Life at the border: Adaptation of proteins to anisotropic membrane environment

This review discusses main features of transmembrane (TM) proteins which distinguish them from water‐soluble proteins and allow their adaptation to the anisotropic membrane environment. We overview the structural limitations on membrane protein architecture, spatial arrangement of proteins in membranes and their intrinsic hydrophobic thickness, co‐translational and post‐translational folding and insertion into lipid bilayers, topogenesis, high propensity to form oligomers, and large‐scale conformational transitions during membrane insertion and transport function. Special attention is paid to the polarity of TM protein surfaces described by profiles of dipolarity/polarizability and hydrogen‐bonding capacity parameters that match polarity of the lipid environment. Analysis of distributions of Trp resides on surfaces of TM proteins from different biological membranes indicates that interfacial membrane regions with preferential accumulation of Trp indole rings correspond to the outer part of the lipid acyl chain region—between double bonds and carbonyl groups of lipids. These “midpolar” regions are not always symmetric in proteins from natural membranes. We also examined the hydrophobic effect that drives insertion of proteins into lipid bilayer and different free energy contributions to TM protein stability, including attractive van der Waals forces and hydrogen bonds, side‐chain conformational entropy, the hydrophobic mismatch, membrane deformations, and specific protein–lipid binding.     

血清同型半胱氨酸、脂联素、高敏C反应蛋白水平与颈动脉内膜中层厚度在老年2型糖尿病合并脑梗死患者中的意义

目的：观察血清同型半胱氨酸（Hcy）、脂联素（APN）、高敏C反应蛋白（hs．CRP）水平与颈动脉内膜中层厚度（1MT）在老年2型糖尿病合并脑梗死患者中的意义。方法：选择2008年5月至2012年5月在我院就诊的2型糖尿病患者218例,按照是否合并脑梗死分为糖尿病伴脑梗死组（105例）和单纯糖尿病组（113例）。选择同期健康体检者30例为健康对照组。观察三组血清Hcy、APN、hs—CRP和IMT的水平变化。结果：糖尿病伴脑梗死组和单纯糖尿病组的血清Hcy、hs—CRP和IMT的水平均较正常对照组明显提高（P〈0．01）,糖尿病伴脑梗死组以上指标显著高于单纯糖尿病组（P〈0．01）;而糖尿病伴脑梗死组和单纯糖尿病组的血清APN的水平较正常对照组明显降低（P〈0．01）,糖尿病伴脑梗死组血清APN的水平较单纯糖尿病组显著降低（P〈0．01）。血清Hcy和hs—CRP水平随着1MT的严重程度增加而升高（P〈0．01）,而APN水平随着IMT严重程度升高而降低（P〈0．01）。结论：糖尿病伴脑梗死的患者大血管病变较单纯糖尿病患者更为严重,颈动脉IMT与Hcy和hs—cRP呈正相关,而与APN呈负相关。     

Comparison of patella bone strain between females with and without patellofemoral pain: A finite element analysis study

Elevated bone principal strain (an indicator of potential bone injury) resulting from reduced cartilage thickness has been suggested to contribute to patellofemoral symptoms. However, research linking patella bone strain, articular cartilage thickness, and patellofemoral pain (PFP) remains limited. The primary purpose was to determine whether females with PFP exhibit elevated patella bone strain when compared to pain-free controls. A secondary objective was to determine the influence of patella cartilage thickness on patella bone strain. Ten females with PFP and 10 gender, age, and activity-matched pain-free controls participated. Patella bone strain fields were quantified utilizing subject-specific finite element (FE) models of the patellofemoral joint (PFJ). Input parameters for the FE model included (1) PFJ geometry, (2) elastic moduli of the patella bone, (3) weight-bearing PFJ kinematics, and (4) quadriceps muscle forces. Using quasi-static simulations, peak and average minimum principal strains as well as peak and average maximum principal strains were quantified. Cartilage thickness was quantified by computing the perpendicular distance between opposing voxels defining the cartilage edges on axial plane magnetic resonance images. Compared to the pain-free controls, individuals with PFP exhibited increased peak and average minimum and maximum principal strain magnitudes in the patella. Additionally, patella cartilage thickness was negatively associated with peak minimum principal patella strain and peak maximum principal patella strain. The elevated bone strain magnitudes resulting from reduced cartilage thickness may contribute to patellofemoral symptoms and bone injury in persons with PFP.     

