西藏拉萨市部分鸡场鸡沙门氏菌病流行病学调查

为了解拉萨市鸡沙门氏菌病的流行情况,探讨主要发病原因,2015年4月至2016年9月,对拉萨市5个县(区)12个集约化养鸡场进行了流行病学调查。结果显示:所采集的1 203份样品中,共检测出沙门氏菌589株,阳性率达48.96%,说明拉萨市鸡沙门氏菌感染较为普遍;在所检测的样品中,种鸡、种蛋检出率分别为41.00%和37.00%,说明种鸡沙门氏菌带菌现象较为严重;病鸡样品检出率为70.54%,其中成年鸡为57.63%、鸡舍环境样本阳性率为16.67%,饲料阳性率为11.60%,说明这些都是造成沙门氏菌水平传播的主要风险因素。     

Surrogate Correlations and Near-Infrared Diffuse Reflectance Sensing of Trace Metal Content in Soils

Near-infrared diffuse reflectance sensing (NIRS) of soils has been the object of considerable interest and research in the last few years. This has been motivated by the prospect that this method seems to provide a cheap, convenient alternative to conventional, time-consuming methods for the measurement of a wide range of soil parameters. In particular, various authors have advocated that NIRS could be used to measure rapidly and non-destructively the concentration of trace metals in surface soils. Correlation analyses between NIRS spectra and trace metal concentration have yielded inconclusive results to date, suggesting that trace metal concentration may belong to a class of “tertiary” soil parameters, linked to NIRS spectra through “surrogate”, or indirect, correlations, involving some other primary or secondary parameter like clay or organic matter content, to which NIRS spectra are very sensitive. To assess the validity of this surrogate correlation hypothesis in the case of trace metals, experiments were carried out with soil samples varying only in the amount of trace metals they contain. Field-aged Hudson and Arkport soil pots spiked with Cu and Zn, freshly spiked samples of the same soils, and samples of a metalliferous peat soil from Western New York naturally rich in Cd and Zn were subjected to NIRS under laboratory conditions. Detailed analysis indicates that the NIR spectrum is sensitive to sample handling, including the orientation of the samples in the NIRS instrument, but that, at the same time, there is no discernable effect of the presence of trace metals on any part of the NIR spectrum. These results provide strong experimental support to the hypothesis of “surrogate” correlation for trace metals, and indicate that trace metals, even in severely contaminated soils, should not interfere with the NIR sensing of primary or secondary parameters, like organic matter content. Further work is needed to determine if this feature of NIR spectra extends to other soil chemical parameters.     

高原环境下羊败血性链球菌灭活疫苗生产工艺探索

为了优化羊败血性链球菌灭活疫苗的生产工艺条件,本试验对羊败血性链球菌C55001株、C55002株种子液的培养基种类、培养时间及发酵时间进行优化,从而确定羊败血性链球菌C55001、C55002株灭活疫苗的最佳生产工艺条件.再采用最佳生产工艺条件制备1×108 CFU/mL、2×108 CFU/mL、3×108 CFU...     

高效液相色谱法测定伊维菌素脂质体药物的含量及包封率

本试验旨在建立伊维菌素脂质体载体药物含量及包封率测定的高效液相色谱法。Waters surfire C18柱(150 mm×2.1 mm,5 μm),流动相为乙腈—甲醇—水(62∶30∶8),流速1 mL/min,检测波长245 nm,进样量10 μL,柱温30 ℃。采用凝胶过滤法、透析法、冷冻超速离心法、超滤离心法4种方法对脂质体与药物进行分离。结果表明,在优化色谱条件下伊维菌素与辅料及溶剂峰均得到良好分离,伊维菌素在1～50 μg/mL浓度范围内线性关系良好(r=0.9998,n=5),最终采用超速冷冻离心法可将脂质体与药物很好的分离,伊维菌素脂质载体的包封率可达98.54%±1.6%。该方法准确可靠、简单快速,可用于伊维菌素脂质体载体药物含量及包封率的测定。     

