mantle. formed suilloid fungi much less usually produced clearly defined mantle abundant...

summary Previous studies of nitrogen‐assimilating enzymes in ectomycorrhizal associations the Pinaceae (Norway spruce, Douglas fir) and Fagaceae (beech) have suggested that host plant may regulate expression some fungal enzymes. To improve our understanding regulation plants, we extended this work to a third family, Myrtaceae. Glutamate dehydrogenases, specific either for NAD (NAD‐GDH) or NADP (NADP‐GDH), aspartate amminotransferase (AAT) were investigated by enzyme assays electrophoretic...