235130 research outputs found
Sort by
Long Tails with Flower-like Conformations Undergo an Escape Transition in Homopolymer Adsorption Layers
Get PDFDe Gennes predicted that homopolymer adsorption on a solid-liquid interface results in an adsorption profile with a proximal, a central, and a distal region, wherein, for a good solvent, the central region has a self-similar structure with a density profile that decays as a power law with a coefficient of -4/3. Recent numerical self-consistent field (SCF) predictions for the long-chain length (N) limit revealed a more complex central region with an inner part, where the loops dominate the layer, with a (mean-field) power-law coefficient of -2 and an outer part, where tails dominate, with a "de Gennes" scaling of -4/3. The tails with length t t*, and these behave differently. With the increasing length of the tails, there exists a weak escape transition at t = tescape ≈ N/10. Long tails in the adsorption profile (t ≳ t∗ ∝ N0.733) show enhanced fluctuations due to this nearby escape transition, and this explains the excluded volume scaling for the outer part of the central region in SCF. With this interpretation, the -2 scaling found by SCF for the inner part should be classified as a mean-field result.</p
The C-Termini of the baculovirus per os infectivity factors 1 and 2 mediate ODV oral infectivity by facilitating the binding of PIF0 and PIF8 to the core of the entry complex
No full textOral infection of caterpillars by baculoviruses is initiated by occlusion-derived virus particles (ODVs) that infect midgut epithelium cells. The ODV envelope therefore contains at least ten different proteins, which are called per os infectivity factors (PIFs). Nine of these PIFs form the so-called ODV entry complex that consists of a stable core formed by PIF1, 2, 3 and 4, to which the other PIFs [PIF0, 6, 7, 8 and 9 (ac108)] bind with lower affinity. PIF1 and 2 are not only essential for complex formation, but also mediate ODV-binding to the epithelial brush border, probably via the C-Termini. To study the involvement of these PIFs during midgut infection in greater detail, we assessed the oral infectivity and the ability to form the complex of a series of PIF1 and PIF2 C-Terminal truncation mutants of Autographa californica multiple nucleopolyhedrovirus (AcMNPV), which were constructed in this study. Limited truncation of either PIF1 or 2 already severely impaired the ODV oral infectivity, but did not affect the formation of the core complex. However, the entry complex as a whole was not assembled in these mutants as PIF0 and 8 failed to bind to the core. This suggests that the interactions between the core and the loosely associated PIFs are important for the ODV infectivity and that complex formation complicates the determination of the exact roles of PIF1 and 2 during midgut infection. We also showed that the presence of PIF0, 6 and the ZF-domain of PIF8 are crucial for complex formation.</p
Nutritional composition and microbial communities of two non-alcoholic traditional fermented beverages from Zambia : A study of mabisi and munkoyo
Get PDFTraditional fermented foods and beverages are common in many countries, including Zambia. While the general (nutritional) benefits of fermented foods are widely recognised, the nutritional composition of most traditional fermented foods is unknown. Furthermore, fermentation is known to add nutritional value to raw materials, mainly by adding B-vitamins and removing anti-nutritional factors. In the case of traditional fermentation, the composition of microbial communities responsible for fermentation varies from producer to producer and this may also be true for the nutritional composition. Here, we characterized the nutrient profile and microbial community composition of two traditional fermented foods: milk-based Mabisi and cereal-based Munkoyo. We found that the two products are different with respect to their nutritional parameters and their microbial compositions. Mabisi was found to have higher nutritional values for crude protein, fat, and carbohydrates than Munkoyo. The microbial community composition was also different for the two products, while both communities were dominated by lactic acid bacteria. Our analyses showed that variations in nutritional composition, defined as the amount of consumption that would contribute to the estimated average requirement (EAR), might be explained by variations in microbial community composition. Consumption of Mabisi appeared to contribute more than Munkoyo to the EAR and its inclusion in food-based recommendations is warranted. Our results show the potential of traditional fermented foods such as Mabisi and Munkoyo to add value to current diets and suggests that variations in microbial composition between specific product samples can result in variations in nutritional composition.</p
Metagenomic analysis of regularly microwave-treated and untreated domestic kitchen sponges
Get PDFKitchen sponges massively absorb and spread microorganisms, leading to contamination of kitchen appliances, surfaces, and food. Microwaving as an effective and widespread technique can rapidly reduce the microbial load of kitchen sponges. However, long-term effects of such treatments are largely unknown. Notably, it has been speculated that regularly applied domestic cleaning and disinfection may select for microbial communities with a higher pathogenic potential and/or malodorous properties. In this study, we distributed newly purchased polyurethane kitchen sponges to 20 participants, with the instruction to use them under normal household conditions for four weeks. Ten of the participants sanitized their sponges regularly by a standardized microwaving protocol, while the remaining ten sponges remained untreated. Metagenomic sequence data evaluation indicated that, in addition to bacteria, viruses, eukaryotes, and archaea were also part of the kitchen sponge microbiome. Comparisons of sanitized and untreated kitchen sponges indicated a trend towards a reduced structural microbial diversity while functional diversity increased. Microwave sanitization appeared to alter composition and metabolic properties of the microbial communities. Follow-up studies will have to show whether these changes are more positive or negative in terms of domestic hygiene, human health, and well-being.</p
