Characterization of tBid-induced cytochrome c release from mitochondria and liposomes

tBid, the cleaved form of Bid, can induce cytochrome c (Cyt. c) release from rat heart mitochondria more efficiently and reproducibly than that from liver or brain mitochondria. Unlike Bax, such release was not prevented by cyclosphorin A, an inhibitor of the opening of permeability transition pore. Carbonyl-cyanide m-chlorophenyl-hydrazone or oligomycin also have no obvious effect on the release of Cyt. c. In contrast to ceramide, tBid-mediated Cyt. c release from mitochondria is independent of the redox state of Cyt. c. Furthermore, Bid or tBid can directly trigger the efflux of encapsulated Cyt. c or trypsin within liposomes without involvement of other protein factors.     

基因科学的革命--基因芯片技术

基因芯片技术是一种建立在杂交测序基本理论上的全新技术,它利用固定在芯片上的几万至几十万条探针与样品进行杂交,在一步实验中获取大量的信息。它的出现,使基因序列测定、基因功能测定等工作的程序得到了极大的简化,使许多原来根本不可能实现的检测成为可能。基因芯片技术使用了包括光控固相化学合成、激光共聚焦等在内的多项先进技术,实验实现了全部自动化,操作极为简便,可以节约大量的时间和实验成本。该项技术,已经在基     

A single site (Ser16) phosphorylation in phospholamban is sufficient in mediating its maximal cardiac responses to beta -agonists

Phospholamban (PLB) can be phosphorylated at Ser(16) by cyclic AMP-dependent protein kinase and at Thr(17) by Ca(2+)-calmodulin-dependent protein kinase during beta-agonist stimulation. A previous study indicated that mutation of S16A in PLB resulted in lack of Thr(17) phosphorylation and attenuation of the beta-agonist stimulatory effects in perfused mouse hearts. To further delineate the functional interplay between dual-site PLB phosphorylation, we generated transgenic mice expressing the T17A mutant PLB in the cardiac compartment of the null background. Lines expressing similar levels of T17A mutant, S16A mutant, or wild-type PLB in the null background were characterized in parallel. Cardiac myocyte basal mechanics and Ca(2+) kinetics were similar among the three groups. Isoproterenol stimulation was associated with phosphorylation of both Ser(16) and Thr(17) in wild-type PLB and Ser(16) phosphorylation in T17A mutant PLB, whereas there was no detectable phosphorylation of S16A mutant PLB. Phosphorylation of Ser(16) alone in T17A mutant PLB resulted in responses of the mechanical and Ca(2+) kinetic parameters to isoproterenol similar to those in wild-type myocytes, which exhibited dual-site PLB phosphorylation. However, those parameters were significantly attenuated in the S16A mutant myocytes. Thus, Ser(16) in PLB can be phosphorylated independently of Thr(17) in vivo, and phosphorylation of Ser(16) is sufficient for mediating the maximal cardiac responses to beta-adrenergic stimulation.     

蚯蚓基因组学的研究进展: 基于全基因组及线粒体基因组

蚯蚓被喻为土壤中的“生态系统工程师”, 具有高度的多样性且在全世界都有分布, 被用作土壤健康的指示生物。蚯蚓具有极强的环境适应能力, 在不断适应的过程中促进了自身基因组的进化。本文对近年来蚯蚓全基因组以及线粒体基因组的研究进展进行了综述。蚯蚓全基因组的测序、拼装和分析为研究蚯蚓生态学、污染物对蚯蚓致毒的分子机制、免疫防御的分子机制、蚯蚓再生的分子机制等奠定基础。而线粒体基因组多应用于蚯蚓分子系统发育方面的研究, 目前已有多种蚯蚓通过线粒体基因组测序完成了物种的鉴定。本文建议今后重点开展以下几方面的研究: (1)针对现有的4种蚯蚓全基因组测序结果, 进一步进行比较基因组学、进化基因组学和功能基因组学的研究。(2)完善不同种蚯蚓的基因文库和表达序列标签。(3)建立线粒体基因组、全基因组与蚯蚓物种多样性的关联分析。     

一种花生快速遗传转化方法的建立与应用

遗传转化是植物基因工程的重要手段。快速、高效地将目的基因导入植物细胞, 并缩短获得转基因后代的时间是遗传转化的关键。花生(Arachis hypogaea)是我国重要的油料及经济作物。目前花生的遗传转化体系尚未完善, 制约着花生的基因功能解析和分子育种进程。该文建立了一套快速、稳定的花生遗传转化体系。通过将农杆菌注射于花生第2茎节的切面获得转化植株, 再将阳性植株进行移栽和回土, 采摘注射点以上的荚果进行后续鉴定与分析。结果表明, 利用该方法可获得40%以上的T₀代嵌合体植株, 约5个月可收获T₀代花生种子, 其中约有9%的T₁代花生植株为非嵌合体的杂合体。针对部分转基因植株结实少的问题, 进一步提出了将快速转化体系与传统组培方法相结合的优化方案。构建的快速转化方法对大蒜(Allium sativum)、马铃薯(Solanum tuberosum)和香雪兰(Freesia refracta)的遗传转化具有潜在应用价值, 对其它植物的遗传转化也有重要参考价值。     

