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Sample records for midday aurorae

  1. Midday auroras and magnetospheric substorms.

    NASA Technical Reports Server (NTRS)

    Akasofu, S. I.

    1972-01-01

    Auroral activity in the midday sector is examined in some detail on the basis of all-sky photographs taken from Pyramida, Spitzbergen. The equatorward motion of the midday auroras observed during substorms and the subsequent poleward shift during the recovery phase are discussed.

  2. Measurements of optical and midday auroras

    NASA Technical Reports Server (NTRS)

    Sivjee, G. G.

    1974-01-01

    Measurements made in the midday auroras are analyzed and compared to measurements from the nighttime auroras. Examples are given of coordinated programs in Alaska which involve satellites, radars, ground optical instrumentation, and other types of observing satellites for the study of auroras.

  3. Coordinated analysis of airborne spectrophotometric measurements from the mid-day auroras

    NASA Technical Reports Server (NTRS)

    Sivjee, G. G.

    1974-01-01

    Measurements made in the midday auroras are analyzed and compared to measurements from the nighttime auroras. The auroral emission features in the UV spectrum, the N2(+)ING, the N22PG, and N2VK bands, are discussed. Spectral profiles of different bands are presented, and intensity distributions are obtained. Three mechanisms are suggested which can account for the marked differences between the intensity distributions of the N2(+)ING bands of the high altitude midday auroras and the low altitude nighttime auroras: (1) differences in vibrational, rotational, and transitional temperatures; (2) resonant scattering of solar radiation; and (3) excitation of slow ions.

  4. Electron precipitation in the midday auroral oval

    SciTech Connect

    Meng, C.

    1981-04-01

    Simultaneous observations of auroral displays and electron precipitations by the DMSP 33 satellite provide an excellent and unique opportunity to study precipitation characteristics of the midday auroral oval. Attention is given to two topics: (1) the nature of the 'gap' of the midday discrete auroras which is a permanent feature of the dayside auroral oval observed by both Isis 2 and DMSP satellites and (2) the relationship of this gap with the polar cusp region. Based on 2-month (June, July 1975) observations of the midday auroras over the southern hemisphere, it is found that inside the 'gap' of the discrete auroras along the dayside auroral oval, soft electron precipitations with a magnetosheathlike spectrum were invariably detected. The spatial extent of this region was about few degrees in latitude and about 2--3 hours in local time near 1130 magnetic local time meridian. No significant electron precipitation was detected poleward of the instantaneous midday auroral oval. Typical plasma sheet and discrete auroral types of electron precipitations were detected in the other parts of the midday auroral oval. Therefore it is proposed that the ionospheric projection of the polar cusp is a small region of the instantaneous dayside auroral oval near the noon meridian, coinciding with the 'gap' of the midday discrete auroras.

  5. Rainbow Near Midday

    NASA Astrophysics Data System (ADS)

    Cornell, David A.

    2012-12-01

    It was near midday on Sunday, Sept. 25, 2011. My family and I were coming home in the car when we saw strongly colored bands in the sky near the northern horizon. The effect was striking and attracted motorists to stop and gaze at it. Houses in the north seemed to be wearing a gently curving band of colors above the roof. If this were a rainbow, it was like no other that I had seen before. I quickly ran to get a camera to capture the effect before it vanished. See Fig. 1 for an image of the phenomenon.

  6. Aurora Australis

    NASA Video Gallery

    Video of the Aurora Australis taken by the crew of Expedition 29 on board the International Space Station. This sequence of shots was taken September 17, 2011 from 17:22:27 to 17:45:12 GMT, on an a...

  7. Watching the Earth Spin: A Determination of Midday.

    ERIC Educational Resources Information Center

    Hansgen, Richard

    1995-01-01

    Presents activities that enable students to determine the exact time of midday and to use this to plot a north-south line. Uses shadow experiments to teach the concepts of rotation of the earth and calculation of latitude. (JRH)

  8. SSUSI Aurora Forecast Model

    NASA Astrophysics Data System (ADS)

    Hsieh, S. W.; Zhang, Y.; Schaefer, R. K.; Romeo, G.; Paxton, L.

    2013-12-01

    A new capability has been developed at JHU/APL for forecasting the global aurora quantities based on the DMSP SSUSI data and the TIMED/GUVI Global Aurora Model. The SSUSI Aurora Forecast Model predicts the electron energy flux, mean energy, and equatorward boundary in the auroral oval for up to 1 day or 15 DMSP orbits in advance. In our presentation, we will demonstrate this newly implemented capability and its results. The future improvement plan will be discussed too.

  9. Modeling the Jovian aurora

    NASA Technical Reports Server (NTRS)

    Waite, J. Hunter, Jr.

    1992-01-01

    The Jovian aurora is the most powerful aurora in the solar system, over 100 times more powerful than the Earth's aurora. These magnificent visual displays can provide important information about the planetary magnetosphere which is responsible for the acceleration of energetic particles that produce aurora at any planet. Similarities and differences in planetary auroral emissions are thus a viable means of classifying and studying both comparative atmospheric and magnetospheric processes. For instance, at Earth the solar wind is the primary source of auroral power while at Jupiter it is conjectured that the rotation of the planet is the major source of magnetospheric and auroral power. The purpose of this IR project was to develop a model: (1) for use in interpreting the existing set of multispectral observations of Jupiter's aurora; and (2) to design new experiments based on the findings to improve understanding of the underlying auroral processes.

  10. Sleep spindles in midday naps enhance learning in preschool children.

    PubMed

    Kurdziel, Laura; Duclos, Kasey; Spencer, Rebecca M C

    2013-10-22

    Despite the fact that midday naps are characteristic of early childhood, very little is understood about the structure and function of these sleep bouts. Given that sleep benefits memory in young adults, it is possible that naps serve a similar function for young children. However, children transition from biphasic to monophasic sleep patterns in early childhood, eliminating the nap from their daily sleep schedule. As such, naps may contain mostly light sleep stages and serve little function for learning and memory during this transitional age. Lacking scientific understanding of the function of naps in early childhood, policy makers may eliminate preschool classroom nap opportunities due to increasing curriculum demands. Here we show evidence that classroom naps support learning in preschool children by enhancing memories acquired earlier in the day compared with equivalent intervals spent awake. This nap benefit is greatest for children who nap habitually, regardless of age. Performance losses when nap-deprived are not recovered during subsequent overnight sleep. Physiological recordings of naps support a role of sleep spindles in memory performance. These results suggest that distributed sleep is critical in early learning; when short-term memory stores are limited, memory consolidation must take place frequently. PMID:24062429

  11. Sleep spindles in midday naps enhance learning in preschool children

    PubMed Central

    Kurdziel, Laura; Duclos, Kasey; Spencer, Rebecca M. C.

    2013-01-01

    Despite the fact that midday naps are characteristic of early childhood, very little is understood about the structure and function of these sleep bouts. Given that sleep benefits memory in young adults, it is possible that naps serve a similar function for young children. However, children transition from biphasic to monophasic sleep patterns in early childhood, eliminating the nap from their daily sleep schedule. As such, naps may contain mostly light sleep stages and serve little function for learning and memory during this transitional age. Lacking scientific understanding of the function of naps in early childhood, policy makers may eliminate preschool classroom nap opportunities due to increasing curriculum demands. Here we show evidence that classroom naps support learning in preschool children by enhancing memories acquired earlier in the day compared with equivalent intervals spent awake. This nap benefit is greatest for children who nap habitually, regardless of age. Performance losses when nap-deprived are not recovered during subsequent overnight sleep. Physiological recordings of naps support a role of sleep spindles in memory performance. These results suggest that distributed sleep is critical in early learning; when short-term memory stores are limited, memory consolidation must take place frequently. PMID:24062429

  12. Look out, aurorae about!

    NASA Astrophysics Data System (ADS)

    Wild, Jim

    2006-02-01

    Myths and legends abound concerning the aurora borealis; observations, at least in the UK, are considerably more rare, yet people continue to be interested in observing them on the few times a year they are visible. AuroraWatch hopes to boost this interest by providing an email alert service that, since 2000, has used real-time information from a network of magnetometers to assess when aurorae might be visible. Alerts can be sent to mobile phones as well as by conventional email, and have already enabled many people to see this beautiful natural phenomenon.

  13. Aurora final report

    SciTech Connect

    Robert, Dross; Amedeo, Conti

    2013-12-06

    Final Technical report detailing the work done by Nuvera and its partners to fulfill the goals of the program "Transport Studies Enabling Efficiency Optimization of Cost-Competitive Fuel Cell Stacks" (a.k.a. AURORA)

  14. The dynamic aurora

    SciTech Connect

    Akasofu, Syunichi )

    1989-05-01

    Auroral physicists today know that auroras are lights emitted when atoms and molecules in the ionosphere are struck by electrons blowing in from the sun. The apparent motion of the auroral curtain is caused not by atmospheric turbulence but by changes in the electromagnetic conditions that propel the electrons, just as motion on a television screen is an illusion created by changes in the magnetic field that directs electrons from a cathode tube onto the screen. In the case of the aurora, what serves as the cathode tube Where is its power supply Why does that power seem to fluctuate from time to time, causing the aurora to ebb and flow across the polar sky More than 20 years ago it was determined that auroral emissions occur because the ionosphere is bombarded by electron beams generated by a complex interaction between the solar wind and the earth's magnetic envelope. The geomagnetic nature of the aurora can be seen clearly from outer space. Centered on each of the geomagnetic poles is a great luminous oval that is a permanent feature of the planet. The one around the North Pole is the aurora borealis. Its counterpart in the south is the aurora australis. The authors and his colleagues have now found a numerical relation between the solar wind and the generation of the power that drives the aurora, as well as other disturbances of the geomagnetic field. They are also gaining a better idea of how the sun's activity affects the solar wind. This progress raises the interesting possibility of developing a computer method to predict the intensity of auroral activity. Because auroras can interfere significantly with radio and satellite communications, as well as with power lines and some defense systems, the ability to predict auroral intensity has become increasingly important as human activity expands into polar regions and into space.

  15. AuroraMAX!

    NASA Astrophysics Data System (ADS)

    Donovan, E.; Spanswick, E. L.; Chicoine, R.; Pugsley, J.; Langlois, P.

    2011-12-01

    AuroraMAX is a public outreach and education initiative that brings auroral images to the public in real time. AuroraMAX utilizes an observing station located just outside Yellowknife, Canada. The station houses a digital All-Sky Imager (ASI) that collects full-colour images of the night sky every six seconds. These images are then transmitted via satellite internet to our web server, where they are made instantly available to the public. Over the last two years this program has rapidly become one of the most successful outreach programs in the history of Space Science in Canada, with hundreds of thousands of distinct visitors to the CSA AuroraMAX website, thousands of followers on social media, and hundreds of newspaper, magazine, radio, and television spots. Over the next few years, the project will expand to include a high-resolution SLR delivering real-time auroral images (also from Yellowknife), as well as a program where astronauts on the ISS will take pictures of the aurora with a handheld SLR. The objectives of AuroraMAX are public outreach and education. The ASI design, operation, and software were based on infrastructure that was developed for the highly successful ASI component of the NASA THEMIS mission as well as the Canadian Space Agency (CSA) Canadian GeoSpace Monitoring (CGSM) program. So from an education and public outreach perspective, AuroraMAX is a single camera operating in the Canadian north. On the other hand, AuroraMAX is one of nearly 40 All-Sky Imagers that are operating across North America. The AuroraMAX camera produces data that is seamlessly integrated with the CGSM ASI data, and made widely available to the Space Science community through open-access web and FTP sites. One of our objectives in the next few years is to incorporate some of the data from the THEMIS and CGSM imagers into the AuroraMAX system, to maximize viewing opportunities and generate more real-time data for public outreach. This is an exemplar of a program that

  16. A single starfish Aurora kinase performs the combined functions of Aurora-A and Aurora-B in human cells.

    PubMed

    Abe, Yusuke; Okumura, Eiichi; Hosoya, Takamitsu; Hirota, Toru; Kishimoto, Takeo

    2010-11-15

    Aurora, an essential mitotic kinase, is highly conserved during evolution. Most vertebrates have at least two Aurora kinases, Aurora-A and Aurora-B, which have distinct functions in the centrosome-spindle and inner centromere-midbody, respectively. However, some non-vertebrate deuterostomes have only a single Aurora. It remains to be verified whether the single Aurora performs the same functions as vertebrate Auroras A and B combined. We have isolated a cDNA of a single Aurora (ApAurora) from the echinoderm starfish, Asterina pectinifera, and show that ApAurora displays most features of both Aurora-A and Aurora-B in starfish oocytes and early embryos. Furthermore, ApAurora that is stably expressed in HeLa cells can substitute for both human Aurora-A and Aurora-B when either is reduced by RNAi. A single ApAurora thus has properties of both Aurora-A and Aurora-B in starfish eggs and HeLa cells. Together with phylogenetic analysis indicating that ApAurora forms a clade with all types of vertebrate Auroras and single Auroras of non-vertebrate deuterostomes, our observations support the idea that the single Aurora found in non-vertebrate deuterostomes represents the ancestor that gave rise to various types of vertebrate Auroras. This study thus provides functional evidence for phylogenetic considerations. PMID:21048162

  17. NASA Observes Auroras Across Canada

    NASA Video Gallery

    The dancing lights in the image above are the aurora borealis, viewed from the ground looking up. The aurora shown above occurred as the result of a CME that struck Earth’s magnetic field early on ...

  18. Space Weather and Earth's Aurora

    NASA Video Gallery

    Aurora are colorful lights in the night time sky primarily appearing in Earth's polar regions. But what causes them? The culprit behind aurora is our own Sun and the solar plasma that is ejected du...

  19. Understanding the theta aurora

    NASA Astrophysics Data System (ADS)

    Fear, Robert; Milan, Steve; Carter, Jennifer; Maggiolo, Romain; Fazakerley, Andrew; Dandouras, Iannis; Mende, Stephen

    2015-04-01

    The theta aurora, first observed by Dynamics Explorer in the 1980s, is a configuration of the Earth's aurora in which auroral emissions extend into and across the polar cap in the form of a transpolar arc. It is well established that the theta aurora occurs predominantly when the interplanetary magnetic field has a northward component, but over the last thirty years various mechanisms have been put forward to explain this intriguing phenomenon. In the last couple of years, a range of evidence has accumulated which strongly suggests that the transpolar arc is formed as proposed by Milan et al. (2005): magnetotail reconnection occurs during intervals of northward IMF, which results in a local "wedge" of closed magnetospheric flux that remains trapped in the magnetotail. Precipitation on these closed field lines results in the transpolar arc analogously to the formation of the aurora in the main oval. Evidence for magnetotail reconnection as the cause of the theta aurora includes the timescales necessary to influence the location at which the transpolar arc forms, and the presence of characteristic ionospheric flows which are excited by magnetotail reconnection and which are statistically associated with transpolar arcs (Fear & Milan, 2012a,b). Most recently, direct observation has been made of a localised wedge of closed magnetic flux, "trapped" in the lobe, which was observed to move back and forth in a manner which (to our knowledge) can only be explained by the magnetotail reconnection mechanism (Fear et al., 2014). In this talk, we summarise the evidence for the formation of the theta aurora by magnetotail reconnection, and discuss the remaining challenges in obtaining a comprehensive understanding of this spectacular phenomenon.

  20. Structure of black aurora associated with pulsating aurora

    NASA Astrophysics Data System (ADS)

    Fritz, Bruce A.; Lessard, Marc L.; Blandin, Matthew J.; Fernandes, Philip A.

    2015-11-01

    Morphological behavior of black aurora as it relates to pulsating aurora is investigated by examining a collection of ground-based observations from January 2007 in support of the Rocket Observations of Pulsating Aurora rocket campaign. Images were sampled from video recorded by a Xybion intensified camera (30 fps) at Poker Flat Research Range, AK. The primary observations of black aurora recorded during the substorm recovery phase were between separate patches of pulsating aurora as well as pulsating aurora separated from diffuse aurora. In these observations the black aurora forms an apparent firm boundary between the auroral forms in a new behavior that is in contrast with previously reported observations. Also presented for the first time are black curls in conjunction with pulsating aurora. Curl structures that indicate shear plasma flows in the ionosphere may be used as a proxy for converging/diverging electric fields in and above the ionosphere. This new subset of black auroral behavior may provide visual evidence of black aurora as an ionospheric feedback mechanism as related to pulsating aurora.

  1. Thermospheric aurora and airglow

    SciTech Connect

    Meier, R.R.

    1987-04-01

    New information added in the years between 1983 and 1986 to the understanding of the physics and chemistry responsible for the production of aurora and airglow emissions is presented. On auroras, the bulk of new information comes from the information obtained from satellite-based imaging (by DE1) and spectroscopy, rocket-based observations of bremsstrahlung from electrons precipitating in the auroral zone, and measurements of metastable ion species. On airglow, the DE1 photometric experiment has provided the opportunity of studying the geocorona on a global scale. A geotail was detected in the antisolar direction, confirming earlier observations. 123 references.

  2. Fast aurora zone analysis

    NASA Technical Reports Server (NTRS)

    Booker, Mattie

    1992-01-01

    The Flight Dynamics Facility (FDF) of the Flight Dynamics Division (FDD), of the Goddard Space Flight Center provides acquisition data to tracking stations and orbit and attitude services to scientists and mission support personnel. The following paper explains how a method was determined that found spacecraft entry and exit times of the aurora zone.

  3. Tabletop Aurora Demonstrator.

    ERIC Educational Resources Information Center

    Zaffo, Peter Alfred

    1991-01-01

    A simple apparatus for studying various forms of the aurora borealis on a miniature scale can be constructed from a neon-storage flask, aluminum tape, a cardboard box, and a small piezoelectric ion gun of the type used to neutralize static charges on phonograph records. (PR)

  4. Midday Naps and the Risk of Coronary Artery Disease: Results of the Heinz Nixdorf Recall Study

    PubMed Central

    Stang, Andreas; Dragano, Nico; Moebus, Susanne; Möhlenkamp, Stefan; Schmermund, Axel; Kälsch, Hagen; Erbel, Raimund; Jöckel, Karl-Heinz

    2012-01-01

    Study Objectives: Several studies have assessed the association between midday nap and cardiovascular outcomes and reported heterogenous results. Concern exists that confounding might have distorted these results and contributed to discrepancies among them. This study prospectively examines the association between midday nap habits and the occurrence of coronary artery disease in a non-Mediterranean population. Participants: The baseline examination of 4,123 participants aged 45–75 years. Measurements: Measurements included interviews, physical examinations, laboratory tests, and electron beam computed tomography. We studied the influence of midday nap habits on risk of coronary artery disease. We adjusted for several potential confounders including measures of subclinical atherosclerosis—such as coronary calcium score and ankle brachial index—at baseline. Cardiac events during a median follow-up of 8.1 years were defined as nonfatal myocardial infarction and sudden cardiac death. Results: Overall, 135 of 4,123 subjects (3.3%) either suffered from acute myocardial infarction (81 subjects) or died due to a sudden cardiac death (54 subjects) during follow-up. After adjustment for several confounders including measures of subclinical atherosclerosis, regular long (> 60 min) midday nap was associated with an increased hazard ratio of cardiac events (hazard ratio 2.12, 95% confidence interval 1.11–4.05). Conclusions: As our detailed confounder analyses showed, confounding is not the sole explanation for this finding. Future research on midday naps should focus on biological mechanisms that may be responsible for increasing the risk of coronary artery disease among subjects taking regular long midday naps. Citation: Stang A; Dragano N; Moebus S; Möhlenkamp S; Schmermund A; Kälsch H; Erbel R; Jöckel KH. Midday naps and the risk of coronary artery disease: results of the Heinz Nixdorf Recall Study. SLEEP 2012;35(12):1705–1712. PMID:23204613

  5. Visible Jovian Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jupiter's aurora on the night side of the planet is seen here at five different wavelengths. Jupiter's bright crescent, which is about half illuminated, is out of view to the right. North is at the top. The images are centered at 57 degrees north and 184 degrees West and were taken on April 2, 1997 at a range of 1.7 million kilometers (1.05 million miles) by the Solid State Imaging (SSI) camera system aboard NASA's Galileo spacecraft.

    Although Jupiter's aurora had been imaged from Earth in the ultraviolet and infrared, these are the first images at visible wavelengths, where most of the emission takes place. CLR stands for clear (no filter) and shows the integrated brightness at all wavelengths. The other panels show the violet, green, red, and 889 nanometer-wavelength filtered images. The brightness of the aurora is roughly independent of wavelength, at least at the spectral resolution obtainable with these filters.

    As on Earth, the aurora is caused by electrically charged particles striking the upper atmosphere, causing the molecules of the atmosphere to glow. The brightness in the different filters contains information about the energy of the impinging particles and the composition of the upper atmosphere. If atomic hydrogen were the only emitter, the light would be much stronger in the red filter, which is not consistent with the observed distribution.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.

  6. Baxter Aurora dialysis system.

    PubMed

    Kelly, Thomas D

    2004-01-01

    With the recent focus on the benefits of more frequent dialysis, the Baxter Aurora dialysis system provides maximum flexibility for therapy prescription, including short daily treatments, long nocturnal treatments, hemodialysis, hemofiltration, and online hemodiafiltration, all in a compact, reliable, easy to use system. A self-prompting touch screen user interface mounted on a movable arm provides for comfortable operation, whether sitting and standing. An automatic treatment setup mode facilitates easy treatment setup. Complex menus are eliminated by the use of a hardware key that automatically selects only the prescribed options during power up, eliminating all menus associated with nonprescribed functions and modalities. This prevents the user from becoming confused or accidentally altering the dialysis treatment. Prior to dialysis the instrument goes through an automatic self-test that confirms the operation of internal systems. The screen will dim when there is no action that the patient needs to attend to on the instrument. After dialysis, press the disinfect button and the instrument disinfects itself and shuts off. For patient safety, the "disinfect" menus are not available during dialysis. The instrument can also be programmed to automatically start and rinse at a set time. For remote treatment monitoring, the instrument connects to the Internet. The Aurora records information about the machine's technical status, providing a record of instrument history for easy servicing. The Aurora is a flexible platform that provides the desired renal therapy with ease of use and proper support for the hemodialysis patient when combined with Baxter's 24-hour infrastructure and support. PMID:15043620

  7. Characteristics of Pulsating Aurora

    NASA Astrophysics Data System (ADS)

    Humberset, B. K.; Gjerloev, J. W.; Mann, I. R.; Samara, M.; Michell, R.

    2013-12-01

    We have investigated the spatiotemporal characteristics of pulsating auroral patches observed with an all-sky imager located at Poker Flat, Alaska. Pulsating aurora often covers the entire sky with intermixed large and small-scale patches that vary in intensity or disappear and reappear on different time scales and timings. The broad definition of pulsating aurora covers patches and bands from tens to several tens of km which have a quasi-periodic temporal variation from 1 s to tens of seconds. In this paper we examine >15 patches from different events. We analyze all-sky movies (557.7 nm, 3.31 Hz) with a simple, yet robust, technique that allows us to determine the scale size dependent variability of the >15 individual patches. A spatial 2D Fourier Transform is used to separate the aurora into different horizontal scale sizes, and by correlating each patch for all image separations and available scale sizes smaller than the patch itself, we reveal what scale sizes are pulsating and their variability. The patches are found to be persistent, meaning that we can follow them for typically 5 minutes. The period of the pulsations is often remarkably variable and it seems that only certain scale sizes pulsate (typically the size of the patch). The patches drift with the background ExB plasma drift indicating that the magnetospheric source mechanism drifts with the field lines.

  8. Pulsating aurora: Source region & morphology

    NASA Astrophysics Data System (ADS)

    Jaynes, Allison

    Pulsating aurora, a common phenomenon in the polar night sky, offers a unique opportunity to study the precipitating particle populations responsible for this subtle yet fascinating display of lights. The conjecture that the source of these electrons originates near the equator, made decades ago, has now been confirmed using in-situ measurements. In this thesis, we present these results that compare the frequencies of equatorial electron flux pulsations and pulsating aurora luminosity fluctuations at the ionospheric footprint. We use simultaneous satellite-based data from GOES 13 and ground-based data from the THEMIS allsky imager array to show that there is a direct correlation between luminosity fluctuations near the ground and particle pulsations in equatorial space; the source region of the pulsating aurora. Pulsating aurora almost exclusively occurs embedded within a region of diffuse aurora. By studying the two particle populations, one can contribute to the theory behind auroral pulsations. The interplay between the two auroral types, and the systems that control them, are not yet well known. We analyze ground optical observations of pulsating aurora events to attempt to characterize the relationship between the two types of auroral precipitation. Pulsating aurora is a significant component of energy transfer within the framework of magnetosphere-ionosphere coupling. Further study of the morphology, total energy deposition, and the pulsation mechanism of pulsating aurora is key to a better understanding of our earth-sun system.

  9. Night Side Jovian Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Jovian aurora on the night side of the planet. The upper bright arc is auroral emission seen 'edge on' above the planetary limb with the darkness of space as a background. The lower bright arc is seen against the dark clouds of Jupiter. The aurora is easier to see on the night side of Jupiter because it is fainter than the clouds when they are illuminated by sunlight. Jupiter's north pole is out of view to the upper right. The images were taken in the clear filter (visible light) and are displayed in shades of blue.

    As on Earth, the auroral emission is caused by electrically charged particles striking the upper atmosphere from above. The particles travel along the magnetic field lines of the planet, but their origin is not fully understood. The field lines where the aurora is most intense cross the Jovian equator at large distances (many Jovian radii) from the planet. The faint background throughout the image is scattered light in the camera. This stray light comes from the sunlit portion of Jupiter, which is out of the image to the right. In multispectral observations the aurora appears red, consistent with glow from atomic hydrogen in Jupiter's atmosphere. Galileo's unique perspective allows it to view the night side of the planet at short range, revealing details that cannot be seen from Earth. These detailed features are time dependent, and can be followed in sequences of Galileo images.

    North is at the top of the picture. A grid of planetocentric latitude and west longitude is overlain on the images. The images were taken on November 5, 1997 at a range of 1.3 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the

  10. The theta aurora

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Craven, J. D.; Gurnett, D. A.; Shawhan, S. D.; Burch, J. L.; Winningham, J. D.; Chappell, C. R.; Waite, J. H.; Maynard, N. C.; Sugiura, M.

    1986-01-01

    A comprehensive review is presented of the characteristics of theta aurora as revealed from four imaging efforts with the DE 1 and 2 satellites. The theta aurora consists of an auroral oval with a sun-aligned arc extending from the dayside to the nightside sectors of the oval. The DE 1 spacecraft provided high altitude simultaneous measurements of the electric and magnetic fields and plasma and the DE 2 collected equivalent low altitude data on the four events. The plasma was found to convect sunward when the transpolar arc appeared, while the convection was antisunward in other regions over the polar cap. The arc plasmas featured field-aligned electron acceleration into the polar atmosphere and field-aligned current sheets, both of which were sparse over the rest of the polar cap. The ions originated in the ionosphere and the solar wind; ions over the rest of the polar cap mainly arrived from the magnetosphere. Further discussions are provided of the dominant electrons and ions and the associated flow directions into and out of the various regions of the pole, similarities between the transpolar arc and the auroral oval, and interactions between the ionosphere and the auroral phenomena.

  11. Simultaneous observations of auroras from the South Pole Station and of precipitating electrons by Isis 1.

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Heikkila, W. J.; Akasofu, S.-I.; Yasuhara, F.

    1973-01-01

    On the basis of the simultaneous observations of auroras from the South Pole and of precipitating electrons by the Isis 1 satellite it is shown that (1) a midday auroral arc (photographed on black and white film) occurs within the cleft (cusp) region projected to the appropriate auroral height along the geomagnetic field; (2) in the evening sector an aurora, observed by Isis 1 and the South Pole all-sky camera, extended for at least 5 hours of local geomagnetic time in the expected position of the auroral oval; and (3) during a period of extreme magnetic quiet, cleftlike electrons were observed just poleward of a narrow region of intense precipitation in the midnight sector. An earth-sun oriented arc was seen at the projected location of the intense electron flux.

  12. Aurorae in Australian Aboriginal Traditions

    NASA Astrophysics Data System (ADS)

    Hamacher, Duane W.

    2013-07-01

    Transient celestial phenomena feature prominently in the astronomical knowledge and traditions of Aboriginal Australians. In this paper, I collect accounts of the Aurora Australis from the literature regarding Aboriginal culture. Using previous studies of meteors, eclipses, and comets in Aboriginal traditions, I anticipate that the physical properties of aurora, such as their generally red colour as seen from southern Australia, will be associated with fire, death, blood, and evil spirits. The survey reveals this to be the case and also explores historical auroral events in Aboriginal cultures, aurorae in rock art, and briefly compares Aboriginal auroral traditions with other global indigenous groups, including the Maori of New Zealand.

  13. Aurora Australis over Indian Ocean

    NASA Video Gallery

    Video of the Aurora Australis taken by the crew of Expedition 28 on board the International Space Station. This sequence of shots was taken September 7, 2011 from 17:38:03 to 17:49:15 GMT, from the...

  14. Aurora Australis, Seen From Space

    NASA Video Gallery

    This video of the Aurora Australis was created from a sequence of still shots taken by astronauts on board the International Space Station. The images were acquired on September 11, 2011 as the ISS...

  15. Aurora Kinase Inhibitors: Current Status and Outlook

    PubMed Central

    Bavetsias, Vassilios; Linardopoulos, Spiros

    2015-01-01

    The Aurora kinase family comprises of cell cycle-regulated serine/threonine kinases important for mitosis. Their activity and protein expression are cell cycle regulated, peaking during mitosis to orchestrate important mitotic processes including centrosome maturation, chromosome alignment, chromosome segregation, and cytokinesis. In humans, the Aurora kinase family consists of three members; Aurora-A, Aurora-B, and Aurora-C, which each share a conserved C-terminal catalytic domain but differ in their sub-cellular localization, substrate specificity, and function during mitosis. In addition, Aurora-A and Aurora-B have been found to be overexpressed in a wide variety of human tumors. These observations led to a number of programs among academic and pharmaceutical organizations to discovering small molecule Aurora kinase inhibitors as anti-cancer drugs. This review will summarize the known Aurora kinase inhibitors currently in the clinic, and discuss the current and future directions. PMID:26734566

  16. False Color Aurora

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Data from NASA's Galileo spacecraft were used to produce this false-color composite of Jupiter's northern aurora on the night side of the planet. The height of the aurora, the thickness of the auroral arc, and the small-scale structure are revealed for the first time. Images in Galileo's red, green, and clear filters are displayed in red, green, and blue respectively. The smallest resolved features are tens of kilometers in size, which is a ten-fold improvement over Hubble Space Telescope images and a hundred-fold improvement over ground-based images.

    The glow is caused by electrically charged particles impinging on the atmosphere from above. The particles travel along Jupiter's magnetic field lines, which are nearly vertical at this latitude. The auroral arc marks the boundary between the 'closed' field lines that are attached to the planet at both ends and the 'open' field lines that extend out into interplanetary space. At the boundary the particles have been accelerated over the greatest distances, and the glow is especially intense.

    The latitude-longitude lines refer to altitudes where the pressure is 1 bar. The image shows that the auroral emissions originate about 500 kilometers (about 310 miles) above this surface. The colored background is light scattered from Jupiter's bright crescent, which is out of view to the right. North is at the top. The images are centered at 57 degrees north and 184 degrees west and were taken on April 2, 1997 at a range of 1.7 million kilometers (1.05 million miles) by Galileo's Solid State Imaging (SSI) system.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at: http:// galileo.jpl.nasa.gov. Background information and educational context for the images can be found at: http:/ /www.jpl.nasa.gov/galileo/sepo.

  17. Pulsating aurora: The importance of the ionosphere

    SciTech Connect

    Stenbaek-Nielsen, H.C.

    1980-05-01

    A number of different, but mainly optical, observations made in pulsating auroras are presented. These observations indicate that active ionospheric processes are likely to play an important role in causing and/or modifying pulsating aurora.

  18. Aurorae and Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  19. Aurorae and Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  20. Triton torus and Neptune aurora

    NASA Technical Reports Server (NTRS)

    Cheng, Andrew F.

    1990-01-01

    Triton is shown to be the dominant source of plasma for L equal to or greater than 7 in the magnetosphere of Neptune. Triton maintains a neutral hydrogen torus of average density comparable to a greater than that of the Titan torus at Saturn. The Triton torus may be detectable in H Lyman-alpha emissions. However, the energy source from plasma outward transport and mass loading in the Triton torus is insufficient to explain the Neptune aurora. It is proposed that Neptune's aurora is driven mainly by a solar wind interaction.

  1. Spatial Compartmentalization Specializes the Function of Aurora A and Aurora B*

    PubMed Central

    Li, Si; Deng, Zhaoxuan; Fu, Jingyan; Xu, Caiyue; Xin, Guangwei; Wu, Zhige; Luo, Jia; Wang, Gang; Zhang, Shuli; Zhang, Boyan; Zou, Fangdong; Jiang, Qing; Zhang, Chuanmao

    2015-01-01

    Aurora kinase A and B share great similarity in sequences, structures, and phosphorylation motif, yet they show different localizations and play distinct crucial roles. The factors that determine such differences are largely unknown. Here we targeted Aurora A to the localization of Aurora B and found that Aurora A phosphorylates the substrate of Aurora B and substitutes its function in spindle checkpoint. In return, the centrosome targeting of Aurora B substitutes the function of Aurora A in the mitotic entry. Expressing the chimera proteins of the Auroras with exchanged N termini in cells indicates that the divergent N termini are also important for their spatiotemporal localizations and functions. Collectively, we demonstrate that functional divergence of Aurora kinases is determined by spatial compartmentalization, and their divergent N termini also contribute to their spatial and functional differentiation. PMID:25987563

  2. Spatial Compartmentalization Specializes the Function of Aurora A and Aurora B.

    PubMed

    Li, Si; Deng, Zhaoxuan; Fu, Jingyan; Xu, Caiyue; Xin, Guangwei; Wu, Zhige; Luo, Jia; Wang, Gang; Zhang, Shuli; Zhang, Boyan; Zou, Fangdong; Jiang, Qing; Zhang, Chuanmao

    2015-07-10

    Aurora kinase A and B share great similarity in sequences, structures, and phosphorylation motif, yet they show different localizations and play distinct crucial roles. The factors that determine such differences are largely unknown. Here we targeted Aurora A to the localization of Aurora B and found that Aurora A phosphorylates the substrate of Aurora B and substitutes its function in spindle checkpoint. In return, the centrosome targeting of Aurora B substitutes the function of Aurora A in the mitotic entry. Expressing the chimera proteins of the Auroras with exchanged N termini in cells indicates that the divergent N termini are also important for their spatiotemporal localizations and functions. Collectively, we demonstrate that functional divergence of Aurora kinases is determined by spatial compartmentalization, and their divergent N termini also contribute to their spatial and functional differentiation. PMID:25987563

  3. Electrodynamics of the Duskside Aurora

    NASA Astrophysics Data System (ADS)

    Shue, J.; Newell, P. T.; Liou, K.; Meng, C.; Germany, G. A.; Hairston, M. R.; Rich, F. J.

    2002-12-01

    Shue et al. [2002] reported that an auroral feature, which is called the two-cell aurora, was identified from Polar Ultraviolet Imager auroral images. The characteristics of the two-cell aurora are azimuthal elongation over extended local times with gaps at noon and midnight. Its electrodynamic association with the convection, particle precipitation, and field-aligned currents has not been fully understood. In conjunctions with DMSP F12 spacecraft on the duskside branch of the aurora, we are able to investigate the association of auroral emissions with convection reversals, upward field-aligned currents, and energy fluxes and average energy of particles. It is found that the location of the convection reversal is colocated with the upward field-aligned currents. The maximum auroral emissions occur at or poleward of the convection reversals. The energy flux and average energy derived from auroral images are consistent with observations from DMSP in a region mapped to the plasma sheet. However, inconsistency occurs in a region mapped to the plasma sheet boundary layer. Shue, J.-H., P. T. Newell, K. Liou, C.-I. Meng, Y. Kamide, and R. P. Lepping, Two-component auroras, Geophys. Res. Lett., 29(10), 10.1029/2002GL14657, 2002.

  4. Ionospheric Response to Flickering Aurora

    NASA Astrophysics Data System (ADS)

    Gustavsson, B.; Grydeland, T.; Blixt, M.; Baddeley, L.; Lunde, J.

    2007-12-01

    Flickering aurora is characterized by optical emissions varying in intensity with frequencies typically between 5 and 20 Hz. Here we use high-speed narrow field-of-view imaging in white light to determine the intensity variation in the field aligned direction, which is also the direction of the beam of the EISCAT Svalbard Radar (ESR). Incoherent scatter radar data is noise-like, and must be integrated over multiple pulses to reduce the variance to useful levels, even for high signal to noise ratios. Usually, this means integrating over several seconds to some tens of seconds of observation, which is not very useful with respect to flickering aurora. In the experiment presented here, we have taken data at the voltage level, before any integration. By integrating pulses with the same relative phase with respect to the optical intensity we can determine the variation in radar back-scatter on time-scales of 0.02 s.

  5. The morphology of displays of pulsating auroras.

    NASA Technical Reports Server (NTRS)

    Cresswell, G. R.

    1972-01-01

    An auroral substorm generates displays of pulsating auroras in ways which show a dependence upon both local time and latitude relative to the auroral oval. For several hours after midnight pulsating auroras can be observed in the wake of poleward expansions or within equatorward spreading diffuse envelopes of meridional extent of several hundred kilometers. As the dawn meridian is approached the displays of pulsating auroras tend increasingly to be comprised of distinct eastward drifting patches easily recorded by all-sky cameras.

  6. N2 vibrational distribution in aurorae

    NASA Technical Reports Server (NTRS)

    Waite, J. H.; Nagy, A. F.; Torr, D. G.

    1979-01-01

    The N2 vibrational distribution is calculated for a specific IBC Class II aurora using as input data obtained from coordinated rocket and satellite observations and currently accepted excitation and quenching rates. The results of the calculations indicate no significant vibrational enhancements for this specific aurora nor for 'upper limit' estimates for more intense aurorae. It is concluded that if significantly larger concentrations of vibrationally excited N2 molecules exist in the aurora, as recent rocket EUV measurements suggest, current concepts of the sources and sinks of N2 vibrational excitation will require significant revision.

  7. Mitotic mechanics: the auroras come into view.

    PubMed

    Andrews, Paul D; Knatko, Elena; Moore, William J; Swedlow, Jason R

    2003-12-01

    Aurora kinases have recently taken centre stage in the regulation of key cell cycle processes. Aurora A is emerging as a critical regulator of centrosome and spindle function. Aurora B mediates chromosome segregation by ensuring proper biorientation of sister chromatids, possibly through the regulation of microtubule dynamics. This enzyme also functions in cytokinesis apparently by interacting with a critical GTPase and a kinesin-like protein. Recent work on both kinases has revealed functional links between Aurora kinase activity and the mechanics of cell division. PMID:14644191

  8. Nutrient Densities, Carbon:Nitrogen Ratios, and Midday Differential Canopy Temperature Impact Grain Yield of Stressed Oat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant architecture components (i.e., leaf area per plant, leaf area index, number of leaves and number of tillers per plant), midday differential canopy temperature, nutrient densities and C:N ratio were assessed in oat (Avena sativa L.) plants subjected to biotic stresses caused by aphid feeding or...

  9. Aurora at the pole and equator: overlapping functions of Aurora kinases in the mitotic spindle.

    PubMed

    Hochegger, Helfrid; Hégarat, Nadia; Pereira-Leal, Jose B

    2013-03-01

    The correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division. Aurora kinases play a central role in orchestrating bipolar spindle establishment, chromosome alignment and segregation. In most eukaryotes, ranging from amoebas to humans, Aurora activity appears to be required both at the spindle pole and the kinetochore, and these activities are often split between two different Aurora paralogues, termed Aurora A and B. Polar and equatorial functions of Aurora kinases have generally been considered separately, with Aurora A being mostly involved in centrosome dynamics, whereas Aurora B coordinates kinetochore attachment and cytokinesis. However, double inactivation of both Aurora A and B results in a dramatic synergy that abolishes chromosome segregation. This suggests that these two activities jointly coordinate mitotic progression. Accordingly, recent evidence suggests that Aurora A and B work together in both spindle assembly in metaphase and disassembly in anaphase. Here, we provide an outlook on these shared functions of the Auroras, discuss the evolution of this family of mitotic kinases and speculate why Aurora kinase activity may be required at both ends of the spindle microtubules. PMID:23516109

  10. Aurora at the pole and equator: overlapping functions of Aurora kinases in the mitotic spindle

    PubMed Central

    Hochegger, Helfrid; Hégarat, Nadia; Pereira-Leal, Jose B.

    2013-01-01

    The correct assembly and timely disassembly of the mitotic spindle is crucial for the propagation of the genome during cell division. Aurora kinases play a central role in orchestrating bipolar spindle establishment, chromosome alignment and segregation. In most eukaryotes, ranging from amoebas to humans, Aurora activity appears to be required both at the spindle pole and the kinetochore, and these activities are often split between two different Aurora paralogues, termed Aurora A and B. Polar and equatorial functions of Aurora kinases have generally been considered separately, with Aurora A being mostly involved in centrosome dynamics, whereas Aurora B coordinates kinetochore attachment and cytokinesis. However, double inactivation of both Aurora A and B results in a dramatic synergy that abolishes chromosome segregation. This suggests that these two activities jointly coordinate mitotic progression. Accordingly, recent evidence suggests that Aurora A and B work together in both spindle assembly in metaphase and disassembly in anaphase. Here, we provide an outlook on these shared functions of the Auroras, discuss the evolution of this family of mitotic kinases and speculate why Aurora kinase activity may be required at both ends of the spindle microtubules. PMID:23516109

  11. Aurora University: Cornerstone for Community Partnerships.

    ERIC Educational Resources Information Center

    Wasicsko, M. Mark; And Others

    1996-01-01

    Out of a 1995 meeting of local educational stakeholders, the Aurora (Illinois) Online Community Network was born. The purpose was to share resources among schools, colleges, and other educational organizations and learn about the Internet. Aurora University shared its technological expertise with the community, initiated a cooperative master's…

  12. Generation of proton aurora by magnetosonic waves

    PubMed Central

    Xiao, Fuliang; Zong, Qiugang; Wang, Yongfu; He, Zhaoguo; Su, Zhenpeng; Yang, Chang; Zhou, Qinghua

    2014-01-01

    Earth's proton aurora occurs over a broad MLT region and is produced by the precipitation of low-energy (2–10 keV) plasmasheet protons. Proton precipitation can alter chemical compositions of the atmosphere, linking solar activity with global climate variability. Previous studies proposed that electromagnetic ion cyclotron waves can resonate with protons, producing proton scattering precipitation. A long-outstanding question still remains whether there is another mechanism responsible for the proton aurora. Here, by performing satellite data analysis and diffusion equation calculations, we show that fast magnetosonic waves can produce trapped proton scattering that yields proton aurora. This provides a new insight into the mechanism of proton aurora. Furthermore, a ray-tracing study demonstrates that magnetosonic wave propagates over a broad MLT region, consistent with the global distribution of proton aurora. PMID:24898626

  13. Uranus's auroras observed from Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-05-01

    New observations from the Hubble Space Telescope provide the first ever images of Uranus's auroras. The new observations, described by Lamy et al., are also the first unambiguous detections of Uranus's auroras since they were first discovered using the Voyager 2 spacecraft, which few by the planet in 1986. Auroras arise from the solar wind's interaction with a planet's magnetosphere. Uranus's magnetosphere, which is not well studied, is unusual because the planet's magnetic axis is both offset and sharply tilted with respect to the planet's spin axis. The newly detected auroras, seen on the dayside of the planet in November 2011, are quite different from Earth's—Uranus's auroras were faint dots of light that lasted online a few minutes, unlike the dancing colored curtains organized along rings of emissions around Earth's magnetic poles, intensified on the nightside and lasting for hours. (Geophysical Research Letters, doi:10.1029/ 2012GL051312, 2012)

  14. Aurorae: The earliest datable observation of the aurora borealis

    NASA Astrophysics Data System (ADS)

    Stephenson, F. Richard; Willis, David M.; Hallinan, Thomas J.

