Supramolecular structures of peptide assemblies in membranes by neutron off-plane scattering: method of analysis

In a previous paper (Yang et al., Biophys. J. 75:641-645, 1998), we showed a simple, efficient method of recording the diffraction patterns of supramolecular peptide assemblies in membranes where the samples were prepared in the form of oriented multilayers. Here we develop a method of analysis based on the diffraction theory of two-dimensional liquids. Gramicidin was used as a prototype model because its pore structure in membrane in known. At full hydration, the diffraction patterns of alamethicin and magainin are similar to gramicidin except in the scale of q (the momentum transfer of scattering), clearly indicating that both alamethicin and magainin form pores in membranes but of different sizes. When the hydration of the multilayer samples was decreased while the bilayers were still fluid, the in-plane positions of the membrane pores became correlated from one bilayer to the next. We believe that this is a new manifestation of the hydration force. The effect is most prominent in magainin patterns, which are used to demonstrate the method of analysis. When magainin samples were further dehydrated or cooled, the liquid-like diffraction turned into crystal-like patterns. This discovery points to the possibility of investigating the supramolecular structures with high-order diffraction.     

铅锌镉联合染毒及营养干预对大鼠血液系统的影响研究

目的：了解铅锌镉联合染毒对大鼠血液系统的影响及营养干预对其损伤的修复作用。方法：选择SPF级初断乳Wistar大鼠72只,随机分为对照组、染毒组和干预组,分别采用生理盐水、铅锌镉联合染毒液及染毒后以营养干预液灌胃28天和56天之后,检测其血液系统中五元素和血细胞的指标。结果：染毒组较对照组大鼠血铜、血锌含量高,血钙含量低于对照组,差异均有统计学意义（P〈0．05）;染毒组血铜含量高于干预组,血钙含量低于干预组,差异均有统计学意义（P〈0．05）;干预组红细胞（RBC）计数、血红蛋白（Hb）、血细胞比容（HCT）均高于染毒组,差异均有统计学意义（P〈0．05）;对照组白细胞（WBC）计数高于染毒组、干预组,差异均有统计学意义（P〈0．05）。结论：铅镉对大鼠血铜、血钙、血锌水平有影响;综合营养干预对重金属元素造成的血液系统损伤有明显的拮抗作用,对血液系统有一定的保护及修复作用。     

基于最大熵生态位模型的中华穿山甲潜在适宜生境预测

中华穿山甲（Manis pentadactyla）属于全球极度濒危物种,也是我国一级保护动物。对中华穿山甲的非法捕杀曾导致其种群数量锐减。但是,近年来相关研究报道较少,穿山甲分布状况不明,极大地制约了对该物种的有效保护。搜集了近年来国内中华穿山甲的救护记录和救护新闻,甄别出67个记录分布点,利用最大熵模型软件（MaxEnt）进行因子筛选,结果表明最冷季度降水量、人口密度、年降水量、坡度、坡向、海拔等6个环境变量是与中华穿山甲分布显著相关的影响因子。基于6个主导环境变量构建的MaxEnt模型AUC平均值为0.961±0.014,预测结果达到极好标准。刀切法（Jackknife）表明,其中最冷季度降水量、年降水量、人口密度和海拔是影响中华穿山甲分布的主要因素。中华穿山甲适宜生境（出现概率大于0.498）具有以下特点：最冷季度降水量141.22-439.46 mm,年降水量1471.67-2386.56 mm,人口密度≥390人/km²,海拔<316.98 m。该模型预测中华穿山甲在我国的潜在分布适宜区主要位于我国长江以南地区,总面积约为74.27×10⁴ km²,占国土面积的7.73%,主要集中在江西、广东、湖南和广西省,面积分别占该区域的97.58%,89.65%,76.90%和73.08%;其次是浙江、福建、台湾和安徽省。湖北、江苏、四川、云南、贵州等省份也有中华穿山甲的零星分布。湖北东南部、江苏南部、浙江西南部和福建西北部等与江西接壤的区域也是中华穿山甲的重要潜在分布适宜区。明确中华穿山甲的潜在分布适宜区,可为该物种的种群保护和栖息地管理提供科技支撑。     

