Modulation of the expression of ryanodine receptor mRNA from Plutella xylostella as a result of diamide insecticide application

Ryanodine receptors (RyRs), members of the largest family of calcium channel proteins, have been studied because of their key roles in calcium signalling within cells. With the development of diamide insecticides that exhibit a novel mode of action on the RyRs from Lepidoptera, research on insect RyRs has become more attractive in the field of plant protection. To enhance our understanding of the effects of diamides on RyRs, we cloned the Plutella xylostella RyR gene (Px-RyR), which is the most serious pest of Brassicaceae plants throughout the world. Furthermore, we investigated the modulation of the expression of Px-RyR as a result of the application of diamide insecticides. The full-length cDNAs of Px-RyR contain an open reading frame (ORF) of 15,372 bp with a predicted protein consisting of 5123 amino acids. Px-RyR possesses a high level of overall amino acid homology with other isoforms (77–92% identity with insect isoforms and 45–47% identity with vertebrate isoforms). The weight of Px. gradually decreased as the concentration of the diamides increased. However, the relative expression levels of the RyRs from larvae were dependent on the insecticide concentration and gradually increased with increasing insecticide concentrations.     

Social interactions, body image and oral health among institutionalised frail elders: an unexplored relationship

doi: 10.1111/j.1741‐2358.2011.00523.x Social interactions, body image and oral health among institutionalised frail elders: an unexplored relationship Objectives: This paper draws on theories of ageing, body image and disfigurement, to explore the potential for relationships between oral health, body image and social interactions between institutionalised elders. Background: Social relationships are important at all stages of life. A positive body image increases confidence in social interactions, which contributes substantially to health, well‐being and quality of life. Body image can be negatively impacted by oral conditions, particularly those that are appearance related and do not meet cultural ideals. Results: Typically, the oral health of frail elders in long‐term care facilities is poor, but to what extent poor oral health and dysfunction influence body image, and social behaviours is unclear. Conclusions: We conclude that there is the potential for poor oral health conditions to contribute negatively to the social well‐being in this population, but suggest that it requires further investigation.     

Compressive strains and displacement in a partially dentate lower jaw rehabilitated with two different treatment modalities

doi: 10.1111/j.1741‐2358.2011.00572.x Compressive strains and displacement in a partially dentate lower jaw rehabilitated with two different treatment modalities Background: Understanding of the biomechanical consequences of the stresses generated to the supporting bone during occlusal loading is significant for improving the design and clinical planning process in partial edentulism therapy. Objective: The aim of this study was to analyse the distribution of strain and displacement on the partially dentate lower jaw rehabilitated with an partial denture (RPD) and to compare it to the strain and displacement distribution on a partially dentate lower jaw rehabilitated with a cantilever fixed partial denture (FPD). Material and methods: The experimental models were a partially dentate mandible with full‐arch PFM crowns and RPD and a partially dentate mandible rehabilitated with a full‐arch cantilever FPD. Strains and displacement were measured using the Digital Image Correlation Method. Results: Displacement values of the first experimental model ranged from 0.31 to 0.54 mm with strains from 1.35 to 2.34%. Analysis of the second experimental model results showed displacement values from 0 to 0.34 mm, while strains were in the range of 0–1.40%. Conclusion: Higher displacements and strains of bone tissue were observed below the RPD, especially in the region of the distal abutment and distal portion of the free‐end saddle. Strains within bone and the bone‐denture contact area were mostly influenced by the teeth and denture vertical displacement.     

The role of atomic level steric effects and attractive forces in protein folding

Protein folding into tertiary structures is controlled by an interplay of attractive contact interactions and steric effects. We investigate the balance between these contributions using structure‐based models using an all‐atom representation of the structure combined with a coarse‐grained contact potential. Tertiary contact interactions between atoms are collected into a single broad attractive well between the C^β atoms between each residue pair in a native contact. Through the width of these contact potentials we control their tolerance for deviations from the ideal structure and the spatial range of attractive interactions. In the compact native state dominant packing constraints limit the effects of a coarse‐grained contact potential. During folding, however, the broad attractive potentials allow an early collapse that starts before the native local structure is completely adopted. As a consequence the folding transition is broadened and the free energy barrier is decreased. Eventually two‐state folding behavior is lost completely for systems with very broad attractive potentials. The stabilization of native‐like residue interactions in non‐perfect geometries early in the folding process frequently leads to structural traps. Global mirror images are a notable example. These traps are penalized by the details of the repulsive interactions only after further collapse. Successful folding to the native state requires simultaneous guidance from both attractive and repulsive interactions. Proteins 2012. © 2011 Wiley Periodicals, Inc.     

