Protecting group and switchable pore-discriminating adsorption properties of a hydrophilic-hydrophobic metal-organic framework

Formed by linking metals or metal clusters through organic linkers, metal-organic frameworks are a class of solids with structural and chemical properties that mark them out as candidates for many emerging gas storage, separation, catalysis and biomedical applications. Important features of these materials include their high porosity and their flexibility in response to chemical or physical stimuli. Here, a copper-based metal-organic framework has been prepared in which the starting linker (benzene-1,3,5-tricarboxylic acid) undergoes selective monoesterification during synthesis to produce a solid with two different channel systems, lined by hydrophilic and hydrophobic surfaces, respectively. The material reacts differently to gases or vapours of dissimilar chemistry, some stimulating subtle framework flexibility or showing kinetic adsorption effects. Adsorption can be switched between the two channels by judicious choice of the conditions. The monoesterified linker is recoverable in quantitative yield, demonstrating possible uses of metal-organic frameworks in molecular synthetic chemistry as 'protecting groups' to accomplish selective transformations that are difficult using standard chemistry techniques.

Morphological cladistic analysis as a model for character evaluation in primitive living chitons (Polyplacophora, Lepidopleurina)

Chitons are often referred to as "living fossils" in part because they are proposed as one of the earliest-diverging groups of living molluscs, but also because the gross morphology of the polyplacophoran shell has been conserved for hundreds of millions of years. As such, the analysis of evolution and radiation within polyplacophorans is of considerable interest not only for resolving the shape of pan-molluscan phylogeny but also as model organisms for the study of character evolution. This study presents a new, rigorous cladistic analysis of the morphological characters used in taxonomic descriptions for chitons in the living suborder Lepidopleurina Thiele, 1910 (the earliest-derived living group of chitons). Shell-based characters alone entirely fail to recover any recognized subdivisions within the group, which may raise serious questions about the application of fossil data (from isolated shell valves). New analysis including characters from girdle armature and gill arrangements recovers some genera within the group but also points to the lack of monophyly within the main genus Leptochiton Gray, 1847. Additional characters from molecular data and soft anatomy, used in combination, are clearly needed to resolve questions of chiton relationships. However, the data sets currently available already provide interesting insights into the analytical power of traditional morphology as well as some knowledge about the early evolution and radiation of this group.

A Superfamily of Actin-Binding Proteins at the Actin-Membrane Nexus of Higher Plants

Complex animals use a wide variety of adaptor proteins to produce specialized sites of interaction between actin and membranes. Plants do not have these protein families, yet actin-membrane interactions within plant cells are critical for the positioning of subcellular compartments, for coordinating intercellular communication, and for membrane deformation [1]. Novel factors are therefore likely to provide interfaces at actin-membrane contacts in plants, but their identity has remained obscure. Here we identify the plantspecific Networked (NET) superfamily of actin-binding proteins, members of which localize to the actin cytoskeleton and specify different membrane compartments. The founding member of the NET superfamily, NET1A, is anchored at the plasma membrane and predominates at cell junctions, the plasmodesmata. NET1A binds directly to actin filaments via a novel actin-binding domain that defines a superfamily of thirteen Arabidopsis proteins divided into four distinct phylogenetic clades. Members of other clades identify interactions at the tonoplast, nuclear membrane, and pollen tube plasma membrane, emphasizing the role of this superfamily in mediating actin-membrane interactions.

Strategies of actin reorganisation in plant cells

Spatial-temporal flexibility of the actin filament network (F-actin) is essential for all basic cellular functions and is governed by a stochastic dynamic model. In this model, actin filaments that randomly polymerise from a pool of free actin are bundled with other filaments and severed by ADF/cofilin. The fate of the severed fragments is not known. It has been proposed that the fragments are disassembled and the monomeric actin recycled for the polymerisation of new filaments. Here, we have generated tobacco cell lines and Arabidopsis plants expressing the actin marker Lifeact to address the mechanisms of F-actin reorganisation in vivo. We found that F-actin is more dynamic in isotropically expanding cells and that the density of the network changes with a periodicity of 70 seconds. The depolymerisation rate, but not the polymerisation rate, of F-actin increases when microtubules are destabilised. New filaments can be assembled from shorter free cytoplasmic fragments, from the products of F-actin severing and by polymerisation from the ends of extant filaments. Thus, remodelling of F-actin might not require bulk depolymerisation of the entire network, but could occur via severing and end-joining of existing polymers.

