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991.
Li C Wong P Pan T Xiao F Yin S Chang B Kang SC Ironside J Sy MS 《The Biochemical journal》2007,406(2):333-341
The normal PrP(C) (cellular prion protein) contains sLe(X) [sialyl-Le(X) (Lewis X)] and Le(X). sLe(X) is a ligand of selectins. To examine whether PrP(C) is a ligand of selectins, we generated three human PrP(C)-Ig fusion proteins: one with Le(X), one with sLe(X), and the other with neither Le(X) nor sLe(X). Only Le(X)-PrP(C)-Ig binds E-, L- and P-selectins. Binding is Ca(2+)-dependent and occurs with nanomolar affinity. Removal of sialic acid on sLe(X)-PrP(C)-Ig enables the fusion protein to bind all selectins. These findings were confirmed with brain-derived PrP(C). The selectins precipitated PrP(C) in human brain in a Ca(2+)-dependent manner. Treatment of brain homogenates with neuraminidase increased the amounts of PrP(C) precipitated. Therefore the presence of sialic acid prevents the binding of PrP(C) in human brain to selectins. Hence, human brain PrP(C) interacts with selectins in a manner that is distinct from interactions in peripheral tissues. Alternations in these interactions may have pathological consequences. 相似文献
992.
Bladder cancer-associated protein gene (BLCAP) is a novel candidate tumor suppressor gene identified from the human bladder
carcinoma. Our previous studies have shown that BLCAP overexpression could inhibit cell growth by inducing apoptosis in HeLa
cells [Zuo Z, Zhao M, Liu J, Gao G, Wu X: Tumor Biol 27: 221–226, 2006]. Such evidence suggests the alterations in BLCAP may
play an important role in tumorigenesis. To further study the biological function of the BLCAP gene, we constructed a recombinant
retroviral vector encoding BLCAP cDNA. Overexpressed BLCAP, via stable infection of exogenous BLCAP, resulted in growth inhibition
of the human tongue cancer cell line Tca8113 in vitro, accompanied by S phase cell cycle arrest and apoptosis. The growth inhibition was correlated with up-regulation of p21WAF1/CIP1 expression and down-regulation of Bcl-XL and Bcl-2 expressions. However, p53 expression and NF-κB activity remained unchanged
post infection. Furthermore, no changes in p53 phosphorylation at Ser46 and nuclear localization, which are critical to p53
function, were observed in BLCAP-overexpressed cells. Taken together, BLCAP may play a role not only in regulating cell proliferation
but also in coordinating apoptosis and cell cycle via a novel way independent of p53 and NF-κB.
Jun Yao and Li Duan contributed equally to this work. 相似文献
993.
Wolk CP Fan Q Zhou R Huang G Lechno-Yossef S Kuritz T Wojciuch E 《Archives of microbiology》2007,188(6):551-563
The clones generated in a sequencing project represent a resource for subsequent analysis of the organism whose genome has
been sequenced. We describe an interrelated group of cloning vectors that either integrate into the genome or replicate, and
that enhance the utility, for developmental and other studies, of the clones used to determine the genomic sequence of the
cyanobacterium, Anabaena sp. strain PCC 7120. One integrating vector is a mobilizable BAC vector that was used both to generate bridging clones and
to complement transposon mutations. Upon addition of a cassette that permits mobilization and selection, pUC-based sequencing
clones can also integrate into the genome and thereupon complement transposon mutations. The replicating vectors are based
on cyanobacterial plasmid pDU1, whose sequence we report, and on broad-host-range plasmid RSF1010. The RSF1010- and pDU1-based
vectors provide the opportunity to express different genes from either cell-type-specific or -generalist promoters, simultaneously
from different plasmids in the same cyanobacterial cells. We show that pDU1 ORF4 and its upstream region play an essential
role in the replication and copy number of pDU1, and that ORFs alr2887 and alr3546 (hetF
A
) of Anabaena sp. are required specifically for fixation of dinitrogen under oxic conditions. 相似文献
994.
An inducible system for expression and validation of the specificity of short hairpin RNA in mammalian cells 总被引:1,自引:0,他引:1
RNA interference (RNAi) by means of short hairpin RNA (shRNA) has developed into a powerful tool for loss-of-function analysis in mammalian cells. The principal problem in RNAi experiments is off-target effects, and the most vigorous demonstration of the specificity of shRNA is the rescue of the RNAi effects with a shRNA-resistant target gene. This presents its own problems, including the unpredictable relative expression of shRNA and rescue cDNA in individual cells, and the difficulty in generating stable cell lines. In this report, we evaluated the plausibility of combining the expression of shRNA and rescue cDNA in the same vector. In addition to facilitate the validation of shRNA specificity, this system also considerably simplifies the generation of shRNA-expressing cell lines. Since the compensatory cDNA is under the control of an inducible promoter, stable shRNA-expressing cells can be generated before the knockdown phenotypes are studied by conditionally turning off the rescue protein. Conversely, the rescue protein can be activated after the endogenous protein is completely repressed. This approach is particularly suitable when prolonged expression of either the shRNA or the compensatory cDNA is detrimental to cell growth. This system allows a convenient one-step validation of shRNA and generation of stable shRNA-expressing cells. 相似文献
995.