螺旋CT的多排多层探测器应用设计

目的设计螺旋CT机的多排多层探测器,提高影像质量。方法将常规多排探测器改进为多排多层探测器,输出端接超高倍光电耦合放大器,可成倍提高探测器与采集系统的信噪比。结果多排多层探测器比同样排数的单层探测器输出的信噪比高、省时、剂量少,且图像质量高。结论多排多层探测器输出的数据量大幅增加,使CT系统的成像质量显著提高。     

Three-dimensional microstructural changes in murine abdominal aortic aneurysms quantified using immunofluorescent array tomography

This study investigated the spatial and temporal remodeling of blood vessel wall microarchitecture and cellular morphology during abdominal aortic aneurysm (AAA) development using immunofluorescent array tomography (IAT), a high-resolution three-dimensional (3D) microscopy technology, in the murine model. Infrarenal aortas of C57BL6 mice (N=20) were evaluated at 0, 7, and 28 days after elastase or heat-inactivated elastase perfusion. Custom algorithms quantified volume fractions (VF) of elastin, smooth muscle cell (SMC) actin, and adventitial collagen type I, as well as elastin thickness, elastin fragmentation, non-adventitial wall thickness, and nuclei amount. The 3D renderings depicted elastin and collagen type I degradation and SMC morphological changes. Elastin VF decreased 37.5% (p<0.01), thickness decreased 48.9%, and fragmentation increased 449.7% (p<0.001) over 28 days. SMC actin VF decreased 78.3% (p<0.001) from days 0 to 7 and increased 139.7% (p<0.05) from days 7 to 28. Non-adventitial wall thickness increased 61.1%, medial nuclei amount increased 159.1% (p<0.01), and adventitial collagen type I VF decreased 64.1% (p<0.001) over 28 days. IAT and custom image analysis algorithms have enabled robust quantification of vessel wall content, microstructure, and organization to help elucidate the dynamics of vascular remodeling during AAA development.     

Three-dimensional reconstructions of Arp2/3 complex with bound nucleation promoting factors

Arp2/3 complex initiates the growth of branched actin-filament networks by inducing actin polymerization from the sides of pre-existing filaments. Nucleation promoting factors (NPFs) are essential for the branching reaction through interactions with the Arp2/3 complex prior to branch formation. The modes by which NPFs bind Arp2/3 complex and associated conformational changes have remained elusive. Here, we used electron microscopy to determine three-dimensional structures at ~2 nm resolution of Arp2/3 complex with three different bound NPFs: N-WASp, Scar-VCA and cortactin. All of these structures adopt a conformation with the two actin-related proteins in an actin-filament-like dimer and the NPF bound to the pointed end. Distance constraints derived by fluorescence resonance energy transfer independently verified the NPF location. Furthermore, all bound NPFs partially occlude the actin-filament binding site, suggesting that additional local structural rearrangements are required in the pathway of Arp2/3 complex activation to allow branch formation.     

Toward the virtual cell: Automated approaches to building models of subcellular organization "learned" from microscopy images

We review state-of-the-art computational methods for constructing, from image data, generative statistical models of cellular and nuclear shapes and the arrangement of subcellular structures and proteins within them. These automated approaches allow consistent analysis of images of cells for the purposes of learning the range of possible phenotypes, discriminating between them, and informing further investigation. Such models can also provide realistic geometry and initial protein locations to simulations in order to better understand cellular and subcellular processes. To determine the structures of cellular components and how proteins and other molecules are distributed among them, the generative modeling approach described here can be coupled with high throughput imaging technology to infer and represent subcellular organization from data with few a priori assumptions. We also discuss potential improvements to these methods and future directions for research.     

Spatial distribution of cytoplasmic domains of the Mg-transporter MgtE,in a solution lacking Mg,revealed by paramagnetic relaxation enhancement

MgtE is a prokaryotic Mg²⁺ transporter that controls cellular Mg²⁺ concentrations. We previously reported crystal structures of the cytoplasmic region of MgtE, consisting of 2 domains, that is, N and CBS, in the Mg²⁺-free and Mg²⁺-bound forms. The Mg²⁺-binding sites lay at the interface of the 2 domains, making the Mg²⁺-bound form compact and globular. In the Mg²⁺-free structure, however, the domains are far apart, and the Mg²⁺-binding sites are destroyed. Therefore, it is unclear how Mg²⁺-free MgtE changes its conformation to accommodate Mg²⁺ ions. Here, we used paramagnetic relaxation enhancement (PRE) to characterize the relative orientation of the N and CBS domains in the absence of Mg²⁺ in solution. When the residues on the surface of the CBS domain were labeled with nitroxide tags, significant PRE effects were observed for the residues in the N domain. No single structure satisfied the PRE profiles, suggesting that the N and CBS domains are not fixed in a particular orientation in solution. We then conducted ensemble simulated annealing calculations in order to obtain the atomic probability density and visualize the spatial distribution of the N domain in solution. The results indicate that the N domain tends to occupy the space near its position in the Mg²⁺-bound crystal structure, facilitating efficient capture of Mg²⁺ with increased intracellular Mg²⁺ concentration, which is necessary to close the gate.