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991.
钠钙交换是小鼠心脏发育中最早有功能性表达的通道基因。它的功能主要是通过泵出1个钙,泵入3个钠位置细胞内的钙稳态,此外可能参与兴奋收缩偶联。但是,至今钠钙交换在心脏发育过程中的功能性表达及其在细胞早期兴奋形成中的作用还不是很清楚。采用胚胎干细胞分化的心肌细胞为研究对象,发现在发育极早期,电压钳制在35mV的条件下,10mmol/L咖啡因诱导的内向电流的80%能被灌流液中Na^+被等浓度的Li^+取代(n=8)。此为钠钙交换电流。所有钳制的细胞单细胞RT-PCR都检测到了NCX1亚型的mRNA表达。进一步研究了钠钙交换的功能,发现等浓度Li^+取代灌流液中Na^+及应用高浓度Ni^2+阻断了膜电位震荡及与震荡相间的动作电位(早期膜兴奋形式)。因此认为钠钙交换(NCX1亚型)在心脏发育极早期的心肌细胞中已有大量功能性表达,它对于早期自主性兴奋活动的发生起着关键性的作用。 相似文献
992.
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994.
急性低压低氧对大鼠空间学习记忆的影响及与海马内孤啡肽的关系 总被引:4,自引:0,他引:4
目的:研究暴露在不同海拔高度的急性低压低氧环境中,大鼠空间学习记忆能力的变化及与海马内孤啡肽的关系.方法:采用低压舱模拟4 500 m(中度)和7 500 m(重度)两种海拨高度,Morris水迷宫训练方法和反转录多聚酶链式反应(RT-PCR)技术.结果:①海马内孤啡肽mRNA表达在急性重度低压低氧(8 h/d,连续6 d)后明显增加,然而在Morris 水迷宫训练(6 counts/d,连续6 d,定位航行潜伏期逐渐缩短)后则显著降低.②急性低压低氧后,定位航行潜伏期明显延长,而海马内孤啡肽mRNA表达较学习记忆训练组明显升高.结论:海马内孤啡肽参与急性低压低氧降低大鼠空间学习记忆的机制. 相似文献
995.
Three antibiotics were evaluated for their effects on the elimination of Agrobacterium tumefaciens during the genetic transformation of loblolly pine ( Pinus taeda L.) using mature zygotic embryos as targets. Agrobacterium tumefaciens strains, EHA105, GV3101, and LBA 4404, all harbouring the plasmid pCAMBIA1301, which carries the selectable marker gene, hygromycin phosphotransferase ( hpt) controlled by the cauliflower mosaic virus 35S promoter and terminator, and the uidA reporter gene (GUS) driven by the cauliflower mosaic virus 35S promoter and the terminator of nopaline synthase gene, were used in this study. Exposure to 350 mg l-1 carbenicillin, claforan, and timentin respectively for up to 6 weeks did not eliminate the Agrobacterium, while antibiotics at 500 mg l-1 eradicated them from the co-cultivated zygotic embryos. All three antibiotics increased callus growth and shoot regeneration at 350 and 500 mg l-1 each, but reduced callus growth and shoot regeneration at 650 mg l-1 when compared with controls. Putative transgenic calli were selected for continued proliferation and differentiation on 4.5 mg l-1 hygromycin-containing medium. Transformed calli and transgenic plants produced on a selection medium containing 4.5 mg l-1 hygromycin were confirmed by GUS histochemical assays, by polymerase chain reaction (PCR), and by Southern blot analysis. These results are useful for future studies on optimizing genetic transformation procedures in loblolly pine. 相似文献
996.
Luo Z Palasis M Yamakawa M Liu LX Vincent KA Trudell L Akita GA Koch WJ Cheng SH Gregory RJ Jiang C 《The journal of gene medicine》2004,6(10):1061-1068
BACKGROUND: Previous studies have shown that incubation of balloon-injured rat carotid arteries with adenoviral vectors encoding the carboxyl terminus of the beta-adrenergic receptor kinase (Ad2/betaARKct) for 30 min reduces neointima formation. However, it is unclear whether this beneficial effect of betaARKct could be achieved using a catheter-based vector delivery system and whether the observed inhibition of neointima formation translated into a reduction of vessel stenosis. METHODS: In this study, Ad2/betaARKct was infused into the balloon-injured site of rabbit iliac arteries using a porous infusion catheter over 2 min. Twenty-eight days after gene transfer, angiographic and histological assessments were performed. RESULTS: Angiographic and histological assessments indicate significant (p < 0.05) inhibition of iliac artery neointima formation and lumen stenosis by Ad2/betaARKct. Our studies demonstrate that an inhibitory effect of Ad2/betaARKct on neointima formation is achievable using a catheter-based vector delivery system and that the inhibition of neointima formation translates into a gain in the vessel minimal luminal diameter. The extent of inhibition (35%) was comparable to that observed with adenoviral-mediated expression of thymidine kinase plus ganciclovir treatment, a cytotoxic gene therapy approach for restenosis. CONCLUSIONS: These results suggest that adenoviral-mediated gene transfer of betaARKct is a clinically viable cytostatic gene therapy strategy for the treatment of restenosis. 相似文献
997.
