Multi-stage subduction-related metasomatism recorded in whiteschists from the Dora-Maira Massif, Western Alps

Whiteschists from the Dora-Maira massif (Western Alps, Italy) are Mg and K-rich metasomatised granites which experienced ultra-high pressure metamorphism and fluid-rock interaction during Alpine continental subduction. The sources and timing of fluid infiltration are a source of significant debate. In this study we present boron (B) isotopes and other fluid-mobile trace element (FME) concentrations in various generations of phengite from whiteschists and their country rock protoliths to investigate the sources and timing of metasomatic fluid influx. Reconstructed bulk rock concentrations based on modal data and mineral compositions indicate that significant amounts B and other FME were added to the rock during prograde metamorphism, but that this fluid influx postdates the main Mg metasomatic event. High B concentrations (150–350 µg/g) and light δ11B values (-16 to -4 ‰) recorded in phengite point to a B-rich sediment-derived fluid as the main source of B in the whiteschists. Further redistribution of FME during metamorphism was associated with breakdown of hydrous minerals such as talc, phlogopite and ellenbergerite. The source of the Mg-rich fluids cannot be constrained based on the B data in phengite, since its signature was overprinted by the later main B metasomatic event. Rare tourmaline-bearing whiteschists record additional information about B processes. Tourmaline δ11B values (-6 to +1 ‰) are in isotopic equilibrium with similar fluids to those recorded in most phengite, but phengites in tourmaline-bearing samples records anomalous B isotope compositions that reflect later redistribution of B. This study demonstrates the utility of in situ analyses in unravelling complex fluid-rock interaction histories, where whole rock analyses make it difficult to distinguish between different stages of fluid-rock interaction. Polymetasomatism may result in decoupling of different isotopic systems, thus complicating their interpretation. The Dora-Maira whiteschists interacted with multiple generations of fluids during subduction and therefore may represent a long-lived fluid pathway

The Amsterdam Declaration on Fungal Nomenclature

The Amsterdam Declaration on Fungal Nomenclature was agreed at an international symposium convened in Amsterdam on 19–20 April 2011 under the auspices of the International Commission on the Taxonomy of Fungi (ICTF). The purpose of the symposium was to address the issue of whether or how the current system of naming pleomorphic fungi should be maintained or changed now that molecular data are routinely available. The issue is urgent as mycologists currently follow different practices, and no consensus was achieved by a Special Committee appointed in 2005 by the International Botanical Congress to advise on the problem. The Declaration recognizes the need for an orderly transitition to a single-name nomenclatural system for all fungi, and to provide mechanisms to protect names that otherwise then become endangered. That is, meaning that priority should be given to the first described name, except where that is a younger name in general use when the first author to select a name of a pleomorphic monophyletic genus is to be followed, and suggests controversial cases are referred to a body, such as the ICTF, which will report to the Committee for Fungi. If appropriate, the ICTF could be mandated to promote the implementation of the Declaration. In addition, but not forming part of the Declaration, are reports of discussions held during the symposium on the governance of the nomenclature of fungi, and the naming of fungi known only from an environmental nucleic acid sequence in particular. Possible amendments to the Draft BioCode (2011) to allow for the needs of mycologists are suggested for further consideration, and a possible example of how a fungus only known from the environment might be described is presented

Self-assembled architectures with multiple aqueous compartments

A vital organizational feature of living cells is that of compartmentalization. This allows cells to run concurrently incompatible metabolic processes and to regulate these processes by selective trans-membrane transport. Although strategies that effectively mimic cell function in simple architectures have been researched extensively, soft matter systems with membranes that delineate distinct and multiple aqueous environments have only recently caught attention. We highlight a range of multi-compartmentalized soft matter systems including vesosomes, capsosomes, polymersomes, double emulsions, and their combinations, and demonstrate that the unique properties of the multi-compartmentalized architectures have the potential to add value to application areas such as drug-delivery and multi-enzyme biosynthesis

