WorldWideScience

Sample records for monitoring spindle drive

  1. Monitoring spindle orientation: Spindle position checkpoint in charge.

    Science.gov (United States)

    Caydasi, Ayse K; Ibrahim, Bashar; Pereira, Gislene

    2010-12-11

    Every cell division in budding yeast is inherently asymmetric and counts on the correct positioning of the mitotic spindle along the mother-daughter polarity axis for faithful chromosome segregation. A surveillance mechanism named the spindle position checkpoint (SPOC), monitors the orientation of the mitotic spindle and prevents cells from exiting mitosis when the spindle fails to align along the mother-daughter axis. SPOC is essential for maintenance of ploidy in budding yeast and similar mechanisms might exist in higher eukaryotes to ensure faithful asymmetric cell division. Here, we review the current model of SPOC activation and highlight the importance of protein localization and phosphorylation for SPOC function.

  2. Monitoring spindle orientation: Spindle position checkpoint in charge

    Directory of Open Access Journals (Sweden)

    Pereira Gislene

    2010-12-01

    Full Text Available Abstract Every cell division in budding yeast is inherently asymmetric and counts on the correct positioning of the mitotic spindle along the mother-daughter polarity axis for faithful chromosome segregation. A surveillance mechanism named the spindle position checkpoint (SPOC, monitors the orientation of the mitotic spindle and prevents cells from exiting mitosis when the spindle fails to align along the mother-daughter axis. SPOC is essential for maintenance of ploidy in budding yeast and similar mechanisms might exist in higher eukaryotes to ensure faithful asymmetric cell division. Here, we review the current model of SPOC activation and highlight the importance of protein localization and phosphorylation for SPOC function.

  3. Combination spindle-drive system for high precision machining

    Science.gov (United States)

    Gerth, Howard L.

    1977-07-26

    A combination spindle-drive is provided for fabrication of optical quality surface finishes. Both the spindle-and-drive utilize the spindle bearings for support, thereby removing the conventional drive-means bearings as a source of vibration. An airbearing spindle is modified to carry at the drive end a highly conductive cup-shaped rotor which is aligned with a stationary stator to produce torque in the cup-shaped rotor through the reaction of eddy currents induced in the rotor. This arrangement eliminates magnetic attraction forces and all force is in the form of torque on the cup-shaped rotor.

  4. Testing a Low-Influence Spindle Drive Motor

    Energy Technology Data Exchange (ETDEWEB)

    Hale, L; Wulff, T; Sedgewick, J

    2003-11-05

    Precision spindles used for diamond turning and other applications requiring low error motion generally require a drive system that ideally applies a pure torque to the rotating spindle. Frequently a frameless motor, that is, one without its own bearings, is directly coupled to the spindle to make a compact and simple system having high resonant frequencies. Although in addition to delivering drive torque, asymmetries in the motor cause it to generate disturbance loads (forces and moments) which influence the spindle error motion of the directly coupled system. This paper describes the tests and results for a particular frameless, brushless DC motor that was originally developed for military and space applications requiring very low torque ripple. Because the construction of the motor should also lead to very low disturbance loads, it was selected for use on a new diamond turning and grinding machine under developed at Lawrence Livermore National Laboratory. The level of influence for this motor-spindle combination is expected to be of order one nanometer for radial and axial error motion.

  5. Research on Control System of Spindle Drive for High Speed Spinning Machine

    Institute of Scientific and Technical Information of China (English)

    魏建

    2001-01-01

    Through analyzing the principle of spindle drive of winding mechanism for high speed spinning machine,the article not only describes a kind of mode of spindle drive for take-up motion on the basis of control method of constant velocity winding, but also introduces the design technique of software and hardware for the control system of mechatronics of spindle drive mode for take- up motion on the basis of constant velocity winding for high speed spinning machine with single-chip microcomputer. The mathematical model to describe the spindle rotating speed is established. It is an important technology for high speed spinning machine and provides a feasible application way.

  6. Optical sensor for precision in-situ spindle health monitoring

    Science.gov (United States)

    Zhao, Rui

    An optical sensor which can record in-situ measurements of the dynamic runout of a precision miniature spindle system in a simple and low-cost manner is proposed in this dissertation. Spindle error measurement technology utilizes a cylindrical or spherical target artifact attached to the miniature spindle with non-contact sensors, typically capacitive sensors which are calibrated with a flat target surface not a curved target surface. Due to the different behavior of an electric field between a flat plate and a curved surface and an electric field between two flat plates, capacitive sensors is not suitable for measuring target surfaces smaller than its effective sensing area. The proposed sensor utilizes curved-edge diffraction (CED), which uses the effect of cylindrical surface curvature on the diffraction phenomenon in the transition regions adjacent to shadow, transmission, and reflection boundaries. The laser diodes light incident on the cylindrical surface of precision spindle and photodetectors collect the total field produced by the diffraction around the target surface. Laser diode in the different two direction are incident to the spindle shaft edges along the X and Y axes, four photodetectors collect the total fields produced by interference of multiple waves due to CED around the spindle shaft edges. The X and Y displacement can be obtained from the total fields using two differential amplifier configurations, respectively. Precision miniature spindle (shaft φ5.0mm) runout was measured, and the proposed sensor can perform curve at the different speed of rotation from 1500rpm to 8000rpm in the X and Y axes, respectively. On the other hand, CED also show changes for different running time and temperature of spindle. These results indicate that the proposed sensor promises to be effective for in-situ monitoring of the miniature spindle's health with high resolution, wide bandwidth, and low-cost.

  7. Alpha spindles as neurophysiological correlates indicating attentional shift in a simulated driving task.

    Science.gov (United States)

    Sonnleitner, Andreas; Simon, Michael; Kincses, Wilhelm E; Buchner, Axel; Schrauf, Michael

    2012-01-01

    The intention of this paper is to describe neurophysiological correlates of driver distraction with highly robust parameters in the EEG (i.e. alpha spindles). In a simulated driving task with two different secondary tasks (i.e. visuomotor, auditory), N=28 participants had to perform full stop brakes reacting to appearing stop signs and red traffic lights. Alpha spindle rate was significantly higher during an auditory secondary task and significantly lower during a visuomotor secondary task as compared to driving only. Alpha spindle duration was significantly shortened during a visuomotor secondary task. The results are consistent with the assumption that alpha spindles indicate active inhibition of visual information processing. Effects on the alpha spindles while performing secondary tasks on top of the driving task indicate attentional shift according to the task modality. As compared to alpha band power, both the measures of alpha spindle rate and alpha spindle duration were less vulnerable to artifacts and the effect sizes were larger, allowing for a more accurate description of the current driver state.

  8. Dynamic characteristics of hard disk drive spindles supported by hydrodynamic bearings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Most hard disk spindles currently used are supported by grease lubricated deep-groove ball bearings.However, in the trend of increasing spindle speed and reducing size and cost, the shortcomings of ball bearing spin-dles, such as high non-repeatable run out, high acoustic noise and short life time at high running speed, make themunsuitable for high performance hard disk drives (HDD). On the contrary, the dynamic characteristics of hydrody-namic bearing spindles are superior to that of ball bearing spindles. Therefore, they are considered to be the substi-tute of ball bearing spindles in HDD. In this paper, a simulative setup of HDD is build up. The dynamic characteristicsof liquid lubricated spiral groove bearing(SGB) spindles are studied. The effects of both operating condition andbearing clearance are investigated. It is found that running speed of the spindle has significant influence on its dy-namic performance, while the load has little influence. The effect of clearance is also evident.

  9. A distributed monitoring system for spinning-machine's spindle

    Science.gov (United States)

    Hong, Yang; Ping, Yang; Zhou, Jian Ping

    2005-12-01

    As a key unit with textile coil process technology, spinning-machine's spindles composes of a braking switch, a threephase current motor, rolling bearings and a rotary cup. Aiming at on line monitoring and fault diagnosis, a distributed monitoring system was proposed for real-time data collection and high-speed transmission. In this system, an IPC worked as an upper deck computer and many single chip processors served as bottom controllers that working status data collection and transmission can be conveniently conducted. With the features of bulk processing data and large quantities of controlled nodal points in a workshop condition, the distributed monitoring system was developed with adoption of particular approaches such as a distributed configuration with PCI bus for real time data collection and highspeed transmission, logic compression algorithm for data processing, etc. Therefore this system realizes reliable and high-speed bulk data collection, transmission and processing to meet needs of real-time monitor and control of spindle units.

  10. On-line tool breakage monitoring of vibration tapping using spindle motor current

    Science.gov (United States)

    Li, Guangjun; Lu, Huimin; Liu, Gang

    2008-10-01

    Input current of driving motor has been employed successfully as monitoring the cutting state in manufacturing processes for more than a decade. In vibration tapping, however, the method of on-line monitoring motor electric current has not been reported. In this paper, a tap failure prediction method is proposed to monitor the vibration tapping process using the electrical current signal of the spindle motor. The process of vibration tapping is firstly described. Then the relationship between the torque of vibration tapping and the electric current of motor is investigated by theoretic deducing and experimental measurement. According to those results, a monitoring method of tool's breakage is proposed through monitoring the ratio of the current amplitudes during adjacent vibration tapping periods. Finally, a low frequency vibration tapping system with motor current monitoring is built up using a servo motor B-106B and its driver CR06. The proposed method has been demonstrated with experiment data of vibration tapping in titanic alloys. The result of experiments shows that the method, which can avoid the tool breakage and giving a few error alarms when the threshold of amplitude ratio is 1.2 and there is at least 2 times overrun among 50 adjacent periods, is feasible for tool breakage monitoring in the process of vibration tapping small thread holes.

  11. CLIC Drive Beam Position Monitor

    CERN Document Server

    Smith, S; Gudkov, D; Soby, L; Syratchev, I

    2011-01-01

    CLIC, an electron-positron linear collider proposed to probe the TeV energy scale, is based on a two-beam scheme where RF power to accelerate a high energy luminosity beam is extracted from a high current drive beam. The drive beam is efficiently generated in a long train at modest frequency and current then compressed in length and multiplied in frequency via bunch interleaving. The drive beam decelerator requires >40000 quadrupoles, each holding a beam position monitor (BPM). Though resolution requirements are modest (2 microns) these BPMs face several challenges. They must be compact and inexpensive. They must operate below waveguide cutoff to insure locality of position signals, ruling out processing at the natural 12 GHz bunch spacing frequency. Wakefields must be kept low. We find compact conventional stripline BPM with signals processed below 40 MHz can meet requirements. Choices of mechanical design, operating frequency, bandwidth, calibration and processing algorithm are presented. Calculations of wa...

  12. Research on a Power Management System for Thermoelectric Generators to Drive Wireless Sensors on a Spindle Unit

    Directory of Open Access Journals (Sweden)

    Sheng Li

    2014-07-01

    Full Text Available Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical systems. Typically, the waste heat from spindle units in machine tools creates potential for thermoelectric generation. However, the problem of low and fluctuant ambient temperature differences in spindle units limits the application of thermoelectric generation to drive a wireless sensor. This study is devoted to presenting a transformer-based power management system and its associated control strategy to make the wireless sensor work stably at different speeds of the spindle. The charging/discharging time of capacitors is optimized through this energy-harvesting strategy. A rotating spindle platform is set up to test the performance of the power management system at different speeds. The experimental results show that a longer sampling cycle time will increase the stability of the wireless sensor. The experiments also prove that utilizing the optimal time can make the power management system work more effectively compared with other systems using the same sample cycle.

  13. Research on a power management system for thermoelectric generators to drive wireless sensors on a spindle unit.

    Science.gov (United States)

    Li, Sheng; Yao, Xinhua; Fu, Jianzhong

    2014-07-16

    Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical systems. Typically, the waste heat from spindle units in machine tools creates potential for thermoelectric generation. However, the problem of low and fluctuant ambient temperature differences in spindle units limits the application of thermoelectric generation to drive a wireless sensor. This study is devoted to presenting a transformer-based power management system and its associated control strategy to make the wireless sensor work stably at different speeds of the spindle. The charging/discharging time of capacitors is optimized through this energy-harvesting strategy. A rotating spindle platform is set up to test the performance of the power management system at different speeds. The experimental results show that a longer sampling cycle time will increase the stability of the wireless sensor. The experiments also prove that utilizing the optimal time can make the power management system work more effectively compared with other systems using the same sample cycle.

  14. Extracellular Regulation of the Mitotic Spindle and Fate Determinants Driving Asymmetric Cell Division.

    Science.gov (United States)

    Smith, Prestina; Azzam, Mark; Hinck, Lindsay

    2017-01-01

    Stem cells use mode of cell division, symmetric (SCD) versus asymmetric (ACD), to balance expansion with self-renewal and the generation of daughter cells with different cell fates. Studies in model organisms have identified intrinsic mechanisms that govern this process, which involves partitioning molecular components between daughter cells, frequently through the regulation of the mitotic spindle. Research performed in vertebrate tissues is revealing both conservation of these intrinsic mechanisms and crucial roles for extrinsic cues in regulating the frequency of these divisions. Morphogens and positional cues, including planar cell polarity proteins and guidance molecules, regulate key signaling pathways required to organize cell/ECM contacts and spindle pole dynamics. Noncanonical WNT7A/VANGL2 signaling governs asymmetric cell division and the acquisition of cell fates through spindle pole orientation in satellite stem cells of regenerating muscle fibers. During cortical neurogenesis, the same pathway regulates glial cell fate determination by regulating spindle size, independent of its orientation. Sonic hedgehog (SHH) stimulates the symmetric expansion of cortical stem and cerebellar progenitor cells and contributes to cell fate acquisition in collaboration with Notch and Wnt signaling pathways. SLIT2 also contributes to stem cell homeostasis by restricting ACD frequency through the regulation of spindle orientation. The capacity to influence stem cells makes these secreted factors excellent targets for therapeutic strategies designed to enhance cell populations in degenerative disease or restrict cell proliferation in different types of cancers.

  15. Nuclear envelope-associated dynein drives prophase centrosome separation and enables Eg5-independent bipolar spindle formation.

    Science.gov (United States)

    Raaijmakers, Jonne A; van Heesbeen, Roy G H P; Meaders, Johnathan L; Geers, Erica F; Fernandez-Garcia, Belen; Medema, René H; Tanenbaum, Marvin E

    2012-11-05

    The microtubule motor protein kinesin-5 (Eg5) provides an outward force on centrosomes, which drives bipolar spindle assembly. Acute inhibition of Eg5 blocks centrosome separation and causes mitotic arrest in human cells, making Eg5 an attractive target for anti-cancer therapy. Using in vitro directed evolution, we show that human cells treated with Eg5 inhibitors can rapidly acquire the ability to divide in the complete absence of Eg5 activity. We have used these Eg5-independent cells to study alternative mechanisms of centrosome separation. We uncovered a pathway involving nuclear envelope (NE)-associated dynein that drives centrosome separation in prophase. This NE-dynein pathway is essential for bipolar spindle assembly in the absence of Eg5, but also functions in the presence of full Eg5 activity, where it pulls individual centrosomes along the NE and acts in concert with Eg5-dependent outward pushing forces to coordinate prophase centrosome separation. Together, these results reveal how the forces are produced to drive prophase centrosome separation and identify a novel mechanism of resistance to kinesin-5 inhibitors.

  16. Spindle pole bodies exploit the mitotic exit network in metaphase to drive their age-dependent segregation.

    Science.gov (United States)

    Hotz, Manuel; Leisner, Christian; Chen, Daici; Manatschal, Cristina; Wegleiter, Thomas; Ouellet, Jimmy; Lindstrom, Derek; Gottschling, Dan E; Vogel, Jackie; Barral, Yves

    2012-03-02

    Like many asymmetrically dividing cells, budding yeast segregates mitotic spindle poles nonrandomly between mother and daughter cells. During metaphase, the spindle positioning protein Kar9 accumulates asymmetrically, localizing specifically to astral microtubules emanating from the old spindle pole body (SPB) and driving its segregation to the bud. Here, we show that the SPB component Nud1/centriolin acts through the mitotic exit network (MEN) to specify asymmetric SPB inheritance. In the absence of MEN signaling, Kar9 asymmetry is unstable and its preference for the old SPB is disrupted. Consistent with this, phosphorylation of Kar9 by the MEN kinases Dbf2 and Dbf20 is not required to break Kar9 symmetry but is instead required to maintain stable association of Kar9 with the old SPB throughout metaphase. We propose that MEN signaling links Kar9 regulation to SPB identity through biasing and stabilizing the age-insensitive, cyclin-B-dependent mechanism of symmetry breaking. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Thermal Analysis for Condition Monitoring of Machine Tool Spindles

    Science.gov (United States)

    Clough, D.; Fletcher, S.; Longstaff, A. P.; Willoughby, P.

    2012-05-01

    Decreasing tolerances on parts manufactured, or inspected, on machine tools increases the requirement to have a greater understanding of machine tool capabilities, error sources and factors affecting asset availability. Continuous usage of a machine tool during production processes causes heat generation typically at the moving elements, resulting in distortion of the machine structure. These effects, known as thermal errors, can contribute a significant percentage of the total error in a machine tool. There are a number of design solutions available to the machine tool builder to reduce thermal error including, liquid cooling systems, low thermal expansion materials and symmetric machine tool structures. However, these can only reduce the error not eliminate it altogether. It is therefore advisable, particularly in the production of high value parts, for manufacturers to obtain a thermal profile of their machine, to ensure it is capable of producing in tolerance parts. This paper considers factors affecting practical implementation of condition monitoring of the thermal errors. In particular is the requirement to find links between temperature, which is easily measureable during production and the errors which are not. To this end, various methods of testing including the advantages of thermal images are shown. Results are presented from machines in typical manufacturing environments, which also highlight the value of condition monitoring using thermal analysis.

  18. An approach based on wavelet packet decomposition and Hilbert-Huang transform (WPD-HHT) for spindle bearings condition monitoring

    Science.gov (United States)

    Law, Leh-Sung; Kim, Jong Hyun; Liew, Willey Y. H.; Lee, Sun-Kyu

    2012-11-01

    In order to prevent possible damages to the spindle systems, reliable monitoring techniques are required to provide valuable information on the condition of the spindle condition. A technique is proposed for monitoring spindle bearings conditions via the use of acoustic emission (AE) signals, which implements Hilbert-Huang transform (HHT) analysis to extract the crucial characteristic from the measured data to correlate spindle running condition. The HHT becomes a promising technique in extracting the properties of nonlinear and non-stationary signal. However, the original HHT has several deficiencies, which eventually lead to misinterpretation to the final results. The improved version of HHT is proposed and used to overcome the weakness of the original HHT. The simulation and experimental results are used to verify the effectiveness of the WPD-HHT and therefore Hilbert marginal spectral, compared to traditional Fourier transform. Experimental results are presented to examine and explore the effectiveness of AE for monitoring spindle bearings conditions. It is concluded that good correlation existed between the results obtained by AE data and the increase in the preload, and change in the dimensions and geometry of the spindle bearings and their housings as the temperature increases. In support of this finding, vibration and acceleration data are also used to assess the amount changes in the antistrophic stiffness and radial error motion.

  19. Behavioral self-monitoring for safe driving.

    Science.gov (United States)

    Nielsen, Don

    2010-01-01

    Self-monitoring is an approach to change behavior by manipulating antecedents, observing and recording target behaviors, and receiving feedback and consequences. In the present paper the basic procedures of self-monitoring and safe driving are identified. Self-monitoring checklist development is presented and a case study using antecedents to signal behavior is discussed. The purpose of this study was to determine if a prompt can increase the use of turn signals of drivers. The study incorporated three phases, a baseline phase, an intervention phase, and a return to baseline phase (ABA). The effectiveness of the intervention, a prompt to use turn signals, appeared to be an effective in increasing turn signal usage among motorists, from 33.5 percent (phase A) to 70.3 percent (phase B).

  20. Spindle picker harvest speed effects

    Science.gov (United States)

    The gear drive of a modern John Deere Pro 16 picker unit was modified so that spindle speed was reduced without changing the drum speed. Three 1-row picking units were used in the study, one with the standard drive speeds, one with 25% reduction in spindle drive speed, and one with 50% reduction in...

  1. Analysis on machine tool systems using spindle vibration monitoring for automatic tool changer

    Directory of Open Access Journals (Sweden)

    Shang-Liang Chen

    2015-12-01

    Full Text Available Recently, the intelligent systems of technology have become one of the major items in the development of machine tools. One crucial technology is the machinery status monitoring function, which is required for abnormal warnings and the improvement of cutting efficiency. During processing, the mobility act of the spindle unit determines the most frequent and important part such as automatic tool changer. The vibration detection system includes the development of hardware and software, such as vibration meter, signal acquisition card, data processing platform, and machine control program. Meanwhile, based on the difference between the mechanical configuration and the desired characteristics, it is difficult for a vibration detection system to directly choose the commercially available kits. For this reason, it was also selected as an item for self-development research, along with the exploration of a significant parametric study that is sufficient to represent the machine characteristics and states. However, we also launched the development of functional parts of the system simultaneously. Finally, we entered the conditions and the parameters generated from both the states and the characteristics into the developed system to verify its feasibility.

  2. Spindle pole body-anchored Kar3 drives the nucleus along microtubules from another nucleus in preparation for nuclear fusion during yeast karyogamy.

    Science.gov (United States)

    Gibeaux, Romain; Politi, Antonio Z; Nédélec, François; Antony, Claude; Knop, Michael

    2013-02-01

    Nuclear migration during yeast karyogamy, termed nuclear congression, is required to initiate nuclear fusion. Congression involves a specific regulation of the microtubule minus end-directed kinesin-14 motor Kar3 and a rearrangement of the cytoplasmic microtubule attachment sites at the spindle pole bodies (SPBs). However, how these elements interact to produce the forces necessary for nuclear migration is less clear. We used electron tomography, molecular genetics, quantitative imaging, and first principles modeling to investigate how cytoplasmic microtubules are organized during nuclear congression. We found that Kar3, with the help of its light chain, Cik1, is anchored during mating to the SPB component Spc72 that also serves as a nucleator and anchor for microtubules via their minus ends. Moreover, we show that no direct microtubule-microtubule interactions are required for nuclear migration. Instead, SPB-anchored Kar3 exerts the necessary pulling forces laterally on microtubules emanating from the SPB of the mating partner nucleus. Therefore, a twofold symmetrical application of the core principle that drives nuclear migration in higher cells is used in yeast to drive nuclei toward each other before nuclear fusion.

  3. Mechanisms of centrosome separation and bipolar spindle assembly.

    Science.gov (United States)

    Tanenbaum, Marvin E; Medema, René H

    2010-12-14

    Accurate segregation of chromosomes during cell division is accomplished through the assembly of a bipolar microtubule-based structure called the mitotic spindle. Work over the past two decades has identified a core regulator of spindle bipolarity, the microtubule motor protein kinesin-5. However, an increasing body of evidence has emerged demonstrating that kinesin-5-independent mechanisms driving bipolar spindle assembly exist as well. Here, we discuss different pathways that promote initial centrosome separation and bipolar spindle assembly.

  4. Dynamic Response Analysis of Motorized Spindle System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; LUO Yi-chao; XU Juan; XIAO Ru-feng; LI Xian-hui

    2013-01-01

    As to motorized spindle system, this paper builds a simplified 3D model of spindle and bearing, performs structure modal analysis, reveals its dynamic characteristics under the free model;furthermore, modifies bearing radial stiffness and number of model, and studies the change of modal parameters. On this basis, through the harmonic response analysis of the finite element model, dy-namic response characteristic caused by imbalance of monitored spindle system and law of vibration response to different amount of unbalance is analyzed.

  5. The Application for Spindle Monitor System Based MCGS%基于MCGS组态软件下电主轴监控系统应用

    Institute of Scientific and Technical Information of China (English)

    王胜; 苗晓锋

    2011-01-01

    This thesis introduces the key parameters that the machine tool spindle needed to monitor、hardware components about the system and some mainly functions of configuration software MGCS in China, MGCS(M onitor and Control Generated System) is, a online monitoring and analysis system, especially designed to machine tool spindle. The system acquires and analyzes the Real-Time datas generated from machine tool spindle vibration sign、 rotational speed、 motor、 the temperature between front and back bearing、 axial displacement and relative condition parameters. It can provide judging information for workers who lack spindle and bearing knowledge by indicators so as to recognize the working condition、discover the fault sign, and eliminate the fault in time so that avoiding the destructive accidents.It also lays a solid speciality foundation to professional and technical person for their bearing and machine tool spindle optimum design、 test and some other aspects.%文章以高速电主轴监控系统为研究对象,分析了机床电主轴需要监测的几个主要参数、系统主要硬件构成和国产组态软件MGCS的主要功能.通过电主轴专用实验平台采集分析机床主轴的振动信号、转速、电机和前后轴承温度、轴向位移及相关状态参数.经采集系统分析后,可通过指示灯为缺乏主轴、轴承知识的一线工作人员提供判断信息.试验证明:该采集系统能够及时识别机床主轴的状态、发现故障早期征兆,从而可以及时消除故障隐患,避免破坏性事故的发生,为专业技术人员在机床主轴的优化设计、检修等方面提供了坚实的技术基础.

  6. Study on the Structure about Exchangeable A-axis of Direct-drive Bi-rotary Spindle Head%直驱式双摆头交换A轴相关结构的研究

    Institute of Scientific and Technical Information of China (English)

    刘波; 李焱

    2011-01-01

    The issues about exchangeable A-axis of direct-drive bi-rotary spindle head, such as the quick coupling technology, positioning, clamping and torque transmission technologies and layout of A-axis, were introduced and solutions were provided.%介绍直驱式双摆头交换A轴的相关结构涉及到的快换技术,定位、夹紧、扭矩传递,A轴安置等一系列问题并提出解决方案.

  7. Antagonistic spindle motors and MAPs regulate metaphase spindle length and chromosome segregation.

    Science.gov (United States)

    Syrovatkina, Viktoriya; Fu, Chuanhai; Tran, Phong T

    2013-12-02

    Metaphase describes a phase of mitosis where chromosomes are attached and oriented on the bipolar spindle for subsequent segregation at anaphase. In diverse cell types, the metaphase spindle is maintained at characteristic constant length [1-3]. Metaphase spindle length is proposed to be regulated by a balance of pushing and pulling forces generated by distinct sets of spindle microtubules (MTs) and their interactions with motors and MT-associated proteins (MAPs). Spindle length is further proposed to be important for chromosome segregation fidelity, as cells with shorter- or longer-than-normal metaphase spindles, generated through deletion or inhibition of individual mitotic motors or MAPs, showed chromosome segregation defects. To test the force-balance model of spindle length control and its effect on chromosome segregation, we applied fast microfluidic temperature control with live-cell imaging to monitor the effect of deleting or switching off different combinations of antagonistic force contributors in the fission yeast metaphase spindle. We show that the spindle midzone proteins kinesin-5 cut7p and MT bundler ase1p contribute to outward-pushing forces and that the spindle kinetochore proteins kinesin-8 klp5/6p and dam1p contribute to inward-pulling forces. Removing these proteins individually led to aberrant metaphase spindle length and chromosome segregation defects. Removing these proteins in antagonistic combination rescued the defective spindle length and in some combinations also partially rescued chromosome segregation defects.

  8. Smartphone Based Approach For Monitoring Inefficient And Unsafe Driving Behavior And Recognizing Drink And Drive Conditions.

    Directory of Open Access Journals (Sweden)

    G. V. Mane

    2015-08-01

    Full Text Available Many automobile drivers having knowledge of the driving behaviours and habits that can lead to inefficient and unsafe driving. However it is often the case that these same drivers unknowingly manifest these inefficient and unsafe driving behaviours in their everyday driving activity. The proposed system proposes a practical and economical way to capture measure and alert drives of inefficient and unsafe driving as well as highly efficient system aimed at early detection and alert of dangerous vehicle maneuvers typically related to drunk driving. The upcoming solution consists of a mobile application running on a modern smartphone device paired with a compatible OBDII On-board diagnostics II reader.

  9. Zika virus causes supernumerary foci with centriolar proteins and impaired spindle positioning

    Science.gov (United States)

    Wolf, Benita; Diop, Fodé; Ferraris, Pauline; Wichit, Sineewanlaya; Busso, Coralie; Missé, Dorothée

    2017-01-01

    Zika virus (ZIKV) causes congenital microcephaly. Although ZIKV can impair cell cycle progression and provoke apoptosis, which probably contributes to disease aetiology through depletion of neural progenitor cells, additional cellular mechanisms may be important. Here, we investigated whether ZIKV infection alters centrosome number and spindle positioning, because such defects are thought to be at the root of inherited primary autosomal recessive microcephaly (MCPH). In addition to HeLa cells, in which centrosome number and spindle positioning can be well monitored, we analysed retinal epithelial cells (RPE-1), as well as brain-derived microglial (CHME-5) and neural progenitor (ReN) cells, using immunofluorescence. We established that ZIKV infection leads to supernumerary foci containing centriolar proteins that in some cases drive multipolar spindle assembly, as well as spindle positioning defects in HeLa, RPE-1 and CHME-5 cells, but not in ReN cells. We uncovered similar phenotypes in HeLa cells upon infection with dengue virus (DENV-2), another flavivirus that does not target brain cells and does not cause microcephaly. We conclude that infection with Flaviviridae can increase centrosome numbers and impair spindle positioning, thus potentially contributing to microcephaly in the case of Zika. PMID:28100662

  10. Next generation spindles for micromilling.

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Jay P. (Machine Tool Research Center, University of Florida, Gainesville, FL); Payne, Scott W. T. (Machine Tool Research Center, University of Florida, Gainesville, FL); Gill, David Dennis; Ziegert, John C. (Machine Tool Research Center, University of Florida, Gainesville, FL); Jokiel, Bernhard, Jr.

    2004-12-01

    There exists a wide variety of important applications for micro- and meso-scale mechanical systems in the commercial and defense sectors, which require high-strength materials and complex geometries that cannot be produced using current MEMS fabrication technologies. Micromilling has great potential to fill this void in MEMS technology by adding the capability of free form machining of complex 3D shapes from a wide variety and combination of traditional, well-understood engineering alloys, glasses and ceramics. Inefficiencies in micromilling result from the relationships between a cutting tool's breaking strength, the applied cutting force, and the metal removal rate. Because machining times in mesofeatures scale inversely to the part size, a feature 1/10th as large will take 10 times as long to machine. Also, required chip sizes of 1 m or less are cut with tools having edge radius of 2-3 m, the cutting edge effectively has a highly negative rake angle, cutting forces are increased significantly causing chip loads to be further reduced and the machining takes even longer than predicted above. However, cutting forces do not increase with cutting speed, so faster spindles with reduced tool runout are the path to achieve efficient mesoscale milling. This research explored the development of new ultra-high speed micromilling spindles. A novel air-bearing spindle design is discussed that will run at very high speeds (450,000 rpm) and provide very minimal runout allowing the best use of micromilling cutters and reducing overall machining time drastically. Two generations of this spindle design were completed; one with an air bearing supported tool shaft and one with a novel rolling element bearing supported tool shaft. Both designs utilized friction-drive systems that relied on diameter differences between the drive wheel (operating at speeds up to 90,000 rpm) and the tool shaft to achieve high rotational tool speeds. Runout, stiffness, and machining tests were

  11. Self-Organization and Forces in the Mitotic Spindle.

    Science.gov (United States)

    Pavin, Nenad; Tolić, Iva M

    2016-07-05

    At the onset of division, the cell forms a spindle, a precise self-constructed micromachine composed of microtubules and the associated proteins, which divides the chromosomes between the two nascent daughter cells. The spindle arises from self-organization of microtubules and chromosomes, whose different types of motion help them explore the space and eventually approach and interact with each other. Once the interactions between the chromosomes and the microtubules have been established, the chromosomes are moved to the equatorial plane of the spindle and ultimately toward the opposite spindle poles. These transport processes rely on directed forces that are precisely regulated in space and time. In this review, we discuss how microtubule dynamics and their rotational movement drive spindle self-organization, as well as how the forces acting in the spindle are generated, balanced, and regulated.

  12. Mitotic spindle perturbations

    NARCIS (Netherlands)

    Tame, Mihoko Amy

    2016-01-01

    Microtubules are major components of the cytoskeleton and form the bipolar spindle apparatus during mitosis. The mitotic spindle consists of highly dynamic microtubule polymers that are under constant modulation, controlled by multiple motor proteins and microtubule-associated proteins. This tight s

  13. Road Safety Data, Collection, Transfer and Analysis DaCoTa. Workpackage 6, Driver Behaviour Monitoring through Naturalistic Driving: Deliverable 6.5: Naturalistic Driving for cross-national monitoring of SPIs and Exposure : an overview.

    NARCIS (Netherlands)

    Wegman, R.W.N. & Bos, N.M.

    2015-01-01

    WP6 of DaCoTA, Driver Behaviour Monitoring through Naturalistic Driving, focuses on the usefulness and feasibility of applying the Naturalistic Driving method for monitoring within the framework of ERSO. The aim is to continuously collect comparable information about the road safety level in EU Memb

  14. Road Safety Data, Collection, Transfer and Analysis DaCoTa. Workpackage 6, Driver Behaviour Monitoring through Naturalistic Driving: Deliverable 6.5: Naturalistic Driving for cross-national monitoring of SPIs and Exposure : an overview.

    NARCIS (Netherlands)

    Wegman, R.W.N. & Bos, N.M.

    2015-01-01

    WP6 of DaCoTA, Driver Behaviour Monitoring through Naturalistic Driving, focuses on the usefulness and feasibility of applying the Naturalistic Driving method for monitoring within the framework of ERSO. The aim is to continuously collect comparable information about the road safety level in EU Memb

  15. Phosphorylation-dependent protein interactions at the spindle midzone mediate cell cycle regulation of spindle elongation.

    Science.gov (United States)

    Khmelinskii, Anton; Roostalu, Johanna; Roque, Helio; Antony, Claude; Schiebel, Elmar

    2009-08-01

    The metaphase-to-anaphase transition is one of the most dramatic and highly regulated steps in cell division. At anaphase onset the protease separase dissolves sister chromatid cohesion. Simultaneously, the mitotic spindle elongates as interpolar microtubules (iMTs) slide apart at the spindle midzone, ensuring chromosome segregation. However, it remains unclear how spindle elongation is coordinated with cell cycle progression. Here we demonstrate that phosphorylation of the midzone organizer Ase1 controls localization and function of Cin8, a kinesin-5 that slides iMTs relative to each other. Phosphorylation of Ase1 by Cdk1 (cyclin-dependent kinase) inhibits Cin8 binding to iMTs, preventing bending and collapse of the metaphase spindle. In anaphase Ase1 dephosphorylation by the separase-activated phosphatase Cdc14 is necessary and sufficient for Cin8 recruitment to the midzone, where it drives spindle elongation. Our results reveal that sliding forces at the midzone are activated by separase and explain how spindle elongation is triggered with anaphase entry.

  16. A Flux weakening Control for Induction Motor for Spindle Drive%主轴驱动用异步电机的弱磁控制算法研究

    Institute of Scientific and Technical Information of China (English)

    邓新锦; 曾岳南; 陈康平

    2014-01-01

    针对数控机床主轴驱动系统中的异步电机运行所要求宽调速范围、大转矩、高的动态性能要求,采用了一种基于转子磁链定向的电压轨迹弱磁控制方法搭建的高性能驱动控制系统,重点分析了电压轨迹的弱磁控制原理,该方法能充分利用逆变器的最大可用电压和电流,并且在整个弱磁区域能实现最大转矩输出。同时,在恒转矩区域和弱磁调速区之间能够实现平滑的过渡。最后,在1.5 kW系统上对所提出的弱磁方法进行仿真验证。仿真结果表明该方法是可行、有效的。%Induction motor used in spindle drive systems of machine tool which was required out a wide speed range ,high torque ,high dynamic performance . This paper proposed a flux-weaken ing control strate-gy based on rotor flux oriented vector control method . focusing on analysis of the voltage trajectory weake-ning control . the method can make full use of the maximum available inverter voltage and current , and in the field weakening region to achieve maximum torque output. Meanwhile, Smooth and automatic transition between the constant torque region and a weak magnetic speed region can be achieved. Finally,The validity of the proposed field weakening technique is validated by computer simulations tests with a 1. 5kW induction motor drive system. Simulation results will be presented to fully support the claims.

  17. Design and characterization of a prototype stripline beam position monitor for the Clic Drive Beam*

    CERN Document Server

    Benot-Morell, A; Wendt, M; Nappa, J M; Tassan-Viol, J; Vilalte, S; Smith, S

    2012-01-01

    The prototype of a stripline Beam Position Monitor (BPM) with its associated readout electronics is under development at CERN, in collaboration with SLAC, LAPP and IFIC. The anticipated position resolution and accuracy are expected to be below 2μm and 20μm respectively for operation of the BPM in the CLIC drive beam (DB) linac. This paper describes the particular CLIC DB conditions with respect to the beam position monitoring, presents the measurement concept, and summarizes electromagnetic simulations and RF measurements performed on the prototype.

  18. Anthrax receptors position the spindle.

    Science.gov (United States)

    Minc, Nicolas; Piel, Matthieu

    2013-01-01

    Spindle orientation plays a pivotal role in tissue morphogenesis. An asymmetric anthrax receptor cap is revealed to promote activation of a formin to orient the spindle along the planar cell polarity (PCP) axis in zebrafish dorsal epiblast cells.

  19. Intelligent pump drives. Simulation, condition monitoring, fault diagnosis and energy efficiency; Intelligente Pumpenantriebe. Simulation, Condition Monitoring, Fehlerdiagnose und Energieeffizienz

    Energy Technology Data Exchange (ETDEWEB)

    Kleinmann, Stefan [Allweiler AG, Radolfzell (Germany); Leonardo, Domenico; Koller-Hodac, Agathe [Hochschule fuer Technik Rapperswil (Switzerland)

    2011-07-01

    The authors of the contribution under consideration report on an implementation of a simulation environment and a fault diagnostic system for an oil burner application. Using a modification of the application hardware, an additional increase in efficiency in an advanced control of pump drives is achieved. The properties of the combustion process are not affected adversely. All changes to the system can be investigated in simulations for feasibility and impact. Using the simulation model, a diagnostic system is brought up enabling a remote monitoring for example.

  20. Thermal Error Modelling of the Spindle Using Neurofuzzy Systems

    Directory of Open Access Journals (Sweden)

    Jingan Feng

    2016-01-01

    Full Text Available This paper proposes a new combined model to predict the spindle deformation, which combines the grey models and the ANFIS (adaptive neurofuzzy inference system model. The grey models are used to preprocess the original data, and the ANFIS model is used to adjust the combined model. The outputs of the grey models are used as the inputs of the ANFIS model to train the model. To evaluate the performance of the combined model, an experiment is implemented. Three Pt100 thermal resistances are used to monitor the spindle temperature and an inductive current sensor is used to obtain the spindle deformation. The experimental results display that the combined model can better predict the spindle deformation compared to BP network, and it can greatly improve the performance of the spindle.

  1. Metaphase Spindle Assembly

    Directory of Open Access Journals (Sweden)

    Tarun M. Kapoor

    2017-02-01

    Full Text Available A microtubule-based bipolar spindle is required for error-free chromosome segregation during cell division. In this review I discuss the molecular mechanisms required for the assembly of this dynamic micrometer-scale structure in animal cells.

  2. Status of the Stripline Beam Position Monitor developement for the CLIC Drive Beam

    CERN Document Server

    Benot-Morell, A; Wendt, M; Faus-Golfe, A; Nappa, J M; Vilalte, S; Smith, S

    2013-01-01

    In collaboration with SLAC, LAPP and IFIC, a first prototype of a stripline Beam Position Monitor (BPM) for the CLIC Drive Beam and its associated readout electronics has been successfully tested in the CLIC Test Facility linac (CTF3) at CERN. In addition, a modified prototype with downstream terminated striplines is under development to improve the suppression of unwanted RF signal interference. This paper presents the results of the beam tests, and the most relevant aspects for the modified stripline BPM design and its expected improvements.

  3. Fission yeast cells undergo nuclear division in the absence of spindle microtubules.

    Directory of Open Access Journals (Sweden)

    Stefania Castagnetti

    Full Text Available Mitosis in eukaryotic cells employs spindle microtubules to drive accurate chromosome segregation at cell division. Cells lacking spindle microtubules arrest in mitosis due to a spindle checkpoint that delays mitotic progression until all chromosomes have achieved stable bipolar attachment to spindle microtubules. In fission yeast, mitosis occurs within an intact nuclear membrane with the mitotic spindle elongating between the spindle pole bodies. We show here that in fission yeast interference with mitotic spindle formation delays mitosis only briefly and cells proceed to an unusual nuclear division process we term nuclear fission, during which cells perform some chromosome segregation and efficiently enter S-phase of the next cell cycle. Nuclear fission is blocked if spindle pole body maturation or sister chromatid separation cannot take place or if actin polymerization is inhibited. We suggest that this process exhibits vestiges of a primitive nuclear division process independent of spindle microtubules, possibly reflecting an evolutionary intermediate state between bacterial and Archeal chromosome segregation where the nucleoid divides without a spindle and a microtubule spindle-based eukaryotic mitosis.

  4. Remote sensing monitoring and driving force analysis to forest and greenbelt in Zhuhai

    Science.gov (United States)

    Yuliang Qiao, Pro.

    As an important city in the southern part of Chu Chiang Delta, Zhuhai is one of the four special economic zones which are opening up to the outside at the earliest in China. With pure and fresh air and trees shading the street, Zhuhai is a famous beach port city which is near the mountain and by the sea. On the basis of Garden City, the government of Zhuhai decides to build National Forest City in 2011, which firstly should understand the situation of greenbelt in Zhuhai in short term. Traditional methods of greenbelt investigation adopt the combination of field surveying and statistics, whose efficiency is low and results are not much objective because of artificial influence. With the adventure of the information technology such as remote sensing to earth observation, especially the launch of many remote sensing satellites with high resolution for the past few years, kinds of urban greenbelt information extraction can be carried out by using remote sensing technology; and dynamic monitoring to spatial pattern evolvement of forest and greenbelt in Zhuhai can be achieved by the combination of remote sensing and GIS technology. Taking Landsat5 TM data in 1995, Landsat7 ETM+ data in 2002, CCD and HR data of CBERS-02B in 2009 as main information source, this research firstly makes remote sensing monitoring to dynamic change of forest and greenbelt in Zhuhai by using the combination of vegetation coverage index and three different information extraction methods, then does a driving force analysis to the dynamic change results in 3 months. The results show: the forest area in Zhuhai shows decreasing tendency from 1995 to 2002, increasing tendency from 2002 to 2009; overall, the forest area show a small diminution tendency from 1995 to 2009. Through the comparison to natural and artificial driving force, the artificial driving force is the leading factor to the change of forest and greenbelt in Zhuhai. The research results provide a timely and reliable scientific basis

  5. A Gas-Jet Profile Monitor for the CLIC Drive Beam

    CERN Document Server

    Jeff, A; Lefevre, T; Tzoganis, V; Welsch, C P

    2013-01-01

    The Compact Linear Collider (CLIC) will use a novel acceleration scheme in which energy extracted from a very intense beam of relatively low-energy electrons (the Drive Beam) is used to accelerate a lower intensity Main Beam to very high energy. The high intensity of the Drive Beam, with pulses of more than 1015 electrons, poses a challenge for conventional profile measurements such as wire scanners. Thus, new non-invasive profile measurements are being investigated. Profile monitors using gas ionisation or fluorescence have been used at a number of accelerators. Typically, extra gas must be injected at the monitor and the rise in pressure spreads for some distance down the beam pipe. In contrast, a gas jet can be fired across the beam into a receiving chamber, with little gas escaping into the rest of the beam pipe. In addition, a gas jet shaped into a thin plane can be used like a screen on which the beam crosssectionis imaged. In this paper we present some arrangements for the generation of such a jet. In ...

  6. Dynein, Lis1 and CLIP-170 counteract Eg5-dependent centrosome separation during bipolar spindle assembly

    NARCIS (Netherlands)

    M.E. Tanenbaum (Marvin); L. Macůrek (Libor); N.J. Galjart (Niels); R.H. Medema (Rene)

    2008-01-01

    textabstractBipolar spindle assembly critically depends on the microtubule plus-end-directed motor Eg5 that binds antiparallel microtubules and slides them in opposite directions. As such, Eg5 can produce the necessary outward force within the spindle that drives centrosome separation and inhibition

  7. VHL loss causes spindle misorientation and chromosome instability.

    Science.gov (United States)

    Thoma, Claudio R; Toso, Alberto; Gutbrodt, Katrin L; Reggi, Sabina P; Frew, Ian J; Schraml, Peter; Hergovich, Alexander; Moch, Holger; Meraldi, Patrick; Krek, Wilhelm

    2009-08-01

    Error-free mitosis depends on fidelity-monitoring checkpoint systems that ensure correct temporal and spatial coordination of chromosome segregation by the microtubule spindle apparatus. Defects in these checkpoint systems can lead to genomic instability, an important aspect of tumorigenesis. Here we show that the von Hippel-Lindau (VHL) tumour suppressor protein, pVHL, which is inactivated in hereditary and sporadic forms of renal cell carcinoma, localizes to the mitotic spindle in mammalian cells and its functional inactivation provokes spindle misorientation, spindle checkpoint weakening and chromosomal instability. Spindle misorientation is linked to unstable astral microtubules and is supressed by the restoration of wild-type pVHL in pVHL-deficient cells, but not in naturally-occurring VHL disease mutants that are defective in microtubule stabilization. Impaired spindle checkpoint function and chromosomal instability are the result of reduced Mad2 (mitotic arrest deficient 2) levels actuated by pVHL-inactivation and are rescued by re-expression of either Mad2 or pVHL in VHL-defective cells. An association between VHL inactivation, reduced Mad2 levels and increased aneuploidy was also found in human renal cancer, implying that the newly identified functions of pVHL in promoting proper spindle orientation and chromosomal stability probably contribute to tumour suppression.

  8. The Spindle Type Cotton Harvester

    Science.gov (United States)

    The spindle type cotton picker was commercialized during the mid 1900’s and is currently produced by two US agricultural equipment manufacturers, John Deere and CaseIH. Picking is the predominate machine harvest method used throughout the US and world. Harvesting efficiency of a spindle type cotton ...

  9. Statistical analysis of sleep spindle occurrences.

    Science.gov (United States)

    Panas, Dagmara; Malinowska, Urszula; Piotrowski, Tadeusz; Żygierewicz, Jarosław; Suffczyński, Piotr

    2013-01-01

    Spindles - a hallmark of stage II sleep - are a transient oscillatory phenomenon in the EEG believed to reflect thalamocortical activity contributing to unresponsiveness during sleep. Currently spindles are often classified into two classes: fast spindles, with a frequency of around 14 Hz, occurring in the centro-parietal region; and slow spindles, with a frequency of around 12 Hz, prevalent in the frontal region. Here we aim to establish whether the spindle generation process also exhibits spatial heterogeneity. Electroencephalographic recordings from 20 subjects were automatically scanned to detect spindles and the time occurrences of spindles were used for statistical analysis. Gamma distribution parameters were fit to each inter-spindle interval distribution, and a modified Wald-Wolfowitz lag-1 correlation test was applied. Results indicate that not all spindles are generated by the same statistical process, but this dissociation is not spindle-type specific. Although this dissociation is not topographically specific, a single generator for all spindle types appears unlikely.

  10. Microtubule Dynamics and Oscillating State for Mitotic Spindle

    CERN Document Server

    Rashid-Shomali, Safura

    2010-01-01

    We present a physical mechanism that can cause the mitotic spindle to oscillate. The driving force for this mechanism emerges from the polymerization of astral microtubules interacting with the cell cortex. We show that Brownian ratchet model for growing microtubules reaching the cell cortex, mediate an effective mass to the spindle body and therefore force it to oscillate. We compare the predictions of this mechanism with the previous mechanisms which were based on the effects of motor proteins. Finally we combine the effects of microtubules polymerization and motor proteins, and present the detailed phase diagram for possible oscillating states.

  11. The role of Hklp2 in the stabilization and maintenance of spindle bipolarity.

    Science.gov (United States)

    Vanneste, David; Takagi, Masatoshi; Imamoto, Naoko; Vernos, Isabelle

    2009-11-03

    Spindle bipolarity relies on a fine balance of forces exerted by various molecular motors [1-4]. In most animal cells, spindle bipolarity requires sustained outward forces to push the spindle poles apart, an activity that is provided by Eg5, a conserved homotetrameric plus-end-directed kinesin that crosslinks and slides antiparallel microtubules apart [5]. These pushing forces are balanced by inward minus-end-directed forces. Impairing both Eg5 and dynein restores the formation of functional bipolar spindles [4], although the mechanism at play is far from clear. The current model also fails to explain why in some systems Eg5 inhibition does not promote bipolar spindle collapse [6, 7] or why increasing Eg5 levels does not interfere with bipolar spindle assembly [8]. Moreover, the C. elegans Eg5 ortholog is not required for bipolar spindle formation [9]. We show here that the kinesin Hklp2 participates in the assembly and stabilization of the bipolar spindle. Hklp2 localizes to the mitotic microtubules in a TPX2-dependent manner and to the chromosomes through Ki67. Our data indicate that its mechanism of action is clearly distinct from and complementary to that of Eg5, providing an additional understanding of the mechanism driving the formation and maintenance of the bipolar spindle.

  12. Kinetochore-microtubule attachment is sufficient to satisfy the human spindle assembly checkpoint

    NARCIS (Netherlands)

    Etemad, Banafsheh; Kuijt, Timo E F; Kops, Geert J P L

    2015-01-01

    The spindle assembly checkpoint (SAC) is a genome surveillance mechanism that protects against aneuploidization. Despite profound progress on understanding mechanisms of its activation, it remains unknown what aspect of chromosome-spindle interactions is monitored by the SAC: kinetochore-microtubule

  13. Asymmetry of the budding yeast Tem1 GTPase at spindle poles is required for spindle positioning but not for mitotic exit.

    Directory of Open Access Journals (Sweden)

    Ilaria Scarfone

    2015-02-01

    Full Text Available The asymmetrically dividing yeast S. cerevisiae assembles a bipolar spindle well after establishing the future site of cell division (i.e., the bud neck and the division axis (i.e., the mother-bud axis. A surveillance mechanism called spindle position checkpoint (SPOC delays mitotic exit and cytokinesis until the spindle is properly positioned relative to the mother-bud axis, thereby ensuring the correct ploidy of the progeny. SPOC relies on the heterodimeric GTPase-activating protein Bub2/Bfa1 that inhibits the small GTPase Tem1, in turn essential for activating the mitotic exit network (MEN kinase cascade and cytokinesis. The Bub2/Bfa1 GAP and the Tem1 GTPase form a complex at spindle poles that undergoes a remarkable asymmetry during mitosis when the spindle is properly positioned, with the complex accumulating on the bud-directed old spindle pole. In contrast, the complex remains symmetrically localized on both poles of misaligned spindles. The mechanism driving asymmetry of Bub2/Bfa1/Tem1 in mitosis is unclear. Furthermore, whether asymmetry is involved in timely mitotic exit is controversial. We investigated the mechanism by which the GAP Bub2/Bfa1 controls GTP hydrolysis on Tem1 and generated a series of mutants leading to constitutive Tem1 activation. These mutants are SPOC-defective and invariably lead to symmetrical localization of Bub2/Bfa1/Tem1 at spindle poles, indicating that GTP hydrolysis is essential for asymmetry. Constitutive tethering of Bub2 or Bfa1 to both spindle poles impairs SPOC response but does not impair mitotic exit. Rather, it facilitates mitotic exit of MEN mutants, likely by increasing the residence time of Tem1 at spindle poles where it gets active. Surprisingly, all mutant or chimeric proteins leading to symmetrical localization of Bub2/Bfa1/Tem1 lead to increased symmetry at spindle poles of the Kar9 protein that mediates spindle positioning and cause spindle misalignment. Thus, asymmetry of the Bub2/Bfa1/Tem1

  14. Development of a Revolutionary High Speed Spindle

    Science.gov (United States)

    Agba, Emmanuel I.

    1999-01-01

    This report presents the development of a hydraulic motor driven spindle system to be employed for high speed machining of composite materials and metals. The spindle system is conceived to be easily retrofitted into conventional milling machines. The need for the hydraulic spindle arises because of the limitations placed on conventional electric motor driven spindles by the low cutting power and the presence of vibrational phenomena associated with voltage frequency at high rotational speeds. Also, the electric motors are usually large and expensive when power requirements are moderately high. In contrast, hydraulic motor driven spindles promise a distinct increase in spindle life over the conventional electric motor driven spindles. In this report, existing technologies applicable to spindle holder for severe operating conditions were reviewed, conceptual designs of spindle holder system were developed and evaluated, and a detailed design of an acceptable concept was conducted. Finally, a rapid prototype of the design was produced for design evaluation.

  15. Dynein, Lis1 and CLIP-170 counteract Eg5-dependent centrosome separation during bipolar spindle assembly.

    Science.gov (United States)

    Tanenbaum, Marvin E; Macůrek, Libor; Galjart, Niels; Medema, René H

    2008-12-17

    Bipolar spindle assembly critically depends on the microtubule plus-end-directed motor Eg5 that binds antiparallel microtubules and slides them in opposite directions. As such, Eg5 can produce the necessary outward force within the spindle that drives centrosome separation and inhibition of this antiparallel sliding activity results in the formation of monopolar spindles. Here, we show that upon depletion of the minus-end-directed motor dynein, or the dynein-binding protein Lis1, bipolar spindles can form in human cells with substantially less Eg5 activity, suggesting that dynein and Lis1 produce an inward force that counteracts the Eg5-dependent outward force. Interestingly, we also observe restoration of spindle bipolarity upon depletion of the microtubule plus-end-tracking protein CLIP-170. This function of CLIP-170 in spindle bipolarity seems to be mediated through its interaction with dynein, as loss of CLIP-115, a highly homologous protein that lacks the dynein-dynactin interaction domain, does not restore spindle bipolarity. Taken together, these results suggest that complexes of dynein, Lis1 and CLIP-170 crosslink and slide microtubules within the spindle, thereby producing an inward force that pulls centrosomes together.

  16. An organelle-exclusion envelope assists mitosis and underlies distinct molecular crowding in the spindle region.

    Science.gov (United States)

    Schweizer, Nina; Pawar, Nisha; Weiss, Matthias; Maiato, Helder

    2015-08-31

    The mitotic spindle is a microtubular assembly required for chromosome segregation during mitosis. Additionally, a spindle matrix has long been proposed to assist this process, but its nature has remained elusive. By combining live-cell imaging with laser microsurgery, fluorescence recovery after photobleaching, and fluorescence correlation spectroscopy in Drosophila melanogaster S2 cells, we uncovered a microtubule-independent mechanism that underlies the accumulation of molecules in the spindle region. This mechanism relies on a membranous system surrounding the mitotic spindle that defines an organelle-exclusion zone that is conserved in human cells. Supported by mathematical modeling, we demonstrate that organelle exclusion by a membrane system causes spatio-temporal differences in molecular crowding states that are sufficient to drive accumulation of mitotic regulators, such as Mad2 and Megator/Tpr, as well as soluble tubulin, in the spindle region. This membranous "spindle envelope" confined spindle assembly, and its mechanical disruption compromised faithful chromosome segregation. Thus, cytoplasmic compartmentalization persists during early mitosis to promote spindle assembly and function.

  17. Timely Endocytosis of Cytokinetic Enzymes Prevents Premature Spindle Breakage during Mitotic Exit.

    Directory of Open Access Journals (Sweden)

    Cheen Fei Chin

    2016-07-01

    Full Text Available Cytokinesis requires the spatio-temporal coordination of membrane deposition and primary septum (PS formation at the division site to drive acto-myosin ring (AMR constriction. It has been demonstrated that AMR constriction invariably occurs only after the mitotic spindle disassembly. It has also been established that Chitin Synthase II (Chs2p neck localization precedes mitotic spindle disassembly during mitotic exit. As AMR constriction depends upon PS formation, the question arises as to how chitin deposition is regulated so as to prevent premature AMR constriction and mitotic spindle breakage. In this study, we propose that cells regulate the coordination between spindle disassembly and AMR constriction via timely endocytosis of cytokinetic enzymes, Chs2p, Chs3p, and Fks1p. Inhibition of endocytosis leads to over accumulation of cytokinetic enzymes during mitotic exit, which accelerates the constriction of the AMR, and causes spindle breakage that eventually could contribute to monopolar spindle formation in the subsequent round of cell division. Intriguingly, the mitotic spindle breakage observed in endocytosis mutants can be rescued either by deleting or inhibiting the activities of, CHS2, CHS3 and FKS1, which are involved in septum formation. The findings from our study highlight the importance of timely endocytosis of cytokinetic enzymes at the division site in safeguarding mitotic spindle integrity during mitotic exit.

  18. Left Supraclavicular Spindle Cell Lipoma

    OpenAIRE

    Oladejo Olaleye; Bertram Fu; Ram Moorthy; Charles Lawson; Myles Black; David Mitchell

    2010-01-01

    Background. Spindle cell lipoma (SCL) is a benign lipomatous tumour, typically occurring in the posterior neck, shoulder or upper back of elderly males. They compose of fat, CD34 positive spindle cells, and ropey collagen on a myxoid matrix. This case highlights a rare presentation of SCL and the need for pre-operative diagnosis. Case Report. A 63-year-old gentleman presented with a pre-existing left supraclavicular mass that had recently increased in size. FNA and CT Scans were performed and...

  19. Slipping past the spindle assembly checkpoint.

    Science.gov (United States)

    Subramanian, Radhika; Kapoor, Tarun M

    2013-11-01

    Error-free genome segregation depends on the spindle assembly checkpoint (SAC), a signalling network that delays anaphase onset until chromosomes have established proper spindle attachments. Three reports now quantitatively examine the sensitivity and robustness of the SAC response.

  20. Autoassociative MLP in sleep spindle detection.

    Science.gov (United States)

    Huupponen, E; Värri, A; Himanen, S L; Hasan, J; Lehtokangas, M; Saarinen, J

    2000-06-01

    Spindles are one of the most important short-lasting waveforms in sleep EEG. They are the hallmarks of the so-called Stage 2 sleep. Visual spindle scoring is a tedious workload, since there are often a thousand spindles in one all-night recording of some 8 hr. Automated methods for spindle detection typically use some form of fixed spindle amplitude threshold, which is poor with respect to inter-subject variability. In this work a spindle detection system allowing spindle detection without an amplitude threshold was developed. This system can be used for automatic decision making of whether or not a sleep spindle is present in the EEG at a certain point of time. An Autoassociative Multilayer Perceptron (A-MLP) network was employed for the decision making. A novel training procedure was developed to remove inconsistencies from the training data, which was found to improve the system performance significantly.

  1. Spindle formation, chromosome segregation and the spindle checkpoint in mammalian oocytes and susceptibility to meiotic error.

    Science.gov (United States)

    Vogt, E; Kirsch-Volders, M; Parry, J; Eichenlaub-Ritter, U

    2008-03-12

    The spindle assembly checkpoint (SAC) monitors attachment to microtubules and tension on chromosomes in mitosis and meiosis. It represents a surveillance mechanism that halts cells in M-phase in the presence of unattached chromosomes, associated with accumulation of checkpoint components, in particular, Mad2, at the kinetochores. A complex between the anaphase promoting factor/cylosome (APC/C), its accessory protein Cdc20 and proteins of the SAC renders APC/C inactive, usually until all chromosomes are properly assembled at the spindle equator (chromosome congression) and under tension from spindle fibres. Upon release from the SAC the APC/C can target proteins like cyclin B and securin for degradation by the proteasome. Securin degradation causes activation of separase proteolytic enzyme, and in mitosis cleavage of cohesin proteins at the centromeres and arms of sister chromatids. In meiosis I only the cohesin proteins at the sister chromatid arms are cleaved. This requires meiosis specific components and tight regulation by kinase and phosphatase activities. There is no S-phase between meiotic divisions. Second meiosis resembles mitosis. Mammalian oocytes arrest constitutively at metaphase II in presence of aligned chromosomes, which is due to the activity of the cytostatic factor (CSF). The SAC has been identified in spermatogenesis and oogenesis, but gender-differences may contribute to sex-specific differential responses to aneugens. The age-related reduction in expression of components of the SAC in mammalian oocytes may act synergistically with spindle and other cell organelles' dysfunction, and a partial loss of cohesion between sister chromatids to predispose oocytes to errors in chromosome segregation. This might affect dose-response to aneugens. In view of the tendency to have children at advanced maternal ages it appears relevant to pursue studies on consequences of ageing on the susceptibility of human oocytes to the induction of meiotic error by

  2. Cardiac spindle cell hemangioma: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ju Young; Lee, In Jae; Min, Kwang Sun; Jeon, Eui Yong; Lee, Yul; Bae, Sang Hoon [Hallym University College of Medicine, Anyang (Korea, Republic of)

    2007-04-15

    Spindle cell hemangioma is an uncommon vascular lesion histologically resembling a cavernous hemangioma and Kaposi's sarcoma with a predilection for the extremities. There are no radiologic reports concerning cardiac spindle cell hemangioma in the current literature. We report here a case of cardiac spindle cell hemangioma.

  3. Samurai sword sets spindle size.

    Science.gov (United States)

    Reber, Simone; Hyman, Anthony A

    2011-12-09

    Although the parts list is nearly complete for many cellular structures, mechanisms that control their size remain poorly understood. Loughlin and colleagues now show that phosphorylation of a single residue of katanin, a microtubule-severing protein, largely accounts for the difference in spindle length between two closely related frogs.

  4. Left supraclavicular spindle cell lipoma.

    Science.gov (United States)

    Olaleye, Oladejo; Fu, Bertram; Moorthy, Ram; Lawson, Charles; Black, Myles; Mitchell, David

    2010-01-01

    Background. Spindle cell lipoma (SCL) is a benign lipomatous tumour, typically occurring in the posterior neck, shoulder or upper back of elderly males. They compose of fat, CD34 positive spindle cells, and ropey collagen on a myxoid matrix. This case highlights a rare presentation of SCL and the need for pre-operative diagnosis. Case Report. A 63-year-old gentleman presented with a pre-existing left supraclavicular mass that had recently increased in size. FNA and CT Scans were performed and results discussed in the mutidisciplinary team meeting. Excisional biopsy was recommended. Radiology. CT neck showed a left supraclavicular mass of fatty density with fine internal septations. A low-grade liposarcoma could not be excluded. Histopathology. FNA was indeterminate. Histology of specimen showed bland spindle cells with no evidence of malignancy. Immuno-histochemistry showed SCL with CD34 positivity and negative staining on CDK4 and p16. Management. Excision biopsy of the mass was performed which was technically difficult as the mass invaginated around the brachial plexus. The patient recovered well post-operatively with no neurological deficits. Conclusion. Spindle cell lipoma is a rare benign tumour and a pre-operative diagnosis based on the clinical context, imaging and immuno-histochemistry is crucial to management.

  5. Theory of meiotic spindle assembly

    Science.gov (United States)

    Furthauer, Sebastian; Foster, Peter; Needleman, Daniel; Shelley, Michael

    2016-11-01

    The meiotic spindle is a biological structure that self assembles from the intracellular medium to separate chromosomes during meiosis. It consists of filamentous microtubule (MT) proteins that interact through the fluid in which they are suspended and via the associated molecules that orchestrate their behavior. We aim to understand how the interplay between fluid medium, MTs, and regulatory proteins allows this material to self-organize into the spindle's highly stereotyped shape. To this end we develop a continuum model that treats the spindle as an active liquid crystal with MT turnover. In this active material, molecular motors, such as dyneins which collect MT minus ends and kinesins which slide MTs past each other, generate active fluid and material stresses. Moreover nucleator proteins that are advected with and transported along MTs control the nucleation and depolymerization of MTs. This theory captures the growth process of meiotic spindles, their shapes, and the essential features of many perturbation experiments. It thus provides a framework to think about the physics of this complex biological suspension.

  6. The coordination of centromere replication, spindle formation, and kinetochore-microtubule interaction in budding yeast.

    Directory of Open Access Journals (Sweden)

    Hong Liu

    2008-11-01

    Full Text Available The kinetochore is a protein complex that assembles on centromeric DNA to mediate chromosome-microtubule interaction. Most eukaryotic cells form the spindle and establish kinetochore-microtubule interaction during mitosis, but budding yeast cells finish these processes in S-phase. It has long been noticed that the S-phase spindle in budding yeast is shorter than that in metaphase, but the biological significance of this short S-phase spindle structure remains unclear. We addressed this issue by using ask1-3, a temperature-sensitive kinetochore mutant that exhibits partially elongated spindles at permissive temperature in the presence of hydroxyurea (HU, a DNA synthesis inhibitor. After exposure to and removal of HU, ask1-3 cells show a delayed anaphase entry. This delay depends on the spindle checkpoint, which monitors kinetochore-microtubule interaction defects. Overproduction of microtubule-associated protein Ase1 or Cin8 also induces spindle elongation in HU-arrested cells. The spindle checkpoint-dependent anaphase entry delay is also observed after ASE1 or CIN8 overexpression in HU-arrested cells. Therefore, the shorter spindle in S-phase cells is likely to facilitate proper chromosome-microtubule interaction.

  7. Drive-train condition monitoring for offshore wind and tidal turbines

    DEFF Research Database (Denmark)

    Roshanmanesh, Sanaz; Hayati, Farzad; Kappatos, Vassilios

    Offshore wind and tidal turbines are complex systems consisting of several different components and subsystems. One of the most important components is the drive-train. Gearboxes in geared designs are designed to operate for the entire lifetime of a wind or tidal turbine or the equivalent of 25 y...

  8. Statistical analysis of sleep spindle occurrences.

    Directory of Open Access Journals (Sweden)

    Dagmara Panas

    Full Text Available Spindles - a hallmark of stage II sleep - are a transient oscillatory phenomenon in the EEG believed to reflect thalamocortical activity contributing to unresponsiveness during sleep. Currently spindles are often classified into two classes: fast spindles, with a frequency of around 14 Hz, occurring in the centro-parietal region; and slow spindles, with a frequency of around 12 Hz, prevalent in the frontal region. Here we aim to establish whether the spindle generation process also exhibits spatial heterogeneity. Electroencephalographic recordings from 20 subjects were automatically scanned to detect spindles and the time occurrences of spindles were used for statistical analysis. Gamma distribution parameters were fit to each inter-spindle interval distribution, and a modified Wald-Wolfowitz lag-1 correlation test was applied. Results indicate that not all spindles are generated by the same statistical process, but this dissociation is not spindle-type specific. Although this dissociation is not topographically specific, a single generator for all spindle types appears unlikely.

