Pavlina Sobrova

Deoxynivalenol and its toxicity.

Deoxynivalenol and its toxicity Deoxynivalenol (DON) is one of several mycotoxins produced by certain Fusarium species that frequently infect corn, wheat, oats, barley, rice, and other grains in the field or during storage. The exposure risk to human is directly through foods of plant origin (cereal grains) or indirectly through foods of animal origin (kidney, liver, milk, eggs). It has been detected in buckwheat, popcorn, sorgum, triticale, and other food products including flour, bread, breakfast cereals, noodles, infant foods, pancakes, malt and beer. DON affects animal and human health causing acute temporary nausea, vomiting, diarrhea, abdominal pain, headache, dizziness, and fever. This review briefly summarizes toxicities of this mycotoxin as well as effects on reproduction and their antagonistic and synergic actions.

Phytochelatin synthase activity as a marker of metal pollution.

The synthesis of phytochelatins is catalyzed by γ-Glu-Cys dipeptidyl transpeptidase called phytochelatin synthase (PCS). Aim of this study was to suggest a new tool for determination of phytochelatin synthase activity in the tobacco BY-2 cells treated with different concentrations of the Cd(II). After the optimization steps, an experiment on BY-2 cells exposed to different concentrations of Cd(NO(3))(2) for 3 days was performed. At the end of the experiment, cells were harvested and homogenized. Reduced glutathione and cadmium (II) ions were added to the cell suspension supernatant. These mixtures were incubated at 35°C for 30min and analysed using high performance liquid chromatography coupled with electrochemical detector (HPLC-ED). The results revealed that PCS activity rises markedly with increasing concentration of cadmium (II) ions. The lowest concentration of the toxic metal ions caused almost three fold increase in PCS activity as compared to control samples. The activity of PCS (270fkat) in treated cells was more than seven times higher in comparison to control ones. K(m) for PCS was estimated as 2.3mM.

The effects on soil/water/plant/animal systems by platinum group elements

AbstractEmissions of toxic substances such as oxides of carbon, nitrogen, sulphur, and, in addition, aromatic hydrocarbons, aldehydes and heavy metals are the most serious problem of road traffic affecting landscape. Platinum group elements (PGE), which are the main component of the catalyst, are one of the main sources of heavy metals in the environment. Here, we review the way by which emissions and forms of the emitted PGE end up in the environment especially to the soil-water-plant-animal system. The major points discussed are the following: 1) the main sources of PGE emission are automobile exhaust catalysts; 2) hospitals, where platinum is widely used to treat malignant neoplasm, and urban waste water belonging to other important sources of PGE in the environment; 3) soil is one of the most important components of the environment that may be contaminated with platinum metals; 4) phytotoxicity of PGE depends on the following conditions: the concentration of metals in the soil, time of exposure, the chemical form of metal, the chemical composition of exposed soil and plant species; 5) animals are also endangered by the increasing concentration of PGE in the environment. Moreover, we pay our attention to thiol-based mechanisms of how an organism protects itself against platinum group elements.

Comparison of various easy-to-use procedures for extraction of phenols from apricot fruits.

Phenols are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potential antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. The objective of this study was to investigate a suitable method for determination of protocatechuic acid, 4-aminobenzoic acid, chlorogenic acid, caffeic acid, vanillin, p-coumaric acid, rutin, ferulic acid, quercetin, resveratrol and quercitrin from apricot samples. A high-performance liquid chromatograph with electrochemical and UV detectors was used. The method was optimized in respect to both the separation selectivity of individual phenolic compounds and the maximum sensitivity with the electrochemical detection. The lowest limits of detection (3 S/N) using UV detection were estimated for ferulic acid (3 µM), quercitrin (4 µM) and quercetin (4 µM). Using electrochemical detection values of 27 nM, 40 nM and 37 nM were achieved for ferulic acid, quercitrin and quercetin, respectively. It follows from the acquired results that the coulometric detection under a universal potential of 600 mV is more suitable and sensitive for polyphenols determination than UV detection at a universal wavelength of 260 nm. Subsequently, we tested the influence of solvent composition, vortexing and sonication on separation efficiency. Our results showed that a combination of water, acetone and methanol in 20:20:60 ratio was the most effective for p-aminobenzoic acid, chlorgenic acid, caffeic acid, protocatechuic acid, ferulic acid, rutin, resveratrol and quercetin, in comparison with other solvents. On the other hand, vortexing at 4 °C produced the highest yield. Moreover, we tested the contents of individual polyphenols in the apricot cultivars Mamaria, Mold and LE-1075. The major phenolic compounds were chlorgenic acid and rutin. Chlorgenic acid was found in amounts of 2,302 mg/100 g in cultivar LE-1075, 546 mg/100 g in cultivar Mamaria and 129 mg/100 g in cultivar Mold. Generally, the cultivar LE-1075 produced the highest polyphenol content values, contrary to Mold, which compared to cultivar LE-1075 was quite poor from the point of view of the phenolics content.

Electrophoretic study of peptide-mediated quantum dot-human immunoglobulin bioconjugation.

