Effect of the external electric field on selected tripeptides.

The effect of external electric field (EEF) of 5.14, 25.70, and 51.40 MV/cm upon Cys-Asn-Ser, Glu-Arg-Leu, Glu-Cys-Glc, Ser-Asp-Leu, Ser-Glu-Met tripeptide inner salts was simulated involving HyperChem 8.0 software together with the AM1 method for optimization of the molecules' conformation. The reaction to EEF is diverse and specific to particular peptides. EEF stimulated an increase in the positive charge density on the hydrogen atoms of the N(+)H3, peptide bond NH, NH2, and COOH groups as well decrease in the negative charge density on the oxygen atoms of the peptide bond carbonyl groups. Thus, EEF could control behavior and action of tripeptides, such as an increase in their catalytic activity.

Inhibition of autophagy by 3-methyladenine potentiates sulforaphane-induced cell death of BE(2)-C human neuroblastoma cells.

Sulforaphane (SFN) is an isothiocyanate present in cruciferous vegetables, which has been shown to exert an anti-cancer effect when tested in vitro and in vivo. The anti-cancer effects of SFN encompass induction of cytoprotective autophagy; therefore, the present study aimed to determine whether the chemopreventive activity of SFN may be potentiated by inhibition of autophagy. The present study provided detailed insight into the susceptibility of human neuroblastoma cells to treatment with synthetic SFN, in combination with an inhibitor of autophagy, 3-methyladenine (3-MA). The present study confirmed the suppression of the viability of the human neuroblastoma cell line BE(2)-C by SFN and reported the inhibition of DNA synthesis, as determined by a decrease in tritiated thymidine incorporation. Furthermore, the results verified the effectiveness of SFN in inducing apoptosis in the BE(2)-C cell line as demonstrated by caspase activation, increased protein expression levels of B-cell lymphoma 2-associated X protein and loss of mitochondrial membrane potential. Combined treatment of the cells with SFN with 3-MA proved to be effective in decreasing cell viability, through a mechanism that may proceed via the early induction of autophagy by SFN, followed by induction of apoptosis, as well as inhibition of autophagy by 3-MA.

The kinetic reduction of Cr(VI) by yeast Saccharomyces cerevisiae, Phaffia rhodozyma and their protoplasts.

Chromium in the sixth oxidation state may easily penetrate cellular membranes via non-specific sulfate transporters due to its tetrahedral symmetry (high similarity to SO4(2-) and HPO4(2-)). This feature makes chromium a toxic and hazardous pollutant responsible for the deterioration of midland water quality. The aim of the study was to evaluate the capacity of two yeast species - Saccharomyces cerevisiae and Phaffia rhodozyma - and their protoplasts to reduce Cr(VI) to lower oxidation states. The study also deals with the behavior of the yeasts upon the presence of elevated sulfate ions as a competitive inhibitor of chromate transport by the sulfate transporters. The chromate-reducing activities were monitored by determination of Cr(V) free radical form with the use of L-band (1.2 GHz) EPR (electron paramagnetic resonance) spectroscopy. It was observed that both of the studied yeast strains exhibited the ability to reduce Cr(VI) applied at 4 mM. The cells of P. rhodozyma showed about 3.5 times higher reduction than S. cerevisiae. The reduction efficiency was significantly improved when the protoplasts of both strains were used and reached 100% in the first 10 minutes of the reduction process which suggests that the cellular wall may have a notable influence on the uptake and/or inhibition of chromium reduction process. The reduction effect of P. rhodozyma cells and protoplasts may be associated with the more sufficient production of metabolites (such as glutathione and cysteine), which may also be responsible for the increased tolerance of the strain towards high concentrations of toxic chromium.

Chromium(VI) bioremediation by aquatic macrophyte Callitriche cophocarpa Sendtn.

Callitriche cophocarpa (water-starwort)--aquatic widespread macrophyte--was found to be an excellent chromium accumulator. The plants were exposed to various chromium(VI) concentration ranging from 50 to 700 microM in a hydroponic culture up to ca. 3 weeks. Physiological conditions of shoots were monitored via measuring potential photosynthesis quantum efficiency (F(v)/F(m)) and photosynthetic pigment contents. Additionally, the structure of leaves was analyzed using optical and atomic force microscopy (AFM). It has been shown that plants grown in 50 microM Cr(VI) solution exhibited photosynthetic activity and shoot and leaf morphology similar to control plants. Moreover, at the same time the average Cr concentration in their shoots reached about 470 mg kg(-1)d.w. after 10d and up to 1000 mg kg(-1)d.w. after 3 weeks of culture while in control plants did not exceed a few mgkg(-1)d.w. Our results point to Callitriche cophocarpa as a very promising species to be used in the investigation of chromium(VI) phytoremediation mechanisms as well as a good candidate for wastewaters remediation purpose.

Methylotrophic extremophilic yeast Trichosporon sp.: a soil-derived isolate with potential applications in environmental biotechnology.

