A new method for determination of elastolytic activity using (14C) labeled elastin and its application to leukocytic elastase.

A new, highly sensitive and specific assay for elastolytic activity is described which employs insoluble elastin randomly labeled with [¹⁴C]. The substrate was prepared by labeling amino groups of the protein in vitro with [¹⁴C] methyl groups by reductive alkylation. The substrate was used to quantitate elastolytic activity from human leukocytes and to compare leukocytic elastase with pancreatic elastase. Purified human leukocytic elastase was approximately one-fourth as active as pancreatic elastase. Similar difference between leukocytic elastase and pancreatic elastase activities was found when the enzymes were tested against succinyl-L-alanyl-L-alanyl-L-alanine-p-nitroanilide, but not when t-BOC-L-alanine-p-nitrophenyl ester was used.     

The subunit fine structure of isolated, purified Na,K-adenosine triphosphatase : Freeze-fracture study

The ultrastructural features of a purified fraction of Na⁺,K⁺-adenosine triphosphatase (ATPase) isolated from dog kidney medulla were compared with those of the initial crude microsomal fraction in the purification sequence. Although both fractions consist of vesicular structures, the purified fraction is more homogeneous with respect to overall size and intramembrane protein particle size and distribution. Polyacrylamide gel electrophoresis profiles of both fractions reveal multiple proteins in the microsomal fraction but only two in the final purified fraction. The membranes of the pure fraction comprised one class of particles roughly 95–120 Å in diameter which represent the in vitro configuration of Na⁺,K⁺-ATPase.     

A sedimentation procedure for the detection of binding to concanavalin A and heparin to lipoproteins.

Specific enzymatic bands in disc gel electrophoresis are generally determined by either of two methods: (i) Gel is sliced and the enzymatic activity is assayed on each slice or (ii) gel is stained histochemically, if the product of the enzymatic reaction and the dye can form an insoluble precipitate, and the activity band is located on the gel by a color band. The former is laborious and often inaccurate in the calculation of electrophoretic mobility. The latter, often nonspecific, is not applicable when the enzymatic product cannot form an insoluble precipitate with the dye. Staining with tetrazolium salt has been widely employed for amine oxidase (1–6). However, this method has limitations: (i) Tetrazolium salt is nonspecific for amine oxidase and may show artifacts (6,7), and (ii) the use of tetrazolium salt is limited only to substrates containing indolamine such as tryptamine or serotonin (8). Other substrates, like benzylamine, the most active substrate for plasma amine oxidase, do not form a color band with tetrazolium salt.This communication reports a simple spectrophotometric method for the identification of the enzymatic activity band for amine oxidase on disc gel electrophoresis. Neither slice and assay nor staining is needed. This method may possibly also be used generally for other enzyme systems which have a specific absorption at ultraviolet or visible range.     

Antibody formation by one or both lymphoid populations present in chimeric marmosets

Development of an isoimmune serum capable of identifying a specific leukocyte antigen in the marmoset, Saguinus fuscicollis illigeri, permitted detection of lymphoid cell chimerism in this species by the cytotoxic test. This reagent was then used to identify the cell population in the chimera responsible for antibody production against a test antigen, sheep red blood cells. Primary in vitro antibody formation as measured by plaque-forming cells with blood leukocytes or splenic lymphocytes of six animals chimeric for the leukocyte antigen, MLA-1, revealed an immune response by both cell types of the chimeric population from three animals and a response by only one cell type in the other three.     

Formation of cartilage by non-chondrogenic cell types

Freshly excised embryonic rat skeletal muscle has been shown to form hyaline cartilage when organ cultured upon demineralized rat bone (bone matrix). Since skeletal muscle is composed of fibrous connective tissue (C.T.) as well as muscle cells, the cartilage could arise from either of these sources. The object of this study was to determine whether cartilage arose from fibrous connective tissue or muscle cells, or both, and whether the ability to form cartilage is limited to tissues derived from somatic mesoderm. Control experiments demonstrated that 19-day embryonic rat skeletal muscle formed cartilage when organ cultured on bone matrix after dissociation and cultivation in vitro, and that 11-day embryonic chick muscle also formed cartilage, although less reproducibly (3 out of 10 cases). Fibroblasts and skeletal muscle were cloned from similar suspensions of dissociated muscle in order to test these purified cell types. Dermis, vascular tissue, and tendons were mechanically removed prior to dissociation in order to eliminate fibroblasts from contaminant sources. Cloned fibroblasts, derived from rat skeletal muscle, formed cartilage in three out of three cases. It was not possible to clone sufficient rat skeletal muscle to place an aggregate onto bone matrix. An aggregate of several hundred chick skeletal muscle clones formed cartilage on bone matrix. The freshly excised C.T. capsules of embryonic chick thyroid and lung were tested for the ability to form cartilage as nonskeletal C.T. derivatives. The epithelial rudiments of thyroid and lung were also tested as endodermal derivatives. Chick cornea was similarly tested as an ectodermal derivative. Of these tissues, only the C.T. capsules formed cartilage. The results demonstrate that various C.T. cell types may alter their phenotype well after that stage at which their differentiation is thought to be stabilized, and that the ability to differentiate as cartilage may be common to all C.T. cells. The option of differentiating along a certain variety of pathways may depend more upon local conditions than on a predetermined pattern.     