  9. Spindle Bursts in Neonatal Rat Cerebral Cortex

    Directory of Open Access Journals (Sweden)

    Jenq-Wei Yang

    2016-01-01

    Full Text Available Spontaneous and sensory evoked spindle bursts represent a functional hallmark of the developing cerebral cortex in vitro and in vivo. They have been observed in various neocortical areas of numerous species, including newborn rodents and preterm human infants. Spindle bursts are generated in complex neocortical-subcortical circuits involving in many cases the participation of motor brain regions. Together with early gamma oscillations, spindle bursts synchronize the activity of a local neuronal network organized in a cortical column. Disturbances in spindle burst activity during corticogenesis may contribute to disorders in cortical architecture and in the activity-dependent control of programmed cell death. In this review we discuss (i the functional properties of spindle bursts, (ii the mechanisms underlying their generation, (iii the synchronous patterns and cortical networks associated with spindle bursts, and (iv the physiological and pathophysiological role of spindle bursts during early cortical development.

  10. Spindle Bursts in Neonatal Rat Cerebral Cortex.

    Science.gov (United States)

    Yang, Jenq-Wei; Reyes-Puerta, Vicente; Kilb, Werner; Luhmann, Heiko J

    2016-01-01

    Spontaneous and sensory evoked spindle bursts represent a functional hallmark of the developing cerebral cortex in vitro and in vivo. They have been observed in various neocortical areas of numerous species, including newborn rodents and preterm human infants. Spindle bursts are generated in complex neocortical-subcortical circuits involving in many cases the participation of motor brain regions. Together with early gamma oscillations, spindle bursts synchronize the activity of a local neuronal network organized in a cortical column. Disturbances in spindle burst activity during corticogenesis may contribute to disorders in cortical architecture and in the activity-dependent control of programmed cell death. In this review we discuss (i) the functional properties of spindle bursts, (ii) the mechanisms underlying their generation, (iii) the synchronous patterns and cortical networks associated with spindle bursts, and (iv) the physiological and pathophysiological role of spindle bursts during early cortical development.

  11. Phase transition of spindle-associated protein regulate spindle apparatus assembly.

    Science.gov (United States)

    Jiang, Hao; Wang, Shusheng; Huang, Yuejia; He, Xiaonan; Cui, Honggang; Zhu, Xueliang; Zheng, Yixian

    2015-09-24

    Spindle assembly required during mitosis depends on microtubule polymerization. We demonstrate that the evolutionarily conserved low-complexity protein, BuGZ, undergoes phase transition or coacervation to promote assembly of both spindles and their associated components. BuGZ forms temperature-dependent liquid droplets alone or on microtubules in physiological buffers. Coacervation in vitro or in spindle and spindle matrix depends on hydrophobic residues in BuGZ. BuGZ coacervation and its binding to microtubules and tubulin are required to promote assembly of spindle and spindle matrix in Xenopus egg extract and in mammalian cells. Since several previously identified spindle-associated components also contain low-complexity regions, we propose that coacervating proteins may be a hallmark of proteins that comprise a spindle matrix that functions to promote assembly of spindles by concentrating its building blocks.

  12. MINITYPE MACHINING SYSTEM FOR DIAMOND LAPPING & POLISHING BY USING BRUSHLESS DIRECT CURRENT MOTOR AS PRECISE SPINDLE

    Institute of Scientific and Technical Information of China (English)

    FU Huinan; CHEN Dongsheng; ZHAO Yong; LIN Binquan

    2008-01-01

    A minitype precise spindle system which can machine precisely and stably in the process of diamond lapping and polishing is designed. In such minitype spindle system, the brushless DC spindle motor is used to drive the lapping finish table, which is built with fluid dynamic bearings. Some measures have been taken to make the lapping system dynamic balance, and a servo controller which can adjust the speed of motor from 1 200 r/min to 5 400 r/min is designed. Experiments show that the spindle system is reliable and stable for diamond polishing, and the detection results by atomic force microscope(AFM) show that the surfaces of diamond edge's Ra is 6.725 nm and whole diamond average Ra is 3.25 nm.

  13. Mitotic rounding alters cell geometry to ensure efficient bipolar spindle formation.

    Science.gov (United States)

    Lancaster, Oscar M; Le Berre, Maël; Dimitracopoulos, Andrea; Bonazzi, Daria; Zlotek-Zlotkiewicz, Ewa; Picone, Remigio; Duke, Thomas; Piel, Matthieu; Baum, Buzz

    2013-05-13

    Accurate animal cell division requires precise coordination of changes in the structure of the microtubule-based spindle and the actin-based cell cortex. Here, we use a series of perturbation experiments to dissect the relative roles of actin, cortical mechanics, and cell shape in spindle formation. We find that, whereas the actin cortex is largely dispensable for rounding and timely mitotic progression in isolated cells, it is needed to drive rounding to enable unperturbed spindle morphogenesis under conditions of confinement. Using different methods to limit mitotic cell height, we show that a failure to round up causes defects in spindle assembly, pole splitting, and a delay in mitotic progression. These defects can be rescued by increasing microtubule lengths and therefore appear to be a direct consequence of the limited reach of mitotic centrosome-nucleated microtubules. These findings help to explain why most animal cells round up as they enter mitosis.

  14. Fault-diagnosis applications. Model-based condition monitoring. Acutators, drives, machinery, plants, sensors, and fault-tolerant systems

    Energy Technology Data Exchange (ETDEWEB)

    Isermann, Rolf [Technische Univ. Darmstadt (DE). Inst. fuer Automatisierungstechnik (IAT)

    2011-07-01

    Supervision, condition-monitoring, fault detection, fault diagnosis and fault management play an increasing role for technical processes and vehicles in order to improve reliability, availability, maintenance and lifetime. For safety-related processes fault-tolerant systems with redundancy are required in order to reach comprehensive system integrity. This book is a sequel of the book ''Fault-Diagnosis Systems'' published in 2006, where the basic methods were described. After a short introduction into fault-detection and fault-diagnosis methods the book shows how these methods can be applied for a selection of 20 real technical components and processes as examples, such as: Electrical drives (DC, AC) Electrical actuators Fluidic actuators (hydraulic, pneumatic) Centrifugal and reciprocating pumps Pipelines (leak detection) Industrial robots Machine tools (main and feed drive, drilling, milling, grinding) Heat exchangers Also realized fault-tolerant systems for electrical drives, actuators and sensors are presented. The book describes why and how the various signal-model-based and process-model-based methods were applied and which experimental results could be achieved. In several cases a combination of different methods was most successful. The book is dedicated to graduate students of electrical, mechanical, chemical engineering and computer science and for engineers. (orig.)

  15. Possibilities of improving exactness of engineering-geology research results by the monitoring of the driving process

    Directory of Open Access Journals (Sweden)

    Krúpa Víazoslav

    2000-09-01

    Full Text Available In detail engineering-geology, hydrology and geotechnical research at driving a part of exploration gallery Branisko was fulfilled by results of computer application for the computing monitoring information of TBM driving process according to different viewpoints. A high density of the gathered information made it possible to determine a methodics for the classification of strength rock mass properties, to identify the influence of the rock mass damage and to apply some methods of rock classification. In the article are presented some results of the RQD coefficient determination, coefficient of burden by Terzag’s and the rock classification according to Protodjakonov. For each geologic entirety defined by the research, achieved results are compared with the engineering-geology research results. In the contribution, in a table form are elaborated values of four methods of determination: the RQD coefficient, the rock burden coefficient, and the Terzaghys and Protodjakonov methods of rock classification. For the 42 geologic sections of the total length of 2340m that was driven by a full profile driving machine Wirth TB-II-330H/M (geologic sections were defined by in detail geological, engineering geological, hydrological and geotechnical exploration elaborated by employees of INGEO, a.s., Žilina, and were compared to the results of the rock categorization according to the classification classes defined by Deere, Terzaghi and Protodjakonov. The classification of the rocks into categories was based on the arithmetic average of defined values. The values of deviation or dispersion or coefficient of variation were not considered. From the graphical result presentation of the methods for the chosen 500 m section of the exploratory gallery of the motorway tunnel Branisko (that are presented by the values gained from the computer monitoring process, it results, that in geological units it is possible to determine local changes of rock properties. These

  16. Mechanical design principles of a mitotic spindle.

    Science.gov (United States)

    Ward, Jonathan J; Roque, Hélio; Antony, Claude; Nédélec, François

    2014-12-18

    An organised spindle is crucial to the fidelity of chromosome segregation, but the relationship between spindle structure and function is not well understood in any cell type. The anaphase B spindle in fission yeast has a slender morphology and must elongate against compressive forces. This 'pushing' mode of chromosome transport renders the spindle susceptible to breakage, as observed in cells with a variety of defects. Here we perform electron tomographic analyses of the spindle, which suggest that it organises a limited supply of structural components to increase its compressive strength. Structural integrity is maintained throughout the spindle's fourfold elongation by organising microtubules into a rigid transverse array, preserving correct microtubule number and dynamically rescaling microtubule length.

  17. Spindle checkpoint proteins and chromosome-microtubule attachment in budding yeast.

    Science.gov (United States)

    Gillett, Emily S; Espelin, Christopher W; Sorger, Peter K

    2004-02-16

    Accurate chromosome segregation depends on precise regulation of mitosis by the spindle checkpoint. This checkpoint monitors the status of kinetochore-microtubule attachment and delays the metaphase to anaphase transition until all kinetochores have formed stable bipolar connections to the mitotic spindle. Components of the spindle checkpoint include the mitotic arrest defective (MAD) genes MAD1-3, and the budding uninhibited by benzimidazole (BUB) genes BUB1 and BUB3. In animal cells, all known spindle checkpoint proteins are recruited to kinetochores during normal mitoses. In contrast, we show that whereas Saccharomyces cerevisiae Bub1p and Bub3p are bound to kinetochores early in mitosis as part of the normal cell cycle, Mad1p and Mad2p are kinetochore bound only in the presence of spindle damage or kinetochore lesions that interfere with chromosome-microtubule attachment. Moreover, although Mad1p and Mad2p perform essential mitotic functions during every division cycle in mammalian cells, they are required in budding yeast only when mitosis goes awry. We propose that differences in the behavior of spindle checkpoint proteins in animal cells and budding yeast result primarily from evolutionary divergence in spindle assembly pathways. Copyright The Rockefeller University Press

  18. Cell cycle regulation of central spindle assembly.

    Science.gov (United States)

    Mishima, Masanori; Pavicic, Visnja; Grüneberg, Ulrike; Nigg, Erich A; Glotzer, Michael

    2004-08-19

    The bipolar mitotic spindle is responsible for segregating sister chromatids at anaphase. Microtubule motor proteins generate spindle bipolarity and enable the spindle to perform mechanical work. A major change in spindle architecture occurs at anaphase onset when central spindle assembly begins. This structure regulates the initiation of cytokinesis and is essential for its completion. Central spindle assembly requires the centralspindlin complex composed of the Caenorhabditis elegans ZEN-4 (mammalian orthologue MKLP1) kinesin-like protein and the Rho family GAP CYK-4 (MgcRacGAP). Here we describe a regulatory mechanism that controls the timing of central spindle assembly. The mitotic kinase Cdk1/cyclin B phosphorylates the motor domain of ZEN-4 on a conserved site within a basic amino-terminal extension characteristic of the MKLP1 subfamily. Phosphorylation by Cdk1 diminishes the motor activity of ZEN-4 by reducing its affinity for microtubules. Preventing Cdk1 phosphorylation of ZEN-4/MKLP1 causes enhanced metaphase spindle localization and defects in chromosome segregation. Thus, phosphoregulation of the motor domain of MKLP1 kinesin ensures that central spindle assembly occurs at the appropriate time in the cell cycle and maintains genomic stability.

  19. Beam Tests of a Prototype Stripline Beam Position Monitoring System for the Drive Beam of the CLIC Two-beam Module at CTF3

    CERN Document Server

    Benot-Morell, Alfonso; Nappa, Jean-Marc; Vilalte, Sebastien; Wendt, Manfred

    2016-01-01

    In collaboration with LAPP and IFIC, two units of a prototype stripline Beam Position Monitor (BPM) for the CLIC Drive Beam (DB), and its associated readout electronics have been successfully installed and tested in the Two-Beam-Module (TBM) at the CLIC Test Facility 3 (CTF3) at CERN. This paper gives a short overview of the BPM system and presents the performance measured under different Drive Beam configurations.

  20. Sensorless Monitoring of a Motor-Drive Machanical System Based on Adaptive Signal Decomposition

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-feng; JIAO Li-cheng

    2006-01-01

    A method for estimating current harmonics of an induction motor is introduced which is used for sensorless monitoring of a mechanical system driven by the motor. The method is based on an adaptive signal representation and is proposed to extract weak harmonics from a noisy current signal, especially in the presence of additive interference caused by transient modulation waves. As an application, a rotor unbalance experiment of rotating machinery driven by an induction motor is carried out. The result shows that the eccentricity harmonic magnitude of a current signal obtained by the method represents the rotor unbalance conditions sensitively. Vibration analysis is used to validate the proposed method.

  1. Investigation of Data Fusion Applied to Health Monitoring of Wind Turbine Drive train Components

    Science.gov (United States)

    Dempsey, Paula J.; Sheng, Shuangwen

    2011-01-01

    The research described was performed on diagnostic tools used to detect damage to dynamic mechanical components in a wind turbine gearbox. Different monitoring technologies were evaluated by collecting vibration and oil debris data from tests performed on a "healthy" gearbox and a damaged gearbox in a dynamometer test stand located at the National Renewable Energy Laboratory. The damaged gearbox tested was removed from the field after experiencing component damage due to two losses of oil events and was retested under controlled conditions in the dynamometer test stand. Preliminary results indicate oil debris and vibration can be integrated to assess the health of the wind turbine gearbox.

  2. Dynamic spindle reflexes and the rigidity of Parkinsonism.

    Science.gov (United States)

    McLellan, D L

    1973-06-01

    The effects of stimulating the reflex arc from dynamic spindle endings were examined in patients with the rigidity of Parkinsonism and in control subjects. The arc was activated phasically by a tendon tap and by electrical stimulation in 15 patients. The effect of reinforcement by Jendrassik's manoeuvre was observed. The response to phasic activation indicated central facilitation of the reflex loop in the patients with Parkinsonism, with a concurrent decrease in fusimotor drive to dynamic spindles. These abnormalities could not be correlated with the severity of the patients' rigidity, and they did not alter when the rigidity was reduced by levodopa. The effect of activating dynamic spindle endings tonically by vibration at 50 Hz was also examined. The reflex contraction of the biceps and triceps muscles in response to vibration was found to be increased in 24 patients with rigidity compared with 24 control subjects. Patients with severe rigidity developed a more powerful contraction in response to vibration than patients with mild rigidity. The response to vibration was reduced by treatment with levodopa but the amount of this reduction could not be correlated with changes in the patients' rigidity.

  3. Left Supraclavicular Spindle Cell Lipoma

    Directory of Open Access Journals (Sweden)

    Oladejo Olaleye

    2010-01-01

    This case highlights a rare presentation of SCL and the need for pre-operative diagnosis. Case Report. A 63-year-old gentleman presented with a pre-existing left supraclavicular mass that had recently increased in size. FNA and CT Scans were performed and results discussed in the mutidisciplinary team meeting. Excisional biopsy was recommended. Radiology. CT neck showed a left supraclavicular mass of fatty density with fine internal septations. A low-grade liposarcoma could not be excluded. Histopathology. FNA was indeterminate. Histology of specimen showed bland spindle cells with no evidence of malignancy. Immuno-histochemistry showed SCL with CD34 positivity and negative staining on CDK4 and p16. Management. Excision biopsy of the mass was performed which was technically difficult as the mass invaginated around the brachial plexus. The patient recovered well post-operatively with no neurological deficits. Conclusion. Spindle cell lipoma is a rare benign tumour and a pre-operative diagnosis based on the clinical context, imaging and immuno-histochemistry is crucial to management.

  4. Optimization Study of the Efficient Spindle

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the field of yam dyeing, the most generally employed method is a type of package dyeing which uses a package of cheese stacked on a spindle made of a perforated robe. Spindles up to now, have been designed without considering the characteristics of dyeing liquid, focusing only on the geometric configuration which cause many problems such as lack of level dyeing. To improve the level dyeing and find the appropriate spindle configuration for the most effective dyeing process, this study examines the spindle flow-field in detail, using a computational method. Flow characteristics inside the spindle have been investigated with varying in porosity, porous diameter and the velocity of the flow. The results show that the total pressure of the flow through the spindle is used to overcom e body force. The characteristics of the flow from the porous spindle could also be observed. Based on the results from this study, an effective spindle configuration for level-dyeing has been proposed.

  5. Retropharyngeal spindle cell/plemorphic lipoma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Kyung; Hwang, Seung Bae; Chung, Gyung Ho; Hong, Ki Hwang; Jang, Kyu Yun [Chonbuk National University Medical School and Hospital, Jeonju (Korea, Republic of)

    2013-06-15

    Spindle cell/pleomorphic lipoma is an uncommon benign adipose tissue tumor most frequently arising from the subcutaneous tissue of the back, shoulder, head and neck, and extremities. The deep cervical spaces are the rarely affected locations. Herein we report on the imaging findings of spindle cell/pleomorphic lipoma involving the retropharyngeal space in an elderly woman.

  6. Nap sleep spindle correlates of intelligence

    NARCIS (Netherlands)

    Ujma, P.P.; Bodizs, R.; Gombos, F.; Stintzing, J.; Konrad, B.N.; Genzel, L.; Steiger, A.; Dresler, M.

    2015-01-01

    Sleep spindles are thalamocortical oscillations in non-rapid eye movement (NREM) sleep, that play an important role in sleep-related neuroplasticity and offline information processing. Several studies with full-night sleep recordings have reported a positive association between sleep spindles and fl

  7. The chromosomal passenger complex and the spindle assembly checkpoint: kinetochore-microtubule error correction and beyond

    Directory of Open Access Journals (Sweden)

    Maia André F

    2008-05-01

    Full Text Available Abstract During mitosis, correct bipolar chromosome attachment to the mitotic spindle is an essential prerequisite for the equal segregation of chromosomes. The spindle assembly checkpoint can prevent chromosome segregation as long as not all chromosome pairs have obtained bipolar attachment to the spindle. The chromosomal passenger complex plays a crucial role during chromosome alignment by correcting faulty chromosome-spindle interactions (e.g. attachments that do not generate tension. In the process of doing so, the chromosomal passenger complex generates unattached chromosomes, a specific situation that is known to promote checkpoint activity. However, several studies have implicated an additional, more direct role for the chromosomal passenger complex in enforcing the mitotic arrest imposed by the spindle assembly checkpoint. In this review, we discuss the different roles played by the chromosomal passenger complex in ensuring proper mitotic checkpoint function. Additionally, we discuss the possibility that besides monitoring the presence of unattached kinetochores, the spindle assembly checkpoint may also be capable of responding to chromosome-microtubule interactions that do not generate tension and we propose experimental set-ups to study this.

  8. A curved edge diffraction-utilized displacement sensor for spindle metrology

    Science.gov (United States)

    Lee, ChaBum; Mahajan, Satish M.; Zhao, Rui; Jeon, Seongkyul

    2016-07-01

    This paper presents a new dimensional metrological sensing principle for a curved surface based on curved edge diffraction. Spindle error measurement technology utilizes a cylindrical or spherical target artifact attached to the spindle with non-contact sensors, typically a capacitive sensor (CS) or an eddy current sensor, pointed at the artifact. However, these sensors are designed for flat surface measurement. Therefore, measuring a target with a curved surface causes error. This is due to electric fields behaving differently between a flat and curved surface than between two flat surfaces. In this study, a laser is positioned incident to the cylindrical surface of the spindle, and a photodetector collects the total field produced by the diffraction around the target surface. The proposed sensor was compared with a CS within a range of 500 μm. The discrepancy between the proposed sensor and CS was 0.017% of the full range. Its sensing performance showed a resolution of 14 nm and a drift of less than 10 nm for 7 min of operation. This sensor was also used to measure dynamic characteristics of the spindle system (natural frequency 181.8 Hz, damping ratio 0.042) and spindle runout (22.0 μm at 2000 rpm). The combined standard uncertainty was estimated as 85.9 nm under current experiment conditions. It is anticipated that this measurement technique allows for in situ health monitoring of a precision spindle system in an accurate, convenient, and low cost manner.

  9. The chromosomal passenger complex and the spindle assembly checkpoint: kinetochore-microtubule error correction and beyond.

    Science.gov (United States)

    Vader, Gerben; Maia, André F; Lens, Susanne Ma

    2008-05-28

    During mitosis, correct bipolar chromosome attachment to the mitotic spindle is an essential prerequisite for the equal segregation of chromosomes. The spindle assembly checkpoint can prevent chromosome segregation as long as not all chromosome pairs have obtained bipolar attachment to the spindle. The chromosomal passenger complex plays a crucial role during chromosome alignment by correcting faulty chromosome-spindle interactions (e.g. attachments that do not generate tension). In the process of doing so, the chromosomal passenger complex generates unattached chromosomes, a specific situation that is known to promote checkpoint activity. However, several studies have implicated an additional, more direct role for the chromosomal passenger complex in enforcing the mitotic arrest imposed by the spindle assembly checkpoint. In this review, we discuss the different roles played by the chromosomal passenger complex in ensuring proper mitotic checkpoint function. Additionally, we discuss the possibility that besides monitoring the presence of unattached kinetochores, the spindle assembly checkpoint may also be capable of responding to chromosome-microtubule interactions that do not generate tension and we propose experimental set-ups to study this.

  10. A curved edge diffraction-utilized displacement sensor for spindle metrology.

    Science.gov (United States)

    Lee, ChaBum; Mahajan, Satish M; Zhao, Rui; Jeon, Seongkyul

    2016-07-01

    This paper presents a new dimensional metrological sensing principle for a curved surface based on curved edge diffraction. Spindle error measurement technology utilizes a cylindrical or spherical target artifact attached to the spindle with non-contact sensors, typically a capacitive sensor (CS) or an eddy current sensor, pointed at the artifact. However, these sensors are designed for flat surface measurement. Therefore, measuring a target with a curved surface causes error. This is due to electric fields behaving differently between a flat and curved surface than between two flat surfaces. In this study, a laser is positioned incident to the cylindrical surface of the spindle, and a photodetector collects the total field produced by the diffraction around the target surface. The proposed sensor was compared with a CS within a range of 500 μm. The discrepancy between the proposed sensor and CS was 0.017% of the full range. Its sensing performance showed a resolution of 14 nm and a drift of less than 10 nm for 7 min of operation. This sensor was also used to measure dynamic characteristics of the spindle system (natural frequency 181.8 Hz, damping ratio 0.042) and spindle runout (22.0 μm at 2000 rpm). The combined standard uncertainty was estimated as 85.9 nm under current experiment conditions. It is anticipated that this measurement technique allows for in situ health monitoring of a precision spindle system in an accurate, convenient, and low cost manner.

  11. Measuring mitotic spindle dynamics in budding yeast

    Science.gov (United States)

    Plumb, Kemp

    In order to carry out its life cycle and produce viable progeny through cell division, a cell must successfully coordinate and execute a number of complex processes with high fidelity, in an environment dominated by thermal noise. One important example of such a process is the assembly and positioning of the mitotic spindle prior to chromosome segregation. The mitotic spindle is a modular structure composed of two spindle pole bodies, separated in space and spanned by filamentous proteins called microtubules, along which the genetic material of the cell is held. The spindle is responsible for alignment and subsequent segregation of chromosomes into two equal parts; proper spindle positioning and timing ensure that genetic material is appropriately divided amongst mother and daughter cells. In this thesis, I describe fluorescence confocal microscopy and automated image analysis algorithms, which I have used to observe and analyze the real space dynamics of the mitotic spindle in budding yeast. The software can locate structures in three spatial dimensions and track their movement in time. By selecting fluorescent proteins which specifically label the spindle poles and cell periphery, mitotic spindle dynamics have been measured in a coordinate system relevant to the cell division. I describe how I have characterised the accuracy and precision of the algorithms by simulating fluorescence data for both spindle poles and the budding yeast cell surface. In this thesis I also describe the construction of a microfluidic apparatus that allows for the measurement of long time-scale dynamics of individual cells and the development of a cell population. The tools developed in this thesis work will facilitate in-depth quantitative analysis of the non-equilibrium processes in living cells.

  12. Overview of condition monitoring and operation control of electric power conversion systems in direct-drive wind turbines under faults

    Science.gov (United States)

    Huang, Shoudao; Wu, Xuan; Liu, Xiao; Gao, Jian; He, Yunze

    2017-09-01

    Electric power conversion system (EPCS), which consists of a generator and power converter, is one of the most important subsystems in a direct-drive wind turbine (DD-WT). However, this component accounts for the most failures (approximately 60% of the total number) in the entire DD-WT system according to statistical data. To improve the reliability of EPCSs and reduce the operation and maintenance cost of DD-WTs, numerous researchers have studied condition monitoring (CM) and fault diagnostics (FD). Numerous CM and FD techniques, which have respective advantages and disadvantages, have emerged. This paper provides an overview of the CM, FD, and operation control of EPCSs in DD-WTs under faults. After introducing the functional principle and structure of EPCS, this survey discusses the common failures in wind generators and power converters; briefly reviewed CM and FD methods and operation control of these generators and power converters under faults; and discussed the grid voltage faults related to EPCSs in DD-WTs. These theories and their related technical concepts are systematically discussed. Finally, predicted development trends are presented. The paper provides a valuable reference for developing service quality evaluation methods and fault operation control systems to achieve high-performance and high-intelligence DD-WTs.

  13. Dynein light intermediate chains maintain spindle bipolarity by functioning in centriole cohesion.

    Science.gov (United States)

    Jones, Laura A; Villemant, Cécile; Starborg, Toby; Salter, Anna; Goddard, Georgina; Ruane, Peter; Woodman, Philip G; Papalopulu, Nancy; Woolner, Sarah; Allan, Victoria J

    2014-11-24

    Cytoplasmic dynein 1 (dynein) is a minus end-directed microtubule motor protein with many cellular functions, including during cell division. The role of the light intermediate chains (LICs; DYNC1LI1 and 2) within the complex is poorly understood. In this paper, we have used small interfering RNAs or morpholino oligonucleotides to deplete the LICs in human cell lines and Xenopus laevis early embryos to dissect the LICs' role in cell division. We show that although dynein lacking LICs drives microtubule gliding at normal rates, the LICs are required for the formation and maintenance of a bipolar spindle. Multipolar spindles with poles that contain single centrioles were formed in cells lacking LICs, indicating that they are needed for maintaining centrosome integrity. The formation of multipolar spindles via centrosome splitting after LIC depletion could be rescued by inhibiting Eg5. This suggests a novel role for the dynein complex, counteracted by Eg5, in the maintenance of centriole cohesion during mitosis.

  14. The CENP-A NAC/CAD kinetochore complex controls chromosome congression and spindle bipolarity.

    Science.gov (United States)

    McClelland, Sarah E; Borusu, Satyarebala; Amaro, Ana C; Winter, Jennifer R; Belwal, Mukta; McAinsh, Andrew D; Meraldi, Patrick

    2007-12-12

    Kinetochores are complex protein machines that link chromosomes to spindle microtubules and contain a structural core composed of two conserved protein-protein interaction networks: the well-characterized KMN (KNL1/MIND/NDC80) and the recently identified CENP-A NAC/CAD. Here we show that the CENP-A NAC/CAD subunits can be assigned to one of two different functional classes; depletion of Class I proteins (Mcm21R(CENP-O) and Fta1R(CENP-L)) causes a failure in bipolar spindle assembly. In contrast, depletion of Class II proteins (CENP-H, Chl4R(CENP-N), CENP-I and Sim4R(CENP-K)) prevents binding of Class I proteins and causes chromosome congression defects, but does not perturb spindle formation. Co-depletion of Class I and Class II proteins restores spindle bipolarity, suggesting that Class I proteins regulate or counteract the function of Class II proteins. We also demonstrate that CENP-A NAC/CAD and KMN regulate kinetochore-microtubule attachments independently, even though CENP-A NAC/CAD can modulate NDC80 levels at kinetochores. Based on our results, we propose that the cooperative action of CENP-A NAC/CAD subunits and the KMN network drives efficient chromosome segregation and bipolar spindle assembly during mitosis.

  15. Sensory-evoked and spontaneous gamma and spindle bursts in neonatal rat motor cortex.

    Science.gov (United States)

    An, Shuming; Kilb, Werner; Luhmann, Heiko J

    2014-08-13

    Self-generated neuronal activity originating from subcortical regions drives early spontaneous motor activity, which is a hallmark of the developing sensorimotor system. However, the neural activity patterns and role of primary motor cortex (M1) in these early movements are still unknown. Combining voltage-sensitive dye imaging (VSDI) with simultaneous extracellular multielectrode recordings in postnatal day 3 (P3)-P5 rat primary somatosensory cortex (S1) and M1 in vivo, we observed that tactile forepaw stimulation induced spindle bursts in S1 and gamma and spindle bursts in M1. Approximately 40% of the spontaneous gamma and spindle bursts in M1 were driven by early motor activity, whereas 23.7% of the M1 bursts triggered forepaw movements. Approximately 35% of the M1 bursts were uncorrelated to movements and these bursts had significantly fewer spikes and shorter burst duration. Focal electrical stimulation of layer V neurons in M1 mimicking physiologically relevant 40 Hz gamma or 10 Hz spindle burst activity reliably elicited forepaw movements. We conclude that M1 is already involved in somatosensory information processing during early development. M1 is mainly activated by tactile stimuli triggered by preceding spontaneous movements, which reach M1 via S1. Only a fraction of M1 activity transients trigger motor responses directly. We suggest that both spontaneously occurring and sensory-evoked gamma and spindle bursts in M1 contribute to the maturation of corticospinal and sensorimotor networks required for the refinement of sensorimotor coordination.

  16. Evaluation of an in-vehicle monitoring system (IVMS) to reduce risky driving behaviors in commercial drivers: Comparison of in-cab warning lights and supervisory coaching with videos of driving behavior.

    Science.gov (United States)

    Bell, Jennifer L; Taylor, Matthew A; Chen, Guang-Xiang; Kirk, Rachel D; Leatherman, Erin R

    2017-02-01

    Roadway incidents are the leading cause of work-related death in the United States. The objective of this research was to evaluate whether two types of feedback from a commercially available in-vehicle monitoring system (IVMS) would reduce the incidence of risky driving behaviors in drivers from two companies. IVMS were installed in 315 vehicles representing the industries of local truck transportation and oil and gas support operations, and data were collected over an approximate two-year period in intervention and control groups. In one period, intervention group drivers were given feedback from in-cab warning lights from an IVMS that indicated occurrence of harsh vehicle maneuvers. In another period, intervention group drivers viewed video recordings of their risky driving behaviors with supervisors, and were coached by supervisors on safe driving practices. Risky driving behaviors declined significantly more during the period with coaching plus instant feedback with lights in comparison to the period with lights-only feedback (ORadj=0.61 95% CI 0.43-0.86; Holm-adjusted p=0.035) and the control group (ORadj=0.52 95% CI 0.33-0.82; Holm-adjusted p=0.032). Lights-only feedback was not found to be significantly different than the control group's decline from baseline (ORadj=0.86 95% CI 0.51-1.43; Holm-adjusted p>0.05). The largest decline in the rate of risky driving behaviors occurred when feedback included both supervisory coaching and lights. Supervisory coaching is an effective form of feedback to improve driving habits in the workplace. The potential advantages and limitations of this IVMS-based intervention program are discussed. Published by Elsevier Ltd.

  17. Intrafusal muscle fibre types in frog spindles.

    Science.gov (United States)

    Diwan, F H; Ito, F

    1989-04-01

    Muscle spindles from bullfrog semitendinosus, iliofibularis and sartorius muscles were examined with light and electron microscopy. Four types of intrafusal muscle fibre were identified according to their diameter, central nucleation and reticular zone arrangement: a large nuclear bag fibre, a medium nuclear bag fibre, and two types of small nuclear chain fibres with and without a reticular zone, respectively. It is suggested that they are comparable to the nuclear bag1, bag2 and chain fibres in mammalian muscle spindles.

  18. Multi Satellites Monitoring of Land Use/Cover Change and Its Driving Forces in Kashgar Region, China

    Science.gov (United States)

    Maimaitiaili, Ayisulitan; Aji, xiaokaiti; Kondoh, Akihiko

    2016-04-01

    Multi Satellites Monitoring of Land Use/Cover Change and Its Driving Forces in Kashgar Region, China Ayisulitan Maimaitiaili1, Xiaokaiti Aji2 Akihiko Kondoh2 1Graduate School of Science, Chiba University, Japan 2Center for Environmental Remote Sensing, Chiba University The spatio-temporal changes of Land Use/Cover (LUCC) and its driving forces in Kashgar region, Xinjiang Province, China, are investigated by using satellite remote sensing and a geographical information system (GIS). Main goal of this paper is to quantify the drivers of LUCC. First, considering lack of the Land Cover (LC) map in whole study area, we produced LC map by using Landsat images. Land use information from Landsat data was collected using maximum likelihood classification method. Land use change was studied based on the change detection method of land use types. Second, because the snow provides a key water resources for stream flow, agricultural production and drinking water for sustaining large population in Kashgar region, snow cover are estimated by Spot Vegetation data. Normalized Difference Snow Index (NDSI) algorithm are applied to make snow cover map, which is used to screen the LUCC and climate change. The best agreement is found with threshold value of NDSI≥0.2 to generate multi-temporal snow cover and snowmelt maps. Third, driving forces are systematically identified by LC maps and statistical data such as climate and socio-economic data, regarding to i) the climate changes and ii) socioeconomic development that the spatial correlation among LUCC, snow cover change, climate and socioeconomic changes are quantified by using liner regression model and negative / positive trend analysis. Our results showed that water bodies, bare land and grass land have decreasing notably. By contrast, crop land and urban area have continually increasing significantly, which are dominated in study area. The area of snow/ice have fluctuated and has strong seasonal trends, total annual snow cover

  19. Regulation of mitotic spindle asymmetry by SUMO and the spindle-assembly checkpoint in yeast.

    Science.gov (United States)

    Leisner, Christian; Kammerer, Daniel; Denoth, Annina; Britschi, Mirjam; Barral, Yves; Liakopoulos, Dimitris

    2008-08-26

    During mitosis, the kinetochore microtubules capture and segregate chromosomes, and the astral microtubules position the spindle within the cell. Although the spindle is symmetric, proper positioning of the spindle in asymmetrically dividing cells generally correlates with the formation of morphologically and structurally distinct asters [1]. In budding yeast, the spindle-orientation proteins Kar9 and dynein decorate only one aster of the metaphase spindle and direct it toward the bud [2, 3]. The mechanisms controlling the distribution of Kar9 and dynein remain unclear. Here, we show that SUMO regulates astral-microtubule function in at least two ways. First, Kar9 was sumoylated in vivo. Sumoylation and Cdk1-dependent phosphorylation of Kar9 independently promoted Kar9 asymmetry on the spindle. Second, proper regulation of kinetochore function by SUMO was also required for Kar9 asymmetry. Indeed, activation of the spindle-assembly checkpoint (SAC) due to SUMO and kinetochore defects promoted symmetric redistribution of Kar9 in a Mad2-dependent manner. The control of Kar9 distribution by the SAC was independent of Kar9 sumoylation and phosphorylation. Together, our data reveal that three independent mechanisms contribute to Kar9 asymmetry: Cdk1-dependent phosphorylation, sumoylation, and SAC signaling. Hence, the two seemingly independent spindle domains, kinetochores and astral microtubules, function in a tightly coordinated fashion.

  20. The spindle protein CHICA mediates localization of the chromokinesin Kid to the mitotic spindle

    NARCIS (Netherlands)

    Santamaria, Anna; Nagel, Susanna; Sillje, Herman H W; Nigg, Erich A

    2008-01-01

    Microtubule-based motor proteins provide essential forces for bipolar organization of spindle microtubules and chromosome movement, prerequisites of chromosome segregation during the cell cycle. Here, we describe the functional characterization of a novel spindle protein, termed "CHICA," that was or

  1. New spindle morphogenesis model by Dynein,Nudel, and the spindle matrix

    Institute of Scientific and Technical Information of China (English)

    Wei-Lih Lee; Patricia Wadsworth

    2009-01-01

    @@ It is well established that the mi-totic spindle, the organeile responsible for chromosome segregation during mitosis, is built from microtubules, motor proteins, and associated struc-tural and regulatory molecules. More controversial is the existence and identity of non-microtubule spindle components, collectively referred to as the matrix.

  2. Purification of fluorescently labeled Saccharomyces cerevisiae Spindle Pole Bodies

    Science.gov (United States)

    Davis, Trisha N.

    2016-01-01

    Centrosomes are components of the mitotic spindle responsible for organizing microtubules and establishing a bipolar spindle for accurate chromosome segregation. In budding yeast, Saccharomyces cerevisiae, the centrosome is called the spindle pole body, a highly organized tri-laminar structure embedded in the nuclear envelope. Here we describe a detailed protocol for the purification of fluorescently labeled spindle pole bodes from S. cerevisiae. Spindle pole bodies are purified from yeast using a TAP-tag purification followed by velocity sedimentation. This highly reproducible TAP-tag purification method improves upon previous techniques and expands the scope of in vitro characterization of yeast spindle pole bodies. The genetic flexibility of this technique allows for the study of spindle pole body mutants as well as the study of spindle pole bodies during different stages of the cell cycle. The ease and reproducibility of the technique makes it possible to study spindle pole bodies using a variety of biochemical, biophysical, and microscopic techniques. PMID:27193850

  3. Sleep spindle density in narcolepsy.

    Science.gov (United States)

    Christensen, Julie Anja Engelhard; Nikolic, Miki; Hvidtfelt, Mathias; Kornum, Birgitte Rahbek; Jennum, Poul

    2017-06-01

    Patients with narcolepsy type 1 (NT1) show alterations in sleep stage transitions, rapid-eye-movement (REM) and non-REM sleep due to the loss of hypocretinergic signaling. However, the sleep microstructure has not yet been evaluated in these patients. We aimed to evaluate whether the sleep spindle (SS) density is altered in patients with NT1 compared to controls and patients with narcolepsy type 2 (NT2). All-night polysomnographic recordings from 28 NT1 patients, 19 NT2 patients, 20 controls (C) with narcolepsy-like symptoms, but with normal cerebrospinal fluid hypocretin levels and multiple sleep latency tests, and 18 healthy controls (HC) were included. Unspecified, slow, and fast SS were automatically detected, and SS densities were defined as number per minute and were computed across sleep stages and sleep cycles. The between-cycle trends of SS densities in N2 and NREM sleep were evaluated within and between groups. Between-group comparisons in sleep stages revealed no significant differences in any type of SS. Within-group analyses of the SS trends revealed significant decreasing trends for NT1, HC, and C between first and last sleep cycle. Between-group analyses of SS trends between first and last sleep cycle revealed that NT2 differ from NT1 patients in the unspecified SS density in NREM sleep, and from HC in the slow SS density in N2 sleep. SS activity is preserved in NT1, suggesting that the ascending neurons to thalamic activation of SS are not significantly affected by the hypocretinergic system. NT2 patients show an abnormal pattern of SS distribution. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Sleep Spindles as Facilitators of Memory Formation and Learning

    Directory of Open Access Journals (Sweden)

    Daniel Ulrich

    2016-01-01

    Full Text Available Over the past decades important progress has been made in understanding the mechanisms of sleep spindle generation. At the same time a physiological role of sleep spindles is starting to be revealed. Behavioural studies in humans and animals have found significant correlations between the recall performance in different learning tasks and the amount of sleep spindles in the intervening sleep. Concomitant neurophysiological experiments showed a close relationship between sleep spindles and other sleep related EEG rhythms as well as a relationship between sleep spindles and synaptic plasticity. Together, there is growing evidence from several disciplines in neuroscience for a participation of sleep spindles in memory formation and learning.

  5. A defect-driven diagnostic method for machine tool spindles.

    Science.gov (United States)

    Vogl, Gregory W; Donmez, M Alkan

    2015-01-01

    Simple vibration-based metrics are, in many cases, insufficient to diagnose machine tool spindle condition. These metrics couple defect-based motion with spindle dynamics; diagnostics should be defect-driven. A new method and spindle condition estimation device (SCED) were developed to acquire data and to separate system dynamics from defect geometry. Based on this method, a spindle condition metric relying only on defect geometry is proposed. Application of the SCED on various milling and turning spindles shows that the new approach is robust for diagnosing the machine tool spindle condition.

  6. Corticothalamic Feedback Controls Sleep Spindle Duration In Vivo

    Science.gov (United States)

    Bonjean, Maxime; Baker, Tanya; Lemieux, Maxime; Timofeev, Igor; Sejnowski, Terrence; Bazhenov, Maxim

    2011-01-01

    Spindle oscillations are commonly observed during stage two of non-REM sleep. During sleep spindles, the cerebral cortex and thalamus interact through feedback connections. Both initiation and termination of spindle oscillations are thought to originate in the thalamus, based on thalamic recordings and computational models, although some in vivo results suggest otherwise. Here, we have used computer modeling and in vivo multisite recordings from the cortex and the thalamus in cats to examine the involvement of the cortex in spindle oscillations. We found that although the propagation of spindles depended on synaptic interaction within the thalamus, the initiation and termination of spindle sequences critically involved corticothalamic influences. PMID:21697364

  7. Do All Dinoflagellates have an Extranuclear Spindle?

    Science.gov (United States)

    Moon, Eunyoung; Nam, Seung Won; Shin, Woongghi; Park, Myung Gil; Coats, D Wayne

    2015-11-01

    The syndinean dinoflagellates are a diverse assemblage of alveolate endoparasites that branch basal to the core dinoflagellates. Because of their phylogenetic position, the syndineans are considered key model microorganisms in understanding early evolution in the dinoflagellates. Closed mitosis with an extranuclear spindle that traverses the nucleus in cytoplasmic grooves or tunnels is viewed as one of the morphological features shared by syndinean and core dinoflagellates. Here we describe nuclear morphology and mitosis in the syndinean dinoflagellate Amoebophrya sp. from Akashiwo sanguinea, a member of the A. ceratii complex, as revealed by protargol silver impregnation, DNA specific fluorochromes, and transmission electron microscopy. Our observations show that not all species classified as dinoflagellates have an extranuclear spindle. In Amoebophrya sp. from A. sanguinea, an extranuclear microtubule cylinder located in a depression in the nuclear surface during interphase moves into the nucleoplasm via sequential membrane fusion events and develops into an entirely intranuclear spindle. Results suggest that the intranuclear spindle of Amoebophrya spp. may have evolved from an ancestral extranuclear spindle and indicate the need for taxonomic revision of the Amoebophryidae.

  8. Investigation of multiple spindle characteristics under non-uniform bearing preload

    Directory of Open Access Journals (Sweden)

    Yanfei Zhang

    2016-02-01

    Full Text Available The non-uniform distribution load during machining and assembly process is crucial for spindle system, especially in complex working conditions. The conception of non-uniform preload adjustment approach was proposed and experimentally investigated in this article. Based on the mechanical equivalent principle, the non-uniform preload was theoretically transformed to the combination of uniform preload and an extra moment. Then, the non-uniform preload of rolling bearing was experimentally measured and analyzed via a spacer with 15-µm wear loss on the end face. The spindle performance factors, such as rotation accuracy, temperature rising, acceleration, and vibration, were all monitored. The rotation center of spindle was deviated in different non-uniform preload conditions. Meanwhile, the temperature and vibration performance of non-uniform preload are superior to those of uniform bearing preload.

  9. Formation of bipolar spindles with two centrosomes in tetraploid cells established from normal human fibroblasts.

    Science.gov (United States)

    Ohshima, Susumu; Seyama, Atsushi

    2012-09-01

    Tetraploid cells with unstable chromosomes frequently arise as an early step in tumorigenesis and lead to the formation of aneuploid cells. The mechanisms responsible for the chromosome instability of polyploid cells are not fully understood, although the supernumerary centrosomes in polyploid cells have been considered the major cause of chromosomal instability. The aim of this study was to examine the integrity of mitotic spindles and centrosomes in proliferative polyploid cells established from normal human fibroblasts. TIG-1 human fibroblasts were treated with demecolcine (DC) for 4 days to induce polyploidy, and the change in DNA content was monitored. Localization of centrosomes and mitotic spindles in polyploid mitotic cells was examined by immunohistochemistry and laser scanning cytometry. TIG-1 cells treated with DC became almost completely tetraploid at 2 weeks after treatment and grew at the same rate as untreated diploid cells. Most mitotic cells with 8C DNA content had only two centrosomes with bipolar spindles in established tetraploid cells, although they had four or more centrosomes with multipolar spindles at 3 days after DC treatment. The frequency of aneuploid cells increased as established tetraploid cells were propagated. These results indicate that tetraploid cells that form bipolar spindles with two centrosomes in mitosis can proliferate as diploid cells. These cells may serve as a useful model for studying the chromosome instability of polyploid cells.

  10. Thermal Error Modelling of the Spindle Using Data Transformation and Adaptive Neurofuzzy Inference System

    Directory of Open Access Journals (Sweden)

    Yanlei Li

    2015-01-01

    Full Text Available This paper proposes a new method for predicting spindle deformation based on temperature data. The method introduces the adaptive neurofuzzy inference system (ANFIS, which is a neurofuzzy modeling approach that integrates the kernel and geometrical transformations. By utilizing data transformation, the number of ANFIS rules can be effectively reduced and the predictive model structure can be simplified. To build the predictive model, we first map the original temperature data to a feature space with Gaussian kernels. We then process the mapped data with the geometrical transformation and make the data gather in the square region. Finally, the transformed data are used as input to train the ANFIS. A verification experiment is conducted to evaluate the performance of the proposed method. Six Pt100 thermal resistances are used to monitor the spindle temperature, and a laser displacement sensor is used to detect the spindle deformation. Experimental results show that the proposed method can precisely predict the spindle deformation and greatly improve the thermal performance of the spindle. Compared with back propagation (BP networks, the proposed method is more suitable for complex working conditions in practical applications.

  11. Spindle assembly checkpoint genes reveal distinct as well as overlapping expression that implicates MDF-2/Mad2 in postembryonic seam cell proliferation in Caenorhabditis elegans.

    Science.gov (United States)

    Tarailo-Graovac, Maja; Wang, Jun; Chu, Jeffrey S C; Tu, Domena; Baillie, David L; Chen, Nansheng

    2010-09-21

    The spindle assembly checkpoint (SAC) delays anaphase onset by inhibiting the activity of the anaphase promoting complex/cyclosome (APC/C) until all of the kinetochores have properly attached to the spindle. The importance of SAC genes for genome stability is well established; however, the roles these genes play, during postembryonic development of a multicellular organism, remain largely unexplored. We have used GFP fusions of 5' upstream intergenic regulatory sequences to assay spatiotemporal expression patterns of eight conserved genes implicated in the spindle assembly checkpoint function in Caenorhabditis elegans. We have shown that regulatory sequences for all of the SAC genes drive ubiquitous GFP expression during early embryonic development. However, postembryonic spatial analysis revealed distinct, tissue-specific expression of SAC genes with striking co-expression in seam cells, as well as in the gut. Additionally, we show that the absence of MDF-2/Mad2 (one of the checkpoint genes) leads to aberrant number and alignment of seam cell nuclei, defects mainly attributed to abnormal postembryonic cell proliferation. Furthermore, we show that these defects are completely rescued by fzy-1(h1983)/CDC20, suggesting that regulation of the APC/CCDC20 by the SAC component MDF-2 is important for proper postembryonic cell proliferation. Our results indicate that SAC genes display different tissue-specific expression patterns during postembryonic development in C. elegans with significant co-expression in hypodermal seam cells and gut cells, suggesting that these genes have distinct as well as overlapping roles in postembryonic development that may or may not be related to their established roles in mitosis. Furthermore, we provide evidence, by monitoring seam cell lineage, that one of the checkpoint genes is required for proper postembryonic cell proliferation. Importantly, our research provides the first evidence that postembryonic cell division is more sensitive to

  12. Mechanical stability of bipolar spindle assembly

    CERN Document Server

    Malgaretti, Paolo

    2016-01-01

    Assembly and stability of mitotic spindle is governed by the interplay of various intra-cellular forces, e.g. the forces generated by motor proteins by sliding overlapping anti-parallel microtubules (MTs) polymerized from the opposite centrosomes, the interaction of kinetochores with MTs, and the interaction of MTs with the chromosomes arms. We study the mechanical behavior and stability of spindle assembly within the framework of a minimal model which includes all these effects. For this model, we derive a closed--form analytical expression for the force acting between the centrosomes as a function of their separation distance and we show that an effective potential can be associated with the interactions at play. We obtain the stability diagram of spindle formation in terms of parameters characterizing the strength of motor sliding, repulsive forces generated by polymerizing MTs, and the forces arising out of interaction of MTs with kinetochores. The stability diagram helps in quantifying the relative effec...

  13. Spindle Assembly and Chromosome Segregation Requires Central Spindle Proteins in Drosophila Oocytes

    Science.gov (United States)

    Das, Arunika; Shah, Shital J.; Fan, Bensen; Paik, Daniel; DiSanto, Daniel J.; Hinman, Anna Maria; Cesario, Jeffry M.; Battaglia, Rachel A.; Demos, Nicole; McKim, Kim S.

    2016-01-01

    Oocytes segregate chromosomes in the absence of centrosomes. In this situation, the chromosomes direct spindle assembly. It is still unclear in this system which factors are required for homologous chromosome bi-orientation and spindle assembly. The Drosophila kinesin-6 protein Subito, although nonessential for mitotic spindle assembly, is required to organize a bipolar meiotic spindle and chromosome bi-orientation in oocytes. Along with the chromosomal passenger complex (CPC), Subito is an important part of the metaphase I central spindle. In this study we have conducted genetic screens to identify genes that interact with subito or the CPC component Incenp. In addition, the meiotic mutant phenotype for some of the genes identified in these screens were characterized. We show, in part through the use of a heat-shock-inducible system, that the Centralspindlin component RacGAP50C and downstream regulators of cytokinesis Rho1, Sticky, and RhoGEF2 are required for homologous chromosome bi-orientation in metaphase I oocytes. This suggests a novel function for proteins normally involved in mitotic cell division in the regulation of microtubule–chromosome interactions. We also show that the kinetochore protein, Polo kinase, is required for maintaining chromosome alignment and spindle organization in metaphase I oocytes. In combination our results support a model where the meiotic central spindle and associated proteins are essential for acentrosomal chromosome segregation. PMID:26564158

  14. Spindle pole mechanics studied in mitotic asters: dynamic distribution of spindle forces through compliant linkages.

    Science.gov (United States)

    Charlebois, Blake D; Kollu, Swapna; Schek, Henry T; Compton, Duane A; Hunt, Alan J

    2011-04-06

    During cell division, chromosomes must faithfully segregate to maintain genome integrity, and this dynamic mechanical process is driven by the macromolecular machinery of the mitotic spindle. However, little is known about spindle mechanics. For example, spindle microtubules are organized by numerous cross-linking proteins yet the mechanical properties of those cross-links remain unexplored. To examine the mechanical properties of microtubule cross-links we applied optical trapping to mitotic asters that form in mammalian mitotic extracts. These asters are foci of microtubules, motors, and microtubule-associated proteins that reflect many of the functional properties of spindle poles and represent centrosome-independent spindle-pole analogs. We observed bidirectional motor-driven microtubule movements, showing that microtubule linkages within asters are remarkably compliant (mean stiffness 0.025 pN/nm) and mediated by only a handful of cross-links. Depleting the motor Eg5 reduced this stiffness, indicating that Eg5 contributes to the mechanical properties of microtubule asters in a manner consistent with its localization to spindle poles in cells. We propose that compliant linkages among microtubules provide a mechanical architecture capable of accommodating microtubule movements and distributing force among microtubules without loss of pole integrity-a mechanical paradigm that may be important throughout the spindle.

  15. Mitotic spindle proteomics in Chinese hamster ovary cells

    National Research Council Canada - National Science Library

    Bonner, Mary Kate; Poole, Daniel S; Xu, Tao; Sarkeshik, Ali; Yates, 3rd, John R; Skop, Ahna R

    2011-01-01

    .... Here, we report a proteomic study of the mitotic spindle from Chinese Hamster Ovary (CHO) cells. Four different isolations of metaphase spindles were subjected to Multi-dimensional Protein Identification Technology...

  16. Regulation of mitotic progression by the spindle assembly checkpoint

    DEFF Research Database (Denmark)

    Lischetti, Tiziana; Nilsson, Jakob

    2015-01-01

    Equal segregation of sister chromatids during mitosis requires that pairs of kinetochores establish proper attachment to microtubules emanating from opposite poles of the mitotic spindle. The spindle assembly checkpoint (SAC) protects against errors in segregation by delaying sister separation...

  17. Towards a quantitative understanding of mitotic spindle assembly and mechanics

    OpenAIRE

    Mogilner, Alex; Craig, Erin

    2010-01-01

    The ‘simple’ view of the mitotic spindle is that it self-assembles as a result of microtubules (MTs) randomly searching for chromosomes, after which the spindle length is maintained by a balance of outward tension exerted by molecular motors on the MTs connecting centrosomes and chromosomes, and compression generated by other motors on the MTs connecting the spindle poles. This picture is being challenged now by mounting evidence indicating that spindle assembly and maintenance rely on much m...

  18. The pacemaker role of thalamic reticular nucleus in controlling spike-wave discharges and spindles

    Science.gov (United States)

    Fan, Denggui; Liao, Fucheng; Wang, Qingyun

    2017-07-01

    Absence epilepsy, characterized by 2-4 Hz spike-wave discharges (SWDs), can be caused by pathological interactions within the thalamocortical system. Cortical spindling oscillations are also demonstrated to involve the oscillatory thalamocortical rhythms generated by the synaptic circuitry of the thalamus and cortex. This implies that SWDs and spindling oscillations can share the common thalamocortical mechanism. Additionally, the thalamic reticular nucleus (RE) is hypothesized to regulate the onsets and propagations of both the epileptic SWDs and sleep spindles. Based on the proposed single-compartment thalamocortical neural field model, we firstly investigate the stimulation effect of RE on the initiations, terminations, and transitions of SWDs. It is shown that the activations and deactivations of RE triggered by single-pulse stimuli can drive the cortical subsystem to behave as the experimentally observed onsets and self-abatements of SWDs, as well as the transitions from 2-spike and wave discharges (2-SWDs) to SWDs. In particular, with increasing inhibition from RE to the specific relay nucleus (TC), rich transition behaviors in cortex can be obtained through the upstream projection path, RE → TC → Cortex . Although some of the complex dynamical patterns can be expected from the earlier single compartment thalamocortical model, the effect of brain network topology on the emergence of SWDs and spindles, as well as the transitions between them, has not been fully investigated. We thereby develop a spatially extended 3-compartment coupled network model with open-/closed-end connective configurations, to investigate the spatiotemporal effect of RE on the SWDs and spindles. Results show that the degrees of activations of RE 1 can induce the rich spatiotemporal evolution properties including the propagations from SWDs to spindles within different compartments and the transitions between them, through the RE 1 → TC 1 → Cortex 1 and Cortex 1 → Cortex 2

  19. Lis1/dynactin regulates metaphase spindle orientation in Drosophila neuroblasts

    Science.gov (United States)

    Siller, Karsten H.; Doe, Chris Q.

    2008-01-01

    Mitotic spindle orientation in polarized cells determines whether they divide symmetrically or asymmetrically. Moreover, regulated spindle orientation may be important for embryonic development, stem cell biology, and tumor growth. Drosophila neuroblasts align their spindle along an apical/basal cortical polarity axis to self-renew an apical neuroblast and generate a basal differentiating cell. It is unknown whether the spindle alignment requires both apical and basal cues, nor have molecular motors been identified that regulate spindle movement. Using live imaging of neuroblasts within intact larval brains, we detect independent movement of both apical and basal spindle poles, suggesting that forces act on both poles. We show that reducing astral microtubules decreases the frequency of spindle movement, but not its maximum velocity, suggesting that one or few microtubules can move the spindle. Mutants in the Lis1/dynactin complex strongly decrease maximum and average spindle velocity, consistent with this motor complex mediating spindle/cortex forces. Loss of either astral microtubules or Lis1/dynactin leads to spindle/cortical polarity alignment defects at metaphase, but these are rescued by telophase. We propose that an early Lis1/dynactin-dependent pathway and a late Lis1/dynactin-independent pathway regulate neuroblast spindle orientation. PMID:18485341

  20. The KASH protein Kms2 coordinates mitotic remodeling of the spindle pole body.

    Science.gov (United States)

    Wälde, Sarah; King, Megan C

    2014-08-15

    Defects in the biogenesis of the spindle pole body (SPB), the yeast centrosome equivalent, can lead to monopolar spindles and mitotic catastrophe. The KASH domain protein Kms2 and the SUN domain protein Sad1 colocalize within the nuclear envelope at the site of SPB attachment during interphase and at the spindle poles during mitosis in Schizosaccharomyces pombe. We show that Kms2 interacts with the essential SPB components Cut12 and Pcp1 and the Polo kinase Plo1. Depletion of Kms2 delays mitotic entry and leads to defects in the insertion of the SPB into the nuclear envelope, disrupting stable bipolar spindle formation. These effects are mediated in part by a delay in the recruitment of Plo1 to the SPB at mitotic entry. Plo1 activity supports mitotic SPB remodeling by driving a burst of incorporation of Cut12 and Pcp1. Thus, a fission yeast SUN-KASH complex plays an important role in supporting the remodeling of the SPB at mitotic entry.

  1. Lte1 promotes mitotic exit by controlling the localization of the spindle position checkpoint kinase Kin4.

    Science.gov (United States)

    Falk, Jill E; Chan, Leon Y; Amon, Angelika

    2011-08-02

    For a daughter cell to receive a complete genomic complement, it is essential that the mitotic spindle be positioned accurately within the cell. In budding yeast, a signaling system known as the spindle position checkpoint (SPOC) monitors spindle position and regulates the activity of the mitotic exit network (MEN), a GTPase signaling pathway that promotes exit from mitosis. The protein kinase Kin4 is a central component of the spindle position checkpoint. Kin4 primarily localizes to the mother cell and associates with spindle pole bodies (SPBs) located in the mother cell to inhibit MEN signaling. In contrast, the kinase does not associate with the SPB in the bud. Thus, only when a MEN bearing SPB leaves the mother cell and the spindle is accurately positioned along the mother-bud axis can MEN signaling occur and cell division proceed. Here, we describe a mechanism ensuring that Kin4 only associates with mother cell-located SPBs. The bud-localized MEN regulator Lte1, whose molecular function has long been unclear, prevents Kin4 that escapes into the bud from associating with SPBs in the daughter cell.

  2. Integrated Multivariate Health Monitoring System for Helicopters Main Rotor Drives: Development and Validation with In-Service Data

    Science.gov (United States)

    2014-10-02

    distribution of the ordinary regime of the process. In a population characterised by a multidimensional Gauss distribution, the Mahalanobis distances...The extent to which the filtered healthy operational states of each component of the power drive fit with a multidimen- sional Gauss distribution...automotive and aerospace applications. John Wiley and Sons, Ltd. Publications. Rencher, A. C. (2002). Methods of multivariate analysis. Wi- ley

  3. A cell cycle timer for asymmetric spindle positioning.

    Science.gov (United States)

    McCarthy Campbell, Erin K; Werts, Adam D; Goldstein, Bob

    2009-04-21

    The displacement of the mitotic spindle to one side of a cell is important for many cells to divide unequally. While recent progress has begun to unveil some of the molecular mechanisms of mitotic spindle displacement, far less is known about how spindle displacement is precisely timed. A conserved mitotic progression mechanism is known to time events in dividing cells, although this has never been linked to spindle displacement. This mechanism involves the anaphase-promoting complex (APC), its activator Cdc20/Fizzy, its degradation target cyclin, and cyclin-dependent kinase (CDK). Here we show that these components comprise a previously unrecognized timer for spindle displacement. In the Caenorhabditis elegans zygote, mitotic spindle displacement begins at a precise time, soon after chromosomes congress to the metaphase plate. We found that reducing the function of the proteasome, the APC, or Cdc20/Fizzy delayed spindle displacement. Conversely, inactivating CDK in prometaphase caused the spindle to displace early. The consequence of experimentally unlinking spindle displacement from this timing mechanism was the premature displacement of incompletely assembled components of the mitotic spindle. We conclude that in this system, asymmetric positioning of the mitotic spindle is normally delayed for a short time until the APC inactivates CDK, and that this delay ensures that the spindle does not begin to move until it is fully assembled. To our knowledge, this is the first demonstration that mitotic progression times spindle displacement in the asymmetric division of an animal cell. We speculate that this link between the cell cycle and asymmetric cell division might be evolutionarily conserved, because the mitotic spindle is displaced at a similar stage of mitosis during asymmetric cell divisions in diverse systems.

  4. A cell cycle timer for asymmetric spindle positioning.

    Directory of Open Access Journals (Sweden)

    Erin K McCarthy Campbell

    2009-04-01

    Full Text Available The displacement of the mitotic spindle to one side of a cell is important for many cells to divide unequally. While recent progress has begun to unveil some of the molecular mechanisms of mitotic spindle displacement, far less is known about how spindle displacement is precisely timed. A conserved mitotic progression mechanism is known to time events in dividing cells, although this has never been linked to spindle displacement. This mechanism involves the anaphase-promoting complex (APC, its activator Cdc20/Fizzy, its degradation target cyclin, and cyclin-dependent kinase (CDK. Here we show that these components comprise a previously unrecognized timer for spindle displacement. In the Caenorhabditis elegans zygote, mitotic spindle displacement begins at a precise time, soon after chromosomes congress to the metaphase plate. We found that reducing the function of the proteasome, the APC, or Cdc20/Fizzy delayed spindle displacement. Conversely, inactivating CDK in prometaphase caused the spindle to displace early. The consequence of experimentally unlinking spindle displacement from this timing mechanism was the premature displacement of incompletely assembled components of the mitotic spindle. We conclude that in this system, asymmetric positioning of the mitotic spindle is normally delayed for a short time until the APC inactivates CDK, and that this delay ensures that the spindle does not begin to move until it is fully assembled. To our knowledge, this is the first demonstration that mitotic progression times spindle displacement in the asymmetric division of an animal cell. We speculate that this link between the cell cycle and asymmetric cell division might be evolutionarily conserved, because the mitotic spindle is displaced at a similar stage of mitosis during asymmetric cell divisions in diverse systems.

  5. Proprioceptive Feedback through a Neuromorphic Muscle Spindle Model

    Directory of Open Access Journals (Sweden)

    Lorenzo Vannucci

    2017-06-01

    Full Text Available Connecting biologically inspired neural simulations to physical or simulated embodiments can be useful both in robotics, for the development of a new kind of bio-inspired controllers, and in neuroscience, to test detailed brain models in complete action-perception loops. The aim of this work is to develop a fully spike-based, biologically inspired mechanism for the translation of proprioceptive feedback. The translation is achieved by implementing a computational model of neural activity of type Ia and type II afferent fibers of muscle spindles, the primary source of proprioceptive information, which, in mammals is regulated through fusimotor activation and provides necessary adjustments during voluntary muscle contractions. As such, both static and dynamic γ-motoneurons activities are taken into account in the proposed model. Information from the actual proprioceptive sensors (i.e., motor encoders is then used to simulate the spindle contraction and relaxation, and therefore drive the neural activity. To assess the feasibility of this approach, the model is implemented on the NEST spiking neural network simulator and on the SpiNNaker neuromorphic hardware platform and tested on simulated and physical robotic platforms. The results demonstrate that the model can be used in both simulated and real-time robotic applications to translate encoder values into a biologically plausible neural activity. Thus, this model provides a completely spike-based building block, suitable for neuromorphic platforms, that will enable the development of sensory-motor closed loops which could include neural simulations of areas of the central nervous system or of low-level reflexes.

  6. Sister chromatid tension and the spindle assembly checkpoint.

    Science.gov (United States)

    Nezi, Luigi; Musacchio, Andrea

    2009-12-01

    The spindle assembly checkpoint (SAC) is a feedback control system that monitors the state of kinetochore/microtubule attachment during mitosis and halts cell cycle progression until all chromosomes are properly aligned at the metaphase plate. The state of chromosome-microtubule attachment is implicated as a crucial factor in the checkpoint response. On the contrary, lack of tension in the centromere-kinetochore region of sister chromatids has been shown to regulate a pathway of correction of undesired chromosome-microtubule connections, while the presence of tension is believed to promote the stabilization of attachments. We discuss how tension-sensitive phenomena, such as attachment correction and stabilization, relate to the SAC and we speculate on the existence of a single pathway linking error correction and SAC activation.

  7. Temporal and compartment-specific signals coordinate mitotic exit with spindle position.

    Science.gov (United States)

    Caydasi, Ayse Koca; Khmelinskii, Anton; Duenas-Sanchez, Rafael; Kurtulmus, Bahtiyar; Knop, Michael; Pereira, Gislene

    2017-01-24

    The spatiotemporal control of mitotic exit is crucial for faithful chromosome segregation during mitosis. In budding yeast, the mitotic exit network (MEN) drives cells out of mitosis, whereas the spindle position checkpoint (SPOC) blocks MEN activity when the anaphase spindle is mispositioned. How the SPOC operates at a molecular level remains unclear. Here, we report novel insights into how mitotic signalling pathways orchestrate chromosome segregation in time and space. We establish that the key function of the central SPOC kinase, Kin4, is to counterbalance MEN activation by the cdc fourteen early anaphase release (FEAR) network in the mother cell compartment. Remarkably, Kin4 becomes dispensable for SPOC function in the absence of FEAR. Cells lacking both FEAR and Kin4 show that FEAR contributes to mitotic exit through regulation of the SPOC component Bfa1 and the MEN kinase Cdc15. Furthermore, we uncover controls that specifically promote mitotic exit in the daughter cell compartment.

  8. Assessment: A Driving Force.

    Science.gov (United States)

    Rakow, Steven J.

    1992-01-01

    Asserts that educational assessment drives the curriculum. Thus, assessment is very important in contemplating reform in science education. Assessment should be an integral part of the instructional process, utilizing diagnostic testing, monitoring, and summative evaluations. (PR)

  9. Intrafusal muscle fibre types in frog spindles.

    OpenAIRE

    Diwan, F H; Ito, F

    1989-01-01

    Muscle spindles from bullfrog semitendinosus, iliofibularis and sartorius muscles were examined with light and electron microscopy. Four types of intrafusal muscle fibre were identified according to their diameter, central nucleation and reticular zone arrangement: a large nuclear bag fibre, a medium nuclear bag fibre, and two types of small nuclear chain fibres with and without a reticular zone, respectively. It is suggested that they are comparable to the nuclear bag1, bag2 and chain fibres...

