Screening of l‐histidine‐based ligands to modify monolithic supports and selectively purify the supercoiled plasmid DNA isoform

The growing demand of pharmaceutical‐grade plasmid DNA (pDNA) suitable for biotherapeutic applications fostered the development of new purification strategies. The surface plasmon resonance technique was employed for a fast binding screening of l ‐histidine and its derivatives, 1‐benzyl‐l ‐histidine and 1‐methyl‐l ‐histidine, as potential ligands for the biorecognition of three plasmids with different sizes (6.05, 8.70, and 14 kbp). The binding analysis was performed with different isoforms of each plasmid (supercoiled, open circular, and linear) separately. The results revealed that the overall affinity of plasmids to l ‐histidine and its derivatives was high (K_D > 10⁻⁸ M), and the highest affinity was found for human papillomavirus 16 E6/E7 (K_D = 1.1 × 10⁻¹⁰ M and K_D = 3.34 × 10⁻¹⁰ M for open circular and linear plasmid isoforms, respectively). l ‐Histidine and 1‐benzyl‐l ‐histidine were immobilized on monolithic matrices. Chromatographic studies of l ‐histidine and 1‐benzyl‐l ‐histidine monoliths were also performed with the aforementioned samples. In general, the supercoiled isoform had strong interactions with both supports. The separation of plasmid isoforms was achieved by decreasing the ammonium sulfate concentration in the eluent, in both supports, but a lower salt concentration was required in the 1‐benzyl‐l ‐histidine monolith because of stronger interactions promoted with pDNA. The efficiency of plasmid isoforms separation remained unchanged with flow rate variations. The binding capacity for pDNA achieved with the l ‐histidine monolith was 29‐fold higher than that obtained with conventional l ‐histidine agarose. Overall, the combination of either l ‐histidine or its derivatives with monolithic supports can be a promising strategy to purify the supercoiled isoform from different plasmids with suitable purity degree for pharmaceutical applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Changes in soil iron biogeochemistry in response to mangrove dieback

Biogeochemistry - Fe biogeochemistry is associated with important ecosystem services provided by mangrove forests, including carbon sequestration and the retention of potentially toxic elements....     

Biodiversity mitigates trade-offs among species functional traits underpinning multiple ecosystem services

Biodiversity loss and its effects on humanity is of major global concern. While a growing body of literature confirms positive relationships between biodiversity and multiple ecological functions, the links between biodiversity, ecological functions and multiple ecosystem services is yet unclear. Studies of biodiversity–functionality relationships are mainly based on computer simulations or controlled field experiments using only few species. Here, we use a trait-based approach to integrate plant functions into an ecosystem service assessment to address impacts of restoration on species-rich grasslands over time. We found trade-offs among functions and services when analysing contributions from individual species. At the community level, these trade-offs disappeared for almost all services with time since restoration as an effect of increased species diversity and more evenly distributed species. Restoration to enhance biodiversity also in species-rich communities is therefore essential to secure higher functional redundancy towards disturbances and sustainable provision of multiple ecosystem services over time.     

Linking human impacts to community processes in terrestrial and freshwater ecosystems

Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integrative approach to explain these differences by linking impacts to four fundamental processes that structure communities: dispersal, speciation, species-level selection and ecological drift. Our goal is to provide process-based insights into why human impacts, and responses to impacts, may differ across ecosystem types using a mechanistic, eco-evolutionary comparative framework. To enable these insights, we review and synthesise (i) how the four processes influence diversity and dynamics in terrestrial versus freshwater communities, specifically whether the relative importance of each process differs among ecosystems, and (ii) the pathways by which human impacts can produce divergent responses across ecosystems, due to differences in the strength of processes among ecosystems we identify. Finally, we highlight research gaps and next steps, and discuss how this approach can provide new insights for conservation. By focusing on the processes that shape diversity in communities, we aim to mechanistically link human impacts to ongoing and future changes in ecosystems.     

Microalgal secondary metabolites: effect of climatic variables,seasons, and photocycles on the biogeneration of volatile organic compounds (VOCs)

Journal of Applied Phycology - Microalgae produce many metabolites with diversified structures that play important roles in their development. This work evaluated the effects of different climatic...     

<Emphasis Type="Italic">Tabaroa</Emphasis>, a new genus of Leguminosae tribe Brongniartieae from Brazil

A new genus of Leguminosae in tribe Brongniartieae is proposed based on a new species endemic to the Caatinga of Bahia state. The new genus is named as Tabaroa L. P. Queiroz, G. P. Lewis & M. F. Wojc. and the new species as Tabaroa caatingicola L. P. Queiroz, G. P. Lewis & M. F. Wojc. A phylogenetic study of the Brongniartieae based on nuclear rDNA ITS and plastid matK sequences supports a closer relationship between Tabaroa and Harpalyce Moc. & Sessé than to the two South American genera Poecilanthe Benth. and Cyclolobium Benth., which are more similar morphologically. Optimisation of selected morphological characters on one of the most parsimonious trees indicates that the sessile ovary and the explosive pollen presentation are putative synapomorphies of the Tabaroa-Harpalyce clade. The genus Tabaroa may be diagnosed by the absence of peltate glandular trichomes; leaves imparipinnate, exstipellate and with opposite leaflets; flowers sessile, not resupinate, grouped in panicles; anthers apiculate; and fruit indehiscent. The only known species inhabits areas of arboreal caatinga on sandy soil in southwestern Bahia, near the boundaries of Dom Basílio and Livramento de Nossa Senhora municipalities.     

Chilling-induced changes in membrane fluidity and antioxidant enzyme activities in Coffea arabica L. roots

Exposure of coffee to low temperatures caused growth inhibition, changes in metabolic rates, and membrane alterations. Root tissue exposed to 10 °C evolved significantly lower rates of metabolic heat compared with controls grown at 25 °C, and the values were closely associated with the observed root growth inhibition. Electron paramagnetic resonance spectra of intact tissues showed that the spin probe 5-doxylstearic acid was capable to intercalate within the cellular membrane lipids. Indeed, at the depth of the 5th carbon atoms of the alkyl chains, the nitroxide radical detected more rigid membranes in seedlings exposed to 10 °C compared with 25 °C treated samples. Ascorbate peroxidase and catalase activities did not show appreciable changes under chilling conditions, while guaiacol peroxidase activity increased 55 % compared to the control. On the other hand, glutathione reductase activity decreased, in parallel to a significant decline in the capacity to reduce triphenyl-tetrazolium. Our results showed a marked correlation between lipid peroxidation and root tissue damage, which seemed to be associated with increased membrane rigidity. This revised version was published online in July 2006 with corrections to the Cover Date.