Position sense at the human elbow joint measured by arm matching or pointing.

PubMed

Tsay, Anthony; Allen, Trevor J; Proske, Uwe

2016-10-01

Position sense at the human elbow joint has traditionally been measured in blindfolded subjects using a forearm matching task. Here we compare position errors in a matching task with errors generated when the subject uses a pointer to indicate the position of a hidden arm. Evidence from muscle vibration during forearm matching supports a role for muscle spindles in position sense. We have recently shown using vibration, as well as muscle conditioning, which takes advantage of muscle's thixotropic property, that position errors generated in a forearm pointing task were not consistent with a role by muscle spindles. In the present study we have used a form of muscle conditioning, where elbow muscles are co-contracted at the test angle, to further explore differences in position sense measured by matching and pointing. For fourteen subjects, in a matching task where the reference arm had elbow flexor and extensor muscles contracted at the test angle and the indicator arm had its flexors conditioned at 90°, matching errors lay in the direction of flexion by 6.2°. After the same conditioning of the reference arm and extension conditioning of the indicator at 0°, matching errors lay in the direction of extension (5.7°). These errors were consistent with predictions based on a role by muscle spindles in determining forearm matching outcomes. In the pointing task subjects moved a pointer to align it with the perceived position of the hidden arm. After conditioning of the reference arm as before, pointing errors all lay in a more extended direction than the actual position of the arm by 2.9°-7.3°, a distribution not consistent with a role by muscle spindles. We propose that in pointing muscle spindles do not play the major role in signalling limb position that they do in matching, but that other sources of sensory input should be given consideration, including afferents from skin and joint.

Spindle cell oncocytoma of the adenohypophysis in a woman: a case report and review of the literature.

PubMed

Mlika, M; Azouz, H; Chelly, I; Saïd, I Ben; Jemel, H; Haouet, S; Zitouna, M; Kchir, N

2011-02-14

Spindle cell oncocytoma of the adenohypophysis is a rare tumour recently reported by Roncaroli et al. in 2002. This tumour is considered a grade I tumour by the World Health Organization. We describe what is, to the best of our knowledge, the 14th case of its kind in the literature. A 45-year-old African woman presented clinical and radiological findings related to a nonfunctioning pituitary adenoma. The diagnosis was made on the basis of histological and immunohistochemical findings. The purpose of this work is to report a rare pituitary tumour and to describe its histological and immunohistochemical features, which were characterized by the expression of thyroid transcription factor 1 antigen by tumour cells. This fact could support the theory of a possible common origin of these tumours in pituicytomas. In fact, thyroid transcription factor 1 is considered to be a specific marker of pituicytes.

Recent advances in understanding oogenesis: interactions with the cytoskeleton, microtubule organization, and meiotic spindle assembly in oocytes

PubMed Central

Marlow, Florence L.

2018-01-01

Maternal control of development begins with production of the oocyte during oogenesis. All of the factors necessary to complete oocyte maturation, meiosis, fertilization, and early development are produced in the transcriptionally active early oocyte. Active transcription of the maternal genome is a mechanism to ensure that the oocyte and development of the early embryo begin with all of the factors needed for successful embryonic development. To achieve the maximum maternal store, only one functional cell is produced from the meiotic divisions that produce the oocyte. The oocyte receives the bulk of the maternal cytoplasm and thus is significantly larger than its sister cells, the tiny polar bodies, which receive a copy of the maternal genome but essentially none of the maternal cytoplasm. This asymmetric division is accomplished by an enormous cell that is depleted of centrosomes in early oogenesis; thus, meiotic divisions in oocytes are distinct from those of mitotic cells. Therefore, these cells must partition the chromosomes faithfully to ensure euploidy by using mechanisms that do not rely on a conventional centrosome-based mitotic spindle. Several mechanisms that contribute to assembly and maintenance of the meiotic spindle in oocytes have been identified; however, none is fully understood. In recent years, there have been many exciting and significant advances in oogenesis, contributed by studies using a myriad of systems. Regrettably, I cannot adequately cover all of the important advances here and so I apologize to those whose beautiful work has not been included. This review focuses on a few of the most recent studies, conducted by several groups, using invertebrate and vertebrate systems, that have provided mechanistic insight into how microtubule assembly and meiotic spindle morphogenesis are controlled in the absence of centrosomes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Era, Saho; Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501; Abe, Takuya

Highlights: Black-Right-Pointing-Pointer SENP1 knockout chicken DT40 cells are hypersensitive to spindle poisons. Black-Right-Pointing-Pointer Spindle poison treatment of SENP1{sup -/-} cells leads to increased mitotic slippage. Black-Right-Pointing-Pointer Mitotic slippage in SENP1{sup -/-} cells associates with apoptosis and endoreplication. Black-Right-Pointing-Pointer SENP1 counteracts sister chromatid separation during mitotic arrest. Black-Right-Pointing-Pointer Plk1-mediated cohesion down-regulation is involved in colcemid cytotoxicity. -- Abstract: SUMO conjugation is a reversible posttranslational modification that regulates protein function. SENP1 is one of the six SUMO-specific proteases present in vertebrate cells and its altered expression is observed in several carcinomas. To characterize SENP1 role in genome integrity, we generated Senp1 knockoutmore » chicken DT40 cells. SENP1{sup -/-} cells show normal proliferation, but are sensitive to spindle poisons. This hypersensitivity correlates with increased sister chromatid separation, mitotic slippage, and apoptosis. To test whether the cohesion defect had a causal relationship with the observed mitotic events, we restored the cohesive status of sister chromatids by introducing the TOP2{alpha}{sup +/-} mutation, which leads to increased catenation, or by inhibiting Plk1 and Aurora B kinases that promote cohesin release from chromosomes during prolonged mitotic arrest. Although TOP2{alpha} is SUMOylated during mitosis, the TOP2{alpha}{sup +/-} mutation had no obvious effect. By contrast, inhibition of Plk1 or Aurora B rescued the hypersensitivity of SENP1{sup -/-} cells to colcemid. In conclusion, we identify SENP1 as a novel factor required for mitotic arrest and cohesion maintenance during prolonged mitotic arrest induced by spindle poisons.« less

Spindle cell oncocytoma of the adenohypophysis in a woman: a case report and review of the literature

PubMed Central

2011-01-01

Introduction Spindle cell oncocytoma of the adenohypophysis is a rare tumour recently reported by Roncaroli et al. in 2002. This tumour is considered a grade I tumour by the World Health Organization. Case presentation We describe what is, to the best of our knowledge, the 14th case of its kind in the literature. A 45-year-old African woman presented clinical and radiological findings related to a nonfunctioning pituitary adenoma. The diagnosis was made on the basis of histological and immunohistochemical findings. Conclusion The purpose of this work is to report a rare pituitary tumour and to describe its histological and immunohistochemical features, which were characterized by the expression of thyroid transcription factor 1 antigen by tumour cells. This fact could support the theory of a possible common origin of these tumours in pituicytomas. In fact, thyroid transcription factor 1 is considered to be a specific marker of pituicytes. PMID:21320334

Pericentromere tension is self-regulated by spindle structure in metaphase

PubMed Central

Chacón, Jeremy M.; Mukherjee, Soumya; Schuster, Breanna M.; Clarke, Duncan J.

2014-01-01

During cell division, a mitotic spindle is built by the cell and acts to align and stretch duplicated sister chromosomes before their ultimate segregation into daughter cells. Stretching of the pericentromeric chromatin during metaphase is thought to generate a tension-based signal that promotes proper chromosome segregation. However, it is not known whether the mitotic spindle actively maintains a set point tension magnitude for properly attached sister chromosomes to facilitate robust mechanochemical checkpoint signaling. By imaging and tracking the thermal movements of pericentromeric fluorescent markers in Saccharomyces cerevisiae, we measured pericentromere stiffness and then used the stiffness measurements to quantitatively evaluate the tension generated by pericentromere stretch during metaphase in wild-type cells and in mutants with disrupted chromosome structure. We found that pericentromere tension in yeast is substantial (4–6 pN) and is tightly self-regulated by the mitotic spindle: through adjustments in spindle structure, the cell maintains wild-type tension magnitudes even when pericentromere stiffness is disrupted. PMID:24821839

Pericentromere tension is self-regulated by spindle structure in metaphase.

PubMed

Chacón, Jeremy M; Mukherjee, Soumya; Schuster, Breanna M; Clarke, Duncan J; Gardner, Melissa K

2014-05-12

During cell division, a mitotic spindle is built by the cell and acts to align and stretch duplicated sister chromosomes before their ultimate segregation into daughter cells. Stretching of the pericentromeric chromatin during metaphase is thought to generate a tension-based signal that promotes proper chromosome segregation. However, it is not known whether the mitotic spindle actively maintains a set point tension magnitude for properly attached sister chromosomes to facilitate robust mechanochemical checkpoint signaling. By imaging and tracking the thermal movements of pericentromeric fluorescent markers in Saccharomyces cerevisiae, we measured pericentromere stiffness and then used the stiffness measurements to quantitatively evaluate the tension generated by pericentromere stretch during metaphase in wild-type cells and in mutants with disrupted chromosome structure. We found that pericentromere tension in yeast is substantial (4-6 pN) and is tightly self-regulated by the mitotic spindle: through adjustments in spindle structure, the cell maintains wild-type tension magnitudes even when pericentromere stiffness is disrupted.

E2 Ubiquitin-conjugating Enzyme, UBE2C Gene, Is Reciprocally Regulated by Wild-type and Gain-of-Function Mutant p53.

PubMed

Bajaj, Swati; Alam, Sk Kayum; Roy, Kumar Singha; Datta, Arindam; Nath, Somsubhra; Roychoudhury, Susanta

2016-07-01

Spindle assembly checkpoint governs proper chromosomal segregation during mitosis to ensure genomic stability. At the cellular level, this event is tightly regulated by UBE2C, an E2 ubiquitin-conjugating enzyme that donates ubiquitin to the anaphase-promoting complex/cyclosome. This, in turn, facilitates anaphase-onset by ubiquitin-mediated degradation of mitotic substrates. UBE2C is an important marker of chromosomal instability and has been associated with malignant growth. However, the mechanism of its regulation is largely unexplored. In this study, we report that UBE2C is transcriptionally activated by the gain-of-function (GOF) mutant p53, although it is transcriptionally repressed by wild-type p53. We showed that wild-type p53-mediated inhibition of UBE2C is p21-E2F4-dependent and GOF mutant p53-mediated transactivation of UBE2C is NF-Y-dependent. We further explored that DNA damage-induced wild-type p53 leads to spindle assembly checkpoint arrest by repressing UBE2C, whereas mutant p53 causes premature anaphase exit by increasing UBE2C expression in the presence of 5-fluorouracil. Identification of UBE2C as a target of wild-type and GOF mutant p53 further highlights the contribution of p53 in regulation of spindle assembly checkpoint. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Correlation between bending of the VM region and pathogenicity of different Potato Spindle Tuber Viroid strains.

PubMed Central

Schmitz, A; Riesner, D

1998-01-01

Only 40 of the 359 nucleotides of Potato Spindle Tuber Viroid (PSTVd) represent the virulence-modulating (VM) region. Minor sequence variations in this domain distinguish mild from severe and even necrotic strains. Our recent hypothesis (Owens RA et al., 1996, Virology 222:144-158) that these differences result in varying degrees of bending of this part of the molecule could be tested experimentally. By in vitro transcription and partial double-strand formation, three types of model RNAs were prepared and subjected to electrophoresis in polyacrylamide gels: (1) Fragments representing the VM regions of six different PSTVd strains; (2) control fragments containing a bulge-loop as a rigid bend or an internal loop as a point of increased flexibility; and (3) dsRNAs of 36, 39, and 43 bp as length standards. Migration anomalies in gels of increasing percentage were evaluated and resulted in the following conclusions. In the absence of Mg2+, the VM regions differ only in terms of flexibility. Addition of Mg2+ induces conformational changes in these RNAs. All strains but Mild exhibit a rigid bend, and the angle of bending increases monotonically with the pathogenicity of the strain. The data are discussed in terms of a mechanism of pathogenicity, that protein-binding to the VM region is the primary pathogenic event. PMID:9769103

Male gametogenesis without centrioles.

PubMed

Riparbelli, Maria Giovanna; Callaini, Giuliano

2011-01-15

The orientation of the mitotic spindle plays a central role in specifying stem cell-renewal by enabling interaction of the daughter cells with external cues: the daughter cell closest to the hub region is instructed to self-renew, whereas the distal one starts to differentiate. Here, we have analyzed male gametogenesis in DSas-4 Drosophila mutants and we have reported that spindle alignment and asymmetric divisions are properly executed in male germline stem cells that lack centrioles. Spermatogonial divisions also correctly proceed in the absence of centrioles, giving rise to cysts of 16 primary spermatocytes. By contrast, abnormal meiotic spindles assemble in primary spermatocytes. These results point to different requirements for centrioles during male gametogenesis of Drosophila. Spindle formation during germ cell mitosis may be successfully supported by an acentrosomal pathway that is inadequate to warrant the proper execution of meiosis. Copyright © 2010 Elsevier Inc. All rights reserved.

Synthesis and luminescent properties of spindle-like CaWO{sub 4}:Sm{sup 3+} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tian, Yue; Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026; Liu, Yu

2012-01-15

Graphical abstract: In this paper, spindle-like CaWO{sub 4}:Sm{sup 3+} phosphors were prepared via a polyvinylpyrrolidone (PVP)-assisted sonochemical process. Dependence of emission intensity on Sm{sup 3+} ions concentration in the CaWO{sub 4}:Sm{sup 3+} phosphor were also calculated via a nonlinear fitting by using the formula y = ax/(1 + bx{sup c}). Highlights: Black-Right-Pointing-Pointer The samples were prepared via a PVP assisted sonochemical process. Black-Right-Pointing-Pointer The color coordinates for 1 mol% Sm{sup 3+} doped CaWO{sub 4} phosphor were calculated. Black-Right-Pointing-Pointer The D-D interaction is responsible for concentration quenching between Sm{sup 3+} ions. Black-Right-Pointing-Pointer The critical energy transfer distances (R{sub c}) were obtained.more » -- Abstract: Spindle-like CaWO{sub 4}:Sm{sup 3+} phosphors were prepared via a Polyvinylpyrrolidone (PVP)-assisted sonochemical process, and characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectroscopy (PL). The XRD results suggested that the prepared samples are single-phase. The FE-SEM images indicated that the prepared CaWO{sub 4}:Sm{sup 3+} phosphors are composed of many spindles with maximum average diameter of 150 nm and maximum average length of 500 nm. Under 404 nm excitation, the characteristic emissions corresponding to {sup 4}G{sub 5/2} {yields} {sup 6}H{sub J} (J = 5/2, 7/2, 9/2 and 11/2) transitions of Sm{sup 3+} in CaWO{sub 4} phosphors were observed. The color coordinates for 1 mol% Sm{sup 3+} doped CaWO{sub 4} phosphor were calculated to be (0.595, 0.404). The fluorescent concentration quenching of Sm{sup 3+} doped spindle-like phosphors was studied based on the Van Uitert's model, and it was found that the electric dipole-dipole (D-D) interaction is the dominant energy transfer mechanism between Sm{sup 3+} ions in the CaWO{sub 4}:Sm{sup 3+} phosphors. The critical energy transfer distance was estimated.« less

RNA as a structural and regulatory component of the centromere.

PubMed

Gent, Jonathan I; Dawe, R Kelly

2012-01-01

Despite many challenges, great progress has been made in identifying kinetochore proteins and understanding their overall functions relative to spindles and centromeric DNA. In contrast, less is known about the specialized centromeric chromatin environment and how it may be involved in regulating the assembly of kinetochore proteins. Multiple independent lines of evidence have implicated transcription and the resulting RNA as an important part of this process. Here, we summarize recent literature demonstrating the roles of centromeric RNA in regulating kinetochore assembly and maintenance. We also review literature suggesting that the process of centromeric transcription may be as important as the resulting RNA and that such transcription may be involved in recruiting the centromeric histone variant CENH3.

Decoding the principles underlying the frequency of association with nucleoli for RNA polymerase III–transcribed genes in budding yeast

PubMed Central

Belagal, Praveen; Normand, Christophe; Shukla, Ashutosh; Wang, Renjie; Léger-Silvestre, Isabelle; Dez, Christophe; Bhargava, Purnima; Gadal, Olivier

2016-01-01

The association of RNA polymerase III (Pol III)–transcribed genes with nucleoli seems to be an evolutionarily conserved property of the spatial organization of eukaryotic genomes. However, recent studies of global chromosome architecture in budding yeast have challenged this view. We used live-cell imaging to determine the intranuclear positions of 13 Pol III–transcribed genes. The frequency of association with nucleolus and nuclear periphery depends on linear genomic distance from the tethering elements—centromeres or telomeres. Releasing the hold of the tethering elements by inactivating centromere attachment to the spindle pole body or changing the position of ribosomal DNA arrays resulted in the association of Pol III–transcribed genes with nucleoli. Conversely, ectopic insertion of a Pol III–transcribed gene in the vicinity of a centromere prevented its association with nucleolus. Pol III–dependent transcription was independent of the intranuclear position of the gene, but the nucleolar recruitment of Pol III–transcribed genes required active transcription. We conclude that the association of Pol III–transcribed genes with the nucleolus, when permitted by global chromosome architecture, provides nucleolar and/or nuclear peripheral anchoring points contributing locally to intranuclear chromosome organization. PMID:27559135

A curved edge diffraction-utilized displacement sensor for spindle metrology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, ChaBum, E-mail: clee@tntech.edu; Zhao, Rui; Jeon, Seongkyul

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 surfacemore » 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.« less

The invariant cleavage pattern displayed by ascidian embryos depends on spindle positioning along the cell's longest axis in the apical plane and relies on asynchronous cell divisions

PubMed Central

Dumollard, Rémi; Minc, Nicolas; Salez, Gregory; Aicha, Sameh Ben; Bekkouche, Faisal; Hebras, Céline; Besnardeau, Lydia; McDougall, Alex

2017-01-01

The ascidian embryo is an ideal system to investigate how cell position is determined during embryogenesis. Using 3D timelapse imaging and computational methods we analyzed the planar cell divisions in ascidian early embryos and found that spindles in every cell tend to align at metaphase in the long length of the apical surface except in cells undergoing unequal cleavage. Furthermore, the invariant and conserved cleavage pattern of ascidian embryos was found to consist in alternate planar cell divisions between ectoderm and endomesoderm. In order to test the importance of alternate cell divisions we manipulated zygotic transcription induced by β-catenin or downregulated wee1 activity, both of which abolish this cell cycle asynchrony. Crucially, abolishing cell cycle asynchrony consistently disrupted the spindle orienting mechanism underpinning the invariant cleavage pattern. Our results demonstrate how an evolutionary conserved cell cycle asynchrony maintains the invariant cleavage pattern driving morphogenesis of the ascidian blastula. DOI: http://dx.doi.org/10.7554/eLife.19290.001 PMID:28121291

The role of muscle spindles in the development of the monosynaptic stretch reflex

PubMed Central

Wang, Zhi; Li, LingYing

2012-01-01

Muscle sensory axons induce the development of specialized intrafusal muscle fibers in muscle spindles during development, but the role that the intrafusal fibers may play in the development of the central projections of these Ia sensory axons is unclear. In the present study, we assessed the influence of intrafusal fibers in muscle spindles on the formation of monosynaptic connections between Ia (muscle spindle) sensory axons and motoneurons (MNs) using two transgenic strains of mice. Deletion of the ErbB2 receptor from developing myotubes disrupts the formation of intrafusal muscle fibers and causes a nearly complete absence of functional synaptic connections between Ia axons and MNs. Monosynaptic connectivity can be fully restored by postnatal administration of neurotrophin-3 (NT-3), and the synaptic connections in NT-3-treated mice are as specific as in wild-type mice. Deletion of the Egr3 transcription factor also impairs the development of intrafusal muscle fibers and disrupts synaptic connectivity between Ia axons and MNs. Postnatal injections of NT-3 restore the normal strengths and specificity of Ia–motoneuronal connections in these mice as well. Severe deficits in intrafusal fiber development, therefore, do not disrupt the establishment of normal, selective patterns of connections between Ia axons and MNs, although these connections require the presence of NT-3, normally supplied by intrafusal fibers, to be functional. PMID:22490553

Fabrication of an infrared Shack-Hartmann sensor by combining high-speed single-point diamond milling and precision compression molding processes.

PubMed

Zhang, Lin; Zhou, Wenchen; Naples, Neil J; Yi, Allen Y

2018-05-01

A novel fabrication method by combining high-speed single-point diamond milling and precision compression molding processes for fabrication of discontinuous freeform microlens arrays was proposed. Compared with slow tool servo diamond broaching, high-speed single-point diamond milling was selected for its flexibility in the fabrication of true 3D optical surfaces with discontinuous features. The advantage of single-point diamond milling is that the surface features can be constructed sequentially by spacing the axes of a virtual spindle at arbitrary positions based on the combination of rotational and translational motions of both the high-speed spindle and linear slides. By employing this method, each micro-lenslet was regarded as a microstructure cell by passing the axis of the virtual spindle through the vertex of each cell. An optimization arithmetic based on minimum-area fabrication was introduced to the machining process to further increase the machining efficiency. After the mold insert was machined, it was employed to replicate the microlens array onto chalcogenide glass. In the ensuing optical measurement, the self-built Shack-Hartmann wavefront sensor was proven to be accurate in detecting an infrared wavefront by both experiments and numerical simulation. The combined results showed that precision compression molding of chalcogenide glasses could be an economic and precision optical fabrication technology for high-volume production of infrared optics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Akinori; Kikuguchi, Chisato; Morita, Masahiro

Highlights: Black-Right-Pointing-Pointer CNOT3 depletion increases the mitotic index. Black-Right-Pointing-Pointer CNOT3 inhibits the expression of MAD1. Black-Right-Pointing-Pointer CNOT3 destabilizes the MAD1 mRNA. Black-Right-Pointing-Pointer MAD1 knockdown attenuates the CNOT3 depletion-induced mitotic arrest. -- Abstract: The stability of mRNA influences the dynamics of gene expression. The CCR4-NOT complex, the major deadenylase in mammalian cells, shortens the mRNA poly(A) tail and contributes to the destabilization of mRNAs. The CCR4-NOT complex plays pivotal roles in various physiological functions, including cell proliferation, apoptosis, and metabolism. Here, we show that CNOT3, a subunit of the CCR4-NOT complex, is involved in the regulation of the spindle assembly checkpoint,more » suggesting that the CCR4-NOT complex also plays a part in the regulation of mitosis. CNOT3 depletion increases the population of mitotic-arrested cells and specifically increases the expression of MAD1 mRNA and its protein product that plays a part in the spindle assembly checkpoint. We showed that CNOT3 depletion stabilizes the MAD1 mRNA, and that MAD1 knockdown attenuates the CNOT3 depletion-induced increase of the mitotic index. Basing on these observations, we propose that CNOT3 is involved in the regulation of the spindle assembly checkpoint through its ability to regulate the stability of MAD1 mRNA.« less

Clinicopathologic Diversity of Undifferentiated Sarcoma With BCOR-CCNB3 Fusion: Analysis of 11 Cases With a Reappraisal of the Utility of Immunohistochemistry for BCOR and CCNB3.

PubMed

Matsuyama, Atsuji; Shiba, Eisuke; Umekita, Yoshihisa; Nosaka, Kanae; Kamio, Takihiro; Yanai, Hiroyuki; Miyasaka, Chika; Watanabe, Reiko; Ito, Ichiro; Tamaki, Tomoko; Hayashi, Shinichi; Hisaoka, Masanori

2017-12-01

Undifferentiated sarcoma harboring the BCOR-CCNB3 fusion is characterized by its predilection to affect skeletons of adolescent males, cellular small round/spindle cell morphology, and CCNB3 immunoreactivity. We analyzed 11 cases of BCOR-CCNB3 sarcoma, 10 of which were identified in a reverse transcription-polymerase chain reaction-based screen of 85 patient samples recorded in our database as unclassified small round or spindle cell sarcomas. BCOR rearrangements were confirmed by fluorescence in situ hybridization in 8 tumors. All patients were males aged between 6 and 31 years. In addition to 5 tumors in soft tissue and 4 in the axial or appendicular skeletons, which are typical locations, a tumor was located in the paranasal sinus and another in the lung. Microscopically, the tumors comprised proliferating atypical spindle and/or small round cells with diverse morphologic features such as small concentric whorls, myxoid stroma, a hemangiopericytomatous appearance, and/or hyalinized collagen resembling a solitary fibrous tumor, and angiomatous or slit-like spaces containing extravasated erythrocytes. Tumor cells were immunoreactive to CCNB3 (9/11), BCOR (10/10), TLE1 (6/10), bcl-2 (9/11), CD99 (8/10), CD56 (8/10), c-kit (4/10), and cyclin D1 (10/10). In an immunohistochemical analysis of an additional 412 small round or spindle cell tumors, CCNB3 was detected in 6 (1.5%) and BCOR in 18 (4.4%). Our analysis highlights the varying clinicopathologic features of this tumor, which partially overlap with other small round or spindle cell tumors, including solitary fibrous tumor and vascular tumors. Because CCNB3 and BCOR immunohistochemistry lacks adequate sensitivity and specificity, a molecular genetic approach remains essential for diagnosis.

v-Src-induced nuclear localization of YAP is involved in multipolar spindle formation in tetraploid cells.

PubMed

Kakae, Keiko; Ikeuchi, Masayoshi; Kuga, Takahisa; Saito, Youhei; Yamaguchi, Naoto; Nakayama, Yuji

2017-01-01

The protein-tyrosine kinase, c-Src, is involved in a variety of signaling events, including cell division. We have reported that v-Src, which is a mutant variant of the cellular proto-oncogene, c-Src, causes delocalization of Aurora B kinase, resulting in a furrow regression in cytokinesis and the generation of multinucleated cells. However, the effect of v-Src on mitotic spindle formation is unknown. Here we show that v-Src-expressing HCT116 and NIH3T3 cells undergo abnormal cell division, in which cells separate into more than two cells. Upon v-Src expression, the proportion of multinucleated cells is increased in a time-dependent manner. Flow cytometry analysis revealed that v-Src increases the number of cells having a ≥4N DNA content. Microscopic analysis showed that v-Src induces the formation of multipolar spindles with excess centrosomes. These results suggest that v-Src induces multipolar spindle formation by generating multinucleated cells. Tetraploidy activates the tetraploidy checkpoint, leading to a cell cycle arrest of tetraploid cells at the G1 phase, in which the nuclear exclusion of the transcription co-activator YAP plays a critical role. In multinucleated cells that are induced by cytochalasin B and the Plk1 inhibitor, YAP is excluded from the nucleus. However, v-Src prevents this nuclear exclusion of YAP through a decrease in the phosphorylation of YAP at Ser127 in multinucleated cells. Furthermore, v-Src decreases the expression level of p53, which also plays a critical role in the cell cycle arrest of tetraploid cells. These results suggest that v-Src promotes abnormal spindle formation in at least two ways: generation of multinucleated cells and a weakening of the tetraploidy checkpoint. Copyright © 2016 Elsevier Inc. All rights reserved.

Supramolecular "Step Polymerization" of Preassembled Micelles: A Study of "Polymerization" Kinetics.

PubMed

Yang, Chaoying; Ma, Xiaodong; Lin, Jiaping; Wang, Liquan; Lu, Yingqing; Zhang, Liangshun; Cai, Chunhua; Gao, Liang

2018-03-01

In nature, sophisticated functional materials are created through hierarchical self-assembly of nanoscale motifs, which has inspired the fabrication of man-made materials with complex architectures for a variety of applications. Herein, a kinetic study on the self-assembly of spindle-like micelles preassembled from polypeptide graft copolymers is reported. The addition of dimethylformamide and, subsequently, a selective solvent (water) can generate a "reactive point" at both ends of the spindles as a result of the existence of structural defects, which induces the "polymerization" of the spindles into nanowires. Experimental results combined with dissipative particle dynamics simulations show that the polymerization of the micellar subunits follows a step-growth polymerization mechanism with a second-order reaction characteristic. The assembly rate of the micelles is dependent on the subunit concentration and on the activity of the reactive points. The present work reveals a law governing the self-assembly kinetics of micelles with structural defects and opens the door for the construction of hierarchical structures with a controllable size through supramolecular step polymerization. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tension-Induced Error Correction and Not Kinetochore Attachment Status Activates the SAC in an Aurora-B/C-Dependent Manner in Oocytes.

PubMed

Vallot, Antoine; Leontiou, Ioanna; Cladière, Damien; El Yakoubi, Warif; Bolte, Susanne; Buffin, Eulalie; Wassmann, Katja

2018-01-08

Cell division with partitioning of the genetic material should take place only when paired chromosomes named bivalents (meiosis I) or sister chromatids (mitosis and meiosis II) are correctly attached to the bipolar spindle in a tension-generating manner. For this to happen, the spindle assembly checkpoint (SAC) checks whether unattached kinetochores are present, in which case anaphase onset is delayed to permit further establishment of attachments. Additionally, microtubules are stabilized when they are attached and under tension. In mitosis, attachments not under tension activate the so-named error correction pathway depending on Aurora B kinase substrate phosphorylation. This leads to microtubule detachments, which in turn activates the SAC [1-3]. Meiotic divisions in mammalian oocytes are highly error prone, with severe consequences for fertility and health of the offspring [4, 5]. Correct attachment of chromosomes in meiosis I leads to the generation of stretched bivalents, but-unlike mitosis-not to tension between sister kinetochores, which co-orient. Here, we set out to address whether reduction of tension applied by the spindle on bioriented bivalents activates error correction and, as a consequence, the SAC. Treatment of oocytes in late prometaphase I with Eg5 kinesin inhibitor affects spindle tension, but not attachments, as we show here using an optimized protocol for confocal imaging. After Eg5 inhibition, bivalents are correctly aligned but less stretched, and as a result, Aurora-B/C-dependent error correction with microtubule detachment takes place. This loss of attachments leads to SAC activation. Crucially, SAC activation itself does not require Aurora B/C kinase activity in oocytes. Copyright © 2017 Elsevier Ltd. All rights reserved.

BCOR-CCNB3-positive soft tissue sarcoma with round-cell and spindle-cell histology: a series of four cases highlighting the pitfall of mimicking poorly differentiated synovial sarcoma.

PubMed

Li, Wan-Shan; Liao, I-Chuang; Wen, Mei-Chin; Lan, Howard Haw-Chang; Yu, Shih-Chen; Huang, Hsuan-Ying

2016-11-01

BCOR-CCNB3 sarcoma is a genetically defined undifferentiated malignancy with Ewing sarcoma (ES)-like round cells, and preferentially affects the bones of male adolescents. Sarcomas harbouring BCOR-CCNB3 rarely arise from soft tissues; therefore, we aimed to report four cases to expand the clinicopathological spectrum. By reverse transcription polymerase chain reaction and confirmatory sequencing, we detected a BCOR-CCNB3 transcript in primary undifferentiated sarcomas of the deep musculature of four male patients, comprising two teenagers (aged 14 and 17 years) and two adults (aged 34 and 44 years). The tumours originated in the back (n = 2), pelvis (n = 1), and thigh (n = 1), and were 70-140 mm in size (mean, 107 mm). All tumours showed sheets of primitive round or ovoid cells with vesicular nuclei, active mitosis (28-41/10 high-power fields), variably prominent nucleoli, and geographical necrosis. This major component transformed into fascicles of elongated spindle cells with staghorn vessels and a myxoid reticular stroma, accounting for 10-50% of areas. All cases were positive for CD99, three were positive for TLE1, and one was positive for EMA, indicating poorly differentiated synovial sarcomas (PDSSs). Nuclear cyclin B3 reactivity was present in all cases, but not in molecularly confirmed atypical ESs and PDSSs. At the last follow-up (median, 13.5 months), one patient had died of lung metastasis, two were alive with tumours, and one was tumour-free. BCOR-CCNB3-positive sarcomas may primarily occur in soft tissues of adults and show PDSS-mimicking round-cell and spindle-cell histology with aggressive behaviour. Cyclin B3 is useful for selecting candidates for BCOR-CCNB3 molecular testing. © 2016 John Wiley & Sons Ltd.

BCOR-CCNB3 Fusions Are Frequent in Undifferentiated Sarcomas of Male Children

PubMed Central

Peters, Tricia L.; Kumar, Vijetha; Polikepahad, Sumanth; Lin, Frank Y.; Sarabia, Stephen F.; Liang, Yu; Wang, Wei-Lien; Lazar, Alexander J.; Doddapaneni, Harsha Vardhan; Chao, Hsu; Muzny, Donna M.; Wheeler, David A.; Okcu, M. Fatih; Plon, Sharon E.; Hicks, M. John; López-Terrada, Dolores; Parsons, D. Williams; Roy, Angshumoy

2014-01-01

The BCOR-CCNB3 fusion gene, resulting from a chromosome X paracentric inversion, was recently described in translocation-negative ‘Ewing-like’ sarcomas arising in bone and soft tissue. Genetic subclassification of undifferentiated unclassified sarcomas may potentially offer markers for reproducible diagnosis and substrates for therapy. Using whole transcriptome paired end RNA sequencing (RNA-seq) we unexpectedly identified BCOR-CCNB3 fusion transcripts in an undifferentiated spindle cell sarcoma. RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA. Five additional undifferentiated sarcomas with BCOR-CCNB3 fusions were identified in a series of 42 pediatric and adult unclassified sarcomas. Genomic breakpoint analysis demonstrated unique breakpoint locations in each case at the DNA level even though the resulting fusion mRNA was identical in all cases. All patients with BCOR-CCNB3 sarcoma were males diagnosed in mid-childhood (7-13 years of age). Tumors were equally distributed between axial and extra-axial locations. Five of the six tumors were soft tissue lesions with either predominant spindle cell morphology or spindle cell areas interspersed with ovoid to round cells. CCNB3 immunohistochemistry showed strong nuclear positivity in 5 tumors prior to oncologic therapy, but was patchy to negative in post-treatment tumor samples. An RT-PCR assay developed to detect the fusion transcript in archival formalin-fixed tissue was positive in all 6 cases, with high sensitivity and specificity in both pre- and post-treated samples. This study adds to recent reports on the clinicopathologic spectrum of BCOR-CCNB3 fusion-positive sarcomas, a newly-emerging entity within the undifferentiated unclassified sarcoma category, and describes a simple RT-PCR assay that in conjunction with CCNB3 immunohistochemistry can be useful in diagnosing these tumors. PMID:25360585

Age-associated increase in aneuploidy and changes in gene expression in mouse eggs

PubMed Central

Pan, Hua; Ma, Pengpeng; Zhu, Wenting; Schultz, Richard M.

2008-01-01

An increase in the incidence of aneuploidy is well documented with increasing maternal age, in particular in human females. Remarkably, little is known regarding the underlying molecular basis for the age-associated increase in aneuploidy, which is a major source of decreased fertility in humans. Using mouse as a model system we find that eggs obtained from old mice (60–70 weeks of age) display a six-fold increase in the incidence of hyperploidy as assessed by chromosome spreads. Expression profiling of transcripts in oocytes and eggs obtained from young and old mice reveals that ~5% of the transcripts are differentially expressed in oocytes obtained from old females when compared to oocytes obtained from young females (6–12 weeks of age) and that this fraction increases to ~33% in eggs. The latter finding indicates that the normal pattern of degradation of maternal mRNAs that occurs during oocyte maturation is dramatically altered in eggs obtained from old mice and could therefore be a contributing source to the decline in fertility. Analysis of the differentially expressed transcripts also indicated that the strength of the spindle assembly checkpoint is weakened and that higher errors of microtubule-kinetochore interactions constitute part of molecular basis for the ageassociated increase in aneuploidy in females. Last, BRCA1 expression is reduced in oocytes obtained from old females and RNAi-mediated reduction of BRCA1 in oocytes obtained from young females results in perturbing spindle formation and chromosome congression following maturation. PMID:18342300

Thermal Error Test and Intelligent Modeling Research on the Spindle of High Speed CNC Machine Tools

NASA Astrophysics Data System (ADS)

Luo, Zhonghui; Peng, Bin; Xiao, Qijun; Bai, Lu

2018-03-01

Thermal error is the main factor affecting the accuracy of precision machining. Through experiments, this paper studies the thermal error test and intelligent modeling for the spindle of vertical high speed CNC machine tools in respect of current research focuses on thermal error of machine tool. Several testing devices for thermal error are designed, of which 7 temperature sensors are used to measure the temperature of machine tool spindle system and 2 displacement sensors are used to detect the thermal error displacement. A thermal error compensation model, which has a good ability in inversion prediction, is established by applying the principal component analysis technology, optimizing the temperature measuring points, extracting the characteristic values closely associated with the thermal error displacement, and using the artificial neural network technology.

SNM1B/Apollo interacts with astrin and is required for the prophase cell cycle checkpoint.

PubMed

Liu, Lingling; Akhter, Shamima; Bae, Jae-Bum; Mukhopadhyay, Sudit S; Richie, Christopher T; Liu, Xiaojun; Legerski, Randy

2009-02-15

Previously, we have shown that SNM1A is a multifunctional gene involved in both the DNA damage response and in an early mitotic checkpoint in response to spindle stress. Another member of the SNM1 gene family, SNM1B/Apollo, has been shown to have roles in both the response to DNA interstrand cross-linking agents and in telomere protection during S phase. Here, we demonstrate a novel role for SNM1B/Apollo in mitosis in response to spindle stress. SNM1B-deficient cells exhibit a defect in the prophase checkpoint. Loss of the prophase checkpoint induces an extended mitotic delay, which is due to prolonged activation of the spindle checkpoint. In addition, we show that SNM1B/Apollo interacts with the essential microtubule binding protein Astrin. SNM1B/Apollo interacts with Astrin through its conserved metallo-beta-lactamase domain, and disruption of this interaction by point mutations results in a deficient prophase checkpoint. These findings suggest that SNM1B/Apollo and Astrin function together to enforce the prophase checkpoint in response to spindle stress.

A Bromodomain-Containing Protein from Tomato Specifically Binds Potato Spindle Tuber Viroid RNA In Vitro and In Vivo

PubMed Central

Martínez de Alba, Angel Emilio; Sägesser, Rudolf; Tabler, Martin; Tsagris, Mina

2003-01-01

For the identification of RNA-binding proteins that specifically interact with potato spindle tuber viroid (PSTVd), we subjected a tomato cDNA expression library prepared from viroid-infected leaves to an RNA ligand screening procedure. We repeatedly identified cDNA clones that expressed a protein of 602 amino acids. The protein contains a bromodomain and was termed viroid RNA-binding protein 1 (VIRP1). The specificity of interaction of VIRP1 with viroid RNA was studied by different methodologies, which included Northwestern blotting, plaque lift, and electrophoretic mobility shift assays. VIRP1 interacted strongly and specifically with monomeric and oligomeric PSTVd positive-strand RNA transcripts. Other RNAs, for example, U1 RNA, did not bind to VIRP1. Further, we could immunoprecipitate complexes from infected tomato leaves that contained VIRP1 and viroid RNA in vivo. Analysis of the protein sequence revealed that VIRP1 is a member of a newly identified family of transcriptional regulators associated with chromatin remodeling. VIRP1 is the first member of this family of proteins, for which a specific RNA-binding activity is shown. A possible role of VIRP1 in viroid replication and in RNA mediated chromatin remodeling is discussed. PMID:12915580

Cytological, molecular mechanisms and temperature stress regulating production of diploid male gametes in Dianthus caryophyllus L.

PubMed

Zhou, Xuhong; Mo, Xijun; Gui, Min; Wu, Xuewei; Jiang, Yalian; Ma, Lulin; Shi, Ziming; Luo, Ying; Tang, Wenru

2015-12-01

In plant evolution, because of its key role in sexual polyploidization or whole genome duplication events, diploid gamete formation is considered as an important component in diversification and speciation. Environmental stress often triggers unreduced gamete production. However, the molecular, cellular mechanisms and adverse temperature regulating diplogamete production in carnation remain poorly understood. Here, we investigate the cytological basis for 2n male gamete formation and describe the isolation and characterization of the first gene, DcPS1 (Dianthus Caryophyllus Parallel Spindle 1). In addition, we analyze influence of temperature stress on diploid gamete formation and transcript levels of DcPS1. Cytological evidence indicated that 2n male gamete formation is attributable to abnormal spindle orientation at male meiosis II. DcPS1 protein is conserved throughout the plant kingdom and carries domains suggestive of a regulatory function. DcPS1 expression analysis show DcPS1 gene probably have a role in 2n pollen formation. Unreduced pollen formation in various cultivation was sensitive to high or low temperature which was probably regulated by the level of DcPS1 transcripts. In a broader perspective, these findings can have potential applications in fundamental polyploidization research and plant breeding programs. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Radiation noise of the bearing applied to the ceramic motorized spindle based on the sub-source decomposition method

NASA Astrophysics Data System (ADS)

Bai, X. T.; Wu, Y. H.; Zhang, K.; Chen, C. Z.; Yan, H. P.

2017-12-01

This paper mainly focuses on the calculation and analysis on the radiation noise of the angular contact ball bearing applied to the ceramic motorized spindle. The dynamic model containing the main working conditions and structural parameters is established based on dynamic theory of rolling bearing. The sub-source decomposition method is introduced in for the calculation of the radiation noise of the bearing, and a comparative experiment is adopted to check the precision of the method. Then the comparison between the contribution of different components is carried out in frequency domain based on the sub-source decomposition method. The spectrum of radiation noise of different components under various rotation speeds are used as the basis of assessing the contribution of different eigenfrequencies on the radiation noise of the components, and the proportion of friction noise and impact noise is evaluated as well. The results of the research provide the theoretical basis for the calculation of bearing noise, and offers reference to the impact of different components on the radiation noise of the bearing under different rotation speed.

Searching for proprioceptors in human facial muscles.

PubMed

Cobo, Juan L; Abbate, Francesco; de Vicente, Juan C; Cobo, Juan; Vega, José A

2017-02-15

The human craniofacial muscles innervated by the facial nerve typically lack muscle spindles. However these muscles have proprioception that participates in the coordination of facial movements. A functional substitution of facial proprioceptors by cutaneous mechanoreceptors has been proposed but at present this alternative has not been demonstrated. Here we have investigated whether other kinds of sensory structures are present in two human facial muscles (zygomatic major and buccal). Human checks were removed from Spanish cadavers, and processed for immunohistochemical detection of nerve fibers (neurofilament proteins and S100 protein) and two putative mechanoproteins (acid-sensing ion channel 2 and transient receptor potential vanilloid 4) associated with mechanosensing. Nerves of different calibers were found in the connective septa and within the muscle itself. In all the muscles analysed, capsular corpuscle-like structures resembling elongated or round Ruffini-like corpuscles were observed. Moreover the axon profiles within these structures displayed immunoreactivity for both putative mechanoproteins. The present results demonstrate the presence of sensory structures in facial muscles that can substitute for typical muscle spindles as the source of facial proprioception. Copyright © 2017 Elsevier B.V. All rights reserved.

Muscle spindle response at the onset of isometric voluntary contractions in man. Time difference between fusimotor and skeletomotor effects

PubMed Central

Vallbo, Å. B.

1971-01-01

1. Impulses in single muscle afferents were recorded from the median nerves of waking human subjects with percutaneously inserted tungsten needle electrodes. During isometric voluntary contractions, unitary discharges were analysed from muscle spindle endings in the wrist and finger flexor muscles and the electromyographic activity from these muscles was recorded simultaneously. 2. When the subject activated the muscle portion in which a spindle was located, the afferent discharge increased in spite of the mechanical unloading effects of the skeletomotor contraction indicating a concomitant fusimotor activation. This was valid for slowly rising contractions as well as small fast rising twitches. 3. The time of onset of spindle acceleration was determined in relation to the time of onset of the electromyographic activity for thirty-one units studied altogether in more than seven hundred contractions. It was found that spindle acceleration regularly occurred after the onset of the electromyographic activity. 4. There was a considerable variation from one test to the other, for the individual units, with regard to the exact time of onset of spindle acceleration, although spindle acceleration occurred mostly within 0·5 sec after the onset of the electromyographic activity in sustained contractions and within 0·1 sec in small fast rising twitches. It was not possible to assess to what extent this variation was accounted for by variations in the mechanical unloading effects of the skeletomotor contraction or variations in the timing of the fusimotor outflow. 5. For many units, spindle acceleration did not occur until 10-50 msec after the onset of the skeletomotor contraction. This time is of the same order of magnitude as the time difference in latency from the spinal cord to the recording points in the two systems, as estimated from reasonable assumptions. 6. It was concluded that the fusimotor system does not participate in the initiation of voluntary contractions in man, but that the skeletomotor activity is initiated by descending impulses from supraspinal structures and their effects on the neuronal organization within the spinal cord. 7. The fact that fusimotor activation occurs also in very small and short lasting twitches, when spindle acceleration must have a negligible influence on the skeletomotor outflow, suggests that the fusimotor and the skeletomotor systems are rigidly co-activated in voluntary contractions. 8. The finding that spindle acceleration does not occur until 10-50 msec after the onset of the electromyographic activity suggests that there is an approximately simultaneous onset of the fusimotor and the skeletomotor outflows from the spinal cord. PMID:4256547

Transcriptional regulation of intermediate progenitor cell generation during hippocampal development

PubMed Central

Harris, Lachlan; Zalucki, Oressia; Gobius, Ilan; McDonald, Hannah; Osinki, Jason; Harvey, Tracey J.; Essebier, Alexandra; Vidovic, Diana; Gladwyn-Ng, Ivan; Burne, Thomas H.; Heng, Julian I.; Richards, Linda J.; Gronostajski, Richard M.

2016-01-01

During forebrain development, radial glia generate neurons through the production of intermediate progenitor cells (IPCs). The production of IPCs is a central tenet underlying the generation of the appropriate number of cortical neurons, but the transcriptional logic underpinning this process remains poorly defined. Here, we examined IPC production using mice lacking the transcription factor nuclear factor I/X (Nfix). We show that Nfix deficiency delays IPC production and prolongs the neurogenic window, resulting in an increased number of neurons in the postnatal forebrain. Loss of additional Nfi alleles (Nfib) resulted in a severe delay in IPC generation while, conversely, overexpression of NFIX led to precocious IPC generation. Mechanistically, analyses of microarray and ChIP-seq datasets, coupled with the investigation of spindle orientation during radial glial cell division, revealed that NFIX promotes the generation of IPCs via the transcriptional upregulation of inscuteable (Insc). These data thereby provide novel insights into the mechanisms controlling the timely transition of radial glia into IPCs during forebrain development. PMID:27965439

Localization of the Kinesin-like Protein Xklp2 to Spindle Poles Requires a Leucine Zipper, a Microtubule-associated Protein, and Dynein

PubMed Central

Wittmann, Torsten; Boleti, Haralabia; Antony, Claude; Karsenti, Eric; Vernos, Isabelle

1998-01-01

Xklp2 is a plus end–directed Xenopus kinesin-like protein localized at spindle poles and required for centrosome separation during spindle assembly in Xenopus egg extracts. A glutathione-S-transferase fusion protein containing the COOH-terminal domain of Xklp2 (GST-Xklp2-Tail) was previously found to localize to spindle poles (Boleti, H., E. Karsenti, and I. Vernos. 1996. Cell. 84:49–59). Now, we have examined the mechanism of localization of GST-Xklp2-Tail. Immunofluorescence and electron microscopy showed that Xklp2 and GST-Xklp2-Tail localize specifically to the minus ends of spindle pole and aster microtubules in mitotic, but not in interphase, Xenopus egg extracts. We found that dimerization and a COOH-terminal leucine zipper are required for this localization: a single point mutation in the leucine zipper prevented targeting. The mechanism of localization is complex and two additional factors in mitotic egg extracts are required for the targeting of GST-Xklp2-Tail to microtubule minus ends: (a) a novel 100-kD microtubule-associated protein that we named TPX2 (Targeting protein for Xklp2) that mediates the binding of GST-Xklp2-Tail to microtubules and (b) the dynein–dynactin complex that is required for the accumulation of GST-Xklp2-Tail at microtubule minus ends. We propose two molecular mechanisms that could account for the localization of Xklp2 to microtubule minus ends. PMID:9813089

Chromosomal instability in mouse embryonic fibroblasts null for the transcriptional co-repressor Ski

PubMed Central

Marcelain, Katherine; Armisen, Ricardo; Aguirre, Adam; Ueki, Nobuhide; Toro, Jessica; Colmenares, Clemencia; Hayman, Michael J

2011-01-01

Ski is a transcriptional regulator that has been considered an oncoprotein, given its ability to induce oncogenic transformation in avian model systems. However, studies in mouse and in some human tumor cells have also indicated a tumor suppressor activity for this protein. We found that Ski−/− mouse embryo fibroblasts exhibit high levels of genome instability, namely aneuploidy, consistent with a tumor suppressor function for Ski. Time-lapse microscopy revealed lagging chromosomes and chromatin/chromosome bridges as the major cause of micronuclei formation and the subsequent aneuploidy. Although these cells arrested in mitosis after treatment with spindle disrupting drugs and exhibited a delayed metaphase/anaphase transition, Spindle Assembly Checkpoint (SAC) was not sufficient to prevent chromosome missegregation, consistent with a weakened SAC. Our in vivo analysis also showed dynamic metaphase plate rearrangements with switches in polarity in cells arrested in metaphase. Importantly, after ectopic expression of Ski the cells that displayed this metaphase arrest died directly during metaphase or after aberrant cell division, relating SAC activation and mitotic cell death. This increased susceptibility to undergo mitosis-associated cell death reduced the number of micronuclei-containing cells. The presented data support a new role for Ski in the mitotic process and in maintenance of genetic stability, providing insights into the mechanism of tumor suppression mediated by this protein. PMID:21412778

Chromosomal instability in mouse embryonic fibroblasts null for the transcriptional co-repressor Ski.

PubMed

Marcelain, Katherine; Armisen, Ricardo; Aguirre, Adam; Ueki, Nobuhide; Toro, Jessica; Colmenares, Clemencia; Hayman, Michael J

2012-01-01

Ski is a transcriptional regulator that has been considered an oncoprotein given its ability to induce oncogenic transformation in avian model systems. However, studies in mouse and in some human tumor cells have also indicated a tumor suppressor activity for this protein. We found that Ski-/- mouse embryo fibroblasts exhibit high levels of genome instability, namely aneuploidy, consistent with a tumor suppressor function for Ski. Time-lapse microscopy revealed lagging chromosomes and chromatin/chromosome bridges as the major cause of micronuclei (MN) formation and the subsequent aneuploidy. Although these cells arrested in mitosis after treatment with spindle disrupting drugs and exhibited a delayed metaphase/anaphase transition, spindle assembly checkpoint (SAC) was not sufficient to prevent chromosome missegregation, consistent with a weakened SAC. Our in vivo analysis also showed dynamic metaphase plate rearrangements with switches in polarity in cells arrested in metaphase. Importantly, after ectopic expression of Ski the cells that displayed this metaphase arrest died directly during metaphase or after aberrant cell division, relating SAC activation and mitotic cell death. This increased susceptibility to undergo mitosis-associated cell death reduced the number of MN-containing cells. The presented data support a new role for Ski in the mitotic process and in maintenance of genetic stability, providing insights into the mechanism of tumor suppression mediated by this protein. Copyright © 2011 Wiley Periodicals, Inc.

Progression of Mouse Skin Carcinogenesis Is Associated with Increased Erα Levels and Is Repressed by a Dominant Negative Form of Erα

PubMed Central

Michalopoulos, Ioannis; Sideridou, Maria; Tsimaratou, Katerina; Christodoulou, Ioannis; Pyrillou, Katerina; Gorgoulis, Vassilis; Vlahopoulos, Spiros; Zoumpourlis, Vassilis

2012-01-01

Estrogen receptors (ER), namely ERα and ERβ, are hormone-activated transcription factors with an important role in carcinogenesis. In the present study, we aimed at elucidating the implication of ERα in skin cancer, using chemically-induced mouse skin tumours, as well as cell lines representing distinct stages of mouse skin oncogenesis. First, using immunohistochemical staining we showed that ERα is markedly increased in aggressive mouse skin tumours in vivo as compared to the papilloma tumours, whereas ERβ levels are low and become even lower in the aggressive spindle tumours of carcinogen-treated mice. Then, using the multistage mouse skin carcinogenesis model, we showed that ERα gradually increases during promotion and progression stages of mouse skin carcinogenesis, peaking at the most aggressive stage, whereas ERβ levels only slightly change throughout skin carcinogenesis. Stable transfection of the aggressive, spindle CarB cells with a dominant negative form of ERα (dnERα) resulted in reduced ERα levels and reduced binding to estrogen responsive elements (ERE)-containing sequences. We characterized two highly conserved EREs on the mouse ERα promoter through which dnERα decreased endogenous ERα levels. The dnERα-transfected CarB cells presented altered protein levels of cytoskeletal and cell adhesion molecules, slower growth rate and impaired anchorage-independent growth in vitro, whereas they gave smaller tumours with extended latency period of tumour onset in vivo. Our findings suggest an implication of ERα in the aggressiveness of spindle mouse skin cancer cells, possibly through regulation of genes affecting cell shape and adhesion, and they also provide hints for the effective targeting of spindle cancer cells by dnERα. PMID:22870269

Flattop regulates basal body docking and positioning in mono- and multiciliated cells

PubMed Central

Gegg, Moritz; Böttcher, Anika; Burtscher, Ingo; Hasenoeder, Stefan; Van Campenhout, Claude; Aichler, Michaela; Walch, Axel; Grant, Seth G N; Lickert, Heiko

2014-01-01

Planar cell polarity (PCP) regulates basal body (BB) docking and positioning during cilia formation, but the underlying mechanisms remain elusive. In this study, we investigate the uncharacterized gene Flattop (Fltp) that is transcriptionally activated during PCP acquisition in ciliated tissues. Fltp knock-out mice show BB docking and ciliogenesis defects in multiciliated lung cells. Furthermore, Fltp is necessary for kinocilium positioning in monociliated inner ear hair cells. In these cells, the core PCP molecule Dishevelled 2, the BB/spindle positioning protein Dlg3, and Fltp localize directly adjacent to the apical plasma membrane, physically interact and surround the BB at the interface of the microtubule and actin cytoskeleton. Dlg3 and Fltp knock-outs suggest that both cooperatively translate PCP cues for BB positioning in the inner ear. Taken together, the identification of novel BB/spindle positioning components as potential mediators of PCP signaling might have broader implications for other cell types, ciliary disease, and asymmetric cell division. DOI: http://dx.doi.org/10.7554/eLife.03842.001 PMID:25296022

Characterization of Topographically Specific Sleep Spindles in Mice

PubMed Central

Kim, Dongwook; Hwang, Eunjin; Lee, Mina; Sung, Hokun; Choi, Jee Hyun

2015-01-01

Study Objective: Sleep spindles in humans have been classified as slow anterior and fast posterior spindles; recent findings indicate that their profiles differ according to pharmacology, pathology, and function. However, little is known about the generation mechanisms within the thalamocortical system for different types of spindles. In this study, we aim to investigate the electrophysiological behaviors of the topographically distinctive spindles within the thalamocortical system by applying high-density EEG and simultaneous thalamic LFP recordings in mice. Design: 32-channel extracranial EEG and 2-channel thalamic LFP were recorded simultaneously in freely behaving mice to acquire spindles during spontaneous sleep. Subjects: Hybrid F1 male mice of C57BL/6J and 129S4/svJae. Measurements and Results: Spindle events in each channel were detected by spindle detection algorithm, and then a cluster analysis was applied to classify the topographically distinctive spindles. All sleep spindles were successfully classified into 3 groups: anterior, posterior, and global spindles. Each spindle type showed distinct thalamocortical activity patterns regarding the extent of similarity, phase synchrony, and time lags between cortical and thalamic areas during spindle oscillation. We also found that sleep slow waves were likely to associate with all types of sleep spindles, but also that the ongoing cortical decruitment/recruitment dynamics before the onset of spindles and their relationship with spindle generation were also variable, depending on the spindle types. Conclusion: Topographically specific sleep spindles show distinctive thalamocortical network behaviors. Citation: Kim D, Hwang E, Lee M, Sung H, Choi JH. Characterization of topographically specific sleep spindles in mice. SLEEP 2015;38(1):85–96. PMID:25325451

Automated frequency analysis of synchronous and diffuse sleep spindles.

PubMed

Huupponen, Eero; Saastamoinen, Antti; Niemi, Jukka; Virkkala, Jussi; Hasan, Joel; Värri, Alpo; Himanen, Sari-Leena

2005-01-01

Sleep spindles have different properties in different localizations in the cortex. First main objective was to develop an amplitude-independent multi-channel spindle detection method. Secondly the method was applied to study the anteroposterior frequency differences of pure synchronous (visible bilaterally, either frontopolarly or centrally) and diffuse (visible bilaterally both frontopolarly and centrally) sleep spindles. A previously presented spindle detector based on the fuzzy reasoning principle and a level detector were combined to form a multi-channel spindle detector. The spindle detector had a 76.17% true positive rate and 0.93% false-positive rate. Pure central spindles were faster and pure frontal spindles were slower than diffuse spindles measured simultaneously from both locations. The study of frequency relations of spindles might give new information about thalamocortical sleep spindle generating mechanisms. Copyright (c) 2005 S. Karger AG, Basel.

Dynactin-dependent cortical dynein and spherical spindle shape correlate temporally with meiotic spindle rotation in Caenorhabditis elegans

PubMed Central

Crowder, Marina E.; Flynn, Jonathan R.; McNally, Karen P.; Cortes, Daniel B.; Price, Kari L.; Kuehnert, Paul A.; Panzica, Michelle T.; Andaya, Armann; Leary, Julie A.; McNally, Francis J.

2015-01-01

Oocyte meiotic spindles orient with one pole juxtaposed to the cortex to facilitate extrusion of chromosomes into polar bodies. In Caenorhabditis elegans, these acentriolar spindles initially orient parallel to the cortex and then rotate to the perpendicular orientation. To understand the mechanism of spindle rotation, we characterized events that correlated temporally with rotation, including shortening of the spindle in the pole-to pole axis, which resulted in a nearly spherical spindle at rotation. By analyzing large spindles of polyploid C. elegans and a related nematode species, we found that spindle rotation initiated at a defined spherical shape rather than at a defined spindle length. In addition, dynein accumulated on the cortex just before rotation, and microtubules grew from the spindle with plus ends outward during rotation. Dynactin depletion prevented accumulation of dynein on the cortex and prevented spindle rotation independently of effects on spindle shape. These results support a cortical pulling model in which spindle shape might facilitate rotation because a sphere can rotate without deforming the adjacent elastic cytoplasm. We also present evidence that activation of spindle rotation is promoted by dephosphorylation of the basic domain of p150 dynactin. PMID:26133383

Automated mitotic spindle tracking suggests a link between spindle dynamics, spindle orientation, and anaphase onset in epithelial cells

PubMed Central

Larson, Matthew E.; Bement, William M.

2017-01-01

Proper spindle positioning at anaphase onset is essential for normal tissue organization and function. Here we develop automated spindle-tracking software and apply it to characterize mitotic spindle dynamics in the Xenopus laevis embryonic epithelium. We find that metaphase spindles first undergo a sustained rotation that brings them on-axis with their final orientation. This sustained rotation is followed by a set of striking stereotyped rotational oscillations that bring the spindle into near contact with the cortex and then move it rapidly away from the cortex. These oscillations begin to subside soon before anaphase onset. Metrics extracted from the automatically tracked spindles indicate that final spindle position is determined largely by cell morphology and that spindles consistently center themselves in the XY-plane before anaphase onset. Finally, analysis of the relationship between spindle oscillations and spindle position relative to the cortex reveals an association between cortical contact and anaphase onset. We conclude that metaphase spindles in epithelia engage in a stereotyped “dance,” that this dance culminates in proper spindle positioning and orientation, and that completion of the dance is linked to anaphase onset. PMID:28100633

A unique hinge binder of extremely selective aminopyridine-based Mps1 (TTK) kinase inhibitors with cellular activity.

PubMed

Kusakabe, Ken-ichi; Ide, Nobuyuki; Daigo, Yataro; Itoh, Takeshi; Yamamoto, Takahiko; Kojima, Eiichi; Mitsuoka, Yasunori; Tadano, Genta; Tagashira, Sachie; Higashino, Kenichi; Okano, Yousuke; Sato, Yuji; Inoue, Makiko; Iguchi, Motofumi; Kanazawa, Takayuki; Ishioka, Yukichi; Dohi, Keiji; Kido, Yasuto; Sakamoto, Shingo; Ando, Shigeru; Maeda, Masahiro; Higaki, Masayo; Yoshizawa, Hidenori; Murai, Hitoshi; Nakamura, Yusuke

2015-05-01

Mps1, also known as TTK, is a dual-specificity kinase that regulates the spindle assembly check point. Increased expression levels of Mps1 are observed in cancer cells, and the expression levels correlate well with tumor grade. Such evidence points to selective inhibition of Mps1 as an attractive strategy for cancer therapeutics. Starting from an aminopyridine-based lead 3a that binds to a flipped-peptide conformation at the hinge region in Mps1, elaboration of the aminopyridine scaffold at the 2- and 6-positions led to the discovery of 19c that exhibited no significant inhibition for 287 kinases as well as improved cellular Mps1 and antiproliferative activities in A549 lung carcinoma cells (cellular Mps1 IC₅₀=5.3 nM, A549 IC₅₀=26 nM). A clear correlation between cellular Mps1 and antiproliferative IC₅₀ values indicated that the antiproliferative activity observed in A549 cells would be responsible for the cellular inhibition of Mps1. The X-ray structure of 19c in complex with Mps1 revealed that this compound retains the ability to bind to the peptide flip conformation. Finally, comparative analysis of the X-ray structures of 19c, a deamino analogue 33, and a known Mps1 inhibitor bound to Mps1 provided insights into the unique binding mode at the hinge region. Copyright © 2015 Elsevier Ltd. All rights reserved.

The small molecule inhibitor YK-4-279 disrupts mitotic progression of neuroblastoma cells, overcomes drug resistance and synergizes with inhibitors of mitosis.

PubMed

Kollareddy, Madhu; Sherrard, Alice; Park, Ji Hyun; Szemes, Marianna; Gallacher, Kelli; Melegh, Zsombor; Oltean, Sebastian; Michaelis, Martin; Cinatl, Jindrich; Kaidi, Abderrahmane; Malik, Karim

2017-09-10

Neuroblastoma is a biologically and clinically heterogeneous pediatric malignancy that includes a high-risk subset for which new therapeutic agents are urgently required. As well as MYCN amplification, activating point mutations of ALK and NRAS are associated with high-risk and relapsing neuroblastoma. As both ALK and RAS signal through the MEK/ERK pathway, we sought to evaluate two previously reported inhibitors of ETS-related transcription factors, which are transcriptional mediators of the Ras-MEK/ERK pathway in other cancers. Here we show that YK-4-279 suppressed growth and triggered apoptosis in nine neuroblastoma cell lines, while BRD32048, another ETV1 inhibitor, was ineffective. These results suggest that YK-4-279 acts independently of ETS-related transcription factors. Further analysis reveals that YK-4-279 induces mitotic arrest in prometaphase, resulting in subsequent cell death. Mechanistically, we show that YK-4-279 inhibits the formation of kinetochore microtubules, with treated cells showing a broad range of abnormalities including multipolar, fragmented and unseparated spindles, together leading to disrupted progression through mitosis. Notably, YK-4-279 does not affect microtubule acetylation, unlike the conventional mitotic poisons paclitaxel and vincristine. Consistent with this, we demonstrate that YK-4-279 overcomes vincristine-induced resistance in two neuroblastoma cell-line models. Furthermore, combinations of YK-4-279 with vincristine, paclitaxel or the Aurora kinase A inhibitor MLN8237/Alisertib show strong synergy, particularly at low doses. Thus, YK-4-279 could potentially be used as a single-agent or in combination therapies for the treatment of high-risk and relapsing neuroblastoma, as well as other cancers. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Further evidences for sleep instability and impaired spindle-delta dynamics in schizophrenia: a whole-night polysomnography study with neuroloop-gain and sleep-cycle analysis.

PubMed

Sasidharan, Arun; Kumar, Sunil; Nair, Ajay Kumar; Lukose, Ammu; Marigowda, Vrinda; John, John P; Kutty, Bindu M

2017-10-01

Sleep offers a unique window into the brain dysfunctions in schizophrenia. Many past sleep studies have reported abnormalities in both macro-sleep architecture (like increased awakenings) as well as micro-sleep-architecture (like spindle deficits) in patients with schizophrenia (PSZ). The present study attempts to replicate previous reports of macro- and micro-sleep-architectural abnormalities in schizophrenia. In addition, the study also examined sleep-stage changes and spindle-delta dynamics across sleep-cycles to provide further evidence in support of the dysfunctional thalamocortical mechanisms causing sleep instability and poor sleep maintenance associated with schizophrenia pathophysiology. Whole-night polysomnography was carried out among 45 PSZ and 39 age- and gender-matched healthy control subjects. Sleep-stage dynamics were assessed across sleep-cycles using a customized software algorithm. Spindle-delta dynamics across sleep-cycles were determined using neuroloop-gain analysis. PSZ showed macro-sleep architecture abnormalities such as prolonged sleeplessness, increased intermittent-awakenings, long sleep-onset latency, reduced non-rapid eye movement (NREM) stage 2 sleep, increased stage transitions, and poor sleep efficiency. They also showed reduced spindle density (sigma neuroloop-gain) but comparable slow wave density (delta neuroloop-gain) throughout the sleep. Sleep-cycle-wise analysis revealed transient features of sleep instability due to significantly increased intermittent awakenings especially in the first and third sleep-cycles, and unstable and recurrent stage transitions in both NREM (first sleep-cycle) and rapid eye movement (REM) sleep-periods (second sleep-cycle). Spindle deficits were persistent across the first three cycles and were positively correlated with sleep disruption during the subsequent REM sleep. In addition to replicating previously reported sleep deficits in PSZ, the current study showed subtle deficits in NREM-REM alterations across whole-night polysomnography. These results point towards a possible maladaptive interplay between unstable thalamocortical networks, resulting in sleep-cycle-specific instability patterns associated with schizophrenia pathophysiology. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

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.

The crack effect on instability in a machine tool spindle with gas bearings

NASA Astrophysics Data System (ADS)

Huang, Bo-Wun

2005-09-01

Gas-bearing spindles are required for increased spindle speed in precise machining. Due to manufacturing flaws or cyclic loading, cracks frequently appear in a rotating spindle systems. Cracks markedly affect the dynamic characteristics of rotating machinery. Hence, in this study, high-speed spindles with gas bearings and the crack effect on the instability dynamics are considered. Most investigations on dynamic characteristics of the spindle system were confined to ball-bearing-type spindles. This work examines the dynamic instability in a cracked rotating spindle system with gas bearings. A round Euler-Bernoulli beam is used to approximate the spindle. The Hamilton principle is applied to derive the equation of motion for the spindle system. The effects of crack depth, rotation speed and provided air pressure on the dynamic instability of a rotating spindle system are studied

Pneumo MSG-325 Lathe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rhorer, R.L.

1980-01-01

The LASL Shop Department has recently installed a Pneumo MSG-325 two-axis contouring lathe. This one-microinch resolution lathe, which utilizes both air-bearing spindle and air bearing slide ways, was purchased primarily for miniature work, but can also single point diamond turn metal optics.

Micromanipulation studies of the mitotic apparatus in sand dollar eggs.

PubMed

Hiramoto, Y; Nakano, Y

1988-01-01

Mechanical properties of the mitotic spindle and the effects of various operations of the mitotic apparatus on the chromosome movement and spindle elongation were investigated in fertilized eggs and blastomeres of the sand dollar, Clypeaster japonicus. On the basis of results with mechanical stretching and compression of the spindle with a pair of microneedles and the behavior of an oil drop microinjected into the spindle, it was concluded that the equatorial region of the spindle is mechanically weaker than the half-spindle region. Anaphase chromosome movement occurred in the spindle from which an aster had been removed or separated with its polar end and in the spindle in which the interzonal region had been removed. This fact indicates that chromosomes move poleward in anaphase by forces generated near the kinetochores in the half-spindle. Because of the effects of separation or removal of an aster from the spindle on the spindle elongation in anaphase and the behavior of the aster, it was concluded that the spindle elongation in anaphase is caused by pulling forces generated by asters attached to the ends of the spindle.

Thalamic Spindles Promote Memory Formation during Sleep through Triple Phase-Locking of Cortical, Thalamic, and Hippocampal Rhythms.

PubMed

Latchoumane, Charles-Francois V; Ngo, Hong-Viet V; Born, Jan; Shin, Hee-Sup

2017-07-19

While the interaction of the cardinal rhythms of non-rapid-eye-movement (NREM) sleep-the thalamo-cortical spindles, hippocampal ripples, and the cortical slow oscillations-is thought to be critical for memory consolidation during sleep, the role spindles play in this interaction is elusive. Combining optogenetics with a closed-loop stimulation approach in mice, we show here that only thalamic spindles induced in-phase with cortical slow oscillation up-states, but not out-of-phase-induced spindles, improve consolidation of hippocampus-dependent memory during sleep. Whereas optogenetically stimulated spindles were as efficient as spontaneous spindles in nesting hippocampal ripples within their excitable troughs, stimulation in-phase with the slow oscillation up-state increased spindle co-occurrence and frontal spindle-ripple co-occurrence, eventually resulting in increased triple coupling of slow oscillation-spindle-ripple events. In-phase optogenetic suppression of thalamic spindles impaired hippocampus-dependent memory. Our results suggest a causal role for thalamic sleep spindles in hippocampus-dependent memory consolidation, conveyed through triple coupling of slow oscillations, spindles, and ripples. Copyright © 2017 Elsevier Inc. All rights reserved.

Stability derivatives for bodies of revolution at subsonic speeds

NASA Technical Reports Server (NTRS)

Liu, D. D.; Platzer, M. F.; Ruo, S. Y.

1976-01-01

The paper considers a rigid pointed body of revolution in a steady uniform subsonic flow. The body performs harmonic small-amplitude pitching oscillations around its zero angle of attack position. The body is assumed to be smooth and sufficiently slender so that the small perturbation concept can be applied. The basis of the method used, following Revell (1960), is the relation of a body-fixed perturbation potential to the general velocity potential. Normal force distributions as well as total force and moment coefficients are calculated for parabolic spindles and the numerical results show good agreement between Revell's second-order slender body theory and the present theory for the static stability derivatives of the parabolic spindles.

Expression of microphthalmia transcription factor, S100 protein, and HMB-45 in malignant melanoma and pigmented nevi.

PubMed

Xia, Jianxin; Wang, Yanlong; Li, Fuqiu; Wang, Jinfeng; Mu, Yan; Mei, Xianglin; Li, Xue; Zhu, Wenjing; Jin, Xianhua; Yu, Kai

2016-09-01

Malignant melanoma (MM) is a type of malignant tumor, which originates from neural crest melanocytes. MM progresses rapidly and results in a high mortality rate. The present study aims to investigate the expression of microphthalmia transcription factor (MITF), the S100 protein, and HMB-45 in MM and pigmented nevi. A total of 32 MM samples (including three skin metastasis, three lymph node metastasis and two spindle cell MM samples), two Spitz nevus samples, four pigmented nevus samples and two blue nevus samples were collected. The expression levels of S100 protein, HMB-45, and MITF were observed via immunostaining. The S100 protein exhibited high positive rates in MM and pigment disorders (96.7 and 100%, respectively), but with low specificity. The S100 protein was also expressed in fibroblasts, myoepithelial cells, histocytes and Langerhans cells in normal skin samples. HMB-45 had high specificity. Its positive expression was only confined to MM cells and junctional nevus cells. Furthermore, HMB-45 was not expressed in melanocytes in the normal tissue samples around the tumor or in the benign intradermal nevus cells. MITF exhibited high specificity and high sensitivity. It was expressed in the nuclei of melanocytes, MM cells and nevus cells. It was observed to be strongly expressed in metastatic MM and spindle cell MMs. Thus, MITF may present as a specific immunomarker for the diagnosis and differential diagnosis of MM.