  10. Breast spindle cell tumours: about eight cases

    Directory of Open Access Journals (Sweden)

    Abd El All Howayda S

    2006-07-01

    Full Text Available Abstract Background Breast spindle cell tumours (BSCTs, although rare, represent a heterogeneous group with different treatment modalities. This work was undertaken to evaluate the utility of fine needle aspiration cytology (FNAC, histopathology and immunohistochemistry (IHC in differentiating BSCTs. Methods FNAC of eight breast masses diagnosed cytologically as BSCTs was followed by wide excision biopsy. IHC using a panel of antibodies against vimentin, pan-cytokeratin, s100, desmin, smooth muscle actin, CD34, and CD10 was evaluated to define their nature. Results FNAC defined the tumors as benign (n = 4, suspicious (n = 2 and malignant (n = 3, based on the cytopathological criteria of malignancy. Following wide excision biopsy, the tumors were reclassified into benign (n = 5 and malignant (n = 3. In the benign group, the diagnosis was raised histologically and confirmed by IHC for 3 cases (one spindle cell lipoma, one myofibroblastoma and one leiomyoma. For the remaining two cases, the diagnosis was set up after IHC (one fibromatosis and one spindle cell variant of adenomyoepithelioma. In the malignant group, a leiomyosarcoma was diagnosed histologically, while IHC was crucial to set up the diagnosis of one case of spindle cell carcinoma and one malignant myoepithelioma. Conclusion FNAC in BSCTs is an insufficient tool and should be followed by wide excision biopsy. The latter technique differentiate benign from malignant BSCTs and is able in 50% of the cases to set up the definite diagnosis. IHC is of value to define the nature of different benign lesions and is mandatory in the malignant ones for optimal treatment. Awareness of the different types of BSCTs prevents unnecessary extensive therapeutic regimes.

  11. Spindle alignment regulates the dynamic association of checkpoint proteins with yeast spindle pole bodies.

    Science.gov (United States)

    Caydasi, Ayse Koca; Pereira, Gislene

    2009-01-01

    In many polarized cells, the accuracy of chromosome segregation depends on the correct positioning of the mitotic spindle. In budding yeast, the spindle positioning checkpoint (SPOC) delays mitotic exit when the anaphase spindle fails to extend toward the mother-daughter axis. However it remains to be established how spindle orientation is translated to SPOC components at the yeast spindle pole bodies (SPB). Here, we used photobleaching techniques to show that the dynamics with which Bub2-Bfa1 turned over at SPBs significantly increased upon SPOC activation. A version of Bfa1 that was stably associated with SPBs rendered the cells SPOC deficient without affecting other Bub2-Bfa1 functions, demonstrating the functional importance of regulating the dynamics of Bfa1 SPB association. In addition, we established that the SPOC kinase Kin4 is the major regulator of Bfa1 residence time at SPBs. We suggest that upon SPOC activation Bfa1-Bub2 spreads throughout the cytoplasm, thereby inhibiting mitotic exit.

  12. Sleep spindles and intelligence: evidence for a sexual dimorphism.

    Science.gov (United States)

    Ujma, Péter P; Konrad, Boris Nikolai; Genzel, Lisa; Bleifuss, Annabell; Simor, Péter; Pótári, Adrián; Körmendi, János; Gombos, Ferenc; Steiger, Axel; Bódizs, Róbert; Dresler, Martin

    2014-12-03

    Sleep spindles are thalamocortical oscillations in nonrapid eye movement sleep, which play an important role in sleep-related neuroplasticity and offline information processing. Sleep spindle features are stable within and vary between individuals, with, for example, females having a higher number of spindles and higher spindle density than males. Sleep spindles have been associated with learning potential and intelligence; however, the details of this relationship have not been fully clarified yet. In a sample of 160 adult human subjects with a broad IQ range, we investigated the relationship between sleep spindle parameters and intelligence. In females, we found a positive age-corrected association between intelligence and fast sleep spindle amplitude in central and frontal derivations and a positive association between intelligence and slow sleep spindle duration in all except one derivation. In males, a negative association between intelligence and fast spindle density in posterior regions was found. Effects were continuous over the entire IQ range. Our results demonstrate that, although there is an association between sleep spindle parameters and intellectual performance, these effects are more modest than previously reported and mainly present in females. This supports the view that intelligence does not rely on a single neural framework, and stronger neural connectivity manifesting in increased thalamocortical oscillations in sleep is one particular mechanism typical for females but not males.

  13. Presence of Meiotic Spindles Indicates Early Cleavage of Embryos

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To assess whether the detection of the meiotic spindle could anticipate the appearance of early cleavage.Methods Oocytes were obtained from stimulated ovaries of consenting patients undergoing oocytes retrieval for ICSI.Spindles were imaged with the Polscope.After ICSI,oocytes with or without spindles were cultured for examination of early cleavage and embryo development.A total of 328 oocytes from 50 cycles were examined with the Polscope and inseminated by ICSI.Results Spindles were imaged in 81.7% of oocytes.After ICSI,more oocytes with spindles (78.4%) fertilized normally than oocytes without spindles (53.3%)(P<0.001).At 25-27 h post ICSI.more fertilized oocytes developed from oocytes with spindles (81.9%) were detected early cleavage than those from oocytes without spindles(28.1%)(P<0.001).Significantly more embryos with early cleavage (82.2%) developed to high quality embryos at d 3 compared with the embryos without early cleavage(48.3%)(P=0.001).The value of rs related to the relationship between spindles and early cleavage was 0.420(P<0.0001).Conclusion The existing of the early cleavage may have a predictive value on the opportunity of high quality embryos and the existing of the spindle may have a predictive value in the appearance of early cleavage.

  14. Simplified Dynamic Analysis of Grinders Spindle Node

    Science.gov (United States)

    Demec, Peter

    2014-12-01

    The contribution deals with the simplified dynamic analysis of surface grinding machine spindle node. Dynamic analysis is based on the use of the transfer matrix method, which is essentially a matrix form of method of initial parameters. The advantage of the described method, despite the seemingly complex mathematical apparatus, is primarily, that it does not require for solve the problem of costly commercial software using finite element method. All calculations can be made for example in MS Excel, which is advantageous especially in the initial stages of constructing of spindle node for the rapid assessment of the suitability its design. After detailing the entire structure of spindle node is then also necessary to perform the refined dynamic analysis in the environment of FEM, which it requires the necessary skills and experience and it is therefore economically difficult. This work was developed within grant project KEGA No. 023TUKE-4/2012 Creation of a comprehensive educational - teaching material for the article Production technique using a combination of traditional and modern information technology and e-learning.

  15. Drive Stands

    Data.gov (United States)

    Federal Laboratory Consortium — The Electrical Systems Laboratory (ESL)houses numerous electrically driven drive stands. A drive stand consists of an electric motor driving a gearbox and a mounting...

  16. A general thermal model of machine tool spindle

    Directory of Open Access Journals (Sweden)

    Yanfang Dong

    2017-01-01

    Full Text Available As the core component of machine tool, the thermal characteristics of the spindle have a significant influence on machine tool running status. Lack of an accurate model of the spindle system, particularly the model of load–deformation coefficient between the bearing rolling elements and rings, severely limits the thermal error analytic precision of the spindle. In this article, bearing internal loads, especially the function relationships between the principal curvature difference F(ρ and auxiliary parameter nδ, semi-major axis a, and semi-minor axis b, have been determined; furthermore, high-precision heat generation combining the heat sinks in the spindle system is calculated; finally, an accurate thermal model of the spindle was established. Moreover, a conventional spindle with embedded fiber Bragg grating temperature sensors has been developed. By comparing the experiment results with simulation, it indicates that the model has good accuracy, which verifies the reliability of the modeling process.

  17. The spindle checkpoint and chromosome segregation in meiosis.

    Science.gov (United States)

    Gorbsky, Gary J

    2015-07-01

    The spindle checkpoint is a key regulator of chromosome segregation in mitosis and meiosis. Its function is to prevent precocious anaphase onset before chromosomes have achieved bipolar attachment to the spindle. The spindle checkpoint comprises a complex set of signaling pathways that integrate microtubule dynamics, biomechanical forces at the kinetochores, and intricate regulation of protein interactions and post-translational modifications. Historically, many key observations that gave rise to the initial concepts of the spindle checkpoint were made in meiotic systems. In contrast with mitosis, the two distinct chromosome segregation events of meiosis present a special challenge for the regulation of checkpoint signaling. Preservation of fidelity in chromosome segregation in meiosis, controlled by the spindle checkpoint, also has a significant impact in human health. This review highlights the contributions from meiotic systems in understanding the spindle checkpoint as well as the role of checkpoint signaling in controlling the complex divisions of meiosis.

  18. Spatial signals link exit from mitosis to spindle position.

    Science.gov (United States)

    Falk, Jill Elaine; Tsuchiya, Dai; Verdaasdonk, Jolien; Lacefield, Soni; Bloom, Kerry; Amon, Angelika

    2016-05-11

    In budding yeast, if the spindle becomes mispositioned, cells prevent exit from mitosis by inhibiting the mitotic exit network (MEN). The MEN is a signaling cascade that localizes to spindle pole bodies (SPBs) and activates the phosphatase Cdc14. There are two competing models that explain MEN regulation by spindle position. In the 'zone model', exit from mitosis occurs when a MEN-bearing SPB enters the bud. The 'cMT-bud neck model' posits that cytoplasmic microtubule (cMT)-bud neck interactions prevent MEN activity. Here we find that 1) eliminating cMT- bud neck interactions does not trigger exit from mitosis and 2) loss of these interactions does not precede Cdc14 activation. Furthermore, using binucleate cells, we show that exit from mitosis occurs when one SPB enters the bud despite the presence of a mispositioned spindle. We conclude that exit from mitosis is triggered by a correctly positioned spindle rather than inhibited by improper spindle position.

  19. Mitotic spindle proteomics in Chinese hamster ovary cells.

    Directory of Open Access Journals (Sweden)

    Mary Kate Bonner

    Full Text Available Mitosis is a fundamental process in the development of all organisms. The mitotic spindle guides the cell through mitosis as it mediates the segregation of chromosomes, the orientation of the cleavage furrow, and the progression of cell division. Birth defects and tissue-specific cancers often result from abnormalities in mitotic events. Here, we report a proteomic study of the mitotic spindle from Chinese Hamster Ovary (CHO cells. Four different isolations of metaphase spindles were subjected to Multi-dimensional Protein Identification Technology (MudPIT analysis and tandem mass spectrometry. We identified 1155 proteins and used Gene Ontology (GO analysis to categorize proteins into cellular component groups. We then compared our data to the previously published CHO midbody proteome and identified proteins that are unique to the CHO spindle. Our data represent the first mitotic spindle proteome in CHO cells, which augments the list of mitotic spindle components from mammalian cells.

  20. Non-contact measurement and analysis of machine tool spindles

    OpenAIRE

    Clough, David A; Fletcher, Simon; Longstaff, Andrew P.

    2010-01-01

    Increasing demand on the manufacturing industry to produce tighter tolerance parts means it is\\ud necessary to gain a greater understanding of machine tool capabilities and error sources. A significant source of machine tool errors is down to spindle inaccuracies and performance, leading to part scrapping. Catastrophic spindle failure brings production to a standstill until a new spindle can be procured and installed, resulting in lost production time.\\ud This project aims to assess the effec...

  1. Use of the Protein Ontology (PRO for Multi-Faceted Analysis of Biological Processes: a Case Study of the Spindle Checkpoint

    Directory of Open Access Journals (Sweden)

    Karen E Ross

    2013-04-01

    Full Text Available As a member of the Open Biomedical Ontologies (OBO foundry, the Protein Ontology (PRO provides an ontological representation of protein forms and complexes and their relationships. Annotations in PRO can be assigned to individual protein forms and complexes, each distinguishable down to the level of post-translational modification, thereby allowing for a more precise depiction of protein function than is possible with annotations to the gene as a whole. Moreover, PRO is fully interoperable with other OBO ontologies and integrates knowledge from other protein-centric resources such as UniProt and Reactome. Here we demonstrate the value of the PRO framework in the investigation of the spindle checkpoint, a highly conserved biological process that relies extensively on protein modification and protein complex formation. The spindle checkpoint maintains genomic integrity by monitoring the attachment of chromosomes to spindle microtubules and delaying cell cycle progression until the spindle is fully assembled. Using PRO in conjunction with other bioinformatics tools, we explored the cross-species conservation of spindle checkpoint proteins, including phosphorylated forms and complexes; studied the impact of phosphorylation on spindle checkpoint function; and examined the interactions of spindle checkpoint proteins with the kinetochore, the site of checkpoint activation. Our approach can be generalized to any biological process of interest.

  2. Sleep Spindle Density Predicts the Effect of Prior Knowledge on Memory Consolidation.

    Science.gov (United States)

    Hennies, Nora; Lambon Ralph, Matthew A; Kempkes, Marleen; Cousins, James N; Lewis, Penelope A

    2016-03-30

    Information that relates to a prior knowledge schema is remembered better and consolidates more rapidly than information that does not. Another factor that influences memory consolidation is sleep and growing evidence suggests that sleep-related processing is important for integration with existing knowledge. Here, we perform an examination of how sleep-related mechanisms interact with schema-dependent memory advantage. Participants first established a schema over 2 weeks. Next, they encoded new facts, which were either related to the schema or completely unrelated. After a 24 h retention interval, including a night of sleep, which we monitored with polysomnography, participants encoded a second set of facts. Finally, memory for all facts was tested in a functional magnetic resonance imaging scanner. Behaviorally, sleep spindle density predicted an increase of the schema benefit to memory across the retention interval. Higher spindle densities were associated with reduced decay of schema-related memories. Functionally, spindle density predicted increased disengagement of the hippocampus across 24 h for schema-related memories only. Together, these results suggest that sleep spindle activity is associated with the effect of prior knowledge on memory consolidation. Episodic memories are gradually assimilated into long-term memory and this process is strongly influenced by sleep. The consolidation of new information is also influenced by its relationship to existing knowledge structures, or schemas, but the role of sleep in such schema-related consolidation is unknown. We show that sleep spindle density predicts the extent to which schemas influence the consolidation of related facts. This is the first evidence that sleep is associated with the interaction between prior knowledge and long-term memory formation. Copyright © 2016 Hennies et al.

  3. First simultaneous measurement of sextupolar and octupolar resonance driving terms in a circular accelerator from turn-by-turn beam position monitors data

    CERN Document Server

    Franchi, A; Ewald, F; Bec, G Le; Scheidt, K B

    2014-01-01

    Beam lifetime in storage rings and colliders is affected by, among other effects, lattice nonlinearities. Their control are of great benefit to the dynamic aperture of an accelerator, whose enlargement leads in general to more efficient injection and longer lifetime. This article describes a procedure to evaluate and correct unwanted nonlinearities by using turn-by-turn beam position monitor data, which is an evolution of previous works on the resonance driving terms (RDTs). Effective sextupole magnetic errors and tilts at the ESRF electron storage ring are evaluated and corrected (when possible) by using this technique. For the first time, also octupolar RDTs could be measured and used to define an octupolar model for the main quadrupoles. Most of the deviations from the model observed in the sextupolar RDTs of the ESRF storage ring turned out to be generated by focusing errors rather than by sextupole errors. These results could be achieved thanks to new analytical formulas describing the harmonic content o...

  4. Myosin-10 independently influences mitotic spindle structure and mitotic progression.

    Science.gov (United States)

    Sandquist, Joshua C; Larson, Matthew E; Hine, Ken J

    2016-06-01

    The iconic bipolar structure of the mitotic spindle is of extreme importance to proper spindle function. At best, spindle abnormalities result in a delayed mitosis, while worse outcomes include cell death or disease. Recent work has uncovered an important role for the actin-based motor protein myosin-10 in the regulation of spindle structure and function. Here we examine the contribution of the myosin tail homology 4 (MyTH4) domain of the myosin-10 tail to the protein's spindle functions. The MyTH4 domain is known to mediate binding to microtubules and we verify the suspicion that this domain contributes to myosin-10's close association with the spindle. More surprisingly, our data demonstrate that some but not all of myosin-10's spindle functions require microtubule binding. In particular, myosin-10's contribution to spindle pole integrity requires microtubule binding, whereas its contribution to normal mitotic progression does not. This is demonstrated by the observation that dominant negative expression of the wild-type MyTH4 domain produces multipolar spindles and an increased mitotic index, whereas overexpression of a version of the MyTH4 domain harboring point mutations that abrogate microtubule binding results in only the mitotic index phenotype. Our data suggest that myosin-10 helps to control the metaphase to anaphase transition in cells independent of microtubule binding. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  5. Form and Function of Sleep Spindles across the Lifespan

    Directory of Open Access Journals (Sweden)

    Brittany C. Clawson

    2016-01-01

    Full Text Available Since the advent of EEG recordings, sleep spindles have been identified as hallmarks of non-REM sleep. Despite a broad general understanding of mechanisms of spindle generation gleaned from animal studies, the mechanisms underlying certain features of spindles in the human brain, such as “global” versus “local” spindles, are largely unknown. Neither the topography nor the morphology of sleep spindles remains constant throughout the lifespan. It is likely that changes in spindle phenomenology during development and aging are the result of dramatic changes in brain structure and function. Across various developmental windows, spindle activity is correlated with general cognitive aptitude, learning, and memory; however, these correlations vary in strength, and even direction, depending on age and metrics used. Understanding these differences across the lifespan should further clarify how these oscillations are generated and their function under a variety of circumstances. We discuss these issues, and their translational implications for human cognitive function. Because sleep spindles are similarly affected in disorders of neurodevelopment (such as schizophrenia and during aging (such as neurodegenerative conditions, both types of disorders may benefit from therapies based on a better understanding of spindle function.

  6. Diverse functions of spindle assembly checkpoint genes in Saccharomyces cerevisiae.

    Science.gov (United States)

    Daniel, Jewel A; Keyes, Brice E; Ng, Yvonne P Y; Freeman, C Onyi; Burke, Daniel J

    2006-01-01

    The spindle assembly checkpoint regulates the metaphase-to-anaphase transition from yeast to humans. We examined the genetic interactions with four spindle assembly checkpoint genes to identify nonessential genes involved in chromosome segregation, to identify the individual roles of the spindle assembly checkpoint genes within the checkpoint, and to reveal potential complexity that may exist. We used synthetic genetic array (SGA) analysis using spindle assembly checkpoint mutants mad1, mad2, mad3, and bub3. We found 228 synthetic interactions with the four spindle assembly checkpoint mutants with substantial overlap in the spectrum of interactions between mad1, mad2, and bub3. In contrast, there were many synthetic interactions that were common to mad1, mad2, and bub3 that were not shared by mad3. We found shared interactions between pairs of spindle assembly checkpoint mutants, suggesting additional complexity within the checkpoint and unique interactions for all of the spindle assembly checkpoint genes. We show that most genes in the interaction network, including ones with unique interactions, affect chromosome transmission or microtubule function, suggesting that the complexity of interactions reflects diverse roles for the checkpoint genes within the checkpoint. Our analysis expands our understanding of the spindle assembly checkpoint and identifies new candidate genes with possible roles in chromosome transmission and mitotic spindle function.

  7. Spindle Cell Carcinoma of the Mandibular Gingiva - A Case Report.

    Science.gov (United States)

    Patankar, Sangeeta R; Gaonkar, Pratyusha P; Bhandare, Prachi R; Tripathi, Nidhi; Sridharan, Gokul

    2016-02-01

    Spindle cell carcinoma is a malignancy of epithelial origin often mimicking its mesenchymal counterpart thus posing a diagnostic challenge. It is a rare biphasic malignant tumour mostly encountered in the upper aerodigestive tract. The chief differential diagnoses of spindle cell carcinoma are true superficial sarcomas and they especially need to be differentiated from fibrosarcoma. This presentation reports a spindle cell carcinoma of the gingiva and highlights the difficulties encountered in the diagnosis. It also emphasizes the importance of accurate and thorough diagnosis of malignant spindle cell lesions to determine the appropriate therapeutic modality.

  8. Is human muscle spindle afference dependent on perceived size of error in visual tracking?

    Science.gov (United States)

    Kakuda, N; Wessberg, J; Vallbo, A B

    1997-04-01

    Impulses of 16 muscle spindle afferents from finger extensor muscles were recorded from the radial nerve along with electromyographic (EMG) activity and kinematics of joint movement. Twelve units were classified as Ia and 4 as II spindle afferents. Subjects were requested to perform precision movements at a single metacarpophalangeal joint in an indirect visual tracking task. Similar movements were executed under two different conditions, i.e. with high and low error gain. The purpose was to explore whether different precision demands were associated with different spindle firing rates. With high error gain, a small but significantly higher impulse rate was found in pooled data from Ia afferents during lengthening movements but not during shortening movements, nor with II afferents. EMG was also significantly higher with high error gain in recordings with Ia afferents. When the effect of EMG was factored out, using partial correlation analysis, the significant difference in Ia firing rate vanished. The findings suggest that fusimotor drive as well as skeletomotor activity were both marginally higher when the precision demand was higher, whereas no indication of independent fusimotor adjustments was found. These results are discussed with respect to data from behaving animals and the role of fusimotor independence in various limb muscles proposed.

  9. Spindle cell haemangioma of the tongue.

    Science.gov (United States)

    French, Kathryn E M; Felstead, Andrew M; Haacke, Norman; Theaker, Jeffrey; Brennan, Peter A; Colbert, Serryth D

    2016-11-01

    Spindle cell hemangioma (SCH) is an uncommon benign vascular tumor that rarely occurs in the mouth. We present an SCH arising in the tongue of a 52-year-old otherwise healthy woman. SCH should be considered in the differential diagnosis of vascular tumors in the oral cavity and not misinterpreted as a more aggressive vascular tumor. We describe the clinical presentation, investigation, differential diagnosis and management of this condition and a literature search showing published case reports. Although SCH rarely presents in the oral cavity it needs to be considered in the differential diagnosis of oral cavity tumors. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. A FRET-based study reveals site-specific regulation of spindle position checkpoint proteins at yeast centrosomes.

    Science.gov (United States)

    Gryaznova, Yuliya; Koca Caydasi, Ayse; Malengo, Gabriele; Sourjik, Victor; Pereira, Gislene

    2016-05-09

    The spindle position checkpoint (SPOC) is a spindle pole body (SPB, equivalent of mammalian centrosome) associated surveillance mechanism that halts mitotic exit upon spindle mis-orientation. Here, we monitored the interaction between SPB proteins and the SPOC component Bfa1 by FRET microscopy. We show that Bfa1 binds to the scaffold-protein Nud1 and the γ-tubulin receptor Spc72. Spindle misalignment specifically disrupts Bfa1-Spc72 interaction by a mechanism that requires the 14-3-3-family protein Bmh1 and the MARK/PAR-kinase Kin4. Dissociation of Bfa1 from Spc72 prevents the inhibitory phosphorylation of Bfa1 by the polo-like kinase Cdc5. We propose Spc72 as a regulatory hub that coordinates the activity of Kin4 and Cdc5 towards Bfa1. In addition, analysis of spc72∆ cells shows that a mitotic-exit-promoting dominant signal, which is triggered upon elongation of the spindle into the bud, overrides the SPOC. Our data reinforce the importance of daughter-cell-associated factors and centrosome-based regulations in mitotic exit and SPOC control.

  11. TFG-MET fusion in an infantile spindle cell sarcoma with neural features

    NARCIS (Netherlands)

    Flucke, Uta; van Noesel, Max M.; Wijnen, Marc; Zhang, Lei; Chen, Chun Liang; Sung, Yun Shao; Antonescu, Cristina R.

    2017-01-01

    An increasing number of congenital and infantile sarcomas displaying a primitive, monomorphic spindle cell phenotype have been characterized to harbor recurrent gene fusions, including infantile fibrosarcoma and congenital spindle cell rhabdomyosarcoma. Here, we report an unusual spindle cell

  12. Electromagnetic driving units for complex microrobotic systems

    Science.gov (United States)

    Michel, Frank; Ehrfeld, Wolfgang; Berg, Udo; Degen, Reinhard; Schmitz, Felix

    1998-10-01

    Electromagnetic actuators play an important role in macroscopic robotic systems. In combination with motion transformers, like reducing gear units, angular gears or spindle-screw drives, electromagnetic motors in large product lines ensure the rotational or linear motion of robot driving units and grippers while electromagnets drive valves or part conveyors. In this paper micro actuators and miniaturized motion transformers are introduced which allow a similar development in microrobotics. An electromagnetic motor and a planetary gear box, both with a diameter of 1.9 mm, are already commercially available from the cooperation partner of IMM, the company Dr. Fritz Faulhaber GmbH in Schonaich, Germany. In addition, a motor with a diameter of 2.4 mm is in development. The motors successfully drive an angular gear and a belt drive. A linear stage with a motion range of 7 mm and an overall size as small as 5 X 3.5 X 24 mm3 has been realized involving the motor, a stationary spur gear with zero backlash and a spindle-screw drive. By the use of these commercially available elements complex microrobots can be built up cost-efficiently and rapidly. Furthermore, a batch process has been developed to produce the coils of micro actuator arrays using lithographic techniques with SU-8 resin. In applying these components, the modular construction of complex microrobotic systems becomes feasible.

  13. 10-15 years of GST monitoring over mountain permafrost in Switzerland: Indicators for driving forces for permafrost evolution

    Science.gov (United States)

    Staub, Benno; Delaloye, Reynald; Hilbich, Christin; Lambiel, Christophe; Nötzli, Jeannette; Völksch, Ingo

    2013-04-01

    Ground Surface Temperatures (GST) are mainly controlled by atmospheric factors and topographical effects and represent an important standard element within the operational permafrost monitoring network PERMOS in Switzerland. Due to its shape, position and extent the Alpine arc is influenced by prevailing winds from several directions provoking a complex and highly variable pattern of precipitation in different regions of Switzerland with a general trend to a more continental climate in some inner-alpine valleys. The lower boundary for the occurrence of mountain permafrost in the Swiss Alps is located at about 2500 m asl., close to the free atmosphere where air temperatures are almost homogenous in all regions, but precipitation usually shows large regional differences regarding timing and quantity depending on the meteorological conditions. At the elevation range of mountain permafrost the ground surface remains snow-free only for about 4-5 months (between June and November) with a high temporal and spatial variability, while over the rest of the year it stays well shielded from the atmosphere (due to the high surface albedo and emissivity and low thermal conductivity of snow). Therefore, the influence of the atmosphere at this boundary layer on the ground thermal regime is well reflected by GST measurements on a very local, site-specific scale. Relative values like GST anomalies can serve as indicators describing processes of energy and heat transfer at the ground surface in a semi-quantitative way. This information is used in a signal-response analysis integrating GST with other permafrost monitoring elements that represent the permafrost response to external effects (e.g. relative changes in borehole temperatures, apparent electrical resistivities or rock glacier creep rates). To identify and quantify the dominant processes and factors controlling the response of Alpine permafrost to external forces, special consideration is devoted to the characteristics of

  14. Hematite spindles with optical functionalities: growth of gold nanoshells and assembly of gold nanorods.

    Science.gov (United States)

    Spuch-Calvar, Miguel; Pérez-Juste, Jorge; Liz-Marzán, Luis M

    2007-06-01

    The layer-by-layer (LBL) assembly method, combined with the seeded growth technique, have been used to deposit gold shells on the surface of hematite (alpha-Fe(2)O(3)) spindles. While the LBL method yields dense coatings of preformed Au nanoparticles, when AuCl(-)(4) ions are further reduced by a mild reducing agent, thicker, rough nanostructured shells can be grown. The deposition process was monitored by TEM and UV-visible spectroscopy, demonstrating a gradual change in the optical features of the colloids as the surface is more densely covered. The particles so-prepared can find useful applications in cancer therapy and as SERS substrates. Additionally, we show that Au nanorods can be assembled on hematite spindles, providing a flexible way to tune the optical properties of the resulting composite colloids.

  15. Joined at the hip: kinetochores, microtubules, and spindle assembly checkpoint signaling.

    Science.gov (United States)

    Sacristan, Carlos; Kops, Geert J P L

    2015-01-01

    Error-free chromosome segregation relies on stable connections between kinetochores and spindle microtubules. The spindle assembly checkpoint (SAC) monitors such connections and relays their absence to the cell cycle machinery to delay cell division. The molecular network at kinetochores that is responsible for microtubule binding is integrated with the core components of the SAC signaling system. Molecular-mechanistic understanding of how the SAC is coupled to the kinetochore-microtubule interface has advanced significantly in recent years. The latest insights not only provide a striking view of the dynamics and regulation of SAC signaling events at the outer kinetochore but also create a framework for understanding how that signaling may be terminated when kinetochores and microtubules connect.

  16. IL-6 and mouse oocyte spindle.

    Directory of Open Access Journals (Sweden)

    Jashoman Banerjee

    Full Text Available Interleukin 6 (IL-6 is considered a major indicator of the acute-phase inflammatory response. Endometriosis and pelvic inflammation, diseases that manifest elevated levels of IL-6, are commonly associated with higher infertility. However, the mechanistic link between elevated levels of IL-6 and poor oocyte quality is still unclear. In this work, we explored the direct role of this cytokine as a possible mediator for impaired oocyte spindle and chromosomal structure, which is a critical hurdle in the management of infertility. Metaphase-II mouse oocytes were exposed to recombinant mouse IL-6 (50, 100 and 200 ng/mL for 30 minutes and subjected to indirect immunofluorescent staining to identify alterations in the microtubule and chromosomal alignment compared to untreated controls. The deterioration in microtubule and chromosomal alignment were evaluated utilizing both fluorescence and confocal microscopy, and were quantitated with a previously reported scoring system. Our results showed that IL-6 caused a dose-dependent deterioration in microtubule and chromosomal alignment in the treated oocytes as compared to the untreated group. Indeed, IL-6 at a concentration as low as 50 ng/mL caused deterioration in the spindle structure in 60% of the oocytes, which increased significantly (P<0.0001 as IL-6 concentration was increased. In conclusion, elevated levels of IL-6 associated with endometriosis and pelvic inflammation may reduce the fertilizing capacity of human oocyte through a mechanism that involves impairment of the microtubule and chromosomal structure.

  17. Sleep Spindles as Biomarker for Early Detection of Neurodegenerative Disorders

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to the use of sleep spindles as a novel biomarker for early diagnosis of synucleinopathies, in particular Parkinson's disease (PD). The method is based on automatic detection of sleep spindles. The method may be combined with measurements of one or more further...

  18. Towards a quantitative understanding of mitotic spindle assembly and mechanics.

    Science.gov (United States)

    Mogilner, Alex; Craig, Erin

    2010-10-15

    The 'simple' view of the mitotic spindle is that it self-assembles as a result of microtubules (MTs) randomly searching for chromosomes, after which the spindle length is maintained by a balance of outward tension exerted by molecular motors on the MTs connecting centrosomes and chromosomes, and compression generated by other motors on the MTs connecting the spindle poles. This picture is being challenged now by mounting evidence indicating that spindle assembly and maintenance rely on much more complex interconnected networks of microtubules, molecular motors, chromosomes and regulatory proteins. From an engineering point of view, three design principles of this molecular machine are especially important: the spindle assembles quickly, it assembles accurately, and it is mechanically robust--yet malleable. How is this design achieved with randomly interacting and impermanent molecular parts? Here, we review recent interdisciplinary studies that have started to shed light on this question. We discuss cooperative mechanisms of spindle self-assembly, error correction and maintenance of its mechanical properties, speculate on analogy between spindle and lamellipodial dynamics, and highlight the role of quantitative approaches in understanding the mitotic spindle design.

  19. Mitotic spindle assembly: May the force be with you

    NARCIS (Netherlands)

    Heesbeen, R.G.H.P. van

    2015-01-01

    The research described in this thesis is focused on multiple pathways required for assembly of a bipolar mitotic spindle. Proper assembly of a bipolar mitotic spindle is essential for the generation of stable kinetochore-microtubule attachments and correct segregation of the sister chromatids. Defec

  20. On the Spatial Configuration of the Mitotic Spindle

    Science.gov (United States)

    Wen, Weijia; Sun, Limin; Lu, Kunquan; Tang, Xiaowei

    1995-03-01

    An experimental simulation using electrorheological (ER) fluid is developed to investigate the spatial configuration of the mitotic spindle. In the presence of two different kinds of electric field, the structures of particle arrangement in ER fluid are similar to the configuration of the mitotic spindle of the animal and plant cells respectively.

  1. Mechanisms of Centrosome Separation and Bipolar Spindle Assembly

    NARCIS (Netherlands)

    Tanenbaum, Marvin E.; Medema, Rene H.

    2010-01-01

    Accurate segregation of chromosomes during cell division is accomplished through the assembly of a bipolar microtubule-based structure called the mitotic spindle. Work over the past two decades has identified a core regulator of spindle bipolarity, the microtubule motor protein kinesin-5. However, a

  2. First observation of a muscle spindle in fish.

    Science.gov (United States)

    Maeda, N; Miyoshi, S; Toh, H

    1983-03-01

    In many groups of vertebrates, the muscle spindle is a specialized sensory organ for the detection of muscle stretching. The structure of the spindle varies among vertebrate classes. Moreover, Barker has asserted that Amphibia are the most primitive vertebrates to possess muscle spindles. Extensive studies, made mainly on the locomotor myotome, seem to show that the muscle receptors of fish are less specialized than those of more advanced animals, and that muscle spindles are absent. However, little attention has been paid to the jaw-closing muscle. We report here our finding of a very simple muscle spindle with a single intrafusal fibre in the well-developed jaw-closing muscle, adductor mandibulae, in a primitive teleostean, Oncorhynchus masou (Brevoort).

  3. Sleep spindles predict stress-related increases in sleep disturbances

    Directory of Open Access Journals (Sweden)

    Thien Thanh eDang-Vu

    2015-02-01

    Full Text Available Background and Aim: Predisposing factors place certain individuals at higher risk for insomnia, especially in the presence of precipitating conditions such as stressful life events. Sleep spindles have been shown to play an important role in the preservation of sleep continuity. Lower spindle density might thus constitute an objective predisposing factor for sleep reactivity to stress. The aim of this study was therefore to evaluate the relationship between baseline sleep spindle density and the prospective change in insomnia symptoms in response to a standardized academic stressor. Methods: 12 healthy students had a polysomnography (PSG recording during a period of lower stress at the beginning of the academic semester, along with an assessment of insomnia complaints using the Insomnia Severity Index (ISI. They completed a second ISI assessment at the end of the semester, a period coinciding with the week prior to final examinations and thus higher stress. Spindle density, amplitude, duration and frequency, as well as sigma power were computed from C4-O2 electroencephalography (EEG derivation during stages N2-N3 of non-rapid-eye-movement (NREM sleep, across the whole night and for each NREM sleep period. To test for the relationship between spindle density and changes in insomnia symptoms in response to academic stress, spindle measurements at baseline were correlated with changes in ISI across the academic semester.Results: Spindle density (as well as spindle amplitude and sigma power, particularly during the first NREM sleep period, negatively correlated with changes in ISI (p < 0.05. Conclusion: Lower spindle activity, especially at the beginning of the night, prospectively predicted larger increases in insomnia symptoms in response to stress. This result indicates that individual differences in sleep spindle activity contribute to the differential vulnerability to sleep disturbances in the face of precipitating factors.

  4. Drugged Driving

    Science.gov (United States)

    ... Parents & Educators Children & Teens Search Connect with NIDA : Google Plus Facebook LinkedIn Twitter YouTube Flickr RSS Menu ... misuse of prescription drugs can make driving a car unsafe—just like driving after drinking alcohol. Drugged ...

  5. p600 regulates spindle orientation in apical neural progenitors and contributes to neurogenesis in the developing neocortex

    Directory of Open Access Journals (Sweden)

    Camille Belzil

    2014-05-01

    Full Text Available Apical neural progenitors (aNPs drive neurogenesis by means of a program consisting of self-proliferative and neurogenic divisions. The balance between these two manners of division sustains the pool of apical progenitors into late neurogenesis, thereby ensuring their availability to populate the brain with terminal cell types. Using knockout and in utero electroporation mouse models, we report a key role for the microtubule-associated protein 600 (p600 in the regulation of spindle orientation in aNPs, a cellular event that has been associated with cell fate and neurogenesis. We find that p600 interacts directly with the neurogenic protein Ndel1 and that aNPs knockout for p600, depleted of p600 by shRNA or expressing a Ndel1-binding p600 fragment all display randomized spindle orientation. Depletion of p600 by shRNA or expression of the Ndel1-binding p600 fragment also results in a decreased number of Pax6-positive aNPs and an increased number of Tbr2-positive basal progenitors destined to become neurons. These Pax6-positive aNPs display a tilted mitotic spindle. In mice wherein p600 is ablated in progenitors, the production of neurons is significantly impaired and this defect is associated with microcephaly. We propose a working model in which p600 controls spindle orientation in aNPs and discuss its implication for neurogenesis.

  6. Electric drives

    CERN Document Server

    Boldea, Ion

    2005-01-01

    ENERGY CONVERSION IN ELECTRIC DRIVESElectric Drives: A DefinitionApplication Range of Electric DrivesEnergy Savings Pay Off RapidlyGlobal Energy Savings Through PEC DrivesMotor/Mechanical Load MatchMotion/Time Profile MatchLoad Dynamics and StabilityMultiquadrant OperationPerformance IndexesProblemsELECTRIC MOTORS FOR DRIVESElectric Drives: A Typical ConfigurationElectric Motors for DrivesDC Brush MotorsConventional AC MotorsPower Electronic Converter Dependent MotorsEnergy Conversion in Electric Motors/GeneratorsPOWER ELECTRONIC CONVERTERS (PECs) FOR DRIVESPower Electronic Switches (PESs)The

  7. Polycystic kidney disease protein fibrocystin localizes to the mitotic spindle and regulates spindle bipolarity.

    Science.gov (United States)

    Zhang, Jingjing; Wu, Maoqing; Wang, Shixuan; Shah, Jagesh V; Wilson, Patricia D; Zhou, Jing

    2010-09-01

    Autosomal recessive polycystic kidney disease (ARPKD) is a significant hereditary renal disease occurring in infancy and childhood, which presents with greatly enlarged echogenic kidneys, ultimately leading to renal insufficiency and end-stage renal disease. ARPKD is caused by mutations in a single gene PKHD1, which encodes fibrocystin/polyductin (FPC), a large single transmembrane protein generally known to be on the primary cilium, basal body and plasma membrane. Here, using our newly generated antibody raised against the entire C-terminal intracellular cytoplasmic domain (ICD) of FPC, as well as our previously well-characterized antibody against a peptide of ICD, we report for the first time that at least one isoform of FPC is localized to the centrosome and mitotic spindle of dividing cells in multiple cell lines, including MDCK, mIMCD3, LLC-PK1, HEK293, RCTEC and HFCT cells. Using short-hairpin-mediated RNA interference, we show that the inhibition of FPC function in MDCK and mIMCD3 cells leads to centrosome amplification, chromosome lagging and multipolar spindle formation. Consistent with our in vitro findings, we also observed centrosome amplification in the kidneys from human ARPKD patients. These findings demonstrate a novel function of FPC in centrosome duplication and mitotic spindle assembly during cell division. We propose that mitotic defects due to FPC dysfunction contribute to cystogenesis in ARPKD.

  8. A displacement spindle in a micro/nano level

    Science.gov (United States)

    Fan, Kuang-Chao; Lai, Zi-Fa; Wu, Peitsung; Chen, Yung-Chang; Chen, Yejin; Jäger, Gerd

    2007-06-01

    This paper presents two micro/nano level displacement sensors, which consist of a mini LDGI (linear diffraction grating interferometer) and a focus probe. These two sensors are integrated into the spindle system of a micro/nano-CMM. This micro/nano spindle system is fixed on a rectangular granite bridge to achieve the z-axis function. The motion of the spindle is driven by an ultrasonic motor on a precision cross-roller slide. Its displacement is fed back by the LDGI. A DVD pick-up head is modified with its S-curve principle as the non-contact focus probe. Mounting the probe onto the spindle head, it is possible to achieve a large displacement and nanoresolution measuring spindle system with a feedback nanomotion control scheme. After accuracy calibration and error compensation, the spindle motion to 10 mm can perform 10 nm positioning accuracy and 30 nm measurement accuracy. Experiments on some ultraprecision profiles have shown the capability of this spindle system.

  9. Distinct Kinesin-14 mitotic mechanisms in spindle bipolarity.

    Science.gov (United States)

    Simeonov, Dimitre R; Kenny, Katelyn; Seo, Lan; Moyer, Amanda; Allen, Jessica; Paluh, Janet L

    2009-11-01

    Kinesin-like proteins are integral to formation and function of a conserved mitotic spindle apparatus that directs chromosome segregation and precedes cell division. Ubiquitous to the mechanism of spindle assembly and stability are balanced Kinesin-5 promoting and Kinesin-14 opposing forces. Distinct Kinesin-14 roles in bipolarity in eukaryotes have not been shown, but are suggested by gamma-tubulin-based pole interactions that affect establishment and by microtubule cross-linking and sliding that maintain bipolarity and spindle length. Distinct roles also imply specialized functional domains. By cross-species analysis of compatible mechanisms in establishing mitotic bipolarity we demonstrate that Kinesin-14 human HSET (HsHSET) functionally replaces Schizosaccharomyces pombe Pkl1 and its action is similarly blocked by mutation in a Kinesin-14 binding site on gamma-tubulin. Drosophila DmNcd localizes preferentially to bundled interpolar microtubules in fission yeast and does not replace SpPkl1. Analysis of twenty-six Kinesin-14 derivatives, including Tail, Stalk or Neck-Motor chimeras, for spindle localization, spindle assembly and mitotic progression defined critical domains. The Tail of SpPkl1 contains functional elements enabling its role in spindle assembly that are distinct from but transferable to DmNcd, whereas HsHSET function utilizes both Tail and Stalk features. Our analysis is the first to demonstrate distinct mechanisms between SpPkl1 and DmNcd, and reveal that HsHSET shares functional overlap in spindle pole mechanisms.

  10. 3D Simulation of Spindle Gravitational Collapse of a Collisionless Particle System

    CERN Document Server

    Yoo, Chul-Moon; Okawa, Hirotada

    2016-01-01

    We simulate the spindle gravitational collapse of a collisionless particle system in a 3D numerical relativity code and compare the qualitative results with the old work done by Shapiro and Teukolsky(ST). The simulation starts from the prolate-shaped distribution of particles and a spindle collapse is observed. The peak value and its spatial position of curvature invariants are monitored during the time evolution. We find that the peak value of the Kretschmann invariant takes a maximum at some moment, when there is no apparent horizon, and its value is greater for finer resolution, which is consistent with what is reported in ST. We also find a similar tendency for the Weyl curvature invariant. Therefore, our results lend support to the formation of a naked singularity as a result of the spindle collapse of a collisionless particle system in the limit of infinite resolution. However, unlike in ST, our code does not break down then but go well beyond. We find that the peak values of the curvature invariants st...

  11. Centrosomes and the art of mitotic spindle maintenance.

    Science.gov (United States)

    Hinchcliffe, Edward H

    2014-01-01

    The assembly of a bipolar spindle lies at the heart of mitotic chromosome segregation. In animal somatic cells, the process of spindle assembly involves multiple complex interactions between various cellular compartments, including an emerging antiparallel microtubule network, microtubule-associated motor proteins and spindle assembly factors, the cell's cortex, and the chromosomes themselves. The result is a dynamic structure capable of aligning pairs of sister chromatids, sensing chromosome misalignment, and generating force to segregate the replicated genome into two daughters. Because the centrosome lies at the center of the array of microtubule minus-ends, and the essential one-to-two duplication of the centrosome prior to mitosis is linked to cell cycle progression, this organelle has long been implicated as a device to generate spindle bipolarity. However, this classic model for spindle assembly is challenged by observations and experimental manipulations demonstrating that acentrosomal cells can and do form bipolar spindles, both mitotic and meiotic. Indeed, recent comprehensive proteomic analysis of centrosome-dependent versus independent mitotic spindle assembly mechanisms reveals a large, common set of genes required for both processes, with very few genes needed to differentiate between the two. While these studies cast doubt on an absolute role for the centrosome in establishing spindle polarity, it is clear that having too few or too many centrosomes results in abnormal chromosome segregation and aneuploidy. Here we review the case both for and against the role of the centrioles and centrosomes in ensuring proper assembly of a bipolar spindle, an essential element in the maintenance of genomic stability.

  12. Sleep spindling and fluid intelligence across adolescent development: sex matters

    Directory of Open Access Journals (Sweden)

    Róbert eBódizs

    2014-11-01

    Full Text Available Evidence supports the intricate relationship between sleep electroencephalogram (EEG spindling and cognitive abilities in children and adults. Although sleep EEG changes during adolescence index fundamental brain reorganization, a detailed analysis of sleep spindling and the spindle-intelligence relationship was not yet provided for adolescents. Therefore, adolescent development of sleep spindle oscillations were studied in a home polysomnographic study focusing on the effects of chronological age and developmentally acquired overall mental efficiency (fluid IQ with sex as a potential modulating factor. Subjects were 24 healthy adolescents (12 males with an age range of 15–22 years (mean: 18 years and fluid IQ of 91-126 (mean: 104.12, Raven Progressive Matrices Test. Slow spindles (SSs and fast spindles (FSs were analyzed in 21 EEG derivations by using the individual adjustment method. A significant age-dependent increase in average FS density (r = .57; p = .005 was found. Moreover, fluid IQ correlated with FS density (r = .43; p = .04 and amplitude (r = .41; p = .049. The latter effects were entirely driven by particularly reliable FS-IQ correlations in females [r = .80 (p = .002 and r = .67 (p = .012, for density and amplitude, respectively]. Region-specific analyses revealed that these correlations peak in the fronto-central regions. The control of the age-dependence of FS measures and IQ scores did not considerably reduce the spindle-IQ correlations with respect to FS density. The only positive spindle-index of fluid IQ in males turned out to be the frequency of FSs (r = .60, p = .04. Increases in FS density during adolescence may index reshaped structural connectivity related to white matter maturation in the late developing human brain. The continued development over this age range of cognitive functions is indexed by specific measures of sleep spindling unravelling gender differences in adolescent brain maturation and perhaps cognitive

  13. Pile Driving

    Science.gov (United States)

    1987-01-01

    Machine-oriented structural engineering firm TERA, Inc. is engaged in a project to evaluate the reliability of offshore pile driving prediction methods to eventually predict the best pile driving technique for each new offshore oil platform. Phase I Pile driving records of 48 offshore platforms including such information as blow counts, soil composition and pertinent construction details were digitized. In Phase II, pile driving records were statistically compared with current methods of prediction. Result was development of modular software, the CRIPS80 Software Design Analyzer System, that companies can use to evaluate other prediction procedures or other data bases.

  14. Human papillomavirus type 16 E7 oncoprotein engages but does not abrogate the mitotic spindle assembly checkpoint

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yueyang [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States); Munger, Karl, E-mail: kmunger@rics.bwh.harvard.edu [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States)

    2012-10-10

    The mitotic spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during mitosis by censoring kinetochore-microtubule interactions. It is frequently rendered dysfunctional during carcinogenesis causing chromosome missegregation and genomic instability. There are conflicting reports whether the HPV16 E7 oncoprotein drives chromosomal instability by abolishing the SAC. Here we report that degradation of mitotic cyclins is impaired in cells with HPV16 E7 expression. RNAi-mediated depletion of Mad2 or BubR1 indicated the involvement of the SAC, suggesting that HPV16 E7 expression causes sustained SAC engagement. Mutational analyses revealed that HPV16 E7 sequences that are necessary for retinoblastoma tumor suppressor protein binding as well as sequences previously implicated in binding the nuclear and mitotic apparatus (NuMA) protein and in delocalizing dynein from the mitotic spindle contribute to SAC engagement. Importantly, however, HPV16 E7 does not markedly compromise the SAC response to microtubule poisons.

  15. The spatial arrangement of chromosomes during prometaphase facilitates spindle assembly.

    Science.gov (United States)

    Magidson, Valentin; O'Connell, Christopher B; Lončarek, Jadranka; Paul, Raja; Mogilner, Alex; Khodjakov, Alexey

    2011-08-19

    Error-free chromosome segregation requires stable attachment of sister kinetochores to the opposite spindle poles (amphitelic attachment). Exactly how amphitelic attachments are achieved during spindle assembly remains elusive. We employed photoactivatable GFP and high-resolution live-cell confocal microscopy to visualize complete 3D movements of individual kinetochores throughout mitosis in nontransformed human cells. Combined with electron microscopy, molecular perturbations, and immunofluorescence analyses, this approach reveals unexpected details of chromosome behavior. Our data demonstrate that unstable lateral interactions between kinetochores and microtubules dominate during early prometaphase. These transient interactions lead to the reproducible arrangement of chromosomes in an equatorial ring on the surface of the nascent spindle. A computational model predicts that this toroidal distribution of chromosomes exposes kinetochores to a high density of microtubules which facilitates subsequent formation of amphitelic attachments. Thus, spindle formation involves a previously overlooked stage of chromosome prepositioning which promotes formation of amphitelic attachments.

  16. Spindle extraction method for ISAR image based on Radon transform

    Science.gov (United States)

    Wei, Xia; Zheng, Sheng; Zeng, Xiangyun; Zhu, Daoyuan; Xu, Gaogui

    2015-12-01

    In this paper, a method of spindle extraction of target in inverse synthetic aperture radar (ISAR) image is proposed which depends on Radon Transform. Firstly, utilizing Radon Transform to detect all straight lines which are collinear with these line segments in image. Then, using Sobel operator to detect image contour. Finally, finding all intersections of each straight line and image contour, the two intersections which have maximum distance between them is the two ends of this line segment and the longest line segment of all line segments is spindle of target. According to the proposed spindle extraction method, one hundred simulated ISAR images which are respectively rotated 0 degrees, 10 degrees, 20 degrees, 30 degrees and 40 degrees in counterclockwise are used to do experiment and the proposed method and the detection results are more close to the real spindle of target than the method based on Hough Transform .

  17. Asymmetric spindle pole formation in CPAP-depleted mitotic cells.

    Science.gov (United States)

    Lee, Miseon; Chang, Jaerak; Chang, Sunghoe; Lee, Kyung S; Rhee, Kunsoo

    2014-02-21

    CPAP is an essential component for centriole formation. Here, we report that CPAP is also critical for symmetric spindle pole formation during mitosis. We observed that pericentriolar material between the mitotic spindle poles were asymmetrically distributed in CPAP-depleted cells even with intact numbers of centrioles. The length of procentrioles was slightly reduced by CPAP depletion, but the length of mother centrioles was not affected. Surprisingly, the young mother centrioles of the CPAP-depleted cells are not fully matured, as evidenced by the absence of distal and subdistal appendage proteins. We propose that the selective absence of centriolar appendages at the young mother centrioles may be responsible for asymmetric spindle pole formation in CPAP-depleted cells. Our results suggest that the neural stem cells with CPAP mutations might form asymmetric spindle poles, which results in premature initiation of differentiation.

  18. Spindle mechanics and dynamics during mitosis in Drosophila.

    Science.gov (United States)

    Kwon, Mijung; Scholey, Jonathan M

    2004-04-01

    Drosophila melanogaster is an excellent model for studying mitosis. Syncytial embryos are amenable to time-lapse imaging of hundreds of synchronously dividing spindles, allowing the quantitation of spindle and chromosome dynamics with unprecedented fidelity. Other Drosophila cell types, including neuroblasts, cultured cells, spermatocytes and oocytes, contain spindles that differ in their design, providing cells amenable to different types of experiments and allowing identification of common core mechanisms. The function of mitotic proteins can be studied using mutants, inhibitor microinjection and RNA interference (RNAi) to identify the full inventory of mitotic proteins encoded by the genome. Here, we review recent advances in understanding how ensembles of mitotic proteins coordinate spindle assembly and chromosome motion in this system.

  19. Aurora B regulates spindle bipolarity in meiosis in vertebrate oocytes.

    Science.gov (United States)

    Shao, Hua; Ma, Chunqi; Zhang, Xuan; Li, Ruizhen; Miller, Ann L; Bement, William M; Liu, X Johné

    2012-07-15

    Aurora B (Aur-B) plays multiple roles in mitosis, of which the best known are to ensure bi-orientation of sister chromatids by destabilizing incorrectly attached kinetochore microtubules and to participate in cytokinesis. Studies in Xenopus egg extracts, however, have indicated that Aur-B and the chromosome passenger complex play an important role in stabilizing chromosome-associated spindle microtubules. Aur-B stabilizes spindle microtubules in the egg extracts by inhibiting the catastrophe kinesin MCAK. Whether or not Aur-B plays a similar role in intact oocytes remains unknown. Here we have employed a dominant-negative Aur-B mutant (Aur-B122R, in which the ATP-binding lysine(122) is replaced with arginine) to investigate the function of Aur-B in spindle assembly in Xenopus oocytes undergoing meiosis. Overexpression of Aur-B122R results in short bipolar spindles or monopolar spindles, with higher concentrations of Aur-B122R producing mostly the latter. Simultaneous inhibition of MCAK translation in oocytes overexpressing Aur-B122R results in suppression of monopolar phenotype, suggesting that Aur-B regulates spindle bipolarity by inhibiting MCAK. Furthermore, recombinant MCAK-4A protein, which lacks all four Aur-B phosphoryaltion sites and is therefore insensitive to Aur-B inhibition but not wild-type MCAK, recapitulated the monopolar phenotype in the oocytes. These results suggest that in vertebrate oocytes that lack centrosomes, one major function of Aur-B is to stabilize chromosome-associated spindle microtubules to ensure spindle bipolarity.

  20. The Spindle Unit of Machine Tool(Ⅱ)%机床的主轴单元(下)

    Institute of Scientific and Technical Information of China (English)

    张曙; 张柄生; 卫汉华

    2016-01-01

    通过回顾机床主轴发展历程,指出电主轴在高端数控机床的应用日益广泛。继而详尽地阐述了机床主轴单元的设计要点,包括轴承、润滑和冷却以及刀具接口等。接着对主轴的静动态和热性能分析以及建模仿真进行了全面介绍。最后指出主轴的工况监控、智能化和自适应控制是新一代电主轴的重要特征和未来发展趋势。%Reviewing the development of machine tool spindle, it points out that the application of motorized spindle in high-end CNC machine tools is becoming more and more widely. It shows the detail about the design key points of machine tool spindle unit such as bearing, lubrication, cooling and cutting tool interface. It illus-trates the static and dynamic and thermal performance analysis and modeling simulation for spindle unit, pre-sents the important characteristics and the future development trend in condition monitoring, intelligent and adaptive control ect.

  1. Cytogenetic Analysis of a Pseudoangiomatous Pleomorphic/Spindle Cell Lipoma.

    Science.gov (United States)

    Panagopoulos, Ioannis; Gorunova, Ludmila; Lobmaier, Ingvild; Andersen, Hege Kilen; Bjerkehagen, Bodil; Heim, Sverre

    2017-05-01

    Pseudoangiomatous pleomorphic/spindle cell lipoma is a rare subtype of pleomorphic/spindle cell lipoma. Only approximately 20 such tumors have been described. Genetic information on pseudoangiomatous pleomorphic/spindle cell lipoma is restricted to a single case in which deletion of the forkhead box O1 (FOXO1) gene was found, using fluorescence in situ hybridization (FISH). G-banding and FISH analyses were performed on a pseudoangiomatous pleomorphic/spindle cell lipoma. G-banding of tumor cells showed complex karyotypic changes including loss of chromosome 13. FISH analysis revealed that the deleted region contained the RB1 gene (13q14.2) and the part of chromosome arm 13q (q14.2-q14.3) in which spans the TRIM13 gene, the two non-coding RNA genes, DLEU1 and DLEU2, and the genetic markers RH44686 and D13S25. Several acquired genomic aberrations were found in the tumor. Among them was loss of chromosome 13 material. Results confirm the (cyto)genetic similarity between pseudoangiomatous pleomorphic/spindle cell lipoma and spindle cell lipomas. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  2. Muscle spindles in the human bulbospongiosus and ischiocavernosus muscles.

    Science.gov (United States)

    Peikert, Kevin; May, Christian Albrecht

    2015-07-01

    Muscle spindles are crucial for neuronal regulation of striated muscles, but their presence and involvement in the superficial perineal muscles is not known. Bulbospongiosus and ischiocavernosus muscle specimens were obtained from 31 human cadavers. Serial sections were stained with hematoxylin and eosin, Sirius red, antibodies against Podocalyxin, myosin heavy chain isoforms (MyHC-slow tonic, S46; MyHC-2a/2x, A4.74), and neurofilament for the purpose of muscle spindle screening, counting, and characterization. A low but consistent number of spindles were detected in both muscles. The muscles contained few intrafusal fibers, but otherwise showed normal spindle morphology. The extrafusal fibers of both muscles were small in diameter. The presence of muscle spindles in bulbospongiosus and ischiocavernosus muscles supports physiological models of pelvic floor regulation and may provide a basis for further clinical observations regarding sexual function and micturition. The small number of muscle spindles points to a minor level of proprioceptive regulation. © 2014 Wiley Periodicals, Inc.

  3. Evaluation of Friction Torque and Heat Quantity Generated in Spindle (1st Report) : Development of Evaluation System and Evaluation of Air Spindle Characteristics

    OpenAIRE

    横山, 和宏; 鈴木, 孝昌; 平倉, 隆史; 森脇, 俊道; Yokoyama, Kazuhiro; Suzuki, Takamasa; Hirakura, Takashi; Moriwaki, Toshimichi

    1995-01-01

    This paper presents a new method to evaluate the friction torque and the heat quantity generated in a spindle system. The decrease in the rotational speed of spindle during the free run period is precisely measured, and the angular deceleration is calculated. The heat quantity generated during the spindle rotation is evaluated as the product of the moment of inertia of spindle, the angular deceleration and the angular velocity. A device is newly developed to measure the rotational speed of sp...

  4. The Maize Divergent spindle-1 (dv1) Gene Encodes a Kinesin-14A Motor Protein Required for Meiotic Spindle Pole Organization

    OpenAIRE

    Higgins, David M.; Nannas, Natalie J.; R Kelly Dawe

    2016-01-01

    The classic maize mutant divergent spindle-1 (dv1) causes failures in meiotic spindle assembly and a decrease in pollen viability. By analyzing two independent dv1 alleles we demonstrate that this phenotype is caused by mutations in a member of the kinesin-14A subfamily, a class of C-terminal, minus-end directed microtubule motors. Further analysis demonstrates that defects in early spindle assembly are rare, but that later stages of spindle organization promoting the formation of finely focu...

  5. Road Safety Data, Collection, Transfer and Analysis DaCoTa. Workpackage 6, Driver Behaviour Monitoring through Naturalistic Driving: Deliverable 6.2: Part B: Sampling techniques and naturalistic driving study design.

    NARCIS (Netherlands)

    Commandeur, J.J.F.

    2015-01-01

    In this document we provide an overview of sampling and estimation methods that can be used to obtain population values of risk exposure data and safety performance indicators based on naturalistic driving study designs. More specifically, we discuss how to determine the optimal sample size required

  6. Microcephaly protein Asp focuses the minus ends of spindle microtubules at the pole and within the spindle.

    Science.gov (United States)

    Ito, Ami; Goshima, Gohta

    2015-12-07

    Depletion of Drosophila melanogaster Asp, an orthologue of microcephaly protein ASPM, causes spindle pole unfocusing during mitosis. However, it remains unclear how Asp contributes to pole focusing, a process that also requires the kinesin-14 motor Ncd. We show that Asp localizes to the minus ends of spindle microtubule (MT) bundles and focuses them to make the pole independent of Ncd. We identified a critical domain in Asp exhibiting MT cross-linking activity in vitro. Asp was also localized to, and focuses the minus ends of, intraspindle MTs that were nucleated in an augmin-dependent manner and translocated toward the poles by spindle MT flux. Ncd, in contrast, functioned as a global spindle coalescence factor not limited to MT ends. We propose a revised molecular model for spindle pole focusing in which Asp at the minus ends cross-links MTs at the pole and within the spindle. Additionally, this study provides new insight into the dynamics of intraspindle MTs by using Asp as a minus end marker. © 2015 Ito and Goshima.

  7. Vibro-Acoustic Model of a Disk Drive

    Science.gov (United States)

    Lee, Ming-Ran; Singh, Rajendra

    A new mathematical model of the vibro-acoustic characteristics of a computer hard-disk drive is presented in this paper. In particular, a mobility transfer function is defined that links sound radiated by a stationary or rotating disk to electromagnetic torque pulsations and structural dynamics. A simplified disk-drive system consisting of a brushless d.c. motor driving a single disk-spindle assembly, which is mounted on a flexible casing, is considered as the example case. Parametric studies illustrate the roles of bearing stiffness and disk geometry on the vibration and radiated sound.

  8. Balanced Activity of Three Mitotic Motors Is Required for Bipolar Spindle Assembly and Chromosome Segregation

    Directory of Open Access Journals (Sweden)

    Roy G.H.P. van Heesbeen

    2014-08-01

    Full Text Available Bipolar spindle assembly requires force to organize the microtubule network. Here, we show that three motor proteins, namely Eg5, Kif15, and dynein, act together to produce the right force balance in the spindle. Excessive inward force results in monopolar spindle formation, while excessive outward force generation results in unstable spindles with splayed spindle poles. Blocking activity of all three motors prevents bipolar spindle formation, but established bipolar spindles are refractory to loss of all motor activity. Further analysis shows that although these preformed spindles remain bipolar, outward force generation is required to establish sufficient tension on kinetochores and to accomplish successful chromosome segregation. Together, these results show how Eg5, Kif15, and dynein work together to build a bipolar spindle and reveal an important role for antagonistic motors in chromosome segregation.

  9. Topography-specific spindle frequency changes in Obstructive Sleep Apnea

    Directory of Open Access Journals (Sweden)

    V Suzana

    2012-07-01

    Full Text Available Abstract Background Sleep spindles, as detected on scalp electroencephalography (EEG, are considered to be markers of thalamo-cortical network integrity. Since obstructive sleep apnea (OSA is a known cause of brain dysfunction, the aim of this study was to investigate sleep spindle frequency distribution in OSA. Seven non-OSA subjects and 21 patients with OSA (11 mild and 10 moderate were studied. A matching pursuit procedure was used for automatic detection of fast (≥13Hz and slow (Hz spindles obtained from 30min samples of NREM sleep stage 2 taken from initial, middle and final night thirds (sections I, II and III of frontal, central and parietal scalp regions. Results Compared to non-OSA subjects, Moderate OSA patients had higher central and parietal slow spindle percentage (SSP in all night sections studied, and higher frontal SSP in sections II and III. As the night progressed, there was a reduction in central and parietal SSP, while frontal SSP remained high. Frontal slow spindle percentage in night section III predicted OSA with good accuracy, with OSA likelihood increased by 12.1%for every SSP unit increase (OR 1.121, 95% CI 1.013 - 1.239, p=0.027. Conclusions These results are consistent with diffuse, predominantly frontal thalamo-cortical dysfunction during sleep in OSA, as more posterior brain regions appear to maintain some physiological spindle frequency modulation across the night. Displaying changes in an opposite direction to what is expected from the aging process itself, spindle frequency appears to be informative in OSA even with small sample sizes, and to represent a sensitive electrophysiological marker of brain dysfunction in OSA.

  10. Distracted Driving

    Science.gov (United States)

    ... What's this? Submit What's this? Submit Button Distracted Driving Recommend on Facebook Tweet Share Compartir Each day in the United States, over 8 people are killed and 1,161 injured in crashes ...

  11. DRIVING GREEN

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    China is promoting environmentally friendly cars to save energy and protect the environment While people enjoy the pleasure and convenience of driving, they are also creating and breathing more and more toxic

  12. Signal transmission from motor axons to group Ia muscle spindle afferents: frequency responses and second-order non-linearities.

    Science.gov (United States)

    Windhorst, U; Kokkoroyiannis, T; Laouris, Y; Meyer-Lohmann, J

    1994-03-01

    hypothesis that the two feedback pathways monitor different state variables determining the production of muscle force: neural input and length and its changes. Specifically, the dynamic properties of both subsystems may combine favourably to decrease the risk of instability (tremor) in the motoneuron-muscle spindle loop.

  13. Characteristics of motorized spindle supported by active magnetic bearings

    Institute of Scientific and Technical Information of China (English)

    Xie Zhenyu; Yu Kun; Wen Liantang; Wang Xiao; Zhou Hongkai

    2014-01-01

    A motorized spindle supported by active magnetic bearings (AMBs) is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spin-dle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic char-acteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.

  14. Spindle neurons of the human anterior cingulate cortex

    Science.gov (United States)

    Nimchinsky, E. A.; Vogt, B. A.; Morrison, J. H.; Hof, P. R.; Bloom, F. E. (Principal Investigator)

    1995-01-01

    The human anterior cingulate cortex is distinguished by the presence of an unusual cell type, a large spindle neuron in layer Vb. This cell has been noted numerous times in the historical literature but has not been studied with modern neuroanatomic techniques. For instance, details regarding the neuronal class to which these cells belong and regarding their precise distribution along both ventrodorsal and anteroposterior axes of the cingulate gyrus are still lacking. In the present study, morphological features and the anatomic distribution of this cell type were studied using computer-assisted mapping and immunocytochemical techniques. Spindle neurons are restricted to the subfields of the anterior cingulate cortex (Brodmann's area 24), exhibiting a greater density in anterior portions of this area than in posterior portions, and tapering off in the transition zone between anterior and posterior cingulate cortex. Furthermore, a majority of the spindle cells at any level is located in subarea 24b on the gyral surface. Immunocytochemical analysis revealed that the neurofilament protein triple was present in a large percentage of these neurons and that they did not contain calcium-binding proteins. Injections of the carbocyanine dye DiI into the cingulum bundle revealed that these cells are projection neurons. Finally, spindle cells were consistently affected in Alzheimer's disease cases, with an overall loss of about 60%. Taken together, these observations indicate that the spindle cells of the human cingulate cortex represent a morphological subpopulation of pyramidal neurons whose restricted distribution may be associated with functionally distinct areas.

  15. Regulation of cell cycle by the anaphase spindle midzone

    Directory of Open Access Journals (Sweden)

    Sluder Greenfield

    2004-12-01

    Full Text Available Abstract Background A number of proteins accumulate in the spindle midzone and midbody of dividing animal cells. Besides proteins essential for cytokinesis, there are also components essential for interphase functions, suggesting that the spindle midzone and/or midbody may play a role in regulating the following cell cycle. Results We microsurgically severed NRK epithelial cells during anaphase or telophase, such that the spindle midzone/midbody was associated with only one of the daughter cells. Time-lapse recording of cells severed during early anaphase indicated that the cell with midzone underwent cytokinesis-like cortical contractions and progressed normally through the interphase, whereas the cell without midzone showed no cortical contraction and an arrest or substantial delay in the progression of interphase. Similar microsurgery during telophase showed a normal progression of interphase for both daughter cells with or without the midbody. Microsurgery of anaphase cells treated with cytochalasin D or nocodazole indicated that interphase progression was independent of cortical ingression but dependent on microtubules. Conclusions We conclude that the mitotic spindle is involved in not only the separation of chromosomes but also the regulation of cell cycle. The process may involve activation of components in the spindle midzone that are required for the cell cycle, and/or degradation of components that are required for cytokinesis but may interfere with the cell cycle.

  16. Characteristics of motorized spindle supported by active magnetic bearings

    Directory of Open Access Journals (Sweden)

    Xie Zhenyu

    2014-12-01

    Full Text Available A motorized spindle supported by active magnetic bearings (AMBs is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spindle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic characteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.