Growth of respiratory syncytial virus in primary epithelial cells from the human respiratory tract

Respiratory syncytial virus (RSV) is the most important cause of lower respiratory tract disease in infants and children. To study RSV replication, we have developed an in vitro model of human nasopharyngeal mucosa, human airway epithelium (HAE). RSV grows to moderate titers in HAE, though they are significantly lower than those in a continuous epithelial cell line, HEp-2. In HAE, RSV spreads over time to form focal collections of infected cells causing minimal cytopathic effect. Unlike HEp-2 cells, in which wild-type and live-attenuated vaccine candidate viruses grow equally well, the vaccine candidates exhibit growth in HAE that parallels their level of attenuation in children.     

Detection of protease-resistant cervid prion protein in water from a CWD-endemic area

Chronic wasting disease (CWD) is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. Although the exact mode of natural transmission remains unknown, substantial evidence suggests that prions can persist in the environment, implicating components thereof as potential prion reservoirs and transmission vehicles.^1–4 CWD-positive animals may contribute to environmental prion load via decomposing carcasses and biological materials including saliva, blood, urine and feces.^5–7 Sensitivity limitations of conventional assays hamper evaluation of environmental prion loads in soil and water. Here we show the ability of serial protein misfolding cyclic amplification (sPMCA) to amplify a 1.3 × 10⁻⁷ dilution of CWD-infected brain homogenate spiked into water samples, equivalent to approximately 5 × 10⁷ protease resistant cervid prion protein (PrP^CWD) monomers. We also detected PrP^CWD in one of two environmental water samples from a CWD endemic area collected at a time of increased water runoff from melting winter snow pack, as well as in water samples obtained concurrently from the flocculation stage of water processing by the municipal water treatment facility. Bioassays indicated that the PrP^CWD detected was below infectious levels. These data demonstrate detection of very low levels of PrP^CWD in the environment by sPMCA and suggest persistence and accumulation of prions in the environment that may promote CWD transmission.Key words: prions, chronic wasting disease, water, environment, serial protein misfolding cyclic amplification     

Temporal and spatial fluctuations of heavy metals in Opa Reservoir,Ile-Ife,Nigeria

The Opa Reservoir, established for water supply to the Obafemi Awolowo University community, over the years has received direct linkage to township drains as a result of the widening and dredging of its river channels. The current study aimed at documenting monthly heavy metal loads at its riverine, transition and lacustrine zones in 2012–2013. Most of the heavy metals, analysed using an atomic absorption spectrophotometer, occurred within wide ranges, with coefficients of variation ranging from 60% to 300%, although the differences in heavy metal loads between the different zones were statistically insignificant at both the surface and bottom levels. The overall order of dominance of the metals was Ni > Cu > Fe > Zn > Cd = Cr > Pb, with nickel concentration being very high throughout. Heavy metal total mean concentration was higher during the rainy season (1.889 mg l?1) than the dry season (1.503 mg l?1) irrespective of sampling sites, having highly significant seasonal differences (p < 0.001) in Ni, Cd, Fe and Cu concentrations. The mean concentrations of Zn (0.074 mg l?1), Fe (0.176 mg l?1), Cu (0.507 mg l?1) and Pb (0.004 mg l?1) were within the WHO acceptable limit. However, the recorded levels of toxic elements Cd (0.031 mg l?1) and Ni (0.905 mg l?1) pose potential health risk to water consumers.     

Isolation and characterization of microsatellites in Neogobius kessleri (Perciformes,Gobiidae) and cross‐species amplification within the family Gobiidae

Fourteen polymorphic microsatellites were isolated from Neogobius kessleri, a benthic fish of Ponto‐Caspian origin which has been recently introduced into the Middle and Upper Danube River. Number of alleles and heterozygosity per locus in a sample of 32 fish individuals ranged from two to four and from 0.13 to 0.75, respectively. These primers will be useful in determining the population structure of N. kessleri. In addition, successful cross‐amplification was obtained for four related species, N. melanostomus, N. fluviatilis, N. gymnotrachelus and Proterorhinus marmoratus. These microsatellite loci may be useful for the evaluation of the origin of non‐native goby populations.