Receptor activation alters inner surface potential during phagocytosis

The surface potential of biological membranes varies according to their lipid composition. We devised genetically encoded probes to assess surface potential in intact cells. These probes revealed marked, localized alterations in the charge of the inner surface of the plasma membrane of macrophages during the course of phagocytosis. Hydrolysis of phosphoinositides and displacement of phosphatidylserine accounted for the change in surface potential at the phagosomal cup. Signaling molecules such as K-Ras, Rac1, and c-Src that are targeted to the membrane by electrostatic interactions were rapidly released from membrane subdomains where the surface charge was altered by lipid remodeling during phagocytosis.     

混合硝酸稀土对小麦幼苗琥珀酸脱氢酶活性的影响

混合硝酸稀土对小麦幼苗琥珀酸脱氨酶活性的影响为：当硝酸稀土浓度小于０．０５μｇ／ｌ时，稀土离子对酶活性无影响，当硝酸稀土浓度大于０．０５μｇ／ｌ后其浓度越大对酶活性抑制作用越强．在线粒体内膜外侧，存在一些位点，稀土离子通过与这些位点结合而间接抑制琥珀酸脱氢酶活性。ＥＤＴＡ去抑制能力要大于柠檬酸，据我们试验的结果，我们推测，稀土对酶活性的抑制是多位点作用，稀土与这些位点的结合力强弱不一。     

复合硝酸稀土对盐胁下冬小麦生育前期生长及生理生化的影响

本文研究了复合硝酸稀土对盐胁条件下冬小麦三叶期、拔节期生长及其生理生化的影响。结果表明，稀土可促进三叶期幼苗在盐胁条件下的生长，机理之一是稀土提高了膜保护系统活性，从而降低膜相对透性，减轻膜伤害；稀土可促进盐胁条件下拔节期新生叶的生长，延缓叶片衰老过程，从而延长叶片的功能期。     

Control of synaptic strength by glial TNFalpha

Activity-dependent modulation of synaptic efficacy in the brain contributes to neural circuit development and experience-dependent plasticity. Although glia are affected by activity and ensheathe synapses, their influence on synaptic strength has largely been ignored. Here, we show that a protein produced by glia, tumor necrosis factor alpha (TNFalpha), enhances synaptic efficacy by increasing surface expression of AMPA receptors. Preventing the actions of endogenous TNFalpha has the opposite effects. Thus, the continual presence of TNFalpha is required for preservation of synaptic strength at excitatory synapses. Through its effects on AMPA receptor trafficking, TNFalpha may play roles in synaptic plasticity and modulating responses to neural injury.     

Cell corpse engulfment mediated by C. elegans phosphatidylserine receptor through CED-5 and CED-12

During apoptosis, phosphatidylserine, which is normally restricted to the inner leaflet of the plasma membrane, is exposed on the surface of apoptotic cells and has been suggested to act as an "eat-me" signal to trigger phagocytosis. It is unclear how phagocytes recognize phosphatidylserine. Recently, a putative phosphatidylserine receptor (PSR) was identified and proposed to mediate recognition of phosphatidylserine and phagocytosis. We report that psr-1, the Caenorhabditis elegans homolog of PSR, is important for cell corpse engulfment. In vitro PSR-1 binds preferentially phosphatidylserine or cells with exposed phosphatidylserine. In C. elegans, PSR-1 acts in the same cell corpse engulfment pathway mediated by intracellular signaling molecules CED-2 (homologous to the human CrkII protein), CED-5 (DOCK180), CED-10 (Rac GTPase), and CED-12 (ELMO), possibly through direct interaction with CED-5 and CED-12. Our findings suggest that PSR-1 is likely an upstream receptor for the signaling pathway containing CED-2, CED-5, CED-10, and CED-12 proteins and plays an important role in recognizing phosphatidylserine during phagocytosis.     