Sleep spindles in humans: insights from intracranial EEG and unit recordings

PubMed Central

Andrillon, Thomas; Nir, Yuval; Staba, Richard J.; Ferrarelli, Fabio; Cirelli, Chiara; Tononi, Giulio; Fried, Itzhak

2012-01-01

Sleep spindles are an electroencephalographic (EEG) hallmark of non-rapid eye movement (NREM) sleep and are believed to mediate many sleep-related functions, from memory consolidation to cortical development. Spindles differ in location, frequency, and association with slow waves, but whether this heterogeneity may reflect different physiological processes and potentially serve different functional roles remains unclear. Here we utilized a unique opportunity to record intracranial depth EEG and single-unit activity in multiple brain regions of neurosurgical patients to better characterize spindle activity in human sleep. We find that spindles occur across multiple neocortical regions, and less frequently also in the parahippocampal gyrus and hippocampus. Most spindles are spatially restricted to specific brain regions. In addition, spindle frequency is topographically organized with a sharp transition around the supplementary motor area between fast (13-15Hz) centroparietal spindles often occurring with slow wave up-states, and slow (9-12Hz) frontal spindles occurring 200ms later on average. Spindle variability across regions may reflect the underlying thalamocortical projections. We also find that during individual spindles, frequency decreases within and between regions. In addition, deeper sleep is associated with a reduction in spindle occurrence and spindle frequency. Frequency changes between regions, during individual spindles, and across sleep may reflect the same phenomenon, the underlying level of thalamocortical hyperpolarization. Finally, during spindles neuronal firing rates are not consistently modulated, although some neurons exhibit phase-locked discharges. Overall, anatomical considerations can account well for regional spindle characteristics, while variable hyperpolarization levels can explain differences in spindle frequency. PMID:22159098

Thalamocortical and intracortical laminar connectivity determines sleep spindle properties.

PubMed

Krishnan, Giri P; Rosen, Burke Q; Chen, Jen-Yung; Muller, Lyle; Sejnowski, Terrence J; Cash, Sydney S; Halgren, Eric; Bazhenov, Maxim

2018-06-27

Sleep spindles are brief oscillatory events during non-rapid eye movement (NREM) sleep. Spindle density and synchronization properties are different in MEG versus EEG recordings in humans and also vary with learning performance, suggesting spindle involvement in memory consolidation. Here, using computational models, we identified network mechanisms that may explain differences in spindle properties across cortical structures. First, we report that differences in spindle occurrence between MEG and EEG data may arise from the contrasting properties of the core and matrix thalamocortical systems. The matrix system, projecting superficially, has wider thalamocortical fanout compared to the core system, which projects to middle layers, and requires the recruitment of a larger population of neurons to initiate a spindle. This property was sufficient to explain lower spindle density and higher spatial synchrony of spindles in the superficial cortical layers, as observed in the EEG signal. In contrast, spindles in the core system occurred more frequently but less synchronously, as observed in the MEG recordings. Furthermore, consistent with human recordings, in the model, spindles occurred independently in the core system but the matrix system spindles commonly co-occurred with core spindles. We also found that the intracortical excitatory connections from layer III/IV to layer V promote spindle propagation from the core to the matrix system, leading to widespread spindle activity. Our study predicts that plasticity of intra- and inter-cortical connectivity can potentially be a mechanism for increased spindle density as has been observed during learning.

Human Nek7-interactor RGS2 is required for mitotic spindle organization

PubMed Central

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. PMID:25664600

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

PubMed Central

Ray, Laura B.; Sockeel, Stéphane; Soon, Melissa; Bore, Arnaud; Myhr, Ayako; Stojanoski, Bobby; Cusack, Rhodri; Owen, Adrian M.; Doyon, Julien; Fogel, Stuart M.

2015-01-01

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 60 s 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. PMID:26441604

Nap sleep spindle correlates of intelligence.

PubMed

Ujma, Péter P; Bódizs, Róbert; Gombos, Ferenc; Stintzing, Johannes; Konrad, Boris N; Genzel, Lisa; Steiger, Axel; Dresler, Martin

2015-11-26

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 fluid intelligence scores, however more recently it has been shown that only few sleep spindle measures correlate with intelligence in females, and none in males. Sleep spindle regulation underlies a circadian rhythm, however the association between spindles and intelligence has not been investigated in daytime nap sleep so far. In a sample of 86 healthy male human subjects, we investigated the correlation between fluid intelligence and sleep spindle parameters in an afternoon nap of 100 minutes. Mean sleep spindle length, amplitude and density were computed for each subject and for each derivation for both slow and fast spindles. A positive association was found between intelligence and slow spindle duration, but not any other sleep spindle parameter. As a positive correlation between intelligence and slow sleep spindle duration in full-night polysomnography has only been reported in females but not males, our results suggest that the association between intelligence and sleep spindles is more complex than previously assumed.

The Clathrin-dependent Spindle Proteome*

PubMed Central

Rao, Sushma R.; Flores-Rodriguez, Neftali; Page, Scott L.; Wong, Chin; Robinson, Phillip J.; Chircop, Megan

2016-01-01

The mitotic spindle is required for chromosome congression and subsequent equal segregation of sister chromatids. These processes involve a complex network of signaling molecules located at the spindle. The endocytic protein, clathrin, has a “moonlighting” role during mitosis, whereby it stabilizes the mitotic spindle. The signaling pathways that clathrin participates in to achieve mitotic spindle stability are unknown. Here, we assessed the mitotic spindle proteome and phosphoproteome in clathrin-depleted cells using quantitative MS/MS (data are available via ProteomeXchange with identifier PXD001603). We report a spindle proteome that consists of 3046 proteins and a spindle phosphoproteome consisting of 5157 phosphosites in 1641 phosphoproteins. Of these, 2908 (95.4%) proteins and 1636 (99.7%) phosphoproteins are known or predicted spindle-associated proteins. Clathrin-depletion from spindles resulted in dysregulation of 121 proteins and perturbed signaling to 47 phosphosites. The majority of these proteins increased in mitotic spindle abundance and six of these were validated by immunofluorescence microscopy. Functional pathway analysis confirmed the reported role of clathrin in mitotic spindle stabilization for chromosome alignment and highlighted possible new mechanisms of clathrin action. The data also revealed a novel second mitotic role for clathrin in bipolar spindle formation. PMID:27174698

The Clathrin-dependent Spindle Proteome.

PubMed

Rao, Sushma R; Flores-Rodriguez, Neftali; Page, Scott L; Wong, Chin; Robinson, Phillip J; Chircop, Megan

2016-08-01

The mitotic spindle is required for chromosome congression and subsequent equal segregation of sister chromatids. These processes involve a complex network of signaling molecules located at the spindle. The endocytic protein, clathrin, has a "moonlighting" role during mitosis, whereby it stabilizes the mitotic spindle. The signaling pathways that clathrin participates in to achieve mitotic spindle stability are unknown. Here, we assessed the mitotic spindle proteome and phosphoproteome in clathrin-depleted cells using quantitative MS/MS (data are available via ProteomeXchange with identifier PXD001603). We report a spindle proteome that consists of 3046 proteins and a spindle phosphoproteome consisting of 5157 phosphosites in 1641 phosphoproteins. Of these, 2908 (95.4%) proteins and 1636 (99.7%) phosphoproteins are known or predicted spindle-associated proteins. Clathrin-depletion from spindles resulted in dysregulation of 121 proteins and perturbed signaling to 47 phosphosites. The majority of these proteins increased in mitotic spindle abundance and six of these were validated by immunofluorescence microscopy. Functional pathway analysis confirmed the reported role of clathrin in mitotic spindle stabilization for chromosome alignment and highlighted possible new mechanisms of clathrin action. The data also revealed a novel second mitotic role for clathrin in bipolar spindle formation. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

A THERMODYNAMIC ANALYSIS OF MITOTIC SPINDLE EQUILIBRIUM AT ACTIVE METAPHASE

PubMed Central

Stephens, R. E.

1973-01-01

The mitotic apparatus of first-division metaphase eggs of the sea urchin Strongylocentrotus drobachiensis was observed by means of polarization microscopy under controlled temperature conditions. Eggs were fertilized and grown at two temperature extremes in order to produce two different sizes of available spindle pool. Slow division time allowed successive samples of such cells to be observed at the same point in metaphase but at different equilibrium temperatures, yielding curves of metaphase equilibrium birefringence vs. observational temperature. Using the plateau value of birefringence at higher temperatures as a measure of total available spindle pool and the observed birefringence at lower temperatures as a measure of polymerized material at equilibrium, the spindle protein association was evaluated according to the method of Inoué. Both pool conditions produced linear van't Hoff functions. Analysis of these functions yielded enthalpy and entropy changes of +55–65 kcal/mol and +197–233 entropy units (eu), respectively. These values for active mitotic metaphase are quite comparable to those obtained by Inoué and co-workers for arrested meiotic metaphase cells. When other equilibrium treatments were considered, the best fit to the experimental data was still that of Inoué, a treatment which theoretically involves first-order polymerization and dissociation kinetics. Treatment of metaphase cells with D2O by direct immersion drove the equilibrium to completion regardless of temperature, attaining or exceeding a birefringence value equal to the cell's characteristic pool size; perfusion with D2O appeared to erase the original temperature-determined pool size differences for the two growth conditions, attaining a maximum value characteristic of the larger pool condition. These data confirm Inoué's earlier contention that D2O treatment can modify the available spindle pool. PMID:4734864

Decoding the principles underlying the frequency of association with nucleoli for RNA polymerase III-transcribed genes in budding yeast.

PubMed

Belagal, Praveen; Normand, Christophe; Shukla, Ashutosh; Wang, Renjie; Léger-Silvestre, Isabelle; Dez, Christophe; Bhargava, Purnima; Gadal, Olivier

2016-10-15

The association of RNA polymerase III (Pol III)-transcribed genes with nucleoli seems to be an evolutionarily conserved property of the spatial organization of eukaryotic genomes. However, recent studies of global chromosome architecture in budding yeast have challenged this view. We used live-cell imaging to determine the intranuclear positions of 13 Pol III-transcribed genes. The frequency of association with nucleolus and nuclear periphery depends on linear genomic distance from the tethering elements-centromeres or telomeres. Releasing the hold of the tethering elements by inactivating centromere attachment to the spindle pole body or changing the position of ribosomal DNA arrays resulted in the association of Pol III-transcribed genes with nucleoli. Conversely, ectopic insertion of a Pol III-transcribed gene in the vicinity of a centromere prevented its association with nucleolus. Pol III-dependent transcription was independent of the intranuclear position of the gene, but the nucleolar recruitment of Pol III-transcribed genes required active transcription. We conclude that the association of Pol III-transcribed genes with the nucleolus, when permitted by global chromosome architecture, provides nucleolar and/or nuclear peripheral anchoring points contributing locally to intranuclear chromosome organization. © 2016 Belagal et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Synchronization and Propagation of Global Sleep Spindles

PubMed Central

de Souza, Rafael Toledo Fernandes; Gerhardt, Günther Johannes Lewczuk; Schönwald, Suzana Veiga; Rybarczyk-Filho, José Luiz; Lemke, Ney

2016-01-01

Sleep spindles occur thousands of times during normal sleep and can be easily detected by visual inspection of EEG signals. These characteristics make spindles one of the most studied EEG structures in mammalian sleep. In this work we considered global spindles, which are spindles that are observed simultaneously in all EEG channels. We propose a methodology that investigates both the signal envelope and phase/frequency of each global spindle. By analysing the global spindle phase we showed that 90% of spindles synchronize with an average latency time of 0.1 s. We also measured the frequency modulation (chirp) of global spindles and found that global spindle chirp and synchronization are not correlated. By investigating the signal envelopes and implementing a homogeneous and isotropic propagation model, we could estimate both the signal origin and velocity in global spindles. Our results indicate that this simple and non-invasive approach could determine with reasonable precision the spindle origin, and allowed us to estimate a signal speed of 0.12 m/s. Finally, we consider whether synchronization might be useful as a non-invasive diagnostic tool. PMID:26963102

Transcription and ncRNAs: at the cent(rome)re of kinetochore assembly and maintenance.

PubMed

Scott, Kristin C

2013-12-01

Centromeres are sites of chromosomal spindle attachment during mitosis and meiosis. Centromeres are defined, in part, by a distinct chromatin landscape in which histone H3 is replaced by the conserved histone H3 variant, CENP-A. Sequences competent for centromere formation and function vary among organisms and are typically composed of repetitive DNA. It is unclear how such diverse genomic signals are integrated with the epigenetic mechanisms that govern CENP-A incorporation at a single locus on each chromosome. Recent work highlights the intriguing possibility that the transcriptional properties of centromeric core DNA contribute to centromere identity and maintenance through cell division. Moreover, core-derived noncoding RNAs (ncRNAs) have emerged as active participants in the regulation and control of centromere activity in plants and mammals. This paper reviews the transcriptional properties of eukaryotic centromeres and discusses the known roles of core-derived ncRNAs in chromatin integrity, kinetochore assembly, and centromere activity.

Topographic and sex-related differences in sleep spindles in major depressive disorder: a high-density EEG investigation.

PubMed

Plante, D T; Goldstein, M R; Landsness, E C; Peterson, M J; Riedner, B A; Ferrarelli, F; Wanger, T; Guokas, J J; Tononi, G; Benca, R M

2013-03-20

Sleep spindles are believed to mediate several sleep-related functions including maintaining disconnection from the external environment during sleep, cortical development, and sleep-dependent memory consolidation. Prior studies that have examined sleep spindles in major depressive disorder (MDD) have not demonstrated consistent differences relative to control subjects, which may be due to sex-related variation and limited spatial resolution of spindle detection. Thus, this study sought to characterize sleep spindles in MDD using high-density electroencephalography (hdEEG) to examine the topography of sleep spindles across the cortex in MDD, as well as sex-related variation in spindle topography in the disorder. All-night hdEEG recordings were collected in 30 unipolar MDD participants (19 women) and 30 age and sex-matched controls. Topography of sleep spindle density, amplitude, duration, and integrated spindle activity (ISA) were assessed to determine group differences. Spindle parameters were compared between MDD and controls, including analysis stratified by sex. As a group, MDD subjects demonstrated significant increases in frontal and parietal spindle density and ISA compared to controls. When stratified by sex, MDD women demonstrated increases in frontal and parietal spindle density, amplitude, duration, and ISA; whereas MDD men demonstrated either no differences or decreases in spindle parameters. Given the number of male subjects, this study may be underpowered to detect differences in spindle parameters in male MDD participants. This study demonstrates topographic and sex-related differences in sleep spindles in MDD. Further research is warranted to investigate the role of sleep spindles and sex in the pathophysiology of MDD. Copyright © 2012 Elsevier B.V. All rights reserved.

Coordination of Slow Waves With Sleep Spindles Predicts Sleep-Dependent Memory Consolidation in Schizophrenia.

PubMed

Demanuele, Charmaine; Bartsch, Ullrich; Baran, Bengi; Khan, Sheraz; Vangel, Mark G; Cox, Roy; Hämäläinen, Matti; Jones, Matthew W; Stickgold, Robert; Manoach, Dara S

2017-01-01

Schizophrenia patients have correlated deficits in sleep spindle density and sleep-dependent memory consolidation. In addition to spindle density, memory consolidation is thought to rely on the precise temporal coordination of spindles with slow waves (SWs). We investigated whether this coordination is intact in schizophrenia and its relation to motor procedural memory consolidation. Twenty-one chronic medicated schizophrenia patients and 17 demographically matched healthy controls underwent two nights of polysomnography, with training on the finger tapping motor sequence task (MST) on the second night and testing the following morning. We detected SWs (0.5-4 Hz) and spindles during non-rapid eye movement (NREM) sleep. We measured SW-spindle phase-amplitude coupling and its relation with overnight improvement in MST performance. Patients did not differ from controls in the timing of SW-spindle coupling. In both the groups, spindles peaked during the SW upstate. For patients alone, the later in the SW upstate that spindles peaked and the more reliable this phase relationship, the greater the overnight MST improvement. Regression models that included both spindle density and SW-spindle coordination predicted overnight improvement significantly better than either parameter alone, suggesting that both contribute to memory consolidation. Schizophrenia patients show intact spindle-SW temporal coordination, and these timing relationships, together with spindle density, predict sleep-dependent memory consolidation. These relations were seen only in patients suggesting that their memory is more dependent on optimal spindle-SW timing, possibly due to reduced spindle density. Interventions to improve memory may need to increase spindle density while preserving or enhancing the coordination of NREM oscillations. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

A microtubule polymerase cooperates with the kinesin-6 motor and a microtubule cross-linker to promote bipolar spindle assembly in the absence of kinesin-5 and kinesin-14 in fission yeast

PubMed Central

Yukawa, Masashi; Kawakami, Tomoki; Okazaki, Masaki; Kume, Kazunori; Tang, Ngang Heok; Toda, Takashi

2017-01-01

Accurate chromosome segregation relies on the bipolar mitotic spindle. In many eukaryotes, spindle formation is driven by the plus-end–directed motor kinesin-5 that generates outward force to establish spindle bipolarity. Its inhibition leads to the emergence of monopolar spindles with mitotic arrest. Intriguingly, simultaneous inactivation of the minus-end–directed motor kinesin-14 restores spindle bipolarity in many systems. Here we show that in fission yeast, three independent pathways contribute to spindle bipolarity in the absence of kinesin-5/Cut7 and kinesin-14/Pkl1. One is kinesin-6/Klp9 that engages with spindle elongation once short bipolar spindles assemble. Klp9 also ensures the medial positioning of anaphase spindles to prevent unequal chromosome segregation. Another is the Alp7/TACC-Alp14/TOG microtubule polymerase complex. Temperature-sensitive alp7cut7pkl1 mutants are arrested with either monopolar or very short spindles. Forced targeting of Alp14 to the spindle pole body is sufficient to render alp7cut7pkl1 triply deleted cells viable and promote spindle assembly, indicating that Alp14-mediated microtubule polymerization from the nuclear face of the spindle pole body could generate outward force in place of Cut7 during early mitosis. The third pathway involves the Ase1/PRC1 microtubule cross-linker that stabilizes antiparallel microtubules. Our study, therefore, unveils multifaceted interplay among kinesin-dependent and -independent pathways leading to mitotic bipolar spindle assembly. PMID:29021344

The p90 ribosomal S6 kinase 2 specifically affects mitotic progression by regulating the basal level, distribution and stability of mitotic spindles

PubMed Central

Park, Yun Yeon; Nam, Hyun-Ja; Do, Mihyang; Lee, Jae-Ho

2016-01-01

RSK2, also known as RPS6KA3 (ribosomal protein S6 kinase, 90 kDa, polypeptide 3), is a downstream kinase of the mitogen-activated protein kinase (MAPK) pathway, which is important in regulating survival, transcription, growth and proliferation. However, its biological role in mitotic progression is not well understood. In this study, we examined the potential involvement of RSK2 in the regulation of mitotic progression. Interestingly, depletion of RSK2, but not RSK1, caused the accumulation of mitotic cells. Time-lapse analysis revealed that mitotic duration, particularly the duration for metaphase-to-anaphase transition was prolonged in RSK2-depleted cells, suggesting activation of spindle assembly checkpoint (SAC). Indeed, more BubR1 (Bub1-related kinase) was present on metaphase plate kinetochores in RSK2-depleted cells, and depletion of BubR1 abolished the mitotic accumulation caused by RSK2 depletion, confirming BubR1-dependent SAC activation. Along with the shortening of inter-kinetochore distance, these data suggested that weakening of the tension across sister kinetochores by RSK2 depletion led to the activation of SAC. To test this, we analyzed the RSK2 effects on the stability of kinetochore–microtubule interactions, and found that RSK2-depleted cells formed less kinetochore–microtubule fibers. Moreover, RSK2 depletion resulted in the decrease of basal level of microtubule as well as an irregular distribution of mitotic spindles, which might lead to observed several mitotic progression defects such as increase in unaligned chromosomes, defects in chromosome congression and a decrease in pole-to-pole distance in these cells. Taken together, our data reveal that RSK2 affects mitotic progression by regulating the distribution, basal level and the stability of mitotic spindles. PMID:27491410

Torque-balanced vibrationless rotary coupling

DOEpatents

Miller, Donald M.

1980-01-01

This disclosure describes a torque-balanced vibrationless rotary coupling for transmitting rotary motion without unwanted vibration into the spindle of a machine tool. A drive member drives a driven member using flexible connecting loops which are connected tangentially and at diametrically opposite connecting points through a free floating ring.

The Spindle Cell Neoplasms of the Oral Cavity.

PubMed

Shamim, Thorakkal

2015-01-01

Spindle cell neoplasms are defined as neoplasms that consist of spindle-shaped cells in the histopathology. Spindle cell neoplasms can affect the oral cavity. In the oral cavity, the origin of the spindle cell neoplasms may be traced to epithelial, mesenchymal and odontogenic components. This article aims to review the spindle cell neoplasms of the oral cavity with emphasis on histopathology.

The Spindle Cell Neoplasms of the Oral Cavity

PubMed Central

Shamim, Thorakkal

2015-01-01

Spindle cell neoplasms are defined as neoplasms that consist of spindle-shaped cells in the histopathology. Spindle cell neoplasms can affect the oral cavity. In the oral cavity, the origin of the spindle cell neoplasms may be traced to epithelial, mesenchymal and odontogenic components. This article aims to review the spindle cell neoplasms of the oral cavity with emphasis on histopathology. PMID:26351482

Maternal RNA regulates Aurora C kinase during mouse oocyte maturation in a translation-independent fashion.

PubMed

Balboula, Ahmed Z; Blengini, Cecilia S; Gentilello, Amanda S; Takahashi, Masashi; Schindler, Karen

2017-06-01

During oocyte meiotic maturation, Aurora kinase C (AURKC) is required to accomplish many critical functions including destabilizing erroneous kinetochore-microtubule (K-MT)attachments and regulating bipolar spindle assembly. How localized activity of AURKC is regulated in mammalian oocytes, however, is not fully understood. Female gametes from many species, including mouse, contain stores of maternal transcripts that are required for downstream developmental events. We show here that depletion of maternal RNA in mouse oocytes resulted in impaired meiotic progression, increased incidence of chromosome misalignment and abnormal spindle formation at metaphase I (Met I), and cytokinesis defects. Importantly, depletion of maternal RNA perturbed the localization and activity of AURKC within the chromosomal passenger complex (CPC). These perturbations were not observed when translation was inhibited by cycloheximide (CHX) treatment. These results demonstrate a translation-independent function of maternal RNA to regulate AURKC-CPC function in mouse oocytes. © The Authors 2017. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Physiological and ultrastructural analysis of elongating mitotic spindles reactivated in vitro

PubMed Central

1986-01-01

We have developed a simple procedure for isolating mitotic spindles from the diatom Stephanopyxis turris and have shown that they undergo anaphase spindle elongation in vitro upon addition of ATP. The isolated central spindle is a barrel-shaped structure with a prominent zone of microtubule overlap. After ATP addition greater than 75% of the spindle population undergoes distinct structural rearrangements: the spindles on average are longer and the two half-spindles are separated by a distinct gap traversed by only a small number of microtubules, the phase-dense material in the overlap zone is gone, and the peripheral microtubule arrays have depolymerized. At the ultrastructural level, we examined serial cross-sections of spindles after 1-, 5-, and 10-min incubations in reactivation medium. Microtubule depolymerization distal to the poles is confirmed by the increased number of incomplete, i.e., c-microtubule profiles specifically located in the region of overlap. After 10 min we see areas of reduced microtubule number which correspond to the gaps seen in the light microscope and an overall reduction in the number of half-spindle microtubules to about one-third the original number. The changes in spindle structure are highly specific for ATP, are dose-dependent, and do not occur with nonhydrolyzable nucleotide analogues. Spindle elongation and gap formation are blocked by 10 microM vanadate, equimolar mixtures of ATP and AMPPNP, and by sulfhydryl reagents. This process is not affected by nocodazole, erythro-9-[3-(2-hydroxynonyl)]adenine, cytochalasin D, and phalloidin. In the presence of taxol, the extent of spindle elongation is increased; however, distinct gaps still form between the two half- spindles. These results show that the response of isolated spindles to ATP is a complex process consisting of several discrete steps including initiation events, spindle elongation mechanochemistry, controlled central spindle microtubule plus-end depolymerization, and loss of peripheral microtubules. They also show that the microtubule overlap zone is an important site of ATP action and suggest that spindle elongation in vitro is best explained by a mechanism of microtubule- microtubule sliding. Spindle elongation in vitro cannot be accounted for by cytoplasmic forces pulling on the poles or by microtubule polymerization. PMID:3733882

A defect-driven diagnostic method for machine tool spindles

PubMed Central

Vogl, Gregory W.; Donmez, M. Alkan

2016-01-01

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. PMID:28065985

Differential Diagnosis of Benign Spindle Cell Lesions.

PubMed

Magro, Gaetano

2018-03-01

Spindle cell lesions of the breast cover a wide spectrum of diseases ranging from reactive tumor-like lesions to high-grade malignant tumors. The recognition of the benign spindle cell tumor-like lesions (nodular fasciitis; reactive spindle cell nodule after biopsy, inflammatory pseudotumor/inflammatory myofibroblastic tumor; fascicular variant of pseudoangiomatous stromal hyperplasia) and tumors (myofibroblastoma, benign fibroblastic spindle cell tumor, leiomyoma, schwannoma, spindle cell lipoma, solitary fibrous tumor, myxoma) is crucial to avoid confusion with morphologically similar but more aggressive bland-appearing spindle cell tumors, such as desmoid-type fibromatosis, low-grade (fibromatosis-like) spindle cell carcinoma, low-grade fibrosarcoma/myofibroblastic sarcoma and dermatofibrosarcoma protuberans. Copyright © 2017 Elsevier Inc. All rights reserved.

Heterogeneous Origins of Human Sleep Spindles in Different Cortical Layers.

PubMed

Hagler, Donald J; Ulbert, István; Wittner, Lucia; Erőss, Loránd; Madsen, Joseph R; Devinsky, Orrin; Doyle, Werner; Fabó, Dániel; Cash, Sydney S; Halgren, Eric

2018-03-21

Sleep spindles are a cardinal feature in human NREM sleep and may be important for memory consolidation. We studied the intracortical organization of spindles in men and women by recording spontaneous sleep spindles from different cortical layers using linear microelectrode arrays. Two patterns of spindle generation were identified using visual inspection, and confirmed with factor analysis. Spindles (10-16 Hz) were largest and most common in upper and middle channels, with limited involvement of deep channels. Many spindles were observed in only upper or only middle channels, but approximately half occurred in both. In spindles involving both middle and upper channels, the spindle envelope onset in middle channels led upper by ∼25-50 ms on average. The phase relationship between spindle waves in upper and middle channels varied dynamically within spindle epochs, and across individuals. Current source density analysis demonstrated that upper and middle channel spindles were both generated by an excitatory supragranular current sink while an additional deep source was present for middle channel spindles only. Only middle channel spindles were accompanied by deep low (25-50 Hz) and high (70-170 Hz) gamma activity. These results suggest that upper channel spindles are generated by supragranular pyramids, and middle channel by infragranular. Possibly, middle channel spindles are generated by core thalamocortical afferents, and upper channel by matrix. The concurrence of these patterns could reflect engagement of cortical circuits in the integration of more focal (core) and distributed (matrix) aspects of memory. These results demonstrate that at least two distinct intracortical systems generate human sleep spindles. SIGNIFICANCE STATEMENT Bursts of ∼14 Hz oscillations, lasting ∼1 s, have been recognized for over 80 years as cardinal features of mammalian sleep. Recent findings suggest that they play a key role in organizing cortical activity during memory consolidation. We used linear microelectrode arrays to study their intracortical organization in humans. We found that spindles could be divided into two types. One mainly engages upper layers of the cortex, which are considered to be specialized for associative activity. The other engages both upper and middle layers, including those devoted to sensory input. The interaction of these two spindle types may help organize the interaction of sensory and associative aspects of memory consolidation. Copyright © 2018 the authors 0270-6474/18/383013-13$15.00/0.

78 FR 46933 - Combined Notice of Filings #1

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-02

... Power Act of Saja Energy LLC. Filed Date: 7/24/13. Accession Number: 20130724-5109. Comments Due: 5 p.m.... Applicants: Eagle Point Power Generation LLC, Hazle Spindle, LLC, La Paloma Generating Company, LLC, RC Cape...-001. Applicants: Public Service Company of New Mexico. Description: WestConnect Regional Transmission...

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

PubMed Central

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

Self-organization mechanisms in the assembly and maintenance of bipolar spindles

NASA Astrophysics Data System (ADS)

Burbank, Kendra Stewart

Anastral, meiotic spindles are thought to be organized differently from astral, mitotic spindles, but the field has lacked basic structural information required to describe and model them, including the location of microtubule nucleating sites and minus ends. How the various components of spindles act together to establish and maintain the dynamic bipolar structure of spindles is not understood. We measure the distributions of oriented microtubules (MTs) in metaphase anastral spindles in Xenopus extracts by fluorescence speckle microscopy and cross-correlation analysis. We localized plus ends by tubulin incorporation and combined this with the orientation data to infer the localization of minus ends. We find that minus ends are localized throughout the spindle, sparsely at the equator and at higher concentrations near the poles. This dads to the surprising conclusion that spindles contained many short MTs, not connected to the spindle poles. Based on these data, we propose a slide-and-cluster model based on four known molecular activities: MT nucleation near chromosomes, the sliding of MTs by a plus-enddirected motor, the clustering of their minus ends by a minus-end-directed motor, and the loss of MTs by dynamic instability. This work demonstrates how the interplay between two types of motors together with continual nucleation of MTs by chromosomes could organize the MTs into spindles. Our model applies to overlapping, nonkinetochore MTs in anastral spindles, and perhaps also to interpolar MTs in astral spindles. We show mathematically that the slide-and-cluster mechanism robustly forms bipolar spindles a stable steady-state length, sometimes with sharp poles. This model accounts for several experimental observations that were difficult to explain with existing models, and is the first self contained model for anastral spindle assembly, MT sliding (known as poleward flux), and spindle bistability. Our experimental results support the slide-and-cluster scenario; most significantly, we find that MT sliding slows near spindle poles, confirming the models primary prediction.

Physical limits on kinesin-5–mediated chromosome congression in the smallest mitotic spindles

PubMed Central

McCoy, Kelsey M.; Tubman, Emily S.; Claas, Allison; Tank, Damien; Clancy, Shelly Applen; O’Toole, Eileen T.; Berman, Judith; Odde, David J.

2015-01-01

A characteristic feature of mitotic spindles is the congression of chromosomes near the spindle equator, a process mediated by dynamic kinetochore microtubules. A major challenge is to understand how precise, submicrometer-scale control of kinetochore micro­tubule dynamics is achieved in the smallest mitotic spindles, where the noisiness of microtubule assembly/disassembly will potentially act to overwhelm the spatial information that controls microtubule plus end–tip positioning to mediate congression. To better understand this fundamental limit, we conducted an integrated live fluorescence, electron microscopy, and modeling analysis of the polymorphic fungal pathogen Candida albicans, which contains one of the smallest known mitotic spindles (<1 μm). Previously, ScCin8p (kinesin-5 in Saccharomyces cerevisiae) was shown to mediate chromosome congression by promoting catastrophe of long kinetochore microtubules (kMTs). Using C. albicans yeast and hyphal kinesin-5 (Kip1p) heterozygotes (KIP1/kip1∆), we found that mutant spindles have longer kMTs than wild-type spindles, consistent with a less-organized spindle. By contrast, kinesin-8 heterozygous mutant (KIP3/kip3∆) spindles exhibited the same spindle organization as wild type. Of interest, spindle organization in the yeast and hyphal states was indistinguishable, even though yeast and hyphal cell lengths differ by two- to fivefold, demonstrating that spindle length regulation and chromosome congression are intrinsic to the spindle and largely independent of cell size. Together these results are consistent with a kinesin-5–mediated, length-dependent depolymerase activity that organizes chromosomes at the spindle equator in C. albicans to overcome fundamental noisiness in microtubule self-assembly. More generally, we define a dimensionless number that sets a fundamental physical limit for maintaining congression in small spindles in the face of assembly noise and find that C. albicans operates very close to this limit, which may explain why it has the smallest known mitotic spindle that still manifests the classic congression architecture. PMID:26354423

Analysis and topology optimization design of high-speed driving spindle

NASA Astrophysics Data System (ADS)

Wang, Zhilin; Yang, Hai

2018-04-01

The three-dimensional model of high-speed driving spindle is established by using SOLIDWORKS. The model is imported through the interface of ABAQUS, A finite element analysis model of high-speed driving spindle was established by using spring element to simulate bearing boundary condition. High-speed driving spindle for the static analysis, the spindle of the stress, strain and displacement nephogram, and on the basis of the results of the analysis on spindle for topology optimization, completed the lightweight design of high-speed driving spindle. The design scheme provides guidance for the design of axial parts of similar structures.

Electronically controlled cable wrapper

DOEpatents

Young, Thomas M.

1984-01-01

A spindle assembly engages and moves along a length of cable to be wrapped with insulating tape. Reels of insulating tape are mounted on a outer rotatable spindle which revolves around the cable to dispense insulating tape. The rate of movement of the spindle assembly along the length of the cable is controlled by a stepper motor which is programmably synchronized to the rate at which rotatable spindle wraps the cable. The stepper motor drives a roller which engages the cable and moves the spindle assembly along the length of the cable as it is being wrapped. The spindle assembly is mounted at the end of an articulated arm which allows free movement of the spindle assembly and allows the spindle assembly to follow lateral movement of the cable.

Electronically controlled cable wrapper

DOEpatents

Young, T.M.

1982-08-17

A spindle assembly engages and moves along a length of cable to be wrapped with insulating tape. Reels of insulating tape are mounted on a outer rotatable spindle which revolves around the cable to dispense insulating tape. The rate of movement of the spindle assembly along the length of the cable is controlled by a stepper motor which is programmably synchronized to the rate at which rotatable spindle wraps the cable. The stepper motor drives a roller which engages the cable and moves the spindle assembly along the length of the cable as it is being wrapped. The spindle assembly is mounted at the end of an articulated arm which allows free movement of the spindle assembly and allows the spindle assembly to follow lateral movement of the cable.

The 5α-reductase inhibitor finasteride is not associated with alterations in sleep spindles in men referred for polysomnography

PubMed Central

Goldstein, Michael R.; Cook, Jesse D.; Plante, David T.

2015-01-01

Objective Endogenous neurosteroids that potentiate the GABAA receptor are thought to enhance the generation of sleep spindles. This study tested the hypothesis that the 5α-reductase inhibitor finasteride, an agent associated with reductions in neurosteroids, would be associated with reduced sleep spindles in men referred for polysomnography. Methods Spectral analysis and spindle waveform detection were performed on electroencephalographic (EEG) sleep data in the 11–16Hz sigma band, as well as several subranges, from 27 men taking finasteride and 27 matched comparison patients (ages 18 to 81 years). Results No significant differences between groups were observed for spectral power or sleep spindle morphology measures, including spindle density, amplitude, duration, and integrated spindle activity. Conclusions Contrary to our hypothesis, these findings demonstrate that finasteride is not associated with alterations in sleep spindle range activity or spindle morphology parameters. PMID:26494125

Development of a walleye spleen stromal cell line sensitive to viral hemorrhagic septicemia virus (VHSV IVb) and to protection by synthetic dsRNA.

PubMed

Vo, Nguyen T K; Bender, Aaron W; Ammendolia, Dustin A; Lumsden, John S; Dixon, Brian; Bols, Niels C

2015-07-01

A cell line, WE-spleen6, has been developed from the stromal layer of primary spleen cell cultures. On conventional plastic, WE-spleen6 cells had a spindle-shaped morphology at low cell density but grew to become epithelial-like at confluency. On the commercial extracellular matrix (ECM), Matrigel, the cells remained spindle-shaped and formed lumen-like structures. WE-spleen6 cells had intermediate filament protein, vimentin and the ECM protein, collagen I, but not smooth muscle α-actin (SMA) and von Willebrand factor (vWF) and lacked alkaline phosphatase and phagocytic activities. WE-spleen6 was more susceptible to infection with VHSV IVb than a fibroblast and epithelial cell lines from the walleye caudal fin, WE-cfin11f and WE-cfin11e, respectively. Viral transcripts and proteins appeared earlier in WE-spleen6 cultures as did cytopathic effect (CPE) and significant virus production. The synthetic double-stranded RNA (dsRNA), polyinosinic: polycytidylic acid (pIC), induced the antiviral protein Mx in both cell lines. Treating WE-spleen6 cultures with pIC prior to infection with VHSV IVb inhibited the early accumulation of viral transcripts and proteins and delayed the appearance of CPE and significant viral production. Of particular note, pIC caused the disappearance of viral P protein 2 days post infection. WE-spleen6 should be useful for investigating the impact of VHSV IVb on hematopoietic organs and the actions of pIC on the rhabdovirus life cycle. Copyright © 2015 Elsevier Ltd. All rights reserved.

Checkpoints couple transcription network oscillator dynamics to cell-cycle progression.

PubMed

Bristow, Sara L; Leman, Adam R; Simmons Kovacs, Laura A; Deckard, Anastasia; Harer, John; Haase, Steven B

2014-09-05

The coupling of cyclin dependent kinases (CDKs) to an intrinsically oscillating network of transcription factors has been proposed to control progression through the cell cycle in budding yeast, Saccharomyces cerevisiae. The transcription network regulates the temporal expression of many genes, including cyclins, and drives cell-cycle progression, in part, by generating successive waves of distinct CDK activities that trigger the ordered program of cell-cycle events. Network oscillations continue autonomously in mutant cells arrested by depletion of CDK activities, suggesting the oscillator can be uncoupled from cell-cycle progression. It is not clear what mechanisms, if any, ensure that the network oscillator is restrained when progression in normal cells is delayed or arrested. A recent proposal suggests CDK acts as a master regulator of cell-cycle processes that have the potential for autonomous oscillatory behavior. Here we find that mitotic CDK is not sufficient for fully inhibiting transcript oscillations in arrested cells. We do find that activation of the DNA replication and spindle assembly checkpoints can fully arrest the network oscillator via overlapping but distinct mechanisms. Further, we demonstrate that the DNA replication checkpoint effector protein, Rad53, acts to arrest a portion of transcript oscillations in addition to its role in halting cell-cycle progression. Our findings indicate that checkpoint mechanisms, likely via phosphorylation of network transcription factors, maintain coupling of the network oscillator to progression during cell-cycle arrest.

A Land Plant-Specific Transcription Factor Directly Enhances Transcription of a Pathogenic Noncoding RNA Template by DNA-Dependent RNA Polymerase II[OPEN

PubMed Central

Qu, Jie; Ji, Shaoyi; Wallace, Andrew J.; Wu, Jian; Li, Yi; Gopalan, Venkat; Ding, Biao

2016-01-01

Some DNA-dependent RNA polymerases (DdRPs) possess RNA-dependent RNA polymerase activity, as was first discovered in the replication of Potato spindle tuber viroid (PSTVd) RNA genome in tomato (Solanum lycopersicum). Recent studies revealed that this activity in bacteria and mammals is important for transcriptional and posttranscriptional regulatory mechanisms. Here, we used PSTVd as a model to uncover auxiliary factors essential for RNA-templated transcription by DdRP. PSTVd replication in the nucleoplasm generates (−)-PSTVd intermediates and (+)-PSTVd copies. We found that the Nicotiana benthamiana canonical 9-zinc finger (ZF) Transcription Factor IIIA (TFIIIA-9ZF) as well as its variant TFIIIA-7ZF interacted with (+)-PSTVd, but only TFIIIA-7ZF interacted with (−)-PSTVd. Suppression of TFIIIA-7ZF reduced PSTVd replication, and overexpression of TFIIIA-7ZF enhanced PSTVd replication in planta. Consistent with the locale of PSTVd replication, TFIIIA-7ZF was found in the nucleoplasm and nucleolus, in contrast to the strictly nucleolar localization of TFIIIA-9ZF. Footprinting assays revealed that only TFIIIA-7ZF bound to a region of PSTVd critical for initiating transcription. Furthermore, TFIIIA-7ZF strongly enhanced the in vitro transcription of circular (+)-PSTVd by partially purified Pol II. Together, our results identify TFIIIA-7ZF as a dedicated cellular transcription factor that acts in DdRP-catalyzed RNA-templated transcription, highlighting both the extraordinary evolutionary adaptation of viroids and the potential of DdRPs for a broader role in cellular processes. PMID:27113774

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

PubMed

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).

Comparison of a Four-Section Spindle and Stomacher for Efficacy of Detaching Microorganisms from Fresh Vegetables.

PubMed

Kim, Do-Kyun; Kim, Soo-Ji; Kang, Dong-Hyun

2015-07-01

This study was undertaken to compare the effect of the spindle and stomacher for detaching microorganisms from fresh vegetables. The spindle is an apparatus for detaching microorganisms from food surfaces, which was developed in our laboratory. When processed with the spindle, food samples were barely disrupted, the original shape was maintained, and the diluent was clear, facilitating further detection analysis more easily than with stomacher treatment. The four-section spindle consists of four sample bag containers (A, B, C, and D) to economize time and effort by simultaneously processing four samples. The aerobic plate counts (APC) of 50 fresh vegetable samples were measured following spindle and stomacher treatment. Correlations between the two methods for each section of the spindle and stomacher were very high (R(2) = 0.9828 [spindle compartment A; Sp A], 0.9855 [Sp B], 0.9848 [Sp C], and 0.9851 [Sp D]). One-tenth milliliter of foodborne pathogens suspensions was inoculated onto surfaces of food samples, and ratios of spindle-to-stomacher enumerations were close to 1.00 log CFU/g between every section of the spindle and stomacher. One of the greatest features of the spindle is that it can treat large-sized samples that exceed 200 g. Uncut whole apples, green peppers, potatoes, and tomatoes were processed by the spindle and by hand massaging by 2 min. Large-sized samples were also assayed for aerobic plate count and recovery of the three foodborne pathogens, and the difference between each section of the spindle and hand massaging was not significant (P > 0.05). This study demonstrated that the spindle apparatus can be an alternative device for detaching microorganisms from all fresh vegetable samples for microbiological analysis by the food processing industry.

The structure of the mitotic spindle and nucleolus during mitosis in the amebo-flagellate Naegleria.

PubMed

Walsh, Charles J

2012-01-01

Mitosis in the amebo-flagellate Naegleria pringsheimi is acentrosomal and closed (the nuclear membrane does not break down). The large central nucleolus, which occupies about 20% of the nuclear volume, persists throughout the cell cycle. At mitosis, the nucleolus divides and moves to the poles in association with the chromosomes. The structure of the mitotic spindle and its relationship to the nucleolus are unknown. To identify the origin and structure of the mitotic spindle, its relationship to the nucleolus and to further understand the influence of persistent nucleoli on cellular division in acentriolar organisms like Naegleria, three-dimensional reconstructions of the mitotic spindle and nucleolus were carried out using confocal microscopy. Monoclonal antibodies against three different nucleolar regions and α-tubulin were used to image the nucleolus and mitotic spindle. Microtubules were restricted to the nucleolus beginning with the earliest prophase spindle microtubules. Early spindle microtubules were seen as short rods on the surface of the nucleolus. Elongation of the spindle microtubules resulted in a rough cage of microtubules surrounding the nucleolus. At metaphase, the mitotic spindle formed a broad band completely embedded within the nucleolus. The nucleolus separated into two discreet masses connected by a dense band of microtubules as the spindle elongated. At telophase, the distal ends of the mitotic spindle were still completely embedded within the daughter nucleoli. Pixel by pixel comparison of tubulin and nucleolar protein fluorescence showed 70% or more of tubulin co-localized with nucleolar proteins by early prophase. These observations suggest a model in which specific nucleolar binding sites for microtubules allow mitotic spindle formation and attachment. The fact that a significant mass of nucleolar material precedes the chromosomes as the mitotic spindle elongates suggests that spindle elongation drives nucleolar division.

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

PubMed Central

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

2017-01-01

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. PMID:28513584

A microtubule polymerase cooperates with the kinesin-6 motor and a microtubule cross-linker to promote bipolar spindle assembly in the absence of kinesin-5 and kinesin-14 in fission yeast.

PubMed

Yukawa, Masashi; Kawakami, Tomoki; Okazaki, Masaki; Kume, Kazunori; Tang, Ngang Heok; Toda, Takashi

2017-12-01

Accurate chromosome segregation relies on the bipolar mitotic spindle. In many eukaryotes, spindle formation is driven by the plus-end-directed motor kinesin-5 that generates outward force to establish spindle bipolarity. Its inhibition leads to the emergence of monopolar spindles with mitotic arrest. Intriguingly, simultaneous inactivation of the minus-end-directed motor kinesin-14 restores spindle bipolarity in many systems. Here we show that in fission yeast, three independent pathways contribute to spindle bipolarity in the absence of kinesin-5/Cut7 and kinesin-14/Pkl1. One is kinesin-6/Klp9 that engages with spindle elongation once short bipolar spindles assemble. Klp9 also ensures the medial positioning of anaphase spindles to prevent unequal chromosome segregation. Another is the Alp7/TACC-Alp14/TOG microtubule polymerase complex. Temperature-sensitive alp7cut7pkl1 mutants are arrested with either monopolar or very short spindles. Forced targeting of Alp14 to the spindle pole body is sufficient to render alp7cut7pkl1 triply deleted cells viable and promote spindle assembly, indicating that Alp14-mediated microtubule polymerization from the nuclear face of the spindle pole body could generate outward force in place of Cut7 during early mitosis. The third pathway involves the Ase1/PRC1 microtubule cross-linker that stabilizes antiparallel microtubules. Our study, therefore, unveils multifaceted interplay among kinesin-dependent and -independent pathways leading to mitotic bipolar spindle assembly. © 2017 Yukawa et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

A Functional Relationship between NuMA and Kid Is Involved in Both Spindle Organization and Chromosome Alignment in Vertebrate CellsV⃞

PubMed Central

Levesque, Aime A.; Howard, Louisa; Gordon, Michael B.; Compton, Duane A.

2003-01-01

We examined spindle morphology and chromosome alignment in vertebrate cells after simultaneous perturbation of the chromokinesin Kid and either NuMA, CENP-E, or HSET. Spindle morphology and chromosome alignment after simultaneous perturbation of Kid and either HSET or CENP-E were no different from when either HSET or CENP-E was perturbed alone. However, short bipolar spindles with organized poles formed after perturbation of both Kid and NuMA in stark contrast to splayed spindle poles observed after perturbation of NuMA alone. Spindles were disorganized if Kid, NuMA, and HSET were perturbed, indicating that HSET is sufficient for spindle organization in the absence of Kid and NuMA function. In addition, chromosomes failed to align efficiently at the spindle equator after simultaneous perturbation of Kid and NuMA despite appropriate kinetochore-microtubule interactions that generated chromosome movement at normal velocities. These data indicate that a functional relationship between the chromokinesin Kid and the spindle pole organizing protein NuMA influences spindle morphology, and we propose that this occurs because NuMA forms functional linkages between kinetochore and nonkinetochore microtubules at spindle poles. In addition, these data show that both Kid and NuMA contribute to chromosome alignment in mammalian cells. PMID:12972545

ATRX, a member of the SNF2 family of helicase/ATPases, is required for chromosome alignment and meiotic spindle organization in metaphase II stage mouse oocytes.

PubMed

De La Fuente, Rabindranath; Viveiros, Maria M; Wigglesworth, Karen; Eppig, John J

2004-08-01

ATRX is a centromeric heterochromatin binding protein belonging to the SNF2 family of helicase/ATPases with chromatin remodeling activity. Mutations in the human ATRX gene result in X-linked alpha-thalassaemia with mental retardation (ATRX) syndrome and correlate with changes in methylation of repetitive DNA sequences. We show here that ATRX also functions to regulate key stages of meiosis in mouse oocytes. At the germinal vesicle (GV) stage, ATRX was found associated with the perinucleolar heterochromatin rim in transcriptionally quiescent oocytes. Phosphorylation of ATRX during meiotic maturation is dependent upon calcium calmodulin kinase (CamKII) activity. Meiotic resumption also coincides with deacetylation of histone H4 at lysine 5 (H4K5 Ac) while ATRX and histone H3 methylated on lysine 9 (H3K9) remained bound to the centromeres and interstitial regions of condensing chromosomes, respectively. Inhibition of histone deacetylases (HDACs) with trichostatin A (TSA) disrupted ATRX binding to the centromeres of hyperacetylated chromosomes resulting in abnormal chromosome alignments at metaphase II (MII). Similarly, while selective ablation of ATRX by antibody microinjection and RNA interference (RNAi) had no effect on the progression of meiosis, it had severe consequences for the alignment of chromosomes on the metaphase II spindle. These results suggest that genome-wide epigenetic modifications such as global histone deacetylation are essential for the binding of ATRX to centromeric heterochromatin. Moreover, centromeric ATRX is required for correct chromosome alignment and organization of a bipolar meiotic metaphase II spindle.

Microtubule Dynamics Scale with Cell Size to Set Spindle Length and Assembly Timing.

PubMed

Lacroix, Benjamin; Letort, Gaëlle; Pitayu, Laras; Sallé, Jérémy; Stefanutti, Marine; Maton, Gilliane; Ladouceur, Anne-Marie; Canman, Julie C; Maddox, Paul S; Maddox, Amy S; Minc, Nicolas; Nédélec, François; Dumont, Julien

2018-05-21

Successive cell divisions during embryonic cleavage create increasingly smaller cells, so intracellular structures must adapt accordingly. Mitotic spindle size correlates with cell size, but the mechanisms for this scaling remain unclear. Using live cell imaging, we analyzed spindle scaling during embryo cleavage in the nematode Caenorhabditis elegans and sea urchin Paracentrotus lividus. We reveal a common scaling mechanism, where the growth rate of spindle microtubules scales with cell volume, which explains spindle shortening. Spindle assembly timing is, however, constant throughout successive divisions. Analyses in silico suggest that controlling the microtubule growth rate is sufficient to scale spindle length and maintain a constant assembly timing. We tested our in silico predictions to demonstrate that modulating cell volume or microtubule growth rate in vivo induces a proportional spindle size change. Our results suggest that scalability of the microtubule growth rate when cell size varies adapts spindle length to cell volume. Copyright © 2018 Elsevier Inc. All rights reserved.

Aeronautic Instruments. Section IV : Direction Instruments

NASA Technical Reports Server (NTRS)

Franklin, W S; Stillman, M H; Sanford, R L; Warner, John A C; Sylvander, R C; Rounds, E W

1923-01-01

Part one points out the adequacy of a consideration of the steady state gyroscopic motion as a basis for the discussion of displacements of the gyroscope mounted on an airplane, and develops a simple theory on this basis. Principal types of gyroscopic inclinometers are described and requirements stated. Part two describes a new type of stabilizing gyro mounted on top of a spindle by means of a universal joint, the spindle being kept in a vertical position by supporting it as a pendulum of which the bob is the driving motor. Methods of tests and the difficulties in designing a satisfactory and reliable compass for aircraft use in considered in part three. Part four contains a brief general treatment of the important features of construction of aircraft compasses and description of the principal types used.

Regulation of spindle integrity and mitotic fidelity by BCCIP

PubMed Central

Huhn, S C; Liu, J; Ye, C; Lu, H; Jiang, X; Feng, X; Ganesan, S; White, E; Shen, Z

2017-01-01

Centrosomes together with the mitotic spindle ensure the faithful distribution of chromosomes between daughter cells, and spindle orientation is a major determinant of cell fate during tissue regeneration. Spindle defects are not only an impetus of chromosome instability but are also a cause of developmental disorders involving defective asymmetric cell division. In this work, we demonstrate BCCIP, especially BCCIPα, as a previously unidentified component of the mitotic spindle pole and the centrosome. We demonstrate that BCCIP localizes proximal to the mother centriole and participates in microtubule organization and then redistributes to the spindle pole to ensure faithful spindle architecture. We find that BCCIP depletion leads to morphological defects, disoriented mitotic spindles, chromosome congression defects and delayed mitotic progression. Our study identifies BCCIP as a novel factor critical for microtubule regulation and explicates a mechanism utilized by BCCIP in tumor suppression. PMID:28394342

Time-frequency dynamics during sleep spindles on the EEG in rodents with a genetic predisposition to absence epilepsy (WAG/Rij rats)

NASA Astrophysics Data System (ADS)

Hramov, Alexander E.; Sitnikova, Evgenija Y.; Pavlov, Alexey N.; Grubov, Vadim V.; Koronovskii, Alexey A.; Khramova, Marina V.

2015-03-01

Sleep spindles are known to appear spontaneously in the thalamocortical neuronal network of the brain during slow-wave sleep; pathological processes in the thalamocortical network may be the reason of the absence epilepsy. The aim of the present work is to study developed changes in the time-frequency structure of sleep spindles during the progressive development of the absence epilepsy in WAG/Rij rats. EEG recordings were made at age 7 and 9 months. Automatic recognition and subsequent analysis of sleep spindles on the EEG were performed using the continuous wavelet transform. The duration of epileptic discharges and the total duration of epileptic activity were found to increase with age, while the duration of sleep spindles, conversely, decreased. In terms of the mean frequency, sleep spindles could be divided into three classes: `slow' (mean frequency 9.3Hz), `medium' (11.4Hz), and `fast' (13.5Hz). Slow and medium (transitional) spindles in five-month-old animals showed increased frequency from the beginning to the end of the spindle. The more intense the epilepsy is, the shorter are the durations of spindles of all types. The mean frequencies of `medium' and `fast' spindles were higher in rats with more intense signs of epilepsy. Overall, high epileptic activity in WAG/Rij rats was linked with significant changes in spindles of the transitional type, with less marked changes in the two traditionally identified types of spindle, slow and fast.

Fabrication of a grazing incidence telescope by grinding and polishing techniques on aluminum

NASA Technical Reports Server (NTRS)

Gallagher, Dennis; Cash, Webster; Green, James

1991-01-01

The paper describes the fabrication processes, by grinding and polishing, used in making the mirrors for a f/2.8 Wolter type-I grazing incidence telescope at Boulder (Colorado), together with testing procedure used to determine the quality of the images. All grinding and polishing is done on specially designed machine that consists of a horizontal spindle to hold and rotate the mirror and a stroke arm machine to push the various tools back and forth along the mirrors length. The progress is checked by means of the ronchi test during all grinding and polishing stages. Current measurements of the telescope's image quality give a FWHM measurement of 44 arcsec, with the goal set at 5-10 arcsec quality.

Linear and quadratic models of point process systems: contributions of patterned input to output.

PubMed

Lindsay, K A; Rosenberg, J R

2012-08-01

In the 1880's Volterra characterised a nonlinear system using a functional series connecting continuous input and continuous output. Norbert Wiener, in the 1940's, circumvented problems associated with the application of Volterra series to physical problems by deriving from it a new series of terms that are mutually uncorrelated with respect to Gaussian processes. Subsequently, Brillinger, in the 1970's, introduced a point-process analogue of Volterra's series connecting point-process inputs to the instantaneous rate of point-process output. We derive here a new series from this analogue in which its terms are mutually uncorrelated with respect to Poisson processes. This new series expresses how patterned input in a spike train, represented by third-order cross-cumulants, is converted into the instantaneous rate of an output point-process. Given experimental records of suitable duration, the contribution of arbitrary patterned input to an output process can, in principle, be determined. Solutions for linear and quadratic point-process models with one and two inputs and a single output are investigated. Our theoretical results are applied to isolated muscle spindle data in which the spike trains from the primary and secondary endings from the same muscle spindle are recorded in response to stimulation of one and then two static fusimotor axons in the absence and presence of a random length change imposed on the parent muscle. For a fixed mean rate of input spikes, the analysis of the experimental data makes explicit which patterns of two input spikes contribute to an output spike. Copyright © 2012 Elsevier Ltd. All rights reserved.

Dynactin Function in Mitotic Spindle Positioning

PubMed Central

Moore, Jeffrey K.; Li, Jun; Cooper, John A.

2008-01-01

Dynactin is a multisubunit protein complex necessary for dynein function. Here, we investigated the function of dynactin in budding yeast. Loss of dynactin impaired movement and positioning of the mitotic spindle, similar to loss of dynein. Dynactin subunits required for function included p150Glued, dynamitin, actin-related protein (Arp) 1 and p24. Arp10 and capping protein were dispensable, even in combination. All dynactin subunits tested localized to dynamic plus ends of cytoplasmic microtubules, to stationary foci on the cell cortex and to spindle pole bodies. The number of molecules of dynactin in those locations was small, less than five. In the absence of dynactin, dynein accumulated at plus ends and did not appear at the cell cortex, consistent with a role for dynactin in offloading dynein from the plus end to the cortex. Dynein at the plus end was necessary for dynactin plus-end targeting. p150Glued was the only dynactin subunit sufficient for plus-end targeting. Interactions among the subunits support a molecular model that resembles the current model for brain dynactin in many respects; however, three subunits at the pointed end of brain dynactin appear to be absent from yeast. PMID:18221362

Mechanical design principles of a mitotic spindle.

PubMed

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.

Optimal design of high-speed loading spindle based on ABAQUS

NASA Astrophysics Data System (ADS)

Yang, Xudong; Dong, Yu; Ge, Qingkuan; Yang, Hai

2017-12-01

The three-dimensional model of high-speed loading spindle is established by using ABAQUS’s modeling module. A finite element analysis model of high-speed loading spindle was established by using spring element to simulate bearing boundary condition. The static and dynamic performance of the spindle structure with different specifications of the rectangular spline and the different diameter neck of axle are studied in depth, and the influence of different spindle span on the static and dynamic performance of the high-speed loading spindle is studied. Finally, the optimal structure of the high-speed loading spindle is obtained. The results provide a theoretical basis for improving the overall performance of the test-bed

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

NASA Astrophysics Data System (ADS)

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

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 crosslinkers are important for bipolarity, but the mechanisms necessary and sufficient for spindle assembly remain unknown. Here we describe a physical model that exhibits de novo bipolar spindle formation. We began with previously published data on fission-yeast spindle-pole-body size and microtubule number, kinesin-5 motors, kinesin-14 motors, and passive crosslinkers. 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 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 crosslinkers alone. We also identify characteristic failed states of spindle assembly, which are avoided by creation and maintenance of antiparallel microtubule overlaps. DMR-0847685, DMR-1551095, DMR-1420736, K25GM110486, R01GM104976, R01GM033787.

Relationship between focal penicillin spikes and cortical spindles in the cerveau isolé cat.

PubMed

McLachlan, R S; Kaibara, M; Girvin, J P

1983-01-01

Using the unanesthetized, cerveau isolé preparation in the cat, the association between artificially induced penicillin (PCN) spikes and spontaneously occurring electrocorticographic (ECoG) spindles was investigated. Spikes were elicited by surface application of small pledgets of PCN. After the application of PCN, there was a decrease in spindle amplitude but no change in frequency, duration, or spindle wave frequency in the area of the focus. Examination of the times of occurrence of the spikes and spindles disclosed that in the majority of cases, within a few minutes of the initiation of the foci, there was very high simultaneity, usually 100% between the occurrences of these two events. Examination of the times of occurrence of the spikes within the ECoG spindles failed to disclose any compelling evidence which would favor either the hypothesis that spikes "trigger" spindles or the hypothesis that spindles predispose to focal spikes. Thus, whether spikes trigger spindles, or spikes simply occur in a nonspecific manner during the occurrence of the spindle, or whether it is a combination of both these explanations, must remain an open question on the basis of the data available.

Topographical distribution of fast and slow sleep spindles in medicated depressive patients.

PubMed

Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

2014-10-01

To compare the properties of sleep spindles between healthy subjects and medicated patients with major depressive episode, including frequency range, spectra power, and spatial distribution of spindle power. Continuous 16-channel EEG was used to record nocturnal sleep in healthy control subjects and medicated depressive patients. Recordings were analyzed for changes in EEG power spectra and power topography. Additionally, we graphically demonstrated the pattern of spatial distribution of each type of sleep spindle, divided into fast (12.5-14 Hz) and slow spindles (11-12.5 Hz). Sleep EEG records of depressive subjects exhibited a significantly higher amplitude of slow spindles in the prefrontal region, compared with the healthy controls (P < 0.01). Fast spindles were dominant in the centroparietal region in both depressive patients and the control group. Enhanced slow spindles in the prefrontal region were observed in the medicated depressive patients and not in the healthy controls. The frequency of fast spindles in depressive patients was globally higher than that in healthy participants. The alteration in sleep spindles seen in medicated depressive subjects may reflect a pharmacological modulation of synaptic function involving the thalamic-reticular and thalamocortical mechanisms.

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

NASA Astrophysics Data System (ADS)

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.

CENP-W Plays a Role in Maintaining Bipolar Spindle Structure

PubMed Central

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 motor proteins during chromosome congression. Taken together, our findings are consistent with a model in which centrosome integrity is controlled by the pathways regulating kinetochore-microtubule attachment stability. PMID:25329824

Sleep spindles and intelligence: evidence for a sexual dimorphism.

PubMed

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. Copyright © 2014 the authors 0270-6474/14/3416358-11$15.00/0.

Budding yeast chromatin is dispersed in a crowded nucleoplasm in vivo

PubMed Central

Chen, Chen; Lim, Hong Hwa; Shi, Jian; Tamura, Sachiko; Maeshima, Kazuhiro; Surana, Uttam; Gan, Lu

2016-01-01

Chromatin organization has an important role in the regulation of eukaryotic systems. Although recent studies have refined the three-dimensional models of chromatin organization with high resolution at the genome sequence level, little is known about how the most fundamental units of chromatin—nucleosomes—are positioned in three dimensions in vivo. Here we use electron cryotomography to study chromatin organization in the budding yeast Saccharomyces cerevisiae. Direct visualization of yeast nuclear densities shows no evidence of 30-nm fibers. Aside from preribosomes and spindle microtubules, few nuclear structures are larger than a tetranucleosome. Yeast chromatin does not form compact structures in interphase or mitosis and is consistent with being in an “open” configuration that is conducive to high levels of transcription. From our study and those of others, we propose that yeast can regulate its transcription using local nucleosome–nucleosome associations. PMID:27605704

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

NASA Astrophysics Data System (ADS)

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.

MULTIPOLAR SPINDLE 1 (MPS1), a novel coiled-coil protein of Arabidopsis thaliana, is required for meiotic spindle organization.

PubMed

Jiang, Hua; Wang, Fen-Fei; Wu, Yu-Ting; Zhou, Xi; Huang, Xue-Yong; Zhu, Jun; Gao, Ju-Fang; Dong, Rui-Bin; Cao, Kai-Ming; Yang, Zhong-Nan

2009-09-01

The spindle is essential for chromosome segregation during meiosis, but the molecular mechanism of meiotic spindle organization in higher plants is still not well understood. Here, we report on the identification and characterization of a plant-specific protein, MULTIPOLAR SPINDLE 1 (MPS1), which is involved in spindle organization in meiocytes of Arabidopsis thaliana. The homozygous mps1 mutant exhibits male and female sterility. Light microscopy showed that mps1 mutants produced multiple uneven spores during anther development, most of which aborted in later stages. Cytological analysis showed that chromosome segregation was abnormal in mps1 meiocytes. Immunolocalization showed unequal bipolar or multipolar spindles in mps1 meiocytes, which indicated that aberrant spindles resulted in disordered chromosome segregation. MPS1 encodes a 377-amino-acid protein with putative coiled-coil motifs. In situ hybridization analysis showed that MPS1 is strongly expressed in meiocytes.

Mitotic Spindle Positioning in the EMS Cell of Caenorhabditis elegans Requires LET-99 and LIN-5/NuMA.

PubMed

Liro, Małgorzata J; Rose, Lesilee S

2016-11-01

Asymmetric divisions produce daughter cells with different fates, and thus are critical for animal development. During asymmetric divisions, the mitotic spindle must be positioned on a polarized axis to ensure the differential segregation of cell fate determinants into the daughter cells. In many cell types, a cortically localized complex consisting of Gα, GPR-1/2, and LIN-5 (Gαi/Pins/Mud, Gαi/LGN/NuMA) mediates the recruitment of dynactin/dynein, which exerts pulling forces on astral microtubules to physically position the spindle. The conserved PAR polarity proteins are known to regulate both cytoplasmic asymmetry and spindle positioning in many cases. However, spindle positioning also occurs in response to cell signaling cues that appear to be PAR-independent. In the four-cell Caenorhabditis elegans embryo, Wnt and Mes-1/Src-1 signaling pathways act partially redundantly to align the spindle on the anterior/posterior axis of the endomesodermal (EMS) precursor cell. It is unclear how those extrinsic signals individually contribute to spindle positioning and whether either pathway acts via conserved spindle positioning regulators. Here, we genetically test the involvement of Gα, LIN-5, and their negative regulator LET-99, in transducing EMS spindle positioning polarity cues. We also examined whether the C. elegans ortholog of another spindle positioning regulator, DLG-1, is required. We show that LET-99 acts in the Mes-1/Src-1 pathway for spindle positioning. LIN-5 is also required for EMS spindle positioning, possibly through a Gα- and DLG-1-independent mechanism. Copyright © 2016 by the Genetics Society of America.

Mitotic Spindle Positioning in the EMS Cell of Caenorhabditis elegans Requires LET-99 and LIN-5/NuMA

PubMed Central

Liro, Małgorzata J.; Rose, Lesilee S.

2016-01-01

Asymmetric divisions produce daughter cells with different fates, and thus are critical for animal development. During asymmetric divisions, the mitotic spindle must be positioned on a polarized axis to ensure the differential segregation of cell fate determinants into the daughter cells. In many cell types, a cortically localized complex consisting of Gα, GPR-1/2, and LIN-5 (Gαi/Pins/Mud, Gαi/LGN/NuMA) mediates the recruitment of dynactin/dynein, which exerts pulling forces on astral microtubules to physically position the spindle. The conserved PAR polarity proteins are known to regulate both cytoplasmic asymmetry and spindle positioning in many cases. However, spindle positioning also occurs in response to cell signaling cues that appear to be PAR-independent. In the four-cell Caenorhabditis elegans embryo, Wnt and Mes-1/Src-1 signaling pathways act partially redundantly to align the spindle on the anterior/posterior axis of the endomesodermal (EMS) precursor cell. It is unclear how those extrinsic signals individually contribute to spindle positioning and whether either pathway acts via conserved spindle positioning regulators. Here, we genetically test the involvement of Gα, LIN-5, and their negative regulator LET-99, in transducing EMS spindle positioning polarity cues. We also examined whether the C. elegans ortholog of another spindle positioning regulator, DLG-1, is required. We show that LET-99 acts in the Mes-1/Src-1 pathway for spindle positioning. LIN-5 is also required for EMS spindle positioning, possibly through a Gα- and DLG-1-independent mechanism. PMID:27672093

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

PubMed

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

2008-05-20

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 originally identified in a proteomic survey of the human spindle apparatus [1]. We show that CHICA localizes to the mitotic spindle and is both upregulated and phosphorylated during mitosis. CHICA-depleted cells form shorter spindles and fail to organize a proper metaphase plate, highly reminiscent of the phenotype observed upon depletion of the chromokinesin Kid, a key mediator of polar ejection forces [2-6]. We further show that CHICA coimmunoprecipitates with Kid and is required for the spindle localization of Kid without affecting its chromosome association. Moreover, upon depletion of either CHICA or Kid (or both proteins simultaneously), chromosomes collapse onto the poles of monastrol-induced monopolar spindles. We conclude that CHICA represents a novel interaction partner of the chromokinesin Kid that is required for the generation of polar ejection forces and chromosome congression.

Meiosis-Specific Stable Binding of Augmin to Acentrosomal Spindle Poles Promotes Biased Microtubule Assembly in Oocytes

PubMed Central

Colombié, Nathalie; Głuszek, A. Agata; Meireles, Ana M.; Ohkura, Hiroyuki

2013-01-01

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. PMID:23785300

Monitoring Method of Cutting Force by Using Additional Spindle Sensors

NASA Astrophysics Data System (ADS)

Sarhan, Ahmed Aly Diaa; Matsubara, Atsushi; Sugihara, Motoyuki; Saraie, Hidenori; Ibaraki, Soichi; Kakino, Yoshiaki

This paper describes a monitoring method of cutting forces for end milling process by using displacement sensors. Four eddy-current displacement sensors are installed on the spindle housing of a machining center so that they can detect the radial motion of the rotating spindle. Thermocouples are also attached to the spindle structure in order to examine the thermal effect in the displacement sensing. The change in the spindle stiffness due to the spindle temperature and the speed is investigated as well. Finally, the estimation performance of cutting forces using the spindle displacement sensors is experimentally investigated by machining tests on carbon steel in end milling operations under different cutting conditions. It is found that the monitoring errors are attributable to the thermal displacement of the spindle, the time lag of the sensing system, and the modeling error of the spindle stiffness. It is also shown that the root mean square errors between estimated and measured amplitudes of cutting forces are reduced to be less than 20N with proper selection of the linear stiffness.

Remote drill bit loader

DOEpatents

Dokos, J.A.

1997-12-30

A drill bit loader is described for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pins prevent rotation of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned. 5 figs.

Rat isolated phrenic nerve-diaphragm preparation for pharmacological study of muscle spindle afferent activity: effect of oxotremorine.

PubMed Central

Ganguly, D K; Nath, D N; Ross, H G; Vedasiromoni, J R

1978-01-01

1. Muscle spindle afferent discharges exhibiting an approximately linear length-frequency relation could be recorded from the phrenic nerve in the isolated phrenic nerve-diaphragm preparation of the rat. 2. Muscle spindle afferent discharges could be identified by their characteristic "spindle pause" during muscle contraction and by their response to succinylcholine. 3. Cholinergic influence on spontaneous and stretch-induced afferent discharges was indicated by the augmentation produced by physostigmine and acetylcholine. (+)-Tubocurarine, but not atropine, prevented this augmentation indicating the presence of curariform cholinoceptors in muscle spindles. 4. Acetylcholine did not appear to be involved in the genesis of spindle afferent discharges as incubation with hemicholinium-3 and (+)-tubocurarine failed to affect the rate of spontaneous and stretch-induced spindle discharges. 5. Oxotremorine markedly increased the rate of spontaneous and stretch-induced spindle afferent discharges and this effect was prevented in the presence of hemicholinium-3 and (+)-tubocurarine. 6. These results with oxotremorine are of interest in connection with the observation that muscle spindle afferents and hyperactive in Parkinsonian patients. PMID:151569

Remote drill bit loader

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dokos, James A.

A drill bit loader for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pins prevent rotationmore » of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned.« less

Remote drill bit loader

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dokos, J.A.

A drill bit loader is described for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pinsmore » prevent rotation of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned. 5 figs.« less

78 FR 2438 - Agency Information Collection Activities; Existing Collection, Comments Requested: The National...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-11

... Collection, Comments Requested: The National Instant Criminal Background Check System (NICS) Point-of-Contact... Background Check System (NICS) Point-of-Contact (POC) State Final Determination Electronic Submission. (3... required to respond, as well as a brief abstract: Primary: Full Point-of-Contact (POC) States; Partial POC...

Ultrasonic drilling apparatus

DOEpatents

Duran, Edward L.; Lundin, Ralph L.

1989-01-01

Apparatus attachable to an ultrasonic drilling machine for drilling deep holes in very hard materials, such as boron carbide, is provided. The apparatus utilizes a hollow spindle attached to the output horn of the ultrasonic drilling machine. The spindle has a hollow drill bit attached at the opposite end. A housing surrounds the spindle, forming a cavity for holding slurry. In operation, slurry is provided into the housing, and into the spindle through inlets while the spindle is rotating and ultrasonically reciprocating. Slurry flows through the spindle and through the hollow drill bit to cleanse the cutting edge of the bit during a drilling operation.

Ultrasonic drilling apparatus

DOEpatents

Duran, E.L.; Lundin, R.L.

1988-06-20

Apparatus attachable to an ultrasonic drilling machine for drilling deep holes in very hard materials, such as boron carbide, is provided. The apparatus utilizes a hollow spindle attached to the output horn of the ultrasonic drilling machine. The spindle has a hollow drill bit attached at the opposite end. A housing surrounds the spindle, forming a cavity for holding slurry. In operation, slurry is provided into the housing, and into the spindle through inlets while the spindle is rotating and ultrasonically reciprocating. Slurry flows through the spindle and through the hollow drill bit to cleanse the cutting edge of the bit during a drilling operation. 3 figs.