  17. Spindle Activity Orchestrates Plasticity during Development and Sleep

    Directory of Open Access Journals (Sweden)

    Christoph Lindemann

    2016-01-01

    Full Text Available Spindle oscillations have been described during early brain development and in the adult brain. Besides similarities in temporal patterns and involved brain areas, neonatal spindle bursts (NSBs and adult sleep spindles (ASSs show differences in their occurrence, spatial distribution, and underlying mechanisms. While NSBs have been proposed to coordinate the refinement of the maturating neuronal network, ASSs are associated with the implementation of acquired information within existing networks. Along with these functional differences, separate synaptic plasticity mechanisms seem to be recruited. Here, we review the generation of spindle oscillations in the developing and adult brain and discuss possible implications of their differences for synaptic plasticity. The first part of the review is dedicated to the generation and function of ASSs with a particular focus on their role in healthy and impaired neuronal networks. The second part overviews the present knowledge of spindle activity during development and the ability of NSBs to organize immature circuits. Studies linking abnormal maturation of brain wiring with neurological and neuropsychiatric disorders highlight the importance to better elucidate neonatal plasticity rules in future research.

  18. Calculation and structural analysis for the rigidity of air spindle in the single point diamond turning lathe

    Science.gov (United States)

    An, Chenhui; Xu, Qiao; Zhang, Feihu; Zhang, Jianfeng

    2007-12-01

    Ultra-precision machining for optical lens is a key subject in the field of modern optics machining, the focus of which is the higher demands for profile precision and surface roughness. As a kind of deterministic machining, the single point diamond turning lathe is widely used in the optical field, thus higher stabilization for the turning lathe is required with small amplitude of vibrations in a broad frequency-domain. The single point diamond turning lathe now boast its various forms both at home and abroad, and the vertical flying cutting milling style is an important branch. This kind of lathe is characterized with low guide rail velocity and main errors of this part are the alignment error of guide rail, the disturbance evolved by driving components, and the low velocity crawl. Such errors are presented as low-frequency profile error on the workpiece surface, and often relate to the guide rail velocity. The rotate speed of the spindle is higher comparatively, and the system is composed as a vibration element with mass, air-rigidity, air-damping and the periodicity impact vibration. As a result, this vibration can copy to the work piece by the tool nose in machining process, so we must manage to reduce the vibration for high machining precision. This paper is to deduce the proper dynamic parameter for reducing the spindle vibration and optimize the spindle structure via dynamic calculation for the diamond turning lathes used and bring forward the reformative idea for the lathes.

  19. Human Nek7-interactor RGS2 is required for mitotic spindle organization.

    Science.gov (United States)

    de Souza, Edmarcia Elisa; Hehnly, Heidi; Perez, Arina Marina; Meirelles, Gabriela Vaz; Smetana, Juliana Helena Costa; Doxsey, Stephen; Kobarg, Jörg

    2015-01-01

    The mitotic spindle apparatus is composed of microtubule (MT) networks attached to kinetochores organized from 2 centrosomes (a.k.a. spindle poles). In addition to this central spindle apparatus, astral MTs assemble at the mitotic spindle pole and attach to the cell cortex to ensure appropriate spindle orientation. We propose that cell cycle-related kinase, Nek7, and its novel interacting protein RGS2, are involved in mitosis regulation and spindle formation. We found that RGS2 localizes to the mitotic spindle in a Nek7-dependent manner, and along with Nek7 contributes to spindle morphology and mitotic spindle pole integrity. RGS2-depletion leads to a mitotic-delay and severe defects in the chromosomes alignment and congression. Importantly, RGS2 or Nek7 depletion or even overexpression of wild-type or kinase-dead Nek7, reduced γ-tubulin from the mitotic spindle poles. In addition to causing a mitotic delay, RGS2 depletion induced mitotic spindle misorientation coinciding with astral MT-reduction. We propose that these phenotypes directly contribute to a failure in mitotic spindle alignment to the substratum. In conclusion, we suggest a molecular mechanism whereupon Nek7 and RGS2 may act cooperatively to ensure proper mitotic spindle organization.

  20. A tumor suppressor role of the Bub3 spindle checkpoint protein after apoptosis inhibition

    Science.gov (United States)

    Moutinho-Santos, Tatiana

    2013-01-01

    Most solid tumors contain aneuploid cells, indicating that the mitotic checkpoint is permissive to the proliferation of chromosomally aberrant cells. However, mutated or altered expression of mitotic checkpoint genes accounts for a minor proportion of human tumors. We describe a Drosophila melanogaster tumorigenesis model derived from knocking down spindle assembly checkpoint (SAC) genes and preventing apoptosis in wing imaginal discs. Bub3-deficient tumors that were also deficient in apoptosis displayed neoplastic growth, chromosomal aneuploidy, and high proliferative potential after transplantation into adult flies. Inducing aneuploidy by knocking down CENP-E and preventing apoptosis does not induce tumorigenesis, indicating that aneuploidy is not sufficient for hyperplasia. In this system, the aneuploidy caused by a deficient SAC is not driving tumorigenesis because preventing Bub3 from binding to the kinetochore does not cause hyperproliferation. Our data suggest that Bub3 has a nonkinetochore-dependent function that is consistent with its role as a tumor suppressor. PMID:23609535

  1. An Overview of the Spindle Assembly Checkpoint Status in Oral Cancer

    Directory of Open Access Journals (Sweden)

    José Henrique Teixeira

    2014-01-01

    Full Text Available Abnormal chromosome number, or aneuploidy, is a common feature of human solid tumors, including oral cancer. Deregulated spindle assembly checkpoint (SAC is thought as one of the mechanisms that drive aneuploidy. In normal cells, SAC prevents anaphase onset until all chromosomes are correctly aligned at the metaphase plate thereby ensuring genomic stability. Significantly, the activity of this checkpoint is compromised in many cancers. While mutations are rather rare, many tumors show altered expression levels of SAC components. Genomic alterations such as aneuploidy indicate a high risk of oral cancer and cancer-related mortality, and the molecular basis of these alterations is largely unknown. Yet, our knowledge on the status of SAC components in oral cancer remains sparse. In this review, we address the state of our knowledge regarding the SAC defects and the underlying molecular mechanisms in oral cancer, and discuss their therapeutic relevance, focusing our analysis on the core components of SAC and its target Cdc20.

  2. Adaptive changes in the kinetochore architecture facilitate proper spindle assembly.

    Science.gov (United States)

    Magidson, Valentin; Paul, Raja; Yang, Nachen; Ault, Jeffrey G; O'Connell, Christopher B; Tikhonenko, Irina; McEwen, Bruce F; Mogilner, Alex; Khodjakov, Alexey

    2015-09-01

    Mitotic spindle formation relies on the stochastic capture of microtubules at kinetochores. Kinetochore architecture affects the efficiency and fidelity of this process with large kinetochores expected to accelerate assembly at the expense of accuracy, and smaller kinetochores to suppress errors at the expense of efficiency. We demonstrate that on mitotic entry, kinetochores in cultured human cells form large crescents that subsequently compact into discrete structures on opposite sides of the centromere. This compaction occurs only after the formation of end-on microtubule attachments. Live-cell microscopy reveals that centromere rotation mediated by lateral kinetochore-microtubule interactions precedes the formation of end-on attachments and kinetochore compaction. Computational analyses of kinetochore expansion-compaction in the context of lateral interactions correctly predict experimentally observed spindle assembly times with reasonable error rates. The computational model suggests that larger kinetochores reduce both errors and assembly times, which can explain the robustness of spindle assembly and the functional significance of enlarged kinetochores.

  3. Spindle cell lesions of the breast - An approach to diagnosis.

    Science.gov (United States)

    Tay, Timothy Kwang Yong; Tan, Puay Hoon

    2017-09-01

    Spindle cell lesions of the breast are among the less common entities encountered in breast pathology. They encompass a whole spectrum of benign reactive lesions to high grade malignant neoplasms. An accurate diagnosis is important to ensure that the patient receives the appropriate management. While this group of conditions broadly share the same basic morphology of a lesion composed of spindle cells, there are often recognizable differences on histology, which coupled with ancillary studies and correlation with the clinical and imaging findings, can help one to arrive at a specific diagnosis. On core biopsy however, spindle cell lesions pose significant interpretive challenges and a firm diagnosis is often not possible. We share our approach to this group of conditions, with a focus on the more common entities, highlighting their key clinical, imaging and pathological features. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Kinetochore flexibility: creating a dynamic chromosome-spindle interface.

    Science.gov (United States)

    O'Connell, Christopher B; Khodjakov, Alexey; McEwen, Bruce F

    2012-02-01

    Kinetochores are complex macromolecular assemblies that link chromosomes to the mitotic spindle, mediate forces for chromosome motion, and generate the checkpoint signal delaying anaphase onset until all chromosomes are incorporated into the spindle. Proper execution of these functions depends on precise interactions between kinetochores and microtubules. While the molecular composition of the kinetochore is well described, structural organization of this organelle at the molecular and atomic levels is just beginning to emerge. Recent structural studies across scales suggest that kinetochores should not be viewed as rigid static scaffolds. Instead, these organelles exhibit a surprising degree of flexibility that enables rapid adaptations to various types of interactions with the mitotic spindle. Copyright © 2012 Elsevier Ltd. All rights reserved.

  5. Reflex changes in muscle spindle discharge during a voluntary contraction.

    Science.gov (United States)

    Aniss, A M; Gandevia, S C; Burke, D

    1988-03-01

    1. This study was undertaken to determine whether low-threshold cutaneous and muscle afferents from mechanoreceptors in the foot reflexly affect fusimotor neurons innervating the plantar and dorsiflexors of the ankle during voluntary contractions. 2. Recordings were made from 29 identified muscle spindle afferents innervating triceps surae and the pretibial flexors. Trains of electrical stimuli (5 stimuli, 300 impulses per second) were delivered to the sural nerve at the ankle (intensity: 2-4 times sensory threshold) and to the posterior tibial nerve at the ankle (intensity: 1.5-3 times motor threshold for the small muscles of the foot). The stimuli were delivered while the subject maintained an isometric voluntary contraction of the receptor-bearing muscle, sufficient to accelerate the discharge of each spindle ending. This ensured that the fusimotor neurons directed to the ending were active and influencing the spindle discharge. The effects of these stimuli on muscle spindle discharge were assessed using raster displays, frequencygrams, poststimulus time histograms (PSTHs) and cumulative sums ("CUSUMs") of the PSTHs. Reflex effects onto alpha-motoneurons were determined from poststimulus changes in the averaged rectified electromyogram (EMG). Reflex effects of these stimuli onto single-motor units were assessed in separate experiments using PSTHs and CUSUMs. 3. Electrical stimulation of the sural or posterior tibial nerves at nonnoxious levels had no significant effect on the discharge of the 14 spindle endings in the pretibial flexor muscles. The electrical stimuli also produced no significant change in discharge of 11 of 15 spindle endings in triceps surae. With the remaining four endings in triceps surae, the overall change in discharge appeared to be an increase for two endings (at latencies of 60 and 68 ms) and a decrease for two endings (at latencies of 110 and 150 ms). The difference in the incidence of the responses of spindle endings in tibialis

  6. Regional Slow Waves and Spindles in Human Sleep

    Science.gov (United States)

    Nir, Yuval; Staba, Richard J.; Andrillon, Thomas; Vyazovskiy, Vladyslav V.; Cirelli, Chiara; Fried, Itzhak; Tononi, Giulio

    2011-01-01

    SUMMARY The most prominent EEG events in sleep are slow waves, reflecting a slow (waves and the underlying active and inactive neuronal states occur locally. Thus, especially in late sleep, some regions can be active while others are silent. We also find that slow waves can propagate, usually from medial prefrontal cortex to the medial temporal lobe and hippocampus. Sleep spindles, the other hallmark of NREM sleep EEG, are likewise predominantly local. Thus, intracerebral communication during sleep is constrained because slow and spindle oscillations often occur out-of-phase in different brain regions. PMID:21482364

  7. Acentrosomal spindle assembly and chromosome segregation during oocyte meiosis.

    Science.gov (United States)

    Dumont, Julien; Desai, Arshad

    2012-05-01

    The ability to reproduce relies in most eukaryotes on specialized cells called gametes. Gametes are formed by the process of meiosis in which, after a single round of replication, two successive cell divisions reduce the ploidy of the genome. Fusion of gametes at fertilization reconstitutes diploidy. In most animal species, chromosome segregation during female meiosis occurs on spindles assembled in the absence of the major microtubule-organizing center, the centrosome. In mammals, oocyte meiosis is error prone and underlies most birth aneuploidies. Here, we review recent work on acentrosomal spindle formation and chromosome alignment/separation during oocyte meiosis in different animal models.

  8. Force encoding in muscle spindles during stretch of passive muscle.

    Science.gov (United States)

    Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

    2017-09-01

    Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

  9. Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.

  10. An automatic sleep spindle detector based on wavelets and the teager energy operator.

    Science.gov (United States)

    Ahmed, Beena; Redissi, Amira; Tafreshi, Reza

    2009-01-01

    Sleep spindles are one of the most important short-lasting rhythmic events occurring in the EEG during Non-Rapid Eye Movement sleep. Their accurate identification in a polysomnographic signal is essential for sleep professionals to help them mark Stage 2 sleep. Visual spindle scoring however is a tedious workload, as there are often a thousand spindles in an all-night recording. In this paper a novel approach for the automatic detection of sleep spindles based upon the Teager Energy Operator and wavelet packets has been presented. The Teager operator was found to accurately enhance periodic activity in epochs of the EEG containing spindles. The wavelet packet transform proved effective in accurately locating spindles in the time-frequency domain. The autocorrelation function of the resultant Teager signal and the wavelet packet energy ratio were used to identify epochs with spindles. These two features were integrated into a spindle detection algorithm which achieved an accuracy of 93.7%.

  11. Time-frequency analysis and detecting method research on milling force token signal in spindle current signal

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The vast majority of tool condition monitoring systems use the motor current instead of the cutting force as the predictor signal. The measured motor current signal is time-dependant and instable. It is difficult to detect the cutting force token signal from such motor current signal. This paper presents a method that uses the wavelet transforms to reconstruct the cutting force token signal from the current signal based on the time frequency analysis of the cutting force signal. The result of the cutting force measurement experiment shows that the proposed reconstruct method could be used to analyze the spindle current and monitor the time-varying cutting force.

  12. Death Drive

    OpenAIRE

    Stühler, Rebekka Hellstrøm

    2012-01-01

    The aim of this project is to investigate why the Freudian term Death Drive is not acknowledged in modern psychological therapy. On basis of psychoanalytical theory and through a literary analysis, the project will present a discussion of the significance and presence of the term within these practises.

  13. The chromosomal passenger complex and the spindle assembly checkpoint: kinetochore-microtubule error correction and beyond

    OpenAIRE

    Maia André F; Vader Gerben; Lens Susanne MA

    2008-01-01

    Abstract During mitosis, correct bipolar chromosome attachment to the mitotic spindle is an essential prerequisite for the equal segregation of chromosomes. The spindle assembly checkpoint can prevent chromosome segregation as long as not all chromosome pairs have obtained bipolar attachment to the spindle. The chromosomal passenger complex plays a crucial role during chromosome alignment by correcting faulty chromosome-spindle interactions (e.g. attachments that do not generate tension). In ...

  14. Involvement of Spindles in Memory Consolidation Is Slow Wave Sleep-Specific

    Science.gov (United States)

    Cox, Roy; Hofman, Winni F.; Talamini, Lucia M.

    2012-01-01

    Both sleep spindles and slow oscillations have been implicated in sleep-dependent memory consolidation. Whereas spindles occur during both light and deep sleep, slow oscillations are restricted to deep sleep, raising the possibility of greater consolidation-related spindle involvement during deep sleep. We assessed declarative memory retention…

  15. Development of a Spindle Thermal Error Characterization and Compensation Sensor System for Machining Center Accuracy Enhancement

    Science.gov (United States)

    1993-12-01

    vertical spindle CNC machining center, "* a Sundstrand series 20 Omnimill horizontal spindle CNC machining center, * a Producto A-1738 vertical spindle CNC...hardware and software developed during this program have been successfully commercialized by API. Currently API is marketing this system under the trade name

  16. Experimental study on bearing preload optimum of machine tool spindle

    Science.gov (United States)

    Xu, Tao; Xu, Guanghua; Zhang, Qin; Hua, Cheng; Zhang, Hu; Jiang, Kuosheng

    2012-05-01

    An experimental study is conducted to investigate the possibility and the effect of temperature rise and vibration level of bearing by adjusting axial preloads and radial loads in spindle bearing test rig. The shaft of the test rig is driven by a motorized high speed spindle at the range of 0~20000 rpm. The axial preloads and radial loads on bearings are controlled by using hydraulic pressure which can be adjusted automatically. Temperature rise and radial vibration of test bearings are measured by thermocouples and Polytec portable laser vibrometer PDV100. Experiment shows that the temperature rise of bearings is nonlinear varying with the increase of radial loads, but temperature rise almost increases linearly with the increase of axial preload and rotating speed. In this paper, an alternate axial preload is used for bearings. When the rotating speed passes through the critical speed of the shaft, axial preload of bearings will have a remarkable effect. The low preload could reduce bearing vibration and temperature rise for bearings as well. At the others speed, the high preload could improve the vibration performance of high speed spindle and the bearing temperature was lower than that of the constant pressure preload spindle.

  17. Sleep spindle alterations in patients with Parkinson's disease

    DEFF Research Database (Denmark)

    Christensen, Julie Anja Engelhard; Nikolic, Miki; Warby, Simon C.;

    2015-01-01

    The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score...

  18. Sleep spindle alterations in patients with Parkinson's disease

    DEFF Research Database (Denmark)

    Christensen, Julie Anja Engelhard; Nikolic, Miki; Warby, Simon C.

    2015-01-01

    The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score...

  19. Kinetochore-microtubule attachment is sufficient to satisfy the human spindle assembly checkpoint.

    Science.gov (United States)

    Etemad, Banafsheh; Kuijt, Timo E F; Kops, Geert J P L

    2015-12-01

    The spindle assembly checkpoint (SAC) is a genome surveillance mechanism that protects against aneuploidization. Despite profound progress on understanding mechanisms of its activation, it remains unknown what aspect of chromosome-spindle interactions is monitored by the SAC: kinetochore-microtubule attachment or the force generated by dynamic microtubules that signals stable biorientation of chromosomes? To answer this, we uncoupled these two processes by expressing a non-phosphorylatable version of the main microtubule-binding protein at kinetochores (HEC1-9A), causing stabilization of incorrect kinetochore-microtubule attachments despite persistent activity of the error-correction machinery. The SAC is fully functional in HEC1-9A-expressing cells, yet cells in which chromosomes cannot biorient but are stably attached to microtubules satisfy the SAC and exit mitosis. SAC satisfaction requires neither intra-kinetochore stretching nor dynamic microtubules. Our findings support the hypothesis that in human cells the end-on interactions of microtubules with kinetochores are sufficient to satisfy the SAC without the need for microtubule-based pulling forces.

  20. Membrane Bistability in Thalamic Reticular Neurons During Spindle Oscillations

    Science.gov (United States)

    Fuentealba, Pablo; Timofeev, Igor; Bazhenov, Maxim; Sejnowski, Terrence J.; Steriade, Mircea

    2010-01-01

    The thalamic reticular (RE) nucleus is a major source of inhibition in the thalamus. It plays a crucial role in regulating the excitability of thalamocortical networks and in generating some sleep rhythms. Current-clamp intracellular recordings of RE neurons in cats under barbiturate anesthesia revealed the presence of membrane bistability in ~20% of neurons. Bistability consisted of two alternate membrane potentials, separated by ~17–20 mV. While non-bistable (common) RE neurons fired rhythmic spike-bursts during spindles, bistable RE neurons fired tonically, with burst modulation, throughout spindle sequences. Bistability was strongly voltage dependent and only expressed under resting conditions (i.e. no current injection). The transition from the silent to the active state was a regenerative event that could be activated by brief depolarization, whereas brief hyperpolarizations could switch the membrane potential from the active to the silent state. These effects outlasted the current pulses. Corticothalamic stimulation could also switch the membrane potential from silent to active states. Addition of QX-314 in the recording micropipette either abolished or disrupted membrane bistability, suggesting INa(p) to be responsible for its generation. Thalamocortical cells presented various patterns of spindling that reflected the membrane bistability in RE neurons. Finally, experimental data and computer simulations predicted a role for RE neurons’ membrane bistability in inducing various patterns of spindling in target thalamocortical cells. We conclude that membrane bistability of RE neurons is an intrinsic property, likely generated by INa(p) and modulated by cortical influences, as well as a factor that determines different patterns of spindle rhythms in thalamocortical neurons. PMID:15331618

  1. 基于垂直两点法的电主轴回转精度分析%Two Rotary Precision Analysis Method Based on Vertical Spindle

    Institute of Scientific and Technical Information of China (English)

    陆峰; 沈鸿波; 张啸飞; 张丽秀; 吴玉厚; 张珂

    2014-01-01

    应用垂直两点法设计测试系统,对电主轴回转精度进行动态测量。该系统主要由标准棒、高精度非接触式电涡流传感器组成。通过建立误差分离数学模型,对垂直两点法测量电主轴回转精度进行分析,利用垂直两点法分离误差方法对实验数据进行处理,得到电主轴在不同转速下的回转精度,研究表明电主轴转速在10000 r/min以上时回转误差较小并趋于稳定,找出影响电主轴回转精度的因素并进行了归纳。对电主轴回转精度在线监测和转速控制提供了重要的理论、实验依据。%Application of vertical two-point method designed to test systems for electric spindle rotation ac-curacy dynamic measurement. The system consists of standard bars, high-precision non-contact eddy current sensor. Analyzed by a mathematical model to establish error separation, measurement of two spindle rotation accuracy. The use of two isolated error method for processing the experimental data obtained spindle rotation accuracy at different speeds. Studies have shown that when the spindle speed of 10,000 rpm rotational error is small and tends to be more stable. Identify the factors that affect the accuracy of spindle rotation and sum-marized. Spindle rotation accuracy on-line monitoring and speed control provides an important theoretical, experimental basis.

  2. The Maize Divergent spindle-1 (dv1) Gene Encodes a Kinesin-14A Motor Protein Required for Meiotic Spindle Pole Organization.

    Science.gov (United States)

    Higgins, David M; Nannas, Natalie J; Dawe, R Kelly

    2016-01-01

    The classic maize mutant divergent spindle-1 (dv1) causes failures in meiotic spindle assembly and a decrease in pollen viability. By analyzing two independent dv1 alleles we demonstrate that this phenotype is caused by mutations in a member of the kinesin-14A subfamily, a class of C-terminal, minus-end directed microtubule motors. Further analysis demonstrates that defects in early spindle assembly are rare, but that later stages of spindle organization promoting the formation of finely focused spindle poles are strongly dependent on Dv1. Anaphase is error-prone in dv1 lines but not severely so, and the majority of cells show normal chromosome segregation. Live-cell imaging of wild type and mutant plants carrying CFP-tagged β-tubulin confirm that meiosis in dv1 lines fails primarily at the pole-sharpening phase of spindle assembly. These data indicate that plant kinesin-14A proteins help to enforce bipolarity by focusing spindle poles and that this stage of spindle assembly is not required for transition through the spindle checkpoint but improves the accuracy of chromosome segregation.

  3. The maize Divergent spindle-1 (dv1 gene encodes a kinesin-14A motor protein required for meiotic spindle pole organization

    Directory of Open Access Journals (Sweden)

    David M Higgins

    2016-08-01

    Full Text Available The classic maize mutant divergent spindle-1 (dv1 causes failures in meiotic spindle assembly and a decrease in pollen viability. By analyzing two independent dv1 alleles we demonstrate that this phenotype is caused by mutations in a member of the kinesin-14A subfamily, a class of C-terminal, minus-end directed microtubule motors. Further analysis demonstrates that defects in early spindle assembly are rare, but that later stages of spindle organization promoting the formation of finely focused spindle poles are strongly dependent on Dv1. Anaphase is error-prone in dv1 lines but not severely so, and the majority of cells show normal chromosome segregation. Live-cell imaging of wild type and mutant plants carrying CFP-tagged β-tubulin confirm that meiosis in dv1 lines fails primarily at the pole-sharpening phase of spindle assembly. These data indicate that plant kinesin-14A proteins help to enforce bipolarity by focusing spindle poles and that this stage of spindle assembly is not required for transition through the spindle checkpoint but improves the accuracy of chromosome segregation.

  4. A Bipolar Spindle of Antiparallel ParM Filaments Drives Bacterial Plasmid Segregation

    DEFF Research Database (Denmark)

    Gayathri, P; Fujii, T; Møller-Jensen, Jakob;

    2012-01-01

    To ensure their stable inheritance by daughter cells during cell division, bacterial low copy-number plasmids make simple DNA segregating machines that use an elongating protein filament between sister plasmids. In the ParMRC system of Escherichia coli R1 plasmid, ParM, an actin-like protein, forms...

  5. CPAP Treatment Partly Normalizes Sleep Spindle Features in Obstructive Sleep Apnea

    Science.gov (United States)

    Saunamäki, Tiia; Huupponen, Eero; Loponen, Juho

    2017-01-01

    Objective. Obstructive sleep apnea (OSA) decreases sleep spindle density and frequency. We evaluated the effects of continuous positive airway pressure (CPAP) treatment on different features of sleep spindles. Methods. Twenty OSA patients underwent two night polysomnographies in a diagnostic phase and one night polysomnography after 6 months of CPAP treatment. The control group comprised 20 healthy controls. Sleep spindles were analyzed by a previously developed automated method. Unilateral and bilateral spindles were identified in central and frontopolar brain locations. Spindle density and frequency were determined for the first and last half of the NREM time. Results. The density of bilateral central spindles, which did not change in the untreated OSA patients, increased towards the morning hours during CPAP treatment and in the controls. Central spindles did not become faster with sleep in OSA patients and the central spindles remained slow in the left hemisphere even with CPAP. Conclusion. CPAP treatment normalized spindle features only partially. The changes may be associated with deficits in thalamocortical spindle generating loops. Significance. This study shows that some sleep spindle changes persist after CPAP treatment in OSA patients. The association of these changes to daytime symptoms in OSA patients needs to be further evaluated. PMID:28261503

  6. Physical determinants of bipolar mitotic spindle assembly and stability in fission yeast

    Science.gov (United States)

    Blackwell, Robert; Edelmaier, Christopher; Sweezy-Schindler, Oliver; Lamson, Adam; Gergely, Zachary R.; O’Toole, Eileen; Crapo, Ammon; Hough, Loren E.; McIntosh, J. Richard; Glaser, Matthew A.; Betterton, Meredith D.

    2017-01-01

    Mitotic spindles use an elegant bipolar architecture to segregate duplicated chromosomes with high fidelity. Bipolar spindles form from a monopolar initial condition; this is the most fundamental construction problem that the spindle must solve. Microtubules, motors, and cross-linkers are important for bipolarity, but the mechanisms necessary and sufficient for spindle assembly remain unknown. We describe a physical model that exhibits de novo bipolar spindle formation. We began with physical properties of fission-yeast spindle pole body size and microtubule number, kinesin-5 motors, kinesin-14 motors, and passive cross-linkers. Our model results agree quantitatively with our experiments in fission yeast, thereby establishing a minimal system with which to interrogate collective self-assembly. By varying the features of our model, we identify a set of functions essential for the generation and stability of spindle bipolarity. When kinesin-5 motors are present, their bidirectionality is essential, but spindles can form in the presence of passive cross-linkers alone. We also identify characteristic failed states of spindle assembly—the persistent monopole, X spindle, separated asters, and short spindle, which are avoided by the creation and maintenance of antiparallel microtubule overlaps. Our model can guide the identification of new, multifaceted strategies to induce mitotic catastrophes; these would constitute novel strategies for cancer chemotherapy. PMID:28116355

  7. Augmin promotes meiotic spindle formation and bipolarity in Xenopus egg extracts.

    Science.gov (United States)

    Petry, Sabine; Pugieux, Céline; Nédélec, François J; Vale, Ronald D

    2011-08-30

    Female meiotic spindles in many organisms form in the absence of centrosomes, the organelle typically associated with microtubule (MT) nucleation. Previous studies have proposed that these meiotic spindles arise from RanGTP-mediated MT nucleation in the vicinity of chromatin; however, whether this process is sufficient for spindle formation is unknown. Here, we investigated whether a recently proposed spindle-based MT nucleation pathway that involves augmin, an 8-subunit protein complex, also contributes to spindle morphogenesis. We used an assay system in which hundreds of meiotic spindles can be observed forming around chromatin-coated beads after introduction of Xenopus egg extracts. Spindles forming in augmin-depleted extracts showed reduced rates of MT formation and were predominantly multipolar, revealing a function of augmin in stabilizing the bipolar shape of the acentrosomal meiotic spindle. Our studies also have uncovered an apparent augmin-independent MT nucleation process from acentrosomal poles, which becomes increasingly active over time and appears to partially rescue the spindle defects that arise from augmin depletion. Our studies reveal that spatially and temporally distinct MT generation pathways from chromatin, spindle MTs, and acentrosomal poles all contribute to robust bipolar spindle formation in meiotic extracts.

  8. Sleep Spindles as an Electrographic Element: Description and Automatic Detection Methods

    Directory of Open Access Journals (Sweden)

    Dorothée Coppieters ’t Wallant

    2016-01-01

    Full Text Available Sleep spindle is a peculiar oscillatory brain pattern which has been associated with a number of sleep (isolation from exteroceptive stimuli, memory consolidation and individual characteristics (intellectual quotient. Oddly enough, the definition of a spindle is both incomplete and restrictive. In consequence, there is no consensus about how to detect spindles. Visual scoring is cumbersome and user dependent. To analyze spindle activity in a more robust way, automatic sleep spindle detection methods are essential. Various algorithms were developed, depending on individual research interest, which hampers direct comparisons and meta-analyses. In this review, sleep spindle is first defined physically and topographically. From this general description, we tentatively extract the main characteristics to be detected and analyzed. A nonexhaustive list of automatic spindle detection methods is provided along with a description of their main processing principles. Finally, we propose a technique to assess the detection methods in a robust and comparable way.

  9. A comparison of two sleep spindle detection methods based on all night averages: individually adjusted versus fixed frequencies

    Directory of Open Access Journals (Sweden)

    Péter Przemyslaw Ujma

    2015-02-01

    Full Text Available Sleep spindles are frequently studied for their relationship with state and trait cognitive variables, and they are thought to play an important role in sleep-related memory consolidation. Due to their frequent occurrence in NREM sleep, the detection of sleep spindles is only feasible using automatic algorithms, of which a large number is available. We compared subject averages of the spindle parameters computed by a fixed frequency (11-13 Hz for slow spindles, 13-15 Hz for fast spindles automatic detection algorithm and the individual adjustment method (IAM, which uses individual frequency bands for sleep spindle detection. Fast spindle duration and amplitude are strongly correlated in the two algorithms, but there is little overlap in fast spindle density and slow spindle parameters in general. The agreement between fixed and manually determined sleep spindle frequencies is limited, especially in case of slow spindles. This is the most likely reason for the poor agreement between the two detection methods in case of slow spindle parameters. Our results suggest that while various algorithms may reliably detect fast spindles, a more sophisticated algorithm primed to individual spindle frequencies is necessary for the detection of slow spindles as well as individual variations in the number of spindles in general.

  10. Layout and variables of air-powered drive of small-size pneumatic winch

    Science.gov (United States)

    Gileta, VP; Baris, AV; Vanag, YuV

    2017-02-01

    The paper describes three layouts of a winch with a harmonic drive and a flexible gear in the form of a set of spindles: classical layout with the remote motor and barrel; layout with the harmonic drive and remote motor; layout with the barrel with the in-built drive members. The analytical models are developed to determine acting faces and lateral dimension of rigid gear teeth depending on the layout and on the design and kinematic variables of the winch and the drive.

  11. Neuromorphic meets neuromechanics, part II: the role of fusimotor drive

    Science.gov (United States)

    Jalaleddini, Kian; Minos Niu, Chuanxin; Chakravarthi Raja, Suraj; Sohn, Won Joon; Loeb, Gerald E.; Sanger, Terence D.; Valero-Cuevas, Francisco J.

    2017-04-01

    Objective. We studied the fundamentals of muscle afferentation by building a Neuro-mechano-morphic system actuating a cadaveric finger. This system is a faithful implementation of the stretch reflex circuitry. It allowed the systematic exploration of the effects of different fusimotor drives to the muscle spindle on the closed-loop stretch reflex response. Approach. As in Part I of this work, sensory neurons conveyed proprioceptive information from muscle spindles (with static and dynamic fusimotor drive) to populations of α-motor neurons (with recruitment and rate coding properties). The motor commands were transformed into tendon forces by a Hill-type muscle model (with activation-contraction dynamics) via brushless DC motors. Two independent afferented muscles emulated the forces of flexor digitorum profundus and the extensor indicis proprius muscles, forming an antagonist pair at the metacarpophalangeal joint of a cadaveric index finger. We measured the physical response to repetitions of bi-directional ramp-and-hold rotational perturbations for 81 combinations of static and dynamic fusimotor drives, across four ramp velocities, and three levels of constant cortical drive to the α-motor neuron pool. Main results. We found that this system produced responses compatible with the physiological literature. Fusimotor and cortical drives had nonlinear effects on the reflex forces. In particular, only cortical drive affected the sensitivity of reflex forces to static fusimotor drive. In contrast, both static fusimotor and cortical drives reduced the sensitivity to dynamic fusimotor drive. Interestingly, realistic signal-dependent motor noise emerged naturally in our system without having been explicitly modeled. Significance. We demonstrate that these fundamental features of spinal afferentation sufficed to produce muscle function. As such, our Neuro-mechano-morphic system is a viable platform to study the spinal mechanisms for healthy muscle function—and its

  12. Effects of electrical and natural stimulation of skin afferents on the gamma-spindle system of the triceps surae muscle.

    Science.gov (United States)

    Johansson, H; Sjölander, P; Sojka, P; Wadell, I

    1989-08-01

    The aim of the present study was to investigate the extent to which skin receptors might influence the responses of primary muscle spindle afferents via reflex actions on the fusimotor system. The experiments were performed on 43 cats anaesthetized with alpha-chloralose. The alterations in fusimotor activity were assessed from changes in the responses of the muscle spindle afferents to sinusoidal stretching of their parent muscles (triceps surae and plantaris). The mean rate of firing and the modulation of the afferent response were determined. Control measurements were made in absence of any cutaneous stimulation. Tests were made (a) during physiological stimulation of skin afferents of the ipsilateral pad or of the contralateral hindlimb, or (b) during repetitive electrical stimulation of the sural nerve in the ipsilateral hindlimb, or of sural or superficial peroneal nerve in the contralateral hindlimb. Of the total number of 113 units tested with repetitive electrical stimulation of the ipsilateral sural nerve (at 20 Hz), 24.8% exhibited predominantly dynamic fusimotor reflexes, 5.3% mixed or predominantly static fusimotor reflexes. One unit studied in a preparation with intact spinal cord exhibited static reflexes at low stimulation intensities and dynamic ones at higher stimulation strengths. The remaining units (69%) were uninfluenced. When the receptor-bearing muscle was held at constant length and a train of stimuli (at 20 Hz) was applied to the ipsilateral sural nerve, the action potentials in the primary muscle spindle afferent could be stimulus-locked to the 3rd or 4th pulse in the train (and to the pulses following thereafter), with a latency of about 24 ms from the effective pulse. This 1:1 pattern of driving seemed to be mediated via static and/or dynamic fusimotor neurons. Natural stimulation influenced comparatively few units (3 of 65 units tested from the ipsilateral pad and 10 of 98 tested from the contralateral hindlimb), but when the effects

  13. DNA damage response and spindle assembly checkpoint function throughout the cell cycle to ensure genomic integrity.

    Directory of Open Access Journals (Sweden)

    Katherine S Lawrence

    2015-04-01

    Full Text Available Errors in replication or segregation lead to DNA damage, mutations, and aneuploidies. Consequently, cells monitor these events and delay progression through the cell cycle so repair precedes division. The DNA damage response (DDR, which monitors DNA integrity, and the spindle assembly checkpoint (SAC, which responds to defects in spindle attachment/tension during metaphase of mitosis and meiosis, are critical for preventing genome instability. Here we show that the DDR and SAC function together throughout the cell cycle to ensure genome integrity in C. elegans germ cells. Metaphase defects result in enrichment of SAC and DDR components to chromatin, and both SAC and DDR are required for metaphase delays. During persistent metaphase arrest following establishment of bi-oriented chromosomes, stability of the metaphase plate is compromised in the absence of DDR kinases ATR or CHK1 or SAC components, MAD1/MAD2, suggesting SAC functions in metaphase beyond its interactions with APC activator CDC20. In response to DNA damage, MAD2 and the histone variant CENPA become enriched at the nuclear periphery in a DDR-dependent manner. Further, depletion of either MAD1 or CENPA results in loss of peripherally associated damaged DNA. In contrast to a SAC-insensitive CDC20 mutant, germ cells deficient for SAC or CENPA cannot efficiently repair DNA damage, suggesting that SAC mediates DNA repair through CENPA interactions with the nuclear periphery. We also show that replication perturbations result in relocalization of MAD1/MAD2 in human cells, suggesting that the role of SAC in DNA repair is conserved.

  14. Relations between ultrastructure of mitotic spindle and chromosome translocation

    Directory of Open Access Journals (Sweden)

    Jadwiga A. Tarkowska

    2014-01-01

    Full Text Available Dividing endosperm cells of Haemanthus katherinae Bak. treated with an 0.25 per cent mixture of water-soluble glycosides from Nerium oleander were insepected in a light microscope (LM and severe disturbances were found in all phases of mitosis. The same cells were observed in the electron microscope (EM and relations were noted and analysed between the chromosome arrangement and the submicroscopic structure of the mitotuc spindle. The successive steps in the disintegration of the formed spindle are described: fragmentatiun of all microtubules (MTs starting from the poles, disappearance of non-kinetachore MTs and further the external MTs of the kineto,chore bundle. The central (internal parallel ones remain the longest at the kinerf,ochares. Oleander glycosides cause disintegration of the existing MTs and prevent formation of new ones. The causes of restitution transformations in the successive phases of mitosis are discussed.

  15. Stability analysis of machine tool spindle under uncertainty

    Directory of Open Access Journals (Sweden)

    Wei Dou

    2016-05-01

    Full Text Available Chatter is a harmful machining vibration that occurs between the workpiece and the cutting tool, usually resulting in irregular flaw streaks on the finished surface and severe tool wear. Stability lobe diagrams could predict chatter by providing graphical representations of the stable combinations of the axial depth of the cut and spindle speed. In this article, the analytical model of a spindle system is constructed, including a Timoshenko beam rotating shaft model and double sets of angular contact ball bearings with 5 degrees of freedom. Then, the stability lobe diagram of the model is developed according to its dynamic properties. The Monte Carlo method is applied to analyse the bearing preload influence on the system stability with uncertainty taken into account.

  16. Analysis on Failure Mode Severity of Machining Center Spindle System

    Institute of Scientific and Technical Information of China (English)

    Guixiang Shen; Shuguang Sun; Yingzhi Zhang; Xiaoyan Qi; Bingkun Chen

    2015-01-01

    According to the subjectivity and fuzziness of analysis on failure mode severity about spindle system of machining center, an analysis model of the failure mode severity of such a system is proposed based on the new fault severity index system, improved analytic hierarchy process ( IAHP ) and entropy⁃based fuzzy comprehensive evaluation. IAHP and entropy methods are adopted to determine the comprehensive failure severity index weight. The evaluation result is obtained after the factor set, comment set, weight set, and other parameters are determined, and then the level of risk degree and numerical value order of every spindle system failure mode is given. By taking an example, we verify that the proposed method can quantify the qualitative problem comprehensively, obtain more accurate analysis results, and provide the theoretical reference for mechanization and sequencing of failure mode effect analysis in reliability analysis. The calculation results can also serve as the basis of failure mode, effects, and criticality analysis in the subsequent step.

  17. Radiation-induced spindle cell sarcoma: A rare case report

    Directory of Open Access Journals (Sweden)

    Khan Mubeen

    2009-01-01

    Full Text Available Ionizing radiation has been known to induce malignant transformation in human beings. Radiation-induced sarcomas are a late sequel of radiation therapy. Most sarcomas have been reported to occur after exposure to a radiation dose of 55 Gray (Gy and above, with a dose ranging from 16 to 112 Gys. Spindle cell sarcomas, arising after radiotherapy given to treat the carcinoma of head and neck region is a very uncommon sequel. This is a rare case report of spindle cell sarcoma of left maxilla, in a 24-year-old male, occurring as a late complication of radiotherapy with Cobalt-60 given for the treatment of retinoblastoma of the left eye 21 years back.

  18. Temporal variability in groundwater and surface water quality in humid agricultural catchments; driving processes and consequences for regional water quality monitoring

    NARCIS (Netherlands)

    Rozemeijer, J.; Velde, van der Y.

    2014-01-01

    Considering the large temporal variability in surface water quality is essential for adequate water quality policy and management. Neglecting these dynamics may easily lead to decreased effectiveness of measures to improve water quality and to inefficient water quality monitoring. The objective of

  19. Temporal variability in groundwater and surface water quality in humid agricultural catchments; driving processes and consequences for regional water quality monitoring

    NARCIS (Netherlands)

    Rozemeijer, J.; Velde, van der Y.

    2014-01-01

    Considering the large temporal variability in surface water quality is essential for adequate water quality policy and management. Neglecting these dynamics may easily lead to decreased effectiveness of measures to improve water quality and to inefficient water quality monitoring. The objective of t

  20. Sleep spindle alterations in patients with Parkinson's disease

    DEFF Research Database (Denmark)

    Christensen, Julie Anja Engelhard; Nikolic, Miki; Warby, Simon C.;

    2015-01-01

    The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score...... in patients with PD or other neurodegenerative disorders (NDDs)....

  1. Acentrosomal Spindle Assembly & Chromosome Segregation During Oocyte Meiosis

    OpenAIRE

    Dumont, Julien; Desai, Arshad

    2012-01-01

    The ability to reproduce relies in most eukaryotes on specialized cells called gametes. Gametes are formed by the process of meiosis in which, after a single round of replication, two successive cell divisions reduce the ploidy of the genome. Fusion of gametes at fertilization reconstitutes diploidy. In most animal species, chromosome segregation during female meiosis occurs on spindles assembled in the absence of the major microtubule-organizing center, the centrosome. In mammals, oocyte mei...

  2. AMPK regulates mitotic spindle orientation through phosphorylation of myosin regulatory light chain.

    Science.gov (United States)

    Thaiparambil, Jose T; Eggers, Carrie M; Marcus, Adam I

    2012-08-01

    The proper orientation of the mitotic spindle is essential for mitosis; however, how these events unfold at the molecular level is not well understood. AMP-activated protein kinase (AMPK) regulates energy homeostasis in eukaryotes, and AMPK-null Drosophila mutants have spindle defects. We show that threonine(172) phosphorylated AMPK localizes to the mitotic spindle poles and increases when cells enter mitosis. AMPK depletion causes a mitotic delay with misoriented spindles relative to the normal division plane and a reduced number and length of astral microtubules. AMPK-depleted cells contain mitotic actin bundles, which prevent astral microtubule-actin cortex attachments. Since myosin regulatory light chain (MRLC) is an AMPK downstream target and mediates actin function, we investigated whether AMPK signals through MRLC to control spindle orientation. Mitotic levels of serine(19) phosphorylated MRLC (pMRLC(ser19)) and spindle pole-associated pMRLC(ser19) are abolished when AMPK function is compromised, indicating that AMPK is essential for pMRLC(ser19) spindle pole activity. Phosphorylation of AMPK and MRLC in the mitotic spindle is dependent upon calcium/calmodulin-dependent protein kinase kinase (CamKK) activity in LKB1-deficient cells, suggesting that CamKK regulates this pathway when LKB1 function is compromised. Taken together, these data indicate that AMPK mediates spindle pole-associated pMRLC(ser19) to control spindle orientation via regulation of actin cortex-astral microtubule attachments.

  3. Spindle assembly checkpoint and its regulators in meiosis.

    Science.gov (United States)

    Sun, Shao-Chen; Kim, Nam-Hyung

    2012-01-01

    BACKGROUND Meiosis is a unique form of cell division in which cells divide twice but DNA is duplicated only once. Errors in chromosome segregation during meiosis will result in aneuploidy, followed by loss of the conceptus during pregnancy or birth defects. During mitosis, cells utilize a mechanism called the spindle assembly checkpoint (SAC) to ensure faithful chromosome segregation. A similar mechanism has been uncovered for meiosis in the last decade, especially in the past several years. METHODS For this review, we included data and relevant information obtained through a PubMed database search for all articles published in English from 1991 through 2011 which included the term 'meiosis', 'spindle assembly checkpoint', or 'SAC'. RESULTS There are 91 studies included. Evidence for the existence of SAC functions in meiosis is provided by studies on the SAC proteins mitotic-arrest deficient-1 (Mad1), Mad2, budding uninhibited by benzimidazole-1 (Bub1), Bub3, BubR1 and Mps1; microtubule-kinetochore attachment regulators Ndc80 complex, chromosomal passenger complex, mitotic centromere-associated kinesin (MCAK), kinetochore null 1 (KNL1) and Mis12 complex and spindle stability regulators. CONCLUSIONS SAC and its regulators exist and function in meiosis, and their malfunctions may cause germ cell aneuploidy. However, species and sexual differences exist. Moreover, interaction of SAC components with other regulators is still poorly understood, which needs further study.

  4. Correcting improper chromosome-spindle attachments during cell division.

    Science.gov (United States)

    Lampson, Michael A; Renduchitala, Kishore; Khodjakov, Alexey; Kapoor, Tarun M

    2004-03-01

    For accurate segregation of chromosomes during cell division, microtubule fibres must attach sister kinetochores to opposite poles of the mitotic spindle (bi-orientation). Aurora kinases are linked to oncogenesis and have been implicated in the regulation of chromosome-microtubule attachments. Although loss of Aurora kinase activity causes an accumulation of mal-orientated chromosomes in dividing cells, it is not known how the active kinase corrects improper chromosome attachments. The use of reversible small-molecule inhibitors allows activation of protein function in living vertebrate cells with temporal control. Here we show that by removal of small-molecule inhibitors, controlled activation of Aurora kinase during mitosis can correct chromosome attachment errors by selective disassembly of kinetochore-microtubule fibres, rather than by alternative mechanisms involving initial release of microtubules from either kinetochores or spindle poles. Observation of chromosomes and microtubule dynamics with real-time high-resolution microscopy showed that mal-orientated, but not bi-orientated, chromosomes move to the spindle pole as both kinetochore-microtubule fibres shorten, followed by alignment at the metaphase plate. Our results provide direct evidence for a mechanism required for the maintenance of genome integrity during cell division.

  5. CENP-W plays a role in maintaining bipolar spindle structure.

    Science.gov (United States)

    Kaczmarczyk, Agnieszka; Sullivan, Kevin F

    2014-01-01

    The CENP-W/T complex was previously reported to be required for mitosis. HeLa cells depleted of CENP-W displayed profound mitotic defects, with mitotic timing delay, disorganized prometaphases and multipolar spindles as major phenotypic consequences. In this study, we examined the process of multipolar spindle formation induced by CENP-W depletion. Depletion of CENP-W in HeLa cells labeled with histone H2B and tubulin fluorescent proteins induced rapid fragmentation of originally bipolar spindles in a high proportion of cells. CENP-W depletion was associated with depletion of Hec1 at kinetochores. The possibility of promiscuous centrosomal duplication was ruled out by immunofluorescent examination of centrioles. However, centrioles were frequently observed to be abnormally split. In addition, a large proportion of the supernumerary poles lacked centrioles, but were positively stained with different centrosomal markers. These observations suggested that perturbation in spindle force distribution caused by defective kinetochores could contribute to a mechanical mechanism for spindle pole disruption. 'Spindle free' nocodazole arrested cells did not exhibit pole fragmentation after CENP-W depletion, showing that pole fragmentation is microtubule dependent. Inhibition of centrosome separation by monastrol reduced the incidence of spindle pole fragmentation, indicating that Eg5 plays a role in spindle pole disruption. Surprisingly, CENP-W depletion rescued the monopolar spindle phenotype of monastrol treatment, with an increased frequency of bipolar spindles observed after CENP-W RNAi. We overexpressed the microtubule cross-linking protein TPX2 to create spindle poles stabilized by the microtubule cross-linking activity of TPX2. Spindle pole fragmentation was suppressed in a TPX2-dependent fashion. We propose that CENP-W, by influencing proper kinetochore assembly, particularly microtubule docking sites, can confer spindle pole resistance to traction forces exerted by

  6. CENP-W plays a role in maintaining bipolar spindle structure.

    Directory of Open Access Journals (Sweden)

    Agnieszka Kaczmarczyk

    Full Text Available The CENP-W/T complex was previously reported to be required for mitosis. HeLa cells depleted of CENP-W displayed profound mitotic defects, with mitotic timing delay, disorganized prometaphases and multipolar spindles as major phenotypic consequences. In this study, we examined the process of multipolar spindle formation induced by CENP-W depletion. Depletion of CENP-W in HeLa cells labeled with histone H2B and tubulin fluorescent proteins induced rapid fragmentation of originally bipolar spindles in a high proportion of cells. CENP-W depletion was associated with depletion of Hec1 at kinetochores. The possibility of promiscuous centrosomal duplication was ruled out by immunofluorescent examination of centrioles. However, centrioles were frequently observed to be abnormally split. In addition, a large proportion of the supernumerary poles lacked centrioles, but were positively stained with different centrosomal markers. These observations suggested that perturbation in spindle force distribution caused by defective kinetochores could contribute to a mechanical mechanism for spindle pole disruption. 'Spindle free' nocodazole arrested cells did not exhibit pole fragmentation after CENP-W depletion, showing that pole fragmentation is microtubule dependent. Inhibition of centrosome separation by monastrol reduced the incidence of spindle pole fragmentation, indicating that Eg5 plays a role in spindle pole disruption. Surprisingly, CENP-W depletion rescued the monopolar spindle phenotype of monastrol treatment, with an increased frequency of bipolar spindles observed after CENP-W RNAi. We overexpressed the microtubule cross-linking protein TPX2 to create spindle poles stabilized by the microtubule cross-linking activity of TPX2. Spindle pole fragmentation was suppressed in a TPX2-dependent fashion. We propose that CENP-W, by influencing proper kinetochore assembly, particularly microtubule docking sites, can confer spindle pole resistance to traction

  7. Sleep spindles and intelligence in early childhood-developmental and trait-dependent aspects.

    Science.gov (United States)

    Ujma, Péter P; Sándor, Piroska; Szakadát, Sára; Gombos, Ferenc; Bódizs, Róbert

    2016-12-01

    Sleep spindles act as a powerful marker of individual differences in cognitive ability. Sleep spindle parameters correlate with both age-related changes in cognitive abilities and with the age-independent concept of IQ. While some studies have specifically demonstrated the relationship between sleep spindles and intelligence in young children, our previous work in older subjects revealed sex differences in the sleep spindle correlates of IQ, which was never investigated in small children before. We investigated the relationship between age, Raven Colored Progressive Matrices (CPM) scores and sleep spindles in 28 young children (age 4-8 years, 15 girls). We specifically investigated sex differences in the psychometric correlates of sleep spindles. We also aimed to separate the correlates of sleep spindles that are because of age-related maturation from other effects that reflect an age-independent relationship between sleep spindles and general intelligence. Our results revealed a modest positive correlation between fast spindle amplitude and age. Raven CPM scores positively correlated with both slow and fast spindle amplitude, but this effect remained a tendency in males and vanished after correcting for the effects of age. Age-corrected correlations between Raven CPM scores and both slow and fast spindle amplitude were only significant in females. Overall, our results show that in male children sleep spindles are a maturational marker, but in female children they indicate trait-like intelligence, in line with previous studies in adolescent and adult subjects. Thalamocortical white matter connectivity may be the underlying mechanism behind both higher spindle amplitude and higher intelligence in female, but not male subjects. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  8. Reduced ability to recover from spindle disruption and loss of kinetochore spindle assembly checkpoint proteins in oocytes from aged mice.

    Science.gov (United States)

    Yun, Yan; Holt, Janet E; Lane, Simon I R; McLaughlin, Eileen A; Merriman, Julie A; Jones, Keith T

    2014-01-01

    Currently, maternal aging in women, based on mouse models, is thought to raise oocyte aneuploidy rates, because chromosome cohesion deteriorates during prophase arrest, and Sgo2, a protector of centromeric cohesion, is lost. Here we show that the most common mouse strain, C57Bl6/J, is resistant to maternal aging, showing little increase in aneuploidy or Sgo2 loss. Instead it demonstrates significant kinetochore-associated loss in the spindle assembly checkpoint protein Mad2 and phosphorylated Aurora C, which is involved in microtubule-kinetochore error correction. Their loss affects the fidelity of bivalent segregation but only when spindle organization is impaired during oocyte maturation. These findings have an impact clinically regarding the handling of human oocytes ex vivo during assisted reproductive techniques and suggest there is a genetic basis to aneuploidy susceptibility.

  9. Clathrin is spindle-associated but not essential for mitosis.

    Directory of Open Access Journals (Sweden)

    Joana Borlido

    Full Text Available Clathrin is a multimeric protein involved in vesicle coat assembly. Recently clathrin distribution was reported to change during the cell cycle and was found to associate with the mitotic spindle. Here we test whether the recruitment of clathrin to the spindle is indicative of a critical functional contribution to mitosis.Previously a chicken pre-B lymphoma cell line (DKO-R was developed in which the endogenous clathrin heavy chain alleles were replaced with the human clathrin heavy chain under the control of a tetracycline-regulatable promoter. Receptor-mediated and fluid-phase endocytosis were significantly inhibited in this line following clathrin knockout, and we used this to explore the significance of clathrin heavy chain expression for cell cycle progression. We confirmed using confocal microscopy that clathrin colocalised with tubulin at mitotic spindles. Using a propidium iodide flow cytometric assay we found no statistical difference in the cell cycle distribution of the knockout cells versus the wild-type. Additionally, we showed that the ploidy and the recovery kinetics following cell cycle arrest with nocodazole were unchanged by repressing clathrin heavy chain expression.We conclude that the association of clathrin with the mitotic spindle and the contribution of clathrin to endocytosis are evolutionarily conserved. However we find that the contribution of clathrin to mitosis is less robust and dependent on cellular context. In other cell-lines silencing RNA has been used by others to knockdown clathrin expression resulting in an increase in the mitotic index of the cells. We show an effect on the G2/M phase population of clathrin knockdown in HEK293 cells but show that repressing clathrin expression in the DKO-R cell-line has no effect on the size of this population. Consequently this work highlights the need for a more detailed molecular understanding of the recruitment and function of clathrin at the spindle, since the

  10. Magnetic suspension motorized spindle-cutting system dynamics analysis and vibration control review

    Directory of Open Access Journals (Sweden)

    Xiaoli QIAO

    2016-10-01

    Full Text Available The performance of high-speed spindle directly determines the development of high-end machine tools. The cutting system's dynamic characteristics and vibration control effect are inseparable with the performance of the spindle,which influence each other, synergistic effect together the cutting efficiency, the surface quality of the workpiece and tool life in machining process. So, the review status on magnetic suspension motorized spindle, magnetic suspension bearing-flexible rotor system dynamics modeling theory and status of active control technology of flexible magnetic suspension motorized spindle rotor vibration are studied, and the problems which present in the magnetic suspension flexible motorized spindle rotor systems are refined, and the development trend of magnetic levitation motorized spindle and the application prospect is forecasted.

  11. Inter-expert and intra-expert reliability in sleep spindle scoring

    DEFF Research Database (Denmark)

    Wendt, Sabrina Lyngbye; Welinder, Peter; Sørensen, Helge Bjarup Dissing

    2015-01-01

    with higher reliability than the estimation of spindle duration. Reliability of sleep spindle scoring can be improved by using qualitative confidence scores, rather than a dichotomous yes/no scoring system. Conclusions We estimate that 2–3 experts are needed to build a spindle scoring dataset......Objectives To measure the inter-expert and intra-expert agreement in sleep spindle scoring, and to quantify how many experts are needed to build a reliable dataset of sleep spindle scorings. Methods The EEG dataset was comprised of 400 randomly selected 115 s segments of stage 2 sleep from 110...... sleeping subjects in the general population (57 ± 8, range: 42–72 years). To assess expert agreement, a total of 24 Registered Polysomnographic Technologists (RPSGTs) scored spindles in a subset of the EEG dataset at a single electrode location (C3-M2). Intra-expert and inter-expert agreements were...

  12. Intercentrosomal angular separation during mitosis plays a crucial role for maintaining spindle stability

    Science.gov (United States)

    Sutradhar, S.; Basu, S.; Paul, R.

    2015-10-01

    Cell division through proper spindle formation is one of the key puzzles in cell biology. In most mammalian cells, chromosomes spontaneously arrange to achieve a stable bipolar spindle during metaphase which eventually ensures proper segregation of the DNA into the daughter cells. In this paper, we present a robust three-dimensional mechanistic model to investigate the formation and maintenance of a bipolar mitotic spindle in mammalian cells under different physiological constraints. Using realistic parameters, we test spindle viability by measuring the spindle length and studying the chromosomal configuration. The model strikingly predicts a feature of the spindle instability arising from the insufficient intercentrosomal angular separation and impaired sliding of the interpolar microtubules. In addition, our model successfully reproduces chromosomal patterns observed in mammalian cells, when activity of different motor proteins is perturbed.

  13. Microtubule organization within mitotic spindles revealed by serial block face scanning electron microscopy and image analysis.

    Science.gov (United States)

    Nixon, Faye M; Honnor, Thomas R; Clarke, Nicholas I; Starling, Georgina P; Beckett, Alison J; Johansen, Adam M; Brettschneider, Julia A; Prior, Ian A; Royle, Stephen J

    2017-05-15

    Serial block face scanning electron microscopy (SBF-SEM) is a powerful method to analyze cells in 3D. Here, working at the resolution limit of the method, we describe a correlative light-SBF-SEM workflow to resolve microtubules of the mitotic spindle in human cells. We present four examples of uses for this workflow that are not practical by light microscopy and/or transmission electron microscopy. First, distinguishing closely associated microtubules within K-fibers; second, resolving bridging fibers in the mitotic spindle; third, visualizing membranes in mitotic cells, relative to the spindle apparatus; and fourth, volumetric analysis of kinetochores. Our workflow also includes new computational tools for exploring the spatial arrangement of microtubules within the mitotic spindle. We use these tools to show that microtubule order in mitotic spindles is sensitive to the level of TACC3 on the spindle. © 2017. Published by The Company of Biologists Ltd.

  14. Surface shape control of the workpiece in a double-spindle triple-workstation wafer grinder

    Science.gov (United States)

    Xianglong, Zhu; Renke, Kang; Zhigang, Dong; Guang, Feng

    2011-10-01

    Double-spindle triple-workstation (DSTW) ultra precision grinders are mainly used in production lines for manufacturing and back thinning large diameter (>= 300 mm) silicon wafers for integrated circuits. It is important, but insufficiently studied, to control the wafer shape ground on a DSTW grinder by adjusting the inclination angles of the spindles and work tables. In this paper, the requirements of the inclination angle adjustment of the grinding spindles and work tables in DSTW wafer grinders are analyzed. A reasonable configuration of the grinding spindles and work tables in DSTW wafer grinders are proposed. Based on the proposed configuration, an adjustment method of the inclination angle of grinding spindles and work tables for DSTW wafer grinders is put forward. The mathematical models of wafer shape with the adjustment amount of inclination angles for both fine and rough grinding spindles are derived. The proposed grinder configuration and adjustment method will provide helpful instruction for DSTW wafer grinder design.

  15. EFFECT OF ANGELICA SINENSIS ON AFFERENT DISCHARGE OF SINGLE MUSCLE SPINDLE IN TOADS

    Institute of Scientific and Technical Information of China (English)

    高云芳; 樊小力

    2004-01-01

    Objective In drugs for invigorating blood circulation, to find a herb that can stimulate afferent discharge of muscle spindle. Methods A single muscle spindle was isolated from sartorial muscle of toad. Using air-gap technique, afferent discharge of the muscle spindle was recorded. Effects of Angelica Sinensis, Salvia Miltiorrhiza, and Safflower on afferent discharge of the muscle spindle were observed. Results Angelica Sinensis could distinctly increase afferent discharge frequency of the muscle spindle, and this increase was dose-dependent. But Salvia Miltiorrhiza and Safflower had no this excitatory effect. Conclusion It is known that Angelica Sinensis can invigorate blood circulation, and we have found its excitatory effect on muscle spindle which makes it possible to serve people with muscle atrophy if more evidences from clinical experiments are available.

  16. Wetting and drying of masonry walls: 2D-resistivity monitoring of driving rain experiments on historic stonework in Oxford, UK

    Science.gov (United States)

    Sass, O.; Viles, H. A.

    2010-01-01

    2D resistivity methods can provide useful information about moisture distributions within porous historic stonework, especially when used in conjunction with simulated driving rain. Moisture is known to be a highly important factor in the deterioration of porous stone. We report here on a series of experiments on historic walls within the centre of Oxford, UK, which illustrate varying degrees of deterioration (including the formation of gypsum-rich black crusts and exfoliating hollows). Using medical electrodes we have been able to carry out non-invasive and non-destructive 2D resistivity surveys before and after simulated rainfall to investigate the progress of wetting and drying. We have applied tentative calibrations to convert resistivity values to moisture contents. Our results show that rainfall penetrates in predictable ways, with clearly defined wetting and drying fronts. Stone blocks with highly weathered surfaces exhibit the most rapid and high levels of water uptake, but also dry out more quickly than crusted or sound blocks. Thus, positive feedbacks may be encouraged whereby more water is cycled through damaged blocks, thereby enhancing the potential for further damage.

  17. Large Tailed Spindle Viruses of Archaea: a New Way of Doing Viral Business.

    Science.gov (United States)

    Hochstein, Rebecca; Bollschweiler, Daniel; Engelhardt, Harald; Lawrence, C Martin; Young, Mark

    2015-09-01

    Viruses of Archaea continue to surprise us. Archaeal viruses have revealed new morphologies, protein folds, and gene content. This is especially true for large spindle viruses, which infect only Archaea. We present a comparison of particle morphologies, major coat protein structures, and gene content among the five characterized large spindle viruses to elucidate defining characteristics. Structural similarities and a core set of genes support the grouping of the large spindle viruses into a new superfamily.

  18. Sleep-spindle detection: crowdsourcing and evaluating performance of experts, non-experts and automated methods

    DEFF Research Database (Denmark)

    Warby, Simon C.; Wendt, Sabrina Lyngbye; Welinder, Peter

    2014-01-01

    Sleep spindles are discrete, intermittent patterns of brain activity observed in human electroencephalographic data. Increasingly, these oscillations are of biological and clinical interest because of their role in development, learning and neurological disorders. We used an Internet interface...... that crowdsourcing the scoring of sleep data is an efficient method to collect large data sets, even for difficult tasks such as spindle identification. Further refinements to spindle detection algorithms are needed for middle- to older-aged subjects....

  19. 小模数滚齿机用电主轴的设计与研究%Design and Research of Motorized Spindle of Small Module Gear Hobbing Machine

    Institute of Scientific and Technical Information of China (English)

    王东寅; 杨建玺; 孙渊涛; 黄健; 周浩兵

    2015-01-01

    小模数数控滚齿机去掉了传动用的齿轮副、蜗轮蜗杆副等传动元件,刀具轴和工件轴直接与电机轴相联。几何误差和热误差是小模数滚齿机的主要误差来源,为此,设计了一种新型的电主轴。该电主轴采用了主轴电机置于主轴后轴承之后的形式,缩小了主轴轴承位置的径向尺寸,使轴承摩擦产生的热量的散发,减少了电机发热对轴承变形产生的影响;主轴轴承采用了静压轴承的形式,提高了主轴轴承的耐磨性和回转精度。该电主轴的设计能够提高小模数滚齿机的生产效率和加工精度。%The small modulus gear hobbing machine was removed of drive gears and worm wheel⁃worm, and both hob spindle and workpiece spindle directly were connected directly with the motor shaft. Geometric error and thermal error were main error coming from the small module hobbing machine. For the case of that, a new type of motorized spindle is designed. The form of the spindle mo⁃tor being behind the spindle bearing was used, which led to the reduction of radial size of spindle bearing position, the heat dissipation cased by bearing friction and the reduction of the influence of electrical machine emitted heat made deformation of bearing. The form of the hydrostatic bearing was used on spindle bearing, which improved the abrasion resistance and the rotation accuracy of the spindle bearing. Production efficiency and machining accuracy of the small modulus gear hobbing machine are improved by the designed motor⁃ized spindle.

  20. The 3Ms of central spindle assembly: microtubules, motors and MAPs.

    Science.gov (United States)

    Glotzer, Michael

    2009-01-01

    During metaphase, sister chromatids are positioned at the midpoint of the microtubule-based mitotic spindle in preparation for their segregation. The onset of anaphase triggers inactivation of the key mitotic kinase cyclin-dependent kinase 1 (CDK1) and the polewards movement of sister chromatids. During anaphase, the mitotic spindle reorganizes in preparation for cytokinesis. Kinesin motor proteins and microtubule-associated proteins bundle the plus ends of interpolar microtubules and generate the central spindle, which regulates cleavage furrow initiation and the completion of cytokinesis. Complementary approaches, including cell biology, genetics and computational modelling, have provided new insights into the mechanism and regulation of central spindle assembly.

  1. Cep57, a NEDD1-binding pericentriolar material component, is essential for spindle pole integrity

    Institute of Scientific and Technical Information of China (English)

    Qixi Wu; Runsheng He; Haining Zhou; Albert CH Yu; Bo Zhang; Junlin Teng; Jianguo Chen

    2012-01-01

    Formation of a bipolar spindle is indispensable for faithful chromosome segregation and cell division.Spindle integrity is largely dependent on the centrosome and the microtubule network.Centrosome protein Cep57 can bundle microtubules in mammalian cells.Its related protein (Cep57R) in Xenopus was characterized as a stabilization factor for microtubule-kinetochore attachment.Here we show that Cep57 is a pericentriolar material (PCM) component.Its interaction with NEDD1 is necessary for the centrosome localization of Cep57.Depletion of Cep57 leads to unaligned chromosomes and a multipolar spindle,which is induced by PCM fragmentation.In the absence of Cep57,centrosome microtubule array assembly activity is weakened,and the spindle length and microtubule density decrease.As a spindle microtubule-binding protein,Cep57 is also responsible for the proper organization of the spindle microtubule and localization of spindle pole focusing proteins.Collectively,these results suggest that Cep57,as a NEDD1binding centrosome component,could function as a spindle pole- and microtubule-stabilizing factor for establishing robust spindle architecture.