    2004-12-01

    The Late Babylonian astronomical texts, discovered at the site of Babylon (32.5°N, 44.4°E) more than a century ago, contain what is probably the earliest reliable account of the aurora borealis. A clay tablet recording numerous celestial observations made by the official astronomers during the 37th year of King Nebuchadnezzar II (568/567 BC) describes an unusual ``red glow'' in the sky at night; the exact date of this observation corresponds to the night of 12/13 March in 567 BC. The most likely interpretation of the phenomenon is an auroral display. This event occurred several centuries before the first clearly identifiable observation of the aurora from elsewhere in the world, namely China in 193 BC. The Babylonian auroral observation is remarkable in the sense that it is one of a series of carefully recorded astronomical observations, for each of which the year, month and day are known precisely. This observation occurred at a time when the geomagnetic (dipole) latitude of Babylon was about 41°N compared with the present value of 27.5°N, suggesting a higher auroral incidence at Babylon in 567 BC than at present.

  15. Nature's Fireworks: The Inner Workings of the Auroras.

    ERIC Educational Resources Information Center

    Kikoyin, A. K.

    1992-01-01

    Describes the great variety of observations surrounding the auroras (both borealis and australis), and provides photographs from the space shuttle, Discovery. Discusses where and when the auroras can be observed, the process that the Earth's magnetic phenomena fulfill in how and why auroras appear, and the effects of solar wind upon auroras. (JJK)

  16. The emperor of Japan and the aurora

    NASA Astrophysics Data System (ADS)

    Akasofu, S. I.

    On October 3, 1985, I gave a special lecture on the aurora for the Emperor of Japan in his palace in Tokyo. It seems the Emperor, a marine biologist, has an unusual interest in the aurora. After my slide presentation, he asked how we confirm ancient sighting reports of the aurora in Japan. He was not satisfied with my response that anomalous events in the sky were well documented in an ancient publication entitled Japanese Meteorological Data and asked further how one could confirm such sightings as auroral events. He was visibly pleased to learn that the dates of these sightings coincided with those recorded elsewhere in the world.

  17. Jupiter's nightside airglow and aurora.

    PubMed

    Gladstone, G Randall; Stern, S Alan; Slater, David C; Versteeg, Maarten; Davis, Michael W; Retherford, Kurt D; Young, Leslie A; Steffl, Andrew J; Throop, Henry; Parker, Joel Wm; Weaver, Harold A; Cheng, Andrew F; Orton, Glenn S; Clarke, John T; Nichols, Jonathan D

    2007-10-12

    Observations of Jupiter's nightside airglow (nightglow) and aurora obtained during the flyby of the New Horizons spacecraft show an unexpected lack of ultraviolet nightglow emissions, in contrast to the case during the Voyager flybys in 1979. The flux and average energy of precipitating electrons generally decrease with increasing local time across the nightside, consistent with a possible source region along the dusk flank of Jupiter's magnetosphere. Visible emissions associated with the interaction of Jupiter and its satellite Io extend to a surprisingly high altitude, indicating localized low-energy electron precipitation. These results indicate that the interaction between Jupiter's upper atmosphere and near-space environment is variable and poorly understood; extensive observations of the day side are no guide to what goes on at night. PMID:17932286

  18. Determining the mechanism of cusp proton aurora

    PubMed Central

    Xiao, Fuliang; Zong, Qiugang; Su, Zhenpeng; Yang, Chang; He, Zhaoguo; Wang, Yongfu; Gao, Zhonglei

    2013-01-01

    Earth's cusp proton aurora occurs near the prenoon and is primarily produced by the precipitation of solar energetic (2–10 keV) protons. Cusp auroral precipitation provides a direct source of energy for the high-latitude dayside upper atmosphere, contributing to chemical composition change and global climate variability. Previous studies have indicated that magnetic reconnection allows solar energetic protons to cross the magnetopause and enter the cusp region, producing cusp auroral precipitation. However, energetic protons are easily trapped in the cusp region due to a minimum magnetic field existing there. Hence, the mechanism of cusp proton aurora has remained a significant challenge for tens of years. Based on the satellite data and calculations of diffusion equation, we demonstrate that EMIC waves can yield the trapped proton scattering that causes cusp proton aurora. This moves forward a step toward identifying the generation mechanism of cusp proton aurora. PMID:23575366

  19. Aurorae Observed at the Canary Islands

    NASA Astrophysics Data System (ADS)

    Vázquez, M.; Vaquero, J. M.

    2010-12-01

    Descriptions of eleven aurorae observed in the Canary Islands during the period 1770 - 2010 have been found in different documents. Most of them are coincident with periods of strong solar activity, with the geomagnetic latitude playing a minor role. Coronal mass ejections are the most probable solar source of these low-latitude events. The absence of low-latitude aurorae is verified in our sample during the Dalton Minimum and the first half of the twentieth century.

  20. Low Latitude Aurora: Index of Solar Activity

    NASA Astrophysics Data System (ADS)

    Bekli, M. R.; Aissani, D.; Chadou, I.

    2010-10-01

    Observations of aurora borealis at low latitudes are rare, and are clearly associated with high solar activity. In this paper, we analyze some details of the solar activity during the years 1769-1792. Moreover, we describe in detail three low latitude auroras. The first event was reported by ash-Shalati and observed in North Africa (1770 AD). The second and third events were reported by l'Abbé Mann and observed in Europe (1770 and 1777 AD).

  1. A descent of the aurora over Lapland

    NASA Astrophysics Data System (ADS)

    Whiter, D.; Partamies, N.

    2014-04-01

    A very large statistical study (~400000 measurements) into the peak emission height of the aurora has shown that the aurora over Laplanddescended significantly between 1996 and 2007. The study was performed using images from a network of ground-based all-sky cameras, which form part of the MIRACLE (Magnetometers-Ionospheric Radar-All-sky Cameras Large Experiment) network, and are located at various observation stations across northern Finland and Sweden.

  2. Discovery of an aurora on Mars.

    PubMed

    Bertaux, Jean-Loup; Leblanc, François; Witasse, Olivier; Quemerais, Eric; Lilensten, Jean; Stern, S A; Sandel, B; Korablev, Oleg

    2005-06-01

    In the high-latitude regions of Earth, aurorae are the often-spectacular visual manifestation of the interaction between electrically charged particles (electrons, protons or ions) with the neutral upper atmosphere, as they precipitate along magnetic field lines. More generally, auroral emissions in planetary atmospheres "are those that result from the impact of particles other than photoelectrons" (ref. 1). Auroral activity has been found on all four giant planets possessing a magnetic field (Jupiter, Saturn, Uranus and Neptune), as well as on Venus, which has no magnetic field. On the nightside of Venus, atomic O emissions at 130.4 nm and 135.6 nm appear in bright patches of varying sizes and intensities, which are believed to be produced by electrons with energy <300 eV (ref. 7). Here we report the discovery of an aurora in the martian atmosphere, using the ultraviolet spectrometer SPICAM on board Mars Express. It corresponds to a distinct type of aurora not seen before in the Solar System: it is unlike aurorae at Earth and the giant planets, which lie at the foot of the intrinsic magnetic field lines near the magnetic poles, and unlike venusian auroras, which are diffuse, sometimes spreading over the entire disk. Instead, the martian aurora is a highly concentrated and localized emission controlled by magnetic field anomalies in the martian crust. PMID:15944698

  3. Ubiquitin-Mediated Degradation of Aurora Kinases

    PubMed Central

    Lindon, Catherine; Grant, Rhys; Min, Mingwei

    2016-01-01

    The Aurora kinases are essential regulators of mitosis in eukaryotes. In somatic cell divisions of higher eukaryotes, the paralogs Aurora kinase A (AurA) and Aurora kinase B (AurB) play non-overlapping roles that depend on their distinct spatiotemporal activities. These mitotic roles of Aurora kinases depend on their interactions with different partners that direct them to different mitotic destinations and different substrates: AurB is a component of the chromosome passenger complex that orchestrates the tasks of chromosome segregation and cytokinesis, while AurA has many known binding partners and mitotic roles, including a well-characterized interaction with TPX2 that mediates its role in mitotic spindle assembly. Beyond the spatial control conferred by different binding partners, Aurora kinases are subject to temporal control of their activation and inactivation. Ubiquitin-mediated proteolysis is a critical route to irreversible inactivation of these kinases, which must occur for ordered transition from mitosis back to interphase. Both AurA and AurB undergo targeted proteolysis after anaphase onset as substrates of the anaphase-promoting complex/cyclosome (APC/C) ubiquitin ligase, even while they continue to regulate steps during mitotic exit. Temporal control of Aurora kinase destruction ensures that AurB remains active at the midbody during cytokinesis long after AurA activity has been largely eliminated from the cell. Differential destruction of Aurora kinases is achieved despite the fact that they are targeted at the same time and by the same ubiquitin ligase, making these substrates an interesting case study for investigating molecular determinants of ubiquitin-mediated proteolysis in higher eukaryotes. The prevalence of Aurora overexpression in cancers and their potential as therapeutic targets add importance to the task of understanding the molecular determinants of Aurora kinase stability. Here, we review what is known about ubiquitin-mediated targeting

  4. Making the Auroras glow: regulation of Aurora A and B kinase function by interacting proteins

    PubMed Central

    Carmena, Mar; Ruchaud, Sandrine; Earnshaw, William C

    2009-01-01

    The conserved Aurora family of protein kinases have emerged as crucial regulators of mitosis and cytokinesis. Despite their high degree of homology, Aurora A and B have very distinctive localisations and functions: Aurora A associates with the spindle poles to regulate entry into mitosis, centrosome maturation and spindle assembly; Aurora B is a member of the Chromosomal Passenger Complex (CPC) that transfers from the inner centromere in early mitosis to the spindle midzone, equatorial cortex and midbody in late mitosis and cytokinesis. Aurora B functions include regulation of chromosome–microtubule interactions, cohesion, spindle stability and cytokinesis. This review will focus on how interacting proteins make this functional diversity possible by targeting the kinases to different subcellular locations and regulating their activity. PMID:19836940

  5. Making the Auroras glow: regulation of Aurora A and B kinase function by interacting proteins.

    PubMed

    Carmena, Mar; Ruchaud, Sandrine; Earnshaw, William C

    2009-12-01

    The conserved Aurora family of protein kinases have emerged as crucial regulators of mitosis and cytokinesis. Despite their high degree of homology, Aurora A and B have very distinctive localisations and functions: Aurora A associates with the spindle poles to regulate entry into mitosis, centrosome maturation and spindle assembly; Aurora B is a member of the Chromosomal Passenger Complex (CPC) that transfers from the inner centromere in early mitosis to the spindle midzone, equatorial cortex and midbody in late mitosis and cytokinesis. Aurora B functions include regulation of chromosome-microtubule interactions, cohesion, spindle stability and cytokinesis. This review will focus on how interacting proteins make this functional diversity possible by targeting the kinases to different subcellular locations and regulating their activity. PMID:19836940

  6. Hubble Images Reveal Jupiter's Auroras

    NASA Technical Reports Server (NTRS)

    1996-01-01

    These images, taken by the Hubble Space Telescope, reveal changes in Jupiter's auroral emissions and how small auroral spots just outside the emission rings are linked to the planet's volcanic moon, Io. The images represent the most sensitive and sharply-detailed views ever taken of Jovian auroras.

    The top panel pinpoints the effects of emissions from Io, which is about the size of Earth's moon. The black-and-white image on the left, taken in visible light, shows how Io and Jupiter are linked by an invisible electrical current of charged particles called a 'flux tube.' The particles - ejected from Io (the bright spot on Jupiter's right) by volcanic eruptions - flow along Jupiter's magnetic field lines, which thread through Io, to the planet's north and south magnetic poles. This image also shows the belts of clouds surrounding Jupiter as well as the Great Red Spot.

    The black-and-white image on the right, taken in ultraviolet light about 15 minutes later, shows Jupiter's auroral emissions at the north and south poles. Just outside these emissions are the auroral spots. Called 'footprints,' the spots are created when the particles in Io's 'flux tube' reach Jupiter's upper atmosphere and interact with hydrogen gas, making it fluoresce. In this image, Io is not observable because it is faint in the ultraviolet.

    The two ultraviolet images at the bottom of the picture show how the auroral emissions change in brightness and structure as Jupiter rotates. These false-color images also reveal how the magnetic field is offset from Jupiter's spin axis by 10 to 15 degrees. In the right image, the north auroral emission is rising over the left limb; the south auroral oval is beginning to set. The image on the left, obtained on a different date, shows a full view of the north aurora, with a strong emission inside the main auroral oval.

    The images were taken by the telescope's Wide Field and Planetary Camera 2 between May 1994 and September 1995.

    This image and

  7. Ionospheric variation during pulsating aurora

    NASA Astrophysics Data System (ADS)

    Hosokawa, K.; Ogawa, Y.

    2015-07-01

    We have statistically analyzed data from the European Incoherent Scatter (EISCAT) UHF/VHF radars in Tromsø (69.60°N, 19.20°E), Norway, to reveal how the occurrence of pulsating auroras (PsAs) modifies the electron density profile in the ionosphere. By checking five winter seasons' (2007-2012) observations of all-sky aurora cameras of the National Institute of Polar Research in Tromsø, we have extracted 21 cases of PsA. During these PsA events, either the UHF or VHF radar of EISCAT was operative and the electron density profiles were obtained along the field-aligned or vertical direction near the zenith. From these electron density measurements, we calculated hmE (E region peak height) and NmE (E region peak density), which are proxies for the energy and flux of the precipitating PsA electrons, respectively. Then, we examined how these two parameters changed during the evolution of 21 PsA events in a statistical fashion. The results can be summarized as follows: (1) hmE is lower (the energy of precipitation electrons is higher) during the periods of PsA than that in the surrounding interval; (2) when NmE is higher (flux of PsA electrons is larger), hmE tends to be lower (precipitation is harder); (3) hmE is lower and NmE is larger in the later magnetic local time; and (4) when the AE index during the preceding substorm is larger, hmE is lower and NmE is larger. These tendencies are discussed in terms of the characteristics of particles and plasma waves in the source of PsA in the magnetosphere. In addition to the statistics of the EISCAT data, we carried out several detailed case studies, in which the altitude profiles of the electron density were derived by separating the On and Off phases of PsA. This allows us to estimate the true altitude profiles of the PsA ionization, which can be used for estimating the characteristic energy of the PsA electrons and better understanding the wave-particle interaction process in the magnetosphere.

  8. A descent of the aurora over Lapland

    NASA Astrophysics Data System (ADS)

    Whiter, Daniel; Partamies, Noora

    2014-05-01

    A very large statistical study (≃ 4 × 105 measurements) into the peak emission height of the aurora has shown that the aurora over Lapland descended significantly between 1996 and 2007. The study was performed using images from a network of ground-based all-sky cameras which form part of the MIRACLE (Magnetometers-Ionospheric Radar-All-sky Cameras Large Experiment) network, and are located at various observation stations across northern Finland and Sweden. The height of the aurora was first measured about a century ago. Since then, it has generally been assumed that the peak emission height of any particular auroral emission is constant for similar geomagnetic conditions. The present work was motivated by the need to improve estimates of the height of the aurora used to calculate other ionospheric and auroral properties, such as optical flow velocities and auroral arc widths. In recent years MIRACLE has produced approximately 105 images of the aurora per station per year. In order to analyse such a large number of images, a novel fast and automatic method was developed for finding the peak emission height of an auroral structure from a pair of all-sky camera images with overlapping fields of view. This method has been applied to all auroral images recorded by the MIRACLE intensified CCD cameras in operation between 1996 and 2007. Such a large data set allows the study of variations in the height of the aurora with time (yearly, monthly, hourly) and with solar and geomagnetic indices such as F10.7 and Kp. Results from the statistical study show that the peak emission height of green (557.7 nm, O1S - O1D transition) aurora over Lapland descended by about 10 km between 1996 and 2007. This descent occurred independently of the solar cycle, and is thought to be due to a cooling and contraction of the mesosphere and lower thermosphere.

  9. Statistical study of dayside pulsating aurora

    NASA Astrophysics Data System (ADS)

    Kanmae, T.; Kadokura, A.; Ogawa, Y.; Ebihara, Y.; Motoba, T.; Gerrard, A. J.; Weatherwax, A. T.

    2015-12-01

    Pulsating aurora normally occurs after a substorm breakup in the midnight sector, often observed to persist through the morning sector and beyond. Indeed, it has also been observed on the dayside; however, the characteristics of the dayside pulsating aurora are poorly known. A handful of observational studies have been reported, but the results are somewhat disputable because most of the studies had non-uniform sampling of the dark dayside region. Furthermore, the previous studies used photometer data, with which the spatial characteristics of the pulsating aurora cannot be examined. To determine both temporal and spatial characteristics of the pulsating aurora, we have studied three years of all-sky image data obtained at the South Pole station. Because of its unique geographical location, the station has 24 hours of darkness during the austral winter from April to August, providing an ideal platform for studying dayside aurora. In a preliminary survey of the data, we have identified the pulsating auroras in 198 days out of 365 days of observations. The magnetic local time (MLT) distribution of the occurrence peaks between 9:00 and 11:00, but shows no or little dependence on the geomagnetic activity. In many events, pulsating patches initially appear as east-west aligned arc segments and later in the afternoon sector develop into large, diffuse patches, which occasionally fill a large part of the field of view. Using the long-term data, we will statistically examine both temporal (occurrence rate, duration and pulsation period) and spatial (sizes and shapes) characteristics of the dayside pulsating aurora.

  10. Breakfast, midday meals and academic achievement in rural primary schools in Uganda: implications for education and school health policy

    PubMed Central

    Acham, Hedwig; Kikafunda, Joyce K.; Malde, Marian K.; Oldewage-Theron, Wilna H.; Egal, AbdulKadir A.

    2012-01-01

    Background Underachievement in schools is a global problem and is especially prevalent in developing countries. Indicators of educational performance show that Uganda has done remarkably well on education access-related targets since the introduction of universal primary education in 1997. However, educational outcomes remain disappointing. The absence of school feeding schemes, one of the leading causes of scholastic underachievement, has not been given attention by the Ugandan authorities. Instead, as a national policy, parents are expected to provide meals even though many, especially in the rural areas, cannot afford to provide even the minimal daily bowl of maize porridge. Objective To assess and demonstrate the effect of breakfast and midday meal consumption on academic achievement of schoolchildren. Design, Materials and Methods We assessed household characteristics, feeding patterns and academic achievement of 645 schoolchildren (aged 9–15 years) in Kumi district, eastern Uganda, in 2006–2007, using a modified cluster sampling design which involved only grade 1 schools (34 in total) and pupils of grade four. Household questionnaires and school records were used to collect information on socio-demographic factors, feeding patterns and school attendance. Academic achievement was assessed using unstandardized techniques, specifically designed for this study. Results Underachievement (the proportion below a score of 120.0 points) was high (68.4%); in addition, significantly higher achievement and better feeding patterns were observed among children from the less poor households (p<0.05). Achievement was significantly associated with consumption of breakfast and a midday meal, particularly for boys (p<0.05), and a greater likelihood of scoring well was observed for better nourished children (all OR values>1.0). Conclusion We observed that underachievement was relatively high; inadequate patterns of meal consumption, particularly for the most poor

  11. Atmospheric physics: Chorus keeps the diffuse aurora humming

    NASA Astrophysics Data System (ADS)

    Newell, Patrick T.

    2010-10-01

    The origin of the diffuse aurora, whose beauty and intensity pale beside those of the famous aurora borealis, has remained controversial. A convincing explanation for this auroral display is now at hand. See Letter p.943

  12. Evaluation of the Aurora Application Shade Measurement Accuracy

    SciTech Connect

    2015-12-01

    Aurora is an integrated, Web-based application that helps solar installers perform sales, engineering design, and financial analysis. One of Aurora's key features is its high-resolution remote shading analysis.

  13. Satellite Footprints Seen in Jupiter Aurora

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This is a spectacular NASA Hubble Space Telescope close-up view of an electric-blue aurora that is eerily glowing one half billion miles away on the giant planet Jupiter. Auroras are curtains of light resulting from high-energy electrons racing along the planet's magnetic field into the upper atmosphere. The electrons excite atmospheric gases, causing them to glow. The image shows the main oval of the aurora, which is centered on the magnetic north pole, plus more diffuse emissions inside the polar cap.

    Though the aurora resembles the same phenomenon that crowns Earth's polar regions, the Hubble image shows unique emissions from the magnetic 'footprints' of three of Jupiter's largest moons. (These points are reached by following Jupiter's magnetic field from each satellite down to the planet).

    Auroral footprints can be seen in this image from Io (along the lefthand limb), Ganymede (near the center), and Europa (just below and to the right of Ganymede's auroral footprint). These emissions, produced by electric currents generated by the satellites, flow along Jupiter's magnetic field, bouncing in and out of the upper atmosphere. They are unlike anything seen on Earth.

    This ultraviolet image of Jupiter was taken with the Hubble Space Telescope Imaging Spectrograph (STIS) on November 26, 1998. In this ultraviolet view, the aurora stands out clearly, but Jupiter's cloud structure is masked by haze.

    December 14, 2000 inaugurates an intensive two weeks of joint observation of Jupiter's aurora by Hubble and the Cassini spacecraft. Cassini will make its closest approach to Jupiter enroute to a July 2004 rendezvous with Saturn. A second campaign in January 2001 will consist of Hubble images of Jupiter's day-side aurora and Cassini images of Jupiter's night-side aurora, obtained just after Cassini has flown past Jupiter. The team will develop computer models that predict how the aurora operates, and this will yield new insights into the effects of the solar wind

  14. Persistent, widespread pulsating aurora: A case study

    NASA Astrophysics Data System (ADS)

    Jones, S. L.; Lessard, M. R.; Rychert, K.; Spanswick, E.; Donovan, E.; Jaynes, A. N.

    2013-06-01

    Observations of a pulsating aurora event occurring on 11 February 2008, using the Time History of Events and Macroscale Interactions during Substorms (THEMIS) All-Sky Imager (ASI) array, indicate a spatially and temporally continuous event with a duration of greater than 15 h and covering a region with a maximum size of greater than 10 h magnetic local time. The optical pulsations are at times locally interrupted or drowned out by auroral substorm activity but are observed in the same location once the discrete aurora recedes. The pulsations following the auroral breakup appear to be brighter and have a larger patch size than before breakup. This suggests that, while the onset of pulsating aurora is not necessarily dependent upon a substorm precursor, the pulsations are affected and possibly enhanced by the substorm process. The long duration of this pulsating aurora event, lasting approximately 8 h without interruption as imaged from Gillam station, is significantly longer than the typical 2-3 h substorm recovery phase, suggesting that pulsating aurora is not strictly a recovery phase phenomenon. This paper is accompanied by a movie of the THEMIS ASI array data, from 0000 to 1715 UT, plotted in mosaic and superimposed onto a map of North America.

  15. Validating Aurora B as an anti-cancer drug target.

    PubMed

    Girdler, Fiona; Gascoigne, Karen E; Eyers, Patrick A; Hartmuth, Sonya; Crafter, Claire; Foote, Kevin M; Keen, Nicholas J; Taylor, Stephen S

    2006-09-01

    The Aurora kinases, a family of mitotic regulators, have received much attention as potential targets for novel anti-cancer therapeutics. Several Aurora kinase inhibitors have been described including ZM447439, which prevents chromosome alignment, spindle checkpoint function and cytokinesis. Subsequently, ZM447439-treated cells exit mitosis without dividing and lose viability. Because ZM447439 inhibits both Aurora A and B, we set out to determine which phenotypes are due to inhibition of which kinase. Using molecular genetic approaches, we show that inhibition of Aurora B kinase activity phenocopies ZM447439. Furthermore, a novel ZM compound, which is 100 times more selective for Aurora B over Aurora A in vitro, induces identical phenotypes. Importantly, inhibition of Aurora B kinase activity induces a penetrant anti-proliferative phenotype, indicating that Aurora B is an attractive anti-cancer drug target. Using molecular genetic and chemical-genetic approaches, we also probe the role of Aurora A kinase activity. We show that simultaneous repression of Aurora A plus induction of a catalytic mutant induces a monopolar phenotype. Consistently, another novel ZM-related inhibitor, which is 20 times as potent against Aurora A compared with ZM447439, induces a monopolar phenotype. Expression of a drug-resistant Aurora A mutant reverts this phenotype, demonstrating that Aurora A kinase activity is required for spindle bipolarity in human cells. Because small molecule-mediated inhibition of Aurora A and Aurora B yields distinct phenotypes, our observations indicate that the Auroras may present two avenues for anti-cancer drug discovery. PMID:16912073

  16. Aurora: Observing and Recording Nature's Spectacular Light Show

    NASA Astrophysics Data System (ADS)

    Akasofu, Syun-Ichi

    2008-06-01

    There have been many popular books on the aurora that include beautiful photographs with lyrical descriptions. Aurora by Neil Bone is different from other popular books in that it describes not only the aurora but also various sky phenomena, including noctilucent clouds, halos, and meteors.

  17. Discovery of diffuse aurora on Mars.

    PubMed

    Schneider, N M; Deighan, J I; Jain, S K; Stiepen, A; Stewart, A I F; Larson, D; Mitchell, D L; Mazelle, C; Lee, C O; Lillis, R J; Evans, J S; Brain, D; Stevens, M H; McClintock, W E; Chaffin, M S; Crismani, M; Holsclaw, G M; Lefevre, F; Lo, D Y; Clarke, J T; Montmessin, F; Jakosky, B M

    2015-11-01

    Planetary auroras reveal the complex interplay between an atmosphere and the surrounding plasma environment. We report the discovery of low-altitude, diffuse auroras spanning much of Mars' northern hemisphere, coincident with a solar energetic particle outburst. The Imaging Ultraviolet Spectrograph, a remote sensing instrument on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, detected auroral emission in virtually all nightside observations for ~5 days, spanning nearly all geographic longitudes. Emission extended down to ~60 kilometer (km) altitude (1 microbar), deeper than confirmed at any other planet. Solar energetic particles were observed up to 200 kilo--electron volts; these particles are capable of penetrating down to the 60 km altitude. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit auroras more globally than Earth. PMID:26542577

  18. The first accurate description of an aurora

    NASA Astrophysics Data System (ADS)

    Schröder, Wilfried

    2006-12-01

    As technology has advanced, the scientific study of auroral phenomena has increased by leaps and bounds. A look back at the earliest descriptions of aurorae offers an interesting look into how medieval scholars viewed the subjects that we study.Although there are earlier fragmentary references in the literature, the first accurate description of the aurora borealis appears to be that published by the German Catholic scholar Konrad von Megenberg (1309-1374) in his book Das Buch der Natur (The Book of Nature). The book was written between 1349 and 1350.

  19. A new theory of the aurora

    NASA Astrophysics Data System (ADS)

    Bryant, D. A.

    1993-03-01

    Experiments made using sounding rockets have played a key role in studying the physics of the aurora. The development of a theory to explain the acceleration of the electrons responsible for one of the most striking and highly characteristic forms of aurora - the auroral arc - in terms of acceleration through a potential difference is outlined and fundamental difficulties with this theory are discussed. A new theory in which acceleration is caused by electrostatic waves is examined and found to provide a promising explanation of this key problem in space plasma physics. The techniques by which the measurements are obtained in such experiments are summarized.

  20. Possible Role of Aurora-C in Meiosis

    PubMed Central

    Yang, Kuo-Tai; Tang, Chieh-Ju C.; Tang, Tang K.

    2015-01-01

    The meiotic generation of haploid gametes with equal contents of genetic material is important for sexual reproduction in mammals. Errors in the transmission of chromosomes during meiosis may lead to aneuploidy, which is the leading cause of miscarriage and congenital birth defects in humans. The Aurora kinases, which include Aurora-A, Aurora-B, and Aurora-C, are highly conserved serine–threonine kinases that play essential roles in centrosome function, chromosome segregation, and cytokinesis during mitosis and meiosis. While Aurora-A and Aurora-B have been extensively studied in mitosis, the role of Aurora-C in meiosis is only now starting to be revealed. For example, the perturbation of Aurora-C kinase activity by microinjection of Aurora-C-kinase-dead mutant mRNAs into mouse oocytes induced multiple defects, including chromosome misalignment, abnormal kinetochore–microtubule attachment, premature chromosome segregation, and failure of cytokinesis during meiotic division. However, the analysis of such defects is complicated by the possibility that Aurora-B may be present in mammalian germ cells. Interestingly, a homozygous mutation of Aurora-C in humans leads to the production of large-headed polyploid spermatozoa and causes male infertility, but homozygous females are fertile. Mouse studies regarding the roles of Aurora-B and Aurora-C in female meiotic divisions have yielded inconsistent results, and it has proven difficult to explain why homozygous human females have no significant clinical phenotype. In this review, we will discuss the controversial status of Aurora-B in oocytes and the possible role of Aurora-C during meiotic division. PMID:26322271

  1. Diel trends in stomatal response to ozone and water deficit: a unique relationship of midday values to growth and allometry in Pima cotton?

    PubMed

    Grantz, D A; Paudel, R; Vu, H-B; Shrestha, A; Grulke, N

    2016-01-01

    Plant responses to ozone (O3 ) and water deficit (WD) are commonly observed, although less is known about their interaction. Stomatal conductance (gs ) is both an impact of these stressors and a protective response to them. Stomatal closure reduces inward flux of O3 and outward flux of water. Stomatal measurements are generally obtained at midday when gas exchange is maximal, but these may not be adequate surrogates for stomatal responses observed at other times of day, nor for non-stomatal responses. Here, we find in Pima cotton that stomatal responses to O3 observed at midday do not reflect responses at other times. Stomata were more responsive to O3 and WD near midday, despite being at quasi-steady state, than during periods of active opening or closing in morning or evening. Stomatal responsivity to O3 was not coincident with maximum gas exchange or with periods of active regulation, but coincident with plant sensitivity to O3 previously determined in this cultivar. Responses of pigmentation and shoot productivity were more closely related to stomatal responses at midday than to responses at other times of day under well-watered (WW) conditions, reflecting higher stomatal responsivity, sensitivity to O3 , and magnitude of midday gs . Under WD conditions, shoot responses were more closely related to early morning gs. Root responses were more closely related to early morning gs under both WW and WD. Responses of stomata to O3 at midday were not good surrogates for stomatal responses early or late in the day, and may not adequately predicting O3 flux under WD or when maximum ambient concentrations do not occur near midday. PMID:26031549

  2. Hubble Provides Clear Images of Saturn's Aurora

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This is the first image of Saturn's ultraviolet aurora taken by the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope in October 1997, when Saturn was a distance of 810 million miles (1.3 billion kilometers) from Earth. The new instrument, used as a camera, provides more than ten times the sensitivity of previous Hubble instruments in the ultraviolet. STIS images reveal exquisite detail never before seen in the spectacular auroral curtains of light that encircle Saturn's north and south poles and rise more than a thousand miles above the cloud tops.

    Saturn's auroral displays are caused by an energetic wind from the Sun that sweeps over the planet, much like the Earths aurora that is occasionally seen in the nighttime sky and similar to the phenomenon that causes fluorescent lamps to glow. But unlike the Earth, Saturn's aurora is only seen in ultraviolet light that is invisible from the Earths surface, hence the aurora can only be observed from space. New Hubble images reveal ripples and overall patterns that evolve slowly, appearing generally fixed in our view and independent of planet rotation. At the same time, the curtains show local brightening that often follow the rotation of the planet and exhibit rapid variations on time scales of minutes. These variations and regularities indicate that the aurora is primarily shaped and powered by a continual tug-of-war between Saturn's magnetic field and the flow of charged particles from the Sun.

    Study of the aurora on Saturn had its beginnings just seventeen years ago. The Pioneer 11 spacecraft observed a far-ultraviolet brightening on Saturn's poles in 1979. The Saturn flybys of the Voyager 1 and 2 spacecraft in the early 1980s provided a basic description of the aurora and mapped for the first time planets enormous magnetic field that guides energetic electrons into the atmosphere near the north and south poles.

    The first images of Saturn's aurora were provided in 1994-5 by the

  3. Clinical experience with aurora kinase inhibitors: a review.

    PubMed

    Boss, David S; Beijnen, Jos H; Schellens, Jan H M

    2009-08-01

    The aurora kinase family of serine/threonine kinases comprises three members, designated auroras A, B, and C. Auroras A and B are essential components of the mitotic pathway, ensuring proper chromosome assembly, formation of the mitotic spindle, and cytokinesis. The role of aurora C is less clear. Overexpression of aurora A and B has been observed in several tumor types, and has been linked with a poor prognosis of cancer patients. Several small molecules targeting aurora kinases A and B or both have been evaluated preclinically and in early phase I trials. In this review we aim to summarize the most recent advances in the development of aurora kinase inhibitors, with a focus on the clinical data. PMID:19684075

  4. Aurora kinase targeted therapeutics in oncology: past, present and future.

    PubMed

    Mahadevan, Daruka; Beeck, Sunni

    2007-07-01

    Aurora A, B and C are a family of serine-threonine protein kinases that regulate distinct functions of the mitotic phase of the cell cycle. All three Auroras are overexpressed in human cancers with an associated polyploid phenotype. Crystal structures of Aurora A or B with bound small molecular inhibitors have provided detailed insight of the active site, mode of binding and hotspots for developing resistance through point mutations. Structural studies have aided fragment-based rational drug discovery of Aurora inhibitors, including compounds specific for Aurora A or B. Aurora inhibitors have excellent antitumor activity in rodent models of cancer. At present, Aurora inhibitors are being evaluated in Phase I trials. The future holds promise for rational combinations in both solid and hematological malignancies. PMID:23484820

  5. Proyecto Aurora: Building a Community of Women.

    ERIC Educational Resources Information Center

    Noya, Gladys R. Capella

    1997-01-01

    Describes the development of Proyecto Aurora, a program to develop and implement educational, support, and research programs to benefit low-income women in Puerto Rico. Portraits of some clients illustrate the rewards and challenges of working with this community and furthering their educational experiences and opportunities. (SLD)

  6. Nighttime subvisual high-latitude auroras

    NASA Astrophysics Data System (ADS)

    Vorobjev, V. G.; Kornilov, I. A.; Kornilova, T. A.; Yagodkina, O. I.; Sandholt, P. E.; Lybekk, B.

    2008-10-01

    Special methods for processing TV images have been used to study the characteristics of nighttime auroras based on the observations at high-latitude observatories on Spitsbergen. Weak subvisual auroras (SVAs), originating 3°-4° north of brighter auroras in the auroral oval, have been detected in the interval 1900-0400 MLT. The average lifetime of SVAs is approximately 7 min, and the average velocity of the equatorward shift is ˜0.6 km/s. SVAs were observed during relatively quiet periods, when the IMF B z component is mainly positive. However, SVAs are not polar-cap auroras since they are oriented from east to west rather than toward the Sun. The optical observations indicate that the SVA intensity is 0.2-0.5 and 0.1-0.3 kR in the 630 and 557.7 nm emissions, respectively. The average ratio of the emission intensities ( I 5577/ I 6300) is about 0.5. According to the direct satellite observations, the SVA electron spectrum has a maximum at 0.4-1.0 keV. In this case the energy flux of precipitating electrons is approximately an order of magnitude as low as such a flux in brighter auroral arcs in the auroral oval.

  7. Aurora A's Functions During Mitotic Exit: The Guess Who Game.

    PubMed

    Reboutier, David; Benaud, Christelle; Prigent, Claude

    2015-01-01

    Until recently, the knowledge of Aurora A kinase functions during mitosis was limited to pre-metaphase events, particularly centrosome maturation, G2/M transition, and mitotic spindle assembly. However, an involvement of Aurora A in post-metaphase events was also suspected, but not clearly demonstrated due to the technical difficulty to perform the appropriate experiments. Recent developments of both an analog-specific version of Aurora A and small molecule inhibitors have led to the first demonstration that Aurora A is required for the early steps of cytokinesis. As in pre-metaphase, Aurora A plays diverse functions during anaphase, essentially participating in astral microtubules dynamics and central spindle assembly and functioning. The present review describes the experimental systems used to decipher new functions of Aurora A during late mitosis and situate these functions into the context of cytokinesis mechanisms. PMID:26734572

  8. Jung's quest for the Aurora consurgens.

    PubMed

    Haaning, Aksel

    2014-02-01

    The paper focuses on the year 1929 when Jung published 'A European commentary' to Richard Wilhelm's German translation of the Taoist text The Secret of the Golden Flower. This shows that Jung had already started on the track of European alchemy by following up Conrad Waldkirch's preface in Artis Auriferae (1593); and it raises the question of whether this could be the possible missing link to Jung's subsequent research in Alchemy and Hermetic Philosophy in the years to come. It is argued that here was the beginning of Jung's quest for the Aurora consurgens, the publication of which concludes the Mysterium Conuinctionis more than twenty years later. It is further maintained that this choice of the Aurora is a profound expression of Jung's ambition to revitalize the past from within the individual, and helps explain Jung's deep concern with the welfare and future of modern society. PMID:24467350

  9. Discovery of a Potent And Selective Aurora Kinase Inhibitor

    SciTech Connect

    Oslob, J.D.; Romanowski, M.J.; Allen, D.A.; Baskaran, S.; Bui, M.; Elling, R.A.; Flanagan, W.M.; Fung, A.D.; Hanan, E.J.; Harris, S.; Heumann, S.A.; Hoch, U.; Jacobs, J.W.; Lam, J.; Lawrence, C.E.; McDowell, R.S.; Nannini, M.A.; Shen, W.; Silverman, J.A.; Sopko, M.M.; Tangonan, B.T.

    2009-05-21

    This communication describes the discovery of a novel series of Aurora kinase inhibitors. Key SAR and critical binding elements are discussed. Some of the more advanced analogues potently inhibit cellular proliferation and induce phenotypes consistent with Aurora kinase inhibition. In particular, compound 21 (SNS-314) is a potent and selective Aurora kinase inhibitor that exhibits significant activity in pre-clinical in vivo tumor models.

  10. Auroral kilometric radiation/aurora correlation

    NASA Technical Reports Server (NTRS)

    Benson, R. F.; Akasofu, S.-I.

    1984-01-01

    Auroral kilometric radiation (AKR) observations from the ISIS 1 topside sounder receiver were compared with visual auroral observations from the network of Alaskan all-sky camera stations. The goal was to relate AKR source region encounters to specific auroral forms on the same magnetic field line. Thirty-eight simultaneous data sets were identified and analyzed. In general, intense AKR was associated with bright auroral arcs and conditions of weak or no AKR corresponded to times when either no aurora or only a faint arc or weak diffuse aurora were observed. Five cases, when both intense AKR and bright visual aurora were present, were analyzed in detail. Complete electron density N sub e contours, from the satellite altitude down to the F region ionization peak, were obtained along N-S traversals of the AKR source region. In addition, the ISIS 1 orbital tracks were projected down the magnetic field lines to the auroral altitude and compared to auroral features on a map derived from the all sky camera images. Density cavities (regions where N sub e 100/cu cm) were encountered on each of these passes. Previously announced in STAR as N83-27516

  11. Complex structure within Saturn's infrared aurora

    USGS Publications Warehouse

    Stallard, T.; Miller, S.; Lystrup, M.; Achilleos, N.; Bunce, E.J.; Arridge, C.S.; Dougherty, M.K.; Cowley, S.W.H.; Badman, S.V.; Talboys, D.L.; Brown, R.H.; Baines, K.H.; Buratti, B.J.; Clark, R.N.; Sotin, C.; Nicholson, P.D.; Drossart, P.

    2008-01-01

    The majority of planetary aurorae are produced by electrical currents flowing between the ionosphere and the magnetosphere which accelerate energetic charged particles that hit the upper atmosphere. At Saturn, these processes collisionally excite hydrogen, causing ultraviolet emission, and ionize the hydrogen, leading to H3+ infrared emission. Although the morphology of these aurorae is affected by changes in the solar wind, the source of the currents which produce them is a matter of debate. Recent models predict only weak emission away from the main auroral oval. Here we report images that show emission both poleward and equatorward of the main oval (separated by a region of low emission). The extensive polar emission is highly variable with time, and disappears when the main oval has a spiral morphology; this suggests that although the polar emission may be associated with minor increases in the dynamic pressure from the solar wind, it is not directly linked to strong magnetospheric compressions. This aurora appears to be unique to Saturn and cannot be explained using our current understanding of Saturn's magnetosphere. The equatorward arc of emission exists only on the nightside of the planet, and arises from internal magnetospheric processes that are currently unknown. ??2008 Macmillan Publishers Limited. All rights reserved.

  12. Hubble Provides Complete View of Jupiter's Auroras

    NASA Technical Reports Server (NTRS)

    1998-01-01

    NASA's Hubble Space Telescope has captured a complete view of Jupiter's northern and southern auroras.

    Images taken in ultraviolet light by the Space Telescope Imaging Spectrograph (STIS) show both auroras, the oval-shaped objects in the inset photos. While the Hubble telescope has obtained images of Jupiter's northern and southern lights since 1990, the new STIS instrument is 10 times more sensitive than earlier cameras. This allows for short exposures, reducing the blurring of the image caused by Jupiter's rotation and providing two to five times higher resolution than earlier cameras. The resolution in these images is sufficient to show the 'curtain' of auroral light extending several hundred miles above Jupiter's limb (edge). Images of Earth's auroral curtains, taken from the space shuttle, have a similar appearance. Jupiter's auroral images are superimposed on a Wide Field and Planetary Camera 2 image of the entire planet. The auroras are brilliant curtains of light in Jupiter's upper atmosphere. Jovian auroral storms, like Earth's, develop when electrically charged particles trapped in the magnetic field surrounding the planet spiral inward at high energies toward the north and south magnetic poles. When these particles hit the upper atmosphere, they excite atoms and molecules there, causing them to glow (the same process acting in street lights).

    The electrons that strike Earth's atmosphere come from the sun, and the auroral lights remain concentrated above the night sky in response to the 'solar wind.'

  13. Complex structure within Saturn's infrared aurora.

    PubMed

    Stallard, Tom; Miller, Steve; Lystrup, Makenzie; Achilleos, Nicholas; Bunce, Emma J; Arridge, Christopher S; Dougherty, Michele K; Cowley, Stan W H; Badman, Sarah V; Talboys, Dean L; Brown, Robert H; Baines, Kevin H; Buratti, Bonnie J; Clark, Roger N; Sotin, Christophe; Nicholson, Phil D; Drossart, Pierre

    2008-11-13

    The majority of planetary aurorae are produced by electrical currents flowing between the ionosphere and the magnetosphere which accelerate energetic charged particles that hit the upper atmosphere. At Saturn, these processes collisionally excite hydrogen, causing ultraviolet emission, and ionize the hydrogen, leading to H(3)(+) infrared emission. Although the morphology of these aurorae is affected by changes in the solar wind, the source of the currents which produce them is a matter of debate. Recent models predict only weak emission away from the main auroral oval. Here we report images that show emission both poleward and equatorward of the main oval (separated by a region of low emission). The extensive polar emission is highly variable with time, and disappears when the main oval has a spiral morphology; this suggests that although the polar emission may be associated with minor increases in the dynamic pressure from the solar wind, it is not directly linked to strong magnetospheric compressions. This aurora appears to be unique to Saturn and cannot be explained using our current understanding of Saturn's magnetosphere. The equatorward arc of emission exists only on the nightside of the planet, and arises from internal magnetospheric processes that are currently unknown. PMID:19005549

  14. Auroral kilometric radiation/aurora correlation

    NASA Technical Reports Server (NTRS)

    Benson, R. F.; Akasofu, S. I.

