Podocyte Injury Associated with Mutant α-Actinin-4

Focal segmental glomerulosclerosis (FSGS) is an important cause of proteinuria and nephrotic syndrome in humans. The pathogenesis of FSGS may be associated with glomerular visceral epithelial cell (GEC; podocyte) injury, leading to apoptosis, detachment, and “podocytopenia”, followed by glomerulosclerosis. Mutations in α-actinin-4 are associated with FSGS in humans. In cultured GECs, α-actinin-4 mediates adhesion and cytoskeletal dynamics. FSGS-associated α-actinin-4 mutants show increased binding to actin filaments, compared with the wild-type protein. Expression of an α-actinin-4 mutant in mouse podocytes in vivo resulted in proteinuric FSGS. GECs that express mutant α-actinin-4 show defective spreading and motility, and such abnormalities could alter the mechanical properties of the podocyte, contribute to cytoskeletal disruption, and lead to injury. The potential for mutant α-actinin-4 to injure podocytes is also suggested by the characteristics of this mutant protein to form microaggregates, undergo ubiquitination, impair the ubiquitin-proteasome system, enhance endoplasmic reticulum stress, and exacerbate apoptosis

Toxicity testing of Atlantic salmon aquaculture chemotherapeutants on spot prawns and benthic invertebrates

Demand for protein sources is high in North America and growing throughout the world. Global declines in fisheries has encouraged coastal regions to embrace aquaculture as a means of reconciling the growing pressures on wild fish stocks with this demand. Intensive salmon farming practices result in periodic infestations with naturally-occurring parasitic copepods referred to as “sea lice”. To prevent productivity losses, a variety of chemical and physical treatments have been implemented through regulatory systems or emergency applications. One objective of this study is to determine if these chemo-therapeutic treatments pose a risk to other non-target marine organisms including crustaceans such as the Spot prawn (Pandalus platyceros). These organisms can be both culturally and economically important to local First Nations and all residents of the Salish Sea region, as well as crucial components of marine ecosystems. The sub-chronic toxicity of the sea lice pesticides Slice® (active ingredient: emamectin benzoate) was assessed for lethal and sub-lethal effects on Pacific prawns, amphipods, and polychaetes which are all found in areas where aquaculture pens exist. Slice and ivermectin whole sediment exposures were conducted. Test concentrations were representative of environmentally-relevant levels. The toxicity of these treatments was assessed using the endpoints of: mortality, growth, and behavioural response. Preliminary results indicate a concentration-response relationship for various selected endpoints

Spin-gap opening accompanied by a strong magnetoelastic response in the S=1 magnetic dimer system Ba3BiRu2O9

Neutron diffraction, magnetization, resistivity, and heat capacity measurements on the 6H-perovskite Ba3BiRu2O9 reveal simultaneous magnetic and structural dimerization driven by strong magnetoelastic coupling. An isostructural but strongly displacive first-order transition on cooling through T*=176 K is associated with a change in the nature of direct Ru-Ru bonds within Ru2O9 face-sharing octahedra. Above T*, Ba3BiRu2O9 is an S=1 magnetic dimer system with intradimer exchange interactions J0/kB=320 K and interdimer exchange interactions J'/kB=-160 K. Below T*, a spin-gapped state emerges with \Delta\approx220 K. Ab initio calculations confirm antiferromagnetic exchange within dimers, but the transition is not accompanied by long range-magnetic order.Comment: 5 pages, 5 figures, accepted by Physical Review

Thin Wholesale Markets and Direct Marketing in Renewable Resource Exploitation

The ex-vessel supply chain for fisheries has been recognized as an important determinant of value generation. In recent years, as the retail demand for fresh seafood products has increased, many independent fishermen have bypassed thin, monopsonized, or otherwise inferior wholesale markets by engaging in implicit or explicit fixed-output contracts with consumers (e.g., restaurants, supermarkets, individuals). We investigate the implications of this type of market structure for various management scenarios with a simple model of resource stochasticity and fishing effort. We show that contracts are associated with risk when periodic stock is stochastic, leading to inefficiencies and excess effort in the short run when resource conditions are temporarily poor. However, the results suggest that bilateral production agreements between fishermen can absolve a significant proportion of these inefficiencies, with broader partnership schemes offering further gains. Fishing cooperatives – which are often designed to facilitate the joint marketing of fish products – are an obvious tool in alleviating the inefficiencies associated with small-scale, contract-driven marketing

Target Selection for the LBTI Exozodi Key Science Program

The Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) on the Large Binocular Telescope Interferometer will survey nearby stars for faint emission arising from ~300 K dust (exozodiacal dust), and aims to determine the exozodiacal dust luminosity function. HOSTS results will enable planning for future space telescopes aimed at direct spectroscopy of habitable zone terrestrial planets, as well as greater understanding of the evolution of exozodiacal disks and planetary systems. We lay out here the considerations that lead to the final HOSTS target list. Our target selection strategy maximizes the ability of the survey to constrain the exozodi luminosity function by selecting a combination of stars selected for suitability as targets of future missions and as sensitive exozodi probes. With a survey of approximately 50 stars, we show that HOSTS can enable an understanding of the statistical distribution of warm dust around various types of stars and is robust to the effects of varying levels of survey sensitivity induced by weather conditions.Comment: accepted to ApJ

