赭曲霉产生的脲酶抑制剂的提纯与动力学

对赭曲霉(Aspergillus ochraoeus)产生的脲酶抑制剂进行了纯化,经硅胶薄层层析和高效液相色谱鉴定达到均一,晶体呈白色针状。质谱及元素分析表明,该物质含C、H,O三元索,分子量为184,分子式是C_9H_(12)O_4,溶点105～110℃,其抑制作用随抑制剂浓度而增强,抑制类型为非竞争性。K为1.3×10~(-3)mol/L。抑制剂未改变酶的Hill系数,n=1。     

Genome-wide tagging SNPs with entropy-based Monte Carlo method.

The number of common single nucleotide polymorphisms (SNPs) in the human genome is estimated to be around 3-6 million. It is highly anticipated that the study of SNPs will help provide a means for elucidating the genetic component of complex diseases and variable drug responses. High-throughput technologies such as oligonucleotide arrays have produced enormous amount of SNP data, which creates great challenges in genome-wide disease linkage and association studies. In this paper, we present an adaptation of the cross entropy (CE) method and propose an iterative CE Monte Carlo (CEMC) algorithm for tagging SNP selection. This differs from most of SNP selection algorithms in the literature in that our method is independent of the notion of haplotype block. Thus, the method is applicable to whole genome SNP selection without prior knowledge of block boundaries. We applied this block-free algorithm to three large datasets (two simulated and one real) that are in the order of thousands of SNPs. The successful applications to these large scale datasets demonstrate that CEMC is computationally feasible for whole genome SNP selection. Furthermore, the results show that CEMC is significantly better than random selection, and it also outperformed another block-free selection algorithm for the dataset considered.     

Refolding, purification, and activation of miniplasminogen and microplasminogen isolated from E. coli inclusion bodies

Two des-kringle derivatives of human plasminogen, microplasminogen and miniplasminogen, have been expressed at high levels as inclusion bodies in Escherichia coli using a T7 expression system. In each case, the isolated inclusion bodies were refolded and purified. A final yield of 10% of total refolded protein was observed in each case. Both refolded molecules were successfully activated to their functional forms, microplasmin and miniplasmin, by the plasminogen activator urokinase. The kinetic properties of the refolded microplasmin and miniplasmin were comparable to full length, native plasmin.     

Design at the atomic level: generation of novel hybrid biaryloxazolidinones as promising new antibiotics

From the X-ray crystal structures of linezolid and the non-selective antibiotic sparsomycin, we have derived a new family of hybrid oxazolidinones. From this initial compound set we have developed a new biaryloxazolidinone scaffold that shows both potent antimicrobial activity as well as selective inhibition of ribosomal translation. The synthesis of these compounds is outlined.     

Cells captured from spatium intermusculare by porous material exhibit the characteristics of stem cells

Most of the current methods to capture stem cells are very complicated. Our new discovery of acquiring adult stem cells by implanting three dimension (3-D) porous material into the spatium intermusculare of mice hind limbs would bring hope to achieve autologous stem cells transplantation. We discovered that a great number of cells migrated into the 3-D porous material implanted in vivo. Furthermore, the migrating cells exhibited stem cell properties (CD34(+), Sca-1(+), GFAP(+), alphafetoprotein(+)) and were hematogeous (CD45(+)) and CD105(+). The ability of migrating cells to undergo differentiation into hematopoietic lineages was tested with methylcellulose medium. These findings demonstrate that the cells captured from spatium intermusculare by implanting 3-D porous material exhibit the characteristics of stem cells.     

白及种质资源及其近缘种的SSR指纹图谱研究

白及(Bletilla striata Rchb.)为中国珍稀濒危药用植物,野生资源枯竭,混伪种繁多。该研究基于SSR标记技术对16个地区48份白及(Bletilla striata Rchb.)样品和4份黄花白及(Bletilla ochracea Schltr.)、4份小白及(Bletilla formosana(Hayata)Schltr.)、4份华白及(Bletilla sinensis(Rolfe)Schltr.)样品进行遗传多样性分析,构建白及种质资源的SSR指纹图谱,并对60份白及样品进行种质资源鉴定,分析白及属种内及其种间的遗传分化特征。结果表明:(1)20对白及SSR引物均能在4个白及属植物中成功扩增,条带清晰且多态性丰富,每对引物的复等位基因数(Na)在4~9之间,等位基因数(Na)总和为127,平均为6.35。(2)筛选出基因型丰富、多态性信息含量(PIC)高的7对白及SSR引物(BJSSR01、BJSSR14、BJSSR15、BJSSR16、BJSSR18、BJSSR19、BJSSR22)构建的白及SSR指纹图谱能将白及属各种质资源清楚分开。(3)白及属在种间水平均有较高的遗传多样性(Na=6.35,I=1.429 1,h=0.706 8),物种间遗传分化强烈(Gst=0.44),物种间的基因流较弱(Nm=0.475 3)。(4)UPGMA聚类分析表明,60份供试样品明显聚为4大支,同一物种的个体首先聚在一起,这与形态学分类基本一致;不同来源地的样品种内和种间的亲缘关系有明显差异,地理距离较近的白及样品具有较近的遗传关系。     

遥感信息应用于区域尺度水分限制条件下作物生长模拟的研究进展

第2生产水平(即水分限制条件)下的大范围作物生长动态模拟研究具有十分重要的现实意义.目前,区域尺度上水分限制条件下作物生长模拟存在一定的难度,而遥感信息与作物生长模拟模型的结合,可以为区域尺度水分限制条件下作物生长发育模拟及产量估算提供了一条行之有效的途径.本文简要回顾了遥感与作物生长模拟模型结合研究的发展概况,指出了区域尺度水分限制条件下作物生长模拟需要解决的问题,并在已有遥感反演土壤水分状况研究的基础上,简述了遥感信息应用于区域尺度水分限制条件下作物生长模拟的研究方法,并探讨了当前该领域研究的其他可能途径及需要进一步研究和解决的科学问题.     

Comparisons of methods for linkage analysis and haplotype reconstruction using extended pedigree data

We compare and contrast the performance of SIMPLE, a Monte Carlo based software, with that of several other methods for linkage and haplotype analyses, focusing on the simulated data from the New York City population. First, a whole-genome scan study based on the microsatellite markers was performed using GENEHUNTER. Because GENEHUNTER had to drop individuals for many of the pedigrees, we performed a follow-up study focusing on several regions of interest using SIMPLE, which can handle all pedigrees in their entirety. Second, 3 haplotyping programs, including that in SIMPLE, were used to reconstruct haplotypic configurations in pedigrees. SIMPLE emerges clearly as a preferred tool, as it can handle large pedigrees and produces haplotypic configurations without double recombinant haplotypes. For this study, we had knowledge of the simulating models at the time we performed the analysis.