Natural and Artificial Functionalized Biopolyesters I. Chemoenzymatic Mediated Synthesis of Chiral Precursors

Design of optically active polymeric materials for temporary therapeutic and environmental applications requires the working-out of functionalized polymers with structures and properties adjusted to the considered applications. Biocompatibility of selected polymers is a required property in regard to the interactions between living organisms and macromolecular systems. It is therefore important to prepare highly optically active monomers and their corresponding hydrolyzable and biocompatible polymers. Bacterium Clostridium tetanomorphum is an useful source of enzymes for bioconversion and particularly in the chemoenzyrnatic route to optically active alkylmalolactonic acid esters and their optically pure stereoisomers. 3-Methylaspartase, involved in the glutamate fermentation pathway, is a very interesting enzyme, which can provide chiral precursors with high optically purity. This chemoenzymatic strategy can be used to prepare the four stereoisomers of 3-methylmalolaconic acid esters, by enzymatic resolution of natural and artificial stereoisomers of 3-methylaspartic acid. A series of 3-alkymalolactonic acid esters with alkyl equal to ethyl or isopropyl, have been also synthesized and transformed into corresponding optically active polyesters.     

Exploring barriers to climate change adaptation in the Swiss tourism sector

Increasingly, various sectors are affected by climate change and need to find ways to adapt with much public guidance and support. This paper examines the adaptation process of a sector that started it some time ago – Swiss Alpine tourism. It identifies barriers that may be relevant for all sectors, all along the successive phases of the adaptation process. It additionally identifies the barriers which are most important and how these can be overcome. In order to do this we use an online survey directed to Swiss tourism stakeholders. Our results indicate that both economic and social feasibility barriers are important impediments to the adjustment process, whereas the acceptability among inhabitants and the willingness to act of stakeholders appear less critical. These barriers can be overcome and adaptation facilitated with more and especially better information about the regional consequences of climate change and feasible adaptation measures, by some top-down leadership and coordination, and by providing financial support.     

Temperature and parasitism by <Emphasis Type="BoldItalic">Asobara tabida</Emphasis> (Hymenoptera: Braconidae) influence larval pupation behaviour in two <Emphasis Type="BoldItalic">Drosophila</Emphasis> species

In holometabolous insects, pupation site selection behaviour has large consequences for survival. Here, we investigated the combined effects of temperature and parasitism by the parasitoid Asobara tabida on larval pupation behaviour in two of its main Drosophila sp. hosts differing in their climate origin. We found that larvae of Drosophila melanogaster—a species with a (sub)tropical origin—placed at 25°C pupated higher in rearing jars than those placed at 15°C. The opposite pattern was observed for Drosophila subobscura larvae—a species from temperate regions—which pupated lower, i.e. on or near the substrate at 25°C, than those placed at 15°C. When placed at 25°C, parasitized larvae of both species pupated closer to the substrate than unparasitized ones. Moreover, the Drosophila larvae that had been exposed and probably stung by A. tabida, but were not parasitized, pupated lower than the control unparasitized larvae. These results provide new insights of host behaviour manipulation by A. tabida larvae.     

Conception of an environmental friendly O/W cosmetic emulsion from microalgae

The development of eco-friendly cosmetic such as those from microalgae for skin regeneration and collagen synthesis has gained a great interest worldwide. Accordingly, the potential of microalgae biomass as source of anti-aging cosmetic cream with high antioxidant activity has been investigated. Stabilities and sensory characteristics of cosmetic creams supplemented with Spirulina, Tetraselmis sp. and Dunaliella sp. at 0.5, 1.5 and 2.5%, respectively, revealed a conservation of physico-chemical and preliminary stability properties of formulations. To analyze physico-chemical and textural parameters, accelerated stability study was evaluated under two thermal conditions (25 and 40 °C) during 90 days. Results showed that pH values of all formulations were within the limits of normal skin pH range under storage time at 25 and 40 °C. During this period, the colored creams showed a significant changes of a* and b* indices, reflecting the instability of microalgae colors. Microalgae modified the textural characteristics of emulsions. The Tetraselmis sp. containing-cream had the lowest (P < 0.05)?values of hardness, springiness, and cohesiveness. The 0.5% Spirulina containing-cream had the best stable consistency and adhesiveness under time and temperature variations. It exhibited the best properties to be used for skin care products. Thanks to their high content in bioactive macromolecules, microalgae considerably improved the antioxidant activity of the new formulated skin creams.

     

Interaction of bioaccumulation of heavy metal chromium with water relation, mineral nutrition and photosynthesis in developed leaves of Lolium perenne L

Contamination by chromium (Cr) is widespread in agricultural soils and industrial sites. This heavy metal represents a risk to human health. In order to gain fundamental insights into the nature of the adaptation to Cr excess, the characterisation of physiological indices, including responses of photosynthetic gas exchange and chlorophyll a fluorescence along with changes in mineral nutrient contents and water status were studied in ray grass (Lolium perenne L.). Increased concentrations of Cr(VI) (0-500 microM Cr) in the Co?c and Lessaint nutrient solution were applied. The growth of Lolium perenne is decreased by chromium and the leaves have lost their pigments. Chromium accumulation was greater in roots than in leaves and reached 2450 and 210 microg g(-1) DW, respectively with 500 microM Cr(VI) in nutrient medium. The physiological parameters were severely reduced by this heavy metal. Cr induced toxicity arising from 100 microM Cr(VI) and resulted in a modification of mineral content in roots and leaves, especially for Ca, Mg and Fe. The chromium stress decreased CO2 assimilation rates mainly due to stomatal closure, which reduced water loss by transpiration without decreasing the cellular available CO2. The fluorescence parameters associated with photosystem II (PSII) activity and the photochemical activity are modified by chromium. Non-radiative energy dissipation mechanisms were triggered during stress since non-photochemical quenching was increased and efficiency of excitation capture by open centers was reduced.     

Correction to: Water and soil contaminated by arsenic: the use of microorganisms and plants in bioremediation

Environmental Science and Pollution Research -     

Metal particle seeding on urban surface samples

Environmental Science and Pollution Research - In order to estimate the resuspension of the particles empirically, it is necessary to carry out a homogeneous distribution of the particles on the...