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排序方式: 共有103条查询结果,搜索用时 15 毫秒
1.
The -galactosidase (EC 3.2.1.32) of Corynebacterium murisepticum (inducible by lactose and galactose) was purified by successive column chromatography on Sephadex G-200, DEAE-Sephadex A-50 and DEAE-cellulose (DE52). The enzyme was found to be a dimer of identical subunits of molecular mass 100,000 daltons. The K
m values of the enzyme for the substrates lactose and o-nitrophenyl--d-galactopyranoside (ONPG) are 16.7 mM and 4.4 mM, respectively, indicating, its low affinity for the substrates. The Ouchterlony immunodiffusion method exhibited immunological homogeneity of the enzyme preparation. The catalytic site of the enzyme does not take part in antigen-antibody reaction. 相似文献
2.
immunocytochemical localization of urokinase-type plasminogen activator in lewis lung carcinoma 总被引:1,自引:0,他引:1 下载免费PDF全文
L Skriver LI Larsson V Kielberg LS Nielsen PB Andresen P Kristensen K Dano 《The Journal of cell biology》1984,99(2):753-758
The invasively growing and metasizing Lewis lung carcinoma consistently contained urokinase-type plasminogen activator (u-PA) enzyme activity. When investigated immunocytochemically with antibodies against u-PA, different parts of individual tumors showed a pronounced heterogeneity in staining intensity. Strong staining was found in areas with invasive growth and degradation of surrounding normal tissue, while other areas were completely devoid of staining. Immunoreactivity occurred both with a perinuclear cytoplasmic localization in tumor cells and associated with apparently extracellular material. SDS PAGE of tumor extracts, under both reducing and nonreducing conditions, followed by immunoblotting, showed only one immunocytochemically stainable band with an electrophoretic mobility corresponding to that of purified proenzyme to u-PA, while no two-chain u-PA was detected. This indicates that the major part of the activator in Lewis lung carcinoma is present as one-chain pro-u-PA. 相似文献
3.
4.
Abstract Post-construction avifauna investigations were undertaken at Project West Wind, Meridian Energy Limited's 62-turbine wind farm on the Wellington south coast. These investigations were required in accordance with the resource consent conditions to quantify the level of avian mortalities occurring at the wind farm, particularly in regard to New Zealand falcon (Falco novaeseelandiae), kākā (Nestor meridionalis) and kererū (Hemiphaga novaeseelandiae). This is the first comprehensive study at a New Zealand operating wind farm. The methods included three field components necessary to calculate annual estimates of mortalities across the wind farm site: routine turbine searches; carcass detection trials; and carcass removal trials. Results from years 1 and 2 of a three-year programme are presented. To date, mortalities have been recorded for 17 taxa at 18 of the 24 study turbines. There have been no recorded mortalities of falcon, kākā or kererū. Australasian harrier (Circus approximans) has been the species for which the most mortalities have been recorded. Overall estimated annual mortality rates for years 1 and 2 were calculated to be approximately six and five birds per turbine respectively. 相似文献
5.
Guofen Gao Lindsay Wieczorek Kristina K. Peachman Victoria R. Polonis Carl R. Alving Mangala Rao Venigalla B. Rao 《The Journal of biological chemistry》2013,288(1):234-246
The HIV-1 envelope spike is a trimer of heterodimers composed of an external glycoprotein gp120 and a transmembrane glycoprotein gp41. gp120 initiates virus entry by binding to host receptors, whereas gp41 mediates fusion between viral and host membranes. Although the basic pathway of HIV-1 entry has been extensively studied, the detailed mechanism is still poorly understood. Design of gp41 recombinants that mimic key intermediates is essential to elucidate the mechanism as well as to develop potent therapeutics and vaccines. Here, using molecular genetics and biochemical approaches, a series of hypotheses was tested to overcome the extreme hydrophobicity of HIV-1 gp41 and design a soluble near full-length gp41 trimer. The two long heptad repeat helices HR1 and HR2 of gp41 ectodomain were mutated to disrupt intramolecular HR1-HR2 interactions but not intermolecular HR1-HR1 interactions. This resulted in reduced aggregation and improved solubility. Attachment of a 27-amino acid foldon at the C terminus and slow refolding channeled gp41 into trimers. The trimers appear to be stabilized in a prehairpin-like structure, as evident from binding of a HR2 peptide to exposed HR1 grooves, lack of binding to hexa-helical bundle-specific NC-1 mAb, and inhibition of virus neutralization by broadly neutralizing antibodies 2F5 and 4E10. Fusion to T4 small outer capsid protein, Soc, allowed display of gp41 trimers on the phage nanoparticle. These approaches for the first time led to the design of a soluble gp41 trimer containing both the fusion peptide and the cytoplasmic domain, providing insights into the mechanism of entry and development of gp41-based HIV-1 vaccines. 相似文献
6.
Dan H. Barouch Kathryn E. Stephenson Erica N. Borducchi Kaitlin Smith Kelly Stanley Anna G. McNally Jinyan Liu Peter Abbink Lori F. Maxfield Michael S. Seaman Anne-Sophie Dugast Galit Alter Melissa Ferguson Wenjun Li Patricia L. Earl Bernard Moss Elena E. Giorgi James J. Szinger Leigh Anne Eller Erik A. Billings Mangala Rao Sodsai Tovanabutra Eric Sanders-Buell Mo Weijtens Maria G. Pau Hanneke Schuitemaker Merlin L. Robb Jerome H. Kim Bette T. Korber Nelson L. Michael 《Cell》2013
7.
