端粒酶与端粒的研究进展

端粒是真核生物染色体末端的一种特殊的DNA-蛋白质结构,对染色体的稳定性有重要作用.端粒酶是一种由蛋白质和RNA组成的核糖核蛋白复合物.端粒酶活性的测定方法主要是以TRAP为基础的改良法.近来,越来越多的研究结果表明在多数肿瘤、细胞癌变和衰老过程中都可检测到很高的端粒酶活性和端粒长度缩短.但同时也有许多不依赖端粒酶的端粒维持和细胞永生.目前,有关以端粒酶为靶位点的药物设计的研究已广泛开展.     

Multicolor FISH analysis of rDNA and telomere on spinach

In this study, multicolor fluorescence in situ hybridization (FISH) analysis on metaphase chromosomes of spinach with biotin-labeled 25S rDNA, DIG-labeled telomere sequences and biotin-labeled and DIG-labeled 5S rDNA was performed. There were six 25S rDNA loci located on the satellites of the third, the fifth and the sixth chromosomes, and four 5S rDNA loci located on the long arms of the third and the fifth chromosomes. The telomere loci were located on the end of the sixth chromosome and also on both the end and centromeric regions of other chromosomes. This study is an important complement to both traditional karyotype analysis and FISH karyotype analysis in spinach. __________ Translated from Hereditas (Beijing), 2007, 29(11): 1405–1408 [译自: 遗传(北京)]     

Pot1, the putative telomere end-binding protein in fission yeast and humans

Telomere proteins from ciliated protozoa bind to the single-stranded G-rich DNA extensions at the ends of macronuclear chromosomes. We have now identified homologous proteins in fission yeast and in humans. These Pot1 (protection of telomeres) proteins each bind the G-rich strand of their own telomeric repeat sequence, consistent with a direct role in protecting chromosome ends. Deletion of the fission yeast pot1+ gene has an immediate effect on chromosome stability, causing rapid loss of telomeric DNA and chromosome circularization. It now appears that the protein that caps the ends of chromosomes is widely dispersed throughout the eukaryotic kingdom.     

Effects of telomerase and telomere length on epidermal stem cell behavior

A key process in organ homeostasis is the mobilization of stem cells out of their niches. We show through analysis of mouse models that telomere length, as well as the catalytic component of telomerase, Tert, are critical determinants in the mobilization of epidermal stem cells. Telomere shortening inhibited mobilization of stem cells out of their niche, impaired hair growth, and resulted in suppression of stem cell proliferative capacity in vitro. In contrast, Tert overexpression in the absence of changes in telomere length promoted stem cell mobilization, hair growth, and stem cell proliferation in vitro. The effects of telomeres and telomerase on stem cell biology anticipate their role in cancer and aging.     

Resolution of sister telomere association is required for progression through mitosis

Cohesins keep sister chromatids associated from the time of their replication in S phase until the onset of anaphase. In vertebrate cells, two distinct pathways dissociate cohesins, one acts on chromosome arms and the other on centromeres. Here, we describe a third pathway that acts on telomeres. Knockdown of tankyrase 1, a telomeric poly(ADP-ribose) polymerase caused mitotic arrest. Chromosomes aligned normally on the metaphase plate but were unable to segregate. Sister chromatids separated at centromeres and arms but remained associated at telomeres, apparently through proteinaceous bridges. Thus, telomeres may require a unique tankyrase 1-dependent mechanism for sister chromatid resolution before anaphase.     

Cryo-electron tomography reveals the cytoskeletal structure of Spiroplasma melliferum

Evidence has accumulated recently that not only eukaryotes but also bacteria can have a cytoskeleton. We used cryo-electron tomography to study the three-dimensional structure of Spiroplasma melliferum cells in a close-to-native state at approximately 4-nanometer resolution. We showed that these cells possess two types of filaments arranged in three parallel ribbons underneath the cell membrane. These two filamentous structures are built of the fibril protein and possibly the actin-like protein MreB. On the basis of our structural data, we could model the motility modes of these cells and explain how helical Mollicutes can propel themselves by means of coordinated length changes of their cytoskeletal ribbons.     

零价铁去除三氯乙烯研究

[目的]研究零价铁（Fe0）对三氯乙烯（TCE）的去除作用。[方法]通过分批试验,利用廉价铁粉对水中TCE进行还原脱氯,研究了Fe0的纯度、粒径、投加量、酸洗预处理及不同的pH值条件对TCE去除的影响。[结果]Fe0的纯度越高,粒径越小,TCE的去除效果越好;在试验范围内,Fe0的投加量越大,TCE的去除效率越高;酸洗预处理可以明显提高Fe0对TCE的去除率;在试验范围内,不同pH值下Fe0去除TCE的效率为：pH值6〉pH值7〉pH值8,说明偏酸性的条件有利于Fe0对TCE的去除。[结论]研究的结果将为地下水TCE污染的场地修复技术提供理论基础。     

Dissection of the mammalian midbody proteome reveals conserved cytokinesis mechanisms

Cytokinesis is the essential process that partitions cellular contents into daughter cells. To identify and characterize cytokinesis proteins rapidly, we used a functional proteomic and comparative genomic strategy. Midbodies were isolated from mammalian cells, proteins were identified by multidimensional protein identification technology (MudPIT), and protein function was assessed in Caenorhabditis elegans. Of 172 homologs disrupted by RNA interference, 58% displayed defects in cleavage furrow formation or completion, or germline cytokinesis. Functional dissection of the midbody demonstrated the importance of lipid rafts and vesicle trafficking pathways in cytokinesis, and the utilization of common membrane cytoskeletal components in diverse morphogenetic events in the cleavage furrow, the germline, and neurons.     

