硫霉素环化酶基因在变铅青链霉菌TK24中的表达及基因定位

将含有硫霉素环化酶基因的重组质粒p6BCl2转化变铅青链霉菌(Streptomyceslividans)TK24,含有p6BCl2的转化子细胞抽提液分别与琉霉素生物合成阻断变株Y,发酵液以及纯化的Y。中间产物经过体外共培养可产生活性物质．化学分析表明与Y,发酵液混合后产生的是硫霉素,与纯化的Y。中间产物混合产生的是一种不稳定的活性物质。说明硫霉素环化酶基因在S.lividans TK24中得到了表达,其产物以Y。中间产物为底物并弥补了Y,中的缺陷。对p6Bcl2中4．5kb外源片段进行了限制酶酶切分析,建立了酶切图谱．利用含硫霉素环化酶基因的S．Lividans TK24转化子体外转化Y,的应用体系,将硫霉素环化酶基因定位在0．9kb Hinc I—Pst I片段上,并证明了硫霉紊环化酶的活性与IPNS同源片段无关。以上实验为进一步研究琉霉素环化酶基因的结构打下了基础。     

格尔德霉素生物合成的调控基因

从吸水链霉菌17997中克隆了格尔德霉素(Geldanamycin, Gdm)生物合成酶基因簇, 通过生物信息学分析发现两个LAL(Large ATP-binding regulators of the LuxR family)家族的调控基因gdmRI和gdmRII, 基因阻断和基因回复实验证实这两个基因产物都正调控Gdm的生物合成。     

青藏高原冬小麦冠层几何结构、光截获及其对光合潜能的影响

在西藏拉萨测量了藏冬系列３个冬小麦品种的冠层几何结构及冠层地光合有效辐射（ＰＡＲ）的反射率,透过率和截获率,通过实测和理论计算。结果表明,高原地区冬小麦叶片比平原地区的更趋于直立,具有比平原地区低的消光系数,能够容纳较大的绿叶面积和有效穗数,当冠层的ＰＡＲ的截获率趋于饱和时,高原地区麦田可容纳的最大绿叶面积可达８．６,是平原地区的１．４倍左右,开花到成熟期间的叶日积（ＬＡＤ）大约可达平原地区的２倍     

海洋来源节菱孢菌ZSDS1-F3中PKS-NRPS类天然产物挖掘

【目的】以基因组信息为指导,定向激活海洋来源真菌Arthrinium arundinisZSDS1-F3中沉默的聚酮合成酶-非核糖体肽合成酶(PKS-NRPS)类生物合成基因簇,鉴定次级代谢产物结构。【方法】通过启动子工程和异源表达的策略激活实验室培养条件下沉默或低表达的生物合成基因簇,实现目标化合物的分离,通过HR-ESI-MS和NMR数据分析鉴定产物结构,结合基因重组和生物信息学分析结果推导化合物的生物合成途径。【结果】依据基因组生物信息学分析,从海洋来源真菌A. arundinis ZSDS1-F3中选取一个编码PKS-NRPS类次级代谢产物的生物合成基因簇开展研究,在宿主Aspergillus nidulansA1145中实现了基因簇的异源表达,从中分离到2个新化合物,并推导了其生物合成途径。【结论】基因组信息指导下的天然产物挖掘,可以目标明确地分离产物,加快真菌中新颖天然产物的发现步伐。     

格尔德霉素生物合成的调控基因

从吸水链霉菌17997中克隆了格尔德霉素(Geldanamycin, Gdm)生物合成酶基因簇, 通过生物信息学分析发现两个LAL(Large ATP-binding regulators of the LuxR family)家族的调控基因gdmRI和gdmRII, 基因阻断和基因回复实验证实这两个基因产物都正调控Gdm的生物合成。     