NuMA-microtubule interactions are critical for spindle orientation and the morphogenesis of diverse epidermal structures

PubMed Central

Seldin, Lindsey; Muroyama, Andrew; Lechler, Terry

2016-01-01

Mitotic spindle orientation is used to generate cell fate diversity and drive proper tissue morphogenesis. A complex of NuMA and dynein/dynactin is required for robust spindle orientation in a number of cell types. Previous research proposed that cortical dynein/dynactin was sufficient to generate forces on astral microtubules (MTs) to orient the spindle, with NuMA acting as a passive tether. In this study, we demonstrate that dynein/dynactin is insufficient for spindle orientation establishment in keratinocytes and that NuMA’s MT-binding domain, which targets MT tips, is also required. Loss of NuMA-MT interactions in skin caused defects in spindle orientation and epidermal differentiation, leading to neonatal lethality. In addition, we show that NuMA-MT interactions are also required in adult mice for hair follicle morphogenesis and spindle orientation within the transit-amplifying cells of the matrix. Loss of spindle orientation in matrix cells results in defective differentiation of matrix-derived lineages. Our results reveal an additional and direct function of NuMA during mitotic spindle positioning, as well as a reiterative use of spindle orientation in the skin to build diverse structures. DOI: http://dx.doi.org/10.7554/eLife.12504.001 PMID:26765568

Automated Stitching of Microtubule Centerlines across Serial Electron Tomograms

PubMed Central

Weber, Britta; Tranfield, Erin M.; Höög, Johanna L.; Baum, Daniel; Antony, Claude; Hyman, Tony; Verbavatz, Jean-Marc; Prohaska, Steffen

2014-01-01

Tracing microtubule centerlines in serial section electron tomography requires microtubules to be stitched across sections, that is lines from different sections need to be aligned, endpoints need to be matched at section boundaries to establish a correspondence between neighboring sections, and corresponding lines need to be connected across multiple sections. We present computational methods for these tasks: 1) An initial alignment is computed using a distance compatibility graph. 2) A fine alignment is then computed with a probabilistic variant of the iterative closest points algorithm, which we extended to handle the orientation of lines by introducing a periodic random variable to the probabilistic formulation. 3) Endpoint correspondence is established by formulating a matching problem in terms of a Markov random field and computing the best matching with belief propagation. Belief propagation is not generally guaranteed to converge to a minimum. We show how convergence can be achieved, nonetheless, with minimal manual input. In addition to stitching microtubule centerlines, the correspondence is also applied to transform and merge the electron tomograms. We applied the proposed methods to samples from the mitotic spindle in C. elegans, the meiotic spindle in X. laevis, and sub-pellicular microtubule arrays in T. brucei. The methods were able to stitch microtubules across section boundaries in good agreement with experts' opinions for the spindle samples. Results, however, were not satisfactory for the microtubule arrays. For certain experiments, such as an analysis of the spindle, the proposed methods can replace manual expert tracing and thus enable the analysis of microtubules over long distances with reasonable manual effort. PMID:25438148

Automated stitching of microtubule centerlines across serial electron tomograms.

PubMed

Weber, Britta; Tranfield, Erin M; Höög, Johanna L; Baum, Daniel; Antony, Claude; Hyman, Tony; Verbavatz, Jean-Marc; Prohaska, Steffen

2014-01-01

Tracing microtubule centerlines in serial section electron tomography requires microtubules to be stitched across sections, that is lines from different sections need to be aligned, endpoints need to be matched at section boundaries to establish a correspondence between neighboring sections, and corresponding lines need to be connected across multiple sections. We present computational methods for these tasks: 1) An initial alignment is computed using a distance compatibility graph. 2) A fine alignment is then computed with a probabilistic variant of the iterative closest points algorithm, which we extended to handle the orientation of lines by introducing a periodic random variable to the probabilistic formulation. 3) Endpoint correspondence is established by formulating a matching problem in terms of a Markov random field and computing the best matching with belief propagation. Belief propagation is not generally guaranteed to converge to a minimum. We show how convergence can be achieved, nonetheless, with minimal manual input. In addition to stitching microtubule centerlines, the correspondence is also applied to transform and merge the electron tomograms. We applied the proposed methods to samples from the mitotic spindle in C. elegans, the meiotic spindle in X. laevis, and sub-pellicular microtubule arrays in T. brucei. The methods were able to stitch microtubules across section boundaries in good agreement with experts' opinions for the spindle samples. Results, however, were not satisfactory for the microtubule arrays. For certain experiments, such as an analysis of the spindle, the proposed methods can replace manual expert tracing and thus enable the analysis of microtubules over long distances with reasonable manual effort.

Assessing EEG sleep spindle propagation. Part 1: theory and proposed methodology.

PubMed

O'Reilly, Christian; Nielsen, Tore

2014-01-15

A convergence of studies has revealed sleep spindles to be associated with sleep-related cognitive processing and even with fundamental waking state capacities such as intelligence. However, some spindle characteristics, such as propagation direction and delay, may play a decisive role but are only infrequently investigated because of technical complexities. A new methodology for assessing sleep spindle propagation over the human scalp using noninvasive electroencephalography (EEG) is described. This approach is based on the alignment of time-frequency representations of spindle activity across recording channels. This first of a two-part series concentrates on framing theoretical considerations related to EEG spindle propagation and on detailing the methodology. A short example application is provided that illustrates the repeatability of results obtained with the new propagation measure in a sample of 32 night recordings. A more comprehensive experimental investigation is presented in part two of the series. Compared to existing methods, this approach is particularly well adapted for studying the propagation of sleep spindles because it estimates time delays rather than phase synchrony and it computes propagation properties for every individual spindle with windows adjusted to the specific spindle duration. The proposed methodology is effective in tracking the propagation of spindles across the scalp and may thus help in elucidating the temporal aspects of sleep spindle dynamics, as well as other transient EEG and MEG events. A software implementation (the Spyndle Python package) is provided as open source software. Copyright © 2013 Elsevier B.V. All rights reserved.

Mechanical design principles of a mitotic spindle

PubMed Central

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

2014-01-01

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. DOI: http://dx.doi.org/10.7554/eLife.03398.001 PMID:25521247

Brownian dynamics simulation of fission yeast mitotic spindle formation

NASA Astrophysics Data System (ADS)

Edelmaier, Christopher

2014-03-01

The mitotic spindle segregates chromosomes during mitosis. The dynamics that establish bipolar spindle formation are not well understood. We have developed a computational model of fission-yeast mitotic spindle formation using Brownian dynamics and kinetic Monte Carlo methods. Our model includes rigid, dynamic microtubules, a spherical nuclear envelope, spindle pole bodies anchored in the nuclear envelope, and crosslinkers and crosslinking motor proteins. Crosslinkers and crosslinking motor proteins attach and detach in a grand canonical ensemble, and exert forces and torques on the attached microtubules. We have modeled increased affinity for crosslinking motor attachment to antiparallel microtubule pairs, and stabilization of microtubules in the interpolar bundle. We study parameters controlling the stability of the interpolar bundle and assembly of a bipolar spindle from initially adjacent spindle-pole bodies.

Dual mechanism controls asymmetric spindle position in ascidian germ cell precursors.

PubMed

Prodon, François; Chenevert, Janet; Hébras, Céline; Dumollard, Rémi; Faure, Emmanuel; Gonzalez-Garcia, Jose; Nishida, Hiroki; Sardet, Christian; McDougall, Alex

2010-06-01

Mitotic spindle orientation with respect to cortical polarity cues generates molecularly distinct daughter cells during asymmetric cell division (ACD). However, during ACD it remains unknown how the orientation of the mitotic spindle is regulated by cortical polarity cues until furrowing begins. In ascidians, the cortical centrosome-attracting body (CAB) generates three successive unequal cleavages and the asymmetric segregation of 40 localized postplasmic/PEM RNAs in germ cell precursors from the 8-64 cell stage. By combining fast 4D confocal fluorescence imaging with gene-silencing and classical blastomere isolation experiments, we show that spindle repositioning mechanisms are active from prometaphase until anaphase, when furrowing is initiated in B5.2 cells. We show that the vegetal-most spindle pole/centrosome is attracted towards the CAB during prometaphase, causing the spindle to position asymmetrically near the cortex. Next, during anaphase, the opposite spindle pole/centrosome is attracted towards the border with neighbouring B5.1 blastomeres, causing the spindle to rotate (10 degrees /minute) and migrate (3 microm/minute). Dynamic 4D fluorescence imaging of filamentous actin and plasma membrane shows that precise orientation of the cleavage furrow is determined by this second phase of rotational spindle displacement. Furthermore, in pairs of isolated B5.2 blastomeres, the second phase of rotational spindle displacement was lost. Finally, knockdown of PEM1, a protein localized in the CAB and required for unequal cleavage in B5.2 cells, completely randomizes spindle orientation. Together these data show that two separate mechanisms active during mitosis are responsible for spindle positioning, leading to precise orientation of the cleavage furrow during ACD in the cells that give rise to the germ lineage in ascidians.

[Soft tissue sarcomas: the role of histology and molecular pathology for differential diagnosis].

PubMed

Poremba, C

2006-01-01

Soft tissue sarcomas include a wide spectrum of different entities. The so-called small round blue cell tumors and spindle cell tumors are difficult to classify based solely on conventional histology. To identify different subtypes of tumors special histochemical and immunohistochemical techniques are necessary. Analysis of protein expression by immunohistochemistry provides a helpful tool to investigate the histogenesis of tumors. A basic spectrum of antibodies should be included to study these tumors: Desmin and myogenin (or MyoD1) for skeletal differentiation; S-100, NSE, CD56, and synaptophysin for neural/neuroendocrine differentiation; CD3, CD20, and CD79 alpha for malignant lymphomas; CD34, sm-actin, and beta-catenin for spindle cell tumors; additional antigens, e. g. Ki-67 and p 53, for estimation of proliferation and tumor suppressor gene malfunctions. Nevertheless, the molecular analysis of soft tissue sarcomas is necessary for demonstration of specific translocations or gene defects to specify and proof a diagnosis. For this purpose, RT-PCR for RNA expression analysis of gene fusion transcripts and multi-color FISH for analysis of chromosomal rearrangements are used. Further investigations, using DNA microrrays may help to subclassify such tumors, with respect to prognosis or prediction of therapeutic response.

Gene knockout of Zmym3 in mice arrests spermatogenesis at meiotic metaphase with defects in spindle assembly checkpoint.

PubMed

Hu, Xiangjing; Shen, Bin; Liao, Shangying; Ning, Yan; Ma, Longfei; Chen, Jian; Lin, Xiwen; Zhang, Daoqin; Li, Zhen; Zheng, Chunwei; Feng, Yanmin; Huang, Xingxu; Han, Chunsheng

2017-06-29

ZMYM3, a member of the MYM-type zinc finger protein family and a component of a LSD1-containing transcription repressor complex, is predominantly expressed in the mouse brain and testis. Here, we show that ZMYM3 in the mouse testis is expressed in somatic cells and germ cells until pachytene spermatocytes. Knockout (KO) of Zmym3 in mice using the CRISPR-Cas9 system resulted in adult male infertility. Spermatogenesis of the KO mice was arrested at the metaphase of the first meiotic division (MI). ZMYM3 co-immunoprecipitated with LSD1 in spermatogonial stem cells, but its KO did not change the levels of LSD1 or H3K4me1/2 or H3K9me2. However, Zmym3 KO resulted in elevated numbers of apoptotic germ cells and of MI spermatocytes that are positive for BUB3, which is a key player in spindle assembly checkpoint. Zmym3 KO also resulted in up-regulated expression of meiotic genes in spermatogonia. These results show that ZMYM3 has an essential role in metaphase to anaphase transition during mouse spermatogenesis by regulating the expression of diverse families of genes.

Syndecan defines precise spindle orientation by modulating Wnt signaling in C. elegans.

PubMed

Dejima, Katsufumi; Kang, Sukryool; Mitani, Shohei; Cosman, Pamela C; Chisholm, Andrew D

2014-11-01

Wnt signals orient mitotic spindles in development, but it remains unclear how Wnt signaling is spatially controlled to achieve precise spindle orientation. Here, we show that C. elegans syndecan (SDN-1) is required for precise orientation of a mitotic spindle in response to a Wnt cue. We find that SDN-1 is the predominant heparan sulfate (HS) proteoglycan in the early C. elegans embryo, and that loss of HS biosynthesis or of the SDN-1 core protein results in misorientation of the spindle of the ABar blastomere. The ABar and EMS spindles both reorient in response to Wnt signals, but only ABar spindle reorientation is dependent on a new cell contact and on HS and SDN-1. SDN-1 transiently accumulates on the ABar surface as it contacts C, and is required for local concentration of Dishevelled (MIG-5) in the ABar cortex adjacent to C. These findings establish a new role for syndecan in Wnt-dependent spindle orientation. © 2014. Published by The Company of Biologists Ltd.

Intra-spindle Microtubule Assembly Regulates Clustering of Microtubule-Organizing Centers during Early Mouse Development.

PubMed

Watanabe, Sadanori; Shioi, Go; Furuta, Yasuhide; Goshima, Gohta

2016-04-05

Errors during cell division in oocytes and early embryos are linked to birth defects in mammals. Bipolar spindle assembly in early mouse embryos is unique in that three or more acentriolar microtubule-organizing centers (MTOCs) are initially formed and are then clustered into two spindle poles. Using a knockout mouse and live imaging of spindles in embryos, we demonstrate that MTOC clustering during the blastocyst stage requires augmin, a critical complex for MT-dependent MT nucleation within the spindle. Functional analyses in cultured cells with artificially increased numbers of centrosomes indicate that the lack of intra-spindle MT nucleation, but not loss of augmin per se or overall reduction of spindle MTs, is the cause of clustering failure. These data suggest that onset of mitosis with three or more MTOCs is turned into a typical bipolar division through augmin-dependent intra-spindle MT assembly. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

77 FR 5838 - Notice of Intent To Repatriate Cultural Items: USDA Forest Service, Coconino National Forest...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-06

.... The 12 unassociated funerary objects are: 7 projectile points, 4 bone whistles and 1 spindle whorl... bone awl. Based on the ceramic collection, material culture and architecture, the New Caves Site has... trumpet; 1 shell artifact; 1 bone needle; 1 bone hairpin; 1 bone knife; 5 stone knives; 1 stone hammer...

Fusiform Rust of Southern Pines

Treesearch

W. R. Phelps; F. L. Czabator

1978-01-01

Fusiform rust, caused by the fungus Cronartium fusiforme Hedg. & Hunt ex Cumm., is distributed in the Southern United States from Maryland to Florida and west to Texas and southern Arkansas. Infections by the fungus, which develops at or near the point of infection, result in tapered, spindle-shaped swells, called galls, on branches and stems of pines. (see photo...

Modal identification of spindle-tool unit in high-speed machining

NASA Astrophysics Data System (ADS)

Gagnol, Vincent; Le, Thien-Phu; Ray, Pascal

2011-10-01

The accurate knowledge of high-speed motorised spindle dynamic behaviour during machining is important in order to ensure the reliability of machine tools in service and the quality of machined parts. More specifically, the prediction of stable cutting regions, which is a critical requirement for high-speed milling operations, requires the accurate estimation of tool/holder/spindle set dynamic modal parameters. These estimations are generally obtained through Frequency Response Function (FRF) measurements of the non-rotating spindle. However, significant changes in modal parameters are expected to occur during operation, due to high-speed spindle rotation. The spindle's modal variations are highlighted through an integrated finite element model of the dynamic high-speed spindle-bearing system, taking into account rotor dynamics effects. The dependency of dynamic behaviour on speed range is then investigated and determined with accuracy. The objective of the proposed paper is to validate these numerical results through an experiment-based approach. Hence, an experimental setup is elaborated to measure rotating tool vibration during the machining operation in order to determine the spindle's modal frequency variation with respect to spindle speed in an industrial environment. The identification of natural frequencies of the spindle under rotating conditions is challenging, due to the low number of sensors and the presence of many harmonics in the measured signals. In order to overcome these issues and to extract the characteristics of the system, the spindle modes are determined through a 3-step procedure. First, spindle modes are highlighted using the Frequency Domain Decomposition (FDD) technique, with a new formulation at the considered rotating speed. These extracted modes are then analysed through the value of their respective damping ratios in order to separate the harmonics component from structural spindle natural frequencies. Finally, the stochastic properties of the modes are also investigated by considering the probability density of the retained modes. Results show a good correlation between numerical and experiment-based identified frequencies. The identified spindle-tool modal properties during machining allow the numerical model to be considered as representative of the real dynamic properties of the system.

The Development Of Drosophila Melanogaster under Different Duration Space Flight and Subsequent Adaptation to Earth Gravity.

PubMed

Ogneva, Irina V; Belyakin, Stepan N; Sarantseva, Svetlana V

2016-01-01

In prospective human exploration of outer space, the need to preserve a species over several generations under changed gravity conditions may arise. This paper demonstrates our results in the creation of the third generation of fruit fly Drosophila melanogaster (third-stage larvae) during the 44.5-day space flight (Foton-M4 satellite (2014, Russia)), then the fourth generation on Earth and the fifth generation again in conditions of the 12-day space flight (2014, in the Russian Segment of the ISS). The species preserves fertility despite a number of changes in the level of expression and content of cytoskeletal proteins, which are the key components of the cleavage spindle and the contractile ring of cells. The results of transcriptome screening and space analysis of cytoskeletal proteins show that the exposure to weightless conditions leads to the increased transcription of metabolic genes, cuticle components and the decreased transcription of genes involved in morphogenesis, cell differentiation, cytoskeletal organization and genes associated with the plasma membrane. "Subsequent" exposure to the microgravity for 12 days resulted in an even more significant increase/decrease in the transcription of the same genes. On the contrary, the transition from the microgravity conditions to the gravity of Earth leads to the increased transcription of genes whose products are involved in the morphogenesis, cytoskeletal organization, motility of cells and transcription regulation, and to the decreased transcription of cuticle genes and proteolytic processes.

The Development Of Drosophila Melanogaster under Different Duration Space Flight and Subsequent Adaptation to Earth Gravity

PubMed Central

Belyakin, Stepan N.; Sarantseva, Svetlana V.

2016-01-01

In prospective human exploration of outer space, the need to preserve a species over several generations under changed gravity conditions may arise. This paper demonstrates our results in the creation of the third generation of fruit fly Drosophila melanogaster (third-stage larvae) during the 44.5-day space flight (Foton-M4 satellite (2014, Russia)), then the fourth generation on Earth and the fifth generation again in conditions of the 12-day space flight (2014, in the Russian Segment of the ISS). The species preserves fertility despite a number of changes in the level of expression and content of cytoskeletal proteins, which are the key components of the cleavage spindle and the contractile ring of cells. The results of transcriptome screening and space analysis of cytoskeletal proteins show that the exposure to weightless conditions leads to the increased transcription of metabolic genes, cuticle components and the decreased transcription of genes involved in morphogenesis, cell differentiation, cytoskeletal organization and genes associated with the plasma membrane. “Subsequent” exposure to the microgravity for 12 days resulted in an even more significant increase/decrease in the transcription of the same genes. On the contrary, the transition from the microgravity conditions to the gravity of Earth leads to the increased transcription of genes whose products are involved in the morphogenesis, cytoskeletal organization, motility of cells and transcription regulation, and to the decreased transcription of cuticle genes and proteolytic processes. PMID:27861601

Low-grade sinonasal sarcoma with neural and myogenic features: a clinicopathologic analysis of 28 cases.

PubMed

Lewis, Jason T; Oliveira, Andre M; Nascimento, Antonio G; Schembri-Wismayer, David; Moore, Eric A; Olsen, Kerry D; Garcia, Joaquin G; Lonzo, Melissa L; Lewis, Jean E

2012-04-01

Sarcomas of the sinonasal region are rare. We describe a distinct spindle cell sarcoma of the sinonasal region characterized by concomitant neural and myogenic differentiation. Consultation files and surgical cases from Mayo Clinic were reviewed. Twenty-eight cases were identified that met the inclusion criteria. Clinical data were collected from medical records, consultation letters, and referring pathologists. Reverse transcriptase-polymerase chain reaction for synovial sarcoma fusion transcripts was performed on 18 cases. Cytogenetic studies were performed on 2 cases. The 21 female and 7 male patients ranged in age from 24 to 85 years (mean, 52 y). All cases showed a characteristic histology, which included a cellular spindle cell neoplasm with uniform, elongate nuclei and an infiltrative growth pattern. All tumors demonstrated expression of S-100 with actin positivity in 96% of cases tested. Reverse transcriptase-polymerase chain reaction for synovial sarcoma fusion transcripts was negative in all cases tested. Cytogenetic studies conducted on 2 cases demonstrated the chromosomal translocation t(2;4). The nasal cavity (54%) and ethmoid sinus (57%) were the most commonly involved areas, singly or in combination. Follow-up information was available for 57% (16/28) of cases, with a mean of 8.3 years. Of these, 44% (7/16) experienced at least 1 recurrence. No patient has developed metastases or died of disease. We describe a unique tumor with a characteristic morphologic, immunophenotypic, and cytogenetic profile. On the basis of the locally aggressive nature of this lesion we believe it is best considered a low-grade sarcoma and suggest the term low-grade sinonasal sarcoma with neural and myogenic features.

Sequential activities of Dynein, Mud and Asp in centrosome-spindle coupling maintain centrosome number upon mitosis.

PubMed

Bosveld, Floris; Ainslie, Anna; Bellaïche, Yohanns

2017-10-15

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 about 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. Altogether, we propose that Dynein, Mud and Asp operate sequentially during the cell cycle to ensure efficient centrosome-spindle coupling in mitosis, thereby preventing centrosome mis-segregation to maintain centrosome number. © 2017. Published by The Company of Biologists Ltd.

Adaptive vibration control using synchronous demodulation with machine tool controller motor commutation

DOEpatents

Hopkins, David James [Livermore, CA

2008-05-13

A control system and method for actively reducing vibration in a spindle housing caused by unbalance forces on a rotating spindle, by measuring the force-induced spindle-housing motion, determining control signals based on synchronous demodulation, and provide compensation for the measured displacement to cancel or otherwise reduce or attenuate the vibration. In particular, the synchronous demodulation technique is performed to recover a measured spindle housing displacement signal related only to the rotation of a machine tool spindle, and consequently rejects measured displacement not related to spindle motion or synchronous to a cycle of revolution. Furthermore, the controller actuates at least one voice-coil (VC) motor, to cancel the original force-induced motion, and adapts the magnitude of voice coil signal until this measured displacement signal is brought to a null. In order to adjust the signal to a null, it must have the correct phase relative to the spindle angle. The feedback phase signal is used to adjust a common (to both outputs) commutation offset register (offset relative to spindle encoder angle) to force the feedback phase signal output to a null. Once both of these feedback signals are null, the system is compensating properly for the spindle-induced motion.

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

PubMed

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. © 2015 European Sleep Research Society.

Akap350 Recruits Eb1 to The Spindle Poles, Ensuring Proper Spindle Orientation and Lumen Formation in 3d Epithelial Cell Cultures.

PubMed

Almada, Evangelina; Tonucci, Facundo M; Hidalgo, Florencia; Ferretti, Anabela; Ibarra, Solange; Pariani, Alejandro; Vena, Rodrigo; Favre, Cristián; Girardini, Javier; Kierbel, Arlinet; Larocca, M Cecilia

2017-11-02

The organization of epithelial cells to form hollow organs with a single lumen requires the accurate three-dimensional arrangement of cell divisions. Mitotic spindle orientation is defined by signaling pathways that provide molecular links between specific spots at the cell cortex and astral microtubules, which have not been fully elucidated. AKAP350 is a centrosomal/Golgi scaffold protein, implicated in the regulation of microtubule dynamics. Using 3D epithelial cell cultures, we found that cells with decreased AKAP350 expression (AKAP350KD) formed polarized cysts with abnormal lumen morphology. Analysis of mitotic cells in AKAP350KD cysts indicated defective spindle alignment. We established that AKAP350 interacts with EB1, a microtubule associated protein that regulates spindle orientation, at the spindle poles. Decrease of AKAP350 expression lead to a significant reduction of EB1 levels at spindle poles and astral microtubules. Conversely, overexpression of EB1 rescued the defective spindle orientation induced by deficient AKAP350 expression. The specific delocalization of the AKAP350/EB1complex from the centrosome decreased EB1 levels at astral microtubules and lead to the formation of 3D-organotypic structures which resembled AKAP350KD cysts. We conclude that AKAP350 recruits EB1 to the spindle poles, ensuring EB1 presence at astral microtubules and proper spindle orientation during epithelial morphogenesis.

Assessing the Contributions of Motor Enzymes and Microtubule Dynamics to Mitotic Chromosome Motions.

PubMed

McIntosh, J Richard

2017-10-06

During my graduate work with Keith Porter, I became fascinated by the mitotic spindle, an interest that has motivated much of my scientific work ever since. I began spindle studies by using electron microscopes, instruments that have made significant contributions to our understanding of spindle organization. Such instruments have helped to elucidate the distributions of spindle microtubules, the interactions among them, their molecular polarity, and their associations with both kinetochores and spindle poles. Our lab has also investigated some processes of spindle physiology: microtubule dynamics, the actions of microtubule-associated proteins (including motor enzymes), the character of forces generated by specific spindle components, and factors that control mitotic progression. Here, I give a personal perspective on some of this intellectual history and on what recent discoveries imply about the mechanisms of chromosome motion.

Self-Organization and Forces in the Mitotic Spindle.

PubMed

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.

The Drosophila Microtubule-Associated Protein Mars Stabilizes Mitotic Spindles by Crosslinking Microtubules through Its N-Terminal Region

PubMed Central

Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

2013-01-01

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. PMID:23593258

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

NASA Astrophysics Data System (ADS)

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.

The muscle spindle as a feedback element in muscle control

NASA Technical Reports Server (NTRS)

Andrews, L. T.; Iannone, A. M.; Ewing, D. J.

1973-01-01

The muscle spindle, the feedback element in the myotatic (stretch) reflex, is a major contributor to muscular control. Therefore, an accurate description of behavior of the muscle spindle during active contraction of the muscle, as well as during passive stretch, is essential to the understanding of muscle control. Animal experiments were performed in order to obtain the data necessary to model the muscle spindle. Spectral density functions were used to identify a linear approximation of the two types of nerve endings from the spindle. A model reference adaptive control system was used on a hybrid computer to optimize the anatomically defined lumped parameter estimate of the spindle. The derived nonlinear model accurately predicts the behavior of the muscle spindle both during active discharge and during its silent period. This model is used to determine the mechanism employed to control muscle movement.

Goniometric measurement of hip motion in cycling while standing.

PubMed

Hull, M L; Beard, A; Varma, H

1990-01-01

The purpose of this study was to develop an instrument for quantifying the motion of the hip relative to the bicycle while cycling in the standing position. Because of the need to measure hip motion on the road as well as in the laboratory, a goniometer which locates the hip using spherical coordinates was designed. The goniometer is presented first, followed by the development of the equations that enable the distance from the joint center to the pedal spindle to be determined. The orientation of this line segment is specified by calculating two angles referenced to the frame. Also outlined are the procedures used to both calibrate the goniometer and perform an accuracy check. The results of this check indicate that the attachment point of the goniometer to the rider can be located to within 2.5 mm of the true position. The goniometer was used to record the hip movement patterns of six subjects who cycled in the standing position on a treadmill. Representative results from one test subject who cycled at 6% grade and 25 km h-1 are presented. Results indicate that the bicycle is leaned from side to side with the frequency of leaning equal to the frequency of pedalling. Extreme lean angles are +/- 6 degrees. The distance from the hip to the pedal varies approximately sinusoidally with frequency equal to pedalling rate and amplitude somewhat less than crank arm length. The absolute elevation of the hip, however, exhibits two cycles for each crank cycle. Asymmetry in the plot of elevation over a single crank cycle indicates that the pelvis rocks from side to side and that the elevation of the pelvis midpoint changes. Extreme values of the pelvis rocking angle are +/- 12 degrees. Highest pelvis midpoint elevations, however, do not occur at the same crank angles as those angles at which the pelvis rocking is extreme. It appears that the vertical motion of the hips affects pedalling mechanics when cycling in the standing position.

Spatiotemporal characteristics of sleep spindles depend on cortical location.

PubMed

Piantoni, Giovanni; Halgren, Eric; Cash, Sydney S

2017-02-01

Since their discovery almost one century ago, sleep spindles, 0.5-2s long bursts of oscillatory activity at 9-16Hz during NREM sleep, have been thought to be global and relatively uniform throughout the cortex. Recent work, however, has brought this concept into question but it remains unclear to what degree spindles are global or local and if their properties are uniform or location-dependent. We addressed this question by recording sleep in eight patients undergoing evaluation for epilepsy with intracranial electrocorticography, which combines high spatial resolution with extensive cortical coverage. We find that spindle characteristics are not uniform but are strongly influenced by the underlying cortical regions, particularly for spindle density and fundamental frequency. We observe both highly isolated and spatially distributed spindles, but in highly skewed proportions: while most spindles are restricted to one or very few recording channels at any given time, there are spindles that occur over widespread areas, often involving lateral prefrontal cortices and superior temporal gyri. Their co-occurrence is affected by a subtle but significant propagation of spindles from the superior prefrontal regions and the temporal cortices towards the orbitofrontal cortex. This work provides a brain-wide characterization of sleep spindles as mostly local graphoelements with heterogeneous characteristics that depend on the underlying cortical area. We propose that the combination of local characteristics and global organization reflects the dual properties of the thalamo-cortical generators and provides a flexible framework to support the many functions ascribed to sleep in general and spindles specifically. Copyright © 2016 Elsevier Inc. All rights reserved.

Response of lumbar paraspinal muscles spindles is greater to spinal manipulative loading compared with slower loading under length control.

PubMed

Pickar, Joel G; Sung, Paul S; Kang, Yu-Ming; Ge, Weiqing

2007-01-01

Spinal manipulation (SM) is a form of manual therapy used clinically to treat patients with low back and neck pain. The most common form of this maneuver is characterized as a high-velocity (duration <150 ms), low-amplitude (segmental translation <2 mm, rotation <4 degrees , and applied force 220-889 N) impulse thrust (high-velocity, low-amplitude spinal manipulation [HVLA-SM]). Clinical skill in applying an HVLA-SM lies in the practitioner's ability to control the duration and magnitude of the load (ie, the rate of loading), the direction in which the load is applied, and the contact point at which the load is applied. Control over its mechanical delivery is presumably related to its clinical effects. Biomechanical changes evoked by an HVLA-SM are thought to have physiological consequences caused, at least in part, by changes in sensory signaling from paraspinal tissues. If activation of afferent pathways does contribute to the effects of an HVLA-SM, it seems reasonable to anticipate that neural discharge might increase or decrease in a nonlinear fashion as the thrust duration approaches a threshold value. We hypothesized that the relationship between the duration of an impulsive thrust to a vertebra and paraspinal muscle spindle discharge would be nonlinear with an inflection near the duration of an HVLA-SM delivered clinically (<150 ms). In addition, we anticipated that muscle spindle discharge would be more sensitive to larger amplitude thrusts. A neurophysiological study of spinal manipulation using the lumbar spine of a feline model. Impulse thrusts (duration: 12.5, 25, 50, 100, 200, and 400 ms; amplitude 1 or 2 mm posterior to anterior) were applied to the spinous process of the L6 vertebra of deeply anesthetized cats while recording single unit activity from dorsal root filaments of muscle spindle afferents innervating the lumbar paraspinal muscles. A feedback motor was used in displacement control mode to deliver the impulse thrusts. The motor's drive arm was securely attached to the L6 spinous process via a forceps. As thrust duration became shorter, the discharge of the lumbar paraspinal muscle spindles increased in a curvilinear fashion. A concave-up inflection occurred near the 100-ms duration eliciting both a higher frequency discharge compared with the longer durations and a substantially faster rate of change as thrust duration was shortened. This pattern was evident in paraspinal afferents with receptive fields both close and far from the midline. Paradoxically, spindle afferents were almost twice as sensitive to the 1-mm compared with the 2-mm amplitude thrust (6.2 vs. 3.3 spikes/s/mm/s). This latter finding may be related to the small versus large signal range properties of muscle spindles. The results indicate that the duration and amplitude of a spinal manipulation elicit a pattern of discharge from paraspinal muscle spindles different from slower mechanical inputs. Clinically, these parameters may be important determinants of an HVLA-SM's therapeutic benefit.

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

ERIC Educational Resources Information Center

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…

Soft tissue angiofibroma: Clinicopathologic, immunohistochemical and molecular analysis of 14 cases.

PubMed

Bekers, Elise M; Groenen, Patricia J T A; Verdijk, Marian A J; Raaijmakers-van Geloof, Winny L; Roepman, Paul; Vink, Robert; Gilhuijs, Nathalie D B; van Gorp, Joost M; Bovée, Judith V M G; Creytens, David H; Flanagan, Adrienne M; Suurmeijer, Albert J H; Mentzel, Thomas; Arbajian, Elsa; Flucke, Uta

2017-10-01

Soft tissue angiofibroma is rare and has characteristic histomorphological and genetic features. For diagnostic purposes, there are no specific antibodies available. Fourteen lesions (6 females, 8 males; age range 7-67 years) of the lower extremities (12) and trunk (2) were investigated by immunohistochemistry, including for the first time NCOA2. NCOA2 was also tested in a control group of other spindle cell lesions. The known fusion-genes (AHRR-NCOA2 and GTF2I-NCOA2) were examined using RT-PCR in order to evaluate their diagnostic value. Cases in which no fusion gene was detected were additionally analysed by RNA sequencing. All cases tested showed nuclear expression of NCOA2. However, this was not specific since other spindle cell neoplasms also expressed this marker in a high percentage of cases. Other variably positive markers were EMA, SMA, desmin and CD34. STAT6 was negative in the cases tested. By RT-PCR for the most frequently observed fusions, an AHRR-NCOA2 fusion transcript was found in 9/14 cases. GTF2I-NCOA2 was not detected in the remaining cases (n = 3). RNA sequencing revealed three additional positive cases; two harbored a AHRR-NCOA2 fusion and one case a novel GAB1-ABL1 fusion. Two cases failed molecular analysis due to poor RNA quality. In conclusion, the AHRR-NCOA2 fusion is a frequent finding in soft tissue angiofibroma, while GTF2I-NCOA2 seems to be a rare genetic event. For the first time, we report a GAB1-ABL1 fusion in a soft tissue angiofibroma of a child. Nuclear expression of NCOA2 is not discriminating when compared with other spindle cell neoplasms. © 2017 Wiley Periodicals, Inc.

Mechanisms of plant spindle formation.

PubMed

Zhang, Han; Dawe, R Kelly

2011-04-01

In eukaryotes, the formation of a bipolar spindle is necessary for the equal segregation of chromosomes to daughter cells. Chromosomes, microtubules and kinetochores all contribute to spindle morphogenesis and have important roles during mitosis. A unique property of flowering plant cells is that they entirely lack centrosomes, which in animals have a major role in spindle formation. The absence of these important structures suggests that plants have evolved novel mechanisms to assure chromosome segregation. In this review, we highlight some of the recent studies on plant mitosis and argue that plants utilize a variation of "spindle self-organization" that takes advantage of the early polarity of plant cells and accentuates the role of kinetochores in stabilizing the spindle midzone in prometaphase.

Targeting Alp7/TACC to the spindle pole body is essential for mitotic spindle assembly in fission yeast

PubMed Central

Tang, Ngang Heok; Okada, Naoyuki; Fong, Chii Shyang; Arai, Kunio; Sato, Masamitsu; Toda, Takashi

2014-01-01

The conserved TACC protein family localises to the centrosome (the spindle pole body, SPB in fungi) and mitotic spindles, thereby playing a crucial role in bipolar spindle assembly. However, it remains elusive how TACC proteins are recruited to the centrosome/SPB. Here, using fission yeast Alp7/TACC, we have determined clustered five amino acid residues within the TACC domain required for SPB localisation. Critically, these sequences are essential for the functions of Alp7, including proper spindle formation and mitotic progression. Moreover, we have identified pericentrin-like Pcp1 as a loading factor to the mitotic SPB, although Pcp1 is not a sole platform. PMID:24937146

Spatial signals link exit from mitosis to spindle position.

PubMed

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.

Sleep Spindles and Intelligence in Early Childhood--Developmental and Trait-Dependent Aspects

ERIC Educational Resources Information Center

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

2016-01-01

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…

The function of the sleep spindle: a physiological index of intelligence and a mechanism for sleep-dependent memory consolidation.

PubMed

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. Copyright © 2010 Elsevier Ltd. All rights reserved.

Integrating high-throughput genetic interaction mapping and high-content screening to explore yeast spindle morphogenesis

PubMed Central

Vizeacoumar, Franco J.; van Dyk, Nydia; S.Vizeacoumar, Frederick; Cheung, Vincent; Li, Jingjing; Sydorskyy, Yaroslav; Case, Nicolle; Li, Zhijian; Datti, Alessandro; Nislow, Corey; Raught, Brian; Zhang, Zhaolei; Frey, Brendan; Bloom, Kerry

2010-01-01

We describe the application of a novel screening approach that combines automated yeast genetics, synthetic genetic array (SGA) analysis, and a high-content screening (HCS) system to examine mitotic spindle morphogenesis. We measured numerous spindle and cellular morphological parameters in thousands of single mutants and corresponding sensitized double mutants lacking genes known to be involved in spindle function. We focused on a subset of genes that appear to define a highly conserved mitotic spindle disassembly pathway, which is known to involve Ipl1p, the yeast aurora B kinase, as well as the cell cycle regulatory networks mitotic exit network (MEN) and fourteen early anaphase release (FEAR). We also dissected the function of the kinetochore protein Mcm21p, showing that sumoylation of Mcm21p regulates the enrichment of Ipl1p and other chromosomal passenger proteins to the spindle midzone to mediate spindle disassembly. Although we focused on spindle disassembly in a proof-of-principle study, our integrated HCS-SGA method can be applied to virtually any pathway, making it a powerful means for identifying specific cellular functions. PMID:20065090

The Kinesin-Related Protein, Hset, Opposes the Activity of Eg5 and Cross-Links Microtubules in the Mammalian Mitotic Spindle

PubMed Central

Mountain, Vicki; Simerly, Calvin; Howard, Louisa; Ando, Asako; Schatten, Gerald; Compton, Duane A.

1999-01-01

We have prepared antibodies specific for HSET, the human homologue of the KAR3 family of minus end-directed motors. Immuno-EM with these antibodies indicates that HSET frequently localizes between microtubules within the mammalian metaphase spindle consistent with a microtubule cross-linking function. Microinjection experiments show that HSET activity is essential for meiotic spindle organization in murine oocytes and taxol-induced aster assembly in cultured cells. However, inhibition of HSET did not affect mitotic spindle architecture or function in cultured cells, indicating that centrosomes mask the role of HSET during mitosis. We also show that (acentrosomal) microtubule asters fail to assemble in vitro without HSET activity, but simultaneous inhibition of HSET and Eg5, a plus end-directed motor, redresses the balance of forces acting on microtubules and restores aster organization. In vivo, centrosomes fail to separate and monopolar spindles assemble without Eg5 activity. Simultaneous inhibition of HSET and Eg5 restores centrosome separation and, in some cases, bipolar spindle formation. Thus, through microtubule cross-linking and oppositely oriented motor activity, HSET and Eg5 participate in spindle assembly and promote spindle bipolarity, although the activity of HSET is not essential for spindle assembly and function in cultured cells because of centrosomes. PMID:10525540

Inscuteable Regulates the Pins-Mud Spindle Orientation Pathway

PubMed Central

Mauser, Jonathon F.; Prehoda, Kenneth E.

2012-01-01

During asymmetric cell division, alignment of the mitotic spindle with the cell polarity axis ensures that the cleavage furrow separates fate determinants into distinct daughter cells. The protein Inscuteable (Insc) is thought to link cell polarity and spindle positioning in diverse systems by binding the polarity protein Bazooka (Baz; aka Par-3) and the spindle orienting protein Partner of Inscuteable (Pins; mPins or LGN in mammals). Here we investigate the mechanism of spindle orientation by the Insc-Pins complex. Previously, we defined two Pins spindle orientation pathways: a complex with Mushroom body defect (Mud; NuMA in mammals) is required for full activity, whereas binding to Discs large (Dlg) is sufficient for partial activity. In the current study, we have examined the role of Inscuteable in mediating downstream Pins-mediated spindle orientation pathways. We find that the Insc-Pins complex requires Gαi for partial activity and that the complex specifically recruits Dlg but not Mud. In vitro competition experiments revealed that Insc and Mud compete for binding to the Pins TPR motifs, while Dlg can form a ternary complex with Insc-Pins. Our results suggest that Insc does not passively couple polarity and spindle orientation but preferentially inhibits the Mud pathway, while allowing the Dlg pathway to remain active. Insc-regulated complex assembly may ensure that the spindle is attached to the cortex (via Dlg) before activation of spindle pulling forces by Dynein/Dynactin (via Mud). PMID:22253744

Oocyte spindle proteomics analysis leading to rescue of chromosome congression defects in cloned embryos

PubMed Central

Duan, Xunbao; Zhong, Zhisheng; Potireddy, Santhi; Moncada, Camilo; Merali, Salim; Latham, Keith E.

2015-01-01

Embryos produced by somatic cell nuclear transfer (SCNT) display low term developmental potential. This is associated with deficiencies in spindle composition prior to activation and at early mitotic divisions, including failure to assemble certain proteins on the spindle. The protein-deficient spindles are accompanied by chromosome congression defects prior to activation and during the first mitotic divisions of the embryo. The molecular basis for these deficiencies and how they might be avoided are unknown. Proteomic analyses of spindles isolated from normal metaphase II (MII) stage oocytes and SCNT constructs, along with a systematic immunofluorescent survey of known spindle-associated proteins were undertaken. This was the first proteomics study of mammalian oocyte spindles. The study revealed four proteins as being deficient in spindles of SCNT embryos in addition to those previously identified; these were clathrin heavy chain (CLTC), aurora B kinase, dynactin 4, and casein kinase 1 alpha. Due to substantial reduction in CLTC abundance after spindle removal, we undertook functional studies to explore the importance of CLTC in oocyte spindle function and in chromosome congression defects of cloned embryos. Using siRNA knockdown we demonstrated an essential role for CLTC in chromosome congression during oocyte maturation. We also demonstrated rescue of chromosome congression defects in SCNT embryos at the first mitosis using CLTC mRNA injection. These studies are the first to employ proteomics analyses coupled to functional interventions to rescue a specific molecular defect in cloned embryos. PMID:20883044

Stage-independent, single lead EEG sleep spindle detection using the continuous wavelet transform and local weighted smoothing.

PubMed

Tsanas, Athanasios; Clifford, Gari D

2015-01-01

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 toward 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.

Initial diameter of the polar body contractile ring is minimized by the centralspindlin complex.

PubMed

Fabritius, Amy S; Flynn, Jonathan R; McNally, Francis J

2011-11-01

Polar body formation is an essential step in forming haploid eggs from diploid oocytes. This process involves completion of a highly asymmetric cytokinesis that results in a large egg and two small polar bodies. Unlike mitotic contractile rings, polar body contractile rings assemble over one spindle pole so that the spindle must move through the contractile ring before cytokinesis. During time-lapse imaging of C. elegans meiosis, the contractile ring moved downward along the length of the spindle and completed scission at the midpoint of the spindle, even when spindle length or rate of ring movement was increased. Patches of myosin heavy chain and dynamic furrowing of the plasma membrane over the entire embryo suggested that global cortical contraction forces the meiotic spindle and overlying membrane out through the contractile ring center. Consistent with this model, depletion of myosin phosphatase increased the velocity of ring movement along the length of the spindle. Global dynamic furrowing, which was restricted to anaphase I and II, was dependent on myosin II, the anaphase promoting complex and separase, but did not require cortical contact by the spindle. Large cortical patches of myosin during metaphase I and II indicated that myosin was already in the active form before activation of separase. To identify the signal at the midpoint of the anaphase spindle that induces scission, we depleted two proteins that mark the exact midpoint of the spindle during late anaphase, CYK-4 and ZEN-4. Depletion of either protein resulted in the unexpected phenotype of initial ingression of a polar body ring with twice the diameter of wild type. This phenotype revealed a novel mechanism for minimizing polar body size. Proteins at the spindle midpoint are required for initial ring ingression to occur close to the membrane-proximal spindle pole. 2011 Elsevier Inc. All rights reserved.

Nonequilibrium fluctuations in metaphase spindles: polarized light microscopy, image registration, and correlation functions

NASA Astrophysics Data System (ADS)

Brugués, Jan; Needleman, Daniel J.

2010-02-01

Metaphase spindles are highly dynamic, nonequilibrium, steady-state structures. We study the internal fluctuations of spindles by computing spatio-temporal correlation functions of movies obtained from quantitative polarized light microscopy. These correlation functions are only physically meaningful if corrections are made for the net motion of the spindle. We describe our image registration algorithm in detail and we explore its robustness. Finally, we discuss the expression used for the estimation of the correlation function in terms of the nematic order of the microtubules which make up the spindle. Ultimately, studying the form of these correlation functions will provide a quantitative test of the validity of coarse-grained models of spindle structure inspired from liquid crystal physics.

Life Cycle Characterization of Sulfolobus Monocaudavirus 1, an Extremophilic Spindle-Shaped Virus with Extracellular Tail Development

PubMed Central

Uldahl, Kristine B.; Jensen, Signe B.; Bhoobalan-Chitty, Yuvaraj; Martínez-Álvarez, Laura; Papathanasiou, Pavlos

2016-01-01

ABSTRACT We provide here, for the first time, insights into the initial infection stages of a large spindle-shaped archaeal virus and explore the following life cycle events. Our observations suggest that Sulfolobus monocaudavirus 1 (SMV1) exhibits a high adsorption rate and that virions adsorb to the host cells via three distinct attachment modes: nosecone association, body association, and body/tail association. In the body/tail association mode, the entire virion, including the tail(s), aligns to the host cell surface and the main body is greatly flattened, suggesting a possible fusion entry mechanism. Upon infection, the intracellular replication cycle lasts about 8 h, at which point the virions are released as spindle-shaped tailless particles. Replication of the virus retarded host growth but did not cause lysis of the host cells. Once released from the host and at temperatures resembling that of its natural habitat, SMV1 starts developing one or two tails. This exceptional property of undergoing a major morphological development outside, and independently of, the host cell has been reported only once before for the related Acidianus two-tailed virus. Here, we show that SMV1 can develop tails of more than 900 nm in length, more than quadrupling the total virion length. IMPORTANCE Very little is known about the initial life cycle stages of viruses infecting hosts of the third domain of life, Archaea. This work describes the first example of an archaeal virus employing three distinct association modes. The virus under study, Sulfolobus monocaudavirus 1, is a representative of the large spindle-shaped viruses that are frequently found in acidic hot springs. The results described here will add valuable knowledge about Archaea, the least studied domain in the virology field. PMID:27053548

Life Cycle Characterization of Sulfolobus Monocaudavirus 1, an Extremophilic Spindle-Shaped Virus with Extracellular Tail Development.

PubMed

Uldahl, Kristine B; Jensen, Signe B; Bhoobalan-Chitty, Yuvaraj; Martínez-Álvarez, Laura; Papathanasiou, Pavlos; Peng, Xu

2016-06-15

We provide here, for the first time, insights into the initial infection stages of a large spindle-shaped archaeal virus and explore the following life cycle events. Our observations suggest that Sulfolobus monocaudavirus 1 (SMV1) exhibits a high adsorption rate and that virions adsorb to the host cells via three distinct attachment modes: nosecone association, body association, and body/tail association. In the body/tail association mode, the entire virion, including the tail(s), aligns to the host cell surface and the main body is greatly flattened, suggesting a possible fusion entry mechanism. Upon infection, the intracellular replication cycle lasts about 8 h, at which point the virions are released as spindle-shaped tailless particles. Replication of the virus retarded host growth but did not cause lysis of the host cells. Once released from the host and at temperatures resembling that of its natural habitat, SMV1 starts developing one or two tails. This exceptional property of undergoing a major morphological development outside, and independently of, the host cell has been reported only once before for the related Acidianus two-tailed virus. Here, we show that SMV1 can develop tails of more than 900 nm in length, more than quadrupling the total virion length. Very little is known about the initial life cycle stages of viruses infecting hosts of the third domain of life, Archaea This work describes the first example of an archaeal virus employing three distinct association modes. The virus under study, Sulfolobus monocaudavirus 1, is a representative of the large spindle-shaped viruses that are frequently found in acidic hot springs. The results described here will add valuable knowledge about Archaea, the least studied domain in the virology field. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

The effects of eszopiclone on sleep spindles and memory consolidation in schizophrenia: a randomized placebo-controlled trial.

PubMed

Wamsley, Erin J; Shinn, Ann K; Tucker, Matthew A; Ono, Kim E; McKinley, Sophia K; Ely, Alice V; Goff, Donald C; Stickgold, Robert; Manoach, Dara S

2013-09-01

In schizophrenia there is a dramatic reduction of sleep spindles that predicts deficient sleep-dependent memory consolidation. Eszopiclone (Lunesta), a non-benzodiazepine hypnotic, acts on γ-aminobutyric acid (GABA) neurons in the thalamic reticular nucleus where spindles are generated. We investigated whether eszopiclone could increase spindles and thereby improve memory consolidation in schizophrenia. In a double-blind design, patients were randomly assigned to receive either placebo or 3 mg of eszopiclone. Patients completed Baseline and Treatment visits, each consisting of two consecutive nights of polysomnography. On the second night of each visit, patients were trained on the motor sequence task (MST) at bedtime and tested the following morning. Academic research center. Twenty-one chronic, medicated schizophrenia outpatients. We compared the effects of two nights of eszopiclone vs. placebo on stage 2 sleep spindles and overnight changes in MST performance. Eszopiclone increased the number and density of spindles over baseline levels significantly more than placebo, but did not significantly enhance overnight MST improvement. In the combined eszopiclone and placebo groups, spindle number and density predicted overnight MST improvement. Eszopiclone significantly increased sleep spindles, which correlated with overnight motor sequence task improvement. These findings provide partial support for the hypothesis that the spindle deficit in schizophrenia impairs sleep-dependent memory consolidation and may be ameliorated by eszopiclone. Larger samples may be needed to detect a significant effect on memory. Given the general role of sleep spindles in cognition, they offer a promising novel potential target for treating cognitive deficits in schizophrenia.

Electroencephalogram spindle activity during dexmedetomidine sedation and physiological sleep.

PubMed

Huupponen, E; Maksimow, A; Lapinlampi, P; Särkelä, M; Saastamoinen, A; Snapir, A; Scheinin, H; Scheinin, M; Meriläinen, P; Himanen, S-L; Jääskeläinen, S

2008-02-01

Dexmedetomidine, a selective alpha(2)-adrenoceptor agonist, induces a unique, sleep-like state of sedation. The objective of the present work was to study human electroencephalogram (EEG) sleep spindles during dexmedetomidine sedation and compare them with spindles during normal physiological sleep, to test the hypothesis that dexmedetomidine exerts its effects via normal sleep-promoting pathways. EEG was continuously recorded from a bipolar frontopolar-laterofrontal derivation with Entropy Module (GE Healthcare) during light and deep dexmedetomidine sedation (target-controlled infusions set at 0.5 and 3.2 ng/ml) in 11 healthy subjects, and during physiological sleep in 10 healthy control subjects. Sleep spindles were visually scored and quantitatively analyzed for density, duration, amplitude (band-pass filtering) and frequency content (matching pursuit approach), and compared between the two groups. In visual analysis, EEG activity during dexmedetomidine sedation was similar to physiological stage 2 (S2) sleep with slight to moderate amount of slow-wave activity and abundant sleep spindle activity. In quantitative EEG analyses, sleep spindles were similar during dexmedetomidine sedation and normal sleep. No statistically significant differences were found in spindle density, amplitude or frequency content, but the spindles during dexmedetomidine sedation had longer duration (mean 1.11 s, SD 0.14 s) than spindles in normal sleep (mean 0.88 s, SD 0.14 s; P=0.0014). Analysis of sleep spindles shows that dexmedetomidine produces a state closely resembling physiological S2 sleep in humans, which gives further support to earlier experimental evidence for activation of normal non-rapid eye movement sleep-promoting pathways by this sedative agent.

The Multidimensional Aspects of Sleep Spindles and Their Relationship to Word-Pair Memory Consolidation.

PubMed

Lustenberger, Caroline; Wehrle, Flavia; Tüshaus, Laura; Achermann, Peter; Huber, Reto

2015-07-01

Several studies proposed a link between sleep spindles and sleep dependent memory consolidation in declarative learning tasks. In addition to these state-like aspects of sleep spindles, they have also trait-like characteristics, i.e., were related to general cognitive performance, an important distinction that has often been neglected in correlative studies. Furthermore, from the multitude of different sleep spindle measures, often just one specific aspect was analyzed. Thus, we aimed at taking multidimensional aspects of sleep spindles into account when exploring their relationship to word-pair memory consolidation. Each subject underwent 2 study nights with all-night high-density electroencephalographic (EEG) recordings. Sleep spindles were automatically detected in all EEG channels. Subjects were trained and tested on a word-pair learning task in the evening, and retested in the morning to assess sleep related memory consolidation (overnight retention). Trait-like aspects refer to the mean of both nights and state-like aspects were calculated as the difference between night 1 and night 2. Sleep laboratory. Twenty healthy male subjects (age: 23.3 ± 2.1 y). Overnight retention was negatively correlated with trait-like aspects of fast sleep spindle density and positively with slow spindle density on a global level. In contrast, state-like aspects were observed for integrated slow spindle activity, which was positively related to the differences in overnight retention in specific regions. Our results demonstrate the importance of a multidimensional approach when investigating the relationship between sleep spindles and memory consolidation and thereby provide a more complete picture explaining divergent findings in the literature. © 2015 Associated Professional Sleep Societies, LLC.

Slow Sleep Spindle Activity, Declarative Memory, and General Cognitive Abilities in Children

PubMed Central

Hoedlmoser, Kerstin; Heib, Dominik P.J.; Roell, Judith; Peigneux, Philippe; Sadeh, Avi; Gruber, Georg; Schabus, Manuel

2014-01-01

Study Objectives: Functional interactions between sleep spindle activity, declarative memory consolidation, and general cognitive abilities in school-aged children. Design: Healthy, prepubertal children (n = 63; mean age 9.56 ± 0.76 y); ambulatory all-night polysomnography (2 nights); investigating the effect of prior learning (word pair association task; experimental night) versus nonlearning (baseline night) on sleep spindle activity; general cognitive abilities assessed using the Wechsler Intelligence Scale for Children-IV (WISC-IV). Measurements and Results: Analysis of spindle activity during nonrapid eye movement sleep (N2 and N3) evidenced predominant peaks in the slow (11-13 Hz) but not in the fast (13-15 Hz) sleep spindle frequency range (baseline and experimental night). Analyses were restricted to slow sleep spindles. Changes in spindle activity from the baseline to the experimental night were not associated with the overnight change in the number of recalled words reflecting declarative memory consolidation. Children with higher sleep spindle activity as measured at frontal, central, parietal, and occipital sites during both baseline and experimental nights exhibited higher general cognitive abilities (WISC-IV) and declarative learning efficiency (i.e., number of recalled words before and after sleep). Conclusions: Slow sleep spindles (11-13 Hz) in children age 8–11 y are associated with inter-individual differences in general cognitive abilities and learning efficiency. Citation: Hoedlmoser K, Heib DPJ, Roell J, Peigneux P, Sadeh A, Gruber G, Schabus M. Slow sleep spindle activity, declarative memory, and general cognitive abilities in children. SLEEP 2014;37(9):1501-1512. PMID:25142558

An allometric analysis of the number of muscle spindles in mammalian skeletal muscles

PubMed Central

Banks, R W

2006-01-01

An allometric analysis of the number of muscle spindles in relation to muscle mass in mammalian (mouse, rat, guinea-pig, cat, human) skeletal muscles is presented. It is shown that the trend to increasing number as muscle mass increases follows an isometric (length) relationship between species, whereas within a species, at least for the only essentially complete sample (human), the number of spindles scales, on average, with the square root rather than the cube root of muscle mass. An attempt is made to reconcile these apparently discrepant relationships. Use of the widely accepted spindle density (number of spindles g−1 of muscle) as a measure of relative abundance of spindles in different muscles is shown to be grossly misleading. It is replaced with the residuals of the linear regression of ln spindle number against ln muscle mass. Significant differences in relative spindle abundance as measured by residuals were found between regional groups of muscles: the greatest abundance is in axial muscles, including those concerned with head position, whereas the least is in muscles of the shoulder girdle. No differences were found between large and small muscles operating in parallel, or between antigravity and non-antigravity muscles. For proximal vs. distal muscles, spindles were significantly less abundant in the hand than the arm, but there was no difference between the foot and the leg. PMID:16761976

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

PubMed Central

Onishi, Masayuki; Yeong, Foong May

2016-01-01

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. PMID:27447488

Spindle-shaped Microstructures: Potential Models for Planktonic Life Forms on Other Worlds

NASA Technical Reports Server (NTRS)

Oehler, Dorothy Z.; Walsh, Maud M.; Sugitani, Kenichiro; House, Christopher H.

2014-01-01

Spindle-shaped, organic microstructures ("spindles") are now known from Archean cherts in three localities (Figs. 1-4): The 3 Ga Farrel Quartzite from the Pilbara of Australia [1]; the older, 3.3-3.4 Ga Strelley Pool Formation, also from the Pilbara of Australia [2]; and the 3.4 Ga Kromberg Formation of the Barberton Mountain Land of South Africa [3]. Though the spindles were previously speculated to be pseudofossils or epigenetic organic contaminants, a growing body of data suggests that these structures are bona fide microfossils and further, that they are syngenetic with the Archean cherts in which they occur [1-2, 4-10]. As such, the spindles are among some of the oldest-known organically preserved microfossils on Earth. Moreover, recent delta C-13 study of individual spindles from the Farrel Quartzite (using Secondary Ion Mass Spectrometry [SIMS]) suggests that the spindles may have been planktonic (living in open water), as opposed to benthic (living as bottom dwellers in contact with muds or sediments) [9]. Since most Precambrian microbiotas have been described from benthic, matforming communities, a planktonic lifestyle for the spindles suggests that these structures could represent a segment of the Archean biosphere that is poorly known. Here we synthesize the recent work on the spindles, and we add new observations regarding their geographic distribution, robustness, planktonic habit, and long-lived success. We then discuss their potential evolutionary and astrobiological significance.

Influence of proprioceptive feedback on the firing rate and recruitment of motoneurons

NASA Astrophysics Data System (ADS)

De Luca, C. J.; Kline, J. C.

2012-02-01

We investigated the relationships of the firing rate and maximal recruitment threshold of motoneurons recorded during isometric contraction with the number of spindles in individual muscles. At force levels above 10% of maximal voluntary contraction, the firing rate was inversely related to the number of spindles in a muscle, with the slope of the relationship increasing with force. The maximal recruitment threshold of motor units increased linearly with the number of spindles in the muscle. Thus, muscles with a greater number of spindles had lower firing rates and a greater maximal recruitment threshold. These findings may be explained by a mechanical interaction between muscle fibres and adjacent spindles. During low-level (0% to 10%) voluntary contractions, muscle fibres of recruited motor units produce force twitches that activate nearby spindles to respond with an immediate excitatory feedback that reaches maximal level. As the force increases further, the twitches overlap and tend towards tetanization, the muscle fibres shorten, the spindles slacken, their excitatory firings decrease, and the net excitation to the homonymous motoneurons decreases. Motoneurons of muscles with greater number of spindles receive a greater decrease in excitation which reduces their firing rates, increases their maximal recruitment threshold, and changes the motoneuron recruitment distribution.

MAPK-Activated Protein Kinase 2 Is Required for Mouse Meiotic Spindle Assembly and Kinetochore-Microtubule Attachment

PubMed Central

Qi, Shu-Tao; Tong, Jing-Shan; Wei, Liang; Li, Mo; Ouyang, Ying-Chun; Hou, Yi; Schatten, Heide; Sun, Qing-Yuan

2010-01-01

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. PMID:20596525

The chromokinesin Kid is required for maintenance of proper metaphase spindle size.

PubMed

Tokai-Nishizumi, Noriko; Ohsugi, Miho; Suzuki, Emiko; Yamamoto, Tadashi

2005-11-01

The human chromokinesin Kid/kinesin-10, a plus end-directed microtubule (MT)-based motor with both microtubule- and DNA-binding domains, is required for proper chromosome alignment at the metaphase plate. Here, we performed RNA interference experiments to deplete endogenous Kid from HeLa cells and confirmed defects in metaphase chromosome arm alignment in Kid-depleted cells. In addition, we noted a shortening of the spindle length, resulting in a pole-to-pole distance only 80% of wild type. The spindle microtubule-bundles with which Kid normally colocalize became less robust. Rescue of the two Kid deficiency phenotypes-imprecise chromosome alignment at metaphase and shortened spindles- exhibited distinct requirements. Mutants lacking either the DNA-binding domain or the MT motor ATPase failed to rescue the former defect, whereas rescue of the shortened spindle phenotype required neither activity. Kid also exhibits microtubule bundling activity in vitro, and rescue of the shortened spindle phenotype and the bundling activity displayed similar domain requirements, except that rescue required a coiled-coil domain not needed for bundling. These results suggest that distinct from its role in chromosome movement, Kid contributes to spindle morphogenesis by mediating spindle microtubules stabilization.

Micromanipulation studies of chromosome movement. II. Birefringent chromosomal fibers and the mechanical attachment of chromosomes to the spindle

PubMed Central

1979-01-01

The degree of mechanical coupling of chromosomes to the spindles of Nephrotoma and Trimeratropis primary spermatocytes varies with the stage of meiosis and the birefringent retardation of the chromosomal fibers. In early prometaphase, before birefringent chromosomal fibers have formed, a bivalent can be displaced toward a spindle pole by a single, continuous pull with a microneedle. Resistance to poleward displacement increases with increased development of the chromosomal fibers, reaching a maximum at metaphase. At this stage kinetochores cannot be displaced greater than 1 micrometer toward either spindle pole, even by a force which is sufficient to displace the entire spindle within the cell. The abolition of birefringence with either colcemid or vinblastine results in the loss of chromosome-spindle attachment. In the absence of birefringent fibers a chromosome can be displaced anywhere within the cell. The photochemical inactivation of colcemid by irradiation with 366-nm light results in the reformation of birefringent chromosomal fibers and the concomitant re-establishment of chromosome attachment to the spindle. These results support the hypothesis that the birefringent chromosomal fibers anchor the chromosomes to the spindle and transmit the force for anaphase chromosome movement. PMID:479316

Mucinous breast carcinoma with myoepithelial-like spindle cells.

PubMed

Miyake, Yasuyuki; Hirokawa, Mitsuyoshi; Norimatsu, Yoshiaki; Kanahara, Takuo; Monobe, Yasumasa; Ohno, Setsuyo; Miyamoto, Tomoyuki; Yakushiji, Hiromasa; Sakaguchi, Takuya; Aratake, Yatsuki; Ohno, Eiji

2009-06-01

Appearance of spindle cells has been believed as a benign index of breast cytology. But, we have frequently observed the spindle cells in smears from mucinous carcinoma of the breast. Here, we characterized the biochemical nature of the spindle cells, so as to clarify their identity in cytology. Nineteen cases of breast mucinous carcinoma were used for cytological examination. The spindle cells were located at edges of tumor cell nests and in the backgrounds of cytological specimens. Immunohistological examination revealed that the spindle cells exhibited both immunoreactivity against carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA). Immunoreactivity against vimentin, cytokeratin, or alpha-smooth muscle actin was, however, not observed. The mode of distribution of biochemical markers suggests that the positive cells for anti-CEA antibody and anti-EMA antibody are tumor cells compressed by mucin, while the vimentin-positive cells are fibroblasts. We assert that the presence of spindle cells can be a characteristic feature of mucinous carcinoma of the breast. Discrimination of the spindle cells in mucinous carcinoma from myoepithelial cells and naked bipolar nuclei in benign lesions was established here. It should facilitate precise diagnosis of breast cancer. (c) 2009 Wiley-Liss, Inc.

Spindle formation in the mouse embryo requires Plk4 in the absence of centrioles.

PubMed

Coelho, Paula A; Bury, Leah; Sharif, Bedra; Riparbelli, Maria G; Fu, Jingyan; Callaini, Giuliano; Glover, David M; Zernicka-Goetz, Magdalena

2013-12-09

During the first five rounds of cell division in the mouse embryo, spindles assemble in the absence of centrioles. Spindle formation initiates around chromosomes, but the microtubule nucleating process remains unclear. Here we demonstrate that Plk4, a protein kinase known as a master regulator of centriole formation, is also essential for spindle assembly in the absence of centrioles. Depletion of maternal Plk4 prevents nucleation and growth of microtubules and results in monopolar spindle formation. This leads to cytokinesis failure and, consequently, developmental arrest. We show that Plk4 function depends on its kinase activity and its partner protein, Cep152. Moreover, tethering Cep152 to cellular membranes sequesters Plk4 and is sufficient to trigger spindle assembly from ectopic membranous sites. Thus, the Plk4-Cep152 complex has an unexpected role in promoting microtubule nucleation in the vicinity of chromosomes to mediate bipolar spindle formation in the absence of centrioles. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Telomeres and centromeres have interchangeable roles in promoting meiotic spindle formation

PubMed Central

Fennell, Alex; Fernández-Álvarez, Alfonso; Tomita, Kazunori

2015-01-01

Telomeres and centromeres have traditionally been considered to perform distinct roles. During meiotic prophase, in a conserved chromosomal configuration called the bouquet, telomeres gather to the nuclear membrane (NM), often near centrosomes. We found previously that upon disruption of the fission yeast bouquet, centrosomes failed to insert into the NM at meiosis I and nucleate bipolar spindles. Hence, the trans-NM association of telomeres with centrosomes during prophase is crucial for efficient spindle formation. Nonetheless, in approximately half of bouquet-deficient meiocytes, spindles form properly. Here, we show that bouquet-deficient cells can successfully undergo meiosis using centromere–centrosome contact instead of telomere–centrosome contact to generate spindle formation. Accordingly, forced association between centromeres and centrosomes fully rescued the spindle defects incurred by bouquet disruption. Telomeres and centromeres both stimulate focal accumulation of the SUN domain protein Sad1 beneath the centrosome, suggesting a molecular underpinning for their shared spindle-generating ability. Our observations demonstrate an unanticipated level of interchangeability between the two most prominent chromosomal landmarks. PMID:25688135

SLK-dependent activation of ERMs controls LGN–NuMA localization and spindle orientation

PubMed Central

Machicoane, Mickael; de Frutos, Cristina A.; Fink, Jenny; Rocancourt, Murielle; Lombardi, Yannis; Garel, Sonia; Piel, Matthieu

2014-01-01

Mitotic spindle orientation relies on a complex dialog between the spindle microtubules and the cell cortex, in which F-actin has been recently implicated. Here, we report that the membrane–actin linkers ezrin/radixin/moesin (ERMs) are strongly and directly activated by the Ste20-like kinase at mitotic entry in mammalian cells. Using microfabricated adhesive substrates to control the axis of cell division, we found that the activation of ERMs plays a key role in guiding the orientation of the mitotic spindle. Accordingly, impairing ERM activation in apical progenitors of the mouse embryonic neocortex severely disturbed spindle orientation in vivo. At the molecular level, ERM activation promotes the polarized association at the mitotic cortex of leucine-glycine-asparagine repeat protein (LGN) and nuclear mitotic apparatus (NuMA) protein, two essential factors for spindle orientation. We propose that activated ERMs, together with Gαi, are critical for the correct localization of LGN–NuMA force generator complexes and hence for proper spindle orientation. PMID:24958772

O-Linked N-Acetylglucosamine Cycling Regulates Mitotic Spindle Organization*

PubMed Central

Tan, Ee Phie; Caro, Sarah; Potnis, Anish; Lanza, Christopher; Slawson, Chad

2013-01-01

Any defects in the correct formation of the mitotic spindle will lead to chromosomal segregation errors, mitotic arrest, or aneuploidy. We demonstrate that O-linked N-acetylglucosamine (O-GlcNAc), a post-translational modification of serine and threonine residues in nuclear and cytoplasmic proteins, regulates spindle function. In O-GlcNAc transferase or O-GlcNAcase gain of function cells, the mitotic spindle is incorrectly assembled. Chromosome condensation and centrosome assembly is impaired in these cells. The disruption in spindle architecture is due to a reduction in histone H3 phosphorylation by Aurora kinase B. However, gain of function cells treated with the O-GlcNAcase inhibitor Thiamet-G restored the assembly of the spindle and partially rescued histone phosphorylation. Together, these data suggest that the coordinated addition and removal of O-GlcNAc, termed O-GlcNAc cycling, regulates mitotic spindle organization and provides a potential new perspective on how O-GlcNAc regulates cellular events. PMID:23946484

HDAC8 functions in spindle assembly during mouse oocyte meiosis

PubMed Central

Shu, Jing; Chen, Xueqin; Shi, Yingjiao; Wang, Ensheng; Wang, Li; Hu, Qinbo; Dai, Yibo; Xiong, Bo

2017-01-01

HDAC8 is a class I histone deacetylase that functions in a variety of biological processes through its non-histone substrates. However, its roles during oocyte meiosis remain elusive. Here, we document that HDAC8 localizes at spindle poles and positively participates in the regulation of microtubule organization and spindle assembly in mouse oocytes. Depletion of HDAC8 by siRNA-based gene silencing results in various spindle defects and chromosome misalignment during oocyte meiotic maturation, accompanied by impaired kinetochore-microtubule attachments. Consequently, a higher incidence of aneuploidy is generated in HDAC8-depleted MII eggs. In addition, inhibition of HDAC8 activity with its selective inhibitor PCI-34051 phenocopies the spindle/chromosome defects resulting from HDAC8 depletion by siRNA injection. Finally, we find that HDAC8 is required for the correct localization of ϕ-tubulin to spindle poles. Collectively, these data reveal that HDAC8 plays a significant role in regulating spindle assembly and thus ensuring the euploidy in mouse eggs. PMID:28223544

Spatial signals link exit from mitosis to spindle position

PubMed Central

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

2016-01-01

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. DOI: http://dx.doi.org/10.7554/eLife.14036.001 PMID:27166637

Parvalbumin-positive interneurons mediate neocortical-hippocampal interactions that are necessary for memory consolidation

PubMed Central

Xia, Frances; Richards, Blake A; Tran, Matthew M; Josselyn, Sheena A

2017-01-01

Following learning, increased coupling between spindle oscillations in the medial prefrontal cortex (mPFC) and ripple oscillations in the hippocampus is thought to underlie memory consolidation. However, whether learning-induced increases in ripple-spindle coupling are necessary for successful memory consolidation has not been tested directly. In order to decouple ripple-spindle oscillations, here we chemogenetically inhibited parvalbumin-positive (PV+) interneurons, since their activity is important for regulating the timing of spiking activity during oscillations. We found that contextual fear conditioning increased ripple-spindle coupling in mice. However, inhibition of PV+ cells in either CA1 or mPFC eliminated this learning-induced increase in ripple-spindle coupling without affecting ripple or spindle incidence. Consistent with the hypothesized importance of ripple-spindle coupling in memory consolidation, post-training inhibition of PV+ cells disrupted contextual fear memory consolidation. These results indicate that successful memory consolidation requires coherent hippocampal-neocortical communication mediated by PV+ cells. PMID:28960176

Mounting arrangement for the drive system of an air-bearing spindle on a machine tool

DOEpatents

Lunsford, J.S.; Crisp, D.W.; Petrowski, P.L.

1987-12-07

The present invention is directed to a mounting arrangement for the drive system of an air-bearing spindle utilized on a machine tool such as a lathe. The mounting arrangement of the present invention comprises a housing which is secured to the casing of the air bearing in such a manner that the housing position can be selectively adjusted to provide alignment of the air-bearing drive shaft supported by the housing and the air-bearing spindle. Once this alignment is achieved the air between spindle and the drive arrangement is maintained in permanent alignment so as to overcome misalignment problems encountered in the operation of the machine tool between the air-bearing spindle and the shaft utilized for driving the air-bearing spindle.

Combination spindle-drive system for high precision machining

DOEpatents

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.