Hominid lifestyle and diet reconsidered: paleo-environmental and comparative data

It is traditionally believed that human ancestors evolved in a warm and dry environment. The available evidence, however, favours the vision that it happened in a warm and wet environment. The paleo-environmental data suggest that the early australopithecinesAustralopithecus anamensis, afarensis andafricanus lived in warm, moist, and wooded landscapes such as gallery forests. In the Pleistocene, the robust australopithecinesA. robustus andboisei seem to have dwelt in more open, possibly cooler and generally dryer places, in the vicinity of shallow and relatively stagnant waters of lakesides, lagoons, marshes and riverbanks. Dental and microwear studies suggest that the australopithecines, more than Western lowland gorillas, regularly fed on aquatic herbaceous vegetation (AHV). Homo fossils, on the other hand, as suggested by the paleo-environmental data, are more frequently discovered near lakes, seas and rivers where molluscs were abundant. Shellfish could provide a dietary supplement for their omnivorous diet. This is how early hominines might have learned to use stones to crack bivalves. This subsequently could have led to stone tool use for other purposes.     

The evolution of host‐specific variation in cuckoo eggshell strength

Cuckoo eggs are renowned for their mimicry of different host species, leading to the evolution of host‐specific races (or ‘gentes’) defined by egg colour and pattern. This study aims to test the prediction that another property of parasitic eggs, namely shell strength, might also have experienced divergent selection within cuckoo species. Host races of the common cuckoo Cuculus canorus encountering stronger host rejection have thicker‐shelled eggs than those parasitising less discriminating species, as expected if egg strengthening discourages host rejection. Moreover, in the diederik cuckoo Chrysococcyx caprius, eggshell thickness was correlated across cuckoo gentes and host species, as expected if eggshell strength has been involved in coevolutionary interactions. This is the first report of host‐specific differences in cuckoo egg properties other than colour and pattern and lends correlational support to the hypothesis that the strong eggshells of brood parasites are an adaptation to reduce host rejection.     

Morphometric Analyses of Retinal Sections

Morphometric analyses of retinal sections have been used in examining retinal diseases. For examples, neuronal cells were significantly lost in the retinal ganglion cell layer (RGCL) in rat models with N-methyl-D-aspartate (NMDA)–induced excitotoxicity¹, retinal ischemia-reperfusion injury² and glaucoma³. Reduction of INL and inner plexiform layer (IPL) thicknesses were reversed with citicoline treatment in rats'' eyes subjected to kainic acid-mediated glutamate excitotoxicity⁴. Alteration of RGC density and soma sizes were observed with different drug treatments in eyes with elevated intraocular pressure^3,5,6. Therefore, having objective methods of analyzing the retinal morphometries may be of great significance in evaluating retinal pathologies and the effectiveness of therapeutic strategies.The retinal structure is multi-layers and several different kinds of neurons exist in the retina. The morphometric parameters of retina such as cell number, cell size and thickness of different layers are more complex than the cell culture system. Early on, these parameters can be detected using other commercial imaging software. The values are normally of relative value, and changing to the precise value may need further accurate calculation. Also, the tracing of the cell size and morphology may not be accurate and sensitive enough for statistic analysis, especially in the chronic glaucoma model. The measurements used in this protocol provided a more precise and easy way. And the absolute length of the line and size of the cell can be reported directly and easy to be copied to other files. For example, we traced the margin of the inner and outer most nuclei in the INL and formed a line then using the software to draw a 90 degree angle to measure the thickness. While without the help of the software, the line maybe oblique and the changing of retinal thickness may not be repeatable among individual observers. In addition, the number and density of RGCs can also be quantified. This protocol successfully decreases the variability in quantitating features of the retina, increases the sensitivity in detecting minimal changes. This video will demonstrate three types of morphometric analyses of the retinal sections. They include measuring the INL thickness, quantifying the number of RGCs and measuring the sizes of RGCs in absolute value. These three analyses are carried out with Stereo Investigator (MBF Bioscience — MicroBrightField, Inc.). The technique can offer a simple but scientific platform for morphometric analyses.     