Regulation of the pollen-specific actin-depolymerizing factor LIADF1

Pollen tube growth is dependent on a dynamic actin cytoskeleton, suggesting that actin-regulating proteins are involved. We have examined the regulation of the lily pollen-specific actin-depolymerizing factor (ADF) LIADF1. Its actin binding and depolymerizing activity is pH sensitive, inhibited by certain phosphoinositides, but not controlled by phosphorylation. Compared with its F-actin binding properties, its low activity in depolymerization assays has been used to explain why pollen ADF decorates F-actin in pollen grains. This low activity is incompatible with a role in increasing actin dynamics necessary to promote pollen tube growth. We have identified a plant homolog of actin-interacting protein, AIP1, which enhances the depolymerization of F-actin in the presence of LIADF1 by similar to60%. Both pollen ADF and pollen AIP1 bind F-actin in pollen grains but are mainly cytoplasmic in pollen tubes. Our results suggest that together these proteins remodel actin filaments as pollen grains enter and exit dormancy.

GIANT LOBES OF CENTAURUS A RADIO GALAXY OBSERVED WITH THE SUZAKU X-RAY SATELLITE

We report on Suzaku observations of selected regions within the southern giant lobe of the radio galaxy Centaurus A. In our analysis we focus on distinct X-ray features detected with the X-ray Imaging Spectrometer within the range 0.5-10 keV, some of which are likely associated with fine structure of the lobe revealed by recent high-quality radio intensity and polarization maps. With the available photon statistics, we find that the spectral properties of the detected X-ray features are equally consistent with thermal emission from hot gas with temperatures kT > 1 keV, or with a power-law radiation continuum characterized by photon indices Gamma similar to 2.0 +/- 0.5. However, the plasma parameters implied by these different models favor a synchrotron origin for the analyzed X-ray spots, indicating that a very efficient acceleration of electrons up to greater than or similar to 10 TeV energies is taking place within the giant structure of Centaurus A, albeit only in isolated and compact regions associated with extended and highly polarized radio filaments. We also present a detailed analysis of the diffuse X-ray emission filling the whole field of view of the instrument, resulting in a tentative detection of a soft excess component best fitted by a thermal model with a temperature of kT similar to 0.5 keV. The exact origin of the observed excess remains uncertain, although energetic considerations point to thermal gas filling the bulk of the volume of the lobe and mixed with the non-thermal plasma, rather than to the alternative scenario involving a condensation of the hot intergalactic medium around the edges of the expanding radio structure. If correct, this would be the first detection of the thermal content of the extended lobes of a radio galaxy in X-rays. The corresponding number density of the thermal gas in such a case is n(g) similar to 10(-4) cm(-3), while its pressure appears to be in almost exact equipartition with the volume-averaged non-thermal pressure provided by the radio-emitting electrons and the lobes' magnetic field. A prominent large-scale fluctuation of the Galactic foreground emission, resulting in excess foreground X-ray emission aligned with the lobe, cannot be ruled out. Although tentative, our findings potentially imply that the structure of the extended lobes in active galaxies is likely to be highly inhomogeneous and non-uniform, with magnetic reconnection and turbulent acceleration processes continuously converting magnetic energy to internal energy of the plasma particles, leading to possibly significant spatial and temporal variations in the plasma beta parameter around the volume-averaged equilibrium condition beta similar to 1.

Effect of membrane stiffness and cytoskeletal element density on mechanical stimuli within cells: an analysis of the consequences of ageing in cells

A finite element model of a single cell was created and used to investigate the effects of ageing on biophysical stimuli generated within a cell. Major cellular components were incorporated in the model: the membrane, cytoplasm, nucleus, microtubules, actin filaments, intermediate filaments, nuclear lamina, and chromatin. The model used multiple sets of tensegrity structures. Viscoelastic properties were assigned to the continuum components. To corroborate the model, a simulation of Atomic Force Microscopy (AFM) indentation was performed and results showed a force/indentation simulation with the range of experimental results.

Ageing was simulated by both increasing membrane stiffness (thereby modelling membrane peroxidation with age) and decreasing density of cytoskeletal elements (thereby modelling reduced actin density with age). Comparing normal and aged cells under indentation predicts that aged cells have a lower membrane area subjected to high strain compared to young cells, but the difference, surprisingly, is very small and would not be measurable experimentally. Ageing is predicted to have more significant effect on strain deep in the nucleus. These results show that computation of biophysical stimuli within cells are achievable with single-cell computational models whose force/displacement behaviour is within experimentally observed ranges. the models suggest only small, though possibly physiologically-significant, differences in internal biophysical stimuli between normal and aged cells.

