Evaluation of Mercury Contamination in Fungi Boletus Species from Latosols,Lateritic Red Earths,and Red and Yellow Earths in the Circum-Pacific Mercuriferous Belt of Southwestern China

For the first time, highly elevated levels of mercury (Hg) have been documented for several species of the edible Fungi genus Boletus growing in latosols, lateritic red earths, and red and yellow earths from the Yunnan province of China. Analysis of Hg concentrations in the genus suggests that geogenic Hg is the dominant source of Hg in the fungi, whereas anthropogenic sources accumulate largely in the organic layer of the forest soil horizon. Among the 21 species studied from 32 locations across Yunnan and 2 places in Sichuan Province, the Hg was found at elevated level in all samples from Yunnan but not in the samples from Sichuan, which is located outside the mercuriferous belt. Particularly abundant in Hg were the caps of fruiting bodies of Boletus aereus (up to 13 mg kg^-1 dry matter), Boletus bicolor (up to 5.5 mg kg^-1 dry matter), Boletus edulis (up to 22 mg kg^-1 dry matter), Boletus luridus (up to 11 mg kg^-1 dry matter), Boletus magnificus (up to 13 mg kg^-1 dry matter), Boletus obscureumbrinus (up to 9.4 mg kg^-1 dry matter), Boletus purpureus (up to 16 mg kg^-1 dry matter), Boletus sinicus (up to 6.8 mg kg^-1 dry matter), Boletus speciosus (up to 4.9mg kg^-1 dry matter), Boletus tomentipes (up to 13 mg kg^-1 dry matter), and Boletus umbriniporus (up to 4.9 mg kg^-1 dry matter). Soil samples of the 0–10 cm topsoil layer from the widely distributed locations had mercury levels ranging between 0.034 to 3.4 mg kg^-1 dry matter. In Yunnan, both the soil parent rock and fruiting bodies of Boletus spp. were enriched in Hg, whereas the same species from Sichuan, located outside the mercuriferous belt, had low Hg concentrations, suggesting that the Hg in the Yunnan samples is mainly from geogenic sources rather than anthropogenic sources. However, the contribution of anthropogenically-derived Hg sequestered within soils of Yunnan has not been quantified, so more future research is required. Our results suggest that high rates of consumption of Boletus spp. from Yunnan can deliver relatively high doses of Hg to consumers, but that rates can differ widely because of large variability in mercury concentrations between species and locations.     

Hypersensitive mung bean nuclease cleavage sites in Plasmodium knowlesi DNA

Nucleotide sequences of Plasmodium knowlesi DNA that are cleaved by mung bean nuclease (Mbn) at low enzyme concentration (0.2 units enzyme per micrograms DNA) are listed. They are tandemly repeated purine/pyrimidine (RpY) stretches of DNA with (ApT) dimers predominating. Most cut sites are within almost 100% RpY tracts. The enzyme cleaves at many points within the RpY stretch and usually hydrolyzes the 5'-ApT-3' linkage. These alternating RpY target sites are flanked by homopurine and homopyrimidine stretches. At least one Mbn target site lies next to an in vivo transcribed region.     

Flavonoids enantiomer distribution in different parts of goldenrod (Solidago virgaurea L.), lucerne (Medicago sativa L.) and phacelia (Phacelia tanacetifolia Benth.)

Plant material is a rich source of valuable compounds such as flavanones. Their different forms influence bioavailability and biological activity, causing problems with the selection of plant material for specific purposes. The purpose of this research was to determine selected flavanone (eriodictyol, naringenin, liquiritigenin, and hesperetin) enantiomer contents in free form and bonded to glycosides by an RP‐UHPLC‐ESI‐MS/MS method. Different parts (stems, leaves, and flowers) of goldenrod (Solidago virgaurea L.), lucerne (Medicago sativa L.), and phacelia (Phacelia tanacetifolia Benth.) were used. The highest content of eriodictyol was found in goldenrod flowers (13.1 μg/g), where it occurred mainly as the (S)‐enantiomer, and the greatest proportion of the total amount was bonded to glycosides. The richest source of naringenin was found to be lucerne leaves (4.7 μg/g), where it was mainly bonded to glycosides and with the (S)‐enantiomer as the dominant form. Liquiritigenin was determined only in lucerne, where the flowers contained the highest amount (1.2 μg/g), with the (R)‐enantiomer as dominant aglycone form and the (S)‐enantiomer as the dominant glycosylated form. The highest hesperetin content was determined in phacelia leaves (0.38 μg/g), where it was present in the form of a glycoside and only as the (S)‐enantiomer. A comparison of the different analyte forms occurring in different plant parts was performed for the first time.     