Variations in slice sensitivity profile for various height settings in tomosynthesis imaging: Phantom study

Understanding the properties of slice sensitivity profile (SSP), or slice thickness, is crucial for an accurate and highly reproducible diagnosis using tomosynthesis imaging. The objectives of the present study are therefore to quantitatively evaluate how the SSP with the use of a small metal bead is affected by different settings of the height from the table and the height of the center of rotation (COR) in tomosynthesis imaging except for the digital breast tomosynthesis, and visually verify the effects on tomosynthesis images. The reconstruction filters used were three types of filtered back-projection and iterative reconstructions. The SSP was measured from the full width at half maximum (FWHM-SSP) of the profile curve of the bead in the perpendicular direction (z direction) relative to the table. Two types of anthropomorphic phantoms simulating the human body, with bones and soft tissues, were used to study the effects of different settings for the COR height. In all reconstruction filters, the FWHM-SSP changed as the height of the bead varied when the bead and COR were set to the same height from the table. If the bead and the COR were set to different heights, the FWHM-SSP increased (decreased) when the height of the bead was set to be greater (less) than the height of the COR. These changes were also confirmed on the anthropomorphic phantom images of the bones and soft tissues.     

Over 100‐nm‐Thick MoOx Films with Superior Hole Collection and Transport Properties for Organic Solar Cells

Herein, a novel and effective method to prepare n‐doped MoO_x films with highly improved conductivity is reported. The MoO_x films are readily prepared by spin‐coating an aqueous solution containing ammonium molybdate tetrahydrate and vitamin C (VC). As confirmed by UV–vis absorption, X‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy measurements, Mo(VI) is partially reduced to Mo(V) by VC, resulting in the n‐doping of MoO_x. The conductivity of the n‐doped MoO_x (H:V‐Mo) film can be enhanced by four orders of magnitude compared to pristine MoO_x (H‐Mo), that is, from 1.2 × 10⁻⁷ to 1.1 × 10⁻³ S m⁻¹. The device using a 10 nm H:V‐Mo anode interlayer (AIL) exhibits comparable photovoltaic performance to a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)‐modified device. More importantly, the hole transport and collection properties of the H:V‐Mo AILs show outstanding tolerance to thickness variation, that is, with increasing thickness of the H:V‐Mo AIL from 10 to 150 nm, the V _oc and fill factor values of the devices remain unchanged. The device based on the blade‐coated H:V‐Mo AIL also has a high power conversion efficiency of 10.6%. To the best of the authors' knowledge, this work demonstrates the first example to prepare metal oxide AILs with outstanding tolerance to thickness, which is promising for the future large‐area manufacturing.     

Effects of seasonal snow cover on decomposition and carbon,nitrogen and phosphorus release of Picea schrenkiana leaf litter in Mt. Tianshan,Northwest China

季节性雪被下显著的冻融格局差异可能对干旱区山地森林凋落叶分解过程产生重要影响, 但一直未见深入研究。2015年10月至2016年10月, 采用凋落物分解袋法, 研究了天山典型树种雪岭云杉(Picea schrenkiana)凋落叶在季节性雪被覆盖下的3个关键时期(冻融期、深冻期、融冻期)以及生长季(生长季早期和生长季末期)的分解动态和碳、氮、磷释放特征。结果表明: (1)经过一年的分解, 不同雪被厚度下雪岭云杉凋落叶分解率为24.6%-29.2%, 且存在显著性差异。分解系数k值厚雪被覆盖最大, 无雪被覆盖最小。(2)冬季雪被覆盖期雪岭云杉凋落叶分解对当年分解总量的贡献达46.0%- 48.5%, 其中对冻融期凋落叶分解影响较为明显。(3)随着凋落叶的分解, 雪岭云杉凋落叶氮含量总体呈增加趋势; 碳含量和碳氮比大致呈下降趋势, 在深冻期和生长季末期不同雪被处理下碳含量呈显著性差异; 而凋落叶磷含量呈不规则变化趋势, 且在冻融期和融冻期不同雪被厚度下呈显著性差异。(4)整个雪被覆盖季节凋落叶氮元素表现为富集, 碳和磷元素表现为释放; 其中, 在融冻期薄雪被和中雪被处理下碳元素富集率最大, 在冻融期薄雪被、中雪被和厚雪被处理下, 融冻期无雪被和厚雪被下以及生长季早期中雪被和厚雪被下氮元素富集率最大, 而雪被对凋落叶磷释放的影响不显著。