Scaling Readiness: Science and practice of an approach to enhance impact of research for development
Get PDFScaling of innovations is a key requirement for addressing societal challenges in sectors such as health, agriculture, and the environment. Research for development (R4D) programs, projects and other interventions struggle to make particular innovations go to scale. Current conceptualizations of scaling are often too simplistic; more systemic and multidimensional perspectives, frameworks and measures are needed. There is a gap between new complexity-aware theories and perspectives on innovation, and tools and approaches that can improve strategic and operational decision-making in R4D interventions that aim to scale innovations. This paper aims to bridge that gap by developing the key concepts and measures of Scaling Readiness. Scaling Readiness is an approach that encourages critical reflection on how ready innovations are for scaling and what appropriate actions could accelerate or enhance scaling. Scaling Readiness provides action-oriented support for (1) characterizing the innovation and innovation system; (2) diagnosing the current readiness and use of innovations as a proxy for their readiness to scale; (3) developing strategy to overcome bottlenecks for scaling; (4) facilitating and negotiating multi-stakeholder innovation and scaling processes; and (5) navigating and monitoring the implementation process to allow for adaptive management. Scaling Readiness has the potential to support evidence-based scaling strategy design, implementation and monitoring, and – if applied across multiple interventions – can be used to manage a portfolio of innovation and scaling investments.</p
Towards a low-carbon economy : A nexus-oriented policy coherence analysis in Greece
Get PDFThe sustainable management of natural resources under climate change conditions is a critical research issue. Among the many approaches emerged in recent times, the so-called 'nexus approach' is gaining traction in academic and policy circles. The nexus approach presupposes the analysis of bio-physical, socio-economic and policy interlinkages among sectors (e.g., water, energy, food) for the identification of integrated solutions and the support of policy decisions. Ultimately, the nexus approach aims to identify synergies and trade-offs among the nexus dimensions. Concerning policy, the nexus approach focuses on policy coherence, i.e., the systematic identification and management of trade-offs and synergies between policies across sectors. This paper investigates the coherence between policies on the water-land-energy-food-climate nexus in Greece. The systematic analysis of policy documents led to the elicitation of nexus-related policy objectives and instruments. Then, the coherence among objectives and between objectives and instruments was assessed using the methodology proposed by Nilsson et al. A stakeholder (trans-disciplinary) orientation was adopted and the need to incorporate stakeholders' recommendations as to policy coherence assessment was highlighted. Overall, the findings revealed that climate and food/agricultural policies represent critical future priorities in Greece by stimulating progress in other nexus-related policies (energy, water, land policies) and being positively influenced by them.</p
Desiccation Tolerance : Avoiding Cellular Damage during Drying and Rehydration
No full textDesiccation of plants is often lethal but is tolerated by the majority of seeds and by vegetative tissues of only a small number of land plants. Desiccation tolerance is an ancient trait, lost from vegetative tissues following the appearance of tracheids but reappearing in several lineages when selection pressures favored its evolution. Cells of all desiccation-tolerant plants and seeds must possess a core set of mechanisms to protect them from desiccation- and rehydration-induced damage. This review explores how desiccation generates cell damage and how tolerant cells assuage the complex array of mechanical, structural, metabolic, and chemical stresses and survive.Likewise, the stress of rehydration requires appropriate mitigating cellular responses. We also explore what comparative genomics, both structural and responsive, have added to our understanding of cellular protection mechanisms induced by desiccation, and how vegetative desiccation tolerance circumvents destructive, stress-induced cell senescence.</p
Evaluation of diurnal responses of Tetradesmus obliquus under nitrogen limitation
Get PDFTetradesmus obliquus is an oleaginous microalga with high potential for triacylglycerol production. We characterized the biochemical composition and the transcriptional landscape of T. obliquus wild-type and the starchless mutant (slm1), adapted to 16:8 h light dark (LD) cycles under nitrogen limitation. In comparison to the nitrogen replete conditions, the diurnal RNA samples from both strains also displayed a cyclic pattern, but with much less variation which could be related to a reduced transcription activity in at least the usually highly active processes. During nitrogen limitation, the wild-type continued to use starch as the preferred storage compound to store energy and carbon. Starch was accumulated to an average content of 0.25 g·gDW −1, which is higher than the maximum observed under nitrogen replete conditions. Small oscillations were observed, indicating that starch was being used as a diurnal energy storage compound, but to a lesser extent than under nitrogen replete conditions. For the slm1 mutant, TAG content was higher than for the wild-type (average steady state value was 0.26 g·gDW −1 for slm1 compared to 0.06 g·gDW −1 for the wild-type). Despite the higher TAG content in the slm1, the conversion efficiency of photons into biomass components for the slm1 was only half of the one obtained for the wild-type. This is related to the observed decrease in biomass productivity (from 1.29 gDW·L−1·day−1 for the wild-type to 0.52 gDW·L−1·day−1 for the slm1). While the transcriptome of slm1 displayed clear signs of energy generation by degrading TAG and amino-acids during the dark period, no significant variation of these metabolites could be measured. When looking through the diurnal cycle, the photosynthetic efficiency was lower for the slm1 mutant compared to the wild-type especially during the second half of the light period, where starch accumulation occurred in the wild-type.</p