The Chromatin Protein DUET/MMD1 Controls Expression of the Meiotic Gene TDM1 during Male Meiosis in Arabidopsis

PubMed Central

Andreuzza, Sébastien; Nishal, Bindu; Singh, Aparna; Siddiqi, Imran

2015-01-01

Meiosis produces haploid cells essential for sexual reproduction. In yeast, entry into meiosis activates transcription factors which trigger a transcriptional cascade that results in sequential co-expression of early, middle and late meiotic genes. However, these factors are not conserved, and the factors and regulatory mechanisms that ensure proper meiotic gene expression in multicellular eukaryotes are poorly understood. Here, we report that DUET/MMD1, a PHD finger protein essential for Arabidopsis male meiosis, functions as a transcriptional regulator in plant meiosis. We find that DUET-PHD binds H3K4me2 in vitro, and show that this interaction is critical for function during meiosis. We also show that DUET is required for proper microtubule organization during meiosis II, independently of its function in meiosis I. Remarkably, DUET protein shows stage-specific expression, confined to diplotene. We identify two genes TDM1 and JAS with critical functions in cell cycle transitions and spindle organization in male meiosis, as DUET targets, with TDM1 being a direct target. Thus, DUET is required to regulate microtubule organization and cell cycle transitions during male meiosis, and functions as a direct transcription activator of the meiotic gene TDM1. Expression profiling showed reduced expression of a subset comprising about 12% of a known set of meiosis preferred genes in the duet mutant. Our results reveal the action of DUET as a transcriptional regulator during male meiosis in plants, and suggest that transcription of meiotic genes is under stagewise control in plants as in yeast. PMID:26348709

The Chromatin Protein DUET/MMD1 Controls Expression of the Meiotic Gene TDM1 during Male Meiosis in Arabidopsis.

PubMed

Andreuzza, Sébastien; Nishal, Bindu; Singh, Aparna; Siddiqi, Imran

2015-09-01

Meiosis produces haploid cells essential for sexual reproduction. In yeast, entry into meiosis activates transcription factors which trigger a transcriptional cascade that results in sequential co-expression of early, middle and late meiotic genes. However, these factors are not conserved, and the factors and regulatory mechanisms that ensure proper meiotic gene expression in multicellular eukaryotes are poorly understood. Here, we report that DUET/MMD1, a PHD finger protein essential for Arabidopsis male meiosis, functions as a transcriptional regulator in plant meiosis. We find that DUET-PHD binds H3K4me2 in vitro, and show that this interaction is critical for function during meiosis. We also show that DUET is required for proper microtubule organization during meiosis II, independently of its function in meiosis I. Remarkably, DUET protein shows stage-specific expression, confined to diplotene. We identify two genes TDM1 and JAS with critical functions in cell cycle transitions and spindle organization in male meiosis, as DUET targets, with TDM1 being a direct target. Thus, DUET is required to regulate microtubule organization and cell cycle transitions during male meiosis, and functions as a direct transcription activator of the meiotic gene TDM1. Expression profiling showed reduced expression of a subset comprising about 12% of a known set of meiosis preferred genes in the duet mutant. Our results reveal the action of DUET as a transcriptional regulator during male meiosis in plants, and suggest that transcription of meiotic genes is under stagewise control in plants as in yeast.

Age-dependent seizures of absence epilepsy and sleep spindles dynamics in WAG/Rij rats

NASA Astrophysics Data System (ADS)

Grubov, Vadim V.; Sitnikova, Evgenia Y.; Pavlov, Alexey N.; Khramova, Marina V.; Koronovskii, Alexey A.; Hramov, Alexander E.

2015-03-01

In the given paper, a relation between time-frequency characteristics of sleep spindles and the age-dependent epileptic activity in WAG/Rij rats is discussed. Analysis of sleep spindles based on the continuous wavelet transform is performed for rats of different ages. It is shown that the epileptic activity affects the time-frequency intrinsic dynamics of sleep spindles.

The Multidimensional Aspects of Sleep Spindles and Their Relationship to Word-Pair Memory Consolidation

PubMed Central

Lustenberger, Caroline; Wehrle, Flavia; Tüshaus, Laura; Achermann, Peter; Huber, Reto

2015-01-01

Study Objectives: Several studies proposed a link between sleep spindles and sleep dependent memory consolidation in declarative learning tasks. In addition to these state-like aspects of sleep spindles, they have also trait-like characteristics, i.e., were related to general cognitive performance, an important distinction that has often been neglected in correlative studies. Furthermore, from the multitude of different sleep spindle measures, often just one specific aspect was analyzed. Thus, we aimed at taking multidimensional aspects of sleep spindles into account when exploring their relationship to word-pair memory consolidation. Design: Each subject underwent 2 study nights with all-night high-density electroencephalographic (EEG) recordings. Sleep spindles were automatically detected in all EEG channels. Subjects were trained and tested on a word-pair learning task in the evening, and retested in the morning to assess sleep related memory consolidation (overnight retention). Trait-like aspects refer to the mean of both nights and state-like aspects were calculated as the difference between night 1 and night 2. Setting: Sleep laboratory. Participants: Twenty healthy male subjects (age: 23.3 ± 2.1 y) Measurements and Results: Overnight retention was negatively correlated with trait-like aspects of fast sleep spindle density and positively with slow spindle density on a global level. In contrast, state-like aspects were observed for integrated slow spindle activity, which was positively related to the differences in overnight retention in specific regions. Conclusion: Our results demonstrate the importance of a multidimensional approach when investigating the relationship between sleep spindles and memory consolidation and thereby provide a more complete picture explaining divergent findings in the literature. Citation: Lustenberger C, Wehrle F, Tüshaus L, Achermann P, Huber R. The multidimensional aspects of sleep spindles and their relationship to word-pair memory consolidation. SLEEP 2015;38(7):1093–1103. PMID:25845686

Phosphorylation by Cdk1 Increases the Binding of Eg5 to Microtubules In Vitro and in Xenopus Egg Extract Spindles

PubMed Central

Cahu, Julie; Olichon, Aurelien; Hentrich, Christian; Schek, Henry; Drinjakovic, Jovana; Zhang, Cunjie; Doherty-Kirby, Amanda; Lajoie, Gilles; Surrey, Thomas

2008-01-01

Background Motor proteins from the kinesin-5 subfamily play an essential role in spindle assembly during cell division of most organisms. These motors crosslink and slide microtubules in the spindle. Kinesin-5 motors are phosphorylated at a conserved site by Cyclin-dependent kinase 1 (Cdk1) during mitosis. Xenopus laevis kinesin-5 has also been reported to be phosphorylated by Aurora A in vitro. Methodology/Principal Findings We investigate here the effect of these phosphorylations on kinesin-5 from Xenopus laevis, called Eg5. We find that phosphorylation at threonine 937 in the C-terminal tail of Eg5 by Cdk1 does not affect the velocity of Eg5, but strongly increases its binding to microtubules assembled in buffer. Likewise, this phosphorylation promotes binding of Eg5 to microtubules in Xenopus egg extract spindles. This enhancement of binding elevates the amount of Eg5 in spindles above a critical level required for bipolar spindle formation. We find furthermore that phosphorylation of Xenopus laevis Eg5 by Aurora A at serine 543 in the stalk is not required for spindle formation. Conclusions/Significance These results show that phosphorylation of Eg5 by Cdk1 has a direct effect on the interaction of this motor with microtubules. In egg extract, phosphorylation of Eg5 by Cdk1 ensures that the amount of Eg5 in the spindle is above a level that is required for spindle formation. This enhanced targeting to the spindle appears therefore to be, at least in part, a direct consequence of the enhanced binding of Eg5 to microtubules upon phosphorylation by Cdk1. These findings advance our understanding of the regulation of this essential mitotic motor protein. PMID:19079595

Measuring mitotic spindle dynamics in budding yeast

NASA Astrophysics Data System (ADS)

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.

Acute effect of carbamazepine on corticothalamic 5-9-Hz and thalamocortical spindle (10-16-Hz) oscillations in the rat.

PubMed

Zheng, Thomas W; O'Brien, Terence J; Kulikova, Sofya P; Reid, Christopher A; Morris, Margaret J; Pinault, Didier

2014-03-01

A major side effect of carbamazepine (CBZ), a drug used to treat neurological and neuropsychiatric disorders, is drowsiness, a state characterized by increased slow-wave oscillations with the emergence of sleep spindles in the electroencephalogram (EEG). We conducted cortical EEG and thalamic cellular recordings in freely moving or lightly anesthetized rats to explore the impact of CBZ within the intact corticothalamic (CT)-thalamocortical (TC) network, more specifically on CT 5-9-Hz and TC spindle (10-16-Hz) oscillations. Two to three successive 5-9-Hz waves were followed by a spindle in the cortical EEG. A single systemic injection of CBZ (20 mg/kg) induced a significant increase in the power of EEG 5-9-Hz oscillations and spindles. Intracellular recordings of glutamatergic TC neurons revealed 5-9-Hz depolarizing wave-hyperpolarizing wave sequences prolonged by robust, rhythmic spindle-frequency hyperpolarizing waves. This hybrid sequence occurred during a slow hyperpolarizing trough, and was at least 10 times more frequent under the CBZ condition than under the control condition. The hyperpolarizing waves reversed at approximately -70 mV, and became depolarizing when recorded with KCl-filled intracellular micropipettes, indicating that they were GABAA receptor-mediated potentials. In neurons of the GABAergic thalamic reticular nucleus, the principal source of TC GABAergic inputs, CBZ augmented both the number and the duration of sequences of rhythmic spindle-frequency bursts of action potentials. This indicates that these GABAergic neurons are responsible for the generation of at least the spindle-frequency hyperpolarizing waves in TC neurons. In conclusion, CBZ potentiates GABAA receptor-mediated TC spindle oscillations. Furthermore, we propose that CT 5-9-Hz waves can trigger TC spindles. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Cell cycle-dependent regulation of Aurora kinase B mRNA by the Microprocessor complex.

PubMed

Jung, Eunsun; Seong, Youngmo; Seo, Jae Hong; Kwon, Young-Soo; Song, Hoseok

2014-03-28

Aurora kinase B regulates the segregation of chromosomes and the spindle checkpoint during mitosis. In this study, we showed that the Microprocessor complex, which is responsible for the processing of the primary transcripts during the generation of microRNAs, destabilizes the mRNA of Aurora kinase B in human cells. The Microprocessor-mediated cleavage kept Aurora kinase B at a low level and prevented premature entrance into mitosis. The cleavage was reduced during mitosis leading to the accumulation of Aurora kinase B mRNA and protein. In addition to Aurora kinase B mRNA, the processing of other primary transcripts of miRNAs were also decreased during mitosis. We found that the cleavage was dependent on an RNA helicase, DDX5, and the association of DDX5 and DDX17 with the Microprocessor was reduced during mitosis. Thus, we propose a novel mechanism by which the Microprocessor complex regulates stability of Aurora kinase B mRNA and cell cycle progression. Copyright © 2014 Elsevier Inc. All rights reserved.

Cytoskeletal mechanisms in positioning of the second-division spindles and meiotic restitution in tobacco (Nicotiana tabacum L.) microsporogenesis.

PubMed

Sidorchuk, Yuriy Vladimirovich; Deineko, Elena Victorovna

2017-06-01

Microsporogenesis patterns of the polyploid (2n = 4x = 96) and diploid (2n = 2x = 48) Nicotiana tabacum L. (cv. Havana Petit line SR1) plants have been analyzed and compared. Four types of abnormal positions of the second-division spindles-tripolar, parallel, proximal, and fused-have been observed. Of these abnormalities, only tripolar (2.4%) and parallel (1.4%) spindles are observable in diploid plants. As for polyploids, the increased ploidy is accompanied by an increase in the incidence of tripolar (22.8%) and parallel (8.1%) spindle orientations and emergence of two remaining abnormalities (proximal and fused spindles, 3.3%). As has been shown, the spindle position abnormalities in diploid plants have no effect on the meiotic products, whereas both dyads and triads are detectable among the tetrads in polyploid plants. Analysis of cytoskeletal remodeling has allowed for the insight into the role of interzonal radial microtubule system in spindle positioning during the second division. The reason underlying the change in spindle positioning is disturbed polymerization-depolymerization processes and interdigitation of microtubule plus ends within the interzonal cytoskeleton system in late telophase I-interkinesis and prophase II. As has been demonstrated, fused second-division spindles are formed as a result of fused cytoskeletal structures in prophase-prometaphase II in the case when the nuclei are drawn abnormally close to one another. © 2017 International Federation for Cell Biology.

Facile synthesis and luminescent properties of TiO{sub 2}:Eu{sup 3+} nanorods and spindle-shaped nanoparticles from titanate nanotubes precursors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hongbo; Sheng, Ye; Zhao, Huan

2012-12-15

Graphical abstract: This picture illustration for the formation process of TiO{sub 2}:Eu{sup 3+} nanorods and spindle-shaped nanoparticles. Display Omitted Highlights: ► TiO{sub 2}:Eu{sup 3+} nanorods and spindle-shaped nanoparticles were prepared. ► The nanotubes could transform to nanorods and spindle-shaped nanoparticles. ► The luminescence properties are dependent on the increases of the bandgap. -- Abstract: TiO{sub 2}:Eu{sup 3+} nanorods and spindle-shaped nanoparticles have been successfully prepared through simple calcination and hydrothermal process respectively using titanate as the precursors. On the basis of X-ray diffraction results, the as-obtained precursors are titanate (H{sub 2}Ti{sub 2}O{sub 5}·H{sub 2}O), while nanorods and spindle-shaped nanoparticles aremore » pure anatase phase of TiO{sub 2}. TEM and SEM images show that the as-formed precursor could be transformed from nanotubes into nanorods and spindle-shaped nanoparticles by the calcination and hydrothermal process respectively. Under UV light excitation, both the TiO{sub 2}:Eu{sup 3+} nanorods and spindle-shaped nanoparticles exhibit the strong red emission. In addition, the luminescence intensity of TiO{sub 2}:Eu{sup 3+} nanorods is higher than that of TiO{sub 2}:Eu{sup 3+} spindle-shaped nanoparticles due to the increases of the bandgap of the TiO{sub 2} nanorods.« less

REACH. Teacher's Guide Volume II. Check Points.

ERIC Educational Resources Information Center

Georgia Univ., Athens. Div. of Vocational Education.

Designed for use with individualized instructional units (CE 026 345-347, CE 026 349-351) in the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this second volume of the postsecondary teacher guide contains the check points which the instructor may want to refer to when the unit sheet directs the…

A novel GhBEE1-Like gene of cotton causes anther indehiscence in transgenic Arabidopsis under uncontrolled transcription level.

PubMed

Chen, Eryong; Wang, Xiaoqian; Gong, Qian; Butt, Hamama Islam; Chen, Yanli; Zhang, Chaojun; Yang, Zuoren; Wu, Zhixia; Ge, Xiaoyang; Zhang, Xianlong; Li, Fuguang; Zhang, Xueyan

2017-09-05

Male-sterile lines are very important for selective breeding, and anther dehiscence defect is an effective way to generate male-sterile lines. Although several bHLH-family proteins in Arabidopsis have been characterized, little is known about the role of bHLH-family proteins in cotton. Here, we isolated a novel bHLH protein from cotton (Gossypium hirsutum), named GhBEE1-Like. Protein domain analysis showed that GhBEE1-Like contained a basic domain and an HLH domain. Subcellular localization analysis revealed that GhBEE1-Like was a nuclear-localized protein. Expression pattern analysis showed GhBEE1-Like was highly expressed in floral organs, and its expression was induced by the active brassinosteroid (BR) substance 24-epi-BL. GhBEE1-Like overexpression in Arabidopsis resulted in two types of transgenic lines, one with normal anther dehiscence and the other with defective anther dehiscence. Semi-qRT-PCR and qRT-PCR analyses revealed that GhBEE1-Like transcript levels acted as a check-point determining how anther dehiscence proceeds in these transgenic lines; regulated transcript levels result in normal anther dehiscence, whereas uncontrolled transcript levels lead to anther indehiscence. These results suggest that GhBEE1-Like plays an important role via its accumulation in regulating anther dehiscence. Therefore, controlling the level of GhBEE1-Like expression in cotton could be a convenient tool for generating male-sterile lines to use in selective breeding. Copyright © 2017. Published by Elsevier B.V.

On the Dynamics of Rocking Motion of the Hard-Disk Drive Spindle Motor System

NASA Astrophysics Data System (ADS)

Wang, Joseph

Excessive rocking motion of the spindle motor system can cause track misregistration resulting in poor throughput or even drive failure. The chance of excessive disk stack rocking increases as a result of decreasing torsional stiffness of spindle motor bearing system due to the market demand for low profile hard drives. As the track density increases and the vibration specification becomes increasingly stringent, rocking motion of a spindle motor system deserves even more attention and has become a primary challenge for a spindle motor system designer. Lack of understanding of the rocking phenomenon combined with misleading paradox has presented a great difficulty in the effort of avoiding the rocking motion in the hard-disk drive industry. This paper aims to provide fundamental understanding of the rocking phenomenon of a rotating spindle motor system, to clarify the paradox in disk-drive industry and to provide a design guide to an optimized spindle system. This paper, theoretically and experimentally, covers a few important areas of industrial interest including the prediction of rocking natural frequencies and mode shape of a rotating spindle, free vibration, and frequency response under common forcing functions such as rotating and fixed-plane forcing functions. The theory presented here meets with agreeable experimental observation.

Aurora A regulates the activity of HURP by controlling the accessibility of its microtubule-binding domain.

PubMed

Wong, Jim; Lerrigo, Robert; Jang, Chang-Young; Fang, Guowei

2008-05-01

HURP is a spindle-associated protein that mediates Ran-GTP-dependent assembly of the bipolar spindle and promotes chromosome congression and interkinetochore tension during mitosis. We report here a biochemical mechanism of HURP regulation by Aurora A, a key mitotic kinase that controls the assembly and function of the spindle. We found that HURP binds to microtubules through its N-terminal domain that hyperstabilizes spindle microtubules. Ectopic expression of this domain generates defects in spindle morphology and function that reduce the level of tension across sister kinetochores and activate the spindle checkpoint. Interestingly, the microtubule binding activity of this N-terminal domain is regulated by the C-terminal region of HURP: in its hypophosphorylated state, C-terminal HURP associates with the microtubule-binding domain, abrogating its affinity for microtubules. However, when the C-terminal domain is phosphorylated by Aurora A, it no longer binds to N-terminal HURP, thereby releasing the inhibition on its microtubule binding and stabilizing activity. In fact, ectopic expression of this C-terminal domain depletes endogenous HURP from the mitotic spindle in HeLa cells in trans, suggesting the physiological importance for this mode of regulation. We concluded that phosphorylation of HURP by Aurora A provides a regulatory mechanism for the control of spindle assembly and function.

Interdependency of Fission Yeast Alp14/TOG and Coiled Coil Protein Alp7 in Microtubule Localization and Bipolar Spindle FormationD⃞

PubMed Central

Sato, Masamitsu; Vardy, Leah; Angel Garcia, Miguel; Koonrugsa, Nirada; Toda, Takashi

2004-01-01

The Dis1/TOG family plays a pivotal role in microtubule organization. In fission yeast, Alp14 and Dis1 share an essential function in bipolar spindle formation. Here, we characterize Alp7, a novel coiled-coil protein that is required for organization of bipolar spindles. Both Alp7 and Alp14 colocalize to the spindle pole body (SPB) and mitotic spindles. Alp14 localization to these sites is fully dependent upon Alp7. Conversely, in the absence of Alp14, Alp7 localizes to the SPBs, but not mitotic spindles. Alp7 forms a complex with Alp14, where the C-terminal region of Alp14 interacts with the coiled-coil domain of Alp7. Intriguingly, this Alp14 C terminus is necessary and sufficient for mitotic spindle localization. Overproduction of either full-length or coiled-coil region of Alp7 results in abnormal V-shaped spindles and stabilization of interphase microtubules, which is induced independent of Alp14. Alp7 may be a functional homologue of animal TACC. Our results shed light on an interdependent relationship between Alp14/TOG and Alp7. We propose a two-step model that accounts for the recruitment of Alp7 and Alp14 to the SPB and microtubules. PMID:14742702

Interdependency of fission yeast Alp14/TOG and coiled coil protein Alp7 in microtubule localization and bipolar spindle formation.

PubMed

Sato, Masamitsu; Vardy, Leah; Angel Garcia, Miguel; Koonrugsa, Nirada; Toda, Takashi

2004-04-01

The Dis1/TOG family plays a pivotal role in microtubule organization. In fission yeast, Alp14 and Dis1 share an essential function in bipolar spindle formation. Here, we characterize Alp7, a novel coiled-coil protein that is required for organization of bipolar spindles. Both Alp7 and Alp14 colocalize to the spindle pole body (SPB) and mitotic spindles. Alp14 localization to these sites is fully dependent upon Alp7. Conversely, in the absence of Alp14, Alp7 localizes to the SPBs, but not mitotic spindles. Alp7 forms a complex with Alp14, where the C-terminal region of Alp14 interacts with the coiled-coil domain of Alp7. Intriguingly, this Alp14 C terminus is necessary and sufficient for mitotic spindle localization. Overproduction of either full-length or coiled-coil region of Alp7 results in abnormal V-shaped spindles and stabilization of interphase microtubules, which is induced independent of Alp14. Alp7 may be a functional homologue of animal TACC. Our results shed light on an interdependent relationship between Alp14/TOG and Alp7. We propose a two-step model that accounts for the recruitment of Alp7 and Alp14 to the SPB and microtubules.

27 T ultra-high static magnetic field changes orientation and morphology of mitotic spindles in human cells

PubMed Central

Zhang, Lei; Hou, Yubin; Li, Zhiyuan; Ji, Xinmiao; Wang, Ze; Wang, Huizhen; Tian, Xiaofei; Yu, Fazhi; Yang, Zhenye; Pi, Li; Mitchison, Timothy J; Lu, Qingyou; Zhang, Xin

2017-01-01

Purified microtubules have been shown to align along the static magnetic field (SMF) in vitro because of their diamagnetic anisotropy. However, whether mitotic spindle in mammalian cells can be aligned by magnetic field has not been experimentally proved. In particular, the biological effects of SMF of above 20 T (Tesla) on mammalian cells have never been reported. Here we found that in both CNE-2Z and RPE1 human cells spindle orients in 27 T SMF. The direction of spindle alignment depended on the extent to which chromosomes were aligned to form a planar metaphase plate. Our results show that the magnetic torque acts on both microtubules and chromosomes, and the preferred direction of spindle alignment relative to the field depends more on chromosome alignment than microtubules. In addition, spindle morphology was also perturbed by 27 T SMF. This is the first reported study that investigated the mammalian cellular responses to ultra-high magnetic field of above 20 T. Our study not only found that ultra-high magnetic field can change the orientation and morphology of mitotic spindles, but also provided a tool to probe the role of spindle orientation and perturbation in developmental and cancer biology. DOI: http://dx.doi.org/10.7554/eLife.22911.001 PMID:28244368

The Light Intermediate Chain 2 Subpopulation of Dynein Regulates Mitotic Spindle Orientation.

PubMed

Mahale, Sagar; Kumar, Megha; Sharma, Amit; Babu, Aswini; Ranjan, Shashi; Sachidanandan, Chetana; Mylavarapu, Sivaram V S

2016-12-23

Cytoplasmic dynein 1 is a multi-protein intracellular motor essential for mediating several mitotic functions, including the establishment of proper spindle orientation. The functional relevance and mechanistic distinctions between two discrete dynein subpopulations distinguished only by Light Intermediate Chain (LIC) homologues, LIC1 and LIC2 is unknown during mitosis. Here, we identify LIC2-dynein as the major mediator of proper spindle orientation and uncover its underlying molecular mechanism. Cortically localized dynein, essential for maintaining correct spindle orientation, consists majorly of LIC2-dynein, which interacts with cortical 14-3-3 ε- ζ and Par3, conserved proteins required for orienting the spindle. LIC2-dynein is also responsible for the majority of dynein-mediated asymmetric poleward transport of NuMA, helping focus microtubule minus ends. In addition, LIC2-dynein dominates in equatorially aligning chromosomes at metaphase and in regulating mitotic spindle length. Key mitotic functions of LIC2 were remarkably conserved in and essential for early embryonic divisions and development in zebrafish. Thus LIC2-dynein exclusively engages with two major cortical pathways to govern spindle orientation. Overall, we identify a novel selectivity of molecular interactions between the two LICs in mitosis as the underlying basis for their uneven distribution of labour in ensuring proper spindle orientation.

Influence of proprioceptive feedback on the firing rate and recruitment of motoneurons

PubMed Central

De Luca, C J; Kline, J C

2012-01-01

We investigated the relationships of the firing rate and maximal recruitment threshold of motoneurons recorded during isometric contraction with the number of spindles in individual muscles. At force levels above 10% of maximal voluntary contraction, the firing rate was inversely related to the number of spindles in a muscle, with the slope of the relationship increasing with force. The maximal recruitment threshold of motor units increased linearly with the number of spindles in the muscle. Thus, muscles with a greater number of spindles had lower firing rates and a greater maximal recruitment threshold. These findings may be explained by a mechanical interaction between muscle fibres and adjacent spindles. During low-level (0 to 10%) voluntary contractions, muscle fibres of recruited motor units produce force-twitches that activate nearby spindles to respond with an immediate excitatory feedback that reaches maximal level. As the force increases further, the twitches overlap and tend towards tetanization, the muscle fibres shorten, the spindles slacken, their excitatory firings decrease, and the net excitation to the homonymous motoneurons decreases. Motoneurons of muscles with greater number of spindles receive a greater decrease in excitation which reduces their firing rates, increases their maximal recruitment threshold, and changes the motoneuron recruitment distribution. PMID:22183300

Glandular differentiation in dedifferentiated chondrosarcoma: molecular evidence of a rare phenomenon.

PubMed

Jour, George; Liu, Yajuan; Ricciotti, Robert; Pritchard, Colin; Hoch, Benjamin L

2015-09-01

Epithelial glandular differentiation in dedifferentiated chondrosarcoma has not been described. Our patient was a 64-year-old man with a history of prostate cancer status post-radiation and hormonal therapy. On screening bone scan, he was found to have increased uptake in his right femoral shaft. Biopsy revealed intermediate-grade conventional chondrosarcoma. Subsequent femoral resection was remarkable for an intermediate-grade chondrosarcomatous component juxtaposed to an area composed of anastomosing nests and cords of malignant epithelial cells showing nuclear atypia and increased mitotic activity. A fibroblastic-appearing spindle cell population was intimately associated with the epithelial cells. The epithelial cells labeled with 34bE12, AE1/AE3, EMA, and Vimentin (both spindled and epithelial components) while being negative for prostate-specific antigen, prostate specific acid phosphatase, cytokeratin 20, thyroid transcription factor-1, and CDX2. The patient developed local recurrence 9 months after the initial resection but has had no metastatic disease and consistently undetectable prostate-specific antigen levels. Deep parallel sequencing of the dedifferentiated component showed a nonsynonymous mutation at exon 4 of IDH1 gene at codon R132 leading to a substitution of arginine, with serine confirming glandular differentiation in dedifferentiated chondrosarcoma. Copyright © 2015 Elsevier Inc. All rights reserved.

HTLV-I Tax and cell cycle progression.

PubMed

Neuveut, C; Jeang, K T

2000-01-01

Human T-cell leukemia virus type I (HTLV-I) is the etiological agent for adult T-cell leukemia (ATL) and various human myopathies/neuropathies. HTLV-I encodes a 40 kDa phosphoprotein, Tax, which has been implicated in cellular transformation. In similarity with several other oncoproteins such as Myc, Jun, and Fos, Tax is a transcriptional activator. How Tax mechanistically dysregulates the cell cycle remains unclear. Recent findings from us and others have shown that Tax targets key regulators of G1/S and M progression such as p16INK4a, cyclin D1, cyclin D3-cdk, and the mitotic spindle checkpoint apparatus. Thus, Tax influences the progression of cells in various phases of the cell cycle. In this regard, we will discuss three distinct mechanisms through which Tax affects cell-cycling: a) through direct association Tax can abrogate the inhibitory function of p16INK4a on the G1-cdks, b) Tax can also directly influence cyclin D-cdk activities by a protein-protein interaction, and c) Tax targets the HsMAD1 mitotic spindle-assembly checkpoint protein. Through these varied routes, the HTLV-I oncoprotein dysregulates cellular growth controls and engenders a proclivity of cells toward a loss of DNA-damage surveillance.

Measuring and modeling polymer concentration profiles near spindle boundaries argues that spindle microtubules regulate their own nucleation

NASA Astrophysics Data System (ADS)

Kaye, Bryan; Stiehl, Olivia; Foster, Peter J.; Shelley, Michael J.; Needleman, Daniel J.; Fürthauer, Sebastian

2018-05-01

Spindles are self-organized microtubule-based structures that segregate chromosomes during cell division. The mass of the spindle is controlled by the balance between microtubule turnover and nucleation. The mechanisms that control the spatial regulation of microtubule nucleation remain poorly understood. While previous work found that microtubule nucleators bind to pre-existing microtubules in the spindle, it is still unclear whether this binding regulates the activity of those nucleators. Here we use a combination of experiments and mathematical modeling to investigate this issue. We measured the concentration of microtubules and soluble tubulin in and around the spindle. We found a very sharp decay in the concentration of microtubules at the spindle interface. This is inconsistent with a model in which the activity of nucleators is independent of their association with microtubules but consistent with a model in which microtubule nucleators are only active when bound to pre-existing microtubules. This argues that the activity of microtubule nucleators is greatly enhanced when bound to pre-existing microtubules. Thus, microtubule nucleators are both localized and activated by the microtubules they generate.

Kinesin-8 effects on mitotic microtubule dynamics contribute to spindle function in fission yeast

PubMed Central

Gergely, Zachary R.; Crapo, Ammon; Hough, Loren E.; McIntosh, J. Richard; Betterton, Meredith D.

2016-01-01

Kinesin-8 motor proteins destabilize microtubules. Their absence during cell division is associated with disorganized mitotic chromosome movements and chromosome loss. Despite recent work studying effects of kinesin-8s on microtubule dynamics, it remains unclear whether the kinesin-8 mitotic phenotypes are consequences of their effect on microtubule dynamics, their well-established motor activity, or additional, unknown functions. To better understand the role of kinesin-8 proteins in mitosis, we studied the effects of deletion of the fission yeast kinesin-8 proteins Klp5 and Klp6 on chromosome movements and spindle length dynamics. Aberrant microtubule-driven kinetochore pushing movements and tripolar mitotic spindles occurred in cells lacking Klp5 but not Klp6. Kinesin-8–deletion strains showed large fluctuations in metaphase spindle length, suggesting a disruption of spindle length stabilization. Comparison of our results from light microscopy with a mathematical model suggests that kinesin-8–induced effects on microtubule dynamics, kinetochore attachment stability, and sliding force in the spindle can explain the aberrant chromosome movements and spindle length fluctuations seen. PMID:27146110

Measurement of Spindle Rigidity by using a Magnet Loader

NASA Astrophysics Data System (ADS)

Yamazaki, Taku; Matsubara, Atsushi; Fujita, Tomoya; Muraki, Toshiyuki; Asano, Kohei; Kawashima, Kazuyuki

The static rigidity of a rotating spindle in the radial direction is investigated in this research. A magnetic loading device (magnet loader) has been developed for the measurement. The magnet loader, which has coils and iron cores, generates the electromagnetic force and attracts a dummy tool attached to the spindle. However, the eddy current is generated in the dummy tool with the spindle rotation and reduces the attractive force at high spindle speed. In order to understand the magnetic flux and eddy current in the dummy tool, the electromagnetic field analysis by FEM was carried out. Grooves on the attraction surface of the dummy tool were designed to cut the eddy current flow. The dimension of the groove were decided based on the FEM analysis, and the designed tool were manufactured and tested. The test result shows that the designed tool successfully reduces the eddy current and recovers the attractive force. By using the magnet loader and the grooved tool, the spindle rigidity can be measured when the spindle rotates with a speed up to 10,000 min-1.

Sleep spindle activity and cognitive performance in healthy children.

PubMed

Chatburn, Alex; Coussens, Scott; Lushington, Kurt; Kennedy, Declan; Baumert, Mathias; Kohler, Mark

2013-02-01

To investigate the association between indices of sleep spindle activity and cognitive performance in a sample of healthy children. Correlational. Intelligence (Stanford-Binet) and neurocognitive functioning (NEPSY) were assessed, with sleep variables being measured during overnight polysomnography. Hospital sleep laboratory. Twenty-seven healthy children (mean age 8.19 y; 14 female, 13 male). N/A. Participants underwent a single night of overnight polysomnography after completing measures of intelligence and neurocognitive functioning. Sleep spindles were visually identified by an experienced sleep scoring technician and separated algorithmically into fast (> 13 Hz) and slow spindle (< 13 Hz) categories. The number of fast spindles was significantly correlated with narrative memory (r(s) = 0.38) and sensorimotor functioning (-0.43). Mean central frequency of spindles was also significantly correlated with sensorimotor functioning (-0.41), planning ability (-0.41), and working memory (-0.54). Basal sleep spindle activity is associated with different aspects of cognitive performance in children. To the extent that these associations in a pediatric population are different from what is known in adult sleep may play an important role in development.

Effect of spinal manipulation on the development of history-dependent responsiveness of lumbar paraspinal muscle spindles in the cat

PubMed Central

Cao, Dong-Yuan; Pickar, Joel G.

2014-01-01

We determined whether spinal manipulation could prevent and/or reverse the decrease and increase in paraspinal muscle spindle responsiveness caused respectively by lengthening and shortening histories of the lumbar muscles. Single unit spindle activity from multifidus and longissimus muscles was recorded in the L6 dorsal root in anesthetized cats. Muscle history was created and spinal manipulation delivered (thrust amplitude: 1.0mm, duration: 100ms) using a feedback-controlled motor attached to the L6 spinous process. Muscle spindle discharge to a fixed vertebral position (static test) and to vertebral movement (dynamic test) was evaluated following the lengthening and shortening histories. For the static test, changes in muscle spindle responsiveness were significantly less when spinal manipulation followed muscle history (p<0.01), but not when spinal manipulation preceded it (p>0.05). For the dynamic test, spinal manipulation did not significantly affect the history-induced change in muscle spindle responsiveness. Spinal manipulation may partially reverse the effects of muscle history on muscle spindle signaling of vertebral position. PMID:24932019

Dynein-mediated pulling forces drive rapid mitotic spindle elongation in Ustilago maydis

PubMed Central

Fink, Gero; Schuchardt, Isabel; Colombelli, Julien; Stelzer, Ernst; Steinberg, Gero

2006-01-01

Spindle elongation segregates chromosomes and occurs in anaphase, an essential step in mitosis. Dynein-mediated pulling forces position the spindle, but their role in anaphase is a matter of debate. Here, we demonstrate that dynein is responsible for rapid spindle elongation in the model fungus Ustilago maydis. We show that initial slow elongation is supported by kinesin-5, which is located in the spindle mid-zone. When the spindle reaches ∼2 μm in length, the elongation rate increases four-fold. This coincides with the appearance of long and less-dynamic microtubules (MTs) at each pole that accumulate dynein at their tips. Laser-mediated nanosurgery revealed that these MTs exert pulling forces in control cells, but not in dynein mutants. In addition, dynein mutants undergo initial slow anaphase, but fail to establish less-dynamic MTs and do not perform rapid spindle elongation, suggesting that dynein drives anaphase B. This is most likely mediated by cortical sliding of astral MTs along stationary dynein, which is off-loaded from the MT plus-end to the cortex. PMID:17024185

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

PubMed Central

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

2015-01-01

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. DOI: http://dx.doi.org/10.7554/eLife.09384.001 PMID:26406118

RNA-Seq Profiling Reveals Novel Hepatic Gene Expression Pattern in Aflatoxin B1 Treated Rats

PubMed Central

Merrick, B. Alex; Phadke, Dhiral P.; Auerbach, Scott S.; Mav, Deepak; Stiegelmeyer, Suzy M.; Shah, Ruchir R.; Tice, Raymond R.

2013-01-01

Deep sequencing was used to investigate the subchronic effects of 1 ppm aflatoxin B1 (AFB1), a potent hepatocarcinogen, on the male rat liver transcriptome prior to onset of histopathological lesions or tumors. We hypothesized RNA-Seq would reveal more differentially expressed genes (DEG) than microarray analysis, including low copy and novel transcripts related to AFB1’s carcinogenic activity compared to feed controls (CTRL). Paired-end reads were mapped to the rat genome (Rn4) with TopHat and further analyzed by DESeq and Cufflinks-Cuffdiff pipelines to identify differentially expressed transcripts, new exons and unannotated transcripts. PCA and cluster analysis of DEGs showed clear separation between AFB1 and CTRL treatments and concordance among group replicates. qPCR of eight high and medium DEGs and three low DEGs showed good comparability among RNA-Seq and microarray transcripts. DESeq analysis identified 1,026 differentially expressed transcripts at greater than two-fold change (p<0.005) compared to 626 transcripts by microarray due to base pair resolution of transcripts by RNA-Seq, probe placement within transcripts or an absence of probes to detect novel transcripts, splice variants and exons. Pathway analysis among DEGs revealed signaling of Ahr, Nrf2, GSH, xenobiotic, cell cycle, extracellular matrix, and cell differentiation networks consistent with pathways leading to AFB1 carcinogenesis, including almost 200 upregulated transcripts controlled by E2f1-related pathways related to kinetochore structure, mitotic spindle assembly and tissue remodeling. We report 49 novel, differentially-expressed transcripts including confirmation by PCR-cloning of two unique, unannotated, hepatic AFB1-responsive transcripts (HAfT’s) on chromosomes 1.q55 and 15.q11, overexpressed by 10 to 25-fold. Several potentially novel exons were found and exon refinements were made including AFB1 exon-specific induction of homologous family members, Ugt1a6 and Ugt1a7c. We find the rat transcriptome contains many previously unidentified, AFB1-responsive exons and transcripts supporting RNA-Seq’s capabilities to provide new insights into AFB1-mediated gene expression leading to hepatocellular carcinoma. PMID:23630614

RNA-Seq profiling reveals novel hepatic gene expression pattern in aflatoxin B1 treated rats.

PubMed

Merrick, B Alex; Phadke, Dhiral P; Auerbach, Scott S; Mav, Deepak; Stiegelmeyer, Suzy M; Shah, Ruchir R; Tice, Raymond R

2013-01-01

Deep sequencing was used to investigate the subchronic effects of 1 ppm aflatoxin B1 (AFB1), a potent hepatocarcinogen, on the male rat liver transcriptome prior to onset of histopathological lesions or tumors. We hypothesized RNA-Seq would reveal more differentially expressed genes (DEG) than microarray analysis, including low copy and novel transcripts related to AFB1's carcinogenic activity compared to feed controls (CTRL). Paired-end reads were mapped to the rat genome (Rn4) with TopHat and further analyzed by DESeq and Cufflinks-Cuffdiff pipelines to identify differentially expressed transcripts, new exons and unannotated transcripts. PCA and cluster analysis of DEGs showed clear separation between AFB1 and CTRL treatments and concordance among group replicates. qPCR of eight high and medium DEGs and three low DEGs showed good comparability among RNA-Seq and microarray transcripts. DESeq analysis identified 1,026 differentially expressed transcripts at greater than two-fold change (p<0.005) compared to 626 transcripts by microarray due to base pair resolution of transcripts by RNA-Seq, probe placement within transcripts or an absence of probes to detect novel transcripts, splice variants and exons. Pathway analysis among DEGs revealed signaling of Ahr, Nrf2, GSH, xenobiotic, cell cycle, extracellular matrix, and cell differentiation networks consistent with pathways leading to AFB1 carcinogenesis, including almost 200 upregulated transcripts controlled by E2f1-related pathways related to kinetochore structure, mitotic spindle assembly and tissue remodeling. We report 49 novel, differentially-expressed transcripts including confirmation by PCR-cloning of two unique, unannotated, hepatic AFB1-responsive transcripts (HAfT's) on chromosomes 1.q55 and 15.q11, overexpressed by 10 to 25-fold. Several potentially novel exons were found and exon refinements were made including AFB1 exon-specific induction of homologous family members, Ugt1a6 and Ugt1a7c. We find the rat transcriptome contains many previously unidentified, AFB1-responsive exons and transcripts supporting RNA-Seq's capabilities to provide new insights into AFB1-mediated gene expression leading to hepatocellular carcinoma.

Drosophila parthenogenesis: A tool to decipher centrosomal vs acentrosomal spindle assembly pathways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riparbelli, Maria Giovanna; Callaini, Giuliano

2008-04-15

Development of unfertilized eggs in the parthenogenetic strain K23-O-im of Drosophila mercatorum requires the stochastic interactions of self-assembled centrosomes with the female chromatin. In a portion of the unfertilized eggs that do not assemble centrosomes, microtubules organize a bipolar anastral mitotic spindle around the chromatin like the one formed during the first female meiosis, suggesting that similar pathways may be operative. In the cytoplasm of eggs in which centrosomes do form, monastral and biastral spindles are found. Analysis by laser scanning confocal microscopy suggests that these spindles are derived from the stochastic interaction of astral microtubules directly with kinetochore regionsmore » or indirectly with kinetochore microtubules. Our findings are consistent with the idea that mitotic spindle assembly requires both acentrosomal and centrosomal pathways, strengthening the hypothesis that astral microtubules can dictate the organization of the spindle by capturing kinetochore microtubules.« less

Microtubule-dependent regulation of mitotic protein degradation

PubMed Central

Song, Ling; Craney, Allison; Rape, Michael

2014-01-01

Accurate cell division depends on tightly regulated ubiquitylation events catalyzed by the anaphase-promoting complex. Among its many substrates, the APC/C triggers the degradation of proteins that stabilize the mitotic spindle, and loss or accumulation of such spindle assembly factors can result in aneuploidy and cancer. Although critical for cell division, it has remained poorly understood how the timing of spindle assembly factor degradation is established during mitosis. Here, we report that active spindle assembly factors are protected from APC/C-dependent degradation by microtubules. In contrast, those molecules that are not bound to microtubules are highly susceptible to proteolysis and turned over immediately after APC/C-activation. The correct timing of spindle assembly factor degradation, as achieved by this regulatory circuit, is required for accurate spindle structure and function. We propose that the localized stabilization of APC/C-substrates provides a mechanism for the selective disposal of cell cycle regulators that have fulfilled their mitotic roles. PMID:24462202

Autocatalytic microtubule nucleation determines the size and mass of Xenopus laevis egg extract spindles

PubMed Central

Decker, Franziska; Oriola, David; Dalton, Benjamin

2018-01-01

Regulation of size and growth is a fundamental problem in biology. A prominent example is the formation of the mitotic spindle, where protein concentration gradients around chromosomes are thought to regulate spindle growth by controlling microtubule nucleation. Previous evidence suggests that microtubules nucleate throughout the spindle structure. However, the mechanisms underlying microtubule nucleation and its spatial regulation are still unclear. Here, we developed an assay based on laser ablation to directly probe microtubule nucleation events in Xenopus laevis egg extracts. Combining this method with theory and quantitative microscopy, we show that the size of a spindle is controlled by autocatalytic growth of microtubules, driven by microtubule-stimulated microtubule nucleation. The autocatalytic activity of this nucleation system is spatially regulated by the limiting amounts of active microtubule nucleators, which decrease with distance from the chromosomes. This mechanism provides an upper limit to spindle size even when resources are not limiting. PMID:29323637

Chromosome and mitotic spindle dynamics in fission yeast kinesin-8 mutants

NASA Astrophysics Data System (ADS)

Crapo, Ammon M.; Gergley, Zachary R.; McIntosh, J. Richard; Betterton, M. D.

2014-03-01

Fission yeast proteins Klp5p and Klp6p are plus-end directed motors of the kinesin-8 family which promote microtubule (MT) depolymerization and also affect chromosome segregation, but the mechanism of these activities is not well understood. Using live-cell time-lapse fluorescence microscopy of fission yeast wild-type (WT) and klp5/6 mutant strains, we quantify and compare the dynamics of kinetochore motion and mitotic spindle length in 3D. In WT cells, the spindle, once formed, remains a consistent size and chromosomes are correctly organized and segregated. In kinesin-8 mutants, spindles undergo large length fluctuations of several microns. Kinetochore motions are also highly fluctuating, with kinetochores frequently moving away from the spindle rather than toward it. We observe transient pushing of chromosomes away from the spindle by as much as 10 microns in distance.

A tip/tilt mirror with large dynamic range for the ESO VLT Four Laser Guide Star Facility

NASA Astrophysics Data System (ADS)

Rijnveld, N.; Henselmans, R.; Nijland, B.

2011-09-01

One of the critical elements in the Four Laser Guide Star Facility (4LGSF) for the ESO Very Large Telescope (VLT) is the Optical Tube Assembly (OTA), consisting of a stable 20x laser beam expander and an active tip/tilt mirror, the Field Selector Mechanism (FSM). This paper describes the design and performance testing of the FSM. The driving requirement for the FSM is its large stroke of +/-6.1 mrad, in combination with less than 1.5 μrad RMS absolute accuracy. The FSM design consists of a Zerodur mirror, bonded to a membrane spring and strut combination to allow only tip and tilt. Two spindle drives actuate the mirror, using a stiffness based transmission to increase resolution. Absolute accuracy is achieved with two differential inductive sensor pairs. A prototype of the FSM is realized to optimize the control configuration and measure its performance. Friction in the spindle drive is overcome by creating a local velocity control loop between the spindle drives and the shaft encoders. Accuracy is achieved by using a cascaded low bandwidth control loop with feedback from the inductive sensors. The pointing jitter and settling time of the FSM are measured with an autocollimator. The system performance meets the strict requirements, and is ready to be implemented in the first OTA.

Remote drill bit loader

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dokos, J.A.

1996-12-31

A drill bit loader is described for loading a tapered shank of a drill bit into a similarly tapered recess in the end of a drill spindle. The spindle has a transverse slot at the inner end of the recess. The end of the tapered shank of the drill bit has a transverse tang adapted to engage in the slot so that the drill bit will be rotated by the spindle. The loader is in the form of a cylinder adapted to receive the drill bit with the shank projecting out of the outer end of the cylinder. Retainer pinsmore » prevent rotation of the drill bit in the cylinder. The spindle is lowered to extend the shank of the drill bit into the recess in the spindle and the spindle is rotated to align the slot in the spindle with the tang on the shank. A spring unit in the cylinder is compressed by the drill bit during its entry into the recess of the spindle and resiliently drives the tang into the slot in the spindle when the tang and slot are aligned. In typical remote drilling operations, whether in hot cells or water pits, drill bits have been held using a collet or end mill type holder with set screws. In either case, to load or change a drill bit required the use master-slave manipulators to position the bits and tighten the collet or set screws. This requirement eliminated many otherwise useful work areas because they were not equipped with slaves, particularly in water pits.« less

Warts phosphorylates Mud to promote Pins-mediated mitotic spindle orientation in Drosophila independent of Yorkie

PubMed Central

Dewey, Evan B.; Sanchez, Desiree; Johnston, Christopher A.

2015-01-01

SUMMARY Multicellular animals have evolved conserved signaling pathways that translate cell polarity cues into mitotic spindle positioning to control the orientation of cell division within complex tissue structures. These oriented cell divisions are essential for the development of cell diversity and the maintenance of tissue homeostasis. Despite intense efforts, the molecular mechanisms that control spindle orientation remain incompletely defined. Here we describe a role for the Hippo (Hpo) kinase complex in promoting Partner of Inscuteable (Pins)-mediated spindle orientation. Knockdown of Hpo, Salvador (Sav), or Warts (Wts) each result in a partial loss of spindle orientation, a phenotype previously described following loss of the Pins-binding protein Mushroom body defect (Mud). Similar to orthologs spanning yeast to mammals, Wts kinase localizes to mitotic spindle poles, a prominent site of Mud localization. Wts directly phosphorylates Mud in vitro within its C-terminal coiled-coil domain. This Mud coiled-coil domain directly binds the adjacent Pins-binding domain to dampen the Pins/Mud interaction, and Wts-mediated phosphorylation uncouples this intramolecular Mud interaction. Loss of Wts prevents cortical Pins/Mud association without affecting Mud accumulation at spindle poles, suggesting phosphorylation acts as a molecular switch to specifically activate cortical Mud function. Finally, loss of Wts in Drosophila imaginal disc epithelial cells results in diminished cortical Mud and defective planar spindle orientation. Our results provide new insights into the molecular basis for dynamic regulation of the cortical Pins/Mud spindle positioning complex and highlight a novel link with an essential, evolutionarily-conserved cell proliferation pathway. PMID:26592339

Slow sleep spindle and procedural memory consolidation in patients with major depressive disorder.

PubMed

Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

2016-01-01

Evidence has accumulated, which indicates that, in healthy individuals, sleep enhances procedural memory consolidation, and that sleep spindle activity modulates this process. However, whether sleep-dependent procedural memory consolidation occurs in patients medicated for major depressive disorder remains unclear, as are the pharmacological and physiological mechanisms that underlie this process. Healthy control participants (n=17) and patients medicated for major depressive disorder (n=11) were recruited and subjected to a finger-tapping motor sequence test (MST; nondominant hand) paradigm to compare the averaged scores of different learning phases (presleep, postsleep, and overnight improvement). Participants' brain activity was recorded during sleep with 16 electroencephalography channels (between MSTs). Sleep scoring and frequency analyses were performed on the electroencephalography data. Additionally, we evaluated sleep spindle activity, which divided the spindles into fast-frequency spindle activity (12.5-16 Hz) and slow-frequency spindle activity (10.5-12.5 Hz). Sleep-dependent motor memory consolidation in patients with depression was impaired in comparison with that in control participants. In patients with depression, age correlated negatively with overnight improvement. The duration of slow-wave sleep correlated with the magnitude of motor memory consolidation in patients with depression, but not in healthy controls. Slow-frequency spindle activity was associated with reduction in the magnitude of motor memory consolidation in both groups. Because the changes in slow-frequency spindle activity affected the thalamocortical network dysfunction in patients medicated for depression, dysregulated spindle generation may impair sleep-dependent memory consolidation. Our findings may help to elucidate the cognitive deficits that occur in patients with major depression both in the waking state and during sleep.

Sleep Spindles in the Right Hemisphere Support Awareness of Regularities and Reflect Pre-Sleep Activations.

PubMed

Yordanova, Juliana; Kolev, Vasil; Bruns, Eike; Kirov, Roumen; Verleger, Rolf

2017-11-01

The present study explored the sleep mechanisms which may support awareness of hidden regularities. Before sleep, 53 participants learned implicitly a lateralized variant of the serial response-time task in order to localize sensorimotor encoding either in the left or right hemisphere and induce implicit regularity representations. Electroencephalographic (EEG) activity was recorded at multiple electrodes during both task performance and sleep, searching for lateralized traces of the preceding activity during learning. Sleep EEG analysis focused on region-specific slow (9-12 Hz) and fast (13-16 Hz) sleep spindles during nonrapid eye movement sleep. Fast spindle activity at those motor regions that were activated during learning increased with the amount of postsleep awareness. Independently of side of learning, spindle activity at right frontal and fronto-central regions was involved: there, fast spindles increased with the transformation of sequence knowledge from implicit before sleep to explicit after sleep, and slow spindles correlated with individual abilities of gaining awareness. These local modulations of sleep spindles corresponded to regions with greater presleep activation in participants with postsleep explicit knowledge. Sleep spindle mechanisms are related to explicit awareness (1) by tracing the activation of motor cortical and right-hemisphere regions which had stronger involvement already during learning and (2) by recruitment of individually consolidated processing modules in the right hemisphere. The integration of different sleep spindle mechanisms with functional states during wake collectively supports the gain of awareness of previously experienced regularities, with a special role for the right hemisphere. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

Warts phosphorylates mud to promote pins-mediated mitotic spindle orientation in Drosophila, independent of Yorkie.

PubMed

Dewey, Evan B; Sanchez, Desiree; Johnston, Christopher A

2015-11-02

Multicellular animals have evolved conserved signaling pathways that translate cell polarity cues into mitotic spindle positioning to control the orientation of cell division within complex tissue structures. These oriented cell divisions are essential for the development of cell diversity and the maintenance of tissue homeostasis. Despite intense efforts, the molecular mechanisms that control spindle orientation remain incompletely defined. Here, we describe a role for the Hippo (Hpo) kinase complex in promoting Partner of Inscuteable (Pins)-mediated spindle orientation. Knockdown of Hpo, Salvador (Sav), or Warts (Wts) each result in a partial loss of spindle orientation, a phenotype previously described following loss of the Pins-binding protein Mushroom body defect (Mud). Similar to orthologs spanning yeast to mammals, Wts kinase localizes to mitotic spindle poles, a prominent site of Mud localization. Wts directly phosphorylates Mud in vitro within its C-terminal coiled-coil domain. This Mud coiled-coil domain directly binds the adjacent Pins-binding domain to dampen the Pins/Mud interaction, and Wts-mediated phosphorylation uncouples this intramolecular Mud interaction. Loss of Wts prevents cortical Pins/Mud association without affecting Mud accumulation at spindle poles, suggesting phosphorylation acts as a molecular switch to specifically activate cortical Mud function. Finally, loss of Wts in Drosophila imaginal disc epithelial cells results in diminished cortical Mud and defective planar spindle orientation. Our results provide new insights into the molecular basis for dynamic regulation of the cortical Pins/Mud spindle positioning complex and highlight a novel link with an essential, evolutionarily conserved cell proliferation pathway. Copyright © 2015 Elsevier Ltd. All rights reserved.

Welcoming the new WHO classification of pituitary tumors 2017: revolution in TTF-1-positive posterior pituitary tumors.

PubMed

Shibuya, Makoto

2018-04-01

The fourth edition of the World Health Organization classification of endocrine tumors (EN-WHO2017) was released in 2017. In this new edition, changes in the classification of non-neuroendocrine tumors are proposed particularly in tumors arising in the posterior pituitary. These tumors are a distinct group of low-grade neoplasms of the sellar region that express thyroid transcription factor-1, and include pituicytoma, granular cell tumor of the sellar region, spindle cell oncocytoma, and sellar ependymoma. This short review focuses on the classification of posterior pituitary tumors newly proposed in EN-WHO2017, and controversies in their pathological differential diagnosis are discussed based on recent cases.

Archaeal viruses--novel, diverse and enigmatic.

PubMed

Peng, Xu; Garrett, Roger A; She, QunXin

2012-05-01

Recent research has revealed a remarkable diversity of viruses in archaeal-rich environments where spindles, spheres, filaments and rods are common, together with other exceptional morphotypes never recorded previously. Moreover, their double-stranded DNA genomes carry very few genes exhibiting homology to those of bacterial and eukaryal viruses. Studies on viral life cycles are still at a preliminary stage but important insights are being gained especially from microarray analyses of viral transcripts for a few model virus-host systems. Recently, evidence has been presented for some exceptional archaeal-specific mechanisms for extra-cellular morphological development of virions and for their cellular extrusion. Here we summarise some of the recent developments in this rapidly developing and exciting research area.

Desmoplastic small round cell tumor of the lung.

PubMed

Muramatsu, Takashi; Shimamura, Mie; Furuichi, Motohiko; Nishii, Tatsuhiko; Takeshita, Shinji; Shiono, Motomi

2010-12-01

We report a rare case of desmoplastic small round cell tumor, which arose from the left lung. A 25-year-old man was found to have an abnormal shadow during a routine physical examination and was admitted to our hospital. A thoracoscopic tumor biopsy was performed under general anesthesia. According to the histopathologic findings of permanent sections, the tumor was composed of sharply outlined nests, clusters, and trabeculae of small round to oval cells separated by a spindle-shaped desmoplastic stroma. A gene analysis revealed chimera genes of Ewing's sarcoma and Wilms' tumor by reverse transcription polymerase chain reaction. Copyright © 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Very High Load Capacity Air Bearing Spindle for Large Diamond Turning Machines

DTIC Science & Technology

2010-06-08

testing and a surplus air bearing rotary table has been located. A prototype spindle has been designed to work with the table. 15. SUBJECT TERMS...MSFC) • PROTOTYPE SPINDLE DESIGN June 8, 2010Mirror Technology Workshop 3 Introduction • DT is a proven method of manufacturing aspheric off-axis... designed to hold in a strain-free condition. This spindle development is aimed at producing 3 meter diameter components. This requirement results in the

Muscle spindles exhibit core lesions and extensive degeneration of intrafusal fibers in the Ryr1{sup I4895T/wt} mouse model of core myopathy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zvaritch, Elena; MacLennan, David H., E-mail: david.maclennan@utoronto.ca

Muscle spindles from the hind limb muscles of adult Ryr1{sup I4895T/wt} (IT/+) mice exhibit severe structural abnormalities. Up to 85% of the spindles are separated from skeletal muscle fascicles by a thick layer of connective tissue. Many intrafusal fibers exhibit degeneration, with Z-line streaming, compaction and collapse of myofibrillar bundles, mitochondrial clumping, nuclear shrinkage and pyknosis. The lesions resemble cores observed in the extrafusal myofibers of this animal model and of core myopathy patients. Spindle abnormalities precede those in extrafusal fibers, indicating that they are a primary pathological feature in this murine Ryr1-related core myopathy. Muscle spindle involvement, if confirmedmore » for human core myopathy patients, would provide an explanation for an array of devastating clinical features characteristic of these diseases and provide novel insights into the pathology of RYR1-related myopathies. - Highlights: • Muscle spindles exhibit structural abnormalities in a mouse model of core myopathy. • Myofibrillar collapse and mitochondrial clumping is observed in intrafusal fibers. • Myofibrillar degeneration follows a pattern similar to core formation in extrafusal myofibers. • Muscle spindle abnormalities are a part of the pathological phenotype in the mouse model of core myopathy. • Direct involvement of muscle spindles in the pathology of human RYR1-related myopathies is proposed.« less

Kinesin-5–dependent Poleward Flux and Spindle Length Control in Drosophila Embryo Mitosis

PubMed Central

Brust-Mascher, Ingrid; Sommi, Patrizia; Cheerambathur, Dhanya K.

2009-01-01

We used antibody microinjection and genetic manipulations to dissect the various roles of the homotetrameric kinesin-5, KLP61F, in astral, centrosome-controlled Drosophila embryo spindles and to test the hypothesis that it slides apart interpolar (ip) microtubules (MT), thereby controlling poleward flux and spindle length. In wild-type and Ncd null mutant embryos, anti-KLP61F dissociated the motor from spindles, producing a spatial gradient in the KLP61F content of different spindles, which was visible in KLP61F-GFP transgenic embryos. The resulting mitotic defects, supported by gene dosage experiments and time-lapse microscopy of living klp61f mutants, reveal that, after NEB, KLP61F drives persistent MT bundling and the outward sliding of antiparallel MTs, thereby contributing to several processes that all appear insensitive to cortical disruption. KLP61F activity contributes to the poleward flux of both ipMTs and kinetochore MTs and to the length of the metaphase spindle. KLP61F activity maintains the prometaphase spindle by antagonizing Ncd and another unknown force-generator and drives anaphase B, although the rate of spindle elongation is relatively insensitive to the motor's concentration. Finally, KLP61F activity contributes to normal chromosome congression, kinetochore spacing, and anaphase A rates. Thus, a KLP61F-driven sliding filament mechanism contributes to multiple aspects of mitosis in this system. PMID:19158379

White Matter Structure in Older Adults Moderates the Benefit of Sleep Spindles on Motor Memory Consolidation.

PubMed

Mander, Bryce A; Zhu, Alyssa H; Lindquist, John R; Villeneuve, Sylvia; Rao, Vikram; Lu, Brandon; Saletin, Jared M; Ancoli-Israel, Sonia; Jagust, William J; Walker, Matthew P

2017-11-29

Sleep spindles promote the consolidation of motor skill memory in young adults. Older adults, however, exhibit impoverished sleep-dependent motor memory consolidation. The underlying pathophysiological mechanism(s) explaining why motor memory consolidation in older adults fails to benefit from sleep remains unclear. Here, we demonstrate that male and female older adults show impoverished overnight motor skill memory consolidation relative to young adults, with the extent of impairment being associated with the degree of reduced frontal fast sleep spindle density. The magnitude of the loss of frontal fast sleep spindles in older adults was predicted by the degree of reduced white matter integrity throughout multiple white matter tracts known to connect subcortical and cortical brain regions. We further demonstrate that the structural integrity of selective white matter fiber tracts, specifically within right posterior corona radiata, right tapetum, and bilateral corpus callosum, statistically moderates whether sleep spindles promoted overnight consolidation of motor skill memory. Therefore, white matter integrity within tracts known to connect cortical sensorimotor control regions dictates the functional influence of sleep spindles on motor skill memory consolidation in the elderly. The deterioration of white matter fiber tracts associated with human brain aging thus appears to be one pathophysiological mechanism influencing subcortical-cortical propagation of sleep spindles and their related memory benefits. SIGNIFICANCE STATEMENT Numerous studies have shown that sleep spindle expression is reduced and sleep-dependent motor memory is impaired in older adults. However, the mechanisms underlying these alterations have remained unknown. The present study reveals that age-related degeneration of white matter within select fiber tracts is associated with reduced sleep spindles in older adults. We further demonstrate that, within these same fiber tracts, the degree of degeneration determines whether sleep spindles can promote motor memory consolidation. Therefore, white matter integrity in the human brain, more than age per se, determines the magnitude of decline in sleep spindles in later life and, with it, the success (or lack thereof) of sleep-dependent motor memory consolidation in older adults. Copyright © 2017 the authors 0270-6474/17/3711675-13$15.00/0.

White Matter Structure in Older Adults Moderates the Benefit of Sleep Spindles on Motor Memory Consolidation

PubMed Central

Zhu, Alyssa H.; Lindquist, John R.; Villeneuve, Sylvia; Rao, Vikram; Lu, Brandon; Ancoli-Israel, Sonia

2017-01-01

Sleep spindles promote the consolidation of motor skill memory in young adults. Older adults, however, exhibit impoverished sleep-dependent motor memory consolidation. The underlying pathophysiological mechanism(s) explaining why motor memory consolidation in older adults fails to benefit from sleep remains unclear. Here, we demonstrate that male and female older adults show impoverished overnight motor skill memory consolidation relative to young adults, with the extent of impairment being associated with the degree of reduced frontal fast sleep spindle density. The magnitude of the loss of frontal fast sleep spindles in older adults was predicted by the degree of reduced white matter integrity throughout multiple white matter tracts known to connect subcortical and cortical brain regions. We further demonstrate that the structural integrity of selective white matter fiber tracts, specifically within right posterior corona radiata, right tapetum, and bilateral corpus callosum, statistically moderates whether sleep spindles promoted overnight consolidation of motor skill memory. Therefore, white matter integrity within tracts known to connect cortical sensorimotor control regions dictates the functional influence of sleep spindles on motor skill memory consolidation in the elderly. The deterioration of white matter fiber tracts associated with human brain aging thus appears to be one pathophysiological mechanism influencing subcortical–cortical propagation of sleep spindles and their related memory benefits. SIGNIFICANCE STATEMENT Numerous studies have shown that sleep spindle expression is reduced and sleep-dependent motor memory is impaired in older adults. However, the mechanisms underlying these alterations have remained unknown. The present study reveals that age-related degeneration of white matter within select fiber tracts is associated with reduced sleep spindles in older adults. We further demonstrate that, within these same fiber tracts, the degree of degeneration determines whether sleep spindles can promote motor memory consolidation. Therefore, white matter integrity in the human brain, more than age per se, determines the magnitude of decline in sleep spindles in later life and, with it, the success (or lack thereof) of sleep-dependent motor memory consolidation in older adults. PMID:29084867

TIME COURSE FOR THE DEVELOPMENT OF MUSCLE HISTORY IN LUMBAR PARASPINAL MUSCLE SPINDLES ARISING FROM CHANGES IN VERTEBRAL POSITION

PubMed Central

Pickar, Joel G.; Ge, Weiqing

2008-01-01

Background Context In neutral spinal postures with low loading moments the lumbar spine is not inherently stable. Small compromises in paraspinal muscle activity may affect lumbar spinal biomechanics. Proprioceptive feedback from muscle spindles is considered important for control of muscle activity. Because skeletal muscle and muscle spindles are thixotropic, their length history changes their physical properties. The present study explores a mechanism that can affect the responsiveness of paraspinal muscle spindles in the lumbar spine. Purpose This study had two aims: to extend our previous findings demonstrating the history dependent effects of vertebral position on the responsiveness of lumbar paraspinal muscle spindles; and to determine the time course for these effects. Based upon previous studies, if a crossbridge mechanism underlies these thixotropic effects, then the relationship between the magnitude of spindle discharge and the duration of the vertebral position will be one of exponential decay or growth. Study Design/Setting A neurophysiological study using the lumbar spine of a feline model. Methods The discharge from individual muscle spindles afferents innervating lumbar paraspinal muscles in response to the duration and direction of vertebral position were obtained from teased filaments in the L6 dorsal roots of 30 Nembutal-anesthetized cats. The L6 vertebra was controlled using a displacement-controlled feedback motor and was held in each of 3 different conditioning positions for durations of 0, 0.5, 1, 1.5, and 2 seconds. Two of the conditioning positions stretched or shortened the lumbar muscles relative to an intermediate conditioning position. Conditioning positions for all cats ranged from 0.9 – 2.0 mm dorsal and ventralward relative to the intermediate position. These magnitudes were determined based upon the displacement that loaded the L6 vertebra to 50–60% of the cat’s body weight. Conditioning was thought to simulate a motion segment’s position that might be passively maintained due to fixation, external load, a prolonged posture, or structural change. Following conditioning positions that stretched (hold-long) and shortened (hold-short) the spindle, the vertebra was repositioned identically and muscle spindle discharge at rest and to movement was compared with conditioning at the intermediate position. Results Lumbar vertebral positions maintained for less than 2 seconds were capable of evoking different discharge rates from lumbar paraspinal muscle spindles despite the vertebra having been returned to identical locations. Both resting spindle discharge and their responsiveness to movement were altered. Conditioning vertebral positions that stretched the spindles decreased spindle activity and positions that unloaded the spindles increased spindle activity upon returning the vertebra to identical original (intermediate) positions. The magnitude of these effects increased as conditioning duration increased to 2 seconds. These effects developed with a time course following a first order exponential reaching a maximal value after approximately 4 seconds of history. The time constant for a hold-short history was 2.6 seconds and for a hold-long history was approximately half of that at 1.1 seconds. Conclusions Thixotropic contributions to the responsiveness of muscles spindles in the low back are caused by the rapid, spontaneous formation of stable crossbridges. These sensory alterations due to vertebral history would represent a proprioceptive input not necessarily representative of the current state of intersegmental positioning. As such, they would constitute a source of inaccurate sensory feedback. Examples are presented suggesting ways in which this novel finding may affect spinal physiology. PMID:17938002

Acceleration and Performance Modeling Workshop, Washington, DC, 14-17 May 79,

DTIC Science & Technology

1979-12-01

disturbance of the muscular systems, perhaps changes in spindle fiber output, and changes in the perceived weight of the muscle because of the acceleration...at this point either. The output models which are determining performance are essentially tied to muscular systems, through manual control (hand and...feet), and through speech, another muscular output. In normal activities the pilot, who senses changes in the visual system, the acceleration vector

Automated High-Throughput Quantification of Mitotic Spindle Positioning from DIC Movies of Caenorhabditis Embryos

PubMed Central

Cluet, David; Spichty, Martin; Delattre, Marie

2014-01-01

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 and the accuracy of the automated tracking matches the precision of the human eye. PMID:24763198

Mutations in the kinesin-like protein Eg5 disrupting localization to the mitotic spindle.

PubMed Central

Sawin, K E; Mitchison, T J

1995-01-01

Eg5, a member of the bimC subfamily of kinesin-like microtubule motor proteins, localizes to spindle microtubules in mitosis but not to interphase microtubules. We investigated the molecular basis for spindle localization by transient transfection of Xenopus A6 cells with myc-tagged derivatives of Eg5. Expressed at constitutively high levels from a cytomegalovirus promoter, mycEg5 protein is cytoplasmic throughout interphase, begins to bind microtubules in early prophase, and remains localized to spindle and/or midbody microtubules through mitosis to the end of telophase. Both N- and C-terminal regions of Eg5 are required for this cell-cycle-regulated targeting. Eg5 also contains within its C-terminal domain a sequence conserved among bimC subfamily proteins that includes a potential p34cdc2 phosphorylation site. We show that mutation of a single threonine (T937) within this site to nonphosphorylatable alanine abolishes localization of the mutant protein to the spindle, whereas mutation of T937 to serine preserves spindle localization. We hypothesize that phosphorylation of Eg5 may regulate its localization to the spindle in the cell cycle. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:7753799

The Chromokinesin Kid Is Required for Maintenance of Proper Metaphase Spindle SizeD⃞

PubMed Central

Tokai-Nishizumi, Noriko; Ohsugi, Miho; Suzuki, Emiko; Yamamoto, Tadashi

2005-01-01

The human chromokinesin Kid/kinesin-10, a plus end-directed microtubule (MT)-based motor with both microtubule- and DNA-binding domains, is required for proper chromosome alignment at the metaphase plate. Here, we performed RNA interference experiments to deplete endogenous Kid from HeLa cells and confirmed defects in metaphase chromosome arm alignment in Kid-depleted cells. In addition, we noted a shortening of the spindle length, resulting in a pole-to-pole distance only 80% of wild type. The spindle microtubule-bundles with which Kid normally colocalize became less robust. Rescue of the two Kid deficiency phenotypes—imprecise chromosome alignment at metaphase and shortened spindles— exhibited distinct requirements. Mutants lacking either the DNA-binding domain or the MT motor ATPase failed to rescue the former defect, whereas rescue of the shortened spindle phenotype required neither activity. Kid also exhibits microtubule bundling activity in vitro, and rescue of the shortened spindle phenotype and the bundling activity displayed similar domain requirements, except that rescue required a coiled-coil domain not needed for bundling. These results suggest that distinct from its role in chromosome movement, Kid contributes to spindle morphogenesis by mediating spindle microtubules stabilization. PMID:16176979

Kif2a regulates spindle organization and cell cycle progression in meiotic oocytes.

PubMed

Yi, Zi-Yun; Ma, Xue-Shan; Liang, Qiu-Xia; Zhang, Teng; Xu, Zhao-Yang; Meng, Tie-Gang; Ouyang, Ying-Chun; Hou, Yi; Schatten, Heide; Sun, Qing-Yuan; Quan, Song

2016-12-19

Kif2a is a member of the Kinesin-13 microtubule depolymerases. Here, we report the expression, subcellular localization and functions of Kif2a during mouse oocyte meiotic maturation. Immunoblotting analysis showed that Kif2a was gradually increased form GV to the M I stages, and then decreased slightly at the M II stage. Confocal microscopy identified that Kif2a localized to the meiotic spindle, especially concentrated at the spindle poles and inner centromeres in metaphase and translocated to the midbody at telophase. Kif2a depletion by siRNA microinjection generated severely defective spindles and misaligned chromosomes, reduced microtubule depolymerization, which led to significant pro-M I/M Iarrest and failure of first polar body (PB1) extrusion. Kif2a-depleted oocytes were also defective in spindle pole localization of γ-tubulin and showed spindle assembly checkpoint (SAC) protein Bub3 at the kinetochores even after 10 hr extended culture. These results demonstrate that Kif2a may act as a microtubule depolymerase, regulating microtubule dynamics, spindle assembly and chromosome congression, and thus cell cycle progression during mouse oocyte meiotic maturation.

Electro-Acoustic Behavior of the Mitotic Spindle: A Semi-Classical Coarse-Grained Model

PubMed Central

Havelka, Daniel; Kučera, Ondřej; Deriu, Marco A.; Cifra, Michal

2014-01-01

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. PMID:24497952

Evaluation of micro-organism-detaching efficacy from meat samples by spindle or stomacher treatment and quality analysis of suspensions.

PubMed

Kim, S-J; Kim, D-K; Kang, D-H

2016-04-01

We investigated and compared the efficacy of a new apparatus for detaching micro-organisms from meat samples. The efficacy of Spindle and stomacher in detaching micro-organisms from meat samples was evaluated. Also, evaluation of appropriateness of suspensions generated by both methods for carrying out molecular biological analysis was implemented. A nearly identical correlation and high R(2) were obtained between Spindle and stomacher in Aerobic Plate Count (APC), and no significant differences were observed in detachment of three major foodborne pathogens. The suspension generated by the Spindle showed lower turbidity and total protein concentration. Also, significantly different threshold cycles were observed in Real-time PCR analysis using suspensions generated by both methods. The Spindle shows nearly identical efficacy with stomacher treatment in detaching micro-organisms from meat samples. Furthermore, the high quality of suspensions generated by the Spindle, in terms of turbidity and total protein assay, allows for a lower threshold cycle than stomached suspension in Real-time PCR. The Spindle could be an alternative method for detaching micro-organisms, yielding a higher quality of suspensions which may be better suited for further molecular microbiological analysis. © 2016 The Society for Applied Microbiology.