大熊猫分布区珍稀濒危物种丰富度空间格局与热点区分析

分析物种丰富度格局和热点区是保护生物多样性的有效手段和途径。本文基于珍稀濒危物种名录信息,结合遥感影像、文献信息和专家经验,研究了大熊猫分布区内珍稀濒危物种及中国特有珍稀濒危物种的丰富度空间格局,确定了物种丰富度热点区,分析了大熊猫保护区对热点区保护的有效性。结果表明:大熊猫分布区内,与大熊猫同域分布的珍稀濒危物种有293种,包括哺乳动物109种、鸟类58种、爬行动物18种、两栖动物35种、高等植物73种;其中,IUCN极危物种11种、濒危物种48种、易危物种111种、近危物种74种,列入CITES附录Ⅱ2种,国家一级保护植物7种,国家二级保护植物36种;293种珍稀濒危物种中,133种为中国特有,19种为大熊猫分布区特有。大熊猫分布区中,岷山的文县和平武,邛崃山的汶川、宝兴和康定珍稀濒危物种丰富度最高,达到15~19种/km2,物种密集区呈块状或线状破碎化分布;秦岭山系、岷山山系和邛崃山系为中国特有珍稀濒危物种丰富度最高的集中分布区,丰富度为5~6种/km2;海拔1400~1600m和1800~2000m,分别为珍稀濒危物种和中国特有珍稀濒危物种丰富度最高的海拔区段,物种丰富度达186种和77种;800~2800m是珍稀濒危物种和中国特有珍稀濒危物种分布最密集的海拔范围,分别覆盖了88.4%的珍稀濒危物种和87.2%的中国特有珍稀濒危物种。大熊猫分布区有6个珍稀濒危物种丰富度热点区,占分布区总面积的10.5%,覆盖了分布区85%的珍稀濒危物种;中国特有珍稀濒危物种热点区,占分布区总面积的17.2%,覆盖了85%的中国特有珍稀濒危物种。大熊猫保护区,覆盖了27.6%的珍稀濒危物种热点区和21.4%的中国特有珍稀濒危物种热点区,保护了71.7%的珍稀濒危物种和70.7%的中国特有珍稀濒危物种。本研究结果可为提高大熊猫保护区的有效性和维护大熊猫种群的持续生存提供科学依据。      

输气管道置换投产工艺的研究与实践

对涩宁兰输气管道涩北—西宁段和西宁—兰州段,分别采用了加隔离器和不加隔离器两种置换工艺方案进行比较分析,指出传统的加隔离器置换工艺存在混气量大、隔离器损耗大的问题,尤其是在高程变化大的山区地段和管道的多弯头、变径处隔离器易被卡住,而不加隔离器置换工艺,具有混气量小,安全便捷的优点。     

直径355.6 mm管道复合耐磨皮碗结构设计及密封性能

为了减少某些特殊工况下,清管器和检测器皮碗在清管和检测过程中产生的皮碗偏磨现象。深入分析了导致皮碗出现偏磨的原因,提出一种适用于直径355.6 mm油气管道的复合耐磨皮碗结构设计方案。利用有限元模拟仿真分析方法验证了复合耐磨皮碗结构在不同管道壁厚下的适应能力和密封性能。结果表明:复合皮碗结构与不同壁厚管道的接触过程中,在保证固有密封性能的条件下,皮碗外边缘上的万向滚珠可以有效减少皮碗唇边与管壁之间的接触面积,分担皮碗唇边所受的正压力和接触应力。说明该复合耐磨皮碗结构设计方案具有可行性,可以有效减缓皮碗唇边磨损,减少皮碗偏磨现象的产生。该复合耐磨皮碗结构设计和密封性能的分析验证,对于丰富中国清管器和检测器用皮碗设计理念,完善清管器和检测器结构设计具有重要意义。     

采用塑料台基取代蜂蜡台基育王的研究

从王台接受率、育出王的初生重和卵小管数三个方面对采用塑料台基取代蜂蜡台基育王的可行性进行了探讨．试验结果显示：（１）塑料台基的王台接受率（７９．５５％）比蜂蜡台基的（９３．５２％）低，差异极显著（Ｐ＜０．０１）；（２）塑料台基育出王的初生重（Ｘ＝２２３．２３ｍｇ）与蜂蜡的（Ｘ＝２２１．２７ｍｇ）差异不显著（Ｐ＞０．０５）；（３）塑料台基育出王的卵小管数（Ｘ＝２６８．８２０５条）与蜂蜡的（Ｘ＝２６９．３３３３）差异不显著（Ｐ＞０．０５）．据此，我们认为塑料台基可取代蜂蜡台基培育蜂王．     

黑嘴病病原菌人工感染对中间球海胆吞噬作用相关免疫指标的影响

为探讨黑嘴病病原菌感染对中间球海胆Strongylocentrotus intermedius吞噬作用相关免疫指标的影响,选用壳径约2 cm的中间球海胆108只,用注射器针头刺入海胆体腔,再用浓度102 CFU/mL的黑嘴病病原菌液浸泡,经病原菌胁迫后0、1、6、12、24、48 h时测定各体腔细胞密度、细胞凋亡率、细...     

