Mutations in SEC63 cause autosomal dominant polycystic liver disease

Mutations in PRKCSH, encoding the beta-subunit of glucosidase II, an N-linked glycan-processing enzyme in the endoplasmic reticulum (ER), cause autosomal dominant polycystic liver disease. We found that mutations in SEC63, encoding a component of the protein translocation machinery in the ER, also cause this disease. These findings are suggestive of a role for cotranslational protein-processing pathways in maintaining epithelial luminal structure and implicate noncilial ER proteins in human polycystic disease.     

RIM1alpha is required for presynaptic long-term potentiation.

Two main forms of long-term potentiation (LTP)-a prominent model for the cellular mechanism of learning and memory-have been distinguished in the mammalian brain. One requires activation of postsynaptic NMDA (N-methyl d-aspartate) receptors, whereas the other, called mossy fibre LTP, has a principal presynaptic component. Mossy fibre LTP is expressed in hippocampal mossy fibre synapses, cerebellar parallel fibre synapses and corticothalamic synapses, where it apparently operates by a mechanism that requires activation of protein kinase A. Thus, presynaptic substrates of protein kinase A are probably essential in mediating this form of long-term synaptic plasticity. Studies of knockout mice have shown that the synaptic vesicle protein Rab3A is required for mossy fibre LTP, but the protein kinase A substrates rabphilin, synapsin I and synapsin II are dispensable. Here we report that mossy fibre LTP in the hippocampus and the cerebellum is abolished in mice lacking RIM1alpha, an active zone protein that binds to Rab3A and that is also a protein kinase A substrate. Our results indicate that the long-term increase in neurotransmitter release during mossy fibre LTP may be mediated by a unitary mechanism that involves the GTP-dependent interaction of Rab3A with RIM1alpha at the interface of synaptic vesicles and the active zone.     

Orbital Kondo effect in carbon nanotubes

Progress in the fabrication of nanometre-scale electronic devices is opening new opportunities to uncover deeper aspects of the Kondo effect--a characteristic phenomenon in the physics of strongly correlated electrons. Artificial single-impurity Kondo systems have been realized in various nanostructures, including semiconductor quantum dots, carbon nanotubes and individual molecules. The Kondo effect is usually regarded as a spin-related phenomenon, namely the coherent exchange of the spin between a localized state and a Fermi sea of delocalized electrons. In principle, however, the role of the spin could be replaced by other degrees of freedom, such as an orbital quantum number. Here we show that the unique electronic structure of carbon nanotubes enables the observation of a purely orbital Kondo effect. We use a magnetic field to tune spin-polarized states into orbital degeneracy and conclude that the orbital quantum number is conserved during tunnelling. When orbital and spin degeneracies are present simultaneously, we observe a strongly enhanced Kondo effect, with a multiple splitting of the Kondo resonance at finite field and predicted to obey a so-called SU4 symmetry.     

Liquid-crystal-mediated self-assembly at nanodroplet interfaces

Technological applications of liquid crystals have generally relied on control of molecular orientation at a surface or an interface. Such control has been achieved through topography, chemistry and the adsorption of monolayers or surfactants. The role of the substrate or interface has been to impart order over visible length scales and to confine the liquid crystal in a device. Here, we report results from a computational study of a liquid-crystal-based system in which the opposite is true: the liquid crystal is used to impart order on the interfacial arrangement of a surfactant. Recent experiments on macroscopic interfaces have hinted that an interfacial coupling between bulk liquid crystal and surfactant can lead to a two-dimensional phase separation of the surfactant at the interface, but have not had the resolution to measure the structure of the resulting phases. To enhance that coupling, we consider the limit of nanodroplets, the interfaces of which are decorated with surfactant molecules that promote local perpendicular orientation of mesogens within the droplet. In the absence of surfactant, mesogens at the interface are all parallel to that interface. As the droplet is cooled, the mesogens undergo a transition from a disordered (isotropic) to an ordered (nematic or smectic) liquid-crystal phase. As this happens, mesogens within the droplet cause a transition of the surfactant at the interface, which forms new ordered nanophases with morphologies dependent on surfactant concentration. Such nanophases are reminiscent of those encountered in block copolymers, and include circular, striped and worm-like patterns.     

