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991.
Endostatin gene therapy enhances the efficacy of paclitaxel to suppress breast cancers and metastases in mice 总被引:5,自引:0,他引:5
Li J Dong X Xu Z Jiang X Jiang H Krissansen GW Sun X 《Journal of biomedical science》2008,15(1):99-109
Chemotherapy combined with antiangiogenic therapy is more effective than chemotherapy alone. The aim of this study was to
investigate whether endostatin, a potent anti-angiogenic agent, could enhance the efficacy of paclitaxel to combat breast
cancer. An expression plasmid encoding mouse endostatin (End-pcDNA3.1) was constructed, which produced intense expression
of endostatin and inhibited angiogenesis in the chorioallantoic membrane assay. 4T1 breast tumors were established in BALB/c
mice by subcutaneous injection of 1 × 105 4T1 cells. The End-pcDNA3.1 plasmid diluted in the transfection reagent FuGENETM was injected into the tumors (around 100 mm2), and paclitaxel was injected i.p. into the mice. Endostatin gene therapy synergized with paclitaxel in suppressing the growth
of 4T1 tumors and their metastasis to the lung and liver. Both endostatin and paclitaxel inhibited tumor angiogenesis and
induced cell apoptosis. Despite the finding that endostatin was superior to paclitaxel at inhibiting tumor angiogenesis, paclitaxel
was nevertheless more effective at inducing tumor apoptosis. The combination of paclitaxel and endostatin was more effective
in suppressing tumor growth, metastases, angiogenesis, and inducing apoptosis than the respective monotherapies. The combinational
therapy with endostatin and paclitaxel warrants future investigation as a therapeutic strategy to combat breast cancer. 相似文献
992.
Relations of mineral-soil C and N to climate and texture: regional differences within the conterminous USA 总被引:4,自引:0,他引:4
Soil is a prominent component of terrestrial C and N budgets. Soil C and N pools are influenced by, and may reciprocally influence,
many environmental factors. Our objective was to determine the quantitative relations of surface mineral-soil organic C, N,
and C/N ratios to climate and soil texture across seven ecological regions that make up the conterminous USA. Up to 608 soil
profiles per region and their corresponding climates were evaluated with regression analysis. The organic C pool (kg C m−2) in the upper 20 cm of mineral soil was positively related to mean annual precipitation, evapotranspiration and clay content
in all regions. It was negatively related to a temperature/precipitation index in all regions and negatively related to mean
annual temperature, except in the northwest temperate forest region. Soil C/N ratios were negatively related to clay or silt
content in all regions. These relations are consistent with concepts of moisture and temperature controls on detrital production,
differential effects of temperature on detrital production and decomposition, and stabilization of organic matter by clay
and silt. Differences in quantitative relations among regions may be related to vegetation-composition effects on soil organic
matter processes, clay mineralogy, and faunal mixing of surface organic horizons with mineral soil. Regional differences also
occurred in the importance of climate vs. soil texture in explaining the variability in soil C. The regional differences indicate
the importance of using region-specific, rather than generalized, equations for projecting long-term soil responses to climate
change and for conducting ecosystem-model calibration or validation. 相似文献
993.
基于金黄色葡萄球菌16S rRNA基因序列,采用序列比对设计了一种茎环结构的寡聚核苷酸探针。探针的环序列即为金黄色葡萄球菌16S rRNA基因序列的其中一个片段,同其他菌种的16S rRNA基因序列误配2个以上的核苷酸,因此能高度专一、灵敏的检测金黄色葡萄球菌16S rRNA。根据分子信标技术和酶联免疫分析的原理,评估一个实验方法,即利用能构象转换的、固定化的茎环结构探针酶联检测靶核酸。由于探针的特异性加强,这个检测系统能有效的排除假阳性即不会出现误配一个核苷酸的情况。采用微量浓度测定分析,最低下限可检测出大约4ng的金葡球菌16SrRNA。这种方法的灵敏度比其他常规检测方法高出了至少一个数量级。 相似文献
994.
The α-glucosidase (AGL) from Aspergillus niger has been applied to produce isomaltooligosaccharides. In the present study, various factors which affect the yield of recombinant AGL, produced by engineered Pichia pastoris, were investigated. The expression level reached 5.5 U ml?1 in bioreactor after optimization of parameters of initial induction cell density, induction temperature and methanol concentration. In addition, it was found that coexpression of protein disulfide isomerase (PDI) inhibited the growth of the engineered P. pastoris strains and had an adverse effect on the production of AGL, while codon optimization of native A. niger α-glucosidase encoding gene (aglu) resulted in a significant enhancement of enzyme production, which reached 10.1 U ml?1. We believe that yield of AGL is increased by codon optimization as a result of enhanced translation efficiency as well as more stable mRNA secondary structure. In contrast, PDI coexpression under the control of alcohol oxidase promoter (PAOX1) seems to be less efficient in helping disulfide bond formation in AGL while probably induce unfolded protein response, which further leads to cell apoptosis and increased protein degradation. 相似文献
995.
