Growth on nitrate and occurrence of nitrate reductase-encoding genes in a phylogenetically diverse range of ectomycorrhizal fungi

Ectomycorrhizal (ECM) fungi are often considered to be most prevalent under conditions where organic sources of N predominate. However, ECM fungi are increasingly exposed to nitrate from anthropogenic sources. Currently, the ability of ECM fungi to metabolize this nitrate is poorly understood. Here, growth was examined among 106 isolates, representing 68 species, of ECM fungi on nitrate as the sole N source. In addition, the occurrence of genes coding for the nitrate reductase enzyme (nar gene) in a broad range of ectomycorrhizal fungi was investigated. All isolates grew on nitrate, but there was a strong taxonomic signature in the biomass production, with the Russulaceae and Amanita showing the lowest growth. Thirty-five partial nar sequences were obtained from 43 tested strains comprising 31 species and 10 genera. These taxa represent three out of the four clades of the Agaricales within which ECM fungi occur. No nar sequences were recovered from the Russulaceae and Amanita, but Southern hybridization showed that the genes were present. The results demonstrate that the ability to utilize nitrate as an N source is widespread in ECM fungi, even in those fungi from boreal forests where the supply of nitrate may be very low.     

Modeling Solute Transport by DLA in Soils of Northeastern Egypt

Arid soils in Egypt display large variability in solute transport properties, causing problems in soil management. To characterize this variability, dye infiltration experiments were conducted on four plots representing three main soil types in northeastern Egypt. The plots represented both cultivated and uncultivated land use. The observed dye patterns displayed a large variability and especially the clay soils indicated a high degree of preferential flow. The loamy sand and sandy soils displayed a more uniform dye distribution indicating more homogeneous soil properties. The observed dye patterns were modeled using a diffusion limited aggregation (DLA) model. The DLA is a random walk model where model parameters can be optimized using genetic algorithms (GA). The DLA model reproduced the observed dye patterns for all soils in an excellent way. The best fit was obtained with a specific combination of directional random walk probabilities P_u, P_d, P_r, and P_l for each plot (correlation 0.97–0.99). To account for soil layers with different hydraulic properties a two layer DLA model was developed. For all plots the P_u (upward random walk probability) was higher for the upper more homogeneous soil layer. The overall results showed that spatial variability resulting from solute transport for the investigated soils can be modeled using a DLA approach.     

Different HLA-DRB1 allele distributions in distinct clinical subgroups of sarcoidosis patients

Background

A strong genetic influence by the MHC class II region has been reported in sarcoidosis, however in many studies with different results. This may possibly be caused by actual differences between distinct ethnic groups, too small sample sizes, or because of lack of accurate clinical subgrouping.

Subjects and methods

In this study we HLA typed a large patient population (n = 754) recruited from one single centre. Patients were sub-grouped into those with Löfgren''s syndrome (LS) (n = 302) and those without (non-Löfgren''s) (n = 452), and the majority of them were clinically classified into those with recovery within two years (resolving) and those with signs of disease for more than two years (non-resolving). PCR was used for determination of HLA-DRB1 alleles. Swedish healthy blood donors (n = 1366) served as controls.

Results

There was a dramatic difference in the distribution of HLA alleles in LS compared to non-LS patients (p = 4 × 10^-36). Most notably, DRB1*01, DRB1*03 and DRB1*14, clearly differed in LS and non-LS patients. In relation to disease course, DRB1*07, DRB1*14 and DRB1*15 generally associated with, while DRB1*01 and DRB1*03 protected against, a non-resolving disease. Interestingly, the clinical influence of DRB1*03 (good prognosis) dominated over that of DRB1*15 (bad prognosis).

Conclusions

We found several significant differences between LS and non-LS patients and we therefore suggest that genetic association studies in sarcoidosis should include a careful clinical characterisation and sub-grouping of patients, in order to reveal true genetic associations. This may be particularly accurate to do in the heterogeneous non-LS group of patients.     

Light-induced multistep oxidation of dinuclear manganese complexes for artificial photosynthesis