  2. REM sleep behaviour disorder is associated with lower fast and higher slow sleep spindle densities.

    Science.gov (United States)

    O'Reilly, Christian; Godin, Isabelle; Montplaisir, Jacques; Nielsen, Tore

    2015-12-01

    To investigate differences in sleep spindle properties and scalp topography between patients with rapid eye movement sleep behaviour disorder (RBD) and healthy controls, whole-night polysomnograms of 35 patients diagnosed with RBD and 35 healthy control subjects matched for age and sex were compared. Recordings included a 19-lead 10-20 electroencephalogram montage and standard electromyogram, electrooculogram, electrocardiogram and respiratory leads. Sleep spindles were automatically detected using a standard algorithm, and their characteristics (amplitude, duration, density, frequency and frequency slope) compared between groups. Topological analyses of group-discriminative features were conducted. Sleep spindles occurred at a significantly (e.g. t34 = -4.49; P = 0.00008 for C3) lower density (spindles ∙ min(-1) ) for RBD (mean ± SD: 1.61 ± 0.56 for C3) than for control (2.19 ± 0.61 for C3) participants. However, when distinguishing slow and fast spindles using thresholds individually adapted to the electroencephalogram spectrum of each participant, densities smaller (31-96%) for fast but larger (20-120%) for slow spindles were observed in RBD in all derivations. Maximal differences were in more posterior regions for slow spindles, but over the entire scalp for fast spindles. Results suggest that the density of sleep spindles is altered in patients with RBD and should therefore be investigated as a potential marker of future neurodegeneration in these patients.

  3. Cep57, a NEDD1-binding pericentriolar material component, is essential for spindle pole integrity.

    Science.gov (United States)

    Wu, Qixi; He, Runsheng; Zhou, Haining; Yu, Albert C H; Zhang, Bo; Teng, Junlin; Chen, Jianguo

    2012-09-01

    Formation of a bipolar spindle is indispensable for faithful chromosome segregation and cell division. Spindle integrity is largely dependent on the centrosome and the microtubule network. Centrosome protein Cep57 can bundle microtubules in mammalian cells. Its related protein (Cep57R) in Xenopus was characterized as a stabilization factor for microtubule-kinetochore attachment. Here we show that Cep57 is a pericentriolar material (PCM) component. Its interaction with NEDD1 is necessary for the centrosome localization of Cep57. Depletion of Cep57 leads to unaligned chromosomes and a multipolar spindle, which is induced by PCM fragmentation. In the absence of Cep57, centrosome microtubule array assembly activity is weakened, and the spindle length and microtubule density decrease. As a spindle microtubule-binding protein, Cep57 is also responsible for the proper organization of the spindle microtubule and localization of spindle pole focusing proteins. Collectively, these results suggest that Cep57, as a NEDD1-binding centrosome component, could function as a spindle pole- and microtubule-stabilizing factor for establishing robust spindle architecture.

  4. Kinesin-5-independent mitotic spindle assembly requires the antiparallel microtubule crosslinker Ase1 in fission yeast

    Science.gov (United States)

    Rincon, Sergio A.; Lamson, Adam; Blackwell, Robert; Syrovatkina, Viktoriya; Fraisier, Vincent; Paoletti, Anne; Betterton, Meredith D.; Tran, Phong T.

    2017-05-01

    Bipolar spindle assembly requires a balance of forces where kinesin-5 produces outward pushing forces to antagonize the inward pulling forces from kinesin-14 or dynein. Accordingly, Kinesin-5 inactivation results in force imbalance leading to monopolar spindle and chromosome segregation failure. In fission yeast, force balance is restored when both kinesin-5 Cut7 and kinesin-14 Pkl1 are deleted, restoring spindle bipolarity. Here we show that the cut7Δpkl1Δ spindle is fully competent for chromosome segregation independently of motor activity, except for kinesin-6 Klp9, which is required for anaphase spindle elongation. We demonstrate that cut7Δpkl1Δ spindle bipolarity requires the microtubule antiparallel bundler PRC1/Ase1 to recruit CLASP/Cls1 to stabilize microtubules. Brownian dynamics-kinetic Monte Carlo simulations show that Ase1 and Cls1 activity are sufficient for initial bipolar spindle formation. We conclude that pushing forces generated by microtubule polymerization are sufficient to promote spindle pole separation and the assembly of bipolar spindle in the absence of molecular motors.

  5. Noninvasive three-dimensional live imaging methodology for the spindles at meiosis and mitosis

    Science.gov (United States)

    Zheng, Jing-gao; Huo, Tiancheng; Tian, Ning; Chen, Tianyuan; Wang, Chengming; Zhang, Ning; Zhao, Fengying; Lu, Danyu; Chen, Dieyan; Ma, Wanyun; Sun, Jia-lin; Xue, Ping

    2013-05-01

    The spindle plays a crucial role in normal chromosome alignment and segregation during meiosis and mitosis. Studying spindles in living cells noninvasively is of great value in assisted reproduction technology (ART). Here, we present a novel spindle imaging methodology, full-field optical coherence tomography (FF-OCT). Without any dye labeling and fixation, we demonstrate the first successful application of FF-OCT to noninvasive three-dimensional (3-D) live imaging of the meiotic spindles within the mouse living oocytes at metaphase II as well as the mitotic spindles in the living zygotes at metaphase and telophase. By post-processing of the 3-D dataset obtained with FF-OCT, the important morphological and spatial parameters of the spindles, such as short and long axes, spatial localization, and the angle of meiotic spindle deviation from the first polar body in the oocyte were precisely measured with the spatial resolution of 0.7 μm. Our results reveal the potential of FF-OCT as an imaging tool capable of noninvasive 3-D live morphological analysis for spindles, which might be useful to ART related procedures and many other spindle related studies.

  6. Spindle cell melanocytic lesions--part I: an approach to compound naevoidal pattern lesions with spindle cell morphology and Spitzoid pattern lesions.

    Science.gov (United States)

    Sade, Shachar; Al Habeeb, Ayman; Ghazarian, Danny

    2010-04-01

    Melanocytic lesions show great morphological diversity in their architecture and the cytomorphological appearance of their composite cells. Whereas functional melanocytes reveal a dendritic cytomorphology and territorial isolation, lesional naevomelanocytes and melanoma cells typically show epithelioid, spindled or mixed cytomorphologies and a range of architectural arrangements. Spindling is common to melanocytic lesions, and may be either a characteristic feature or a divergent appearance. The presence of spindle cells may mask the melanocytic nature of a lesion, and is often disconcerting, either because of its infrequent appearance in a particular lesion or its interpretation as a dedifferentiated phenotype. Spindle cell melanocytic lesions follow the full spectrum of potential biological outcomes, and difficulty may be experienced judging the nature of a lesion because of a lack of consistently reliable features to predict biological behaviour. Over time, recognition of numerous histomorphological features that may portend a more aggressive lesion have been identified. However, the translation of these features into a diagnostic entity requires a gestalt approach. Although most spindle cell melanocytic lesions can reliably be resolved with this standard approach, problem areas do exist and cause no end of grief to the surgical pathologist or dermatopathologist. In this review, the authors present their algorithmic approach to spindle cell melanocytic lesions and discuss each entity in turn, in order to (1) model a systematic approach to such lesions, and (2) provide familiarity with those melanocytic lesions that either typically or occasionally display a spindled cytomorphology.

  7. ELDERLY DRIVING BEHAVIOR AND COGNITIVE FUNCTIONS

    Directory of Open Access Journals (Sweden)

    Etsuo HORIKAWA

    2009-01-01

    Discussions: Of the 30 items monitored in the study, significant differences were evident in only a few. Because the evidence did not suggest a particular link to accident experience, it will be necessary to obtain objective data from other cognitive function tests and driving behavior for reassessment. various problems related to elderly driving in Japan were discussed.

  8. [Receptor adaptation of muscle spindles treated in different ways].

    Science.gov (United States)

    Zalkind, V I; Rokotova, N A

    1978-11-01

    Comparison of the grades of 60 sensitive muscle spindle terminals on two actions: gradual stretch of the muscle and short intensive tetanization of the muscle nerve, showed that, irrespective of the mode of action, the character of adaptation remains the smae in majority of units. The speed of receptors adaptation depends not on the specific of testing precedures, but, apparently, on the means of connection of the sensitive terminals with different types of intrafusal muscle fibers with different elasticviscous properties. The possible reason for speedy adaptation of muscle receptors of elementary dynamic type, is discussed.

  9. Connections between microtubules and endoplasmic reticulum in mitotic spindle

    Directory of Open Access Journals (Sweden)

    J. A. Tarkowska

    2015-01-01

    Full Text Available Dividing endosperm cells of Haemanthus katherinae Bak. were treated with an 0.025 per cent aqueous solution of an oleander glycosides mixture which produces severe disturtaances in the mitotic spindle and high hypertrophy of the endoplasmic reticulum (ER in the whole cells. There appear between the kinetochore microtubules (MTs numerous elongated and narrow ER cisterns, particularly well visible when the number of kinetochore MTs is reduced. Both these structures (MTs and ER are frequently connected by cross-bridges. The presumable role of these connections is discused.

  10. Thermal Error Modelling of the Spindle Using Neurofuzzy Systems

    OpenAIRE

    Jingan Feng; Xiaoqi Tang; Yanlei Li; Bao Song

    2016-01-01

    This paper proposes a new combined model to predict the spindle deformation, which combines the grey models and the ANFIS (adaptive neurofuzzy inference system) model. The grey models are used to preprocess the original data, and the ANFIS model is used to adjust the combined model. The outputs of the grey models are used as the inputs of the ANFIS model to train the model. To evaluate the performance of the combined model, an experiment is implemented. Three Pt100 thermal resistances are use...

  11. Spindle cell hemangioma: Unusual presentation of an uncommon tumor

    Directory of Open Access Journals (Sweden)

    Olalere Omoyosola Gbolahan

    2015-01-01

    Full Text Available Spindle cell hemangioma (SCH is an uncommon tumor that usually presents as subcutaneous or deep dermal nodule affecting the extremities and is typically <2 cm in size. A few cases have been reported in the head and neck region. To the best of the authors' knowledge, there are no previous reports of SCH occurring in the orbit in the English literature. We, therefore, report the case of a large SCH involving the right orbit of a healthy 9-year-old Nigerian girl.

  12. Structure, distribution and innervation of muscle spindles in avian fast and slow skeletal muscle

    Science.gov (United States)

    OVALLE, WILLIAM K.; DOW, PIERRE R.; NAHIRNEY, PATRICK C.

    1999-01-01

    Muscle spindles in 2 synergistic avian skeletal muscles, the anterior (ALD) and posterior (PLD) latissimus dorsi, were studied by light and electron microscopy to determine whether morphological or quantitative differences existed between these sensory receptors. Differences were found in the density, distribution and location of muscle spindles in the 2 muscles. They also differed with respect to the morphology of their capsules and intracapsular components. The slow ALD possessed muscle spindles which were evenly distributed throughout the muscle, whereas in the fast PLD they were mainly concentrated around the single nerve entry point into the muscle. The muscle spindle index (number of spindles per gram wet muscle weight) in the ALD was more than double that of its fast-twitch PLD counterpart (130.5±2.0 vs 55.4±2.0 respectively, n=6). The number of intrafusal fibres per spindle ranged from 1 to 8 in the ALD and 2 to 9 in the PLD, and their diameters varied from 5.0 to 16.0 μm and 4.5 to 18.5 μm, respectively. Large diameter intrafusal fibres were more frequently encountered in spindles of the PLD. Unique to the ALD was the presence of monofibre muscle spindles (12.7% of total spindles observed in ALD) which contained a solitary intrafusal fibre. In muscle spindles of both the ALD and PLD, sensory nerve endings terminated in a spiral fashion on the intrafusal fibres in their equatorial regions. Motor innervation was restricted to either juxtaequatorial or polar regions of the intrafusal fibres. Outer capsule components were extensive in polar and juxtaequatorial regions of ALD spindles, whereas inner capsule cells of PLD spindles were more numerous in juxtaequatorial and equatorial regions. Overall, muscle spindles of the PLD exhibited greater complexity with respect to the number of intrafusal fibres per spindle, range of intrafusal fibre diameters and development of their inner capsules. It is postulated that the differences in muscle spindle density and

  13. Thermal influence of the Couette flow in a hydrostatic spindle on the machining precision

    Science.gov (United States)

    Chen, Dongju; Fan, Jinwei; Li, Haiyong; Wang, Xiaofeng; Zhang, Feihu

    2013-05-01

    Hydrostatic spindles are increasingly used in precision machine tools. Thermal error is the key factor affecting the machining accuracy of the spindle, and research has focused on spindle thermal errors through examination of the influence of the temperature distribution, thermal deformation and spindle mode. However, seldom has any research investigated the thermal effects of the associated Couette flow. To study the heat transfer mechanism in spindle systems, the criterion of the heat transfer direction according to the temperature distribution of the Couette flow at different temperatures is deduced. The method is able to deal accurately with the significant phenomena occurring at every place where thermal energy flowed in such a spindle system. The variation of the motion error induced by thermal effects on a machine work-table during machining is predicated by establishing the thermo-mechanical error model of the hydrostatic spindle for a high precision machine tool. The flow state and thermal behavior of a hydrostatic spindle is analyzed with the evaluated heat power and the coefficients of the convective heat transfer over outer surface of the spindle are calculated, and the thermal influence on the oil film stiffness is evaluated. Thermal drift of the spindle nose is measured with an inductance micrometer, the thermal deformation data 1.35 μm after running for 4 h is consistent with the value predicted by the finite element analysis's simulated result 1.28 μm, and this demonstrates that the simulation method is feasible. The thermal effects on the processing accuracy from the flow characteristics of the fluid inside the spindle are analyzed for the first time.

  14. Arecoline arrests cells at prometaphase by deregulating mitotic spindle assembly and spindle assembly checkpoint: implication for carcinogenesis.

    Science.gov (United States)

    Wang, Yu-Chu; Tsai, Yi-Shan; Huang, Jau-Ling; Lee, Ka-Wo; Kuo, Ching-Chuan; Wang, Chung-Sheng; Huang, A-Mei; Chang, Jang-Yang; Jong, Yuh-Jyh; Lin, Chang-Shen

    2010-04-01

    One apparent feature of cancerous cells is genomic instability, which may include various types of chromosomal aberrations, such as translocation, aneuploidy, and the presence of micronuclei inside the cells. Mutagenic factors that promote the emergence of genomic instability are recognized as risk factors for the development of human malignancies. In Asia, betel quid (BQ) chewing is one of such risk factors for oral cancer. Areca nut is an essential constitute of BQ and is declared as a group I carcinogen by the International Agency for Research on Cancer. However, the molecular and cellular mechanisms regarding the carcinogenicity of areca nut are not fully explored. Here we reported that arecoline, a major alkaloid of areca nut, could arrest cells at prometaphase with large amounts of misaligned chromosomes. This prometaphase arrest was evidenced by condensed chromosome pattern, increased histone H3 phosphorylation, and accumulation of mitotic proteins, including aurora A and cyclin B(1). To investigate the molecular mechanisms accounting for arecoline-induced prometaphase arrest, we found that arecoline could stabilize mitotic spindle assembly, which led to distorted organization of mitotic spindles, misalignment of chromosomes, and up-regulation of spindle assembly checkpoint (SAC) genes. The SAC proteins BubR1 and Mps1 were differentially modified between the cells treated with arecoline and nocodazole. This together with aurora A overexpression suggested that SAC might be partly suppressed by arecoline. As a result, the arecoline-exposed cells might produce progeny that contained various chromosomal aberrations and exhibited genomic instability. Copyright 2010 Elsevier Ltd. All rights reserved.

  15. Overexpression of Ran GTPase Components Regulating Nuclear Export, but not Mitotic Spindle Assembly, Marks Chromosome Instability and Poor Prognosis in Breast Cancer.

    Science.gov (United States)

    Vaidyanathan, Srividya; Thangavelu, Pulari U; Duijf, Pascal H G

    2016-10-01

    Ran GTPase regulates nuclear import, nuclear export, and mitotic spindle assembly. The multifunctional involvement of seventeen Ran GTPase components in these processes has complicated research into how each contributes to cancer development. To assess whether individual and process-specific misexpression of Ran GTPase components contribute to chromosome instability (CIN) and worsen breast cancer patient prognosis. Using publicly available datasets, we studied the degree of misexpression of all Ran GTPase signaling components in breast cancer, assessed their involvement in CIN and used four clinical tests to evaluate whether their misregulation may constitute independent prognostic predictors. A significant majority of Ran GTPase signaling components is overexpressed in breast cancer. Strikingly, spindle assembly components are overexpressed and associated with CIN with only marginal significance and four independent tests indicate that this does not worsen patient outcome. Overexpression of nuclear import components is neither CIN-associated nor clinically significant. In sharp contrast, overexpression of nuclear export components constitutes a strong independent marker for both CIN and poor patient prognosis. We identify Exportin 2/CSE1L, Exportin 3/XPOT, Exportin 5/XPO5, and RANBP1 as novel potential targets. We find that overexpression of Ran GTPase components involved in nuclear export, but not nuclear import or mitotic spindle assembly, is a strong CIN-associated marker for poor breast cancer prognosis. This could mean that increased nuclear export (of, for instance, pRb, p53, p73, BRCA1, p21, p27, E2F4, IκB, survivin), rather than spindle defects, mainly drives CIN and tumorigenesis. Hence, selective inhibitors of nuclear export may be effective for treating the most aggressive and chromosomally unstable breast cancers.

  16. SPINDLE CELL SARCOMA OF VAGINA- A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Sankareswari

    2013-04-01

    Full Text Available ABSTRACT : Malignant tumors of vagina are rare accounting for 1 to 4 % of all genital malignancies. Rarest of rare is spindle cell sarcoma of vagina having a very poor prognosis. 47yrs old, regularly menstruating woman, completed f amily, presented with hard painful ulcerated swelling near the vaginal introitus and l ower vaginal wall of 4 months duration. On examination, 2x4cms sized ulcerated growth with exc avated base, covered with necrotic material, present in the left antero-lateral lower e nd of vagina, inner to hymenal ring which was tender, hard, indurated, infiltrating, fixed to bas e and did not bleed to touch. Another nodule of size 1x1cm tender, hard, fixed and necrotic was pres ent below the external urethral meatus. HPE revealed Amelanotic malignant melanoma of vagin a. Immunohistochemistry revealed Spindle cell sarcoma of vagina. Tumor board recommen ded neo-adjuvant chemotherapy and radiotherapy (CT + EBRT. Of the recommended 50Gy, s he completed 46Gy in 23days and 1 course of chemotherapy (VAC. On review after 9 mont hs, the lesion disappeared clinically and she was advised to complete the treatment. Inspite o f radio and chemotherapy secondaries to lungs and brain could not be prevented and the patien t expired 20 months after the final diagnosis

  17. Expression of basement membrane antigens in spindle cell melanoma.

    Science.gov (United States)

    Prieto, V G; Woodruff, J M

    1998-07-01

    Spindle cell melanoma (SCM) is an uncommon form of melanoma that may be confused histologically with other tumors, including malignant peripheral nerve sheath tumors (MPNST). Tumors with neural differentiation and melanocytic nevi may both show basement membrane immunohistochemically and at the ultrastructural level. However, most ultrastructural studies of melanoma have failed to demonstrate well formed basement membrane around tumor cells. The presence of basement membrane has been used by some authors as evidence favoring MPNST, as opposed to SCM. To evaluate this distinction immunohistochemically, 22 primary and metastatic cutaneous melanomas having a spindle cell component (SCM) were studied using monoclonal antibodies against laminin and Type IV collagen. S100 protein and HMB45 antigen expression were also studied. All but one of the SCM were reactive for S100 protein in at least 25% of the cells. Thirteen of 20 tumors (65%) were focally reactive with HMB45. Laminin was expressed in 42% of the tumors (only membranous pattern in 3; cytoplasmic and membranous in 5). Seventeen tumors (77%) expressed type IV collagen (only membranous pattern in 7; cytoplasmic and membranous pattern in 10). Laminin and type IV collagen, known components of basement membrane, are often found in SCM. Therefore, their detection cannot be used to distinguish SCM from MPNST.

  18. Topological defects in confined populations of spindle-shaped cells

    Science.gov (United States)

    Duclos, Guillaume; Erlenkämper, Christoph; Joanny, Jean-François; Silberzan, Pascal

    2017-01-01

    Most spindle-shaped cells (including smooth muscles and sarcomas) organize in vivo into well-aligned `nematic’ domains, creating intrinsic topological defects that may be used to probe the behaviour of these active nematic systems. Active non-cellular nematics have been shown to be dominated by activity, yielding complex chaotic flows. However, the regime in which live spindle-shaped cells operate, and the importance of cell-substrate friction in particular, remains largely unexplored. Using in vitro experiments, we show that these active cellular nematics operate in a regime in which activity is effectively damped by friction, and that the interaction between defects is controlled by the system’s elastic nematic energy. Due to the activity of the cells, these defects behave as self-propelled particles and pairwise annihilate until all displacements freeze as cell crowding increases. When confined in mesoscopic circular domains, the system evolves towards two identical +1/2 disclinations facing each other. The most likely reduced positions of these defects are independent of the size of the disk, the cells’ activity or even the cell type, but are well described by equilibrium liquid crystal theory. These cell-based systems thus operate in a regime more stable than other active nematics, which may be necessary for their biological function.

  19. Cenp-meta is required for sustained spindle checkpoint

    Directory of Open Access Journals (Sweden)

    Thomas Rubin

    2014-05-01

    Full Text Available Cenp-E is a kinesin-like motor protein required for efficient end-on attachment of kinetochores to the spindle microtubules. Cenp-E immunodepletion in Xenopus mitotic extracts results in the loss of mitotic arrest and massive chromosome missegregation, whereas its depletion in mammalian cells leads to chromosome segregation defects despite the presence of a functional spindle assembly checkpoint (SAC. Cenp-meta has previously been reported to be the Drosophila homolog of vertebrate Cenp-E. In this study, we show that cenp-metaΔ mutant neuroblasts arrest in mitosis when treated with colchicine. cenp-metaΔ mutant cells display a mitotic delay. Yet, despite the persistence of the two checkpoint proteins Mad2 and BubR1 on unattached kinetochores, these cells eventually enter anaphase and give rise to highly aneuploid daughter cells. Indeed, we find that cenp-metaΔ mutant cells display a slow but continuous degradation of cyclin B, which eventually triggers the mitotic exit observed. Thus, our data provide evidence for a role of Cenp-meta in sustaining the SAC response.

  20. Accurate measurement of poleward microtubule flux in the spindle of Drosophila S2 cells.

    Science.gov (United States)

    Munzarova, Alina; Popova, Julia; Razuvaeva, Alena; Shloma, Victor; Gatti, Maurizio; Omelyanchuk, Leonid

    2016-09-01

    The spindle microtubule (MT) flux is the continuous translocation of MTs toward the spindle poles caused by MT polymerization at plus ends coupled to depolymerization at minus ends. Poleward flux is observed in both mitotic and meiotic spindles; it is evolutionarily conserved and contributes to the regulation of spindle length and anaphase chromosome movement. MT photobleaching is a tool frequently used to measure poleward flux. Spindles containing fluorescently tagged tubulin are photobleached to generate a non-fluorescent stripe, which moves toward the spindle poles allowing a measure of the flux. However, this method only permits rapid measurements of the flux, because the fluorescence of the bleached stripe recovers rapidly due to the spindle MT turnover. Here, we describe a modification of the current photobleaching-based method for flux measurement. We photobleached two large areas at the opposite sides of the metaphase plate in spindles of Drosophila S2 cells expressing Cherry-tagged tubulin, leaving unbleached only the area near the chromosomes. We then measured the speed with which the fluorescent MTs move toward the poles. We found that this method allows a measure of the flux over a two- to threefold longer time than the "single stripe" method, providing a reliable evaluation of the flux rate. © 2016 International Federation for Cell Biology.

  1. Cdk and APC activities limit the spindle-stabilizing function of Fin1 to anaphase.

    Science.gov (United States)

    Woodbury, Erika L; Morgan, David O

    2007-01-01

    The fidelity of chromosome segregation depends on proper regulation of mitotic spindle behaviour. In anaphase, spindle stability is promoted by the dephosphorylation of cyclin-dependent kinase (Cdk) substrates, which results from Cdk inactivation and phosphatase activation. Few of the critical Cdk targets have been identified. Here, we identify the budding-yeast protein Fin1 (ref. 7) as a spindle-stabilizing protein whose activity is strictly limited to anaphase by changes in its phosphorylation state and rate of degradation. Phosphorylation of Fin1 from S phase to metaphase, by the cyclin-dependent kinase Clb5-Cdk1, inhibits Fin1 association with the spindle. In anaphase, when Clb5-Cdk1 is inactivated, Fin1 is dephosphorylated by the phosphatase Cdc14. Fin1 dephosphorylation targets it to the poles and microtubules of the elongating spindle, where it contributes to spindle integrity. A non-phosphorylatable Fin1 mutant localizes to the spindle before anaphase and impairs efficient chromosome segregation. As cells complete mitosis and disassemble the spindle, the ubiqutin ligase APC(Cdh1) targets Fin1 for destruction. Our studies illustrate how phosphorylation-dependent changes in the behaviour of Cdk1 substrates influence complex mitotic processes.

  2. Age-Dependent Increase of Absence Seizures and Intrinsic Frequency Dynamics of Sleep Spindles in Rats

    Directory of Open Access Journals (Sweden)

    Evgenia Sitnikova

    2014-01-01

    Full Text Available The risk of neurological diseases increases with age. In WAG/Rij rat model of absence epilepsy, the incidence of epileptic spike-wave discharges is known to be elevated with age. Considering close relationship between epileptic spike-wave discharges and physiologic sleep spindles, it was assumed that age-dependent increase of epileptic activity may affect time-frequency characteristics of sleep spindles. In order to examine this hypothesis, electroencephalograms (EEG were recorded in WAG/Rij rats successively at the ages 5, 7, and 9 months. Spike-wave discharges and sleep spindles were detected in frontal EEG channel. Sleep spindles were identified automatically using wavelet-based algorithm. Instantaneous (localized in time frequency of sleep spindles was determined using continuous wavelet transform of EEG signal, and intraspindle frequency dynamics were further examined. It was found that in 5-months-old rats epileptic activity has not fully developed (preclinical stage and sleep spindles demonstrated an increase of instantaneous frequency from beginning to the end. At the age of 7 and 9 months, when animals developed matured and longer epileptic discharges (symptomatic stage, their sleep spindles did not display changes of intrinsic frequency. The present data suggest that age-dependent increase of epileptic activity in WAG/Rij rats affects intrinsic dynamics of sleep spindle frequency.

  3. Sustaining sleep spindles through enhanced SK2 channel activity consolidates sleep and elevates arousal threshold

    Science.gov (United States)

    Wimmer, Ralf D.; Astori, Simone; Bond, Chris T.; Rovó, Zita; Chatton, Jean-Yves; Adelman, John P.; Franken, Paul; Lüthi, Anita

    2013-01-01

    Sleep spindles are synchronized 11–15 Hz electroencephalographic (EEG) oscillations predominant during non-rapid-eye-movement sleep (NREMS). Rhythmic bursting in the reticular thalamic nucleus (nRt), arising from interplay between Cav3.3-type Ca2+ channels and Ca2+-dependent small-conductance-type 2 (SK2) K+ channels, underlies spindle generation. Correlative evidence indicates that spindles contribute to memory consolidation and protection against environmental noise in human NREMS. Here, we describe a molecular mechanism through which spindle power is selectively extended and we probed the actions of intensified spindling in the naturally sleeping mouse. Using electrophysiological recordings in acute brain slices from SK2 channel-over-expressing (SK2-OE) mice, we found that nRt bursting was potentiated and thalamic circuit oscillations were prolonged. Moreover, nRt cells showed greater resilience to transit from burst to tonic discharge in response to gradual depolarization, mimicking transitions out of NREMS. Compared to wild-type littermates, chronic EEG recordings of SK2-OE mice contained less fragmented NREMS, while the NREMS EEG power spectrum was conserved. Furthermore, EEG spindle activity was prolonged at NREMS exit. Finally, when exposed to white noise, SK2-OE mice needed stronger stimuli to arouse. Increased nRt bursting thus strengthens spindles and improves sleep quality through mechanisms independent of EEG slow-waves (< 4 Hz), suggesting SK2 signaling as a new potential therapeutic target for sleep disorders and for neuropsychiatric diseases accompanied by weakened sleep spindles. PMID:23035101

  4. Sustaining sleep spindles through enhanced SK2-channel activity consolidates sleep and elevates arousal threshold.

    Science.gov (United States)

    Wimmer, Ralf D; Astori, Simone; Bond, Chris T; Rovó, Zita; Chatton, Jean-Yves; Adelman, John P; Franken, Paul; Lüthi, Anita

    2012-10-03

    Sleep spindles are synchronized 11-15 Hz electroencephalographic (EEG) oscillations predominant during nonrapid-eye-movement sleep (NREMS). Rhythmic bursting in the reticular thalamic nucleus (nRt), arising from interplay between Ca(v)3.3-type Ca(2+) channels and Ca(2+)-dependent small-conductance-type 2 (SK2) K(+) channels, underlies spindle generation. Correlative evidence indicates that spindles contribute to memory consolidation and protection against environmental noise in human NREMS. Here, we describe a molecular mechanism through which spindle power is selectively extended and we probed the actions of intensified spindling in the naturally sleeping mouse. Using electrophysiological recordings in acute brain slices from SK2 channel-overexpressing (SK2-OE) mice, we found that nRt bursting was potentiated and thalamic circuit oscillations were prolonged. Moreover, nRt cells showed greater resilience to transit from burst to tonic discharge in response to gradual depolarization, mimicking transitions out of NREMS. Compared with wild-type littermates, chronic EEG recordings of SK2-OE mice contained less fragmented NREMS, while the NREMS EEG power spectrum was conserved. Furthermore, EEG spindle activity was prolonged at NREMS exit. Finally, when exposed to white noise, SK2-OE mice needed stronger stimuli to arouse. Increased nRt bursting thus strengthens spindles and improves sleep quality through mechanisms independent of EEG slow waves (<4 Hz), suggesting SK2 signaling as a new potential therapeutic target for sleep disorders and for neuropsychiatric diseases accompanied by weakened sleep spindles.

  5. Antagonistic activities of Klp10A and Orbit regulate spindle length, bipolarity and function in vivo.

    Science.gov (United States)

    Laycock, Joseph E; Savoian, Matthew S; Glover, David M

    2006-06-01

    The metaphase-spindle steady-state length occurs as spindle microtubules ;flux', incorporating new subunits at their plus ends, while simultaneously losing subunits from their minus ends. Orbit/Mast/CLASP is required for tubulin subunit addition at kinetochores, and several kinesins regulate spindle morphology and/or flux by serving as microtubule depolymerases. Here, we use RNA interference in S2 cells to examine the relationship between Orbit and the four predicted kinesin-type depolymerases encoded by the Drosophila genome (Klp10A, Klp59C, Klp59D and Klp67A). Single depletion of Orbit results in monopolar spindles, mitotic arrest and a subsequent increase in apoptotic cells. These phenotypes are rescued by co-depleting Klp10A but none of the other three depolymerases. Spindle bipolarity is restored by preventing the spindle collapse seen in cells that lack Orbit, leading to functional spindles that are similar to controls in shape and length. We conclude that Klp10A exclusively antagonises Orbit in the regulation of bipolar spindle formation and maintenance.

  6. A spindle checkpoint functions during mitosis in the early Caenorhabditis elegans embryo.

    Science.gov (United States)

    Encalada, Sandra E; Willis, John; Lyczak, Rebecca; Bowerman, Bruce

    2005-03-01

    During mitosis, chromosome segregation is regulated by a spindle checkpoint mechanism. This checkpoint delays anaphase until all kinetochores are captured by microtubules from both spindle poles, chromosomes congress to the metaphase plate, and the tension between kinetochores and their attached microtubules is properly sensed. Although the spindle checkpoint can be activated in many different cell types, the role of this regulatory mechanism in rapidly dividing embryonic animal cells has remained controversial. Here, using time-lapse imaging of live embryonic cells, we show that chemical or mutational disruption of the mitotic spindle in early Caenorhabditis elegans embryos delays progression through mitosis. By reducing the function of conserved checkpoint genes in mutant embryos with defective mitotic spindles, we show that these delays require the spindle checkpoint. In the absence of a functional checkpoint, more severe defects in chromosome segregation are observed in mutants with abnormal mitotic spindles. We also show that the conserved kinesin CeMCAK, the CENP-F-related proteins HCP-1 and HCP-2, and the core kinetochore protein CeCENP-C all are required for this checkpoint. Our analysis indicates that spindle checkpoint mechanisms are functional in the rapidly dividing cells of an early animal embryo and that this checkpoint can prevent chromosome segregation defects during mitosis.

  7. A comparison of the spindles in two different muscles of the frog.

    Science.gov (United States)

    Brown, M C

    1971-08-01

    1. The responses of spindles in the iliofibularis muscle of frogs to stretch during either small motor nerve fibre stimulation or the application of suxamethonium were compared.2. All spindles which were excited by small motor nerve fibre stimulation were also excited by suxamethonium, and their responses to these two methods of excitation were very similar. The drug dose was usually 5-10 mug/ml. but smaller and larger doses were effective. Large doses (> 100 mug/ml.) could sometimes lead to a reversible partial block of the spindle response to stretch.3. Suxamethonium also caused a prolonged contraction in extrafusal slow muscle fibres. This contraction was not responsible for the effect on the spindle, because the time course of its action on the muscle tension and on the spindle afferent was different.4. It was concluded that suxamethonium stimulated prolonged contraction in the small intrafusal muscle fibres, which are known to be innervated by the small motor nerve fibres.5. Only about half of the spindles in the iliofibularis muscle were excited by suxamethonium.6. In the sartorius muscle which has no slow extrafusal muscle fibres, no spindles were found to be excited by suxamethonium in the way characteristic of that due to small intrafusal muscle fibre contraction.7. It is concluded that, in frog muscles which have no slow extrafusal fibres, the muscle spindles do not have small intrafusal muscle fibres of the kind found in the iliofibularis muscle.

  8. Exploiting the compromised spindle assembly checkpoint function of tumor cells: dawn on the horizon?

    NARCIS (Netherlands)

    Schmidt, M.; Medema, R.H.

    2006-01-01

    Aneuploidy is a frequent property of cancer cells that arises as a consequence of chromosomal instability (CIN). A major safeguard mechanism protecting cells from CIN is the spindle assembly checkpoint. This checkpoint surveys proper attachment of chromosomes to the mitotic spindle and effectively s

  9. Constitutive Cdk2 activity promotes aneuploidy while altering the spindle assembly and tetraploidy checkpoints

    DEFF Research Database (Denmark)

    Jahn, Stephan C; Corsino, Patrick E; Davis, Bradley J;

    2013-01-01

    instability. Expression of these complexes in the MCF10A cell line leads to retinoblastoma protein (Rb) hyperphosphorylation, a subsequent increase in proliferation rate, and increased expression of the spindle assembly checkpoint protein Mad2. This results in a strengthening of the spindle assembly...

  10. The Plk1 target Kizuna stabilizes mitotic centrosomes to ensure spindle bipolarity.

    Science.gov (United States)

    Oshimori, Naoki; Ohsugi, Miho; Yamamoto, Tadashi

    2006-10-01

    Formation of a bipolar spindle is essential for faithful chromosome segregation at mitosis. Because centrosomes define spindle poles, defects in centrosome number and structural organization can lead to a loss of bipolarity. In addition, microtubule-mediated pulling and pushing forces acting on centrosomes and chromosomes are also important for bipolar spindle formation. Polo-like kinase 1 (Plk1) is a highly conserved Ser/Thr kinase that has essential roles in the formation of a bipolar spindle with focused poles. However, the mechanism by which Plk1 regulates spindle-pole formation is poorly understood. Here, we identify a novel centrosomal substrate of Plk1, Kizuna (Kiz), depletion of which causes fragmentation and dissociation of the pericentriolar material from centrioles at prometaphase, resulting in multipolar spindles. We demonstrate that Kiz is critical for establishing a robust mitotic centrosome architecture that can endure the forces that converge on the centrosomes during spindle formation, and suggest that Plk1 maintains the integrity of the spindle poles by phosphorylating Kiz.

  11. Evaluation of the Dynamicity of Mitotic Exit Network and Spindle Position Checkpoint Components on Spindle Pole Bodies by Fluorescence Recovery After Photobleaching (FRAP).

    Science.gov (United States)

    Caydasi, Ayse Koca; Pereira, Gislene

    2017-01-01

    Fluorescence recovery after photobleaching (FRAP) is a powerful technique to study in vivo binding and diffusion dynamics of fluorescently labeled proteins. In this chapter, we describe how to determine spindle pole body (SPB) binding dynamics of mitotic exit network (MEN) and spindle position checkpoint (SPOC) proteins using FRAP microscopy. Procedures presented here include the growth of the yeast cultures, sample preparation, image acquisition and analysis.

  12. Canoe binds RanGTP to promote Pins(TPR)/Mud-mediated spindle orientation.

    Science.gov (United States)

    Wee, Brett; Johnston, Christopher A; Prehoda, Kenneth E; Doe, Chris Q

    2011-10-31

    Regulated spindle orientation maintains epithelial tissue integrity and stem cell asymmetric cell division. In Drosophila melanogaster neural stem cells (neuroblasts), the scaffolding protein Canoe (Afadin/Af-6 in mammals) regulates spindle orientation, but its protein interaction partners and mechanism of action are unknown. In this paper, we use our recently developed induced cell polarity system to dissect the molecular mechanism of Canoe-mediated spindle orientation. We show that a previously uncharacterized portion of Canoe directly binds the Partner of Inscuteable (Pins) tetratricopeptide repeat (TPR) domain. The Canoe-Pins(TPR) interaction recruits Canoe to the cell cortex and is required for activation of the Pins(TPR)-Mud (nuclear mitotic apparatus in mammals) spindle orientation pathway. We show that the Canoe Ras-association (RA) domains directly bind RanGTP and that both the Canoe(RA) domains and RanGTP are required to recruit Mud to the cortex and activate the Pins/Mud/dynein spindle orientation pathway.

  13. A force-generating machinery maintains the spindle at the cell center during mitosis.

    Science.gov (United States)

    Garzon-Coral, Carlos; Fantana, Horatiu A; Howard, Jonathon

    2016-05-27

    The position and orientation of the mitotic spindle is precisely regulated to ensure the accurate partition of the cytoplasm between daughter cells and the correct localization of the daughters within growing tissue. Using magnetic tweezers to perturb the position of the spindle in intact cells, we discovered a force-generating machinery that maintains the spindle at the cell center during metaphase and anaphase in one- and two-cell Caenorhabditis elegans embryos. The forces increase with the number of microtubules and are larger in smaller cells. The machinery is rigid enough to suppress thermal fluctuations to ensure precise localization of the mitotic spindle, yet compliant enough to allow molecular force generators to fine-tune the position of the mitotic spindle to facilitate asymmetric division.

  14. Specific polar subpopulations of astral microtubules control spindle orientation and symmetric neural stem cell division.

    Science.gov (United States)

    Mora-Bermúdez, Felipe; Matsuzaki, Fumio; Huttner, Wieland B

    2014-07-04

    Mitotic spindle orientation is crucial for symmetric vs asymmetric cell division and depends on astral microtubules. Here, we show that distinct subpopulations of astral microtubules exist, which have differential functions in regulating spindle orientation and division symmetry. Specifically, in polarized stem cells of developing mouse neocortex, astral microtubules reaching the apical and basal cell cortex, but not those reaching the central cell cortex, are more abundant in symmetrically than asymmetrically dividing cells and reduce spindle orientation variability. This promotes symmetric divisions by maintaining an apico-basal cleavage plane. The greater abundance of apical/basal astrals depends on a higher concentration, at the basal cell cortex, of LGN, a known spindle-cell cortex linker. Furthermore, newly developed specific microtubule perturbations that selectively decrease apical/basal astrals recapitulate the symmetric-to-asymmetric division switch and suffice to increase neurogenesis in vivo. Thus, our study identifies a novel link between cell polarity, astral microtubules, and spindle orientation in morphogenesis.

  15. A LCMT1-PME-1 methylation equilibrium controls mitotic spindle size.

    Science.gov (United States)

    Xia, Xiaoyu; Gholkar, Ankur; Senese, Silvia; Torres, Jorge Z

    2015-01-01

    Leucine carboxyl methyltransferase-1 (LCMT1) and protein phosphatase methylesterase-1 (PME-1) are essential enzymes that regulate the methylation of the protein phosphatase 2A catalytic subunit (PP2AC). LCMT1 and PME-1 have been linked to the regulation of cell growth and proliferation, but the underlying mechanisms have remained elusive. We show here an important role for an LCMT1-PME-1 methylation equilibrium in controlling mitotic spindle size. Depletion of LCMT1 or overexpression of PME-1 led to long spindles. In contrast, depletion of PME-1, pharmacological inhibition of PME-1 or overexpression of LCMT1 led to short spindles. Furthermore, perturbation of the LCMT1-PME-1 methylation equilibrium led to mitotic arrest, spindle assembly checkpoint activation, defective cell divisions, induction of apoptosis and reduced cell viability. Thus, we propose that the LCMT1-PME-1 methylation equilibrium is critical for regulating mitotic spindle size and thereby proper cell division.

  16. Expert and crowd-sourced validation of an individualized sleep spindle detection method employing complex demodulation and individualized normalization

    Directory of Open Access Journals (Sweden)

    Laura eRay

    2015-09-01

    Full Text Available A spindle detection method was developed that: 1 extracts the signal of interest (i.e., spindle-related phasic changes in sigma relative to ongoing background sigma activity using complex demodulation, 2 accounts for variations of spindle characteristics across the night, scalp derivations and between individuals, and 3 employs a minimum number of sometimes arbitrary, user-defined parameters. Complex demodulation was used to extract instantaneous power in the spindle band. To account for intra- and inter-individual differences, the signal was z-score transformed using a 60s sliding window, per channel, over the course of the recording. Spindle events were detected with a z-score threshold corresponding to a low probability (e.g., 99th percentile. Spindle characteristics, such as amplitude, duration and oscillatory frequency, were derived for each individual spindle following detection, which permits spindles to be subsequently and flexibly categorized as slow or fast spindles from a single detection pass. Spindles were automatically detected in 15 young healthy subjects. Two experts manually identified spindles from C3 during Stage 2 sleep, from each recording; one employing conventional guidelines, and the other, identifying spindles with the aid of a sigma (11-16 Hz filtered channel. These spindles were then compared between raters and to the automated detection to identify the presence of true positives, true negatives, false positives and false negatives. This method of automated spindle detection resolves or avoids many of the limitations that complicate automated spindle detection, and performs well compared to a group of non-experts, and importantly, has good external validity with respect to the extant literature in terms of the characteristics of automatically detected spindles.

  17. Older drivers with cognitive impairment: Perceived changes in driving skills, driving-related discomfort and self-regulation of driving

    DEFF Research Database (Denmark)

    Meng, A.; Siren, A.; Teasdale, Thomas William

    2013-01-01

    The results of a previous study indicate that in general, older drivers who recognise cognitive problems show realistic self-assessment of changes in their driving skills and that driving-related discomfort may function as an indirect monitoring of driving ability, contributing to their safe...... driving performance. The aim of the present study was to examine whether these findings also apply to cognitively impaired older drivers. Structured face-to-face interviews were conducted with 25 cognitively impaired older drivers. The results showed that the participants were most likely to report...... their driving skills as unchanged. There was an association between level of discomfort and avoidance of driving situations, but not between cognitive status and discomfort or avoidance. The results suggest that cognitively impaired older drivers constitute a unique group; while cognitively impaired older...

  18. Sympathetic modulation of muscle spindle afferent sensitivity to stretch in rabbit jaw closing muscles.

    Science.gov (United States)

    Roatta, S; Windhorst, U; Ljubisavljevic, M; Johansson, H; Passatore, M

    2002-04-01

    Previous reports showed that sympathetic stimulation affects the activity of muscle spindle afferents (MSAs). The aim of the present work is to study the characteristics of sympathetic modulation of MSA response to stretch: (i) on the dynamic and static components of the stretch response, and (ii) on group Ia and II MSAs to evaluate potentially different effects. In anaesthetised rabbits, the peripheral stump of the cervical sympathetic nerve (CSN) was stimulated at 10 impulses s(-1) for 45-90 s. The responses of single MSAs to trapezoidal displacement of the mandible were recorded from the mesencephalic trigeminal nucleus. The following characteristic parameters were determined from averaged trapezoidal responses: initial frequency (IF), peak frequency at the end of the ramp (PF), and static index (SI). From these, other parameters were derived: dynamic index (DI = PF - SI), dynamic difference (DD = PF - IF) and static difference (SD = SI - IF). The effects of CSN stimulation were also evaluated during changes in the state of intrafusal muscle fibre contraction induced by succinylcholine and curare. In a population of 124 MSAs, 106 units (85.4 %) were affected by sympathetic stimulation. In general, while changes in resting discharge varied among different units (Ia vs. II) and experimental conditions (curarised vs. non-curarised), ranging from enhancement to strong depression of firing, the amplitude of the response to muscle stretches consistently decreased. This was confirmed and detailed in a quantitative analysis performed on 49 muscle spindle afferents. In both the non-curarised (23 units) and curarised (26 units) condition, stimulation of the CSN reduced the response amplitude in terms of DD and SD, but hardly affected DI. The effects were equally present in both Ia and II units; they were shown to be independent from gamma drive and intrafusal muscle tone and not secondary to muscle hypoxia. Sympathetic action on the resting discharge (IF) was less

  19. Functional analysis of Survivin in spindle assembly in Xenopus egg extracts.

    Science.gov (United States)

    Canovas, Pedro M; Guadagno, Thomas M

    2007-01-01

    Survivin is a member of the inhibitor of apoptosis (IAP) protein family that serves critical roles in mitosis and cytokinesis. Many studies have suggested Survivin's involvement in spindle regulation, but direct biochemical evidence for this has been lacking. Using the cell-free system of Xenopus egg extracts, we tested whether Survivin was necessary for the assembly of metaphase spindles. Removal or inhibition of Xenopus Survivin causes the disruption in the formation of metaphase spindles. In particular, we observe the generation of microtubule (MT) asters or poorly formed shortened spindle structures. In the latter phenotype the spindle structures display a decrease pole-to-pole length and a reduction of MTs around the chromatin indicating that Survivin may promote the stabilization of MT-chromatin interactions. In addition, function analysis of Survivin's conserved phosphorylation site Thr34 (Thr43 in Xenopus) and tubulin-binding domain was also assessed in regulating spindle assembly. Treatment of Xenopus egg extracts with a recombinant Survivin mutant that contained an alanine residue substitution at Thr43 (SURT43A mutant) or that was missing the C-terminal tubulin-binding domain (SURCL mutant) produced an increased frequency of MT asters and shorten abnormal spindle structures in Xenopus egg extracts. Interestingly, a phosphomimetic mutation made at residue Thr43 of Survivin (SURT43E mutant) generated a high frequency of MT asters implying that premature 'activation' of Survivin may interfere with an early stage of spindle assembly. Taken together, we propose that Survivin is a necessary component of the mitotic spindle and its phosphorylation at residue Thr43 is important for Survivin function in spindle assembly. 2006 Wiley-Liss, Inc.

  20. The spindle pole bodies facilitate nuclear envelope division during closed mitosis in fission yeast.

    Science.gov (United States)

    Zheng, Liling; Schwartz, Cindi; Magidson, Valentin; Khodjakov, Alexey; Oliferenko, Snezhana

    2007-07-01

    Many organisms divide chromosomes within the confines of the nuclear envelope (NE) in a process known as closed mitosis. Thus, they must ensure coordination between segregation of the genetic material and division of the NE itself. Although many years of work have led to a reasonably clear understanding of mitotic spindle function in chromosome segregation, the NE division mechanism remains obscure. Here, we show that fission yeast cells overexpressing the transforming acid coiled coil (TACC)-related protein, Mia1p/Alp7p, failed to separate the spindle pole bodies (SPBs) at the onset of mitosis, but could assemble acentrosomal bipolar and antiparallel spindle structures. Most of these cells arrested in anaphase with fully extended spindles and nonsegregated chromosomes. Spindle poles that lacked the SPBs did not lead the division of the NE during spindle elongation, but deformed it, trapping the chromosomes within. When the SPBs were severed by laser microsurgery in wild-type cells, we observed analogous deformations of the NE by elongating spindle remnants, resulting in NE division failure. Analysis of dis1Delta cells that elongate spindles despite unattached kinetochores indicated that the SPBs were required for maintaining nuclear shape at anaphase onset. Strikingly, when the NE was disassembled by utilizing a temperature-sensitive allele of the Ran GEF, Pim1p, the abnormal spindles induced by Mia1p overexpression were capable of segregating sister chromatids to daughter cells, suggesting that the failure to divide the NE prevents chromosome partitioning. Our results imply that the SPBs preclude deformation of the NE during spindle elongation and thus serve as specialized structures enabling nuclear division during closed mitosis in fission yeast.

  1. The spindle pole bodies facilitate nuclear envelope division during closed mitosis in fission yeast.

    Directory of Open Access Journals (Sweden)

    Liling Zheng

    2007-07-01

    Full Text Available Many organisms divide chromosomes within the confines of the nuclear envelope (NE in a process known as closed mitosis. Thus, they must ensure coordination between segregation of the genetic material and division of the NE itself. Although many years of work have led to a reasonably clear understanding of mitotic spindle function in chromosome segregation, the NE division mechanism remains obscure. Here, we show that fission yeast cells overexpressing the transforming acid coiled coil (TACC-related protein, Mia1p/Alp7p, failed to separate the spindle pole bodies (SPBs at the onset of mitosis, but could assemble acentrosomal bipolar and antiparallel spindle structures. Most of these cells arrested in anaphase with fully extended spindles and nonsegregated chromosomes. Spindle poles that lacked the SPBs did not lead the division of the NE during spindle elongation, but deformed it, trapping the chromosomes within. When the SPBs were severed by laser microsurgery in wild-type cells, we observed analogous deformations of the NE by elongating spindle remnants, resulting in NE division failure. Analysis of dis1Delta cells that elongate spindles despite unattached kinetochores indicated that the SPBs were required for maintaining nuclear shape at anaphase onset. Strikingly, when the NE was disassembled by utilizing a temperature-sensitive allele of the Ran GEF, Pim1p, the abnormal spindles induced by Mia1p overexpression were capable of segregating sister chromatids to daughter cells, suggesting that the failure to divide the NE prevents chromosome partitioning. Our results imply that the SPBs preclude deformation of the NE during spindle elongation and thus serve as specialized structures enabling nuclear division during closed mitosis in fission yeast.

  2. Neurotrophin-3 and trkC in muscle are non-essential for the development of mouse muscle spindles

    NARCIS (Netherlands)

    Kucera, J; Fan, GP; Walro, J; Copray, S; Tessarollo, L; Jaenisch, R

    1998-01-01

    NEUROTROPHIN-3 (NT3) or TrkC null mutant mice were examined for the presence of muscle spindles. Muscles of mastication, but not limbs, contained spindles in newborn and adolescent mutants. The intramuscular distribution and morphological properties of spindles in mutant masticatory muscles were ind

  3. VARIABLE INERTIAL DAMPER AND ITS APPLICATION IN ZERO-DRIVE GEAR HOBBING MACHINE

    Institute of Scientific and Technical Information of China (English)

    LIU Runai; ZHANG Genbao; GONG Li; HUANG Qiang

    2006-01-01

    A variable inertial damper, whose viscous damping coefficient can be adjusted by changing the gap between inertia wheel and motor spindle, is designed in servomechanism of zero-drive hobbing machine and is directly attached on the motor spindle. The mathematical model of servo system with inertial damper is built. By using theoretical analysis and system simulation, it is demonstrated that the variable inertial damper with optimal damping coefficient and moment of inertia should lead to no resonance point in wider frequency range of exciting force. Therefore, its application in zero-drive hobbing machine makes this system not only achieve higher system stiffness to overcome load torque fluctuation, but also gain better stability.

  4. Responses of muscle spindles in feline dorsal neck muscles to electrical stimulation of the cervical sympathetic nerve.

    Science.gov (United States)

    Hellström, F; Roatta, S; Thunberg, J; Passatore, M; Djupsjöbacka, M

    2005-09-01

    Previous studies performed in jaw muscles of rabbits and rats have demonstrated that sympathetic outflow may affect the activity of muscle spindle afferents (MSAs). The resulting impairment of MSA information has been suggested to be involved in the genesis and spread of chronic muscle pain. The present study was designed to investigate sympathetic influences on muscle spindles in feline trapezius and splenius muscles (TrSp), as these muscles are commonly affected by chronic pain in humans. Experiments were carried out in cats anesthetized with alpha-chloralose. The effect of electrical stimulation (10 Hz for 90 s or 3 Hz for 5 min) of the peripheral stump of the cervical sympathetic nerve (CSN) was investigated on the discharge of TrSp MSAs (units classified as Ia-like and II-like) and on their responses to sinusoidal stretching of these muscles. In some of the experiments, the local microcirculation of the muscles was monitored by laser Doppler flowmetry. In total, 46 MSAs were recorded. Stimulation of the CSN at 10 Hz powerfully depressed the mean discharge rate of the majority of the tested MSAs (73%) and also affected the sensitivity of MSAs to sinusoidal changes of muscle length, which were evaluated in terms of amplitude and phase of the sinusoidal fitting of unitary activity. The amplitude was significantly reduced in Ia-like units and variably affected in II-like units, while in general the phase was affected little and not changed significantly in either group. The discharge of a smaller percentage of tested units was also modulated by 3-Hz CSN stimulation. Blockade of the neuromuscular junctions by pancuronium did not induce any changes in MSA responses to CSN stimulation, showing that these responses were not secondary to changes in extrafusal or fusimotor activity. Further data showed that the sympathetically induced modulation of MSA discharge was not secondary to the concomitant reduction of muscle blood flow induced by the stimulation. Hence

  5. HARMONIC DRIVE SELECTION

    Directory of Open Access Journals (Sweden)

    Piotr FOLĘGA

    2014-03-01

    Full Text Available The variety of types and sizes currently in production harmonic drive is a problem in their rational choice. Properly selected harmonic drive must meet certain requirements during operation, and achieve the anticipated service life. The paper discusses the problems associated with the selection of the harmonic drive. It also presents the algorithm correct choice of harmonic drive. The main objective of this study was to develop a computer program that allows the correct choice of harmonic drive by developed algorithm.

  6. PB-M网桥在高炉水冲渣传动监控系统中的应用%Application of the PB-M Bridge in Blast Furnace Slag Granulation Drive Monitoring and Contorl System

    Institute of Scientific and Technical Information of China (English)

    田海; 赵德琦; 任清娟

    2012-01-01

    简述了基于在高炉水冲渣传动监控系统的工艺背景下,Profibus-Modbus网桥在控制系统中使支持Profibus协议的设备与支持Modbus RTU协议的设备之间进行通讯协议转换的作用,使得支持不同通讯协议的设备之间能够进行数据传递,并且给出了设计方法.应用证明PB-M总线桥在控制系统中的稳定可靠,作为协议转换,总线桥很适合工业控制现场使用.%This article gives a brief introduction based on the technology background of the blast furnace slag granulation drive monitoring and control system. Profibus-Modbus bridge which supports the Profibus protocol equipment and support Modbus RTU protocol for communication between devices in protocol conversion function in the control system,allowing the support of different communication protocols to pass data between devices and gives the design idea. The practical application proved that PB-M bridge was a reliable and stable equipment,which was very suitable to be used in the industrial controlling field as the protocol transition bus bridge.

  7. Axon and muscle spindle hyperplasia in the myostatin null mouse.

    Science.gov (United States)

    Elashry, Mohamed I; Otto, Anthony; Matsakas, Antonios; El-Morsy, Salah E; Jones, Lisa; Anderson, Bethan; Patel, Ketan

    2011-02-01

    Germline deletion of the myostatin gene results in hyperplasia and hypertrophy of the tension-generating (extrafusal) fibres in skeletal muscle. As this gene is expressed predominantly in myogenic tissues it offers an excellent model with which to investigate the quantitative relationship between muscle and axonal development. Here we show that skeletal muscle hyperplasia in myostatin null mouse is accompanied by an increase in nerve fibres in major nerves of both the fore- and hindlimbs. We show that axons within these nerves undergo hypertrophy. Furthermore, we provide evidence that the age-related neural atrophic process is delayed in the absence of myostatin. Finally, we show that skeletal muscle hyperplasia in the myostatin null mouse is accompanied by an increase in the number of muscle spindles (also called stretch receptors or proprioceptors). However, our work demonstrates that the mechanisms regulating intrafusal fibre hyperplasia and hypertrophy differ from those that control the aetiology of extrafusal fibres.

  8. 高速电主轴系统热变形分析及抑制措施%Thermal deformation analysis & suppression measures about high-speed electric spindle system

    Institute of Scientific and Technical Information of China (English)

    李永芳; 张启萍; 王瑞; 李新宁; 苟卫东; 杨锦斌

    2012-01-01

    Analyzes both from spindle structure and heat source of electric spindle of machining center, this article proposes a technical solutions to reduce the temperature rise of spindle, main measures which have been taken are to reduce the heat amount of bearing and motor, spindle bearing cooling and oil lubrication systems. And these has already been tested by the Belgium-based Lemmens dynamic multi-channel monitors and a high accuracy temperature sensor pt 100, the temperature rise high-speed spindle of machining center has been effectively controlled, and both its mechanical performance and reliability have been guaranteed. It has an extraordinary practical significance on the application & potentiality of high speed spindle of machining Center.%从加工中心电主轴的结构和热源两方面对电主轴热变形原因进行了分析,提出了降低电主轴温升的技术方案,主要采取了减小轴承发热量、减小电动机发热量、主轴轴承循环冷却及油气润滑系统等措施,通过基于比利时Lemmens多通道动态监测仪和高精度pt 100温度传感器的试验验证,高速加工中心电主轴的温升得到了有效控制,其机械性能、可靠性也得到了保障,对加工中心高速电主轴的应用及发挥其潜能具有非凡的现实意义.

  9. Spindle activity and monosynaptic reflex excitability during foreperiod.

    Science.gov (United States)

    Gerilovsky, L; Struppler, A; Altmann, H; Velho, F

    1983-11-01

    Healthy volunteers were instructed to perform an isometric plantar foot flexion as quickly as possible after a foreperiod (FP) of 1000 msec defined by two clicks (warning signal (WS) and response signal (RS). In 6 volunteers the H reflex was evoked in triceps surae muscle and recorded by surface electrodes (stimulus intensity 30% of maximum). The H reflex was elicited at WS and RS as well as during FP at intervals of 100 msec. H reflex amplitudes were taken as a sign of monosynaptic reflex excitability (MSRE). Amplitudes during FP were compared with the average control values at rest. Relaxation of lower limb muscles before and during FP was controlled by EMG. MSRE was increased in the first part of FP with a maximum at 300 msec after WS and decreased in the second part, with a minimum at 800 msec after WS. In a second series of experiments, in 10 volunteers, single fiber activity from primary muscle spindle afferents was recorded with tungsten electrodes from deep peroneal nerve (6 records) and from tibial nerve (3 records). The activity of primary spindle afferents before and during the FP was calculated by instantaneous discharge frequency and histograms of spike distribution. The EMG was taken from sural triceps and anterior tibial muscles with needle electrodes; a mechanogram of tendon deflection was taken by an appropriate strain gauge. In 5 primary afferents without spontaneous activity at rest and during FP, discharge started with a delay of 10-15 msec after the onset of EMG activity during the motor reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Sleep spindles and hippocampal functional connectivity in human NREM sleep.

    Science.gov (United States)

    Andrade, Kátia C; Spoormaker, Victor I; Dresler, Martin; Wehrle, Renate; Holsboer, Florian; Sämann, Philipp G; Czisch, Michael

    2011-07-13

    We investigated human hippocampal functional connectivity in wakefulness and throughout non-rapid eye movement sleep. Young healthy subjects underwent simultaneous EEG and functional magnetic resonance imaging (fMRI) measurements at 1.5 T under resting conditions in the descent to deep sleep. Continuous 5 min epochs representing a unique sleep stage (i.e., wakefulness, sleep stages 1 and 2, or slow-wave sleep) were extracted. fMRI time series of subregions of the hippocampal formation (HF) (cornu ammonis, dentate gyrus, and subiculum) were extracted based on cytoarchitectonical probability maps. We observed sleep stage-dependent changes in HF functional coupling. The HF was integrated to variable strength in the default mode network (DMN) in wakefulness and light sleep stages but not in slow-wave sleep. The strongest functional connectivity between the HF and neocortex was observed in sleep stage 2 (compared with both slow-wave sleep and wakefulness). We observed a strong interaction of sleep spindle occurrence and HF functional connectivity in sleep stage 2, with increased HF/neocortical connectivity during spindles. Moreover, the cornu ammonis exhibited strongest functional connectivity with the DMN during wakefulness, while the subiculum dominated hippocampal functional connectivity to frontal brain regions during sleep stage 2. Increased connectivity between HF and neocortical regions in sleep stage 2 suggests an increased capacity for possible global information transfer, while connectivity in slow-wave sleep is reflecting a functional system optimal for segregated information reprocessing. Our data may be relevant to differentiating sleep stage-specific contributions to neural plasticity as proposed in sleep-dependent memory consolidation.

  11. Aurora A kinase regulates proper spindle positioning in C. elegans and in human cells.

    Science.gov (United States)

    Kotak, Sachin; Afshar, Katayon; Busso, Coralie; Gönczy, Pierre

    2016-08-01

    Accurate spindle positioning is essential for error-free cell division. The one-cell Caenorhabditis elegans embryo has proven instrumental for dissecting mechanisms governing spindle positioning. Despite important progress, how the cortical forces that act on astral microtubules to properly position the spindle are modulated is incompletely understood. Here, we report that the PP6 phosphatase PPH-6 and its associated subunit SAPS-1, which positively regulate pulling forces acting on spindle poles, associate with the Aurora A kinase AIR-1 in C. elegans embryos. We show that acute inactivation of AIR-1 during mitosis results in excess pulling forces on astral microtubules. Furthermore, we uncover that AIR-1 acts downstream of PPH-6-SAPS-1 in modulating spindle positioning, and that PPH-6-SAPS-1 negatively regulates AIR-1 localization at the cell cortex. Moreover, we show that Aurora A and the PP6 phosphatase subunit PPP6C are also necessary for spindle positioning in human cells. There, Aurora A is needed for the cortical localization of NuMA and dynein during mitosis. Overall, our work demonstrates that Aurora A kinases and PP6 phosphatases have an ancient function in modulating spindle positioning, thus contributing to faithful cell division.

  12. The centromere geometry essential for keeping mitosis error free is controlled by spindle forces.

    Science.gov (United States)

    Loncarek, Jadranka; Kisurina-Evgenieva, Olga; Vinogradova, Tatiana; Hergert, Polla; La Terra, Sabrina; Kapoor, Tarun M; Khodjakov, Alexey

    2007-11-29

    Accurate segregation of chromosomes, essential for the stability of the genome, depends on 'bi-orientation'-simultaneous attachment of each individual chromosome to both poles of the mitotic spindle. On bi-oriented chromosomes, kinetochores (macromolecular complexes that attach the chromosome to the spindle) reside on the opposite sides of the chromosome's centromere. In contrast, sister kinetochores shift towards one side of the centromere on 'syntelic' chromosomes that erroneously attach to one spindle pole with both sister kinetochores. Syntelic attachments often arise during spindle assembly and must be corrected to prevent chromosome loss. It is assumed that restoration of proper centromere architecture occurs automatically owing to elastic properties of the centromere. Here we test this assumption by combining laser microsurgery and chemical biology assays in cultured mammalian cells. We find that kinetochores of syntelic chromosomes remain juxtaposed on detachment from spindle microtubules. These findings reveal that correction of syntelic attachments involves an extra step that has previously been overlooked: external forces must be applied to move sister kinetochores to the opposite sides of the centromere. Furthermore, we demonstrate that the shape of the centromere is important for spindle assembly, because bipolar spindles do not form in cells lacking centrosomes when multiple chromosomes with juxtaposed kinetochores are present. Thus, proper architecture of the centromere makes an important contribution to achieving high fidelity of chromosome segregation.

  13. Error-prone mammalian female meiosis from silencing the spindle assembly checkpoint without normal interkinetochore tension.

    Science.gov (United States)

    Kolano, Agnieszka; Brunet, Stéphane; Silk, Alain D; Cleveland, Don W; Verlhac, Marie-Hélène

    2012-07-03

    It is well established that chromosome segregation in female meiosis I (MI) is error-prone. The acentrosomal meiotic spindle poles do not have centrioles and are not anchored to the cortex via astral microtubules. By Cre recombinase-mediated removal in oocytes of the microtubule binding site of nuclear mitotic apparatus protein (NuMA), which is implicated in anchoring microtubules at poles, we determine that without functional NuMA, microtubules lose connection to MI spindle poles, resulting in highly disorganized early spindle assembly. Subsequently, very long spindles form with hyperfocused poles. The kinetochores of homologs make attachments to microtubules in these spindles but with reduced tension between them and accompanied by alignment defects. Despite this, the spindle assembly checkpoint is normally silenced and the advance to anaphase I and first polar body extrusion takes place without delay. Females without functional NuMA in oocytes are sterile, producing aneuploid eggs with altered chromosome number. These findings establish that in mammalian MI, the spindle assembly checkpoint is unable to sustain meiotic arrest in the presence of one or few misaligned and/or misattached kinetochores with reduced interkinetochore tension, thereby offering an explanation for why MI in mammals is so error-prone.