Inventory of Sarcophaginae (Diptera: Sarcophagidae) for the Humid Chaco,a poorly surveyed ecoregion of South America

ABSTRACT

Sarcophaginae is a large subfamily of sarcophagid flies (Diptera: Calyptratae: Oestroidea: Sarcophagidae) which have diverse habits, mainly sarcosaprophagous, and have forensic and sanitary importance. This is the first work that analyzes the fauna of Sarcophaginae exclusively in the Humid Chaco ecoregion where diversity of flies has scarcely been studied. This inventory was based on: a) samplings at different locations in the province of Chaco, Argentina, and in the state of Mato Grosso do Sul, Brazil; b) examination of entomological collections and c) bibliographic records. Sixty-two species of Sarcophaginae flies are included in this paper, of which 31 species are recorded for the first time in the Humid Chaco ecoregion. Ten species are new records for Argentina, two for Brazil and three for Paraguay. Lepidodexia (Neophytodes) lindneri Townsend, 1931, Lepidodexia (Notochaeta) adelina Mulieri, Schaefer, Duré and González, 2018, Lepidodexia (Pachygraphomima) lenti Lopes, 1980, Oxysarcodexia berthet Dufek and Mulieri, 2017, Oxysarcodexia ibera Dufek and Mulieri, 2017 and Retrocitomyia paraguayensis Lopes, 1985 are registered as endemic species of the Humid Chaco ecoregion. Species with forensically and sanitary importance are listed. Some comments on species distribution previously published in catalogues are provided.     

Diversity and life-history traits of wild bees (Insecta: Hymenoptera) in intensive agricultural landscapes in the Rolling Pampa,Argentina

The decline of bees is a major concern due to their vital role in pollinating many crops and wild plants. Some regions in South America, and especially the Pampas, are amongst those parts of the world where stressors of bee populations have been little studied. The Pampas has been intensively transformed for agriculture, being presently one of the most productive areas of agricultural commodities in the world. Here, we aim to provide first insights on the taxonomic and functional composition of bee assemblages in the Rolling Pampa, the most intensively managed part of the Pampas. Soybean (herbicide-tolerant genetically modified varieties) is the predominant crop in this region. Bees were sampled with coloured pan traps. Sampling points were located on field margins in either the cropped or the semi-natural grassland area of a farmland site devoted to annual cropping. A total of 2384 individuals were caught, representing 33 taxa [mainly (morpho)species]. The subgenus Lasioglossum (Dialictus) largely dominated captures (78% of the total abundance) and was relatively abundant in the entire study area, suggesting that some species are likely to reach their ecological requirements in cropped areas. No-till fields and field margins may provide large areas for these below-ground nesting species, while their polylectic food preferences allow them to collect pollen on a wide range of plant species, among them possibly soybean. On the contrary, the richness and the abundance of other taxa were higher in the semi-natural area than in the cropped area. Among them, above-ground nesting or oil-collecting species, which have more specialised nesting and floral requirements, were highly associated with the semi-natural area. Our findings highlight the large dominance of L. (Dialictus) species in this highly intensively managed landscape, and the urgent need of preserving semi-natural habitats to maintain species-rich and functionally diverse bee communities in the Pampas.     

The bootstrapped artefact: a collectivist account of technological ontology, functions, and normativity

In 2006, this journal addressed the problem of technological artefacts, and through a series of articles aimed at tackling the ‘dual nature of technical artefacts’, posited an understanding of these as constituted by both a structural (physical) and a functional (intentional) component. This attempt to conceptualise artefacts established a series of important questions, concerning such aspects of material technologies as mechanisms, functions, human intentionality, and normativity. However, I believe that in establishing the ‘dual nature’ thesis, the authors within this issue focused too strongly on technological function. By positing function as the analytic axis of the ‘dual nature’ framework, the theorists did not sufficiently problematise what is ultimately a social phenomenon. Here I posit a complementary analytic approach to this problem; namely, I argue that by using the Strong Programme’s performative theory of social institutions, we can better understand the nature of material technologies. Drawing particularly from Martin Kusch’s work, I here argue that by conceptualising artefacts as artificial kinds, we can better examine technological ontology, functions, and normativity. Ultimately, a Strong Programme approach, constructivist and collectivist in nature, offers a useful elaboration upon the important question raised by the ‘dual nature’ theorists.