EEG alpha spindles and prolonged brake reaction times during auditory distraction in an on-road driving study.

PubMed

Sonnleitner, Andreas; Treder, Matthias Sebastian; Simon, Michael; Willmann, Sven; Ewald, Arne; Buchner, Axel; Schrauf, Michael

2014-01-01

Driver distraction is responsible for a substantial number of traffic accidents. This paper describes the impact of an auditory secondary task on drivers' mental states during a primary driving task. N=20 participants performed the test procedure in a car following task with repeated forced braking on a non-public test track. Performance measures (provoked reaction time to brake lights) and brain activity (EEG alpha spindles) were analyzed to describe distracted drivers. Further, a classification approach was used to investigate whether alpha spindles can predict drivers' mental states. Results show that reaction times and alpha spindle rate increased with time-on-task. Moreover, brake reaction times and alpha spindle rate were significantly higher while driving with auditory secondary task opposed to driving only. In single-trial classification, a combination of spindle parameters yielded a median classification error of about 8% in discriminating the distracted from the alert driving. Reduced driving performance (i.e., prolonged brake reaction times) during increased cognitive load is assumed to be indicated by EEG alpha spindles, enabling the quantification of driver distraction in experiments on public roads without verbally assessing the drivers' mental states. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sleep Spindle Characteristics in Children with Neurodevelopmental Disorders and Their Relation to Cognition

PubMed Central

Wise, Merrill S.

2016-01-01

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. PMID:27478646

The Physics of the Metaphase Spindle.

PubMed

Oriola, David; Needleman, Daniel J; Brugués, Jan

2018-05-20

The assembly of the mitotic spindle and the subsequent segregation of sister chromatids are based on the self-organized action of microtubule filaments, motor proteins, and other microtubule-associated proteins, which constitute the fundamental force-generating elements in the system. Many of the components in the spindle have been identified, but until recently it remained unclear how their collective behaviors resulted in such a robust bipolar structure. Here, we review the current understanding of the physics of the metaphase spindle that is only now starting to emerge.

Role of Rad23 and Dsk2 in Nucleotide Excision Repair and Spindle Pole Body Duplication

DTIC Science & Technology

2006-03-01

AD Award Number: W81XWH-05-1-0310 TITLE: Role of Rad23 and Dsk2 in Nucleotide Excision Repair and Spindle Pole Body Duplication PRINCIPAL...Feb 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Role of Rad23 and Dsk2 in Nucleotide Excision Repair and Spindle Pole Body Duplication Sb. GRANT...Degradation, Cell Cycle, Spindle Pole Body 16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON OF ABSTRACT OF

Genetic Instability of Breast Cancer Cells Induced by Aberrant Expression of hMpS1

DTIC Science & Technology

2004-09-01

and function of the mitotic spindle is dependent on the MpS1 protein kinase. The components of mitotic spindle checkpoints were first identified in...yeast and their homologs of higher organisms were then identified and characterized. These include Bubl, Bub2, Bub3, Madl, Mad2, Mad3 and MpS1 . MpS 1...spindle checkpoint and centrosome duplication (1-6). Although several recent reports demonstrated that vertebrate MpS1 proteins regulate the spindle

Sleep spindles may predict response to cognitive-behavioral therapy for chronic insomnia.

PubMed

Dang-Vu, Thien Thanh; Hatch, Benjamin; Salimi, Ali; Mograss, Melodee; Boucetta, Soufiane; O'Byrne, Jordan; Brandewinder, Marie; Berthomier, Christian; Gouin, Jean-Philippe

2017-11-01

While cognitive-behavioral therapy for insomnia constitutes the first-line treatment for chronic insomnia, only few reports have investigated how sleep architecture relates to response to this treatment. In this pilot study, we aimed to determine whether pre-treatment sleep spindle density predicts treatment response to cognitive-behavioral therapy for insomnia. Twenty-four participants with chronic primary insomnia participated in a 6-week cognitive-behavioral therapy for insomnia performed in groups of 4-6 participants. Treatment response was assessed using the Pittsburgh Sleep Quality Index and the Insomnia Severity Index measured at pre- and post-treatment, and at 3- and 12-months' follow-up assessments. Secondary outcome measures were extracted from sleep diaries over 7 days and overnight polysomnography, obtained at pre- and post-treatment. Spindle density during stage N2-N3 sleep was extracted from polysomnography at pre-treatment. Hierarchical linear modeling analysis assessed whether sleep spindle density predicted response to cognitive-behavioral therapy. After adjusting for age, sex, and education level, lower spindle density at pre-treatment predicted poorer response over the 12-month follow-up, as reflected by a smaller reduction in Pittsburgh Sleep Quality Index over time. Reduced spindle density also predicted lower improvements in sleep diary sleep efficiency and wake after sleep onset immediately after treatment. There were no significant associations between spindle density and changes in the Insomnia Severity Index or polysomnography variables over time. These preliminary results suggest that inter-individual differences in sleep spindle density in insomnia may represent an endogenous biomarker predicting responsiveness to cognitive-behavioral therapy. Insomnia with altered spindle activity might constitute an insomnia subtype characterized by a neurophysiological vulnerability to sleep disruption associated with impaired responsiveness to cognitive-behavioral therapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Slow sleep spindle and procedural memory consolidation in patients with major depressive disorder

PubMed Central

Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

2016-01-01

Introduction Evidence has accumulated, which indicates that, in healthy individuals, sleep enhances procedural memory consolidation, and that sleep spindle activity modulates this process. However, whether sleep-dependent procedural memory consolidation occurs in patients medicated for major depressive disorder remains unclear, as are the pharmacological and physiological mechanisms that underlie this process. Methods Healthy control participants (n=17) and patients medicated for major depressive disorder (n=11) were recruited and subjected to a finger-tapping motor sequence test (MST; nondominant hand) paradigm to compare the averaged scores of different learning phases (presleep, postsleep, and overnight improvement). Participants’ brain activity was recorded during sleep with 16 electroencephalography channels (between MSTs). Sleep scoring and frequency analyses were performed on the electroencephalography data. Additionally, we evaluated sleep spindle activity, which divided the spindles into fast-frequency spindle activity (12.5–16 Hz) and slow-frequency spindle activity (10.5–12.5 Hz). Result Sleep-dependent motor memory consolidation in patients with depression was impaired in comparison with that in control participants. In patients with depression, age correlated negatively with overnight improvement. The duration of slow-wave sleep correlated with the magnitude of motor memory consolidation in patients with depression, but not in healthy controls. Slow-frequency spindle activity was associated with reduction in the magnitude of motor memory consolidation in both groups. Conclusion Because the changes in slow-frequency spindle activity affected the thalamocortical network dysfunction in patients medicated for depression, dysregulated spindle generation may impair sleep-dependent memory consolidation. Our findings may help to elucidate the cognitive deficits that occur in patients with major depression both in the waking state and during sleep. PMID:26869818

Counterinsurgency After Afghanistan: A Concept in Crisis

DTIC Science & Technology

2011-12-01

in strategy was undeniably stabilizing. This also explains the concrete walls, barriers, check- points, and other population-control measures...partnering with Sunni community leaders, Dagger Brigade was able to interpose itself—with concrete barriers, combined outposts, and checkpoints...local forces work together toward the same end. Also important in this regard are the aforementioned check- points, concrete barriers, and other

Frequency Response Studies using Receptance Coupling Approach in High Speed Spindles

NASA Astrophysics Data System (ADS)

Shaik, Jakeer Hussain; Ramakotaiah, K.; Srinivas, J.

2018-01-01

In order to assess the stability of high speed machining, estimate the frequency response at the end of tool tip is of great importance. Evaluating dynamic response of several combinations of integrated spindle-tool holder-tool will consume a lot of time. This paper presents coupled field dynamic response at tool tip for the entire integrated spindle tool unit. The spindle unit is assumed to be relying over the front and rear bearings and investigated using the Timoshenko beam theory to arrive the receptances at different locations of the spindle-tool unit. The responses are further validated with conventional finite element model as well as with the experiments. This approach permits quick outputs without losing accuracy of solution and further these methods are utilized to analyze the various design variables on system dynamics. The results obtained through this analysis are needed to design the better spindle unit in an attempt to reduce the frequency amplitudes at the tool tip to improvise the milling stability during cutting process.

Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning.

PubMed

Howard, Jonathon; Garzon-Coral, Carlos

2017-11-01

Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. © 2017 The Authors. BioEssays published by Wiley Periodicals, Inc.

Interactions between core and matrix thalamocortical projections in human sleep spindle synchronization

PubMed Central

Bonjean, Maxime; Baker, Tanya; Bazhenov, Maxim; Cash, Sydney; Halgren, Eric; Sejnowski, Terrence

2012-01-01

Sleep spindles, which are bursts of 11–15 Hz that occur during non-REM sleep, are highly synchronous across the scalp when measured with EEG, but have low spatial coherence and exhibit low correlation with EEG signals when simultaneously measured with MEG spindles in humans. We developed a computational model to explore the hypothesis that the spatial coherence of the EEG spindle is a consequence of diffuse matrix projections of the thalamus to layer 1 compared to the focal projections of the core pathway to layer 4 recorded by the MEG. Increasing the fanout of thalamocortical connectivity in the matrix pathway while keeping the core pathway fixed led to increased synchrony of the spindle activity in the superficial cortical layers in the model. In agreement with cortical recordings, the latency for spindles to spread from the core to the matrix was independent of the thalamocortical fanout but highly dependent on the probability of connections between cortical areas. PMID:22496571

Mechanical Forces Program the Orientation of Cell Division during Airway Tube Morphogenesis.

PubMed

Tang, Zan; Hu, Yucheng; Wang, Zheng; Jiang, Kewu; Zhan, Cheng; Marshall, Wallace F; Tang, Nan

2018-02-05

Oriented cell division plays a key role in controlling organogenesis. The mechanisms for regulating division orientation at the whole-organ level are only starting to become understood. By combining 3D time-lapse imaging, mouse genetics, and mathematical modeling, we find that global orientation of cell division is the result of a combination of two types of spindles with distinct spindle dynamic behaviors in the developing airway epithelium. Fixed spindles follow the classic long-axis rule and establish their division orientation before metaphase. In contrast, rotating spindles do not strictly follow the long-axis rule and determine their division orientation during metaphase. By using both a cell-based mechanical model and stretching-lung-explant experiments, we showed that mechanical force can function as a regulatory signal in maintaining the stable ratio between fixed spindles and rotating spindles. Our findings demonstrate that mechanical forces, cell geometry, and oriented cell division function together in a highly coordinated manner to ensure normal airway tube morphogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Autocatalytic microtubule nucleation determines the size and mass of Xenopus laevis egg extract spindles.

PubMed

Decker, Franziska; Oriola, David; Dalton, Benjamin; Brugués, Jan

2018-01-11

Regulation of size and growth is a fundamental problem in biology. A prominent example is the formation of the mitotic spindle, where protein concentration gradients around chromosomes are thought to regulate spindle growth by controlling microtubule nucleation. Previous evidence suggests that microtubules nucleate throughout the spindle structure. However, the mechanisms underlying microtubule nucleation and its spatial regulation are still unclear. Here, we developed an assay based on laser ablation to directly probe microtubule nucleation events in Xenopus laevis egg extracts. Combining this method with theory and quantitative microscopy, we show that the size of a spindle is controlled by autocatalytic growth of microtubules, driven by microtubule-stimulated microtubule nucleation. The autocatalytic activity of this nucleation system is spatially regulated by the limiting amounts of active microtubule nucleators, which decrease with distance from the chromosomes. This mechanism provides an upper limit to spindle size even when resources are not limiting. © 2018, Decker et al.

Ase1/Prc1-dependent spindle elongation corrects merotely during anaphase in fission yeast

PubMed Central

Courtheoux, Thibault; Gay, Guillaume; Tournier, Sylvie

2009-01-01

Faithful segregation of sister chromatids requires the attachment of each kinetochore (Kt) to microtubules (MTs) that extend from opposite spindle poles. Merotelic Kt orientation is a Kt–MT misattachment in which a single Kt binds MTs from both spindle poles rather than just one. Genetic induction of merotelic Kt attachment during anaphase in fission yeast resulted in intra-Kt stretching followed by either correction or Kt disruption. Laser ablation of spindle MTs revealed that intra-Kt stretching and merotelic correction were dependent on MT forces. The presence of multiple merotelic chromosomes linearly antagonized the spindle elongation rate, and this phenomenon could be solved numerically using a simple force balance model. Based on the predictions of our mechanical model, we provide in vivo evidence that correction of merotelic attachment in anaphase is tension dependent and requires an Ase1/Prc1-dependent mechanism that prevents spindle collapse and thus asymmetric division and/or the appearance of the cut phenotype. PMID:19948483

Dynamic maintenance of asymmetric meiotic spindle position through Arp2/3 complex-driven cytoplasmic streaming in mouse oocytes

PubMed Central

Yi, Kexi; Unruh, Jay R.; Deng, Manqi; Slaughter, Brian D.; Rubinstein, Boris; Li, Rong

2012-01-01

Mature mammalian oocytes are poised for the completion of second polar body extrusion upon fertilization by positioning the metaphase spindle in close proximity to an actomyosin-rich cortical cap. Loss of this spindle position asymmetry is often associated with poor oocyte quality and infertility 1–3. Here, we report a novel role for the Arp2/3 actin nucleation complex in the maintenance of asymmetric spindle position in mature mouse oocytes. The Arp2/3 complex localizes to the cortical cap in a Ran GTPase-dependent manner and accounts for the nucleation of the majority of actin filaments in both the cortical cap and a cytoplasmic actin network. Inhibition of Arp2/3 complex activity or localization leads to rapid dissociation of the spindle from the cortex. High resolution live imaging and spatiotemporal image correlation spectroscopy (STICS) analysis reveal that in normal oocytes actin filaments flow continuously away from the Arp2/3-rich cortex, generating a cytoplamic streaming that results in a net pushing force on the spindle toward the actomyosin cap. Arp2/3 inhibition not only diminishes this actin flow and cytoplamic streaming but also enables a reverse streaming driven by myosin-II-based cortical contraction, leading to spindle movement away from the cortex. We conclude that the Arp2/3 complex maintains asymmetric meiotic spindle position by generating an actin polymerization-driven cytoplamic streaming and by suppressing a counteracting force from myosin-II-based contractility. PMID:21874009

EEG alpha spindle measures as indicators of driver fatigue under real traffic conditions.

PubMed

Simon, Michael; Schmidt, Eike A; Kincses, Wilhelm E; Fritzsche, Martin; Bruns, Andreas; Aufmuth, Claus; Bogdan, Martin; Rosenstiel, Wolfgang; Schrauf, Michael

2011-06-01

The purpose of this study is to show the effectiveness of EEG alpha spindles, defined by short narrowband bursts in the alpha band, as an objective measure for assessing driver fatigue under real driving conditions. An algorithm for the identification of alpha spindles is described. The performance of the algorithm is tested based on simulated data. The method is applied to real data recorded under real traffic conditions and compared with the performance of traditional EEG fatigue measures, i.e. alpha-band power. As a highly valid fatigue reference, the last 20 min of driving from participants who aborted the drive due to heavy fatigue were used in contrast to the initial 20 min of driving. Statistical analysis revealed significant increases from the first to the last driving section of several alpha spindle parameters and among all traditional EEG frequency bands, only of alpha-band power; with larger effect sizes for the alpha spindle based measures. An increased level of fatigue over the same time periods for drop-outs, as compared to participants who did not abort the drive, was observed only by means of alpha spindle parameters. EEG alpha spindle parameters increase both fatigue detection sensitivity and specificity as compared to EEG alpha-band power. It is demonstrated that alpha spindles are superior to EEG band power measures for assessing driver fatigue under real traffic conditions. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Free Vibration Analysis of a Spinning Flexible DISK-SPINDLE System Supported by Ball Bearing and Flexible Shaft Using the Finite Element Method and Substructure Synthesis

NASA Astrophysics Data System (ADS)

JANG, G. H.; LEE, S. H.; JUNG, M. S.

2002-03-01

Free vibration of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft is analyzed by using Hamilton's principle, FEM and substructure synthesis. The spinning disk is described by using the Kirchhoff plate theory and von Karman non-linear strain. The rotating spindle and stationary shaft are modelled by Rayleigh beam and Euler beam respectively. Using Hamilton's principle and including the rigid body translation and tilting motion, partial differential equations of motion of the spinning flexible disk and spindle are derived consistently to satisfy the geometric compatibility in the internal boundary between substructures. FEM is used to discretize the derived governing equations, and substructure synthesis is introduced to assemble each component of the disk-spindle-bearing-shaft system. The developed method is applied to the spindle system of a computer hard disk drive with three disks, and modal testing is performed to verify the simulation results. The simulation result agrees very well with the experimental one. This research investigates critical design parameters in an HDD spindle system, i.e., the non-linearity of a spinning disk and the flexibility and boundary condition of a stationary shaft, to predict the free vibration characteristics accurately. The proposed method may be effectively applied to predict the vibration characteristics of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft in the various forms of computer storage device, i.e., FDD, CD, HDD and DVD.

A new method to measure circular runout of end-milling spindle based on cutting mark

NASA Astrophysics Data System (ADS)

Zhou, Jianlai; Liu, Shuchun

2008-12-01

A practical method is introduced to measure the circular runout of a end-milling spindle system at high speed rotations without the need of a reference sphere. A workpiece is held on a linear slide which moves along the axial direction of the spindle. The spindle is then programmed to run at a specific speed. A very sharp edge cutter must be used and the depth of cut will be very shallow in order to keep the cutting force very small. The workpiece is then fed into the end mill in order to make a cutting mark of teens μm in depth. The cutting marks are circular, and their diameters are related to the circular runout of the spindle system. The cutting mark that is generated at a specific speed is expected to contain information about the spindle circular runout at this speed. In practice the cutting marks are not perfectly circular. Therefore, a best-fit circle of a cutting mark is needed to determine its diameter. A high-resolution edge detector machine is used for this purpose. Quantitative precision analysis was carried out to confirm the accuracy and repeatability of this new measurement technique. It is demonstrated that this technique for the measurement of spindle circular runout is an effective tool in verifying the actual running accuracy of spindles at their actual operating speeds and can be accomplished without the need for a reference sphere.

In-series compliance of gastrocnemius muscle in cat step cycle: do spindles signal origin-to-insertion length?

PubMed Central

Elek, J; Prochazka, A; Hulliger, M; Vincent, S

1990-01-01

1. It has been claimed that stretch in the non-contractile (extramysial) portion of muscles is substantial, and may produce large discrepancies between the origin-to-insertion muscle length and the internal length variations 'seen' by muscle spindle endings. 2. In eight pentobarbitone-anaesthetized cats, we estimated stretch in the extramysial portion of medial gastrocnemius (MG) muscle with a method similar to the spindle null technique. 3. Length variations of MG previously monitored in a normal step cycle were reproduced with a computer-controlled length servo. The responses of test MG spindle endings were monitored in dorsal root filaments. Distributed stimulation of ventral root filaments, rate-modulated by the step-cycle EMG envelope, served to reproduce step-cycle forces. The filaments were selected so as to have no fusimotor action on the test spindle. 4. Spindle responses in active cycles were compared with those in passive cycles (stretch, but no distributed stimulation). In some cases concomitant tonic fusimotor stimulation was used to maintain spindle responsiveness throughout the cycle, both in active and passive trials. Generally, small discrepancies in spindle firing were seen. The passive trials were now repeated, with iterative adjustments of the length function, until the response matched the spindle firing profile in the active trial. The spindle 'saw' the same internal length change in the final passive trial as in the active trial. Any difference between the corresponding length profiles was attributed to extramysial displacement. 5. Extramysial displacement estimated in this was was maximal at short mean muscle lengths, reaching about 0.5 mm in a typical step cycle (force rising from 0 to 10 N). At longer mean muscle lengths where muscle force rose from say 2 to 12 N in the cycle, extramysial displacement was in the range 0.2-0.4 mm. 6. Except at very short lengths, the displacement was probably mainly tendinous. On this assumption, our results suggested that the stiffness of the MG tendinous compartment was force related, and about double that of cat soleus muscle at any given force. Calculations indicated that though the stretch was small, the MG tendon would store and release enough strain energy per cycle to contribute significantly to the E3 phase of the step cycle. The discrepancies in spindle firing were generally quite subtle, so we reject the claim that extramysial stretch poses a serious difficulty for inferences about fusimotion from chronic spindle afferent recordings. PMID:2148952

Novel POC1A mutation in primordial dwarfism reveals new insights for centriole biogenesis.

PubMed

Koparir, Asuman; Karatas, Omer F; Yuceturk, Betul; Yuksel, Bayram; Bayrak, Ali O; Gerdan, Omer F; Sagiroglu, Mahmut S; Gezdirici, Alper; Kirimtay, Koray; Selcuk, Ece; Karabay, Arzu; Creighton, Chad J; Yuksel, Adnan; Ozen, Mustafa

2015-10-01

POC1A encodes a WD repeat protein localizing to centrioles and spindle poles and is associated with short stature, onychodysplasia, facial dysmorphism and hypotrichosis (SOFT) syndrome. These main features are related to the defect in cell proliferation of chondrocytes in growth plate. In the current study, we aimed at identifying the molecular basis of two patients with primordial dwarfism (PD) in a single family through utilization of whole-exome sequencing. A novel homozygous p.T120A missense mutation was detected in POC1A in both patients, a known causative gene of SOFT syndrome, and confirmed using Sanger sequencing. To test the pathogenicity of the detected mutation, primary fibroblast cultures obtained from the patients and a control individual were used. For evaluating the global gene expression profile of cells carrying p.T120A mutation in POC1A, we performed the gene expression array and compared their expression profiles to those of control fibroblast cells. The gene expression array analysis showed that 4800 transcript probes were significantly deregulated in cells with p.T120A mutation in comparison to the control. GO term association results showed that deregulated genes are mostly involved in the extracellular matrix and cytoskeleton. Furthermore, the p.T120A missense mutation in POC1A caused the formation of abnormal mitotic spindle structure, including supernumerary centrosomes, and changes in POC1A were accompanied by alterations in another centrosome-associated WD repeat protein p80-katanin. As a result, we identified a novel mutation in POC1A of patients with PD and showed that this mutation causes the formation of multiple numbers of centrioles and multipolar spindles with abnormal chromosome arrangement. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Intramedullary spindle cell hemangioma: case report.

PubMed

Nasser, Rani; Ashayeri, Kimberly; Legatt, Alan D; Houten, John K

2016-09-01

The authors describe the case of a 48-year-old man found to have the first reported intramedullary spinal cord spindle cell hemangioma. Previous research indicates that spindle cell hemangiomas are rarely found in the spine. Only 3 previous cases exist, all in the intradural, extramedullary space. In the present case, gross-total resection of the tumor was possible with no loss of function from baseline. This report presents the successful resection of the first reported intramedullary spindle cell hemangioma and reports 4-month follow-up, demonstrating the biological behavior of this rare tumor.

Design and Delivery of HMT Half-Shaft Prototype

DTIC Science & Technology

2012-11-01

spindle welded to the outer joint output is ease of Design  and Delivery of HMT Half‐ Shaft  Prototype    24    assembly. Flange 1 contains threaded... spindle , and splined shafts . Also, the spindle of the production design is splined to match the splines of the hub internals. 2.2. Analysis The...inner-joint (Figure 33). Design  and Delivery of HMT Half‐ Shaft  Prototype    27      Figure 33: FBD of Flange/ Spindle Applying Newton’s Laws to the

X-43A Rudder Spindle Fatigue Life Estimate and Testing

NASA Technical Reports Server (NTRS)

Glaessgen, Edward H.; Dawicke, David S.; Johnston, William M.; James, Mark A.; Simonsen, Micah; Mason, Brian H.

2005-01-01

Fatigue life analyses were performed using a standard strain-life approach and a linear cumulative damage parameter to assess the effect of a single accidental overload on the fatigue life of the Haynes 230 nickel-base superalloy X-43A rudder spindle. Because of a limited amount of information available about the Haynes 230 material, a series of tests were conducted to replicate the overload and in-service conditions for the spindle and corroborate the analysis. Both the analytical and experimental results suggest that the spindle will survive the anticipated flight loads.

Inflammatory myofibroblastic tumors in two dogs.

PubMed

Knight, C; Fan, E; Riis, R; McDonough, S

2009-03-01

Two soft tissue masses from different locations in 2 dogs were submitted for histopathologic examination. Each was well demarcated and consisted of interweaving streams of bland spindle cells among which numerous plasma cells and lymphocytes were scattered. All the spindle cells reacted strongly to antibodies against vimentin and calponin, whereas a subset of the spindle cells expressed smooth muscle actin and desmin. Immunohistochemistry results were consistent with a myofibroblastic derivation for the spindle-cell population and the diagnosis of inflammatory myofibroblastic tumor (IMT) was made. This is the second report of IMT in the veterinary literature.

Casein kinase II is required for the spindle assembly checkpoint by regulating Mad2p in fission yeast

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shimada, Midori; Yamamoto, Ayumu; Murakami-Tonami, Yuko

2009-10-23

The spindle checkpoint is a surveillance mechanism that ensures the fidelity of chromosome segregation in mitosis. Here we show that fission yeast casein kinase II (CK2) is required for this checkpoint function. In the CK2 mutants mitosis occurs in the presence of a spindle defect, and the spindle checkpoint protein Mad2p fails to localize to unattached kinetochores. The CK2 mutants are sensitive to the microtubule depolymerising drug thiabendazole, which is counteracted by ectopic expression of mad2{sup +}. The level of Mad2p is low in the CK2 mutants. These results suggest that CK2 has a role in the spindle checkpoint bymore » regulating Mad2p.« less

Biophysical Aspects of Spindle Evolution

NASA Astrophysics Data System (ADS)

Farhadifar, Reza; Baer, Charlie; Needleman, Daniel

2011-03-01

The continual propagation of genetic material from one generation to the next is one of the most basic characteristics of all organisms. In eukaryotes, DNA is segregated into the two daughter cells by a highly dynamic, self-organizing structure called the mitotic spindle. Mitotic spindles can show remarkable variability between tissues and organisms, but there is currently little understanding of the biophysical and evolutionary basis of this diversity. We are studying how spontaneous mutations modify cell division during nematode development. By comparing the mutational variation - the raw material of evolution - with the variation present in nature, we are investigating how the mitotic spindle is shaped over the course of evolution. This combination of quantitative genetics and cellular biophysics gives insight into how the structure and dynamics of the spindle is formed through selection, drift, and biophysical constraints.

Regulating positioning and orientation of mitotic spindles via cell size and shape

NASA Astrophysics Data System (ADS)

Li, Jingchen; Jiang, Hongyuan

2018-01-01

Proper location of the mitotic spindle is critical for chromosome segregation and the selection of the cell division plane. However, how mitotic spindles sense cell size and shape to regulate their own position and orientation is still largely unclear. To investigate this question systematically, we used a general model by considering chromosomes, microtubule dynamics, and forces of various molecular motors. Our results show that in cells of various sizes and shapes, spindles can always be centered and oriented along the long axis robustly in the absence of other specified mechanisms. We found that the characteristic time of positioning and orientation processes increases with cell size. Spindles sense the cell size mainly by the cortical force in small cells and by the cytoplasmic force in large cells. In addition to the cell size, the cell shape mainly influences the orientation process. We found that more slender cells have a faster orientation process, and the final orientation is not necessarily along the longest axis but is determined by the radial profile and the symmetry of the cell shape. Finally, our model also reproduces the separation and repositioning of the spindle poles during the anaphase. Therefore, our work provides a general tool for studying the mitotic spindle across the whole mitotic phase.

Achilles tendon shape and echogenicity on ultrasound among active badminton players.

PubMed

Malliaras, P; Voss, C; Garau, G; Richards, P; Maffulli, N

2012-04-01

The relationship between Achilles tendon ultrasound abnormalities, including a spindle shape and heterogeneous echogenicity, is unclear. This study investigated the relationship between these abnormalities, tendon thickness, Doppler flow and pain. Sixty-one badminton players (122 tendons, 36 men, and 25 women) were recruited. Achilles tendon thickness, shape (spindle, parallel), echogenicity (heterogeneous, homogeneous) and Doppler flow (present or absent) were measured bilaterally with ultrasound. Achilles tendon pain (during or after activity over the last week) and pain and function [Victorian Institute of Sport Achilles Assessment (VISA-A)] were measured. Sixty-eight (56%) tendons were parallel with homogeneous echogenicity (normal), 22 (18%) were spindle shaped with homogeneous echogenicity, 16 (13%) were parallel with heterogeneous echogenicity and 16 (13%) were spindle shaped with heterogeneous echogenicity. Spindle shape was associated with self-reported pain (P<0.05). Heterogeneous echogenicity was associated with lower VISA-A scores than normal tendon (P<0.05). There was an ordinal relationship between normal tendon, parallel and heterogeneous and spindle shaped and heterogeneous tendons with regard to increasing thickness and likelihood of Doppler flow. Heterogeneous echogenicity with a parallel shape may be a physiological phase and may develop into heterogeneous echogenicity with a spindle shape that is more likely to be pathological. © 2010 John Wiley & Sons A/S.

Error-prone meiotic division and subfertility in mice with oocyte-conditional knockdown of pericentrin.

PubMed

Baumann, Claudia; Wang, Xiaotian; Yang, Luhan; Viveiros, Maria M

2017-04-01

Mouse oocytes lack canonical centrosomes and instead contain unique acentriolar microtubule-organizing centers (aMTOCs). To test the function of these distinct aMTOCs in meiotic spindle formation, pericentrin (Pcnt), an essential centrosome/MTOC protein, was knocked down exclusively in oocytes by using a transgenic RNAi approach. Here, we provide evidence that disruption of aMTOC function in oocytes promotes spindle instability and severe meiotic errors that lead to pronounced female subfertility. Pcnt-depleted oocytes from transgenic (Tg) mice were ovulated at the metaphase-II stage, but show significant chromosome misalignment, aneuploidy and premature sister chromatid separation. These defects were associated with loss of key Pcnt-interacting proteins (γ-tubulin, Nedd1 and Cep215) from meiotic spindle poles, altered spindle structure and chromosome-microtubule attachment errors. Live-cell imaging revealed disruptions in the dynamics of spindle assembly and organization, together with chromosome attachment and congression defects. Notably, spindle formation was dependent on Ran GTPase activity in Pcnt-deficient oocytes. Our findings establish that meiotic division is highly error-prone in the absence of Pcnt and disrupted aMTOCs, similar to what reportedly occurs in human oocytes. Moreover, these data underscore crucial differences between MTOC-dependent and -independent meiotic spindle assembly. © 2017. Published by The Company of Biologists Ltd.

Drosophila Klp67A binds prophase kinetochores to subsequently regulate congression and spindle length.

PubMed

Savoian, Matthew S; Glover, David M

2010-03-01

The kinesin-8 proteins are a family of microtubule-depolymerising motor molecules, which, despite their highly conserved roles in chromosome alignment and spindle dynamics, remain poorly characterised. Here, we report that the Drosophila kinesin-8 protein, Klp67A, exists in two spatially and functionally separable metaphase pools: at kinetochores and along the spindle. Fixed and live-cell analyses of different Klp67A recombinant variants indicate that this kinesin-8 first collects at kinetochores during prophase and, by metaphase, localises to the kinetochore outerplate. Although the catalytic motor activity of Klp67A is required for efficient kinetochore recruitment at all times, microtubules are entirely dispensable for this process. The tail of Klp67A does not play a role in kinetochore accumulation, but is both necessary and sufficient for spindle association. Using functional assays, we reveal that chromosome position and spindle length are determined by the microtubule-depolymerising motor activity of Klp67A exclusively when located at kinetochores, but not along the spindle. These data reveal that, unlike other metazoan kinesin-8 proteins, Klp67A binds the nascent prophase and mature metaphase kinetochore. From this location, Klp67A uses its motor activity to ensure chromosome alignment and proper spindle length.

Clathrin heavy chain 1 is required for spindle assembly and chromosome congression in mouse oocytes.

PubMed

Zhao, Jie; Wang, Lu; Zhou, Hong-Xia; Liu, Li; Lu, Angeleem; Li, Guang-Peng; Schatten, Heide; Liang, Cheng-Guang

2013-10-01

Clathrin heavy chain 1 (CLTC) has been considered a “moonlighting protein” which acts in membrane trafficking during interphase and in stabilizing spindle fibers during mitosis. However, its roles in meiosis, especially in mammalian oocyte maturation, remain unclear. This study investigated CLTC expression and function in spindle formation and chromosome congression during mouse oocyte meiotic maturation. Our results showed that the expression level of CLTC increased after germinal vesicle breakdown (GVBD) and peaked in the M phase. Immunostaining results showed CLTC distribution throughout the cytoplasm in a cell cycle-dependent manner. Appearance and disappearance of CLTC along with β-tubulin (TUBB) could be observed during spindle dynamic changes. To explore the relationship between CLTC and microtubule dynamics, oocytes at metaphase were treated with taxol or nocodazole. CLTC colocalized with TUBB at the enlarged spindle and with cytoplasmic asters after taxol treatment; it disassembled and distributed into the cytoplasm along with TUBB after nocodazole treatment. Disruption of CLTC function using stealth siRNA caused a decreased first polar body extrusion rate and extensive spindle formation and chromosome congression defects. Taken together, these results show that CLTC plays an important role in spindle assembly and chromosome congression through a microtubule correlation mechanism during mouse oocyte maturation.

JMJD5 (Jumonji Domain-containing 5) Associates with Spindle Microtubules and Is Required for Proper Mitosis.

PubMed

He, Zhimin; Wu, Junyu; Su, Xiaonan; Zhang, Ye; Pan, Lixia; Wei, Huimin; Fang, Qiang; Li, Haitao; Wang, Da-Liang; Sun, Fang-Lin

2016-02-26

Precise mitotic spindle assembly is a guarantee of proper chromosome segregation during mitosis. Chromosome instability caused by disturbed mitosis is one of the major features of various types of cancer. JMJD5 has been reported to be involved in epigenetic regulation of gene expression in the nucleus, but little is known about its function in mitotic process. Here we report the unexpected localization and function of JMJD5 in mitotic progression. JMJD5 partially accumulates on mitotic spindles during mitosis, and depletion of JMJD5 results in significant mitotic arrest, spindle assembly defects, and sustained activation of the spindle assembly checkpoint (SAC). Inactivating SAC can efficiently reverse the mitotic arrest caused by JMJD5 depletion. Moreover, JMJD5 is found to interact with tubulin proteins and associate with microtubules during mitosis. JMJD5-depleted cells show a significant reduction of α-tubulin acetylation level on mitotic spindles and fail to generate enough interkinetochore tension to satisfy the SAC. Further, JMJD5 depletion also increases the susceptibility of HeLa cells to the antimicrotubule agent. Taken together, these results suggest that JMJD5 plays an important role in regulating mitotic progression, probably by modulating the stability of spindle microtubules. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

The Msd1–Wdr8–Pkl1 complex anchors microtubule minus ends to fission yeast spindle pole bodies

PubMed Central

Yukawa, Masashi; Ikebe, Chiho

2015-01-01

The minus ends of spindle microtubules are anchored to a microtubule-organizing center. The conserved Msd1/SSX2IP proteins are localized to the spindle pole body (SPB) and the centrosome in fission yeast and humans, respectively, and play a critical role in microtubule anchoring. In this paper, we show that fission yeast Msd1 forms a ternary complex with another conserved protein, Wdr8, and the minus end–directed Pkl1/kinesin-14. Individual deletion mutants displayed the identical spindle-protrusion phenotypes. Msd1 and Wdr8 were delivered by Pkl1 to mitotic SPBs, where Pkl1 was tethered through Msd1–Wdr8. The spindle-anchoring defect imposed by msd1/wdr8/pkl1 deletions was suppressed by a mutation of the plus end–directed Cut7/kinesin-5, which was shown to be mutual. Intriguingly, Pkl1 motor activity was not required for its anchoring role once targeted to the SPB. Therefore, spindle anchoring through Msd1–Wdr8–Pkl1 is crucial for balancing the Cut7/kinesin-5–mediated outward force at the SPB. Our analysis provides mechanistic insight into the spatiotemporal regulation of two opposing kinesins to ensure mitotic spindle bipolarity. PMID:25987607

The Forkhead Transcription Factor Hcm1 Promotes Mitochondrial Biogenesis and Stress Resistance in Yeast*

PubMed Central

Rodriguez-Colman, Maria José; Reverter-Branchat, Gemma; Sorolla, M. Alba; Tamarit, Jordi; Ros, Joaquim; Cabiscol, Elisa

2010-01-01

In Saccharomyces cerevisiae, the forkhead transcription factor Hcm1 is involved in chromosome segregation, spindle pole dynamics, and budding. We found that Hcm1 interacts with the histone deacetylase Sir2 and shifts from cytoplasm to the nucleus in the G1/S phase or in response to oxidative stress stimuli. The nuclear localization of Hcm1 depends on the activity of Sir2 as revealed by activators and inhibitors of the sirtuins and the Δsir2 mutant. Hcm1-overexpressing cells display more mitochondria that can be attributed to increased amounts of Abf2, a protein involved in mitochondrial biogenesis. These cells also show higher rates of oxygen consumption and improved resistance to oxidative stress that would be explained by increased catalase and Sod2 activities and molecular chaperones such as Hsp26, Hsp30, and members of Hsp70 family. Microarray analyses also reveal increased expression of genes involved in mitochondrial energy pathways and those allowing the transition from the exponential to the stationary phase. Taken together, these results describe a new and relevant role of Hcm1 for mitochondrial functions, suggesting that this transcription factor would participate in the adaptation of cells from fermentative to respiratory metabolism. PMID:20847055

Ha-ras(val12) induces HSP70b transcription via the HSE/HSF1 system, but HSP70b expression is suppressed in Ha-ras(val12)-transformed cells.

PubMed

Stanhill, A; Levin, V; Hendel, A; Shachar, I; Kazanov, D; Arber, N; Kaminski, N; Engelberg, D

2006-03-09

Heat shock proteins (Hsps) are overexpressed in many tumors, but are downregulated in some tumors. To check for a direct effect of Ha-Ras(val12) on HSP70 transcription, we transiently expressed the oncoprotein in Rat1 fibroblasts and monitored its effect on HSP70b promoter-driven reporter gene. We show that expression of Ha-Ras(val12) induced this promoter. Promoter analysis via systematic deletions and point mutations revealed that Ha-Ras(val12) induces HSP70b transcription via heat shock elements (HSEs). Also, Ha-Ras(val12) induction of HSE-mediated transcription was dramatically reduced in HSF1-/- cells. Yet, residual effect of Ha-Ras(val12) that was still measured in HSF1-/- cells suggests that some of the Ha-Ras(val12) effect is Hsf1-independent. When HSF1-/- cells, stably expressing Ha-Ras(val12), were grown on soft agar only small colonies were formed suggesting a role for heat shock factor 1 (Hsf1) in Ha-Ras(val12)-mediated transformation. Although Ha-ras(Val12) seems to be an inducer of HSP70's expression, we found that in Ha-ras(Val12-)transformed fibroblasts expression of this gene is suppressed. This suppression is correlated with higher sensitivity of Ha-ras(val12)-transformed cells to heat shock. We suggest that Ha-ras(Val12) is involved in Hsf1 activation, thereby inducing the cellular protective response. Cells that repress this response are perhaps those that acquire the capability to further proliferate and become transformed clones.

Measurement and analysis of thrust force in drilling sisal-glass fiber reinforced polymer composites

NASA Astrophysics Data System (ADS)

Ramesh, M.; Gopinath, A.

2017-05-01

Drilling of composite materials is difficult when compared to the conventional materials because of its in-homogeneous nature. The force developed during drilling play a major role in the surface quality of the hole and minimizing the damages around the surface. This paper focuses the effect of drilling parameters on thrust force in drilling of sisal-glass fiber reinforced polymer composite laminates. The quadratic response models are developed by using response surface methodology (RSM) to predict the influence of cutting parameters on thrust force. The adequacy of the models is checked by using the analysis of variance (ANOVA). A scanning electron microscope (SEM) analysis is carried out to analyze the quality of the drilled surface. From the results, it is found that, the feed rate is the most influencing parameter followed by spindle speed and the drill diameter is the least influencing parameter on the thrust force.

Dynamic Selective Exposure during Decision-Making.

PubMed

Phillips, James G; Hoon, Teressa; Landon, Jason

2016-01-01

To understand dynamic changes in the likelihood that people would access and selectively expose themselves to information online, the present study examined the checking of account balances during simulated gambling. Sixteen participants played 120 hands of computer Blackjack for points, at higher or lower levels of risk (different point multipliers), and after each win or loss the computer recorded if participants checked their account balances. There were individual differences in checking rates. Participants who were more likely to check balances exhibited a selectivity of exposure to decision consonant information after a win at low risk. Although it was expected that people would seek to maintain positive mood, data were better explained in terms of Cognitive Dissonance. The effects of Cognitive Dissonance are liable to extend beyond single static decisions into dynamic online environments.

Responses in Rat Core Auditory Cortex are Preserved during Sleep Spindle Oscillations

PubMed Central

Sela, Yaniv; Vyazovskiy, Vladyslav V.; Cirelli, Chiara; Tononi, Giulio; Nir, Yuval

2016-01-01

Study Objectives: Sleep is defined as a reversible state of reduction in sensory responsiveness and immobility. A long-standing hypothesis suggests that a high arousal threshold during non-rapid eye movement (NREM) sleep is mediated by sleep spindle oscillations, impairing thalamocortical transmission of incoming sensory stimuli. Here we set out to test this idea directly by examining sensory-evoked neuronal spiking activity during natural sleep. Methods: We compared neuronal (n = 269) and multiunit activity (MUA), as well as local field potentials (LFP) in rat core auditory cortex (A1) during NREM sleep, comparing responses to sounds depending on the presence or absence of sleep spindles. Results: We found that sleep spindles robustly modulated the timing of neuronal discharges in A1. However, responses to sounds were nearly identical for all measured signals including isolated neurons, MUA, and LFPs (all differences < 10%). Furthermore, in 10% of trials, auditory stimulation led to an early termination of the sleep spindle oscillation around 150–250 msec following stimulus onset. Finally, active ON states and inactive OFF periods during slow waves in NREM sleep affected the auditory response in opposite ways, depending on stimulus intensity. Conclusions: Responses in core auditory cortex are well preserved regardless of sleep spindles recorded in that area, suggesting that thalamocortical sensory relay remains functional during sleep spindles, and that sensory disconnection in sleep is mediated by other mechanisms. Citation: Sela Y, Vyazovskiy VV, Cirelli C, Tononi G, Nir Y. Responses in rat core auditory cortex are preserved during sleep spindle oscillations. SLEEP 2016;39(5):1069–1082. PMID:26856904

The Spindle Positioning Protein Kar9p Interacts With the Sumoylation Machinery in Saccharomyces cerevisiae

PubMed Central

Meednu, Nida; Hoops, Harold; D'Silva, Sonia; Pogorzala, Leah; Wood, Schuyler; Farkas, David; Sorrentino, Mark; Sia, Elaine; Meluh, Pam; Miller, Rita K.

2008-01-01

Accurate positioning of the mitotic spindle is important for the genetic material to be distributed evenly in dividing cells, but little is known about the mechanisms that regulate this process. Here we report that two microtubule-associated proteins important for spindle positioning interact with several proteins in the sumoylation pathway. By two-hybrid analysis, Kar9p and Bim1p interact with the yeast SUMO Smt3p, the E2 enzyme Ubc9p, an E3 Nfi1p, as well as Wss1p, a weak suppressor of a temperature-sensitive smt3 allele. The physical interaction between Kar9p and Ubc9p was confirmed by in vitro binding assays. A single-amino-acid substitution in Kar9p, L304P disrupted its two-hybrid interaction with proteins in the sumoylation pathway, but retained its interactions with the spindle positioning proteins Bim1p, Stu2p, Bik1p, and Myo2p. The kar9-L304P mutant showed defects in positioning the mitotic spindle, with the spindle located more distally than normal. Whereas wild-type Kar9p-3GFP normally localizes to only the bud-directed spindle pole body (SPB), Kar9p-L304P-3GFP was mislocalized to both SPBs. Using a reconstitution assay, Kar9p was sumoylated in vitro. We propose a model in which sumoylation regulates spindle positioning by restricting Kar9p to one SPB. These findings raise the possibility that sumoylation could regulate other microtubule-dependent processes. PMID:18832349

Sleep Spindles and Intellectual Ability: Epiphenomenon or Directly Related?

PubMed

Fang, Zhuo; Sergeeva, Valya; Ray, Laura B; Viczko, Jeremy; Owen, Adrian M; Fogel, Stuart M

2017-01-01

Sleep spindles-short, phasic, oscillatory bursts of activity that characterize non-rapid eye movement sleep-are one of the only electrophysiological oscillations identified as a biological marker of human intelligence (e.g., cognitive abilities commonly assessed using intelligence quotient tests). However, spindles are also important for sleep maintenance and are modulated by circadian factors. Thus, the possibility remains that the relationship between spindles and intelligence quotient may be an epiphenomenon of a putative relationship between good quality sleep and cognitive ability or perhaps modulated by circadian factors such as morningness-eveningness tendencies. We sought to ascertain whether spindles are directly or indirectly related to cognitive abilities using mediation analysis. Here, we show that fast (13.5-16 Hz) parietal but not slow (11-13.5 Hz) frontal spindles in both non-rapid eye movement stage 2 sleep and slow wave sleep are directly related to reasoning abilities (i.e., cognitive abilities that support "fluid intelligence," such as the capacity to identify complex patterns and relationships and the use of logic to solve novel problems) but not verbal abilities (i.e., cognitive abilities that support "crystalized intelligence"; accumulated knowledge and experience) or cognitive abilities that support STM (i.e., the capacity to briefly maintain information in an available state). The relationship between fast spindles and reasoning abilities is independent of the indicators of sleep maintenance and circadian chronotype, thus suggesting that spindles are indeed a biological marker of cognitive abilities and can serve as a window to further explore the physiological and biological substrates that give rise to human intelligence.

Nek2A destruction marks APC/C activation at the prophase-to-prometaphase transition by spindle-checkpoint-restricted Cdc20.

PubMed

Boekhout, Michiel; Wolthuis, Rob

2015-04-15

Nek2 isoform A (Nek2A) is a presumed substrate of the anaphase-promoting complex/cyclosome containing Cdc20 (APC/C(Cdc20)). Nek2A, like cyclin A, is degraded in mitosis while the spindle checkpoint is active. Cyclin A prevents spindle checkpoint proteins from binding to Cdc20 and is recruited to the APC/C in prometaphase. We found that Nek2A and cyclin A avoid being stabilized by the spindle checkpoint in different ways. First, enhancing mitotic checkpoint complex (MCC) formation by nocodazole treatment inhibited the degradation of geminin and cyclin A, whereas Nek2A disappeared at a normal rate. Second, depleting Cdc20 effectively stabilized cyclin A but not Nek2A. Nevertheless, Nek2A destruction crucially depended on Cdc20 binding to the APC/C. Third, in contrast to cyclin A, Nek2A was recruited to the APC/C before the start of mitosis. Interestingly, the spindle checkpoint very effectively stabilized an APC/C-binding mutant of Nek2A, which required the Nek2A KEN box. Apparently, in cells, the spindle checkpoint primarily prevents Cdc20 from binding destruction motifs. Nek2A disappearance marks the prophase-to-prometaphase transition, when Cdc20, regardless of the spindle checkpoint, activates the APC/C. However, Mad2 depletion accelerated Nek2A destruction, showing that spindle checkpoint release further increases APC/C(Cdc20) catalytic activity. © 2015. Published by The Company of Biologists Ltd.

Why does a cleavage plane develop parallel to the spindle axis in conical sand dollar eggs? A key question for clarifying the mechanism of contractile ring positioning.

PubMed

Yoshigaki, Tomoyoshi

2003-03-21

Three types of models have been proposed about how the mitotic apparatus determines the position of the cleavage furrow in animal cells. In the first and second types, the contractile ring appears in a cortical region that least and most astral microtubules reach, respectively. The third type is that the spindle midzone positions the contractile ring. In the previous study, a new model was proposed through analyses of cytokinesis in sand dollar and sea urchin eggs. Gradients of the surface density of microtubule plus ends are assumed to drive membrane proteins whose accumulation causes the formation of contractile-ring microfilaments. In the present study, the validity of each model is examined by simulating the furrow formation in conical sand dollar eggs with the mitotic apparatus oriented perpendicular to the cone axis. The new model predicts that unilateral furrows with cleavage planes roughly parallel to the spindle axis appear between the mitotic apparatus and the vertex besides the normally positioned furrow. The predictions are consistent with the observations by Rappaport & Rappaport (1994, Dev. Biol.164, 258-266). The other three types of models do not predict the formation of the ectopic furrows. Furthermore, it is pointed out that only the new model has the ability to explain the geometrical relationship between the mitotic apparatus and the contractile ring under various experimental conditions. These results strongly suggest the real existence of the membrane proteins postulated in the model.

Ethics of Mitochondrial Replacement Techniques: A Habermasian Perspective.

PubMed

Palacios-González, César

2017-01-01

Jürgen Habermas is regarded as a central bioconservative commentator in the debate on the ethics of human prenatal genetic manipulations. While his main work on this topic, The Future of Human Nature, has been widely examined in regard to his position on prenatal genetic enhancement, his arguments regarding prenatal genetic therapeutic interventions have for the most part been overlooked. In this work I do two things. First, I present the three necessary conditions that Habermas establishes for a prenatal genetic manipulation to be regarded as morally permissible. Second, I examine if mitochondrial replacement techniques meet these necessary conditions. I investigate, specifically, the moral permissibility of employing pronuclear transfer and maternal spindle transfer. I conclude that, according to a Habermasian perspective on prenatal genetic manipulation, maternal spindle transfer (without using a preselected sperm and egg) and pronuclear transfer are morally impermissible. Maternal spindle transfer is, in principle, morally permissible, but only when we have beforehand preselected a sperm and an egg for our reproductive purpose. These findings are relevant for bioconservatives, both for those who hold a Habermasian stance and for those who hold something akin to a Habermasian stance, because they answer the question: what should bioconservatives do regarding mitochondrial replacement techniques? In fact, the answer to this question does not only normatively prescribe what bioconservatives should do in terms of their personal morality, but it also points towards what kind of legislation regulating mitochondrial replacement techniques they should aim at. © 2017 The Authors Bioethics Published by John Wiley & Sons Ltd.

Ethics of Mitochondrial Replacement Techniques: A Habermasian Perspective

PubMed Central

2016-01-01

Abstract Jürgen Habermas is regarded as a central bioconservative commentator in the debate on the ethics of human prenatal genetic manipulations. While his main work on this topic, The Future of Human Nature, has been widely examined in regard to his position on prenatal genetic enhancement, his arguments regarding prenatal genetic therapeutic interventions have for the most part been overlooked. In this work I do two things. First, I present the three necessary conditions that Habermas establishes for a prenatal genetic manipulation to be regarded as morally permissible. Second, I examine if mitochondrial replacement techniques meet these necessary conditions. I investigate, specifically, the moral permissibility of employing pronuclear transfer and maternal spindle transfer. I conclude that, according to a Habermasian perspective on prenatal genetic manipulation, maternal spindle transfer (without using a preselected sperm and egg) and pronuclear transfer are morally impermissible. Maternal spindle transfer is, in principle, morally permissible, but only when we have beforehand preselected a sperm and an egg for our reproductive purpose. These findings are relevant for bioconservatives, both for those who hold a Habermasian stance and for those who hold something akin to a Habermasian stance, because they answer the question: what should bioconservatives do regarding mitochondrial replacement techniques? In fact, the answer to this question does not only normatively prescribe what bioconservatives should do in terms of their personal morality, but it also points towards what kind of legislation regulating mitochondrial replacement techniques they should aim at. PMID:27973714

Do All Dinoflagellates have an Extranuclear Spindle?

PubMed

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. Copyright © 2015 Elsevier GmbH. All rights reserved.

The C. elegans RSA complex localizes protein phosphatase 2A to centrosomes and regulates mitotic spindle assembly.

PubMed

Schlaitz, Anne-Lore; Srayko, Martin; Dammermann, Alexander; Quintin, Sophie; Wielsch, Natalie; MacLeod, Ian; de Robillard, Quentin; Zinke, Andrea; Yates, John R; Müller-Reichert, Thomas; Shevchenko, Andrei; Oegema, Karen; Hyman, Anthony A

2007-01-12

Microtubule behavior changes during the cell cycle and during spindle assembly. However, it remains unclear how these changes are regulated and coordinated. We describe a complex that targets the Protein Phosphatase 2A holoenzyme (PP2A) to centrosomes in C. elegans embryos. This complex includes Regulator of Spindle Assembly 1 (RSA-1), a targeting subunit for PP2A, and RSA-2, a protein that binds and recruits RSA-1 to centrosomes. In contrast to the multiple functions of the PP2A catalytic subunit, RSA-1 and RSA-2 are specifically required for microtubule outgrowth from centrosomes and for spindle assembly. The centrosomally localized RSA-PP2A complex mediates these functions in part by regulating two critical mitotic effectors: the microtubule destabilizer KLP-7 and the C. elegans regulator of spindle assembly TPXL-1. By regulating a subset of PP2A functions at the centrosome, the RSA complex could therefore provide a means of coordinating microtubule outgrowth from centrosomes and kinetochore microtubule stability during mitotic spindle assembly.

A yeast gene essential for regulation of spindle pole duplication.

PubMed Central

Baum, P; Yip, C; Goetsch, L; Byers, B

1988-01-01

In eucaryotic cells, duplication of spindle poles must be coordinated with other cell cycle functions. We report here the identification in Saccharomyces cerevisiae of a temperature-sensitive lethal mutation, esp1, that deregulates spindle pole duplication. Mutant cells transferred to the nonpermissive temperature became unable to continue DNA synthesis and cell division but displayed repeated duplication of their spindle pole bodies. Although entry into this state after transient challenge by the nonpermissive temperature was largely lethal, rare survivors were recovered and found to have become increased in ploidy. If the mutant cells were held in G0 or G1 during exposure to the elevated temperature, they remained viable and maintained normal numbers of spindle poles. These results suggest dual regulation of spindle pole duplication, including a mechanism that promotes duplication as cells enter the division cycle and a negative regulatory mechanism, controlled by ESP1, that limits duplication to a single occurrence in each cell division cycle. Tetrad analysis has revealed that ESP1 resides at a previously undescribed locus on the right arm of chromosome VII. Images PMID:3072479

Direct kinetochore–spindle pole connections are not required for chromosome segregation

PubMed Central

Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B.; He, Jie; Le Berre, Maël; Tikhonenko, Irina; Ault, Jeffrey G.; McEwen, Bruce F.; Chen, James K.; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M.

2014-01-01

Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes′ kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the spindle equator during metaphase and segregated properly during anaphase when one of their K-fibers was severed near the kinetochore with a laser microbeam. We also found that, in normal fully assembled spindles, K-fibers of some chromosomes did not extend to the spindle pole. These K-fibers connected to adjacent K-fibers and/or nonkinetochore MTs. Poleward movement of chromosomes with short K-fibers was uncoupled from MT depolymerization at the kinetochore. Instead, these chromosomes moved by dynein-mediated transport of the entire K-fiber/kinetochore assembly. Thus, at least two distinct parallel mechanisms drive chromosome segregation in mammalian cells. PMID:25023516

Regulation of kinetochore recruitment of two essential mitotic spindle checkpoint proteins by Mps1 phosphorylation.

PubMed

Xu, Quanbin; Zhu, Songcheng; Wang, Wei; Zhang, Xiaojuan; Old, William; Ahn, Natalie; Liu, Xuedong

2009-01-01

Mps1 is a protein kinase that plays essential roles in spindle checkpoint signaling. Unattached kinetochores or lack of tension triggers recruitment of several key spindle checkpoint proteins to the kinetochore, which delays anaphase onset until proper attachment or tension is reestablished. Mps1 acts upstream in the spindle checkpoint signaling cascade, and kinetochore targeting of Mps1 is required for subsequent recruitment of Mad1 and Mad2 to the kinetochore. The mechanisms that govern recruitment of Mps1 or other checkpoint proteins to the kinetochore upon spindle checkpoint activation are incompletely understood. Here, we demonstrate that phosphorylation of Mps1 at T12 and S15 is required for Mps1 recruitment to the kinetochore. Mps1 kinetochore recruitment requires its kinase activity and autophosphorylation at T12 and S15. Mutation of T12 and S15 severely impairs its kinetochore association and markedly reduces recruitment of Mad2 to the kinetochore. Our studies underscore the importance of Mps1 autophosphorylation in kinetochore targeting and spindle checkpoint signaling.

Mathematical modeling and numerical simulation of the mitotic spindle orientation system.

PubMed

Ibrahim, Bashar

2018-05-21

The mitotic spindle orientation and position is crucial for the fidelity of chromosome segregation during asymmetric cell division to generate daughter cells with different sizes or fates. This mechanism is best understood in the budding yeast Saccharomyces cerevisiae, named the spindle position checkpoint (SPOC). The SPOC inhibits cells from exiting mitosis until the mitotic spindle is properly oriented along the mother-daughter polarity axis. Despite many experimental studies, the mechanisms underlying SPOC regulation remains elusive and unexplored theoretically. Here, a minimal mathematical is developed to describe SPOC activation and silencing having autocatalytic feedback-loop. Numerical simulations of the nonlinear ordinary differential equations (ODEs) model accurately reproduce the phenotype of SPOC mechanism. Bifurcation analysis of the nonlinear ODEs reveals the orientation dependency on spindle pole bodies, and how this dependence is altered by parameter values. These results provide for systems understanding on the molecular organization of spindle orientation system via mathematical modeling. The presented mathematical model is easy to understand and, within the above mentioned context, can be used as a base for further development of quantitative models in asymmetric cell-division. Copyright © 2018. Published by Elsevier Inc.

Sleep spindles and cognitive performance across adolescence: A meta-analytic review.

PubMed

Reynolds, C M; Short, M A; Gradisar, M

2018-07-01

Higher sleep spindle activity generally relates to better cognitive performance in adults, while studies in children often show the opposite. As children become young adults, there is rapid brain maturation and development of higher-order cognitive functions, and therefore investigations within this age group may elucidate the relationship between spindles and cognition in this developmental period. Twelve studies published between 2009 and 2016 were identified. Meta-analyses revealed a positive relationship between spindles and cognition overall (r = 0.27), however effects varied depending on cognitive domain. Moderate positive relationships were seen for fluid IQ (r = 0.44), working memory/executive function (r = 0.40) and speed/accuracy (r = 0.33), while full IQ/verbal IQ was not significantly associated (r = -0.05). Meta-regressions indicated cognitive domain and spindle characteristic had a small influence over effect sizes, while age and gender did not have a significant influence. The relationship between spindles and cognition in adolescents is likely influenced by individual neural makeup and brain maturation. Copyright © 2018 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Contractile Ring-independent Localization of DdINCENP, a Protein Important for Spindle Stability and CytokinesisD⃞V⃞

PubMed Central

Chen, Qian; Li, Hui; De Lozanne, Arturo

2006-01-01

Dictyostelium DdINCENP is a chromosomal passenger protein associated with centromeres, the spindle midzone, and poles during mitosis and the cleavage furrow during cytokinesis. Disruption of the single DdINCENP gene revealed important roles for this protein in mitosis and cytokinesis. DdINCENP null cells lack a robust spindle midzone and are hypersensitive to microtubule-depolymerizing drugs, suggesting that their spindles may not be stable. Furthermore DdCP224, a protein homologous to the microtubule-stabilizing protein TOGp/XMAP215, was absent from the spindle midzone of DdINCENP null cells. Overexpression of DdCP224 rescued the weak spindle midzone defect of DdINCENP null cells. Although not required for the localization of the myosin II contractile ring and subsequent formation of a cleavage furrow, DdINCENP is important for the abscission of daughter cells at the end of cytokinesis. Finally, we show that the localization of DdINCENP at the cleavage furrow is modulated by myosin II but it occurs by a mechanism different from that controlling the formation of the contractile ring. PMID:16339076

Direct kinetochore-spindle pole connections are not required for chromosome segregation.

PubMed

Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B; He, Jie; Le Berre, Maël; Tikhonenko, Irina; Ault, Jeffrey G; McEwen, Bruce F; Chen, James K; Sui, Haixin; Piel, Matthieu; Kapoor, Tarun M; Khodjakov, Alexey

2014-07-21

Segregation of genetic material occurs when chromosomes move to opposite spindle poles during mitosis. This movement depends on K-fibers, specialized microtubule (MT) bundles attached to the chromosomes' kinetochores. A long-standing assumption is that continuous K-fibers connect every kinetochore to a spindle pole and the force for chromosome movement is produced at the kinetochore and coupled with MT depolymerization. However, we found that chromosomes still maintained their position at the spindle equator during metaphase and segregated properly during anaphase when one of their K-fibers was severed near the kinetochore with a laser microbeam. We also found that, in normal fully assembled spindles, K-fibers of some chromosomes did not extend to the spindle pole. These K-fibers connected to adjacent K-fibers and/or nonkinetochore MTs. Poleward movement of chromosomes with short K-fibers was uncoupled from MT depolymerization at the kinetochore. Instead, these chromosomes moved by dynein-mediated transport of the entire K-fiber/kinetochore assembly. Thus, at least two distinct parallel mechanisms drive chromosome segregation in mammalian cells.

The Schizosaccharomyces pombe HIRA-Like Protein Hip1 Is Required for the Periodic Expression of Histone Genes and Contributes to the Function of Complex Centromeres

PubMed Central

Blackwell, Chris; Martin, Kate A.; Greenall, Amanda; Pidoux, Alison; Allshire, Robin C.; Whitehall, Simon K.

2004-01-01

HIRA-like (Hir) proteins are evolutionarily conserved and are implicated in the assembly of repressive chromatin. In Saccharomyces cerevisiae, Hir proteins contribute to the function of centromeres. However, S. cerevisiae has point centromeres that are structurally different from the complex centromeres of metazoans. In contrast, Schizosaccharomyces pombe has complex centromeres whose domain structure is conserved with that of human centromeres. Therefore, we examined the functions of the fission yeast Hir proteins Slm9 and the previously uncharacterised protein Hip1. Deletion of hip1+ resulted in phenotypes that were similar to those described previously for slm9Δ cells: a cell cycle delay, synthetic lethality with cdc25-22, and poor recovery from nitrogen starvation. However, while it has previously been shown that Slm9 is not required for the periodic expression of histone H2A, we found that loss of Hip1 led to derepression of core histone genes expression outside of S phase. Importantly, we found that deletion of either hip1+ or slm9+ resulted in increased rates of chromosome loss, increased sensitivity to spindle damage, and reduced transcriptional silencing in the outer centromeric repeats. Thus, S. pombe Hir proteins contribute to pericentromeric heterochromatin, and our data thus suggest that Hir proteins may be required for the function of metazoan centromeres. PMID:15121850

The Schizosaccharomyces pombe HIRA-like protein Hip1 is required for the periodic expression of histone genes and contributes to the function of complex centromeres.

PubMed

Blackwell, Chris; Martin, Kate A; Greenall, Amanda; Pidoux, Alison; Allshire, Robin C; Whitehall, Simon K

2004-05-01

HIRA-like (Hir) proteins are evolutionarily conserved and are implicated in the assembly of repressive chromatin. In Saccharomyces cerevisiae, Hir proteins contribute to the function of centromeres. However, S. cerevisiae has point centromeres that are structurally different from the complex centromeres of metazoans. In contrast, Schizosaccharomyces pombe has complex centromeres whose domain structure is conserved with that of human centromeres. Therefore, we examined the functions of the fission yeast Hir proteins Slm9 and the previously uncharacterised protein Hip1. Deletion of hip1(+) resulted in phenotypes that were similar to those described previously for slm9 Delta cells: a cell cycle delay, synthetic lethality with cdc25-22, and poor recovery from nitrogen starvation. However, while it has previously been shown that Slm9 is not required for the periodic expression of histone H2A, we found that loss of Hip1 led to derepression of core histone genes expression outside of S phase. Importantly, we found that deletion of either hip1(+) or slm9(+) resulted in increased rates of chromosome loss, increased sensitivity to spindle damage, and reduced transcriptional silencing in the outer centromeric repeats. Thus, S. pombe Hir proteins contribute to pericentromeric heterochromatin, and our data thus suggest that Hir proteins may be required for the function of metazoan centromeres.

Directional tuning of human forearm muscle afferents during voluntary wrist movements

PubMed Central

Jones, Kelvin E; Wessberg, Johan; Vallbo, Åke B

2001-01-01

Single unit activity was recorded with the microneurography technique from sixteen spindle afferents and one Golgi tendon organ afferent originating from the forearm extensor muscles. Impulse rates were studied while subjects performed unobstructed aiming movements at the wrist in eight different directions 45 deg apart. In addition, similar imposed movements were performed while the subject was instructed to remain relaxed. Movement amplitudes were about 5 deg and the speed 10–30 deg s−1. Joint movements were translated to movements of a cursor on a monitor to provide visual feedback. Individual spindle afferents modulated their activity over a number of targets, i.e. were broadly tuned, during these aiming movements. The preferred direction for a spindle afferent was the same during both passive and active movements, indicating that the fusimotor effects associated with active contractions had little or no effect on the direction of tuning. The direction of tuning of individual spindle afferents could be predicted from the biomechanically inferred length changes of the parent muscle. Thus spindle afferents responded as stretch receptors, i.e. impulse rates increased with lengthening and decreased with shortening, in active as well as passive movements. Spindles from muscles, which continuously counteracted gravity exhibited a stretch response and directional tuning during the phase of movement alone whereas their position sensitivity was poor. In contrast, spindle afferents from the muscles that had no or minimal antigravity role were directionally tuned during both the dynamic and the static phase of the aiming task and their position sensitivity was substantially higher. In spite of the limited data base from three extensor muscles it could be demonstrated that wrist joint position was remarkably well encoded in the ensemble muscle spindle data. In some cases the ensemble muscle spindle data encoded the instantaneous trajectory of movement as well. PMID:11600696

A quantitative study of skeletofusimotor innervation in the cat peroneus tertius muscle.

PubMed Central

Jami, L; Murthy, K S; Petit, J

1982-01-01

1. Physiological tests were used to identify skeletofusimotor or beta axons to the cat peroneus tertius muscle in order to assess the proportion of beta axons in the motor supply to this muscle. 2. Static beta axons (beta S) were identified by: (a) observation of a delay between the complete block of extrafusal contraction and the failure of spindle activation upon prolonged stimulation, (b) increase of spindle excitation with stimulation frequencies above that eliciting maximal extrafusal contraction, (c) observation of 'unfused' frequencygram of spindle primary afferent discharge during stimulation of the axon at frequencies above that eliciting complete fusion of extrafusal contraction and (d) static action exerted on the response of the spindle afferent to ramp stretch. 3. Dynamic beta axons (beta D) were identified by the persistence of spindle activation after selective block of extrafusal neuromuscular junctions and by their dynamic action on spindle primary endings. 4. The actions of 116 motor axons (conduction velocity 56-104 m/sec) on ninety-five spindle afferents (fifty-seven from primary and thirty-eight from secondary endings) were examined in ten experiments. Thirty-six beta axons (31% of the total sample) were identified: twenty-four beta S (conduction velocity 69-104 m/sec) and twelve beta D (conduction velocity 56-91 m/sec). 5. Twenty (35%) primary endings were activated by a beta S and sixteen (28%) by a beta D axon. Nineteen (45%) secondary endings were activated by a beta S and five (13%) by a beta D axon. Convergence of beta D and beta S axons on the same spindle occurred in 10% of instances. beta-innervated spindles were also supplied by gamma axons. 6. Most of the beta S motor units were of the fast-fatigue resistant (FR) type, with a few units of the fast-fatigable (FF) type, and nearly all the beta D motor units were of the slow (S) type. PMID:6213764

Force encoding in muscle spindles during stretch of passive muscle

PubMed Central

Blum, Kyle P.; Zytnicki, Daniel

2017-01-01

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 relevant to the detection and sensorimotor response to mechanical perturbations to the body, and to previously-described history-dependence in perception of limb position. PMID:28945740

Force encoding in muscle spindles during stretch of passive muscle.

PubMed

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 relevant to the detection and sensorimotor response to mechanical perturbations to the body, and to previously-described history-dependence in perception of limb position.

Suprasellar chordoid neoplasm with expression of thyroid transcription factor 1: evidence that chordoid glioma of the third ventricle and pituicytoma may form part of a spectrum of lineage-related tumors of the basal forebrain.

PubMed

Hewer, Ekkehard; Beck, Jürgen; Kellner-Weldon, Frauke; Vajtai, Istvan

2015-07-01

Chordoid glioma of the third ventricle is a rare neuroepithelial tumor characterized by a unique histomorphology and exclusive association with the suprasellar/third ventricular compartment. Variously interpreted as either astrocytic- or ependymal-like, and speculatively ascribed to the lamina terminalis/subcommissural organ, its histogenesis remains, nevertheless, unsettled. Here, we report on a suprasellar chordoid glioma occurring in a 52-year-old man. Although displaying otherwise typical morphological features, the tumor was notable for expression of thyroid transcription factor 1, a marker of tumors of pituicytic origin in the context of the sellar region. We furthermore found overlapping immunoprofiles of this example of chordoid glioma and pituicytic tumors (pituicytoma and spindle cell oncocytoma), respectively. Specifically, phosphorylated ribosomal protein S6, a marker of mTOR pathway activation, was expressed in both groups. Based on these findings, we suggest that chordoid glioma and pituicytic tumors may form part of a spectrum of lineage-related neoplasms of the basal forebrain. Copyright © 2015 Elsevier Inc. All rights reserved.

NUCLEOPORINS NPP-1, NPP-3, NPP-4, NPP-11 and NPP-13 ARE REQUIRED FOR PROPER SPINDLE ORIENTATION IN C. ELEGANS

PubMed Central

Schetter, Aaron; Askjaer, Peter; Piano, Fabio; Mattaj, Iain; Kemphues, Kenneth

2006-01-01

Nucleoporins are components of the nuclear pore, which is required for nucleo-cytoplasmic transport. We report a role for a subclass of nucleoporins in orienting the mitotic spindle in C. elegans embryos. RNAi-mediated depletion of any of five putative nucleoporins npp-1, npp-3, npp-4, npp-11, and npp-13 leads to indistinguishable spindle orientation defects. Transgenic worms expressing NPP-1::GFP or NPP-11::GFP show GFP localization at the nuclear envelope, consistent with their predicted function. NPP-1 interacts with the other nucleoporins in yeast two-hybrid assays suggesting that the proteins affect spindle orientation by a common process. The failed orientation phenotype of npp-1(RNAi) is at least partially epistatic to the ectopic spindle rotation in the AB blastomere of par-3 mutant embryos. This suggests that NPP-1 contributes to the mechanics of spindle orientation. However, NPP-1 is also required for PAR-6 asymmetry at the two-cell stage, indicating that nucleoporins may be required to define cortical domains in the germ line blasotmere P1. Nuclear envelope structure is abnormal in npp-1(RNAi) embryos but the envelope maintains its integrity and most nuclear proteins we assayed accumulate normally. These findings raise the possibility that these nucleoporins may have direct roles in orienting the mitotic spindle and the maintenance of cell polarity. PMID:16325795

Amphiastral Mitotic Spindle Assembly in Vertebrate Cells Lacking Centrosomes

PubMed Central

Hornick, Jessica E.; Mader, Christopher C.; Tribble, Emily K.; Bagne, Cydney C.; Vaughan, Kevin T.; Shaw, Sidney L.; Hinchcliffe, Edward H.

