Crowding-induced hybridization of single DNA hairpins

It is clear that a crowded environment influences the structure, dynamics, and interactions of biological molecules, but the complexity of this phenomenon demands the development of new experimental and theoretical approaches. Here we use two complementary single-molecule FRET techniques to show that the kinetics of DNA base pairing and unpairing, which are fundamental to both the biological role of DNA and its technological applications, are strongly modulated by a crowded environment. We directly observed single DNA hairpins, which are excellent model systems for studying hybridization, either freely diffusing in solution or immobilized on a surface under crowding conditions. The hairpins followed two-state folding dynamics with a closing rate increasing by 4-fold and the opening rate decreasing 2-fold, for only modest concentrations of crowder [10% (w/w) polyethylene glycol (PEG)]. These experiments serve both to unambiguously highlight the impact of a crowded environment on a fundamental biological process, DNA base pairing, and to illustrate the benefits of single-molecule approaches to probing the structure and dynamics of complex biomolecular systems

Rapid and specific purification of Argonaute-small RNA complexes from crude cell lysates

Small interfering RNAs (siRNAs) direct Argonaute proteins, the core components of the RNA-induced silencing complex (RISC), to cleave complementary target RNAs. Here, we describe a method to purify active RISC containing a single, unique small RNA guide sequence. We begin by capturing RISC using a complementary 2\u27-O-methyl oligonucleotide tethered to beads. Unlike other methods that capture RISC but do not allow its recovery, our strategy purifies active, soluble RISC in good yield. The method takes advantage of the finding that RISC partially paired to a target through its siRNA guide dissociates more than 300 times faster than a fully paired siRNA in RISC. We use this strategy to purify fly Ago1- and Ago2-RISC, as well as mouse AGO2-RISC. The method can discriminate among RISCs programmed with different guide strands, making it possible to deplete and recover specific RISC populations. Endogenous microRNA:Argonaute complexes can also be purified from cell lysates. Our method scales readily and takes less than a day to complete

Study of different pretreatments on Spirulina platensis biomass for bioethanol production

Aquatic biomass presents a large variety of compounds that can be used for the production of third generation (3G) biofuels, mainly carbohydrates, lipids, proteins and co-products, which can be obtained and used in the production of biofuels such as bioethanol from rich carbohydrate biomass [1]. Nowadays Spirulina platensis biomass can be considered as an alternative since it has a great capacity to produce carbohydrates [2]. This work presents a study of 3G biorefinery process from Spirulina platensis biomass; diverse types of hydrothermal pretreatments (autoclave 121 °C 20 min; freezing/thawing -4 °C and gelatinization 100 °C 10 min; gelatinization 100 °C 20 min; microwave 121 °C 20 min; ultrasound bath 20 min) and their effects on enzymatic hydrolysis with -amylase and amyloglucosidase in order to obtain fermentable sugars were evaluated. Moreover, two fermentation strategies were evaluated; simultaneous saccharification and fermentation (SSF) and pre-saccharification and fermentation (PSF), the conditions used for the fermentation were pH 4.5, 35 ° C, 150 rpm and Saccharomyces cerevisiae yeast was employed, all strategies were used as alternatives in 3G bioethanol process. Results showed that the pretreatment with autoclave (121 ° C 20 min 5% solids) was better for the cellular breakdown and accessibility of enzymes to cellular matrix in the enzymatic hydrolysis. The treatment of pre-saccharification and fermentation (PSF) with 5 % solids pretreated with autoclave at 121 ° C for 20 min and pre-hydrolyzed with -amylase and amyloglucosidase after fermentation obtained a maximum yield of conversion of glucose to bioethanol of 79.34 %. Simultaneous saccharification and fermentation (SSF) was the best strategy for the obtention of bioethanol from pretreatment biomass of Spirulina platensis with a yield of 81.12 %. These results are good since there are no previously reported studies of the use of SSF for bioethanol from microalgae biomass production.info:eu-repo/semantics/publishedVersio

Postharvest shelf life extension of blueberries using a chitosan-based edible coating containing aloe vera juice

