Genetic dissection of the circuit for hand dexterity in primates

It is generally accepted that the direct connection from the motor cortex to spinal motor neurons is responsible for dexterous hand movements in primates. However, the role of the 'phylogenetically older' indirect pathways from the motor cortex to motor neurons, mediated by spinal interneurons, remains elusive. Here we used a novel double-infection technique to interrupt the transmission through the propriospinal neurons (PNs), which act as a relay of the indirect pathway in macaque monkeys (Macaca fuscata and Macaca mulatta). The PNs were double infected by injection of a highly efficient retrograde gene-transfer vector into their target area and subsequent injection of adeno-associated viral vector at the location of cell somata. This method enabled reversible expression of green fluorescent protein (GFP)-tagged tetanus neurotoxin, thereby permitting the selective and temporal blockade of the motor cortex–PN–motor neuron pathway. This treatment impaired reach and grasp movements, revealing a critical role for the PN-mediated pathway in the control of hand dexterity. Anti-GFP immunohistochemistry visualized the cell bodies and axonal trajectories of the blocked PNs, which confirmed their anatomical connection to motor neurons. This pathway-selective and reversible technique for blocking neural transmission does not depend on cell-specific promoters or transgenic techniques, and is a new and powerful tool for functional dissection in system-level neuroscience studies.     

Cleavage of des-Arg9-bradykinin by angiotensin I-converting enzyme from pig kidney cortex

Summary Fast and very slow hydrolyses of des-Arg⁹-bradykinin and angiotensin II by angiotensin I-converting enzyme were detected by high performance liquid chromatography. The Michaelis constants of the enzyme, K_m values, for des-Arg⁹-bradykinin and bradykinin were found to be 0.24 mM and 4.4 M, and the maximum velocities, V_max values (mol·min^–1·mg protein^–1) for these compounds to be 3.24 and 0.34, respectively. The enzyme also hydrolyzed Z-Gly-Pro-Gly-Gly-Pro-Ala to a tripeptide that was identified as dansyl-Gly-Pro-Ala by TLC on polyamide. These observations show that the enzyme hydrolyzes the peptides at the bond before the prolyl residue in the penultimate position.Acknowledgments. We thank Dr Kinzo Nagasawa of Kitasato University for encouragement in this work and Dr Ervin G. Erdös, University of Texas, Health Science Center, Dallas, for valuable discussion and suggestions.Abbreviations used: Z, carbobenzoxy; Bz, benzoyl; ACE, angiotensin I-converting enzyme; BK, bradykinin; HPLC, high performance liquid chromatography.     

内流式锥阀液动力的理论探讨

文中指出一般内流式锥阀流体力分析中选用一个控制体积的不足，选取了阀腔上、下流两个控制体积，运用两次动量变化的概念，得到新的内流式锥阀液动力理论方程。为了实用方便，文中给出了一种近似计算公式。     

添加物对黑小麦草青贮的细胞壁成分和体外干物质消化率的影响及其与小麦、黑麦草青贮的比较

用乳熟期的黑小麦草、小麦及黑麦草调制了青贮，每种草都有添加乳酸菌(LAB)、纤维素酶(CEL)、乳酸菌 纤维素酶(MIX)和对照(CON)4种处理，常温下贮存49天开封后，测定了青贮的细脓壁成分(OCW—总纤维、Ob—低消化性纤维、Oa—高消化性纤维)含量和体外干物质消化率（IVDMD)．结果表明，添加CEL和MIX使所有青贮的OCW、Ob含量和黑小麦草青贮的Oa含量减少，添加CEL使小麦青贮的IVDMD提高；黑小麦草青贮的OCW和Ob含量高于小麦青贮低于黑麦草青贮，Oa含量低于其他两种青贮，IVDMD低于小麦青贮，极显著地高于黑麦草青贮．     

Disappearance of summer collection records for Menochilus sexmaculatus (Coleoptera: Coccinellidae) during climate warming

Long-term changes in the collection season of Menochilus sexmaculatus (Fabricius) were analysed based on 265 specimens collected from the Kansai district, central Japan, during 1949–2004. Results show that collection records in the summer months, July and August, decreased during this period, and that there were no summer records from 2000 to 2004. Concurrently, the annual mean and summer temperatures tended to increase and summer humidity decreased during this period in the Kansai district. Thus, the activity of M. sexmaculatus would be limited in summer because of the recent climate warming.     