A yeast isolate revealing unique enzymatic activities and substrate-dependent polymorphism was obtained from autochthonous microflora of soil heavily polluted with oily slurries. By means of standard yeast identification procedures the strain was identified as Trichosporon cutaneum. Further molecular PCR product analyses of ribosomal DNA confirmed the identity of the isolate with the genus Trichosporon. As it grew on methanol as a sole carbon source, the strain appeared to be methylotrophic. Furthermore, it was also able to utilize formaldehyde. A multi-substrate growth potential was shown with several other carbon sources: glucose, glycerol, ethanol as well as petroleum derivatives and phenol. Optimum growth temperature was determined at 25 degrees C, and strong inhibition of growth at 37 degrees C together with the original soil habitat indicated lack of pathogenicity in warm-blooded animals and humans. The unusually high tolerance to xenobiotics such as diesel oil (>30 g/l), methanol (50 g/l), phenol (2 g/l) and formaldehyde (7.5 g/l) proved that the isolate was an extremophilic organism. With high-density cultures, formaldehyde was totally removed at initial concentrations up to 7.5 g/l within 24 h, which is the highest biodegradation capability ever reported. Partial biodegradation of methanol (13 g/l) and diesel fuel (20 g/l) was also observed. Enzymatic studies revealed atypical methylotrophic pathway reactions, lacking alcohol oxidase, as compared with the conventional methylotroph Hansenula polymorpha. However, the activities of glutathione-dependent formaldehyde dehydrogenase, formaldehyde reductase, formate dehydrogenase and unspecific aldehyde dehydrogenase(s) were present. An additional glutathione-dependent aldehyde dehydrogenase activity was also detected. Metabolic and biochemical characteristics of the isolated yeast open up new possibilities for environmental biotechnology. Some potential applications in soil bioremediation and wastewater decontamination are discussed.

Chromium accumulation by living yeast at various environmental conditions.

Yeast tolerance to Cr (III) and Cr (VI) as well as chromium accumulation potential were shown to depend on treatment time, metal concentration, biomass density and the phase of growth. Kinetic studies as exemplified by Pichia guilliermondii ATCC 201911 revealed a biphasic mode of Cr (III) uptake: a rapid sorption phase was followed by a slow process of accumulation, in which the contribution of the cell-bound Cr fraction increased, while the total cellular Cr level remained constant. Cr (VI) uptake was characterized by a time-dependent increase of total Cr and by a constant fractional contribution of the cell-adsorbed chromium, which suggests that the amount of cell-accumulated Cr also tended to increase over time. The resistance to Cr and metal accumulation levels were substantially elevated for a given strain when cultures were treated at high initial biomass densities (1 mg dry weight/ml) of exponentially proliferating cells. Maximum accumulation capabilities ranged between 4.0 and 13 mg Cr (III)/g dry weight and 2-6.7 mg Cr (VI)/g dry weight. The total cell-accumulated Cr contained 29.3% and 52.3% of organically bound chromium for the treatment of P. guilliermondii with Cr (III) and Cr (VI), respectively. Selected yeast strains, under specified physiological conditions, can be applied for bioremediation of environmental Cr contamination, and might be useful too for attempts to obtain chromium-enriched biomass containing biostabilized and nontoxic Cr forms for nutritional applications.

[Herb honey containing sulforaphane-aglycone with potential use in cancer prophylaxis]. / Ziolomiód zawierajacy sulforafan--aglikon o potencjalnej roli w profilaktyce chorób nowotworowych.

Cruciferous vegetables play an important role because of their sulphorafane contents which are enzymatically released from the glucosinolate known as glucoraphanin. The physiological properties of the compound exhibit antitumorigenic activity. The work describes the chloroform extraction method of sulforaphane from the broccoli and the preparation of sulforaphane sugar extract. The extract was then used to feed bees in a specially constructed beehive so that sulforaphane could be transformed into herbal honey. The concentration of sulforaphane was determined in the obtained herbal honey as high as 1.2 microM.

Bioremediation of chromium by the yeast Pichia guilliermondii: toxicity and accumulation of Cr (III) and Cr (VI) and the influence of riboflavin on Cr tolerance.

A comparative study has been made on the sensitivity of the yeast Pichia guilliermondii to Cr (III) and Cr (VI) as well as on the Cr uptake potential at growth-inhibitory concentrations of chromium. The strains used in the study were either isolated from natural sources or obtained from a laboratory strain collection. The results show that most of the natural strains were more tolerant to chromium and were able to grow in the presence of 5 mM Cr (III) or 0.5 mM Cr (VI), that is at concentrations which substantially inhibited the growth of laboratory strains. The cellular Cr content after treatment was similar for both strain types and ranged from 1.2-4.0 mg/g d.w. and 0.4-0.9 mg/g d.w., for Cr (III) and Cr (VI) forms, respectively, however, in one case of a natural strain it reached the value of 10 mg Cr (III)/g dry mass. Natural-source strains were grouped into four groups based on the yeasts' differential response to Cr (III) and Cr (VI). Hexavalent Cr-resistant mutants of a P. giuilliermondii laboratory strain, which revealed markedly changed capabilities of chromium accumulation, were obtained by means of UV-induced mutagenesis. Cr (VI) treatment triggered oversynthesis of riboflavin and the addition of exogenous riboflavin increased P. guilliermondii resistance to both Cr (III) and Cr (VI). Electrophoretic protein profiles revealed the induction and/or suppression of several proteins in response to toxic Cr (VI) levels.

Biodegradation of formaldehyde and its derivatives in industrial wastewater with methylotrophic yeast Hansenula polymorpha and with the yeast-bioaugmented activated sludge.

Methylotrophic yeast Hansenula polymorpha were shown to cooperate with activated sludge from biological wastewater treatment stations, enhancing substantially its potential to biodegrade formaldehyde in industrial wastewater. After integration with yeast cells the modified sludge retained its original structure and activity whereas its resistance to elevated formaldehyde concentrations was significantly improved. The applicability of the yeast in the utilization of formaldehyde derivatives, as exemplified by urotropine and trioxane, was also investigated. The treatment of urotropine-containing wastewater with methylotrophic yeast was found to be effective at acidic conditions (pH below 5.5). Trioxane was not degraded due to the stability of an ether bond which made themolecule recalcitrant to oxidation via methylotrophic pathway reactions. It is concluded that the yeast species may be applied to treat wastewater containing formaldehyde and some of its derivatives as either monocultures or as an integrated, specialized element of the activated sludge biocenosis.