西藏那曲县草地状况及其生物量的观测分析

选择那曲县不同类型草地,实地调查了草地基况以及牧草生长期（2007年5-8月）内具有代表性的6种优势牧草的产量和品质。调查内容包括：草地覆盖度、草地地上生物量、牧草与土壤含水量、草地退化程度以及鼠害情况。同时,选取草地植株样品以及010 cm表层土壤样品进行牧草品质和土壤养分分析。结果表明,藏嵩草Kobresia tibetica生长状况和地上生物量明显优于其他品种的草地;各样点土壤含水量、土壤养分、毒草所占的比重、鼠害、草地退化状况存在明显差异;从草地地上生物量与气象条件的关系来看,生物量分别与降水量、气温、地温之间均存在显著的正相关关系。从牧草品质来看,在综合考虑含氮量、粗蛋白、粗脂肪等因素的情况下,小嵩草K. pygmaea的品质要优于藏嵩草,点地梅Androsace umbellata品质最差。     

围封年限对西藏高寒草甸植被特征与土壤养分的影响

围栏禁牧是高寒草地恢复的重要技术手段之一,但学术界对适宜的围栏年限还存在较大争议。本研究以青藏高原腹地的高寒草甸草地为研究对象,比较分析了退化高寒草甸自由放牧、围封5年、围封7年和围封11年后植物多样性、生物量和土壤理化性质的变化。结果表明:1)相比自由放牧草地,不同年限围封显著提高了退化高寒草甸植物物种丰富度、多样性指数、盖度和地上生物量(P0.05)。不同围封年限之间,围封7年的物种丰富度和多样性指数最高,但与围封5年和围封11年无显著差异(P0.05)。围封5年的地上生物量最高,且与围封11年存在显著差异(P0.05)。2)围封降低了退化高寒草甸土壤容重,显著增加了土壤有机质含量(P0.05)。相比自由放牧草地,不同年限围封提高了高寒草甸土壤全氮、全磷含量。不同围封年限之间,土壤有机质含量随围封年限的增长而增加,土壤全氮和全磷无显著变化(P0.05)。3)总体而言,围封有效恢复了退化高寒草甸的植被与土壤。不同围封年限下,围封5年和7年更有利于退化高寒草甸的植被恢复。     

Long unfolded linkers facilitate membrane protein import through the nuclear pore complex

Active nuclear import of soluble cargo involves transport factors that shuttle cargo through the nuclear pore complex (NPC) by binding to phenylalanine-glycine (FG) domains. How nuclear membrane proteins cross through the NPC to reach the inner membrane is presently unclear. We found that at least a 120-residue-long intrinsically disordered linker was required for the import of membrane proteins carrying a nuclear localization signal for the transport factor karyopherin-α. We propose an import mechanism for membrane proteins in which an unfolded linker slices through the NPC scaffold to enable binding between the transport factor and the FG domains in the center of the NPC.     

2000—2014年改则县植被变化及草原保护政策实施效果评价

为评价改则县草原保护政策实施效果,在3S技术支持下,利用2000—2014年MODIS-NDVI资料,结合研究区气象数据、禁牧数据对改则县植被覆盖时空分布进行分析。结果表明：（1）改则县植被覆盖总体较差,多年平均结果植被指数主要分布在0~0.2之间,最大合成结果植被指数主要在0.1~0.3之间,空间分布表现为南部植被覆盖优于北部。（2）改则县夏季植被覆盖最好,春季植被覆盖最差,北部为昆仑山脉植被覆盖季节变化不大。（3）2000—2014年间改则县植被覆盖总体呈稳定状态,呈稳定状态的区域面积占全县总面积的45.46%,呈改善趋势的区域占全县总面积的11.28%,呈退化趋势的区域占全县总的面积的8.69%,改善区域大于退化区域。（4）2008—2014年间改则县降水量及气温变化不利于植被改善,草原保护政策对该县植被改善起到了较好效果。     

3种藏药复方抗ORFV作用研究

将岩青、轮叶棘豆等3种藏药材按一定比例配成复方,采用乙醇提取法进行提取,将浓缩药液用细胞维持液配制成1g／L的药液,并根据对兔肾细睁（PRK）安全浓度的测定结果,稀释成不同梯度浓度,分别与脓疱皮炎病毒（ORFV）加入到已培养24h的单层PRK中,通过M1TI’法测定OD值,分析其对ORFV病毒增殖的影响。经回归分析,复方药液在7．81—62·5mg／mL浓度范围内,药物浓度与活细胞存在线性关系,对病毒增势有显著的抑制作用（P〈0·05）。表明藏药材复方药液具有抗脓疱皮炎病毒感染的作用。