  14. Spindle Misorientation of Cerebral and Cerebellar Progenitors Is a Mechanistic Cause of Megalencephaly.

    Science.gov (United States)

    Li, Huaibiao; Kroll, Torsten; Moll, Jürgen; Frappart, Lucien; Herrlich, Peter; Heuer, Heike; Ploubidou, Aspasia

    2017-09-18

    Misoriented division of neuroprogenitors, by loss-of-function studies of centrosome or spindle components, has been linked to the developmental brain defects microcephaly and lissencephaly. As these approaches also affect centrosome biogenesis, spindle assembly, or cell-cycle progression, the resulting pathologies cannot be attributed solely to spindle misorientation. To address this issue, we employed a truncation of the spindle-orienting protein RHAMM. This truncation of the RHAMM centrosome-targeting domain does not have an impact on centrosome biogenesis or on spindle assembly in vivo. The RHAMM mutants exhibit misorientation of the division plane of neuroprogenitors, without affecting the division rate of these cells, resulting against expectation in megalencephaly associated with cerebral cortex thickening, cerebellum enlargement, and premature cerebellum differentiation. We conclude that RHAMM associates with the spindle of neuroprogenitor cells via its centrosome-targeting domain, where it regulates differentiation in the developing brain by orienting the spindle. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Rotation of Meiotic Spindle Is Controlled by Microfilaments in Mouse Oocytes

    Institute of Scientific and Technical Information of China (English)

    Da-YuanChen; Jin-SongLi; LiLian; LeiLei; Zhi-MingHan; Qing-YuanSun

    2005-01-01

    The completion of meiosis requires the spatial and temporal coordination of cytokinesis and karyokirlesis. During meiotic maturation, many events, such as formation, location, and rotation of the meiotic spindle as well as chromosomal movement,Polar body extrusion,and pronuclear migration,are dependent on regulation of the cytoskeleton system.To study functions of microfilaments in meiosis,we induced metaphase Ⅱ(MII)mouse oocytes to resume meiosis by in vitro fertilization or parthenogenetic activation,and we treated such oocytes with cytochalasin B(CB).The changes of the meiotic spindle,as visualized in preparations stained for β-tubulin and chromation,were observed by fluorescent confocal microscopy.The meiotic spindle of Mll oocytes was observed to be parallel to the plasmalemma.After meiosis had resumed,the spindle rotated to the vertical position so that the second polar body could be extruded into the perivitelline space.When meiosis resumed and oocytes were treated with 10μg/ml of CB,the spindle rotation was inhibited.Consequently,the oocyte formed an extra pronucleus instead of extruding a second polar body.These results indicate that spindle rotation is essential for polar body extrusion;it is the microfilaments that play a crucial role in regulating rotation of the meiotic spindle.

  16. Spindle cell melanocytic lesions: part II--an approach to intradermal proliferations and horizontally oriented lesions.

    Science.gov (United States)

    Sade, Shachar; Al Habeeb, Ayman; Ghazarian, Danny

    2010-05-01

    Melanocytic lesions show great morphological diversity in their architecture and the cytomorphological appearance of their composite cells. Whereas functional melanocytes show a dendritic cytomorphology and territorial isolation, lesional nevomelanocytes and melanoma cells typically show epithelioid, spindled or mixed cytomorphologies, and a range of architectural arrangements. Spindling is common to melanocytic lesions, and may either be a characteristic feature or a divergent appearance. The presence of spindle cells may mask the melanocytic nature of a lesion, and is often disconcerting, either due to its infrequent appearance in a particular lesion or its interpretation as a dedifferentiated phenotype. Spindle cell melanocytic lesions follow the full spectrum of potential biological outcomes, and difficulty may be experienced judging the nature of a lesion due to a lack of consistently reliable features to predict biological behaviour. Over time, recognition of numerous histomorphological features that may portend a more aggressive lesion have been identified; however, the translation of these features into a diagnostic entity requires a gestalt approach. Although most spindle cell melanocytic lesions may reliably be resolved through this standard approach, problem areas do exist for the surgical pathologist or dermatopathologist. With this review (part II of II), we complete our discussion of spindle cell melanocytic lesions, in order to: (1) model a systematic approach to such lesions; and (2) provide familiarity with those melanocytic lesions which either typically or occasionally display a spindled cytomorphology.

  17. Aurora A phosphorylates MCAK to control ran-dependent spindle bipolarity.

    Science.gov (United States)

    Zhang, Xin; Ems-McClung, Stephanie C; Walczak, Claire E

    2008-07-01

    During mitosis, mitotic centromere-associated kinesin (MCAK) localizes to chromatin/kinetochores, a cytoplasmic pool, and spindle poles. Its localization and activity in the chromatin region are regulated by Aurora B kinase; however, how the cytoplasmic- and pole-localized MCAK are regulated is currently not clear. In this study, we used Xenopus egg extracts to form spindles in the absence of chromatin and centrosomes and found that MCAK localization and activity are tightly regulated by Aurora A. This regulation is important to focus microtubules at aster centers and to facilitate the transition from asters to bipolar spindles. In particular, we found that MCAK colocalized with NuMA and XMAP215 at the center of Ran asters where its activity is regulated by Aurora A-dependent phosphorylation of S196, which contributes to proper pole focusing. In addition, we found that MCAK localization at spindle poles was regulated through another Aurora A phosphorylation site (S719), which positively enhances bipolar spindle formation. This is the first study that clearly defines a role for MCAK at the spindle poles as well as identifies another key Aurora A substrate that contributes to spindle bipolarity.

  18. Kinesin-5 motors are required for organization of spindle microtubules in Silvetia compressa zygotes

    Directory of Open Access Journals (Sweden)

    Kropf Darryl L

    2006-08-01

    Full Text Available Abstract Background Monastrol, a chemical inhibitor specific to the Kinesin-5 family of motor proteins, was used to examine the functional roles of Kinesin-5 proteins during the first, asymmetric cell division cycle in the brown alga Silvetia compressa. Results Monastrol treatment had no effect on developing zygotes prior to entry into mitosis. After mitosis entry, monastrol treatment led to formation of monasters and cell cycle arrest in a dose dependent fashion. These findings indicate that Kinesin-5 motors maintain spindle bipolarity, and are consistent with reports in animal cells. At low drug concentrations that permitted cell division, spindle position was highly displaced from normal, resulting in abnormal division planes. Strikingly, application of monastrol also led to formation of numerous cytasters throughout the cytoplasm and multipolar spindles, uncovering a novel effect of monastrol treatment not observed in animal cells. Conclusion We postulate that monastrol treatment causes spindle poles to break apart forming cytasters, some of which capture chromosomes and become supernumerary spindle poles. Thus, in addition to maintaining spindle bipolarity, Kinesin-5 members in S. compressa likely organize microtubules at spindle poles. To our knowledge, this is the first functional characterization of the Kinesin-5 family in stramenopiles.

  19. Meiosis in a triploid hybrid of Gossypium: high frequency of secondary bipolar spindles at metaphase II

    Indian Academy of Sciences (India)

    Mosareza Vafaie-Tabar; Shanti Chandrashekaran

    2007-01-01

    Studies on meiosis in pollen mother cells (PMCs) of a triploid interspecific hybrid ($3x = 39$ chromosomes, AAD) between tetraploid Gossypium hirsutum ($4n = 2x = 52$,AADD) and diploid G. arboreum ($2n = 2x = 26$,AA) are reported. During meiotic metaphase I, 13 AA bivalents and 13 D univalents are expected in the hybrid. However, only 28% of the PMCs had this expected configuration. The rest of the PMCs had between 8 and 12 bivalents and between 12 and 17 univalents. Univalents lagged at anaphase I, and at metaphase II one or a group of univalents remained scattered in the cytoplasm and failed to assemble at a single metaphase plate. Primary bipolar spindles organized around the bivalents and multivalents. In addition to the primary spindle, several secondary and smaller bipolar spindles organized themselves around individual univalents and groups of univalents. Almost all (97%) of the PMCs showed secondary spindles. Each spindle functioned independently and despite their multiple numbers in a cell, meiosis I proceeded normally, with polyad formation. These observations strongly support the view that in plant meiocytes bilateral kinetochore symmetry is not required for establishing a bipolar spindle and that single unpaired chromosomes can initiate and stabilize the formation of a functional bipolar spindle.

  20. p21-activated kinase 4 regulates mitotic spindle positioning and orientation.

    Science.gov (United States)

    Bompard, Guillaume; Morin, Nathalie

    2012-01-01

    During mitosis, microtubules (MTs) are massively rearranged into three sets of highly dynamic MTs that are nucleated from the centrosomes to form the mitotic spindle. Tight regulation of spindle positioning in the dividing cell and chromosome alignment at the center of the metaphase spindle are required to ensure perfect chromosome segregation and to position the cytokinetic furrow that will specify the two daughter cells. Spindle positioning requires regulation of MT dynamics, involving depolymerase activities together with cortical and kinetochore-mediated pushing and pulling forces acting on astral MTs and kinetochore fibres. These forces rely on MT motor activities. Cortical pulling forces exerted on astral MTs depend upon dynein/dynactin complexes and are essential in both symmetric and asymmetric cell division. A well-established spindle positioning pathway regulating the cortical targeting of dynein/dynactin involves the conserved LGN (Leu-Gly-Asn repeat-enriched-protein) and NuMA (microtubule binding nuclear mitotic apparatus protein) complex. Spindle orientation is also regulated by integrin-mediated cell adhesion and actin retraction fibres that respond to mechanical stress and are influenced by the microenvironment of the dividing cell. Altering the capture of astral MTs or modulating pulling forces affects spindle position, which can impair cell division, differentiation and embryogenesis. In this general scheme, the activity of mitotic kinases such as Auroras and Plk1 (Polo-like kinase 1) is crucial. Recently, the p21-activated kinases (PAKs) emerged as novel important players in mitotic progression. In our recent article, we demonstrated that PAK4 regulates spindle positioning in symmetric cell division. In this commentary, and in light of recent published studies, we discuss how PAK4 could participate in the regulation of mechanisms involved in spindle positioning and orientation.

  1. An assessment of six muscle spindle models for predicting sensory information during human wrist movements.

    Directory of Open Access Journals (Sweden)

    Puja eMalik

    2016-01-01

    Full Text Available Background: The muscle spindle is an important sensory organ for proprioceptive information, yet there have been few attempts to use Shannon information theory to quantify the capacity of human muscle spindles to encode sensory input.Methods: Computer simulations linked kinematics, to biomechanics, to six muscle spindle models that generated predictions of firing rate. The predicted firing rates were compared to firing rates of human muscle spindles recorded during a step-tracking (center-out task to validate their use. The models were then used to predict firing rates during random movements with statistical properties matched to the ergonomics of human wrist movements. The data were analyzed for entropy and mutual information.Results: Three of the six models produced predictions that approximated the firing rate of human spindles during the step-tracking task. For simulated random movements these models predicted mean rates of 16.0±4.1 imp/s (mean±sd, peak firing rates <50 imp/s and zero firing rate during an average of 25% of the movement. The average entropy of the neural response was 4.1±0.3 bits and is an estimate of the maximum information that could be carried by muscles spindles during ecologically valid movements. The information about tendon displacement preserved in the neural response was 0.10±0.05 bits per symbol; whereas 1.25±0.30 bits per symbol of velocity input were preserved in the neural response of the spindle models.Conclusions: Muscle spindle models, originally based on cat experiments, have predictive value for modeling responses of human muscle spindles with minimal parameter optimization. These models predict more than 10-fold more velocity over length information encoding during ecologically valid movements. These results establish theoretical parameters for developing neuroprostheses for proprioceptive function.

  2. Automated high-throughput quantification of mitotic spindle positioning from DIC movies of Caenorhabditis embryos.

    Directory of Open Access Journals (Sweden)

    David Cluet

    Full Text Available The mitotic spindle is a microtubule-based structure that elongates to accurately segregate chromosomes during anaphase. Its position within the cell also dictates the future cell cleavage plan, thereby determining daughter cell orientation within a tissue or cell fate adoption for polarized cells. Therefore, the mitotic spindle ensures at the same time proper cell division and developmental precision. Consequently, spindle dynamics is the matter of intensive research. Among the different cellular models that have been explored, the one-cell stage C. elegans embryo has been an essential and powerful system to dissect the molecular and biophysical basis of spindle elongation and positioning. Indeed, in this large and transparent cell, spindle poles (or centrosomes can be easily detected from simple DIC microscopy by human eyes. To perform quantitative and high-throughput analysis of spindle motion, we developed a computer program ACT for Automated-Centrosome-Tracking from DIC movies of C. elegans embryos. We therefore offer an alternative to the image acquisition and processing of transgenic lines expressing fluorescent spindle markers. Consequently, experiments on large sets of cells can be performed with a simple setup using inexpensive microscopes. Moreover, analysis of any mutant or wild-type backgrounds is accessible because laborious rounds of crosses with transgenic lines become unnecessary. Last, our program allows spindle detection in other nematode species, offering the same quality of DIC images but for which techniques of transgenesis are not accessible. Thus, our program also opens the way towards a quantitative evolutionary approach of spindle dynamics. Overall, our computer program is a unique macro for the image- and movie-processing platform ImageJ. It is user-friendly and freely available under an open-source licence. ACT allows batch-wise analysis of large sets of mitosis events. Within 2 minutes, a single movie is processed

  3. Early stages of spindle formation and independence of chromosome and microtubule cycles in Haemanthus endosperm.

    Science.gov (United States)

    Smirnova, E A; Bajer, A S

    1998-01-01

    We analyzed transformation of the interphase microtubular cytoskeleton into the prophase spindle and followed the pattern of spindle axis determination. Microtubules in endosperm of the higher plant Haemanthus (Scadoxus) were stained by the immunogold and immunogold silver-enhanced methods. Basic structural units involved in spindle morphogenesis were "microtubule converging centers." We emphasized the importance of relative independence of chromosomal and microtubular cycles, and the influence of these cycles on the progress of mitosis. Cells with moderately desynchronized cycles were functional, but extreme desynchronization led to aberrant mitosis. There were three distinct phases of spindle development. The first one comprised interphase and early to mid-prophase. During this phase, the interphase microtubule meshwork radiating from the nuclear surface into the cytoplasm rearranged and formed a dense microtubule cage around the nucleus. The second phase comprised mid to late prophase, and resulted in the formation of normal (bipolar) or transitory aberrant (apolar or multipolar) prophase spindles. The third phase comprised late prophase with prometaphase. The onset of prometaphase was accompanied by a rapid association of microtubule converging centers with kinetochores. In this stage aberrant spindles transformed invariably into bipolar ones. Lateral association of a few bipolar kinetochore fibers at early prometaphase established the core of the bipolar spindle and its alignment. We concluded that (1) spindle formation is a largely independent microtubular process modified by the chromosomal/kinetochore cycle; and (2) the initial polarity of the spindle is established by microtubule converging centers, which are a functional substitute of the centrosome/MTOC. We believe that the dynamics of microtubule converging centers is an expression of microtubule self-organization driven by motor proteins as proposed by Mitchison [1992: Philos. Trans. R. Soc. Lond. B

  4. Design of Accelerated Reliability Test for CNC Motorized Spindle Based on Vibration Signal

    Directory of Open Access Journals (Sweden)

    Chen Chao

    2016-01-01

    Full Text Available Motorized spindle is the key functional component of CNC machining centers which is a mechatronics system with long life and high reliability. The reliability test cycle of motorized spindle is too long and infeasible. This paper proposes a new accelerated test for reliability evaluation of motorized spindle. By field reliability test, authors collect and calculate the load data including rotational speed, cutting force and torque. Load spectrum distribution law is analyzed. And authors design a test platform to apply the load spectrum. A new method to define the fuzzy acceleration factor based on the vibration signal is proposed. Then the whole test plan of accelerated reliability test is done.

  5. CKAP2 is necessary to ensure the faithful spindle bipolarity in a dividing diploid hepatocyte.

    Science.gov (United States)

    Yoo, Bum Ho; Park, Chi-Hu; Kim, Hyun-Jun; Kang, Du-Seock; Bae, Chang-Dae

    2016-05-13

    Spindle bipolarity is crucial for segregating chromosome during somatic cell division. Previous studies have suggested that cytoskeleton associated protein 2 (CKAP2) is involved in spindle assembly and chromosome segregation. In this study, we show that CKAP2-depleted primary hepatocytes exhibit over-duplicated centrosomes with disjoined chromosomes from metaphase plate. These cells proceed to apoptosis or multipolar cell division and subsequent apoptotic cell death. In addition, a mouse liver regeneration experiment showed a marked decrease in efficiency of hepatic regeneration in CKAP2-depleted liver. These data suggest a physiological role of CKAP2 in the formation of spindle bipolarity, which is necessary for maintaining chromosomal stability.

  6. Sleep spindle-related reactivation of category-specific cortical regions after learning face-scene associations

    DEFF Research Database (Denmark)

    Bergmann, Til O; Mölle, Matthias; Diedrichs, Jens

    2012-01-01

    ) and functional magnetic resonance imaging (fMRI) recordings in humans, we show that sleep spindles play a key role in the reactivation of memory-related neocortical representations. On separate days, participants either learned face-scene associations or performed a visuomotor control task. Spindle-coupled......, reactivation did not only occur in temporal synchrony with spindle events but was tuned by ongoing variations in spindle amplitude. These learning-related increases in spindle-coupled neocortical activity were topographically specific because reactivation was restricted to the face- and scene-selective visual...... cortical areas previously activated during pre-sleep learning. Spindle-coupled hippocampal activation was stronger the better the participant had performed at prior learning. These results are in agreement with the notion that sleep spindles orchestrate the reactivation of new hippocampal...

  7. Analysis of static and dynamic characteristic of spindle system and its structure optimization in camshaft grinding machine

    Science.gov (United States)

    Feng, Jianjun; Li, Chengzhe; Wu, Zhi

    2017-08-01

    As an important part of the valve opening and closing controller in engine, camshaft has high machining accuracy requirement in designing. Taking the high-speed camshaft grinder spindle system as the research object and the spindle system performance as the optimizing target, this paper firstly uses Solidworks to establish the three-dimensional finite element model (FEM) of spindle system, then conducts static analysis and the modal analysis by applying the established FEM in ANSYS Workbench, and finally uses the design optimization function of the ANSYS Workbench to optimize the structure parameter in the spindle system. The study results prove that the design of the spindle system fully meets the production requirements, and the performance of the optimized spindle system is promoted. Besides, this paper provides an analysis and optimization method for other grinder spindle systems.

  8. Eu/Tb codoped spindle-shaped fluorinated hydroxyapatite nanoparticles for dual-color cell imaging.

    Science.gov (United States)

    Ma, Baojin; Zhang, Shan; Qiu, Jichuan; Li, Jianhua; Sang, Yuanhua; Xia, Haibing; Jiang, Huaidong; Claverie, Jerome; Liu, Hong

    2016-06-02

    Lanthanide doped fluorinated hydroxyapatite (FAp) nanoparticles are promising cell imaging nanomaterials but they are excited at wavelengths which do not match the light sources usually found in a commercial confocal laser scanning microscope (CLSM). In this work, we have successfully prepared spindle-shaped Eu/Tb codoped FAp nanoparticles by a hydrothermal method. Compared with single Eu doped FAp, Eu/Tb codoped FAp can be excited by a 488 nm laser, and exhibit both green and red light emission. By changing the amounts of Eu and Tb peaks, the emission in the green region (500-580 nm) can be decreased to the benefit of the emission in the red region (580-720 nm), thus reaching a balanced dual color emission. Using MC3T3-E1 cells co-cultured with Eu/Tb codoped FAp nanoparticles, it is observed that the nanoparticles are cytocompatible even at a concentration as high as 800 μg ml(-1). The Eu/Tb codoped FAp nanoparticles are located in the cytoplasm and can be monitored by dual color-green and red imaging with a single excitation light at 488 nm. At a concentration of 200 μg ml(-1), the cytoplasm is saturated in 8 hours, and Eu/Tb codoped FAp nanoparticles retain their fluorescence for at least 3 days. The cytocompatible Eu/Tb codoped FAp nanoparticles with unique dual color emission will be of great use for cell and tissue imaging.

  9. Muscle spindle composition and distribution in human young masseter and biceps brachii muscles reveal early growth and maturation.

    Science.gov (United States)

    Osterlund, Catharina; Liu, Jing-Xia; Thornell, Lars-Eric; Eriksson, Per-Olof

    2011-04-01

    Significant changes in extrafusal fiber type composition take place in the human masseter muscle from young age, 3-7 years, to adulthood, in parallel with jaw-face skeleton growth, changes of dentitions and improvement of jaw functions. As motor and sensory control systems of muscles are interlinked, also the intrafusal fiber population, that is, muscle spindles, should undergo age-related changes in fiber type appearance. To test this hypothesis, we examined muscle spindles in the young masseter muscle and compared the result with previous data on adult masseter spindles. Also muscle spindles in the young biceps brachii muscle were examined. The result showed that muscle spindle composition and distribution were alike in young and adult masseter. As for the adult masseter, young masseter contained exceptionally large muscle spindles, and with the highest spindle density and most complex spindles found in the deep masseter portion. Hence, contrary to our hypothesis, masseter spindles do not undergo major morphological changes between young age and adulthood. Also in the biceps, young spindles were alike adult spindles. Taken together, the results showed that human masseter and biceps muscle spindles are morphologically mature already at young age. We conclude that muscle spindles in the human young masseter and biceps precede the extrafusal fiber population in growth and maturation. This in turn suggests early reflex control and proprioceptive demands in learning and maturation of jaw motor skills. Similarly, well-developed muscle spindles in young biceps reflect early need of reflex control in learning and performing arm motor behavior. Copyright © 2011 Wiley-Liss, Inc.

  10. Induction of robust de novo centrosome amplification, high-grade spindle multipolarity and metaphase catastrophe: a novel chemotherapeutic approach.

    Science.gov (United States)

    Pannu, V; Rida, P C G; Ogden, A; Clewley, R; Cheng, A; Karna, P; Lopus, M; Mishra, R C; Zhou, J; Aneja, R

    2012-07-12

    Centrosome amplification (CA) and resultant chromosomal instability have long been associated with tumorigenesis. However, exacerbation of CA and relentless centrosome declustering engender robust spindle multipolarity (SM) during mitosis and may induce cell death. Recently, we demonstrated that a noscapinoid member, reduced bromonoscapine, (S)-3-(R)-9-bromo-5-(4,5-dimethoxy-1,3-dihydroisobenzofuran-1-yl)-4-methoxy-6-methyl-5,6,7,8-tetrahydro-[1,3]dioxolo-[4,5-g]isoquinoline (Red-Br-nos), induces reactive oxygen species (ROS)-mediated autophagy and caspase-independent death in prostate cancer PC-3 cells. Herein, we show that Red-Br-nos induces ROS-dependent DNA damage that resulted in high-grade CA and SM in PC-3 cells. Unlike doxorubicin, which causes double-stranded DNA breaks and chronic G2 arrest accompanied by 'templated' CA, Red-Br-nos-mediated DNA damage elicits de novo CA during a transient S/G2 stall, followed by checkpoint abrogation and mitotic entry to form aberrant mitotic figures with supernumerary spindle poles. Attenuation of multipolar phenotype in the presence of tiron, a ROS inhibitor, indicated that ROS-mediated DNA damage was partly responsible for driving CA and SM. Although a few cells (∼5%) yielded to aberrant cytokinesis following an 'anaphase catastrophe', most mitotically arrested cells (∼70%) succumbed to 'metaphase catastrophe,' which was caspase-independent. This report is the first documentation of rapid de novo centrosome formation in the presence of parent centrosome by a noscapinoid family member, which triggers death-inducing SM via a unique mechanism that distinguishes it from other ROS-inducers, conventional DNA-damaging agents, as well as other microtubule-binding drugs.

  11. Driving After a Stroke

    Science.gov (United States)

    ... Inspirational Stories Stroke Heroes Among Us Driving After Stroke Updated:Jul 23,2015 Can I drive after ... more tips for daily living . Let's Talk About Stroke Fact Sheets Our stroke fact sheets cover treatments, ...

  12. Electric Vehicle - Economical driving

    DEFF Research Database (Denmark)

    Jensen, VCE, Steen V.; Schøn, Henriette

    1999-01-01

    Instruct the reader in getting most satisfaction out of an EV, especially concerning driving and loading.......Instruct the reader in getting most satisfaction out of an EV, especially concerning driving and loading....

  13. Dementia and driving

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000028.htm Dementia and driving To use the sharing features on ... please enable JavaScript. If your loved one has dementia , deciding when they can no longer drive may ...

  14. Gear bearing drive

    Science.gov (United States)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  15. Poleward tubulin flux in spindles: regulation and function in mitotic cells.

    Science.gov (United States)

    Buster, Daniel W; Zhang, Dong; Sharp, David J

    2007-08-01

    The poleward flux of tubulin subunits through spindle microtubules is a striking and conserved phenomenon whose function and molecular components remain poorly understood. To screen for novel components of the flux machinery, we utilized RNA interference to deplete regulators of microtubule dynamics, individually and in various combinations, from S2 cells and examined the resulting impact on flux rate. This led to the identification of two previously unknown flux inhibitors, KLP59C and KLP67A, and a flux promoter, Mini-spindles. Furthermore, we find that flux rate is regulated by functional antagonism among microtubule stabilizers and destabilizers specifically at plus ends. Finally, by examining mitosis on spindles in which flux has been up- or down-regulated or restored after the codepletion of antagonistic flux regulators, we show that flux is an integral contributor to anaphase A but is not responsible for chromosome congression, interkinetochore tension, or the establishment of normal spindle length during prometaphase/metaphase.

  16. A Case Report of Spindle Cell (Sarcomatoid Carcinoma of the Larynx

    Directory of Open Access Journals (Sweden)

    Harry Boamah

    2012-01-01

    Full Text Available Spindle cell carcinoma (SpCC or sarcomatoid carcinoma is a highly malignant variant of squamous cell carcinoma which comprises 2% to 3% of all laryngeal cancers. It is considered to be a biphasic tumor that is composed of a squamous cell carcinoma (in situ or invasive and spindle cell carcinoma with sarcomatous appearance. Most spindle cell tumors are polypoid and pedunculated; they are often detected at an early stage, removed by polypectomy during diagnosis, and tend to have a very good prognosis. We present a case of spindle cell carcinoma in a 67-year-old Caucasian male who presented with progressive hoarseness of his voice, dysphagia, odynophagia and a 20-pound weight loss. The patient underwent direct laryngoscopy with excision of the malignant mass and received radiation therapy. His symptoms gradually improved, and he regained good control of his voice.

  17. A spindle cell hemangioendothelioma on the head resembling an arteriovenous malformation.

    Science.gov (United States)

    Higashino, Takuya; Hirai, Rintaro

    2014-07-01

    A spindle cell hemangioendothelioma is a relatively uncommon lesion, especially on the head and neck. Recurrence occurs after local excision of 50% to 60% of these lesions; therefore, it is important to recognize this unusual neoplasm and avoid misdiagnosis. Here, we report a rare case of a spindle cell hemangioendothelioma of the head. A 37-year-old woman presented with a soft subcutaneous mass, 2.5 cm in size, on her right occipital region. The mass pulsated strongly and a thrill was present. Magnetic resonance imaging showed that some dilated feeding arteries flowed into the mass and that a flow-void sign was present. The lesion looked like an arteriovenous malformation, and a marginal resection was performed. Histologically, there was a mix of cavernous vascular cavities and Kaposi sarcomalike spindle cell vascular zones, which is compatible with a spindle cell hemangioendothelioma.

  18. Automated three-dimensional single cell phenotyping of spindle dynamics, cell shape, and volume

    CERN Document Server

    Plumb, Kemp; Pelletier, Vincent; Kilfoil, Maria L

    2015-01-01

    We present feature finding and tracking algorithms in 3D in living cells, and demonstrate their utility to measure metrics important in cell biological processes. We developed a computational imaging hybrid approach that combines automated three-dimensional tracking of point-like features with surface determination from which cell (or nuclear) volume, shape, and planes of interest can be extracted. After validation, we applied the technique to real space context-rich dynamics of the mitotic spindle, and cell volume and its relationship to spindle length, in dividing living cells. These methods are additionally useful for automated segregation of pre-anaphase and anaphase spindle populations in budding yeast. We found that genetic deletion of the yeast kinesin-5 mitotic motor cin8 leads to large mother and daughter cells that were indistinguishable based on size, and that in those cells the spindle length becomes uncorrelated with cell size. The technique can be used to visualize and quantify tracked feature c...

  19. Identification of MAC1: A Small Molecule That Rescues Spindle Bipolarity in Monastrol-Treated Cells.

    Science.gov (United States)

    Al-Obaidi, Naowras; Mitchison, Timothy J; Crews, Craig M; Mayer, Thomas U

    2016-06-17

    The genetic integrity of each organism is intimately tied to the correct segregation of its genome during mitosis. Insights into the underlying mechanisms are fundamental for both basic research and the development of novel strategies to treat mitosis-relevant diseases such as cancer. Due to their fast mode of action, small molecules are invaluable tools to dissect mitosis. Yet, there is a great demand for novel antimitotic compounds. We performed a chemical genetic suppression screen to identify compounds that restore spindle bipolarity in cells treated with Monastrol, an inhibitor of the mitotic kinesin Eg5. We identified one compound-MAC1-that rescued spindle bipolarity in cells lacking Eg5 activity. Mechanistically, MAC1 induces the formation of additional microtubule nucleation centers, which allows kinesin Kif15-dependent bipolar spindle assembly in the absence of Eg5 activity. Thus, our chemical genetic suppression screen revealed novel unexpected insights into the mechanism of spindle assembly in mammalian cells.

  20. Novel approach for determining the optimal axial preload of a simulating rotary table spindle system

    Institute of Scientific and Technical Information of China (English)

    SHAN Xiao-biao; XIE Tao; CHEN Wei-shan

    2007-01-01

    This paper presents a new theoretical model to determine the optimal axial preload ora spindle system, for challenging the traditional method which relies heavily on experience of engineers. The axial preloading stiffness was treated as the sum of the spindle modal stiffness and the framework elastic stiffness, based on a novel concept that magnitude of preloads can be controlled by measuring the resonant frequency of a spindle system. By employing an example of a certain type of aircraft simulating rotary table, the modal stiffness was measured on the Agilent 35670A Dynamic Signal Analyzer by experimental modal analysis. The equivalent elastic stiffness was simulated by both finite element analysis in ANSYS(R) and a curve fitting in MATLAB(R). Results showed that the static preloading stiffness of the spindle was 7.2125×107 N/m, and that the optimal preloading force was 120.0848 N. Practical application proved the feasibility of our method.

  1. Hierarchical nesting of slow oscillations, spindles and ripples in the human hippocampus during sleep.

    Science.gov (United States)

    Staresina, Bernhard P; Bergmann, Til Ole; Bonnefond, Mathilde; van der Meij, Roemer; Jensen, Ole; Deuker, Lorena; Elger, Christian E; Axmacher, Nikolai; Fell, Juergen

    2015-11-01

    During systems-level consolidation, mnemonic representations initially reliant on the hippocampus are thought to migrate to neocortical sites for more permanent storage, with an eminent role of sleep for facilitating this information transfer. Mechanistically, consolidation processes have been hypothesized to rely on systematic interactions between the three cardinal neuronal oscillations characterizing non-rapid eye movement (NREM) sleep. Under global control of de- and hyperpolarizing slow oscillations (SOs), sleep spindles may cluster hippocampal ripples for a precisely timed transfer of local information to the neocortex. We used direct intracranial electroencephalogram recordings from human epilepsy patients during natural sleep to test the assumption that SOs, spindles and ripples are functionally coupled in the hippocampus. Employing cross-frequency phase-amplitude coupling analyses, we found that spindles were modulated by the up-state of SOs. Notably, spindles were found to in turn cluster ripples in their troughs, providing fine-tuned temporal frames for the hypothesized transfer of hippocampal memory traces.

  2. Research Progress of Key Technology of High-Speed and High Precision Motorized Spindles

    Institute of Scientific and Technical Information of China (English)

    XIONG Wan-li; MI Hai-qing; HUANG Hon-gwu

    2005-01-01

    High speed machining and high precision machining are two tendencies of the manufacturing technology worldwide. The motorized spindle is the core component of the machine tools for achieving the high speed and high precise machining, which affects the general development level of the machine tools to a great extent. Progress of the key techniques is reviewed in this paper, in which the high speed and high precision spindle bearings, the dynamical and thermal characteristics of spindles, the design technique of the high frequency motors and the drivers, the anti-electromagnetic damage technique of the motors, and the machining and assembling technique are involved. Finally, tha development tendencies of the motorized spindles are presented.

  3. Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles.

    Science.gov (United States)

    Tsukiboshi, Taisuke; Sato, Hajime; Tanaka, Yuto; Saito, Mitsuru; Toyoda, Hiroki; Morimoto, Toshifumi; Türker, Kemal Sitki; Maeda, Yoshinobu; Kang, Youngnam

    2012-11-01

    Spindle Ia afferents may be differentially involved in voluntary isometric contraction, depending on the pattern of synaptic connections in spindle reflex pathways. We investigated how isometric contraction of masseter muscles is regulated through the activity of their muscle spindles that contain the largest number of intrafusal fibers among skeletal muscle spindles by examining the effects of vibration of muscle spindles on the voluntary isometric contraction. Subjects were instructed to hold the jaw at resting position by counteracting ramp loads applied on lower molar teeth. In response to the increasing-ramp load, the root mean square (RMS) of masseter EMG activity almost linearly increased under no vibration, while displaying a steep linear increase followed by a slower increase under vibration. The regression line of the relationship between the load and RMS was significantly steeper under vibration than under no vibration, suggesting that the subjects overestimated the ramp load and excessively counteracted it as reflected in the emergence of bite pressure. In response to the decreasing-ramp load applied following the increasing one, the RMS hardly decreased under vibration unlike under no vibration, leading to a generation of bite pressure even after the offset of the negative-ramp load until the vibration was ceased. Thus the subjects overestimated the increasing rate of the load while underestimating the decreasing rate of the load, due to the vibration-induced illusion of jaw opening. These observations suggest that spindle Ia/II inputs play crucial roles both in estimating the load and in controlling the isometric contraction of masseter muscles in the jaw-closed position.

  4. Afferent Innervation, Muscle Spindles, and Contractures Following Neonatal Brachial Plexus Injury in a Mouse Model.

    Science.gov (United States)

    Nikolaou, Sia; Hu, Liangjun; Cornwall, Roger

    2015-10-01

    We used an established mouse model of elbow flexion contracture after neonatal brachial plexus injury (NBPI) to test the hypothesis that preservation of afferent innervation protects against contractures and is associated with preservation of muscle spindles and ErbB signaling. A model of preganglionic C5 through C7 NBPI was first tested in mice with fluorescent axons using confocal imaging to confirm preserved afferent innervation of spindles despite motor end plate denervation. Preganglionic and postganglionic injuries were then created in wild-type mice. Four weeks later, we assessed total and afferent denervation of the elbow flexors by musculocutaneous nerve immunohistochemistry. Biceps muscle volume and cross-sectional area were measured by micro computed tomography. An observer who was blinded to the study protocol measured elbow flexion contractures. Biceps spindle and muscle fiber morphology and ErbB signaling pathway activity were assessed histologically and immunohistochemically. Preganglionic and postganglionic injuries caused similar total denervation and biceps muscle atrophy. However, after preganglionic injuries, afferent innervation was partially preserved and elbow flexion contractures were significantly less severe. Spindles degenerated after postganglionic injury but were preserved after preganglionic injury. ErbB signaling was inactivated in denervated spindles after postganglionic injury but ErbB signaling activity was preserved in spindles after preganglionic injury with retained afferent innervation. Preganglionic and postganglionic injuries were associated with upregulation of ErbB signaling in extrafusal muscle fibers. Contractures after NBPI are associated with muscle spindle degeneration and loss of spindle ErbB signaling activity. Preservation of afferent innervation maintained spindle development and ErbB signaling activity, and protected against contractures. Pharmacologic modulation of ErbB signaling, which is being investigated as a

  5. Can loss of muscle spindle afferents explain the ataxic gait in Riley–Day syndrome?

    OpenAIRE

    Macefield, Vaughan G.; Norcliffe-Kaufmann, Lucy; Gutiérrez, Joel; Axelrod, Felicia B.; Kaufmann, Horacio

    2011-01-01

    The Riley–Day syndrome is the most common of the hereditary sensory and autonomic neuropathies (Type III). Among the well-recognized clinical features are reduced pain and temperature sensation, absent deep tendon reflexes and a progressively ataxic gait. To explain the latter we tested the hypothesis that muscle spindles, or their afferents, are absent in hereditary sensory and autonomic neuropathy III by attempting to record from muscle spindle afferents from a nerve supplying the leg in 10...

  6. Error-prone mammalian female meiosis from silencing the spindle assembly checkpoint without normal interkinetochore tension

    OpenAIRE

    Kolano, Agnieszka; Brunet, Stéphane; Silk, Alain D.; Cleveland, Don W.; Verlhac, Marie-Hélène

    2012-01-01

    It is well established that chromosome segregation in female meiosis I (MI) is error-prone. The acentrosomal meiotic spindle poles do not have centrioles and are not anchored to the cortex via astral microtubules. By Cre recombinase-mediated removal in oocytes of the microtubule binding site of nuclear mitotic apparatus protein (NuMA), which is implicated in anchoring microtubules at poles, we determine that without functional NuMA, microtubules lose connection to MI spindle poles, resulting ...

  7. An AFM-based methodology for measuring axial and radial error motions of spindles

    Science.gov (United States)

    Geng, Yanquan; Zhao, Xuesen; Yan, Yongda; Hu, Zhenjiang

    2014-05-01

    This paper presents a novel atomic force microscopy (AFM)-based methodology for measurement of axial and radial error motions of a high precision spindle. Based on a modified commercial AFM system, the AFM tip is employed as a cutting tool by which nano-grooves are scratched on a flat surface with the rotation of the spindle. By extracting the radial motion data of the spindle from the scratched nano-grooves, the radial error motion of the spindle can be calculated after subtracting the tilting errors from the original measurement data. Through recording the variation of the PZT displacement in the Z direction in AFM tapping mode during the spindle rotation, the axial error motion of the spindle can be obtained. Moreover the effects of the nano-scratching parameters on the scratched grooves, the tilting error removal method for both conditions and the method of data extraction from the scratched groove depth are studied in detail. The axial error motion of 124 nm and the radial error motion of 279 nm of a commercial high precision air bearing spindle are achieved by this novel method, which are comparable with the values provided by the manufacturer, verifying this method. This approach does not need an expensive standard part as in most conventional measurement approaches. Moreover, the axial and radial error motions of the spindle can both be obtained, indicating that this is a potential means of measuring the error motions of the high precision moving parts of ultra-precision machine tools in the future.

  8. Solar disks and solar cycles : spindle whorls and the dawn of solar art in postclassic Mexico

    OpenAIRE

    Brumfiel, Elisabeth

    2007-01-01

    Sun disks are a common motif in spindle whorl decorations at Xaltocan, Mexico. These and other forms of symbolism on domestic artifacts suggest that women participated in the solar cosmologies of Postclassic Central Mexico. These symbols and their cosmologies precede and anticipate the principles of Aztec state religion. Thus, the spindle whorls with solar symbolism suggest that rulers appropriated the symbolism of household units in their efforts to establish the legitimacy of their states. ...

  9. Meiotic spindle normality predicts live birth in patients with recurrent in vitro fertilization failure.

    Science.gov (United States)

    Kilani, Suha; Chapman, Michael G

    2014-02-01

    To investigate the impact of meiotic spindle normality on live birth rates in women with recurrent IVF failure. A retrospective comparative study. A large private sector IVF service in Sydney, Australia. Five hundred five intracytoplasmic sperm injection (ICSI)/ET cycles of patients who fulfilled the criteria for recurrent IVF failure, three or more previous fresh or frozen ETs with no ongoing pregnancy. Polarized light microscopy was used at the time of ICSI. Clinical pregnancy rates (PR) and live birth rates (LBR) were compared depending on the morphology of the meiotic spindle of the oocyte(s) from which the embryo(s) were transferred. Women receiving embryos where at least one was derived from a normally spindled oocyte had significantly increased clinical PR and LBR when compared with those who had only embryos derived from abnormally spindled oocytes (clinical PR: 31% vs. 7%; odds ratio [OR], 6.45; 95% confidence interval [CI] 3.65-11.40) and (LBR: 24% vs. 4%; OR, 7.24; 95% CI 3.62-14.49). Comparison between the abnormal spindle groups showed significantly higher clinical PR and LBR from the group of patients receiving embryos where at least one was derived from an oocyte with no visible spindle compared with the group receiving embryos from dysmorphic spindles only (clinical PR: 9% vs. 6%; OR, 0.58; 95% CI 0.22-1.57 and LBR: 8% vs. 1%; OR, 0.16; 95% CI 0.03-0.77). Normally spindled oocytes, as determined by polarized light microscopy, are associated with significantly higher clinical PRs in patients with recurrent IVF failure. Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  10. Active Control for Multinode Unbalanced Vibration of Flexible Spindle Rotor System with Active Magnetic Bearing

    OpenAIRE

    Xiaoli Qiao; Guojun Hu

    2017-01-01

    The unbalanced vibration of the spindle rotor system in high-speed cutting processes not only seriously affects the surface quality of the machined products, but also greatly reduces the service life of the electric spindle. However, since the unbalanced vibration is often distributed on different node positions, the multinode unbalanced vibration greatly exacerbates the difficulty of vibration control. Based on the traditional influence coefficient method for controlling the vibration of a f...

  11. Genes involved in centrosome-independent mitotic spindle assembly in Drosophila S2 cells.

    Science.gov (United States)

    Moutinho-Pereira, Sara; Stuurman, Nico; Afonso, Olga; Hornsveld, Marten; Aguiar, Paulo; Goshima, Gohta; Vale, Ronald D; Maiato, Helder

    2013-12-01

    Animal mitotic spindle assembly relies on centrosome-dependent and centrosome-independent mechanisms, but their relative contributions remain unknown. Here, we investigated the molecular basis of the centrosome-independent spindle assembly pathway by performing a whole-genome RNAi screen in Drosophila S2 cells lacking functional centrosomes. This screen identified 197 genes involved in acentrosomal spindle assembly, eight of which had no previously described mitotic phenotypes and produced defective and/or short spindles. All 197 genes also produced RNAi phenotypes when centrosomes were present, indicating that none were entirely selective for the acentrosomal pathway. However, a subset of genes produced a selective defect in pole focusing when centrosomes were absent, suggesting that centrosomes compensate for this shape defect. Another subset of genes was specifically associated with the formation of multipolar spindles only when centrosomes were present. We further show that the chromosomal passenger complex orchestrates multiple centrosome-independent processes required for mitotic spindle assembly/maintenance. On the other hand, despite the formation of a chromosome-enriched RanGTP gradient, S2 cells depleted of RCC1, the guanine-nucleotide exchange factor for Ran on chromosomes, established functional bipolar spindles. Finally, we show that cells without functional centrosomes have a delay in chromosome congression and anaphase onset, which can be explained by the lack of polar ejection forces. Overall, these findings establish the constitutive nature of a centrosome-independent spindle assembly program and how this program is adapted to the presence/absence of centrosomes in animal somatic cells.

  12. A mitotic kinase scaffold depleted in testicular seminomas impacts spindle orientation in germ line stem cells.

    Science.gov (United States)

    Hehnly, Heidi; Canton, David; Bucko, Paula; Langeberg, Lorene K; Ogier, Leah; Gelman, Irwin; Santana, L Fernando; Wordeman, Linda; Scott, John D

    2015-09-25

    Correct orientation of the mitotic spindle in stem cells underlies organogenesis. Spindle abnormalities correlate with cancer progression in germ line-derived tumors. We discover a macromolecular complex between the scaffolding protein Gravin/AKAP12 and the mitotic kinases, Aurora A and Plk1, that is down regulated in human seminoma. Depletion of Gravin correlates with an increased mitotic index and disorganization of seminiferous tubules. Biochemical, super-resolution imaging, and enzymology approaches establish that this Gravin scaffold accumulates at the mother spindle pole during metaphase. Manipulating elements of the Gravin-Aurora A-Plk1 axis prompts mitotic delay and prevents appropriate assembly of astral microtubules to promote spindle misorientation. These pathological responses are conserved in seminiferous tubules from Gravin(-/-) mice where an overabundance of Oct3/4 positive germ line stem cells displays randomized orientation of mitotic spindles. Thus, we propose that Gravin-mediated recruitment of Aurora A and Plk1 to the mother (oldest) spindle pole contributes to the fidelity of symmetric cell division.

  13. The mitotic spindle and associated membranes in the closed mitosis of trichomonads.

    Science.gov (United States)

    Ribeiro, Karla Consort; Pereira-Neves, Antonio; Benchimol, Marlene

    2002-06-01

    In the present work, we followed the several phases of Tritrichomonas foetus and Trichomonas vaginalis cell cycles using immunofluorescence, serial thin sections, three-dimensional (3D) reconstruction, and transmission electron microscopy. In motile trichomonad cells or in pseudocyst forms, the nuclear envelope persists throughout mitosis, and the spindle is extranuclear. We found three types of spindle microtubules: pole-to-nucleus microtubules which are attached to the nuclear envelope, pole-to-pole microtubules forming a cylindrical, cytoplasmic groove on the nuclear compartment in pseudocysts of T. foetus cells, and pole-to-cytosol microtubules which extend freely into the cytoplasm. We demonstrated that: (1) in T. foetus, the spindle is assembled from an MTOC located at the base of the costa, underneath one of the basal bodies; (2) the spindle presents an unusual arc shape during the initial phases of mitosis in motile trophozoites; (3) the spindle microtubules are glutamylated, but not acetylated; (4) several membranes similar to those of the endoplasmic reticulum follow the spindle microtubules; (5) finger-like projections extend from the nucleus towards the cell poles in pseudocysts and multinucleated cells; and (6) vesicles formed in between the two nuclear membranes are seen in the course of mitosis in both trophozoite and pseudocyst forms.

  14. Regulation of NDR1 activity by PLK1 ensures proper spindle orientation in mitosis.

    Science.gov (United States)

    Yan, Maomao; Chu, Lingluo; Qin, Bo; Wang, Zhikai; Liu, Xing; Jin, Changjiang; Zhang, Guanglan; Gomez, Marta; Hergovich, Alexander; Chen, Zhengjun; He, Ping; Gao, Xinjiao; Yao, Xuebiao

    2015-01-01

    Accurate chromosome segregation during mitosis requires the physical separation of sister chromatids which depends on correct position of mitotic spindle relative to membrane cortex. Although recent work has identified the role of PLK1 in spindle orientation, the mechanisms underlying PLK1 signaling in spindle positioning and orientation have not been fully illustrated. Here, we identified a conserved signaling axis in which NDR1 kinase activity is regulated by PLK1 in mitosis. PLK1 phosphorylates NDR1 at three putative threonine residues (T7, T183 and T407) at mitotic entry, which elicits PLK1-dependent suppression of NDR1 activity and ensures correct spindle orientation in mitosis. Importantly, persistent expression of non-phosphorylatable NDR1 mutant perturbs spindle orientation. Mechanistically, PLK1-mediated phosphorylation protects the binding of Mob1 to NDR1 and subsequent NDR1 activation. These findings define a conserved signaling axis that integrates dynamic kinetochore-microtubule interaction and spindle orientation control to genomic stability maintenance.

  15. The critical role of sleep spindles in hippocampal-dependent memory: a pharmacology study.

    Science.gov (United States)

    Mednick, Sara C; McDevitt, Elizabeth A; Walsh, James K; Wamsley, Erin; Paulus, Martin; Kanady, Jennifer C; Drummond, Sean P A

    2013-03-06

    An important function of sleep is the consolidation of memories, and features of sleep, such as rapid eye movement (REM) or sleep spindles, have been shown to correlate with improvements in discrete memory domains. Because of the methodological difficulties in modulating sleep, however, a causal link between specific sleep features and human memory consolidation is lacking. Here, we experimentally manipulated specific sleep features during a daytime nap via direct pharmacological intervention. Using zolpidem (Ambien), a short-acting GABAA agonist hypnotic, we show increased sleep spindle density and decreased REM sleep compared with placebo and sodium oxybate (Xyrem). Naps with increased spindles produced significantly better verbal memory and significantly worse perceptual learning but did not affect motor learning. The experimental spindles were similar to control spindles in amplitude and frequency, suggesting that the experimental intervention enhanced normal sleep processes. Furthermore, using statistical methods, we demonstrate for the first time a critical role of spindles in human hippocampal memory performance. The gains in memory consolidation exceed sleep-alone or control conditions and demonstrate the potential for targeted, exceptional memory enhancement in healthy adults with pharmacologically modified sleep.

  16. Electro-acoustic behavior of the mitotic spindle: a semi-classical coarse-grained model.

    Directory of Open Access Journals (Sweden)

    Daniel Havelka

    Full Text Available The regulation of chromosome separation during mitosis is not fully understood yet. Microtubules forming mitotic spindles are targets of treatment strategies which are aimed at (i the triggering of the apoptosis or (ii the interruption of uncontrolled cell division. Despite these facts, only few physical models relating to the dynamics of mitotic spindles exist up to now. In this paper, we present the first electromechanical model which enables calculation of the electromagnetic field coupled to acoustic vibrations of the mitotic spindle. This electromagnetic field originates from the electrical polarity of microtubules which form the mitotic spindle. The model is based on the approximation of resonantly vibrating microtubules by a network of oscillating electric dipoles. Our computational results predict the existence of a rapidly changing electric field which is generated by either driven or endogenous vibrations of the mitotic spindle. For certain values of parameters, the intensity of the electric field and its gradient reach values which may exert a not-inconsiderable force on chromosomes which are aligned in the spindle midzone. Our model may describe possible mechanisms of the effects of ultra-short electrical and mechanical pulses on dividing cells--a strategy used in novel methods for cancer treatment.

  17. Surface shape control of the workpiece in a double-spindle triple-workstation wafer grinder

    Institute of Scientific and Technical Information of China (English)

    Zhu Xianglong; Kang Renke; Dong Zhigang; Feng Guang

    2011-01-01

    Double-spindle triple-workstation (DSTW) ultra precision grinders are mainly used in production lines for manufacturing and back thinning large diameter (≥ 300 mm) silicon wafers for integrated circuits.It is important,but insufficiently studied,to control the wafer shape ground on a DSTW grinder by adjusting the inclination angles of the spindles and work tables.In this paper,the requirements of the inclination angle adjustment of the grinding spindles and work tables in DSTW wafer grinders are analyzed.A reasonable configuration of the grinding spindles and work tables in DSTW wafer grinders are proposed.Based on the proposed configuration,an adjustment method of the inclination angle of grinding spindles and work tables for DSTW wafer grinders is put forward.The mathematical models of wafer shape with the adjustment amount of inclination angles for both fine and rough grinding spindles are derived.The proposed grinder configuration and adjustment method will provide helpful instruction for DSTW wafer grinder design.

  18. Topographical distribution of spindles: variations between and within nrem sleep cycles.

    Science.gov (United States)

    De Gennaro, L; Ferrara, M; Bertini, M

    2000-01-01

    Spindle density, visually scored in the 12-15 Hz range over antero-posterior midline derivations, was assessed during a baseline night in ten normal subjects. Sleep spindles were found to be highly variable between subjects and more abundant during Stage 2. Topographical distribution of spindle density showed a centroparietal prevalence, stable between NREM sleep stages. Intra-night variations of spindle density exhibited a linear increase across consecutive NREM episodes, suggesting an inverse relation with the time course of slow wave sleep. Except for occipital leads reaching a maximum during the third NREM cycle and then decreasing, changes in spindle density across sleep cycles were similar over different derivations. Intra-cycle variations fit a fourth-order polynomial curve with a minimum in the middle part of each sleep episode (when most slow wave sleep is expressed); this intra-cycle trend also seems stable between derivations and consecutive sleep cycles. These results confirm and extend, to the level of macroscopic EEG, the reciprocal relationship between sigma and delta waves previously shown by spectral analysis of EEG frequencies and, at a neuronal level in the thalamocortical network, by changes of membrane potentials that oscillate in the frequency range of spindles or delta at different levels of hyperpolarization.

  19. Chromator is required for proper microtubule spindle formation and mitosis in Drosophila.

    Science.gov (United States)

    Ding, Yun; Yao, Changfu; Lince-Faria, Mariana; Rath, Uttama; Cai, Weili; Maiato, Helder; Girton, Jack; Johansen, Kristen M; Johansen, Jørgen

    2009-10-01

    The chromodomain protein, Chromator, has been shown to have multiple functions that include regulation of chromatin structure as well as coordination of muscle remodeling during metamorphosis depending on the developmental context. In this study we show that mitotic neuroblasts from brain squash preparations from larvae heteroallelic for the two Chromator loss-of-function alleles Chro(71) and Chro(612) have severe microtubule spindle and chromosome segregation defects that were associated with a reduction in brain size. The microtubule spindles formed were incomplete, unfocused, and/or without clear spindle poles and at anaphase chromosomes were lagging and scattered. Time-lapse analysis of mitosis in S2 cells depleted of Chromator by RNAi treatment suggested that the lagging and scattered chromosome phenotypes were caused by incomplete alignment of chromosomes at the metaphase plate, possibly due to a defective spindle-assembly checkpoint, as well as of frayed and unstable microtubule spindles during anaphase. Expression of full-length Chromator transgenes under endogenous promoter control restored both microtubule spindle morphology as well as brain size strongly indicating that the observed mutant defects were directly attributable to lack of Chromator function.

  20. Structural basis for the enhancement of virulence by viral spindles and their in vivo crystallization.

    Science.gov (United States)

    Chiu, Elaine; Hijnen, Marcel; Bunker, Richard D; Boudes, Marion; Rajendran, Chitra; Aizel, Kaheina; Oliéric, Vincent; Schulze-Briese, Clemens; Mitsuhashi, Wataru; Young, Vivienne; Ward, Vernon K; Bergoin, Max; Metcalf, Peter; Coulibaly, Fasséli

    2015-03-31

    The great benefits that chemical pesticides have brought to agriculture are partly offset by widespread environmental damage to nontarget species and threats to human health. Microbial bioinsecticides are considered safe and highly specific alternatives but generally lack potency. Spindles produced by insect poxviruses are crystals of the fusolin protein that considerably boost not only the virulence of these viruses but also, in cofeeding experiments, the insecticidal activity of unrelated pathogens. However, the mechanisms by which spindles assemble into ultra-stable crystals and enhance virulence are unknown. Here we describe the structure of viral spindles determined by X-ray microcrystallography from in vivo crystals purified from infected insects. We found that a C-terminal molecular arm of fusolin mediates the assembly of a globular domain, which has the hallmarks of lytic polysaccharide monooxygenases of chitinovorous bacteria. Explaining their unique stability, a 3D network of disulfide bonds between fusolin dimers covalently crosslinks the entire crystalline matrix of spindles. However, upon ingestion by a new host, removal of the molecular arm abolishes this stabilizing network leading to the dissolution of spindles. The released monooxygenase domain is then free to disrupt the chitin-rich peritrophic matrix that protects insects against oral infections. The mode of action revealed here may guide the design of potent spindles as synergetic additives to bioinsecticides.

  1. Sleep Spindle Characteristics in Children with Neurodevelopmental Disorders and Their Relation to Cognition

    Directory of Open Access Journals (Sweden)

    Reut Gruber

    2016-01-01

    Full Text Available Empirical evidence indicates that sleep spindles facilitate neuroplasticity and “off-line” processing during sleep, which supports learning, memory consolidation, and intellectual performance. Children with neurodevelopmental disorders (NDDs exhibit characteristics that may increase both the risk for and vulnerability to abnormal spindle generation. Despite the high prevalence of sleep problems and cognitive deficits in children with NDD, only a few studies have examined the putative association between spindle characteristics and cognitive function. This paper reviews the literature regarding sleep spindle characteristics in children with NDD and their relation to cognition in light of what is known in typically developing children and based on the available evidence regarding children with NDD. We integrate available data, identify gaps in understanding, and recommend future research directions. Collectively, studies are limited by small sample sizes, heterogeneous populations with multiple comorbidities, and nonstandardized methods for collecting and analyzing findings. These limitations notwithstanding, the evidence suggests that future studies should examine associations between sleep spindle characteristics and cognitive function in children with and without NDD, and preliminary findings raise the intriguing question of whether enhancement or manipulation of sleep spindles could improve sleep-dependent memory and other aspects of cognitive function in this population.

  2. On the Free Vibration Modeling of Spindle Systems: A Calibrated Dynamic Stiffness Matrix

    Directory of Open Access Journals (Sweden)

    Omar Gaber

    2014-01-01

    Full Text Available The effect of bearings on the vibrational behavior of machine tool spindles is investigated. This is done through the development of a calibrated dynamic stiffness matrix (CDSM method, where the bearings flexibility is represented by massless linear spring elements with tuneable stiffness. A dedicated MATLAB code is written to develop and to assemble the element stiffness matrices for the system’s multiple components and to apply the boundary conditions. The developed method is applied to an illustrative example of spindle system. When the spindle bearings are modeled as simply supported boundary conditions, the DSM model results in a fundamental frequency much higher than the system’s nominal value. The simply supported boundary conditions are then replaced by linear spring elements, and the spring constants are adjusted such that the resulting calibrated CDSM model leads to the nominal fundamental frequency of the spindle system. The spindle frequency results are also validated against the experimental data. The proposed method can be effectively applied to predict the vibration characteristics of spindle systems supported by bearings.

  3. The sequential activation of the mitotic microtubule assembly pathways favors bipolar spindle formation

    Science.gov (United States)

    Cavazza, Tommaso; Malgaretti, Paolo; Vernos, Isabelle

    2016-01-01

    Centrosome maturation is the process by which the duplicated centrosomes recruit pericentriolar components and increase their microtubule nucleation activity before mitosis. The role of this process in cells entering mitosis has been mostly related to the separation of the duplicated centrosomes and thereby to the assembly of a bipolar spindle. However, spindles can form without centrosomes. In fact, all cells, whether they have centrosomes or not, rely on chromatin-driven microtubule assembly to form a spindle. To test whether the sequential activation of these microtubule assembly pathways, defined by centrosome maturation and nuclear envelope breakdown, plays any role in spindle assembly, we combined experiments in tissue culture cells and Xenopus laevis egg extracts with a mathematical model. We found that interfering with the sequential activation of the microtubule assembly pathways compromises bipolar spindle assembly in tissue culture cells but not in X. laevis egg extracts. Our data suggest a novel function for centrosome maturation that determines the contribution of the chromosomal microtubule assembly pathway and favors bipolar spindle formation in most animal cells in which tubulin is in limiting amounts. PMID:27489339

  4. Thoracolumbar fascia does not influence proprioceptive signaling from lumbar paraspinal muscle spindles in the cat

    Science.gov (United States)

    Cao, Dong-Yuan; Pickar, Joel G

    2009-01-01

    The thoracolumbar fascia attaches to the lumbar spinous processes and encloses the paraspinal muscles to form a muscle compartment. Because muscle spindles can respond to transverse forces applied at a muscle’s surface, we were interested in the mechanical effects this fascia may have on proprioceptive signaling from lumbar paraspinal muscles during vertebral movement. The discharge of paraspinal muscle spindles at rest and in response to muscle history were investigated in the presence and absence of the thoracolumbar fascia in anesthetized cats. Muscle-history was induced by positioning the L6 vertebra in conditioning directions that lengthened and shortened the paraspinal muscles. The vertebra was then returned to an intermediate position for testing the spindles. Neither resting discharge (P= 0.49) nor the effects of muscle history (P>0.30) was significantly different with the fascia intact vs. removed. Our data showed that the thoracolumbar fascia did not influence proprioceptive signaling from lumbar paraspinal muscles spindles during small passive vertebral movements in cats. In addition, comparison of the transverse threshold pressures needed to stimulate our sample of muscle spindles in the cat with the thoracolumbar fascia compartmental pressures measured in humans during previous studies suggests that the thoracolumbar fascia likely does not affect proprioceptive signaling from lumbar paraspinal muscle spindles in humans. PMID:19627391

  5. Simple Driving Techniques

    DEFF Research Database (Denmark)

    Rosendahl, Mads

    2002-01-01

    -like language. Our aim is to extract a simple notion of driving and show that even in this tamed form it has much of the power of more general notions of driving. Our driving technique may be used to simplify functional programs which use function composition and will often be able to remove intermediate data......Driving was introduced as a program transformation technique by Valentin Turchin in some papers around 1980. It was intended for the programming language REFAL and used in metasystem transitions based on super compilation. In this paper we present one version of driving for a more conventional lisp...

  6. High performance AC drives

    CERN Document Server

    Ahmad, Mukhtar

    2010-01-01

    This book presents a comprehensive view of high performance ac drives. It may be considered as both a text book for graduate students and as an up-to-date monograph. It may also be used by R & D professionals involved in the improvement of performance of drives in the industries. The book will also be beneficial to the researchers pursuing work on multiphase drives as well as sensorless and direct torque control of electric drives since up-to date references in these topics are provided. It will also provide few examples of modeling, analysis and control of electric drives using MATLAB/SIMULIN

  7. Age-related Changes In Sleep Spindles Characteristics During Daytime Recovery Following a 25-Hour Sleep Deprivation

    Directory of Open Access Journals (Sweden)

    Thaïna eRosinvil

    2015-06-01

    Full Text Available Objectives: The mechanisms underlying sleep spindles (~11-15Hz; >0.5s help to protect sleep. With age, it becomes increasingly difficult to maintain sleep at a challenging time (e.g. daytime, even after sleep loss. This study compared spindle characteristics during daytime recovery and nocturnal sleep in young and middle-aged adults. In addition, we explored whether spindles characteristics in baseline nocturnal sleep were associated with the ability to maintain sleep during daytime recovery periods in both age groups.Methods: Twenty-nine young (15 women and 14 men; 27.3 ± 5.0 and 31 middle-aged (19 women and 13 men; 51.6 y ± 5.1 healthy subjects participated in a baseline nocturnal sleep and a daytime recovery sleep after 25 hours of sleep deprivation. Spindles were detected on artefact-free NREM sleep epochs. Spindle density (nb/min, amplitude (μV, frequency (Hz and duration (s were analyzed on parasagittal (linked-ears derivations. Results: In young subjects, spindle frequency increased during daytime recovery sleep as compared to baseline nocturnal sleep in all derivations, whereas middle-aged subjects showed spindle frequency enhancement only in the prefrontal derivation. No other significant interaction between age group and sleep condition was observed. Spindle density for all derivations and centro-occipital spindle amplitude decreased whereas prefrontal spindle amplitude increased from baseline to daytime recovery sleep in both age groups. Finally, no significant correlation was found between spindle characteristics during baseline nocturnal sleep and the marked reduction in sleep efficiency during daytime recovery sleep in both young and middle-aged subjects.Conclusion: These results suggest that the interaction between homeostatic and circadian pressure module spindle frequency differently in aging. Spindle characteristics do not seem to be linked with the ability to maintain daytime recovery sleep.

  8. The Hexagon-Spindle Model for educational ergonomics.

    Science.gov (United States)

    Benedyk, Rachel; Woodcock, Andrée; Harder, Andrew

    2009-01-01

    Ergonomics has traditionally considered work done, in a workplace. More recently, this scope has broadened, and the concept of 'work' may now be applied to the satisfactory completion of any task. Thus, learning, being the transformation and extension of the learner's knowledge or skills, can be viewed as work, with its workplace being the educational environment in which learning tasks take place. In accomplishing the learning, the learner interacts with the teachers, other students, equipment, materials, study plans and the educational organisation; the effectiveness of these learning interactions is influenced by many factors both inside and external to the organisation. To optimize such a multi-factorial process requires the application of an ergonomic approach. This paper proposes an adaptation of the concentric rings model of ergonomics, informed by Kao's earlier model, to produce a new model for educational ergonomics, known as the Hexagon-Spindle Model. In comparison to other published models of educational ergonomics, it is holistic, multi-dimensional, task-related and transferable across a range of educational settings. It extends to characterise a time base for serial and simultaneous tasks, and space shared by multiple learners, and highlights areas where learner/system conflicts may arise. The paper illustrates analysis tools for the application of the model in evaluation and design.

  9. Unprotected Drosophila melanogaster telomeres activate the spindle assembly checkpoint.

    Science.gov (United States)

    Musarò, Mariarosaria; Ciapponi, Laura; Fasulo, Barbara; Gatti, Maurizio; Cenci, Giovanni

    2008-03-01

    In both yeast and mammals, uncapped telomeres activate the DNA damage response (DDR) and undergo end-to-end fusion. Previous work has shown that the Drosophila HOAP protein, encoded by the caravaggio (cav) gene, is required to prevent telomeric fusions. Here we show that HOAP-depleted telomeres activate both the DDR and the spindle assembly checkpoint (SAC). The cell cycle arrest elicited by the DDR was alleviated by mutations in mei-41 (encoding ATR), mus304 (ATRIP), grp (Chk1) and rad50 but not by mutations in tefu (ATM). The SAC was partially overridden by mutations in zw10 (also known as mit(1)15) and bubR1, and also by mutations in mei-41, mus304, rad50, grp and tefu. As expected from SAC activation, the SAC proteins Zw10, Zwilch, BubR1 and Cenp-meta (Cenp-E) accumulated at the kinetochores of cav mutant cells. Notably, BubR1 also accumulated at cav mutant telomeres in a mei-41-, mus304-, rad50-, grp- and tefu-dependent manner. Our results collectively suggest that recruitment of BubR1 by dysfunctional telomeres inhibits Cdc20-APC function, preventing the metaphase-to-anaphase transition.

  10. Anthrax toxin receptor 2a controls mitotic spindle positioning.

    Science.gov (United States)

    Castanon, I; Abrami, L; Holtzer, L; Heisenberg, C P; van der Goot, F G; González-Gaitán, M

    2013-01-01

    Oriented mitosis is essential during tissue morphogenesis. The Wnt/planar cell polarity (Wnt/PCP) pathway orients mitosis in a number of developmental systems, including dorsal epiblast cell divisions along the animal-vegetal (A-V) axis during zebrafish gastrulation. How Wnt signalling orients the mitotic plane is, however, unknown. Here we show that, in dorsal epiblast cells, anthrax toxin receptor 2a (Antxr2a) accumulates in a polarized cortical cap, which is aligned with the embryonic A-V axis and forecasts the division plane. Filamentous actin (F-actin) also forms an A-V polarized cap, which depends on Wnt/PCP and its effectors RhoA and Rock2. Antxr2a is recruited to the cap by interacting with actin. Antxr2a also interacts with RhoA and together they activate the diaphanous-related formin zDia2. Mechanistically, Antxr2a functions as a Wnt-dependent polarized determinant, which, through the action of RhoA and zDia2, exerts torque on the spindle to align it with the A-V axis.

  11. A spindle-like apparatus guides bacterial chromosome segregation.

    Science.gov (United States)

    Ptacin, Jerod L; Lee, Steven F; Garner, Ethan C; Toro, Esteban; Eckart, Michael; Comolli, Luis R; Moerner, W E; Shapiro, Lucy

    2010-08-01

    Until recently, a dedicated mitotic apparatus that segregates newly replicated chromosomes into daughter cells was believed to be unique to eukaryotic cells. Here we demonstrate that the bacterium Caulobacter crescentus segregates its chromosome using a partitioning (Par) apparatus that has surprising similarities to eukaryotic spindles. We show that the C. crescentus ATPase ParA forms linear polymers in vitro and assembles into a narrow linear structure in vivo. The centromere-binding protein ParB binds to and destabilizes ParA structures in vitro. We propose that this ParB-stimulated ParA depolymerization activity moves the centromere to the opposite cell pole through a burnt bridge Brownian ratchet mechanism. Finally, we identify the pole-specific TipN protein as a new component of the Par system that is required to maintain the directionality of DNA transfer towards the new cell pole. Our results elucidate a bacterial chromosome segregation mechanism that features basic operating principles similar to eukaryotic mitotic machines, including a multivalent protein complex at the centromere that stimulates the dynamic disassembly of polymers to move chromosomes into daughter compartments.

  12. The Drosophila microtubule-associated protein mars stabilizes mitotic spindles by crosslinking microtubules through its N-terminal region.