Cinematic Peripheries of Dublin

The term periphery is, most of the time, used with or in relation to the centre. The ‘zoning’ taken by granted by the architect is unlike the one portrayed by the director who frames the differences of places in a non-linear manner. Film offers a constructed urban experience, suggesting the city to be a local network composed of nodes and links, rather than a centre and the margin. It is possible to talk about the construction of a new kind of network in film through a temporal representation of space, of the distant as the close. In this way, film may be a tool to shift the gaze from the bird’s-eye view to the eye level to create ‘a unified perceptual image of the city’, in Christine Boyer’s words. The experienced surface of the city is two-dimensional neither in fiction nor in reality. In this chapter, the nodes of Dublin are examined through two Irish films, Goldfish Memory (Elizabeth Gill, 2003) and Adam and Paul (Leonard Abrahamson, 2004). Specific elements of the city of Dublin, including walls, houses, pubs, streets, bridges, and parks, are analysed to understand the nature of the network of the city composed of nodes and their connections.

Centennial-scale climate change in Ireland during the Holocene

We examine mid- to late Holocene centennial-scale climate variability in Ireland using proxy data from peatlands, lakes and a speleothem. A high degree of between-record variability is apparent in the proxy data and significant chronological uncertainties are present. However, tephra layers provide a robust tool for correlation and improve the chronological precision of the records. Although we can find no statistically significant coherence in the dataset as a whole, a selection of high-quality peatland water table reconstructions co-vary more than would be expected by chance alone. A locally weighted regression model with bootstrapping can be used to construct a ‘best-estimate’ palaeoclimatic reconstruction from these datasets. Visual comparison and cross-wavelet analysis of peatland water table compilations from Ireland and Northern Britain show that there are some periods of coherence between these records. Some terrestrial palaeoclimatic changes in Ireland appear to coincide with changes in the North Atlantic thermohaline circulation and solar activity. However, these relationships are inconsistent and may be obscured by chronological uncertainties. We conclude by suggesting an agenda for future Holocene climate research in Ireland. ©2013 Elsevier B.V. All rights reserved.

Genome-wide association analysis identifies 13 new risk loci for schizophrenia

Schizophrenia is an idiopathic mental disorder with a heritable component and a substantial public health impact. We conducted a multi-stage genome-wide association study (GWAS) for schizophrenia beginning with a Swedish national sample (5,001 cases and 6,243 controls) followed by meta-analysis with previous schizophrenia GWAS (8,832 cases and 12,067 controls) and finally by replication of SNPs in 168 genomic regions in independent samples (7,413 cases, 19,762 controls and 581 parent-offspring trios). We identified 22 loci associated at genome-wide significance; 13 of these are new, and 1 was previously implicated in bipolar disorder. Examination of candidate genes at these loci suggests the involvement of neuronal calcium signaling. We estimate that 8,300 independent, mostly common SNPs (95% credible interval of 6,300-10,200 SNPs) contribute to risk for schizophrenia and that these collectively account for at least 32% of the variance in liability. Common genetic variation has an important role in the etiology of schizophrenia, and larger studies will allow more detailed understanding of this disorder.

Common variant at 16p11.2 conferring risk of psychosis

Epidemiological and genetic data support the notion that schizophrenia and bipolar disorder share genetic risk factors. In our previous genome-wide association (GWA) study, meta-analysis and follow-up (totaling as many as 18,206 cases and 42,536 controls), we identified four loci showing genome-wide significant association with schizophrenia. Here we consider a mixed schizophrenia and bipolar disorder (psychosis) phenotype (addition of 7,469 bipolar disorder cases, 1,535 schizophrenia cases, 333 other psychosis cases, 808 unaffected family members and 46,160 controls). Combined analysis reveals a novel variant at 16p11.2 showing genome-wide significant association (rs4583255[T], OR = 1.08, P = 6.6 × 10−11). The new variant is located within a 593 kb region that substantially increases risk of psychosis when duplicated. In line with the association of the duplication with reduced body mass index (BMI), rs4583255[T] is also associated with lower BMI (P = 0.0039 in the public GIANT consortium dataset; P = 0.00047 in 22,651 additional Icelanders).

Neurotrophin-3 gene polymorphisms and schizophrenia:no evidence for linkage or association

It has been suggested on the basis of neuropathological and epidemiological evidence that schizophrenia is, at least in part, a neurodevelopmental illness. Some patients show abnormalities in cell position in the medial temporal lobes of their brains. Neurotrophin-3 is one of many proteins essential for the proper growth and development of the nervous system. Therefore the finding of a polymorphism near the promoter region of the gene, alleles of which were associated with the disease, prompted us to attempt replication. In a linkage and association analysis of the same polymorphism using familial schizophrenics and population controls we found no evidence to support the finding. We conclude that mutations or polymorphisms at this gene are unlikely to be involved in the genetic aetiology of schizophrenia.