The additive genetic effects of traits can be used to predict evolutionary trajectories,
such as responses to selection. Non-additive genetic and maternal environmental effects
can also change evolutionary trajectories and influence phenotypes, but these effects have
received less attention by researchers. We partitioned the phenotypic variance of survival
and fitness-related traits into additive genetic, non-additive genetic and maternal
environmental effects using a full-factorial breeding design within two allopatric
populations of Atlantic salmon (Salmo salar). Maternal environmental effects were
large at early life stages, but decreased during development, with non-additive genetic
effects being most significant at later juvenile stages (alevin and fry). Non-additive
genetic effects were also, on average, larger than additive genetic effects. The
populations, generally, did not differ in the trait values or inferred genetic
architecture of the traits. Any differences between the populations for trait values could
be explained by maternal environmental effects. We discuss whether the similarities in
architectures of these populations is the result of natural selection across a common
juvenile environment. 相似文献
8.
Richards RL Rao M Vancott TC Matyas GR Birx DL Alving CR 《Immunology and cell biology》2004,82(5):531-538
Protective or therapeutic immunity against HIV infection is currently believed to require both antibody and CTL responses against the envelope protein. In the present study, the adjuvant activity of a unique oil-in-water emulsion, in which liposomes containing lipid A (LA) and encapsulated antigen served as the emulsifying agent, was examined in mice using oligomeric gp140 (ogp140) derived from the HIV-1 envelope as the antigen. Emulsions rendered either highly stable or unstable by altering the ratio of liposomes to oil were used to examine the effect of stability of the emulsion on adjuvant activity. Stable and unstable emulsions had similar potencies for inducing both IgG antibodies to ogp140 and antigen-specific T-lymphocyte proliferation. Stable emulsions, but not unstable emulsions, induced antigen-specific CTL responses, possibly because of the depot effect of the stable emulsions. Furthermore, stable emulsions induced lower IgG2a/IgG1 ratios than the unstable emulsions. We conclude that stable liposomal oil-in-water emulsions provide an effective means of obtaining both antibody and CTL responses against an HIV envelope antigen. 相似文献
9.
Narayana PB Fazolini André LS Cruz Miriam BF Werneck Jo?o PB Viola Clarissa M Maya-Monteiro Patrícia T Bozza 《Cell cycle (Georgetown, Tex.)》2015,14(16):2667-2676
Accumulating evidence suggests that obesity and enhanced inflammatory reactions are predisposing conditions for developing colon cancer. Obesity is associated with high levels of circulating leptin. Leptin is an adipocytokine that is secreted by adipose tissue and modulates immune response and inflammation. Lipid droplets (LD) are organelles involved in lipid metabolism and production of inflammatory mediators, and increased numbers of LD were observed in human colon cancer. Leptin induces the formation of LD in macrophages in a PI3K/mTOR pathway-dependent manner. Moreover, the mTOR is a serine/threonine kinase that plays a key role in cellular growth and is frequently altered in tumors. We therefore investigated the role of leptin in the modulation of mTOR pathway and regulation of lipid metabolism and inflammatory phenotype in intestinal epithelial cells (IEC-6 cells). We show that leptin promotes a dose- and time-dependent enhancement of LD formation. The biogenesis of LD was accompanied by enhanced CXCL1/CINC-1, CCL2/MCP-1 and TGF-β production and increased COX-2 expression in these cells. We demonstrated that leptin-induced increased phosphorylation of STAT3 and AKT and a dose and time-dependent mTORC activation with enhanced phosphorilation of the downstream protein P70S6K protein. Pre-treatment with rapamycin significantly inhibited leptin effects in LD formation, COX-2 and TGF-β production in IEC-6 cells. Moreover, leptin was able to stimulate the proliferation of epithelial cells on a mTOR-dependent manner. We conclude that leptin regulates lipid metabolism, cytokine production and proliferation of intestinal cells through a mechanism largely dependent on activation of the mTOR pathway, thus suggesting that leptin-induced mTOR activation may contribute to the obesity-related enhanced susceptibility to colon carcinoma. 相似文献
10.
Ramadurai Gowrishankar Manish Kumar Vinay Menon Sai Mangala Divi M. Saravanan P. Magudapathy B. K. Panigrahi K. G. M. Nair K. Venkataramaniah 《Biological trace element research》2010,133(3):357-363
Traditionally, Tinospora cordifolia (Willd.) Hook. F. & Thomson (Menispermaceae), Ocimum sanctum L. (Lamiaceae), Moringa oleifera Lam. (Moringaceae), and Phyllanthus niruri L. (Euphorbiaceae) are some of the commonly used medicinal plants in India for curing ailments ranging from common cold,
skin diseases, and dental infections to major disorders like diabetes, hypertension, jaundice, rheumatism, etc. To understand
and correlate their medicinal use, trace element studies on the aqueous extract of these medicinal plants have been carried
out using particle-induced X-ray emission technique. A 2-MeV proton beam was used to identify and characterize major and minor
elements namely Cl, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, and Sr in them. Results have revealed that these elements are
present in varying concentrations in the selected plants. Notable results include very high concentrations of Cl, K, and Ca
in all the leaf samples, appreciable levels of Mn in all plants, high Zn content in T. cordifolia, and the aqueous extract of Moringa leaves compared to others and relative higher concentrations of Cr in all the plants. 相似文献