    1983-01-01

    Auroral kilometric radiation (AKR) observations from the ISIS 1 topside sounder receiver were compared with visual auroral observations from the network of Alaskan all-sky camera stations. The goal was to relate AKR source region encounters to specific auroral forms on the same magnetic field line. Thirty-eight simultaneous data sets were identified and analyzed. In general, intense AKR was associated with bright auroral arcs and conditions of weak or no AKR corresponded to times when either no aurora or only a faint arc or weak diffuse aurora were observed. Five cases, when both intense AKR and bright visual aurora were present, were analyzed in detail. Complete electron density N sub e contours, from the satellite altitude down to the F region ionization peak, were obtained along N-S traversals of the AKR source region. In addition, the ISIS 1 orbital tracks were projected down the magnetic field lines to the auroral altitude and compared to auroral features on a map derived from the all sky camera images. Density cavities (regions where N sub e 100/cu cm) were encountered on each of these passes.

  15. Polar Embedding for Aurora Image Retrieval.

    PubMed

    Yang, Xi; Gao, Xinbo; Tian, Qi

    2015-11-01

    Exploring the multimedia techniques to assist scientists for their research is an interesting and meaningful topic. In this paper, we focus on the large-scale aurora image retrieval by leveraging the bag-of-visual words (BoVW) framework. To refine the unsuitable representation and improve the retrieval performance, the BoVW model is modified by embedding the polar information. The superiority of the proposed polar embedding method lies in two aspects. On the one hand, the polar meshing scheme is conducted to determine the interest points, which is more suitable for images captured by circular fisheye lens. Especially for the aurora image, the extracted polar scale-invariant feature transform (polar-SIFT) feature can also reflect the geomagnetic longitude and latitude, and thus facilitates the further data analysis. On the other hand, a binary polar deep local binary pattern (polar-DLBP) descriptor is proposed to enhance the discriminative power of visual words. Together with the 64-bit polar-SIFT code obtained via Hamming embedding, the multifeature index is performed to reduce the impact of false positive matches. Extensive experiments are conducted on the large-scale aurora image data set. The experimental result indicates that the proposed method improves the retrieval accuracy significantly with acceptable efficiency and memory cost. In addition, the effectiveness of the polar-SIFT scheme and polar-DLBP integration are separately demonstrated. PMID:26068312

  16. Tetraploidization increases sensitivity to Aurora B kinase inhibition.

    PubMed

    Marxer, Miriam; Foucar, Charles E; Man, Wing Yu; Chen, Yu; Ma, Hoi Tang; Poon, Randy Y C

    2012-07-01

    Aurora kinases are overexpressed in many cancers and are targets for anticancer drugs. The yeast homolog of Aurora B kinase, IPL1, was found to be a ploidy-specific lethality gene. Given that polyploidization is a common feature of many cancers, we hypothesized polyploidization also sensitizes mammalian cells to inhibition of Aurora kinases. Using two models of apparent diploid vs. tetraploid cell lines (one based on the hepatocellular carcinoma cell line Hep3B and another on untransformed mouse fibroblasts), we found that tetraploid cells were more sensitive to Aurora B inhibition than their diploid counterparts. Apoptosis could be induced in tetraploid cells by two different Aurora B inhibitors. Furthermore, tetraploid cells were sensitive to Aurora B inhibition but were not affected by Aurora A inhibition. Interestingly, the underlying mechanism was due to mitotic slippage and the subsequent excessive genome reduplication. In support of this, abolition of cytokinesis with dihydrocytochalasin B resulted in similar effects on tetraploid cells as Aurora B inhibition. These results indicate that inhibition of Aurora B or cytokinesis can promote apoptosis effectively in polyploid cancer cells. PMID:22722494

  17. Spatial and temporal conjugacy of meso-scale discrete aurora

    NASA Astrophysics Data System (ADS)

    Sato, Natsuo; Kadokura, Akira

    2009-06-01

    We report on spatial and temporal conjugacy of meso-scale (˜10-200 km) discrete aurora using highly similar auroras that were simultaneously acquired with all-sky TV cameras situated at two geomagnetically conjugate points, at Tjornes in Iceland and at Syowa Station in Antarctica. During this event, discrete auroras, including both east-west and north-south directed auroral forms, showed excellent similarity in terms of shapes, movements and luminosity variations at both observatories. Similar and dissimilar auroras appeared simultaneously in adjoining areas of the sky in both hemispheres.

  18. In Vitro Characterization of Derrone as an Aurora Kinase Inhibitor.

    PubMed

    Hoang, Nhung Thi My; Phuong, Thuong Thien; Nguyen, Trang Thi Nhu; Tran, Yen Thi Hai; Nguyen, Anh Thi Ngoc; Nguyen, Thanh Lai; Bui, Khanh Thi Van

    2016-06-01

    Among mitotic kinases, Aurora kinases are the most widely studied, since their expression is restricted to mitosis. They play a key role in chromosome segregation and cell polyploidy. Aurora kinases are important therapeutic targets, and several research groups have directed their efforts toward the identification of kinase inhibitors. The aim of this study is to screen and characterize Aurora kinase inhibitors from natural substances extracted from plants that are used in the Vietnamese pharmacopoeia. We have characterized in vitro Derrone, extracted from Erythrina orientalis L. MURR, as a novel Aurora kinase inhibitor. This compound exhibited an ability to inhibit the phosphorylation of histone H3 at ser10 both in kinase assay and at the cellular level. The compound was more effective against Aurora kinase B, with a lower IC50 value as compared to Aurora A. Moreover, it impaired the mitotic spindle checkpoint and led to endoreduplication in cancer cells, a phenomenon caused by an Aurora B inhibitor. Interestingly, using the xCelligence system and real-time cell analysis (RTCA) software, we set up a comparison of cell proliferation profiles between cancer cells treated with Derrone and VX680-a well-known Aurora kinase inhibitor-and we found that these profiles exhibited considerable similarity in cell morphology, growth, and death. Additionally, Derrone significantly inhibited the formation and growth of MCF7 tumor spheroids. PMID:26983907

  19. Combined effects of wind and solar irradiance on the spatial variation of midday air temperature over a mountainous terrain

    NASA Astrophysics Data System (ADS)

    Kim, Soo-Ock; Kim, Jin-Hee; Kim, Dae-Jun; Shim, Kyo Moon; Yun, Jin I.

    2015-08-01

    When the midday temperature distribution in a mountainous region was estimated using data from a nearby weather station, the correction of elevation difference based on temperature lapse caused a large error. An empirical approach reflecting the effects of solar irradiance and advection was suggested in order to increase the reliability of the results. The normalized slope irradiance, which was determined by normalizing the solar irradiance difference between a horizontal surface and a sloping surface from 1100 to 1500 LST on a clear day, and the deviation relationship between the horizontal surface and the sloping surface at the 1500 LST temperature on each day were presented as simple empirical formulas. In order to simulate the phenomenon that causes immigrant air parcels to push out or mix with the existing air parcels in order to decrease the solar radiation effects, an advection correction factor was added to exponentially reduce the solar radiation effect with an increase in wind speed. In order to validate this technique, we estimated the 1500 LST air temperatures on 177 clear days in 2012 and 2013 at 10 sites with different slope aspects in a mountainous catchment and compared these values to the actual measured data. The results showed that this technique greatly improved the error bias and the overestimation of the solar radiation effect in comparison with the existing methods. By applying this technique to the Korea Meteorological Administration's 5-km grid data, it was possible to determine the temperature distribution at a 30-m resolution over a mountainous rural area south of Jiri Mountain National Park, Korea.

  20. Analysis of Aurora's Performance Simulation Engine for Three Systems

    SciTech Connect

    Freeman, Janine; Simon, Joseph

    2015-07-07

    Aurora Solar Inc. is building a cloud-based optimization platform to automate the design, engineering, and permit generation process of solar photovoltaic (PV) installations. They requested that the National Renewable Energy Laboratory (NREL) validate the performance of the PV system performance simulation engine of Aurora Solar’s solar design platform, Aurora. In previous work, NREL performed a validation of multiple other PV modeling tools 1, so this study builds upon that work by examining all of the same fixed-tilt systems with available module datasheets that NREL selected and used in the aforementioned study. Aurora Solar set up these three operating PV systems in their modeling platform using NREL-provided system specifications and concurrent weather data. NREL then verified the setup of these systems, ran the simulations, and compared the Aurora-predicted performance data to measured performance data for those three systems, as well as to performance data predicted by other PV modeling tools.

  1. SuperDARN observations of pulsating aurora

    NASA Astrophysics Data System (ADS)

    Clausen, L. B. N.; Yeoman, T. K.; Hosokawa, K.; Yukimatu, A. S.; Sato, N.; Milan, S. E.; Lester, M.

    2009-04-01

    On 25 September 2006 the all-sky camera located in Tjornes, Iceland observed pulsating aurora. During the event, the SuperDARN radar at Pykkvibaer was running in a high time, high spatial resolution mode and observed oscillating Doppler velocities. The pulsating velocities were observed in two separate patches of backscatter at different range gates, with different velocities. Backscattered power and spectral width as well as elevation angle data suggest that the power associated with each patch travelled along different ray paths. We discuss possible ray paths as well as the mechanisms that could have led to the difference in Doppler velocity observed for each patch.

  2. Multifunctional human transcriptional coactivator protein PC4 is a substrate of Aurora kinases and activates the Aurora enzymes.

    PubMed

    Dhanasekaran, Karthigeyan; Kumari, Sujata; Boopathi, Ramachandran; Shima, Hiroki; Swaminathan, Amrutha; Bachu, Mahesh; Ranga, Udaykumar; Igarashi, Kazuhiko; Kundu, Tapas K

    2016-03-01

    Positive coactivator 4 (PC4), a human transcriptional coactivator, is involved in diverse processes like chromatin organization and transcription regulation. It is hyperphosphorylated during mitosis, with unknown significance. For the first time, we demonstrate the function of PC4 outside the nucleus upon nuclear envelope breakdown. A fraction of PC4 associates with Aurora A and Aurora B and undergoes phosphorylation, following which PC4 activates both Aurora A and B to sustain optimal kinase activity to maintain the phosphorylation gradient for the proper functioning of the mitotic machinery. This mitotic role is evident in PC4 knockdown cells where the defects are rescued only by the catalytically active Aurora kinases, but not the kinase-dead mutants. Similarly, the PC4 phosphodeficient mutant failed to rescue such defects. Hence, our observations establish a novel mitotic function of PC4 that might be dependent on Aurora kinase-mediated phosphorylation. PMID:26777301

  3. What's so Bor(a)ing about Aurora-A activation?

    PubMed

    Wiese, Christiane; O'Brien, Lori L

    2006-08-01

    Aurora-A kinases are highly conserved mitotic kinases required for cell division. The regulation of Aurora-A activity is less highly conserved and currently poorly understood. Work by Knoblich and coworkers in this issue of Developmental Cell identifies the conserved protein, Aurora Borealis (Bora), as a key regulator of Aurora-A activity during mitosis. PMID:16890151

  4. The Jovian aurora: Electron or ion precipitation

    NASA Technical Reports Server (NTRS)

    Waite, J. H., Jr.; Clarke, J. T.; Cravens, T. E.

    1986-01-01

    High signal-to-noise spectra of the Jovian aurora at UV wavelengths obtained using the International Ultraviolet Explorer Observatory (including the brightest Jovian aurora observed to date) set strigent upper limits for sulfur and oxygen emissions, which would be associated with the precipitation of energetic heavy ions in the upper Jovian atmosphere if they were solely responsible for Jovian auroral processes. Model calculations of heavy ion precipitation and corresponding estimates of the associated sulfur and oxygen UV emissions previously carried out suggest emission values for 1304 A OI emission that are at least 30 times larger than the upper limit values set by the IUE observations reported. On the other hand the observed (feature of SII at 1256 A of 2 kR) is quite comparable to the theoretically predicted emission intensity. Taken together these observations and calculations suggest that electron as well as ion precipitation play a role in Jovian auroral processes. In light of earlier X-ray observations and in-situ plasma observations that suggest energetic heavy ion precipitation in the Jovian auroral zone, a scenario is suggested where heavy ion auroral energy deposition is concentrated at altitudes below the homopause. Electrons with energies of 10 to 30 keV are responsible for the bulk of the observable UV and EUV emissions since they deposit their energy above the methane absorbing layer defined by the homopause.

  5. Artificial Aurora Generated by HAARP (Invited)

    NASA Astrophysics Data System (ADS)

    Streltsov, A. V.; Kendall, E. A.

    2013-12-01

    We present results from the ionospheric heating experiment conducted on March 12, 2013 at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. During the experiment HAARP transmitted X-mode 4.57 MHz waves modulated with the frequency 0.9 mHz and pointed in the direction of the magnetic zenith. The beam was focused to ~20 km spot at the altitude 100 km. The heating produces two effects: First, it generates magnetic field-aligned currents producing D and H components of the magnetic field with frequency 0.9 mHz detected by fluxgate magnetometer in Gakona. Second, the heating produced bright luminous structures in the heated region detected with the SRI telescope in 427.8 nm, 557.7 nm, 630.0 nm wavelengths. We emphasize, that for the best of our knowledge, this is the first experiment where the heating of the ionosphere with X-mode produces luminous structures in the ionosphere. We classify this luminosity as an 'artificial aurora', because it correlate with the intensity of the magnetic field-aligned currents, and such correlation is constantly seen in the natural aurora.

  6. Pulsating aurorae: Evidence for flux limiting

    SciTech Connect

    Davidson, G.T.; Sears, R.D.

    1980-03-01

    Theoretical models based upon the concept of self-modulated VLF wave-electron interactions have been proposed to explain pulsating aurorae. These models incorporate the idea of a trapping limit, above which strong diffusion into the loss cone rapidly removes any excess electrons. At flux values near the trapping limit, perturbations of the trapped electron distribution can result in cyclic wave growth and electron precipitation. The trapping limit is thus related to the energy deposited and the characteristic energy of electrons precipitated in pulsating aurorae. Photometric measurements of the total energy deposit and of the mean energy parameter made at Chatanika, Alaska (invariant geomagnetic latitude, 65 /sup 0/) indicate that the well-developed pulsations are caused mainly by a modulation of the mean energy parameter. Thus, a nearly constant ''limiting'' value for the precipitating flux is measured F=7 x 10/sup 8/ el/cm/sup 2/ sec from which a trapped flux limit of Japprox. =3 x 10/sup 9/ el/cm/sup 2/ sec can be inferred.

  7. HUBBLE PROVIDES COMPLETE VIEW OF JUPITER'S AURORAS

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA's Hubble Space Telescope has captured a complete view of Jupiter's northern and southern auroras. Images taken in ultraviolet light by the Space Telescope Imaging Spectrograph (STIS) show both auroras, the oval- shaped objects in the inset photos. While the Hubble telescope has obtained images of Jupiter's northern and southern lights since 1990, the new STIS instrument is 10 times more sensitive than earlier cameras. This allows for short exposures, reducing the blurring of the image caused by Jupiter's rotation and providing two to five times higher resolution than earlier cameras. The resolution in these images is sufficient to show the 'curtain' of auroral light extending several hundred miles above Jupiter's limb (edge). Images of Earth's auroral curtains, taken from the space shuttle, have a similar appearance. Jupiter's auroral images are superimposed on a Wide Field and Planetary Camera 2 image of the entire planet. The auroras are brilliant curtains of light in Jupiter's upper atmosphere. Jovian auroral storms, like Earth's, develop when electrically charged particles trapped in the magnetic field surrounding the planet spiral inward at high energies toward the north and south magnetic poles. When these particles hit the upper atmosphere, they excite atoms and molecules there, causing them to glow (the same process acting in street lights). The electrons that strike Earth's atmosphere come from the sun, and the auroral lights remain concentrated above the night sky in response to the 'solar wind,' as Earth rotates underneath. Earth's auroras exhibit storms that extend to lower latitudes in response to solar activity, which can be easily seen from the northern U. S. But Jupiter's auroras are caused by particles spewed out by volcanoes on Io, one of Jupiter's moons. These charged particles are then magnetically trapped and begin to rotate with Jupiter, producing ovals of auroral light centered on Jupiter's magnetic poles in both the day and night skies

  8. Jovian-like aurorae on Saturn.

    PubMed

    Stallard, Tom; Miller, Steve; Melin, Henrik; Lystrup, Makenzie; Cowley, Stan W H; Bunce, Emma J; Achilleos, Nicholas; Dougherty, Michele

    2008-06-19

    Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic field (although other processes form aurorae at both planets). At Saturn, only the main auroral oval has previously been observed and there remains much debate over its origin. Here we report the discovery of a secondary oval at Saturn that is approximately 25 per cent as bright as the main oval, and we show this to be caused by interaction with the middle magnetosphere around the planet. This is a weak equivalent of Jupiter's main oval, its relative dimness being due to the lack of as large a source of ions as Jupiter's volcanic moon Io. This result suggests that differences seen in the auroral emissions from Saturn and Jupiter are due to scaling differences in the conditions at each of these two planets, whereas the underlying formation processes are the same. PMID:18563160

  9. High-speed stereoscopy of aurora

    NASA Astrophysics Data System (ADS)

    Kataoka, R.; Fukuda, Y.; Uchida, H. A.; Yamada, H.; Miyoshi, Y.; Ebihara, Y.; Dahlgren, H.; Hampton, D.

    2016-01-01

    We performed 100 fps stereoscopic imaging of aurora for the first time. Two identical sCMOS cameras equipped with narrow field-of-view lenses (15° by 15°) were directed at magnetic zenith with the north-south base distance of 8.1 km. Here we show the best example that a rapidly pulsating diffuse patch and a streaming discrete arc were observed at the same time with different parallaxes, and the emission altitudes were estimated as 85-95 km and > 100 km, respectively. The estimated emission altitudes are consistent with those estimated in previous studies, and it is suggested that high-speed stereoscopy is useful to directly measure the emission altitudes of various types of rapidly varying aurora. It is also found that variation of emission altitude is gradual (e.g., 10 km increase over 5 s) for pulsating patches and is fast (e.g., 10 km increase within 0.5 s) for streaming arcs.

  10. Large-Scale Aspects and Temporal Evolution of Pulsating Aurora

    NASA Technical Reports Server (NTRS)

    Jones, S. L.; Lessard, M. R.; Rychert, K.; Spanswick, E.; Donovan, E.

    2010-01-01

    Pulsating aurora is a common phenomenon generally believed to occur mainly in the aftermath of a, substorm, where dim long-period pulsating patches appear. The study determines the temporal and spatial evolution of pulsating events using two THEN IIIS ASI stations, at Gillam (66.18 mlat, 332.78 mlon, magnetic midnight at 0634 UT) and Fort Smith, (67.38 mlat, 306.64 mlon, magnetic midnight at, 0806 UT) along roughly the same invariant latitude. Parameters have been calculated from a database of 74 pulsating aurora events from 119 days of good optical data within the period from September 2007 through March 2008 as identified with the Gillam camera. It is shown that the source region of pulsating aurora drifts or expands eastward, away from magnetic midnight, for pre-midnight onsets and that the spatial evolution is more complicated for post midnight onsets, which has implications for the source mechanism. The most probable duration of a pulsating aurora event is roughly 1.5 hours while the distribution of possible event durations includes many long (several hours) events. This may suggest that pulsating aurora is not strictly a substorm recovery phase phenomenon but rather a persistent, long-lived phenomenon that may be temporarily disrupted by auroral substorms. Observations from the Gillam station show that in fact, pulsating aurora is quite common with the occurrence rate increasing to around 60% for morning hours, with 6910 of pulsating aurora onsets occurring after substorm breakup.

  11. The Potential Role of Aurora Kinase Inhibitors in Haematological Malignancies

    PubMed Central

    Farag, Sherif S.

    2011-01-01

    Summary Aurora kinases play an important role in the control of the cell cycle and have been implicated in tumourigenesis in a number of cancers. Among the haematological malignancies, overexpression of Aurora kinases has been reported in acute myeloid leukaemia, chronic myeloid leukaemia, acute lymphoblastic leukaemia, multiple myeloma, aggressive non-Hodgkin lymphoma and Hodgkin lymphoma. A large number of Aurora kinase inhibitors are currently in different stages of clinical development. In addition to varying in their selectivity for the different Aurora kinases, some also have activity directed at other cellular kinases involved in important molecular pathways in cancer cells. This review summarizes the biology of Aurora kinases and discusses why they may be good therapeutic targets in different haematological cancers. We describe preclinical data that has served as the rationale for investigating Aurora kinase inhibitors in different haematological malignancies, and summarize published results from early phase clinical trials. While the anti-tumour effects of Aurora kinase inhibitors appear promising, we highlight important issues for future clinical research and suggest that the optimal use of these inhibitors is likely to be in combination with cytotoxic agents already in use for the treatment of various haematological cancers. PMID:21980926

  12. Sun vs Moon: Competing Mechanisms for Recurring Aurorae

    NASA Astrophysics Data System (ADS)

    Parker, Gary

    2011-11-01

    At New England latitudes, sightings of northern lights do not occur at random. Among the nonrandom patterns are two of similar period caused by solar rotation and lunar revolution. From the 1880's to the 1950's controversy persisted regarding the mechanism by which aurorae recur at intervals that are multiples of about one month. Observations from northern Vermont are used to explore the influences of Sun and Moon on sightings of ``low'' latitude aurora with an eye to answering this question: with geomagnetic disturbance under strong solar control, and with aurorae associated with geomagnetic disturbance, why is the Sun's influence on auroral recurrence so weak?

  13. A study of the spatial distributions of auroras

    NASA Astrophysics Data System (ADS)

    Krakovetskii, Iu. K.; Nadubovich, Iu. A.; Popov, L. N.; Shumilova, N. A.

    The spatial distribution of auroras in the Norilsk region were studied using an automatic wide-angle camera, and spatial distribution profiles obtained over five winter seasons were compared with similar data available for the Yakut region. It is found that anomalies in the spatial distribution of auroras, referred to ground coordinates, are observed in both Yakutia, the location of a global magnetic anomaly, and Norilsk, which is characterized by the presence of regional and local magnetic anomalies. The projections of the anomalies in the spatial distribution of auroras onto the earth surface coincide with zones of earth's crust anisotropy.

  14. The horse-collar aurora - A frequent pattern of the aurora in quiet times

    NASA Technical Reports Server (NTRS)

    Hones, E. W., Jr.; Craven, J. D.; Frank, L. A.; Evans, D. S.; Newell, P. T.

    1989-01-01

    The frequent appearance of the 'horse-collar aurora' pattern in quiet-time DE 1 images is reported, presenting a two-hour image sequence that displays the basic features and shows that it sometimes evolves toward the theta configuration. There is some evidence for interplanetary magnetic field B(y) influence on the temporal development of the pattern. A preliminary statistical analysis finds the pattern appearing in one-third or more of the image sequences recorded during quiet times.

  15. Pulsating Aurora: the Equatorial Source Population & Local Morphological Interplay with Diffuse Aurora

    NASA Astrophysics Data System (ADS)

    Jaynes, A. N.; Lessard, M.; Rodriguez, J. V.; Rychert, K. M.; Donovan, E.; Michell, R. G.; Samara, M.

    2012-12-01

    Pulsating aurora (PA) is a common ionospheric phenomenon and as such offers a unique opportunity to study the source of the precipitating particle populations. While the suggestion that the source of these electrons originates near the equator was made decades ago, this conjecture has not been confirmed until now. The dominant source of loss-cone scattering for energetic equatorial electrons, which can then precipitate as PA, has been explored, but not yet clearly identified. In this study, we compare the frequencies of equatorial electron flux pulsations out in space and pulsating aurora luminosity fluctuations in the corresponding magnetic footprint within the ionosphere. We use simultaneous satellite- and ground-based data from GOES 13 and THEMIS instrumentation to show that there is a direct correlation between diffuse luminosity fluctuations near the ground and particle pulsations in equatorial space. To study the local morphology of such instances, observations of a dynamic pulsating aurora event were taken with a pair of colocated allsky imagers at Poker Flat, one filtered at 4278 (blue) and one at 5577 (green). Here we show preliminary results of differences in the energy channels and the structure that emerges and disappears as pulsating starts and stops.;

  16. Aurora at high latitudes of Ganymede

    NASA Astrophysics Data System (ADS)

    Lavrukhin, A. S.; Alexeev, I. I.

    2015-11-01

    The aurora on Ganymede results from the interaction of Jovian plasma disk electrons with Ganymede's tenuous atmosphere. At the same time, the electrons surrounding Ganymede have energy insufficient for the excitation of emission in the observed lines. They can acquire the necessary acceleration through various processes, such as reconnection of Ganymede's intrinsic magnetic field with the Jovian magnetic field in the upstream and downstream regions. The generation mechanism of a field-aligned potential drop on auroral field lines is considered. The lack of charge carriers required for the generation of the necessary current closing the Alfvén-wing field-aligned currents is shown to be responsible for the formation of an accelerating potential and the acceleration of thermal magnetospheric electrons. The total current in the circuit is determined by the calculated cross-field potential drop applied to Ganymede and by the Pedersen conductivity of Ganymede's ionosphere.

  17. Global magnetic anomaly and aurora of Neptune

    NASA Technical Reports Server (NTRS)

    Cheng, Andrew F.

    1990-01-01

    The large offset and tilt of Neptune's dipole magnetic field combine to create a global magnetic anomaly, analogous to but much more important than earth's South Atlantic Anomaly. Energetic particle precipitation loss within the Neptune anomaly creates 'atmospheric drift shadows' within which particle fluxes are greatly reduced. The energetic particle dropout observed by Voyager near closest approach occurred near the predicted times when Voyager passed within the atmospheric drift shadow. Extremely soft, structured bursts of ions and electrons within the drift shadow may result from plasma wave-induced pitch angle scattering of trapped particles confined near the magnetic equator. The dropout does not necessarily imply that Voyager passed through an earth-like discrete auroral zone, as earlier reported. The ion and electron fluxes observed within the dropout period correspond to particles that must precipitate to Neptune's atmosphere within the anomaly region. This anomaly precipitation can account for a major portion of the ultraviolet emissions previously identified as Neptune aurora.

  18. Were Greek temples oriented towards aurorae?

    NASA Astrophysics Data System (ADS)

    Liritzis, Ioannis; Vassiliou, Helen

    2006-02-01

    Two ancient Greek temples of Apollo at Bassae (Phigaleia, western Peloponnese, Greece), and Thermon at Aetolia, (Aetoloacarnania, western central Greece), have a north-south orientation of their main entrances. This is a rather rare alignment of temples in general and specifically of Apollo in classical Greece, where most of them have broadly an east-west orientation. Based on historical and mythological accounts, as well as astronomical orientation measurements, the northern direction orientation of these constructions may relate to the rare, albeit impressive, occurrence of aurorae borealis, the northern lights. These strong lights are attributed to god Apollo by the epithet ``hyperborean'', meaning to the northern lands. Attribution is supported by archaeomagnetic directional data accompanied by auroral occurrence during those times.

  19. The excitation of O2 in auroras.

    NASA Technical Reports Server (NTRS)

    Cartwright, D. C.; Trajmar, S.; Williams, W.

    1972-01-01

    Newly measured electron impact cross sections for excitation of the a super 1 Delta sub g and b super 1 Sigma (plus) sub g electronic states of O2 have been employed to predict the absolute volume emission rates from these states under auroral conditions. A secondary electron flux typical of an IBC II nighttime aurora was used, and the most important quenching processes were included in the calculations. The new excitation cross sections for the a super 1 Delta sub g and b super 1 Sigma (plus) sub g states are more than an order of magnitude larger than previous estimates and lead to correspondingly greater intensities in the atmospheric and IR atmospheric band systems. The calculated intensity ratios of the volume emission rates of 7621 A and 1.27 micron to that for 3914 A are smaller than those obtained from aircraft observations and recent rocket experiments.

  20. Study of artificially generated and natural auroras

    NASA Technical Reports Server (NTRS)

    Davis, T. N.

    1973-01-01

    The feasibility of generating artificial auroras by injecting electrons into the upper atmosphere was investigated by using an electron accelerator aboard an Aerobee 350 rocket. Four of the artificial auroral rays were detected and recorded by two geophysical sites separated enough to enable the spatial coordinates of the rays to be determined by triangulation. It was found that (1) the beam remained well collimated; (2) most of the initial beam energy was deposited in the atmosphere; (3) plasma instabilities did not play a significant role; and (4) the orientations of the rays were determined with sufficient accuracy to improve the knowledge of the earth's magnetic field over the Virginia coast. The publications resulting from this research are listed.

  1. Hyperspectral all-sky imaging of auroras.

    PubMed

    Sigernes, Fred; Ivanov, Yuriy; Chernouss, Sergey; Trondsen, Trond; Roldugin, Alexey; Fedorenko, Yury; Kozelov, Boris; Kirillov, Andrey; Kornilov, Ilia; Safargaleev, Vladimir; Holmen, Silje; Dyrland, Margit; Lorentzen, Dag; Baddeley, Lisa

    2012-12-01

    A prototype auroral hyperspectral all-sky camera has been constructed and tested. It uses electro-optical tunable filters to image the night sky as a function of wavelength throughout the visible spectrum with no moving mechanical parts. The core optical system includes a new high power all-sky lens with F-number equal to f/1.1. The camera has been tested at the Kjell Henriksen Observatory (KHO) during the auroral season of 2011/2012. It detects all sub classes of aurora above ~½ of the sub visual 1kR green intensity threshold at an exposure time of only one second. Supervised classification of the hyperspectral data shows promise as a new method to process and identify auroral forms. PMID:23262713

  2. The Phenomenon of the Polar Aurora

    NASA Astrophysics Data System (ADS)

    Landsberg, H. E.

    The eerie flickers of auroras have inspired awe since times immemorial. They kindled the fears and superstitions of people in the prescientific era and the curiosity of inquiring minds since. Yet it is only since the arrival of the space age that a full physical understanding has been reached. This has probably stimulated not only substantial journal literature but a number of books which trace the development of that understanding from the supernatural to phenomenology to a reasonably complete physical model. AGU published the work of Eather [1980], and the Nordic experience and contribution is superbly reflected in the treatise of Brekke and Egeland [1983]. A somewhat more theoretical framework is offered by Volland [1984].

  3. Aurora-C Interactions with Survivin and INCENP Reveal Shared and Distinct Features Compared with Aurora-B Chromosome Passenger Protein Complex

    PubMed Central

    Sasai, Kaori; Katayama, Hiroshi; Hawke, David H.; Sen, Subrata

    2016-01-01

    Aurora-C, a member of the Aurora kinase family that can complement Aurora-B function in mitosis is either moderately expressed or repressed in most adult somatic tissues but is active in early embryonic development and expressed at elevated levels in multiple human cancers. Aurora-C overexpression reportedly plays a role in tumorigenic transformation. We performed detailed characterization of Aurora-C interactions with members of the Chromosome Passenger Complex (CPC), Survivin and Inner Centromere Protein (INCENP) in reference to known Aurora-B interactions to understand the functional significance of Aurora-C overexpression in human cancer cells. The results revealed that silencing of Aurora-C or -B individually does not affect localization of the other kinase and the two kinases exist predominantly in independent complexes in vivo. Presence of Aurora-C and -B in molecular complexes of varying as well as overlapping sizes and co-existence in INCENP overexpressing cells indicated oligomerization of ternary complexes under different physiological conditions in vivo. Furthermore, Aurora-C and -B stabilized INCENP through interaction with and phosphorylation of the IN box domain while Aurora-C was activated following Survivin phosphorylation on Serine 20. Phosphorylation of Survivin residue Serine 20 by Aurora-C and –B appears important for proper chromosome segregation. Taken together, our study suggests that Aurora-C, expressed at low levels in somatic cells, functions as a catalytic component of the CPC together with Aurora-B through mitosis. Elevated expression of Aurora-C in cancer cells alters the structural and functional characteristics of the Aurora-B-CPC leading to chromosomal instability. PMID:27332895

  4. The AURORA initiative for metastatic breast cancer.

    PubMed

    Zardavas, D; Maetens, M; Irrthum, A; Goulioti, T; Engelen, K; Fumagalli, D; Salgado, R; Aftimos, P; Saini, K S; Sotiriou, C; Campbell, P; Dinh, P; von Minckwitz, G; Gelber, R D; Dowsett, M; Di Leo, A; Cameron, D; Baselga, J; Gnant, M; Goldhirsch, A; Norton, L; Piccart, M

    2014-11-11

    Metastatic breast cancer is one of the leading causes of cancer-related mortality among women in the Western world. To date most research efforts have focused on the molecular analysis of the primary tumour to dissect the genotypes of the disease. However, accumulating evidence supports a molecular evolution of breast cancer during its life cycle, with metastatic lesions acquiring new molecular aberrations. Recognising this critical gap of knowledge, the Breast International Group is launching AURORA, a large, multinational, collaborative metastatic breast cancer molecular screening programme. Approximately 1300 patients with metastatic breast cancer who have received no more than one line of systemic treatment for advanced disease will, after giving informed consent, donate archived primary tumour tissue, as well as will donate tissue collected prospectively from the biopsy of metastatic lesions and blood. Both tumour tissue types, together with a blood sample, will then be subjected to next generation sequencing for a panel of cancer-related genes. The patients will be treated at the discretion of their treating physicians per standard local practice, and they will be followed for clinical outcome for 10 years. Alternatively, depending on the molecular profiles found, patients will be directed to innovative clinical trials assessing molecularly targeted agents. Samples of outlier patients considered as 'exceptional responders' or as 'rapid progressors' based on the clinical follow-up will be subjected to deeper molecular characterisation in order to identify new prognostic and predictive biomarkers. AURORA, through its innovative design, will shed light onto some of the unknown areas of metastatic breast cancer, helping to improve the clinical outcome of breast cancer patients. PMID:25225904

  5. The AURORA initiative for metastatic breast cancer

    PubMed Central

    Zardavas, D; Maetens, M; Irrthum, A; Goulioti, T; Engelen, K; Fumagalli, D; Salgado, R; Aftimos, P; Saini, K S; Sotiriou, C; Campbell, P; Dinh, P; von Minckwitz, G; Gelber, R D; Dowsett, M; Di Leo, A; Cameron, D; Baselga, J; Gnant, M; Goldhirsch, A; Norton, L; Piccart, M

    2014-01-01

    Metastatic breast cancer is one of the leading causes of cancer-related mortality among women in the Western world. To date most research efforts have focused on the molecular analysis of the primary tumour to dissect the genotypes of the disease. However, accumulating evidence supports a molecular evolution of breast cancer during its life cycle, with metastatic lesions acquiring new molecular aberrations. Recognising this critical gap of knowledge, the Breast International Group is launching AURORA, a large, multinational, collaborative metastatic breast cancer molecular screening programme. Approximately 1300 patients with metastatic breast cancer who have received no more than one line of systemic treatment for advanced disease will, after giving informed consent, donate archived primary tumour tissue, as well as will donate tissue collected prospectively from the biopsy of metastatic lesions and blood. Both tumour tissue types, together with a blood sample, will then be subjected to next generation sequencing for a panel of cancer-related genes. The patients will be treated at the discretion of their treating physicians per standard local practice, and they will be followed for clinical outcome for 10 years. Alternatively, depending on the molecular profiles found, patients will be directed to innovative clinical trials assessing molecularly targeted agents. Samples of outlier patients considered as ‘exceptional responders' or as ‘rapid progressors' based on the clinical follow-up will be subjected to deeper molecular characterisation in order to identify new prognostic and predictive biomarkers. AURORA, through its innovative design, will shed light onto some of the unknown areas of metastatic breast cancer, helping to improve the clinical outcome of breast cancer patients. PMID:25225904

  6. Observation and theory of the radar aurora

    SciTech Connect

    Sahr, J.D.

    1990-01-01

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. Observations are presented of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, a simple nonlinear fluid theory of electrojet ion-acoustic waves is introduced, and reduced to a form of the three-wave interaction equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able to account for type 3 waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of the research a simple new radar transmitting mode and signal processing algorithm was generated which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies. Several new radar data analysis routines were developed, including the principally cross-beam image and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that type 3 waves originate at ordinary electrojet altitudes, not in the upper E region, from which it is concluded that the electrostatic ion-cyclotron mode does not generate type 3 waves. The measured height of type 3 waves and other spectral analyses provide support for the pure ion-acoustic theory of type 3 waves. Suggestions are offered for hardware improvements to the CUPRI radar, new experiments to test new and existing theories.

  7. Aurora Boundaries Quantified by Geomagnetic Index

    NASA Astrophysics Data System (ADS)

    Carbary, J. F.

    2004-12-01

    Various operational systems require information on the location and intensity of the aurora. A statistical model of the aurora is given using global images from the Ultraviolet Imager (UVI) on the Polar satellite. The equatorward (EQ), poleward (PO) and peak (PK) boundaries of the auroral oval are determined. using UVI images averaged into 1° x1° spatial bins according to common geomagnetic indices such as Kp, AE, AL, and PCI. From these bin-averaged images, latitude intensity profiles at 1 hour MLT intervals are constructed by interpolation. A background is subtracted for each profile, and the EQ, PO, and PK boundary latitudes are found from the corrected profile. (The PK boundary is the maximum, and the EQ and PO boundaries are threshold locations of fixed irradiances such as 1, 2, or 4 photons/cm2s.) Several months of images during the winter and summer of 1997 were used to statistically quantify the boundaries at various levels of geomagnetic activity given by the several indices. As expected, the higher the level of activity, the wider and more expanded the oval. More importantly, the boundaries are functionally related to the indices at any local time. These functional relations can then be used to determine the auroral location at any level of geomagnetic activity given by the indices. Thus, given a level of geomagnetic activity, one can find the boundaries of the oval as defined on the basis of intensity. By monitoring the relevant geomagnetic index, an operational system can then easily compute the expected oval location and judge its impact on performance. The optimum indices that best define the oval will be discussed.

  8. SPICAM observations and modeling of Mars aurorae

    NASA Astrophysics Data System (ADS)

    Soret, Lauriane; Gérard, Jean-Claude; Libert, Ludivine; Shematovich, Valery I.; Bisikalo, Dmitry V.; Stiepen, Arnaud; Bertaux, Jean-Loup

    2016-01-01

    Martian aurorae have been detected with the SPICAM instrument on board Mars Express both in the nadir and the limb viewing modes. In this study, we focus on three limb observations to determine both the altitudes and the intensities of the auroral emissions. The CO (a3Π-X1Σ) Cameron bands between 190 and 270 nm, the CO (A1Π-X1Σ+) Fourth Positive system (CO 4P) between 135 and 170 nm, the CO2+ (B2Σu+-X2Πg) doublet at 289 nm, the OI at 297.2 nm and the 130.4 nm OI triplet emissions have been identified in the spectra and in the time variations of the signals. The intensities of these auroral emissions have been quantified and the altitude of the strongest emission of the CO Cameron bands has been estimated to be 137 ± 27 km. The locations of these auroral events have also been determined and correspond to the statistical boundary of open-closed magnetic field lines, in cusp-like structures. The observed altitudes of the auroral emissions are reproduced by a Monte-Carlo model of electron transport in the Martian thermosphere for mono-energetic electrons between 40 and 200 eV. No correlation between electron fluxes measured in the upper thermosphere and nadir auroral intensity has been found. Here, we simulate auroral emissions observed both at the limb and at the nadir using electron energy spectra simultaneously measured with the ASPERA-3/ELS instrument. The simulated altitudes are in very good agreement with the observations. We find that predicted vertically integrated intensities for the various auroral emissions are overestimated, probably as a consequence of the inclination and curvature of the magnetic field line threading the aurora. However, the relative brightness of the CO and CO2+ emissions is in good agreement with the observations.

  9. NORTH PORTAL OF VIADUCT WHERE IT MERGES WITH AURORA AVENUE; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    NORTH PORTAL OF VIADUCT WHERE IT MERGES WITH AURORA AVENUE; DENNY PARK AT TOP MIDDLE OF PICTURE. TOP OF PORTAL INTERSECTS WITH SEVENTH AVENUE ON THE DIAGONAL. - Alaskan Way Viaduct and Battery Street Tunnel, Seattle, King County, WA

  10. 5. Aurora Borealis Pass over the United States at Night

    NASA Video Gallery

    This video of the United States at night and the Aurora Borealis was taken by the crew of Expedition 29 on board the International Space Station. This sequence of shots was taken September 29, 2011...

  11. Are Accurins the cure for Aurora kinase inhibitors?

    PubMed

    Bearss, David J

    2016-02-10

    A nanoparticle formulation of an Aurora B inhibitor increases antitumor efficacy and reduces toxicity, which may be a precedent for the use of this technology with other small molecules (Ashton et al., this issue). PMID:26865564

  12. Simultaneous observations of a theta aurora and associated magnetotail plasmas

    SciTech Connect

    Huang, C.Y.; Craven, J.D.; Frank, L.A.

    1989-08-01

    Observations of a transpolar arc and simultaneous measurements of associated plasmas in the magnetotail lobe on March 25, 1982, are presented. The auroral imager on board Dynamics Explorer 1 observes a theta aurora in the northern polar cap for more than 2 hours, between 0502 and 0720 UT. ISEE 1 is located in the southern lobe of the geomagnetic tail at a distance of 22.2 RE during this time. The plasma and particle detectors measure intermittent bursts of particle fluxes between 0530 and 0705 UT. The observations suggest that these particle fluxes represent the high-altitude signature of a theta aurora in the southern polar cap. The relatively dense and energetic plasmas are organized into several filamentary structures. Magnetic mapping between the two polar regions indicates that the theta aurora in the southern hemisphere is a mirror reflection about the noon-midnight meridional plane of the theta aurora in the northern hemisphere.

  13. Drugging MYCN through an allosteric transition in Aurora Kinase A

    PubMed Central

    Gustafson, William Clay; Meyerowitz, Justin Gabriel; Nekritz, Erin A.; Chen, Justin; Benes, Cyril; Charron, Elise; Simonds, Erin Fitzgerald; Seeger, Robert; Matthay, Katherine; Hertz, Nicholas T.; Eilers, Martin; Shokat, Kevan M.; Weiss, William A.

    2014-01-01

    Summary MYC proteins are major drivers of cancer, yet are considered undruggable, as their DNA binding domains are composed of two extended alpha helices with no apparent surfaces for small molecule binding. Proteolytic degradation of MYCN protein is regulated in part by a kinase-independent function of Aurora A. We describe a class of inhibitors that disrupts the native conformation of Aurora A, and drives degradation of MYCN protein across MYCN-driven cancers. Comparison of co-crystal structures with structure-activity relationships across multiple inhibitors and chemotypes, coupled with mechanistic studies and biochemical assays, delineates an Aurora A conformation-specific effect on proteolytic degradation of MYCN, rather than simple nanomolar-level inhibition of Aurora A kinase activity. PMID:25175806

  14. Equatorward and poleward expansion of the auroras during auroral substorms

    NASA Technical Reports Server (NTRS)

    Nakamura, Rumi; Oguti, Takasi; Yamamoto, Tatsundo; Kokubun, Susumu

    1993-01-01

    The formation of the auroral bulge is investigated on the basis of all-sky TV auroral data with high spatial and temporal resolution. Ways in which the discrete auroral structures within the poleward expanding bulge develop systematically toward the west, the east, and also equatorward from a localized breakup region are shown. Auroral structure at the western end of the bulge (a surge) develops with clockwise rotation as viewed along the magnetic field direction. At the eastern part of the bulge, thin auroral features propagate eastward from the breakup region. Around the central meridian of the bulge, auroral features expand equatorward and become north-south aligned (the N-S aurora). The N-S aurora and the eastward propagating aurora develop into diffuse and pulsating aurora after the expansion. It is suggested that these discrete auroral structures in the bulge develop along the plasma streamlines in a localized distorted two-cell equipotential distribution.

  15. Simultaneous observations of a theta aurora and associated magnetotail plasmas

    NASA Technical Reports Server (NTRS)

    Huang, C. Y.; Craven, J. D.; Frank, L. A.