An improved method for estimating the activity of a mouse with the photoswitch

A new method for estimating the activity of a mouse by means of the photoswitch is contrived. This device can follow the activity with high fidelity and notable sensitivity, as compared with the conventional method.     

氙原子沿着UO2核燃料位错线的运动行为

推导出了一个相干扩散方程用来研究核燃料边缘位置处氙原子沿着位错线的运动规律,并给出了促使其扩散的微观物理机制,研究了氙气泡在材料中的生长受限行为.利用这种含时的有限扩散技术,可以数值计算张力相干扩散过程,进而给出氙原子沿着位错线的扩散性质.结果表明:氙原子沿着位错线的运动是随着驱动能线性变化的,同时,给出了燃料中边缘位置氙气泡无法长大的物理原因.

Abstract：

We give a coherent diffuse equation to study the behaviors of Xenon atom along the dislocation and the Xenon bubble movement mechanism in the UO2 nuclear Fuel boundary, at the same time, we study the Xenon bubble growth behavior. By using a time-dependent finite-difference technique, we can numerically solve stress coherence diffuse equation and study the transfer properties of Xenon along the dislocation. Our numerical results show that the transport of the xenon atom along dislocation is linear change with the external driven energy, and we give the reason of the growth limit of xenon bubble.     

The 2.8 Å crystal structure of the dynein motor domain

Dyneins are microtubule-based AAA(+) motor complexes that power ciliary beating, cell division, cell migration and intracellular transport. Here we report the most complete structure obtained so far, to our knowledge, of the 380-kDa motor domain of Dictyostelium discoideum cytoplasmic dynein at 2.8?? resolution; the data are reliable enough to discuss the structure and mechanism at the level of individual amino acid residues. Features that can be clearly visualized at this resolution include the coordination of ADP in each of four distinct nucleotide-binding sites in the ring-shaped AAA(+) ATPase unit, a newly identified interaction interface between the ring and mechanical linker, and junctional structures between the ring and microtubule-binding stalk, all of which should be critical for the mechanism of dynein motility. We also identify a long-range allosteric communication pathway between the primary ATPase and the microtubule-binding sites. Our work provides a framework for understanding the mechanism of dynein-based motility.     

The tumour suppressor Hippo acts with the NDR kinases in dendritic tiling and maintenance

Precise patterning of dendritic fields is essential for neuronal circuit formation and function, but how neurons establish and maintain their dendritic fields during development is poorly understood. In Drosophila class IV dendritic arborization neurons, dendritic tiling, which allows for the complete but non-overlapping coverage of the dendritic fields, is established through a 'like-repels-like' behaviour of dendrites mediated by Tricornered (Trc), one of two NDR (nuclear Dbf2-related) family kinases in Drosophila. Here we report that the other NDR family kinase, the tumour suppressor Warts/Lats (Wts), regulates the maintenance of dendrites; in wts mutants, dendrites initially tile the body wall normally, but progressively lose branches at later larval stages, whereas the axon shows no obvious defects. We further provide biochemical and genetic evidence for the tumour suppressor kinase Hippo (Hpo) as an upstream regulator of Wts and Trc for dendrite maintenance and tiling, respectively, thereby revealing important functions of tumour suppressor genes of the Hpo signalling pathway in dendrite morphogenesis.     

A quantum Newton's cradle

It is a fundamental assumption of statistical mechanics that a closed system with many degrees of freedom ergodically samples all equal energy points in phase space. To understand the limits of this assumption, it is important to find and study systems that are not ergodic, and thus do not reach thermal equilibrium. A few complex systems have been proposed that are expected not to thermalize because their dynamics are integrable. Some nearly integrable systems of many particles have been studied numerically, and shown not to ergodically sample phase space. However, there has been no experimental demonstration of such a system with many degrees of freedom that does not approach thermal equilibrium. Here we report the preparation of out-of-equilibrium arrays of trapped one-dimensional (1D) Bose gases, each containing from 40 to 250 (87)Rb atoms, which do not noticeably equilibrate even after thousands of collisions. Our results are probably explainable by the well-known fact that a homogeneous 1D Bose gas with point-like collisional interactions is integrable. Until now, however, the time evolution of out-of-equilibrium 1D Bose gases has been a theoretically unsettled issue, as practical factors such as harmonic trapping and imperfectly point-like interactions may compromise integrability. The absence of damping in 1D Bose gases may lead to potential applications in force sensing and atom interferometry.