UV-induced spectral shift and protonation of DNA fluorescent dye Hoechst 33258

DNA-bound Hoechst 33258 is readily excited with UV light and emits blue fluorescence, however, upon exposure to UV, the dye undergoes photobleaching as well as photoconversion to a blue-excited green-emitting form. We demonstrate that the UV-generated green-emitting form of Hoechst 33258 exhibits spectral properties very similar to the form of the dye that can be obtained by subjecting it to an acidic environment (pH 0.5–3.0). We also demonstrate that exposure of Hoechst 33258 to UV light (or hydrogen peroxide) leads to generation of the protonated (1+, 2+, 3+ and possibly the 4+) forms of the dye. Photoconversion of Hoechst 33258 has recently been exploited in single molecule localisation microscopy, thus understanding photophysics of this process can facilitate further development of high resolution optical imaging

Sex-related differences in the dioecious species Rumex thyrsiflorus Fingerh : analysis of the content of phenolic constituents in leaf extracts

Rumex thyrsiflorus Fingerh. is mentioned as a European folk medicinal plant. This species has also been traditionally used as an edible plant in Eastern Europe because of its nutritional value. During the study, qualitative and quantitative sex-related differences of phenolic constituents in methanolic leaf extracts of R. thyrsiflorus were evaluated. The presence of the same substances (nine phenolic acids before, and six phenolic acids after acid hydrolysis, nine flavonoids, and a catechin) was estimated in both female and male specimens, using the HPLC-DAD method. A statistically significant higher content of eleven constituents in female plant extracts (acids: chlorogenic, p-coumaric, cryptochlorogenic, gallic, protocatechuic, neochlorogenic, vanillic; flavonoids: quercitrin, rhamnetin, rutoside; and a catechin) was shown. This is the first report concerning the relation between the sex and the content of biologically active phenolic secondary metabolites in leaf extracts of R. thyrsiflorus. Female plants of R. thyrsiflorus could be useful for pharmaceutical purposes as a preferential source of bioactive phenolic acids, flavonoids and especially catechin

Effects of zearalenone and 24-<i>epi</i>brassinolide on the salt tolerance of select monocotyledonous crop plants

Salinity has an increasing impact on crop production worldwide. Contemporary agricultural practices increasingly use plant biostimulants that protect plants against various environmental stresses. The aim of the work was to investigate whether such stimulants as 24-epibrassinolide (EPI) and zearalenone (ZEN) may alleviate effects of salinity in bread and durum wheat, maize, and sorghum plants. Plants were grown in glasshouse, in pots filled with perlite under continuous salinity stress (120 mM of NaCl). Four-week-old plants were treated with the stimulants. The plant responses to salinity were determined analyzing the following parameters: fresh and dry weights of plants, water content, electrolyte leakage, proline, abscisic acid, and the soluble carbohydrate contents in the leaves. The positive effect of ZEN on the studied parameters was more frequently observed than in the case of EPI. ZEN increased the root mass of both wheat species, as well as the stem and root masses of sorghum. This stimulant improved water relations in bread and durum wheat. Both stimulators increased the content of soluble carbohydrates. ZEN elevated significantly abscisic acid content in sorghum plants as well as it increased strongly proline level in all studied plant species. ZEN was more effective in alleviation salinity disorders than EPI.

Regulation of the Bud Dormancy Development and Release in Micropropagated Rhubarb ‘Malinowy’

Culinary rhubarb is a vegetable crop, valued for its stalks, very rich in different natural bioactive ingredients. In commercial rhubarb stalk production, the bud dormancy development and release are crucial processes that determine the yields and quality of stalks. To date, reports on rhubarb bud dormancy regulation, however, are lacking. It is known that dormancy status depends on cultivars. The study aimed to determine the dormancy regulation in a valuable selection of rhubarb ‘Malinowy’. Changes in carbohydrate, total phenolic, endogenous hormone levels, and gene expression levels during dormancy development and release were studied in micropropagated rhubarb plantlets. Dormancy developed at high temperature (25.5 °C), and long day. Leaf senescence and dying were consistent with a significant increase in starch, total phenolics, ABA, IAA and SA levels. Five weeks of cooling at 4 °C were sufficient to break dormancy, but rhizomes stored for a longer duration showed faster and more uniformity leaf growing, and higher stalk length. No growth response was observed for non-cooled rhizomes. The low temperature activated carbohydrate and hormone metabolism and signalling in the buds. The increased expression of AMY3, BMY3, SUS3, BGLU17, GAMYB genes were consistent with a decrease in starch and increase in soluble sugars levels during dormancy release. Moreover, some genes (ZEP, ABF2, GASA4, GA2OX8) related to ABA and GA metabolism and signal transduction were activated. The relationship between auxin (IAA, IBA, 5-Cl-IAA), and phenolic, including SA levels and dormancy status was also observed

Exhaust Emissions from a Hybrid City Bus Fuelled by Conventional and Oxygenated Fuel

City buses are one of the main means of public transport in cities. As they move in a limited and densely populated area and are intensively exploited, it is particularly important that they are environmentally friendly. There are many ways to reduce emissions from city buses, including the use of hybrid propulsion. Another way is to use low-emission fuels. This article presents the results of the emission tests of an 18 m articulated city bus with a serial hybrid drive fuelled comparatively by conventional diesel fuel and oxygenated fuel containing 10% v/v of triethylene glycol dimethyl ether (TEGDME). The emission tests were carried out during the actual operation of the bus on a route in Poznań (Poland) and over the SORT cycles. The obtained test results were compared also with the results obtained for a conventional bus. The reduction in emissions of some exhaust components was found when the hybrid bus was fuelled with oxygenated fuel during its actual operation on the bus route. There was a reduction in CO emissions by ~50% and NOx emissions by ~10%. Almost identical levels of PM and HC emissions and smoke opacity were observed for both fuels. In the SORT cycles, the differences in the emissions obtained for both types of fuel were small. In general, for the hybrid bus, a lower influence of oxygenated fuel on emissions was recorded than for the conventional bus