    1989-01-01

    Observations of a transpolar arc and simultaneous measurements of associated plasmas in the magnetotail lobe on March 25, 1982, are presented. The auroral imager on board Dynamics Explorer 1 observes a theta aurora in the northern polar cap for more than two hours, between 0502 and 0720 UT. ISEE 1 is located in the southern lobe of the geomagnetic tail at a distance of 22.2 R(E) during this time. The plasma and particle detectors measure intermittent bursts of particle fluxes between 0530 and 0705 UT. The observations suggest that these particle fluxes represent the high-altitude signature of a theta aurora in the southern polar cap. The relatively dense and energetic plasmas are organized into several filamentary structures. Magnetic mapping between the two polar regions indicates that the theta aurora in the Southern Hemisphere is a mirror reflection about the noon-midnight meridional plane of the theta aurora in the Northern Hemisphere.

  16. A new Director for the BAA Aurora Section

    NASA Astrophysics Data System (ADS)

    Gavine, D.

    2011-02-01

    from 2011 January 1, Dr Dave Gavine handed over the Aurora Section Directorship to Ken Kennedy, who has been Assistant Director for the last five years, with special responsibility for Noctilucent Clouds, currently the Section's most important work.

  17. Saturn's aurora observed by the Cassini camera at visible wavelengths

    NASA Astrophysics Data System (ADS)

    Dyudina, Ulyana A.; Ingersoll, Andrew P.; Ewald, Shawn P.; Wellington, Danika

    2016-01-01

    The first observations of Saturn's visible-wavelength aurora were made by the Cassini camera. The aurora was observed between 2006 and 2013 in the northern and southern hemispheres. The color of the aurora changes from pink at a few hundred km above the horizon to purple at 1000-1500 km above the horizon. The spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with laboratory simulated auroras. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs between 70° and 80° latitude north and between 65° and 80° latitude south, which sometimes spiral around the pole, and sometimes form double arcs. A large 10,000-km-scale longitudinal brightness structure persists for more than 100 h. This structure rotates approximately together with Saturn. On top of the large steady structure, the auroras brighten suddenly on the timescales of a few minutes. These brightenings repeat with a period of ∼1 h. Smaller, 1000-km-scale structures may move faster or lag behind Saturn's rotation on timescales of tens of minutes. The persistence of nearly-corotating large bright longitudinal structure in the auroral oval seen in two movies spanning 8 and 11 rotations gives an estimate on the period of 10.65 ± 0.15 h for 2009 in the northern oval and 10.8 ± 0.1 h for 2012 in the southern oval. The 2009 north aurora period is close to the north branch of Saturn Kilometric Radiation (SKR) detected at that time.

  18. IK-guided PP2A suppresses Aurora B activity in the interphase of tumor cells.

    PubMed

    Lee, Sunyi; Jeong, Ae Lee; Park, Jeong Su; Han, Sora; Jang, Chang-Young; Kim, Keun Il; Kim, Yonghwan; Park, Jong Hoon; Lim, Jong-Seok; Lee, Myung Sok; Yang, Young

    2016-09-01

    Aurora B activation is triggered at the mitotic entry and required for proper microtubule-kinetochore attachment at mitotic phase. Therefore, Aurora B should be in inactive form in interphase to prevent aberrant cell cycle progression. However, it is unclear how the inactivation of Aurora B is sustained during interphase. In this study, we find that IK depletion-induced mitotic arrest leads to G2 arrest by Aurora B inhibition, indicating that IK depletion enhances Aurora B activation before mitotic entry. IK binds to Aurora B, and colocalizes on the nuclear foci during interphase. Our data further show that IK inhibits Aurora B activation through recruiting PP2A into IK and Aurora B complex. It is thus believed that IK, as a scaffold protein, guides PP2A into Aurora B to suppress its activity in interphase until mitotic entry. PMID:26906715

  19. The role and targeting of Aurora kinases in head and neck cancer

    PubMed Central

    Mehra, Ranee; Serebriiskii, Ilya G.; Burtness, Barbara; Astsaturov, Igor; Golemis, Erica A.

    2014-01-01

    Summary Controlled activation of the Aurora kinases regulates mitotic progression in normal cells. Overexpression and hyperactivation of the Aurora-A and -B kinases play a leading role in tumorigenesis, inducing aneuploidy and genomic instability. In squamous cell carcinomas of the head and neck (SCCHN), overexpression of Aurora-A is associated with decreased survival, and reduction of Aurora-A and -B expression inhibits SCCHN cell growth and increases apoptosis. In this article, we provide a basic overview of the biological functions of Aurora kinases in normal cells and in cancer, and review both small studies and high throughput datasets that implicate Aurora-A, particularly, in the pathogenesis of SCCHN. Early phase clinical trials are beginning to evaluate the activity of small molecule inhibitors of the Aurora kinases. We summarize the state of current trials evaluating Aurora inhibitors in SCCHN, and discuss rational directions for future drug combination trials and biomarkers for use with Aurora-inhibiting agents. PMID:23993387

  20. Saturn's northern auroras as observed using the Hubble Space Telescope

    NASA Astrophysics Data System (ADS)

    Nichols, J. D.; Badman, S. V.; Bunce, E. J.; Clarke, J. T.; Cowley, S. W. H.; Hunt, G. J.; Provan, G.

    2016-01-01

    We discuss the features of Saturn's northern FUV auroras as observed during a program of Hubble Space Telescope observations which executed over 2011-2013 and culminated, along with Cassini observations, in a comprehensive multi-spectral observing campaign. Our 2011-2013 observations of the northern aurora are also compared with those from our 2007-2008 observation of the southern aurora. We show that the variety of morphologies of the northern auroras is broadly consistent with the southern, and determine the statistical equatorward and poleward boundary locations. We find that our boundaries are overall consistent with previous observations, although a modest poleward displacement of the poleward boundaries is due to the increased prevalence of poleward auroral patches in the noon and afternoon sectors during this program, likely due to the solar wind interaction. We also show that the northern auroral oval oscillates with the northern planetary period oscillation (PPO) phase in an elongated ellipse with semi-major axis ∼1.6° oriented along the post-dawn/post-dusk direction. We further show that the northern auroras exhibit dawn-side brightenings at zero northern magnetic PPO phase, although there is mixed evidence of auroral emissions fixed in the rotating frame of the northern PPO current system, such that overall the dependence of the auroras on northern magnetic phase is somewhat weak.

  1. A Note on the Height of Auroras by Leonhard Euler

    NASA Astrophysics Data System (ADS)

    Schröder, Wilfried

    In former times, mostly before the end of the 19th century, many speculations were made about the height of the Earth's atmosphere. Scientists also discussed the height of the auroras, which were often observed in middle Europe. Mostly, people thought the auroras were manifestations of the lower Earth's atmosphere, and that they formed a circle inside of it. Only a few speculations were devoted to the exact height and nature of these phenomena. They were thought to be signs from God, until the appearance of the aurora on 17 March 1716 (for detail, see Schröder [2001]). An interesting letter written by Leonhard Euler (1707-1783), a Swiss mathematician and member of the Berlin Academy of Sciences, to the theologian and scholar Johann Esaias Silberschlag (1716-1791)-also a member of the Berlin Academy of Sciences- gives some insight into the discussion that took place in the 18th century. Euler wrote in his letter that the auroras, similar to the great meteors or fireballs, must be placed in the high atmosphere, mostly above the height of the meteors. For Euler, it was clear that meteors, fireballs, and auroras were all objects associated with the Earth's atmosphere. In those days, the idea that the auroral phenomena were caused in the atmosphere and were part of its constitution was new. Following the 17 March 1716 event, scientists of the day concluded that the height of the aurora was above that of the normally observed clouds.

  2. Equatorward evolution of auroras from the poleward auroral boundary

    NASA Astrophysics Data System (ADS)

    Saka, O.; Hayashi, K.; Thomsen, M. F.

    2016-07-01

    An all-sky imager installed at the midnight sector in Dawson City (66.0° in geomagnetic latitude) recorded the equatorward evolution of auroras from the auroral poleward boundary. The auroras evolved as shear layers expanding southeastward with velocities of 1-4 km/s, referred to as N-S auroras, and occurred during the transient intensification of the convection electric fields in the nighttime magnetosphere, as inferred from an electron spectrogram at geosynchronous altitudes. A continuous increase in the inclination angle of the field lines and magnetic field perturbations associated with propagating ionospheric loop currents were observed in the auroral zone during the N-S auroras. Simultaneously, Pc4 pulsations were observed at low latitudes from night to day sectors. We conclude the following: (1) the N-S auroras are an auroral manifestation of the earthward drift of plasma sheet electrons in the equatorial plane associated with transient and localized convection electric fields; (2) the Pc4 pulsations are produced in the magnetosphere by plasma sheet ions in the plasmasphere. The localized convection fields produce a vortical motion of plasmas in the equatorial plane, which may initiate the N-S auroras and ionospheric loop currents in the auroral zone.

  3. A New Aurora in Anaplastic Thyroid Cancer Therapy

    PubMed Central

    Baldini, Enke; D'Armiento, Massimino

    2014-01-01

    Anaplastic thyroid cancers (ATC) are among the most aggressive human neoplasms with a dire prognosis and a median survival time of few months from the diagnosis. The complete absence of effective therapies for ATC renders the identification of novel therapeutic approaches sorely needed. Chromosomal instability, a feature of all human cancers, is thought to represent a major driving force in thyroid cancer progression and a number of mitotic kinases showing a deregulated expression in malignant thyroid tissues are now held responsible for thyroid tumor aneuploidy. These include the three members of the Aurora family (Aurora-A, Aurora-B, and Aurora-C), serine/threonine kinases that regulate multiple aspects of chromosome segregation and cytokinesis. Over the last few years, several small molecule inhibitors targeting Aurora kinases were developed, which showed promising antitumor effects against a variety of human cancers, including ATC, in preclinical studies. Several of these molecules are now being evaluated in phase I/II clinical trials against advanced solid and hematological malignancies. In the present review we will describe the structure, expression, and mitotic functions of the Aurora kinases, their implications in human cancer progression, with particular regard to ATC, and the effects of their functional inhibition on malignant cell proliferation. PMID:25097550

  4. Solar activity around AD 775 from aurorae and radiocarbon

    NASA Astrophysics Data System (ADS)

    Neuhäuser, R.; Neuhäuser, D. L.

    2015-04-01

    A large variation in 14C around AD 775 has been considered to be caused by one or more solar super-flares within one year. We critically review all known aurora reports from Europe as well as the Near, Middle, and Far East from AD 731 to 825 and find 39 likely true aurorae plus four more potential aurorae and 24 other reports about halos, meteors, thunderstorms etc., which were previously misinterpreted as aurorae or misdated; we assign probabilities for all events according to five aurora criteria. We find very likely true aurorae in AD 743, 745, 762, 765, 772, 773, 793, 796, 807, and 817. There were two aurorae in the early 770s observed near Amida (now Diyarbak\\i r in Turkey near the Turkish-Syrian border), which were not only red, but also green-yellow - being at a relatively low geomagnetic latitude, they indicate a relatively strong solar storm. However, it cannot be argued that those aurorae (geomagnetic latitude 43 to 50°, considering five different reconstructions of the geomagnetic pole) could be connected to one or more solar super-flares causing the 14C increase around AD 775: There are several reports about low- to mid-latitude aurorae at 32 to 44° geomagnetic latitude in China and Iraq; some of them were likely observed (quasi-)simultaneously in two of three areas (Europe, Byzantium/Arabia, East Asia), one lasted several nights, and some indicate a particularly strong geomagnetic storm (red colour and dynamics), namely in AD 745, 762, 793, 807, and 817 - always without 14C peaks. We use 39 likely true aurorae as well as historic reports about sunspots together with the radiocarbon content from tree rings to reconstruct the solar activity: From AD {˜ 733} to {˜ 823}, we see at least nine Schwabe cycles; instead of one of those cycles, there could be two short, weak cycles - reflecting the rapid increase to a high 14C level since AD 775, which lies at the end of a strong cycle. In order to show the end of the dearth of naked-eye sunspots, we

  5. Aurora Kinase Inhibition Overcomes Cetuximab Resistance in Squamous Cell Cancer of the Head and Neck

    PubMed Central

    Hoellein, Alexander; Pickhard, Anja; von Keitz, Fabienne; Schoeffmann, Stephanie; Piontek, Guido; Rudelius, Martina; Baumgart, Anja; Wagenpfeil, Stefan; Peschel, Christian; Dechow, Tobias; Bier, Henning; Keller, Ulrich

    2011-01-01

    Squamous cell cancer of the head and neck (SCCHN) is the sixth leading cause for cancer deaths worldwide. Despite extense knowledge of risk factors and pathogenesis about 50 percent of all patients and essentially every patient with metastatic SCCHN eventually die from this disease. We analyzed the clinical data and performed immunohistochemistry for Epidermal growth factor receptor (EGFR) and Aurora kinase A (Aurora-A) expression in 180 SCCHN patients. Patients characterized by elevated EGFR and elevated Aurora-A protein expression in tumor tissue represent a risk group with poor disease-free and overall survival (EGFRlow Aurora-Alow versus EGFRhigh Aurora-Ahigh, p = 0.024). Treating SCCHN cell lines with a pan-Aurora kinase inhibitor resulted in defective cytokinesis, polyploidy and apoptosis, which was effective irrespective of the EGFR status. Combined Aurora kinase and EGFR targeting using a monoclonal anti-EGFR antibody was more effective compared to single EGFR and Aurora kinase inhibition. Comparing pan-Aurora kinase and Aurora-A targeting hints towards a strong and clinically relevant biological effect mediated via Aurora kinase B. Taken together, our findings characterize a new poor risk group in SCCHN patients defined by elevated EGFR and Aurora-A protein expression. Our results demonstrate that combined targeting of EGFR and Aurora kinases represents a therapeutic means to activate cell cycle checkpoints and apoptosis in SCCHN. PMID:21865609

  6. On the Origin of Io's Ultraviolet Aurora

    NASA Astrophysics Data System (ADS)

    Shaposhnikov, V. E.; Zaitsev, V. V.; Rucker, H. O.

    A model involving an additional contribution to Io's ultraviolet (UV) aurora is presented. A mechanism for heating of electrons of Io's ionospheric plasma up to sufficient energies for the excitation of Io's atmospheric oxygen and emitting of observed UV emission is proposed. The mechanism operates by the effect of the different magnetization of the electrons and ions in Io's ionosphere which in the course of Io's motion through the Jovian magnetic field causes the creation of a charge-separation electric field in the upstream part of the ionosphere. This field has a component parallel to the magnetic and shifts the electron distribution function relative to the ion distribution function by a value exceeding the thermal velocity of electrons. In this case, a Bunemann instability with a very large growth rate develops. This results in the excitation of turbulent pulsations at frequency close to the ion-sound frequency and the occurrence of anomalous resistance to the electric current. The latter causes heating of Io's ionospheric electrons up to a temperature of about 25 eV. Atmospheric oxygen molecules excited by collisions with the heated electrons of Io's ionosphere, whose density is about 6 × 10^4 cm^(-3), can contribute to the observed UV brightness. The proposed model permits one to explain the correlation of UV brightness with Io's magnetic longitude and the discrepancy between the anti-Jovian equatorial UV spots and sub-Jovian spots as well.

  7. Solar Aurora and a White Light Flare

    NASA Astrophysics Data System (ADS)

    Haerendel, Gerhard

    2016-07-01

    A white light flare analyzed by Krucker et al. (2011) poses a severe challenge to the solar physicist because of the high energy fluxes implied by a hitherto not achieved spatial resolution of simultaneous observations with Hinode and RHESSI. A scenario based on the auroral acceleration mechanism applied to flare conditions, 'Solar Aurora', is able to reproduce the observations, but implies several far-reaching assumptions on the mechanism as well as on the environmental parameters. Unavoidable consequences exist with regard to the spatial and temporal scales. They are extremely short because of the high density of the corona and the need for an energy conversion process involving some kind of anomalous resistivity, i.e. extremely high electric current densities. A further postulate is that of spontaneous propagation of an energy conversion front (ENF), once established, in three dimensions. It is assumed that about one half of the converted energy appears in form of runaway electrons. Obliqueness of the ENFs prevents the existence of a return current problem for the emerging runaway electrons. The key flare parameters are formulated quantitatively in terms of the environmental properties. Transverse length scales turn out to be in the ten centimeter range, time-scales in the range of one millisecond. The energy conversion occurs in 10E3 -10E4 ENFs just above the transition region in a background field of the order of 2000 G. Observational consequences are being discussed.

  8. Dancing Lights: Creating the Aurora Story

    NASA Astrophysics Data System (ADS)

    Wood, E. L.; Cobabe-Ammann, E. A.

    2009-12-01

    Science tells a story about our world, our existence, our history, and the larger environment our planet occupies. Bearing this in mind, we created a series of lessons for 3rd-5th grades using a cross-disciplinary approach to teaching about the aurora by incorporating stories, photos, movies, and geography into the science in order to paint a broad picture and answer the question, “why do we care?” The fundamental backbone of the program is literacy. Students write and illustrate fiction and non-fiction work, poetry, and brochures that solidify both language arts skills and science content. In a time when elementary teachers relegate science to less than one hour per week, we have developed a novel science program that can be easily integrated with other topics during the typical school day to increase the amount of science taught in a school year. We are inspiring students to take an interest in the natural world with this program, a stepping-stone for larger things.

  9. Aurora Kinases and Potential Medical Applications of Aurora Kinase Inhibitors: A Review

    PubMed Central

    Gavriilidis, Paschalis; Giakoustidis, Alexandros; Giakoustidis, Dimitrios

    2015-01-01

    Aurora kinases (AKs) represent a novel group of serine/threonine kinases. They were originally described in 1995 by David Glover in the course of studies of mutant alleles characterized with unusual spindle pole configuration in Drosophila melanogaster. Thus far, three AKs A, B, and C have been discovered in human healthy and neoplastic cells. Each one locates in different subcellular locations and they are all nuclear proteins. AKs are playing an essential role in mitotic events such as monitoring of the mitotic checkpoint, creation of bipolar mitotic spindle and alignment of centrosomes on it, also regulating centrosome separation, bio-orientation of chromosomes and cytokinesis. Any inactivation of them can have catastrophic consequences on mitotic events of spindle formation, alignment of centrosomes and cytokinesis, resulting in apoptosis. Overexpression of AKs has been detected in diverse solid and hematological cancers and has been linked with a dismal prognosis. After discovery and identification of the first aurora kinase inhibitor (AKI) ZM447439 as a potential drug for targeted therapy in cancer treatment, approximately 30 AKIs have been introduced in cancer treatment. PMID:26345296

  10. Aurora A drives early signalling and vesicle dynamics during T-cell activation

    PubMed Central

    Blas-Rus, Noelia; Bustos-Morán, Eugenio; Pérez de Castro, Ignacio; de Cárcer, Guillermo; Borroto, Aldo; Camafeita, Emilio; Jorge, Inmaculada; Vázquez, Jesús; Alarcón, Balbino; Malumbres, Marcos; Martín-Cófreces, Noa B.; Sánchez-Madrid, Francisco

    2016-01-01

    Aurora A is a serine/threonine kinase that contributes to the progression of mitosis by inducing microtubule nucleation. Here we have identified an unexpected role for Aurora A kinase in antigen-driven T-cell activation. We find that Aurora A is phosphorylated at the immunological synapse (IS) during TCR-driven cell contact. Inhibition of Aurora A with pharmacological agents or genetic deletion in human or mouse T cells severely disrupts the dynamics of microtubules and CD3ζ-bearing vesicles at the IS. The absence of Aurora A activity also impairs the activation of early signalling molecules downstream of the TCR and the expression of IL-2, CD25 and CD69. Aurora A inhibition causes delocalized clustering of Lck at the IS and decreases phosphorylation levels of tyrosine kinase Lck, thus indicating Aurora A is required for maintaining Lck active. These findings implicate Aurora A in the propagation of the TCR activation signal. PMID:27091106

  11. Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy of an undated lithograph based on an ambrotype by D.C. Pratt, C. 1857 - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

  12. 77 FR 13694 - Requested Administrative Waiver of the Coastwise Trade Laws: Vessel AURORA B; Invitation for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Maritime Administration Requested Administrative Waiver of the Coastwise Trade Laws: Vessel AURORA B... the vessel AURORA B is: Intended Commercial Use of Vessel: ``Will provide special chartering...

  13. Aurora A drives early signalling and vesicle dynamics during T-cell activation.

    PubMed

    Blas-Rus, Noelia; Bustos-Morán, Eugenio; Pérez de Castro, Ignacio; de Cárcer, Guillermo; Borroto, Aldo; Camafeita, Emilio; Jorge, Inmaculada; Vázquez, Jesús; Alarcón, Balbino; Malumbres, Marcos; Martín-Cófreces, Noa B; Sánchez-Madrid, Francisco

    2016-01-01

    Aurora A is a serine/threonine kinase that contributes to the progression of mitosis by inducing microtubule nucleation. Here we have identified an unexpected role for Aurora A kinase in antigen-driven T-cell activation. We find that Aurora A is phosphorylated at the immunological synapse (IS) during TCR-driven cell contact. Inhibition of Aurora A with pharmacological agents or genetic deletion in human or mouse T cells severely disrupts the dynamics of microtubules and CD3ζ-bearing vesicles at the IS. The absence of Aurora A activity also impairs the activation of early signalling molecules downstream of the TCR and the expression of IL-2, CD25 and CD69. Aurora A inhibition causes delocalized clustering of Lck at the IS and decreases phosphorylation levels of tyrosine kinase Lck, thus indicating Aurora A is required for maintaining Lck active. These findings implicate Aurora A in the propagation of the TCR activation signal. PMID:27091106

  14. Prediction of blue, red and green aurorae at Mars

    NASA Astrophysics Data System (ADS)

    Lilensten, J.; Bernard, D.; Barthélémy, M.; Gronoff, G.; Simon Wedlund, C.; Opitz, A.

    2015-09-01

    The upper atmosphere of Mars is a laboratory for better understanding the planetary atmosphere evolution, and is an example of the interaction of the solar wind with an unmagnetized planet that has only patches of crustal magnetic field. In that context, several space missions were launched to study the Martian environment and its aurorae, notably ESA's Mars Express discovered the first aurora-like structures, and more recently NASA's MAVEN, which is dedicated to understand the atmospheric escape. However, none of the existing missions have spectrometers in the visible spectral range for the observation of the upper atmosphere and the aurorae, but there are UV spectrometer which can be used to infer visible aurora emission. The UV aurorae on Mars have a counterpart in the visible spectral range which should be detectable under the right conditions. We discuss what are the most favorable conditions to observe these aurorae discernible with the naked eye. In this paper, we simulate the Martian aurora in the visible spectral range both with an experimental setup (the Planeterrella, which we use to measure intensity with respect to the naked eye) and with a numerical ionosphere simulation model (Trans*/Aeroplanets). We show that the electron impact on CO2 produces strong emissions at 412 nm and 434 nm, i.e., in the blue part of the visible spectrum which are due to the CO2+(A) Fox-Duffendack-Barker bands. The modeling of the electron transport at Mars shows that these blue emissions as well as the emissions of the 630 nm (red) and 557.7 nm (green) lines of atomic oxygen may be observable several times during a solar cycle during strong solar events. The absence of visible spectrometers dedicated to these observations onboard existing space missions and the location of the different Martian rovers, far from the vertically aligned crustal magnetic field lines of Mars, have prevented so far the observations of such an aurora. In the foreseeable future, two missions may

  15. A Cell Biologist’s Field Guide to Aurora Kinase Inhibitors

    PubMed Central

    de Groot, Christian O.; Hsia, Judy E.; Anzola, John V.; Motamedi, Amir; Yoon, Michelle; Wong, Yao Liang; Jenkins, David; Lee, Hyun J.; Martinez, Mallory B.; Davis, Robert L.; Gahman, Timothy C.; Desai, Arshad; Shiau, Andrew K.

    2015-01-01

    Aurora kinases are essential for cell division and are frequently misregulated in human cancers. Based on their potential as cancer therapeutics, a plethora of small molecule Aurora kinase inhibitors have been developed, with a subset having been adopted as tools in cell biology. Here, we fill a gap in the characterization of Aurora kinase inhibitors by using biochemical and cell-based assays to systematically profile a panel of 10 commercially available compounds with reported selectivity for Aurora A (MLN8054, MLN8237, MK-5108, MK-8745, Genentech Aurora Inhibitor 1), Aurora B (Hesperadin, ZM447439, AZD1152-HQPA, GSK1070916), or Aurora A/B (VX-680). We quantify the in vitro effect of each inhibitor on the activity of Aurora A alone, as well as Aurora A and Aurora B bound to fragments of their activators, TPX2 and INCENP, respectively. We also report kinome profiling results for a subset of these compounds to highlight potential off-target effects. In a cellular context, we demonstrate that immunofluorescence-based detection of LATS2 and histone H3 phospho-epitopes provides a facile and reliable means to assess potency and specificity of Aurora A versus Aurora B inhibition, and that G2 duration measured in a live imaging assay is a specific readout of Aurora A activity. Our analysis also highlights variation between HeLa, U2OS, and hTERT-RPE1 cells that impacts selective Aurora A inhibition. For Aurora B, all four tested compounds exhibit excellent selectivity and do not significantly inhibit Aurora A at effective doses. For Aurora A, MK-5108 and MK-8745 are significantly more selective than the commonly used inhibitors MLN8054 and MLN8237. A crystal structure of an Aurora A/MK-5108 complex that we determined suggests the chemical basis for this higher specificity. Taken together, our quantitative biochemical and cell-based analyses indicate that AZD1152-HQPA and MK-8745 are the best current tools for selectively inhibiting Aurora B and Aurora A, respectively

  16. Identification of Ski as a target for Aurora A kinase

    PubMed Central

    Mosquera, Jocelyn; Armisen, Ricardo; Zhao, Hong Ling; Rojas, Diego A.; Maldonado, Edio; Tapia, Julio C; Colombo, Alicia; Hayman, Michael J; Marcelain, Katherine

    2011-01-01

    Ski is a negative regulator of the transforming growth factor-β and other signalling pathways. The absence of SKI in mouse fibroblasts leads to chromosome segregation defects and genomic instability, suggesting a role for Ski during mitosis. At this stage, Ski is phosphorylated but to date little is known about the kinases involved in this process. Here, we show that Aurora A kinase is able to phosphorylate Ski in vitro. In vivo, Aurora A and Ski co-localized at the centrosomes and co-immunoprecipitated. Conversely, a C-terminal truncation mutant of Ski (SkiΔ491–728) lacking a coiled-coil domain, displayed decreased centrosomal localization. This mutant no longer co-immunoprecipitated with Aurora-A in vivo, but was still phosphorylated in vitro, indicating that the Ski-Aurora A interaction takes place at the centrosomes. These data identify Ski as a novel target of Aurora A and contribute to an understanding of the role of these proteins in the mitotic process. PMID:21600873

  17. Aurora Kinases’ Inhibitors – Rising Stars in Cancer Therapeutics?

    PubMed Central

    Dar, Altaf A; Goff, Laura W.; Majid, Shahana; Berlin, Jordan; El-Rifai, Wael

    2010-01-01

    Standard therapeutic approaches of cytotoxics and radiation in cancer are not only highly toxic, but also of limited efficacy in treatment of a significant number of cancer patients. The molecular analysis of the cancer genomes have shown a remarkable complexity and pointed to key genomic and epigenomic alterations in cancer. These discoveries are paving the way for targeted therapy approaches. However, while there are a large number of potential targets, only a few can regulate key cellular functions and intersect multiple signaling networks. The Aurora kinase family members (A, B, and C) are a collection of highly related and conserved serine/threonine kinases that fulfill these criteria, being key regulators of mitosis and multiple signaling pathways. Alterations in Aurora kinase signaling are associated with mitotic errors and have been closely linked to chromosomal aneuploidy in cancer cells. Several studies have shown amplification and/or over-expression of Aurora kinase A and B in hematologic malignancies and solid tumors. Over the past several years, Aurora kinases have become attractive targets. Several ongoing clinical trials and bench-based research are assessing the unique therapeutic potential of Aurora-based targeted therapy. PMID:20124450

  18. Preclinical validation of Aurora kinases-targeting drugs in osteosarcoma

    PubMed Central

    Tavanti, E; Sero, V; Vella, S; Fanelli, M; Michelacci, F; Landuzzi, L; Magagnoli, G; Versteeg, R; Picci, P; Hattinger, C M; Serra, M

    2013-01-01

    Background: Aurora kinases are key regulators of cell cycle and represent new promising therapeutic targets in several human tumours. Methods: Biological relevance of Aurora kinase-A and -B was assessed on osteosarcoma clinical samples and by silencing these genes with specific siRNA in three human osteosarcoma cell lines. In vitro efficacy of two Aurora kinases-targeting drugs (VX-680 and ZM447439) was evaluated on a panel of four drug-sensitive and six drug-resistant human osteosarcoma cell lines. Results: Human osteosarcoma cell lines proved to be highly sensitive to both drugs. A decreased drug sensitivity was observed in doxorubicin-resistant cell lines, most probably related to ABCB1/MDR1 overexpression. Both drugs variably induced hyperploidy and apoptosis in the majority of cell lines. VX-680 also reduced in vitro cell motility and soft-agar cloning efficiency. Drug association experiments showed that VX-680 positively interacts with all conventional drugs used in osteosarcoma chemotherapy, overcoming the cross-resistance observed in the single-drug treatments. Conclusion: Aurora kinase-A and -B represent new candidate therapeutic targets for osteosarcoma. In vitro analysis of the Aurora kinases inhibitors VX-680 and ZM447439 indicated in VX-680 a new promising drug of potential clinical usefulness in association with conventional osteosarcoma chemotherapeutic agents. PMID:24129234

  19. AURORA: The Next Generation Space Weather Sensor for NPOESS

    NASA Astrophysics Data System (ADS)

    Paxton, L.; Morrison, D.; Santo, A.; Ogorzalek, B.; Goldsten, J.; Boldt, J.; Kil, H.; Zhang, Y.; Demajistre, R.; Wolven, B.; Meng, C.

    2005-12-01

    The AURORA sensor slated for flight on the NPOESS satellites represents the culmination of over 20 years of experience at JHU/APL in the design, manufacture, flight, operation and analysis of compact, cost-effective far ultraviolet sensors for space weather data collection. The far ultraviolet covers the spectral range from about 115 to 185 nm. This region is ideal for observations of the upper atmosphere because, at these wavelengths, the lower atmosphere and Earth's surface are black. AURORA will observe the mid- and low-latitude F-region ionosphere, the auroral E-region ionosphere, the day thermosphere composition, auroral energy deposition and map ionospheric irregularities. AURORA implements the flight-proven design derived from SSUSI on the DMSP Block 5D spacecraft and GUVI on the NASA TIMED spacecraft. These instruments have provided the instrument and algorithm heritage for NPOESS/AURORA. In this talk the performance capabilities of the AURORA instrument will be summarized along with the design of the instrument and algorithms. Example products will be shown for each of the measurement regimes. We acknowldge support from DMSP and NASA and the collaboration with our science colleagues at the Aerospace Corporation (Paul Straus, Jim Hecht, Dave McKenzie, and Andy Christensen) and Computational Physics (Doug Strickland, Hal Knight, and Scott Evans) and Naval Research Laboratory (Robert Meier, Mike Picone, Stefan Thonnard, Pat Dandenault, and Andy Stefan) and our colleagues at APL (Michele Weiss, Doug Holland, Bill Wood, and Jim Eichert) among others.

  20. Update on Aurora Kinase Targeted Therapeutics in Oncology

    PubMed Central

    Green, Myke R.; Woolery, Joseph E.

    2011-01-01

    Introduction Mammalian cells contain three distinct serine/threonine protein kinases with highly conserved catalytic domains, including aurora A and B kinases that are essential regulators of mitotic entry and progression. Overexpression of aurora A and/or B kinase is associated with high proliferation rates and poor prognosis, making them ideal targets for anti-cancer therapy. Disruption of mitotic machinery is a proven anti-cancer strategy employed by multiple chemotherapeutic agents. Numerous small molecule inhibitors of the aurora kinases have been discovered and tested in vivo and in vitro, with a few currently in phase II testing. Areas covered This review provides the reader with updated results from both preclinical and human studies for each of the aurora kinase inhibitors (AKI) that are currently being investigated. The paper also covers in detail the late breaking and phase I data presented for AKIs thereby allowing the reader to compare and contrast individual and classrelated effects of AKIs. Expert opinion While the successful development and approval of an AKI for anti-cancer therapy remains unresolved, pre-clinical identification of resistant mechanisms would help design better early phase clinical trials where relevant combinations may be evaluated prior to phase II testing. The authors believe that aurora kinases are important anti-cancer targets that operate in collaboration with other oncogenes intimately involved in uncontrolled tumor proliferation and by providing a unique, targeted and complimentary anti-cancer mechanism, expand the available armamentarium against cancer. PMID:21556291

  1. Update on Aurora Kinase Targeted Therapeutics in Oncology

    PubMed Central

    Green, Myke R.; Woolery, Joseph E.

    2011-01-01

    Introduction Mammalian cells contain three distinct serine/threonine protein kinases with highly conserved catalytic domains, including aurora A and B kinases that are essential regulators of mitotic entry and progression. Overexpression of aurora A and/or B kinase is associated with high proliferation rates and poor prognosis, making them ideal targets for anti-cancer therapy. Disruption of mitotic machinery is a proven anti-cancer strategy employed by multiple chemotherapeutic agents. Numerous small molecule inhibitors of the aurora kinases have been discovered and tested in vivo and in vitro, with a few currently in phase II testing. Areas covered This review provides the reader with updated results from both preclinical and human studies for each of the aurora kinase inhibitors (AKI) that are currently being investigated. The paper also covers in detail the late breaking and phase I data presented for AKIs thereby allowing the reader to compare and contrast individual and class-related effects of AKIs. Expert opinion While the successful development and approval of an AKI for anti-cancer therapy remains unresolved, pre-clinical identification of resistant mechanisms would help design better early phase clinical trials where relevant combinations may be evaluated prior to phase II testing. The authors believe that aurora kinases are important anti-cancer targets that operate in collaboration with other oncogenes intimately involved in uncontrolled tumor proliferation and by providing a unique, targeted and complimentary anti-cancer mechanism, expand the available armamentarium against cancer. PMID:18991785

  2. Aurora Borealis, A Painting by Frederic Edwin Church

    NASA Astrophysics Data System (ADS)

    Love, J. J.

    2015-12-01

    This year marks the sesquicentennial anniversary of the end of the American Civil War. In 1865, the same year as the War's end, the great American landscape artist, Frederic Edwin Church, unveiled Aurora Borealis, a painting that depicts a fantastic, far-northern place, an auroral arch stretched across a quiet night-time sky, above dark mountains and a frozen sea. Church was born in Connecticut, lived in New York, and traveled to Labrador; he would have often seen the northern lights. Church might have also been influenced by the spectacular displays of aurora that were caused by some unusually intense magnetic storms in 1859. Aurora Borealis can certainly be interpreted in terms of 19th-century romanticism, scientific philosophy, and Arctic missions of exploration, all subjects of interest to Church. As with so many of his paintings, Church's meticulous attention to detail in Aurora Borealis reveals his deep admiration of nature. But his depiction of auroral light is a curious and possibly intentional departure from natural verisimilitude. Some art historians have suggested that Church painted Aurora Borealis as a subdued tribute to the end of the Civil War, with the drapery of auroral light forming an abstract representation of the American flag. If so, then colors of the flag have been unfurled across a cold and barren landscape, not in extravagant celebration, but in somber recognition of the reality of post-war desolation and an uncertain future.

  3. Issues in interpreting the in vivo activity of Aurora-A inhibitors

    PubMed Central

    Shagisultanova, Elena; Dunbrack, Roland L.; Golemis, Erica A.

    2014-01-01

    Introduction Based on its role as a mitotic regulatory kinase, overexpressed and associated with aneuploidy in cancer, small molecule inhibitors have been developed for Aurora-A (AURKA) kinase. In preclinical and clinical assessments, these agents have shown efficacy in inducing stable disease or therapeutic response. In optimizing the use of Aurora-A inhibitors, it is critical to have robust capacity to measure the kinase activity of Aurora-A in tumors. Areas covered we provide an overview of molecular mechanisms of mitotic and non-mitotic activation of Aurora-A kinase, and interaction of Aurora-A with its regulatory partners. Typically, Aurora-A activity is measured by use of phospho-antibodies targeting an auto-phosphorylated T288 epitope. However, recent studies have identified alternative means of Aurora-A activation control, including allosteric regulation by partners, phosphorylation on alternative activating residues (S51, S98), dephosphorylation on inhibitory sites (S342), and T288 phosphorylation by alternative kinases such as Pak enzymes. Additional work has shown that the relative abundance of Aurora-A partners can affect the activity of Aurora-A inhibitors, and that Aurora-A activation also occurs in interphase cells. Expert opinion Taken together, this work suggests the need for comprehensive analysis of Aurora-A activity and expression of Aurora-A partners in order to stratify patients for likely therapeutic response. PMID:25384454

  4. A mathematical model of Aurora B activity in prophase and metaphase.

    PubMed

    Doherty, Kevin; Meere, Martin; Piiroinen, Petri T

    2016-07-01

    Aurora B kinase is a protein that controls several processes in mitosis when it is found associated with INCENP, Survivin and Borealin in a complex known as the Chromosomal Passenger Complex. Aurora B in complex with INCENP is phosphorylated on three sites, resulting in the full activation of Aurora B. In prophase and metaphase, Aurora B is activated at centromeres, the region of chromatin linking sister chromatids, due to an autophosphorylation mechanism, and it has been hypothesised that Aurora B is activated throughout the cytoplasm due to its concentration at centromeres. In this article, we first develop a time-dependent model of Aurora B activation that does not incorporate spatial variation. This model is used to demonstrate the various qualitative behaviours that the activation of Aurora B is capable of displaying for different model parameters. Next, we develop a spatio-temporal model of Aurora B activation that includes diffusion of soluble Aurora B and binding of Aurora B to immobile centromeric binding sites. This model describes the activation of Aurora B throughout the cytoplasm due to its concentration-dependent activation at centromeres. The models demonstrate the effects that a soluble phosphatase concentration, multisite phosphorylation and diffusion have on the activation of Aurora B. PMID:27155569

  5. Aurora Borealis Experiment (ABX): A Planeterrella for Education and Outreach

    NASA Astrophysics Data System (ADS)

    McNulty, Michael; Carpe, Andy; Zwicker, Andrew

    2013-10-01

    The Planeterrella is an experiment invented by Jean Lilensten of the Laboratoire de Planetologie de Grenoble in France designed to simulate aurorae of various planets. It is done by placing two differently sized aluminum spheres in a bell jar with a pressure of approximately 75 mTorr. Each sphere has magnets inside and is electrically biased. An electrode with the opposite electrical bias is inserted into the bell jar so that the voltage between them is on the order of 300 V. A plasma is then created and an aurora is formed around the magnetic poles of the spheres or near the edge of the electrode. We have made a modified version of the planeterrella, called the Aurora Borealis Experiment (ABX), based upon Lilensten's plans. We will present the technical details of the experiment and preliminary results of its use with a variety of different audiences.

  6. Io's atmospheric response to eclipse: UV aurorae observations.

    PubMed

    Retherford, K D; Spencer, J R; Stern, S A; Saur, J; Strobel, D F; Steffl, A J; Gladstone, G R; Weaver, H A; Cheng, A F; Parker, J Wm; Slater, D C; Versteeg, M H; Davis, M W; Bagenal, F; Throop, H B; Lopes, R M C; Reuter, D C; Lunsford, A; Conard, S J; Young, L A; Moore, J M

    2007-10-12

    The New Horizons (NH) spacecraft observed Io's aurora in eclipse on four occasions during spring 2007. NH Alice ultraviolet spectroscopy and concurrent Hubble Space Telescope ultraviolet imaging in eclipse investigate the relative contribution of volcanoes to Io's atmosphere and its interaction with Jupiter's magnetosphere. Auroral brightness and morphology variations after eclipse ingress and egress reveal changes in the relative contribution of sublimation and volcanic sources to the atmosphere. Brightnesses viewed at different geometries are best explained by a dramatic difference between the dayside and nightside atmospheric density. Far-ultraviolet aurora morphology reveals the influence of plumes on Io's electrodynamic interaction with Jupiter's magnetosphere. Comparisons to detailed simulations of Io's aurora indicate that volcanoes supply 1 to 3% of the dayside atmosphere. PMID:17932289

  7. Applications to particle transport in the Earth`s aurora

    SciTech Connect

    Jasperse, J.R.

    1994-12-31

    The visual display of light called the aurora borealis occurs when energetic (1 to 100-keV) electrons, protons, and hydrogen atoms from the Earth`s magnetosphere enter the Earth`s upper atmosphere and collide with the ambient neutral particles. Two kinds of auroras occur in nature: those excited by incident electrons and those excited by incident protons and hydrogen atoms. In this paper, we consider only the latter. The proton-hydrogen aurora may be divided into two altitude regions: high altitudes ({approximately}250 to {approximately}600 km) where charge-changing collisions dominate and energy-loss collisions may be neglected and low altitudes ({approximately}100 to {approximately}250 km) where energy-loss collisions also become important and cause rapid energy degradation. The focus of this review is on the high-altitude region where the one-group approximation is valid.

  8. Combined Cancer Immunotherapy Against Aurora Kinase A.

    PubMed

    Kaštánková, Iva; Poláková, Ingrid; Dušková, Martina; Šmahel, Michal

    2016-05-01

    Aurora kinase A (AURKA) is a centrosomal protein that is overexpressed in a number of human malignancies and can contribute to tumor progression. As we used this protein as a target of DNA immunization, we increased its immunogenicity by the addition of the PADRE helper epitope and decreased its potential oncogenicity by mutagenesis of the kinase domain. For in vitro analysis of induced immune responses in mice, we identified the Aurka220-228 nonapeptide representing an H-2K epitope. As DNA vaccination against the Aurka self-antigen by a gene gun did not show any antitumor effect, we combined DNA immunization with anti-CD25 treatment that depletes mainly regulatory T cells. Whereas 1 anti-CD25 dose injected before DNA vaccination did not enhance the activation of Aurka-specific splenocytes, 3 doses administered on days of immunizations augmented about 10-fold immunity against Aurka. However, an opposite effect was found for antitumor immunity-only 1 anti-CD25 dose combined with DNA vaccination reduced tumor growth. Moreover, the administration of 3 doses of anti-CD25 antibody alone accelerated tumor growth. Analysis of tumor-infiltrating cells showed that 3 anti-CD25 doses not only efficiently depleted regulatory T cells but also activated helper T cells and CD3CD25 cells. Next, we found that blockade of the PD-1 receptor initiated 1 week after the first immunization was necessary for significant inhibition of tumor growth with therapeutic DNA vaccination against Aurka combined with depletion of CD25 cells. Our results suggest that combined cancer immunotherapy should be carefully evaluated to achieve the optimal antitumor effect. PMID:27070447

  9. Artificial aurora conjugate to a rocket-borne electron accelerator

    NASA Technical Reports Server (NTRS)

    Davis, T. N.; Wescott, E. M.; Hallinan, T. J.; Stenbaek-Nielsen, H. C.; Hess, W. N.; Trichel, M. C.; Maier, E. J. R.

    1980-01-01

    An accelerator intended to send electron beams upward along an L = 1.24 magnetic field line was flown from a rocket launched from Kauai, Hawaii, on October 15, 1972. Though the intent was to produce several hundred observable auroral streaks in the Southern Hemisphere, imaging instruments operated there aboard jet aircraft detected only a single aurora. Produced by a 0.155-A beam of energy 22.8 keV, the aurora was of expected brightness and had a diameter (210 + or - 50 m) somewhat larger than expected and an altitude (top 116 + or - 2 km; bottom 92 + or - 2 km) higher than expected.

  10. Aurora painting pays tribute to Civil War's end

    USGS Publications Warehouse

    Love, Jeffrey J.

