中国科学院内蒙古草原生态系统定位站学术交流会在京召开

中国科学院内蒙古草原生态系统定位站学术交流会已于1981年1月29日至2月3日在北京召开。参加这次会议的有中国科学院植物研究所、动物研究所、综合考察委员会及内蒙古大学等17个单位,42人。     

Expression of Oct4 in HCC and modulation to wnt/β-catenin and TGF-β signal pathways

Hepatocellular carcinoma (HCC) is considered as a disease of dysfunction of the stem cells. Studies on stem cells have demonstrated that Oct4 plays a pivotal role in embryo regulation. In order to understand the role of Oct4 in HCC and the relationship among Oct4 and wnt/β-catenin and TGF-β signal pathways, we have detected the expression of Oct4, Nanog, Sox2, STAT3 as well as the genes in wnt/β-catenin, and TGF-β families in HCC cell lines and in tumor specimens from HCC patients. The authors found that Oct4 was expressed in all of the four HCC cell lines and the tumor specimens from HCC patients. Some other genes were also expressed in them with different level including Nanog, Sox2, STAT3 and TCF3, wnt10b, β-catenin, ELF, Smad3 and Smad4. The ability of the clone formation and migration of the HepG2 decreased after Oct4 was knockdowned. Silencing of Oct4 and TCF3 in HCC cell line HepG2 revealed that there were complicated relationships among Oct4, wnt/β-catenin family and TGF-β family genes. Knockdowning Oct4 reduced the expression of TGF-β family genes ELF, Smad3, Smad4 and wnt/β-catenin family genes, wnt10b, and β-catenin but increased TCF3. In reverse, knockdowning TCF3 led to the increased expression of Oct4 and TGF-β family genes. In conclusion, the expression of Oct4 in HCC may play an important role as in stem cell. Because Oct4 improves not only the function of wnt/β-catenin, but also the TGF-β signal pathways, the significance of its expression in HCC might be more complicated than we evinced before.     

聚多曲霉菌原生质体和液泡的制备及优化

原生质体的大量制备是研究原生质体转化、诱变、融合等技术的关键,液泡的制备对研究液泡中分解、转运有机物的特性具有重要意义,但目前分离技术还不够成熟.本研究从聚多曲霉菌菌丝中分离原生质体和液泡并对分离条件进行优化,以聚多曲霉菌DJ515-2菌丝为材料,探索不同因素对原生质体和液泡制备分离效果的影响.结果表明,聚多曲霉菌DJ515-2在菌龄42 h,以3％纤维素酶、1％蜗牛酶和3％的溶壁酶组成复合酶液,25℃下酶解4 h,原生质体达到最大产量,为5.167×105个/mL.同时,在此基础上裂解液泡的最优条件为pH7.5、1.0mol/L KCl、0.020％Triton X-10,其产量达2.63×105个/mL,产率为原生质体的50.8％,相比采用多元碱化合物诱导真菌原生质体裂解释放液泡的产率增加了 40％～45％.本研究为真菌和植物的各种原生质体技术及基于亚细胞层面的研究提供了材料基础.     

分子文库展示技术

分子文库展示技术是一系列广泛应用于多肽、蛋白质及药物筛选和研究蛋白质间相互作用的有效的生物学技术。它将组合成的具有一定长度的随机序列寡核苷酸片段(或cDNA)克隆到特定表达载体中,使其表达产物(多肽片段或蛋白质结构域)以融合蛋白的形式展示在活的噬菌体或细胞表面。根据其蛋白质表达是否依赖于宿主表达系统,分为体内表达展示系统和无细胞展示系统(体外表达展示系统)。就其展示的部位不同又可分为噬菌体展示技术、细胞表面展示技术、核糖体展示技术、mRNA展示技术等。现对各种展示技术的基本原理及相关应用做简要综述。     

Trigoxyphins H and I: two new daphnane diterpenoids from Trigonostemon xyphophylloides

Two new daphnane diterpenoids (1 and 2), together with four known analogues (3-6) were isolated from Trigonostemon xyphophylloides. Their structures were elucidated by spectroscopic analysis. Compounds 1 and 2 were evaluated for in vitro cytotoxic activities against the SPCA-1 (human lung cancer) and BEL-7402 (human hepatocellular carcinoma) cancer cell lines. Trigoxyphin I (2) showed modest cytotoxicity against two tumor cell lines.     

Is GPR39 the natural receptor of obestatin?

GPR39, an orphan receptor belonging to the family of G protein-coupled receptors, was originally reported to be the receptor of obestatin. However recently, numerous reports have questioned this conclusion. In mammals, GPR39 was reported to be involved in the regulation of gastrointestinal and the metabolic functions. In this article, a latest and brief review on the receptor family, structure, distribution and physiological functions of GPR39 has been reported.     