基于景观地形的小流域单元减灾调控评价研究

近年来,中国诸多大中城市内涝灾害频发。武汉市作为城市内涝频发的典型城市,其建成区地表高度（20.0~24.0 m）大多低于外江常年所处的洪水位高度（23.9 m）,在区域性暴雨条件下,极易引发内涝灾害。武汉由于其内涝典型性,2013年被列为全国31个重点防洪城市之一,2015年被列入首批海绵城市试点城市之一。从城市内涝发生机理出发,以水文角度的小流域单元作为内涝风险区划的基本单元,利用小流域单元分析武汉市景观地形要素（地表高程、地表起伏度、地表粗糙度）与城市内涝积水密度的相关性及其影响程度,量算统计出小流域单元的内涝风险等级。基于此,提出武汉市小流域单元减灾地形调控评价。以武汉市作为城市内涝问题的研究案例,以期为武汉市内涝缓解提供新的思考路径,具有典型性和必要性。     

基于生态系统服务簇的深圳市生态系统服务时空演变轨迹研究

明晰生态系统服务的演变特征,有助于针对性的提出区域生态系统服务提升决策,对于维持和改善人类福祉、促进城市可持续发展具有重要意义。以深圳市为例,选取11种生态系统服务,以街道为基本空间单元,对生态系统服务结构特征进行分类,进而探究生态系统服务的长时序演变轨迹。结果表明,深圳市生态系统服务簇有6种类型,分别为水文调节主导型、文化支持潜力型、服务枯竭型、水文调节控制型、水源消耗型、生态保育型;1980—2015年深圳市大部分地区的生态系统服务簇结构稳定,变化明显的地区大多毗邻香港;生态系统服务簇的时空演变轨迹类型有8种,以持续型轨迹为主;生态系统服务簇的时空演变轨迹与城市扩张具有一定的一致性,表明城市扩张对生态系统结构和功能影响的主导性。     

乌鲁木齐山地草地生态系统服务价值变化评估——基于遥感与GIS

草地生态系统服务功能是指草地生态系统及其生态过程所形成和维持的人类赖以生存的自然环境及其有效性,中国干旱半干旱地区的草地退化严重制约着生态系统服务功能的。以乌鲁木齐市山地草地为研究靶区,利用遥感图像(Landsat TM/OLI)划分出7种不同草地类型并计算其生态系统服务价值(Ecosystem Service Values, ESV)。使用空间统计方法、网格分析、空间自相关等方法进一步分析研究区山地草地退化程度和ESV变化。结果表明:21年中,乌鲁木齐市草地生态系统服务价值呈现波动性下降趋势,年均减少0.27×10~7元。生态损失主要是由山地荒漠草地(7.44%)、山地荒漠草原草地(10.71%)、山地草甸草原草地(18.32%)和高寒草甸草地(40.69%)退化造成。单项生态系统服务价值中,草地对调节服务(土壤形成)和供给服务的贡献率较高。草地ESVs Moran平均值为0.869(1994—2015年),并且草地ESV与相邻网格(2 km×2 km)具有更高的空间相关性。草地ESV具有明显的空间分布特征,高ESV区基本上分布在南山山区,低ESV区主要分布在平原草地区,博格达山草地亚区呈现随机分布格局。研究区气候变化对草地的影响十分显著,平均气温、平均地表温度、湿度、蒸散量、降水量和风速对草地ESV变化均有一定的影响,过度放牧、不合理垦荒、药用植物过度开发、城市化等人为活动仍然是驱动草地退化的主要因子,因此亟需采取措施保育乌鲁木齐市山地草原生态系统。     

城市尺度的城乡建设用地潜力及空间格局匹配评价——以南昌市为例

随着经济快速发展和城镇化进程不断加快,土地开发强度日益增大,导致生态环境不断恶化,分析城乡建设用地承载能力及空间格局匹配情况,对解决土地利用不合理、生态破坏等问题具有重要意义。以江西省南昌市为例,首先从生态安全、自然条件、社会经济等方面构建指标体系,采用层次分析法和限制系数评价模型,进行城乡建设用地开发适宜性评价,然后测算城乡建设用地承载力、可承载城乡建设用地丰度;最后与现状城乡建设用地进行空间匹配度分析,并探讨可承载临界值、丰度与空间匹配度的相关性。结果表明：南昌市城乡建设用地最适宜区、较适宜区、较不适宜区和不适宜区面积分别为1466.19、1346.01、353.69 km²和3770.70 km²;研究区城乡建设用地可承载临界值和可承载潜力分别为41.25%和24.05%,各县（区）值差异较大,各县（区）可承载临界值和可承载潜力范围分别为19.43%-98.71%和5.65%-49.83%,可承载城乡建设用地丰度情况良好,各县（区）值介于0.19-1.50之间;研究区各县（区）空间匹配度范围为67.41%-99.25%;相关分析显示,空间匹配度与城乡建设用地可承载临界值和可承载城乡建设用地丰度均呈正相关关系。研究可为南昌市城乡建设用地合理开发利用和国土空间优化提供依据。