Does the lichen mat alleviate the effects of wet deposited nickel on soil microorganisms and Scots pine (Pinus sylvestris L.) seedlings?

A field experiment was conducted in a dry heath forest dominated by Scots pine (Pinus sylvestris L.) and a mat-forming lichen (Cladina stellaris (Opiz) Brodo) to assess the effect of wet-deposited nickel (Ni) on pine seedlings and soil microorganisms, and to explore whether an intact lichen mat could act as a buffer against heavy metal deposits. Pine seedlings were planted in quadrats covered by a natural lichen layer and in quadrats from which the lichen layer had been completely removed. The quadrats were exposed to four levels of Ni deposition: 0 (i.e., distilled water), 10, 100 and 1000 mg m^–2 year^–1 in two growing seasons. Increasing Ni deposition led to an increase in the Ni content of the needles, roots and the soil organic layer. The lichen mat reduced Ni flow to the organic soil layer, but had no significant, reducing effect on needle or root Ni concentration. The most severe Ni treatment had detrimental effects on seedling growth and increased peroxidase activity in the previous years needles. Removal of the lichen layer did not increase susceptibility of seedlings to Ni. Values of maximal carbon use efficiency (Max) and metabolic quotient (qCO₂) of the soil microorganisms indicated protective value of the lichen mat to soil microorganisms at the highest Ni treatment. Skimming per se decreased basal respiration, qCO₂ and concentrations of potassium in the soil and also increased the lag period of the microorganisms as a response to in situ substrate addition.     

Binding of N- and C-terminal anti-prion protein antibodies generates distinct phenotypes of cellular prion proteins (PrPC) obtained from human, sheep, cattle and mouse

Prion diseases are neurodegenerative disorders which cause Creutzfeldt-Jakob disease in humans, scrapie in sheep and bovine spongiform encephalopathy in cattle. The infectious agent is a protease resistant isoform (PrP(Sc)) of a host encoded prion protein (PrP(C)). PrP(Sc) proteins are characterized according to size and glycoform pattern. We analyzed the glycoform patterns of PrP(C) obtained from humans, sheep, cattle and mice to find interspecies variability for distinct differentiation among species. To obtain reliable results, the imaging technique was used for measurement of the staining band intensities and reproducible profiles were achieved by many repeated immunoblot analysis. With a set of antibodies, we discovered two distinct patterns which were not species-dependent. One pattern is characterized by high signal intensity for the di-glycosylated isoform using antibodies that bind to the N-terminal region, whereas the other exhibits high intensity for protein bands at the size of the nonglycosylated isoform using antibodies recognizing the C-terminal region. This pattern is the result of an overlap of the nonglycosylated full-length and the glycosylated N-terminal truncated PrP(C) isoforms. Our data demonstrate the importance of antibody selection in characterization of PrP(C).     

EcM fungal community structure, but not diversity, altered in a Pb-contaminated shooting range in a boreal coniferous forest site in Southern Finland

Boreal forests contain diverse fungal communities that form essential ectomycorrhizal symbioses with trees. To determine the effects of lead (Pb) contamination on ectomycorrhizal fungal communities associated with the dominant pine (Pinus sylvestris L.), we surveyed sporocarps for 3 years, analyzed morphotyped ectomycorrhizal root tips by direct sequencing, and 454-sequenced fungal communities that grew into in-growth bags during a 2-year incubation at a shooting range where sectors vary in the Pb load. We recorded a total of 32 ectomycorrhizal fungi that formed conspicuous sporocarps, 27 ectomycorrhizal fungal phylotypes from 294 root tips, and 116 ectomycorrhizal fungal operation taxonomic unit (OTUs) from a total of 8194 internal transcribed spacer-2 454 sequences. Our ordination analyses by nonparametric multidimensional scaling (NMS) indicated that the Pb enrichment induced a shift in the ectomycorrhizal community composition. This was visible as indicative trends in the sporocarp and root tip data sets, but was explicitly clear in the communities observed in the in-growth bags. The compositional shift in the ectomycorrhizal community was mainly attributable to an increase in the frequencies of OTUs assigned to genus Thelephora and to a decrease in the OTUs assigned to Pseudotomentella, Suillus, and Tylospora in Pb-contaminated areas when compared with the control. While the compositional shifts are clear, their functional consequences for the dominant trees or soil ecosystem function remain undetermined.     

Ammonia-excreting mutants ofKlebsiella pneumoniae with a pleiotropic defect in nitrogen metabolism

Enterobacterial mutants defective in the nitrogen control regulatory system (Ntr) generally display a pleiotropic phenotype with regard to expression and regulation of several enzymes and transport systems involved in the assimilation of N sources. This report describes the isolation and characterization of similar pleiotropic mutants ofKlebsiella pneumoniae that cannot be complemented byntr genes. The strains excreted ammonia, were unable to grow on a number of N sources, and contained low glutamine:2-oxoglutarate amino transferase and normal, but unmodifiable glutamine synthetase activities and a nitrogenase level largely unaffected by ammonium, but still repressible by an amino acid mixture. Genetic studies suggested that this phenotype is due to overexpression of an unknown regulatory protein.Abbreviations GS Glutamine synthetase - GOGAT Glutamate synthase - ATase Adenylyl transferase - Ntr Nitrogen regulatory system     

Differences in proteinase K resistance and neuronal deposition of abnormal prion proteins characterize bovine spongiform encephalopathy (BSE) and scrapie strains.

