牛尾草中一新的对映-贝壳杉烷型二萜

从牛尾草[Isodon ternifolius(D.Don)Kudo]的地上部分分离得到一个新的对映－贝壳杉烷型二萜,命名为牛尾草素H（1）,通过波谱方法鉴定了它的结构。此外,还分离得到5个已知的对映－贝壳杉烷型二萜化合物：香茶菜醛（2）,长管香茶菜素A,E和G（3－5）,开展香茶菜素E（6）,以及木樨草素（7）,芹菜素（8）,α－香树脂醇（9）,乌索酸（10）和2α－羟基乌索酸（11）。     

Soil inorganic carbon storage pattern in China

Soils with pedogenic carbonate cover about 30% (3.44 × 10⁶ km²) of China, mainly across its arid and semiarid regions in the Northwest. Based on the second national soil survey (1979–1992), total soil inorganic carbon (SIC) storage in China was estimated to be 53.3±6.3 PgC (1 Pg=10¹⁵ g) to the depth investigated to 2 m. Soil inorganic carbon storages were 4.6, 10.6, 11.1, and 20.8 Pg for the depth ranges of 0–0.1, 0.1–0.3, 0.3–0.5, and 0.5–1 m, respectively. Stocks for 0.1, 0.3, 0.5, and 1 m of depth accounted for 8.7%, 28.7%, 49.6%, and 88.9% of total SIC, respectively. In contrast with soil organic carbon (SOC) storage, which is highest under 500–800 mm yr⁻¹ of mean precipitation, SIC storage peaks where mean precipitation is <400 mm yr⁻¹. The amount and vertical distribution of SIC was related to climate and land cover type. Content of SIC in each incremental horizon was positively related with mean annual temperature and negatively related with mean annual precipitation, with the magnitude of SIC content across land cover types showing the following order: desert, grassland >shrubland, cropland >marsh, forest, meadow. Densities of SIC increased generally with depth in all ecosystem types with the exception of deserts and marshes where it peaked in intermediate layers (0.1–0.3 m for first and 0.3–0.5 m for latter). Being an abundant component of soil carbon stocks in China, SIC dynamics and the process involved in its accumulation or loss from soils require a better understanding.     

Human thrombin: drug stability and stabilization

Stabilization of enzymes is a key factor when using biocatalysis in practice. Each enzyme stability depends both on the structure of its molecule and on the effect of various environmental factors, thus, one of the methods of the enzyme stability preservation is the formation of optimal macromedium. Thus, water structure and enzyme hydration change in the presence of solvable additives that affects its stability and catalytic properties. The paper deals with a new method of stabilization of human thrombin developed by the authors. It is proposed to use some known organic-ligands which have ion group and different nonpolar hydrophobic groups instead of traditional additives (salts, aminoacids, polyols, polyethylene glycols etc.). Thrombin stabilization proceeds in the conditions something changed compared with traditional ones. Processes of thrombin stabilization by the above compound have been investigated, enzyme stability at different temperatures and long-term storage of diluted solutions of the preparation in different conditions have been studied. It has been established that rosselin and orange II are the most efficient ligands. Optimal finite concentrations of stabilizing agents make approximately 0.0012-0.0014 M which are rather low in the system thrombin-ligand. It has been found that diluted solutions of thrombin are more stable, than concentrated ones. In the latter case the process of autolysis is included that affects negatively the catalytic effect of the enzyme, as far as there occurs the change of thrombin molecule structure, especially of thrombin beta-chain sections, evoking conformational changes of some sites of its active centre. The experiments directed to increasing thrombin intensity in the presence of organic ligands rosselin and orange II are discussed in details. Special attention is given to autolytic method of thrombin inactivation. It is admitted on the basis of already obtained data that thrombin binding with organic ligands proceeds at the expense of anionic area of beta-domain of thrombin active centre where basic aminoacids arginin and lysine (Lys 68, Arg 78, Arg 77, Arg 66 etc.) were found. Under these conditions the hydrophobic interaction is provided at the expense of apolar binding of thrombin active centre area.     

水淹频率变化对鄱阳湖增强型植被指数的影响

水淹状况是湿地植被动态的重要影响因素。该研究基于谷歌地球引擎(GEE)平台, 利用2000-03-01至2020-02-29所有覆盖研究区域的MODIS遥感影像数据, 分析20年间水淹频率(IF)、增强型植被指数(EVI)的时空变化以及湿地植被对IF变化的响应, 得出以下结论: (1) 20年来鄱阳湖水文节律发生了明显改变, 高IF (IF > 75%)水域面积呈现下降趋势, 从2000年1 435.3 km²下降至2019年的510.25 km², 降幅为64.45%; (2)区域平均EVI呈显著上升趋势, 植被扩张主要集中在中部IF下降区域; (3)分析不同总水淹频率区域中平均EVI年际变化, 发现EVI与水淹状况的变化趋势相似, 2009年之后鄱阳湖水域面积萎缩趋势缓解, EVI增长速度出现下降; (4)鄱阳湖湿地植被主要沿水域面积萎缩方向扩张, 基于像元统计20年间IF与EVI的变化趋势, 发现它们在空间分布上高度吻合, 这种空间异质性进一步证实水淹状况起到调节植被动态变化的作用。     

The effect of various forms of thrombin on nonspecific high molecular weight substrates

The ability of native alpha- and non-coagulating gamma-thrombin to catalyze the hydrolysis of nonspecific high molecular weight substrates was studied using chymotrypsinogen and the oxidized insulin B-chain as substrates. The effect of thrombin on chymotrypsinogen was estimated by the appearance of caseinolytic activity measured by the increase in the number of terminal NH2-groups in the 2,4,6-trinitrobenzol sulfonic acid reaction. The same reaction was used to study the hydrolysis of insulin by thrombin. It was found that the destruction of the additional center necessary for fibrinogen proteolysis during the alpha-thrombin conversion to the gamma-form did not affect the enzyme ability to hydrolyze nonspecific protein substrates. It was assumed that the low efficiency of non-physiological high molecular weight substrate hydrolysis by thrombin is due to the lack of specific remote interactions in the regulatory site outside the enzyme active center.     

Preparation and properties of trypsin from the pyloric caeca of Pacific Ocean salmon

Trypsin from pyloric caeca of Pacific salmon was purified by affinity chromatography of the water extract on hexamethylenediamine-glycidylmethacrylate-cellulose. A protein band with a molecular weight of 22.5 kDa was found on SDS-electrophoresis in PAG. The protein band was homogeneous according to isoelectrofocusing in PAG (pI 4.0). The amino acid composition of the enzyme is typical of trypsin anionic forms; the major difference from the cationic forms is the lower content of lysine. The differences in properties caused by change of the enzyme molecule charge are similar to those observed in cationic trypsin when the lysine epsilon-amino groups of the latter are modified (change of pI, shift of the pH-optimum towards basic values, increase of stability to autolysis). Some natural trypsin inhibitors of the different origin suppressed the enzyme activity of trypsin from Pacific salmon in typical stoichiometric ratios. An unusual interaction of the enzyme with the specific inhibitor N-L-tosyl-L-lysine chloromethyl ketone was observed.     

Global transcriptional response of pig brain and lung to natural infection by Pseudorabies virus

Background  

Pseudorabies virus (PRV) is an alphaherpesviruses whose native host is pig. PRV infection mainly causes signs of central nervous system disorder in young pigs, and respiratory system diseases in the adult.