    Directory of Open Access Journals (Sweden)

    Gang Zhang

    Full Text Available Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

  13. Uncovering the Molecular Machinery of the Human Spindle-An Integration of Wet and Dry Systems Biology

    DEFF Research Database (Denmark)

    Rojas, Ana M.; Santamaria, Anna; Malik, Rainer

    2012-01-01

    The mitotic spindle is an essential molecular machine involved in cell division, whose composition has been studied extensively by detailed cellular biology, high-throughput proteomics, and RNA interference experiments. However, because of its dynamic organization and complex regulation it is dif....... Combining integrated bio-computational approaches and single gene experimental follow-ups could be key to exploring the still hidden regions of the human spindle system....... it is difficult to obtain a complete description of its molecular composition. We have implemented an integrated computational approach to characterize novel human spindle components and have analysed in detail the individual candidates predicted to be spindle proteins, as well as the network of predicted...... of interactions is still poorly characterised by experimental means and which are thought to influence the functionality of the mitotic spindle on a large scale. Our analyses suggest that we are still far from knowing the complete repertoire of functionally important components of the human spindle network...

  14. Indirect multisignal monitoring and diagnosis of drill wear

    OpenAIRE

    Jantunen, Erkki

    2006-01-01

    A machine tool utilisation rate can be improved by an advanced condition monitoring system using modern sensor and signal processing techniques. A drilling test and analysis program for indirect tool wear measurement forms the basis of this thesis. For monitoring the drill wear a number of monitoring methods such as vibration, acoustic emission, sound, spindle power and axial force were tested. The signals were analysed in the time domain using statistical methods such as root mean square (rm...

  15. Lectures on magnetohydrodynamical drives

    Science.gov (United States)

    Loigom, Villem

    The paper deals with nonconventional types of electrical machines and drives - magnetohydrodynamical (MHD) machines and drives. In cardinal it is based on the research conducted with participation of the author in Tallinn Technical University at the Institute of Electrical Drives and Power Electronics, where the use of magnetohydrodynamical motors and drives in the metallurgical and casting industries have been studied for a long time. Major research interests include the qualities and applications of the induction MHD-drives for set in the motion (pumping, turning, dosing, mixing, etc.) non-ferrous molten metals like Al, Mg, Sn, Pb, Na, K, and their alloys. The first part of the paper describes induction MHD motors and their electrohydraulical qualities. In the second part energy conversion problems are described. Also, on the basis of the analogy between electromechanical and electrohydraulical phenomenas, static and dynamic qualities of MHD drives with induction MHD machines are discussed.

  16. Four-dimensional visualization and quantitative analysis of meiotic spindle movements in live mouse oocytes.

    Science.gov (United States)

    Tian, N; Zhang, L; Liu, B; Wang, P; Li, Y; Ma, W

    2012-09-01

    This paper made a different attempt of real-time observation of the meiotic spindle movements in living mouse oocyte using a convenient method. This method was based on an experimental phenomenon discovered in our work. In living mouse oocytes, a high concentration of calcium ions (Ca(2+)) was observed throughout the region occupied by the initial meiotic spindle. After Ca(2+) labelling with Fura-2, a weakly fluorescent area (WFA) appeared on each side of the chromosomes. The activities of the WFAs changed during spindle development. By real-time tracking of WFAs, we were able to indirectly observe the meiotic spindle movements. Occasionally, it was observed that the first meiotic spindle rotated from an orientation parallel to the cortex to become perpendicular, instead of migrating from the oocyte centre to the cortex along its axis. Moreover, we analysed this uncommon rotation of the first meiotic spindle and found that the whole rotation process can be divided into two phases: the early slow-speed rotation and the subsequent rapid-speed rotation. We further characterized this rotation with respect to rotational speed and acceleration at all the stages of development. By using a two-photon laser-scanning microscope in combination with Fura-2 dye that is nondamaging to oocytes, we provide a convenient method for indirect visualization and quantitative analysis of spindle movements by real-time tracking of WFAs. This method is easy to operate and master, and economical with time and effort. © 2012 The Authors Journal of Microscopy © 2012 Royal Microscopical Society.

  17. Smurf2 as a novel mitotic regulator: From the spindle assembly checkpoint to tumorigenesis

    Directory of Open Access Journals (Sweden)

    Moore Finola E

    2009-07-01

    Full Text Available Abstract The execution of the mitotic program with high fidelity is dependent upon precise spatiotemporal regulation of posttranslational protein modifications. For example, the timely polyubiquitination of critical mitotic regulators by Anaphase Promoting Complex/Cyclosome (APC/C is essential for the metaphase to anaphase transition and mitotic exit. The spindle assembly checkpoint prevents unscheduled activity of APC/C-Cdc20 in early mitosis, allowing bipolar attachment of kinetochores to mitotic spindle and facilitating equal segregation of sister chromatids. The critical effector of the spindle checkpoint, Mitotic arrest deficient 2 (Mad2, is recruited to unattached kinetochores forming a complex with other regulatory proteins to efficiently and cooperatively inhibit APC/C-Cdc20. A weakened and/or dysfunctional spindle checkpoint has been linked to the development of genomic instability in both cell culture and animal models, and evidence suggests that aberrant regulation of the spindle checkpoint plays a critical role in human carcinogenesis. Recent studies have illuminated a network of both degradative and non-degradative ubiquitination events that regulate the metaphase to anaphase transition and mitotic exit. Within this context, our recent work showed that the HECT (Homologous to E6-AP C-terminus-family E3 ligase Smurf2 (Smad specific ubiquitin regulatory factor 2, known as a negative regulator of transforming growth factor-beta (TGF-β signaling, is required for a functional spindle checkpoint by promoting the functional localization and stability of Mad2. Here we discuss putative models explaining the role of Smurf2 as a new regulator in the spindle checkpoint. The dynamic mitotic localization of Smurf2 to the centrosome and other critical mitotic structures provides implications about mitotic checkpoint control dependent on various ubiquitination events. Finally, deregulated Smurf2 activity may contribute to carcinogenesis by

  18. Evaluating and Improving Automatic Sleep Spindle Detection by Using Multi-Objective Evolutionary Algorithms

    Directory of Open Access Journals (Sweden)

    Min-Yin Liu

    2017-05-01

    Full Text Available Sleep spindles are brief bursts of brain activity in the sigma frequency range (11–16 Hz measured by electroencephalography (EEG mostly during non-rapid eye movement (NREM stage 2 sleep. These oscillations are of great biological and clinical interests because they potentially play an important role in identifying and characterizing the processes of various neurological disorders. Conventionally, sleep spindles are identified by expert sleep clinicians via visual inspection of EEG signals. The process is laborious and the results are inconsistent among different experts. To resolve the problem, numerous computerized methods have been developed to automate the process of sleep spindle identification. Still, the performance of these automated sleep spindle detection methods varies inconsistently from study to study. There are two reasons: (1 the lack of common benchmark databases, and (2 the lack of commonly accepted evaluation metrics. In this study, we focus on tackling the second problem by proposing to evaluate the performance of a spindle detector in a multi-objective optimization context and hypothesize that using the resultant Pareto fronts for deriving evaluation metrics will improve automatic sleep spindle detection. We use a popular multi-objective evolutionary algorithm (MOEA, the Strength Pareto Evolutionary Algorithm (SPEA2, to optimize six existing frequency-based sleep spindle detection algorithms. They include three Fourier, one continuous wavelet transform (CWT, and two Hilbert-Huang transform (HHT based algorithms. We also explore three hybrid approaches. Trained and tested on open-access DREAMS and MASS databases, two new hybrid methods of combining Fourier with HHT algorithms show significant performance improvement with F1-scores of 0.726–0.737.

  19. Modulation of jaw muscle spindle afferent activity following intramuscular injections with hypertonic saline.

    Science.gov (United States)

    Ro, J Y; Capra, N F

    2001-05-01

    Transient noxious chemical stimulation of small diameter muscle afferents modulates jaw movement-related responses of caudal brainstem neurons. While it is likely that the effect is mediated from the spindle afferents in the mesencephalic nucleus (Vmes) via the caudally projecting Probst's tract, the mechanisms of pain induced modulations of jaw muscle spindle afferents is not known. In the present study, we tested the hypothesis that jaw muscle nociceptors gain access to muscle spindle afferents in the same muscle via central mechanisms and alter their sensitivity. Thirty-five neurons recorded from the Vmes were characterized as muscle spindle afferents based on their responses to passive jaw movements, muscle palpation, and electrical stimulation of the masseter nerve. Each cell was tested by injecting a small volume (250 microl) of either 5% hypertonic and/or isotonic saline into the receptor-bearing muscle. Twenty-nine units were tested with 5% hypertonic saline, of which 79% (23/29) showed significant modulation of mean firing rates (MFRs) during one or more phases of ramp-and-hold movements. Among the muscle spindle primary-like units (n = 12), MFRs of 4 units were facilitated, five reduced, two showed mixed responses and one unchanged. In secondary-like units (n = 17), MFRs of 9 were facilitated, three reduced and five unchanged. Thirteen units were tested with isotonic saline, of which 77% showed no significant changes of MFRs. Further analysis revealed that the hypertonic saline not only affected the overall output of muscle spindle afferents, but also increased the variability of firing and altered the relationship between afferent signal and muscle length. These results demonstrated that activation of muscle nociceptors significantly affects proprioceptive properties of jaw muscle spindles via central neural mechanisms. The changes can have deleterious effects on oral motor function as well as kinesthetic sensibility.

  20. Can loss of muscle spindle afferents explain the ataxic gait in Riley-Day syndrome?

    Science.gov (United States)

    Macefield, Vaughan G; Norcliffe-Kaufmann, Lucy; Gutiérrez, Joel; Axelrod, Felicia B; Kaufmann, Horacio

    2011-11-01

    The Riley-Day syndrome is the most common of the hereditary sensory and autonomic neuropathies (Type III). Among the well-recognized clinical features are reduced pain and temperature sensation, absent deep tendon reflexes and a progressively ataxic gait. To explain the latter we tested the hypothesis that muscle spindles, or their afferents, are absent in hereditary sensory and autonomic neuropathy III by attempting to record from muscle spindle afferents from a nerve supplying the leg in 10 patients. For comparison we also recorded muscle spindles from 15 healthy subjects and from two patients with hereditary sensory and autonomic neuropathy IV, who have profound sensory disturbances but no ataxia. Tungsten microelectrodes were inserted percutaneously into fascicles of the common peroneal nerve at the fibular head. Intraneural stimulation within muscle fascicles evoked twitches at normal stimulus currents (10-30 µA), and deep pain (which often referred) at high intensities (1 mA). Microneurographic recordings from muscle fascicles revealed a complete absence of spontaneously active muscle spindles in patients with hereditary sensory and autonomic neuropathy III; moreover, responses to passive muscle stretch could not be observed. Conversely, muscle spindles appeared normal in patients with hereditary sensory and autonomic neuropathy IV, with mean firing rates of spontaneously active endings being similar to those recorded from healthy controls. Intraneural stimulation within cutaneous fascicles evoked paraesthesiae in the fascicular innervation territory at normal stimulus intensities, but cutaneous pain was never reported during high-intensity stimulation in any of the patients. Microneurographic recordings from cutaneous fascicles revealed the presence of normal large-diameter cutaneous mechanoreceptors in hereditary sensory and autonomic neuropathy III. Our results suggest that the complete absence of functional muscle spindles in these patients explains

  1. Prolonged hyperpolarizing potentials precede spindle oscillations in the thalamic reticular nucleus

    Science.gov (United States)

    Fuentealba, Pablo; Timofeev, Igor; Steriade, Mircea

    2004-01-01

    The thalamic reticular (RE) nucleus is a key structure in the generation of spindles, a hallmark bioelectrical oscillation during early stages of sleep. Intracellular recordings of RE neurons in vivo revealed the presence of prolonged hyperpolarizing potentials preceding spindles in a subgroup (30%) of neurons. These hyperpolarizations (6-10 mV) lasted for 200-300 ms and were present just before the onset of spontaneously occurring spindle waves. Corticothalamic volleys also were effective in generating such hyperpolarizations followed by spindles in RE neurons. A drop of up to 40% in the apparent input resistance (Rin) was associated with these hyperpolarizing potentials, suggesting an active process rather than disfacilitation. Accordingly, the reversal potential was approximately -100 mV for both spontaneous and cortically elicited hyperpolarizations, consistent with the activation of slow K+ conductances. QX-314 in the recording pipettes decreased both the amplitude and incidence of prolonged hyperpolarizations, suggesting the participation of G protein-dependent K+ currents in the generation of hyperpolarizations. Simultaneous extracellular and intracellular recordings in the RE nucleus demonstrated that some RE neurons discharged during the hyperpolarizations and, thus, may be implicated in their generation. The prolonged hyperpolarizations preceding spindles may play a role in the transition from tonic to bursting firing of RE neurons within a range of membrane potential (-60 to -65 mV) at which they set favorable conditions for the generation of low-threshold spike bursts that initiate spindle sequences. These data are further arguments for the generation of spindles within the thalamic RE nucleus. PMID:15210981

  2. NAD(PH:quinone oxidoreductase 1 (NQO1 localizes to the mitotic spindle in human cells.

    Directory of Open Access Journals (Sweden)

    David Siegel

    Full Text Available NAD(PH:quinone oxidoreductase 1 (NQO1 is an FAD containing quinone reductase that catalyzes the 2-electron reduction of a broad range of quinones. The 2-electron reduction of quinones to hydroquinones by NQO1 is believed to be a detoxification process since this reaction bypasses the formation of the highly reactive semiquinone. NQO1 is expressed at high levels in normal epithelium, endothelium and adipocytes as well as in many human solid tumors. In addition to its function as a quinone reductase NQO1 has been shown to reduce superoxide and regulate the 20 S proteasomal degradation of proteins including p53. Biochemical studies have indicated that NQO1 is primarily located in the cytosol, however, lower levels of NQO1 have also been found in the nucleus. In these studies we demonstrate using immunocytochemistry and confocal imaging that NQO1 was found associated with mitotic spindles in cells undergoing division. The association of NQO1 with the mitotic spindles was observed in many different human cell lines including nontransformed cells (astrocytes, HUVEC immortalized cell lines (HBMEC, 16HBE and cancer (pancreatic adenocarcinoma, BXPC3. Confocal analysis of double-labeling experiments demonstrated co-localization of NQO1with alpha-tubulin in mitotic spindles. In studies with BxPc-3 human pancreatic cancer cells the association of NQO1 with mitotic spindles appeared to be unchanged in the presence of NQO1 inhibitors ES936 or dicoumarol suggesting that NQO1 can associate with the mitotic spindle and still retain catalytic activity. Analysis of archival human squamous lung carcinoma tissue immunostained for NQO1 demonstrated positive staining for NQO1 in the spindles of mitotic cells. The purpose of this study is to demonstrate for the first time the association of the quinone reductase NQO1 with the mitotic spindle in human cells.

  3. Accuracy analysis and design of A3 parallel spindle head

    Science.gov (United States)

    Ni, Yanbing; Zhang, Biao; Sun, Yupeng; Zhang, Yuan

    2016-03-01

    As functional components of machine tools, parallel mechanisms are widely used in high efficiency machining of aviation components, and accuracy is one of the critical technical indexes. Lots of researchers have focused on the accuracy problem of parallel mechanisms, but in terms of controlling the errors and improving the accuracy in the stage of design and manufacturing, further efforts are required. Aiming at the accuracy design of a 3-DOF parallel spindle head(A3 head), its error model, sensitivity analysis and tolerance allocation are investigated. Based on the inverse kinematic analysis, the error model of A3 head is established by using the first-order perturbation theory and vector chain method. According to the mapping property of motion and constraint Jacobian matrix, the compensatable and uncompensatable error sources which affect the accuracy in the end-effector are separated. Furthermore, sensitivity analysis is performed on the uncompensatable error sources. The sensitivity probabilistic model is established and the global sensitivity index is proposed to analyze the influence of the uncompensatable error sources on the accuracy in the end-effector of the mechanism. The results show that orientation error sources have bigger effect on the accuracy in the end-effector. Based upon the sensitivity analysis results, the tolerance design is converted into the issue of nonlinearly constrained optimization with the manufacturing cost minimum being the optimization objective. By utilizing the genetic algorithm, the allocation of the tolerances on each component is finally determined. According to the tolerance allocation results, the tolerance ranges of ten kinds of geometric error sources are obtained. These research achievements can provide fundamental guidelines for component manufacturing and assembly of this kind of parallel mechanisms.

  4. Accuracy Analysis and Design of A3 Parallel Spindle Head

    Institute of Scientific and Technical Information of China (English)

    NI Yanbing; ZHANG Biao; SUN Yupeng; ZHANG Yuan

    2016-01-01

    As functional components of machine tools, parallel mechanisms are widely used in high efficiency machining of aviation components, and accuracy is one of the critical technical indexes. Lots of researchers have focused on the accuracy problem of parallel mechanisms, but in terms of controlling the errors and improving the accuracy in the stage of design and manufacturing, further efforts are required. Aiming at the accuracy design of a 3-DOF parallel spindle head(A3 head), its error model, sensitivity analysis and tolerance allocation are investigated. Based on the inverse kinematic analysis, the error model of A3 head is established by using the first-order perturbation theory and vector chain method. According to the mapping property of motion and constraint Jacobian matrix, the compensatable and uncompensatable error sources which affect the accuracy in the end-effector are separated. Furthermore, sensitivity analysis is performed on the uncompensatable error sources. The sensitivity probabilistic model is established and the global sensitivity index is proposed to analyze the influence of the uncompensatable error sources on the accuracy in the end-effector of the mechanism. The results show that orientation error sources have bigger effect on the accuracy in the end-effector. Based upon the sensitivity analysis results, the tolerance design is converted into the issue of nonlinearly constrained optimization with the manufacturing cost minimum being the optimization objective. By utilizing the genetic algorithm, the allocation of the tolerances on each component is finally determined. According to the tolerance allocation results, the tolerance ranges of ten kinds of geometric error sources are obtained. These research achievements can provide fundamental guidelines for component manufacturing and assembly of this kind of parallel mechanisms.

  5. The GTPase Gem and its partner Kif9 are required for chromosome alignment, spindle length control, and mitotic progression.

    Science.gov (United States)

    Andrieu, Guillaume; Quaranta, Muriel; Leprince, Corinne; Hatzoglou, Anastassia

    2012-12-01

    Within the Ras superfamily, Gem is a small GTP-binding protein that plays a role in regulating Ca(2+) channels and cytoskeletal remodeling in interphase cells. Here, we report for the first time that Gem is a spindle-associated protein and is required for proper mitotic progression. Functionally, loss of Gem leads to misaligned chromosomes and prometaphase delay. On the basis of different experimental approaches, we demonstrate that loss of Gem by RNA interference induces spindle elongation, while its enforced expression results in spindle shortening. The spindle length phenotype is generated through deregulation of spindle dynamics on Gem depletion and requires the expression of its downstream effector, the kinesin Kif9. Loss of Kif9 induces spindle abnormalities similar to those observed when Gem expression is repressed by siRNA. We further identify Kif9 as a new regulator of spindle dynamics. Kif9 depletion increases the steady-state levels of spindle α-tubulin by increasing the rate of microtubule polymerization. Overall, this study demonstrates a novel mechanism by which Gem contributes to the mitotic progression by maintaining correct spindle length through the kinesin Kif9.

  6. Universal Drive Train Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This vehicle drive train research facility is capable of evaluating helicopter and ground vehicle power transmission technologies in a system level environment. The...

  7. Aurora B suppresses microtubule dynamics and limits central spindle size by locally activating KIF4A

    Science.gov (United States)

    Nunes Bastos, Ricardo; Gandhi, Sapan R.; Baron, Ryan D.; Gruneberg, Ulrike; Nigg, Erich A.

    2013-01-01

    Anaphase central spindle formation is controlled by the microtubule-stabilizing factor PRC1 and the kinesin KIF4A. We show that an MKlp2-dependent pool of Aurora B at the central spindle, rather than global Aurora B activity, regulates KIF4A accumulation at the central spindle. KIF4A phosphorylation by Aurora B stimulates the maximal microtubule-dependent ATPase activity of KIF4A and promotes its interaction with PRC1. In the presence of phosphorylated KIF4A, microtubules grew more slowly and showed long pauses in growth, resulting in the generation of shorter PRC1-stabilized microtubule overlaps in vitro. Cells expressing only mutant forms of KIF4A lacking the Aurora B phosphorylation site overextended the anaphase central spindle, demonstrating that this regulation is crucial for microtubule length control in vivo. Aurora B therefore ensures that suppression of microtubule dynamic instability by KIF4A is restricted to a specific subset of microtubules and thereby contributes to central spindle size control in anaphase. PMID:23940115

  8. MISP is a novel Plk1 substrate required for proper spindle orientation and mitotic progression

    Science.gov (United States)

    Zhu, Mei; Settele, Florian; Kotak, Sachin; Sanchez-Pulido, Luis; Ehret, Lena; Ponting, Chris P.; Gönczy, Pierre

    2013-01-01

    Precise positioning of the mitotic spindle determines the correct cell division axis and is crucial for organism development. Spindle positioning is mediated through a cortical machinery by capturing astral microtubules, thereby generating pushing/pulling forces at the cell cortex. However, the molecular link between these two structures remains elusive. Here we describe a previously uncharacterized protein, MISP (C19orf21), as a substrate of Plk1 that is required for correct mitotic spindle positioning. MISP is an actin-associated protein throughout the cell cycle. MISP depletion led to an impaired metaphase-to-anaphase transition, which depended on phosphorylation by Plk1. Loss of MISP induced mitotic defects including spindle misorientation accompanied by shortened astral microtubules. Furthermore, we find that MISP formed a complex with and regulated the cortical distribution of the +TIP binding protein p150glued, a subunit of the dynein–dynactin complex. We propose that Plk1 phosphorylates MISP, thus stabilizing cortical and astral microtubule attachments required for proper mitotic spindle positioning. PMID:23509069

  9. TPX2 phosphorylation maintains metaphase spindle length by regulating microtubule flux

    Science.gov (United States)

    Fu, Jingyan; Bian, Minglei; Xin, Guangwei; Deng, Zhaoxuan; Luo, Jia; Guo, Xiao; Chen, Hao; Wang, Yao; Jiang, Qing

    2015-01-01

    A steady-state metaphase spindle maintains constant length, although the microtubules undergo intensive dynamics. Tubulin dimers are incorporated at plus ends of spindle microtubules while they are removed from the minus ends, resulting in poleward movement. Such microtubule flux is regulated by the microtubule rescue factors CLASPs at kinetochores and depolymerizing protein Kif2a at the poles, along with other regulators of microtubule dynamics. How microtubule polymerization and depolymerization are coordinated remains unclear. Here we show that TPX2, a microtubule-bundling protein and activator of Aurora A, plays an important role. TPX2 was phosphorylated by Aurora A during mitosis. Its phospho-null mutant caused short metaphase spindles coupled with low microtubule flux rate. Interestingly, phosphorylation of TPX2 regulated its interaction with CLASP1 but not Kif2a. The effect of its mutant in shortening the spindle could be rescued by codepletion of CLASP1 and Kif2a that abolished microtubule flux. Together we propose that Aurora A–dependent TPX2 phosphorylation controls mitotic spindle length through regulating microtubule flux. PMID:26240182

  10. Review of the touch preparation cytology of spindle epithelial tumor with thymus-like differentiation

    Science.gov (United States)

    Yi, Kijong; Rehman, Abdul; Jang, Se Min; Paik, Seung Sam

    2016-01-01

    We experienced a case of spindle epithelial tumor with thymus-like differentiation (SETTLE) with touch preparation cytology performed during the intraoperative frozen section diagnosis in a 22-year-old woman. The tumor was partially encapsulated by fibrous capsule. It was a highly cellular biphasic tumor characterized by fasciculated spindle cells with streaming pattern and tubulopapillary epithelial component. The tumor cells were positive for cytokeratin, vimentin, c-kit, epithelial membrane antigen (EMA), and thyroid transcription factor-1 (TTF-1). However, the tumor cells were negative for thyroglobulin, calcitonin, CD99, S-100 protein, CD34, smooth muscle actin, HBME-1, and galectin-3. The reviewed touch smears showed tight clusters with high cellularity. Most cellular clusters showed papillary configuration. However, some clusters showed spindle cells with streaming pattern. The spindle tumor cells showed elongated and cigar-shaped nuclei. Although the incidence is very rare, SETLLE should be included in the differential diagnosis when a spindle cell neoplasm is encountered in touch preparation cytology in young patients with a thyroid mass. PMID:27011438

  11. Changes in muscle spindle firing in response to length changes of neighboring muscles.

    Science.gov (United States)

    Smilde, Hiltsje A; Vincent, Jake A; Baan, Guus C; Nardelli, Paul; Lodder, Johannes C; Mansvelder, Huibert D; Cope, Tim C; Maas, Huub

    2016-06-01

    Skeletal muscle force can be transmitted to the skeleton, not only via its tendons of origin and insertion but also through connective tissues linking the muscle belly to surrounding structures. Through such epimuscular myofascial connections, length changes of a muscle may cause length changes within an adjacent muscle and hence, affect muscle spindles. The aim of the present study was to investigate the effects of epimuscular myofascial forces on feedback from muscle spindles in triceps surae muscles of the rat. We hypothesized that within an intact muscle compartment, muscle spindles not only signal length changes of the muscle in which they are located but can also sense length changes that occur as a result of changing the length of synergistic muscles. Action potentials from single afferents were measured intra-axonally in response to ramp-hold release (RHR) stretches of an agonistic muscle at different lengths of its synergist, as well as in response to synergist RHRs. A decrease in force threshold was found for both soleus (SO) and lateral gastrocnemius afferents, along with an increase in length threshold for SO afferents. In addition, muscle spindle firing could be evoked by RHRs of the synergistic muscle. We conclude that muscle spindles not only signal length changes of the muscle in which they are located but also local length changes that occur as a result of changing the length and relative position of synergistic muscles.

  12. Measurement Research of Motorized Spindle Dynamic Stiffness under High Speed Rotating

    Directory of Open Access Journals (Sweden)

    Xiaopeng Wang

    2015-01-01

    Full Text Available High speed motorized spindle has become a key functional unit of high speed machine tools and effectively promotes the development of machine tool technology. The development of higher speed and more power puts forward the stricter requirement for the performance of motorized spindle, especially the dynamic performance which affects the machining accuracy, reliability, and production efficiency. To overcome the problems of ineffective loading and dynamic performance measurement of motorized spindle, a noncontact electromagnetic loading device is developed. The cutting load can be simulated by using electromagnetic force. A new method of measuring force by force sensors is presented, and the steady and transient loading force could be measured exactly. After the high speed machine spindle is tested, the frequency response curves of the spindle relative to machine table are collected at 0~12000 rpm; then the relationships between stiffness and speeds as well as between damping ratio and speeds are obtained. The result shows that not only the static and dynamic stiffness but also the damping ratio declined with the increase of speed.

  13. Regulation of spindle orientation and neural stem cell fate in the Drosophila optic lobe

    Directory of Open Access Journals (Sweden)

    Brand Andrea H

    2007-01-01

    Full Text Available Abstract Background The choice of a stem cell to divide symmetrically or asymmetrically has profound consequences for development and disease. Unregulated symmetric division promotes tumor formation, whereas inappropriate asymmetric division affects organ morphogenesis. Despite its importance, little is known about how spindle positioning is regulated. In some tissues cell fate appears to dictate the type of cell division, whereas in other tissues it is thought that stochastic variation in spindle position dictates subsequent sibling cell fate. Results Here we investigate the relationship between neural progenitor identity and spindle positioning in the Drosophila optic lobe. We use molecular markers and live imaging to show that there are two populations of progenitors in the optic lobe: symmetrically dividing neuroepithelial cells and asymmetrically dividing neuroblasts. We use genetically marked single cell clones to show that neuroepithelial cells give rise to neuroblasts. To determine if a change in spindle orientation can trigger a neuroepithelial to neuroblast transition, we force neuroepithelial cells to divide along their apical/basal axis by misexpressing Inscuteable. We find that this does not induce neuroblasts, nor does it promote premature neuronal differentiation. Conclusion We show that symmetrically dividing neuroepithelial cells give rise to asymmetrically dividing neuroblasts in the optic lobe, and that regulation of spindle orientation and division symmetry is a consequence of cell type specification, rather than a mechanism for generating cell type diversity.

  14. Spindle error motion measurement using concentric circle grating and phase modulation interferometers

    Science.gov (United States)

    Aketagawa, M.; Madden, M.; Uesugi, S.; Kumagai, T.; Maeda, Y.; Okuyama, E.

    2012-11-01

    In the conventional methods to measure radial, axial and angular motions of spindles, complicated artifacts with relative large volume (such as two balls linked with a cylinder) are required. Small volume artifact is favorable from the viewpoint of the accurate and practical measurement of the spindle motion. This paper describes a concurrent measurement of spindle radial, axial and angular motions using concentric circle grating and phase modulation interferometers. In the measurement, the concentric circle grating with fine pitch is installed on top of the spindle of interest. The grating is a reference artifact in the method. Three optical sensors are fixed over the concentric circle grating, and observe the proper positions of the grating. The optical sensor consists of a frequency modulated laser diode as a light source, and two interferometers. One interferometer observes an interference fringe between reflected light form a fixed mirror and 0-th order diffraction light from the grating to measure the axial motion. Another interferometer observes an interference fringe between +/-2nd diffraction lights from the grating to measure the radial motion. Using three optical sensors, three radial displacements and three axial displacements of the proper observed position of the grating can be measured. From these measured displacements, radial, axial and angular motions of the spindle can be calculated concurrently. In the paper, a measurement instrument, a novel fringe interpolation technique by sinusoidal phase modulation and experimental results are discussed.

  15. Development of a simple test device for spindle error measurement using a position sensitive detector

    Science.gov (United States)

    Liu, Chien-Hung; Jywe, Wen-Yuh; Lee, Hau-Wei

    2004-09-01

    A new spindle error measurement system has been developed in this paper. It employs a design development rotational fixture with a built-in laser diode and four batteries to replace a precision reference master ball or cylinder used in the traditional method. Two measuring devices with two position sensitive detectors (one is designed for the measurement of the compound X-axis and Y-axis errors and the other is designed with a lens for the measurement of the tilt angular errors) are fixed on the machine table to detect the laser point position from the laser diode in the rotational fixture. When the spindle rotates, the spindle error changes the direction of the laser beam. The laser beam is then divided into two separated beams by a beam splitter. The two separated beams are projected onto the two measuring devices and are detected by two position sensitive detectors, respectively. Thus, the compound motion errors and the tilt angular errors of the spindle can be obtained. Theoretical analysis and experimental tests are presented in this paper to separate the compound errors into two radial errors and tilt angular errors. This system is proposed as a new instrument and method for spindle metrology.

  16. Separating the spindle, checkpoint, and timer functions of BubR1.

    Science.gov (United States)

    Rahmani, Zohra; Gagou, Mary E; Lefebvre, Christophe; Emre, Doruk; Karess, Roger E

    2009-11-30

    BubR1 performs several roles during mitosis, affecting the spindle assembly checkpoint (SAC), mitotic timing, and spindle function, but the interdependence of these functions is unclear. We have analyzed in Drosophila melanogaster the mitotic phenotypes of kinase-dead (KD) BubR1 and BubR1 lacking the N-terminal KEN box. bubR1-KD individuals have a robust SAC but abnormal spindles with thin kinetochore fibers, suggesting that the kinase activity modulates microtubule capture and/or dynamics but is relatively dispensable for SAC function. In contrast, bubR1-KEN flies have normal spindles but no SAC. Nevertheless, mitotic timing is normal as long as Mad2 is present. Thus, the SAC, timer, and spindle functions of BubR1 are substantially separable. Timing is shorter in bubR1-KEN mad2 double mutants, yet in these flies, lacking both critical SAC components, chromosomes still segregate accurately, reconfirming that in Drosophila, reliable mitosis does not need the SAC.

  17. Manual Characterization of Sleep Spindle Index in Patients with Narcolepsy and Idiopathic Hypersomnia

    Directory of Open Access Journals (Sweden)

    Lourdes M. DelRosso

    2014-01-01

    Full Text Available This is a retrospective review of PSG data from 8 narcolepsy patients and 8 idiopathic hypersomnia (IH patients, evaluating electrophysiologic differences between these two central hypersomnias. Spindles were identified according to the AASM Manual for the Scoring of Sleep and Associated Events; and counted per epoch in the first 50 epochs of N2 sleep and the last 50 epochs of N2 sleep in each patient’s PSG. Spindle count data (mean ± standard deviation per 30 second-epoch (spindle index in the 8 narcolepsy patients was as follows: 0.37 ± 0.73 for the first 50 epochs of N2; 0.65 ± 1.09 for the last 50 epochs of N2; and 0.51 ± 0.93 for all 100 epochs of N2. Spindle index data in the 8 IH patients was as follows: 2.31 ± 2.23 for the first 50 epochs of N2; 2.84 ± 2.43 for the last 50 epochs of N2; and 2.57 ± 2.35 for all 100 epochs of N2. Intergroup differences in spindle count in the first 50 N2 epochs, the last 50 N2 epochs, and all 100 epochs of scored N2 were significant (P<0.01 as were the intragroup differences between the first 50 N2 epochs and the last 50 N2 epochs.

  18. Absence of a conventional spindle mitotic checkpoint in the binucleated single-celled parasite Giardia intestinalis.

    Science.gov (United States)

    Markova, Kristyna; Uzlikova, Magdalena; Tumova, Pavla; Jirakova, Klara; Hagen, Guy; Kulda, Jaroslav; Nohynkova, Eva

    2016-10-01

    The spindle assembly checkpoint (SAC) joins the machinery of chromosome-to-spindle microtubule attachment with that of the cell cycle to prevent missegregation of chromosomes during mitosis. Although a functioning SAC has been verified in a limited number of organisms, it is regarded as an evolutionarily conserved safeguard mechanism. In this report, we focus on the existence of the SAC in a single-celled parasitic eukaryote, Giardia intestinalis. Giardia belongs to Excavata, a large and diverse supergroup of unicellular eukaryotes in which SAC control has been nearly unexplored. We show that Giardia cells with absent or defective mitotic spindles due to the inhibitory effects of microtubule poisons do not arrest in mitosis; instead, they divide without any delay, enter the subsequent cell cycle and even reduplicate DNA before dying. We identified a limited repertoire of kinetochore and SAC components in the Giardia genome, indicating that this parasite is ill equipped to halt mitosis before the onset of anaphase via SAC control of chromosome-spindle microtubule attachment. Finally, based on overexpression, we show that Giardia Mad2, a core SAC protein in other eukaryotes, localizes along intracytoplasmic portions of caudal flagellar axonemes, but never within nuclei, even in mitotic cells with blocked spindles, where the SAC should be active. These findings are consistent with the absence of a conventional SAC, known from yeast and metazoans, in the parasitic protist Giardia.

  19. MLL5 maintains spindle bipolarity by preventing aberrant cytosolic aggregation of PLK1.

    Science.gov (United States)

    Zhao, Wei; Liu, Jie; Zhang, Xiaoming; Deng, Lih-Wen

    2016-03-28

    Faithful chromosome segregation with bipolar spindle formation is critical for the maintenance of genomic stability. Perturbation of this process often leads to severe mitotic failure, contributing to tumorigenesis. MLL5 has been demonstrated to play vital roles in cell cycle progression and the maintenance of genomic stability. Here, we identify a novel interaction between MLL5 and PLK1 in the cytosol that is crucial for sustaining spindle bipolarity during mitosis. Knockdown of MLL5 caused aberrant PLK1 aggregation that led to acentrosomal microtubule-organizing center (aMTOC) formation and subsequent spindle multipolarity. Further molecular studies revealed that the polo-box domain (PBD) of PLK1 interacted with a binding motif on MLL5 (Thr887-Ser888-Thr889), and this interaction was essential for spindle bipolarity. Overexpression of wild-type MLL5 was able to rescue PLK1 mislocalization and aMTOC formation in MLL5-KD cells, whereas MLL5 mutants incapable of interacting with the PBD failed to do so. We thus propose that MLL5 preserves spindle bipolarity through maintaining cytosolic PLK1 in a nonaggregated form.

  20. Design of an Ultimate High Speed Electrical Drive System

    Directory of Open Access Journals (Sweden)

    C. Vishnu Kiran

    2014-05-01

    Full Text Available New emerging applications in the areas of portable power generation, small turbocompressors and spindles require the development of ultrahigh-speed, low power electrical drives. A 500 000 r/min, 100 W electrical drive system is presented. Because of the ultrahigh-speed requirements, standard machine design and power electronic topology choices no longer apply and the complete drive system has to be considered. A permanent magnet machine with a slotless litz-wire winding is used, which results in a low motor inductance and a high fundamental machine frequency. Three different combinations of power electronic topologies and commutation strategies have been experimentally investigated. A voltage source inverter with block commutation and an additional dc–dc converter is selected as the most optimal choice for the power electronics interface as it results in the lowest volume of the entire drive system due to lower switching losses, no heat sink cooling required, a small number of semiconductor devices, and relatively simple control implementation in a low cost digitalsignal processor.

  1. Piezoelectric drive circuit

    Science.gov (United States)

    Treu, Jr., Charles A.

    1999-08-31

    A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes.

  2. Fundamentals of electrical drives

    CERN Document Server

    Veltman, André; De Doncker, Rik W

    2007-01-01

    Provides a comprehensive introduction to various aspects of electrical drive systems. This volume provides a presentation of dynamic generic models that cover all major electrical machine types and modulation/control components of a drive as well as dynamic and steady state analysis of transformers and electrical machines.

  3. Electric vehicles: Driving range

    Science.gov (United States)

    Kempton, Willett

    2016-09-01

    For uptake of electric vehicles to increase, consumers' driving-range needs must be fulfilled. Analysis of the driving patterns of personal vehicles in the US now shows that today's electric vehicles can meet all travel needs on almost 90% of days from a single overnight charge.

  4. Recognizing driving in haste

    NARCIS (Netherlands)

    Rendón-Vélez, E.

    2014-01-01

    One can often hear people discussing the reasons why a road accident has happened: “She had to pick up her kids in the school before four o’clock and she was driving in haste and careless”, “He was stressed, he wanted to reach the beginning of the football match, tried to drive faster and didn't app

  5. Drive Around the World

    Institute of Scientific and Technical Information of China (English)

    Yang Wei

    2008-01-01

    @@ "It's so cool that I can drive on my own,and my own car,"Cao Gang,WOrking for a private company in Changsha,capital city of Hunan Province,mid-south China,said in excitement when he newly bought Ben Ben,a Chinese local auto brand of Chang'an,with his freshly-passed driving license.

  6. Recognizing driving in haste

    NARCIS (Netherlands)

    Rendón-Vélez, E.

    2014-01-01

    One can often hear people discussing the reasons why a road accident has happened: “She had to pick up her kids in the school before four o’clock and she was driving in haste and careless”, “He was stressed, he wanted to reach the beginning of the football match, tried to drive faster and didn't app

  7. Electric Vehicle - Economical driving

    DEFF Research Database (Denmark)

    Jensen, VCE, Steen V.; Schøn, Henriette

    1999-01-01

    How do you reduce the energy-wast when driving and loading EV's - or rather: How do I get more km/l out of an EV......How do you reduce the energy-wast when driving and loading EV's - or rather: How do I get more km/l out of an EV...

  8. Recognizing driving in haste

    NARCIS (Netherlands)

    Rendón-Vélez, E.

    2014-01-01

    One can often hear people discussing the reasons why a road accident has happened: “She had to pick up her kids in the school before four o’clock and she was driving in haste and careless”, “He was stressed, he wanted to reach the beginning of the football match, tried to drive faster and didn't

  9. Localization and function of Kinesin-5-like proteins during assembly and maintenance of mitotic spindles in Silvetia compressa

    Directory of Open Access Journals (Sweden)

    Miller Anne

    2009-06-01

    Full Text Available Abstract Background Kinesin-5 (Eg-5 motor proteins are essential for maintenance of spindle bipolarity in animals. The roles of Kinesin-5 proteins in other systems, such as Arabidopsis, Dictyostelium, and sea urchin are more varied. We are studying Kinesin-5-like proteins during early development in the brown alga Silvetia compressa. Previously, this motor was shown to be needed to assemble a bipolar spindle, similar to animals. This report builds on those findings by investigating the localization of the motor and probing its function in spindle maintenance. Findings Anti-Eg5 antibodies were used to investigate localization of Kinesin-5-like proteins in brown algal zygotes. In interphase zygotes, localization was predominantly within the nucleus. As zygotes entered mitosis, these motor proteins strongly associated with spindle poles and, to a lesser degree, with the polar microtubule arrays and the spindle midzone. In order to address whether Kinesin-5-like proteins are required to maintain spindle bipolarity, we applied monastrol to synchronized zygotes containing bipolar spindles. Monastrol is a cell-permeable chemical inhibitor of the Kinesin-5 class of molecular motors. We found that inhibition of motor function in pre-formed spindles induced the formation of multipolar spindles and short bipolar spindles. Conclusion Based upon these localization and inhibitor studies, we conclude that Kinesin-5-like motors in brown algae are more similar to the motors of animals than those of plants or protists. However, Kinesin-5-like proteins in S. compressa serve novel roles in spindle formation and maintenance not observed in animals.

  10. Localized Aurora B activity spatially controls non-kinetochore microtubules during spindle assembly.

    Science.gov (United States)

    Tanenbaum, Marvin E; Medema, René H

    2011-12-01

    Efficient spindle assembly involves the generation of spatial cues around chromosomes that locally stabilize microtubule (MT) plus-ends. In addition to the small GTPase Ran, there is evidence that Aurora B kinase might also generate a spatial cue around chromosomes but direct proof for this is still lacking. Here, we find that the Aurora B substrate MCAK localizes to MT plus-ends throughout the mitotic spindle, but its accumulation is strongly reduced on MT plus-ends near chromatin, suggesting that a signal emanating from chromosomes negatively regulates MCAK plus-end binding. Indeed, we show that Aurora B is the kinase responsible for producing this chromosome-derived signal. These results are the first to visualize spatially restricted Aurora B kinase activity around chromosomes on an endogenous substrate and explain how Aurora B could spatially control the dynamics of non-kinetochore MTs during spindle assembly.

  11. Presynaptic inhibition of muscle spindle and tendon organ afferents in the mammalian spinal cord.

    Science.gov (United States)

    Rudomin, P

    1990-12-01

    More than 30 years ago, Frank and Fuortes proposed that the synaptic effectiveness of muscle spindle afferents associated with spinal motoneurones could be diminished by the activation of nerves from flexor muscles. Since that time, research has focused on disclosing the mode of operation and the spinal pathways involved in this presynaptic inhibitory control. Initially, it was assumed that the same last-order interneurones mediated presynaptic inhibition of both muscle spindle and tendon organ afferent fibres. More recent evidence indicates that the synaptic effectiveness of these two groups of afferents is controlled by separate sets of GABAergic interneurones synapsing directly with the intraspinal terminals of the afferent fibres. This unique arrangement allows for selective control of the information on muscle length or muscle tension, despite the convergence of muscle spindle and tendon organ afferents on second-order interneurones.

  12. A Rare Case Report of Spindle Cell Ameloblastic Carcinoma Involving the Mandible

    Science.gov (United States)

    Kunche, Arunodaya; Ananthaneni, Anuradha; Bagalad, Bhavana S; Kuberappa, Puneeth Horatti

    2017-01-01

    Ameloblastic Carcinoma (AC) is uncommon malignant epithelial odontogenic tumour of jaw, with characteristic histologic features and behavior. Clinically, it has aggressive, infiltrative growth pattern with a distinct predilection for mandible. It exhibits histologic features of ameloblastoma and gets dedifferentiated overtime to culminate in carcinoma. Majority of the cases arise denovo (primary) and only few cases arise from a pre-existing ameloblastoma (secondary). Spindle-cell differentiation in ameloblastic carcinoma is rare; Salter described it as a separate entity “low-grade spindle cell ameloblastic carcinoma. Here we report a case of 32-year-old female patient who presented with a swelling present for past six months. It was diagnosed as Spindle cell Ameloblastic Carcinoma (SpAC), after the hemimandibulectomy the patient was under regular follow up for 14 months, no sign of recurrence was seen. PMID:28274070

  13. Spindle cell variant of ameloblastic carcinoma arising from an unicystic amelobastoma: Report of a rare case

    Directory of Open Access Journals (Sweden)

    Venkatesh V Kamath

    2012-01-01

    Full Text Available Malignant transformation of ameloblastomas arising from an odontogenic cyst or de novo is well-recognized. Malignancies in ameloblastomas may involve metastasis or a local dysplastic change in the tissue. The latter are classified as ameloblastic carcinomas. A 75-year-old male presented with a mandibular cystic swelling, with no evidence of metastasis. Dysplastic ameloblastic cells with spindle-cell transformation were seen arising from a cystic lining with features of a unicystic ameloblastoma. Immunohistochemically the lesion stained positive with cytokeratin 8,19 and alpha smooth muscle actin, but was negative for vimentin. A diagnosis of spindle-cell ameloblastic carcinoma was made. Spindle-cell ameloblastic carcinomas are rare and this is the second case arising from a unicystic ameloblastoma reported in literature. The recognition of this transformation and inclusion of this entity in the classification of ameloblastic carcinomas is stressed.

  14. Sensory reinnervation of muscle spindles after repair of tibial nerve defects using autogenous vein grafts

    Institute of Scientific and Technical Information of China (English)

    Youwang Pang; Qingnan Hong; Jinan Zheng

    2014-01-01

    Motor reinnervation after repair of tibial nerve defects using autologous vein grafts in rats has previously been reported, but sensory reinnervation after the same repair has not been fully investigated. In this study, partial sensory reinnervation of muscle spindles was observed after repair of 10-mm left tibial nerve defects using autologous vein grafts with end-to-end anasto-mosis in rats, and functional recovery was conifrmed by electrophysiological studies. There were no signiifcant differences in the number, size, or electrophysiological function of reinnervated muscle spindles between the two experimental groups. These ifndings suggest that repair of short nerve defects with autologous vein grafts provides comparable results to immediate end-to-end anastomosis in terms of sensory reinnervation of muscle spindles.

  15. Adapt or die: how eukaryotic cells respond to prolonged activation of the spindle assembly checkpoint.

    Science.gov (United States)

    Rossio, Valentina; Galati, Elena; Piatti, Simonetta

    2010-12-01

    Many cancer-treating compounds used in chemotherapies, the so-called antimitotics, target the mitotic spindle. Spindle defects in turn trigger activation of the SAC (spindle assembly checkpoint), a surveillance mechanism that transiently arrests cells in mitosis to provide the time for error correction. When the SAC is satisfied, it is silenced. However, after a variable amount of time, cells escape from the mitotic arrest, even if the SAC is not satisfied, through a process called adaptation or mitotic slippage. Adaptation weakens the killing properties of antimitotics, ultimately giving rise to resistant cancer cells. We summarize here the mechanisms underlying this process and propose a strategy to identify the factors involved using budding yeast as a model system. Inhibition of factors involved in SAC adaptation could have important therapeutic applications by potentiating the ability of antimitotics to cause cell death.

  16. Low-grade fibromatosis-like spindle cell carcinoma of the breast.

    Science.gov (United States)

    Dwyer, Jessica B; Clark, Beth Z

    2015-04-01

    Low-grade fibromatosis-like spindle cell carcinoma is a rare tumor in the breast, and represents a variant of the very heterogeneous group of metaplastic carcinomas of the breast. These tumors warrant distinction because of their resemblance to pure fibromatosis, their propensity for local recurrence, and their favorable prognosis among the metaplastic carcinomas of the breast. The diagnosis is potentially challenging, particularly on core needle biopsies, because of the morphologic overlap with other low-grade spindle cell lesions. Recognition of a proliferation of cytologically bland spindle cells with areas of epithelial differentiation in combination with immunohistochemistry using antibodies against cytokeratins and myoepithelial markers should aid in producing a definitive diagnosis. These tumors can be locally aggressive with an increased incidence of local recurrence, but the potential for lymph node or distant metastasis is low. Complete excision with adequate margins is considered curative in the majority of cases.

  17. Skp2 is required for Aurora B activation in cell mitosis and spindle checkpoint.

    Science.gov (United States)

    Wu, Juan; Huang, Yu-Fan; Zhou, Xin-Ke; Zhang, Wei; Lian, Yi-Fan; Lv, Xiao-Bin; Gao, Xiu-Rong; Lin, Hui-Kuan; Zeng, Yi-Xin; Huang, Jian-Qing

    2015-01-01

    The Aurora B kinase plays a critical role in cell mitosis and spindle checkpoint. Here, we showed that the ubiquitin E3-ligase protein Skp2, also as a cell-cycle regulatory protein, was required for the activation of Aurora B and its downstream protein. When we restored Skp2 knockdown Hela cells with Skp2 and Skp2-LRR E3 ligase dead mutant we found that Skp2 could rescue the defect in the activation of Aurora B, but the mutant failed to do so. Furthermore, we discovered that Skp2 could interact with Aurora B and trigger Aurora B Lysine (K) 63-linked ubiquitination. Finally, we demonstrated the essential role of Skp2 in cell mitosis progression and spindle checkpoint, which was Aurora B dependent. Our results identified a novel ubiquitinated substrate of Skp2, and also indicated that Aurora B ubiquitination might serve as an important event for Aurora B activation in cell mitosis and spindle checkpoint.

  18. High-Speed Spindle Fault Diagnosis with the Empirical Mode Decomposition and Multiscale Entropy Method

    Directory of Open Access Journals (Sweden)

    Nan-Kai Hsieh

    2015-04-01

    Full Text Available The root mean square (RMS value of a vibration signal is an important indicator used to represent the amplitude of vibrations in evaluating the quality of high-speed spindles. However, RMS is unable to detect a number of common fault characteristics that occur prior to bearing failure. Extending the operational life and quality of spindles requires reliable fault diagnosis techniques for the analysis of vibration signals from three axes. This study used empirical mode decomposition to decompose signals into intrinsic mode functions containing a zero-crossing rate and energy to represent the characteristics of rotating elements. The MSE curve was then used to identify a number of characteristic defects. The purpose of this research was to obtain vibration signals along three axes with the aim of extending the operational life of devices included in the product line of an actual spindle manufacturing company.

  19. 梭形细胞血管瘤%Spindle cell hemangioma:a case report

    Institute of Scientific and Technical Information of China (English)

    姜红浩; 吴凤; 朱里; 钱悦; 涂亚庭; 黄长征; 陈思远

    2011-01-01

    报告1 例梭形细胞血管瘤.患者女,52 岁.左足外侧缘、外踝及左跖部结节伴疼痛15 年.皮损组织病理检查示真皮中下层由海绵状血管腔隙和梭形细胞组成的团块,诊断:梭形细胞血管瘤.%A case of spindle cell hemangioma is reported. A 52-year-old woman presented with nodules on the lateral border, extramalleolus and sole of her left foot for 15 years. Histological examination showed the tumor was located at the middle and lower dermis. The tumor was composed of cavernous endothelial cell-lined blood spaces and cellular nests with spindle cells. The patient was diagnosed as spindle cell hemangioma.

  20. The characteristics of machined surface controlled by multi tip arrayed tool and high speed spindle.

    Science.gov (United States)

    Kim, Yong Woo; Choi, Soo Chang; Park, Jeong Woo; Lee, Deug Woo

    2010-07-01

    In this study, we propose one of the ultra-precision machining methods that can be adapted brittle material as well as soft material by using multi arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because particles of grinding tools are irregular size and material can be fragile. Therefore we were able to design tool paths and machine controlled pattern on surface by multi arrayed diamond tips which has uniform size made in MEMS fabrication and high speed spindle of which maximum speed is about 300,000 rpm. We defined several parameters that can have effect on machining surface. Those are multi array of diamond tips (n * n), speed of the air spindle, and feeding rate. Surface roughness and surface texture can be controlled by those parameters for micro machining.

  1. Semaphorin-Plexin Signaling Controls Mitotic Spindle Orientation during Epithelial Morphogenesis and Repair

    DEFF Research Database (Denmark)

    Xia, Jingjing; Swiercz, Jakub M.; Bañón-Rodríguez, Inmaculada

    2015-01-01

    Morphogenesis, homeostasis, and regeneration of epithelial tissues rely on the accurate orientation of cell divisions, which is specified by the mitotic spindle axis. To remain in the epithelial plane, symmetrically dividing epithelial cells align their mitotic spindle axis with the plane. Here, we...... show that this alignment depends on epithelial cell-cell communication via semaphorin-plexin signaling. During kidney morphogenesis and repair, renal tubular epithelial cells lacking the transmembrane receptor Plexin-B2 or its semaphorin ligands fail to correctly orient the mitotic spindle, leading...... to severe defects in epithelial architecture and function. Analyses of a series of transgenic and knockout mice indicate that Plexin-B2 controls the cell division axis by signaling through its GTPase-activating protein (GAP) domain and Cdc42. Our data uncover semaphorin-plexin signaling as a central...

  2. Gas flow through the clearances of screw spindle vacuum pumps; Gasspaltstroemungen in Schraubenspindel-Vakuumpumpen

    Energy Technology Data Exchange (ETDEWEB)

    Kauder, K.; Wenderott, D. [Dortmund Univ. (Germany). FG Fluidenergiemaschinen

    1998-12-31

    The documentation `Schraubenmaschinen` deals with the subject `screw spindle vacuum pump` for the first time. Therefore, this paper presents the type of maschine `screw spindle vacuum pump`, fixes its limits to the better known screw type compressor and finally classifies it in the crossover of vacuum-technology, characteristic geometry and the numerical simulation. The suggested reflections to choose a proper model of flow are based on the geometry of the screw spindle vacuum pump and fundamentals concerning the vacuum-technology and the state of flow. (orig.) [Deutsch] Die Schriftenreihe `Schraubenmaschinen` behandelt erstmals das Thema `Schraubenspindel-Vakuumpumpe`. Aus diesem Grund stellt der vorliegende Beitrag den Maschinentyp Schraubenspindel-Vakuumpumpe vor, grenzt ihn zur bekannteren Schraubenmaschine ab und ordnet ihn in der Schnittmenge aus Vakuumtechnik, charakteristischer Maschinengeometrie und der Simulation ein. Auf den vakuumtechnischen und stroemungstechnischen Grundlagen sowie geometrischen Betrachtungen basieren die genannten Ueberlegungen zur Auswahl geeigneter Stroemungsmodelle. (orig.)

  3. Masseter length determines muscle spindle reflex excitability during jaw-closing movements.

    Science.gov (United States)

    Naser-Ud-Din, Shazia; Sowman, Paul F; Sampson, Wayne J; Dreyer, Craig W; Türker, Kemal Sitki

    2011-04-01

    The masticatory muscles are considered to be important determinants of facial form, but little is known of the muscle spindle reflex characteristics and their relationship, if any, to face height. The aim of this study was to determine whether spindle reflexes, evoked by mechanical stimulation of an incisor and recorded on the masseter muscle, correlated with different facial patterns. Twenty-eight adult volunteers (16 women; ages, 19-38 years) underwent 2-N tap stimuli to their maxillary left central incisor during simulated mastication. Reflexes were recorded during local anesthesia of the stimulated tooth to eliminate the contribution from periodontal mechanoreceptors. Surface electromyograms of the reflex responses of the jaw muscles to these taps were recorded via bipolar electrodes on the masseter muscle and interpreted by using spike-triggered averaging of the surface electromyograms. Lateral cephalometric analysis was carried out with software (version 10.5, Dolphin, Los Angeles, Calif; and Mona Lisa, Canberra, Australia). Two-newton tooth taps produced principally excitatory reflex responses beginning at 17 ms poststimulus. Correlation analysis showed a significant relationship between these muscle spindle reflexes and facial heights: specifically, shorter face heights were associated with stronger spindle reflexes. This correlation was strongest between the derived measure of masseter length and the spindle reflex strength during jaw closure (r = -0.49, P = 0.008). These results suggest that a similar muscle spindle stimulus will generate a stronger reflex activation in the jaw muscles of patients with shorter faces compared with those with longer faces. This finding might help to explain the higher incidence of clenching or bruxism in those with short faces and also might, in the future, influence the design of orthodontic appliances and dental prostheses. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights

  4. Driving systems: innovations - trends - mechatronics; Antriebssysteme: Innovationen - Trends - Mechatronik

    Energy Technology Data Exchange (ETDEWEB)

    Binder, A. [Technische Univ. Darmstadt (Germany). Inst. fuer Elektrische Energiewandlung; Doppelbauer, M. [SEW-Eurodrive GmbH und Co.KG, Bruchsal (DE). Entwicklung und Konstruktion Motoren (EML); Gold, P.W. [RWTH Aachen (Germany). Inst. fuer Maschinenelemente und Maschinengestaltung; Hofmann, W. [Technische Univ. Chemnitz (Germany). Lehrstuhl fuer Elektrische Maschinen und Antriebe

    2007-03-15

    Short overview on this special meeting with interdisciplinary topics of connection between mechanical and electrical engineering: mechatronics. The main topics are covered by the fields motion control, simulation of drives, monitoring, gears, motors engineering/-design, converter systems, industrial applications and drives for wind turbines. (GL)

  5. Temperature field measurement of spindle ball bearing under radial force based on fiber Bragg grating sensors

    Directory of Open Access Journals (Sweden)

    Yanfang Dong

    2015-12-01

    Full Text Available Bearing temperature rise amplitude is related to the running state of bearing and spindle thermal error, so the measurement of bearing temperature field is helpful to ascertain the bearing running characteristic and analysis of the spindle thermal error. On the basis of thoroughly understood several reasons of bearing heat generation, this article analyzes bearing temperature field simulation based on ANSYS and bearing temperature field measurement based on fiber Bragg grating sensors. The results showed that using fiber Bragg grating is able to complete the bearing temperature field distribution measurement perfectly.

  6. Functions of spindle check-point and its relationship to chromosome instability

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    It is generally believed that the equal distribution of genetic materials to two daughter cells during mitosis is the key to cell health and development. During the dynamic process, spindle checkpoint plays a very important role in chromosome movements and final sister chromatid separation. The equal and precise segregation of chromosomes contributes to the genomic stability while aberrant separations result in chromosome instability that causes pathogenesis of certain diseases such as Down's syndrome and cancers. Kinetochore and its regulatory proteins consist of the spindle checkpoint and determine the spatial and temporal orders of chromosome segregation.

  7. Pengaturan Kecepatan Motor Spindle pada Retrofit Mesin Bubut CNC Menggunakan Kontroler PID Gain Scheduling

    Directory of Open Access Journals (Sweden)

    Fikri Yoga Permana

    2013-03-01

    Full Text Available Pada mesin bubut Computerized Numerical Control (CNC, proses pemahatan benda kerja memerlukan kecepatan potong yang tetap agar hasil kerja memiliki tingkat presisi tinggi. Dalam prakteknya, ketika terjadi pemotongan, diameter benda kerja akan selalu berkurang dan tingkat kedalaman pahat berubah-ubah sesuai dengan proses yang dilakukan sehingga mempengaruhi kecepatan putar motor spindle sehingga mengakibatkan tingkat presisi hasil kerja menjadi berkurang. Pada penelitian ini, digunakan kontroler PI Gain Scheduling untuk mengatur kecapatan motor spindle. Hasil yang didapatkan berupa simulasi kontroler PI Gain Scheduling. Dari hasil simulasi didapatkan kontroler PI Gain Scheduling mampu membuat respon sistem sesuai dengan yang diinginkan.

  8. [Plus end tracking proteins and their role in mitotic spindle organization].

    Science.gov (United States)

    Bajer, Seweryn; Kasprzak, Andrzej A

    2009-01-01

    Plus end tracking proteins (+TIPs) form a diverse protein family, members of which were found in all eukaryotes. Their characteristic feature is the ability of localisation on dynamically growing plus ends of microtubules. +TIPs perform many important functions during mitosis: they control microtubule growth, the recruitment of other proteins to the microtubule plus end and promote the interaction of microtubules with other elements of the spindle. In the article we describe the structure of main +TIPs groups, focusing especially on domains responsible for plus end tracking. We also discuss several mechanisms for plus-end accumulation, the influence of these proteins on microtubule dynamics and their importance in the spindle organization.

  9. Structures of actin-like ParM filaments show architecture of plasmid-segregating spindles

    OpenAIRE

    Bharat, Tanmay A. M.; Murshudov, Garib N.; Sachse, Carsten; Löwe, Jan

    2015-01-01

    Active segregation of E. coli low-copy number plasmid R1 involves formation of a bipolar spindle made of left-handed double-helical actin-like ParM filaments 1-6 . ParR links the filaments with centromeric parC plasmid DNA, while facilitating the addition of subunits to ParM filaments 3,7-9 . Growing ParMRC spindles push sister plasmids to the cell poles 9,10 . Here, using modern electron cryomicroscopy methods we have investigated the structures and arrangements of ParM filaments in vitro an...

  10. Primary undifferentiated spindle-cell sarcoma of sella turcica: successful treatment with adjuvant temozolomide.

    Science.gov (United States)

    Sareen, Pooja; Chhabra, Lovely; Trivedi, Nitin

    2013-05-27

    Sellar tumours in adults are most commonly pituitary adenomas. Primary spindle cell sarcoma of the sella turcica without a prior history of cranial radiation is extremely rare. We report a case of a large sellar mass with suprasellar and cavernous sinus extension in a geriatric male patient who presented with complete left oculomotor nerve palsy and panhypopituitarism. The patient underwent partial resection of the sellar mass through transcranial route. The pathology of the mass revealed a poorly differentiated spindle cell neoplasm most consistent with a sarcoma. Postoperatively, the size of the residual sellar mass decreased significantly following six cycles of external beam radiation in conjunction with temozolomide.

  11. Successful treatment of spindle cell sarcoma of the sella turcica. Case report.

    Science.gov (United States)

    Alpert, Tracy E; Hahn, Seung S; Chung, Chung T; Bogart, Jeffrey A; Hodge, Charles J; Montgomery, Craig

    2002-12-01

    A primary spindle cell sarcoma of the sella turcica in a patient without a history of radiation treatment is a very rare occurrence. Only one other case has been reported to date, with local recurrence 7 months after the patient underwent subtotal resection and stereotactic radiosurgery of the tumor. The authors present a case of spindle cell sarcoma of the sella turcica successfully treated by surgery, external-beam radiotherapy, and gamma knife radiosurgery. After 24 months of follow up, the patient continues to show no evidence of disease.

  12. Meiosis-specific stable binding of augmin to acentrosomal spindle poles promotes biased microtubule assembly in oocytes.

    Science.gov (United States)

    Colombié, Nathalie; Głuszek, A Agata; Meireles, Ana M; Ohkura, Hiroyuki

    2013-06-01

    In the oocytes of many animals including humans, the meiotic spindle assembles without centrosomes. It is still unclear how multiple pathways contribute to spindle microtubule assembly, and whether they are regulated differently in mitosis and meiosis. Augmin is a γ-tubulin recruiting complex which "amplifies" spindle microtubules by generating new microtubules along existing ones in mitosis. Here we show that in Drosophila melanogaster oocytes Augmin is dispensable for chromatin-driven assembly of bulk spindle microtubules, but is required for full microtubule assembly near the poles. The level of Augmin accumulated at spindle poles is well correlated with the degree of chromosome congression. Fluorescence recovery after photobleaching shows that Augmin stably associates with the polar regions of the spindle in oocytes, unlike in mitotic cells where it transiently and uniformly associates with the metaphase spindle. This stable association is enhanced by γ-tubulin and the kinesin-14 Ncd. Therefore, we suggest that meiosis-specific regulation of Augmin compensates for the lack of centrosomes in oocytes by actively biasing sites of microtubule generation within the spindle.

  13. Characterization of Ring-Like F-Actin Structure as a Mechanical Partner for Spindle Positioning in Mitosis

    Science.gov (United States)

    Jiang, Hao; Zhu, Tongge; Xia, Peng; Seffens, William; Aikhionbare, Felix; Wang, Dongmei; Dou, Zhen; Yao, Xuebiao

    2014-01-01

    Proper spindle positioning and orientation are essential for accurate mitosis which requires dynamic interactions between microtubule and actin filament (F-actin). Although mounting evidence demonstrates the role of F-actin in cortical cytoskeleton dynamics, it remains elusive as to the structure and function of F-actin-based networks in spindle geometry. Here we showed a ring-like F-actin structure surrounding the mitotic spindle which forms since metaphase and maintains in MG132-arrested metaphase HeLa cells. This cytoplasmic F-actin structure is relatively isotropic and less dynamic. Our computational modeling of spindle position process suggests a possible mechanism by which the ring-like F-actin structure can regulate astral microtubule dynamics and thus mitotic spindle orientation. We further demonstrated that inhibiting Plk1, Mps1 or Myosin, and disruption of microtubules or F-actin polymerization perturbs the formation of the ring-like F-actin structure and alters spindle position and symmetric division. These findings reveal a previously unrecognized but important link between mitotic spindle and ring-like F-actin network in accurate mitosis and enables the development of a method to theoretically illustrate the relationship between mitotic spindle and cytoplasmic F-actin. PMID:25299690

  14. Meiosis-specific stable binding of augmin to acentrosomal spindle poles promotes biased microtubule assembly in oocytes.

    Directory of Open Access Journals (Sweden)

    Nathalie Colombié

    2013-06-01

    Full Text Available In the oocytes of many animals including humans, the meiotic spindle assembles without centrosomes. It is still unclear how multiple pathways contribute to spindle microtubule assembly, and whether they are regulated differently in mitosis and meiosis. Augmin is a γ-tubulin recruiting complex which "amplifies" spindle microtubules by generating new microtubules along existing ones in mitosis. Here we show that in Drosophila melanogaster oocytes Augmin is dispensable for chromatin-driven assembly of bulk spindle microtubules, but is required for full microtubule assembly near the poles. The level of Augmin accumulated at spindle poles is well correlated with the degree of chromosome congression. Fluorescence recovery after photobleaching shows that Augmin stably associates with the polar regions of the spindle in oocytes, unlike in mitotic cells where it transiently and uniformly associates with the metaphase spindle. This stable association is enhanced by γ-tubulin and the kinesin-14 Ncd. Therefore, we suggest that meiosis-specific regulation of Augmin compensates for the lack of centrosomes in oocytes by actively biasing sites of microtubule generation within the spindle.