TheisfA mutation inhibits mutator activity and processing of UmuD protein inEscherichia coli recA730 strains

Further studies on theisfA mutation responsible for anti-SOS and antimutagenic activities inEscherichia coli are described. We have previously shown that theisfA mutation inhibits mutagenesis and other SOS-dependent phenomena, possibly by interfering with RecA coprotease activity. TheisfA mutation has now been demonstrated also to suppress mutator activity inE. coli recA730 andrecA730 lexA51(Def) strains that constitutively express RecA coprotease activity. We further show that the antimutator activity of theisfA mutation is related to inhibition of RecA coprotease-dependent processing of UmuD. Expression of UmuD' from plasmid pGW2122 efficiently restores UV-induced mutagenesis in therecA730 isfA strain and partially restores its mutator activity. On the other hand, overproduction of UmuD'C proteins from pGW2123 plasmid markedly enhances UV sensitivity with no restoration of mutability.     

Solving the N-Queens problem with a binary Hopfield-type network

The application of a discrete Hopfield-type neural network to solving the NP-Hard optimization problem — the N-Queens Problem (NQP) — is presented. The applied network is binary, and at every moment each neuron potential is equal to either 0 or 1. The network can be implemented in the asynchronous mode as well as in the synchronous one with n parallel running processors. In both cases the convergence rate is up to 100%, and the experimental estimate of the average computational complexity is polynomial. Based on the computer simulation results and the theoretical analysis, the proper network parameters are established. The behaviour of the network is explained.     

In vitro effects of genistein and resveratrol on the production of interferon-gamma (IFNgamma) and interleukin-10 (IL-10) by stimulated murine splenocytes.

Phytoestrogens are a group of plant-derived biologically active substances with a chemical structure that resembles that of 17beta-estradiol (E2). As the presence of estrogen receptors (ER) has been identified in several immune cells, phytoestrogens may also have a great impact on the immune system. The aim of our study was to determine the in vitro effects of genistein and resveratrol on the production of interferon-gamma (IFNgamma) and interleukin-10 (IL-10) by stimulated murine splenocytes and compare them with the effects of natural E2. Phorbol 12-miristate 13-acetate (PMA) together with ionomycin was used to stimulate the cells. E2 and genistein did not show any significant effects on the stimulated production of IFNgamma. Resveratrol had a mild inhibitory effect on IFNgamma production at the concentration of 10(-7)M; however, this difference did not reach statistical significance (p>0.05). IL-10 levels in the splenocytes culture supernatants were found to be increased in the presence of E2, genistein and resveratrol; however, these effects were also not statistically significant. To determine whether the exposure to our studied phytoestrogens induced a shift in the T-helper 1/T-helper 2 (Th1/Th2) balance, we calculated the ratio between the production of IFNgamma, the prototypic Th1 cytokine, and the production of IL-10, the prototypic Th2 cytokine, at different concentrations of our tested substances. Genistein at the concentrations of 10(-6) and 10(-7)M and resveratrol at the concentrations of 10(-6)M decreased significantly the IFNgamma/IL-10 ratio. This decrease was comparable to that of E2 at the concentrations of 10(-7)M. From our in vitro experiments we conclude that genistein and resveratrol, similarly to E2, by decreasing the IFNgamma/IL10 ratio may shift the Th1/Th2 balance towards the Th2 response.     

Concentrations of Metals in Maxilla and Mandible Deciduous and Permanent Human Teeth

The study shows the results of research on the concentrations of metals (Cd, Pb, Mn, Cu, Cr, Fe, Zn, Na, K, Mg, and Ca) in deciduous and permanent teeth with respect to their location in the oral cavity (maxilla, mandible). It has been found that the concentrations of metals were significantly higher in the deciduous teeth than in permanent ones. Regression analysis and principal component analysis revealed an increased dynamics of the processes of binding the elements by the hydroxyapatite of deciduous teeth. Higher concentrations of the metals were found in the maxilla permanent and deciduous teeth than in the mandible ones.