武陵山放线菌多样性

[目的]为了探究武陵山放线菌多样性,以便从新放线菌菌株中发现新的潜在药物先导化合物.[方法]从武陵山采集280份土样,采用纯培养的方法,用4种培养基分离到1134株放线菌.选择其中30株代表菌进行了初步分类鉴定;以3株细菌和7株农作物致病真菌作为指示菌,检测其抑菌活性;利用特异性引物扩增的方法,检测是否具有聚酮合酶(PKS Ⅰ、PKSⅡ)基因、非核糖体多肽合成酶(NRPS)基因和多烯类化合物合成酶(CYP)基因.[结果]分离到的武陵山放线菌中,链霉菌占70%以上,还有小单孢菌等8个科13个属,其中有5个菌株是潜在的新种.选取的30株实验菌对细菌、真菌有不同程度的抗菌活性;其中含有4类化合物合成基因的菌株占23%～60%.[结论]武陵山原始森林土壤中,放线菌多样性很丰富,且存在很多未开发的稀有类群.有抑菌活性的菌株,可用于进一步的药物开发利用.     

MR-1 modulates proliferation and migration of human hepatoma HepG2 cells through myosin light chains-2 (MLC2)/focal adhesion kinase (FAK)/Akt signaling pathway

The key of cell migration process on solid substrates is phosphorylation of myosin light chain-2 (MLC2), which is implicated in a variety of intracellular functions. The previous data show that MLC2 interacts with a novel human gene, myofibrillogenesis regulator 1 (MR-1). Here, we reported that MR-1 was specially overexpressed in human hepatoma HepG2 cells. Transient treatment of cells with small interfering RNA (siRNA) against MR-1 or stable transfection of cells with plasmid expressing MR-1-siRNA led to inhibitions of cell proliferation, migration, and adhesion. Following down-regulation of MR-1, the phosphorylations of MLC2, focal adhesion kinase (FAK), and Akt were dramatically decreased, and the formation of stress fiber was destroyed by MR-1-siRNAs in hepatoma HepG2 cells. In addition, exogenous MR-1-induced as well as inherent phosphorylations of FAK and Akt were decreased by MLC kinase (MLCK) inhibitor, and F-actin polymerization inhibitor also decreased phosphorylations of FAK and Akt. Correspondingly, MR-1-enhanced migration of cells was also inhibited by these two inhibitors. These indicated that MLC2 activation and intact actin cytoskeleton were pivotal for MR-1 function. In vivo data showed that MR-1-siRNA markedly inhibited growth of human HepG2. This study suggested that overexpression of MR-1 was associated with cancer cell proliferation and migration through MLC2 and that MR-1 might be a potential cancer therapeutic target.     

Piezochromic Phenomena of Nanometer Voids Formed by Mono-Dispersed Nanometer Powders Compacting Process

Piezochromism describes a tendency of certain materials changing colors when they are subjected to various pressure levels. It occurs particularly in some polymers or inorganic materials, such as in palladium complexes. However, piezochromism is generally believed to work at high pressure range of 0.1–10 GPa. This research work focused on unique piezochromism responses of the nanometer voids formed by the 5–20 nm inorganic ISOH nanometer powders. It was discovered that microstructures of the nanometer voids could change color at very low pressures of only 0.002–0.01 GPa; its sensitivity to pressure was increased by tens of times. It is believed that the uniform microstructures of nanometer powders contributed to the material''s high sensitivity of piezochromic phenomena. One factor which quantum optical change caused by nanometer voids affected the quantum confinement effect; another is surface Plasmon Resonance of great difference dielectric property between conductive ITO powder and insulation hydroxide.     

Thiazinogeldanamycin, a new geldanamycin derivative produced by Streptomyces hygroscopicus 17997

A new geldanamycin (GDM) derivative was discovered and isolated from the fermentation broth of Streptomyces hygroscopicus 17997. Its chemical structure was elucidated as thiazinogeldanamycin by LC-MS, sulfur analysis, and NMR. The addition of cysteine to the fermentation medium significantly stimulated the production level of thiazinogeldanamycin, suggesting cysteine as a precursor of thiazinogeldanamycin production. Although showing a decreased cytotoxicity against HepG2 cancer cells, thiazinogeldanamycin exhibited an improved water solubility and photostability. Thiazinogeldanamycin may represent the first natural GDM derivative characterized so far that uses GDM as its precursor. Its appearance also clearly indicates that an appropriate end-point of fermentation is of critical importance for the maximal production of GDM by Streptomyces hygroscopicus 17997.