X-ROS signaling: rapid mechano-chemo transduction in heart

We report that in heart cells, physiologic stretch rapidly activates reduced-form nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) to produce reactive oxygen species (ROS) in a process dependent on microtubules (X-ROS signaling). ROS production occurs in the sarcolemmal and t-tubule membranes where NOX2 is located and sensitizes nearby ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR). This triggers a burst of Ca(2+) sparks, the elementary Ca(2+) release events in heart. Although this stretch-dependent "tuning" of RyRs increases Ca(2+) signaling sensitivity in healthy cardiomyocytes, in disease it enables Ca(2+) sparks to trigger arrhythmogenic Ca(2+) waves. In the mouse model of Duchenne muscular dystrophy, hyperactive X-ROS signaling contributes to cardiomyopathy through aberrant Ca(2+) release from the SR. X-ROS signaling thus provides a mechanistic explanation for the mechanotransduction of Ca(2+) release in the heart and offers fresh therapeutic possibilities.     

Astrocytic purinergic signaling coordinates synaptic networks

To investigate the role of astrocytes in regulating synaptic transmission, we generated inducible transgenic mice that express a dominant-negative SNARE domain selectively in astrocytes to block the release of transmitters from these glial cells. By releasing adenosine triphosphate, which accumulates as adenosine, astrocytes tonically suppressed synaptic transmission, thereby enhancing the dynamic range for long-term potentiation and mediated activity-dependent, heterosynaptic depression. These results indicate that astrocytes are intricately linked in the regulation of synaptic strength and plasticity and provide a pathway for synaptic cross-talk.     

MAP激酶在植物信号传递网络中的功能

促分裂素原活化蛋白激酶(mitogen-activated protein kinases,MAP激酶,MAPK)链是真核生物信号传递网络中的重要途径之一.MAPK链由3类蛋白激酶MAP3K-MAP2K-MAPK组成,通过依次磷酸化将上游信号传递至下游应答分子.本文主要阐述MAPK链在植物的逆境反应、抗病反应和激素调控等信号传递网络中的功能.     

Quantitative morphological signatures define local signaling networks regulating cell morphology

Although classical genetic and biochemical approaches have identified hundreds of proteins that function in the dynamic remodeling of cell shape in response to upstream signals, there is currently little systems-level understanding of the organization and composition of signaling networks that regulate cell morphology. We have developed quantitative morphological profiling methods to systematically investigate the role of individual genes in the regulation of cell morphology in a fast, robust, and cost-efficient manner. We analyzed a compendium of quantitative morphological signatures and described the existence of local signaling networks that act to regulate cell protrusion, adhesion, and tension.     

The effect of oxygen on biochemical networks and the evolution of complex life

The evolution of oxygenic photosynthesis and ensuing oxygenation of Earth's atmosphere represent a major transition in the history of life. Although many organisms retreated to anoxic environments, others evolved to use oxygen as a high-potential redox couple while concomitantly mitigating its toxicity. To understand the changes in biochemistry and enzymology that accompanied adaptation to O2, we integrated network analysis with information on enzyme evolution to infer how oxygen availability changed the architecture of metabolic networks. Our analysis revealed the existence of four discrete groups of networks of increasing complexity, with transitions between groups being contingent on the presence of key metabolites, including molecular oxygen, which was required for transition into the largest networks.     

不同药物对罗非鱼耐寒能力及其血液生化指标的影响

自然低温条件下,研究了尼罗罗非鱼在粗盐及粗盐+碳酸氢钠(小苏打)作用下的耐寒能力及罗非鱼血液生化指标的变化.结果表明,粗盐组的罗非鱼相对保护率达90％;同一时间,各试验组罗非鱼血清中丙二醛、总蛋白、谷丙转氨酶、谷草转氨酶、甘油三酯和胆固醇差异均极显著;丙二醛和总蛋白水平及谷丙转氨酶和谷草转氨酶活力随温度的降低而升高,而甘油三酯和胆固醇水平则随温度升高而下降.结果表明,添加粗盐可提高罗非鱼的耐寒能力,罗非鱼血液生化指标随着温度的降低而改变,这与低温胁迫能导致罗非鱼昏迷及死亡有关.     