Proteomic profiling of bone marrow mesenchymal stem cells upon transforming growth factor beta1 stimulation 总被引:6,自引:0,他引:6
Wang D Park JS Chu JS Krakowski A Luo K Chen DJ Li S 《The Journal of biological chemistry》2004,279(42):43725-43734
Bone marrow mesenchymal stem cells (MSCs) can differentiate into different types of cells and have tremendous potential for cell therapy and tissue engineering. Transforming growth factor beta1 (TGF-beta) plays an important role in cell differentiation and vascular remodeling. We showed that TGF-beta induced cell morphology change and an increase in actin fibers in MSCs. To determine the global effects of TGF-beta on MSCs, we employed a proteomic strategy to analyze the effect of TGF-beta on the human MSC proteome. By using two-dimensional gel electrophoresis and electrospray ionization coupled to quadrupole/time-of-flight tandem mass spectrometers, we have generated a proteome reference map of MSCs, and we identified approximately 30 proteins with an increase or decrease in expression or phosphorylation in response to TGF-beta. The proteins regulated by TGF-beta included cytoskeletal proteins, matrix synthesis proteins, membrane proteins, metabolic enzymes, etc. TGF-beta increased the expression of smooth muscle alpha-actin and decreased the expression of gelsolin. Overexpression of gelsolin inhibited TGF-beta-induced assembly of smooth muscle alpha-actin; on the other hand, knocking down gelsolin expression enhanced the assembly of alpha-actin and actin filaments without significantly affecting alpha-actin expression. These results suggest that TGF-beta coordinates the increase of alpha-actin and the decrease of gelsolin to promote MSC differentiation. This study demonstrates that proteomic tools are valuable in studying stem cell differentiation and elucidating the underlying molecular mechanisms. 相似文献
998.
地形因子对森林景观格局多尺度效应分析 总被引:4,自引:3,他引:4
以TM影像和野外调查为数据源,3S技术为研究手段,分析了泰山的森林景观结构动态变化以及景观格局沿高程的分异。选择相对高差较大的区域设计了8个地形方位,采用3种由连续样方组成的辐射状样带,在遥感影像上进行信息采集,研究地形对森林景观格局的多尺度效应,分析了不同地形因子对森林景观分异的影响。结果表明,在景观尺度上,地形方位、海拔、山地类型是影响森林景观镶嵌格局的控制因素,坡向、坡度是重要因素,坡形、坡位是不明显因素。以TM影像为信息源,从森林景观分异和梯度分析上,首先要考虑海拔坡向指数、坡形坡位指数和海拔,并立足于地形方位。地形主要因子间存在着稳定的显著正相关,为森林分异多尺度格局提供了较强的综合解释能力。 相似文献
999.
Tang Yunming Cen Liang Chu Bo Li Changchun Xu Min Luo Ying Lu Cheng 《Frontiers of Biology in China》2006,1(3):246-253
Alkaline phosphatase (AKP), from the succus entericus of silkworm, was purified using 10%–50% ammonium sulfate fractions,
ion exchange chromatography of DEAE-Sepharose, and size exclusion chromatography of Sephacryl S-200. The purification fold
was 464 times and specified activity was 3 936 U/mg. Optimum pH value of the phosphatase was 10.5, and was stable between
pH 7.5 and 11. The optimum temperature of the phosphatase was 40°C and it was unstable over 50°C. K
m value of the phosphatase was 1.25 mmol/L. In a given condition, the phosphatase was selectively modified by PCMB, NBS, PMSF,
TNBS, SUAN, DTT, BrAc, and IAc, the results indicate that PMSF, SUA, BrAc, IAc, and TNBS could obviously inhibit the activity
of the phosphatase, and the degree of inhibition depended on the concentration of these reagents. There was little effect
on the activity of phosphatase after treatment by PMSF, DTT, and NBT. We primarily conclude that mercapto and imidazole are
essential for AKP from silkworm. Also, Lys residue and disulfide bands are necessary to protect the catalysis of the AKP.
__________
Translated from Journal of Southwest Normal University (Natural Science), 2005, 30(5): 925–934 [译自: 西南师范大学学报 (自然科学版), 2005, 30(5): 925–934] 相似文献
1000.
An electromagnetic (EM) heating system is developed to achieve the rapid and uniform warming of cryopreserved biomaterials. Using the heating system, a rectangular resonant cavity is excited in TE101 mode at frequencies near 434 MHz. In experiments, a spherical phantom of biomaterial with a diameter of 36 mm is placed at the center of the cavity. The phantom is first cooled down to about -80 degrees C within the cavity and then thawed by EM absorption. Results show that EM warming can produce much higher warming rate than conventional water-bath warming method. The spatial temperature distribution in the phantom during EM warming is also more uniform than that during the water-bath warming. 相似文献