Revisiting the cubic crystal structures of Sr4Nb2O9 and Sr5Nb2O10

We have synthesized polycrystalline and single crystal samples of Sr4Nb2O9 and Sr5Nb2O10 and revisited the crystal structure of the high-temperature cubic phase. By careful analysis of single-crystal X-ray diffraction (SXRD), powder synchrotron X-ray diffraction (Syn-PXRD) and powder neutron diffraction (PND) data, we arrive at a structure model in space group 4#3 (216), a subgroup of the reported 3# (225) model. The 4#3 model gives a better fit to the diffraction data, especially PND. We observed an interstitial oxide ion O3 on the 48h site near O1, which gives a tetrahedral Nb1−O polyhedron rather than an octahedral one as found in the 3# (225) model. The temperature-dependent conductivities of Sr4Nb2O9 and Sr5Nb2O10 in dried O2 were studied using impedance spectroscopy. The activation energies of Sr4Nb2O9 and Sr5Nb2O10 were estimated to be 1.18(1) eV and 1.17(4) eV respectively. This crystallographic arrangement of O1 and O3 (spread over split sites) is likely a key structural factor behind oxide ionic migration in Sr4Nb2O9 and Sr5Nb2O10

Structure evolution of Na2O2 from room temperature to 500 oC

Na2O2 is one of the possible discharge products from sodium-air batteries. Here we report the evolution of the structure of Na2O2 from room temperature to 500 oC using variable-temperature neutron and synchrotron X- ray powder diffraction. A phase transition from α-Na2O2 to β-Na2O2 is observed in the neutron diffraction measurements above 400 oC and the crystal structure of β-Na2O2 is determined from neutron diffraction data at 500 oC. α-Na2O2 adapts a hexagonal 6#2 (No. 189) structure and β-Na2O2 adapts a tetragonal I41/acd (No. 142) structure. The thermal expansion coefficients of α-Na2O2 is a = 2.98×10–5 K–1, c = 2.89×10–5 K–1 and V = 8.96×10–5 K–1 up to 400 oC and a ~10% volume expansion occurs during the phase transition from α- Na2O2 to β-Na2O2 due to the re-alignment/rotation of O22– groups. Both phases are electronic insulators according to DFT calculations with band gaps (both indirect) of 1.75 eV (α-Na2O2) and 2.56 eV (β-Na2O2). Impedance analysis from room temperature to 400 oC revealed a significant enhancement of conductivity at T ≥ 275 oC. α-Na2O2 shows higher conductivity (~10 times at T ≤ 275 oC and ~3 times at T > 275 oC) in O2 compared to in Ar. We confirmed, by dielectric analysis, that this enhanced conductivity is dominated by ionic conduction

A novel method for comparison of arterial remodeling in hypertension: Quantification of arterial trees and recognition of remodeling patterns on histological sections

Remodeling of spatially heterogeneous arterial trees is routinely quantified on tissue sections by averaging linear dimensions, with lack of comparison between different organs and models. The impact of experimental models or hypertension treatment modalities on organ-specific vascular remodeling remains undefined. A wide variety of arterial remodeling types has been demonstrated for hypertensive models, which include differences across organs. The purpose of this study was to reassess methods for measurement of arterial remodeling and to establish a morphometric algorithm for standard and comparable quantification of vascular remodeling in hypertension in different vascular beds. We performed a novel and comprehensive morphometric analysis of terminal arteries in the brain, heart, lung, liver, kidney, spleen, stomach, intestine, skin, skeletal muscle, and adrenal glands of control and Goldblatt hypertensive rats on routinely processed tissue sections. Mean dimensions were highly variable but grouping them into sequential 5 μm intervals permitted creation of reliable linear regression equations and complex profiles. Averaged arterial dimensions demonstrated seven remodeling patterns that were distinct from conventional inward-outward and hypertrophic-eutrophic definitions. Numerical modeling predicted at least nineteen variants of arterial spatial conformations. Recognition of remodeling variants was not possible using averaged dimensions, their ratios, or the remodeling and growth indices. To distinguish remodeling patterns, a three dimensional modeling was established and tested. The proposed algorithm permits quantitative analysis of arterial remodeling in different organs and may be applicable for comparative studies between animal hypertensive models and human hypertension. Arterial wall tapering is the most important factor to consider in arterial morphometry, while perfusion fixation with vessel relaxation is not necessary. Terminal arteries in organs undergo the same remodeling pattern in Goldblatt rats, except for organs with hemodynamics affected by the arterial clip. The existing remodeling nomenclature should be replaced by a numerical classification applicable to any type of arterial remodeling