Glycogen synthase kinase-3alpha reduces cardiac growth and pressure overload-induced cardiac hypertrophy by inhibition of extracellular signal-regulated kinases

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase having multiple functions and consisting of two isoforms, GSK-3alpha and GSK-3beta. Pressure overload increases expression of GSK-3alpha but not GSK-3beta. Despite our wealth of knowledge about GSK-3beta, the function of GSK-3alpha in the heart is not well understood. To address this issue, we made cardiac-specific GSK-3alpha transgenic mice (Tg). Left ventricular weight and cardiac myocyte size were significantly smaller in Tg than in non-Tg (NTg) mice, indicating that GSK-3alpha inhibits cardiac growth. After 4 weeks of aortic banding (transverse aortic constriction (TAC)), increases in left ventricular weight and myocyte size were significantly smaller in Tg than in NTg, indicating that GSK-3alpha inhibits cardiac hypertrophy. More severe cardiac dysfunction developed in Tg after TAC. Increases in fibrosis and apoptosis were greater in Tg than in NTg after TAC. Among signaling molecules screened, ERK phosphorylation was decreased in Tg. Adenovirus-mediated overexpression of GSK-3alpha, but not GSK-3beta, inhibited ERK in cultured cardiac myocytes. Knockdown of GSK-3alpha increased ERK phosphorylation, an effect that was inhibited by PD98059, rottlerin, and protein kinase Cepsilon (PKCepsilon) inhibitor peptide, suggesting that GSK-3alpha inhibits ERK through PKC-MEK-dependent mechanisms. Knockdown of GSK-3alpha increased protein content and reduced apoptosis, effects that were abolished by PD98059, indicating that inhibition of ERK plays a major role in the modulation of cardiac growth and apoptosis by GSK-3alpha. In conclusion, up-regulation of GSK-3alpha inhibits cardiac growth and pressure overload-induced cardiac hypertrophy but increases fibrosis and apoptosis in the heart. The anti-hypertrophic and pro-apoptotic effect of GSK-3alpha is mediated through inhibition of ERK.     

GPI-anchored CEA family glycoproteins CEA and CEACAM6 mediate their biological effects through enhanced integrin alpha5beta1-fibronectin interaction

Carcinoembryonic antigen (CEA) and CEA family member CEACAM6 are glycophosphatidyl inositol (GPI)-anchored, intercellular adhesion molecules that are up-regulated in a wide variety of human cancers, including colon, breast, and lung. When over-expressed in a number of cellular systems, these molecules are capable of inhibiting cellular differentiation and anoikis, as well as disrupting cell polarization and tissue architecture, thus increasing tumorigenicity. The present study shows that perturbation of the major fibronectin receptor, integrin alpha5beta1, underlies some of these biological effects. Using confocal microscopy and specific antibodies, CEA and CEACAM6 were demonstrated to co-cluster with integrin alpha5beta1 on the cell surface. The presence of CEA and CEACAM6 was shown to lead to an increase in the binding of the integrin alpha5beta1 receptor to its ligand fibronectin, without changing its cell surface levels, resulting in increased adhesion of CEA/CEACAM6-expressing cells to fibronectin. More tenacious binding of free fibronectin to cells led to enhanced fibronectin matrix assembly and the formation of a polymerized fibronectin "cocoon" around the cells. Disruption of this process with specific monoclonal antibodies against either fibronectin or integrin alpha5beta1 led to the restoration of cellular differentiation and anoikis in CEA/CEACAM6 producing cells.     

产微生物絮凝剂的菌株筛选、鉴定及发酵条件优化

微生物絮凝剂是一类新型的水处理制剂,因其具有高效、无毒、易降解等特点,已成为水处理剂开发的研究热点。为了扩大微生物絮凝剂的种类,本研究从活性污泥和土壤样品中筛选絮凝剂产生菌,最终获得一株具有絮凝活性的菌株,通过16S rDNA鉴定,该菌株为蒙氏假单胞菌(Pseudomonas monteilii),因此命名为P. monteilii YR-1。利用单因素实验和正交试验对该菌株的发酵条件进行了优化,其最佳碳、氮源分别为25 g/L葡萄糖和2 g/L复合氮源(酵母浸粉:尿素:硫酸铵=5:5:2),培养基初始pH值为10,培养温度为28℃,发酵时间为72 h。在最佳培养条件下,其发酵液的絮凝率从37.68%提高到63.52%。这是关于蒙氏假单胞菌产絮凝剂的首次报道。     

A Phytophthora Effector Suppresses Trans-Kingdom RNAi to Promote Disease Susceptibility

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