    2015-01-01

    In 1865, the same year the war ended, the American landscape artist Frederic Edwin Church unveiledAurora Borealis (pictured above), a dramatic and mysterious painting that can be interpreted in terms of 19th century romanticism, scientific philosophy, and Arctic missions of exploration. Aurora Borealiscan also be viewed as a restrained tribute to the end of the Civil War—a moving example of how science and current events served as the muses of late romantic artists [e.g., Carr, 1994, p. 277; Avery, 2011; Harvey, 2012].

  11. Nonlinear Plasma Effects in Natural and Artificial Aurora

    SciTech Connect

    Mishin, E. V.

    2011-01-04

    This report describes common features of natural ('Enhanced') aurora and 'artificial aurora'(AA) created by electron beams injected from sounding rockets. These features cannot be explained solely by col-lisional degradation of energetic electrons, thereby pointing to collisionless plasma effects. The fundamental role in electron beam-ionosphere interactions belongs to Langmuir turbulence. Its development in the (weakly-ionized) ionosphere is significantly affected by electron-neutral collisions, so that the heating and acceleration of plasma electrons proceed more efficiently than in collisionless plasmas. As a result, a narrow layer of enhanced auroral glow/ionization is formed above the standard collisional peak.

  12. p53 negatively regulates Aurora A via both transcriptional and posttranslational regulation

    PubMed Central

    Wu, Chun-Chi; Yang, Tsung-Ying; Yu, Chang-Tze Ricky; Phan, Liem; Ivan, Cristina; Sood, Anil K.; Hsu, Shih-Lan; Lee, Mong-Hong

    2012-01-01

    p53 plays an important role in mitotic checkpoint, but what its role is remains enigmatic. Aurora A is a Ser/Thr kinase involved in correcting progression of mitosis. Here, we show that p53 is a negative regulator for Aurora A. We found that p53 deficiency leads to Aurora A elevation. Ectopic expression of p53 or DNA damage-induced expression of p53 can suppress the expression of Aurora A. Mechanistic studies show that p53 is a negative regulator for Aurora A expression through both transcriptional and posttranslational regulation. p53 knockdown in cancer cells reduces the level of p21, which, in turn, increases the activity of CDK2 followed by induction of Rb1 hyperphosphorylation and its dissociation with transcriptional factor E2F3. E2F3 can bind to Aurora A gene promoter, potentiating Aurora A gene expression and p53 deficiency, enhancing the binding of E2F3 on Aurora A promoter. Also, p53 deficiency leads to decelerating Aurora A’s turnover rate, due to the fact that p53 deficiency causes the downregulation of Fbw7α, a component of E3 ligase of Aurora A. Consistently, p53 knockdown-mediated Aurora A elevation is mitigated when Fbw7α is ectopically expressed. Thus, p53-mediated Aurora A degradation requires Fbw7α expression. Significantly, inverse correlation between p53 and Aurora A elevation is translated into the deregulation of centrosome amplification. p53 knockdown leads to high percentages of cells with abnormal amplification of centrosome. These data suggest that p53 is an important negative regulator of Aurora A, and that loss of p53 in many types of cancer could lead to abnormal elevation of Aurora A and dysregulated mitosis, which provides a growth advantage for cancer cells. PMID:22894933

  13. Chandra Probes High-Voltage Auroras on Jupiter

    NASA Astrophysics Data System (ADS)

    2005-03-01

    Scientists have obtained new insight into the unique power source for many of Jupiter's auroras, the most spectacular and active auroras in the Solar System. Extended monitoring of the giant planet with NASA's Chandra X-ray Observatory detected the presence of highly charged particles crashing into the atmosphere above its poles. X-ray spectra measured by Chandra showed that the auroral activity was produced by ions of oxygen and other elements that were stripped of most of their electrons. This implies that these particles were accelerated to high energies in a multimillion-volt environment above the planet's poles. The presence of these energetic ions indicates that the cause of many of Jupiter's auroras is different from auroras produced on Earth or Saturn. Chandra X-ray Image of Jupiter Chandra X-ray Image of Jupiter "Spacecraft have not explored the region above the poles of Jupiter, so X-ray observations provide one of the few ways to probe that environment," said Ron Elsner of the NASA Marshall Space Flight Center in Huntsville, Alabama, and lead author on a recently published paper describing these results in the Journal for Geophysical Research. "These results will help scientists to understand the mechanism for the power output from Jupiter's auroras, which are a thousand times more powerful than those on Earth." Electric voltages of about 10 million volts, and currents of 10 million amps - a hundred times greater than the most powerful lightning bolts - are required to explain the X-ray observations. These voltages would also explain the radio emission from energetic electrons observed near Jupiter by the Ulysses spacecraft. Schematic of Jupiter's Auroral Activity Production Schematic of Jupiter's Auroral Activity Production On Earth, auroras are triggered by solar storms of energetic particles, which disturb Earth's magnetic field. Gusts of particles from the Sun can also produce auroras on Jupiter, but unlike Earth, Jupiter has another way of producing

  14. Aurora-A Kinase as a Promising Therapeutic Target in Cancer

    PubMed Central

    D’Assoro, Antonino B.; Haddad, Tufia; Galanis, Evanthia

    2016-01-01

    Mammalian Aurora family of serine/threonine kinases are master regulators of mitotic progression and are frequently overexpressed in human cancers. Among the three members of the Aurora kinase family (Aurora-A, -B, and -C), Aurora-A and Aurora-B are expressed at detectable levels in somatic cells undergoing mitotic cell division. Aberrant Aurora-A kinase activity has been implicated in oncogenic transformation through the development of chromosomal instability and tumor cell heterogeneity. Recent studies also reveal a novel non-mitotic role of Aurora-A activity in promoting tumor progression through activation of epithelial–mesenchymal transition reprograming resulting in the genesis of tumor-initiating cells. Therefore, Aurora-A kinase represents an attractive target for cancer therapeutics, and the development of small molecule inhibitors of Aurora-A oncogenic activity may improve the clinical outcomes of cancer patients. In the present review, we will discuss mitotic and non-mitotic functions of Aurora-A activity in oncogenic transformation and tumor progression. We will also review the current clinical studies, evaluating small molecule inhibitors of Aurora-A activity and their efficacy in the management of cancer patients. PMID:26779440

  15. A Microtubule-Independent Role for Centrosomes and Aurora A in Nuclear Envelope Breakdown

    PubMed Central

    Portier, Nathan; Audhya, Anjon; Maddox, Paul S.; Green, Rebecca A.; Dammermann, Alexander; Desai, Arshad; Oegema, Karen

    2010-01-01

    SUMMARY Aurora A kinase localizes to centrosomes and is required for centrosome maturation and spindle assembly. Here, we describe a microtubule-independent role for aurora A and centrosomes in nuclear envelope breakdown (NEBD) during the first mitotic division of the C. elegans embryo. Aurora A depletion does not alter the onset or kinetics of chromosome condensation, but dramatically lengthens the interval between the completion of condensation and NEBD. Inhibiting centrosome assembly by other means also lengthens this interval, albeit to a lesser extent than aurora A depletion. By contrast, centrosomally-nucleated microtubules and the nuclear envelope-associated motor dynein are not required for timely NEBD. These results indicate that mitotic centrosomes generate a diffusible factor, which we propose is activated aurora A, that promotes NEBD. A positive feedback loop, in which an aurora A-dependent increase in centrosome size promotes aurora A activation, may temporally couple centrosome maturation to NEBD during mitotic entry. PMID:17419991

  16. Discovery of a Selective Aurora A Kinase Inhibitor by Virtual Screening.

    PubMed

    Kilchmann, Falco; Marcaida, Maria J; Kotak, Sachin; Schick, Thomas; Boss, Silvan D; Awale, Mahendra; Gönczy, Pierre; Reymond, Jean-Louis

    2016-08-11

    Here we report the discovery of a selective inhibitor of Aurora A, a key regulator of cell division and potential anticancer target. We used the atom category extended ligand overlap score (xLOS), a 3D ligand-based virtual screening method recently developed in our group, to select 437 shape and pharmacophore analogs of reference kinase inhibitors. Biochemical screening uncovered two inhibitor series with scaffolds unprecedented among kinase inhibitors. One of them was successfully optimized by structure-based design to a potent Aurora A inhibitor (IC50 = 2 nM) with very high kinome selectivity for Aurora kinases. This inhibitor locks Aurora A in an inactive conformation and disrupts binding to its activator protein TPX2, which impairs Aurora A localization at the mitotic spindle and induces cell division defects. This phenotype can be rescued by inhibitor-resistant Aurora A mutants. The inhibitor furthermore does not induce Aurora B specific effects in cells. PMID:27391133

  17. A Pentacyclic Aurora Kinase Inhibitor (AKI-001) With High in Vivo Potency And Oral Bioavailability

    SciTech Connect

    Rawson, T.E.; Ruth, M.; Blackwood, E.; Burdick, D.; Corson, L.; Dotson, J.; Drummond, J.; Fields, C.; Georges, G.J.; Goller, B.; Halladay, J.; Hunsaker, T.; Kleinheinz, T.; Krell, H.-W.; Li, J.; Liang, J.; Limberg, A.; McNutt, A.; Moffat, J.; Phillips, G.; Ran, Y.

    2009-05-21

    Aurora kinase inhibitors have attracted a great deal of interest as a new class of antimitotic agents. We report a novel class of Aurora inhibitors based on a pentacyclic scaffold. A prototype pentacyclic inhibitor 32 (AKI-001) derived from two early lead structures improves upon the best properties of each parent and compares favorably to a previously reported Aurora inhibitor, 39 (VX-680). The inhibitor exhibits low nanomolar potency against both Aurora A and Aurora B enzymes, excellent cellular potency (IC{sub 50} < 100 nM), and good oral bioavailability. Phenotypic cellular assays show that both Aurora A and Aurora B are inhibited at inhibitor concentrations sufficient to block proliferation. Importantly, the cellular activity translates to potent inhibition of tumor growth in vivo. An oral dose of 5 mg/kg QD is well tolerated and results in near stasis (92% TGI) in an HCT116 mouse xenograft model.

  18. The grand aurorae borealis seen in Colombia in 1859

    NASA Astrophysics Data System (ADS)

    Cárdenas, Freddy Moreno; Sánchez, Sergio Cristancho; Domínguez, Santiago Vargas

    2016-01-01

    On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama's 9°N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia allowed the identification of a narrative from Montería, Colombia (8° 45‧N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling glares, and the appearance of an immense S-like shape in the sky. The very low latitude of the geomagnetic north pole in 1859, the lowest value in over half a millennia, is proposed to have allowed the observations of auroral events at locations closer to the equator, and supports the historical description found in Colombia. The finding of such chronicle represents one of the most complete descriptions of low-latitude sightings of aurorae caused by the Carrington Event.

  19. HPV16 E6 upregulates Aurora A expression

    PubMed Central

    Guo, Yi; Ma, Jiaming; Zheng, Yahong; Li, Lu; Gui, Xiaowei; Wang, Qian; Meng, Xiangkai; Shang, Hong

    2016-01-01

    Overexpression of Aurora A kinase occurs in certain types of cancer, and therefore results in chromosome instability and phosphorylation-mediated ubiquitylation and degradation of p53 for tumorigenesis. The high-risk subtype human papillomavirus (HPV)16 early oncoprotein E6 is a major contributor inducing host cell immortalization and transformation through interaction with a number of cellular factors. In the present study, co-immunoprecipitation, glutathione S-transferase pull-down and immunostaining were used to show that HPV16 E6 and Aurora A bind to each other in vivo and in vitro. Western blotting and reverse transcription-polymerase chain reaction were used to reveal that HPV16 E6 inhibited cell apoptosis by stabilizing Aurora A expression. The present study may report a new mechanism for the involvement of HPV16 E6 in carcinogenesis, as HPV16 E6 elevates Aurora A expression and the latter may be a common target for oncogenic viruses that result in cell carcinogenesis. PMID:27446442

  20. Functions of Aurora kinase C in meiosis and cancer

    PubMed Central

    Quartuccio, Suzanne M.; Schindler, Karen

    2015-01-01

    The mammalian genome encodes three Aurora kinase protein family members: A, B, and C. While Aurora kinase A (AURKA) and B (AURKB) are found in cells throughout the body, significant protein levels of Aurora kinase C (AURKC) are limited to cells that undergo meiosis (sperm and oocyte). Despite its discovery nearly 20 years ago, we know little about the function of AURKC compared to that of the other 2 Aurora kinases. This lack of understanding can be attributed to the high sequence homology between AURKB and AURKC preventing the use of standard approaches to understand non-overlapping and meiosis I (MI)-specific functions of the two kinases. Recent evidence has revealed distinct functions of AURKC in meiosis and may aid in our understanding of why chromosome segregation during MI often goes awry in oocytes. Many cancers aberrantly express AURKC, but because we do not fully understand AURKC function in its normal cellular context, it is difficult to predict the biological significance of this expression on the disease. Here, we consolidate and update what is known about AURKC signaling in meiotic cells to better understand why it has oncogenic potential. PMID:26347867

  1. Traditional Knowledge: An Implementation Workplan for Aurora College.

    ERIC Educational Resources Information Center

    Aurora Coll., Fort Smith (Northwest Territories).

    Prepared as part of an effort to make Aurora College, in the Northwest Territories, Canada, more responsive to the Native American communities that form its primary student base, this plan outline strategies for infusing traditional knowledge into the college's day-to-day operations. Following introductory sections describing traditional knowledge…

  2. Aurora City Schools Kindergarten Math Readiness Course of Study.

    ERIC Educational Resources Information Center

    Aurora City Schools, OH.

    The program goals and objectives for Kindergarten mathematics readiness in Aurora City Schools are listed and described. Consideration of Kindergarten Philosophy, the diverse population of students, the organizational design of adopted textbooks, child development and learning styles, are all assessed in establishing scope and sequence. The…

  3. Identification and dynamics of two classes of aurora-like kinases in Arabidopsis and other plants.

    PubMed

    Demidov, Dmitri; Van Damme, Daniël; Geelen, Danny; Blattner, Frank R; Houben, Andreas

    2005-03-01

    Aurora-like kinases play key roles in chromosome segregation and cytokinesis in yeast, plant, and animal systems. Here, we characterize three Arabidopsis thaliana protein kinases, designated AtAurora1, AtAurora2, and AtAurora3, which share high amino acid identities with the Ser/Thr kinase domain of yeast Ipl1 and animal Auroras. Structure and expression of AtAurora1 and AtAurora2 suggest that these genes arose by a recent gene duplication, whereas the diversification of plant alpha and beta Aurora kinases predates the origin of land plants. The transcripts and proteins of all three kinases are most abundant in tissues containing dividing cells. Intracellular localization of green fluorescent protein-tagged AtAuroras revealed an AtAurora-type specific association mainly with dynamic mitotic structures, such as microtubule spindles and centromeres, and with the emerging cell plate of dividing tobacco (Nicotiana tabacum) BY-2 cells. Immunolabeling using AtAurora antibodies yielded specific signals at the centromeres that are coincident with histone H3 that is phosphorylated at Ser position10 during mitosis. An in vitro kinase assay demonstrated that AtAurora1 preferentially phosphorylates histone H3 at Ser 10 but not at Ser 28 or Thr 3, 11, and 32. The phylogenetic analysis of available Aurora sequences from different eukaryotic origins suggests that, although a plant Aurora gene has been duplicated early in the evolution of plants, the paralogs nevertheless maintained a role in cell cycle-related signal transduction pathways. PMID:15722465

  4. Solar wind signatures in the dayside aurora. (Invited)

    NASA Astrophysics Data System (ADS)

    Mende, S. B.; Frey, H. U.

    2013-12-01

    The THEMIS satellite configuration allows monitoring the solar wind directly in front of the magnetosphere thereby removing ambiguities due to long propagation delays from distant satellites. This situation provides an unprecedented opportunity to monitor the dayside magnetospheric boundary by THEMIS while observing the magnetically conjugate auroras at South Pole and at other Antarctic stations of the US Automatic Geophysical Observatories (AGO) chain. In the dayside magnetosphere field line mapping is expected to be relatively accurate because the field is relatively strong and the distance to the magnetopause is relatively short. Mapping the location of THEMIS crossings of the magnetopause to the aurora shows that cusp auroras tend to occur on open field lines. In most cases the THEMIS satellites show multiple crossings of the magnetopause due to the wavelike radial motion of the magnetopause. These motions are likely to be spontaneous resonances of the field because it was not possible to correlate these motions with latitude movements of the dayside aurora at the magnetic foot point or with variations in pressure or magnetic field of the solar wind immediately in front of the magnetosphere. Persistently occurring dayside transients in the aurora are Pole-ward Moving Auroral Forms (PMAF-s) which occur regularly regardless of the direction of the IMF Bz component. These features generally dissipate quickly within the all-sky imager FOV but there are examples when faint emissions persist while traveling pole-ward and across the entire FOV indicating anti-sunward flow in the polar cap. The movement of polar patches seen inside the polar cap also shows this anti-sunward flow. In some cases the timing and appearance of the patches near the night-side auroral boundary and the observation of subsequent pole-ward substorm surge are consistent with 'substorm triggering' through polar patch associated Polar Boundary Intensifications (PBI-s) and subsequent substorm onsets.

  5. Elevated Aurora B expression contributes to chemoresistance and poor prognosis in breast cancer.

    PubMed

    Zhang, Yiqian; Jiang, Chunling; Li, Huilan; Lv, Feng; Li, Xiaoyan; Qian, Xiaolong; Fu, Li; Xu, Bo; Guo, Xiaojing

    2015-01-01

    Aurora-B is a major kinase responsible for appropriate mitotic progression. Elevated expression of Aurora-B has been frequently associated with several types of cancer, including breast cancer. However, it is not clear whether the alteration contributes to tumor responses to therapies and prognosis. In this study, we conducted immunohistochemistry using antibodies against Aurora-B, S1981p-ATM, Ki67, and p53 in paraffin-embedded tumor tissues from 312 invasive breast cancer patients. The correlation between disease-free-survival (DFS) and Aurora-B expression was analyzed using the Kaplan-Meier method and log-rank test. A Cox proportional hazards regression analysis was used to determine whether Aurora-B was an independent prognostic factor for breast cancer. We found that Aurora-B expression was correlated with the proliferation index (P < 0.001) and p53 expression (P = 0.014) in breast cancer tissues. Further we found that Aurora-B expression was associated with lymph node metastasis (P = 0.002) and histological grade (P = 0.001). Multivariate analyses indicated that elevated Aurora-B expression predicted a poor survival. In a subgroup of patients that received neoadjuvant chemotherapy, we found that elevated Aurora-B contributed to chemoresistance (P = 0.011). In conclusion, elevated Aurora-B expression in breast cancer patients contributes to chemoresistance and predicts poor prognosis. PMID:25755770

  6. IQGAP1 interacts with Aurora-A and enhances its stability and its role in cancer

    SciTech Connect

    Yin, Ning; Shi, Ji; Wang, Dapeng; Tong, Tong; Wang, Mingrong; Fan, Feiyue; Zhan, Qimin

    2012-04-27

    Highlights: Black-Right-Pointing-Pointer IQGAP1 interacts with Aurora-A through its RGCt domain. Black-Right-Pointing-Pointer Overexpression of IQGAP1 prevents ubiquitination of Aurora-A. Black-Right-Pointing-Pointer Overexpression of IQGAP1 enhances the protein stability of Aurora-A. Black-Right-Pointing-Pointer Overexpression of IQGAP1 promotes the kinase activity of Aurora-A. -- Abstract: IQGAP1, a ubiquitously expressed scaffold protein, has been identified in a wide range of organisms. It participates in multiple aspects of cellular events by binding to and regulating numerous interacting proteins. In our present study, we identified a new IQGAP1 binding protein named Aurora-A which is an oncogenic protein and overexpressed in various types of human tumors. In vitro analysis with GST-Aurora-A fusion proteins showed a physical interaction between Aurora-A and IQGAP1. Moreover, the binding also occurred in HeLa cells as endogenous Aurora-A co-immunoprecipitated with IQGAP1 from the cell lysates. Overexpression of IQGAP1 resulted in an elevation of both expression and activity of Aurora-A kinase. Endogenous IQGAP1 knockdown by siRNA promoted Aurora-A degradation whereas IQGAP1 overexpression enhanced the stability of Aurora-A. Additionally, we documented that the IQGAP1-induced cell proliferation was suppressed by knocking down Aurora-A expression. Taken together, our results showed an unidentified relationship between Aurora-A and IQGAP1, and provided a new insight into the molecular mechanism by which IQGAP1 played a regulatory role in cancer.

  7. Preclinical testing of selective Aurora kinase inhibitors on a medullary thyroid carcinoma-derived cell line.

    PubMed

    Tuccilli, Chiara; Baldini, Enke; Prinzi, Natalie; Morrone, Stefania; Sorrenti, Salvatore; Filippini, Angelo; Catania, Antonio; Alessandrini, Stefania; Rendina, Roberta; Coccaro, Carmela; D'Armiento, Massimino; Ulisse, Salvatore

    2016-05-01

    Deregulated expression of the Aurora kinases (Aurora-A, B, and C) is thought to be involved in cell malignant transformation and genomic instability in several cancer types. Over the last decade, a number of small-molecule inhibitors of Aurora kinases have been developed, which have proved to efficiently restrain malignant cell growth and tumorigenicity. Regarding medullary thyroid carcinoma (MTC), we previously showed the efficacy of a pan-Aurora kinase inhibitor (MK-0457) in impairing growth and survival of the MTC-derived cell line TT. In the present study, we sought to establish if one of the Aurora kinases might represent a preferential target for MTC therapy. The effects of selective inhibitors of Aurora-A (MLN8237) and Aurora-B (AZD1152) were analyzed on TT cell proliferation, apoptosis, cell cycle, and ploidy. The two inhibitors reduced TT cell proliferation in a time- and dose-dependent manner, with IC50 of 19.0 ± 2.4 nM for MLN8237 and 401.6 ± 44.1 nM for AZD1152. Immunofluorescence experiments confirmed that AZD1152 inhibited phosphorylation of histone H3 (Ser10) by Aurora-B, while it did not affect Aurora-A autophosphorylation. MLN8237 inhibited Aurora-A autophosphorylation as expected, but at concentrations required to achieve the maximum antiproliferative effects it also abolished H3 (Ser10) phosphorylation. Cytofluorimetry experiments showed that both inhibitors induced accumulation of cells in G2/M phase and increased the subG0/G1 fraction and polyploidy. Finally, both inhibitors triggered apoptosis. We demonstrated that inhibition of either Aurora-A or Aurora-B has antiproliferative effects on TT cells, and thus it would be worthwhile to further investigate the therapeutical potential of Aurora kinase inhibitors in MTC treatment. PMID:26215279

  8. Microtubules Accelerate the Kinase Activity of Aurora-B by a Reduction in Dimensionality

    PubMed Central

    Noujaim, Michael; Bechstedt, Susanne; Wieczorek, Michal; Brouhard, Gary J.

    2014-01-01

    Aurora-B is the kinase subunit of the Chromosome Passenger Complex (CPC), a key regulator of mitotic progression that corrects improper kinetochore attachments and establishes the spindle midzone. Recent work has demonstrated that the CPC is a microtubule-associated protein complex and that microtubules are able to activate the CPC by contributing to Aurora-B auto-phosphorylation in trans. Aurora-B activation is thought to occur when the local concentration of Aurora-B is high, as occurs when Aurora-B is enriched at centromeres. It is not clear, however, whether distributed binding to large structures such as microtubules would increase the local concentration of Aurora-B. Here we show that microtubules accelerate the kinase activity of Aurora-B by a “reduction in dimensionality.” We find that microtubules increase the kinase activity of Aurora-B toward microtubule-associated substrates while reducing the phosphorylation levels of substrates not associated to microtubules. Using the single molecule assay for microtubule-associated proteins, we show that a minimal CPC construct binds to microtubules and diffuses in a one-dimensional (1D) random walk. The binding of Aurora-B to microtubules is salt-dependent and requires the C-terminal tails of tubulin, indicating that the interaction is electrostatic. We show that the rate of Aurora-B auto-activation is faster with increasing concentrations of microtubules. Finally, we demonstrate that microtubules lose their ability to stimulate Aurora-B when their C-terminal tails are removed by proteolysis. We propose a model in which microtubules act as scaffolds for the enzymatic activity of Aurora-B. The scaffolding activity of microtubules enables rapid Aurora-B activation and efficient phosphorylation of microtubule-associated substrates. PMID:24498282

  9. Mitotic Phosphorylation of Histone H3: Spatio-Temporal Regulation by Mammalian Aurora Kinases

    PubMed Central

    Crosio, Claudia; Fimia, Gian Maria; Loury, Romain; Kimura, Masashi; Okano, Yukio; Zhou, Hongyi; Sen, Subrata; Allis, C. David; Sassone-Corsi, Paolo

    2002-01-01

    Phosphorylation at a highly conserved serine residue (Ser-10) in the histone H3 tail is considered to be a crucial event for the onset of mitosis. This modification appears early in the G2 phase within pericentromeric heterochromatin and spreads in an ordered fashion coincident with mitotic chromosome condensation. Mutation of Ser-10 is essential in Tetrahymena, since it results in abnormal chromosome segregation and extensive chromosome loss during mitosis and meiosis, establishing a strong link between signaling and chromosome dynamics. Although mitotic H3 phosphorylation has been long recognized, the transduction routes and the identity of the protein kinases involved have been elusive. Here we show that the expression of Aurora-A and Aurora-B, two kinases of the Aurora/AIK family, is tightly coordinated with H3 phosphorylation during the G2/M transition. During the G2 phase, the Aurora-A kinase is coexpressed while the Aurora-B kinase colocalizes with phosphorylated histone H3. At prophase and metaphase, Aurora-A is highly localized in the centrosomic region and in the spindle poles while Aurora-B is present in the centromeric region concurrent with H3 phosphorylation, to then translocate by cytokinesis to the midbody region. Both Aurora-A and Aurora-B proteins physically interact with the H3 tail and efficiently phosphorylate Ser10 both in vitro and in vivo, even if Aurora-A appears to be a better H3 kinase than Aurora-B. Since Aurora-A and Aurora-B are known to be overexpressed in a variety of human cancers, our findings provide an attractive link between cell transformation, chromatin modifications and a specific kinase system. PMID:11784863

  10. The Uranian aurora and its relationship to the magnetosphere

    NASA Astrophysics Data System (ADS)

    Herbert, F.; Sandel, B. R.

    1994-03-01

    About 32 h of Voyager Ultraviolet Spectrometer (UVS) observations of Uranus H2 band airglow emission (875 less than or equal to lambda less than or equal to 1115 A) have been analyzed using the singular value decomposition (SVD) approach to inversion, producing an intensity map showing aurora at both magnetic poles. An H Lyman alpha aurora may also be present but is difficult to separate from scattered solar and local interstellar medium components. SVD analysis of variance shows that the intensity estimate is significantly larger than the error estimate over both Uranographic poles and part of the equatorial region, fortuitously including both magnetic polar regions. The Goddard Space Flight Center Q3 magnetic field model correctly predicts that the aurora should be larger in area and emit more power at the weaker N magnetic pole than at the stronger S magnetic pole. However, the auroral emissions are quite localized in magnetic longitude and so do not form complete auroral ovals. The brightest auroral emission at each magnetic pole is confined to a range of approximately 90 deg of magnetic longitude centered on the magnetotail direction, at moderate magnetic L parameter (5 less than or equal to L less than or equal to 10), but some emission at each pole is distributed over a range of more than 180 deg of longitude. The magnetic longitudes of the aurora are completely inconsistent with the 'windshield wiper' effect for either ions or electrons, indicating that some other effect, such as rapid depletion of the population of precipitating particles of highly localized strong pitch-angle diffusion, may be acting to localize emission. The low apparent L of the precipitating particles indicates that their energies may be less than or equal to 10 keV. Hence magnetospheric convection is likely to be important, and thus particles exciting the aurora may not remain on constant L shells. The precipitating particles may be a relatively low-energy population at high L that is

  11. Mitotic activation of the kinase Aurora-A requires its binding partner Bora.

    PubMed

    Hutterer, Andrea; Berdnik, Daniela; Wirtz-Peitz, Frederik; Zigman, Mihaela; Schleiffer, Alexander; Knoblich, Juergen A

    2006-08-01

    The protein kinase Aurora-A is required for centrosome maturation, spindle assembly, and asymmetric protein localization during mitosis. Here, we describe the identification of Bora, a conserved protein that is required for the activation of Aurora-A at the onset of mitosis. In the Drosophila peripheral nervous system, bora mutants have defects during asymmetric cell division identical to those observed in aurora-A. Furthermore, overexpression of bora can rescue defects caused by mutations in aurora-A. Bora is conserved in vertebrates, and both Drosophila and human Bora can bind to Aurora-A and activate the kinase in vitro. In interphase cells, Bora is a nuclear protein, but upon entry into mitosis, Bora is excluded from the nucleus and translocates into the cytoplasm in a Cdc2-dependent manner. We propose a model in which activation of Cdc2 initiates the release of Bora into the cytoplasm where it can bind and activate Aurora-A. PMID:16890155

  12. Aurora A’s Functions During Mitotic Exit: The Guess Who Game

    PubMed Central

    Reboutier, David; Benaud, Christelle; Prigent, Claude

    2015-01-01

    Until recently, the knowledge of Aurora A kinase functions during mitosis was limited to pre-metaphase events, particularly centrosome maturation, G2/M transition, and mitotic spindle assembly. However, an involvement of Aurora A in post-metaphase events was also suspected, but not clearly demonstrated due to the technical difficulty to perform the appropriate experiments. Recent developments of both an analog-specific version of Aurora A and small molecule inhibitors have led to the first demonstration that Aurora A is required for the early steps of cytokinesis. As in pre-metaphase, Aurora A plays diverse functions during anaphase, essentially participating in astral microtubules dynamics and central spindle assembly and functioning. The present review describes the experimental systems used to decipher new functions of Aurora A during late mitosis and situate these functions into the context of cytokinesis mechanisms. PMID:26734572

  13. Aurorasaurus: A citizen science platform for viewing and reporting the aurora

    NASA Astrophysics Data System (ADS)

    MacDonald, E. A.; Case, N. A.; Clayton, J. H.; Hall, M. K.; Heavner, M.; Lalone, N.; Patel, K. G.; Tapia, A.

    2015-09-01

    A new, citizen science-based, aurora observing and reporting platform has been developed with the primary aim of collecting auroral observations made by the general public to further improve the modeling of the aurora. In addition, the real-time ability of this platform facilitates the combination of citizen science observations with auroral oval models to improve auroral visibility nowcasting. Aurorasaurus provides easily understandable aurora information, basic gamification, and real-time location-based notification of verified aurora activity to engage citizen scientists. The Aurorasaurus project is one of only a handful of space weather citizen science projects and can provide useful results for the space weather and citizen science communities. Early results are promising with over 2000 registered users submitting over 1000 aurora observations and verifying over 1700 aurora sightings posted on Twitter.

  14. Red Aurora as Seen From the International Space Station (ISS)

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Auroras are caused when high-energy electrons pour down from the Earth's magnetosphere and collide with atoms. Red aurora, as captured here by a still digital camera aboard the International Space Station (ISS), occurs from 200 km to as high as 500 km altitude and is caused by the emission of 6300 Angstrom wavelength light from oxygen atoms. The light is emitted when the atoms return to their original unexcited state. The white spot in the image is from a light on inside of the ISS that is reflected off the inside of the window. The pale blue arch on the left side of the frame is sunlight reflecting off the atmospheric limb of the Earth. At times of peaks in solar activity, there are more geomagnetic storms and this increases the auroral activity viewed on Earth and by astronauts from orbit.

  15. Aurora-A regulates MCRS1 function during mitosis

    PubMed Central

    Meunier, Sylvain; Timón, Krystal; Vernos, Isabelle

    2016-01-01

    ABSTRACT The mitotic spindle is made of microtubules (MTs) nucleated through different pathways involving the centrosomes, the chromosomes or the walls of pre-existing MTs. MCRS1 is a RanGTP target that specifically associates with the chromosome-driven MTs protecting them from MT depolymerases. MCRS1 is also needed for the control of kinetochore fiber (K-fiber) MT minus-ends dynamics in metaphase. Here, we investigated the regulation of MCRS1 activity in M-phase. We show that MCRS1 is phosphorylated by the Aurora-A kinase in mitosis on Ser35/36. Although this phosphorylation has no role on MCRS1 localization to chromosomal MTs and K-fiber minus-ends, we show that it regulates MCRS1 activity in mitosis. We conclude that Aurora-A activity is particularly important in the tuning of K-fiber minus-ends dynamics in mitosis. PMID:27192185

  16. Rapid ray motions in barium plasma clouds and auroras

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Hallinan, T. J.; Stenbaek-Nielsen, H. C.; Swift, D. W.; Wallis, D. D.

    1993-01-01

    On two evenings in 1968, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly through three different Ba(+) clouds over Andoya, Norway. Similar effects were observed in Ba(+) clouds released from rockets launched from Poker Flat, Alaska, on March 21, 1973 and on March 22, 1980. On these occasions, auroras on or near the Ba(+) L shell also exhibited active rapid ray motions, which prompts the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba(+) clouds would lead to a better understanding of the physics of auroral ray motions and the auroral atmosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. The observations provide strong evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions.

  17. Pulsating aurora induced by upper atmospheric barium releases

    NASA Technical Reports Server (NTRS)

    Deehr, C.; Romick, G.

    1977-01-01

    The paper reports the apparent generation of pulsating aurora by explosive releases of barium vapor near 250 km altitude. This effect occurred only when the explosions were in the path of precipitating electrons associated with the visible aurora. Each explosive charge was a standard 1.5 kg thermite mixture of Ba and CuO with an excess of Ba metal which was vaporized and dispersed by the thermite explosion. Traces of Sr, Na, and Li were added to some of the charges, and monitoring was achieved by ground-based spectrophotometric observations. On March 28, 1976, an increase in emission at 5577 A and at 4278 A was observed in association with the first two bursts, these emissions pulsating with roughly a 10 sec period for approximately 60 to 100 sec after the burst.

  18. MLN8054 and Alisertib (MLN8237): Discovery of Selective Oral Aurora A Inhibitors

    PubMed Central

    2015-01-01

    The Aurora kinases are essential for cell mitosis, and the dysregulation of Aurora A and B have been linked to the etiology of human cancers. Investigational agents MLN8054 (8) and alisertib (MLN8237, 10) have been identified as high affinity, selective, orally bioavailable inhibitors of Aurora A that have advanced into human clinical trials. Alisertib (10) is currently being evaluated in multiple Phase II and III clinical trials in hematological malignancies and solid tumors. PMID:26101564

  19. MLN8054 and Alisertib (MLN8237): Discovery of Selective Oral Aurora A Inhibitors.

    PubMed

    Sells, Todd B; Chau, Ryan; Ecsedy, Jeffrey A; Gershman, Rachel E; Hoar, Kara; Huck, Jessica; Janowick, David A; Kadambi, Vivek J; LeRoy, Patrick J; Stirling, Matthew; Stroud, Stephen G; Vos, Tricia J; Weatherhead, Gabriel S; Wysong, Deborah R; Zhang, Mengkun; Balani, Suresh K; Bolen, Joseph B; Manfredi, Mark G; Claiborne, Christopher F

    2015-06-11

    The Aurora kinases are essential for cell mitosis, and the dysregulation of Aurora A and B have been linked to the etiology of human cancers. Investigational agents MLN8054 (8) and alisertib (MLN8237, 10) have been identified as high affinity, selective, orally bioavailable inhibitors of Aurora A that have advanced into human clinical trials. Alisertib (10) is currently being evaluated in multiple Phase II and III clinical trials in hematological malignancies and solid tumors. PMID:26101564

  20. Aurora B is regulated by acetylation/deacetylation during mitosis in prostate cancer cells

    PubMed Central

    Fadri-Moskwik, Maria; Weiderhold, Kimberly N.; Deeraksa, Arpaporn; Chuang, Carol; Pan, Jing; Lin, Sue-Hwa; Yu-Lee, Li-Yuan

    2012-01-01

    Protein acetylation has been implicated in playing an important role during mitotic progression. Aurora B kinase is known to play a critical role in mitosis. However, whether Aurora B is regulated by acetylation is not known. Using IP with an anti-acetyl lysine antibody, we identified Aurora B as an acetylated protein in PC3 prostate cancer cells. Knockdown of HDAC3 or inhibiting HDAC3 deacetylase activity led to a significant increase (P<0.01 and P<0.05, respectively) in Aurora B acetylation as compared to siLuc or vehicle-treated controls. Increased Aurora B acetylation is correlated with a 30% reduction in Aurora B kinase activity in vitro and resulted in significant defects in Aurora B-dependent mitotic processes, including kinetochore-microtubule attachment and chromosome congression. Furthermore, Aurora B transiently interacts with HDAC3 at the kinetochore-microtubule interface of congressing chromosomes during prometaphase. This window of interaction corresponded with a transient but significant reduction (P=0.02) in Aurora B acetylation during early mitosis. Together, these results indicate that Aurora B is more active in its deacetylated state and further suggest a new mechanism by which dynamic acetylation/deacetylation acts as a rheostat to fine-tune Aurora B activity during mitotic progression.—Fadri-Moskwik, M., Weiderhold, K. N., Deeraksa, A., Chuang, C., Pan, J., Lin, S.-H., Yu-Lee, L.-Y. Aurora B is regulated by acetylation/deacetylation during mitosis in prostate cancer cells. PMID:22751009

  1. Omega band pulsating auroras observed onboard THEMIS spacecraft and on the ground

    NASA Astrophysics Data System (ADS)

    Sato, Natsuo; Kadokura, Akira; Tanaka, Yoshimasa; Nishiyama, Takanori; Hori, Tomoaki; Yukimatu, Akira Sessai

    2015-07-01

    We examined a fortuitous case of an omega band pulsating aurora observed simultaneously on the ground at Sanikiluaq in Canada and onboard the Time History of Events and Macroscale Interactions during Substorm (THEMIS) spacecraft on 1 March 2011. We observed almost the entire process of the generation of the omega band aurora from the initial growth to the declining through expansion period. The omega band aurora grew from a faint seed, not via distortion of a preexisting east-west band aurora. The size scale of the omega band aurora during the maximum period was ~500 km in the north-south direction and ~200 km in the east-west direction. The mesoscale omega band aurora consisted of more than 15 patches of complex-shaped small-scale auroras. Each patch contained an intense pulsating aurora with a recurrent period of ~9-12 s and a poleward moving form. The footprints of the THEMIS D and THEMIS E spacecraft crossed the poleward part of the omega band aurora. THEMIS D observed significant signatures in the electromagnetic fields and particles associated with the time at which the spacecraft crossed the omega band aurora. In particular, it was found that the Y and Z components of the DC electric field intensity, especially the Z component, modulated with almost the same period as that of the optical pulsating auroras. The electrostatic low-frequency waves of less than 30 Hz showed quasiperiodic intensity variations similar to those of the DC electric field. These observations suggest that DC electric field variation and low-frequency electrostatic waves may play important roles in the driving mechanism of omega band pulsating auroras.

  2. Differential expression of aurora-A kinase in T-cell lymphomas

    PubMed Central

    Kanagal-Shamanna, Rashmi; Lehman, Norman L; O’Donnell, James P; Lim, Megan S; Schultz, Daniel S; Chitale, Dhananjay A; Bueso-Ramos, Carlos E; Medeiros, L Jeffrey; Inamdar, Kedar V

    2016-01-01

    Aurora-A is a mitotic kinase implicated in oncogenesis and is known to be overexpressed in B-cell lymphomas and plasma cell myeloma. The expression of Aurora-A kinase (henceforth referred to as Aurora-A) in T-cell lymphomas is not well characterized. In this study, we assessed Aurora-A expression by immunohistochemical analysis in 100 lymphomas encompassing a variety of T-cell lymphomas as categorized in the World Health Organization classification. Aurora-A expression was highest in anaplastic large-cell lymphomas and variably expressed in other types of T-cell lymphomas. In addition, the pattern of Aurora-A expression was predominantly cytoplasmic in ALK-positive anaplastic large-cell lymphoma and was nuclear in ALK-negative anaplastic large-cell lymphoma and other T-cell lymphomas, suggesting altered biochemical mechanisms of Aurora-A nuclear transport in ALK-positive anaplastic large-cell lymphoma. Reverse transcriptase-PCR analysis showed that Aurora-A is more highly expressed in ALK-positive anaplastic large-cell lymphoma than in ALK-negative anaplastic large-cell lymphoma, and is relatively lower in peripheral T-cell lymphomas. Using western blot analysis and the DEL cell line (derived from ALK-positive anaplastic large-cell lymphoma), we showed that Aurora-A expression is decreased after treatment with either MYC or MEK inhibitors, consistent with the MYC and MAP kinase signaling pathways being involved in driving Aurora-A expression; the greatest decrease was observed after MYC inhibition. These findings provide insights into the possible importance of Aurora-A overexpression in anaplastic large-cell lymphoma pathogenesis, and also suggest that Aurora-A inhibition could be a potential therapeutic approach for patients with anaplastic large-cell lymphoma. PMID:23411487

  3. Red-Line (630nm) Pulsating Auroras And Their Possible Magnetospheric Driver

    NASA Astrophysics Data System (ADS)

    Liang, J.; Donovan, E.; Zhang, X.; Spanswick, E.; Gillies, M.; Jackel, B. J.

    2015-12-01

    Pulsating auroras are usually known to be led by the precipitation of energetic electrons from the central plasma sheet, and are thus often displayed in blue-line and/or green-line auroral emission lines. In this study we report the observations of 630nm oxygen red-line auroras by REGO imager, and explore their possible underlying mechanisms. Upon inspecting the temporal/spatial pattern of the red-line pulsating auroras and comparing with concurrent/collocated observations from THEMIS and RAINBOW imagers, we distinguish two types of red-line pulsating auroras. In one type of red-line pulsating aurora, the emission is weak in intensity, but its pulsation is synchronous with that of the collocated green-line pulsating aurora. The other type of red-line pulsating aurora is fairly strong in intensity, but its temporal pattern contains much longer-period components as compared to the green-line pulsating aurora. In both types of pulsating auroras, the spatial dimension and motion speed of the red- and green-line auroral patches are rather comparable. We suggest that the first type of red-line pulsating aurora is caused by secondary electrons and/or a cascading excitation of O(1D) as the byproduct of the primary electron precipitation (and the resulting green-line emission), while the second type of red-line pulsating aurora is directly led by the low-energy part (hundreds of eV) of the electron precipitation in the lower F-region ionosphere. In the latter regard, we present in-situ RBSP observations conjugate to the pulsating auroral patches in a few events, and explore a potential relationship between the red-line pulsating aurora and the electron cyclotron harmonic (ECH) wave, which is capable of scattering the low-energy electrons into the loss-cone in the inner magnetosphere.

  4. A short dive into the complexity of Jupiter's aurorae - invited

    NASA Astrophysics Data System (ADS)

    Bonfond, Bertrand

    2015-04-01

    Aurorae are the atmospheric signatures of energetic processes taking place far in the magnetosphere. One of the most important results brought by high resolution imaging of the UV aurorae at Jupiter is the realization that there isn't such a thing as «the aurora» at Jupiter; as these light emissions appear to arise from a variety of processes. Some are related to the interaction of the magnetospheric plasma with the moons (the satellite footprints). Others are linked with the radial motion of flux tubes through centrifugal instabilities (the injection auroral signatures). Some diffuse emissions are connected with wave-particle interaction (the equatorward diffuse emissions). Another feature is associated with the magnetosphere-ionosphere coupling (the main emission/oval). Some auroral spots are related to internally driven reconnection (the polar dawn spots). Finally, the polar-most emissions remain to be understood and this list is still incomplete. In order to illustrate the discrepancies between these various features, I will show a set of recent results derived from the analysis of Hubble Space Telescope observations. For example, I will compare the vertical profile of satellite footprints and the main emissions, and show that the energy population of the precipitating particles varies from feature to feature. Moreover, even within a single feature, spatial variations do exist. As an example, I will characterize the dawn-dusk brightness discrepancy of the main emissions and discuss its implication regarding the magnetospheric currents. And finally, the dynamics of the features also helps differentiating one type of aurora from another. This will be shown through the description of the morphological evolution of the transient flares in the polar region.

