格网尺度下典型旅游城市生态服务价值估算和时空分异特征——以三亚为例

以典型旅游城市三亚市为案例地，利用2006-2018年4期Landsat遥感影像数据，借助ENVI、ArcGIS平台定量识别土地利用演变特征，在1km×1km格网尺度下估算旅游地生态系统服务价值，并结合空间探索性数据分析揭示生态系统服务价值时空分异特征及其与旅游地发展的时空耦合关系。结果表明：（1）2006-2018年间，三亚市生态系统服务价值总量呈逐年下降趋势，由6.73×10⁹元降至5.76×10⁹元，累计减少9.78×10⁸元；（2）空间格局上，三亚市呈"南低北高"空间分异格局，2006-2018年增值区域连片分布于崖州区、天涯区、吉阳区南部区域，且呈逐年减少趋势，减值区域集聚于天涯区东北部、海棠区；（3）空间集聚上，生态系统服务价值截面各年份均呈显著空间正相关且相关性先降后增。高高集聚区位于天涯区北部区域，低低集聚区分布于沿海、海湾地区；（4）旅游发展与生态系统服务价值时空演化特征关联性较强。三亚市天涯区北部林地生态环境良好，生态系统服务价值略有下降但绝对数值稳定，是生态系统服务价值主要来源；旅游发展较为迅速的三亚湾、崖州湾以及海棠湾，相对增值区域较多，但绝对生态系统服务价值损失显著，严重滞后于其他区域。     

Copper and endogenous mediators of estradiol action

Divalent copper increases by severalfold specific estradiol binding in rat uterine cytosol at 37 degrees C. Two endogenous substances have now been isolated from the cytosol one of which sharply inhibits the copper effect while the other sharply promotes it. The inhibitor is thermostable, it is adsorbed by dextran coated charcoal and elutes from Sephadex columns with water. The promoter is thermolabile at 60 degrees C, it is not readily adsorbed by the charcoal and elutes from Sephadex columns with KCl. The two substances are thought to be mediators of estradiol action.     

Recent advances in identifying the functions of gangliosides

The recent development of several new approaches has proven extremely useful in identifying functions for gangliosides, the sialic-acid containing glycosphingolipids. The first is the incorporation of exogenous gangliosides into the plasma membrane of ganglioside-deficient cells. Using this approach, specific gangliosides have been identified as the receptors for certain bacterial toxins and viruses and as important factors in the organization of fibronectin into an extracellular matrix. The second approach has been a ligand blotting technique which allows detection of ganglioside-binding proteins such as toxins and antibodies. Gangliosides are separated by thin-layer chromatography and overlain with the protein of interest. Specific binding of the ligand to gangliosides can then be detected by either direct or indirect methods. The third approach is the use of the B or binding subunit of cholera toxin as a specific probe for endogenous plasma membrane ganglioside function. The ability of the B subunit to alter the growth of cells directly demonstrates a role for gangliosides as biotransducers of signals for the regulation of cell growth.     

斑纹小贻贝(Mytella strigata)基础生物学与生物入侵

生物入侵是继栖息地破坏之后，全球生物多样性丧失的第二大驱动因素。近年来，原产于南美洲地区的斑纹小贻贝（Mytella strigata）在印度-西太平洋海区被陆续报道，而我国台湾、广东、海南、福建、广西等省份同样发现斑纹小贻贝，且其已经建立可自我维持的种群。但是，作为一种新型入侵生物，斑纹小贻贝尚未引起国内海洋管理部门和科研人员足够重视，亟待查明其在我国沿海的分布现状、扩散趋势和生态影响等，为斑纹小贻贝的检测、监测、防控和管理提供科学依据。综述了斑纹小贻贝的基础生物学特征和全球生物入侵现状，发现国内的斑纹小贻贝源于南美洲加勒比海地区，于2014年左右通过船舶压舱水或船体生物污损的形式侵入我国南方沿海并迅速扩散。此外，斑纹小贻贝在我国的生物入侵处于"引进-传播"阶段，即将大规模扩繁，因此亟需开展应急清除行动。     

