Radiation damage to DNA-protein specific complexes: estrogen response element-estrogen receptor complex

The exposure of a DNA-protein regulatory complex to ionising radiation induces damage to both partner biomolecules and thus can affect its functioning. Our study focuses on a complex formed by the estrogen response element (ERE) DNA and the recombinant human estrogen receptor alpha (ER), which mediates the signalling of female sex hormones, estrogens. The method of native polyacrylamide retardation gel electrophoresis is used to study the stability of the complex under irradiation by low LET radiation ((60)Co gamma rays) and the ability of the separately irradiated partners to form complexes. The relative probabilities of ERE DNA strand breakage and base damages as well as the probabilities of damages to the ER binding domain are calculated using the Monte Carlo method-based model RADACK.     

Processing and analytical characterisation of pulp-enriched cloudy apple juices

Pulp-enriched cloudy apple juices were manufactured from two apple varieties by blending of apple puree with natural cloudy apple juice in order to enrich bioactive secondary plant substances. Finishing of the puree with a 0.6-mm mesh screen and final product homogenisation revealed as the optimum processing technology for the novel 100% fruit beverage. The presence of large particles originating from the puree prevented long-term cloud stability, but due to the proportion of cloud-stable juice a complete phase separation did not occur. Optimal drinkability was achieved at a viscosity of 11.5 mPa s. Polyphenol compositions and concentrations were determined by means of RP-HPLC/PDA. The results ranged from 109 to 610 mg/l. All samples showed the typical polyphenol pattern of apples with dominating hydroxycinnamic acids followed by flavanols and flavonols. The puree addition to the cloudy apple juices increased the polyphenol concentrations by average 100%. Relatively, the highest increase could be observed for dimeric procyanidins. Different technological variants did not affect significantly the polyphenol concentrations. The dietary fibre contents of the pulp-enriched cloudy apple juices ranged from 5.8 to 9.4 g/l.     

Relation between the redox state of iron-based nanoparticles and their cytotoxicity toward Escherichia coli

Iron-based nanoparticles have been proposed for an increasing number of biomedical or environmental applications although in vitro toxicity has been observed. The aim of this study was to understand the relationship between the redox state of iron-based nanoparticles and their cytotoxicity toward a Gram-negative bacterium, Escherichia coli. While chemically stable nanoparticles (gammaFe2O3) have no apparent cytotoxicity, nanoparticles containing ferrous and, particularly, zerovalent iron are cytotoxic. The cytotoxic effects appear to be associated principally with an oxidative stress as demonstrated using a mutant strain of E. coli completely devoid of superoxide dismutase activity. This stress can result from the generation of reactive oxygen species with the interplay of oxygen with reduced iron species (Fe(II) and/or Fe(0)) or from the disturbance of the electronic and/or ionic transport chains due to the strong affinity of the nanoparticles for the cell membrane.     

Influence of different storage conditions on changes in the key aroma compounds of orange juice reconstituted from concentrate

Quantification of aroma compounds in an orange juice reconstituted from concentrate which had been stored at 37 °C for 4 weeks (forced storage) revealed an increase in the concentrations of, in particular, dimethyl sulphide, 2-methoxy-4-vinylphenol, α-terpineol, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDF) in comparison with the same orange juice before storage. On the other hand, clearly lower concentrations were found for octanal, decanal, (R)-α-pinene, linalool, and (E)-β-damascenone after storage, while the concentrations of vanillin and carvone remained nearly constant. Similar results were found for the same aroma compounds after storage of the orange juice at 20 °C for 1 year. Sensory experiments corroborated the importance of 2-methoxy-4-vinylphenol and dimethyl sulphide for the typical stale off-flavour of the stored orange juice, while the omission of e.g., α-terpineol in model mixtures could not be detected. Under both storage conditions (37 °C for 4 weeks or 20 °C for 1 year), the breakthrough odour thresholds of α-terpineol and 4-HDF were not reached, while the concentrations of dimethyl sulphide and 2-methoxy-4-vinylphenol clearly exceeded their breakthrough odour thresholds, thus confirming the crucial role of these odorants for the off-flavour of stored orange juice from concentrate. In addition, changes in the concentrations of selected orange juice odorants at various temperatures and times were investigated.     

Assessing the Role of Developmental and Environmental Factors in Chemical Defence Variation in Heliconiini Butterflies

Journal of Chemical Ecology - Chemical defences in animals are both incredibly widespread and highly diverse. Yet despite the important role they play in mediating interactions between predators...     

Nitroreductase-Mediated Release of Inhibitors of Lysine-Specific Demethylase 1 (LSD1) from Prodrugs in Transfected Acute Myeloid Leukaemia Cells

Lysine-specific demethylase 1 (LSD1) has evolved as a promising therapeutic target for cancer treatment, especially in acute myeloid leukaemia (AML). To approach the challenge of site-specific LSD1 inhibition, we developed an enzyme-prodrug system with the bacterial nitroreductase NfsB (NTR) that was expressed in the virally transfected AML cell line THP1-NTR⁺. The cellular activity of the NTR was proven with a new luminescent NTR probe. We synthesised a diverse set of nitroaromatic prodrugs that by design do not affect LSD1 and are reduced by the NTR to release an active LSD1 inhibitor. The emerging side products were differentially analysed using negative controls, thereby revealing cytotoxic effects. The 2-nitroimidazolyl prodrug of a potent LSD1 inhibitor emerged as one of the best prodrug candidates with a pronounced selectivity window between wild-type and transfected THP1 cells. Our prodrugs are selectively activated and release the LSD1 inhibitor locally, proving their suitability for future targeting approaches.     

Circumventing Dedicated Electrolytes in Light‐Emitting Electrochemical Cells

Light‐emitting electrochemical cells (LECs) are devices that utilize efficient ion redistribution to produce high‐efficiency electroluminescence in a simple device architecture. Prototypical polymer LECs utilize three components in the active layer: a luminescent conducting polymer, a salt, and an electrolyte. Similarly, many small‐molecule LECs also utilize an electrolyte to disperse salts. In these systems, the electrolyte is incorporated to efficiently conduct ions and to maintain phase compatibility between all components. However, certain LEC approaches and materials systems enable device operation without a dedicated electrolyte. This review describes the general methods and materials used to circumvent the use of a dedicated electrolyte in LECs. The techniques of synthetically coupling electrolytes, incorporating ionic liquids, and introducing inorganic salts are presented in view of research efforts to date. The use of these techniques in emerging classes of light‐emitting electrochemical cells is also discussed. These approaches have yielded some of the most efficient, long‐lasting, and commercially applicable LECs to date.