杯形砂轮精密磨削WC-Co涂层的磨削力

使用杯形砂轮进行磨削,可以获得较高的加工效率和表面质量.但由于杯形砂轮的平面磨削方式与普通外圆砂轮平面磨削存在差异,故传统的磨削力建模不适合杯形砂轮的平面磨削.为了从本质上解释杯形砂轮磨削力的各种现象,本文对杯形砂轮的磨粒切削过程进行了分析,提出了杯形砂轮有效磨削宽度的概念,分析了杯形砂轮磨削陶瓷涂层时的磨削力,建立了杯形砂轮精密磨削陶瓷涂层磨削力的理论公式.磨削力工艺试验结果验证了理论公式的有效性和正确性.     

Nitrogen nutrition diagnosis for cotton under mulched drip irrigation using unmanned aerial vehicle multispectral images

Remote sensing has been increasingly used for precision nitrogen management to assess the plant nitrogen status in a spatial and real-time manner. The nitrogen nutrition index (NNI) can quantitatively describe the nitrogen status of crops. Nevertheless, the NNI diagnosis for cotton with unmanned aerial vehicle (UAV) multispectral images has not been evaluated yet. This study aimed to evaluate the performance of three machine learning models, i.e., support vector machine (SVM), back propagation neural network (BPNN), and extreme gradient boosting (XGB) for predicting canopy nitrogen weight and NNI of cotton over the whole growing season from UAV images. The results indicated that the models performed better when the top 15 vegetation indices were used as input variables based on their correlation ranking with nitrogen weight and NNI. The XGB model performed the best among the three models in predicting nitrogen weight. The prediction accuracy of nitrogen weight at the upper half-leaf level (R²=0.89, RMSE=0.68 g m^–2, RE=14.62% for calibration and R²=0.83, RMSE=1.08 g m^–2, RE=19.71% for validation) was much better than that at the all-leaf level (R²=0.73, RMSE=2.20 g m^–2, RE=26.70% for calibration and R²=0.70, RMSE=2.48 g m^–2, RE=31.49% for validation) and at the plant level (R²=0.66, RMSE=4.46 g m^–2, RE=30.96% for calibration and R²=0.63, RMSE=3.69 g m^–2, RE=24.81% for validation). Similarly, the XGB model (R²=0.65, RMSE=0.09, RE=8.59% for calibration and R²=0.63, RMSE=0.09, RE=8.87% for validation) also outperformed the SVM model (R²=0.62, RMSE=0.10, RE=7.92% for calibration and R²=0.60, RMSE=0.09, RE=8.03% for validation) and BPNN model (R²=0.64, RMSE=0.09, RE=9.24% for calibration and R²=0.62, RMSE=0.09, RE=8.38% for validation) in predicting NNI. The NNI predictive map generated from the optimal XGB model can intuitively diagnose the spatial distribution and dynamics of nitrogen nutrition in cotton fields, which can help farmers implement precise cotton nitrogen management in a timely and accurate manner.     

稀土甘氨酸丁二酮肟配合物的研究

[目的]研究稀土甘氨酸丁二酮肟配合物的性质。[方法]合成3种稀土甘氨酸丁二酮肟配合物,通过元素分析、红外光谱、紫外光谱和热分析,研究配合物的组成和性质。[结果]稀土甘氨酸丁二酮肟配合物的通式为:RE(Gly)2(DMG)Cl3.3H2O,溶于无水乙醇和水,在乙醇溶液中属于1∶3电解质,氯离子全部处于配合物的外界。红外光谱说明稀土离子与DMG中羟基氧配位。紫外光谱中配合物的吸收峰红移和摩尔吸收系数增大。配合物在100℃左右产生微弱的脱水吸热峰,225~242℃产生配合物的骨架断裂吸热峰,415~492℃产生1或2个很强的氧化放热峰,热分解的最终产物为稀土氧化物。[结论]稀土甘氨酸丁二酮肟配合物具有相似的配位形式和结构类型。     

管道内检测器皮碗过盈量对其力学行为的影响

为了研究管道内检测器皮碗过盈量对皮碗力学行为的影响,以直径为800 mm的管道的内检测器皮碗为研究对象,分析聚氨酯材料的力学特性,建立用于分析管道内检测器皮碗过盈量的二维轴对称有限元模型。通过计算分析,得到了皮碗过盈量为0~10%时,唇缘接触应力、唇缘接触长度、夹持端角度、唇缘角度、皮碗折点内外侧应力的变化趋势,并拟合得到了过盈量与上述参数之间的关系。结果表明:随着皮碗过盈量增加,皮碗唇缘应力趋势由指数下降趋势逐渐转化为线性下降趋势;皮碗唇缘接触长度、夹持端角度的增长速率随皮碗过盈量增大而快速增加;折点内外侧应力增长速率均随皮碗过盈量增大而减小;皮碗唇缘角度随着皮碗过盈量增大而线性减小。     