酸敏感离子通道与脑梗死

急性脑梗死约占全部脑卒中的70%,病死率和致残率高,且极易复发。但目前针对急性脑梗死在时间窗内溶栓、抗凝等治疗手段不能从根本上切实有效地修复受损脑组织,且伴有出血等风险。寻找脑梗死形成发展的原因并予以治疗迫在眉睫。酸中毒是引起缺血性脑损伤的重要机制。大量实验研究表明,酸中毒能加重神经元的缺血性损伤,且其梗死面积与酸中毒的程度直接相关。但缺血产生的酸中毒如何引起神经元损伤的确切机制尚不明确。最近研究发现酸中毒能激活一种在中枢及周围神经中广泛存在的膜通道,即酸敏感离子通道,它对Ca2+通透,能引起细胞内Ca2+超载,同时能激活胞内酶引起细胞内蛋白质、脂类及核酸的降解,加重缺血后脑损伤。本文就酸敏感离子通道1a与脑梗死做一综述。     

Reconstitution of the rat liver vasopressin receptor coupled to guanine nucleotide-binding proteins

The V1 vasopressin receptor has been solubilized from rat liver membranes with the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammoniol]-1-propanesulfonate (CHAPS) and reconstituted into phospholipid vesicles. There is essentially complete solubilization of the receptor by 3% CHAPS at a protein concentration of 15 mg/ml. Reconstitution into soybean phospholipid vesicles is readily achieved either by gel filtration chromatography or by membrane dialysis. The binding of [3H]vasopressin to proteoliposomes is specific, saturable, reversible, and magnesium-dependent. In contrast, the detergent-soluble vasopressin receptor does not display specific binding. The apparent affinity of the reconstituted receptor for [3H]vasopressin is approximately 4-fold lower than that of the receptor in native membranes. In addition, the binding of [3H]vasopressin to reconstituted vesicles is not sensitive to 100 microM guanosine 5'-O-thiotriphosphate (GTP gamma S) as it is in native membranes. However, the apparent affinity of the reconstituted receptor for ligand approximates that of native membranes when membranes are prebound with vasopressin prior to solubilization and reconstitution into vesicles. Furthermore, vesicles reconstituted from membranes prebound with vasopressin show GTP gamma S sensitivity of [3H] vasopressin binding. This finding strongly suggests that vasopressin stabilizes a receptor-G-protein complex during solubilization. The rat liver vasopressin receptor is a glycoprotein, as shown by its specific binding to the lectin "wheat germ agglutinin." The vasopressin receptor can be reconstituted from the N-acetylglucosamine-eluted peak of a wheat germ agglutinin-Sepharose column, and [3H] vasopressin binding activity is purified 5-6-fold from membranes by this chromatographic procedure. The functionality of the partially purified receptor is indicated by its ability to bind ligand with high affinity and by its ability to functionally interact with a G-protein when vasopressin is bound prior to solubilization.     

Lysosomal enzyme precursors in coated vesicles derived from the exocytic and endocytic pathways

The molecular forms of two lysosomal enzymes, cathepsin C and cathepsin D, have been examined in lysosomes and coated vesicles (CVs) of rat liver. In addition, the relative proportion of these lysosomal enzymes residing in functionally distinct CV subpopulations was quantitated. CVs contained newly synthesized precursor forms of the enzymes in contrast to lysosomes where only the mature forms were detected. Exocytic and endocytic CV subpopulations were prepared by two completely different protocols. One procedure, a density shift method, uses cholinesterase to alter the density of CVs derived from exocytic or endocytic pathways. The other relies on electrophoretic heterogeneity to accomplish the CV subfractionation. Subpopulations of CVs prepared by either procedure showed similar results, when examined for their relative proportion of cathepsin C and cathepsin D precursors. Within the starting CV preparation, exocytic CVs contained approximately 80-90% of the total steady-state levels of these enzymes while the level in the endocytic population was approximately 10-13%. The implications of these findings are discussed with regard to lysosome trafficking.     

黑龙江省三江平原丹顶鹤的数量分布

在地面调查的基础上,我们使用Y-11轻型飞机对黑龙江省三江平原地区的丹顶鹤的数量分布近行了调查,调查时飞行高度80米,航速140公里/小时,续航里程共3748公里。调查结果表明,丹顶鹤在三江平原主要分布在8个地区,其中嘟噜河下游、洪河自然保护区、七星河流域和兴凯湖低地是主要繁殖地,总数量共309只。