加剂输油问题探讨

加剂低输量管道存在着加剂站出站管道防腐层老化、中间加热站加热炉对流管的低温腐蚀、加剂后冷油头引起输油干线压力升高等问题。提出了相应措施：①加快加剂输油加热站出站管道防腐层大修进度。②加热处理站加热炉更新改造。③尽量避免冷油头出站,防止中间冷油掺入。④加强运行加热炉的巡回检查及停炉期间炉管检测。⑤严格原油改性剂的质量评定工作。     

全自养脱氮工艺研究进展

全自养脱氮工艺比传统的硝化反硝化工艺节省大量的硝化需氧量和反硝化需COD量,是废水生物脱氮技术的研究热点。介绍了CANON工艺、SHARON-ANAMMOX联合工艺和OLAND工艺的研究进展,论述了全自养脱氮颗粒污泥的培养、强化及中间产物N2O产生的影响因素。最小沉降速率和体积交换比是培养全自养脱氮颗粒污泥的关键控制条件;添加微量NO2和N2H4可强化全自养脱氮过程;影响中间产物N2O排放的因素包括NO2-浓度、DO等。     

Finite-frequency tomography reveals a variety of plumes in the mantle

We present tomographic evidence for the existence of deep-mantle thermal convection plumes. P-wave velocity images show at least six well-resolved plumes that extend into the lowermost mantle: Ascension, Azores, Canary, Easter, Samoa, and Tahiti. Other less well-resolved plumes, including Hawaii, may also reach the lowermost mantle. We also see several plumes that are mostly confined to the upper mantle, suggesting that convection may be partially separated into two depth regimes. All of the observed plumes have diameters of several hundred kilometers, indicating that plumes convey a substantial fraction of the internal heat escaping from Earth.     

氮氧化物去除技术中催化剂的研究进展

选择性催化还原法（SCR）是燃煤电厂等工业领域中去除高浓度氮氧化物最有效的技术,而光催化（Photocatalytic）方法则为最具潜力的去除城市空气环境中低浓度氮氧化物的技术。概述了选择性催化还原中各种金属、非金属以及多孔材料的沸石催化剂的发展及不足,介绍了光催化技术催化原理并就催化剂的选择、制备影响因素进行了综述和评价。最后,对SCR催化剂和光催化剂的发展进行了展望。     

市政污泥好氧堆肥过程中PAHs的去除

为探究市政污泥好氧堆肥过程中多环芳烃（PAHs）的去除动态,本研究以沈阳市市政污泥为研究对象,进行3个批次的好氧堆肥现场试验,分析了市政污泥中PAHs的污染特征、污染来源及堆肥过程中PAHs的去除动态。结果表明：不同季节沈阳市市政污泥中∑PAHs含量差异较大,范围为0.82~3.73 mg·kg^-1,夏季污泥成分以高环PAHs（n≥4）为主（质量比为94.0%）,而冬季和春季污泥以低环PAHs（n<4）为主,质量比分别为76.0%和63.0%。采用双比值法对沈阳市污泥中PAHs进行源解析,结果显示污泥中PAHs的主要来源为煤的燃烧源。经过堆肥处理后∑PAHs去除率大小顺序为春季（52.8%） >夏季（49.1%） >冬季（46.7%）。研究表明,好氧堆肥对PAHs有明显的降解效果,有利于实现污泥的无害化和资源化。     

石斛粗多糖脱蛋白方法的研究

[目的]研究石斛多糖中蛋白质的有效去除方法。[方法]以蛋白脱除率和多糖损失率作为检测指标,考察3种不同方法对石斛粗多糖液去除蛋白质的效果。[结果]三氯乙酸法脱蛋白效果最好,且其多糖损失率最低。[结论]该方法简单、易行,适合于石斛粗多糖中蛋白质的去除。     

柿果的脱涩机理与方法

柿(Diospyros kaki)果有甜涩之分,涩柿需经脱涩,方可食用。本文针对不同的脱涩方法,论述了柿果脱涩与其品种、成熟度、温度以及化学物质间的密切关系,为今后更先进的脱涩技术的开发提供了可靠的依据。     

自动增氧型人工湿地对废水中COD的去除效果

针对常规人工湿地中溶解氧不足的问题,采用页岩空心砖构建自动增氧型人工湿地系统,研究构建系统对废水COD的净化效果。结果表明,自动增氧型湿地内的DO比人工强化曝气型湿地高0.1 mg/L左右,COD去除率达到85%以上,比人工曝气型湿地高2%左右。这说明构建的自动增氧系统可提高湿地系统内部供氧能力,提高湿地系统对废水COD的净化效率。