鸡外周血白细胞吞噬试验的研究

[目的]确定鸡外周血白细胞吞噬葡萄球菌的最佳条件。[方法]使用葡萄球菌10145为吞噬材料,以瑞士染色法检测鸡外周血白细胞的吞噬活性。通过正交试验研究吞噬时间、吞噬温度、葡萄球菌浓度对外周血白细胞吞噬百分率(PP)和吞噬指数(PI)的影响,并对其进行形态观察。[结果]细菌浓度是影响白细胞吞噬指数的主要因素,白细胞吞噬指数最高的条件为:温度41℃,时间40 min,菌液浓度为5×106个/ml。各因素对白细胞吞噬指数的影响程度为:细菌浓度>时间>温度。[结论]该研究为白细胞吞噬功能的检测提供了一种较为简便、可靠的方法。     

施氏鲟抗热应激中草药免疫制剂的筛选

为筛选适用于鲟使用的抗热应激中草药免疫制剂,研究了中草药方剂对常温及高温应激情况下施氏鲟Acipenser schrenckii Brandt免疫性能的影响。在22℃养殖水温下,将1~+龄施氏鲟分为4个受试组,每组设两个平行,每个平行放30尾鲟,选取当归、鱼腥草和一种自组中草药复方(方四),分别以0.30、0.54、0.80 g/kg(体质量)的给药剂量对试验鲟口灌给药,每日1次,连续给药14 d,同时设立口灌蒸馏水的对照组;停药24 h后,每组取半数试验鲟于高温30℃下热刺激2 h后,与常温试验组共同采样,对试验鲟血清中蛋白含量、细胞吞噬和不同组织中溶菌酶活性进行测定。结果表明:方四和鱼腥草能有效抑制机体高温应激后血清中蛋白含量的异常增高;常温情况下,当归具有提高试验鲟细胞吞噬功能的作用;而方四不仅可以有效提高高温应激后机体的细胞吞噬作用,还可有效提高肝、血清、鳃和胃组织中的溶菌酶活性,并能在高温应激后保持其效果。研究表明,高温应激情况下,方四能有效保持施氏鲟机体内环境平衡,并促进机体细胞的吞噬作用和溶菌酶活性,可作为鲟抗热应激中草药免疫制剂进行深入研究。     

β-catenin在藏山羊切牙牙胚发育过程中的表达

研究β-catenin在藏山羊牙胚发育过程中的表达与分布变化,并探讨其在牙齿发育过程中的作用机制。制备藏山羊切牙各期标本,并采用免疫组化方法观察。结果表明,帽状期在星网层、内釉上皮、牙囊均为细胞核阳性表达;钟状早期在内釉上皮、牙乳头细胞核阳性表达;钟状晚期在颈环、牙尖细胞膜阳性表达;成釉期早期在成釉质细胞、成牙本质细胞阳性表达;成釉期晚期均阴性表达。β-catenin在早期牙胚发育中有特定的时空表达模式,通过参与Wnt信号通路和作为黏附分子两种方式,对确定牙胚的形态发生重要作用。     

Phagocytosis in the retinal pigment epithelium of the RCS rat

The retinal pigment epithelium of RCS rats, previously thought not to phagocytize photoreceptor outer segments, exhibited a peak of phagocytosis in vivo when animals were kept under conditions of cyclic lighting (12 hours of darkness and 12 hours of light). The peak occurred at 1 hour after the onset of light, with maximum and minimum levels of phagocytosis averaging about 5 percent of that found in the pigment epithelium of Osborn-Mendel rats used as a control. Eyecups that were obtained from Osborn-Mendel rats and maintained for up to 3 hours in organ culture demonstrated levels of phagocytosis that were sevenfold greater than those of unincubated controls. Likewise a tenfold increase occurred in incubated as opposed to unicubated RCS eyes, raising the possibility that phagocytosis could be experimentally stimulated in vivo.     

Vascular injury and lysis of basement membrane in vitro by neutral protease of human leukocytes

Frozen and thawed granules of human, peripheral-blood leukocytes rapidly produce hemorrhage when injected into animal tissues. The effect is blocked by inhibitors of proteolysis. The granule extract can digest vascular basement membrane in vitro at neutral pH. In addition, basement membranes of blood vessels damaged in vivo by the leukocyte fraction are found to be attenuated when examined by electron microscopy. The proteases of human leukocyte granules differ in several important respects from known lysosomal cathepsins and trypsin-like esterases. Polymorphonuclear neutrophils are a major source of the neutral proteases present in circulating white cells, and release these enzymes during phagocytosis of immune complexes.