2011-01-01

Summary The role of centrosomes/centrioles during mitotic spindle assembly in vertebrates remains controversial. In cell-free extracts and experimentally derived acentrosomal cells, randomly oriented microtubules (MTs) self-organize around mitotic chromosomes and assemble anastral spindles [1, 2, 3]. However, vertebrate somatic cells normally assemble a connected pair of polarized, astral MT arrays – termed an amphiaster (“a star on both sides” [4]) – that is formed by the splitting and separation of the microtubule-organizing center (MTOC) well before nuclear envelope breakdown (NEB) [5]. Whether amphiaster formation requires splitting of duplicated centrosomes is not known. We found that when centrosomes were removed from living vertebrate cells early in their cell cycle, an acentriolar MTOC re-assembled, and prior to NEB, a functional amphiastral spindle formed. Cytoplasmic dynein, dynactin, and pericentrin are all recruited to the interphase aMTOC, and the activity of kinesin-5 is needed for amphiaster formation. Mitosis proceeded on time and these karyoplasts divided in two. However, ~35% of aMTOCs failed to split/separate before NEB, and these entered mitosis with persistent monastral spindles. The chromatin-mediated RAN-GTP pathway could not restore bipolarity to monastral spindles, and these cells exited mitosis as single daughters. Our data reveal the novel finding that MTOC separation and amphiaster formation does not absolutely require the centrosome, but in its absence, the fidelity of bipolar spindle assembly is highly compromised. PMID:21439826

Postovulatory aging affects dynamics of mRNA, expression and localization of maternal effect proteins, spindle integrity and pericentromeric proteins in mouse oocytes

PubMed Central

Trapphoff, T.; Heiligentag, M.; Dankert, D.; Demond, H.; Deutsch, D.; Fröhlich, T.; Arnold, G.J.; Grümmer, R.; Horsthemke, B.; Eichenlaub-Ritter, U.

2016-01-01

Abstract STUDY QUESTION Is the postovulatory aging-dependent differential decrease of mRNAs and polyadenylation of mRNAs coded by maternal effect genes associated with altered abundance and distribution of maternal effect and RNA-binding proteins (MSY2)? SUMMARY ANSWER Postovulatory aging results in differential reduction in abundance of maternal effect proteins, loss of RNA-binding proteins from specific cytoplasmic domains and critical alterations of pericentromeric proteins without globally affecting protein abundance. WHAT IS KNOWN ALREADY Oocyte postovulatory aging is associated with differential alteration in polyadenylation and reduction in abundance of mRNAs coded by selected maternal effect genes. RNA-binding and -processing proteins are involved in storage, polyadenylation and degradation of mRNAs thus regulating stage-specific recruitment of maternal mRNAs, while chromosomal proteins that are stage-specifically expressed at pericentromeres, contribute to control of chromosome segregation and regulation of gene expression in the zygote. STUDY DESIGN, SIZE, DURATION Germinal vesicle (GV) and metaphase II (MII) oocytes from sexually mature C57B1/6J female mice were investigated. Denuded in vivo or in vitro matured MII oocytes were postovulatory aged and analyzed by semiquantitative confocal microscopy for abundance and localization of polyadenylated RNAs, proteins of maternal effect genes (transcription activator BRG1 also known as ATP-dependent helicase SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4 (SMARCA4) and NOD-like receptor family pyrin domain containing 5 (NLRP5) also known as MATER), RNA-binding proteins (MSY2 also known as germ cell-specific Y-box-binding protein, YBX2), and post-transcriptionally modified histones (trimethylated histone H3K9 and acetylated histone H4K12), as well as pericentromeric ATRX (alpha thalassemia/mental retardation syndrome X-linked, also termed ATP-dependent helicase ATRX or X-linked nuclear protein (XNP)). For proteome analysis five replicates of 30 mouse oocytes were analyzed by selected reaction monitoring (SRM). MATERIAL AND METHODS GV and MII oocytes were obtained from large antral follicles or ampullae of sexually mature mice, respectively. Denuded MII oocytes were aged for 24 h post ovulation. For analysis of distribution and abundance of polyadenylated RNAs fixed oocytes were in situ hybridized to Cy5 labeled oligo(dT)20 nucleotides. Absolute quantification of protein concentration per oocyte of selected proteins was done by SRM proteome analysis. Relative abundance of ATRX was assessed by confocal laser scanning microscopy (CLSM) of whole mount formaldehyde fixed oocytes or after removal of zona and spreading. MSY2 protein distribution and abundance was studied in MII oocytes prior to, during and after exposure to nocodazole, or after aging for 2 h in presence of H2O2 or for 24 h in presence of a glutathione donor, glutathione ethylester (GEE). MAIN RESULTS AND ROLE OF CHANCE The significant reduction in abundance of proteins (P < 0.001) translated from maternal mRNAs was independent of polyadenylation status, while their protein localization was not significantly changed by aging. Most of other proteins quantified by SRM analysis did not significantly change in abundance upon aging except MSY2 and GTSF1. MSY2 was enriched in the subcortical RNP domain (SCRD) and in the spindle chromosome complex (SCC) in a distinct pattern, right and left to the chromosomes. There was a significant loss of MSY2 from the SCRD (P < 0.001) and the spindle after postovulatory aging. Microtubule de- and repolymerization caused reversible loss of MSY2 spindle-association whereas H2O2 stress did not significantly decrease MSY2 abundance. Aging in presence of GEE decreased significantly (P < 0.05) the aging-related overall and cytoplasmic loss of MSY2. Postovulatory aging increased significantly spindle abnormalities, unaligned chromosomes, and abundance of acetylated histone H4K12, and decreased pericentromeric trimethylated histone H3K9 (all P < 0.001). Spreading revealed a highly significant increase in pericentromeric ATRX (P < 0.001) upon ageing. Thus, the significantly reduced abundance of MSY2 protein, especially at the SCRD and the spindle may disturb the spatial control and timely recruitment, deadenylation and degradation of developmentally important RNAs. An autonomous program of degradation appears to exist which transiently and specifically induces the loss and displacement of transcripts and specific maternal proteins independent of fertilization in aging oocytes and thereby can critically affect chromosome segregation and gene expression in the embryo after fertilization. LIMITATION, REASONS FOR CAUTION We used the mouse oocyte to study processes associated with postovulatory aging, which may not entirely reflect processes in aging human oocytes. However, increases in spindle abnormalities, unaligned chromosomes and H4K12 acetylated histones, as well as in mRNA abundance and polyadenylation have been observed also in aged human oocytes suggesting conserved processes in aging. WIDER IMPLICATIONS OF THE FINDINGS Postovulatory aging precociously induces alterations in expression and epigenetic modifications of chromatin by ATRX and in histone pattern in MII oocytes that normally occur after fertilization, possibly contributing to disturbances in the oocyte-to-embryo transition (OET) and the zygotic gene activation (ZGA). These observations in mouse oocytes are also relevant to explain disturbances and reduced developmental potential of aged human oocytes and caution to prevent oocyte aging in vivo and in vitro. STUDY FUNDING/COMPETING INTERESTS The study has been supported by the German Research Foundation (DFG) (EI 199/7-1 | GR 1138/12-1 | HO 949/21-1 and FOR 1041). There is no competing interest. PMID:26577303

Postovulatory aging affects dynamics of mRNA, expression and localization of maternal effect proteins, spindle integrity and pericentromeric proteins in mouse oocytes.

PubMed

Trapphoff, T; Heiligentag, M; Dankert, D; Demond, H; Deutsch, D; Fröhlich, T; Arnold, G J; Grümmer, R; Horsthemke, B; Eichenlaub-Ritter, U

2016-01-01

Is the postovulatory aging-dependent differential decrease of mRNAs and polyadenylation of mRNAs coded by maternal effect genes associated with altered abundance and distribution of maternal effect and RNA-binding proteins (MSY2)? Postovulatory aging results in differential reduction in abundance of maternal effect proteins, loss of RNA-binding proteins from specific cytoplasmic domains and critical alterations of pericentromeric proteins without globally affecting protein abundance. Oocyte postovulatory aging is associated with differential alteration in polyadenylation and reduction in abundance of mRNAs coded by selected maternal effect genes. RNA-binding and -processing proteins are involved in storage, polyadenylation and degradation of mRNAs thus regulating stage-specific recruitment of maternal mRNAs, while chromosomal proteins that are stage-specifically expressed at pericentromeres, contribute to control of chromosome segregation and regulation of gene expression in the zygote. Germinal vesicle (GV) and metaphase II (MII) oocytes from sexually mature C57B1/6J female mice were investigated. Denuded in vivo or in vitro matured MII oocytes were postovulatory aged and analyzed by semiquantitative confocal microscopy for abundance and localization of polyadenylated RNAs, proteins of maternal effect genes (transcription activator BRG1 also known as ATP-dependent helicase SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a, member 4 (SMARCA4) and NOD-like receptor family pyrin domain containing 5 (NLRP5) also known as MATER), RNA-binding proteins (MSY2 also known as germ cell-specific Y-box-binding protein, YBX2), and post-transcriptionally modified histones (trimethylated histone H3K9 and acetylated histone H4K12), as well as pericentromeric ATRX (alpha thalassemia/mental retardation syndrome X-linked, also termed ATP-dependent helicase ATRX or X-linked nuclear protein (XNP)). For proteome analysis five replicates of 30 mouse oocytes were analyzed by selected reaction monitoring (SRM). GV and MII oocytes were obtained from large antral follicles or ampullae of sexually mature mice, respectively. Denuded MII oocytes were aged for 24 h post ovulation. For analysis of distribution and abundance of polyadenylated RNAs fixed oocytes were in situ hybridized to Cy5 labeled oligo(dT)20 nucleotides. Absolute quantification of protein concentration per oocyte of selected proteins was done by SRM proteome analysis. Relative abundance of ATRX was assessed by confocal laser scanning microscopy (CLSM) of whole mount formaldehyde fixed oocytes or after removal of zona and spreading. MSY2 protein distribution and abundance was studied in MII oocytes prior to, during and after exposure to nocodazole, or after aging for 2 h in presence of H2O2 or for 24 h in presence of a glutathione donor, glutathione ethylester (GEE). The significant reduction in abundance of proteins (P < 0.001) translated from maternal mRNAs was independent of polyadenylation status, while their protein localization was not significantly changed by aging. Most of other proteins quantified by SRM analysis did not significantly change in abundance upon aging except MSY2 and GTSF1. MSY2 was enriched in the subcortical RNP domain (SCRD) and in the spindle chromosome complex (SCC) in a distinct pattern, right and left to the chromosomes. There was a significant loss of MSY2 from the SCRD (P < 0.001) and the spindle after postovulatory aging. Microtubule de- and repolymerization caused reversible loss of MSY2 spindle-association whereas H2O2 stress did not significantly decrease MSY2 abundance. Aging in presence of GEE decreased significantly (P < 0.05) the aging-related overall and cytoplasmic loss of MSY2. Postovulatory aging increased significantly spindle abnormalities, unaligned chromosomes, and abundance of acetylated histone H4K12, and decreased pericentromeric trimethylated histone H3K9 (all P < 0.001). Spreading revealed a highly significant increase in pericentromeric ATRX (P < 0.001) upon ageing. Thus, the significantly reduced abundance of MSY2 protein, especially at the SCRD and the spindle may disturb the spatial control and timely recruitment, deadenylation and degradation of developmentally important RNAs. An autonomous program of degradation appears to exist which transiently and specifically induces the loss and displacement of transcripts and specific maternal proteins independent of fertilization in aging oocytes and thereby can critically affect chromosome segregation and gene expression in the embryo after fertilization. We used the mouse oocyte to study processes associated with postovulatory aging, which may not entirely reflect processes in aging human oocytes. However, increases in spindle abnormalities, unaligned chromosomes and H4K12 acetylated histones, as well as in mRNA abundance and polyadenylation have been observed also in aged human oocytes suggesting conserved processes in aging. Postovulatory aging precociously induces alterations in expression and epigenetic modifications of chromatin by ATRX and in histone pattern in MII oocytes that normally occur after fertilization, possibly contributing to disturbances in the oocyte-to-embryo transition (OET) and the zygotic gene activation (ZGA). These observations in mouse oocytes are also relevant to explain disturbances and reduced developmental potential of aged human oocytes and caution to prevent oocyte aging in vivo and in vitro. The study has been supported by the German Research Foundation (DFG) (EI 199/7-1 | GR 1138/12-1 | HO 949/21-1 and FOR 1041). There is no competing interest. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The relationship of point-of-sale tobacco advertising and neighborhood characteristics to underage sales of tobacco.

PubMed

Widome, Rachel; Brock, Betsy; Noble, Petra; Forster, Jean L

2012-09-01

Our objective was to determine how point-of-sale tobacco marketing may relate to sales to minors. The authors used data from a 2007 cross-sectional study of the retail tobacco marketing environments in the St. Paul, MN metropolitan area matched with a database of age-of-sale compliance checks (random, covert test purchases by a minor, coordinated by law enforcement) of tobacco retailers and U.S. Census data to test whether certain characteristics of advertising or neighborhoods were associated with compliance check failure. The authors found that tobacco stores were the most likely type of store to fail compliance checks (44% failure), supermarkets were least likely (3%). Aside from a marginally significant association with Hispanic population proportion, there was no other association between either store advertising characteristics or neighborhood demographics and stores' compliance check failure. Though our findings were null, the relationship between advertising and real youth sales may be more nuanced as compliance checks do not perfectly simulate the way youth attempt to purchase cigarettes.

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

PubMed

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.

Fusimotor control of spindle sensitivity regulates central and peripheral coding of joint angles.

PubMed

Lan, Ning; He, Xin

2012-01-01

Proprioceptive afferents from muscle spindles encode information about peripheral joint movements for the central nervous system (CNS). The sensitivity of muscle spindle is nonlinearly dependent on the activation of gamma (γ) motoneurons in the spinal cord that receives inputs from the motor cortex. How fusimotor control of spindle sensitivity affects proprioceptive coding of joint position is not clear. Furthermore, what information is carried in the fusimotor signal from the motor cortex to the muscle spindle is largely unknown. In this study, we addressed the issue of communication between the central and peripheral sensorimotor systems using a computational approach based on the virtual arm (VA) model. In simulation experiments within the operational range of joint movements, the gamma static commands (γ(s)) to the spindles of both mono-articular and bi-articular muscles were hypothesized (1) to remain constant, (2) to be modulated with joint angles linearly, and (3) to be modulated with joint angles nonlinearly. Simulation results revealed a nonlinear landscape of Ia afferent with respect to both γ(s) activation and joint angle. Among the three hypotheses, the constant and linear strategies did not yield Ia responses that matched the experimental data, and therefore, were rejected as plausible strategies of spindle sensitivity control. However, if γ(s) commands were quadratically modulated with joint angles, a robust linear relation between Ia afferents and joint angles could be obtained in both mono-articular and bi-articular muscles. With the quadratic strategy of spindle sensitivity control, γ(s) commands may serve as the CNS outputs that inform the periphery of central coding of joint angles. The results suggest that the information of joint angles may be communicated between the CNS and muscles via the descending γ(s) efferent and Ia afferent signals.

Microtubule-dependent path to the cell cortex for cytoplasmic dynein in mitotic spindle orientation

PubMed Central

Markus, Steven M.; Lee, Wei-Lih

2011-01-01

During animal development, microtubules (MTs) play a major role in directing cellular and subcellular patterning, impacting cell polarization and subcellular organization, thereby affecting cell fate determination and tissue architecture. In particular, when progenitor cells divide asymmetrically along an anterior-posterior or apical-basal axis, MTs must coordinate the position of the mitotic spindle with the site of cell division to ensure normal distribution of cell fate determinants and equal sequestration of genetic material into the two daughter cells. Emerging data from diverse model systems have led to the prevailing view that, during mitotic spindle positioning, polarity cues at the cell cortex signal for the recruitment of NuMA and the minus-end directed MT motor cytoplasmic dynein.1 The NuMA/dynein complex is believed to connect, in turn, to the mitotic spindle via astral MTs, thus aligning and tethering the spindle, but how this connection is achieved faithfully is unclear. Do astral MTs need to search for and then capture cortical NuMA/dynein? How does dynein capture the astral MTs emanating from the correct spindle pole? Recently, using the classical model of asymmetric cell division—budding yeast S. cerevisiae—we successfully demonstrated that astral MTs assume an active role in cortical dynein targeting, in that astral MTs utilize their distal plus ends to deliver dynein to the daughter cell cortex, the site where dynein activity is needed to perform its spindle alignment function. This observation introduced the novel idea that, during mitotic spindle orientation processes, polarity cues at the cell cortex may actually signal to prime the cortical receptors for MT-dependent dynein delivery. This model is consistent with the observation that dynein/dynactin accumulate prominently at the astral MT plus ends during metaphase in a wide range of cultured mammalian cells. PMID:22754610

Slow-oscillatory Transcranial Direct Current Stimulation Modulates Memory in Temporal Lobe Epilepsy by Altering Sleep Spindle Generators: A Possible Rehabilitation Tool.

PubMed

Del Felice, Alessandra; Magalini, Alessandra; Masiero, Stefano

2015-01-01

Temporal lobe epilepsy (TLE) is often associated with memory deficits. Given the putative role for sleep spindles memory consolidation, spindle generators skewed toward the affected lobe in TLE subjects may be a neurophysiological marker of defective memory. Slow-oscillatory transcranial direct current stimulation (sotDCS) during slow waves sleep (SWS) has previously been shown to enhance sleep-dependent memory consolidation by increasing slow-wave sleep and modulating sleep spindles. To test if anodal sotDCS over the affected TL prior to a nap affects sleep spindles and whether this improves memory consolidation. Randomized controlled cross-over study. 12 people with TLE underwent sotDCS (0.75 Hz; 0-250 μV, 30 min) or sham before daytime nap. Declarative verbal and visuospatial learning were tested. Fast and slow spindle signals were recorded by 256-channel EEG during sleep. In both study arms, electrical source imaging (ESI) localized cortical generators. Neuropsychological data were analyzed with general linear model statistics or the Kruskal-Wallis test (P or Z < 0.05), and neurophysiological data tested with the Mann-Whitney t test and binomial distribution test (P or Z < 0.05). An improvement in declarative (P = 0.05) and visuospatial memory performance (P = 0.048) emerged after sotDCS. SotDCS increased slow spindle generators current density (Z = 0.001), with a shift to the anterior cortical areas. Anodal sotDCS over the affected temporal lobe improves declarative and visuospatial memory performance by modulating slow sleep spindles cortical source generators. SotDCS appears a promising tool for memory rehabilitation in people with TLE. Copyright © 2015 Elsevier Inc. All rights reserved.

Enhanced polarizing microscopy as a new tool in aneuploidy research in oocytes.

PubMed

Shen, Ying; Betzendahl, Ilse; Tinneberg, Hans-Rudolf; Eichenlaub-Ritter, Ursula

2008-03-12

Chromosomal non-disjunction in female meiosis gives rise to reduced fertility and trisomy in humans. Human oocytes, especially from aged women, appear especially susceptible to non-disjunction. The oocyte spindle is crucial for high fidelity of chromosome segregation at meiotic divisions, and alterations in spindle morphology are therefore indicators of adverse conditions during oocyte development that may result in meiotic aneuploidy. In the past, oocytes had to be fixed for spindle analysis, precluding direct non-invasive identification of aneugens and adverse maturation conditions that affect spindle integrity and chromosome behaviour. Aneuploidy research for detection of spindle aberrations was therefore mainly focused on in vivo or in vitro exposed, fixed animal oocytes or cytogenetic analysis of spread oocytes. Orientation independent enhanced polarizing microscopy with nearly circularly polarized light and electronically controlled liquid crystal compensator optics is a new tool to study spindle morphology non-invasively in vivo for qualitative as well as quantitative analysis. Image generation by polarization microscopy depends on the intrinsic optical properties of the spindle with its paracrystalline microtubule lattice. When polarized light passes through such a lattice it induces a splitting of the beam and shift in the plane of vibration and retardation of light (termed birefringence and retardance). Studies of animal oocytes and follicle-cell denuded human oocytes fertilized by intracytoplasmic sperm injection for assisted conception have demonstrated the safety and efficacy of enhanced polarization microscopy. The method can be employed in aneuploidy research for non-invasive dose-response studies to detect spindle aberrations, for instance, in combination with cytogenetic analysis. Due to the non-invasive nature of the technique it may be employed in routine analysis of human oocytes to assess risks by lifestyle factors, and occupational and adverse environmental exposures.

Modulation of jaw muscle spindle afferent activity following intramuscular injections with hypertonic saline.

PubMed

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.

Evaluating and Improving Automatic Sleep Spindle Detection by Using Multi-Objective Evolutionary Algorithms

PubMed Central

Liu, Min-Yin; Huang, Adam; Huang, Norden E.

2017-01-01

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. PMID:28572762

How does uncertainty shape patient experience in advanced illness? A secondary analysis of qualitative data.

PubMed

Etkind, Simon Noah; Bristowe, Katherine; Bailey, Katharine; Selman, Lucy Ellen; Murtagh, Fliss Em

2017-02-01

Uncertainty is common in advanced illness but is infrequently studied in this context. If poorly addressed, uncertainty can lead to adverse patient outcomes. We aimed to understand patient experiences of uncertainty in advanced illness and develop a typology of patients' responses and preferences to inform practice. Secondary analysis of qualitative interview transcripts. Studies were assessed for inclusion and interviews were sampled using maximum-variation sampling. Analysis used a thematic approach with 10% of coding cross-checked to enhance reliability. Qualitative interviews from six studies including patients with heart failure, chronic obstructive pulmonary disease, renal disease, cancer and liver failure. A total of 30 transcripts were analysed. Median age was 75 (range, 43-95), 12 patients were women. The impact of uncertainty was frequently discussed: the main related themes were engagement with illness, information needs, patient priorities and the period of time that patients mainly focused their attention on (temporal focus). A typology of patient responses to uncertainty was developed from these themes. Uncertainty influences patient experience in advanced illness through affecting patients' information needs, preferences and future priorities for care. Our typology aids understanding of how patients with advanced illness respond to uncertainty. Assessment of these three factors may be a useful starting point to guide clinical assessment and shared decision making.

F-actin mechanics control spindle centring in the mouse zygote

NASA Astrophysics Data System (ADS)

Chaigne, Agathe; Campillo, Clément; Voituriez, Raphaël; Gov, Nir S.; Sykes, Cécile; Verlhac, Marie-Hélène; Terret, Marie-Emilie

2016-01-01

Mitotic spindle position relies on interactions between astral microtubules nucleated by centrosomes and a rigid cortex. Some cells, such as mouse oocytes, do not possess centrosomes and astral microtubules. These cells rely only on actin and on a soft cortex to position their spindle off-centre and undergo asymmetric divisions. While the first mouse embryonic division also occurs in the absence of centrosomes, it is symmetric and not much is known on how the spindle is positioned at the exact cell centre. Using interdisciplinary approaches, we demonstrate that zygotic spindle positioning follows a three-step process: (1) coarse centring of pronuclei relying on the dynamics of an F-actin/Myosin-Vb meshwork; (2) fine centring of the metaphase plate depending on a high cortical tension; (3) passive maintenance at the cell centre. Altogether, we show that F-actin-dependent mechanics operate the switch between asymmetric to symmetric division required at the oocyte to embryo transition.

Is cohesin required for spindle-pole-body/centrosome cohesion?

PubMed Central

Jin, Hui; Avey, Martin

2012-01-01

Centrosomes are microtubule-organizing centers that nucleate spindle microtubules during cell division. In budding yeast, the centrosome, often referred to as the spindle pole body, shares structural components with the centriole, the central core of the animal centrosome. The parental centrosome is duplicated when DNA replication takes place. Like sister chromatids tethered together by cohesin, duplicated centrosomes are linked and then separate to form the bipolar spindle necessary for chromosome segregation. Recent studies have shown that cohesin is also localized to the animal centrosome and is perhaps directly involved in engaging paired centrioles. Here we discuss the potential role of cohesin in mediating spindle-pole-body cohesion in the context of yeast meiosis. We propose that the coordination of chromosome segregation with centrosome cohesion and duplication is mediated by the antagonistic interaction between the Aurora kinase and the Polo kinase and that the role of cohesin in centrosome regulation appears to be indirect in budding yeast. PMID:22482005

Declarative memory performance is associated with the number of sleep spindles in elderly women.

PubMed

Seeck-Hirschner, Mareen; Baier, Paul Christian; Weinhold, Sara Lena; Dittmar, Manuela; Heiermann, Steffanie; Aldenhoff, Josef B; Göder, Robert

2012-09-01

Recent evidence suggests that the sleep-dependent consolidation of declarative memory relies on the nonrapid eye movement rather than the rapid eye movement phase of sleep. In addition, it is known that aging is accompanied by changes in sleep and memory processes. Hence, the purpose of this study was to investigate the overnight consolidation of declarative memory in healthy elderly women. Sleep laboratory of University. Nineteen healthy elderly women (age range: 61-74 years). We used laboratory-based measures of sleep. To test declarative memory, the Rey-Osterrieth Complex Figure Test was performed. Declarative memory performance in elderly women was associated with Stage 2 sleep spindle density. Women characterized by high memory performance exhibited significantly higher numbers of sleep spindles and higher spindle density compared with women with generally low memory performance. The data strongly support theories suggesting a link between sleep spindle activity and declarative memory consolidation.

Automatic Rail Extraction and Celarance Check with a Point Cloud Captured by Mls in a Railway

NASA Astrophysics Data System (ADS)

Niina, Y.; Honma, R.; Honma, Y.; Kondo, K.; Tsuji, K.; Hiramatsu, T.; Oketani, E.

2018-05-01

Recently, MLS (Mobile Laser Scanning) has been successfully used in a road maintenance. In this paper, we present the application of MLS for the inspection of clearance along railway tracks of West Japan Railway Company. Point clouds around the track are captured by MLS mounted on a bogie and rail position can be determined by matching the shape of the ideal rail head with respect to the point cloud by ICP algorithm. A clearance check is executed automatically with virtual clearance model laid along the extracted rail. As a result of evaluation, the accuracy of extracting rail positions is less than 3 mm. With respect to the automatic clearance check, the objects inside the clearance and the ones related to a contact line is successfully detected by visual confirmation.

Spinal spindle cell haemangioma: an atypical location.

PubMed

Talan-Hranilović, J; Vucić, M; Sajko, T; Bedek, D; Tomić, K; Lupret, V

2007-03-01

We present a case of the 31-year-old male patient who complained of weakness in both legs and progressed slowly. Neuroimagine of the thoracic spine showed an intraspinal, extradural mass lesion, measuring 5.3 x 1.2 cm at the Th1-Th3 level. Histologically the lesion was a spindle cell haemangioma composed of dilated vascular spaces and a proliferation of bland appearing interspersed spindle cells. Immunohistochemical analysis was diffusely positive for VIM, SMA and focally for CD34. This lesion is uncommon and shows a predilection for distal extremities. Spindle cell haemangioma within the spine has not been previously reported in the literature.

Cdc2-mediated phosphorylation of Kid controls its distribution to spindle and chromosomes

PubMed Central

Ohsugi, Miho; Tokai-Nishizumi, Noriko; Shiroguchi, Katsuyuki; Toyoshima, Yoko Y.; Inoue, Jun-ichiro; Yamamoto, Tadashi

2003-01-01

The chromokinesin Kid is important in chromosome alignment at the metaphase plate. Here, we report that Kid function is regulated by phosphorylation. We identify Ser427 and Thr463 as M phase-specific phosphorylation sites and Cdc2–cyclin B as a Thr463 kinase. Kid with a Thr463 to alanine mutation fails to be localized on chromosomes and is only detected along spindles, although it retains the ability to bind DNA or chromosomes. Localization of rigor-type mutant Kid, which shows nucleotide-independent microtubule association, is also confined to the spindle, implying that strong association of Kid with the spindle can sequester it from chromosomes. T463A substitution in DNA-binding domain-truncated Kid consistently enhances its spindle localization. At physiological ionic strength, unphosphorylated Kid shows ATP-independent microtubule association, whereas Thr463-phosphorylated Kid shows ATP dependency. Moreover, the stalk region of unphosphorylated Kid interacts with microtubules and the interaction is weakened when Thr463 is phosphorylated. Our data suggest that phosphorylation on Thr463 of Kid downregulates its affinity for microtubules to ensure reversible association with spindles, allowing Kid to bind chromosomes and exhibit its function. PMID:12727876

The chromokinesin Kid is necessary for chromosome arm orientation and oscillation, but not congression, on mitotic spindles

PubMed Central

Levesque, Aime A.; Compton, Duane A.

2001-01-01

Chromokinesins have been postulated to provide the polar ejection force needed for chromosome congression during mitosis. We have evaluated that possibility by monitoring chromosome movement in vertebrate-cultured cells using time-lapse differential interference contrast microscopy after microinjection with antibodies specific for the chromokinesin Kid. 17.5% of cells injected with Kid-specific antibodies have one or more chromosomes that remain closely opposed to a spindle pole and fail to enter anaphase. In contrast, 82.5% of injected cells align chromosomes in metaphase, progress to anaphase, and display chromosome velocities not significantly different from control cells. However, injected cells lack chromosome oscillations, and chromosome orientation is atypical because chromosome arms extend toward spindle poles during both congression and metaphase. Furthermore, chromosomes cluster into a mass and fail to oscillate when Kid is perturbed in cells containing monopolar spindles. These data indicate that Kid generates the polar ejection force that pushes chromosome arms away from spindle poles in vertebrate-cultured cells. This force increases the efficiency with which chromosomes make bipolar spindle attachments and regulates kinetochore activities necessary for chromosome oscillation, but is not essential for chromosome congression. PMID:11564754

Upregulated Op18/stathmin activity causes chromosomal instability through a mechanism that evades the spindle assembly checkpoint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holmfeldt, Per; Sellin, Mikael E.; Gullberg, Martin, E-mail: Martin.Gullberg@molbiol.umu.se

2010-07-15

Op18/stathmin (Op18) is a microtubule-destabilizing protein that is phosphorylation-inactivated during mitosis and its normal function is to govern tubulin subunit partitioning during interphase. Human tumors frequently overexpress Op18 and a tumor-associated Q18{yields}E mutation has been identified that confers hyperactivity, destabilizes spindle microtubules, and causes mitotic aberrancies, polyploidization, and chromosome loss in K562 leukemia cells. Here we determined whether wild-type and mutant Op18 have the potential to cause chromosomal instability by some means other than interference with spindle assembly, and thereby bypassing the spindle assembly checkpoint. Our approach was based on Op18 derivatives with distinct temporal order of activity during mitosis,more » conferred either by differential phosphorylation inactivation or by anaphase-specific degradation through fusion with the destruction box of cyclin B1. We present evidence that excessive Op18 activity generates chromosomal instability through interference occurring subsequent to the metaphase-to-anaphase transition, which reduces the fidelity of chromosome segregation to spindle poles during anaphase. Similar to uncorrected merotelic attachment, this mechanism evades detection by the spindle assembly checkpoint and thus provides an additional route to chromosomal instability.« less

[The quality of medication orders--can it be improved?].

PubMed

Vaknin, Ofra; Wingart-Emerel, Efrat; Stern, Zvi

2003-07-01

Medication errors are a common cause of morbidity and mortality among patients. Medication administration in hospitals is a complicated procedure with the possibility of error at each step. Errors are most commonly found at the prescription and transcription stages, although it is known that most errors can easily be avoided through strict adherence to standardized procedure guidelines. In examination of medication errors reported in the hospital in the year 2000, we found that 38% reported to have resulted from transcription errors. In the year 2001, the hospital initiated a program designed to identify faulty process of orders in an effort to improve the quality and effectiveness of the medication administration process. As part of this program, it was decided to check and evaluate the quality of the written doctor's orders and the transcription of those orders to the nursing cadre, in various hospital units. The study was conducted using a questionnaire which checked compliance to hospital standards with regard to the medication administration process, as applied to 6 units over the course of 8 weeks. Results of the survey showed poor compliance to guidelines on the part of doctors and nurses. Only 18% of doctors' orders in the study and 37% of the nurses' transcriptions were written according to standards. The Emergency Department showed an even lower compliance with only 3% of doctors' orders and 25% of nurses' transcriptions complying to standards. As a result of this study, it was decided to initiate an intensive in-service teaching course to refresh the staff's knowledge of medication administration guidelines. In the future it is recommended that hand-written orders be replaced by computerized orders in an effort to limit the chance of error.

RED, a Spindle Pole-associated Protein, Is Required for Kinetochore Localization of MAD1, Mitotic Progression, and Activation of the Spindle Assembly Checkpoint*

PubMed Central

Yeh, Pei-Chi; Yeh, Chang-Ching; Chen, Yi-Cheng; Juang, Yue-Li

2012-01-01

The spindle assembly checkpoint (SAC) is essential for ensuring the proper attachment of kinetochores to the spindle and, thus, the precise separation of paired sister chromatids during mitosis. The SAC proteins are recruited to the unattached kinetochores for activation of the SAC in prometaphase. However, it has been less studied whether activation of the SAC also requires the proteins that do not localize to the kinetochores. Here, we show that the nuclear protein RED, also called IK, a down-regulator of human leukocyte antigen (HLA) II, interacts with the human SAC protein MAD1. Two RED-interacting regions identified in MAD1 are from amino acid residues 301–340 and 439–480, designated as MAD1(301–340) and MAD1(439–480), respectively. Our observations reveal that RED is a spindle pole-associated protein that colocalizes with MAD1 at the spindle poles in metaphase and anaphase. Depletion of RED can cause a shorter mitotic timing, a failure in the kinetochore localization of MAD1 in prometaphase, and a defect in the SAC. Furthermore, the RED-interacting peptides MAD1(301–340) and MAD1(439–480), fused to enhanced green fluorescence protein, can colocalize with RED at the spindle poles in prometaphase, and their expression can abrogate the SAC. Taken together, we conclude that RED is required for kinetochore localization of MAD1, mitotic progression, and activation of the SAC. PMID:22351768

Cyclic adenosine monophosphate levels and the function of skin microvascular endothelial cells.

PubMed

Tuder, R M; Karasek, M A; Bensch, K G

1990-02-01

The maintenance of the normal epithelioid morphology of human dermal microvascular endothelial cells (MEC) grown in vitro depends strongly on the presence of factors that increase intracellular levels of cyclic AMP. Complete removal of dibutyryl cAMP and isobutylmethylxanthine (IMX) from the growth medium results in a progressive transition from an epithelioid to a spindle-shaped cell line. This transition cannot be reversed by the readdition of dibutyryl cAMP and IMX to the growth medium or by addition of agonists that increase cAMP levels. Spindle-shaped MEC lose the ability to express Factor VIII rAG and DR antigens and to bind peripheral blood mononuclear leukocyte (PBML). Ultrastructural analyses of transitional cells and spindle-shaped cells show decreased numbers of Weibel-Palade bodies in transitional cells and their complete absence in spindle-shaped cells. Interferon-gamma alters several functional properties of both epithelioid and spindle-shaped cells. In the absence of dibutyryl cAMP it accelerates the transition from epithelial to spindle-shaped cells, whereas in the presence of cyclic AMP interferon-gamma increases the binding of PBMLs to both epithelioid and spindle-shaped MEC and the endocytic activity of the endothelial cells. These results suggest that cyclic AMP is an important second messenger in the maintenance of several key functions of microvascular endothelial cells. Factors that influence the levels of this messenger in vivo can be expected to influence the angiogenic and immunologic functions of the microvasculature.

The Development of a Monitoring System Using a Wireless and Powerless Sensing Node Deployed Inside a Spindle

PubMed Central

Chang, Liang-Cheng; Lee, Da-Sheng

2012-01-01

Installation of a Wireless and Powerless Sensing Node (WPSN) inside a spindle enables the direct transmission of monitoring signals through a metal case of a certain thickness instead of the traditional method of using connecting cables. Thus, the node can be conveniently installed inside motors to measure various operational parameters. This study extends this earlier finding by applying this advantage to the monitoring of spindle systems. After over 2 years of system observation and optimization, the system has been verified to be superior to traditional methods. The innovation of fault diagnosis in this study includes the unmatched assembly dimensions of the spindle system, the unbalanced system, and bearing damage. The results of the experiment demonstrate that the WPSN provides a desirable signal-to-noise ratio (SNR) in all three of the simulated faults, with the difference of SNR reaching a maximum of 8.6 dB. Following multiple repetitions of the three experiment types, 80% of the faults were diagnosed when the spindle revolved at 4,000 rpm, significantly higher than the 30% fault recognition rate of traditional methods. The experimental results of monitoring of the spindle production line indicated that monitoring using the WPSN encounters less interference from noise compared to that of traditional methods. Therefore, this study has successfully developed a prototype concept into a well-developed monitoring system, and the monitoring can be implemented in a spindle production line or real-time monitoring of machine tools. PMID:22368456

The development of a monitoring system using a Wireless and Powerless Sensing Node deployed inside a spindle.

PubMed

Chang, Liang-Cheng; Lee, Da-Sheng

2012-01-01

Installation of a Wireless and Powerless Sensing Node (WPSN) inside a spindle enables the direct transmission of monitoring signals through a metal case of a certain thickness instead of the traditional method of using connecting cables. Thus, the node can be conveniently installed inside motors to measure various operational parameters. This study extends this earlier finding by applying this advantage to the monitoring of spindle systems. After over 2 years of system observation and optimization, the system has been verified to be superior to traditional methods. The innovation of fault diagnosis in this study includes the unmatched assembly dimensions of the spindle system, the unbalanced system, and bearing damage. The results of the experiment demonstrate that the WPSN provides a desirable signal-to-noise ratio (SNR) in all three of the simulated faults, with the difference of SNR reaching a maximum of 8.6 dB. Following multiple repetitions of the three experiment types, 80% of the faults were diagnosed when the spindle revolved at 4,000 rpm, significantly higher than the 30% fault recognition rate of traditional methods. The experimental results of monitoring of the spindle production line indicated that monitoring using the WPSN encounters less interference from noise compared to that of traditional methods. Therefore, this study has successfully developed a prototype concept into a well-developed monitoring system, and the monitoring can be implemented in a spindle production line or real-time monitoring of machine tools.

The Effect of Functional Mandibular Shift on the Muscle Spindle Systems in Head-Neck Muscles and the Related Neurotransmitter Histamine.

PubMed

Du, Bing-Li; Li, Jiang-Ning; Guo, Hong-Ming; Li, Song; Liu, Biao

2017-09-01

The aim of this study is to explore the effects of abnormal occlusion and functional recovery caused by functional mandible deviation on the head and neck muscles and muscle spindle sensory-motor system by electrophysiological response and endogenous monoamine neurotransmitters' distribution in the nucleus of the spinal tract. Seven-week-old male Wistar rats were randomly divided into 7 groups: normal control group, 2W experimental control group, 2W functional mandible deviation group, 2W functional mandible deviation recovery group, 4W experimental control group, 4W functional mandible deviation group, 4W functional mandible deviation recovery group. Chewing muscles, digastric muscle, splenius, and trapezius muscle spindles electrophysiological response activities at the opening and closing state were recorded. And then the chewing muscles, digastric, splenius, trapezius, and neck trigeminal nucleus were taken for histidine decarboxylase (HDC) detection by high performance liquid chromatography (HPLC), immunofluorescence, and reverse-transcription polymerase chain reaction (RT-PCR). Histamine receptor proteins in the neck nucleus of the spinal tract were also examined by immunofluorescence and RT-PCR. Electromyography activity of chewing muscles, digastric, and splenius muscle was significantly asymmetric; the abnormal muscle electromyography activity was mainly detected at the ipsilateral side. After functional mandibular deviation, muscle sensitivity on the ipsilateral sides of the chewing muscle and splenius decreased, muscle excitement weakened, modulation depth decreased, and the muscle spindle afferent impulses of excitation transmission speed slowed down. Changes for digastric muscle electrical activity were contrary. The functions recovered at different extents after removing the deflector. However, trapezius in all the experimental groups and recovery groups exhibited bilateral symmetry electrophysiological responses, and no significant difference compared with the control group. After functional mandibular deviation, HDC protein and messenger ribonucleic acid (mRNA) levels on the ipsilateral sides of the chewing muscle and splenius increased significantly. HDC level changes for digastric muscle were contrary. After the removal of the mandibular position deflector, HDC protein and mRNA levels decreased on the ipsilateral sides of the chewing muscle and splenius while they increased in the digastric muscle. The difference of histamine decarboxylase content in the bilateral trapezius in each experimental group was small. After functional mandibular deviation, the temporomandibular joint mechanical receptors not only caused the fusimotor fiber hypoallergenic fatigue slow response on the ipsilateral sides of splenius, but also increased the injury neurotransmitter histamine release. The authors' results further support the opinion that the temporomandibular joint receptors may be involved in the mechanical theory of the head and neck muscles nervous system regulation.

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

PubMed

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 →Cortex 3 projecting paths, respectively. Overall, those results imply that RE possesses the pacemaker function in controlling SWDs and spindling oscillations, which computationally provide causal support for the involvement of RE in absence seizures and sleep spindles.

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

NASA Astrophysics Data System (ADS)

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 → Cortex 3 projecting paths, respectively. Overall, those results imply that RE possesses the pacemaker function in controlling SWDs and spindling oscillations, which computationally provide causal support for the involvement of RE in absence seizures and sleep spindles.

Autonomous Environment-Monitoring Networks

NASA Technical Reports Server (NTRS)

Hand, Charles

2004-01-01

Autonomous environment-monitoring networks (AEMNs) are artificial neural networks that are specialized for recognizing familiarity and, conversely, novelty. Like a biological neural network, an AEMN receives a constant stream of inputs. For purposes of computational implementation, the inputs are vector representations of the information of interest. As long as the most recent input vector is similar to the previous input vectors, no action is taken. Action is taken only when a novel vector is encountered. Whether a given input vector is regarded as novel depends on the previous vectors; hence, the same input vector could be regarded as familiar or novel, depending on the context of previous input vectors. AEMNs have been proposed as means to enable exploratory robots on remote planets to recognize novel features that could merit closer scientific attention. AEMNs could also be useful for processing data from medical instrumentation for automated monitoring or diagnosis. The primary substructure of an AEMN is called a spindle. In its simplest form, a spindle consists of a central vector (C), a scalar (r), and algorithms for changing C and r. The vector C is constructed from all the vectors in a given continuous stream of inputs, such that it is minimally distant from those vectors. The scalar r is the distance between C and the most remote vector in the same set. The construction of a spindle involves four vital parameters: setup size, spindle-population size, and the radii of two novelty boundaries. The setup size is the number of vectors that are taken into account before computing C. The spindle-population size is the total number of input vectors used in constructing the spindle counting both those that arrive before and those that arrive after the computation of C. The novelty-boundary radii are distances from C that partition the neighborhood around C into three concentric regions (see Figure 1). During construction of the spindle, the changing spindle radius is denoted by h. It is the final value of h, reached before beginning construction on the next spindle, that is denoted by r. During construction of a spindle, if a new vector falls between C and the inner boundary, the vector is regarded as completely familiar and no action is taken. If the new vector falls into the region between the inner and outer boundaries, it is considered unusual enough to warrant the adjustment of C and r by use of the aforementioned algorithms, but not unusual enough to be considered novel. If a vector falls outside the outer boundary, it is considered novel, in which case one of several appropriate responses could be initiation of construction of a new spindle.

Locking mechanism for indexing device

DOEpatents

Lindemeyer, Carl W.

1984-01-01

Disclosed is a locking mechanism for an indexing spindle. A conventional r gear having outwardly extending teeth is affixed to the spindle. Also included is a rotatably mounted camshaft whose axis is arranged in skewed relationship with the axis of the spindle. A disk-like wedge having opposing camming surfaces is eccentrically mounted on the camshaft. As the camshaft is rotated, the camming surfaces of the disc-like member are interposed between adjacent gear teeth with a wiping action that wedges the disc-like member between the gear teeth. A zero backlash engagement between disc-like member and gear results, with the engagement having a high mechanical advantage so as to effectively lock the spindle against bidirectional rotation.

Single-bunch synchrotron shutter

DOEpatents

Norris, James R.; Tang, Jau-Huei; Chen, Lin; Thurnauer, Marion

1993-01-01

An apparatus for selecting a single synchrotron pulse from the millions of pulses provided per second from a synchrotron source includes a rotating spindle located in the path of the synchrotron pulses. The spindle has multiple faces of a highly reflective surface, and having a frequency of rotation f. A shutter is spaced from the spindle by a radius r, and has an open position and a closed position. The pulses from the synchrotron are reflected off the spindle to the shutter such that the speed s of the pulses at the shutter is governed by: s=4.times..pi..times.r.times.f. such that a single pulse is selected for transmission through an open position of the shutter.

Methods for making radially anisotropic thin-film magnetic torroidal cores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiu, Jizheng; Sullivan, Charles R.

2017-05-23

A method of forming a radially anisotropic toroidal magnetic core includes providing apparatus having a first magnet for providing a radial magnetic field extending across a cavity from an axial spindle to a surrounding second magnetic element, placing a substrate in the cavity, the substrate having a hole fitting around the head of the spindle; and sputter-depositing a film of ferromagnetic material onto the substrate. In an embodiment, the spindle is magnetically coupled to a first pole of the first magnet, the second magnetic element is coupled to a second pole of the first magnet, and a thermally conductive, nonmagnetic,more » insert separates the spindle and the second magnetic element.« less

Preferential Ascus Discharge during Cross Maturation in SORDARIA BREVICOLLIS

PubMed Central

MacDonald, D. J.; Bond, D. J.

1974-01-01

Crosses involving spore color mutants of Sordaria brevicollis all showed a decline in the frequency of second division asymmetric asci (2:2:2:2's) as the cross matured. This decline was due to the preferential maturation and/or discharge of these asci. The proportion of spindle overlap and recombinational asci within the group did not change as shown by ascus dissection. The preferential discharge was also found to occur in two-point crosses where the asci did not contain wild-type spores. PMID:4822469

Preferential ascus discharge during cross maturation in Sordaria brevicollis.

PubMed

MacDonald, D J; Bond, D J

1974-02-01

Crosses involving spore color mutants of Sordaria brevicollis all showed a decline in the frequency of second division asymmetric asci (2:2:2:2's) as the cross matured. This decline was due to the preferential maturation and/or discharge of these asci. The proportion of spindle overlap and recombinational asci within the group did not change as shown by ascus dissection. The preferential discharge was also found to occur in two-point crosses where the asci did not contain wild-type spores.

Cell cycle gene expression networks discovered using systems biology: Significance in carcinogenesis

PubMed Central

Scott, RE; Ghule, PN; Stein, JL; Stein, GS

2015-01-01

The early stages of carcinogenesis are linked to defects in the cell cycle. A series of cell cycle checkpoints are involved in this process. The G1/S checkpoint that serves to integrate the control of cell proliferation and differentiation is linked to carcinogenesis and the mitotic spindle checkpoint with the development of chromosomal instability. This paper presents the outcome of systems biology studies designed to evaluate if networks of covariate cell cycle gene transcripts exist in proliferative mammalian tissues including mice, rats and humans. The GeneNetwork website that contains numerous gene expression datasets from different species, sexes and tissues represents the foundational resource for these studies (www.genenetwork.org). In addition, WebGestalt, a gene ontology tool, facilitated the identification of expression networks of genes that co-vary with key cell cycle targets, especially Cdc20 and Plk1 (www.bioinfo.vanderbilt.edu/webgestalt). Cell cycle expression networks of such covariate mRNAs exist in multiple proliferative tissues including liver, lung, pituitary, adipose and lymphoid tissues among others but not in brain or retina that have low proliferative potential. Sixty-three covariate cell cycle gene transcripts (mRNAs) compose the average cell cycle network with p = e−13 to e−36. Cell cycle expression networks show species, sex and tissue variability and they are enriched in mRNA transcripts associated with mitosis many of which are associated with chromosomal instability. PMID:25808367

Meioc maintains an extended meiotic prophase I in mice

PubMed Central

Soh, Y. Q. Shirleen; Godfrey, Alexander K.; de Rooij, Dirk G.; Page, David C.

2017-01-01

The meiosis-specific chromosomal events of homolog pairing, synapsis, and recombination occur over an extended meiotic prophase I that is many times longer than prophase of mitosis. Here we show that, in mice, maintenance of an extended meiotic prophase I requires the gene Meioc, a germ-cell specific factor conserved in most metazoans. In mice, Meioc is expressed in male and female germ cells upon initiation of and throughout meiotic prophase I. Mouse germ cells lacking Meioc initiate meiosis: they undergo pre-meiotic DNA replication, they express proteins involved in synapsis and recombination, and a subset of cells progress as far as the zygotene stage of prophase I. However, cells in early meiotic prophase—as early as the preleptotene stage—proceed to condense their chromosomes and assemble a spindle, as if having progressed to metaphase. Meioc-deficient spermatocytes that have initiated synapsis mis-express CYCLIN A2, which is normally expressed in mitotic spermatogonia, suggesting a failure to properly transition to a meiotic cell cycle program. MEIOC interacts with YTHDC2, and the two proteins pull-down an overlapping set of mitosis-associated transcripts. We conclude that when the meiotic chromosomal program is initiated, Meioc is simultaneously induced so as to extend meiotic prophase. Specifically, MEIOC, together with YTHDC2, promotes a meiotic (as opposed to mitotic) cell cycle program via post-transcriptional control of their target transcripts. PMID:28380054

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

PubMed

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.

Mio depletion links mTOR regulation to Aurora A and Plk1 activation at mitotic centrosomes

PubMed Central

Trinkle-Mulcahy, Laura; Porter, Michael; Jeyaprakash, A. Arockia

2015-01-01

Coordination of cell growth and proliferation in response to nutrient supply is mediated by mammalian target of rapamycin (mTOR) signaling. In this study, we report that Mio, a highly conserved member of the SEACAT/GATOR2 complex necessary for the activation of mTORC1 kinase, plays a critical role in mitotic spindle formation and subsequent chromosome segregation by regulating the proper concentration of active key mitotic kinases Plk1 and Aurora A at centrosomes and spindle poles. Mio-depleted cells showed reduced activation of Plk1 and Aurora A kinase at spindle poles and an impaired localization of MCAK and HURP, two key regulators of mitotic spindle formation and known substrates of Aurora A kinase, resulting in spindle assembly and cytokinesis defects. Our results indicate that a major function of Mio in mitosis is to regulate the activation/deactivation of Plk1 and Aurora A, possibly by linking them to mTOR signaling in a pathway to promote faithful mitotic progression. PMID:26124292

Spindle Cell Rhabdomyosarcoma of Bone with FUS-TFCP2 Fusion: Confirmation of a Very Recently Described Rhabdomyosarcoma Subtype.

PubMed

Dashti, Nooshin K; Wehrs, Rebecca N; Thomas, Brittany C; Nair, Asha; Davila, Jaime; Buckner, Jan C; Martinez, Anthony P; Sukov, William R; Halling, Kevin C; Howe, Benjamin M; Folpe, Andrew L

2018-05-14

Rhabdomyosarcomas of bone are extremely rare, with fewer than 10 reported cases. A very rare subtype of spindle cell/sclerosing rhabdomyosarcoma harboring a FUS-TFCP2 fusion and involving both soft tissue and bone locations has very recently been reported. We report only the fourth case of this unusual, clinically aggressive rhabdomyosarcoma. A previously-well 72-year old male presented with a destructive lesion of the mandible. Morphological and immunohistochemical study of a needle biopsy and the subsequent resection showed a spindle cell rhabdomyosarcoma. RNA-seq, RT-PCR and FISH confirmed the presence of the FUS-TFCP2 fusion. Spindle cell rhabdomyosarcomas carrying the FUS-TFCP2 fusion are very rare rhabdomyosarcoma variants with osseous predilection. The classification and differential diagnosis of this unusual molecular variant of spindle cell/ sclerosing rhabdomyosarcoma are discussed. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Sleep spindles: a physiological marker of age-related changes in gray matter in brain regions supporting motor skill memory consolidation.

PubMed

Fogel, Stuart; Vien, Catherine; Karni, Avi; Benali, Habib; Carrier, Julie; Doyon, Julien

2017-01-01

Sleep is necessary for the optimal consolidation of procedural learning, and in particular, for motor sequential skills. Motor sequence learning remains intact with age, but sleep-dependent consolidation is impaired, suggesting that memory deficits for procedural skills are specifically impacted by age-related changes in sleep. Age-related changes in spindles may be responsible for impaired motor sequence learning consolidation, but the morphological basis for this deficit is unknown. Here, we found that gray matter in the hippocampus and cerebellum was positively correlated with both sleep spindles and offline improvements in performance in young participants but not in older participants. These results suggest that age-related changes in gray matter in the hippocampus relate to spindles and may underlie age-related deficits in sleep-related motor sequence memory consolidation. In this way, spindles can serve as a biological marker for structural brain changes and the related memory deficits in older adults. Copyright © 2016 Elsevier Inc. All rights reserved.

Mitotic Chromosome Biorientation in Fission Yeast Is Enhanced by Dynein and a Minus-end–directed, Kinesin-like Protein

PubMed Central

Spiridonov, Ilia S.; McIntosh, J. Richard

2007-01-01

Chromosome biorientation, the attachment of sister kinetochores to sister spindle poles, is vitally important for accurate chromosome segregation. We have studied this process by following the congression of pole-proximal kinetochores and their subsequent anaphase segregation in fission yeast cells that carry deletions in any or all of this organism's minus end–directed, microtubule-dependent motors: two related kinesin 14s (Pkl1p and Klp2p) and dynein. None of these deletions abolished biorientation, but fewer chromosomes segregated normally without Pkl1p, and to a lesser degree without dynein, than in wild-type cells. In the absence of Pkl1p, which normally localizes to the spindle and its poles, the checkpoint that monitors chromosome biorientation was defective, leading to frequent precocious anaphase. Ultrastructural analysis of mutant mitotic spindles suggests that Pkl1p contributes to error-free biorientation by promoting normal spindle pole organization, whereas dynein helps to anchor a focused bundle of spindle microtubules at the pole. PMID:17409356

Theory of meiotic spindle assembly

NASA Astrophysics Data System (ADS)

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.

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

PubMed Central

Li, Sheng; Yao, Xinhua; Fu, Jianzhong

2014-01-01

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. PMID:25033189

Identified Cellular Correlates of Neocortical Ripple and High-Gamma Oscillations during Spindles of Natural Sleep.

PubMed

Averkin, Robert G; Szemenyei, Viktor; Bordé, Sándor; Tamás, Gábor

2016-11-23

Ultra-high-frequency network events in the hippocampus are instrumental in a dialogue with the neocortex during memory formation, but the existence of transient ∼200 Hz network events in the neocortex is not clear. Our recordings from neocortical layer II/III of freely behaving rats revealed field potential events at ripple and high-gamma frequencies repeatedly occurring at troughs of spindle oscillations during sleep. Juxtacellular recordings identified subpopulations of fast-spiking, parvalbumin-containing basket cells with epochs of firing at ripple (∼200 Hz) and high-gamma (∼120 Hz) frequencies detected during spindles and centered with millisecond precision at the trough of spindle waves in phase with field potential events but phase shifted relative to pyramidal cell firing. The results suggest that basket cell subpopulations are involved in spindle-nested, high-frequency network events that hypothetically provide repeatedly occurring neocortical temporal reference states potentially involved in mnemonic processes. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Establishing biorientation occurs with precocious separation of the sister kinetochores, but not the arms, in the early spindle of budding yeast.

PubMed

Goshima, G; Yanagida, M

2000-03-17

Sister kinetochores are bioriented toward the spindle poles in higher eukaryotic prometaphase before chromosome segregation. We show that, in budding yeast, the sister kinetochores are separated in the very early spindle, while the sister arms remain associated. Biorientation of the separated kinetochores is achieved already after replication. Mtw1p, a homolog of fission yeast Mis12 required for biorientation, locates at the centromeres in an Ndc10p-dependent manner. Mtw1p and the sequences 1.8 and 3.8 kb from CEN3 and CEN15, respectively, behave like the precociously separated kinetochores, whereas the sequences 23 and 35 kb distant from CEN3 and CEN5 previously used as the centromere markers behave like a part of the arm. Mtw1p and Ndc10p are identically located except for additional spindle localization of Ndc10p. A model explaining small centromeres and early spindle formation in budding yeast is proposed.

Cortical dendritic activity correlates with spindle-rich oscillations during sleep in rodents.

PubMed

Seibt, Julie; Richard, Clément J; Sigl-Glöckner, Johanna; Takahashi, Naoya; Kaplan, David I; Doron, Guy; de Limoges, Denis; Bocklisch, Christina; Larkum, Matthew E

2017-09-25

How sleep influences brain plasticity is not known. In particular, why certain electroencephalographic (EEG) rhythms are linked to memory consolidation is poorly understood. Calcium activity in dendrites is known to be necessary for structural plasticity changes, but this has never been carefully examined during sleep. Here, we report that calcium activity in populations of neocortical dendrites is increased and synchronised during oscillations in the spindle range in naturally sleeping rodents. Remarkably, the same relationship is not found in cell bodies of the same neurons and throughout the cortical column. Spindles during sleep have been suggested to be important for brain development and plasticity. Our results provide evidence for a physiological link of spindles in the cortex specific to dendrites, the main site of synaptic plasticity.Different stages of sleep, marked by particular electroencephalographic (EEG) signatures, have been linked to memory consolidation, but underlying mechanisms are poorly understood. Here, the authors show that dendritic calcium synchronisation correlates with spindle-rich sleep phases.

Bioinformatic investigation of the role of ubiquitins in cucumber flower morphogenesis

NASA Astrophysics Data System (ADS)

Pawełkowicz, Magdalena; Osipowski, Paweł; Wojcieszek, Michał; Kowalczuk, Cezary; PlÄ der, Wojciech; Przybecki, Zbigniew

2016-09-01

Three cDNA clones were used to screen cucumber genome in order to find genes and proteins. Functional annotation reveals that they are correlated with ubiquitination pathways. Various bioinformatics tools were used to screen and check protein sequences features such as: the presence of specific domains, transmembrane regions, cleavage site and cellular placement. The computational analysis for promotor region shows many binding sites for transcription factors, which could regulate the expression of genes. In order to check gene expression levels in developing flower buds of monoecious (B10) and gynoecious (2gg) cucumber lines, the real - time PCR technique was applied. The expression was checked for the whole buds and only for the 3rd and 4th whorls of bud when generative organ are form which were obtained by Laser Capture Microdissection (LCM) technique.

Spindle

DOE Office of Scientific and Technical Information (OSTI.GOV)

2013-04-04

Spindle is software infrastructure that solves file system scalabiltiy problems associated with starting dynamically linked applications in HPC environments. When an HPC applications starts up thousands of pricesses at once, and those processes simultaneously access a shared file system to look for shared libraries, it can cause significant performance problems for both the application and other users. Spindle scalably coordinates the distribution of shared libraries to an application to avoid hammering the shared file system.

Studies on Axonal Transport in an Animal Model for Gulf War Syndrome

DTIC Science & Technology

2008-07-01

designated by other documentation. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of...therapeutic strategies. With regard to kinesin-5, a homotetrameric motor protein that interacts with adjacent microtubules in the mitotic spindle , we...sets of antiparallel motor domains (Kashina et al., 1996). In the mitotic spindle , the primary func- tion of kinesin-5 is to maintain spindle bipolarity

Transient synchronization of hippocampo-striato-thalamo-cortical networks during sleep spindle oscillations induces motor memory consolidation.

PubMed

Boutin, Arnaud; Pinsard, Basile; Boré, Arnaud; Carrier, Julie; Fogel, Stuart M; Doyon, Julien

2018-04-01

Sleep benefits motor memory consolidation. This mnemonic process is thought to be mediated by thalamo-cortical spindle activity during NREM-stage2 sleep episodes as well as changes in striatal and hippocampal activity. However, direct experimental evidence supporting the contribution of such sleep-dependent physiological mechanisms to motor memory consolidation in humans is lacking. In the present study, we combined EEG and fMRI sleep recordings following practice of a motor sequence learning (MSL) task to determine whether spindle oscillations support sleep-dependent motor memory consolidation by transiently synchronizing and coordinating specialized cortical and subcortical networks. To that end, we conducted EEG source reconstruction on spindle epochs in both cortical and subcortical regions using novel deep-source localization techniques. Coherence-based metrics were adopted to estimate functional connectivity between cortical and subcortical structures over specific frequency bands. Our findings not only confirm the critical and functional role of NREM-stage2 sleep spindles in motor skill consolidation, but provide first-time evidence that spindle oscillations [11-17 Hz] may be involved in sleep-dependent motor memory consolidation by locally reactivating and functionally binding specific task-relevant cortical and subcortical regions within networks including the hippocampus, putamen, thalamus and motor-related cortical regions. Copyright © 2018 Elsevier Inc. All rights reserved.

Response to apatinib in chemotherapy-failed advanced spindle cell breast carcinoma.

PubMed

Zhou, Na; Liu, Congmin; Hou, Helei; Zhang, Chuantao; Liu, Dong; Wang, Guanqun; Liu, Kewei; Zhu, Jingjuan; Lv, Hongying; Li, Tianjun; Zhang, Xiaochun

2016-11-01

Spindle cell carcinoma of the breast is a rare subtype of metaplastic carcinoma, and no effective chemotherapy special for metaplastic carcinoma exists until now. As spindle cell carcinomas of the breast are typically "Triple Negative", endocrine therapy and molecular therapy targeted to Her2 might not be favorable, resulting in poor prognosis. Apatinib is currently being tested in patients with breast or lung cancers. Here we report a successful case using Apatinib to treat spindle cell carcinoma of breast.A 52- year- old woman presented with a gradually enlarged lump in left breast, which was revealed to be a triple-negative spindle cell carcinoma, underwent a modified radical mastectomy. After the first line chemotherapy with Cyclophosphamide and Epirubicin, multiple metastases in bilateral lung and left anterior thoracic wall appeared. After disease progressed with therapy of Bevacizumab combined with Albumin-bound Paclitaxel and Cisplatin, we treated the patient with Apatinib according to her VEGFR expression, which showed nearly complete response and controllable and tolerated side effects. Next-generation sequencing analysis of the tumor specimen and real time ctDNA was performed to observe the mutated gene numbers matched with therapeutic effect. The present case can help to provide a new and effective therapy strategy to treat advanced spindle cell carcinoma.

Response to apatinib in chemotherapy-failed advanced spindle cell breast carcinoma

PubMed Central

Zhou, Na; Liu, Congmin; Hou, Helei; Zhang, Chuantao; Liu, Dong; Wang, Guanqun; Liu, Kewei; Zhu, Jingjuan; Lv, Hongying; Li, Tianjun; Zhang, Xiaochun

2016-01-01

Spindle cell carcinoma of the breast is a rare subtype of metaplastic carcinoma, and no effective chemotherapy special for metaplastic carcinoma exists until now. As spindle cell carcinomas of the breast are typically “Triple Negative”, endocrine therapy and molecular therapy targeted to Her2 might not be favorable, resulting in poor prognosis. Apatinib is currently being tested in patients with breast or lung cancers. Here we report a successful case using Apatinib to treat spindle cell carcinoma of breast. A 52- year- old woman presented with a gradually enlarged lump in left breast, which was revealed to be a triple-negative spindle cell carcinoma, underwent a modified radical mastectomy. After the first line chemotherapy with Cyclophosphamide and Epirubicin, multiple metastases in bilateral lung and left anterior thoracic wall appeared. After disease progressed with therapy of Bevacizumab combined with Albumin-bound Paclitaxel and Cisplatin, we treated the patient with Apatinib according to her VEGFR expression, which showed nearly complete response and controllable and tolerated side effects. Next-generation sequencing analysis of the tumor specimen and real time ctDNA was performed to observe the mutated gene numbers matched with therapeutic effect. The present case can help to provide a new and effective therapy strategy to treat advanced spindle cell carcinoma. PMID:27738308

Mitosis in Barbulanympha. I. Spindle structure, formation, and kinetochore engagement

PubMed Central

1978-01-01

Successful culture of the obligatorily anaerobic symbionts residing in the hindgut of the wood-eating cockroach Cryptocercus punctulatus now permits continuous observation of mitosis in individual Barbulanympha cells. In Part I of this two-part paper, we report methods for culture of the protozoa, preparation of microscope slide cultures in which Barbulanympha survived and divided for up to 3 days, and an optical arrangement which permits observation and through-focus photographic recording of dividing cells, sequentially in differential interference contrast and rectified polarized light microscopy. We describe the following prophase events and structures: development of the astral rays and large extranuclear central spindle from the tips of the elongate-centrioles; the fine structure of spindle fibers and astral rays which were deduced in vivo from polarized light microscopy and seen as a particular array of microtubules in thin-section electron micrographs; formation of chromosomal spindle fibers by dynamic engagement of astral rays to the kinetochores embedded in the persistent nuclear envelope; and repetitive shortening of chromosomal spindle fibers which appear to hoist the nucleus to the spindle surface, cyclically jostle the kinetochores within the nuclear envelope, and churn the prophase chromosomes. The observations described here and in Part II have implications both for the evolution of mitosis and for understanding the mitotic process generally. PMID:681451

Diverse mitotic functions of the cytoskeletal cross-linking protein Shortstop suggest a role in Dynein/Dynactin activity

PubMed Central

Dewey, Evan B.; Johnston, Christopher A.

2017-01-01

Proper assembly and orientation of the bipolar mitotic spindle is critical to the fidelity of cell division. Mitotic precision fundamentally contributes to cell fate specification, tissue development and homeostasis, and chromosome distribution within daughter cells. Defects in these events are thought to contribute to several human diseases. The underlying mechanisms that function in spindle morphogenesis and positioning remain incompletely defined, however. Here we describe diverse roles for the actin-microtubule cross-linker Shortstop (Shot) in mitotic spindle function in Drosophila. Shot localizes to mitotic spindle poles, and its knockdown results in an unfocused spindle pole morphology and a disruption of proper spindle orientation. Loss of Shot also leads to chromosome congression defects, cell cycle progression delay, and defective chromosome segregation during anaphase. These mitotic errors trigger apoptosis in Drosophila epithelial tissue, and blocking this apoptotic response results in a marked induction of the epithelial–mesenchymal transition marker MMP-1. The actin-binding domain of Shot directly interacts with Actin-related protein-1 (Arp-1), a key component of the Dynein/Dynactin complex. Knockdown of Arp-1 phenocopies Shot loss universally, whereas chemical disruption of F-actin does so selectively. Our work highlights novel roles for Shot in mitosis and suggests a mechanism involving Dynein/Dynactin activation. PMID:28747439

45 CFR 1703.404 - Copying and transcription charges.

Code of Federal Regulations, 2010 CFR

2010-10-01

... LIBRARIES AND INFORMATION SCIENCE GOVERNMENT IN THE SUNSHINE ACT Maintenance of Meeting Records § 1703.404.... Requested information will not be released until the deposit is received. Fees shall be paid by check or money order made payable to the National Commission on Libraries and Information Science. (b) The...

45 CFR 1703.404 - Copying and transcription charges.

Code of Federal Regulations, 2014 CFR

2014-10-01

... LIBRARIES AND INFORMATION SCIENCE GOVERNMENT IN THE SUNSHINE ACT Maintenance of Meeting Records § 1703.404.... Requested information will not be released until the deposit is received. Fees shall be paid by check or money order made payable to the National Commission on Libraries and Information Science. (b) The...

Ultrastructural and molecular biologic comparison of classic proprioceptors and palisade endings in sheep extraocular muscles.

PubMed

Rungaldier, Stefanie; Heiligenbrunner, Stefan; Mayer, Regina; Hanefl-Krivanek, Christiane; Lipowec, Marietta; Streicher, Johannes; Blumer, Roland

2009-12-01

To analyze and compare the structural and molecular features of classic proprioceptors like muscle spindles and Golgi tendon organs (GTOs) and putative proprioceptors (palisade endings) in sheep extraocular muscle (EOMs). The EOMs of four sheep were analyzed. Frozen sections or wholemount preparations of the samples were immunohistochemically labeled and analyzed by confocal laser scanning microscopy. Triple labeling with different combinations of antibodies against neurofilament, synaptophysin, and choline acetyltransferase (ChAT), as well as alpha-bungarotoxin and phalloidin, was performed. Microscopic anatomy of the nerve end organs was analyzed by transmission electron microscopy. The microscopic anatomy demonstrated that muscle spindles and GTOs had a perineural capsule and palisade endings a connective tissue capsule. Sensory nerve terminals in muscle spindles and GTOs contained only a few vesicles, whereas palisade nerve terminals were full of clear vesicles. Likewise, motor terminals in the muscle spindles' polar regions were full of clear vesicles. Immunohistochemistry showed that sensory nerve fibers as well as their sensory nerve terminals in muscle spindles and GTOs were ChAT-negative. Palisade endings were supplied by ChAT-positive nerve fibers, and the palisade complexes including palisade nerve terminals were also ChAT-immunoreactive. Motor terminals in muscle spindles were ChAT and alpha-bungarotoxin positive. The present study demonstrated in sheep EOMs that palisade endings are innervated by cholinergic axons exhibiting characteristics typical of motoneurons, whereas muscle spindles (except the polar regions) and GTOs are supplied by noncholinergic axons. These results raise the question of whether palisade endings are candidates for proprioceptors in EOMs.

Characteristics of Paraspinal Muscle Spindle Response to Mechanically Assisted Spinal Manipulation: A Preliminary Report.

PubMed

Reed, William R; Pickar, Joel G; Sozio, Randall S; Liebschner, Michael A K; Little, Joshua W; Gudavalli, Maruti R

The purpose of this preliminary study is to determine muscle spindle response characteristics related to the use of 2 solenoid powered clinical mechanically assisted manipulation (MAM) devices. L6 muscle spindle afferents with receptive fields in paraspinal muscles were isolated in 6 cats. Neural recordings were made during L7 MAM thrusts using the Activator V (Activator Methods Int. Ltd., Phoenix, AZ) and/or Pulstar (Sense Technology Inc., Pittsburgh, PA) devices at their 3 lowest force settings. Mechanically assisted manipulation response measures included (a) the time required post-thrust until the first action potential, (b) differences in mean frequency (MF) and mean instantaneous frequency (MIF) 2 seconds before and after MAM, and (c) the time required for muscle spindle discharge (MF and MIF) to return to 95% of baseline after MAM. Depending on device setting, between 44% to 80% (Pulstar) and 11% to 63% (Activator V) of spindle afferents required >6 seconds to return to within 95% of baseline MF values; whereas 66% to 89% (Pulstar) and 75% to 100% (Activator V) of spindle responses returned to within 95% of baseline MIF in <6 seconds after MAM. Nonparametric comparisons between the 22 N and 44 N settings of the Pulstar yielded significant differences for the time required to return to baseline MF and MIF. Short duration (<10 ms) MAM thrusts decrease muscle spindle discharge with a majority of afferents requiring prolonged periods (>6 seconds) to return to baseline MF activity. Physiological consequences and clinical relevance of described MAM mechanoreceptor responses will require additional investigation. Copyright © 2017. Published by Elsevier Inc.

High frequency stimulation abolishes thalamic network oscillations: an electrophysiological and computational analysis

NASA Astrophysics Data System (ADS)

Lee, Kendall H.; Hitti, Frederick L.; Chang, Su-Youne; Lee, Dongchul C.; Roberts, David W.; McIntyre, Cameron C.; Leiter, James C.

2011-08-01

Deep brain stimulation (DBS) of the thalamus has been demonstrated to be effective for the treatment of epilepsy. To investigate the mechanism of action of thalamic DBS, we examined the effects of high frequency stimulation (HFS) on spindle oscillations in thalamic brain slices from ferrets. We recorded intracellular and extracellular electrophysiological activity in the nucleus reticularis thalami (nRt) and in thalamocortical relay (TC) neurons in the lateral geniculate nucleus, stimulated the slice using a concentric bipolar electrode, and recorded the level of glutamate within the slice. HFS (100 Hz) of TC neurons generated excitatory post-synaptic potentials, increased the number of action potentials in both TC and nRt neurons, reduced the input resistance, increased the extracellular glutamate concentration, and abolished spindle wave oscillations. HFS of the nRt also suppressed spindle oscillations. In both locations, HFS was associated with significant and persistent elevation in extracellular glutamate levels and suppressed spindle oscillations for many seconds after the cessation of stimulation. We simulated HFS within a computational model of the thalamic network, and HFS also disrupted spindle wave activity, but the suppression of spindle activity was short-lived. Simulated HFS disrupted spindle activity for prolonged periods of time only after glutamate release and glutamate-mediated activation of a hyperpolarization-activated current (Ih) was incorporated into the model. Our results suggest that the mechanism of action of thalamic DBS as used in epilepsy may involve the prolonged release of glutamate, which in turn modulates specific ion channels such as Ih, decreases neuronal input resistance, and abolishes thalamic network oscillatory activity.

From proto-mitosis to mitosis — An alternative hypothesis on the origin and evolution of the mitotic spindle

NASA Astrophysics Data System (ADS)

Roos, U.-P.