菌根菌丝网络介导的番茄植株间机械损伤信号的传递

利用丛枝菌根真菌摩西管柄囊霉(Funneliformis mosseae, Fm)在供体与受体番茄根系间建立菌根菌丝网络(common mycorrhizal networks, CMNs),研究机械损伤供体植株叶片诱导产生的防御信号可否通过CMNs传递给受体植株,诱导受体植株产生防御反应.结果表明,机械损伤处理预先接种Fm的供体植株后,与供体有CMNs连接的受体植株叶片中苯丙氨酸解氨酶(PAL)、超氧化物歧化酶(SOD)、过氧化物酶(POD)和多酚氧化酶(PPO)活性以及受体植株叶片和根系苯丙氨酸解氨酶基因(PAL)和β-1,3-葡聚糖基因(PR2)转录水平显著高于无菌根菌丝网络连接、菌根菌丝网络连接被阻断以及有菌根菌丝网络连接但供体植物叶片未机械损伤的对照处理,其叶片中,4种酶最高活性是无CMNs连接对照处理B的162.1%、69.1%、230.6%和54.6%,而叶片和根系中2个基因最高转录水平分别是无CMNs连接对照处理B的3.9、17.3和7.2、9.0倍.可见,机械损伤诱导供体番茄叶片产生的防御信号可以通过CMNs传递到邻近健康受体番茄植株,诱导其产生防御反应.     

Mechanism of interleukin-2 signaling: mediation of different outcomes by a single receptor and transduction pathway

The T cell lymphokine, interleukin-2 (IL-2), plays a pivotal role in an immune response by stimulating antigen-activated B lymphocytes to progress through the cell cycle and to differentiate into antibody-secreting cells. An IL-2 inducible B lymphoma line, in which the growth and differentiation responses are uncoupled, provides a model system for dissecting the signaling mechanisms operating in each response. This system was used to show that both signals are initiated by IL-2 binding to a single, unifunctional receptor complex. Moreover, both signals are transduced by a pathway that does not involve any known second messenger system and that can be blocked by a second T cell lymphokine, interleukin 4. These findings suggest that the pleiotrophic effects of IL-2 are determined by different translations of the signal in the nucleus.     

ABP1参与BY2细胞生长素响应的Ca2+信号转导过程

将Ca2+响应实时荧光报告系统引入雌二醇诱导生长素结合蛋白(ABP1)调控表达的BY2细胞中,获得了 ABP1过表达(ABP1-ox)、抑制表达(ABP1-anti)同时对Ca2+标记的几个BY2细胞株.对这些细胞株进行雌二醇诱导调控其ABP1过表达或抑制表达后,分析ABP1的表达量,并通过在细胞外添加IAA处理,实时...     

Symmetrized characterization of noisy quantum processes

A major goal of developing high-precision control of many-body quantum systems is to realize their potential as quantum computers. A substantial obstacle to this is the extreme fragility of quantum systems to "decoherence" from environmental noise and other control limitations. Although quantum computation is possible if the noise affecting the quantum system satisfies certain conditions, existing methods for noise characterization are intractable for present multibody systems. We introduce a technique based on symmetrization that enables direct experimental measurement of some key properties of the decoherence affecting a quantum system. Our method reduces the number of experiments required from exponential to polynomial in the number of subsystems. The technique is demonstrated for the optimization of control over nuclear spins in the solid state.     