hrpD6基因决定白叶枯病菌在烟草上的过敏反应和在水稻上的致病性

【目的】白叶枯病菌hrp基因簇由包括hrpD6在内的26个hpa-hrp-hrc基因组成,与植物互作后形成Ⅲ型分泌系统(T3S),将T3S效应分子注入寄主细胞中从而决定在非寄主上的过敏反应(HR)和在水稻上的致病性。但hrpD6基因是否参与了白叶枯病菌在非寄主上的过敏反应(HR)和在水稻上的致病性(pathogenicity)还不清楚。【方法】借助同源重组方法,本研究对白叶枯病菌hrpD6基因进行了突变。【结果】PCR和Southern杂交结果显示,hrpD6基因被成功敲除。烟草上测定结果显示,hrpD6突变体ΔPhrpD6丧失了HR激发能力。致病性测定发现,ΔPhrpD6在水稻苗期不能形成水渍症状,在成株期水稻上不具有致病性,并且细菌生长能力显著下降。功能互补结果显示,hrpD6基因可恢复ΔPhrpD6在烟草上激发HR和在水稻上的致病性以及在水稻组织中的生长能力。RT-PCR结果显示,hrpD6基因的转录表达不仅受水稻诱导,而且受hrpG和hrpX基因调控。不仅如此,hrpD6基因突变还影响T3S效应分子hpa1基因的转录表达和Hpa1蛋白的分泌,暗示hrpD6基因对hpa1基因转录表达具有调控作用。【结论】hrpD6基因的缺失导致白叶枯病菌不能激发烟草产生HR和和丧失在水稻上的致病性,主要是HrpD6对hpa1基因转录表达具有调控作用,并影响T3S效应分子Hpa1的分泌。这些结果为进一步分析hrpD6是否参与T3S分泌装置的形成和调控其它hrp基因的转录表达从而决定病菌在非寄主上的HR和在水稻上的致病性,提供了科学线索。     

Substrate modification with lysine 63-linked ubiquitin chains through the UBC13-UEV1A ubiquitin-conjugating enzyme

Protein modification with lysine 63-linked ubiquitin chains has been implicated in the non-proteolytic regulation of signaling pathways. To understand the molecular mechanisms underlying this process, we have developed an in vitro system to examine the activity of the ubiquitin-conjugating enzyme UBC13-UEV1A with TRAF6 in which TRAF6 serves as both a ubiquitin ligase and substrate for modification. Although TRAF6 potently stimulates the activity of UBC13-UEV1A to synthesize ubiquitin chains, it is not appreciably ubiquitinated. We have determined that the presentation of Lys(63) of ubiquitin by UEV1A suppresses TRAF6 modification. Based on our observations, we propose that the modification of proteins with Lys(63)-linked ubiquitin chains occurs through a UEV1A-independent substrate modification and UEV1A-dependent Lys(63)-linked ubiquitin chain synthesis mechanism.     

玉米直链淀粉生物合成多基因转化载体构建

淀粉分支酶基因sbe是影响玉米直链淀粉含量的主要因素,淀粉分支酶分为3种即sbeI、sbeIIa和sbeIIb,其中sbeIIb对直链淀粉含量影响效应最大,抑制玉米淀粉分支酶sbeIIb基因的表达可减少支链淀粉的含量,从而达到提高直链淀粉的目的;ADP-葡萄糖焦磷酸化酶(AGPase)是直链淀粉合成的关键酶,通过提高AGP表达量同样可提高玉米直链淀粉含量。以此为目的分别克隆了sbeIIb一段375bp高度保守区,玉米SBE基因一段175bp内含子,AGP完整开放阅读框,大麦胚乳特异启动子和ADPG基因终止子。构建了sbeIIb基因正、反义的hpRNA发夹结构,将该发夹结构与上述基因分别连接到pCAM-BIA3301上;构建得到包含sbeIIb基因干扰结构与AGP基因过表达的pCAMB-RSA多基因胚乳特异表达载体。为此,pCAMB-RSA载体的成功构建将为高直链淀粉玉米的培育奠定基础。     

Diagnostic Evaluation of Des-Gamma-Carboxy Prothrombin versus α-Fetoprotein for Hepatitis B Virus-Related Hepatocellular Carcinoma in China: A Large-Scale,Multicentre Study

An efficient serum marker for hepatocellular carcinoma (HCC) is currently lacking and requires intensive exploration. We aimed to evaluate the performance of des-gamma-carboxy prothrombin (DCP) for identifying hepatitis B virus-related HCC in a large, multicentre study in China. A total of 1034 subjects in three cohorts (A, B, and C) including HCC and various non-HCC controls were enrolled from 4 academic medical centers in China from January 2011 to February 2014. Blind parallel detections were conducted for DCP and AFP. The area under the receiver operating characteristic curve (AUC) was used to evaluate the diagnostic efficacies. In cohort A, which comprised 521 subjects, including patients with HCC, liver metastasis, liver cirrhosis (LC), and liver hemangiomas as well as healthy controls (HCs), the accuracy of DCP for distinguishing HCC from various controls was 6.2–9.7% higher than that of AFP. In cohort B, which comprised 447 subjects, including patients with HCC, LC, and chronic hepatitis B as well as HC, the accuracy of DCP was further elevated (12.3–20.67% higher than that of AFP). The superiority of DCP to AFP was more profound in the surveillance of early HCC [AUC 0.837 (95% CI: 0.771–0.903) vs. 0.650 (0.555–0.745)] and AFP-negative HCC [AUC: 0.856 (0.798–0.914)] and in discriminating HCC from LC (accuracy: 92.9% vs.64.71%). Higher DCP levels were associated with worse clinical behaviors and shorter disease-free survival. DCP not only is complementary to AFP in identifying AFP-negative HCC and in excluding AFP-positive non-HCC (liver cirrhosis), but also demonstrates improved performance in HCC surveillance, early diagnosis, treatment response and recurrence monitoring in the HBV-related population.