1984-03-01

Based on the assumption that the ancestral proto-eukaryote evolved from an ameboid prokarybte I propose the hypothesis that nuclear division of the proto-eukaryote was effected by the same system of contractile filaments it used for ameboid movement and cytosis. When the nuclear membranes evolved from the cell membrane, contractile filaments remained associated with them. The attachment site of the genome in the nuclear envelope was linked to the cell membrane by specialized contractile filaments. During protomitosis, i.e., nuclear and cell division of the proto-eukaryote, these filaments performed segregation of the chromosomes, whereas others constricted and cleaved the nucleus and the mother cell. When microtubules (MTs) had evolved in the cytoplasm, they also became engaged in nuclear division. Initially, an extranuolear bundle of MTs assisted chromosome segregation by establishing a defined axis. The evolutionary tendency then was towards an increasingly important role for MTs. Spindle pole bodies (SPBs) developed from the chromosomal attachment sites in the nuclear envelope and organized an extranuclear central spindle. The chromosomes remained attached to the SPBs during nuclear division. In a subsequent step the spindle became permanently lodged inside the nucleus. Chromosomes detached from the SPBs and acquired kinetochores and kinetochore-MTs. At first, this spindle segregated chromosomes by elongation, the kinetochore-MTs playing the role of static anchors. Later, spindle elongation was supplemented by poleward movement of the chromosomes. When dissolution of the nuclear envelope at the beginning of mitosis became a permanent feature, the open spindle of higher eukaryotes was born.

Intelligence measures and stage 2 sleep in typically-developing and autistic children.

PubMed

Tessier, Sophie; Lambert, Andréane; Chicoine, Marjolaine; Scherzer, Peter; Soulières, Isabelle; Godbout, Roger

2015-07-01

The relationship between intelligence measures and 2 EEG measures of non-rapid eye movement sleep, sleep spindles and Sigma activity, was examined in 13 typically-developing (TD) and 13 autistic children with normal IQ and no complaints of poor sleep. Sleep spindles and Sigma EEG activity were computed for frontal (Fp1, Fp2) and central (C3, C4) recording sites. Time in stage 2 sleep and IQ was similar in both groups. Autistic children presented less spindles at Fp2 compared to the TD children. TD children showed negative correlation between verbal IQ and sleep spindle density at Fp2. In the autistic group, verbal and full-scale IQ scores correlated negatively with C3 sleep spindle density. The duration of sleep spindles at Fp1 was shorter in the autistic group than in the TD children. The duration of sleep spindles at C4 was positively correlated with verbal IQ only in the TD group. Fast Sigma EEG activity (13.25-15.75 Hz) was lower at C3 and C4 in autistic children compared to the TD children, particularly in the latter part of the night. Only the TD group showed positive correlation between performance IQ and latter part of the night fast Sigma activity at C4. These results are consistent with a relationship between EEG activity during sleep and cognitive processing in children. The difference between TD and autistic children could derive from dissimilar cortical organization and information processing in these 2 groups. Copyright © 2015. Published by Elsevier B.V.

Sleep Spindles Are Related to Schizotypal Personality Traits and Thalamic Glutamine/Glutamate in Healthy Subjects

PubMed Central

Lustenberger, Caroline; O’Gorman, Ruth L.; Pugin, Fiona; Tüshaus, Laura; Wehrle, Flavia; Achermann, Peter; Huber, Reto

2015-01-01

Background: Schizophrenia is a severe mental disorder affecting approximately 1% of the worldwide population. Yet, schizophrenia-like experiences (schizotypy) are very common in the healthy population, indicating a continuum between normal mental functioning and the psychosis found in schizophrenic patients. A continuum between schizotypy and schizophrenia would be supported if they share the same neurobiological origin. Two such neurobiological markers of schizophrenia are: (1) a reduction of sleep spindles (12–15 Hz oscillations during nonrapid eye movement sleep), likely reflecting deficits in thalamo-cortical circuits and (2) increased glutamine and glutamate (Glx) levels in the thalamus. Thus, this study aimed to investigate whether sleep spindles and Glx levels are related to schizotypal personality traits in healthy subjects. Methods: Twenty young male subjects underwent 2 all-night sleep electroencephalography recordings (128 electrodes). Sleep spindles were detected automatically. After those 2 nights, thalamic Glx levels were measured by magnetic resonance spectroscopy. Subjects completed a magical ideation scale to assess schizotypy. Results: Sleep spindle density was negatively correlated with magical ideation (r = −.64, P < .01) and thalamic Glx levels (r = −.70, P < .005). No correlation was found between Glx levels in the thalamus and magical ideation (r = .12, P > .1). Conclusions: The common relationship of sleep spindle density with schizotypy and thalamic Glx levels indicates a neurobiological overlap between nonclinical schizotypy and schizophrenia. Thus, sleep spindle density and magical ideation may reflect the anatomy and efficiency of the thalamo-cortical system that shows pronounced impairment in patients with schizophrenia. PMID:25074975

A time-frequency analysis of the dynamics of cortical networks of sleep spindles from MEG-EEG recordings

PubMed Central

Zerouali, Younes; Lina, Jean-Marc; Sekerovic, Zoran; Godbout, Jonathan; Dube, Jonathan; Jolicoeur, Pierre; Carrier, Julie

2014-01-01

Sleep spindles are a hallmark of NREM sleep. They result from a widespread thalamo-cortical loop and involve synchronous cortical networks that are still poorly understood. We investigated whether brain activity during spindles can be characterized by specific patterns of functional connectivity among cortical generators. For that purpose, we developed a wavelet-based approach aimed at imaging the synchronous oscillatory cortical networks from simultaneous MEG-EEG recordings. First, we detected spindles on the EEG and extracted the corresponding frequency-locked MEG activity under the form of an analytic ridge signal in the time-frequency plane (Zerouali et al., 2013). Secondly, we performed source reconstruction of the ridge signal within the Maximum Entropy on the Mean framework (Amblard et al., 2004), yielding a robust estimate of the cortical sources producing observed oscillations. Lastly, we quantified functional connectivity among cortical sources using phase-locking values. The main innovations of this methodology are (1) to reveal the dynamic behavior of functional networks resolved in the time-frequency plane and (2) to characterize functional connectivity among MEG sources through phase interactions. We showed, for the first time, that the switch from fast to slow oscillatory mode during sleep spindles is required for the emergence of specific patterns of connectivity. Moreover, we show that earlier synchrony during spindles was associated with mainly intra-hemispheric connectivity whereas later synchrony was associated with global long-range connectivity. We propose that our methodology can be a valuable tool for studying the connectivity underlying neural processes involving sleep spindles, such as memory, plasticity or aging. PMID:25389381

Counterbalance of cutting force for advanced milling operations

NASA Astrophysics Data System (ADS)

Tsai, Nan-Chyuan; Shih, Li-Wen; Lee, Rong-Mao

2010-05-01

The goal of this work is to concurrently counterbalance the dynamic cutting force and regulate the spindle position deviation under various milling conditions by integrating active magnetic bearing (AMB) technique, fuzzy logic algorithm and an adaptive self-tuning feedback loop. Since the dynamics of milling system is highly determined by a few operation conditions, such as speed of spindle, cut depth and feedrate, therefore the dynamic model for cutting process is more appropriate to be constructed by experiments, instead of using theoretical approach. The experimental data, either for idle or cutting, are utilized to establish the database of milling dynamics so that the system parameters can be on-line estimated by employing the proposed fuzzy logic algorithm as the cutting mission is engaged. Based on the estimated milling system model and preset operation conditions, i.e., spindle speed, cut depth and feedrate, the current cutting force can be numerically estimated. Once the current cutting force can be real-time estimated, the corresponding compensation force can be exerted by the equipped AMB to counterbalance the cutting force, in addition to the spindle position regulation by feedback of spindle position. On the other hand, for the magnetic force is nonlinear with respect to the applied electric current and air gap, the characteristics of the employed AMB is investigated also by experiments and a nonlinear mathematic model, in terms of air gap between spindle and electromagnetic pole and coil current, is developed. At the end, the experimental simulations on realistic milling are presented to verify the efficacy of the fuzzy controller for spindle position regulation and the capability of the dynamic cutting force counterbalance.

Isoform-specific functions of Mud/NuMA mediate binucleation of Drosophila male accessory gland cells.

PubMed

Taniguchi, Kiichiro; Kokuryo, Akihiko; Imano, Takao; Minami, Ryunosuke; Nakagoshi, Hideki; Adachi-Yamada, Takashi

2014-12-20

In standard cell division, the cells undergo karyokinesis and then cytokinesis. Some cells, however, such as cardiomyocytes and hepatocytes, can produce binucleate cells by going through mitosis without cytokinesis. This cytokinesis skipping is thought to be due to the inhibition of cytokinesis machinery such as the central spindle or the contractile ring, but the mechanisms regulating it are unclear. We investigated them by characterizing the binucleation event during development of the Drosophila male accessory gland, in which all cells are binucleate. The accessory gland cells arrested the cell cycle at 50 hours after puparium formation (APF) and in the middle of the pupal stage stopped proliferating for 5 hours. They then restarted the cell cycle and at 55 hours APF entered the M-phase synchronously. At this stage, accessory gland cells binucleated by mitosis without cytokinesis. Binucleating cells displayed the standard karyokinesis progression but also showed unusual features such as a non-round shape, spindle orientation along the apico-basal axis, and poor assembly of the central spindle. Mud, a Drosophila homolog of NuMA, regulated the processes responsible for these three features, the classical isoform Mud(PBD) and the two newly characterized isoforms Mud(L) and Mud(S) regulated them differently: Mud(L) repressed cell rounding, Mud(PBD) and Mud(S) oriented the spindle along the apico-basal axis, and Mud(S) and Mud(L) repressed central spindle assembly. Importantly, overexpression of Mud(S) induced binucleation even in standard proliferating cells such as those in imaginal discs. We characterized the binucleation in the Drosophila male accessory gland and examined mechanisms that regulated unusual morphologies of binucleating cells. We demonstrated that Mud, a microtubule binding protein regulating spindle orientation, was involved in this binucleation. We suggest that atypical functions exerted by three structurally different isoforms of Mud regulate cell rounding, spindle orientation and central spindle assembly in binucleation. We also propose that Mud(S) is a key regulator triggering cytokinesis skipping in binucleation processes.

Console test report for shuttle task 501 shuttle carrier aircraft transceiver console (SED 36115353-301)

NASA Technical Reports Server (NTRS)

Lane, J. H.

1976-01-01

Performance tests completed on the Space Shuttle Carrier Aircraft (SCA) transceiver console, verifying its design objectives, were described. These tests included: (1) check of power supply voltages for correct output voltage and energization at the proper point in the turn on sequence, (2) check of cooling system (LRU blower, overload sensors and circuitry, and thermocouple probe), (3) check of control circuits logic, including the provisions for remote control and display, (4) check of the LRU connector for presence of correct voltages and absence of incorrect voltages under both energized and deenergized conditions, and (5) check of the AGC and power output monitor circuits.

A digital system for surface reconstruction

USGS Publications Warehouse

Zhou, Weiyang; Brock, Robert H.; Hopkins, Paul F.

1996-01-01

A digital photogrammetric system, STEREO, was developed to determine three dimensional coordinates of points of interest (POIs) defined with a grid on a textureless and smooth-surfaced specimen. Two CCD cameras were set up with unknown orientation and recorded digital images of a reference model and a specimen. Points on the model were selected as control or check points for calibrating or assessing the system. A new algorithm for edge-detection called local maximum convolution (LMC) helped extract the POIs from the stereo image pairs. The system then matched the extracted POIs and used a least squares “bundle” adjustment procedure to solve for the camera orientation parameters and the coordinates of the POIs. An experiment with STEREO found that the standard deviation of the residuals at the check points was approximately 24%, 49% and 56% of the pixel size in the X, Y and Z directions, respectively. The average of the absolute values of the residuals at the check points was approximately 19%, 36% and 49% of the pixel size in the X, Y and Z directions, respectively. With the graphical user interface, STEREO demonstrated a high degree of automation and its operation does not require special knowledge of photogrammetry, computers or image processing.

Centromeric chromatin and its dynamics in plants.

PubMed

Lermontova, Inna; Sandmann, Michael; Mascher, Martin; Schmit, Anne-Catherine; Chabouté, Marie-Edith

2015-07-01

Centromeres are chromatin structures that are required for proper separation of chromosomes during mitosis and meiosis. The centromere is composed of centromeric DNA, often enriched in satellite repeats, and kinetochore complex proteins. To date, over 100 kinetochore components have been identified in various eukaryotes. Kinetochore assembly begins with incorporation of centromeric histone H3 variant CENH3 into centromeric nucleosomes. Protein components of the kinetochore are either present at centromeres throughout the cell cycle or localize to centromeres transiently, prior to attachment of microtubules to each kinetochore in prometaphase of mitotic cells. This is the case for the spindle assembly checkpoint (SAC) proteins in animal cells. The SAC complex ensures equal separation of chromosomes between daughter nuclei by preventing anaphase onset before metaphase is complete, i.e. the sister kinetochores of all chromosomes are attached to spindle fibers from opposite poles. In this review, we focus on the organization of centromeric DNA and the kinetochore assembly in plants. We summarize recent advances regarding loading of CENH3 into the centromere, and the subcellular localization and protein-protein interactions of Arabidopsis thaliana proteins involved in kinetochore assembly and function. We describe the transcriptional activity of corresponding genes based on in silico analysis of their promoters and cell cycle-dependent expression. Additionally, barley homologs of all selected A. thaliana proteins have been identified in silico, and their sequences and domain structures are presented. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

SU-F-T-238: Analyzing the Performance of MapCHECK2 and Delta4 Quality Assurance Phantoms in IMRT and VMAT Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, SH; Tsai, YC; Lan, HT

2016-06-15

Purpose: Intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) have been widely investigated for use in radiotherapy and found to have a highly conformal dose distribution. Delta{sup 4} is a novel cylindrical phantom consisting of 1069 p-type diodes with true treatments measured in the 3D target volume. The goal of this study was to compare the performance of a Delta{sup 4} diode array for IMRT and VMAT planning with ion chamber and MapCHECK2. Methods: Fifty-four IMRT (n=9) and VMAT (n=45) plans were imported to Philips Pinnacle Planning System 9.2 for recalculation with a solid water phantom, MapCHECK2, and themore » Delta4 phantom. To evaluate the difference between the measured and calculated dose, we used MapCHECK2 and Delta{sup 4} for a dose-map comparison and an ion chamber (PTW 31010 Semiflex 0.125 cc) for a point-dose comparison. Results: All 54 plans met the criteria of <3% difference for the point dose (at least two points) by ion chamber. The mean difference was 0.784% with a standard deviation of 1.962%. With a criteria of 3 mm/3% in a gamma analysis, the average passing rates were 96.86%±2.19% and 98.42%±1.97% for MapCHECK2 and Delta{sup 4}, respectively. The student t-test of MapCHECK2/Delta{sup 4}, ion chamber/Delta{sup 4}, and ion chamber/MapCHECK2 were 0.0008, 0.2944, and 0.0002, respectively. There was no significant difference in passing rates between MapCHECK2 and Delta{sup 4} for the IMRT plan (p = 0.25). However, a higher pass rate was observed in Delta{sup 4} (98.36%) as compared to MapCHECK2 (96.64%, p < 0.0001) for the VMAT plan. Conclusion: The Pinnacle planning system can accurately calculate doses for VMAT and IMRT plans. The Delta{sup 4} shows a similar result when compared to ion chamber and MapCHECK2, and is an efficient tool for patient-specific quality assurance, especially for rotation therapy.« less

6. FLOOR 1; LOOKING WEST; SHOWS UNDERDRIFT SYSTEM, FOUR POSTS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. FLOOR 1; LOOKING WEST; SHOWS UNDERDRIFT SYSTEM, FOUR POSTS SUPPORT BRIDGE BEAM FOR FOOT BEARING OF UPRIGHT SHAFT, SPUR PINION STONE NUTS SLIDE DOWN STONE SPINDLE TO ENGAGE, CENTRIFUGAL GOVERNOR IS MOUNTED ON A SEPARATE SPINDLE DRIVEN BY A BELT FROM THE STONE SPINDLE; ALSO SHOWN ARE THE GREAT SPUR WHEEL AND A LAYSHAFT RUNNING OFF A CROWN WHEEL JUST ABOVE THE GREAT SPUR WHEEL - Gardiner Windmill, East Hampton, Suffolk County, NY

Microtubule dynamics in cell division: exploring living cells with polarized light microscopy.

PubMed

Inoué, Shinya

2008-01-01

This Perspective is an account of my early experience while I studied the dynamic organization and behavior of the mitotic spindle and its submicroscopic filaments using polarized light microscopy. The birefringence of spindle filaments in normally dividing plant and animal cells, and those treated by various agents, revealed (a) the reality of spindle fibers and fibrils in healthy living cells; (b) the labile, dynamic nature of the molecular filaments making up the spindle fibers; (c) the mode of fibrogenesis and action of orienting centers; and (d) force-generating properties based on the disassembly and assembly of the fibrils. These studies, which were carried out directly on living cells using improved polarizing microscopes, in fact predicted the reversible assembly properties of microtubules.

Method for automated building of spindle thermal model with use of CAE system

NASA Astrophysics Data System (ADS)

Kamenev, S. V.

2018-03-01

The spindle is one of the most important units of the metal-cutting machine tool. Its performance is critical to minimize the machining error, especially the thermal error. Various methods are applied to improve the thermal behaviour of spindle units. One of the most important methods is mathematical modelling based on the finite element analysis. The most common approach for its realization is the use of CAE systems. This approach, however, is not capable to address the number of important effects that need to be taken into consideration for proper simulation. In the present article, the authors propose the solution to overcome these disadvantages using automated thermal model building for the spindle unit utilizing the CAE system ANSYS.

Overexpression of Mps1 in colon cancer cells attenuates the spindle assembly checkpoint and increases aneuploidy.

PubMed

Ling, Youguo; Zhang, Xiaojuan; Bai, Yuanyuan; Li, Ping; Wei, Congwen; Song, Ting; Zheng, Zirui; Guan, Kai; Zhang, Yanhong; Zhang, Buchang; Liu, Xuedong; Ma, Runlin Z; Cao, Cheng; Zhong, Hui; Xu, Quanbin

2014-08-08

The spindle assembly checkpoint kinase Mps1 is highly expressed in several types of cancers, but its cellular involvement in tumorigenesis is less defined. Herein, we confirm that Mps1 is overexpressed in colon cancer tissues. Further, we find that forced expression of Mps1 in the colon cancer cell line SW480 enables cells to become resistant to both Mps1 inhibition-induced checkpoint depletion and cell death. Overexpression of Mps1 also increases genome instability in tumor cells owing to a weakened spindle assembly checkpoint. Collectively, our findings suggest that high levels of Mps1 contribute to tumorigenesis by attenuating the spindle assembly checkpoint. Copyright © 2014 Elsevier Inc. All rights reserved.

Exclusive destruction of mitotic spindles in human cancer cells.

PubMed

Visochek, Leonid; Castiel, Asher; Mittelman, Leonid; Elkin, Michael; Atias, Dikla; Golan, Talia; Izraeli, Shai; Peretz, Tamar; Cohen-Armon, Malka

2017-03-28

We identified target proteins modified by phenanthrenes that cause exclusive eradication of human cancer cells. The cytotoxic activity of the phenanthrenes in a variety of human cancer cells is attributed by these findings to post translational modifications of NuMA and kinesins HSET/kifC1 and kif18A. Their activity prevented the binding of NuMA to α-tubulin and kinesins in human cancer cells, and caused aberrant spindles. The most efficient cytotoxic activity of the phenanthridine PJ34, caused significantly smaller aberrant spindles with disrupted spindle poles and scattered extra-centrosomes and chromosomes. Concomitantly, PJ34 induced tumor growth arrest of human malignant tumors developed in athymic nude mice, indicating the relevance of its activity for cancer therapy.

Performance of Compiler-Assisted Memory Safety Checking

DTIC Science & Technology

2014-08-01

software developer has in mind a particular object to which the pointer should point, the intended referent. A memory access error occurs when an ac...Performance of Compiler-Assisted Memory Safety Checking David Keaton Robert C. Seacord August 2014 TECHNICAL NOTE CMU/SEI-2014-TN...based memory safety checking tool and the performance that can be achieved with two such tools whose source code is freely available. The note then

Radiobiological studies of plants orbited in Biosatellite II.

PubMed

Schairer, L A; Sparrow, A H; Marimuthu, K M

1970-01-01

The Biosatellite II Tradescantia experiment probed the effects of the space environment on spontaneous and radiation-induced mutation rates and on cytological changes in Tradescantia clone 02. Thirty two young flowering plants arranged in a plastic housing with the roots immersed in nutrient solution were exposed to gamma radiation from an on-board 85 Strontium source during the two-day orbital flight. Unirradiated plants were flown in a package in the spacecraft behind a tungsten radiation shield and identical non-flight control packages (with and without irradiation) were maintained at the launch site. After retrieval of the spacecraft near Hawaii, samples of root tip, ovary and stamen tissues were collected. These and the intact plants were flown to the Brookhaven National Laboratory for observations on the following end points: somatic mutation, cell size, loss of reproductive integrity resulting in stunted stamen hairs, pollen grain mortality, frequency of micronuclei in pollen, disturbed mitotic spindle function and chromosome aberrations. Analysis of data on somatic mutation, cell size and chromosome aberration end points showed no significant differences between flight and non-flight samples. However, pollen abortion, frequency of micronuclei in pollen and loss of reproductive integrity (stamen hair stunting) showed increases associated with weightlessness in irradiated material. Root tip and microspore cells showed effects of disturbed mitotic spindle function in orbited plants both with and without irradiation. Clearly differences exist between flight and non-flight material and the significance and possible mechanisms for these effects are being studied in continuing non-flight tests.

Genome wide interactions of wild-type and activator bypass forms of σ54.

PubMed

Schaefer, Jorrit; Engl, Christoph; Zhang, Nan; Lawton, Edward; Buck, Martin

2015-09-03

Enhancer-dependent transcription involving the promoter specificity factor σ(54) is widely distributed amongst bacteria and commonly associated with cell envelope function. For transcription initiation, σ(54)-RNA polymerase yields open promoter complexes through its remodelling by cognate AAA+ ATPase activators. Since activators can be bypassed in vitro, bypass transcription in vivo could be a source of emergent gene expression along evolutionary pathways yielding new control networks and transcription patterns. At a single test promoter in vivo bypass transcription was not observed. We now use genome-wide transcription profiling, genome-wide mutagenesis and gene over-expression strategies in Escherichia coli, to (i) scope the range of bypass transcription in vivo and (ii) identify genes which might alter bypass transcription in vivo. We find little evidence for pervasive bypass transcription in vivo with only a small subset of σ(54) promoters functioning without activators. Results also suggest no one gene limits bypass transcription in vivo, arguing bypass transcription is strongly kept in check. Promoter sequences subject to repression by σ(54) were evident, indicating loss of rpoN (encoding σ(54)) rather than creating rpoN bypass alleles would be one evolutionary route for new gene expression patterns. Finally, cold-shock promoters showed unusual σ(54)-dependence in vivo not readily correlated with conventional σ(54) binding-sites. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Genome wide interactions of wild-type and activator bypass forms of σ54

PubMed Central

Schaefer, Jorrit; Engl, Christoph; Zhang, Nan; Lawton, Edward; Buck, Martin

2015-01-01

Enhancer-dependent transcription involving the promoter specificity factor σ54 is widely distributed amongst bacteria and commonly associated with cell envelope function. For transcription initiation, σ54-RNA polymerase yields open promoter complexes through its remodelling by cognate AAA+ ATPase activators. Since activators can be bypassed in vitro, bypass transcription in vivo could be a source of emergent gene expression along evolutionary pathways yielding new control networks and transcription patterns. At a single test promoter in vivo bypass transcription was not observed. We now use genome-wide transcription profiling, genome-wide mutagenesis and gene over-expression strategies in Escherichia coli, to (i) scope the range of bypass transcription in vivo and (ii) identify genes which might alter bypass transcription in vivo. We find little evidence for pervasive bypass transcription in vivo with only a small subset of σ54 promoters functioning without activators. Results also suggest no one gene limits bypass transcription in vivo, arguing bypass transcription is strongly kept in check. Promoter sequences subject to repression by σ54 were evident, indicating loss of rpoN (encoding σ54) rather than creating rpoN bypass alleles would be one evolutionary route for new gene expression patterns. Finally, cold-shock promoters showed unusual σ54-dependence in vivo not readily correlated with conventional σ54 binding-sites. PMID:26082500

Reorganization of microtubules in endosperm cells and cell fragments of the higher plant Haemanthus in vivo

PubMed Central

1986-01-01

The reorganization of the microtubular meshwork was studied in intact Haemanthus endosperm cells and cell fragments (cytoplasts). This higher plant tissue is devoid of a known microtubule organizating organelle. Observations on living cells were correlated with microtubule arrangements visualized with the immunogold method. In small fragments, reorganization did not proceed. In medium and large sized fragments, microtubular converging centers formed first. Then these converging centers reorganized into either closed bushy microtubular spiral or chromosome-free cytoplasmic spindles/phragmoplasts. Therefore, the final shape of organized microtubular structures, including spindle shaped, was determined by the initial size of the cell fragments and could be achieved without chromosomes or centrioles. Converging centers elongate due to the formation of additional structures resembling microtubular fir trees. These structures were observed at the pole of the microtubular converging center in anucleate fragments, accessory phragmoplasts in nucleated cells, and in the polar region of the mitotic spindle during anaphase. Therefore, during anaphase pronounced assembly of new microtubules occurs at the polar region of acentriolar spindles. Moreover, statistical analysis demonstrated that during the first two-thirds of anaphase, when chromosomes move with an approximately constant speed, kinetochore fibers shorten, while the length of the kinetochore fiber complex remains constant due to the simultaneous elongation of their integral parts (microtubular fir trees). The half-spindle shortens only during the last one-third of anaphase. These data contradict the presently prevailing view that chromosome-to-pole movements in acentriolar spindles of higher plants are concurrent with the shortening of the half-spindle, the self- reorganizing property of higher plant microtubules (tubulin) in vivo. It may be specific for cells without centrosomes and may be superimposed also on other microtubule-related processes. PMID:3941154

Genotoxicity of multi-walled carbon nanotubes at occupationally relevant doses

PubMed Central

2014-01-01

Carbon nanotubes are commercially-important products of nanotechnology; however, their low density and small size makes carbon nanotube respiratory exposures likely during their production or processing. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to single-walled carbon nanotubes (SWCNT). In this study, we examined whether multi-walled carbon nanotubes (MWCNT) cause mitotic spindle damage in cultured cells at doses equivalent to 34 years of exposure at the NIOSH Recommended Exposure Limit (REL). MWCNT induced a dose responsive increase in disrupted centrosomes, abnormal mitotic spindles and aneuploid chromosome number 24 hours after exposure to 0.024, 0.24, 2.4 and 24 μg/cm2 MWCNT. Monopolar mitotic spindles comprised 95% of disrupted mitoses. Three-dimensional reconstructions of 0.1 μm optical sections showed carbon nanotubes integrated with microtubules, DNA and within the centrosome structure. Cell cycle analysis demonstrated a greater number of cells in S-phase and fewer cells in the G2 phase in MWCNT-treated compared to diluent control, indicating a G1/S block in the cell cycle. The monopolar phenotype of the disrupted mitotic spindles and the G1/S block in the cell cycle is in sharp contrast to the multi-polar spindle and G2 block in the cell cycle previously observed following exposure to SWCNT. One month following exposure to MWCNT there was a dramatic increase in both size and number of colonies compared to diluent control cultures, indicating a potential to pass the genetic damage to daughter cells. Our results demonstrate significant disruption of the mitotic spindle by MWCNT at occupationally relevant exposure levels. PMID:24479647

Effective killing of the human pathogen Candida albicans by a specific inhibitor of non-essential mitotic kinesin Kip1p

PubMed Central

Chua, Penelope R; Roof, David M; Lee, Yan; Sakowicz, Roman; Clarke, David; Pierce, Dan; Stephens, Thoryn; Hamilton, Matthew; Morgan, Brad; Morgans, David; Nakai, Takashi; Tomasi, Adam; Maxon, Mary E

2007-01-01

Kinesins from the bipolar (Kinesin-5) family are conserved in eukaryotic organisms and play critical roles during the earliest stages of mitosis to mediate spindle pole body separation and formation of a bipolar mitotic spindle. To date, genes encoding bipolar kinesins have been reported to be essential in all organisms studied. We report the characterization of CaKip1p, the sole member of this family in the human pathogenic yeast Candida albicans. C. albicans Kip1p appears to localize to the mitotic spindle and loss of CaKip1p function interferes with normal progression through mitosis. Inducible excision of CaKIP1 revealed phenotypes unique to C. albicans, including viable homozygous Cakip1 mutants and an aberrant spindle morphology in which multiple spindle poles accumulate in close proximity to each other. Expression of the C. albicans Kip1 motor domain in Escherichia coli produced a protein with microtubule-stimulated ATPase activity that was inhibited by an aminobenzothiazole (ABT) compound in an ATP-competitive fashion. This inhibition results in ‘rigor-like’, tight association with microtubules in vitro. Upon treatment of C. albicans cells with the ABT compound, cells were killed, and terminal phenotype analysis revealed an aberrant spindle morphology similar to that induced by loss of the CaKIP1 gene. The ABT compound discovered is the first example of a fungal spindle inhibitor targeted to a mitotic kinesin. Our results also show that the non-essential nature and implementation of the bipolar motor in C. albicans differs from that seen in other organisms, and suggest that inhibitors of a non-essential mitotic kinesin may offer promise as cidal agents for antifungal drug discovery. PMID:17573815

Cdk1-cyclin B1-mediated phosphorylation of tumor-associated microtubule-associated protein/cytoskeleton-associated protein 2 in mitosis.

PubMed

Hong, Kyung Uk; Kim, Hyun-Jun; Kim, Hyo-Sil; Seong, Yeon-Sun; Hong, Kyeong-Man; Bae, Chang-Dae; Park, Joobae

2009-06-12

During mitosis, establishment of structurally and functionally sound bipolar spindles is necessary for maintaining the fidelity of chromosome segregation. Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton-associated protein 2 (CKAP2), is a mitotic spindle-associated protein whose level is frequently up-regulated in various malignancies. Previous reports have suggested that TMAP is a potential regulator of mitotic spindle assembly and dynamics and that it is required for chromosome segregation to occur properly. So far, there have been no reports on how its mitosis-related functions are regulated. Here, we report that TMAP is hyper-phosphorylated at the C terminus specifically during mitosis. At least four different residues (Thr-578, Thr-596, Thr-622, and Ser-627) were responsible for the mitosis-specific phosphorylation of TMAP. Among these, Thr-622 was specifically phosphorylated by Cdk1-cyclin B1 both in vitro and in vivo. Interestingly, compared with the wild type, a phosphorylation-deficient mutant form of TMAP, in which Thr-622 had been replaced with an alanine (T622A), induced a significant increase in the frequency of metaphase cells with abnormal bipolar spindles, which often displayed disorganized, asymmetrical, or narrow and elongated morphologies. Formation of these abnormal bipolar spindles subsequently resulted in misalignment of metaphase chromosomes and ultimately caused a delay in the entry into anaphase. Moreover, such defects resulting from the T622A mutation were associated with a decrease in the rate of protein turnover at spindle microtubules. These findings suggest that Cdk1-cyclin B1-mediated phosphorylation of TMAP is important for and contributes to proper regulation of microtubule dynamics and establishment of functional bipolar spindles during mitosis.

Radmis, a Novel Mitotic Spindle Protein that Functions in Cell Division of Neural Progenitors

PubMed Central

Yumoto, Takahito; Nakadate, Kazuhiko; Nakamura, Yuki; Sugitani, Yoshinobu; Sugitani-Yoshida, Reiko; Ueda, Shuichi; Sakakibara, Shin-ichi

2013-01-01

Developmental dynamics of neural stem/progenitor cells (NSPCs) are crucial for embryonic and adult neurogenesis, but its regulatory factors are not fully understood. By differential subtractive screening with NSPCs versus their differentiated progenies, we identified the radmis (radial fiber and mitotic spindle)/ckap2l gene, a novel microtubule-associated protein (MAP) enriched in NSPCs. Radmis is a putative substrate for the E3-ubiquitin ligase, anaphase promoting complex/cyclosome (APC/C), and is degraded via the KEN box. Radmis was highly expressed in regions of active neurogenesis throughout life, and its distribution was dynamically regulated during NSPC division. In embryonic and perinatal brains, radmis localized to bipolar mitotic spindles and radial fibers (basal processes) of dividing NSPCs. As central nervous system development proceeded, radmis expression was lost in most brain regions, except for several neurogenic regions. In adult brain, radmis expression persisted in the mitotic spindles of both slowly-dividing stem cells and rapid amplifying progenitors. Overexpression of radmis in vitro induced hyper-stabilization of microtubules, severe defects in mitotic spindle formation, and mitotic arrest. In vivo gain-of-function using in utero electroporation revealed that radmis directed a reduction in NSPC proliferation and a concomitant increase in cell cycle exit, causing a reduction in the Tbr2-positive basal progenitor population and shrinkage of the embryonic subventricular zone. Besides, radmis loss-of-function by shRNAs induced the multipolar mitotic spindle structure, accompanied with the catastrophe of chromosome segregation including the long chromosome bridge between two separating daughter nuclei. These findings uncover the indispensable role of radmis in mitotic spindle formation and cell-cycle progression of NSPCs. PMID:24260314

Cdk1-Cyclin B1-mediated Phosphorylation of Tumor-associated Microtubule-associated Protein/Cytoskeleton-associated Protein 2 in Mitosis*

PubMed Central

Uk Hong, Kyung; Kim, Hyun-Jun; Kim, Hyo-Sil; Seong, Yeon-Sun; Hong, Kyeong-Man; Bae, Chang-Dae; Park, Joobae

2009-01-01

During mitosis, establishment of structurally and functionally sound bipolar spindles is necessary for maintaining the fidelity of chromosome segregation. Tumor-associated microtubule-associated protein (TMAP), also known as cytoskeleton-associated protein 2 (CKAP2), is a mitotic spindle-associated protein whose level is frequently up-regulated in various malignancies. Previous reports have suggested that TMAP is a potential regulator of mitotic spindle assembly and dynamics and that it is required for chromosome segregation to occur properly. So far, there have been no reports on how its mitosis-related functions are regulated. Here, we report that TMAP is hyper-phosphorylated at the C terminus specifically during mitosis. At least four different residues (Thr-578, Thr-596, Thr-622, and Ser-627) were responsible for the mitosis-specific phosphorylation of TMAP. Among these, Thr-622 was specifically phosphorylated by Cdk1-cyclin B1 both in vitro and in vivo. Interestingly, compared with the wild type, a phosphorylation-deficient mutant form of TMAP, in which Thr-622 had been replaced with an alanine (T622A), induced a significant increase in the frequency of metaphase cells with abnormal bipolar spindles, which often displayed disorganized, asymmetrical, or narrow and elongated morphologies. Formation of these abnormal bipolar spindles subsequently resulted in misalignment of metaphase chromosomes and ultimately caused a delay in the entry into anaphase. Moreover, such defects resulting from the T622A mutation were associated with a decrease in the rate of protein turnover at spindle microtubules. These findings suggest that Cdk1-cyclin B1-mediated phosphorylation of TMAP is important for and contributes to proper regulation of microtubule dynamics and establishment of functional bipolar spindles during mitosis. PMID:19369249

Plane of vertebral movement eliciting muscle lengthening history in the low back influences the decrease in muscle spindle responsiveness of the cat

PubMed Central

Ge, Weiqing; Cao, Dong-Yuan; Long, Cynthia R.

2011-01-01

Proprioceptive feedback is thought to play a significant role in controlling both lumbopelvic and intervertebral orientations. In the lumbar spine, a vertebra's positional history along the dorsal-ventral axis has been shown to alter the position, movement, and velocity sensitivity of muscle spindles in the multifidus and longissimus muscles. These effects appear due to muscle history. Because spinal motion segments have up to 6 degrees of freedom for movement, we were interested in whether the axis along which the history is applied differentially affects paraspinal muscle spindles. We tested the null hypothesis that the loading axis, which creates a vertebra's positional history, has no effect on a lumbar muscle spindle's subsequent response to vertebral position or movement. Identical displacements were applied along three orthogonal axes directly at the L6 spinous process using a feedback motor system under displacement control. Single-unit nerve activity was recorded from 60 muscle spindle afferents in teased filaments from L6 dorsal rootlets innervating intact longissimus or multifidus muscles of deeply anesthetized cats. Muscle lengthening histories along the caudal-cranial and dorsal-ventral axis, compared with the left-right axis, produced significantly greater reductions in spindle responses to vertebral position and movement. The spinal anatomy suggested that the effect of a lengthening history is greatest when that history had occurred along an axis lying within the anatomical plane of the facet joint. Speculation is made that the interaction between normal spinal mechanics and the inherent thixotropic property of muscle spindles poses a challenge for feedback and feedforward motor control of the lumbar spine. PMID:21960662

The decreased responsiveness of lumbar muscle spindles to a prior history of spinal muscle lengthening is graded with the magnitude of change in vertebral position

PubMed Central

Ge, Weiqing; Pickar, Joel G.

2013-01-01

In the lumbar spine, muscle spindle responsiveness is affected by the duration and direction of a lumbar vertebra’s positional history. The purpose of the present study was to determine the relationship between changes in the magnitude of a lumbar vertebra’s positional history and the responsiveness of lumbar muscle spindles to a subsequent vertebral position and subsequent vertebral movement. Neural activity from multifidus and longissimus muscle spindle afferents in deeply anesthetized cats was recorded while creating positional histories of the L6 vertebra. History was induced using a displacement-controlled feedback motor. It held the L6 vertebra for 4 seconds at an intermediate position (hold-intermediate at 0mm) and at 7 positions from 0.07 to 1.55mm more ventralward and dorsalward which lengthened (hold-long) and shortened (hold-short) the lumbar muscles. Following the conditioning hold positions, L6 was returned to the intermediate position. Muscle spindle discharge at this position and during a lengthening movement was compared between hold-intermediate and hold-short conditionings and between hold-intermediate and hold-short conditionings. We found that regardless of conditioning magnitude, the 7 shortening magnitudes similarly increased muscle spindle responsiveness to both vertebral position and movement. In contrast, the 7 lengthening magnitudes produced a graded decrease in responsiveness to both position and movement. The decrease to position became maximal following conditioning magnitudes of ~0.75 mm. The decrease to movement did not reach a maximum even with conditioning magnitudes of ~1.55 mm. The data suggest that the fidelity of proprioceptive information from muscle spindles in the low back is influenced by small changes in the previous length history of lumbar muscles. PMID:22721784

Spindle assembly in the oocytes of mouse and Drosophila--similar solutions to a problem.

PubMed

Doubilet, Susan; McKim, Kim S

2007-01-01

In the oocytes of many organisms a bipolar spindle is assembled in the absence of centrosomes. In this article we review how this occurs in two model organisms, Drosophila melanogaster and Mus musculus. Common themes include an important role for the chromosomes but paradoxically, organization of a bipolar spindle may not involve kinetochore microtubules. Some comparisons are not yet possible, however, since the same genes have usually not been studied in both systems.

Spindle disturbances in human-hamster hybrid (AL) cells induced by mobile communication frequency range signals.

PubMed

Schrader, Thorsten; Münter, Klaus; Kleine-Ostmann, Thomas; Schmid, Ernst

2008-12-01

The production of spindle disturbances in FC2 cells, a human-hamster hybrid (A(L)) cell line, by non-ionizing radiation was studied using an electromagnetic field with a field strength of 90 V/m at a frequency of 835 MHz. Due to the given experimental conditions slide flask cultures were exposed at room temperature in a microTEM (transversal electromagnetic field) cell, which allows optimal experimental conditions for small samples of biological material. Numerical calculations suggest that specific absorption rates of up to 60 mW/kg are reached for maximum field exposure. All exposure field parameters--either measured or calculable--are precisely defined and, for the first time, traceable to the standards of the SI system of physical units. Compared with co-incident negative controls, the results of two independently performed experiments suggest that exposure periods of time from 0.5 to 2 h with an electric field strength of 90 V/m are spindle acting agents as predominately indicated by the appearance of spindle disturbances at the ana- and telophase stages (especially lagging and non-disjunction of single chromosomes) of cell divisions. The spindle disturbances do not change the fraction of mitotic cells with increasing exposure time up to 2 h. Due to the applied experimental conditions an influence of temperature as a confounder parameter for spindle disturbances can be excluded.

Dissecting the Function and Assembly of Acentriolar Microtubule Organizing Centers in Drosophila Cells In Vivo

PubMed Central

Baumbach, Janina; Novak, Zsofia Anna; Raff, Jordan W.; Wainman, Alan

2015-01-01

Acentriolar microtubule organizing centers (aMTOCs) are formed during meiosis and mitosis in several cell types, but their function and assembly mechanism is unclear. Importantly, aMTOCs can be overactive in cancer cells, enhancing multipolar spindle formation, merotelic kinetochore attachment and aneuploidy. Here we show that aMTOCs can form in acentriolar Drosophila somatic cells in vivo via an assembly pathway that depends on Asl, Cnn and, to a lesser extent, Spd-2—the same proteins that appear to drive mitotic centrosome assembly in flies. This finding enabled us to ablate aMTOC formation in acentriolar cells, and so perform a detailed genetic analysis of the contribution of aMTOCs to acentriolar mitotic spindle formation. Here we show that although aMTOCs can nucleate microtubules, they do not detectably increase the efficiency of acentriolar spindle assembly in somatic fly cells. We find that they are required, however, for robust microtubule array assembly in cells without centrioles that also lack microtubule nucleation from around the chromatin. Importantly, aMTOCs are also essential for dynein-dependent acentriolar spindle pole focusing and for robust cell proliferation in the absence of centrioles and HSET/Ncd (a kinesin essential for acentriolar spindle pole focusing in many systems). We propose an updated model for acentriolar spindle pole coalescence by the molecular motors Ncd/HSET and dynein in conjunction with aMTOCs. PMID:26020779

SSC Geopositional Assessment of the Advanced Wide Field Sensor

NASA Technical Reports Server (NTRS)

Ross, Kenton

2007-01-01

The objective is to provide independent verification of IRS geopositional accuracy claims and of the internal geopositional characterization provided by Lutes (2005). Six sub-scenes (quads) were assessed; Three from each AWiFS camera. Check points were manually matched to digital orthophoto quarter quadrangle (DOQQ) reference (assumed accuracy approx. 5 m, RMSE) Check points were selected to meet or exceed Federal Geographic Data Committee's guidelines. Used ESRI ArcGIS for data collection and SSC-written MATLAB scripts for data analysis.

Sequential actin-based pushing forces drive meiosis I chromosome migration and symmetry breaking in oocytes.

PubMed

Yi, Kexi; Rubinstein, Boris; Unruh, Jay R; Guo, Fengli; Slaughter, Brian D; Li, Rong

2013-03-04

Polar body extrusion during oocyte maturation is critically dependent on asymmetric positioning of the meiotic spindle, which is established through migration of the meiosis I (MI) spindle/chromosomes from the oocyte interior to a subcortical location. In this study, we show that MI chromosome migration is biphasic and driven by consecutive actin-based pushing forces regulated by two actin nucleators, Fmn2, a formin family protein, and the Arp2/3 complex. Fmn2 was recruited to endoplasmic reticulum structures surrounding the MI spindle, where it nucleated actin filaments to initiate an initially slow and poorly directed motion of the spindle away from the cell center. A fast and highly directed second migration phase was driven by actin-mediated cytoplasmic streaming and occurred as the chromosomes reach a sufficient proximity to the cortex to activate the Arp2/3 complex. We propose that decisive symmetry breaking in mouse oocytes results from Fmn2-mediated perturbation of spindle position and the positive feedback loop between chromosome signal-induced Arp2/3 activation and Arp2/3-orchestrated cytoplasmic streaming that transports the chromosomes.

Sequential actin-based pushing forces drive meiosis I chromosome migration and symmetry breaking in oocytes

PubMed Central

Yi, Kexi; Rubinstein, Boris; Unruh, Jay R.; Guo, Fengli; Slaughter, Brian D.

2013-01-01

Polar body extrusion during oocyte maturation is critically dependent on asymmetric positioning of the meiotic spindle, which is established through migration of the meiosis I (MI) spindle/chromosomes from the oocyte interior to a subcortical location. In this study, we show that MI chromosome migration is biphasic and driven by consecutive actin-based pushing forces regulated by two actin nucleators, Fmn2, a formin family protein, and the Arp2/3 complex. Fmn2 was recruited to endoplasmic reticulum structures surrounding the MI spindle, where it nucleated actin filaments to initiate an initially slow and poorly directed motion of the spindle away from the cell center. A fast and highly directed second migration phase was driven by actin-mediated cytoplasmic streaming and occurred as the chromosomes reach a sufficient proximity to the cortex to activate the Arp2/3 complex. We propose that decisive symmetry breaking in mouse oocytes results from Fmn2-mediated perturbation of spindle position and the positive feedback loop between chromosome signal-induced Arp2/3 activation and Arp2/3-orchestrated cytoplasmic streaming that transports the chromosomes. PMID:23439682

An astral simulacrum of the central spindle accounts for normal, spindle-less, and anucleate cytokinesis in echinoderm embryos

PubMed Central

Su, Kuan-Chung; Bement, William M.; Petronczki, Mark; von Dassow, George

2014-01-01

Cytokinesis in animal cells depends on spindle-derived spatial cues that culminate in Rho activation, and thereby actomyosin assembly, in a narrow equatorial band. Although the nature, origin, and variety of such cues have long been obscure, one component is certainly the Rho activator Ect2. Here we describe the behavior and function of Ect2 in echinoderm embryos, showing that Ect2 migrates from spindle midzone to astral microtubules in anaphase and that Ect2 shapes the pattern of Rho activation in incipient furrows. Our key finding is that Ect2 and its binding partner Cyk4 accumulate not only at normal furrows, but also at furrows that form in the absence of associated spindle, midzone, or chromosomes. In all these cases, the cell assembles essentially the same cytokinetic signaling ensemble—opposed astral microtubules decorated with Ect2 and Cyk4. We conclude that if multiple signals contribute to furrow induction in echinoderm embryos, they likely converge on the same signaling ensemble on an analogous cytoskeletal scaffold. PMID:25298401

Arsenite inhibits mitotic division and perturbs spindle dynamics in HeLa S3 cells.

PubMed

Huang, S C; Lee, T C

1998-05-01

Arsenical compounds, known to be human carcinogens, were shown to disturb cell cycle progression and induce cytogenetic alterations in a variety of cell systems. We report here that a 24 h treatment of arsenite induced mitotic accumulation in human cell lines. HeLa S3 and KB cells were most susceptible: 35% of the total cell population was arrested at the mitotic stage after treatment with 5 microM sodium arsenite in HeLa S3 cells and after 10 microM in KB cells. Under a microscope, we observed abnormal mitotic figures in arsenite-arrested mitotic cells, including deranged chromosome congression, elongated polar distance of mitotic spindle, and enhanced microtubule immunofluorescence. The spindle microtubules of arsenite-arrested mitotic cells were more resistant to nocodazole-induced dissolution than those of control mitotic cells. According to turbidity assay, arsenite at concentrations below 100 microM significantly enhanced polymerization of tubulins. Since spindle dynamics play a crucial role in mitotic progression, our results suggest that arsenite-induced mitotic arrest may be due to arsenite's effects on attenuation of spindle dynamics.

Spindle speed variation technique in turning operations: Modeling and real implementation

NASA Astrophysics Data System (ADS)

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.

A cytokinesis checkpoint requiring the yeast homologue of an APC-binding protein

PubMed Central

Muhua, Li; Adames, Neil R.; Murphy, Michael D.; Shields, Colleen R.; Cooper, John A.

2008-01-01

Checkpoint controls ensure that events of the cell-division cycle are completed with fidelity and in the correct order. In budding yeast with a mutation in the motor protein dynein, the mitotic spindle is often misaligned and therefore slow to enter the neck between mother cell and budding daughter cell. When this occurs, cytokinesis (division of the cytoplasm into two) is delayed until the spindle is properly positioned1. Here we describe mutations that abolish this delay, indicating the existence of a new checkpoint mechanism. One mutation lies in the gene encoding the yeast homologue of EB1, a human protein that binds the adenomatous polyposis coli (APC) protein, a tumour suppressor. EB1 is located on microtubules of the mitotic spindle and is important in spindle assembly. EB1 may therefore, by associating with microtubules, contribute to the sensor mechanism that activates the checkpoint. Another mutation affects Stt4, a phosphatidylinositol-4-OH kinase. Cold temperature is an environmental stimulus that causes misalignment of the mitotic spindle in yeast and appears to activate this checkpoint mechanism. PMID:9624007

The expression patterns of bromelain and AcCYS1 correlate with blackheart resistance in pineapple fruits submitted to postharvest chilling stress.

PubMed

Raimbault, Astrid-Kim; Zuily-Fodil, Yasmine; Soler, Alain; Mora, Phillipe; Cruz de Carvalho, Maria H

2013-11-01

Blackheart is a physiological disorder induced by postharvest chilling storage during pineapple fruit export shipping. The aim of this study was to check the involvement of bromelain, the cysteine protease protein family abundantly present in pineapple fruits, and AcCYS1, an endogenous inhibitor of bromelain, in the development of blackheart. For this we checked the response to postharvest chilling treatment of two pineapple varieties (MD2 and Smooth Cayenne) differing in their resistance to blackheart. Quantitative RT-PCR analyses showed that postharvest chilling treatment induced a down-regulation of bromelain transcript accumulation in both varieties with the most dramatic drop in the resistant variety. Regarding AcCYS1 transcript accumulation, the varieties showed opposite trends with an up-regulation in the case of the resistant variety and a down-regulation in the susceptible one. Taken together our results suggest that the control of bromelain and AcCYS1 expression levels directly correlates to the resistance to blackheart development in pineapple fruits. Copyright © 2013 Elsevier GmbH. All rights reserved.

Program Model Checking: A Practitioner's Guide

NASA Technical Reports Server (NTRS)

Pressburger, Thomas T.; Mansouri-Samani, Masoud; Mehlitz, Peter C.; Pasareanu, Corina S.; Markosian, Lawrence Z.; Penix, John J.; Brat, Guillaume P.; Visser, Willem C.

2008-01-01

Program model checking is a verification technology that uses state-space exploration to evaluate large numbers of potential program executions. Program model checking provides improved coverage over testing by systematically evaluating all possible test inputs and all possible interleavings of threads in a multithreaded system. Model-checking algorithms use several classes of optimizations to reduce the time and memory requirements for analysis, as well as heuristics for meaningful analysis of partial areas of the state space Our goal in this guidebook is to assemble, distill, and demonstrate emerging best practices for applying program model checking. We offer it as a starting point and introduction for those who want to apply model checking to software verification and validation. The guidebook will not discuss any specific tool in great detail, but we provide references for specific tools.

Connections between Transcription Downstream of Genes and cis-SAGe Chimeric RNA.

PubMed

Chwalenia, Katarzyna; Qin, Fujun; Singh, Sandeep; Tangtrongstittikul, Panjapon; Li, Hui

2017-11-22

cis-Splicing between adjacent genes (cis-SAGe) is being recognized as one way to produce chimeric fusion RNAs. However, its detail mechanism is not clear. Recent study revealed induction of transcriptions downstream of genes (DoGs) under osmotic stress. Here, we investigated the influence of osmotic stress on cis-SAGe chimeric RNAs and their connection to DoGs. We found,the absence of induction of at least some cis-SAGe fusions and/or their corresponding DoGs at early time point(s). In fact, these DoGs and their cis-SAGe fusions are inversely correlated. This negative correlation was changed to positive at a later time point. These results suggest a direct competition between the two categories of transcripts when total pool of readthrough transcripts is limited at an early time point. At a later time point, DoGs and corresponding cis-SAGe fusions are both induced, indicating that total readthrough transcripts become more abundant. Finally, we observed overall enhancement of cis-SAGe chimeric RNAs in KCl-treated samples by RNA-Seq analysis.

Systems cell biology of the mitotic spindle.

PubMed

Saleem, Ramsey A; Aitchison, John D

2010-01-11

Cell division depends critically on the temporally controlled assembly of mitotic spindles, which are responsible for the distribution of duplicated chromosomes to each of the two daughter cells. To gain insight into the process, Vizeacoumar et al., in this issue (Vizeacoumar et al. 2010. J. Cell Biol. doi:10.1083/jcb.200909013), have combined systems genetics with high-throughput and high-content imaging to comprehensively identify and classify novel components that contribute to the morphology and function of the mitotic spindle.

The Concept of Electrically Assisted Friction Stir Welding (EAFSW) and Application to the Processing of Various Metals

DTIC Science & Technology

2008-09-01

unavailability of a precise load cell. This scale was set on the machine working table. Since the shaft spindle had been placed in fixed vertical...4 Figure 4. Mill Spindle with Slip Ring and Brush Assembly, Weld Tip is in W orking Position...areas . FSW of HSLA 65 and Type 304L Processing Parameter HSLA-65 304L Spindle Speed (RPM) 850 850 Travel Speed (ipm) 6 2 Z-Load (Ibs) 3500 3500

Truth of Varying Shades: Analyzing Language in Fake News and Political Fact-Checking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rashkin, Hannah J.; Choi, Eunsol; Jang, Jin Yea

We present an analytic study on the language of news media in the context of political fact-checking and fake news detection. We compare the language of real news with that of satire, hoax, and propaganda to find linguistic cues for untruthful text. To probe the feasibility of automatic political fact-checking, we present a case study based on PolitiFact.com using their factuality judgments on a 6-point scale. Experimental results show that while media fact-checking remains to be an open research question, stylistic cues can help determine the truthfulness of text.

Sulfolobus Spindle-Shaped Virus 1 Contains Glycosylated Capsid Proteins, a Cellular Chromatin Protein, and Host-Derived Lipids

PubMed Central

Quemin, Emmanuelle R. J.; Pietilä, Maija K.; Oksanen, Hanna M.; Forterre, Patrick; Rijpstra, W. Irene C.; Schouten, Stefan; Bamford, Dennis H.; Prangishvili, David

2015-01-01

ABSTRACT Geothermal and hypersaline environments are rich in virus-like particles, among which spindle-shaped morphotypes dominate. Currently, viruses with spindle- or lemon-shaped virions are exclusive to Archaea and belong to two distinct viral families. The larger of the two families, the Fuselloviridae, comprises tail-less, spindle-shaped viruses, which infect hosts from phylogenetically distant archaeal lineages. Sulfolobus spindle-shaped virus 1 (SSV1) is the best known member of the family and was one of the first hyperthermophilic archaeal viruses to be isolated. SSV1 is an attractive model for understanding virus-host interactions in Archaea; however, the constituents and architecture of SSV1 particles remain only partially characterized. Here, we have conducted an extensive biochemical characterization of highly purified SSV1 virions and identified four virus-encoded structural proteins, VP1 to VP4, as well as one DNA-binding protein of cellular origin. The virion proteins VP1, VP3, and VP4 undergo posttranslational modification by glycosylation, seemingly at multiple sites. VP1 is also proteolytically processed. In addition to the viral DNA-binding protein VP2, we show that viral particles contain the Sulfolobus solfataricus chromatin protein Sso7d. Finally, we provide evidence indicating that SSV1 virions contain glycerol dibiphytanyl glycerol tetraether (GDGT) lipids, resolving a long-standing debate on the presence of lipids within SSV1 virions. A comparison of the contents of lipids isolated from the virus and its host cell suggests that GDGTs are acquired by the virus in a selective manner from the host cytoplasmic membrane, likely during progeny egress. IMPORTANCE Although spindle-shaped viruses represent one of the most prominent viral groups in Archaea, structural data on their virion constituents and architecture still are scarce. The comprehensive biochemical characterization of the hyperthermophilic virus SSV1 presented here brings novel and significant insights into the organization and architecture of spindle-shaped virions. The obtained data permit the comparison between spindle-shaped viruses residing in widely different ecological niches, improving our understanding of the adaptation of viruses with unusual morphotypes to extreme environmental conditions. PMID:26355093

Distribution of TTX-sensitive voltage-gated sodium channels in primary sensory endings of mammalian muscle spindles.

PubMed

Carrasco, Dario I; Vincent, Jacob A; Cope, Timothy C

2017-04-01

Knowledge of the molecular mechanisms underlying signaling of mechanical stimuli by muscle spindles remains incomplete. In particular, the ionic conductances that sustain tonic firing during static muscle stretch are unknown. We hypothesized that tonic firing by spindle afferents depends on sodium persistent inward current (INaP) and tested for the necessary presence of the appropriate voltage-gated sodium (NaV) channels in primary sensory endings. The NaV 1.6 isoform was selected for both its capacity to produce INaP and for its presence in other mechanosensors that fire tonically. The present study shows that NaV 1.6 immunoreactivity (IR) is concentrated in heminodes, presumably where tonic firing is generated, and we were surprised to find NaV 1.6 IR strongly expressed also in the sensory terminals, where mechanotransduction occurs. This spatial pattern of NaV 1.6 IR distribution was consistent for three mammalian species (rat, cat, and mouse), as was tonic firing by primary spindle afferents. These findings meet some of the conditions needed to establish participation of INaP in tonic firing by primary sensory endings. The study was extended to two additional NaV isoforms, selected for their sensitivity to TTX, excluding TTX-resistant NaV channels, which alone are insufficient to support firing by primary spindle endings. Positive immunoreactivity was found for NaV 1.1 , predominantly in sensory terminals together with NaV 1.6 and for NaV 1.7 , mainly in preterminal axons. Differential distribution in primary sensory endings suggests specialized roles for these three NaV isoforms in the process of mechanosensory signaling by muscle spindles. NEW & NOTEWORTHY The molecular mechanisms underlying mechanosensory signaling responsible for proprioceptive functions are not completely elucidated. This study provides the first evidence that voltage-gated sodium channels (NaVs) are expressed in the spindle primary sensory ending, where NaVs are found at every site involved in transduction or encoding of muscle stretch. We propose that NaVs contribute to multiple steps in sensory signaling by muscle spindles as it does in other types of slowly adapting sensory neurons. Copyright © 2017 the American Physiological Society.

Re-Computation of Numerical Results Contained in NACA Report No. 496

NASA Technical Reports Server (NTRS)

Perry, Boyd, III

2015-01-01

An extensive examination of NACA Report No. 496 (NACA 496), "General Theory of Aerodynamic Instability and the Mechanism of Flutter," by Theodore Theodorsen, is described. The examination included checking equations and solution methods and re-computing interim quantities and all numerical examples in NACA 496. The checks revealed that NACA 496 contains computational shortcuts (time- and effort-saving devices for engineers of the time) and clever artifices (employed in its solution methods), but, unfortunately, also contains numerous tripping points (aspects of NACA 496 that have the potential to cause confusion) and some errors. The re-computations were performed employing the methods and procedures described in NACA 496, but using modern computational tools. With some exceptions, the magnitudes and trends of the original results were in fair-to-very-good agreement with the re-computed results. The exceptions included what are speculated to be computational errors in the original in some instances and transcription errors in the original in others. Independent flutter calculations were performed and, in all cases, including those where the original and re-computed results differed significantly, were in excellent agreement with the re-computed results. Appendix A contains NACA 496; Appendix B contains a Matlab(Reistered) program that performs the re-computation of results; Appendix C presents three alternate solution methods, with examples, for the two-degree-of-freedom solution method of NACA 496; Appendix D contains the three-degree-of-freedom solution method (outlined in NACA 496 but never implemented), with examples.

An analytical method for prediction of stability lobes diagram of milling of large-size thin-walled workpiece

NASA Astrophysics Data System (ADS)

Yao, Jiming; Lin, Bin; Guo, Yu

2017-01-01

Different from common thin-walled workpiece, in the process of milling of large-size thin-walled workpiece chatter in the axial direction along the spindle is also likely to happen because of the low stiffness of the workpiece in this direction. An analytical method for prediction of stability lobes of milling of large-size thin-walled workpiece is presented in this paper. In the method, not only frequency response function of the tool point but also frequency response function of the workpiece is considered.

Verification and Planning Based on Coinductive Logic Programming

NASA Technical Reports Server (NTRS)

Bansal, Ajay; Min, Richard; Simon, Luke; Mallya, Ajay; Gupta, Gopal

2008-01-01

Coinduction is a powerful technique for reasoning about unfounded sets, unbounded structures, infinite automata, and interactive computations [6]. Where induction corresponds to least fixed point's semantics, coinduction corresponds to greatest fixed point semantics. Recently coinduction has been incorporated into logic programming and an elegant operational semantics developed for it [11, 12]. This operational semantics is the greatest fix point counterpart of SLD resolution (SLD resolution imparts operational semantics to least fix point based computations) and is termed co- SLD resolution. In co-SLD resolution, a predicate goal p( t) succeeds if it unifies with one of its ancestor calls. In addition, rational infinite terms are allowed as arguments of predicates. Infinite terms are represented as solutions to unification equations and the occurs check is omitted during the unification process. Coinductive Logic Programming (Co-LP) and Co-SLD resolution can be used to elegantly perform model checking and planning. A combined SLD and Co-SLD resolution based LP system forms the common basis for planning, scheduling, verification, model checking, and constraint solving [9, 4]. This is achieved by amalgamating SLD resolution, co-SLD resolution, and constraint logic programming [13] in a single logic programming system. Given that parallelism in logic programs can be implicitly exploited [8], complex, compute-intensive applications (planning, scheduling, model checking, etc.) can be executed in parallel on multi-core machines. Parallel execution can result in speed-ups as well as in larger instances of the problems being solved. In the remainder we elaborate on (i) how planning can be elegantly and efficiently performed under real-time constraints, (ii) how real-time systems can be elegantly and efficiently model- checked, as well as (iii) how hybrid systems can be verified in a combined system with both co-SLD and SLD resolution. Implementations of co-SLD resolution as well as preliminary implementations of the planning and verification applications have been developed [4]. Co-LP and Model Checking: The vast majority of properties that are to be verified can be classified into safety properties and liveness properties. It is well known within model checking that safety properties can be verified by reachability analysis, i.e, if a counter-example to the property exists, it can be finitely determined by enumerating all the reachable states of the Kripke structure.

Chromosome movement in lysed mitotic cells is inhibited by vanadate

PubMed Central

1978-01-01

Mitotic PtK1 cells, lysed at anaphase into a carbowax 20 M Brij 58 solution, continue to move chromosomes toward the spindle poles and to move the spindle poles apart at 50% in vivo rates for 10 min. Chromosome movements can be blocked by adding metabolic inhibitors to the lysis medium and inhibition of movement can be reversed by adding ATP to the medium. Vanadate at micromolar levels reversibly inhibits dynein ATPase activity and movement of demembranated flagella and cilia. It does not affect glycerinated myofibril contraction or myosin ATPase activty at less than millimolar concentrations. Vanadate at 10-- 100 micron reversibly inhibits anaphase movement of chromosomes and spindle elongation. After lysis in vanadate, spindles lose their fusiform appearance and become more barrel shaped. In vitro microtubule polymerization is insensitive to vanadate. PMID:152767

Changes in muscle spindle firing in response to length changes of neighboring muscles

PubMed Central

Smilde, Hiltsje A.; Vincent, Jake A.; Baan, Guus C.; Nardelli, Paul; Lodder, Johannes C.; Mansvelder, Huibert D.; Cope, Tim C.

2016-01-01

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. PMID:27075540

Dynamic distribution of spindlin in nucleoli, nucleoplasm and spindle from primary oocytes to mature eggs and its critical function for oocyte-to-embryo transition in gibel carp.

PubMed

Sun, Min; Li, Zhi; Gui, Jian-Fang

2010-10-01

Spindlin (Spin) was thought as a maternal-effect factor associated with meiotic spindle. Its role for the oocyte-to-embryo transition was suggested in mouse, but its direct evidence for the function had been not obtained in other vertebrates. In this study, we used the CagSpin-specific antibody to investigate CagSpin expression pattern and distribution during oogenesis of gibel carp (Carassius auratus gibelio). First, the oocyte-specific expression pattern and dynamic distribution was revealed in nucleoli, nucleoplasm, and spindle from primary oocytes to mature eggs by immunofluorescence localization. In primary oocytes and growth stage oocytes, CagSpin accumulates in nucleoli in increasing numbers along with the oocyte growth, and its disassembly occurs in vitellogenic oocytes, which implicates that CagSpin may be a major component of a large number of nucleoli in fish growth oocytes. Then, co-localization of CagSpin and β-tubulin was revealed in meiotic spindle of mature egg, indicating that CagSpin is one spindle-associated factor. Moreover, microinjection of CagSpin-specific antibody into the fertilized eggs blocked the first cleavage, and found that the CagSpin depletion resulted in spindle assembly disturbance. Thereby, our study provided the first direct evidence for the critical oocyte-to-embryo transition function of Spin in vertebrates, and confirmed that Spin is one important maternal-effect factor that participates in oocyte growth, oocyte maturation, and oocyte-to-embryo transition.

Spindle neurons of the human anterior cingulate cortex

NASA Technical Reports Server (NTRS)

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.

Anaphase B

PubMed Central

Scholey, Jonathan M.; Civelekoglu-Scholey, Gul; Brust-Mascher, Ingrid

2016-01-01

Anaphase B spindle elongation is characterized by the sliding apart of overlapping antiparallel interpolar (ip) microtubules (MTs) as the two opposite spindle poles separate, pulling along disjoined sister chromatids, thereby contributing to chromosome segregation and the propagation of all cellular life. The major biochemical “modules” that cooperate to mediate pole–pole separation include: (i) midzone pushing or (ii) braking by MT crosslinkers, such as kinesin-5 motors, which facilitate or restrict the outward sliding of antiparallel interpolar MTs (ipMTs); (iii) cortical pulling by disassembling astral MTs (aMTs) and/or dynein motors that pull aMTs outwards; (iv) ipMT plus end dynamics, notably net polymerization; and (v) ipMT minus end depolymerization manifest as poleward flux. The differential combination of these modules in different cell types produces diversity in the anaphase B mechanism. Combinations of antagonist modules can create a force balance that maintains the dynamic pre-anaphase B spindle at constant length. Tipping such a force balance at anaphase B onset can initiate and control the rate of spindle elongation. The activities of the basic motor filament components of the anaphase B machinery are controlled by a network of non-motor MT-associated proteins (MAPs), for example the key MT cross-linker, Ase1p/PRC1, and various cell-cycle kinases, phosphatases, and proteases. This review focuses on the molecular mechanisms of anaphase B spindle elongation in eukaryotic cells and briefly mentions bacterial DNA segregation systems that operate by spindle elongation. PMID:27941648

A Role for the Chaperone Complex BAG3-HSPB8 in Actin Dynamics, Spindle Orientation and Proper Chromosome Segregation during Mitosis

PubMed Central

Fuchs, Margit; Lambert, Herman; Jetté, Alexandra; Elowe, Sabine; Landry, Jacques; Lavoie, Josée N.

2015-01-01

The co-chaperone BAG3, in complex with the heat shock protein HSPB8, plays a role in protein quality control during mechanical strain. It is part of a multichaperone complex that senses damaged cytoskeletal proteins and orchestrates their seclusion and/or degradation by selective autophagy. Here we describe a novel role for the BAG3-HSPB8 complex in mitosis, a process involving profound changes in cell tension homeostasis. BAG3 is hyperphosphorylated at mitotic entry and localizes to centrosomal regions. BAG3 regulates, in an HSPB8-dependent manner, the timely congression of chromosomes to the metaphase plate by influencing the three-dimensional positioning of the mitotic spindle. Depletion of BAG3 caused defects in cell rounding at metaphase and dramatic blebbing of the cortex associated with abnormal spindle rotations. Similar defects were observed upon silencing of the autophagic receptor p62/SQSTM1 that contributes to BAG3-mediated selective autophagy pathway. Mitotic cells depleted of BAG3, HSPB8 or p62/SQSTM1 exhibited disorganized actin-rich retraction fibres, which are proposed to guide spindle orientation. Proper spindle positioning was rescued in BAG3-depleted cells upon addition of the lectin concanavalin A, which restores cortex rigidity. Together, our findings suggest the existence of a so-far unrecognized quality control mechanism involving BAG3, HSPB8 and p62/SQSTM1 for accurate remodelling of actin-based mitotic structures that guide spindle orientation. PMID:26496431

P21-activated kinase 4 (PAK4) is required for metaphase spindle positioning and anchoring.

PubMed

Bompard, G; Rabeharivelo, G; Cau, J; Abrieu, A; Delsert, C; Morin, N

2013-02-14

The oncogenic kinase PAK4 was recently found to be involved in the regulation of the G1 phase and the G2/M transition of the cell cycle. We have also identified that PAK4 regulates Ran GTPase activity during mitosis. Here, we show that after entering mitosis, PAK4-depleted cells maintain a prolonged metaphase-like state. In these cells, chromosome congression to the metaphase plate occurs with normal kinetics but is followed by an extended period during which membrane blebbing and spindle rotation are observed. These bipolar PAK4-depleted metaphase-like spindles have a defective astral microtubule (MT) network and are not centered in the cell but are in close contact with the cell cortex. As the metaphase-like state persists, centrosome fragmentation occurs, chromosomes scatter from the metaphase plate and move toward the spindle poles with an active spindle assembly checkpoint, a phenotype that is reminiscent of cohesion fatigue. PAK4 also regulates the acto-myosin cytoskeleton and we report that PAK4 depletion results in the induction of cortical membrane blebbing during prometaphase arrest. However, we show that membrane blebs, which are strongly enriched in phospho-cofilin, are not responsible for the poor anchoring of the spindle. As PAK4 depletion interferes with the localization of components of the dynein/dynactin complexes at the kinetochores and on the astral MTs, we propose that loss of PAK4 could induce a change in the activities of motor proteins.

A Role for the Chaperone Complex BAG3-HSPB8 in Actin Dynamics, Spindle Orientation and Proper Chromosome Segregation during Mitosis.

PubMed

Fuchs, Margit; Luthold, Carole; Guilbert, Solenn M; Varlet, Alice Anaïs; Lambert, Herman; Jetté, Alexandra; Elowe, Sabine; Landry, Jacques; Lavoie, Josée N

2015-10-01

The co-chaperone BAG3, in complex with the heat shock protein HSPB8, plays a role in protein quality control during mechanical strain. It is part of a multichaperone complex that senses damaged cytoskeletal proteins and orchestrates their seclusion and/or degradation by selective autophagy. Here we describe a novel role for the BAG3-HSPB8 complex in mitosis, a process involving profound changes in cell tension homeostasis. BAG3 is hyperphosphorylated at mitotic entry and localizes to centrosomal regions. BAG3 regulates, in an HSPB8-dependent manner, the timely congression of chromosomes to the metaphase plate by influencing the three-dimensional positioning of the mitotic spindle. Depletion of BAG3 caused defects in cell rounding at metaphase and dramatic blebbing of the cortex associated with abnormal spindle rotations. Similar defects were observed upon silencing of the autophagic receptor p62/SQSTM1 that contributes to BAG3-mediated selective autophagy pathway. Mitotic cells depleted of BAG3, HSPB8 or p62/SQSTM1 exhibited disorganized actin-rich retraction fibres, which are proposed to guide spindle orientation. Proper spindle positioning was rescued in BAG3-depleted cells upon addition of the lectin concanavalin A, which restores cortex rigidity. Together, our findings suggest the existence of a so-far unrecognized quality control mechanism involving BAG3, HSPB8 and p62/SQSTM1 for accurate remodelling of actin-based mitotic structures that guide spindle orientation.

Parameter Estimation of the Thermal Network Model of a Machine Tool Spindle by Self-made Bluetooth Temperature Sensor Module

PubMed Central

Lo, Yuan-Chieh; Hu, Yuh-Chung; Chang, Pei-Zen

2018-01-01

Thermal characteristic analysis is essential for machine tool spindles because sudden failures may occur due to unexpected thermal issue. This article presents a lumped-parameter Thermal Network Model (TNM) and its parameter estimation scheme, including hardware and software, in order to characterize both the steady-state and transient thermal behavior of machine tool spindles. For the hardware, the authors develop a Bluetooth Temperature Sensor Module (BTSM) which accompanying with three types of temperature-sensing probes (magnetic, screw, and probe). Its specification, through experimental test, achieves to the precision ±(0.1 + 0.0029|t|) °C, resolution 0.00489 °C, power consumption 7 mW, and size Ø40 mm × 27 mm. For the software, the heat transfer characteristics of the machine tool spindle correlative to rotating speed are derived based on the theory of heat transfer and empirical formula. The predictive TNM of spindles was developed by grey-box estimation and experimental results. Even under such complicated operating conditions as various speeds and different initial conditions, the experiments validate that the present modeling methodology provides a robust and reliable tool for the temperature prediction with normalized mean square error of 99.5% agreement, and the present approach is transferable to the other spindles with a similar structure. For realizing the edge computing in smart manufacturing, a reduced-order TNM is constructed by Model Order Reduction (MOR) technique and implemented into the real-time embedded system. PMID:29473877

Parameter Estimation of the Thermal Network Model of a Machine Tool Spindle by Self-made Bluetooth Temperature Sensor Module.