996.
Jian Tian Ningfeng Wu Jiang Li Yajie Liu Jun Guo Bin Yao Yunliu Fan 《Applied microbiology》2007,73(7):2364-2368
Leptospirillum ferriphilum strain UBK03 isolated from a mine in Jiangxi, China, is resistant to Ni2+ (30 to 40 mM). A four-gene nickel resistance cluster was identified and, when transformed into Escherichia coli, enabled growth in 6 mM nickel. Mutation experiments revealed that the genes ncrA, ncrB, and ncrC could confer nickel resistance in Escherichia coli, whereas the gene ncrY could have a negative effect on nickel resistance. 相似文献
997.
Removal of agricultural non-point source pollutants by ditch wetlands: implications for lake eutrophication control 总被引:6,自引:0,他引:6
Ditches grown with nature reed (Phragmites communis Trin) and wild rice (Zizania latifolia Turcz) were selected to study the removal capacity of agricultural non-point source pollutants so as to find a way to alleviate
eutrophication in Lake Taihu. Ditches sediment from depths below 40 cm can accumulate organic matter and total nitrogen (TN).
TN is correlated positively to organic matter in reed populated sediment and wild rice populated sediment. This suggests that
the main composition of TN is organic nitrogen derived from plant decomposition. A significant negative relationship between
TN and pH was found in reed and wild rice sediments. Seasonal harvest of helophyte vegetation is an effective method to remove
N and P from wetlands. Organic matter and TN concentrations in water and sediments (0–20 cm) in areas where reeds were removed
are lower than non-harvested areas (control). Reeds and wild rice have high uptake ability of nitrogen (N) and phosphorus
(P). However, the low economic value of these plants will not stimulate voluntary harvest of farmers. Zizania caduciflora Turez Hand-mazt is a kind of vegetable widely cultivated in ditches around the lake. It can also absorb N and P effectively.
Thus, large scale cultivation of Z. caduciflora to replace nature plants may improve water quality. 相似文献
998.
Yu Xie Hao-Han Wu Yong Cui Long Pan Rong Fan Yang-Chao Tian Liu-Si Sheng 《Inorganica chimica acta》2007,360(5):1669-1677
Three homochiral metal-organic coordination networks [Co2(l-Trp)2(Py)6] · Py · (ClO4)2 (1), [Ni(l-Trp)(Py)3] · H2O · ClO4 (2) and [Co2(l-Trp)(INT)2(H2O)2(ClO4)] (3), all containing natural amino acid l-HTrp (l-typtophan), were hydrothermally synthesized and structurally characterized. The compounds 1 and 2 crystallize in the orthorhombic space group C2221, with a = 10.731(2) Å, b = 19.709(4) Å, c = 27.365(6) Å and Z = 4 for 1 and a = 10.710(10) Å, b = 20.088(18) Å, c = 27.63(3) Å and Z = 8 for 2, respectively. The compound 3 has the monoclinic space group P21, with a = 8.1934(14) Å, b = 13.209(2) Å, c = 12.464(2) Å, β = 104.107(3)° and Z = 2. Both 1 and 2 consist of 1D helical chains. Compound 3 is composed of 2D networks, which further assemble into a 3D supramolecular structure via weak interlayer interactions. The optically pure amino acid l-HTrp plays an important role leading to homochiral structures reported here. 相似文献
999.
Predicted glycosyl transferase genes located outside the HEP island are required for formation of heterocyst envelope polysaccharide in Anabaena sp. strain PCC 7120
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During maturation, heterocysts form an envelope layer of polysaccharide, called heterocyst envelope polysaccharide (HEP), whose synthesis depends on a cluster of genes, the HEP island, and on an additional, distant gene, hepB, or a gene immediately downstream from hepB. We show that HEP formation depends upon the predicted glycosyl transferase genes all4160 at a third locus and alr3699, which is adjacent to hepB and is cotranscribed with it. Mutations in the histidine kinase genes hepN and hepK appear to silence the promoter of hepB and incompletely down-regulate all4160. 相似文献
1000.
云南省小黑山自然保护区兰科植物多样性及保护评价 总被引:7,自引:0,他引:7
云南省小黑山自然保护区孕育了丰富的兰科植物。据调查,保护区有兰科植物43属、134种,约占云南省135属、780种的31.9%和17.2%,是保护区种子植物种类最多的科。兰科植物在保护区的各个生态类型中均有出现。保护区134种兰科植物以附生兰占优势,占67.16%(90种);其次,地生兰占31.34%(42种),腐生兰为1.50%(2种)。保护区兰科植物起源于新、旧世界的热带和温带,热带属占70.0%(28),温带属占27.5%(11)。鉴于兰科植物重要的保护价值,应加强保护区兰科植物的保护。首先应加强保护区的建设和管理,还应加强社区经济发展,加强科学研究,实施社区共管以及加大保护宣传力度。 相似文献