  5. Nitric oxide gamma band emission in an aurora

    NASA Technical Reports Server (NTRS)

    Feldman, P. D.

    1976-01-01

    Emission of the NO gamma (1,0) band at 2150 A has been observed by a rocket-borne spectrophotometer in an IBC II(+) aurora. The nu-prime progression of the gamma-system does not appear in the spectrum. The observed emission rate of the 2150 A feature increases relative to N2(+) first negative band emission with increasing altitude. We suggest radiative recombination of NO(+) ions with electrons as a possible excitation mechanism compatible with the data.

  6. Planetary protection in the framework of the Aurora exploration program

    NASA Astrophysics Data System (ADS)

    Kminek, G.

    The Aurora Exploration Program will give ESA new responsibilities in the field of planetary protection. Until now, ESA had only limited exposure to planetary protection from its own missions. With the proposed ExoMars and MSR missions, however, ESA will enter the realm of the highest planetary protection categories. As a consequence, the Aurora Exploration Program has initiated a number of activities in the field of planetary protection. The first and most important step was to establish a Planetary Protection Working Group (PPWG) that is advising the Exploration Program Advisory Committee (EPAC) on all matters concerning planetary protection. The main task of the PPWG is to provide recommendations regarding: Planetary protection for robotic missions to Mars; Planetary protection for a potential human mission to Mars; Review/evaluate standards & procedures for planetary protection; Identify research needs in the field of planetary protection. As a result of the PPWG deliberations, a number of activities have been initiated: Evaluation of the Microbial Diversity in SC Facilities; Working paper on legal issues of planetary protection and astrobiology; Feasibility study on a Mars Sample Return Containment Facility; Research activities on sterilization procedures; Training course on planetary protection (May, 2004); Workshop on sterilization techniques (fall 2004). In parallel to the PPWG, the Aurora Exploration Program has established an Ethical Working Group (EWG). This working group will address ethical issues related to astrobiology, planetary protection, and manned interplanetary missions. The recommendations of the working groups and the results of the R&D activities form the basis for defining planetary protection specification for Aurora mission studies, and for proposing modification and new inputs to the COSPAR planetary protection policy. Close cooperation and free exchange of relevant information with the NASA planetary protection program is strongly

  7. Pulsating proton aurora caused by rising tone Pc1 waves

    NASA Astrophysics Data System (ADS)

    Nomura, R.; Shiokawa, K.; Omura, Y.; Ebihara, Y.; Miyoshi, Y.; Sakaguchi, K.; Otsuka, Y.; Connors, M.

    2016-02-01

    We found rising tone emissions with a dispersion of ˜1 Hz per several tens of seconds in the dynamic spectrum of a Pc1 geomagnetic pulsation (Pc1) observed on the ground. These Pc1 rising tones were successively observed over ˜30 min from 0250 UT on 14 October 2006 by an induction magnetometer at Athabasca, Canada (54.7°N, 246.7°E, magnetic latitude 61.7°N). Simultaneously, a Time History of Events and Macroscale Interactions during Substorms panchromatic (THEMIS) all-sky camera detected pulsations of an isolated proton aurora with a period of several tens of seconds, ˜10% variations in intensity, and fine structures of 3° in magnetic longitudes. The pulsations of the proton aurora close to the zenith of ATH have one-to-one correspondences with the Pc1 rising tones. This suggests that these rising tones scatter magnetospheric protons intermittently at the equatorial region. The radial motion of the magnetospheric source, of which the isolated proton aurora is a projection, can explain the central frequency increase of Pc1, but not the shorter period (tens of seconds) frequency increase of ˜1 Hz in Pc1 rising tones. We suggest that EMIC-triggered emissions generate the frequency increase of Pc1 rising tones on the ground and that they also cause the Pc1 pearl structure, which has a similar characteristic time.

  8. Relativistic-electron precipitations in a pulsating aurora

    SciTech Connect

    Hudnut, K.D.

    1987-01-01

    Data from scintillation and solid-state detectors flown on rockets in Norway in October, 1980 are used to examine the temporal and energetic characteristics of relativistic electrons precipitated during a pulsating post-breakup aurora in the morning sector. Electron bursts with mildly relativistic energies (up to 600 keV) discovered from the data are described in detail. Temporal features of these bursts showing periodic components on a time scale of 10 ms are described. These observations constitute a new regime of time and energy for electrons in morningside aurorae. A region within approximately 1 earth radius above the ionosphere on the L = 6.6 magnetic field line is determined as the point of acceleration of the electrons. These temporal, energetic, and spatial characteristics are compared to the electron-cyclotron resonance theory which has been proposed to explain pulsating electron precipitation in a morningside aurora. The theoretical model is shown to adequately explain some but not all of the observations. Suggestions for further theoretical and experimental treatments of this problem are made.

  9. Ancient writings reveal presence of aurora in 13th-century Canadian Arctic

    NASA Astrophysics Data System (ADS)

    Silverman, Sam

    Modern Norway, Iceland, and Greenland are subject to frequent displays of the aurora borealis. The aurora can be viewed on almost every clear night in the northern part of Iceland and southern Greenland, which lie in or near the auroral oval. Thus, it is surprising to find almost no mention of the aurora in medieval Norse chronicles or in the extensive Icelandic saga literature. Only one paragraph, in the "King's Mirror," a Norwegian writing dating to about 1250 C.E., notes the occurrence of the aurora in Greenland. The author reports this as hearsay and not from personal knowledge. For a fuller discussion of the Norse literature, see Brekke and Egeland [1983].

  10. Activation of Aurora-A is essential for neuronal migration via modulation of microtubule organization.

    PubMed

    Takitoh, Takako; Kumamoto, Kanako; Wang, Chen-Chi; Sato, Makoto; Toba, Shiori; Wynshaw-Boris, Anthony; Hirotsune, Shinji

    2012-08-01

    Neuronal migration is a critical feature to ensure proper location and wiring of neurons during cortical development. Postmitotic neurons migrate from the ventricular zone into the cortical plate to establish neuronal lamina in an "inside-out" gradient of maturation. Here, we report that the mitotic kinase Aurora-A is critical for the regulation of microtubule organization during neuronal migration via an Aurora-A-NDEL1 pathway in the mouse. Suppression of Aurora-A activity by inhibitors or siRNA resulted in severe impairment of neuronal migration of granular neurons. In addition, in utero injection of the Aurora-A kinase-dead mutant provoked defective migration of cortical neurons. Furthermore, we demonstrated that suppression of Aurora-A impaired microtubule modulation in migrating neurons. Interestingly, suppression of CDK5 by an inhibitor or siRNA reduced Aurora-A activity and NDEL1 phosphorylation by Aurora-A, which led to defective neuronal migration. We found that CDK5RAP2 is a key molecule that mediates functional interaction and is essential for centrosomal targeting of Aurora-A. Our observations demonstrated novel and surprising cross talk between Aurora-A and CDK5 during neuronal migration. PMID:22875938

  11. Non-conjugate aurora and inter hemispheric currents

    NASA Astrophysics Data System (ADS)

    Reistad, J. P.; Østgaard, N.; Laundal, K. M.; Oksavik, K.

    2012-04-01

    We look at large scale auroral features using global imagers to obtain simultaneous pictures of both the southern and northern auroral ovals in the ultra violet part of the spectra. During the years 2001 and 2002 the IMAGE satellite was in a favourable position for imaging the aurora borealis (Northern Hemisphere) and the POLAR satellite with its large field-of-view VIS Earth camera had a sporadic coverage of the aurora australis (Southern Hemisphere). In total 19 hours of simultaneous global imaging from different seasons are analysed searching for non-conjugacy in the night side sector. By non-conjugate aurora we mean auroral features appearing in one hemisphere only, or significant differences in intensity between the hemispheres for the same auroral feature. We suggest that our observed large scale asymmetries can be explained in terms of inter hemispheric currents (IHC). Coherent with our earlier findings, we list three possible candidates for producing such inter hemispheric currents based on observations. 1) Hemispherical differences in the solar wind dynamo due to IMF Bx and tilt angle producing different strength of region 1 currents in the conjugate he mispheres, 2) Hemispherical differences in conductivity controlled by the tilt angle only giving rise to IHC on closed field lines, and 3) Field-aligned current components induced by the penetration of the IMF By into the closed magnetosphere. Most of the observed non-conjugate aurora in our dataset can be explained by these candidates only. The IMF By penetration candidate is considered closer. We search for evidence in our data that IMF By < 0 (By > 0) can induce an IHC producing stronger aurora on the polar boundary in the Northern (Southern) Hemisphere. Also a second IHC component are predicted from the theory, mapping to the equatorward part of the oval and opposite directed along the magnetic field lines. Using a much larger dataset for one hemisphere only, we show whether these predicted currents can

  12. Jupiter Night-Side Auroras, North and South

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Oval-shaped auroras glow in night-side areas near Jupiter's north and south poles in these images taken by NASA's Cassini spacecraft on Jan. 13, 2001. The lower frame is the first to capture the southern aurora on the planet's night side. Blue lines of longitude and latitude have been added in each frame to indicate position of the glows.

    Jupiter's auroral ovals are similar to Earth's auroras, often called the northern lights or southern lights, although fluctuations in solar activity play a more important role in the auroras at Earth than at Jupiter. Energetic particles are constantly streaming towards Jupiter on magnetic field lines that intersect the planet's atmosphere on a ring around the magnetic pole. Where the energetic particles hit the upper atmosphere, they cause emission of light, similar to the glow in a fluorescent bulb. In the north (upper image), the magnetic pole is offset from the rotational pole, which is where the blue longitude lines converge, just to the left of the imaged area. The auroral oval appears like a draped necklace that is carried around by the rotation of the planet. In the south (lower image), the magnetic and rotational poles are nearly coincident, so no significant offset is visible.

    Cassini had passed its closest to Jupiter about two weeks before taking these pictures, so it was in position to see the night side of the planet. It was about 16.5 million kilometers (10.3 million miles) from the planet and about 2.5 degrees below the plane of Jupiter's equator. The smallest features visible are about 100 kilometers (about 60 miles) across. The images were taken by Cassini's narrow-band camera through a filter centered on a light-wave frequency at which hydrogen emits light when it is excited. They have been processed to remove scattered light from the overexposed sunlit crescent of the planet. Hydrogen is a major ingredient of Jupiter's atmosphere.

    It is not understood why the auroral oval rings are so thin. Cassini

  13. AURORA on MEGSAT 1: a photon counting observatory for the Earth UV night-sky background and Aurora emission

    NASA Astrophysics Data System (ADS)

    Monfardini, A.; Trampus, P.; Stalio, R.; Mahne, N.; Battiston, R.; Menichelli, M.; Mazzinghi, P.

    2001-08-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed ``Notte'' and the Aurora emission with ``Alba''. AURORA, this is the name of the experiment, will determine, with the ``Notte'' channel, the overall night-side photon background in the 300-400nm spectral range, together with a particular 2+N2 line (λc=337nm). The ``Alba'' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6nm) centered on: 367nm (continuum evaluation), 391nm (1-N+2), 535nm (continuum evaluation), 560nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 ``Satan'' rocket. The satellite orbit is nearly circular (hapogee=648km, /e=0.0022), and the inclination of the orbital plane is 64.56°. An overview of the techniques adopted is given in this paper.

  14. Saturn's Hydrogen Aurora, WFPC2 Imaging from the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Trauger, J. T.; Clarke, J. T.; Ballester, G. E.; Evans, R. W.; Burrows, C. J.; Crisp, D.; Gallagher, J. S.; Griffiths, R. E.; Hester, J. Jeff; Hoessel, J. G.; Holtzman, J. A.; Mould, J. R.; Sahai, R.; Scowen, P. A.; Stapelfeldt, K. R.; Watson, A. M.

    1998-01-01

    WFPC2/HST images of Saturn's far-ultraviolet aurora reveal emissions confined to a narrow band of latitudes near Saturn's north and south poles. The aurorae are most prominent in the morning sector with patterns that appear fixed in local time.

  15. Dynamic Phosphorylation of NudC by Aurora B in Cytokinesis

    PubMed Central

    Weiderhold, Kimberly N.; Fadri-Moskwik, Maria; Pan, Jing; Nishino, Michiya; Chuang, Carol; Deeraksa, Arpaporn; Lin, Sue-Hwa; Yu-Lee, Li-Yuan

    2016-01-01

    Nuclear distribution protein C (NudC) is a mitotic regulator that plays a role in cytokinesis. However, how NudC is regulated during cytokinesis remains unclear. Here, we show that NudC is phosphorylated by Aurora B, a kinase critical for cell abscission. NudC is co-localized with Aurora B at the midbody and co-immunoprecipitated with Aurora B in mitosis. Inhibition of Aurora B by ZM447439 reduced NudC phosphorylation, suggesting that NudC is an Aurora B substrate in vivo. We identified T40 on NudC as an Aurora B phosphorylation site. NudC depletion resulted in cytokinesis failure with a dramatic elongation of the intercellular bridge between daughter cells, sustained Aurora B activity at the midbody, and reduced cell abscission. These cytokinetic defects can be rescued by the ectopic expression of wild-type NudC. Reconstitution with T40A phospho-defective NudC was found to rescue the cytokinesis defect. In contrast, reconstitution with the T40D phospho-mimetic NudC was inefficient in supporting the completion of cytokinesis. These results suggest that that dynamic phosphorylation of NudC by Aurora B regulates cytokinesis. PMID:27074040

  16. Aurora-A kinase (AURKA) in normal and pathological cell growth

    PubMed Central

    Nikonova, Anna S.; Astsaturov, Igor; Serebriiskii, Ilya G.; Dunbrack, Roland L.; Golemis, Erica A.

    2013-01-01

    Temporally and spatially controlled activation of the Aurora-A kinase (AURKA) is regulates centrosome maturation, entry into mitosis, formation and function of the bipolar spindle, and cytokinesis. Genetic amplification, and mRNA and protein overexpression of Aurora-A are common in many types of solid tumor, and associated with aneuploidy, supernumerary centrosomes, defective mitotic spindles, and resistance to apoptosis. These properties have led Aurora-A to be considered a high value target for development of cancer therapeutics, with multiple agents currently in early phase clinical trials. More recently, identification of additional, non-mitotic functions and means of activation of Aurora-A during interphase neurite elongation and ciliary resorption have significantly expanded understanding of its function, and may offer insights into clinical performance of Aurora-A inhibitors. We here review mitotic and non-mitotic functions of Aurora-A, discuss Aurora-A regulation in the context of protein structural information, and evaluate progress in understanding and inhibiting Aurora-A in cancer. PMID:22864622

  17. STS-45 Earth observation of the Aurora Australis or Southern Lights

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-45 Earth observation taken onboard Atlantis, Orbiter Vehicle (OV) 104, is of the Aurora Australis or Southern Lights. The STS-45 crewmembers note the interesting spiralling or corkscrew appearance of this particular sighting. Aurorae were observed and photographed throughout the STS-45 nine-day mission.

  18. Therapeutic potential of mitotic interaction between the nucleoporin Tpr and aurora kinase A

    PubMed Central

    Kobayashi, Akiko; Hashizume, Chieko; Dowaki, Takayuki; Wong, Richard W

    2015-01-01

    Spindle poles are defined by centrosomes; therefore, an abnormal number or defective structural organization of centrosomes can lead to loss of spindle bipolarity and genetic integrity. Previously, we showed that Tpr (translocated promoter region), a component of the nuclear pore complex (NPC), interacts with Mad1 and dynein to promote proper chromosome segregation during mitosis. Tpr also associates with p53 to induce autophagy. Here, we report that Tpr depletion induces mitotic catastrophe and enhances the rate of tetraploidy and polyploidy. Mechanistically, Tpr interacts, via its central domain, with Aurora A but not Aurora B kinase. In Tpr-depleted cells, the expression levels, centrosomal localization and phosphorylation of Aurora A were all reduced. Surprisingly, an Aurora A inhibitor, Alisertib (MLN8237), also disrupted centrosomal localization of Tpr and induced mitotic catastrophe and cell death in a time- and dose-dependent manner. Strikingly, over-expression of Aurora A disrupted Tpr centrosomal localization only in cells with supernumerary centrosomes but not in bipolar cells. Our results highlight the mutual regulation between Tpr and Aurora A and further confirm the importance of nucleoporin function in spindle pole organization, bipolar spindle assembly, and mitosis; functions that are beyond the conventional nucleocytoplasmic transport and NPC structural roles of nucleoporins. Furthermore, the central coiled-coil domain of Tpr binds to and sequesters extra Aurora A to safeguard bipolarity. This Tpr domain merits further investigation for its ability to inhibit Aurora kinase and as a potential therapeutic agent in cancer treatment. PMID:25789545

  19. 78 FR 64196 - Approval of Subzone Status: Pillow Kingdom, Inc., Aurora, Colorado

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-28

    ... Register inviting public comment (78 FR 52758-52759, 08-26-2013). The FTZ staff examiner reviewed the... Foreign-Trade Zones Board Approval of Subzone Status: Pillow Kingdom, Inc., Aurora, Colorado On August 21... existing activation limit of FTZ 123, on behalf of Pillow Kingdom, Inc., in Aurora, Colorado....

  20. 77 FR 43703 - Honoring the Victims of the Tragedy in Aurora, Colorado

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-25

    ... Sig.) [FR Doc. 2012-18326 Filed 7-24-12; 11:15 am] Billing code 3295-F2-P ... Documents#0;#0; ] Proclamation 8842 of July 20, 2012 Honoring the Victims of the Tragedy in Aurora, Colorado... of the senseless acts of violence perpetrated on July 20, 2012, in Aurora, Colorado, by the...

  1. Low-Latitude Auroras: The Magnetic Storm of 14-15 May 1921

    NASA Technical Reports Server (NTRS)

    Silverman, S. M.; Cliver, E. W.

    2001-01-01

    We review solar geophysical data relating to the great magnetic storm of 14-15 May 1921, with emphasis on observations of the low-latitude visual aurora. From the reports we have gathered for this event the lowest geomagnetic latitude of definite overhead aurora (coronal form) was 40 deg and the lowest geomagnetic latitude from which auroras were observed on the poleward horizon in the northern hemisphere was 30 deg. For comparison, corresponding overhead/low-latitude values of 48 deg/32 deg and 41 deg/20 deg were reported for the great auroras on 28-29 August and 1-2 September 1859, respectively. However for the 1921 event, there is a report of aurora from Apia, Samoa, in the southern hemisphere, within 13 deg of the geomagnetic equator. This report by professional observers appears to be credible, based on the aurora description and timing, but is puzzling because of the discrepancy with the lowest latitude of observation in the northern hemisphere and the great implied aurora height (approximately 2000 km, assuming overhead aurora at Auckland, New Zealand). We discuss various possibilities that might account for this observation.

  2. Aurora B Overexpression Causes Aneuploidy and p21Cip1 Repression during Tumor Development

    PubMed Central

    González-Loyola, Alejandra; Fernández-Miranda, Gonzalo; Trakala, Marianna; Partida, David; Samejima, Kumiko; Ogawa, Hiromi; Cañamero, Marta; de Martino, Alba; Martínez-Ramírez, Ángel; de Cárcer, Guillermo; Pérez de Castro, Ignacio; Earnshaw, William C.

    2015-01-01

    Aurora kinase B, one of the three members of the mammalian Aurora kinase family, is the catalytic component of the chromosomal passenger complex, an essential regulator of chromosome segregation in mitosis. Aurora B is overexpressed in human tumors although whether this kinase may function as an oncogene in vivo is not established. Here, we report a new mouse model in which expression of the endogenous Aurkb locus can be induced in vitro and in vivo. Overexpression of Aurora B in cultured cells induces defective chromosome segregation and aneuploidy. Long-term overexpression of Aurora B in vivo results in aneuploidy and the development of multiple spontaneous tumors in adult mice, including a high incidence of lymphomas. Overexpression of Aurora B also results in a reduced DNA damage response and decreased levels of the p53 target p21Cip1 in vitro and in vivo, in line with an inverse correlation between Aurora B and p21Cip1 expression in human leukemias. Thus, overexpression of Aurora B may contribute to tumor formation not only by inducing chromosomal instability but also by suppressing the function of the cell cycle inhibitor p21Cip1. PMID:26240282

  3. Aurora B prevents delayed DNA replication and premature mitotic exit by repressing p21Cip1

    PubMed Central

    Trakala, Marianna; Fernández-Miranda, Gonzalo; Pérez de Castro, Ignacio; Heeschen, Christopher; Malumbres, Marcos

    2013-01-01

    Aurora kinase B is a critical component of the chromosomal passenger complex, which is involved in the regulation of microtubule-kinetochore attachments and cytokinesis. By using conditional knockout cells and chemical inhibition, we show here that inactivation of Aurora B results in delayed G1/S transition and premature mitotic exit. Aurora B deficiency results in delayed DNA replication in cultured fibroblasts as well as liver cells after hepatectomy. This is accompanied by increased transcription of the cell cycle inhibitor p21Cip1. Lack of Aurora B does not prevent mitotic entry but results in a premature exit from prometaphase in the presence of increased p21Cip1-Cdk1 inactive complexes. Aurora B-null cells display reduced degradation of cyclin B1, suggesting the presence of phenomenon known as adaptation to the mitotic checkpoint, previously described in yeast. Elimination of p21Cip1 rescues Cdk1 activity and prevents premature mitotic exit in Aurora B-deficient cells. These results suggest that Aurora B represses p21Cip1, preventing delayed DNA replication, Cdk inhibition and premature mitotic exit. The upregulation of p21Cip1 observed after inhibition of Aurora B may have important implications in cell cycle progression, tetraploidy, senescence or cancer therapy. PMID:23428904

  4. 3 CFR 8842 - Proclamation 8842 of July 20, 2012. Honoring the Victims of the Tragedy in Aurora, Colorado

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Victims of the Tragedy in Aurora, Colorado 8842 Proclamation 8842 Presidential Documents Proclamations Proclamation 8842 of July 20, 2012 Proc. 8842 Honoring the Victims of the Tragedy in Aurora, ColoradoBy the... senseless acts of violence perpetrated on July 20, 2012, in Aurora, Colorado, by the authority vested in...

  5. Spiral structures and regularities in magnetic field variations and auroras

    NASA Astrophysics Data System (ADS)

    Feldstein, Y. I.; Gromova, L. I.; Förster, M.; Levitin, A. E.

    2012-02-01

    The conception of spiral shaped precipitation regions, where solar corpuscles penetrate the upper atmosphere, was introduced into geophysics by C. Störmer and K. Birkeland at the beginning of the last century. Later, in the course of the XX-th century, spiral distributions were disclosed and studied in various geophysical phenomena. Most attention was devoted to spiral shapes in the analysis of regularities pertaining to the geomagnetic activity and auroras. We review the historical succession of perceptions about the number and positions of spiral shapes, that characterize the spatial-temporal distribution of magnetic disturbances. We describe the processes in the upper atmosphere, which are responsible for the appearance of spiral patterns. We considered the zones of maximal aurora frequency and of maximal particle precipitation intensity, as offered in the literature, in their connection with the spirals. We discuss the current system model, that is closely related to the spirals and that appears to be the source for geomagnetic field variations during magnetospheric substorms and storms. The currents in ionosphere and magnetosphere constitute together with field-aligned (along the geomagnetic field lines) currents (FACs) a common 3-D current system. At ionospheric heights, the westward and eastward electrojets represent characteristic elements of the current system. The westward electrojet covers the longitudinal range from the morning to the evening hours, while the eastward electrojet ranges from afternoon to near-midnight hours. The polar electrojet is positioned in the dayside sector at cusp latitudes. All these electrojets map along the magnetic field lines to certain plasma structures in the near-Earth space. The first spiral distribution of auroras was found based on observations in Antarctica for the nighttime-evening sector (N-spiral), and later in the nighttime-evening (N-spiral) and morning (M-spiral) sectors both in the Northern and Southern

  6. The Dawn of Aurora Kinase Research: From Fly Genetics to the Clinic.

    PubMed

    Carmena, Mar; Earnshaw, William C; Glover, David M

    2015-01-01

    Aurora kinases comprise a family of highly conserved serine-threonine protein kinases that play a pivotal role in the regulation of cell cycle. Aurora kinases are not only involved in the control of multiple processes during cell division but also coordinate chromosomal and cytoskeletal events, contributing to the regulation of checkpoints and ensuring the smooth progression of the cell cycle. Because of their fundamental contribution to cell cycle regulation, Aurora kinases were originally identified in independent genetic screens designed to find genes involved in the regulation of cell division. The first aurora mutant was part of a collection of mutants isolated in C. Nusslein-Volhard's laboratory. This collection was screened in D. M. Glover's laboratory in search for mutations disrupting the centrosome cycle in embryos derived from homozygous mutant mothers. The mutants identified were given names related to the "polar regions," and included not only aurora but also the equally famous polo. Ipl1, the only Aurora in yeast, was identified in a genetic screen looking for mutations that caused chromosome segregation defects. The discovery of a second Aurora-like kinase in mammals opened a new chapter in the research of Aurora kinases. The rat kinase AIM was found to be highly homologous to the fly and yeast proteins, but localized at the midzone and midbody and was proposed to have a role in cytokinesis. Homologs of the equatorial Aurora (Aurora B) were identified in metazoans ranging from flies to humans. Xenopus Aurora B was found to be in a complex with the chromosomal passenger INCENP, and both proteins were shown to be essential in flies for chromosome structure, segregation, central spindle formation and cytokinesis. Fifteen years on, Aurora kinase research is an active field of research. After the successful introduction of the first anti-mitotic agents in cancer therapy, both Auroras have become the focus of attention as targets for the development of new

  7. The Dawn of Aurora Kinase Research: From Fly Genetics to the Clinic

    PubMed Central

    Carmena, Mar; Earnshaw, William C.; Glover, David M.

    2015-01-01

    Aurora kinases comprise a family of highly conserved serine-threonine protein kinases that play a pivotal role in the regulation of cell cycle. Aurora kinases are not only involved in the control of multiple processes during cell division but also coordinate chromosomal and cytoskeletal events, contributing to the regulation of checkpoints and ensuring the smooth progression of the cell cycle. Because of their fundamental contribution to cell cycle regulation, Aurora kinases were originally identified in independent genetic screens designed to find genes involved in the regulation of cell division. The first aurora mutant was part of a collection of mutants isolated in C. Nusslein-Volhard's laboratory. This collection was screened in D. M. Glover's laboratory in search for mutations disrupting the centrosome cycle in embryos derived from homozygous mutant mothers. The mutants identified were given names related to the “polar regions,” and included not only aurora but also the equally famous polo. Ipl1, the only Aurora in yeast, was identified in a genetic screen looking for mutations that caused chromosome segregation defects. The discovery of a second Aurora-like kinase in mammals opened a new chapter in the research of Aurora kinases. The rat kinase AIM was found to be highly homologous to the fly and yeast proteins, but localized at the midzone and midbody and was proposed to have a role in cytokinesis. Homologs of the equatorial Aurora (Aurora B) were identified in metazoans ranging from flies to humans. Xenopus Aurora B was found to be in a complex with the chromosomal passenger INCENP, and both proteins were shown to be essential in flies for chromosome structure, segregation, central spindle formation and cytokinesis. Fifteen years on, Aurora kinase research is an active field of research. After the successful introduction of the first anti-mitotic agents in cancer therapy, both Auroras have become the focus of attention as targets for the development of

  8. Jupiter's Mid-Infrared Aurora: Solar Connection and Minor Constituents

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodore; Livengood, T.A.; Fast, K.E.; Hewagama, T.; Schmilling, F.; Sonnabend, G.; Delgado, J.

    2009-01-01

    High spectral resolution in the 12 pin region of the polar regions of Jupiter reveal unique information on auroral phenomena and upper stratospheric composition. Polar aurorae in Jupiter's atmosphere radiate; throughout the electromagnetic spectrum from X-ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based. spectroscopic measurements of Jupiter's northern mid-IR aurora acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane, emission brightness and solar 10.7-cm radar flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high scalar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. The spectra measured contain features that cannot be attributed to ethane and are most likely spectra of minor constituents whose molecular bands overlap the v9 band of ethane. Possible candidates are allene, propane, and other higher order hydrocarbons. These features appear to be enhanced in the active polar regions. Laboratory measurements at comparable spectral resolution of spectra of candidate molecules will be used to identify the constituents. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the NASA/ESA Europa Jupiter System Mission.

  9. AURORA BOREALIS - European Research Icebreaker With Drilling Capability

    NASA Astrophysics Data System (ADS)

    Biebow, N.; Lembke-Jene, L.; Kunz-Pirrung, M.; Thiede, J.

    2008-12-01

    The polar oceans are the least known areas of the globe, in although they hold the key to many of our climate´s secrets. How does the sea ice coverage and the sea water properties change? How do plants and animals survive under the most extreme conditions of the earth? Which information of past climate change can be read from the sediments at the sea-floor and how can the future changing climate be predicted? In order to answer such and further questions, for the moment a hypermodern research vessel, the AURORA BOREALIS, is planned, which can handle the cool summers and freezing winters of the polar oceans and which can drill deep into the sea floor. AURORA BOREALIS will be the most advanced Research Icebreaker in the world with a multi-functional role of drilling in deep ocean basins and supporting climate/environmental research and decision support for stakeholder governments for the next 35-40 years. It will have a high icebreaking capacity to penetrate autonomously (single ship operation) into the central Arctic Ocean with more than 2.5 meters of ice cover, during all seasons of the year. The new technological features will include dynamic positioning in closed sea- ice cover, satellite navigation and ice-management support and the deployment and operation of Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUVs) from the twin moon-pools. A unique feature of the vessel is the deep-sea drilling rig, which will enable sampling of the ocean floor and sub-sea up to 5000 m water and 1000 m penetration at the most inhospitable places on earth. The drilling capability will be deployed in both Polar Regions on the long run and AURORA BOREALIS will be the only vessel worldwide that could undertake this type of scientific investigation.

  10. First Terrestrial Soft X-ray Aurora Observations by Chandra

    NASA Technical Reports Server (NTRS)

    Bhardwaj, Anil; Elsner, Ronald F.; Gladstone, G. Randall; Waite, J. Hunter, Jr.; Cravens, Thomas E.; Ostgaard, Nikolai; Chang, Shen-Wu; Metzger, Albert E.; Majeed, Tariq

    2004-01-01

    Northern polar "auroral" regions of Earth was observed by High-Resolution Camera in imaging mode (T32C-I) aboard Chandra X-Ray Observatory (CXO) during mid December 2003 - mid April 2004. Ten CXO observations, each approximately 20 min duration, were made in a non-conventional method (due to CXO technical issues), such that Chandra was aimed at a fixed point in sky and the Earth's polar cusp was allowed to drift through the HRC-I field-of-view. The observations were performed when CXO was near apogee and timed during northern winter mostly near midnight (6 hr), except two observations which occurred around 1200 UT, so that northern polar region is entirely in dark and solar fluoresced x-ray contamination can be avoided. These observations were aimed at searching the Earth's soft x-ray aurora and to do a comparative study with Jupiter's x-ray aurora, where a pulsating x-ray hot-spot near the northern magnetic pole has been observed by Chandra that implies a particle source region near Jupiter's magnetopause, and entry of heavy solar wind ions due to high-latitude reconnection as a viable explanation for the soft x-ray emissions. The first Chandra soft (0.1-2 keV) x-ray observations of Earth's aurora show that it is highly variable (intense arc, multiple arcs, diffuse, at times almost absent). In at least one of the observations an isolated blob of emission is observed where we expect cusp to be: giving indication of solar wind charge-exchange signature in x-rays. We are comparing the Chandra x-ray observations with observations at other wavelengths and particle data from Earth-orbiting satellites and solar wind measurements from near-Earth ACE and SOH0 spacecraft. Preliminary results from these unique CXO-Earth observations will be presented and discussed.

  11. Modeling Optical Emission Intensities of Rapid Small-Scale Aurora

    NASA Astrophysics Data System (ADS)

    Habash Krause, L.; Minow, J. I.

    2014-12-01

    Auroral transitional line emissions have often been used to infer the fluence and characteristic energy of precipitating electrons. A common practice is to use emissions from an allowed transition to infer absolute particle flux since the odds of quenching before photon emission are negligible. Characteristic energy is then determined by line emission intensity ratios between a forbidden and allowed transitions: The intensity of a forbidden transition will increase with altitude since the probability for quenching drops with decreasing density. Bright metastable lines such as 630.0 nm O(1D) -> O(3P) and the 557.7 nm O(1S) -> O(1D) are often used with a prompt line such as 427.8 nm N2+(1N) to determine characteristic energy. With the advances in scientific cameras, narrow-band filtered video of pulsing aurora up to 32 fps are now in use. The question then becomes, if the transitional lifetimes of the metastable species are significantly greater (or even comparable to) the aurora pulsing period, how can the ratio technique be used to determine the characteristic energy of the precipitating electrons? Once it is realized that the quoted lifetimes are average values, we note that there will be a fraction of photons that are emitted before the species is quenched. With this study, we present results from the GLOW model for different metastable species to determine the optimal combination of lines that would be helpful in determination of precipitating electron characteristics in pulsing aurora up to 100 Hz. Enabling technology and optimal configurations will be presented, along with suggested applications for linking different optical signatures with their corresponding precipitating electron distribution shape.

  12. Evolution of the Global Aurora During Positive IMP Bz and Varying IMP By Conditions

    NASA Technical Reports Server (NTRS)

    Cumnock, J. A.; Sharber, J. R.; Heelis. R. A.; Hairston, M. R.; Carven, J. D.

    1997-01-01

    The DE 1 imaging instrumentation provides a full view of the entire auroral oval every 12 min for several hours during each orbit. We examined five examples of global evolution of the aurora that occurred during the northern hemisphere winter of 1981-1982 when the z component of the interplanetary magnetic field was positive and the y component was changing sign. Evolution of an expanded auroral emission region into a theta aurora appears to require a change in the sign of By during northward interplanetary magnetic field (IMF). Theta aurora are formed both from expanded duskside emission regions (By changes from positive to negative) and dawnside emission regions (By changes from negative to positive), however the dawnside-originating and duskside-originating evolutions are not mirror images. The persistence of a theta aurora after its formation suggests that there may be no clear relationship between the theta aurora pattern and the instantaneous configuration of the IMF.

  13. The Aurora B Kinase in Chromosome Bi-Orientation and Spindle Checkpoint Signaling

    PubMed Central

    Krenn, Veronica; Musacchio, Andrea

    2015-01-01

    Aurora B, a member of the Aurora family of serine/threonine protein kinases, is a key player in chromosome segregation. As part of a macromolecular complex known as the chromosome passenger complex, Aurora B concentrates early during mitosis in the proximity of centromeres and kinetochores, the sites of attachment of chromosomes to spindle microtubules. There, it contributes to a number of processes that impart fidelity to cell division, including kinetochore stabilization, kinetochore–microtubule attachment, and the regulation of a surveillance mechanism named the spindle assembly checkpoint. In the regulation of these processes, Aurora B is the fulcrum of a remarkably complex network of interactions that feed back on its localization and activation state. In this review, we discuss the multiple roles of Aurora B during mitosis, focusing in particular on its role at centromeres and kinetochores. Many details of the network of interactions at these locations remain poorly understood, and we focus here on several crucial outstanding questions. PMID:26528436

  14. A FRET biosensor reveals spatiotemporal activation and functions of aurora kinase A in living cells.

    PubMed

    Bertolin, Giulia; Sizaire, Florian; Herbomel, Gaëtan; Reboutier, David; Prigent, Claude; Tramier, Marc

    2016-01-01

    Overexpression of AURKA is a major hallmark of epithelial cancers. It encodes the multifunctional serine/threonine kinase aurora A, which is activated at metaphase and is required for cell cycle progression; assessing its activation in living cells is mandatory for next-generation drug design. We describe here a Förster's resonance energy transfer (FRET) biosensor detecting the conformational changes of aurora kinase A induced by its autophosphorylation on Thr288. The biosensor functionally replaces the endogenous kinase in cells and allows the activation of the kinase to be followed throughout the cell cycle. Inhibiting the catalytic activity of the kinase prevents the conformational changes of the biosensor. Using this approach, we discover that aurora kinase A activates during G1 to regulate the stability of microtubules in cooperation with TPX2 and CEP192. These results demonstrate that the aurora kinase A biosensor is a powerful tool to identify new regulatory pathways controlling aurora kinase A activation. PMID:27624869

  15. Field-aligned electron flux oscillations that produce flickering aurora

    NASA Technical Reports Server (NTRS)

    Mcfadden, J. P.; Carlson, C. W.; Boehm, M. H.; Hallinan, T. J.

    1987-01-01

    Measurements of energetic electrons that produce flickering aurora were made by a pair of sounding rockets, launched during a slowly evolving auroral breakup. Both payloads passed through a broad inverted-V structure. A component of the electron distribution function was closely aligned with the magnetic field over a broad energy range that extended from low energies up to the inverted-V differential energy flux peak. Measurements of the field-aligned component showed the presence of order of magnitude coherent flux oscillations. Source altitudes between 4000 and 8000 km were derived from velocity dispersion of the flux oscillations.

  16. Exploring the Secrets of the Aurora, 2nd edition

    NASA Astrophysics Data System (ADS)

    Robinson, Robert M.

    2008-04-01

    Pioneers in science invariably have struggled with ideas that future scientists learn and accept with almost casual indifference. Perhaps the basis for progress in science is that the energy and creativity of young scientists need not be expended on rediscovering truths that earlier scientists spent whole careers uncovering. Nevertheless, an appreciation for the process by which these truths were painstakingly unveiled is a lesson from which scientists of all ages can learn. Exploring the Secrets of the Aurora, by Syun-Ichi Akasofu, should be read for that reason alone, but the book has other merits as well.

  17. HUBBLE PROVIDES THE FIRST IMAGES OF SATURN'S AURORA (Top)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This is the first image ever taken of bright aurorae at Saturn's northern and southern poles, as seen in far ultraviolet light by the Wide Field and Planetary Camera 2 aboard NASA's Hubble Space Telescope. Hubble resolves a luminous, circular band centered on the north pole, where an enormous auroral curtain rises as far as 1,200 miles (2,000 kilometers) above the cloudtops. This curtain changed rapidly in brightness and extent over the two hour period of our HST observations, though the brightest emissions remained at a position fixed in sun angle, near 'dawn' in the north auroral band. The image was taken on October 9, 1994, when Saturn was at a distance of 831 million miles (1.3 billion kilometers) from Earth. The aurora is produced as trapped charged particles precipitating from the magnetosphere collide with atmospheric gases -- molecular and atomic hydrogen in Saturn's case. As a result of the bombardment, Saturn's gases glow at far-ultraviolet wavelengths (110-160 nanometers) which are absorbed by the Earth's atmosphere, and so can only be observed from space-based telescopes. Saturn's magnetic field is nearly perfectly aligned with the planet's rotation, giving the auroral 'ring' its symmetry centered on the pole. (The southern aurora is faintly visible in this view despite the fact that Saturn's northern pole is now tilted slightly toward Earth.) The Hubble images demonstrate our capability to record from the Earth the auroral brightness and distribution about Saturn's poles, which will ultimately complement the in situ measurements of Saturn's magnetic field and charged particles to be made by the NASA/ESA Cassini spacecraft near the turn of the century. Study of the aurora on Saturn had its beginnings a few decades ago. The Pioneer 11 probe observed a far-ultraviolet brightening on Saturn's poles in 1979. Beginning in 1980, a series of spectroscopic observations by the International Ultraviolet Explorer (IUE) have sporadically detected emissions from

  18. Artificial auroras in the upper atmosphere. I - Electron beam injections

    NASA Technical Reports Server (NTRS)

    Burch, J. L.; Mende, S. B.; Kawashima, N.; Roberts, W. T.; Taylor, W. W. L.; Neubert, T.; Gibson, W. C.; Marshall, J. A.; Swenson, G. R.

    1993-01-01

    The Atlas-1 Spacelab payload's Space Experiments with Particle Accelerators generated artificial electron beams for the stimulation of auroral emissions at southern auroral latitudes. Optical measurements were made by the Shuttle Orbiter's onboard TV cameras, as well as by the Atmospheric Emissions Photometric Imager (in both white light and the 427.8 nm N2(+) emission line). Shuttle-based auroral imaging furnished a novel perspective on the artificial auroras; the emissions were traced from 295 km to the 110 km level along the curved magnetic-field lines.

  19. UV Imaging of Europa & Ganymede: Unveiling Satellite Aurora & Electrodynamical Interactions

    NASA Astrophysics Data System (ADS)

    McGrath, Melissa

    1999-07-01

    We propose to obtain dispersed ultraviolet images of Europa and Ganymede using STIS to isolate atomic oxygen {1304 and 1356 Angstrom} and hydrogen {Lyman-Alpha} emissions, to study the interaction of the Jovian magnetosphere with the tenuous oxygen atmospheres of these icy satellites. Previous spectroscopic observations, from both HST {with GHRS} and Galileo, suggest the presence of polar aurorae on Ganymede whose geometry would be clearly delineated in these images. Europa is expected to show an oxygen emission morphology similar to that recently discovered on Io.

  20. The reflex-diode HPM source on Aurora

    SciTech Connect

    Huttlin, G.A.; Bushell, M.S.; Conrad, D.B.; Davis, D.P.; Litz, M.S.; Ruth, B.G.; Agee, F.J. ); Ebersole, K.L.; Judy, D.C.; Lezcano, P.A.; Pereira, N.R.; Weidenheimer, D.M. )

    1990-06-01

    This paper describes the most recent in a series of experiments to develop the reflex diode as a source of microwaves on the Aurora relativistic electron-beam pulser. The authors have achieved an overall output for radial extraction of {approximately} 400 J in microwave bursts from {approximately} 100 to 150 ns at frequencies below 1 GHz. The diagnostics for radial extraction have included directional couplers, card calorimeters, and free-field sensors. The authors have varied the anode/cathode spacing, downstream microwave reflector, and a second anode foil, but, within the range of variations, no strong trends have been noted.

  1. Polar views of the earth's aurora with Dynamics Explorer

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Craven, J. D.; Burch, J. L.; Winningham, J. D.

    1982-01-01

    Preliminary examination of the first global auroral images gained with the vacuum-ultraviolet imaging photometer on board DE 1 reveals a remarkable spatial configuration of auroral luminosities. Frequently the northern auroral oval is bifurcated by a sun-aligned arc extending from the midday auroral zone to the nighttime sector of the oval. Simultaneous plasma measurements with the low-altitude DE-2 spacecraft are used to show that the character of plasmas above the polar arc is similar to those found over the poleward zones of the auroral oval. The spatial distribution of auroral luminosities is suggestive of a two-cell structure of current systems and convection electric fields over the earth's polar cap and a similar division of the corresponding lobe in the magnetotail.

