Human Stn1 protects telomere integrity by promoting efficient lagging-strand synthesis at telomeres and mediating C-strand fill-in

Telomere maintenance is critical for genome stability. The newly-identified Ctc1/Stn1/Ten1 complex is important for telomere maintenance, though its precise role is unclear. We report here that depletion of hStn1 induces catastrophic telomere shortening, DNA damage response, and early senescence in human somatic cells. These phenotypes are likely due to the essential role of hStn1 in promoting efficient replication of lagging-strand telomeric DNA. Downregulation of hStn1 accumulates single-stranded G-rich DNA specifically at lagging-strand telomeres, increases telomere fragility, hinders telomere DNA synthesis, as well as delays and compromises telomeric C-strand synthesis. We further show that hStn1 deficiency leads to persistent and elevated association of DNA polymerase α (polα) to telomeres, suggesting that hStn1 may modulate the DNA synthesis activity of polα rather than controlling the loading of polα to telomeres. Additionally, our data suggest that hStn1 is unlikely to be part of the telomere capping complex. We propose that the hStn1 assists DNA polymerases to efficiently duplicate lagging-strand telomeres in order to achieve complete synthesis of telomeric DNA, therefore preventing rapid telomere loss.     

食管鳞癌组织中CDC2、CLDN5蛋白表达及其临床病理意义的研究

目的探讨CDC2及CLDN5在食管鳞癌中表达及其临床病理特征的关系。方法应用免疫组化Elivision法检测90例食管鳞癌组织、28例正常食管黏膜组织及16例重度不典型增生组织中CDC2和CLDN5的蛋白表达情况。结果在食管鳞癌和正常食管黏膜组织中CDC2和CI。DN5的阳性表达率分别为88．89％（80／90）、85．56％（77／90）和48．86％（12／28）、25．00％（7／28）,两者差异有统计学意义（P〈O．05）。CDC2蛋白表达在低分化食管鳞癌中明显高于高分化食管鳞癌;临床分期Ⅲ＋Ⅳ期组的CDC2蛋白的表达显著高于I期、Ⅱ期组（P〈O．05）。CDC2和CLDN5在食管鳞癌中表达呈正相关（r=0．537,P〈o．05）。结论CDC2和CLDN5在食管鳞癌的发生、发展过程中可能发挥重要作用,可能作为食管癌临床早期诊断的重要指标。     

小麦HMW-GS1Dx5基因的克隆及其特异性表达

显微切割了普通小麦钢８２－１２２（Ｔｒｉｔｉｃｕｍａｅｓｔｉｖｕｍ２ｎ＝４２）具有１Ｄｘ５＋１Ｄｙ１０亚基的１Ｄ染色体长臂端,利用ＰＣＲ扩增得到了ＨＭＷ－ＧＳ１Ｄｘ５亚基的５（端４００ｂｐ序列片段．以此作为探针从基因的组织特异性和特定发育阶段的表达两个方面研究了ＨＭＷ－ＧＳ１Ｄｘ５基因表达的规律．结果表明,干种子及萌发种子中存在此基因,而在发育的幼苗中此基因未表达．ＨＭＷ－ＧＳ１Ｄｘ５基因可能从开花初期开始表达．ＨＭＷ－ＧＳ１Ｄｘ５基因在籽粒成熟期表达,然而在营养器官如叶片中未表达,其表达存在组织特异性．ＨＭＷ－ＧＳ１Ｄｘ５基因在蜡熟期籽粒表达水平最高,其次是乳熟期籽粒．从开花１５ｄ至蜡熟期籽粒,表达趋于增加．开花１５ｄ其ｍＲＮＡ水平是蜡熟期籽粒ｍＲＮＡ的２８％,灌浆期为４０％、乳熟期为７２％、完熟期为５４％．这为进一步研究其表达调控和改善小麦品质打下基础     

Novel variant of p230 trans-Golgi network protein identified by serum from Sjögren's syndrome patient

Trans-Golgi network (TGN) protein p230 is a peripheral membrane protein associated with the cytoplasmic face of the TGN. TGNp230 is an extensively coiled-coil protein with flexible amino- and carboxyl-terminal ends, associates with non-clathrin-coated vesicles arising from the TGN, and is implicated in vesicle biogenesis. Here we used an autoimmune serum from a patient with S ogren's syndrome to clone partial cDNAs from a human hepatoma HepG2 expression library. The partial cDNAs encoded a novel amino-terminal splice variant of TGNp230. Specific reactivity of the autoimmune serum for p230 is supported by immunofluorescene staining of the Golgi apparatus, immunoblotting of a > 200-kDa HeLa cell protein, and reactivity with a bacterially expressed GST-p230 fusion protein. The alternative splicing occurs within the first proline-rich domain of p230. It comprises a deletion of 30 bp followed immediately by an additional 66 bp absent in the published sequence. RT-PCR analysis indicated that the splicing occurs independently of previously reported carboxyl-terminal splicing, and that this novel splice variant is more frequent than the previously reported p230. The novel splice variant of p230 is also located at the TGN. We propose that p230 splice variants may be implicated in selection of cargo molecules for vesicles arising from the TGN.     

Biodegradation of bisphenol A by cultured cells of Caragana chamlagu

The biological degradation of 2,2-bis(4-hydroxyphenol)propane (1; bisphenol A, BPA), a representative endocrine disruptor, was studied with plant-cultured cells of Caragana chamlagu. An initial BPA concentration of 425 microM in an aqueous solution was degraded by C. chamlagu at 25 degrees C for 2 days in the dark, and two intermediates were then completely dissipated after 10 days.     

Glucose biosensor based on electrodeposited platinum nanoparticles and three-dimensional porous chitosan membranes

The chitosan with three-dimensional porous structure greatly increased the effective electrode surface for loading of platinum nanoparticles and promoted efficient electron transfer. The resulting biosensor had a response time (within 5 s) and a linear response from 6 μM to 4.2 mM glucose with a detection limit of 2 μM (S/N = 3). Moreover, the methodology can be applied for the immobilization of other enzymes.     

动物源细菌耐药性研究现状与对策

目前我国动物源细菌耐药现象十分普遍,多重耐药甚至泛耐药的菌株不断出现,给公共卫生和食品安全造成了重大威胁。文中从我国动物源耐药性研究的主要问题、细菌耐药性形成和传播机制以及耐药性防控策略等几个方面进行综述,以期为耐药性的研究和防控提供参考。     

New triazole derivatives as antifungal agents: synthesis via click reaction, in vitro evaluation and molecular docking studies

A series of 1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-3-substituted-2-propanols (5a-5y) which are analogues of fluconazole, have been designed and synthesized via Cu(I)-catalyzed azide-alkyne cycloaddition on the basis of computational docking experiments to the active site of the cytochrome P450 14α-demethylase (CYP51). The in vitro antifungal activities of all the target compounds were evaluated against eight human pathogenic fungi. Compound 5l showed the best antifungal activities.