Prion diseases are associated with the accumulation of an abnormal isoform of host-encoded prion protein (PrP(Sc)). A number of prion strains can be distinguished by "glycotyping" analysis of the respective deposited PrP(Sc) compound. In this study, the long-term proteinase K resistance, the molecular mass, and the localization of PrP(Sc) deposits derived from conventional and transgenic mice inoculated with 11 different BSE and scrapie strains or isolates were examined. Differences were found in the long-term proteinase K resistance (50 microg/ml at 37 degrees C) of PrP(Sc). For example, scrapie strain Chandler or PrP(Sc) derived from field BSE isolates were destroyed after 6 hr of exposure, whereas PrP(Sc) of strains 87V and ME7 and of the Hessen1 isolate were extremely resistant to proteolytic cleavage. Nonglycosylated, proteinase K-treated PrP(Sc) of BSE isolates and of scrapie strain 87V exhibited a 1-2 kD lower molecular mass than PrP(Sc) derived from all other scrapie strains and isolates. With the exception of strain 87V, PrP(Sc) was generally deposited in the cerebrum, cerebellum, and brain stem of different mouse lines at comparable levels. Long-term proteinase resistance, molecular mass, and the analysis of PrP(Sc) deposition therefore provide useful criteria in discriminating prion strains and isolates (e.g., BSE and 87V) that are otherwise indistinguishable by the PrP(Sc) "glycotyping" technique.     

Metabolic profiles in five high-producing Swedish dairy herds with a history of abomasal displacement and ketosis

Background  

Body condition score and blood profiles have been used to monitor management and herd health in dairy cows. The aim of this study was to examine BCS and extended metabolic profiles, reflecting both energy metabolism and liver status around calving in high-producing herds with a high incidence of abomasal displacement and ketosis and to evaluate if such profiles can be used at herd level to pinpoint specific herd problems.     

Non-parallel changes in soil microbial carbon and nitrogen dynamics due to reindeer grazing in northern boreal forests

Reindeer grazing has a considerable influence on mineralization processes in northern Fennoscandian boreal forests, but the mechanisms underlying the observed differences between grazed and ungrazed areas are not well understood. We studied the below-ground impacts of reindeer grazing by comparing the carbon and nitrogen mineralization rates inside and outside long-term fenced reindeer exclosure areas in five oligotrophic, lichen-dominated and five mesotrophic, dwarf-shrub dominated forests. The soil C mineralization rates and microbial metabolic activity (qCO₂) were significantly lower in the grazed than the ungrazed areas in both oligotrophic and mesotrophic forests. The reductions occurred irrespective of the impact on soil moisture. We conclude that reindeer grazing causes a reduction in the supply of labile C substrates to microbes, resulting in reduced organic matter decomposition rates through changes in the activity of the microbial biomass. Simultaneously, grazing had no consistent effect on the microbial N dynamics, but the impact ranged from no change to increased or decreased in N mineralization rates at the different study sites. The impact of grazing on the N mineralization potential thus seems to be site-specific and uncoupled from the impact of grazing on soil C mineralization. Reciprocal transplant incubations showed no interactions between N mineralization rates and the reindeer-mediated impact on the soil microclimate. We suggest that plant root damage due to trampling by reindeer may be an important mechanism for the deceleration of soil C cycling. In some cases, however, the impact of grazing on the soil active N pool may be strong enough to outweigh the reduction in soil organic matter decomposition, and by these means uncouple soil N dynamics from soil C quality.     

Cellular prion proteins in human platelets show a phenotype different to those in brain tissues

Prion diseases are characterized by high accumulation of infectious prion proteins (PrP(Sc)) in brains. PrP(Sc) are propagated by the conversion of host-encoded cellular prion proteins (PrP(C)) which are essential for developing the disease but are heterogeneously expressed in brains. The disease can be transmitted to humans and animals through blood and blood products, however, little attention has been given to molecular characterization of PrP(C) in blood cells. In this presented study, we characterized phenotypically PrP(C) of platelets (plt) and characterized the proteins regarding their glycobanding profiles by quantitative immunoblotting using a panel of monoclonal antibodies. The glycosylation patterns of plt and brain PrP(C) were compared using the ratios of di-, mono-, and non-glycosylated prions. The detergent solubility of plt and brain PrP(C) was also analyzed. The distinct banding patterns and detergent solubility of plt PrP(C) differed clearly from the glycosylation profiles and solubility characteristics of brain PrP(C). Plt PrP(C) exhibited single or only few prion protein types, whereas brain PrP(C) showed more extensive banding patterns and lower detergent solubility. Plt PrP(C) are post-translational modified differently from PrP(C) in brain. These findings suggest other or less physiological functions of plt PrP(C) than in brain.