Jia XY Guo ZY Wang Y Xu Y Duan SS Feng YM 《Protein science : a publication of the Protein Society》2003,12(11):2412-2419
The single-chain insulin (PIP) can spontaneously fold into native structure through preferred kinetic intermediates. During refolding, pairing of the first disulfide A20-B19 is highly specific, whereas pairing of the second disulfide is likely random because two two-disulfide intermediates have been trapped. To get more details of pairing property of the second disulfide, four model peptides of possible folding intermediates with two disulfides were prepared by protein engineering, and their properties were analyzed. The four model peptides were named [A20-B19, A7-B7]PIP, [A20-B19, A6-B7]PIP, [A20-B19, A6-A11]PIP, and [A20-B19, A7-A11]PIP according to their remaining disulfides. The four model peptides all adopt partially folded structure with moderate conformational differences. In redox buffer, the disulfides of the model peptides are more easily reduced than those of the wild-type PIP. During in vitro refolding, the reduced model peptides share similar relative folding rates but different folding yields: The refolding efficiency of the reduced [A20-B19, A7-A11]PIP is about threefold lower than that of the other three peptides. The present results indicate that the folding intermediates corresponding to the present model peptides all adopt partially folded conformation, and can be formed during PIP refolding, but the chance of forming the intermediate with disulfide [A20-B19, A7-A11] is much lower than that of forming the other three intermediates. 相似文献
996.
M. Lebouvier M. Laparie M. Hullé A. Marais Y. Cozic L. Lalouette P. Vernon T. Candresse Y. Frenot David Renault 《Biological invasions》2011,13(5):1195-1208
The suite of environments and anthropogenic modifications of sub-Antarctic islands provide key opportunities to improve our
understanding of the potential consequences of climate change and biological species invasions on terrestrial ecosystems.
The profound impact of human introduced invasive species on indigenous biota, and the facilitation of establishment as a result
of changing thermal conditions, has been well documented on the French sub-Antarctic Kerguelen Islands (South Indian Ocean).
The present study provides an overview of the vulnerability of sub-Antarctic terrestrial communities with respect to two interacting
factors, namely climate change and alien insects. We present datasets assimilated by our teams on the Kerguelen Islands since
1974, coupled with a review of the literature, to evaluate the mechanism and impact of biological invasions in this region.
First, we consider recent climatic trends of the Antarctic region, and its potential influence on the establishment, distribution
and abundance of alien insects, using as examples one fly and one beetle species. Second, we consider to what extent limited
gene pools may restrict alien species’ colonisations. Finally, we consider the vulnerability of native communities to aliens
using the examples of one beetle, one fly, and five aphid species taking into consideration their additional impact as plant
virus vectors. We conclude that the evidence assimilated from the sub-Antarctic islands can be applied to more complex temperate
continental systems as well as further developing international guidelines to minimise the impact of alien species. 相似文献
997.
Katrijn Van Laere Soraya C. França Hein Vansteenkiste Johan Van Huylenbroeck Kathy Steppe Marie-Christine Van Labeke 《Acta Physiologiae Plantarum》2011,33(4):1149-1156
In this study, we analysed morphological, anatomical and physiological effects of polyploidisation in Spathiphyllum
wallisii in order to evaluate possible interesting advantages of polyploids for ornamental breeding. Stomatal density was negatively
correlated with increased ploidy level. Stomatal size increased in polyploids. Tetraploid Spathiphyllum plants had more ovate and thicker leaves. The inflorescence of tetraploids had a more ovate and thicker spathum, a more cylindrical
spadix and a thicker but shorter flower stalk. Biomass production of the tetraploids was reduced, as expressed by lower total
dry weights, and tetraploids produced fewer shoots and leaves compared with their diploid progenitors. Furthermore, tetraploid
Spathiphyllum plants were more resistant to drought stress compared with diploid plants. After 15 days of drought stress, diploids showed
symptoms of wilting, while the tetraploids showed almost no symptoms. Further, measurements of stomatal resistance, leaf water
potential, relative water content and proline content indicated that the tetraploid genotypes were more resistant to drought
stress compared with the diploids. 相似文献
998.
999.
Purification of photosystem Ⅱ (PSII) core complexes is a time-consuming and low-efficiency process. In order to isolate pure and active PSII core complexes in large amounts, we have developed a fast method to isolate highly active monomeric and dimeric PSII core complexes from spinach leaves by using sucrose gradient ultracentrifugation. By using a vertical rotor the process was completed significantly faster compared with a swing-out rotor. In order to keep the core complexes in high activity, the whole isolation procedure was performed in the presence of glycine betain and pH at 6.3. The isolated pigment-protein complexes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, absorption spectroscopy, 77 K fluorescence spectroscopy and high performance liquid chromatography. Our results show that this method is a better choice for quick and efficient isolation of functionally active PSII core complexes. 相似文献
1000.
Manuel Porcar 《Systems and synthetic biology》2010,4(1):1-6
Synthetic biology is an engineering approach that seeks to design and construct new biological parts, devices and systems,
as well as to re-design existing components. However, rationally designed synthetic circuits may not work as expected due
to the context-dependence of biological parts. Darwinian selection, the main mechanism through which evolution works, is a
major force in creating biodiversity and may be a powerful tool for synthetic biology. This article reviews selection-based
techniques and proposes strict Darwinian selection as an alternative approach for the identification and characterization
of parts. Additionally, a strategy for fine-tuning of relatively complex circuits by coupling them to a master standard circuit
is discussed. 相似文献