DON暴露对断奶仔猪抗氧化水平、血清生化指标及小肠黏膜形态的影响

旨在研究脱氧雪腐镰刀菌烯醇(DON)暴露对断奶仔猪抗氧化水平、血清生化指标及小肠黏膜形态的影响。选择健康的“杜×长×大”三元杂交断奶仔猪30头,随机分成3组,对照组饲喂基础饲粮,低剂量组和高剂量组分别饲喂1和2 mg·kg^-1的DON饲粮,试验期为60 d。试验结束时,所有仔猪采集血液样本,用于检测抗氧化性能、血清生化指标及肠道通透性。每组选5头仔猪进行剖杀,取小肠组织观察病理变化。结果显示,与对照组相比,DON显著降低了断奶仔猪血清谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性(P<0.05),提高了一氧化氮(NO)和丙二醛(MDA)水平(P<0.05),并引起碱性磷酸酶(ALP)、γ-谷氨酰转移酶(γ-GGT)、肌酐(CREA)、α-淀粉酶(α-AMY)、脂肪酶(LIP)、肌酸激酶(CK)活性显著升高(P<0.05),谷草转氨酶(AST)活性显著降低(P<0.05),血清二胺氧化酶(DAO)及D-乳酸(D-LA)含量随DON剂量的增加而显著升高(P<0.05)。低剂量DON可使小肠黏膜发生部分形态改变,而高剂量DON使小肠组织严重受损。试验结果表明,DON暴露可改变断奶仔猪机体抗氧化反应,引起部分生化指标异常,造成肠道黏膜损伤,增加肠道通透性,对仔猪具有一定的毒性作用。     

慢性热应激对放牧肉牛血液生化指标、抗氧化能力及免疫功能的影响

为研究慢性热应激对放牧肉牛血液生化指标、抗氧化能力及免疫功能的影响,在内蒙古阿鲁科尔沁旗巴彦温都尔草原选取体况相近、体质健康的放牧西门塔尔母牛20头,根据放牧草场环境温湿度的变化,将试验期划分为热应激期和热应激恢复期,并于各试验期最后一天清晨进行血液采样,用ELISA方法测定血清激素、抗氧化指标以及血清免疫球蛋白和白细...     

Allosteric mechanisms of signal transduction

Forty years ago, a simple model of allosteric mechanisms (indirect interactions between distinct sites), used initially to explain feedback-inhibited enzymes, was presented by Monod, Wyman, and Changeux. We review the MWC theory and its applications for the understanding of signal transduction in biology, and also identify remaining issues that deserve theoretical and experimental substantiation.     

Autocorrelation functions of noisy electron micrographs of stained polynucleotide chains

Polyuridylic acid was deposited on carbon films in the presence of the thallous salt of mercury-p-dihydroquinone-O,O-diacetic acid under conditions leading to attachment of one of these molecules to each nucleotide. In electron micrographs of the stained polynucleotide chain, detail was obscured by the noise resulting from the substrate. Optically obtained autocorrelation functions of the distribution of density along the strands revealed peaks suggesting a structural regularity of 8 angstroms; this was interpreted as the internucleotide spacing.     

长期饲喂柑橘提取物对肥育猪血液生化指标、抗氧化能力、免疫功能以及游离氨基酸的影响

旨在研究长期饲喂柑橘提取物对肥育猪血液生化指标、抗氧化能力、免疫功能和游离氨基酸的影响.选取108头56日龄19.73士0.39 kg杜×长×大猪,公母各半,设置3组.空白组为基础饲粮,抗生素组在基础饲粮上添加75 g/t金霉素,柑橘提取物组在基础饲粮上添加柑橘提取物(56～112 d添加250 mL/t,113～19...     

Diversity of G proteins in signal transduction

The heterotrimeric guanine nucleotide-binding proteins (G proteins) act as switches that regulate information processing circuits connecting cell surface receptors to a variety of effectors. The G proteins are present in all eukaryotic cells, and they control metabolic, humoral, neural, and developmental functions. More than a hundred different kinds of receptors and many different effectors have been described. The G proteins that coordinate receptor-effector activity are derived from a large gene family. At present, the family is known to contain at least sixteen different genes that encode the alpha subunit of the heterotrimer, four that encode beta subunits, and multiple genes encoding gamma subunits. Specific transient interactions between these components generate the pathways that modulate cellular responses to complex chemical signals.     

Turnover of inositol phospholipids and signal transduction

Various extracellular informational signals such as those from a group of hormones and some neurotransmitters appear to be passed from the cell surface into the cell interior by two routes, protein kinase C activation and Ca2+ mobilization. Both routes usually become available as the result of an interaction of a single ligand and a receptor and act synergistically to evoke subsequent cellular responses such as release reactions. The signal-dependent breakdown of inositol phospholipids, particularly phosphatidylinositol bisphosphate, now appears to be a key event for initiating these processes.