  2. Basal aurora kinase B activity is sufficient for histone H3 phosphorylation in prophase

    PubMed Central

    Le, Ly-Thuy-Tram; Vu, Hong-Lien; Nguyen, Chi-Hung; Molla, Annie

    2013-01-01

    Summary Histone H3 phosphorylation is the hallmark of mitosis deposited by aurora kinase B. Benzo[e]pyridoindoles are a family of potent, broad, ATP-competitive aurora kinase inhibitors. However, benzo[e]pyridoindole C4 only inhibits histone H3 phosphorylation in prophase but not in metaphase. Under the C4 treatment, the cells enter into mitosis with dephosphorylated histone H3, assemble chromosomes normally and progress to metaphase, and then to anaphase. C4 also induces lagging chromosome in anaphase but we demonstrated that these chromosome compaction defects are not related to the absence of H3 phosphorylation in prophase. As a result of C4 action, mitosis lasts longer and the cell cycle is slowed down. We reproduced the mitotic defects with reduced concentrations of potent pan aurora kinase as well as with a specific aurora B ATP-competitive inhibitor; we therefore propose that histone H3 phosphorylation and anaphase chromosome compaction involve the basal activity of aurora kinase B. Our data suggest that aurora kinase B is progressively activated at mitosis entry and at anaphase onset. The full activation of aurora kinase B by its partners, in prometaphase, induces a shift in the catalytic domain of aurora B that modifies its affinity for ATP. These waves of activation/deactivation of aurora B correspond to different conformations of the chromosomal complex revealed by FRAP. The presence of lagging chromosomes may have deleterious consequences on the daughter cells and, unfortunately, the situation may be encountered in patients receiving treatment with aurora kinase inhibitors. PMID:23616922

  3. Inhibition of Survivin and Aurora B Kinase Sensitizes Mesothelioma Cells by Enhancing Mitotic Arrests

    SciTech Connect

    Kim, Kwang Woon; Mutter, Robert W.; Willey, Christopher D.; Subhawong, Ty K.; Shinohara, Eric T.; Albert, Jeffrey M.; Ling Geng; Cao, Carolyn; Gi, Young Jin; Bo Lu . E-mail: bo.lu@vanderbilt.edu

    2007-04-01

    Purpose: Survivin, a member of the inhibitor of apoptosis gene family, has also been shown to regulate mitosis. It binds Aurora B kinase and the inner centromere protein to form the chromosome passenger complex. Both Aurora B and survivin are overexpressed in many tumors. In this study, we examined whether irradiation affected survivin and Aurora B expression in mesothelioma cells, and how inhibition of these molecules affected radiosensitivity. Methods and Materials: ZM447439 and survivin antisense oligonucleotides were used to inhibit survivin and Aurora B kinase respectively. Western blot was performed to determine the expression of survivin, Aurora B, phosphorylated-histone H3 (Ser 10), and caspase cleavage. Multinucleated cells were counted using flow cytometry, and cell survival after treatment was determined using clonogenic assay. Results: At 3-Gy irradiation an increase was observed in levels of survivin and Aurora B as well as the kinase activity of Aurora B, with an increase in G2/M phase. The radiation-induced upregulation of these molecules was effectively attenuated by antisense oligonucleotides against survivin and a small-molecule inhibitor of Aurora B, ZM447439. Dual inhibition of survivin and Aurora B synergistically radiosensitized mesothelioma cells with a dose enhancement ratio of 2.55. This treatment resulted in increased formation of multinucleated cells after irradiation but did not increase levels of cleaved caspase 3. Conclusion: Inhibition of survivin and Aurora B induces mitotic cell arrest in mesothelioma cells after irradiation. These two proteins may be potential therapeutic targets for the enhancement of radiotherapy in malignant pleural mesothelioma.

  4. Arsenic-induced Aurora-A activation contributes to chromosome instability and tumorigenesis

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Han; Tseng, Ya-Shih; Yang, Chao-Chun; Kao, Yu-Ting; Sheu, Hamm-Ming; Liu, Hsiao-Sheng

    2013-11-01

    Arsenic may cause serious environmental pollution and is a serious industrial problem. Depending on the dosage, arsenic may trigger the cells undergoing either proliferation or apoptosis-related cell death. Because of lack of the proper animal model to study arsenic induced tumorigenesis, the accurate risk level of arsenic exposure has not been determined. Arsenic shows genotoxic effect on human beings who uptake water contaminated by arsenic. Chromosome aberration is frequently detected in arsenic exposure-related diseases and is associated with increased oxidative stress and decreased DNA repairing activity, but the underlying mechanism remains elusive. Aurora-A is a mitotic kinase, over-expression of Aurora-A leads to centrosome amplification, chromosomal instability and cell transformation. We revealed that Aurora-A is over-expressed in the skin and bladder cancer patients from blackfoot-disease endemic areas. Our cell line studies reveal that arsenic exposure between 0.5 μM and 1 μM for 2-7 days are able to induce Aurora-A expression and activation based on promoter activity, RNA and protein analysis. Aurora-A overexpression further increases the frequency of unsymmetrical chromosome segregation through centrosome amplification followed by cell population accumulated at S phase in immortalized keratinocyte (HaCaT) and uroepithelial cells (E7). Furthermore, Aurora-A over-expression was sustained for 1-4 weeks by chronic treatment of immortalized bladder and skin cells with NaAsO2. Aurora-A promoter methylation and gene amplification was not detected in the long-term arsenic treated E7 cells. Furthermore, the expression level of E2F1 transcription factor (E2F1) is increased in the presence of arsenic, and arsenic-related Aurora-A over-expression is transcriptionally regulated by E2F1. We further demonstrated that overexpression of Aurora-A and mutant Ha-ras or Aurora-A and mutant p53 may act additively to trigger arsenic-related bladder and skin cancer

  5. X-ray scanning of overhead aurorae from rockets

    NASA Technical Reports Server (NTRS)

    Barcus, J. R.; Goldberg, R. A.; Gesell, L. H.

    1981-01-01

    Two Nike Tomahawk rocket payloads were launched into energetic auroral events in September, 1976 to investigate the structure of these events, as well as their effects on the atmosphere. X-ray scintillation detectors with energy discrimination in four ranges were used to measure the deposition of bremsstrahlung produced X-rays within the stratosphere and mesosphere. Iterative computer techniques were used to reconstruct X-ray source maps at 100 km, taking atmospheric absorption effects into account. Payload 18.178 was launched on September 21st into an aurora having two distinct azimuthal regions of optical brightness. The X-ray scanner detected the same features, and overlays of the X-ray source maps on all-sky photographs showed spatial coincidence of the X-ray with optical features at the lower energies (below 40 keV). Payload 18.179 was launched September 23rd into an aurora with a more diffuse character. The optical structure did not coincide as well with the measured X-ray structure. There was also an indication of a two-component spectrum for each event, with the hard component originating in the more diffuse, optically faint regions.

  6. Current systems associated with Non-Conjugate Aurora

    NASA Astrophysics Data System (ADS)

    Rexer, Theresa; Østgaard, Nikolai; Reistad, Jone Peter; Magnus Laundal, Karl

    2015-04-01

    The main goal of the present study is twofold. First, we want to develop a solid method for identifying the field aligned currents related to the specific non-conjugate auroral features identified by Reistad et al. (2013) and Laundal et al. (2010). Secondly, by utilizing this method we explore the idea that the non-conjugate aurora can be explained by asymmetries in the field aligned current system in the two hemispheres (Østgaard and Laundal , 2012). By transforming ground magnetometer measurements from the SuperMAG network in both hemispheres to the coordinate system used by the VIS Earth and WIC cameras onboard the Polar and IMAGE satellites, we combine the two datasets. We present four non-conjugate auroral events were a current system associated with the observed aurora and the ground magnetometer measurements can be postulated. For two out of four events we can identify signatures attributred to asymmetric field aligned currents. Three factors stand out as important for the identification of these; the position of the ground magnetometer station in relation to the non-conjugate auroral feature, the spatial extension of the feature and its intensity compared to surrounding auroral features.

  7. Magnetosphere-Ionosphere Energy Interchange in the Electron Diffuse Aurora

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.; Glocer, Alex; Himwich, E. W.

    2014-01-01

    The diffuse aurora has recently been shown to be a major contributor of energy flux into the Earth's ionosphere. Therefore, a comprehensive theoretical analysis is required to understand its role in energy redistribution in the coupled ionosphere-magnetosphere system. In previous theoretical descriptions of precipitated magnetospheric electrons (E is approximately 1 keV), the major focus has been the ionization and excitation rates of the neutral atmosphere and the energy deposition rate to thermal ionospheric electrons. However, these precipitating electrons will also produce secondary electrons via impact ionization of the neutral atmosphere. This paper presents the solution of the Boltzman-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora, including the affiliated production of secondary electrons (E greater than 600 eV) and their ionosphere-magnetosphere coupling processes. In this article, we discuss for the first time how diffuse electron precipitation into the atmosphere and the associated secondary electron production participate in ionosphere-magnetosphere energy redistribution.

  8. Optical emissions and ionization profiles during an intense pulsating aurora

    SciTech Connect

    Sears, R.D.; Vondrak, R.R.

    1981-08-01

    Coordinated spectrophotometric and incoherent scatter radar measurements were made of an intense early-morning pulsating aurora at Chatanika, Alaska. Both instruments were operated simultaneously with temporal resolution of 1 s and were boresighted at geomagnetic zenith. The goals of the collaborative experimental were to determine the total energy flux E/sub t/ and the characteristic energy parameter ..cap alpha.. of the precipitating electrons on a time scale smaller than the pulsation duration and to investigate the response of the ionospheric electron density on a comparable time scale. The relationship between total energy flux and the characteristic energy parameter suggests that during these observations the pulsations were caused by a modulation of ..cap alpha.. rather than by a modulation of the total precipitating particle flux. The values of E/sub t/ and ..cap alpha.. derived from photometric data were used to model the electron density versus altitude in the ionosphere for comparison with the incoherent scatter radar measurements. Measured altitude profiles of ionization did not change significantly on the time scale of the pulsations. The E region maximum electron density typically was 7 x 10/sup 5/ at an altitude of 99 km. Variations in ionospheric conductivity were less than 15% on the pulsation time scale. These results suggest that a magnetospheric modulation mechanism is required to explain diffuse pulsating auroras.

  9. Ultraviolet spectroscopy of the Jovian and Saturnian auroras

    NASA Technical Reports Server (NTRS)

    Durrance, S. T.; Feldman, P. D.; Moos, H. W.

    1982-01-01

    The results of a series of IUE observations of the north polar aurora obtained during a substantial fraction of one complete rotation of Jupiter are presented. From these data a spectrum of the aurora with high signal to noise ratio, and a resolution of about 8 A was obtained, making possible the identification of many H2 Lyman and Werner bands. The spectrum is of sufficient quality to provide reliable quantative data for a comparison with the model atmosphere calculations. The lack of an observable absorption signature makes it possible to set an upper limit on the column density of CH4 and C2H6 above the auroral emissions and hence an upper limit on the primary particle energies. A comparison of this spectrum with a laboratory spectrum of discharge excited H2 shows a remarkable similarity. The results of several IUE observations of the full disk of Saturn are also examined. The exposures were of approximately 2 hours each, and the H2 Lyman and Werner bands were observed near the north pole in two of them.

  10. Knockdown of Aurora-B inhibits the growth of non-small cell lung cancer A549 cells

    PubMed Central

    YU, JING JING; ZHOU, LONG DIAN; ZHAO, TIAN TIAN; BAI, WEI; ZHOU, JING; ZHANG, WEI

    2015-01-01

    Elevated expression of Aurora-B affects cell apoptosis and proliferation in a variety of solid tumors. However, the role of Aurora-B has been poorly evaluated in non-small cell lung cancer (NSCLC). In the present study, it was found that Aurora-B was overexpressed in tissue specimens obtained from 174 patients with lung cancer. It was also demonstrated that knockdown of Aurora-B induces apoptosis and inhibits the growth of lung cancer A549 cells in vitro and in vivo. Furthermore, it was found that silencing Aurora-B decreased the activity of the phosphoinositide 3-kinase (PI3K)/AKT pathway. Therefore, it was concluded that knockdown of Aurora-B induces apoptosis and inhibits growth in NSCLC A549 cells, in addition to inhibiting the activity of the PI3K/AKT signaling pathway. Targeting Aurora-B may provide a novel target for lung cancer therapy. PMID:26622725

  11. A specific pharmacophore model of Aurora B kinase inhibitors and virtual screening studies based on it.

    PubMed

    Wang, Hui-Yuan; Li, Lin-Li; Cao, Zhi-Xing; Luo, Shi-Dong; Wei, Yu-Quan; Yang, Sheng-Yong

    2009-01-01

    In this study, 3D-pharmacophore models of Aurora B kinase inhibitors have been developed by using HipHop and HypoGen modules in Catalyst software package. The best pharmacophore model, Hypo1, which has the highest correlation coefficient (0.9911), consists of one hydrogen-bond acceptor, one hydrogen-bond donor, one hydrophobic aliphatic moiety and one ring aromatic feature. Hypo1 was validated by test set and cross-validation methods. And the specificity of Hypo1 to Aurora B inhibitors was examined with the use of selective inhibitors against Aurora B and its paralogue Aurora A. The results clearly indicate that Hypo1 can differentiate selective inhibitors of Aurora B from those of Aurora A, and the ring aromatic feature likely plays some important roles for the specificity of Hypo1. Then Hypo1 was used as a 3D query to screen several databases including Specs, NCI, Maybridge and Chinese Nature Product Database (CNPD) for identifying new inhibitors of Aurora B. The hit compounds were subsequently subjected to filtering by Lipinski's rule of five and docking studies to refine the retrieved hits, and some compounds selected from the top ranked hits have been suggested for further experimental assay studies. PMID:19152640

  12. Aurora candidates from the chronicle of Qíng dynasty in several degrees of relevance

    NASA Astrophysics Data System (ADS)

    Kawamura, Akito D.; Hayakawa, Hisashi; Tamazawa, Harufumi; Miyahara, Hiroko; Isobe, Hiroaki

    2016-08-01

    We present the result of a survey of sunspots and auroras in Qíngshǐgǎo (清史稿), a draft chronicle of Qíng dynasty, for the period of 1559-1912 CE. This is a sequel to a series of works surveying historical sunspot and aurora records, and providing online data to the scientific community regarding the attained results. In total of this Qíngshǐgǎo survey, we found 111 records of night-sky luminous events with such keywords as vapor (氣, qì), cloud (雲, yún), and light (光, guāng), which may indicate auroras as well as some other phenomena. Similarly, a keyword survey for sunspots was conducted, but no sunspot record was found. In comparison with the aurora records in the western world, we found that 14 of the 111 records have a corresponding record of simultaneous observation in the western world, and hence are very likely to be aurora. In order to investigate the likeliness of the remainder of the record being aurora, we calculated the lunar age and the phase of a solar cycle for each record. After these calculations, a notable fraction of these records clustered near the full moon were to be found statistically doubtful in considerations with atmospheric optics; meanwhile, a few records of observations near the new moon could be more likely interpreted as being auroras, including three records during the Maunder minimum.

  13. Proton Aurora Dynamics in Response to the IMF and Solar Wind Variations

    NASA Technical Reports Server (NTRS)

    Chang, S.; Mende, S.; Frey, H.; Gallagher, D. L.; Lepping, R. P.; Six, N. Frank (Technical Monitor)

    2002-01-01

    On May 23, 2000, proton auroras observed by IMAGE (Imager for Magnetopause to Aurora Global Exploration) FUV (Far Ultraviolet) on the dayside were very dynamic. Auroral pattern in the cusp is well correlated with Interplanetary Magnetic Field (IMF) and solar wind parameters. When IMF were northward, cusp proton aurora appeared at high latitude poleward from the auroral oval. A high-latitude proton aurora brightened after solar wind ion temperature increased and it disappeared after IMF turned southward. Under the southward IMF condition, auroral activity occurred only in the dayside auroral oval. As IMF $B_z$ reverted to northward, cusp proton aurora reappeared at high latitude. The magnetic local time of the cusp proton aurora changes with the IMF $B_y$ polarity, consistent with previous reports. These results suggest an upstream source of the high-latitude cusp proton aurora for this event. One possible explanation is that bow shock energetic ions are transported into the cusp via the high-latitude magnetic merging process to induce optical emissions in the ionosphere.

  14. A coordinated X-ray and EUV study of the Jovian aurora

    NASA Astrophysics Data System (ADS)

    Kraft, Ralph; Kimura, Tomoki; Elsner, Ronald; Branduardi-Raymont, Graziella; Gladstone, Randall; Badman, Sarah; Ezoe, Yuichiro; Murakami, Go; Murray, Stephen; Rodiger, Elke; Tsuchiya, Fuminori; Yamazaki, Atsushi; Yoshikawa, Ichiro; Yoshioka, Kazuo

    2015-04-01

    We present results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument and twice by XMM-Newton for roughly 12 hours per observation. The goal of this campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  15. Aurora kinase inhibitors synergize with paclitaxel to induce apoptosis in ovarian cancer cells

    PubMed Central

    Scharer, Christopher D; Laycock, Noelani; Osunkoya, Adeboye O; Logani, Sanjay; McDonald, John F; Benigno, Benedict B; Moreno, Carlos S

    2008-01-01

    Background A large percentage of patients with recurrent ovarian cancer develop resistance to the taxane class of chemotherapeutics. While mechanisms of resistance are being discovered, novel treatment options and a better understanding of disease resistance are sorely needed. The mitotic kinase Aurora-A directly regulates cellular processes targeted by the taxanes and is overexpressed in several malignancies, including ovarian cancer. Recent data has shown that overexpression of Aurora-A can confer resistance to the taxane paclitaxel. Methods We used expression profiling of ovarian tumor samples to determine the most significantly overexpressed genes. In this study we sought to determine if chemical inhibition of the Aurora kinase family using VE-465 could synergize with paclitaxel to induce apoptosis in paclitaxel-resistant and sensitive ovarian cancer cells. Results Aurora-A kinase and TPX2, an activator of Aurora-A, are two of the most significantly overexpressed genes in ovarian carcinomas. We show that inhibition of the Aurora kinases prevents phosphorylation of a mitotic marker and demonstrate a dose-dependent increase of apoptosis in treated ovarian cancer cells. We demonstrate at low doses that are specific to Aurora-A, VE-465 synergizes with paclitaxel to induce 4.5-fold greater apoptosis than paclitaxel alone in 1A9 cells. Higher doses are needed to induce apoptosis in paclitaxel-resistant PTX10 cells. Conclusion Our results show that VE-465 is a potent killer of taxane resistant ovarian cancer cells and can synergize with paclitaxel at low doses. These data suggest patients whose tumors exhibit high Aurora-A expression may benefit from a combination therapy of taxanes and Aurora-A inhibition. PMID:19077237

  16. MLN-8237: A dual inhibitor of aurora A and B in soft tissue sarcomas

    PubMed Central

    Nair, Jayasree S.; Schwartz, Gary K.

    2016-01-01

    Aurora kinases have become an attractive target in cancer therapy due to their deregulated expression in human tumors. Liposarcoma, a type of soft tissue sarcoma in adults, account for approximately 20% of all adult soft tissue sarcomas. There are no effective chemotherapies for majority of these tumors. Efforts made to define the molecular basis of liposarcomas lead to the finding that besides the amplifications of CDK4 and MDM2, Aurora Kinase A, also was shown to be overexpressed. Based on these as well as mathematic modeling, we have carried out a successful preclinical study using CDK4 and IGF1R inhibitors in liposarcoma. MLN8237 has been shown to be a potent and selective inhibitor of Aurora A. MLN-8237, as per our results, induces a differential inhibition of Aurora A and B in a dose dependent manner. At a low nanomolar dose, cellular effects such as induction of phospho-Histone H3 (Ser10) mimicked as that of the inhibition of Aurora kinase A followed by apoptosis. However, micromolar dose of MLN-8237 induced polyploidy, a hallmark effect of Aurora B inhibition. The dose dependent selectivity of inhibition was further confirmed by using siRNA specific inhibition of Aurora A and B. This was further tested by time lapse microscopy of GFP-H2B labelled cells treated with MLN-8237. LS141 xenograft model at a dose of 30 mg/kg also showed efficient growth suppression by selective inhibition of Aurora Kinase A. Based on our data, a dose that can target only Aurora A will be more beneficial in tumor suppression. PMID:26887042

  17. Diffuse, Monoenergetic, Broadband (wave) and Ion Aurora: Results from a New Generation Precipitation Model

    NASA Astrophysics Data System (ADS)

    Newell, Patrick; Sotirelis, Thomas; Wing, Simon

    We introduce an auroral precipitation model which separately categorizes the discrete aurora and both the electron and ion diffuse aurora. The discrete aurora includes acceleration by two distinct physical mechanisms, namely quasi-static electric fields, producing monoenergetic peaks, and dispersive Alfvén waves, producing broadband electron acceleration. The new model is parameterized by functional fits to solar wind driving, with each MLAT and MLT bin sepa-rately fitted, permitting the first comprehensive comparison of the hemispheric contribution by auroral type. The diffuse aurora is surprisingly dominant, constituting 84 pct of the energy flux into the ionosphere during conditions of low solar wind driving (63 pct e-, 21 pct ions). The diffuse aurora is not quiescent, tripling in power from low to high solar wind driving conditions. Even under the latter condition, the diffuse aurora contains 71 pct of the hemispheric energy flux (57 pct e-, 14 pct ions). Monoenergetic aurora contributes more energy flux than does broadband acceleration signatures. However the broadband aurora rises fastest with activity, increasing by a factor of 8.0 from low to high driving. Seasonal dependence is investigated. Dayside and nightside variations are separately considered, as are conditions of low and high solar wind driving. Several clear patterns emerge. One is that the dayside tends to maximize precipitation in the summer, and much more so for low solar wind driving. Nightside precipita-tion is higher in the winter, and much more so for high solar wind driving. Dayside effects are strongest in number flux, and stronger in diffuse aurora than accelerated aurora. The ease of ion entry through the summer cusp, along with the constraints of charge quasi-neutrality, and the rise in dayside currents in the summer hemisphere adequately explains much (perhaps all) of the dayside behavior. Nightside effects are more apparent in energy flux, with the winter/summer ratio of

  18. Jupiter's north and south polar aurorae with IUE data

    NASA Technical Reports Server (NTRS)

    Livengood, T. A.; Moos, H. W.

    1990-01-01

    Observations of Jupiter's auroral H2 emissions with the IUE spacecraft, from 1978 through 1990, show that aurorae at the two poles are similar in several respects: (1) emission intensity is modulated with magnetic longitude, north peak emission at lambda (III) (1965) 200 deg, south peak at (1965) about 20 deg; (2) emission intensity and degree of modulation are comparable for both poles; and (3) attenuation by hydrocarbons varies in phase with the intensity, peak attenuation coinciding approximately with peak emission. Increases in the hydrocarbon column are an indicator of either enhanced penetration depth and, thus, energy of the auroral primaries, or of increases in the high-altitude hydrocarbon content caused by modification of the local atmosphere.

  19. The charge spectrum of positive ions in a hydrogen aurora

    NASA Technical Reports Server (NTRS)

    Lynch, J.; Pulliam, D.; Leach, R.; Scherb, F.

    1976-01-01

    An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation.

  20. The Aurora kinase inhibitors in cancer research and therapy.

    PubMed

    Cicenas, Jonas

    2016-09-01

    Compounds that affect enzymatic function of kinases are valuable for the understanding of the complex biochemical processes in cells. Aurora kinases (AURKs) play a key role in the control of the mitosis. These kinases are frequently deregulated in different human cancers: overexpression, amplifications, translocations and deletions were reported in many cancer cell lines as well as patient tissues. These findings steered a rigorous hunt for small-molecule AURK inhibitors not only for research purposes as well as for therapeutic uses. In this review, we describe a number of AURK inhibitors and their use in cancer research and/or therapy. We hope to assist researchers and clinicians in deciding which inhibitor is most appropriate for their specific purpose. The review will also provide a broad overview of the clinical studies performed with some of these inhibitors (if such studies have been performed). PMID:26932147

  1. Limit on rotational energy available to excite Jovian aurora

    NASA Technical Reports Server (NTRS)

    Eviatar, A.; Siscoe, G. L.

    1980-01-01

    There is a fundamental relationship between the power that is extracted from Jupiter's rotation to drive magnetospheric processes and the rate at which mass is injected into the Io plasma torus. Half of this power is consumed by bulk motion of the plasma and the other half represents an upper limit on the energy from rotation available for dissipation and in particular to excite the Jovian aurora. Since the rotation of the planet is the only plausible source of energy, the power inferred from the observed auroral intensities requires a plasma injection rate of 2.6 x 10 to the 29th AMU/sec or greater. This in turn leads to a residence time of a torus particle of 48 days or less. These results raise doubts about the applicability of equilibrium thermodynamics to the determination of plasma parameters in the Io torus.

  2. Idealized model of polar cap currents, fields, and auroras

    NASA Technical Reports Server (NTRS)

    Cornwall, J. M.

    1985-01-01

    During periods of northward Bz, the electric field applied to the magnetosphere is generally opposite to that occurring during southward Bz and complicated patterns of convection result, showing some features reversed in comparison with the southward Bz case. A study is conducted of a simple generalization of early work on idealized convection models, which allows for coexistence of sunward convection over the central polar cap and antisunward convection elsewhere in the cap. The present model, valid for By approximately 0, has a four-cell convection pattern and is based on the combination of ionospheric current conservation with a relation between parallel auroral currents and parallel potential drops. Global magnetospheric issues involving, e.g., reconnection are not considered. The central result of this paper is an expression giving the parallel potential drop for polar cap auroras (with By approximately 0) in terms of the polar cap convection field profile.

  3. On the Stenbaek-Nielsen and Hallinan pulsating auroras

    SciTech Connect

    D'Angelo, N. )

    1991-02-01

    Stenbaek-Nielsen and Hallinan (1979) argued that if the pulsating auroras are caused by precipitating electrons, the data suggest that noncollisional interactions, localized in the lower E region (90-107 km), where most of the pulsations are observed, may play a dominant role in thermalizing the particles. They also stated that one type of process that comes to mind is a wave-particle interaction in the ionosphere. If, through one or more instabilities, waves grow at the expense of beam energy and, in turn, energize ambient electrons, the energized ambient electrons could ionize the background gas and, in process, produce luminosity. The exceptionally thin pulsating auroral patches observed by Stenbaek-Nielsen and Hallinan (1979) may be caused by an ionization instability occurring at the end of the range of precipitating electrons. A comparison is made to laboratory results reported by Johnson et al. (1990).

  4. Artificial auroras in the upper atmosphere. II - Imaging results

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Burch, J. L.; Swenson, G. R.; Aamodt, E. K.; Geller, S. P.; Rairden, R. L.; Hassler, P. L.

    1993-01-01

    On the ATLAS 1 mission (STS-45, launched March 24, 1992) two experiments, AEPI (Atmospheric Emissions Photometric Imaging) and SEPAC (Space Experiments with Particle Accelerators) performed the first of a series of active experiments intended to probe the atmosphere, ionosphere and magnetosphere with electron beams. The luminous artificial aurora generated by the electron beam interaction was detected and measured by AEPI both in white light and in a narrow wavelength band at 427.8 nm (peak intensity 5 kR). Modelling calculation showed that there was a significant contribution from emissions originating near the spacecraft. The spatial intensity distribution of the observed auroral patch is consistent with emission contribution from both high and low altitude regions. An extended tail in the direction of the shuttle wake was observed in the 427.8 nm channel, consistent with a decay time associated with the dissipation of the hot electron plasma.

  5. Artificial auroras in the upper atmosphere: 2. Imaging results

    SciTech Connect

    Mende, S.B.; Swenson, G.R.; Aamodt, E.K.; Geller, S.P.; Rairden, R.L. ); Burch, J.L. ); Hassler, P.L. )

    1993-03-19

    On the ATLAS 1 mission (STS-45, launched March 24, 1992) two experiments, AEPI (Atmospheric Emissions Photometric Imaging) and SEPAC (Space Experiments with Particle Accelerators) performed the first experiment in a series of active experiments intended to probe the atmosphere, ionosphere and magnetosphere with electron beams. The luminous artificial aurora generated by the electron beam interaction was detected and measured by AEPI both in white light and in a narrow wavelength band at 427.8 nm (peak intensity 5 kR). Modelling calculation showed that there was a significant contribution from emissions originating near the spacecraft. The spatial intensity distribution of the observed auroral patch is consistent with emission contribution from both high and low altitude regions. An extended tail in the direction of the shuttle wake was observed in the 427.8 nm channel, consistent with a decay time associated with the dissipation of the hot electron plasma. 19 refs., 4 figs., 2 tabs.

  6. Aurora on Uranus - A Faraday disc dynamo mechanism

    NASA Astrophysics Data System (ADS)

    Hill, T. W.; Dessler, A. J.; Rassbach, M. E.

    1983-10-01

    A mechanism is proposed whereby the solar wind flowing past the magnetosphere of Uranus causes a Faraday disk dynamo topology to be established and power to be extracted from the kinetic energy of rotation of Uranus. An immediate consequence of this dynamo is the generation of Birkeland currents that flow in and out of the sunlit polar cap with the accompanying production of polar aurora. The power extracted from planetary rotation is calculated as a function of planetary dipole magnetic moment and the ionospheric conductivity of Uranus. For plausible values of ionospheric conductivity, the observed auroral power requires a magnetic moment corresponding to a surface equatorial field of the order of 4 Gauss, slightly larger than the value 1.8 Gauss given by the empirical 'magnetic Bodes law'.

  7. The response of head and neck squamous cell carcinoma to cetuximab treatment depends on Aurora kinase A polymorphism

    PubMed Central

    Baumann, Alexander; Huhn, Maximilian; Wirth, Markus; Reiter, Rudolf; Rudelius, Martina; Piontek, Guido; Brockhoff, Gero

    2014-01-01

    Objectives The aim of this study was to evaluate the efficiency of cetuximab-based anti-EGFR treatment and Aurora kinase A / B knockdown as a function of Aurora kinase polymorphism in HNSCC cell lines. Materials and methods First, protein expression of Aurora kinase A / B and EGFR and Aurora kinase A polymorphism were studied in tumour samples. The survival and proliferation of Aurora kinase A homo- (Cal27) and heterozygous (HN) HNSCC cell lines was evaluated using a colony formation assay and a flow cytometric assay. Also, aneuploidy was determined. EGFR signalling pathway were visualised by western blotting. Results Immunohistochemistry revealed the overexpression of Aurora kinase A / B in HNSCC. The knockdown of each kinase caused a significant decrease in clonogenic survival, independent of Aurora kinase A polymorphism. In contrast, cetuximab treatment impaired clonogenic survival only in the Aurora kinase A-homozygous cell line (Cal27). Conclusion This study provides in vitro evidence for the predictive value of Aurora kinase A polymorphism in the efficiency of cetuximab treatment. Resistance to cetuximab treatment can be overcome by simultaneous Aurora kinase A/B knockdown. PMID:24980817

  8. Secular variation of the aurora for the past 500 years

    SciTech Connect

    Silverman, S.M. )

    1992-11-01

    Direct observations of the Sun exist only since about 1700. Understanding of long-term solar variability thus depends on proxy data, such as visual auroral observations, measurements of magnetic activity, and the radiocarbon record. These also give information on the interaction between the solar wind, interplanetary field, and terrestrial magnetosphere, as well as, for the radiocarbon record, heliospheric conditions. This paper uses a data base of visual auroral observations for a period of about 500 years, from 1450 to 1948, comprising about 45,000 observations, in addition to the well-known sunspot series and the magnetic activity index [ital aa], from 1868 to 1990. The secular variation of the aurora is examined and compared to sunspot data and magnetic activity data. Blackman-Tukey power spectra are used to determine periodicities. The study confirms the variability of the periodicities in frequency and amplitude. The 11.1-year cycle disappears during the Mounder minimum and at the end of the eighteenth and beginning of the nineteenth century. While the 11.1-year period is normally strongly dominant for sunspots, other shorter periods become important for auroras and magnetic activity. Prolonged solar activity minima are clearly evident. In addition to the known Sporer, Mounder, Dalton, and 1901-1913 minima, a previously unrecognized minimum about 1765 is clearly evident in the data. Comparison of the depth of these minima shows that the Dalton minimum may rival the Mounder minimum in importance. Combining the polar data base with that of mid-latitudes provides a globally comprehensive historical record of auroral occurrence. The data provide confirmation of the anticorrelation of auroral occurrence in the polar regions with sunspot activity. The data provide a basis for understanding the variation over time of the general magnetic field of the Sun, in particular the polar field. 59 refs., 29 figs.

  9. Forecasting auroras from regional and global magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Kauristie, Kirsti; Myllys, Minna; Partamies, Noora; Viljanen, Ari; Peitso, Pyry; Juusola, Liisa; Ahmadzai, Shabana; Singh, Vikramjit; Keil, Ralf; Martinez, Unai; Luginin, Alexej; Glover, Alexi; Navarro, Vicente; Raita, Tero

    2016-06-01

    We use the connection between auroral sightings and rapid geomagnetic field variations in a concept for a Regional Auroral Forecast (RAF) service. The service is based on statistical relationships between near-real-time alerts issued by the NOAA Space Weather Prediction Center and magnetic time derivative (dB/dt) values measured by five MIRACLE magnetometer stations located in Finland at auroral and sub-auroral latitudes. Our database contains NOAA alerts and dB/dt observations from the years 2002-2012. These data are used to create a set of conditional probabilities, which tell the service user when the probability of seeing auroras exceeds the average conditions in Fennoscandia during the coming 0-12 h. Favourable conditions for auroral displays are associated with ground magnetic field time derivative values (dB/dt) exceeding certain latitude-dependent threshold values. Our statistical analyses reveal that the probabilities of recording dB/dt exceeding the thresholds stay below 50 % after NOAA alerts on X-ray bursts or on energetic particle flux enhancements. Therefore, those alerts are not very useful for auroral forecasts if we want to keep the number of false alarms low. However, NOAA alerts on global geomagnetic storms (characterized with Kp values > 4) enable probability estimates of > 50 % with lead times of 3-12 h. RAF forecasts thus rely heavily on the well-known fact that bright auroras appear during geomagnetic storms. The additional new piece of information which RAF brings to the previous picture is the knowledge on typical storm durations at different latitudes. For example, the service users south of the Arctic Circle will learn that after a NOAA ALTK06 issuance in night, auroral spotting should be done within 12 h after the alert, while at higher latitudes conditions can remain favourable during the next night.

  10. Aurora-A modulates MMP-2 expression via AKT/NF-κB pathway in esophageal squamous cell carcinoma cells.

    PubMed

    Wang, Xiaoxia; Li, Xiaozhong; Li, Chaohui; He, Chun; Ren, Benhong; Deng, Qing; Gao, Wei; Wang, Binquan

    2016-06-01

    Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies. It is necessary to identify new markers for predicting tumor progression and therapeutic molecular targets. It has been reported that overexpressions of Aurora-A and matrix metalloproteinases 2 (MMP-2) may promote the malignant development of tumor. However, the relationship between Aurora-A and MMP-2 expression in tumor patients has not been investigated. In addition, the underlying mechanisms that Aurora-A regulates MMP-2 expression are still not fully elucidated. In this study, we demonstrated that Aurora-A and MMP-2 were overexpressed in ESCC tissues compared with paired normal adjacent tissues (P < 0.0001). Overexpression of Aurora-A was associated with the lymph node metastasis of ESCC (P = 0.01). Significantly, Aurora-A protein expression was positively correlated with MMP-2 protein expression in ESCC tissues (r = 0.66, P < 0.0001) as well as in ESCC cell lines. The level of Aurora-A expression was also positively correlated with the invasion capability of ESCC cells. Furthermore, Aurora-A overexpression significantly increased ESCC cell invasion by the upregulation of MMP-2 expression. In addition, Aurora-A overexpression promoted nuclear factor-kappaB (NF-κB) activation, and Aurora-A-mediated MMP-2 upregulation was abrogated by NF-κB inhibitor. Further analysis showed that activation of NF-κB was severely attenuated by AKT inhibitor in cells overexpressing Aurora-A. Taken together, these data indicate that Aurora-A overexpression upregulates MMP-2 expression through activating AKT/NF-κB signaling pathway in ESCC cells. These findings reveal that Aurora-A may be used as an important indicator for the judgment of malignant behavior of ESCC, and may be an attractive target for cancer therapy. PMID:27125974

  11. Auroras Observed in Portugal in Late 18th Century Obtained from Printed and Manuscript Meteorological Observations

    NASA Astrophysics Data System (ADS)

    Vaquero, José M.; Trigo, Ricardo M.

    2005-09-01

    We present a new catalogue of observations of the aurora borealis at Lisbon, i.e., at low-latitudes, in the late 18th century by Jacob Præ torius and Henrique Schulze, two German artillery officers. Dates of 18 auroras compiled by Præ torius and Schulze are compared with those published in other catalogues for that period. The number of annual auroras observed by the two Germans is then compared with two indices of solar activity showing a very good level of consistency between all time series. Finally, we have assessed the number of auroras observed taking into consideration the phase of the lunar cycle and the geomagnetic latitude of Lisbon.

  12. View of the southern aurora, luminous bands or streamers of light

    NASA Technical Reports Server (NTRS)

    1973-01-01

    An excellent view of the southern aurora, luminous bands or streamers of light, in the Southern Hemisphere, as photographed from the Skylab space station in Earth orbit. The space station was moving into the sunlight when this picture was taken. This view is near the edge of the aurora cap. The surface of the Earth is in the foreground. The permanent aurora over the South Pole is in the background. Scientist-Astronaut Owen K. Garriott, Skylab 3 science pilot, took this photograph with a hand-held 35mm Nikon camera, with a four-second exposure at f/1.2, using high speed Ektachrome film. Because auroras are caused by solar activity, they occur at the same time in the Northern and Southern hemispheres.

  13. Bistability of a coupled Aurora B kinase-phosphatase system in cell division.

    PubMed

    Zaytsev, Anatoly V; Segura-Peña, Dario; Godzi, Maxim; Calderon, Abram; Ballister, Edward R; Stamatov, Rumen; Mayo, Alyssa M; Peterson, Laura; Black, Ben E; Ataullakhanov, Fazly I; Lampson, Michael A; Grishchuk, Ekaterina L

    2016-01-01

    Aurora B kinase, a key regulator of cell division, localizes to specific cellular locations, but the regulatory mechanisms responsible for phosphorylation of substrates located remotely from kinase enrichment sites are unclear. Here, we provide evidence that this activity at a distance depends on both sites of high kinase concentration and the bistability of a coupled kinase-phosphatase system. We reconstitute this bistable behavior and hysteresis using purified components to reveal co-existence of distinct high and low Aurora B activity states, sustained by a two-component kinase autoactivation mechanism. Furthermore, we demonstrate these non-linear regimes in live cells using a FRET-based phosphorylation sensor, and provide a mechanistic theoretical model for spatial regulation of Aurora B phosphorylation. We propose that bistability of an Aurora B-phosphatase system underlies formation of spatial phosphorylation patterns, which are generated and spread from sites of kinase autoactivation, thereby regulating cell division. PMID:26765564

  14. Design and synthesis of novel benzoxazole analogs as Aurora B kinase inhibitors.

    PubMed

    An, Ying; Lee, Eun; Yu, Yeongji; Yun, Jieun; Lee, Myeong Youl; Kang, Jong Soon; Kim, Woo-Young; Jeon, Raok

    2016-07-01

    A novel series of benzoxazole analogs was designed and synthesized, and their inhibitory activities against Aurora kinases were evaluated. Some of the tested compounds exhibited a promising activity with respect to the inhibition of Aurora B kinase. A structure-activity relationship study indicated that linker length, regiochemistry, and halogen substitution play important roles in kinase inhibitory potency. The binding modes between representative compounds and Aurora kinases were interpreted through a molecular docking study to explain the inhibitory activity and selectivity for Aurora A and B kinases. Compounds 13l and 13q also show an antiproliferative effect on the human tumor cell lines in a dose-dependent manner. The most potent 13q demonstrated good efficacy in the prostate cancer PC-3 tumor xenograft model. PMID:27209235

  15. Recent advances in the development of Aurora kinases inhibitors in hematological malignancies

    PubMed Central

    Choudary, Iqra; Barr, Paul M.; Friedberg, Jonathan

    2015-01-01

    Over the last two decades, since the discovery of Drosophila mutants in 1995, much effort has been made to understand Aurora kinase biology. Three mammalian subtypes have been identified thus far which include the Aurora A, B and C kinases. These regulatory proteins specifically work at the cytoskeleton and chromosomal structures between the kinetochores and have vital functions in the early phases of the mitotic cell cycle. Today, there are multiple phase I and phase II clinical trials as well as numerous preclinical studies taking place looking at Aurora kinase inhibitors in both hematologic and solid malignancies. This review focuses on the preclinical and clinical development of Aurora kinase inhibitors in hematological malignancy and discusses their therapeutic potential. PMID:26622997

  16. The Importance of Postsecondary Training for Welfare To Work: Initiatives at the Community College of Aurora.

    ERIC Educational Resources Information Center

    Higgins, Daniela

    2001-01-01

    Argues that academic skills, in addition to job skills, are crucial for taking people off the welfare rolls. Discusses postsecondary training programs and services for welfare recipients at the Community College of Aurora in Colorado. (NB)

  17. Aurora B inhibitor barasertib prevents meiotic maturation and subsequent embryo development in pig oocytes.

    PubMed

    Ju, Shiqiang; Peng, Xu; Yang, Xiaoliu; Sozar, Sparksi; Muneri, Caroline W; Xu, Yaping; Chen, Changchao; Cui, Panpan; Xu, Weichao; Rui, Rong

    2016-07-15

    Barasertib, a highly selective Aurora B inhibitor, has been widely used in a variety of cells to investigate the role of Aurora B kinase, which has been implicated in various functions in the mitotic process. However, effects of barasertib on the meiotic maturation process are not fully understood, particularly in porcine oocyte meiotic maturation. In the present study, the effects of barasertib on the meiotic maturation and developmental competence of pig oocytes were investigated, and the possible roles of Aurora B were also evaluated in porcine oocytes undergoing meiosis. Initially, we examined the expression and subcellular localization of Aurora B using Western blot analysis and immunofluorescent staining. Aurora B was found to express and exhibit specific dynamic intracellular localization during porcine oocyte meiotic maturation. Aurora B was observed around the chromosomes after germinal vesicle breakdown. Then it was transferred to the spindle region after metaphase I stage, and was particularly concentrated at the central spindles at telophase I stage. barasertib treatment resulted in the failure of polar body extrusion in pig oocytes, with a larger percentage of barasertib-treated oocytes remaining at the pro-metaphase I stage. Additional results reported that barasertib treatment had no effect on chromosome condensation but resulted in a significantly higher percentage of the treated oocytes with aberrant spindles and misaligned chromosomes during the first meiotic division. In addition, inhibition of Aurora B with lower concentrations of barasertib during pig oocyte meiotic maturation decreased the subsequent embryo developmental competence. Thus, these results illustrate that barasertib has significant effects on porcine oocyte meiotic maturation and subsequent development through Aurora B inhibition, and this regulation is related to its effects on spindle formation and chromosome alignment during the first meiotic division in porcine oocytes. PMID

  18. MLN8054, A Small Molecule Inhibitor of Aurora Kinase A, Sensitizes Androgen-Resistant Prostate Cancer to Radiation;Aurora kinase A; MLN8054; Prostate cancer; Radiation

    SciTech Connect

    Moretti, Luigi; Niermann, Kenneth; Schleicher, Stephen; Giacalone, Nicholas J.; Varki, Vinod; Kim, Kwang Woon; Kopsombut, Prapaporn; Jung, Dae Kwang; Bo Lu

    2011-07-15

    Purpose: To determine whether MLN8054, an Aurora kinase A (Aurora-A) inhibitor causes radiosensitization in androgen-insensitive prostate cancer cells in vitro and in vivo. Methods and Materials: In vitro studies consisted of culturing PC3 and DU145 prostate cancer cells and then immunoblotting Aurora A and phospho-Aurora A after radiation and/or nocodazole with MLN8054. Phases of the cell cycle were measured with flow cytometry. PC3 and DU145 cell lines were measured for survival after treatment with MLN8054 and radiation. Immunofluorescence measured {gamma}-H2AX in the PC3 and DU145 cells after treatment. In vivo studies looked at growth delay of PC3 tumor cells in athymic nude mice. PC3 cells grew for 6 to 8 days in mice treated with radiation, MLN8054, or combined for 7 more days. Tumors were resected and fixed on paraffin and stained for von Willebrand factor, Ki67, and caspase-3. Results: In vitro inhibition of Aurora-A by MLN8054 sensitized prostate cancer cells, as determined by dose enhancement ratios in clonogenic assays. These effects were associated with sustained DNA double-strand breaks, as evidenced by increased immunofluorescence for {gamma}-H2AX and significant G2/M accumulation and polyploidy. In vivo, the addition of MLN8054 (30 mg/kg/day) to radiation in mouse prostate cancer xenografts (PC3 cells) significantly increased tumor growth delay and apoptosis (caspase-3 staining), with reduction in cell proliferation (Ki67 staining) and vascular density (von Willebrand factor staining). Conclusion: MLN8054, a novel small molecule Aurora-A inhibitor showed radiation sensitization in androgen-insensitive prostate cancer in vitro and in vivo. This warrants the clinical development of MLN8054 with radiation for prostate cancer patients.