A facile and fast method for the functionalization of polymersomes by photoinduced cycloaddition chemistry

Polymersomes are promising platforms for use in biosensing, where their stability may be crucial over that of liposomes. For the introduction of the desired functionality multiple strategies have been reported for functionalization of polymersomes. However, none of them have combined readily available starting materials, facility and in situ quantification. We show a simple 4-step method for functionalization of polymersomes starting from commercially available materials. For the key conjugation step a recently explored light induced cycloaddition was used which is relatively fast (15 min) and allows in situ quantification by the intrinsic fluorescence of the conjugate. The facility of the protocol, the ease of preparation and quantification make this ‘click’-type conjugation method a promising alternative to the established strained cycloadditions

Conformational antibody binding to a native, cell-free expressed GPCR in block copolymer membranes.

G-protein coupled receptors (GPCRs) play a key role in physiological processes and are attractive drug targets. Their biophysical characterization is, however, highly challenging because of their innate instability outside a stabilizing membrane and the difficulty of finding a suitable expression system. We here show the cell-free expression of a GPCR, CXCR4, and its direct embedding in diblock copolymer membranes. The polymer-stabilized CXCR4 is readily immobilized onto biosensor chips for label-free binding analysis. Kinetic characterization using a conformationally sensitive antibody shows the receptor to exist in the correctly folded conformation, showing binding behaviour that is commensurate with heterologously expressed CXCR4

Kinetic parameters extracted from fitting the binding curves of concentration series of three different mAbs against a single preparation of immobilized CXCR4 ACMs.

[a]<p>KD for 12G5 binding to CXCR4-ACMS shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110847#pone-0110847-g002" target="_blank">Figure 2</a> was 60.2±17 nM.</p><p>Kinetic parameters extracted from fitting the binding curves of concentration series of three different mAbs against a single preparation of immobilized CXCR4 ACMs.</p

Tuning the properties of PS-PIAT block copolymers and their assembly into polymersomes

The diblock copolymer polystyrene-b-polyisocyanoalanine(2-thiophene-3-yl- ethyl)amide (PS-PIAT) was prepared by reacting the isocyanide monomer (1) with a Ni(ii) initiator complex prepared from polystyrene amine (PS 40NH2), either obtained by atom transfer radical polymerization (ATRP) or anionic polymerization (AP). It was found that polymerization of optically pure 1 followed first-order kinetics in monomer concentration and resulted in the formation of insoluble block copolymers, whereas the rate of polymerization of optical mixtures of 1 was retarded and yielded block copolymers that were better soluble. Furthermore, PS-PIAT polymersomes of which the PS-block was prepared by AP were more stable than polymersomes of which the PS-block was prepared by ATRP, as was indicated by combined turbidity and dynamic light scattering (DLS) measurements on the aggregate solutions

Sensorgrams of mAb 12G5 binding (100 nM) to CXCR4-ACMs immobilized at low RU (ca. 1400) via biotin/spteptavidin immobilization of the embedding polymersome matrix.

<p>The analyte was injected in triplicate, at cycle 7, 14, and 21. Intermediate cycles involved blank injections. The blue line shows the fit to the curve assuming 1∶1 binding kinetics. The inset shows the relative decrease in binding activity of the surface as measured by the binding level 4 s before the end of the injection.</p

Kinetic screening of 12G5 mAb binding to CXCR4-ACMs immobilized onto biosensor chips.

<p>A: Ab was injected at increasing concentrations (6.25–400 nM) over 100 s, followed by a buffer wash (without regeneration) between injections (immobilization level: ca. 5000 RU; biotin/streptavidin immobilization). B. Saturation binding of 125-I SDF1α to CXCR4-ACMs. A dissociation constant of 8.4 nM was determined. C. The same series of measurements as shown in Fig. 2 A, conducted using immobilized VLPS (immobilization level: 5000 RU).</p