  15. Sequential activities of Dynein, Mud and Asp in centrosome-spindle coupling maintain centrosome number upon mitosis.

    Science.gov (United States)

    Bosveld, Floris; Ainslie, Anna; Bellaïche, Yohanns

    2017-09-01

    Centrosomes nucleate microtubules and are tightly coupled to the bipolar spindle to ensure genome integrity, cell division orientation and centrosome segregation. While the mechanisms of centrosome-dependent microtubule nucleation and bipolar spindle assembly have been the focus of numerous works, less is known on the mechanisms ensuring the centrosome-spindle coupling. The conserved NuMA protein (Mud in Drosophila) is best known for its role in spindle orientation. Here we analyzed the role of Mud and two of its interactors, Asp and Dynein, in the regulation of centrosome numbers in Drosophila epithelial cells. We found that Dynein and Mud mainly initiate centrosome-spindle coupling prior to nuclear envelope breakdown (NEB) by promoting correct centrosome positioning or separation, while Asp acts largely independently of Dynein and Mud to maintain centrosome-spindle coupling. Failure in the centrosome-spindle coupling leads to mis-segregation of the two centrosomes into one daughter cell resulting in cells with supernumerary centrosomes during subsequent divisions. Together, we propose that Dynein, Mud and Asp sequentially operate during the cell cycle to ensure efficient centrosome-spindle coupling in mitosis preventing centrosome mis-segregation to maintain centrosome number. © 2017. Published by The Company of Biologists Ltd.

  16. Validation of a novel automatic sleep spindle detector with high performance during sleep in middle aged subjects

    DEFF Research Database (Denmark)

    Wendt, Sabrina Lyngbye; Christensen, Julie A. E.; Kempfner, Jacob

    2012-01-01

    Many of the automatic sleep spindle detectors currently used to analyze sleep EEG are either validated on young subjects or not validated thoroughly. The purpose of this study is to develop and validate a fast and reliable sleep spindle detector with high performance in middle aged subjects. An a...

  17. Turbulent current drive mechanisms

    Science.gov (United States)

    McDevitt, Christopher J.; Tang, Xian-Zhu; Guo, Zehua

    2017-08-01

    Mechanisms through which plasma microturbulence can drive a mean electron plasma current are derived. The efficiency through which these turbulent contributions can drive deviations from neoclassical predictions of the electron current profile is computed by employing a linearized Coulomb collision operator. It is found that a non-diffusive contribution to the electron momentum flux as well as an anomalous electron-ion momentum exchange term provide the most efficient means through which turbulence can modify the mean electron current for the cases considered. Such turbulent contributions appear as an effective EMF within Ohm's law and hence provide an ideal means for driving deviations from neoclassical predictions.

  18. Polar Direct Drive

    Science.gov (United States)

    Skupsky, S.

    2003-10-01

    Direct drive offers the potential of higher target gain on the National Ignition Facility (NIF) than x-ray drive: The initial direct-drive target design had a 1-D gain of 45 and consisted primarily of a pure cryogenic DT shell. Using the expected levels of target and laser nonuniformities for the NIF, two-dimensional (2-D) hydrodynamic simulations predicted target gains around 30.(P.W. McKenty et al.), Phys. Plasmas 8, 2315 (2001). More-recent designs have shown that higher target gains could be obtained by replacing a portion of the DT shell with ``wetted'' CH foam and by using adiabat shaping: (1) Higher-Z material (C) in the foam increases laser absorption by about 40% (from 60% absorption to 85%).(S. Skupsky et al.), in Inertial Fusion Sciences and Applications 2001, edited by K. Tanaka et al. (Elsevier, Paris, 2002), p. 240. (2) Adiabat shaping allows the main portion of the fuel to be placed on a lower adiabat without compromising target stability.(V.N. Goncharov et al.), Phys. Plasmas 10, 1906 (2003). These direct-drive concepts can be tested on the NIF, long before that facility is converted to a direct-drive (spherically symmetric) irradiation configuration. Using the NIF x-ray-drive beam configuration, some of the near-polar beams could be pointed to better illuminate the target's equator. These more-oblique, equatorial beams will have lower absorption and reduced drive efficiency than the polar beams. One strategy to compensate for the difference in polar and equatorial drive is to reduce the irradiation at the poles and employ different pulse shapes to accommodate the time-dependent variations in drive and absorption. This concept of polar direct drive (PDD) has been studied using the 2-D hydrocode DRACO to determine the requirements for achieving ignition and moderate target gain for the NIF. Experiments on the OMEGA laser will examine the effects of oblique irradiation on target drive. Results of simulations for different direct-drive target designs

  19. Road Safety Data, Collection, Transfer and Analysis DaCoTa. Workpackage 6, Driver Behaviour Monitoring through Naturalistic Driving: Deliverable 6.2: Part A: Study design of naturalistic driving observations within ERSO - development of innovative indicators for exposure and safety performance measures.

    NARCIS (Netherlands)

    Bonnard, A. Brusque, C. Hugot, M. Commandeur, J.J.F. & Christoph, M.W.T.

    2015-01-01

    The objective of the Task 6.2 of DaCoTA is to specify the study design of naturalistic driving study in the perspective of the European Road Safety Observatory. More precisely, the task deals with three main issues: 1) the experimental design, 2) the procedures to Risk Exposure Data (RED) and Safety

  20. Ipl1/Aurora kinase suppresses S-CDK-driven spindle formation during prophase I to ensure chromosome integrity during meiosis.

    Directory of Open Access Journals (Sweden)

    Louise Newnham

    Full Text Available Cells coordinate spindle formation with DNA repair and morphological modifications to chromosomes prior to their segregation to prevent cell division with damaged chromosomes. Here we uncover a novel and unexpected role for Aurora kinase in preventing the formation of spindles by Clb5-CDK (S-CDK during meiotic prophase I and when the DDR is active in budding yeast. This is critical since S-CDK is essential for replication during premeiotic S-phase as well as double-strand break induction that facilitates meiotic recombination and, ultimately, chromosome segregation. Furthermore, we find that depletion of Cdc5 polo kinase activity delays spindle formation in DDR-arrested cells and that ectopic expression of Cdc5 in prophase I enhances spindle formation, when Ipl1 is depleted. Our findings establish a new paradigm for Aurora kinase function in both negative and positive regulation of spindle dynamics.

  1. Human oocytes. Error-prone chromosome-mediated spindle assembly favors chromosome segregation defects in human oocytes.

    Science.gov (United States)

    Holubcová, Zuzana; Blayney, Martyn; Elder, Kay; Schuh, Melina

    2015-06-05

    Aneuploidy in human eggs is the leading cause of pregnancy loss and several genetic disorders such as Down syndrome. Most aneuploidy results from chromosome segregation errors during the meiotic divisions of an oocyte, the egg's progenitor cell. The basis for particularly error-prone chromosome segregation in human oocytes is not known. We analyzed meiosis in more than 100 live human oocytes and identified an error-prone chromosome-mediated spindle assembly mechanism as a major contributor to chromosome segregation defects. Human oocytes assembled a meiotic spindle independently of either centrosomes or other microtubule organizing centers. Instead, spindle assembly was mediated by chromosomes and the small guanosine triphosphatase Ran in a process requiring ~16 hours. This unusually long spindle assembly period was marked by intrinsic spindle instability and abnormal kinetochore-microtubule attachments, which favor chromosome segregation errors and provide a possible explanation for high rates of aneuploidy in human eggs.

  2. The Effect of the Rotor Static Eccentricity on the Electro-Mechanical Coupled Characteristics of the Motorized Spindle

    Directory of Open Access Journals (Sweden)

    Wu Zaixin

    2016-01-01

    Full Text Available High-speed motorized spindle is a multi-variable, non-linear and strong coupling system. The rotor static eccentricity is inevitable because of machining or assembling error. The rotor static eccentricities have an important effect on the electromechanical coupled characteristics of the motorized spindle. In this paper, the electromechanical coupled mathematical model of the motorized spindle was set up. The mathematical model includes mechanical and electrical equation. The mechanical and electrical equation is built up by the variational principle. Furthermore, the inductance parameters without the rotor static eccentricity and the inductance parameters with rotor static eccentricity have been calculated by the winding function method and the high speed motorized spindle was simulated. The result show that the rotor static eccentricity can delay the starting process of the motorized spindle, and at steady state, the rotor circuit currents are still large because of the rotor static eccentricity.

  3. Experimental Study on Meiotic Spindles and Chromosomes of Mouse Mature (MⅡ) Stage Oocytes under Laser Scanning Confocal Microscopy

    Institute of Scientific and Technical Information of China (English)

    WANG Yanlin; ZHU Guijin; LI Xia; LI Xiaolan

    2006-01-01

    Taking the mouse as a model, the experimental method of observing the morphology of meiotic spindles and chromosomes in mature oocytes were investigated in order to evaluate the effects of various interventions on the quality of oocytes accurately and rapidly. Laser scanning confocal microscope (LSCM) was used to examine the meiotic spindles and chromosomes by the technologies of optical section and three-dimensional (3D) image reconstruction. The results showed that the configurations of meiotic spindles and chromosomes could be observed clearly by LSCM.The normal rate of meiotic spindles and chromosomes was 82% and 86% respectively. It was concluded that the LSCM was a valid instrument to observe the meiotic spindles and chromosomes of mature oocytes and could be used as a valid method to evaluate the quality of M Ⅱ oocytes.

  4. Driving in a womb

    NARCIS (Netherlands)

    Anonymous

    Drive thousands of kilometres on just a litre of fuel? During the annual Shell eco-marathon at the end of May, schoolchildren and students – including a team from TU Delft – demonstrated that it can indeed be done.

  5. Instant Google Drive starter

    CERN Document Server

    Procopio, Mike

    2013-01-01

    This book is a Starter which teaches you how to use Google Drive practically. This book is perfect for people of all skill levels who want to enjoy the benefits of using Google Drive to safely store their files online and in the cloud. It's also great for anyone looking to learn more about cloud computing in general. Readers are expected to have an Internet connection and basic knowledge of using the internet.

  6. Marine winch drive systems

    Energy Technology Data Exchange (ETDEWEB)

    Clifford, M.; Smith, P.M.

    1983-12-01

    In the design of marine winch drive systems, efficiency, controllability, compactness and component layout flexibility are major considerations. This paper discusses design concepts aimed at achieving the above considerations in the design of variable speed, hydrostatic, marine winch drive systems. These concepts utilize a high pressure, load sensing pump, and a low-speed, high-torque (LSHT), radial-piston, hydraulic motor. These components are then shown applied in several open circuit hydrostatic power transmission systems.

  7. Stage-independent, single lead EEG sleep spindle detection using the continuous wavelet transform and local weighted smoothing

    Directory of Open Access Journals (Sweden)

    Athanasios eTsanas

    2015-04-01

    Full Text Available Sleep spindles are critical in characterizing sleep and have been associated with cognitive function and pathophysiological assessment. Typically, their detection relies on the subjective and time-consuming visual examination of electroencephalogram (EEG signal(s by experts, and has led to large inter-rater variability as a result of poor definition of sleep spindle characteristics. Hitherto, many algorithmic spindle detectors inherently make signal stationarity assumptions (e.g. Fourier transform-based approaches which are inappropriate for EEG signals, and frequently rely on additional information which may not be readily available in many practical settings (e.g. more than one EEG channels, or prior hypnogram assessment. This study proposes a novel signal processing methodology relying solely on a single EEG channel, and provides objective, accurate means towards probabilistically assessing the presence of sleep spindles in EEG signals. We use the intuitively appealing continuous wavelet transform (CWT with a Morlet basis function, identifying regions of interest where the power of the CWT coefficients corresponding to the frequencies of spindles (11-16 Hz is large. The potential for assessing the signal segment as a spindle is refined using local weighted smoothing techniques. We evaluate our findings on two databases: the MASS database comprising 19 healthy controls and the DREAMS sleep spindle database comprising eight participants diagnosed with various sleep pathologies. We demonstrate that we can replicate the experts’ sleep spindles assessment accurately in both databases (MASS database: sensitivity: 84%, specificity: 90%, false discovery rate 83%, DREAMS database: sensitivity: 76%, specificity: 92%, false discovery rate: 67%, outperforming six competing automatic sleep spindle detection algorithms in terms of correctly replicating the experts’ assessment of detected spindles.

  8. Uncovering the molecular machinery of the human spindle--an integration of wet and dry systems biology.

    Directory of Open Access Journals (Sweden)

    Ana M Rojas

    Full Text Available The mitotic spindle is an essential molecular machine involved in cell division, whose composition has been studied extensively by detailed cellular biology, high-throughput proteomics, and RNA interference experiments. However, because of its dynamic organization and complex regulation it is difficult to obtain a complete description of its molecular composition. We have implemented an integrated computational approach to characterize novel human spindle components and have analysed in detail the individual candidates predicted to be spindle proteins, as well as the network of predicted relations connecting known and putative spindle proteins. The subsequent experimental validation of a number of predicted novel proteins confirmed not only their association with the spindle apparatus but also their role in mitosis. We found that 75% of our tested proteins are localizing to the spindle apparatus compared to a success rate of 35% when expert knowledge alone was used. We compare our results to the previously published MitoCheck study and see that our approach does validate some findings by this consortium. Further, we predict so-called "hidden spindle hub", proteins whose network of interactions is still poorly characterised by experimental means and which are thought to influence the functionality of the mitotic spindle on a large scale. Our analyses suggest that we are still far from knowing the complete repertoire of functionally important components of the human spindle network. Combining integrated bio-computational approaches and single gene experimental follow-ups could be key to exploring the still hidden regions of the human spindle system.

  9. Influence of Motion Errors of Feed Drive Systems on Machined Surface

    Science.gov (United States)

    Nishio, Kentaro; Sato, Ryuta; Shirase, Keiichi

    The purpose of this study is to clarify the relationship between the dynamic motion errors of feed drive systems and the machined surfaces. To achieve this purpose, a simulation method for a machined surface by peripheral milling is proposed. In the proposed method, the motion errors of a feed drive system and the machined surface are simulated based on tool diameter, number of flutes, spindle speed, and feed speed. In addition, to clarify the correctness of the proposed method, actual cutting tests are carried out. In the cutting tests, the control parameters of the machine tool are intentionally changed to obtain the motion errors. As the results of the cutting tests, it is confirmed that the influence of the motion errors of feed drive systems on machined surface can be predicted by the proposed simulation method. The relationship between the motion errors and machined surfaces is also examined based on the simulations.

  10. Dementia and driving.

    Science.gov (United States)

    O'Neill, D; Neubauer, K; Boyle, M; Gerrard, J; Surmon, D; Wilcock, G K

    1992-04-01

    Many European countries test cars, but not their drivers, as they age. There is evidence to suggest that human factors are more important than vehicular factors as causes of motor crashes. The elderly also are involved in more accidents per distance travelled than middle-aged drivers. As the UK relies on self-certification of health by drivers over the age of 70 years, we examined the driving practices of patients with dementia attending a Memory Clinic. Nearly one-fifth of 329 patients with documented dementia continued to drive after the onset of dementia, and impaired driving ability was noted in two-thirds of these. Their families experienced great difficulty in persuading patients to stop driving, and had to invoke outside help in many cases. Neuropsychological tests did not help to identify those who drove badly while activity of daily living scores were related to driving ability. These findings suggest that many patients with dementia drive in an unsafe fashion after the onset of the illness. The present system of self-certification of health by the elderly for driver-licensing purposes needs to be reassessed.

  11. Self-driving carsickness.

    Science.gov (United States)

    Diels, Cyriel; Bos, Jelte E

    2016-03-01

    This paper discusses the predicted increase in the occurrence and severity of motion sickness in self-driving cars. Self-driving cars have the potential to lead to significant benefits. From the driver's perspective, the direct benefits of this technology are considered increased comfort and productivity. However, we here show that the envisaged scenarios all lead to an increased risk of motion sickness. As such, the benefits this technology is assumed to bring may not be capitalised on, in particular by those already susceptible to motion sickness. This can negatively affect user acceptance and uptake and, in turn, limit the potential socioeconomic benefits that this emerging technology may provide. Following a discussion on the causes of motion sickness in the context of self-driving cars, we present guidelines to steer the design and development of automated vehicle technologies. The aim is to limit or avoid the impact of motion sickness and ultimately promote the uptake of self-driving cars. Attention is also given to less well known consequences of motion sickness, in particular negative aftereffects such as postural instability, and detrimental effects on task performance and how this may impact the use and design of self-driving cars. We conclude that basic perceptual mechanisms need to be considered in the design process whereby self-driving cars cannot simply be thought of as living rooms, offices, or entertainment venues on wheels.

  12. Cyclin G-associated kinase promotes microtubule outgrowth from chromosomes during spindle assembly.

    Science.gov (United States)

    Tanenbaum, Marvin E; Vallenius, Tea; Geers, Erica F; Greene, Lois; Mäkelä, Tomi P; Medema, Rene H

    2010-08-01

    During mitosis, all chromosomes must attach to microtubules of the mitotic spindle to ensure correct chromosome segregation. Microtubule attachment occurs at specialized structures at the centromeric region of chromosomes, called kinetochores. These kinetochores can generate microtubule attachments through capture of centrosome-derived microtubules, but in addition, they can generate microtubules themselves, which are subsequently integrated with centrosome-derived microtubules to form the mitotic spindle. Here, we have performed a large scale RNAi screen and identify cyclin G-associated kinase (GAK) as a novel regulator of microtubule generation at kinetochores/chromatin. This function of GAK requires its C-terminal J-domain, which is essential for clathrin recycling from endocytic vesicles. Consistently, cells lacking GAK show strongly reduced levels of clathrin on the mitotic spindle, and reduction of clathrin levels also inhibits microtubule generation at kinetochores/chromosomes. Finally, we present evidence that association of clathrin with the spindle is promoted by a signal coming from the chromosomes. These results identify a role for GAK and clathrin in microtubule outgrowth from kinetochores/chromosomes and suggest that GAK acts through clathrin to control microtubule outgrowth around chromosomes.

  13. Whole genome functional analysis identifies novel components required for mitotic spindle integrity in human cells

    Science.gov (United States)

    Rines, Daniel R; Gomez-Ferreria, Maria Ana; Zhou, Yingyao; DeJesus, Paul; Grob, Seanna; Batalov, Serge; Labow, Marc; Huesken, Dieter; Mickanin, Craig; Hall, Jonathan; Reinhardt, Mischa; Natt, Francois; Lange, Joerg; Sharp, David J; Chanda, Sumit K; Caldwell, Jeremy S

    2008-01-01

    Background The mitotic spindle is a complex mechanical apparatus required for accurate segregation of sister chromosomes during mitosis. We designed a genetic screen using automated microscopy to discover factors essential for mitotic progression. Using a RNA interference library of 49,164 double-stranded RNAs targeting 23,835 human genes, we performed a loss of function screen to look for small interfering RNAs that arrest cells in metaphase. Results Here we report the identification of genes that, when suppressed, result in structural defects in the mitotic spindle leading to bent, twisted, monopolar, or multipolar spindles, and cause cell cycle arrest. We further describe a novel analysis methodology for large-scale RNA interference datasets that relies on supervised clustering of these genes based on Gene Ontology, protein families, tissue expression, and protein-protein interactions. Conclusion This approach was utilized to classify functionally the identified genes in discrete mitotic processes. We confirmed the identity for a subset of these genes and examined more closely their mechanical role in spindle architecture. PMID:18302737

  14. Design of a Micro Milling Setup with an Active Magnetic Bearing Spindle

    NARCIS (Netherlands)

    Kimman, M.H.

    2010-01-01

    This thesis describes the design of a micro milling setup with an active magnetic bearing spindle. Micro milling is the mechanical removal of material with sub millimeter tools. An active magnetic bearing typically consists of a set of magnetic actuators, a control loop and position sensors.

  15. Spindle Thermal Error Optimization Modeling of a Five-axis Machine Tool

    Institute of Scientific and Technical Information of China (English)

    Qianjian GUO; Shuo FAN; Rufeng XU; Xiang CHENG; Guoyong ZHAO; Jianguo YANG

    2017-01-01

    Aiming at the problem of low machining accuracy and uncontrollable thermal errors of NC machine tools,spindle thermal error measurement,modeling and compensation of a two turntable five-axis machine tool are researched.Measurement experiment of heat sources and thermal errors are carried out,and GRA(grey relational analysis) method is introduced into the selection of temperature variables used for thermal error modeling.In order to analyze the influence of different heat sources on spindle thermal errors,an ANN (artificial neural network) model is presented,and ABC(artificial bee colony) algorithm is introduced to train the link weights of ANN,a new ABCNN(Artificial bee colony-based neural network) modeling method is proposed and used in the prediction of spindle thermal errors.In order to test the prediction performance of ABC-NN model,an experiment system is developed,the prediction results of LSR (least squares regression),ANN and ABC-NN are compared with the measurement results of spindle thermal errors.Experiment results show that the prediction accuracy of ABC-NN model is higher than LSR and ANN,and the residual error is smaller than 3 μm,the new modeling method is feasible.The proposed research provides instruction to compensate thermal errors and improve machining accuracy of NC machine tools.

  16. Potato spindle tuber viroid detection in phloem exudates and guttation fluid of tomato plants (Solanum lycopersicum)

    Science.gov (United States)

    Potato spindle tuber viroid (PSTVd) is a single-stranded, non protein-encoding, covalently-closed circular RNA molecule (359nt) that infects many horticultural and agricultural crops. PSTVd is mechanically transmitted, replicates in the nucleus, and moves cell-to-cell through plasmodesmata. Though i...

  17. Computational analysis of the spatial distribution of mitotic spindle angles in mouse developing airway

    Science.gov (United States)

    Tang, Nan; Marshall, Wallace F.

    2013-02-01

    Investigating the spatial information of cellular processes in tissues during mouse embryo development is one of the major technical challenges in development biology. Many imaging methods are still limited to the volumes of tissue due to tissue opacity, light scattering and the availability of advanced imaging tools. For analyzing the mitotic spindle angle distribution in developing mouse airway epithelium, we determined spindle angles in mitotic epithelial cells on serial sections of whole airway of mouse embryonic lungs. We then developed a computational image analysis to obtain spindle angle distribution in three dimensional airway reconstructed from the data obtained from all serial sections. From this study, we were able to understand how mitotic spindle angles are distributed in a whole airway tube. This analysis provides a potentially fast, simple and inexpensive alternative method to quantitatively analyze cellular process at subcellular resolution. Furthermore, this analysis is not limited to the size of tissues, which allows to obtain three dimensional and high resolution information of cellular processes in cell populations deeper inside intact organs.

  18. Reduced Sleep Spindle Activity in Early-Onset and Elevated Risk for Depression

    Science.gov (United States)

    Lopez, Jorge; Hoffmann, Robert; Armitage, Roseanne

    2010-01-01

    Objective: Sleep disturbances are common in major depressive disorder (MDD), although polysomnographic (PSG) abnormalities are more prevalent in adults than in children and adolescents with MDD. Sleep spindle activity (SPA) is associated with neuroplasticity mechanisms during brain maturation and is more abundant in childhood and adolescence than…

  19. An evaluation of spindle-shaft seizure accident sequences for the Schenck Dynamic Balancer

    Energy Technology Data Exchange (ETDEWEB)

    Bott, T.F.; Fischer, S.R.

    1998-11-01

    This study was conducted at the request of the USDOE/AL Dynamic Balancer Project Team to develop a set of representative accident sequences initiated by rapid seizure of the spindle shaft of the Schenck dynamic balancing machine used in the mass properties testing activities in Bay 12-60 at the Pantex Plant. This Balancer is used for balancing reentry vehicles. In addition, the study identified potential causes of possible spindle-shaft seizure leading to a rapid deceleration of the rotating assembly. These accident sequences extend to the point that the reentry vehicle either remains in stable condition on the balancing machine or leaves the machine with some translational and rotational motion. Fault-tree analysis was used to identify possible causes of spindle-shaft seizure, and failure modes and effects analysis identified the results of shearing of different machine components. Cause-consequence diagrams were used to help develop accident sequences resulting from the possible effects of spindle-shaft seizure. To make these accident sequences physically reasonable, the analysts used idealized models of the dynamics of rotating masses. Idealized physical modeling also was used to provide approximate values of accident parameters that lead to branching down different accident progression paths. The exacerbating conditions of balancing machine over-speed and improper assembly of the fixture to the face plate are also addressed.

  20. Spindle Thermal Error Optimization Modeling of a Five-axis Machine Tool

    Science.gov (United States)

    Guo, Qianjian; Fan, Shuo; Xu, Rufeng; Cheng, Xiang; Zhao, Guoyong; Yang, Jianguo

    2017-03-01

    Aiming at the problem of low machining accuracy and uncontrollable thermal errors of NC machine tools, spindle thermal error measurement, modeling and compensation of a two turntable five-axis machine tool are researched. Measurement experiment of heat sources and thermal errors are carried out, and GRA(grey relational analysis) method is introduced into the selection of temperature variables used for thermal error modeling. In order to analyze the influence of different heat sources on spindle thermal errors, an ANN (artificial neural network) model is presented, and ABC(artificial bee colony) algorithm is introduced to train the link weights of ANN, a new ABC-NN(Artificial bee colony-based neural network) modeling method is proposed and used in the prediction of spindle thermal errors. In order to test the prediction performance of ABC-NN model, an experiment system is developed, the prediction results of LSR (least squares regression), ANN and ABC-NN are compared with the measurement results of spindle thermal errors. Experiment results show that the prediction accuracy of ABC-NN model is higher than LSR and ANN, and the residual error is smaller than 3 μm, the new modeling method is feasible. The proposed research provides instruction to compensate thermal errors and improve machining accuracy of NC machine tools.

  1. Hydrothermal synthesis of NaEuF4 spindle-like nanocrystals

    Indian Academy of Sciences (India)

    Zhi-Jun Wang; Feng Tao; Wei-Li Cai; Lian-Zeng Yao; Xiao-Guang Li

    2011-12-01

    NaEuF4 spindle-like nanocrystals have been synthesized through a simple hydrothermal method. The nanocrystals were well crystallized and exhibited fine morphology, as indicated by X-ray diffraction, transmission electron microscope and selected area electron diffractometer. The luminescence properties of these NaEuF4 products were investigated.

  2. Design of a Micro Milling Setup with an Active Magnetic Bearing Spindle

    NARCIS (Netherlands)

    Kimman, M.H.

    2010-01-01

    This thesis describes the design of a micro milling setup with an active magnetic bearing spindle. Micro milling is the mechanical removal of material with sub millimeter tools. An active magnetic bearing typically consists of a set of magnetic actuators, a control loop and position sensors. Activ

  3. Spindle speed variation technique in turning operations: Modeling and real implementation

    Science.gov (United States)

    Urbikain, G.; Olvera, D.; de Lacalle, L. N. López; Elías-Zúñiga, A.

    2016-11-01

    Chatter is still one of the most challenging problems in machining vibrations. Researchers have focused their efforts to prevent, avoid or reduce chatter vibrations by introducing more accurate predictive physical methods. Among them, the techniques based on varying the rotational speed of the spindle (or SSV, Spindle Speed ​​Variation) have gained great relevance. However, several problems need to be addressed due to technical and practical reasons. On one hand, they can generate harmful overheating of the spindle especially at high speeds. On the other hand, the machine may be unable to perform the interpolation properly. Moreover, it is not trivial to select the most appropriate tuning parameters. This paper conducts a study of the real implementation of the SSV technique in turning systems. First, a stability model based on perturbation theory was developed for simulation purposes. Secondly, the procedure to realistically implement the technique in a conventional turning center was tested and developed. The balance between the improved stability margins and acceptable behavior of the spindle is ensured by energy consumption measurements. Mathematical model shows good agreement with experimental cutting tests.

  4. An evaluation of spindle-shaft seizure accident sequences for the Schenck Dynamic Balancer

    Energy Technology Data Exchange (ETDEWEB)

    Bott, T.F.; Fischer, S.R.

    1998-11-01

    This study was conducted at the request of the USDOE/AL Dynamic Balancer Project Team to develop a set of representative accident sequences initiated by rapid seizure of the spindle shaft of the Schenck dynamic balancing machine used in the mass properties testing activities in Bay 12-60 at the Pantex Plant. This Balancer is used for balancing reentry vehicles. In addition, the study identified potential causes of possible spindle-shaft seizure leading to a rapid deceleration of the rotating assembly. These accident sequences extend to the point that the reentry vehicle either remains in stable condition on the balancing machine or leaves the machine with some translational and rotational motion. Fault-tree analysis was used to identify possible causes of spindle-shaft seizure, and failure modes and effects analysis identified the results of shearing of different machine components. Cause-consequence diagrams were used to help develop accident sequences resulting from the possible effects of spindle-shaft seizure. To make these accident sequences physically reasonable, the analysts used idealized models of the dynamics of rotating masses. Idealized physical modeling also was used to provide approximate values of accident parameters that lead to branching down different accident progression paths. The exacerbating conditions of balancing machine over-speed and improper assembly of the fixture to the face plate are also addressed.

  5. Sleep spindle and slow wave frequency reflect motor skill performance in primary school-age children

    NARCIS (Netherlands)

    Astill, Rebecca G; Piantoni, Giovanni; Raymann, Roy J E M; Vis, Jose C; Coppens, Joris E; Walker, Matthew P; Stickgold, Robert; Van Der Werf, Ysbrand D; Van Someren, Eus J W

    2014-01-01

    Background and Aim: The role of sleep in the enhancement of motor skills has been studied extensively in adults. We aimed to determine involvement of sleep and characteristics of spindles and slow waves in a motor skill in children. Hypothesis: We hypothesized sleep-dependence of skill enhancement a

  6. Cytological characteristics and classification of spindle inhibitors according to their effects on segmentation mitoses.

    Science.gov (United States)

    Sentein, P; Ates, Y

    1978-01-01

    The effects of spindle inhibitors and of protein synthesis inhibitors on segmentation mitoses allow us to classify them into six groups : 1. Colchicine type : destruction of the whole achromatic apparatus and centrospheres without storing of dense bodies; 2. Quinoline type : same effect on the achromatic apparatus, but blocked centrospheres with accumulation of dense bodies; 3. Chloralhydrate type : Incomplete destruction of achromatic apparatus, spindle residue which maintains the chromosomes in a star shape, inactive centrospheres sequestered by the reticulum, but without accumulation of dense bodies; 4. Phenylurethane type : Incomplete and reversible action, which leads to easy production of pluripolar mitoses; 5. Carboxylic acid type : dissociation of the spindle, sometimes with blocking of the centrosphere, together with profound chromosome changes without primitive breaks; the intensity and quality of their action is related to the number of carbon atoms in the acid considered; 6. Protein synthesis inhibitor type : (cycloheximide, pederin) characterized by a stop of the nuclear cycle at telo-prophase when the action is sufficient, chromosome abnormalities, sometimes, reduced to strings of beads, and freeing of asters; at weaker concentrations mitosis is possible, but the congression of chromosomes at the equator is abnormal because of functional disturbance of the kinetochores. The nature and grading of these effects, their association (or non - association) to chromosome damage, the soundness of the spindle when only the chromosomes are affected (nitrogen mustard) make this one of the tests which gives the most specific data about the action of antimitotic substances.

  7. Computer simulations predict that chromosome movements and rotations accelerate mitotic spindle assembly without compromising accuracy.

    Science.gov (United States)

    Paul, Raja; Wollman, Roy; Silkworth, William T; Nardi, Isaac K; Cimini, Daniela; Mogilner, Alex

    2009-09-15

    The mitotic spindle self-assembles in prometaphase by a combination of centrosomal pathway, in which dynamically unstable microtubules search in space until chromosomes are captured, and a chromosomal pathway, in which microtubules grow from chromosomes and focus to the spindle poles. Quantitative mechanistic understanding of how spindle assembly can be both fast and accurate is lacking. Specifically, it is unclear how, if at all, chromosome movements and combining the centrosomal and chromosomal pathways affect the assembly speed and accuracy. We used computer simulations and high-resolution microscopy to test plausible pathways of spindle assembly in realistic geometry. Our results suggest that an optimal combination of centrosomal and chromosomal pathways, spatially biased microtubule growth, and chromosome movements and rotations is needed to complete prometaphase in 10-20 min while keeping erroneous merotelic attachments down to a few percent. The simulations also provide kinetic constraints for alternative error correction mechanisms, shed light on the dual role of chromosome arm volume, and compare well with experimental data for bipolar and multipolar HT-29 colorectal cancer cells.

  8. AIRE is a critical spindle-associated protein in embryonic stem cells.

    Science.gov (United States)

    Gu, Bin; Lambert, Jean-Philippe; Cockburn, Katie; Gingras, Anne-Claude; Rossant, Janet

    2017-07-25

    Embryonic stem (ES) cells go though embryo-like cell cycles regulated by specialized molecular mechanisms. However, it is not known whether there are ES cell-specific mechanisms regulating mitotic fidelity. Here we showed that Autoimmune Regulator (Aire), a transcription coordinator involved in immune tolerance processes, is a critical spindle-associated protein in mouse ES(mES) cells. BioID analysis showed that AIRE associates with spindle-associated proteins in mES cells. Loss of function analysis revealed that Aire was important for centrosome number regulation and spindle pole integrity specifically in mES cells. We also identified the c-terminal LESLL motif as a critical motif for AIRE's mitotic function. Combined maternal and zygotic knockout further revealed Aire's critical functions for spindle assembly in preimplantation embryos. These results uncovered a previously unappreciated function for Aire and provide new insights into the biology of stem cell proliferation and potential new angles to understand fertility defects in humans carrying Aire mutations.

  9. Evidence that Aurora B is implicated in spindle checkpoint signalling independently of error correction.

    Science.gov (United States)

    Santaguida, Stefano; Vernieri, Claudio; Villa, Fabrizio; Ciliberto, Andrea; Musacchio, Andrea

    2011-04-20

    Fidelity of chromosome segregation is ensured by a tension-dependent error correction system that prevents stabilization of incorrect chromosome-microtubule attachments. Unattached or incorrectly attached chromosomes also activate the spindle assembly checkpoint, thus delaying mitotic exit until all chromosomes are bioriented. The Aurora B kinase is widely recognized as a component of error correction. Conversely, its role in the checkpoint is controversial. Here, we report an analysis of the role of Aurora B in the spindle checkpoint under conditions believed to uncouple the effects of Aurora B inhibition on the checkpoint from those on error correction. Partial inhibition of several checkpoint and kinetochore components, including Mps1 and Ndc80, strongly synergizes with inhibition of Aurora B activity and dramatically affects the ability of cells to arrest in mitosis in the presence of spindle poisons. Thus, Aurora B might contribute to spindle checkpoint signalling independently of error correction. Our results support a model in which Aurora B is at the apex of a signalling pyramid whose sensory apparatus promotes the concomitant activation of error correction and checkpoint signalling pathways.

  10. Cdc20 and Cks direct the spindle checkpoint-independent destruction of cyclin A

    NARCIS (Netherlands)

    Wolthuis, Rob; Clay-Farrace, Lori; van Zon, Wouter; Yekezare, Mona; Koop, Lars; Ogink, Janneke; Medema, Rene; Pines, Jonathon

    2008-01-01

    Successful mitosis requires the right protein be degraded at the right time. Central to this is the spindle checkpoint that prevents the destruction of securin and cyclin 131 when there are improperly attached chromosomes. The principal target of the checkpoint is Cdc20, which activates the anaphase

  11. No Reduction of Spindle Neuron Number in Frontoinsular Cortex in Autism

    Science.gov (United States)

    Kennedy, Daniel P.; Semendeferi, Katerina; Courchesne, Eric

    2007-01-01

    It has been suggested that spindle neurons, an evolutionarily unique type of neuron, might be involved in higher-order social, emotional, and cognitive functions. As such, it was hypothesized that these neurons may be particularly important to the pathophysiology of autism, a disease characterized in part by disruption of higher-order social and…

  12. Widespread reduction in sleep spindle activity in socially anxious children and adolescents.

    Science.gov (United States)

    Wilhelm, Ines; Groch, Sabine; Preiss, Andrea; Walitza, Susanne; Huber, Reto

    2017-05-01

    Social anxiety disorder (SAD) is one of the most prevalent psychiatric diseases typically emerging during childhood and adolescence. Biological vulnerabilities such as a protracted maturation of prefrontal cortex functioning together with heightened reactivity of the limbic system leading to increased emotional reactivity are discussed as factors contributing to the emergence and maintenance of SAD. Sleep slow wave activity (SWA, 0.75-4.5 Hz) and sleep spindle activity (9-16 Hz) reflect processes of brain maturation and emotion regulation. We used high-density electroencephalography to characterize sleep SWA and spindle activity and their relationship to emotional reactivity in children and adolescents suffering from SAD and healthy controls (HC). Subjectively rated arousal was assessed using an emotional picture-word association task. SWA did not differ between socially anxious and healthy participants. We found a widespread reduction in fast spindle activity (13-16 Hz) in SAD patients compared to HC. SAD patients rated negative stimuli to be more arousing and these arousal ratings were negatively correlated with fast spindle activity. These results suggest electrophysiological alterations that are evident at an early stage of psychopathology and that are closely linked to one core symptom of anxiety disorders such as increased emotional reactivity. The role of disturbed GABAergic neurotransmission is discussed as an underlying factor.

  13. Pacemaker activity in a sensory ending with multiple encoding sites : The cat muscle spindle primary ending

    NARCIS (Netherlands)

    Banks, RW; Hulliger, M; Scheepstra, KA; Otten, E

    1997-01-01

    1. A combined physiological, histological and computer modelling study was carried out on muscle spindles of the cat tenuissimus muscle to examine whether there was any correlation between the functional interaction of putative encoding sites, operated separately by static and dynamic fusimotor neur

  14. MAP kinase meets mitosis: A role for Raf Kinase Inhibitory Protein in spindle checkpoint regulation

    Directory of Open Access Journals (Sweden)

    Rosner Marsha

    2007-01-01

    Full Text Available Abstract Raf Kinase Inhibitory Protein (RKIP is an evolutionarily conserved protein that functions as a modulator of signaling by the MAP kinase cascade. Implicated as a metastasis suppressor, Raf Kinase Inhibitory Protein depletion correlates with poor prognosis for breast, prostate and melanoma tumors but the mechanism is unknown. Recent evidence indicates that Raf Kinase Inhibitory Protein regulates the mitotic spindle assembly checkpoint by controlling Aurora B Kinase activity, and the mechanism involves Raf/MEK/ERK signaling. In contrast to elevated MAP kinase signaling during the G1, S or G2 phases of the cell cycle that activates checkpoints and induces arrest or senescence, loss of RKIP during M phase leads to bypass of the spindle assembly checkpoint and the generation of chromosomal abnormalities. These results reveal a role for Raf Kinase Inhibitory Protein and the MAP kinase cascade in ensuring the fidelity of chromosome segregation prior to cell division. Furthermore, these data highlight the need for precise titration of the MAP kinase signal to ensure the integrity of the spindle assembly process and provide a mechanism for generating genomic instability in tumors. Finally, these results raise the possibility that RKIP status in tumors could influence the efficacy of treatments such as poisons that stimulate the Aurora B-dependent spindle assembly checkpoint.

  15. Spindle checkpoint-independent inhibition of mitotic chromosome segregation by Drosophila Mps1.

    Science.gov (United States)

    Althoff, Friederike; Karess, Roger E; Lehner, Christian F

    2012-06-01

    Monopolar spindle 1 (Mps1) is essential for the spindle assembly checkpoint (SAC), which prevents anaphase onset in the presence of misaligned chromosomes. Moreover, Mps1 kinase contributes in a SAC-independent manner to the correction of erroneous initial attachments of chromosomes to the spindle. Our characterization of the Drosophila homologue reveals yet another SAC-independent role. As in yeast, modest overexpression of Drosophila Mps1 is sufficient to delay progression through mitosis during metaphase, even though chromosome congression and metaphase alignment do not appear to be affected. This delay in metaphase depends on the SAC component Mad2. Although Mps1 overexpression in mad2 mutants no longer causes a metaphase delay, it perturbs anaphase. Sister kinetochores barely move apart toward spindle poles. However, kinetochore movements can be restored experimentally by separase-independent resolution of sister chromatid cohesion. We propose therefore that Mps1 inhibits sister chromatid separation in a SAC-independent manner. Moreover, we report unexpected results concerning the requirement of Mps1 dimerization and kinase activity for its kinetochore localization in Drosophila. These findings further expand Mps1's significance for faithful mitotic chromosome segregation and emphasize the importance of its careful regulation.

  16. Stable MCC binding to the APC/C is required for a functional spindle assembly checkpoint

    DEFF Research Database (Denmark)

    Hein, Jamin B; Nilsson, Jakob

    2014-01-01

    The spindle assembly checkpoint (SAC) delays progression into anaphase until all chromosomes have aligned on the metaphase plate by inhibiting Cdc20, the mitotic co-activator of the APC/C. Mad2 and BubR1 bind and inhibit Cdc20, thereby forming the mitotic checkpoint complex (MCC), which can bind...

  17. Cdc20 and Cks direct the spindle checkpoint-independent destruction of cyclin A

    NARCIS (Netherlands)

    Wolthuis, Rob; Clay-Farrace, Lori; van Zon, Wouter; Yekezare, Mona; Koop, Lars; Ogink, Janneke; Medema, Rene; Pines, Jonathon

    2008-01-01

    Successful mitosis requires the right protein be degraded at the right time. Central to this is the spindle checkpoint that prevents the destruction of securin and cyclin 131 when there are improperly attached chromosomes. The principal target of the checkpoint is Cdc20, which activates the

  18. Spindle orientation bias in gut epithelial stem cell compartments is lost in precancerous tissue

    NARCIS (Netherlands)

    Quyn, A.J.; Appleton, P.L.; Carey, F.A.; Steele, R.J.; Barker, N.; Clevers, H.; Ridgway, R.A.; Sansom, O.J.; Nathke, I.S.

    2010-01-01

    The importance of asymmetric divisions for stem cell function and maintenance is well established in the developing nervous system and the skin; however, its role in gut epithelium and its importance for tumorigenesis is still debated. We demonstrate alignment of mitotic spindles perpendicular to th

  19. Fabrication and characteristics of spindle Fe2O3@Au core/shell particles

    Institute of Scientific and Technical Information of China (English)

    SHEN Hong-xia; YAO Jian-lin; GU Ren-ao

    2009-01-01

    The fabrication and characteristics of spindle Fe2O3@Au core/shell particle were investigated, and the effect of the core/shell nanoparticles as the surface enhanced Raman spectroscopy (SERS)-active substrates was studied. By using the seed-catalyzed reduction technique, anisotropic Fe2O3@Au core/shell particles with spindle morphology were successfully prepared. The Fe2O3 particles with spindle morphology were initially prepared as original cores. The Au nanoparticles of 2 nm were attached onto the Fe2O3 particles through organosilane molecules. Uniform Au shell formed onto Fe2O3 core modified by Au nanoparticles through the in-situ reduction of HAuCl4. The shell thickness was controlled through regulating the concentration of HAuCl4 solution. The results of TEM, XRD and UV-vis characterization show that the core/shell particles with the original shape of the Fe2O3 particles are obtained and these surfaces are covered by Au shell completely. The surface enhanced Raman spectrum of the probe molecules adsorbed on these core/shell substrates is strong and the intensity is enhanced with the increase of the thickness of Au shell or the aspect ratio of particles. The spindle Fe2O3@Au core/shell particles exhibit optimum (SERS) activity.

  20. Design and static performance of high speed machining centre with "direct drive"

    Institute of Scientific and Technical Information of China (English)

    Shuhong XIAO; Yulian CHEN; Guangyuan ZHENG

    2009-01-01

    "Direct drive" is an ideal method for speeding machine tools. In the structure of a CNC machining centre with "direct drive", the linear motor's primary and secondary parts are assembled into the worktable and machine bed respectively to directly drive the worktable. The built-in rotary motor is assembled in the spindle to realize the main transmission system of the machine tool "direct drive". All mechanical transmission elements in machine tools are eliminated. High speed, efficiency, and accuracy are easily obtained. However, in this type of "direct drive" machining centre, the magnetic attraction force between the primary and the secondary linear motors and the dynamic impact at acceleration and deceleration are directly imposed on the machine tool, and influence the performance of the machining centre. This paper analyzes the special demands of "direct drive" on the machine centre, and introduces a new structure of the machining tool. The worktable and machine bed are optimized to meet the special demands of "direct drive". Static performance simulation on the machining centre is done to reveal an ideal result.

  1. Survivin exists in immunochemically distinct subcellular pools and is involved in spindle microtubule function.

    Science.gov (United States)

    Fortugno, Paola; Wall, Nathan R; Giodini, Alessandra; O'Connor, Daniel S; Plescia, Janet; Padgett, Karen M; Tognin, Simona; Marchisio, Pier Carlo; Altieri, Dario C

    2002-02-01

    Survivin is a member of the inhibitor of apoptosis gene family that has been implicated in both apoptosis inhibition and regulation of mitosis. However, the subcellular distribution of survivin has been controversial and variously described as a microtubule-associated protein or chromosomal passenger protein. Here, we show that antibodies directed to the survivin sequence Ala(3)-Ile(19) exclusively recognized a nuclear pool of survivin that segregated with nucleoplasmic proteins, but not with outer nuclear matrix or nuclear matrix proteins. By immunofluorescence, nuclear survivin localized to kinetochores of metaphase chromosomes, and to the central spindle midzone at anaphase. However, antibodies to Cys(57)-Trp(67) identified a cytosolic pool of survivin, which associated with interphase microtubules, centrosomes, spindle poles and mitotic spindle microtubules at metaphase and anaphase. Polyclonal antibodies recognizing survivin epitopes Ala(3)-Ile(19), Met(38)-Thr(48), Pro(47)-Phe(58) and Cys(57)-Trp(67) identified both survivin pools within the same mitotic cell. A ratio of approximately 1:6 for nuclear versus cytosolic survivin was obtained by quantitative subcellular fractionation. In synchronized cultures, cytosolic survivin abruptly increased at mitosis, physically associated with p34(cdc2), and was phosphorylated by p34(cdc2) on Thr(34), in vivo. By contrast, nuclear survivin began to accumulate in S phase, was not complexed with p34(cdc2) and was not phosphorylated on Thr(34). Intracellular loading of a polyclonal antibody to survivin caused microtubule defects and resulted in formation of multipolar mitotic spindles, but did not interfere with cytokinesis. These data demonstrate that although both reported localizations of survivin exist in mitotic cells, the preponderant survivin pool is associated with microtubules and participates in the assembly of a bipolar mitotic spindle.

  2. RNA- binding protein Stau2 is important for spindle integrity and meiosis progression in mouse oocytes.

    Science.gov (United States)

    Cao, Yan; Du, Juan; Chen, Dandan; Wang, Qian; Zhang, Nana; Liu, Xiaoyun; Liu, Xiaoyu; Weng, Jing; Liang, Yuanjing; Ma, Wei

    2016-10-01

    Staufen2 (Stau2) is a double-stranded RNA-binding protein involved in cell fate decision by regulating mRNA transport, mRNA stability, translation, and ribonucleoprotein assembly. Little is known about Stau2 expression and function in mammalian oocytes during meiosis. Herein we report the sub-cellular distribution and function of Stau2 in mouse oocyte meiosis. Western blot analysis revealed high and stable expression of Stau2 in oocytes from germinal vesicle (GV) to metaphase II (MII). Immunofluorescence showed that Stau2 was evenly distributed in oocytes at GV stage, and assembled as filaments after germinal vesicle breakdown (GVBD), particularly, colocalized with spindle at MI and MII. Stau2 was disassembled when microtubules were disrupted with nocodazole, on the other hand, when MTs were stabilized with taxol, Stau2 was not colocalized with the stabilized microtubules, but aggregated around the chromosomes array, indicating Stau2 assembly and colocalization with microtubules require both microtubule integrity and its normal dynamics. During interphase and mitosis of BHK and MEF cells, Stau2 was not distributed on microtubules, but colocalized with cis-Golgi marker GM130, implying its association with Golgi complex but not the spindle in fully differentiated somatic cells. Specific morpholino oligo-mediated Stau2 knockdown disrupted spindle formation, chromosome alignment and microtubule-kinetochore attachment in oocytes. The majority oocytes were arrested at MI stage, with bright MAD1 at kinetochores, indicating activation of spindle assembly checkpoint (SAC). Some oocytes were stranded at telophase I (TI), implying suppressed first polar body extrution. Together these data demonstrate that Stau2 is required for spindle formation and timely meiotic progression in mouse oocytes.

  3. Experimental Analysis and Full Prediction Model of a 5-DOF Motorized Spindle

    Directory of Open Access Journals (Sweden)

    Weiyu Zhang

    2017-01-01

    Full Text Available The cost and power consumption of DC power amplifiers are much greater than that of AC power converters. Compared to a motorized spindle supported with DC magnetic bearings, a motorized spindle supported with AC magnetic bearings is inexpensive and more efficient. This paper studies a five-degrees-of-freedom (5-DOF motorized spindle supported with AC hybrid magnetic bearings (HMBs. Most models of suspension forces, except a “switching model”, are quite accurate, but only in a particular operating area and not in regional coverage. If a “switching model” is applied to a 5-DOF motorized spindle, the real-time performance of the control system can be significantly decreased due to the large amount of data processing for both displacement and current. In order to solve this defect, experiments based on the “switching model” are performed, and the resulting data are analyzed. Using the data analysis results, a “full prediction model” based on the operating state is proposed to improve real-time performance and precision. Finally, comparative, verification and stiffness tests are conducted to verify the improvement of the proposed model. Results of the tests indicate that the rotor has excellent characteristics, such as good real-time performance, superior anti-interference performance with load and the accuracy of the model in full zone. The satisfactory experimental results demonstrate the effectiveness of the “full prediction model” applied to the control system under different operating stages. Therefore, the results of the experimental analysis and the proposed full prediction model can provide a control system of a 5-DOF motorized spindle with the most suitable mathematical models of the suspension force.

  4. Sustained spindle-assembly checkpoint response requires de novo transcription and translation of cyclin B1.

    Directory of Open Access Journals (Sweden)

    Ana Lúcia Mena

    Full Text Available BACKGROUND: Microtubule-targeting drugs induce mitotic delay at pro-metaphase by preventing the spindle assembly checkpoint to be satisfied. However, especially after prolonged treatments, cells can escape this arrest in a process called mitotic slippage. The mechanisms underlying the spindle assembly checkpoint and slippage are not fully understood. It has been generally accepted that during mitosis there is a temporary shutdown of high-energy-consuming processes, such as transcription and translation. However, the synthesis of specific proteins is maintained or up-regulated since protein synthesis is necessary for entry into and progression through mitosis. METHODOLOGY/PRINCIPAL FINDINGS: In this work we investigated whether the mitotic arrest caused by the mitotic checkpoint is independent of transcription and translation. By using immunofluorescent microscopy and western blotting, we demonstrate that inhibition of either of these processes induces a shortening of the mitotic arrest caused by the nocodazole treatment, and ultimately leads to mitotic slippage. Our western blotting and RTQ-PCR results show that inhibition of transcription during mitotic arrest does not affect the expression of the spindle checkpoint proteins, whereas it induces a significant decrease in the mRNA and protein levels of Cyclin B1. The exogenous expression of Cyclin B1 substantially rescued the mitotic phenotype in nocodazole cells treated with the inhibitors of transcription and translation. CONCLUSIONS/SIGNIFICANCE: This work emphasizes the importance of transcription and translation for the maintenance of the spindle assembly checkpoint, suggesting the existence of a mechanism dependent on cyclin B1 gene regulation during mitosis. We propose that continuous transcription of mitotic regulators is required to sustain the activation of the spindle assembly checkpoint.

  5. Combining time-frequency and spatial information for the detection of sleep spindles

    Directory of Open Access Journals (Sweden)

    Christian eO'Reilly

    2015-02-01

    Full Text Available EEG sleep spindles are short (0.5-2.0 s bursts of activity in the 11-16 Hz band occurring during non-rapid eye movement (NREM sleep. This sporadic activity is thought to play a role in memory consolidation, brain plasticity, and protection of sleep integrity. Many automatic detectors have been proposed to assist or replace experts for sleep spindle scoring. However, these algorithms usually detect too many events making it difficult to achieve a good tradeoff between sensitivity (Se and false detection rate (FDr. In this work, we propose a semi-automatic detector comprising a sensitivity phase based on well-established criteria followed by a specificity phase using spatial and spectral criteria.In the sensitivity phase, selected events are those which amplitude in the 10 – 16 Hz band and spectral ratio characteristics both reject a null hypothesis (p <0.1 stating that the considered event is not a spindle. This null hypothesis is constructed from events occurring during rapid eye movement (REM sleep epochs. In the specificity phase, a hierarchical clustering of the selected candidates is done based on events’ frequency and spatial position along the anterior-posterior axis. Only events from the classes grouping most (at least 80% spindles scored by an expert are kept. We obtain Se = 93.2% and FDr = 93.0% in the first phase and Se = 85.4% and FDr = 86.2% in the second phase. For these two phases, Matthew’s correlation coefficients are respectively 0.228 and 0.324. Results suggest that spindles are defined by specific spatio-spectral properties and that automatic detection methods can be improved by considering these features.

  6. Driving anger in Malaysia.

    Science.gov (United States)

    Sullman, Mark J M; Stephens, Amanda N; Yong, Michelle

    2014-10-01

    The present study examined the types of situations that cause Malaysian drivers to become angry. The 33-item version of the driver anger scale (Deffenbacher et al., 1994) was used to investigate driver anger amongst a sample of 339 drivers. Confirmatory factor analysis showed that the fit of the original six-factor model (discourtesy, traffic obstructions, hostile gestures, slow driving, illegal driving and police presence), after removing one item and allowing three error pairs to covary, was satisfactory. Female drivers reported more anger, than males, caused by traffic obstruction and hostile gestures. Age was also negatively related to five (discourtesy, traffic obstructions, hostile gestures, slow driving and police presence) of the six factors and also to the total DAS score. Furthermore, although they were not directly related to crash involvement, several of the six forms of driving anger were significantly related to the crash-related conditions of: near misses, loss of concentration, having lost control of a vehicle and being ticketed. Overall the pattern of findings made in the present research were broadly similar to those from Western countries, indicating that the DAS is a valid measure of driving anger even among non-European based cultures.

  7. THE ROLE OF NUCLEUS RAPHE MAGNUS IN THE ANTINOCICEPTIVE EFFECT OF MUSCLE SPINDLE AFFERENTS IN THE RAT

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To investigate the role of NRM in the antinociceptive effect of muscle spindle afferents, the influence of NRM lesion on the inhibitory effect of muscle spindle afferents on the nociceptive responses of wide dynamic range (WDR) neurons and the effects of the muscle spindle afferents on the NRM neuronal activities were observed. Methods The single units of WDR neurons in the spinal dorsal horn were recorded extracellularly, and the inhibitory effects of activating muscle spindle afferents by intravenous administration of succinyicholine (SCH) on the C-fibers evoked responses (C-responses) of WDR neurons were tested before and after lesion of NRM. The ef- fects of the muscle spindle afferents activated by administrating SCH on the single NRM neurons were also examined. Results ①lt was found that the C-responses of WDR neurons were significantly inhibited by intravenously adminis- tration of SCH, and the inhibitory effect was reduced after lesion of NRM ;②The activities of most of the NRM neu- rons could be changed significantly by administrating SCH. According to their responses, NRM neurons could be classified into three types:excitatory, inhibitory and non-responsive neurons, and the responses were dose-depen- dent. Conclusion These results suggest that the muscle spindle afferents evoked by SCH may activate the NRM neu- rons, which plays an important role in the antinociception of muscle spindle afferents.

  8. Formin-mediated actin polymerization cooperates with Mushroom body defect (Mud)-Dynein during Frizzled-Dishevelled spindle orientation.

    Science.gov (United States)

    Johnston, Christopher A; Manning, Laurina; Lu, Michelle S; Golub, Ognjen; Doe, Chris Q; Prehoda, Kenneth E

    2013-10-01

    To position the mitotic spindle, cytoskeletal components must be coordinated to generate cortical forces on astral microtubules. Although the dynein motor is common to many spindle orientation systems, 'accessory pathways' are often also required. In this work, we identified an accessory spindle orientation pathway in Drosophila that functions with Dynein during planar cell polarity, downstream of the Frizzled (Fz) effector Dishevelled (Dsh). Dsh contains a PDZ ligand and a Dynein-recruiting DEP domain that are both required for spindle orientation. The Dsh PDZ ligand recruits Canoe/Afadin and ultimately leads to Rho GTPase signaling mediated through RhoGEF2. The formin Diaphanous (Dia) functions as the Rho effector in this pathway, inducing F-actin enrichment at sites of cortical Dsh. Chimeric protein experiments show that the Dia-actin accessory pathway can be replaced by an independent kinesin (Khc73) accessory pathway for Dsh-mediated spindle orientation. Our results define two 'modular' spindle orientation pathways and show an essential role for actin regulation in Dsh-mediated spindle orientation.

  9. KLP-7 acts through the Ndc80 complex to limit pole number in C. elegans oocyte meiotic spindle assembly.

    Science.gov (United States)

    Connolly, Amy A; Sugioka, Kenji; Chuang, Chien-Hui; Lowry, Joshua B; Bowerman, Bruce

    2015-09-14

    During oocyte meiotic cell division in many animals, bipolar spindles assemble in the absence of centrosomes, but the mechanisms that restrict pole assembly to a bipolar state are unknown. We show that KLP-7, the single mitotic centromere-associated kinesin (MCAK)/kinesin-13 in Caenorhabditis elegans, is required for bipolar oocyte meiotic spindle assembly. In klp-7(-) mutants, extra microtubules accumulated, extra functional spindle poles assembled, and chromosomes frequently segregated as three distinct masses during meiosis I anaphase. Moreover, reducing KLP-7 function in monopolar klp-18(-) mutants often restored spindle bipolarity and chromosome segregation. MCAKs act at kinetochores to correct improper kinetochore-microtubule (k-MT) attachments, and depletion of the Ndc-80 kinetochore complex, which binds microtubules to mediate kinetochore attachment, restored bipolarity in klp-7(-) mutant oocytes. We propose a model in which KLP-7/MCAK regulates k-MT attachment and spindle tension to promote the coalescence of early spindle pole foci that produces a bipolar structure during the acentrosomal process of oocyte meiotic spindle assembly.

  10. MAPK-activated protein kinase 2 is required for mouse meiotic spindle assembly and kinetochore-microtubule attachment.

    Directory of Open Access Journals (Sweden)

    Ju Yuan

    Full Text Available MAPK-activated protein kinase 2 (MK2, a direct substrate of p38 MAPK, plays key roles in multiple physiological functions in mitosis. Here, we show for the first time the unique distribution pattern of MK2 in meiosis. Phospho-MK2 was localized on bipolar spindle minus ends and along the interstitial axes of homologous chromosomes extending over centromere regions and arm regions at metaphase of first meiosis (MI stage in mouse oocytes. At metaphase of second meiosis (MII stage, p-MK2 was localized on the bipolar spindle minus ends and at the inner centromere region of sister chromatids as dots. Knockdown or inhibition of MK2 resulted in spindle defects. Spindles were surrounded by irregular nondisjunction chromosomes, which were arranged in an amphitelic or syntelic/monotelic manner, or chromosomes detached from the spindles. Kinetochore-microtubule attachments were impaired in MK2-deficient oocytes because spindle microtubules became unstable in response to cold treatment. In addition, homologous chromosome segregation and meiosis progression were inhibited in these oocytes. Our data suggest that MK2 may be essential for functional meiotic bipolar spindle formation, chromosome segregation and proper kinetochore-microtubule attachments.

  11. The function of the sleep spindle: a physiological index of intelligence and a mechanism for sleep-dependent memory consolidation.

    Science.gov (United States)

    Fogel, Stuart M; Smith, Carlyle T

    2011-04-01

    Until recently, the electrophysiological mechanisms involved in strengthening new memories into a more permanent form during sleep have been largely unknown. The sleep spindle is an event in the electroencephalogram (EEG) characterizing Stage 2 sleep. Sleep spindles may reflect, at the electrophysiological level, an ideal mechanism for inducing long-term synaptic changes in the neocortex. Recent evidence suggests the spindle is highly correlated with tests of intellectual ability (e.g.; IQ tests) and may serve as a physiological index of intelligence. Further, spindles increase in number and duration in sleep following new learning and are correlated with performance improvements. Spindle density and sigma (14-16Hz) spectral power have been found to be positively correlated with performance following a daytime nap, and animal studies suggest the spindle is involved in a hippocampal-neocortical dialogue necessary for memory consolidation. The findings reviewed here collectively provide a compelling body of evidence that the function of the sleep spindle is related to intellectual ability and memory consolidation.

  12. U.S. DRIVE

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-03-16

    U.S. DRIVE, which stands for United States Driving Research and Innovation for Vehicle efficiency and Energy sustainability, is an expanded government-industry partnership among the U.S. Department of Energy; USCAR, representing Chrysler Group LLC, Ford Motor Company and General Motors; Tesla Motors; five energy companies – BP America, Chevron Corporation, ConocoPhillips, ExxonMobil Corporation, and Shell Oil Products US; two utilities – Southern California Edison and Michigan-based DTE Energy; and the Electric Power Research Institute (EPRI). The U.S. DRIVE mission is to accelerate the development of pre-competitive and innovative technologies to enable a full range of affordable and clean advanced light-duty vehicles, as well as related energy infrastructure.

  13. Differential spike timing and phase dynamics of reticular thalamic and prefrontal cortical neuronal populations during sleep spindles.

    Science.gov (United States)

    Gardner, Richard J; Hughes, Stuart W; Jones, Matthew W

    2013-11-20

    The 8-15 Hz thalamocortical oscillations known as sleep spindles are a universal feature of mammalian non-REM sleep, during which they are presumed to shape activity-dependent plasticity in neocortical networks. The cortex is hypothesized to contribute to initiation and termination of spindles, but the mechanisms by which it implements these roles are unknown. We used dual-site local field potential and multiple single-unit recordings in the thalamic reticular nucleus (TRN) and medial prefrontal cortex (mPFC) of freely behaving rats at rest to investigate thalamocortical network dynamics during natural sleep spindles. During each spindle epoch, oscillatory activity in mPFC and TRN increased in frequency from onset to offset, accompanied by a consistent phase precession of TRN spike times relative to the cortical oscillation. In mPFC, the firing probability of putative pyramidal cells was highest at spindle initiation and termination times. We thus identified "early" and "late" cell subpopulations and found that they had distinct properties: early cells generally fired in synchrony with TRN spikes, whereas late cells fired in antiphase to TRN activity and also had higher firing rates than early cells. The accelerating and highly structured temporal pattern of thalamocortical network activity over the course of spindles therefore reflects the engagement of distinct subnetworks at specific times across spindle epochs. We propose that early cortical cells serve a synchronizing role in the initiation and propagation of spindle activity, whereas the subsequent recruitment of late cells actively antagonizes the thalamic spindle generator by providing asynchronous feedback.

  14. The Mitotic Spindle in the One-Cell C. elegans Embryo Is Positioned with High Precision and Stability

    Science.gov (United States)

    Pécréaux, Jacques; Redemann, Stefanie; Alayan, Zahraa; Mercat, Benjamin; Pastezeur, Sylvain; Garzon-Coral, Carlos; Hyman, Anthony A.; Howard, Jonathon

    2016-10-01

    Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early C. elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution. We found that the precision is remarkably high: the cell-to-cell variation in the transverse position of the center of the spindle during metaphase, as measured by the standard deviation, was only 1.5% of the length of the short axis of the cell. Spindle position is also very stable: the standard deviation of the fluctuations in transverse spindle position during metaphase was only 0.5% of the short axis of the cell. Assuming that stability is limited by fluctuations in the number of independent motor elements such as microtubules or dyneins underlying the centering machinery, we infer that the number is on the order of one thousand, consistent with the several thousand of astral microtubules in these cells. Astral microtubules grow out from the two spindle poles, make contact with the cell cortex, and then shrink back shortly thereafter. The high stability of centering can be accounted for quantitatively if, while making contact with the cortex, the astral microtubules buckle as they exert compressive, pushing forces. We thus propose that the large number of microtubules in the asters provides a highly precise mechanism for positioning the spindle during metaphase while assembly is completed prior to the onset of anaphase.

  15. Toyota hybrid synergy drive

    Energy Technology Data Exchange (ETDEWEB)

    Gautschi, H.

    2008-07-01

    This presentation made at the Swiss 2008 research conference on traffic by Hannes Gautschi, director of service and training at the Toyota company in Switzerland, takes a look at Toyota's hybrid drive vehicles. The construction of the vehicles and their combined combustion engines and electric generators and drives is presented and the combined operation of these components is described. Braking and energy recovery are discussed. Figures on the performance, fuel consumption and CO{sub 2} output of the hybrid vehicles are compared with those of conventional vehicles.

  16. Toyota hybrid synergy drive

    Energy Technology Data Exchange (ETDEWEB)

    Gautschi, H.

    2008-07-01

    This presentation made at the Swiss 2008 research conference on traffic by Hannes Gautschi, director of service and training at the Toyota company in Switzerland, takes a look at Toyota's hybrid drive vehicles. The construction of the vehicles and their combined combustion engines and electric generators and drives is presented and the combined operation of these components is described. Braking and energy recovery are discussed. Figures on the performance, fuel consumption and CO{sub 2} output of the hybrid vehicles are compared with those of conventional vehicles.

  17. Pulsation driving and convection

    Science.gov (United States)

    Antoci, Victoria

    2015-08-01

    Convection in stellar envelopes affects not only the stellar structure, but has a strong impact on different astrophysical processes, such as dynamo-generated magnetic fields, stellar activity and transport of angular momentum. Solar and stellar observations from ground and space have shown that the turbulent convective motion can also drive global oscillations in many type of stars, allowing to study stellar interiors at different evolutionary stages. In this talk I will concentrate on the influence of convection on the driving of stochastic and coherent pulsations across the Hertzsprung-Russell diagram and give an overview of recent studies.

  18. Gears and gear drives

    CERN Document Server

    Jelaska, Damir T

    2012-01-01

    Understanding how gears are formed and how they interact or 'mesh' with each other is essential when designing equipment that uses gears or gear trains. The way in which gear teeth are formed and how they mesh is determined by their geometry and kinematics, which is the topic of this book.  Gears and Gear Drives provides the reader with comprehensive coverage of gears and gear drives. Spur, helical, bevel, worm and planetary gears are all covered, with consideration given to their classification, geometry, kinematics, accuracy control, load capacity and manufacturing. Cylindric

  19. Microlinear piezo drive experiments

    Science.gov (United States)

    Azin, A. V.; Bogdanov, E. P.; Rikkonen, S. V.; Ponomarev, S. V.; Khramtsov, A. M.

    2017-02-01

    The article embraces the experimental description of the micro linear piezo drive intended for the peripheral cord tensioner in the reflecting surface shape regulator system for large-sized transformable spacecraft antenna reflectors. The research target is the experimental investigation of the micro linear piezo drive to determine the stable oscillatory system operating modes which would include improved energy conversion parameters. The following points are briefly presented: test stand construction-design of the peripheral cord tensioner; the determined frequency characteristics and the identified resonant and actual frequencies of an oscillatory system under inertia load. A series of experiments has been conducted for both different preliminary voltages and inertia mass values.

  20. Dangers of Texting While Driving

    Science.gov (United States)

    ... nhtsa.gov/risky-driving/distracted-driving . Print Out Texting While Driving Guide (pdf) File a Complaint with the FCC ... Office: Consumer and Governmental Affairs Tags: Consumers - Distracted Driving - Health and Safety - Texting Federal Communications Commission 445 12th Street SW, Washington, ...