Disentangling the factors of contrasting silver and copper accumulation in sporocarps of the ectomycorrhizal fungus Amanita strobiliformis from two sites.

Amanita strobiliformis (European Pine Cone Lepidella) is an ectomycorrhizal fungus of the Amanitaceae family known to hyperaccumulate Ag in the sporocarps. Two populations (ecotypes) of A. strobiliformis collected from two urban forest plantations in Prague, Czech Republic, were investigated. The concentrations of Ag, Cu, Cd, and Zn were determined in the mushrooms. The metal mobility and fractionation in the soils was investigated by single extractions and sequential extraction. The soil distribution of A. strobiliformis mycelium was assessed by quantitative polymerase chain reaction (qPCR). The metal uptake from the soil into the mushroom sporocarps was traced by Pb isotopic fingerprinting. The findings suggested that A. strobiliformis (i) accumulates primarily Ag from the topsoil layer (circa 12cm deep) and (ii) accumulates Ag associated with the "reducible soil fraction". The concentrations of all metals, particularly Ag and Cu, were significantly higher in the A. strobiliformis sporocarps from one of the investigated sites (Klícov). The elevated concentrations of Ag in the sporocarps from Klícov can possibly be attributed to the higher Ag content in the topsoil layer found at this site. However, the simultaneously elevated concentrations of Cu in A. strobiliformis from Klícov cannot be explained by the differences in the geochemical background and should be attributed to biological factors.

The effect of A163G polymorphism in the osteoprotegerin gene on osteoporosis related traits in Slovak postmenopausal women.

Osteoprotegerin (OPG) plays an important role in the osteoclast differentiation as an effective inhibitor of osteoclast maturation and activation. We examined a potential effect of A163G single nucleotide polymorphism in the promoter region of the OPG gene on femoral neck (FN-BMD) and lumbar spine BMD (LS-BMD), as well as circulating alkaline phosphatase, osteocalcin (ALP, OC; formation markers), beta-CrossLaps (CTx; resorption marker) in Slovak postmenopausal women. In addition, fractures of spine, radius and femur were examined.Altogether 284 women (62.28 ± 8.40 years) were selected according to strict inclusion criteria. The polymorphism was detected by PCR-RFLP method. Genotype frequencies were tested using the chi-square test. The differences of quantitative variables between the genotypes were analyzed by covariance analysis (GLM procedure) after correction of the measurements for age and BMI. Fracture incidence in association with OPG genotype was evaluated by Binary Logistic Regression with the genotype, age, and BMI as covariates. The frequencies of genotypes were 76.8 %, 21.1 %, and 2.1 % for AA, AG, and GG, respectively. Statistically significant associations of OPG genotypes with FN-BMD (p < 0.01) and LS-BMD (p < 0.05) were observed. The GG genotype was associated with higher BMD values likewise decreased CTx concentration (p < 0.05) in compared with the other genotypes, which indicates that the allele G has a protective effect on bone. These associations were not followed by the effect of OPG on fracture incidence. Our results suggest that OPG/A163G polymorphism could contribute to the genetic regulation of BMD or bone turnover markers in Slovak population and thus could increase or decreased osteoporosis risk.

Chronic hypoxia inhibits tetrahydrobiopterin-induced NO production in rat lungs.

Tetrahydrobiopterin (BH4) is an essential cofactor for nitric oxide synthases (NOS). Oxidative stress oxidises BH4 to dihydrobioptein (BH2), resulting in the uncoupling of the two enzymatic domains of NOS and the production of superoxide rather than NO (NOS uncoupling). Oxidative stress is known to be increased in the early stage of chronic hypoxia. This study investigated the participation of NOS uncoupling in the early phase of hypoxia-induced pulmonary hypertension in rats. Rats were exposed to 10% O(2) for 4 days. We investigated the effect of BH4 in vitro on isolated rat lungs and isolated rat peripheral pulmonary blood vessels and in vivo on exhaled NO concentration in exhaled air. BH4 attenuated hypoxic pulmonary vasoconstriction in isolated lungs and its effect was reversed by l-NAME (NOS inhibitor). The main finding of the study is that the effect of BH4 was smaller in rats exposed to 4 days of hypoxia than in normoxic controls. The finding was similar in isolated pulmonary blood vessels. BH4 increased exhaled NO in both normoxic and hypoxic rats. This increase was blunted by l-NIL (specific iNOS inhibitor) and therefore attributable to iNOS. We conclude that BH4 increased NO production in both normoxic and hypoxic rats. The increase was, however, smaller in hypoxic lungs than in controls. We assume that the smaller increase in NO production in hypoxic lungs is due to the decreased BH4/BH2 ratio in chronic hypoxia and NOS uncoupling resulting from this condition.