Biochemistry,evolution and physiological function of the Rnf complex,a novel ion-motive electron transport complex in prokaryotes

Microbes have a fascinating repertoire of bioenergetic enzymes and a huge variety of electron transport chains to cope with very different environmental conditions, such as different oxygen concentrations, different electron acceptors, pH and salinity. However, all these electron transport chains cover the redox span from NADH + H⁺ as the most negative donor to oxygen/H₂O as the most positive acceptor or increments thereof. The redox range more negative than −320 mV has been largely ignored. Here, we have summarized the recent data that unraveled a novel ion-motive electron transport chain, the Rnf complex, that energetically couples the cellular ferredoxin to the pyridine nucleotide pool. The energetics of the complex and its biochemistry, as well as its evolution and cellular function in different microbes, is discussed.     

Different roles of the human Orc6 protein in the replication initiation process

In eukaryotes, binding of the six-subunit origin recognition complex (ORC) to DNA provides an interactive platform for the sequential assembly of pre-replicative complexes. This process licenses replication origins competent for the subsequent initiation step. Here, we analyze the contribution of human Orc6, the smallest subunit of ORC, to DNA binding and pre-replicative complex formation. We show that Orc6 not only interacts with Orc1–Orc5 but also with the initiation factor Cdc6. Biochemical and imaging experiments reveal that this interaction is required for licensing DNA replication competent. Furthermore, we demonstrate that Orc6 contributes to the interaction of ORC with the chaperone protein HMGA1a (high mobility group protein A1a). Binding of human ORC to replication origins is not specified at the level of DNA sequence and the functional organization of origins is poorly understood. We have identified HMGA1a as one factor that might direct ORC to AT-rich heterochromatic regions. The systematic analysis of the interaction between ORC and HMGA1a revealed that Orc6 interacts with the acidic C-terminus of HMGA1a and also with its AT-hooks. Both domains support autonomous replication if targeted to DNA templates. As such, Orc6 functions at different stages of the replication initiation process. Orc6 can interact with ORC chaperone proteins such as HMGA1a to facilitate chromatin binding of ORC and is also an essential factor for pre-RC formation.     

The histidine triad nucleotide-binding protein 1 supports mu-opioid receptor–glutamate NMDA receptor cross-regulation

A series of pharmacological and physiological studies have demonstrated the functional cross-regulation between MOR and NMDAR. These receptors coexist at postsynaptic sites in midbrain periaqueductal grey (PAG) neurons, an area implicated in the analgesic effects of opioids like morphine. In this study, we found that the MOR-associated histidine triad nucleotide-binding protein 1 (HINT1) is essential for maintaining the connection between the NMDAR and MOR. Morphine-induced analgesic tolerance is prevented and even rescued by inhibiting PKC or by antagonizing NMDAR. However, in the absence of HINT1, the MOR becomes supersensitive to morphine before suffering a profound and lasting desensitization that is refractory to PKC inhibition or NMDAR antagonism. Thus, HINT1 emerges as a key protein that is critical for sustaining NMDAR-mediated regulation of MOR signaling strength. Thus, HINT1 deficiency may contribute to opioid-intractable pain syndromes by causing long-term MOR desensitization via mechanisms independent of NMDAR.     

浅议马克思主义的自由观

自由,是人类永恒追求的真理之一.在人类对自由的历史探索中,不同的思想家对自由的理解各有不同.其中较重要的就是以西方文化为代表的新自由主义.随着新自由主义在经济领域的应用而生成的自由市场至上主义思想的发展,显然,对当今全球金融危机的发生负有不可推卸的责任.所以,此时重申马克思主义自由观,对于我们理解、把握这个时代具有重大意义.     

Horses damp the spring in their step.

The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb.     

浅析和谐社会下高校民主决策中的教授治校

高校作为高级知识分子集聚的地方，是科教兴国、人才强国的策源地和意识形态的重要阵地，在和谐社会的构建过程中，发挥着重要的作用。构建和谐校园，是构建和谐社会在高校的体现和要求，而构建和谐校园的题中意之一就是要提高高校决策的民主化水平，形成科学的决策机制。教授治校，则是高校民主决策体制中重要的组成部分。     

科技成果转化与我国企业发展分析

科技成果转化水平受社会经济制度、社会发展水平、企业科技吸收能力等条件的制约，由于我国企业发展层次不同，科技成果转化的途径也有所差异，大中型企业走内部化道路．小型企业通过技术市场获取科技成果，总的趋势是促进科技成果企业内部化。     

高斯型Runge-Kutta方法研究

提出了一类高斯型Runge—Kutta公式的推导思想，并具体的给出了一个两点三阶高斯型Runge—Kutta公式，证明了高斯型Runge—Kutta公式的精度高于传统的对应的Runge—Kutta公式。     

生态学中的效率问题及其发展

效率作为指示生产、生活中反映速率的指标被广泛应用.生态效率以生态能量学为基础,研究生态系统中的能量流动、传递与转化,计算营养级内部和营养级之间的能流的转化效率.传统的效率与生态效率的表达均具有主观性,并常把来源于不同类型、不同性质的能量进行简单或片面的比较.能值理论则把生态系统或生态经济系统中不同种类、不可比较的能量转化成同一标准的能值（太阳能）来衡量和分析,极大提高了生态效率研究的科学性与准确性.