The bioconjugation of quantum dots (QDs) is a key process in their application for bioanalysis as well as imaging. The coupling of QDs with biologically active molecules such as peptides, nucleic acids, and/or antibodies enables their fluorescent labeling, and therefore, selective and sensitive tracking during the bioanalytical process, however, the efficiency of the labeling and preservation of the biological activity of the bioconjugate have to be considered. In this study, a new approach of the bioconjugation of CdTe‐QDs and human immunoglobulin employing a small peptide is described. The heptapeptide (HWRGWVC) was synthesized and characterized by mass spectrometry, liquid chromatography, and capillary electrophoresis. Moreover, the peptide was used as a capping agent for QDs synthesis. The CdTe‐QDs were synthesized by microwave synthesis (600 W, 20 min) using 3.2 mM CdCl2 and 0.8 mM Na2TeO3. The bioconjugation of QDs capped by this peptide with immunoglobulin was investigated by capillary electrophoresis and magnetic immunoextraction coupled with electrochemical detection by differential pulse voltammetry. Furthermore, the applicability of prepared bioconjugates for fluorescent immunodetection was verified using immobilized goat antihuman IgG antibody.

Tissue Specific Electrochemical Fingerprinting

Background Proteomics and metalloproteomics are rapidly developing interdisciplinary fields providing enormous amounts of data to be classified, evaluated and interpreted. Approaches offered by bioinformatics and also by biostatistical data analysis and treatment are therefore of extreme interest. Numerous methods are now available as commercial or open source tools for data processing and modelling ready to support the analysis of various datasets. The analysis of scientific data remains a big challenge, because each new task sets its specific requirements and constraints that call for the design of a targeted data pre-processing approach. Methodology/Principal Findings This study proposes a mathematical approach for evaluating and classifying datasets obtained by electrochemical analysis of metallothionein in rat 9 tissues (brain, heart, kidney, eye, spleen, gonad, blood, liver and femoral muscle). Tissue extracts were heated and then analysed using the differential pulse voltammetry Brdicka reaction. The voltammograms were subsequently processed. Classification models were designed making separate use of two groups of attributes, namely attributes describing local extremes, and derived attributes resulting from the level = 5 wavelet transform. Conclusions/Significance On the basis of our results, we were able to construct a decision tree that makes it possible to distinguish among electrochemical analysis data resulting from measurements of all the considered tissues. In other words, we found a way to classify an unknown rat tissue based on electrochemical analysis of the metallothionein in this tissue.

Metal Transporters in Plants

Several transition metals are essential for plants as for most other organisms. These elements have been needed in the course of evolution because of their chemical properties such as redox activity under physiological conditions (Cu, Fe) or Lewis acid strength (Zn). The properties that make transition metal ions indispensable for life, however, are also the reason why they can easily be toxic when present in excess. The main threat lies in their ability to produce reactive oxygen species (ROS). Unfortunately, toxic metals such as cadmium, lead, mercury, etc., as well as the essential ones can also produce ROS. In the course of industrialization, emissions of metals have risen tremendously and significantly exceed those from natural sources for practically all metals. Due to this mobilization of metals into the biosphere, their circulation through soil, water, and air has greatly increased. The main aim of this chapter is to discuss the effects of metal ions on a plant cell, to summarize the current state of the art in the field of thiol-rich compounds like phytochelatins to detoxify metal ions.

Voltammetry as a tool for characterization of CdTe quantum dots.

Electrochemical detection of quantum dots (QDs) has already been used in numerous applications. However, QDs have not been well characterized using voltammetry, with respect to their characterization and quantification. Therefore, the main aim was to characterize CdTe QDs using cyclic and differential pulse voltammetry. The obtained peaks were identified and the detection limit (3 S/N) was estimated down to 100 fg/mL. Based on the convincing results, a new method for how to study stability and quantify the dots was suggested. Thus, the approach was further utilized for the testing of QDs stability.

Quantum dots and prion proteins: is this a new challenge for neurodegenerative diseases imaging?

A diagnostics of infectious diseases can be done by the immunologic methods or by the amplification of nucleic acid specific to contagious agent using polymerase chain reaction. However, in transmissible spongiform encephalopathies, the infectious agent, prion protein (PrPSc), has the same sequence of nucleic acids as a naturally occurring protein. The other issue with the diagnosing based on the PrPSc detection is that the pathological form of prion protein is abundant only at late stages of the disease in a brain. Therefore, the diagnostics of prion protein caused diseases represent a sort of challenges as that hosts can incubate infectious prion proteins for many months or even years. Therefore, new in vivo assays for detection of prion proteins and for diagnosis of their relation to neurodegenerative diseases are summarized. Their applicability and future prospects in this field are discussed with particular aim at using quantum dots as fluorescent labels.

Capillary electromigration based techniques in diagnostics of prion protein caused diseases.

Transmissible spongiform encephalopathies are a group of fatal neurodegenerative diseases with long incubation time. This group includes Creutzfeld‐Jakob disease, kuru, scrapie, chronic wasting disease, and bovine spongiform encephalopathy. Sensitive and specific detection of abnormal prion protein as “a source agent” of the above‐mentioned diseases in blood could provide a diagnostic test or a screening assay for animal and human prion protein diseases diagnostics. Therefore, diagnostic tests for prion protein diseases represent unique challenge requiring development of novel assays exploiting properties of prion protein complex. Presently, diagnostic methods such as protein misfolding cyclic amplification, conformation‐dependent immunoassay, dissociation‐enhanced lanthanide fluorescent immunoassay, fluorescence correlation spectroscopy, and/or flow microbead immunoassay are used for abnormal prion protein (PrPSc) detection. On the other hand, using of CE for PrPSc detection in body fluids is an attractive alternative; it has been already applied for the blood samples of infected sheep, elk, chimpanzee, as well as humans. In this review, assays for prion protein detection are summarized with special attention to capillary electromigration based techniques, such as CE, CIEF, and/or CGE. The potential of the miniaturized and integrated lab‐on‐chip devices is highlighted, emphasizing recent advances of this field in the proteomic analysis.