Two dinuclear manganese complexes, [Mn(2)BPMP(mu-OAc)(2)].ClO(4) (1, where BPMP is the anion of 2,6-bis([N,N-di(2-pyridinemethyl)amino]methyl)-4-methylphenol) and [Mn(2)L(mu-OAc)(2)].ClO(4) (2, where L is the trianion of 2,6-bis([N-(2-hydroxy-3,5-di-tert-butylbenzyl)-N-(2-pyridinemethyl)amino]methyl)-4-methylphenol), undergo several oxidations by laser flash photolysis, using ruthenium(II)-tris-bipyridine (tris(2,2-bipyridyl)dichloro-ruthenium(II) hexahydrate) as photo-sensitizer and penta-amminechlorocobalt(III) chloride as external electron acceptor. In both complexes stepwise electron transfer was observed. In 1, four Mn-valence states from the initial Mn(2)(II,II) to the Mn(2)(III,IV) state are available. In 2, three oxidation steps are possible from the initial Mn(2)(III,III)state. The last step is accomplished in the Mn(2)(IV,IV) state, which results in a phenolate radical. For the first time we provide firm spectral evidence for formation of the first intermediate state, Mn(2)(II,III), in 1 during the stepwise light-induced oxidation. Observation of Mn(2)(II,III) is dependent on conditions that sustain the mu-acetato bridges in the complex, i.e., by forming Mn(2)(II,III) in dry acetonitrile, or by addition of high concentrations of acetate in aqueous solutions. We maintain that the presence of water is necessary for the transition to higher oxidation states, e.g., Mn(2)(III,III) and Mn(2)(III,IV) in 1, due to a bridging ligand exchange reaction which takes place in the Mn(2)(II,III) state in water solution. Water is also found to be necessary for reaching the Mn(2)(IV,IV) state in 2, which explains why this state was not reached by electrolysis in our earlier work (Eur. J. Inorg. Chem (2002) 2965). In 2, the extra coordinating oxygen atoms facilitate the stabilization of higher Mn valence states than in 1, resulting in formation of a stable Mn(2)(IV,IV) without disintegration of 2. In addition, further oxidation of 2, led to the formation of a phenolate radical (g = 2.0046) due to ligand oxidation. Its spectral width (8 mT) and very fast relaxation at 15 K indicates that this radical is magnetically coupled to the Mn(2)(IV,IV) center.     

Calcium-regulating peptide hormones and blood electrolytic balance in chronic heart failure

Calcium-regulating system is important for the functional activity of myocardium. However, little is known about the role of this system in the pathogenesis of cardiovascular diseases. Blood samples from the patients with chronic heart failure (CHF) caused by ischaemic disease (coronary artery disease) (NYHA class I-IV) were used to analyze the levels of calcium, inorganic phosphate, sodium, potassium, parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP). The heart beat rate and arterial blood pressure were chosen as additional tests for the functional status of cardiovascular system. The alteration of electrolytes homeostasis was found dependent on the severity of the pathology being maximally expressed in the NYHA class IV patients. Similar tendency was demonstrated for circulating PTH and PTHrP with the highest blood concentrations observed in patients of the NYHA class III and IV. The extent of these changes was found more pronounced in the female patients. It is suggested that the calcium-regulating hormonal system is involved in the pathogenesis of the ischaemic heart disease; however the sharp increase of PTH and PTHrP at the severe stages of pathology may play a compensatory role in maintaining the heart function.     

3'-UTR polymorphism in the human CYP2A6 gene affects mRNA stability and enzyme expression

Cytochrome P450 2A6 (CYP2A6) is the major nicotine C-oxidase in human and participates in the metabolism of drugs and precarcinogens. The CYP2A6 gene is highly polymorphic and more than 22 different alleles have been described. We here focused on the polymorphism in the 3'-UTR region, in particular the common CYP2A6*1B allele, carrying an unequal crossover element from the pseudogene CYP2A7. Analysis of CYP2A6 expression in a human liver bank (n=46) revealed that the protein level and catalytic activity using coumarin as a substrate were all higher, following a linear gene-dose relationship, in livers carrying one or two copies of CYP2A6*1B, as compared to other CYP2A6 allelic variants. Different variants of the CYP2A6 3'-UTR were cloned into a modified pGL3 plasmid downstream of the luciferase reporter gene. The plasmids, having the proximal promoter of CYP2A6 gene, were transfected into HeLa cells or injected into the tail veins of male CD1 mice. In both systems, the 3'-UTR CYP2A6*1B constructs caused higher reporter gene activity and the CYP2A7 3'-UTR construct lower activity, compared to the CYP2A6*1 3'-UTR constructs. Two SNPs differentiating the 3'-UTR between CYP2A7 and CYP2A6*1B were found to be of importance for the expression in both systems. Analysis of reporter enzyme degradation in HeLa cells showed that luciferase-3'-UTR-CYP2A6*1A had a half-life of approximately 4.9h as compared to 6.3h for luciferase-3'-UTR-CYP2A6*1B. In conclusion, we identified polymorphic motifs in the CYP2A6 3'-UTR of importance for CYP2A6 mRNA stabilization and enzyme expression. Such polymorphism has been described to influence the in vivo rate of nicotine elimination and possibly the cigarette consumption and risk of smoking induced lung cancer.     

Pervasive associations between Cybaeus spiders and the bacterial symbiont Cardinium

Cardinium is a recently discovered maternally transmitted bacterial endosymbiont in the Bacteroidetes that has thus far been documented in five arthropod orders. While its effects on his hosts are largely unknown, a few strains have been shown to manipulate host reproduction in parasitic wasps and in mites, either by transforming males into females, or by causing mating incompatibilities between infected males and uninfected males. Cardinium has recently been reported to be widespread in spiders, and in this study, we document pervasive infections in Cybaeus spiders, which are some of the most abundant yet understudied spiders in the understory of moist Western North American forests. 12/20 species, as well as 96% of individuals in a local population of Cybaeus signifer were infected. Phylogenetic analysis revealed three closely related symbiont haplotypes within Cybaeus. Haplotypes clustered within geographically close species, suggesting that horizontal transmission might be quite high in this symbiont lineage.