PosterBlueberries are currently one of the most valuable fruits worldwide, due to their organoleptic and nutritional properties. However these fruits are highly perishable due to their susceptibility to fungal infections (e.g. Botrytis cinerea) and water loss during storage. Edible coatings can improve fruits quality and extend their shelf life by providing a barrier to moisture and gases. The incorporation of natural antifungal compounds, e.g. Aloe vera, into edible coatings provides a novel way to enhance edible coatings properties without using synthetic compounds. In this study, chitosan-based coating (0.5% (w/v)) incorporating Aloe vera juice (0.5% (w/v)) was applied to blueberries to evaluate: (1) their antifungal efficiency and (2) postharvest quality of cold-stored blueberries. Uncoated (B) and coated blueberry (BC) samples were monitored over 25 days at 5.5±0.6 °C and 90±3 % relative humidity. During storage time, samples were analyzed in terms of weight loss, microbiological growth, titratable acidity, pH, soluble solids content, and color properties. Results showed that BC treatment delayed blueberries dehydration after 25 days, since B and BC samples weight losses were 6.2% and 3.7%, respectively. B samples presented contamination after 2 days of storage (2.0 log CFU/g), whilst BC samples presented mold contamination only after 9 days of storage (1.3 log CFU/g). The pH of BC samples remained lower (3.15) than that of B samples (3.54) after 12 days of storage. During storage, B samples had significantly lower titratable acidity values than BC samples (p<0.05), demonstrating that the coating helped retaining acidity of blueberries. Chitosan-based coatings with Aloe vera demonstrated great potential in extending blueberries shelf-life (about 5 days). Moreover, two main factors of blueberry postharvest deterioration (microbiological growth and water loss levels) were reduced, which may represent a significant commercial value to blueberries producers

Effect of chitosan-Aloe vera coating on postharvest quality of blueberry (Vaccinium corymbosum) fruit

The present study was carried out to evaluate the effect of chitosan-based edible coatings with Aloe vera extract on the postharvest blueberry fruit quality during storage at 5 °C. Firstly, A. vera fractions (pulp and liquid) were extracted from leaves and evaluated in terms of antifungal and antioxidant capacities. The choice of the most adequate chitosan and A. vera fraction concentrations to be incorporated in coating formulation was made based on the wettability of the corresponding coating solutions. Coatings with 0.5% (w/v) chitosan + 0.5% (w/v) glycerol + 0.1% (w/v) Tween 80 + 0.5% (v/v) A. vera liquid fraction presented the best characteristics to uniformly coat blueberry surface. Physico-chemical (i.e., titratable acidity, pH, weight loss) and microbiological analyses of coated blueberries (non-inoculated or artificially inoculated with Botrytis cinerea) were performed during 25 d. Microbiological growth and water loss levels were approximately reduced by 50% and 42%, respectively, in coated blueberries after 25 d compared to uncoated blueberries. After 15 d, weight loss values were 6.2% and 3.7% for uncoated and chitosanA. vera coated blueberries, respectively. Uncoated fruits presented mold contamination after 2 d of storage (2.0 ± 0.32 log CFU g1), whilst fruits with chitosan-based coatings with A. vera presented mold contamination only after 9 d of storage (1.3 ± 0.35 log CFU g1). Overall, coatings developed in this study extend blueberries shelf-life for about 5 d, demonstrating for the first time that the combination of chitosan and A. vera liquid fraction as edible coating materials has great potential in expanding the shelf-life of fruits.Joana T. Martins (SFRH/BPD/89992/2012) is the recipient of a fellowship from the Fundação para a Ciência e Tecnologia (FCT, Portugal). María L. Flores-López thanks Mexican Science and Technology Council(CONACYT, Mexico) for PhD fellowship support (CONACYT Grant number: 215499/310847). The authors thank the FCT the strategic funding of UID/BIO/04469/2013 unit and the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER- 027462)

Equality of Participation Online Versus Face to Face: Condensed Analysis of the Community Forum Deliberative Methods Demonstration

Online deliberation may provide a more cost-effective and/or less inhibiting environment for public participation than face to face (F2F). But do online methods bias participation toward certain individuals or groups? We compare F2F versus online participation in an experiment affording within-participants and cross-modal comparisons. For English speakers required to have Internet access as a condition of participation, we find no negative effects of online modes on equality of participation (EoP) related to gender, age, or educational level. Asynchronous online discussion appears to improve EoP for gender relative to F2F. Data suggest a dampening effect of online environments on black participants, as well as amplification for whites. Synchronous online voice communication EoP is on par with F2F across individuals. But individual-level EoP is much lower in the online forum, and greater online forum participation predicts greater F2F participation for individuals. Measured rates of participation are compared to self-reported experiences, and other findings are discussed.Comment: 14 pages, 10 tables, to appear in Efthimios Tambouris, Panos Panagiotopoulos, {\O}ystein S{\ae}b{\o}, Konstantinos Tarabanis, Michela Milano, Theresa Pardo, and Maria Wimmer (Editors), Electronic Participation: Proceedings of the 7th IFIP WG 8.5 International Conference, ePart 2015 (Thessaloniki, August 30-September 2), Springer LNCS Vol. 9249, 201