PubMed

Lo, Yuan-Chieh; Hu, Yuh-Chung; Chang, Pei-Zen

2018-02-23

Thermal characteristic analysis is essential for machine tool spindles because sudden failures may occur due to unexpected thermal issue. This article presents a lumped-parameter Thermal Network Model (TNM) and its parameter estimation scheme, including hardware and software, in order to characterize both the steady-state and transient thermal behavior of machine tool spindles. For the hardware, the authors develop a Bluetooth Temperature Sensor Module (BTSM) which accompanying with three types of temperature-sensing probes (magnetic, screw, and probe). Its specification, through experimental test, achieves to the precision ±(0.1 + 0.0029|t|) °C, resolution 0.00489 °C, power consumption 7 mW, and size Ø40 mm × 27 mm. For the software, the heat transfer characteristics of the machine tool spindle correlative to rotating speed are derived based on the theory of heat transfer and empirical formula. The predictive TNM of spindles was developed by grey-box estimation and experimental results. Even under such complicated operating conditions as various speeds and different initial conditions, the experiments validate that the present modeling methodology provides a robust and reliable tool for the temperature prediction with normalized mean square error of 99.5% agreement, and the present approach is transferable to the other spindles with a similar structure. For realizing the edge computing in smart manufacturing, a reduced-order TNM is constructed by Model Order Reduction (MOR) technique and implemented into the real-time embedded system.

A new method for measuring the rotational accuracy of rolling element bearings

NASA Astrophysics Data System (ADS)

Chen, Ye; Zhao, Xiangsong; Gao, Weiguo; Hu, Gaofeng; Zhang, Shizhen; Zhang, Dawei

2016-12-01

The rotational accuracy of a machine tool spindle has critical influence upon the geometric shape and surface roughness of finished workpiece. The rotational performance of the rolling element bearings is a main factor which affects the spindle accuracy, especially in the ultra-precision machining. In this paper, a new method is developed to measure the rotational accuracy of rolling element bearings of machine tool spindles. Variable and measurable axial preload is applied to seat the rolling elements in the bearing races, which is used to simulate the operating conditions. A high-precision (radial error is less than 300 nm) and high-stiffness (radial stiffness is 600 N/μm) hydrostatic reference spindle is adopted to rotate the inner race of the test bearing. To prevent the outer race from rotating, a 2-degrees of freedom flexure hinge mechanism (2-DOF FHM) is designed. Correction factors by using stiffness analysis are adopted to eliminate the influences of 2-DOF FHM in the radial direction. Two capacitive displacement sensors with nano-resolution (the highest resolution is 9 nm) are used to measure the radial error motion of the rolling element bearing, without separating the profile error as the traditional rotational accuracy metrology of the spindle. Finally, experimental measurements are performed at different spindle speeds (100-4000 rpm) and axial preloads (75-780 N). Synchronous and asynchronous error motion values are evaluated to demonstrate the feasibility and repeatability of the developed method and instrument.

Two spatially distinct kinesin-14 proteins, Pkl1 and Klp2, generate collaborative inward forces against kinesin-5 Cut7 in S. pombe.

PubMed

Yukawa, Masashi; Yamada, Yusuke; Yamauchi, Tomoaki; Toda, Takashi

2018-01-04

Kinesin motors play central roles in bipolar spindle assembly. In many eukaryotes, spindle pole separation is driven by kinesin-5, which generates outward force. This outward force is balanced by antagonistic inward force elicited by kinesin-14 and/or dynein. In fission yeast, two kinesin-14 proteins, Pkl1 and Klp2, play an opposing role against the kinesin-5 motor protein Cut7. However, how the two kinesin-14 proteins coordinate individual activities remains elusive. Here, we show that although deletion of either pkl1 or klp2 rescues temperature-sensitive cut7 mutants, deletion of only pkl1 can bypass the lethality caused by cut7 deletion. Pkl1 is tethered to the spindle pole body, whereas Klp2 is localized along the spindle microtubule. Forced targeting of Klp2 to the spindle pole body, however, compensates for Pkl1 functions, indicating that cellular localizations, rather than individual motor specificities, differentiate between the two kinesin-14 proteins. Interestingly, human kinesin-14 (KIFC1 or HSET) can replace either Pkl1 or Klp2. Moreover, overproduction of HSET induces monopolar spindles, reminiscent of the phenotype of Cut7 inactivation. Taken together, this study has uncovered the biological mechanism whereby two different Kinesin-14 motor proteins exert their antagonistic roles against kinesin-5 in a spatially distinct manner. © 2018. Published by The Company of Biologists Ltd.

WAVE2 regulates meiotic spindle stability, peripheral positioning and polar body emission in mouse oocytes.

PubMed

Sun, Shao-Chen; Xu, Yong-Nan; Li, Ying-Hua; Lee, Seung-Eun; Jin, Yong-Xun; Cui, Xiang-Shun; Kim, Nam-Hyung

2011-06-01

During oocyte meiotic maturation, meiotic spindles form in the central cytoplasm and then migrate to the cortex to extrude a small polar body, forming a highly polarized cell through a process involving actin and actin-related molecules. The mechanisms underlying oocyte polarization are still unclear. The Arp2/3 complex regulates oocyte polarization but it is not known whether the WASP family of proteins, a known regulator of the Arp2/3 complex, is involved in this context. In the present study, the role of WASP family member WAVE2 in mouse oocyte asymmetric division was investigated. (1) WAVE2 mRNA and protein were detected during mouse oocyte meiosis. (2) siRNA-mediated and antibody-mediated disruption of WAVE2 resulted in the failure of chromosome congression, spindle formation, spindle positioning and polar body extrusion. (3) WAVE2 regulated actin-driven chromosome migration since chromosomes were arrested in the central cytoplasm by WAVE2 RNAi in the absence of microtubules. (4) Localization of γ-tubulin and MAPK was disrupted after RNAi, confirming the effect of WAVE2 on spindle formation. (5) Actin cap and cortical granule-free domain (CGFD) formation was also disrupted, further confirming the failure of oocyte polarization. Our data suggest that WAVE2 regulates oocyte polarization by regulating meiotic spindle, peripheral positioning, probably via an actin-mediated pathway, and is involved in polar body emission during mouse oocyte meiotic maturation.

40 CFR 86.540-90 - Exhaust sample analysis.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., if appropriate, NOX: (1) Zero the analyzers and obtain a stable zero reading. Recheck after tests. (2... actual concentrations on chart. (3) Check zeros; repeat the procedure in paragraphs (a) (1) and (2) of... appropriate, NOX. concentrations of samples. (6) Check zero and span points. If difference is greater than 2...

Mechanosignaling through YAP and TAZ drives fibroblast activation and fibrosis

PubMed Central

Liu, Fei; Lagares, David; Choi, Kyoung Moo; Stopfer, Lauren; Marinković, Aleksandar; Vrbanac, Vladimir; Probst, Clemens K.; Hiemer, Samantha E.; Sisson, Thomas H.; Horowitz, Jeffrey C.; Rosas, Ivan O.; Fredenburgh, Laura E.; Feghali-Bostwick, Carol; Varelas, Xaralabos; Tager, Andrew M.

2014-01-01

Pathological fibrosis is driven by a feedback loop in which the fibrotic extracellular matrix is both a cause and consequence of fibroblast activation. However, the molecular mechanisms underlying this process remain poorly understood. Here we identify yes-associated protein (YAP) (homolog of drosophila Yki) and transcriptional coactivator with PDZ-binding motif (TAZ) (also known as Wwtr1), transcriptional effectors of the Hippo pathway, as key matrix stiffness-regulated coordinators of fibroblast activation and matrix synthesis. YAP and TAZ are prominently expressed in fibrotic but not healthy lung tissue, with particularly pronounced nuclear expression of TAZ in spindle-shaped fibroblastic cells. In culture, both YAP and TAZ accumulate in the nuclei of fibroblasts grown on pathologically stiff matrices but not physiologically compliant matrices. Knockdown of YAP and TAZ together in vitro attenuates key fibroblast functions, including matrix synthesis, contraction, and proliferation, and does so exclusively on pathologically stiff matrices. Profibrotic effects of YAP and TAZ operate, in part, through their transcriptional target plasminogen activator inhibitor-1, which is regulated by matrix stiffness independent of transforming growth factor-β signaling. Immortalized fibroblasts conditionally expressing active YAP or TAZ mutant proteins overcome soft matrix limitations on growth and promote fibrosis when adoptively transferred to the murine lung, demonstrating the ability of fibroblast YAP/TAZ activation to drive a profibrotic response in vivo. Together, these results identify YAP and TAZ as mechanoactivated coordinators of the matrix-driven feedback loop that amplifies and sustains fibrosis. PMID:25502501

Early growth response 2 and Egr3 are unique regulators in immune system.

PubMed

Taefehshokr, Sina; Key, Yashar Azari; Khakpour, Mansour; Dadebighlu, Pourya; Oveisi, Amin

2017-01-01

The immune system is evolved to defend the body against pathogens and is composed of thousands of complicated and intertwined pathways, which are highly controlled by processes such as transcription and repression of cellular genes. Sometimes the immune system malfunctions and a break down in self-tolerance occurs. This lead to the inability to distinguish between self and non-self and cause attacks on host tissues, a condition also known as autoimmunity, which can result in chronic debilitating diseases. Early growth response genes are family of transcription factors comprising of four members, Egr1, Egr2, Egr3 and Egr4. All of which contain three cyc2-His2 zinc fingers. Initially, Egr2 function was identified in the regulation of peripheral nerve myelination, hindbrain segmentation. Egr3, on the other hand, is highly expressed in muscle spindle development. Egr2 and Egr3 are induced due to the antigen stimulation and this signaling is implemented through the B and T cell receptors in the adaptive immunity. T cell receptor signaling plays a key role in Egr 2 and 3 expressions via their interaction with NFAT molecules. Egr 2 and 3 play a crucial role in regulation of the immune system and their involvement in B and T cell activation, anergy induction and preventing the autoimmune disease has been investigated. The deficiency of these transcription factors has been associated to deficient Cbl-b expression, a resistant to anergy phenotype, and expression of effector and activated T cells.

Investigation the gas film in micro scale induced error on the performance of the aerostatic spindle in ultra-precision machining

NASA Astrophysics Data System (ADS)

Chen, Dongju; Huo, Chen; Cui, Xianxian; Pan, Ri; Fan, Jinwei; An, Chenhui

2018-05-01

The objective of this work is to study the influence of error induced by gas film in micro-scale on the static and dynamic behavior of a shaft supported by the aerostatic bearings. The static and dynamic balance models of the aerostatic bearing are presented by the calculated stiffness and damping in micro scale. The static simulation shows that the deformation of aerostatic spindle system in micro scale is decreased. For the dynamic behavior, both the stiffness and damping in axial and radial directions are increased in micro scale. The experiments of the stiffness and rotation error of the spindle show that the deflection of the shaft resulting from the calculating parameters in the micro scale is very close to the deviation of the spindle system. The frequency information in transient analysis is similar to the actual test, and they are also higher than the results from the traditional case without considering micro factor. Therefore, it can be concluded that the value considering micro factor is closer to the actual work case of the aerostatic spindle system. These can provide theoretical basis for the design and machining process of machine tools.

Casein kinase 1 (α, δ and ϵ) localize at the spindle poles, but may not be essential for mammalian oocyte meiotic progression

PubMed Central

Qi, Shu-Tao; Wang, Zhen-Bo; Huang, Lin; Liang, Li-Feng; Xian, Ye-Xing; Ouyang, Ying-Chun; Hou, Yi; Sun, Qing-Yuan; Wang, Wei-Hua

2015-01-01

CK1 (casein kinase 1) is a family of serine/threonine protein kinase that is ubiquitously expressed in eukaryotic organism. CK1 members are involved in the regulation of many cellular processes. Particularly, CK1 was reported to phosphorylate Rec8 subunits of cohesin complex and regulate chromosome segregation in meiosis in budding yeast and fission yeast.1-3 Here we investigated the expression, subcellular localization and potential functions of CK1α, CK1δ and CK1ϵ during mouse oocyte meiotic maturation. We found that CK1α, CK1δ and CK1ϵ all concentrated at the spindle poles and co-localized with γ-tubulin in oocytes at both metaphase I (MI) and metaphase II (MII) stages. However, depletion of CK1 by RNAi or overexpression of wild type or kinase-dead CK1 showed no effects on either spindle organization or chromosome segregation during oocyte meiotic maturation. Thus, CK1 is not the kinase that phosphorylates Rec8 cohesin in mammalian oocytes, and CK1 may not be essential for spindle organization and meiotic progression although they localize at spindle poles. PMID:25927854

Spindle checkpoint–independent inhibition of mitotic chromosome segregation by Drosophila Mps1

PubMed Central

Althoff, Friederike; Karess, Roger E.; Lehner, Christian F.

2012-01-01

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. PMID:22553353

Spindle checkpoint-independent inhibition of mitotic chromosome segregation by Drosophila Mps1.

PubMed

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.

Synthesis and electrochemical properties of NiO nanospindles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Hai; University of Chinese Academy of Sciences, Beijing 100049; Lv, Baoliang, E-mail: lbl604@sxicc.ac.cn

2014-02-01

Graphical abstract: NiO nanospindles with a different electrochemical activity as compared to those previous reports were synthesized via an agglomeration–dissolution–recrystallization growth process without the addition of any surfactant. - Highlights: • NiO nanospindles were synthesized without the addition of any surfactant. • The agglomeration–dissolution–recrystallization growth process was used to explain the precursors’ formation process of the spindle-like NiO. • As-obtained spindle-like NiO showed a different electrochemical activity as compared to those previous reports. - Abstract: NiO nanospindles were successfully synthesized via a hydrothermal and post-treatment method. The as-synthesized nanospindles were about several hundred nanometers in width and about one micrometermore » in length. X-ray diffraction (XRD) analysis revealed that the spindle-like structure was cubic NiO phase crystalline. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that these NiO nanospindles were of single crystal nature. On the basis of time-dependent experiments, a possible agglomeration–dissolution–recrystallization growth process was proposed to explain the formation process of the spindle-like precursors. The cyclic voltammetry (CV) measurement showed that the as-prepared spindle-like NiO exhibited a pseudo-capacitance behavior.« less

MLL/WDR5 Complex Regulates Kif2A Localization to Ensure Chromosome Congression and Proper Spindle Assembly during Mitosis.

PubMed

Ali, Aamir; Veeranki, Sailaja Naga; Chinchole, Akash; Tyagi, Shweta

2017-06-19

Mixed-lineage leukemia (MLL), along with multisubunit (WDR5, RbBP5, ASH2L, and DPY30) complex catalyzes the trimethylation of H3K4, leading to gene activation. Here, we characterize a chromatin-independent role for MLL during mitosis. MLL and WDR5 localize to the mitotic spindle apparatus, and loss of function of MLL complex by RNAi results in defects in chromosome congression and compromised spindle formation. We report interaction of MLL complex with several kinesin and dynein motors. We further show that the MLL complex associates with Kif2A, a member of the Kinesin-13 family of microtubule depolymerase, and regulates the spindle localization of Kif2A during mitosis. We have identified a conserved WDR5 interaction (Win) motif, so far unique to the MLL family, in Kif2A. The Win motif of Kif2A engages in direct interactions with WDR5 for its spindle localization. Our findings highlight a non-canonical mitotic function of MLL complex, which may have a direct impact on chromosomal stability, frequently compromised in cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

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

PubMed

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

2017-09-01

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 sarcoma presenting as a large and infiltrative pelvic soft tissue mass in a 4-month-old girl, which revealed a novel TFG-MET gene fusion by whole transcriptome RNA sequencing. The tumor resembled the morphology of an infantile fibrosarcoma with both fascicular and patternless growth, however, it expressed strong S100 protein immunoreactivity, while lacking SOX10 staining and retaining H3K27me3 expression. Although this immunoprofile suggested partial neural/neuroectodermal differentiation, overall features were unusual and did not fit into any known tumor types (cellular schwannoma, MPNST), raising the possibility of a novel pathologic entity. The TFG-MET gene fusion expands the genetic spectrum implicated in the pathogenesis of congenital spindle cell sarcomas, with yet another example of kinase oncogenic activation through chromosomal translocation. The discovery of this new fusion is significant since the resulting MET activation can potentially be inhibited by targeted therapy, as MET inhibitors are presently available in clinical trials. © 2017 Wiley Periodicals, Inc.

Prediction of general mental ability based on neural oscillation measures of sleep.

PubMed

Bódizs, Róbert; Kis, Tamás; Lázár, Alpár Sándor; Havrán, Linda; Rigó, Péter; Clemens, Zsófia; Halász, Péter

2005-09-01

The usual assessment of general mental ability (or intelligence) is based on performance attained in reasoning and problem-solving tasks. Differences in general mental ability have been associated with event-related neural activity patterns of the wakeful working brain or physical, chemical and electrical brain features measured during wakeful resting conditions. Recent evidences suggest that specific sleep electroencephalogram oscillations are related to wakeful cognitive performances. Our aim is to reveal the relationship between non-rapid eye movement sleep-specific oscillations (the slow oscillation, delta activity, slow and fast sleep spindle density, the grouping of slow and fast sleep spindles) and general mental ability assessed by the Raven Progressive Matrices Test (RPMT). The grouping of fast sleep spindles by the cortical slow oscillation in the left frontopolar derivation (Fp1) as well as the density of fast sleep spindles over the right frontal area (Fp2, F4), correlated positively with general mental ability. Data from those selected electrodes that showed the high correlations with general mental ability explained almost 70% of interindividual variance in RPMT scores. Results suggest that individual differences in general mental ability are reflected in fast sleep spindle-related oscillatory activity measured over the frontal cortex.

Method for Vibration Response Simulation and Sensor Placement Optimization of a Machine Tool Spindle System with a Bearing Defect

PubMed Central

Cao, Hongrui; Niu, Linkai; He, Zhengjia

2012-01-01

Bearing defects are one of the most important mechanical sources for vibration and noise generation in machine tool spindles. In this study, an integrated finite element (FE) model is proposed to predict the vibration responses of a spindle bearing system with localized bearing defects and then the sensor placement for better detection of bearing faults is optimized. A nonlinear bearing model is developed based on Jones' bearing theory, while the drawbar, shaft and housing are modeled as Timoshenko's beam. The bearing model is then integrated into the FE model of drawbar/shaft/housing by assembling equations of motion. The Newmark time integration method is used to solve the vibration responses numerically. The FE model of the spindle-bearing system was verified by conducting dynamic tests. Then, the localized bearing defects were modeled and vibration responses generated by the outer ring defect were simulated as an illustration. The optimization scheme of the sensor placement was carried out on the test spindle. The results proved that, the optimal sensor placement depends on the vibration modes under different boundary conditions and the transfer path between the excitation and the response. PMID:23012514

Air actuated clutch for four wheel drive vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clohessy, K.E.

1986-12-09

A control system is described for selectively engaging and disengaging a vehicle wheel and a vehicle drive mechanism comprising; a spindle having inside and outside rotative support surfaces, the spindle adapted to be mounted to a vehicle frame, an axle portion rotatably supported on the inside support surface, and drive means for selectively and rotatively driving the axle portion relative to the spindle; a wheel hub assembly adapted to carry a vehicle wheel, the hub assembly rotatively supported on the outside support surface of the spindle; a sealed expansion chamber defined in part by the spindle, the axle portion, themore » hub assembly and a movable wall carried by the hub assembly, venting means venting the outer side of the movable wall to atmospheric pressure, the clutch ring engaged by the movable wall for movement of the clutch ring with movement of the movable wall as induced by a pressure difference generated within the chamber, and pressurizing means for selectively pressurizing and depressurizing the expansion chamber to thereby selectively shift the clutch ring between the positions of interlocking the axle portion and hub assembly and unlocking the axle portion and hub assembly.« less

Analysis of Molecular Genetics Content in Spanish Secondary School Textbooks

ERIC Educational Resources Information Center

Martinez-Gracia, M. V.; Gil-Quilez, M. J.; Osada, J.

2006-01-01

The treatment of molecular biology in thirty-four Spanish high school biology textbooks has been analysed using a check-list made up of twenty-three items. The study showed a tendency to confuse the genetic code with genetic information. The treatment of DNA transcription, regulation of gene expression and translation were presented as masses of…

Mutations in CDK5RAP2 cause Seckel syndrome.

PubMed

Yigit, Gökhan; Brown, Karen E; Kayserili, Hülya; Pohl, Esther; Caliebe, Almuth; Zahnleiter, Diana; Rosser, Elisabeth; Bögershausen, Nina; Uyguner, Zehra Oya; Altunoglu, Umut; Nürnberg, Gudrun; Nürnberg, Peter; Rauch, Anita; Li, Yun; Thiel, Christian Thomas; Wollnik, Bernd

2015-09-01

Seckel syndrome is a heterogeneous, autosomal recessive disorder marked by prenatal proportionate short stature, severe microcephaly, intellectual disability, and characteristic facial features. Here, we describe the novel homozygous splice-site mutations c.383+1G>C and c.4005-9A>G in CDK5RAP2 in two consanguineous families with Seckel syndrome. CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly. We establish CDK5RAP2 as a disease-causing gene for Seckel syndrome and show that loss of functional CDK5RAP2 leads to severe defects in mitosis and spindle organization, resulting in cells with abnormal nuclei and centrosomal pattern, which underlines the important role of centrosomal and mitotic proteins in the pathogenesis of the disease. Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152. This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152.

Mutations in CDK5RAP2 cause Seckel syndrome

PubMed Central

Yigit, Gökhan; Brown, Karen E; Kayserili, Hülya; Pohl, Esther; Caliebe, Almuth; Zahnleiter, Diana; Rosser, Elisabeth; Bögershausen, Nina; Uyguner, Zehra Oya; Altunoglu, Umut; Nürnberg, Gudrun; Nürnberg, Peter; Rauch, Anita; Li, Yun; Thiel, Christian Thomas; Wollnik, Bernd

2015-01-01

Seckel syndrome is a heterogeneous, autosomal recessive disorder marked by prenatal proportionate short stature, severe microcephaly, intellectual disability, and characteristic facial features. Here, we describe the novel homozygous splice-site mutations c.383+1G>C and c.4005-9A>G in CDK5RAP2 in two consanguineous families with Seckel syndrome. CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly. We establish CDK5RAP2 as a disease-causing gene for Seckel syndrome and show that loss of functional CDK5RAP2 leads to severe defects in mitosis and spindle organization, resulting in cells with abnormal nuclei and centrosomal pattern, which underlines the important role of centrosomal and mitotic proteins in the pathogenesis of the disease. Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152. This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152. PMID:26436113

The effects of cutting parameters on cutting forces and heat generation when drilling animal bone and biomechanical test materials.

PubMed

Cseke, Akos; Heinemann, Robert

2018-01-01

The research presented in this paper investigated the effects of spindle speed and feed rate on the resultant cutting forces (thrust force and torque) and temperatures while drilling SawBones ® biomechanical test materials and cadaveric cortical bone (bovine and porcine femur) specimens. It also investigated cortical bone anisotropy on the cutting forces, when drilling in axial and radial directions. The cutting forces are only affected by the feed rate, whereas the cutting temperature in contrast is affected by both spindle speed and feed rate. The temperature distribution indicates friction as the primary heat source, which is caused by the rubbing of the tool margins and the already cut chips over the borehole wall. Cutting forces were considerably higher when drilling animal cortical bone, in comparison to cortical test material. Drilling direction, and therewith anisotropy, appears to have a negligible effect on the cutting forces. The results suggest that this can be attributed to the osteons being cut at an angle rather than in purely axial or radial direction, as a result of a twist drill's point angle. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Dynamics of large-scale brain activity in normal arousal states and epileptic seizures

NASA Astrophysics Data System (ADS)

Robinson, P. A.; Rennie, C. J.; Rowe, D. L.

2002-04-01

Links between electroencephalograms (EEGs) and underlying aspects of neurophysiology and anatomy are poorly understood. Here a nonlinear continuum model of large-scale brain electrical activity is used to analyze arousal states and their stability and nonlinear dynamics for physiologically realistic parameters. A simple ordered arousal sequence in a reduced parameter space is inferred and found to be consistent with experimentally determined parameters of waking states. Instabilities arise at spectral peaks of the major clinically observed EEG rhythms-mainly slow wave, delta, theta, alpha, and sleep spindle-with each instability zone lying near its most common experimental precursor arousal states in the reduced space. Theta, alpha, and spindle instabilities evolve toward low-dimensional nonlinear limit cycles that correspond closely to EEGs of petit mal seizures for theta instability, and grand mal seizures for the other types. Nonlinear stimulus-induced entrainment and seizures are also seen, EEG spectra and potentials evoked by stimuli are reproduced, and numerous other points of experimental agreement are found. Inverse modeling enables physiological parameters underlying observed EEGs to be determined by a new, noninvasive route. This model thus provides a single, powerful framework for quantitative understanding of a wide variety of brain phenomena.

Spindle cell sarcoma of the vulva with myofibroblastic differentiation.

PubMed

Adeleye, Amanda J; Palmeri, Nicholas; Wang, Shih-Hsiu J; Liu-Jarin, Xiaolin; Wright, Jason D

2015-04-01

Primary vulvar sarcomas are rare lesions of the lower genital tract. We report the case of a patient with a spindle cell sarcoma of the vulva. A 44-year-old woman presented with a painless vulvar mass. Vulvar biopsy demonstrated a spindle cell sarcoma with myofibroblastic differentiation. Pretreatment evaluation revealed no evidence of metastatic disease, and magnetic resonance imaging found no local masses. The patient underwent right radical vulvectomy with negative margins and tolerated the procedure well. Women undergoing gynecologic care should have routine evaluation of the vulva to detect these rare neoplasms.

A comparative analysis of the encapsulated end-organs of mammalian skeletal muscles and of their sensory nerve endings.

PubMed

Banks, R W; Hulliger, M; Saed, H H; Stacey, M J

2009-06-01

The encapsulated sensory endings of mammalian skeletal muscles are all mechanoreceptors. At the most basic functional level they serve as length sensors (muscle spindle primary and secondary endings), tension sensors (tendon organs), and pressure or vibration sensors (lamellated corpuscles). At a higher functional level, the differing roles of individual muscles in, for example, postural adjustment and locomotion might be expected to be reflected in characteristic complements of the various end-organs, their sensory endings and afferent nerve fibres. This has previously been demonstrated with regard to the number of muscle-spindle capsules; however, information on the other types of end-organ, as well as the complements of primary and secondary endings of the spindles themselves, is sporadic and inconclusive regarding their comparative provision in different muscles. Our general conclusion that muscle-specific variability in the provision of encapsulated sensory endings does exist demonstrates the necessity for the acquisition of more data of this type if we are to understand the underlying adaptive relationships between motor control and the structure and function of skeletal muscle. The present quantitative and comparative analysis of encapsulated muscle afferents is based on teased, silver-impregnated preparations. We begin with a statistical analysis of the number and distribution of muscle-spindle afferents in hind-limb muscles of the cat, particularly tenuissimus. We show that: (i) taking account of the necessity for at least one primary ending to be present, muscles differ significantly in the mean number of additional afferents per spindle capsule; (ii) the frequency of occurrence of spindles with different sensory complements is consistent with a stochastic, rather than deterministic, developmental process; and (iii) notwithstanding the previous finding, there is a differential distribution of spindles intramuscularly such that the more complex ones tend to be located closer to the main divisions of the nerve. Next, based on a sample of tendon organs from several hind-foot muscles of the cat, we demonstrate the existence in at least a large proportion of tendon organs of a structural substrate to account for multiple spike-initiation sites and pacemaker switching, namely the distribution of sensory terminals supplied by the different first-order branches of the Ib afferent to separate, parallel, tendinous compartments of individual tendon organs. We then show that the numbers of spindles, tendon organs and paciniform corpuscles vary independently in a sample of (mainly) hind-foot muscles of the cat. Grouping muscles by anatomical region in the cat indicated the existence of a gradual proximo-distal decline in the overall average size of the afferent complement of muscle spindles from axial through hind limb to intrinsic foot muscles, but with considerable muscle-specific variability. Finally, we present some comparative data on muscle-spindle afferent complements of rat, rabbit and guinea pig, one particularly notable feature being the high incidence of multiple primary endings in the rat.

[Polarized light microscopy for evaluation of oocytes as a prognostic factor in the evolution of a cycle in assisted reproduction].

PubMed

González-Ortega, C; Cancino-Villarreal, P; Alonzo-Torres, V E; Martínez-Robles, I; Pérez-Peña, E; Gutiérrez-Gutiérrez, A M

2016-04-01

Identification of the best embryos to transfer is a key element for success in assisted reproduction. In the last decade, several morphological criteria of oocytes and embryos were evaluated with regard to their potential for predicting embryo viability. The introduction of polarization light microscopy systems has allowed the visualization of the meiotic spindle and the different layers of the zona pellucida in human oocytes on the basis of birefringence in a non-destructive way. Conflicting results have been reported regarding the predictive value in ICSI cycles. To assess the predictive ability of meiotic spindle and zona pellucida of human oocytes to implant by polarized microscopy in ICSI cycles. Prospective and observational clinical study. 903 oocytes from 94 ICSI cycles were analyzed with polarized microscopy. Meiotic spindle visualization and zona pellucida birefringence values by polarized microscopy were correlated with ICSI cycles results. Meiotic spindle visualization and birefringence values of zona pellucida decreased in a direct basis with increasing age. In patients aged over the 35 years, the percentage of a visible spindle and mean zona pellucida birefringence was lower than in younger patients. Fertilization rate were higher in oocytes with visible meiotic spindle (81.3% vs. 64%; p < 0.0001), as well as embryo quality (47.4% vs. 39%; p=0.01). Fertilization rate was higher in oocytes with positive values of birefringence (77.5 % vs. 68.5% p=0.005) with similar embryo quality. Conception cycles showed oocytes with higher mean value of zona birefringence and visible spindle vs. no-conception cycles (p<0.05). Polarized light microscopy improves oocyte selection, which significantly impacts in the development of embryos with greater implantation potential. The use of polarized light microscopy with sperm selection methods, blastocyst culture and deferred embryo transfers will contribute to transfer fewer embryos without diminishing rates of live birth and single embryo transfer will be more feasible.

Studies on the in vivo sensitivity of spindle microtubules to calcium ions and evidence for a vesicular calcium-sequestering system

PubMed Central

1981-01-01

I microinjected calcium ions into echinoderm eggs during mitosis to determine the calcium sensitivity of microtubules (Mts) in vivo. Spindle birefringence (BR), a measure of the number of aligned Mts in the spindle, is locally, rapidly, and reversibly abolished by small volumes of microinjected CaCl2 (1 mM). Rapid return of BR is followed by anaphase, and subsequent divisions are normal. Similar doses of MgCl2, BaCl2, KCl, NaCl, pH buffers, distilled water, or vegetable oil have no effect on spindle BR, whereas large doses of such agents sometimes cause slow, uniform loss in BR over the course of a minute or more. Of the ions tested, only Sr++ causes effects comparable to Ca++. Ca-EGTA buffers, containing greater than micromolar free Ca++, abolishes BR in a manner similar to millimolar concentrations of injected CaCl2. Caffeine, a potent uncoupler of the Ca++-pump/ATPase of sarcoplasmic reticulum, causes a local, transient depression in spindle BR in the injected region. Finally, injection of potassium oxalate results in the formation of small, highly BR crystals, presumably CA- oxalate, in Triton-sensitive compartments in the cytoplasm. Taken together, these findings demonstrate that spindle Mts are sensitive to levels of free Ca++ in the physiological range, provide evidence for the existence of a strong cytoplasmic Ca++-sequestering system, and support the notion that Mt assembly and disassembly in local regions of the spindle may be orchestrated by local changes in the cytoplasmic free Ca++ concentration during mitosis. An appendix offers the design of a new chamber for immobilizing echinoderm eggs for injection, a new method for determining the volume of the injected solution, and a description of the microinjection technique, which was designed, but never fully described, by Hiramoto (Y. Hiramoto, Exp. Cell. Res., 1962, 27:416-426.). PMID:7194345

Sleep spindle and K-complex detection using tunable Q-factor wavelet transform and morphological component analysis

PubMed Central

Lajnef, Tarek; Chaibi, Sahbi; Eichenlaub, Jean-Baptiste; Ruby, Perrine M.; Aguera, Pierre-Emmanuel; Samet, Mounir; Kachouri, Abdennaceur; Jerbi, Karim

2015-01-01

A novel framework for joint detection of sleep spindles and K-complex events, two hallmarks of sleep stage S2, is proposed. Sleep electroencephalography (EEG) signals are split into oscillatory (spindles) and transient (K-complex) components. This decomposition is conveniently achieved by applying morphological component analysis (MCA) to a sparse representation of EEG segments obtained by the recently introduced discrete tunable Q-factor wavelet transform (TQWT). Tuning the Q-factor provides a convenient and elegant tool to naturally decompose the signal into an oscillatory and a transient component. The actual detection step relies on thresholding (i) the transient component to reveal K-complexes and (ii) the time-frequency representation of the oscillatory component to identify sleep spindles. Optimal thresholds are derived from ROC-like curves (sensitivity vs. FDR) on training sets and the performance of the method is assessed on test data sets. We assessed the performance of our method using full-night sleep EEG data we collected from 14 participants. In comparison to visual scoring (Expert 1), the proposed method detected spindles with a sensitivity of 83.18% and false discovery rate (FDR) of 39%, while K-complexes were detected with a sensitivity of 81.57% and an FDR of 29.54%. Similar performances were obtained when using a second expert as benchmark. In addition, when the TQWT and MCA steps were excluded from the pipeline the detection sensitivities dropped down to 70% for spindles and to 76.97% for K-complexes, while the FDR rose up to 43.62 and 49.09%, respectively. Finally, we also evaluated the performance of the proposed method on a set of publicly available sleep EEG recordings. Overall, the results we obtained suggest that the TQWT-MCA method may be a valuable alternative to existing spindle and K-complex detection methods. Paths for improvements and further validations with large-scale standard open-access benchmarking data sets are discussed. PMID:26283943

40 CFR Appendix A-1 to Part 60 - Test Methods 1 through 2F

Code of Federal Regulations, 2012 CFR

2012-07-01

... points are combined to form a single adjusted traverse point, treat the adjusted point as two separate... checks during the traverse (at least once per hour). Record all necessary data on a form similar to that...

40 CFR Appendix A-1 to Part 60 - Test Methods 1 through 2F

Code of Federal Regulations, 2010 CFR

2010-07-01

... points are combined to form a single adjusted traverse point, treat the adjusted point as two separate... checks during the traverse (at least once per hour). Record all necessary data on a form similar to that...

40 CFR Appendix A-1 to Part 60 - Test Methods 1 through 2F

Code of Federal Regulations, 2013 CFR

2013-07-01

... points are combined to form a single adjusted traverse point, treat the adjusted point as two separate... checks during the traverse (at least once per hour). Record all necessary data on a form similar to that...

40 CFR Appendix A-1 to Part 60 - Test Methods 1 through 2F

Code of Federal Regulations, 2011 CFR

2011-07-01

... points are combined to form a single adjusted traverse point, treat the adjusted point as two separate... checks during the traverse (at least once per hour). Record all necessary data on a form similar to that...

Ebola Check: Delivering molecular diagnostics at the point of need.

PubMed

Moschos, Sterghios A

2015-01-01

The 2013-5 global outbreak of Ebolavirus disease brought to sharp focus the need for diagnostic capacity to be equitably available on a global scale: from the most under-developed areas of resource-limited countries in West Africa to high volume international travel hubs in Europe and the USA. Quick detection of the causal agent of disease is pivotal to containment, contact tracing and clinical action to protect healthcare workers, communities and patients. Nucleic acid testing (NAT) by real time reverse transcription quantitative polymerase chain reaction (RT-PCR) has emerged as the preferred method for reliable patient status confirmation. Presently, this is served through advanced clinical molecular laboratory testing in a <8hr manual process that requires 3.5ml venous blood samples. To meet the demand in West Africa, this has necessitated large-scale mobile laboratory and volunteer biomedical scientist deployment: a solution that has proven eventually adequate, albeit temporary against future re-emergence of this and other haemorrhagic fever disease agents prevalent in the region. The EbolaCheck consortium was formed in August 2014 to address the need for delivering NAT at the point of care. We have developed a novel platform technology that can QUantitatively, RAPidly IDentify (QuRapID) known RNA or DNA targets in viruses, bacteria, or eukaryotic cells directly in crude biofluids, including whole blood, in under 40min using a 5 microliter sample. The portable, battery-operated system lacks microfluidics, pumps or other sensitive/high cost parts making it suitable for the environmental and economic challenges of resource-limited countries. The simple, safe, 5-step sample-to-answer process requires minimal training and informs frontline healthcare workers of diagnostic status, whilst reporting remotely epidemiologically relevant results. Data on biosafety level 2 surrogate Ebolavirus templates presented in encapsulated or enveloped viruses indicate performance comparable to clinical laboratory testing and utility beyond filoviruses. Emerging performance data on live Ebolavirus, non-human primate disease model and patient samples, as well as future development plans will be discussed.

Equilibrium stellar systems with spindle singularities

NASA Technical Reports Server (NTRS)

Shapiro, Stuart L.; Teukolsky, Saul A.

1992-01-01

Equilibrium sequences of axisymmetric Newtonian clusters that tend toward singular states are constructed. The distribution functions are chosen to be of the form f = f(E, Jz). The numerical method then determines the density and gravitational potential self-consistently to satisfy Poisson's equation. For the prolate models, spindle singularities arise from the depletion of angular momentum near the symmetry axis. While the resulting density enhancement is confined to the region near the axis, the influence of the spindle extends much further out through its tidal gravitational field. Centrally condensed prolate clusters may contain strong-field regions even though the spindle mass is small and the mean cluster eccentricity is not extreme. While the calculations performed here are entirely Newtonian, the issue of singularities is an important topic in general relativity. Equilibrium solutions for relativistic star clusters can provide a testing ground for exploring this issue. The methods used in this paper for building nonspherical clusters can be extended to relativistic systems.

HMMR acts in the PLK1-dependent spindle positioning pathway and supports neural development

PubMed Central

Jiang, Jihong; Kuan, Chia-Wei; Fotovati, Abbas; Chu, Tony LH; He, Zhengcheng; Lengyell, Tess C; Li, Huaibiao; Kroll, Torsten; Li, Amanda M; Goldowitz, Daniel; Frappart, Lucien; Ploubidou, Aspasia; Patel, Millan S; Pilarski, Linda M; Simpson, Elizabeth M; Lange, Philipp F; Allan, Douglas W

2017-01-01

Oriented cell division is one mechanism progenitor cells use during development and to maintain tissue homeostasis. Common to most cell types is the asymmetric establishment and regulation of cortical NuMA-dynein complexes that position the mitotic spindle. Here, we discover that HMMR acts at centrosomes in a PLK1-dependent pathway that locates active Ran and modulates the cortical localization of NuMA-dynein complexes to correct mispositioned spindles. This pathway was discovered through the creation and analysis of Hmmr-knockout mice, which suffer neonatal lethality with defective neural development and pleiotropic phenotypes in multiple tissues. HMMR over-expression in immortalized cancer cells induces phenotypes consistent with an increase in active Ran including defects in spindle orientation. These data identify an essential role for HMMR in the PLK1-dependent regulatory pathway that orients progenitor cell division and supports neural development. PMID:28994651

EFHC1, a protein mutated in juvenile myoclonic epilepsy, associates with the mitotic spindle through its N-terminus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nijs, Laurence de; Lakaye, Bernard; Coumans, Bernard

2006-09-10

A novel gene, EFHC1, mutated in juvenile myoclonic epilepsy (JME) encodes a protein with three DM10 domains of unknown function and one putative EF-hand motif. To study the properties of EFHC1, we expressed EGFP-tagged protein in various cell lines. In interphase cells, the fusion protein was present in the cytoplasm and in the nucleus with specific accumulation at the centrosome. During mitosis EGFP-EFHC1 colocalized with the mitotic spindle, especially at spindle poles and with the midbody during cytokinesis. Using a specific antibody, we demonstrated the same distribution of the endogenous protein. Deletion analyses revealed that the N-terminal region of EFHC1more » is crucial for the association with the mitotic spindle and the midbody. Our results suggest that EFHC1 could play an important role during cell division.« less

Wind turbine/generator set and method of making same

DOEpatents

Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

2013-06-04

A wind turbine comprising an electrical generator that includes a rotor assembly. A wind rotor that includes a wind rotor hub is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The wind rotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the wind rotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

Wind turbine/generator set having a stator cooling system located between stator frame and active coils

DOEpatents

Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

2012-11-13

A wind turbine comprising an electrical generator that includes a rotor assembly. A wind rotor that includes a wind rotor hub is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The wind rotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the wind rotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

Wind turbine having a direct-drive drivetrain

DOEpatents

Bevington, Christopher M.; Bywaters, Garrett L.; Coleman, Clint C.; Costin, Daniel P.; Danforth, William L.; Lynch, Jonathan A.; Rolland, Robert H.

2011-02-22

A wind turbine comprising an electrical generator that includes a rotor assembly. A wind rotor that includes a wind rotor hub is directly coupled to the rotor assembly via a simplified connection. The wind rotor and generator rotor assembly are rotatably mounted on a central spindle via a bearing assembly. The wind rotor hub includes an opening having a diameter larger than the outside diameter of the central spindle adjacent the bearing assembly so as to allow access to the bearing assembly from a cavity inside the wind rotor hub. The spindle is attached to a turret supported by a tower. Each of the spindle, turret and tower has an interior cavity that permits personnel to traverse therethrough to the cavity of the wind rotor hub. The wind turbine further includes a frictional braking system for slowing, stopping or keeping stopped the rotation of the wind rotor and rotor assembly.

New frontiers: discovering cilia-independent functions of cilia proteins.

PubMed

Vertii, Anastassiia; Bright, Alison; Delaval, Benedicte; Hehnly, Heidi; Doxsey, Stephen

2015-10-01

In most vertebrates, mitotic spindles and primary cilia arise from a common origin, the centrosome. In non-cycling cells, the centrosome is the template for primary cilia assembly and, thus, is crucial for their associated sensory and signaling functions. During mitosis, the duplicated centrosomes mature into spindle poles, which orchestrate mitotic spindle assembly, chromosome segregation, and orientation of the cell division axis. Intriguingly, both cilia and spindle poles are centrosome-based, functionally distinct structures that require the action of microtubule-mediated, motor-driven transport for their assembly. Cilia proteins have been found at non-cilia sites, where they have distinct functions, illustrating a diverse and growing list of cellular processes and structures that utilize cilia proteins for crucial functions. In this review, we discuss cilia-independent functions of cilia proteins and re-evaluate their potential contributions to "cilia" disorders. © 2015 The Authors.

Sleep spindle detection using deep learning: A validation study based on crowdsourcing.

PubMed

Dakun Tan; Rui Zhao; Jinbo Sun; Wei Qin

2015-08-01

Sleep spindles are significant transient oscillations observed on the electroencephalogram (EEG) in stage 2 of non-rapid eye movement sleep. Deep belief network (DBN) gaining great successes in images and speech is still a novel method to develop sleep spindle detection system. In this paper, crowdsourcing replacing gold standard was applied to generate three different labeled samples and constructed three classes of datasets with a combination of these samples. An F1-score measure was estimated to compare the performance of DBN to other three classifiers on classifying these samples, with the DBN obtaining an result of 92.78%. Then a comparison of two feature extraction methods based on power spectrum density was made on same dataset using DBN. In addition, the DBN trained in dataset was applied to detect sleep spindle from raw EEG recordings and performed a comparable capacity to expert group consensus.

Search, capture and signal: games microtubules and centrosomes play.

PubMed

Schuyler, S C; Pellman, D

2001-01-01

Accurate distribution of the chromosomes in dividing cells requires coupling of cellular polarity cues with both the orientation of the mitotic spindle and cell cycle progression. Work in budding yeast has demonstrated that cytoplasmic dynein and the kinesin Kip3p define redundant pathways that ensure proper spindle orientation. Furthermore, it has been shown that the Kip3p pathway components Kar9p and Bim1p (Yeb1p) form a complex that provides a molecular link between cortical polarity cues and spindle microtubules. Recently, other studies indicated that the cortical localization of Kar9p depends upon actin cables and Myo2p, a type V myosin. In addition, a BUB2-dependent cell cycle checkpoint has been described that inhibits the mitotic exit network and cytokinesis until proper centrosome position is achieved. Combined, these studies provide molecular insight into how cells link cellular polarity, spindle position and cell cycle progression.

Branching microtubule nucleation in Xenopus egg extracts mediated by augmin and TPX2

PubMed Central

Petry, Sabine; Groen, Aaron C.; Ishihara, Keisuke; Mitchison, Timothy J.; Vale, Ronald D.

2013-01-01

Summary The microtubules that comprise mitotic spindles in animal cells are nucleated at centrosomes and by spindle assembly factors that are activated in the vicinity of chromatin. Indirect evidence also has suggested that microtubules might be nucleated from pre-existing microtubules throughout the spindle, but this process has not been observed directly. Here, we demonstrate microtubule nucleation from the sides of existing microtubules in meiotic Xenopus egg extracts. Daughter microtubules grow at a low branch angle and with the same polarity as mother filaments. Branching microtubule nucleation requires gamma-tubulin and augmin and is stimulated by GTP-bound Ran and its effector TPX2, factors previously implicated in chromatin-stimulated nucleation. Because of the rapid amplification of microtubule numbers and the preservation of microtubule polarity, microtubule-dependent microtubule nucleation is well suited for spindle assembly and maintenance. PMID:23415226

The transcription factor LEF-1 induces an epithelial–mesenchymal transition in MDCK cells independent of β-catenin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kobayashi, Wakako; Ozawa, Masayuki, E-mail: mozawa@m.kufm.kagoshima-u.ac.jp

2013-12-06

Highlights: •The transcription factor LEF-1 induces an EMT in MDCK cells. •A mutant LEF-1 that cannot interact with β-catenin retained the ability. •The nuclear function of β-catenin was not necessary for the LEF-1-induced EMT. •The mRNA levels of Slug, ZEB1, and ZEB2 increased significantly in these cells. -- Abstract: The epithelial–mesenchymal transition (EMT), a key process in the tumor metastatic cascade, is characterized by the loss of cell–cell junctions and cell polarity, as well as the acquisition of migratory and invasive properties. LEF-1 is a member of the lymphoid enhancer-binding factor/T-cell factor (LEF/TCF) family of DNA-binding transcription factors, which interactmore » with nuclear β-catenin and act as central transcriptional mediators of Wnt signaling. To investigate the role of LEF-1 in EMT, we generated stable LEF-1 transfectants using MDCK cells. The transfectants had a spindle-shaped mesenchymal morphology, and enhanced migration and invasiveness relative to control cells. These EMT changes were accompanied by the downregulation of an epithelial marker protein, E-cadherin, and the upregulation of mesenchymal marker proteins, vimentin and N-cadherin. Consistent with these observations, the mRNA levels of Slug, ZEB1, and ZEB2—EMT-related transcription factors—increased significantly. Although the N-terminally deleted mutant LEF-1 cannot interact with β-catenin, it retained the ability to induce EMT. Consistent with these observations, neither the expression of a dominant negative β-catenin/engrailed chimera, nor the expression of a cytoplasmic domain of E-cadherin that sequesters β-catenin from binding to LEF/TCF, reversed LEF-1-induced EMT. Together, these data indicated that the nuclear function of β-catenin was not necessary for the induction of Slug, ZEB1, and ZEB2 expression leading to EMT.« less

AURKA mRNA expression is an independent predictor of poor prognosis in patients with non-small cell lung cancer.

PubMed

Al-Khafaji, Ahmed S K; Marcus, Michael W; Davies, Michael P A; Risk, Janet M; Shaw, Richard J; Field, John K; Liloglou, Triantafillos

2017-06-01

Deregulation of mitotic spindle genes has been reported to contribute to the development and progression of malignant tumours. The aim of the present study was to explore the association between the expression profiles of Aurora kinases ( AURKA , AURKB and AURKC ), cytoskeleton-associated protein 5 ( CKAP5 ), discs large-associated protein 5 ( DLGAP5 ), kinesin-like protein 11 ( KIF11 ), microtubule nucleation factor ( TPX2 ), monopolar spindle 1 kinase ( TTK ), and β-tubulins ( TUBB ) and ( TUBB3 ) genes and clinicopathological characteristics in human non-small cell lung carcinoma (NSCLC). Reverse transcription-quantitative polymerase chain reaction-based RNA gene expression profiles of 132 NSCLC and 44 adjacent wild-type tissues were generated, and Cox's proportional hazard regression was used to examine associations. With the exception of AURKC , all genes exhibited increased expression in NSCLC tissues. Of the 10 genes examined, only AURKA was significantly associated with prognosis in NSCLC. Multivariate Cox's regression analysis demonstrated that AURKA mRNA expression [hazard ratio (HR), 1.81; 95% confidence interval (CI), 1.16-2.84; P=0.009], age (HR, 1.03; 95% CI, 1.00-1.06; P=0.020), pathological tumour stage 2 (HR, 2.43; 95% CI, 1.16-5.10; P=0.019) and involvement of distal nodes (pathological node stage 2) (HR, 3.14; 95% CI, 1.24-7.99; P=0.016) were independent predictors of poor prognosis in patients with NSCLC. Poor prognosis of patients with increased AURKA expression suggests that those patients may benefit from surrogate therapy with AURKA inhibitors.

SOX2 and nestin expression in human melanoma: an immunohistochemical and experimental study

PubMed Central

Laga, Alvaro C.; Zhan, Qian; Weishaupt, Carsten; Ma, Jie; Frank, Markus H.; Murphy, George F.

2012-01-01

SOX2 is an embryonic neural crest stem-cell transcription factor recently shown to be expressed in human melanoma and to correlate with experimental tumor growth. SOX2 binds to an enhancer region of the gene that encodes for nestin, also a neural progenitor cell biomarker. To define further the potential relationship between SOX2 and nestin, we examined co-expression patterns in 135 melanomas and 37 melanocytic nevi. Immunohistochemical staining in 27 melanoma tissue sections showed an association between SOX2 positivity, spindle cell shape and a peripheral nestin distribution pattern. In contrast, SOX2-negative cells were predominantly epithelioid, and exhibited a cytoplasmic pattern for nestin. In tissue microarrays, co-expression correlated with tumor progression, with only 11% of nevi co-expressing SOX2 and nestin in contrast to 65% of metastatic melanomas, and preliminarily, with clinical outcome. Human melanoma lines that differentially expressed constitutive SOX2 revealed a positive correlation between SOX2 and nestin expression. Experimental melanomas grown from these respective cell lines in murine subcutis and dermis of xenografted human skin maintained the association between SOX2-positivity, spindle cell shape, and peripheral nestin distribution. Moreover, the cytoplasmic pattern of nestin distribution was observed in xenografts generated from SOX2-knockdown A2058 melanoma cells, in contrast to the periperhal nestin pattern seen in tumors grown from A2058 control cells transfected with non-target shRNA. In aggregate, these data further support a biologically significant linkage between SOX2 and nestin expression in human melanoma. PMID:21410764

Extensive Crosstalk Between O-GlcNAcylation and Phosphorylation Regulates Cytokinesis

PubMed Central

Wang, Zihao; Udeshi, Namrata D.; Slawson, Chad; Compton, Philip D.; Sakabe, Kaoru; Cheung, Win D.; Shabanowitz, Jeffrey; Hunt, Donald F.; Hart, Gerald W.

2010-01-01

Like phosphorylation, the addition of O-linked β-N-acetylglucosamine (O-GlcNAcylation) is a ubiquitous, reversible process that modifies serine and threonine residues on nuclear and cytoplasmic proteins. Overexpression of the enzyme that adds O-GlcNAc to target proteins, O-GlcNAc transferase (OGT), perturbs cytokinesis and promotes polyploidy, but the molecular targets of OGT that are important for its cell cycle functions are unknown. Here, we identify 141 previously unknown O-GlcNAc sites on proteins that function in spindle assembly and cytokinesis. Many of these O-GlcNAcylation sites are either identical to known phosphorylation sites or in close proximity to them. Furthermore, we found that O-GlcNAcylation altered the phosphorylation of key proteins associated with the mitotic spindle and midbody. Forced overexpression of OGT increased the inhibitory phosphorylation of cyclin-dependent kinase 1 (CDK1) and reduced the phosphorylation of CDK1 target proteins. The increased phosphorylation of CDK1 is explained by increased activation of its upstream kinase, MYT1, and by a concomitant reduction in the transcript for the CDK1 phosphatase, CDC25C. OGT overexpression also caused a reduction in both messenger RNA expression and protein abundance of Polo-like kinase 1, which is upstream of both MYT1 and CDC25C. The data not only illustrate the crosstalk between O-GlcNAcylation and phosphorylation of proteins that are regulators of crucial signaling pathways, but also uncover a mechanism for the role of O-GlcNAcylation in regulation of cell division. PMID:20068230

Tumor suppressor roles of CENP-E and Nsl1 in Drosophila epithelial tissues.

PubMed

Clemente-Ruiz, Marta; Muzzopappa, Mariana; Milán, Marco

2014-01-01

Depletion of spindle assembly checkpoint (SAC) genes in Drosophila epithelial tissues leads to JNK-dependent programmed cell death and additional blockade of the apoptotic program drives tumorigenesis. A recent report proposes that chromosomal instability (CIN) is not the driving force in the tumorigenic response of the SAC-deficient tissue, and that checkpoint proteins exert a SAC-independent tumor suppressor role. This notion is based on observations that the depletion of CENP-E levels or prevention of Bub3 from binding to the kinetochore in Drosophila tissues unable to activate the apoptotic program induces CIN but does not cause hyperproliferation. Here we re-examined this proposal. In contrast to the previous report, we observed that depletion of CENP-E or Nsl1-the latter mediating kinetochore targeting of Bub3-in epithelial tissues unable to activate the apoptotic program induces significant levels of aneuploidy and drives tumor-like growth. The induction of the JNK transcriptional targets Wingless, a mitogenic molecule, and MMP1, a matrix metaloproteinase 1 involved in basement membrane degradation was also observed in these tumors. An identical response of the tissue was previously detected upon depletion of several SAC genes or genes involved in spindle assembly, chromatin condensation, and cytokinesis, all of which have been described to cause CIN. All together, these results reinforce the role of CIN in driving tumorigenesis in Drosophila epithelial tissues and question the proposed SAC-independent roles of checkpoint proteins in suppressing tumorigenesis. Differences in aneuploidy rates might explain the discrepancy between the previous report and our results.

SU-E-T-117: Analysis of the ArcCHECK Dosimetry Gamma Failure Using the 3DVH System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, S; Choi, W; Lee, H

2015-06-15

Purpose: To evaluate gamma analysis failure for the VMAT patient specific QA using ArcCHECK cylindrical phantom. The 3DVH system(Sun Nuclear, FL) was used to analyze the dose difference statistic between measured dose and treatment planning system calculated dose. Methods: Four case of gamma analysis failure were selected retrospectively. Our institution gamma analysis indexes were absolute dose, 3%/3mm and 90%pass rate in the ArcCHECK dosimetry. The collapsed cone convolution superposition (CCCS) dose calculation algorithm for VMAT was used. Dose delivery was performed with Elekta Agility. The A1SL(standard imaging, WI) and cavity plug were used for point dose measurement. Delivery QA plansmore » and images were used for 3DVH Reference data instead of patient plan and image. The measured data of ‘.txt’ file was used for comparison at diodes to acquire a global dose level. The,.acml’ file was used for AC-PDP and to calculated point dose. Results: The global dose of 3DVH was calculated as 1.10 Gy, 1.13, 1.01 and 0.2 Gy respectively. The global dose of 0.2 Gy case was induced by distance discrepancy. The TPS calculated point dose of was 2.33 Gy to 2.77 Gy and 3DVH calculated dose was 2.33 Gy to 2.68 Gy. The maximum dose differences were −2.83% and −3.1% for TPS vs. measured dose and TPS vs. 3DVH calculated respectively in the same case. The difference between measured and 3DVH was 0.1% in that case. The 3DVH gamma pass rate was 98% to 99.7%. Conclusion: We found the TPS calculation error by 3DVH calculation using ArcCHECK measured dose. It seemed that our CCCS algorithm RTP system over estimated at the central region and underestimated scattering at the peripheral diode detector point. The relative gamma analysis and point dose measurement would be recommended for VMAT DQA in the gamma failure case of ArcCHECK dosimetry.« less

Ultrastructural and molecular biologic comparison of classical proprioceptors and palisade endings in sheep extraocular muscles

PubMed Central

RUNGALDIER, Stefanie; HEILIGENBRUNNER, Stefan; MAYER, Regina; HANEFL-KRIVANEK, Christiane; LIPOWEC, Marietta; STREICHER, Johannes; BLUMER, Roland

2016-01-01

Purpose To analyze and compare the structural and molecular features of classical proprioceptors like muscle spindles and Golgi tendon organs (GTOs) and putative proprioceptors (palisade endings) in sheep extraocular muscle (EOMs). Methods The EOMs of four sheep were analyzed. Frozen sections or whole mount preparations of the samples were immunohistochemically labeled and analyzed by confocal laser scanning microscopy. Triple labeling with different combinations of antibodies against neurofilament, synaptophysin and choline acetyltransferase (ChAT) as well as α-bungarotoxin and phalloidin was performed. Microscopic anatomy of the nerve end organs was analyzed by transmission electron microscopy. Results The microscopic anatomy demonstrated that muscle spindles and GTOs had a perineural capsule and palisade endings a connective tissue capsule. Sensory nerve terminals in muscle spindles and GTOs contained only few vesicles whereas palisade nerve terminals were full of clear vesicles. Likewise, motor terminals in the muscle spindles’ polar regions were full of clear vesicles. Immunohistochemistry showed that sensory nerve fibers as well as their sensory nerve terminals in muscle spindles and GTOs were ChAT-negative. Palisade endings were supplied by ChAT-positive nerve fibers and the palisade complexes including palisade nerve terminals were also ChAT-immunoreactive. Motor terminals in muscle spindles were ChAT and α-bungarotoxin -positive. Conclusions The present study demonstrated in sheep EOMs that palisade endings are innervated by cholinergic axons exhibiting characteristics typical for motoneurons whereas muscle spindles (except the polar regions) and GTOs are supplied by non-cholinergic axons. These results question whether palisade endings are candidates for proprioceptors in EOMs. PMID:19553627

The responses of muscle spindles to small, slow movements in passive muscle and during fusimotor activity.

PubMed

Wise, A K; Gregory, J E; Proske, U

1999-03-06

We have previously shown that movement detection thresholds at the human elbow joint were less than a degree of joint rotation in the passive limb but were higher if they were measured while subjects co-contracted elbow muscles [A.K. Wise, J.E. Gregory, U. Proske, J. Physiol., 508 (1998) 325-330]. Here we report observations on the responses of muscle spindles of the soleus muscle of the anaesthetised cat to determine their ability to signal small length changes in the passive muscle and during a contraction, under conditions resembling those of the human experiments. After appropriate conditioning of the muscle to control for history effects, primary endings of muscle spindles showed thresholds to ramp stretch at 20 micrometers s-1 of between less than 5 micrometers and 15 micrometers, which translates to 0.05 degrees -0.15 degrees of human elbow joint rotation. Thresholds were much higher following conditioning to introduce slack in the muscle. Since during a voluntary contraction there is likely to be alpha:gamma co-activation, responses of spindles were also recorded during slow stretches (100 micrometers at 20 micrometers s-1) during static fusimotor stimulation, dynamic fusimotor stimulation, combined fusimotor stimulation and fusimotor plus skeletomotor stimulation. Invariably, responses to passive stretch were larger than during motor stimulation. It is concluded that spindles are sensitive enough to signal fractions of a degree of elbow joint rotation and that the rise in threshold observed during a voluntary contraction may be accounted for by the actions of fusimotor and skeletomotor axons on spindle stretch responses. Copyright 1999 Elsevier Science B.V.

Dynamic Interaction of Spindles and Gamma Activity during Cortical Slow Oscillations and Its Modulation by Subcortical Afferents

PubMed Central

Valencia, Miguel; Artieda, Julio; Bolam, J. Paul; Mena-Segovia, Juan

2013-01-01

Slow oscillations are a hallmark of slow wave sleep. They provide a temporal framework for a variety of phasic events to occur and interact during sleep, including the expression of high-frequency oscillations and the discharge of neurons across the entire brain. Evidence shows that the emergence of distinct high-frequency oscillations during slow oscillations facilitates the communication among brain regions whose activity was correlated during the preceding waking period. While the frequencies of oscillations involved in such interactions have been identified, their dynamics and the correlations between them require further investigation. Here we analyzed the structure and dynamics of these signals in anesthetized rats. We show that spindles and gamma oscillations coexist but have distinct temporal dynamics across the slow oscillation cycle. Furthermore, we observed that spindles and gamma are functionally coupled to the slow oscillations and between each other. Following the activation of ascending pathways from the brainstem by means of a carbachol injection in the pedunculopontine nucleus, we were able to modify the gain in the gamma oscillations that are independent of the spindles while the spindle amplitude was reduced. Furthermore, carbachol produced a decoupling of the gamma oscillations that are dependent on the spindles but with no effect on their amplitude. None of the changes in the high-frequency oscillations affected the onset or shape of the slow oscillations, suggesting that slow oscillations occur independently of the phasic events that coexist with them. Our results provide novel insights into the regulation, dynamics and homeostasis of cortical slow oscillations. PMID:23844020

An adult spindle cell rhabdomyosarcoma in the head and neck region with long-term survival: a case report

PubMed Central

2014-01-01

Introduction Spindle cell rhabdomyosarcoma of the head and neck is a very rare tumor in adults. We report on one case with long-term survival. Case presentation A 41-year-old nonsmoking Caucasian man presented in June 2007 with a painless swelling under his tongue. A diagnosis of a soft tissue sarcoma, and a myofibrosarcoma in particular, was made via biopsy. After multimodal treatment, including local and systemic therapy, our patient remained disease-free until September 2010. The local recurrence was treated unsuccessfully with various chemotherapy regimens. In September 2011, our patient underwent surgical resection again, and a spindle cell rhabdomyosarcoma was diagnosed. To analyze the mismatch between the original diagnosis of a myofibrosarcoma and the second diagnosis, the two specimens were reassessed, and a final diagnosis of a spindle cell rhabdomyosarcoma was made. In 2012 and 2013, our patient suffered further recurrences that were surgically treated, and he is still alive with disease six years and 10 months after the initial diagnosis in June 2007. Conclusions In adults, the spindle cell rhabdomyosarcoma tumor is very rare in the head and neck region. In contrast to childhood tumors, spindle cell rhabdomyosarcoma in adulthood is often associated with a poor prognosis. In the present case, the radical surgical treatment might have helped to prolong the patient’s overall survival, which has lasted more than six years. To our knowledge, this is the longest overall survival reported so far for this tumor entity in the head and neck region. PMID:24946859

Multipolar Spindle Pole Coalescence Is a Major Source of Kinetochore Mis-Attachment and Chromosome Mis-Segregation in Cancer Cells

PubMed Central

Silkworth, William T.; Nardi, Isaac K.; Scholl, Lindsey M.; Cimini, Daniela

2009-01-01

Many cancer cells display a CIN (Chromosome Instability) phenotype, by which they exhibit high rates of chromosome loss or gain at each cell cycle. Over the years, a number of different mechanisms, including mitotic spindle multipolarity, cytokinesis failure, and merotelic kinetochore orientation, have been proposed as causes of CIN. However, a comprehensive theory of how CIN is perpetuated is still lacking. We used CIN colorectal cancer cells as a model system to investigate the possible cellular mechanism(s) underlying CIN. We found that CIN cells frequently assembled multipolar spindles in early mitosis. However, multipolar anaphase cells were very rare, and live-cell experiments showed that almost all CIN cells divided in a bipolar fashion. Moreover, fixed-cell analysis showed high frequencies of merotelically attached lagging chromosomes in bipolar anaphase CIN cells, and higher frequencies of merotelic attachments in multipolar vs. bipolar prometaphases. Finally, we found that multipolar CIN prometaphases typically possessed γ-tubulin at all spindle poles, and that a significant fraction of bipolar metaphase/early anaphase CIN cells possessed more than one centrosome at a single spindle pole. Taken together, our data suggest a model by which merotelic kinetochore attachments can easily be established in multipolar prometaphases. Most of these multipolar prometaphase cells would then bi-polarize before anaphase onset, and the residual merotelic attachments would produce chromosome mis-segregation due to anaphase lagging chromosomes. We propose this spindle pole coalescence mechanism as a major contributor to chromosome instability in cancer cells. PMID:19668340

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soeda, Shuhei; Nakayama, Yuji, E-mail: nakayama@mb.kyoto-phu.ac.jp; Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414

Src-family tyrosine kinases are aberrantly activated in cancers, and this activation is associated with malignant tumor progression. v-Src, encoded by the v-src transforming gene of the Rous sarcoma virus, is a mutant variant of the cellular proto-oncogene c-Src. Although investigations with temperature sensitive mutants of v-Src have shown that v-Src induces many oncogenic processes, the effects on cell division are unknown. Here, we show that v-Src inhibits cellular proliferation of HCT116, HeLa S3 and NIH3T3 cells. Flow cytometry analysis indicated that inducible expression of v-Src results in an accumulation of 4N cells. Time-lapse analysis revealed that binucleation is induced throughmore » the inhibition of cytokinesis, a final step of cell division. The localization of Mklp1, which is essential for cytokinesis, to the spindle midzone is inhibited in v-Src-expressing cells. Intriguingly, Aurora B, which regulates Mklp1 localization at the midzone, is delocalized from the spindle midzone and the midbody but not from the metaphase chromosomes upon v-Src expression. Mklp2, which is responsible for the relocation of Aurora B from the metaphase chromosomes to the spindle midzone, is also lost from the spindle midzone. These results suggest that v-Src inhibits cytokinesis through the delocalization of Mklp1 and Aurora B from the spindle midzone, resulting in binucleation. -- Highlights: • v-Src inhibits cell proliferation of HCT116, HeLa S3 and NIH3T3 cells. • v-Src induces binucleation together with cytokinesis failure. • v-Src causes delocalization of Mklp1, Aurora B and INCENP from the spindle midzone.« less

"Fast" and "slow" skeleto-fusimotor innervation in cat tenuissimus spindles; a study with the glycogen-depletion method.

PubMed

Jami, L; Lan-Couton, D; Malmgren, K; Petit, J

1978-07-01

The glycogen-depletion method was used to investigate the motor supply to tenuissimus with respect to the presence of fast beta axons and to assess the total proportion of both fast and slow beta-innervated spindles in this muscle. In a first series of 5 expts., groups of motor axons with conduction velocities higher than 85 m/s were repetitively stimulated so as to produce glycogen depletion in the muscle fibres they innervated. The whole muscle was then quick-frozen, serially cut, stained to demonstrate glycogen and examined for intrafusal glycogen depletion. Zones of glycogen depletion were found in 16 of the 46 examined spindles; they were most frequently located in the longest of the chain intrafusal muscle fibres. Since it is known that there are no purely fusimotor axons to tenuissimus with conduction velocities above 50 m/s, it was concluded that beta axons are present among the fastest axons to this muscle. In a second series of 5 expts. as many motor axons as possible with conduction velocities above 60 m/s were stimulated. Zones of glycogen depletion were found in 19 of the 47 examined spindles. They affected chain fibres in about half of the instances and bag1 fibers in the others. As this latter location is characteristic of slow dynamic beta axons, it was concluded that both slow and fast beta axons occur regularly in the motor supply to tenuissimus. beta-innervation is present in at least 40% of tenuissimus spindles with almost no convergence of fast and slow beta axons onto the same spindle.

Synthesis, structural and optical properties of ZnO spindle/reduced graphene oxide composites with enhanced photocatalytic activity under visible light irradiation

NASA Astrophysics Data System (ADS)

Prabhu, S.; Pudukudy, M.; Sohila, S.; Harish, S.; Navaneethan, M.; Navaneethan, D.; Ramesh, R.; Hayakawa, Y.

2018-05-01

In the present work, spindle-shaped ZnO and reduced graphene oxide sheets were successfully synthesized by a hydrothermal method and then ZnO/r-GO composite was prepared by a direct solution mixing method. Various characterization results confirmed the interior and surface decoration of spindle-shaped ZnO on the reduced graphene oxide sheets. The phase formation, crystalline structure, morphology, surface states and optical properties were characterized using Powder X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis spectroscopy. The X-ray diffraction analysis showed the formation of the hexagonal wurtzite crystalline structure of ZnO with high crystalline quality. The band gap of the ZnO/r-GO composite was found to be low (3.03eV) compared to the band gap of spindle shaped ZnO (3.13 eV), as calculated from optical studies. The spindle-like morphology of the single crystalline ZnO was clearly shown in the electron microscopic images. The chemical bonding and surface states of the samples were studied using XPS measurement. Moreover, a possible growth mechanism for the ZnO spindle was proposed. The catalytic activity of the as-synthesized samples was evaluated for the photodegradation of methylene blue under visible light irradiation. Among the synthesized samples, the ZnO/r-GO composite showed higher degradation efficiency of 93% and successfully reused for four consecutive run without any activity loss.

Diverse mitotic functions of the cytoskeletal cross-linking protein Shortstop suggest a role in Dynein/Dynactin activity.

PubMed

Dewey, Evan B; Johnston, Christopher A

2017-09-15

Proper assembly and orientation of the bipolar mitotic spindle is critical to the fidelity of cell division. Mitotic precision fundamentally contributes to cell fate specification, tissue development and homeostasis, and chromosome distribution within daughter cells. Defects in these events are thought to contribute to several human diseases. The underlying mechanisms that function in spindle morphogenesis and positioning remain incompletely defined, however. Here we describe diverse roles for the actin-microtubule cross-linker Shortstop (Shot) in mitotic spindle function in Drosophila Shot localizes to mitotic spindle poles, and its knockdown results in an unfocused spindle pole morphology and a disruption of proper spindle orientation. Loss of Shot also leads to chromosome congression defects, cell cycle progression delay, and defective chromosome segregation during anaphase. These mitotic errors trigger apoptosis in Drosophila epithelial tissue, and blocking this apoptotic response results in a marked induction of the epithelial-mesenchymal transition marker MMP-1. The actin-binding domain of Shot directly interacts with Actin-related protein-1 (Arp-1), a key component of the Dynein/Dynactin complex. Knockdown of Arp-1 phenocopies Shot loss universally, whereas chemical disruption of F-actin does so selectively. Our work highlights novel roles for Shot in mitosis and suggests a mechanism involving Dynein/Dynactin activation. © 2017 Dewey and Johnston. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Heat shock cognate 71 (HSC71) regulates cellular antiviral response by impairing formation of VISA aggregates.

PubMed

Liu, Zhigang; Wu, Shu-Wen; Lei, Cao-Qi; Zhou, Qian; Li, Shu; Shu, Hong-Bing; Wang, Yan-Yi

2013-05-01

In response to viral infection, RIG-I-like RNA helicases detect viral RNA and signal through the mitochondrial adapter protein VISA. VISA activation leads to rapid activation of transcription factors IRF3 and NF-κB, which collaborate to induce transcription of type I interferon (IFN) genes and cellular antiviral response. It has been demonstrated that VISA is activated by forming prion-like aggregates. However, how this process is regulated remains unknown. Here we show that overexpression of HSC71 resulted in potent inhibition of virus-triggered transcription of IFNB1 gene and cellular antiviral response. Consistently, knockdown of HSC71 had opposite effects. HSC71 interacted with VISA, and negatively regulated virus-triggered VISA aggregation. These findings suggest that HSC71 functions as a check against VISA-mediated antiviral response.