  19. Atmospheric response in aurora experiment: Observations of E and F region neutral winds in a region of postmidnight diffuse aurora

    NASA Technical Reports Server (NTRS)

    Larsen, M. F.; Marshall, T. R.; Mikkelsen, I. S.; Emery, B. A.; Christensen, A.; Kayser, D.; Hecht, J.; Lyons, L.; Walterscheid, R.

    1995-01-01

    The goal of the Atmospheric Response in Aurora (ARIA) experiment carried out at Poker Flat, Alaska, on March 3, 1992, was to determine the response of the neutral atmosphere to the long-lived, large-scale forcing that is characteristic of the diffuse aurora in the post midnight sector. A combination of chemical release rocket wind measurements, instrumented rocket composition measurements, and ground-based optical measurements were used to characterize the response of the neutral atmosphere. The rocket measurements were made at the end of a 90-min period of strong Joule heating. We focus on the neutral wind measurements made with the rocket. The forcing was determined by running the assimilated mapping of ionospheric electrodynamics (AMIE) analysis procedure developed at the National Center for Atmospheric Research. The winds expected at the latitude and longitude of the experiment were calculated using the spectral thermospheric general circulation model developed at the Danish Meteorological Institute. Comparisons of the observations and the model suggest that the neutral winds responded strongly in two height ranges. An eastward wind perturbation of approximately 100 m/s developed between 140 and 200 km altitude with a peak near 160 km. A southwestward wind with peak magnitude of approximately 150 m/s developed near 115 km altitude. The large amplitude winds at the lower altitude are particularly surprising. They appear to be associated with the upward propagating semidiurnal tide. However, the amplitude is much larger than predicted by any of the tidal models, and the shear found just below the peak in the winds was nominally unstable with a Richardson number of approximately 0.08.

  20. Relationship between Pulsating Aurora and Small-scale Field-Aligned Current Systems

    NASA Astrophysics Data System (ADS)

    Gillies, D. M.; Knudsen, D. J.; Donovan, E.; Kabirzadeh, R.

    2014-12-01

    Field-aligned currents derived from CHAMP satellite overpasses were compared to THEMIS ground-based all-sky camera array. Two separate conjunctions were studied in detail. The primary focus of this study was to investigate FAC derived from magnetometer measurements obtained by CHAMP collocated with various auroral phenomena. Two types of aurora were studied in detail: pulsating aurora and diffuse aurora occurring equatorward ward of an established auroral arc. We found that pulsating aurora exhibited low levels of fluctuating field aligned currents alternating between +/- 1 μA/m2 for the duration of the conjunction. We found similar behaviour for diffuse aurora equatorward of stable auroral arc events. Upon entering the region of diffuse aurora CHAMP recorded an alternating current fluctuating between +/- 5 μA/m2. High resolution data confirmed this alternating current structure as well as the presence of small scale arc structure seen by larger, small time scale amplitude fluctuations similar to that seen in the auroral arcs. These results show that electrical currents in diffuse and pulsating auroral structures are relevant.

  1. Co-inhibition of polo-like kinase 1 and Aurora kinases promotes mitotic catastrophe.

    PubMed

    Li, Jingjing; Hong, Myung Jin; Chow, Jeremy P H; Man, Wing Yu; Mak, Joyce P Y; Ma, Hoi Tang; Poon, Randy Y C

    2015-04-20

    Mitosis is choreographed by a number of protein kinases including polo-like kinases and Aurora kinases. As these kinases are frequently dysregulated in cancers, small-molecule inhibitors have been developed for targeted anticancer therapies. Given that PLK1 and Aurora kinases possess both unique functions as well as co-regulate multiple mitotic events, whether pharmacological inhibition of these kinases together can enhance mitotic catastrophe remains an outstanding issue to be determined. Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536). We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells. Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells. These observations underscore the mechanism and potential benefits of targeting PLK1 and Aurora kinases to induce mitotic catastrophe in cancer cells. PMID:25871386

  2. Mechanism of action and therapeutic efficacy of Aurora kinase B inhibition in MYC overexpressing medulloblastoma

    PubMed Central

    Faria, Claudia; Picard, Daniel; Shih, David; Raynaud, Denis; Leadly, Michael; MacKenzie, Danielle; Bryant, Melissa; Bebenek, Matthew; Smith, Christian A.; Taylor, Michael D.; Huang, Annie; Rutka, James T.

    2015-01-01

    Medulloblastoma comprises four molecular subgroups of which Group 3 medulloblastoma is characterized by MYC amplification and MYC overexpression. Lymphoma cells expressing high levels of MYC are susceptible to apoptosis following treatment with inhibitors of mitosis. One of the key regulatory kinases involved in multiple stages of mitosis is Aurora kinase B. We hypothesized that medulloblastoma cells that overexpress MYC would be uniquely sensitized to the apoptotic effects of Aurora B inhibition. The specific inhibition of Aurora kinase B was achieved in MYC-overexpressing medulloblastoma cells with AZD1152-HQPA. MYC overexpression sensitized medulloblastoma cells to cell death upon Aurora B inhibition. This process was found to be independent of endoreplication. Using both flank and intracranial cerebellar xenografts we demonstrate that tumors formed from MYC-overexpressing medulloblastoma cells show a response to Aurora B inhibition including growth impairment and apoptosis induction. Lastly, we show the distribution of AZD1152-HQPA within the mouse brain and the ability to inhibit intracranial tumor growth and prolong survival in mice bearing tumors formed from MYC-overexpressing medulloblastoma cells. Our results suggest the potential for therapeutic application of Aurora kinase B inhibitors in the treatment of Group 3 medulloblastoma. PMID:25739120

  3. Co-inhibition of polo-like kinase 1 and Aurora kinases promotes mitotic catastrophe

    PubMed Central

    Li, Jingjing; Hong, Myung Jin; Chow, Jeremy P.H.; Man, Wing Yu; Mak, Joyce P.Y.; Ma, Hoi Tang; Poon, Randy Y.C.

    2015-01-01

    Mitosis is choreographed by a number of protein kinases including polo-like kinases and Aurora kinases. As these kinases are frequently dysregulated in cancers, small-molecule inhibitors have been developed for targeted anticancer therapies. Given that PLK1 and Aurora kinases possess both unique functions as well as co-regulate multiple mitotic events, whether pharmacological inhibition of these kinases together can enhance mitotic catastrophe remains an outstanding issue to be determined. Using concentrations of inhibitors that did not induce severe mitotic defects on their own, we found that both the metaphase arrest and mitotic slippage induced by inhibitors targeting Aurora A and Aurora B (MK-5108 and Barasertib respectively) were enhanced by a PLK1 inhibitor (BI 2536). We found that PLK1 is overexpressed in cells from nasopharyngeal carcinoma, a highly invasive cancer with poor prognosis, in comparison to normal nasopharyngeal epithelial cells. Nasopharyngeal carcinoma cells were more sensitive to BI 2536 as a single agent and co-inhibition with Aurora kinases than normal cells. These observations underscore the mechanism and potential benefits of targeting PLK1 and Aurora kinases to induce mitotic catastrophe in cancer cells. PMID:25871386

  4. Aurora A is a prognostic marker for breast cancer arising in BRCA2 mutation carriers

    PubMed Central

    Aradottir, Margret; Reynisdottir, Sigridur T; Stefansson, Olafur A; Jonasson, Jon G; Sverrisdottir, Asgerdur; Tryggvadottir, Laufey; Eyfjord, Jorunn E

    2014-01-01

    Abstract Overexpression of the Aurora A kinase has been shown to have prognostic value in breast cancer. Previously, we showed a significant association between AURKA gene amplification and BRCA2 mutation in breast cancer. The aim of this study was to assess the prognostic impact of Aurora A overexpression on breast cancer arising in BRCA2 mutation carriers. Aurora A expression was evaluated by immunohistochemistry on breast tumour tissue microarrays from 107 BRCA2 999del5 mutation carriers and 284 of sporadic origin. Prognostic value of Aurora A nuclear staining was estimated in relation to clinical markers and adjuvant treatment, using multivariate Cox's proportional hazards ratio regression model. BRCA2 wild‐type allele loss was measured by TaqMan in BRCA2 mutated tumour samples. All statistical tests were two sided. Multivariate analysis of breast cancer‐specific survival, including proliferative markers and treatment, indicated independent prognostic value of Aurora A nuclear staining for BRCA2 mutation carriers (hazards ratio = 7.06; 95% confidence interval = 1.23–40.6; p = 0.028). Poor breast cancer‐specific survival of BRCA2 mutation carriers was found to be significantly associated with combined Aurora A nuclear expression and BRCA2 wild type allele loss in tumours (p < 0.001). Multivariate analysis indicated independent prognostic value of both positive Aurora A nuclear staining (hazards ratio = 10.09; 95% confidence interval = 1.19–85.4, p = 0.034) and BRCA2 wild type allele loss (hazards ratio = 9.63; 95% confidence interval = 1.81–51.0, p = 0.008) for BRCA2 mutation carriers. Aurora A nuclear expression was found to be a significant prognostic marker for BRCA2 mutation carriers, independent of clinical parameters and adjuvant treatment. Our conclusion is that treatment benefits for BRCA2 mutation carriers and sporadic breast cancer patients with Aurora A positive tumours may be enhanced by giving

  5. A statistical study of dayside diffuse aurora observed at Yellow River Station in Ny-Ålesund, Svalbard

    NASA Astrophysics Data System (ADS)

    Han, D.; Hu, Z.; Hu, H.; Yang, H.; Huang, D. H.; Chen, X.

    2014-12-01

    Chinese Yellow River Station (YRS), at Ny-Alesund, Svalbard is one of the few stations that can make longtime optical auroral observation at the cusp latitude in the dayside during the boreal winter season on the Earth. Since November 2003, an optical observation system consisting of three identical all-sky imagers supplied with the narrow band filters centered at 427.8, 557.5 and 630.0nm, has been installed at YRS, and the continuous observations providing us with an unprecedented opportunity to investigate some new properties of dayside aurora. Optical diffuse auroras are normally observed at the sub-aurora latitude in nightside on the ground. However, by using 7-year continuous observations obtained at YRS, we found that the diffuse auroras are very frequently observed on the dayside at the high latitude, i.e., near the cusp. We classified the dayside diffuse aurora into four primary categories. They are (1) Veiling Diffuse Aurora, which has no obvious morphological structure and clear boundaries, sometimes likes a thick cloud cover the entire sky, (2) Patch Diffuse Aurora, which is an aurora patch normally in ~10-100km in width and usually owns pulsating property; (3) Diffuse Arcs, which looks like an arc but is apparently different from the discrete auroral arcs in morphology, and (4) Pulsating Aurora, occurring with sparkling forms. We statistical studied how the occurrence of the four types of dayside diffuse auroras depends on the local time, magnetic activity, and solar wind conditions. We found that the occurrence of each type of dayside diffuse aurora shows a unimodal distribution with magnetic local time and their peaks are mostly appeared near the magnetic local noon. We also noted that ~92.2% of the dayside diffuse auroras is observed under low magnetic activity, i.e., Kp ≤ 3, and the dayside diffuse auroras prefer to be observed under IMF By<0 and Bz>0. Although previous studies suggested that the dayside diffuse aurora should be caused by wave

  6. Essential role of autoactivation circuitry on Aurora B-mediated H2AX-pS121 in mitosis

    PubMed Central

    Shimada, Midori; Goshima, Takahiro; Matsuo, Hiromi; Johmura, Yoshikazu; Haruta, Mayumi; Murata, Kazuhiro; Tanaka, Hiromitsu; Ikawa, Masahito; Nakanishi, Keiko; Nakanishi, Makoto

    2016-01-01

    Proper deposition and activation of Aurora B at the centromere is critical for faithful chromosome segregation in mammals. However, the mechanistic basis for abrupt Aurora B kinase activation at the centromere has not yet been fully understood. We demonstrate here that Aurora B-mediated phosphorylation of histone H2AX at serine 121 (H2AX-pS121) promotes Aurora B autophosphorylation and is essential for proper chromosome segregation. Aurora B-mediated H2AX-pS121 is specifically detected at the centromere during mitosis. H2AX depletion results in a severe defect in activation and deposition of Aurora B at this locus. A phosphomimic mutant of H2AX at S121 interacts with activated Aurora B more efficiently than wild-type in vitro. Taken together, these results propose a model in which Aurora B-mediated H2AX-pS121 probably provide a platform for Aurora B autoactivation circuitry at centromeres and thus play a pivotal role in proper chromosome segregation. PMID:27389782

  7. Essential role of autoactivation circuitry on Aurora B-mediated H2AX-pS121 in mitosis.

    PubMed

    Shimada, Midori; Goshima, Takahiro; Matsuo, Hiromi; Johmura, Yoshikazu; Haruta, Mayumi; Murata, Kazuhiro; Tanaka, Hiromitsu; Ikawa, Masahito; Nakanishi, Keiko; Nakanishi, Makoto

    2016-01-01

    Proper deposition and activation of Aurora B at the centromere is critical for faithful chromosome segregation in mammals. However, the mechanistic basis for abrupt Aurora B kinase activation at the centromere has not yet been fully understood. We demonstrate here that Aurora B-mediated phosphorylation of histone H2AX at serine 121 (H2AX-pS121) promotes Aurora B autophosphorylation and is essential for proper chromosome segregation. Aurora B-mediated H2AX-pS121 is specifically detected at the centromere during mitosis. H2AX depletion results in a severe defect in activation and deposition of Aurora B at this locus. A phosphomimic mutant of H2AX at S121 interacts with activated Aurora B more efficiently than wild-type in vitro. Taken together, these results propose a model in which Aurora B-mediated H2AX-pS121 probably provide a platform for Aurora B autoactivation circuitry at centromeres and thus play a pivotal role in proper chromosome segregation. PMID:27389782

  8. Tripolin A, a Novel Small-Molecule Inhibitor of Aurora A Kinase, Reveals New Regulation of HURP's Distribution on Microtubules

    PubMed Central

    Kesisova, Iliana A.; Nakos, Konstantinos C.; Tsolou, Avgi; Angelis, Dimitrios; Lewis, Joe; Chatzaki, Aikaterini; Agianian, Bogos; Giannis, Athanassios; Koffa, Maria D.

    2013-01-01

    Mitotic regulators exhibiting gain of function in tumor cells are considered useful cancer therapeutic targets for the development of small-molecule inhibitors. The human Aurora kinases are a family of such targets. In this study, from a panel of 105 potential small-molecule inhibitors, two compounds Tripolin A and Tripolin B, inhibited Aurora A kinase activity in vitro. In human cells however, only Tripolin A acted as an Aurora A inhibitor. We combined in vitro, in vivo single cell and in silico studies to demonstrate the biological action of Tripolin A, a non-ATP competitive inhibitor. Tripolin A reduced the localization of pAurora A on spindle microtubules (MTs), affected centrosome integrity, spindle formation and length, as well as MT dynamics in interphase, consistent with Aurora A inhibition by RNAi or other specific inhibitors, such as MLN8054 or MLN8237. Interestingly, Tripolin A affected the gradient distribution towards the chromosomes, but not the MT binding of HURP (Hepatoma Up-Regulated Protein), a MT-associated protein (MAP) and substrate of the Aurora A kinase. Therefore Tripolin A reveals a new way of regulating mitotic MT stabilizers through Aurora A phosphorylation. Tripolin A is predicted to bind Aurora A similarly but not identical to MLN8054, therefore it could be used to dissect pathways orchestrated by Aurora kinases as well as a scaffold for further inhibitor development. PMID:23516487

  9. Specific small-molecule activator of Aurora kinase A induces autophosphorylation in a cell-free system.

    PubMed

    Kishore, A Hari; Vedamurthy, B M; Mantelingu, K; Agrawal, Shipra; Reddy, B A Ashok; Roy, Siddhartha; Rangappa, K S; Kundu, Tapas K

    2008-02-28

    Aurora kinases are essential for chromosomal segregation and cell division and thereby important for maintaining the proper genomic integrity. There are three classes of aurora kinases in humans: A, B, and C. Aurora kinase A is frequently overexpressed in various cancers. The link of the overexpression and tumorigenesis is yet to be understood. By employing virtual screening, we have found that anacardic acid, a pentadecane aliphatic chain containing hydroxylcarboxylic acid, from cashew nut shell liquid could be docked in Aurora kinases A and B. Remarkably, we found that anacardic acid could potently activate the Aurora kinase A mediated phosphorylation of histone H3, but at a similar concentration the activity of aurora kinase B remained unaffected in vitro. Mechanistically, anacardic acid induces the structural changes and also the autophosphorylation of the aurora kinase A to enhance the enzyme activity. This data thus indicate anacardic acid as the first small-molecule activator of Aurora kinase, which could be highly useful for probing the function of hyperactive (overexpressed) Aurora kinase A. PMID:18215015

  10. Characteristics of north jovian aurora from STIS FUV spectral images

    NASA Astrophysics Data System (ADS)

    Gustin, J.; Grodent, D.; Ray, L. C.; Bonfond, B.; Bunce, E. J.; Nichols, J. D.; Ozak, N.

    2016-04-01

    We analyzed two observations obtained in Jan. 2013, consisting of spatial scans of the jovian north ultraviolet aurora with the HST Space Telescope Imaging Spectrograph (STIS) in the spectroscopic mode. The color ratio (CR) method, which relates the wavelength-dependent absorption of the FUV spectra to the mean energy of the precipitating electrons, allowed us to determine important characteristics of the entire auroral region. The results show that the spatial distribution of the precipitating electron energy is far from uniform. The morning main emission arc is associated with mean energies of around 265 keV, the afternoon main emission (kink region) has energies near 105 keV, while the 'flare' emissions poleward of the main oval are characterized by electrons in the 50-85 keV range. A small scale structure observed in the discontinuity region is related to electrons of 232 keV and the Ganymede footprint shows energies of 157 keV. Interestingly, each specific region shows very similar behavior for the two separate observations. The Io footprint shows a weak but undeniable hydrocarbon absorption, which is not consistent with altitudes of the Io emission profiles (∼900 km relative to the 1 bar level) determined from HST-ACS observations. An upward shift of the hydrocarbon homopause of at least 100 km is required to reconcile the high altitude of the emission and hydrocarbon absorption. The relationship between the energy fluxes and the electron energies has been compared to curves obtained from Knight's theory of field-aligned currents. Assuming a fixed electron temperature of 2.5 keV, an electron source population density of ∼800 m-3 and ∼2400 m-3 is obtained for the morning main emission and kink regions, respectively. Magnetospheric electron densities are lowered for the morning main emission (∼600 m-3) if the relativistic version of Knight's theory is applied. Lyman and Werner H2 emission profiles, resulting from secondary electrons produced by

  11. Rapid ray motions in barium plasma clouds and auroras

    SciTech Connect

    Wescott, E.M.; Hallinan, T.J.; Stenbaek-Nielsen, H.C.; Swift, D.W.; Wallis, D.D. )

    1993-03-01

    Barium plasma clouds released at high latitudes characteristically become striated with many field-aligned rays. The rays which often resemble auroral features usually drift as a whole with the E [times] B/B[sup 2] drift of the cloud and alter position only slowly (order or tens of seconds). On two evenings in 1968, in releases from Andoya, Norway, anomalous field-aligned brightenings or emission enhancements of up to 3X were observed to move rapidly (10-20 km/s) through three different Ba[sup +] clouds. Similar effects were observed in Ba[sup +] clouds released from rockets launched from Poker Flat, Alaska: On March 21, 1973, in two Ba thermite releases and on March 22, 1980, in the Ba-shaped charge experiment Miss Peggy.' On these occasions, auroras on or near the Ba[sup +] L shell, also exhibited active rapid ray motions. This leads to the assumption that the two phenomena are related and the expectation that an explanation of the rapid ray motions in the Ba[sup +] clouds would lead to a better understanding of the physics of auroral ray motions and the auroral ionosphere. Seven possible mechanisms to produce the observed moving emission enhancements are discussed. Direct motion of an isolated Ba[sup +] ray past the other rays by E [times] B/B[sup 2] motion seems very unlikely due to the observed variations in the enhancements and the large E field required (> 500 mV/m). Compressional waves do not seem to be of sufficient amplitude or velocity. Absorption or radiation of Doppler shifted Ba[sup +] emissions by ions gyrating or moving at a few kilometers per second seems to be the most promising mechanism for producing the enhancements. The observations provide compelling evidence for the existence of transient electric fields of order 100 mV/m at altitudes as low as 200 km during active aurora with rapid ray motions. The affected regions have dimensions of order a few kilometers across B and move eastward at 10-20 km/s. 36 refs., 10 figs., 1 tab.

  12. AURORA BOREALIS: a polar-dedicated European Research Platform

    NASA Astrophysics Data System (ADS)

    Wolff-Boenisch, Bonnie; Egerton, Paul; Thiede, Joern; Roberto, Azzolini; Lembke-Jene, Lester

    2010-05-01

    Polar research and in particular the properties of northern and southern high latitude oceans are currently a subject of intense scientific debate and investigations, because they are subject to rapid and dramatic climatic variations. Polar regions react more rapidly and intensively to global change than other regions of the earth. A shrinking of the Arctic sea-ice cover, potentially leading to an opening of sea passages to the north of North America and Eurasia, on the long to a "blue" Arctic Ocean would additionally have a strong impact on transport, commerce and tourism bearing potential risk for humans and complex ecosystems in the future. In spite of their critical role processes and feedbacks, especially in winter but not exclusively, are virtually unknown: The Arctic Ocean for example, it is the only basin of the world's oceans that has essentially not been sampled by the drill ships of the Deep-Sea Drilling Project (DSDP) or the Ocean Drilling Program (ODP) and its long-term environmental history and tectonic structure is therefore poorly known. Exceptions are the ODP Leg 151 and the more recent very successful ACEX-expedition of the Integrated Ocean Drilling Program (IODP) in 2004. To help to address the most pressing questions regarding climate change and related processes, a Pan-European initiative in the field of Earth system science has been put in place: AURORA BOREALIS is the largest environmental research infrastructure on the ESFRI roadmap of the European Community. AURORA BOREALIS is a very powerful research icebreaker, which will enable year-round operations in the Arctic and the Antarctic as well as in the adjacent ocean basins. Equipped with its drilling rig, the vessel is also capable to explore the presently completely unknown Arctic deep-sea floor. Last but not least, the ship is a floating observatory and mobile monitoring platform that permits to measure on a long-term basis comprehensive time series in all research fields relevant to

  13. Polarization of Pc1/EMIC waves and related proton auroras observed at subauroral latitudes

    NASA Astrophysics Data System (ADS)

    Nomura, R.; Shiokawa, K.; Sakaguchi, K.; Otsuka, Y.; Connors, M.

    2012-02-01

    We have investigated the polarization of Pc1 geomagnetic pulsations and related proton auroras at subauroral latitudes, using an induction magnetometer and an all-sky camera at Athabasca, Canada (54.7°N, 246.7°E, magnetic latitude (mlat) 61.7°N). Isolated proton auroras often appear in association with Pc1 pulsations, because of proton scattering by electromagnetic ion cyclotron (EMIC) waves in the magnetosphere. We used the proton aurora as a proxy for the location and size of the Pc1 ionospheric source. For 27 Pc1 events with simultaneously observed proton auroras over 4 years from September 7, 2005 to September 6, 2009, we calculated the distances between the Pc1 ionospheric source and the observation site, normalized by the scale size of the source. We tried three different definitions of the scale size of Pc1 ionospheric source to calculate the normalized distances. We found that the rotation angle θ between the Pc1 polarization ellipse and the direction to the proton aurora changes from 90° to 0° as the normalized distance increases. For the definition of the scale sizes that gives most clear θ-transition from 90° to 0°, the transition occurs at the normalized distance ˜2.0-4.0, while it was ˜1.0-2.0 by the model calculation of Fujita and Tamao (1988). The averaged major axes tend to point toward the proton aurora at larger distances. The difference of the transition location may imply that the Pc1 ionospheric sources are larger than the isolated proton auroras, or that the inhomogenuity of the ionospheric conductivity by the proton precipitation affects the transition distances.

  14. Solar wind influence on Jupiter's magnetosphere and aurora

    NASA Astrophysics Data System (ADS)

    Vogt, Marissa; Gyalay, Szilard; Withers, Paul

    2016-04-01

    Jupiter's magnetosphere is often said to be rotationally driven, with strong centrifugal stresses due to large spatial scales and a rapid planetary rotation period. For example, the main auroral emission at Jupiter is not due to the magnetosphere-solar wind interaction but is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma. Additionally, processes like tail reconnection are also thought to be driven, at least in part, by processes internal to the magnetosphere. While the solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. We will report on the results of a comprehensive, quantitative study of the influence of the solar wind on various magnetospheric data sets measured by the Galileo mission from 1996 to 2003. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter, we have identified intervals of high and low solar wind dynamic pressure. We can use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration, which in turn will affect the ionospheric mapping of the main auroral emission. We also consider whether there is evidence that reconnection events occur preferentially during certain solar wind conditions or that the solar wind modulates the quasi-periodicity seen in the magnetic field dipolarizations and flow bursts.

  15. Ezekiel and the Northern Lights: Biblical aurora seems plausible

    NASA Astrophysics Data System (ADS)

    Siscoe, George L.; Silverman, Samuel M.; Siebert, Keith D.

    Auroral specialists have suggested that in the Bible's Old Testament book of Ezekiel, the opening vision of a "storm cloud out of the north" depicts imagery inspired by a low-latitude auroral display [Link, 1967; Eather, 1980; Silverman, 1998]. Naturally, other interpretations have been suggested, including a true epiphany, a sandstorm, a thunderstorm, a tornado, a solar halo, a hallucination, and a UFO. Biblical scholars place the site of the Ezekiel's vision about 100 km south of Babylon near Nippur, latitude ˜32°, longitude ˜45°, and the date is within a year or two of 593 B.C., or about 2600 years ago.An auroral interpretation of the vision is subject to possible refutation due to several geophysical considerations. Can auroras be seen at Ezekiel's latitude? More important, can they reach a coronal stage of development, which is what the vision requires? Was the tilt of the dipole axis favorable? Was the general level of solar activity favorable? And finally, What effect does a larger dipole moment in Ezekiel's time have on the question? All but the last question could have been answered on the basis of geophysical data a decade ago or earlier.

  16. Ultraviolet spectrum of the Aurora /2000-2800 A/

    NASA Technical Reports Server (NTRS)

    Beiting, E. J., III; Feldman, P. D.

    1979-01-01

    Ultraviolet spectra between 2000 and 2800 delta-v of an IBC II(+) aurora were obtained by a rocket-borne Ebert-Fastie monochromator at 15-A resolution over Fort Churchill, Manitoba. The v-prime = 0-8 progressions of the N2 Vegard-Kaplan system, the delta-v = 8 sequence of the Lyman-Birge-Hopfield system, and a progression attributed to the Herman-Kaplan system were identified by a synthetic spectrum analysis. Relative populations of the first eight vibrational levels of the A3 Sigma u(+) state at high altitude were obtained from the theoretically generated spectra, and quenching rate coefficients were derived for these eight levels by using an atomic oxygen concentration derived from data from another experiment on board. For v = 0 the quenching rate coefficient was found to be 2.0 times 10 the minus 10th cu cm/sec and was not found to increase for higher vibrational levels. The intensity of the (0,2) band of the Herman-Kaplan system was found to be about 5 times the theoretically predicted value, but even so, the cascade from E3 Sigma g(+) provides less than 2% of the A3 Sigma u(+) state population.

  17. Aurora A kinase activity influences calcium signaling in kidney cells.

    PubMed

    Plotnikova, Olga V; Pugacheva, Elena N; Golemis, Erica A

    2011-06-13

    Most studies of Aurora A (AurA) describe it as a mitotic centrosomal kinase. However, we and others have recently identified AurA functions as diverse as control of ciliary resorption, cell differentiation, and cell polarity control in interphase cells. In these activities, AurA is transiently activated by noncanonical signals, including Ca(2+)-dependent calmodulin binding. These and other observations suggested that AurA might be involved in pathological conditions, such as polycystic kidney disease (PKD). In this paper, we show that AurA is abundant in normal kidney tissue but is also abnormally expressed and activated in cells lining PKD-associated renal cysts. PKD arises from mutations in the PKD1 or PKD2 genes, encoding polycystins 1 and 2 (PC1 and PC2). AurA binds, phosphorylates, and reduces the activity of PC2, a Ca(2+)-permeable nonselective cation channel and, thus, limits the amplitude of Ca(2+) release from the endoplasmic reticulum. These and other findings suggest AurA may be a relevant new biomarker or target in the therapy of PKD. PMID:21670214

  18. Using Radio-Induced Aurora to Observe Ionospheric Irregularities

    NASA Astrophysics Data System (ADS)

    Bernhardt, P.; Gondarenko, N.; Guzdar, P.; Huba, J.; Ossakow, S.; Djuth, F.; Tepley, C.; Sulzer, M.; Kagan, L.; Kelley, M.

    Two-dimensional images of F- and E- layers have been obtained using the technique called radio-induced aurora (RIA). This technique makes the plasma layers glow in the ionosphere glow when being stimulated by high power radio waves. Normally the irregularities in the ionosphere do not radiate strong enough visible emissions to be observed from the ground. Experiments at Arecibo Observatory in Puerto Rico and the SURA facility in Russia have shown that the plasma structures can be made to glow at 630.0 nm, 557.7 nm and other wavelengths by illuminating them by HF radio waves with effective radiated powers of 80 megawatts. The regions of the sporadic-E layers that have electron densities greater than the critical density for reflection of the radio waves emit electrons that collide with and excite atmospheric atomic oxygen and molecular nitrogen. A charge-coupled-device (CCD) imager located on the ground is used to capture images of the glowing E and F-region structures. The camera exposure- times were in the range of 15 to 45 seconds. The images obtained using this technique show a wide variety of both field-aligned and wind-aligned irregularities. Some layers cover the antenna pattern cone illuminated by the radio wave beam. Other layers show strong modulations by both plasma and neutral instabilities. Two-dimensional computer simulations of the coupling between neutral winds, electric fields and the ion layers simulate the structure in the images.

  19. Cosmic ray secular variations in terrestrial records and aurorae

    NASA Technical Reports Server (NTRS)

    Attolini, M. R.; Castagnoli, G. C.; Bonino, G.; Galli, M.; Nanni, T.

    1985-01-01

    The rediscovery that the Sun and the solar wind can undergo important changes on historical time scales has brought into question the stability of the cyclic behavior of past time series of solar and solar-terrestrial origin. It was found by Vector Fourier analysis that the solar 11 year cycle is present in the series of 10Be, delta 180, in ice cores and of thermoluminescence (TL) in sea sediments during the last Millennia with a frequency modulation, related to the Sun behavior, as tested by comparison with the Sunspot number R sub z series. It was shown that the cyclogram of the series of yearly Aurorae from 1721 to 1979 linear-regression-corrected-for-R sub z is straight for the periodicity zeta=11,1y, which indicates that such periodicity is constant in time corresponding to the only line present in the 11y band. The maxima of this component appear at the same time together with the high speed solar wind streams taking place in coronal holes situated in high heliolatitudes. It is evidenced that the 11 year cycle has undergone frequency oscillations on a time scale of two centuries, although it is very difficult to determine the periodicities with high accuracy.

  20. Artificial auroras in the upper atmosphere. 1. Electron beam injections

    SciTech Connect

    Burch, J.L.; Gibson, W.C.; Marshall, J.A. ); Mende, S.B.; Swenson, G.R. ); Kawashima, N. ); Roberts, W.T. ); Taylor, W.W.L. ); Neubert, T. )

    1993-03-19

    Artificial electron beams from the Space Experiments with Particle Accelerators (SEPAC) on the ATLAS 1 Spacelab payload were used to stimulate auroral emissions at southern auroral latitudes. The emitted electron beams were monoenergetic at 6.25 keV and were fired in one-second pulses every fifteen seconds with currents of 1.21 A. Optical measurements of the beam were made in the vicinity of the Shuttle Orbiter by its on-board television camera and in the upper atmosphere by the Atmospheric Emissions Photometric Imager (AEPI). AEPI imaged auroral emissions in both white light and at the 427.8 nm N[sub 2][sup +] emission line. Energy deposition calculations and the results of previous sounding-rocket experiments had suggested that emissions with scale sizes of about 130 meters would result from the artificial electron beams with the visible emissions extending from about 110 to 130 km altitudes. In the ATLAS 1 experiments the auroral imaging was performed from the Shuttle, providing a new perspective on the artificial auroras and allowing the emissions to be traced from altitudes near the 295 km Shuttle altitude down to the 110 km level along the curved magnetic field lines. 11 refs., 3 figs., 1 tab.

  1. Mathematical models of the open magnetosphere - Application to dayside auroras.

    NASA Technical Reports Server (NTRS)

    Forbes, T. G.; Speiser, T. W.

    1971-01-01

    Two static mathematical models of the open or Dungey model of the magnetosphere are constructed. The process of construction is similar to that for early closed magnetosphere models, such as the Taylor-Hones model. The first model in fact is simply an addition of an interplanetary field in arbitrary direction to a Taylor-Hones image dipole model. In order to preserve the shape of the magnetosphere at high latitudes, and to partially exclude the exterior field, another model is constructed with the magnetopause approximated by a diamagnetic sphere. We find that there are some interplanetary field lines connected to the earth for all orientations of the interplanetary field other than strictly northward, and that the maximum number of connected field lines occurs with a due southward field. For an average spiral hose angle of the interplanetary field, the dayside neutral point occurs on the magnetopause at about 10 o'clock local time. Dayside auroras, convection patterns, and other phenomena may exhibit symmetry about this local time. For a positive (negative) interplanetary field sector, energetic, anisotropic particle fluxes should have direct access to the northern (southern) polar caps, as is supported by many recent observations.

  2. Equatorward and poleward expansion of the auroras during auroral substorms

    SciTech Connect

    Nakamura, R. ); Oguti, Takasi ); Yamamoto, Tatsundo ); Kokubun, Susumu )

    1993-04-01

    The authors have used all-sky TV auroral data from a number of different sources to study the formation of the auroral bulge with high spatial and temporal resolution. By linking data sets which cover different parts of the sky they are able to study systematically the development of structures within the poleward expanding bulge. Structures develop to the west, east, and equatorward from a localized region of breakup. To the west a surge develops with a clockwise rotation (when viewed along the magnetic field direction). To the east thin auroral features propagate toward the east. Near the center of the bulge, auroral features develop equatorward, becoming north-south aligned. These and other observations are suggested to be the consequence of the bulge developing along the plasma steamlines as a two cell equipotential distribution. In terms of this model the authors are able to explain the expansions of the bulge in different directions, the observation of pulsating structures in the aurora, and offer explanations of other observations.

  3. BLACK HOLE AURORA POWERED BY A ROTATING BLACK HOLE

    SciTech Connect

    Takahashi, Masaaki; Takahashi, Rohta

    2010-05-15

    We present a model for high-energy emission sources generated by a standing magnetohydrodynamical (MHD) shock in a black hole magnetosphere. The black hole magnetosphere would be constructed around a black hole with an accretion disk, where a global magnetic field could be originated by currents in the accretion disk and its corona. Such a black hole magnetosphere may be considered as a model for the central engine of active galactic nuclei, some compact X-ray sources, and gamma-ray bursts. The energy sources of the emission from the magnetosphere are the gravitational and electromagnetic energies of magnetized accreting matters and the rotational energy of a rotating black hole. When the MHD shock generates in MHD accretion flows onto the black hole, the plasma's kinetic energy and the black hole's rotational energy can convert to radiative energy. In this Letter, we demonstrate the huge energy output at the shock front by showing negative energy postshock accreting MHD flows for a rapidly rotating black hole. This means that the extracted energy from the black hole can convert to the radiative energy at the MHD shock front. When an axisymmetric shock front is formed, we expect a ring-shaped region with very hot plasma near the black hole; this would look like an 'aurora'. The high-energy radiation generated from there would carry to us the information for the curved spacetime due to the strong gravity.

  4. Aurora-A promotes chemoresistance in hepatocelluar carcinoma by targeting NF-kappaB/microRNA-21/PTEN signaling pathway

    PubMed Central

    Chen, Dongqin; Huang, Jiayuan; Feng, Bing; Han, Siqi; Chen, Yitian; Song, Haizhu; De, Wei; Zhu, Ziman; Wang, Rui; Chen, Longbang

    2014-01-01

    Hepatocellular carcinoma (HCC) is highly resistant to chemotherapy. Previously, we have shown that Aurora-A mRNA is upregulated in HCC cells or tissues and silencing of Aurora-A using small interfering RNA (siRNA) decreases growth and enhances apoptosis in HCC cells. However, the clinical significance of Aurora-A protein expression in HCC and association between Aurora-A expression and HCC chemoresistance is unclear. Here, we showed that Aurora-A protein is upregulated in HCC tissues and significantly correlated with recurrence-free and overall survival of patients and multivariate analysis indicated that immunostaining of Aurora-A will be an independent prognostic factor for patients. Silencing of Aurora-A significantly increased the chemosensitivity of HCC cells both in vitro and in vivo, while overexpression of Aurora-A induced the opposite effects. Furthermore, overexpression of Aurora-A reduces chemotherapy-induced apoptosis by promoting microRNA-21 expression, which negatively regulates PTEN and then inhibits caspase-3-mediated apoptosis induction. Mechanically, we demonstrated that Aurora-A promotes expression of nuclear Ikappaβ-alpha (Iκβα) protein and enhances NF-kappa B (NF-κB) activity, thus promotes the transcription of miR-21. This study first reported the involvement of Aurora-A/NF-κB/miR-21/PTEN/Akt signaling axis in chemoresistance of HCC cells, suggesting that targeting this signaling pathway would be helpful as a therapeutic strategy for the reversal of chemoresistance in HCC. PMID:25428915

  5. Aurora B suppresses microtubule dynamics and limits central spindle size by locally activating KIF4A

    PubMed Central

    Nunes Bastos, Ricardo; Gandhi, Sapan R.; Baron, Ryan D.; Gruneberg, Ulrike; Nigg, Erich A.

    2013-01-01

    Anaphase central spindle formation is controlled by the microtubule-stabilizing factor PRC1 and the kinesin KIF4A. We show that an MKlp2-dependent pool of Aurora B at the central spindle, rather than global Aurora B activity, regulates KIF4A accumulation at the central spindle. KIF4A phosphorylation by Aurora B stimulates the maximal microtubule-dependent ATPase activity of KIF4A and promotes its interaction with PRC1. In the presence of phosphorylated KIF4A, microtubules grew more slowly and showed long pauses in growth, resulting in the generation of shorter PRC1-stabilized microtubule overlaps in vitro. Cells expressing only mutant forms of KIF4A lacking the Aurora B phosphorylation site overextended the anaphase central spindle, demonstrating that this regulation is crucial for microtubule length control in vivo. Aurora B therefore ensures that suppression of microtubule dynamic instability by KIF4A is restricted to a specific subset of microtubules and thereby contributes to central spindle size control in anaphase. PMID:23940115

  6. Combined cisplatin and aurora inhibitor treatment increase neuroblastoma cell death but surviving cells overproduce BDNF.

    PubMed

    Polacchini, Alessio; Albani, Clara; Baj, Gabriele; Colliva, Andrea; Carpinelli, Patrizia; Tongiorgi, Enrico

    2016-01-01

    Drug-resistance to chemotherapics in aggressive neuroblastoma (NB) is characterized by enhanced cell survival mediated by TrkB and its ligand, brain-derived neurotrophic factor (BDNF); thus reduction in BDNF levels represent a promising strategy to overcome drug-resistance, but how chemotherapics regulate BDNF is unknown. Here, cisplatin treatment in SK-N-BE neuroblastoma upregulated multiple BDNF transcripts, except exons 5 and 8 variants. Cisplatin increased BDNF mRNA and protein, and enhanced translation of a firefly reporter gene flanked by BDNF 5'UTR exons 1, 2c, 4 or 6 and 3'UTR-long. To block BDNF translation we focused on aurora kinases inhibitors which are proposed as new chemotherapeutics. NB cell survival after 24 h treatment was 43% with cisplatin, and 22% by cisplatin+aurora kinase inhibitor PHA-680632, while the aurora kinases inhibitor alone was less effective; however the combined treatment induced a paradoxical increase of BDNF in surviving cells with strong translational activation of exon6-3'UTR-long transcript, while translation of BDNF transcripts 1, 2C and 4 was suppressed. In conclusion, combined cisplatin and aurora kinase inhibitor treatment increases cell death, but induces BDNF overproduction in surviving cells through an aurora kinase-independent mechanism. PMID:27256407

  7. Ceftriaxone, an FDA-approved cephalosporin antibiotic, suppresses lung cancer growth by targeting Aurora B.

    PubMed

    Li, Xiang; Li, Haitao; Li, Shengqing; Zhu, Feng; Kim, Dong Joon; Xie, Hua; Li, Yan; Nadas, Janos; Oi, Naomi; Zykova, Tatyana A; Yu, Dong Hoon; Lee, Mee-Hyun; Kim, Myoung Ok; Wang, Lei; Ma, Weiya; Lubet, Ronald A; Bode, Ann M; Dong, Ziming; Dong, Zigang

    2012-12-01

    Ceftriaxone, an FDA-approved third-generation cephalosporin antibiotic, has antimicrobial activity against both gram-positive and gram-negative organisms. Generally, ceftriaxone is used for a variety of infections such as community-acquired pneumonia, meningitis and gonorrhea. Its primary molecular targets are the penicillin-binding proteins. However, other activities of ceftriaxone remain unknown. Herein, we report for the first time that ceftriaxone has antitumor activity in vitro and in vivo. Kinase profiling results predicted that Aurora B might be a potential 'off' target of ceftriaxone. Pull-down assay data confirmed that ceftriaxone could bind with Aurora B in vitro and in A549 cells. Furthermore, ceftriaxone (500 µM) suppressed anchorage-independent cell growth by targeting Aurora B in A549, H520 and H1650 lung cancer cells. Importantly, in vivo xenograft animal model results showed that ceftriaxone effectively suppressed A549 and H520 lung tumor growth by inhibiting Aurora B. These data suggest the anticancer efficacy of ceftriaxone for the treatment of lung cancers through its inhibition of Aurora B. PMID:22962305

  8. Aurora kinases and protein phosphatase 1 mediate chromosome congression through regulation of CENP-E.

    PubMed

    Kim, Yumi; Holland, Andrew J; Lan, Weijie; Cleveland, Don W

    2010-08-01

    Opposing roles of Aurora kinases and protein phosphatase 1 (PP1) during mitosis have long been suggested. Here, we demonstrate that Aurora kinases A and B phosphorylate a conserved residue on the kinetochore motor CENP-E. PP1 binds CENP-E via a motif overlapping this phosphorylation site and binding is disrupted by Aurora phosphorylation. Phosphorylation of CENP-E by the Auroras is enriched at spindle poles, disrupting binding of PP1 and reducing CENP-E's affinity for individual microtubules. This phosphorylation is required for CENP-E-mediated towing of initially polar chromosomes toward the cell center. Kinetochores on such chromosomes cannot make subsequent stable attachment to spindle microtubules when dephosphorylation of CENP-E or rebinding of PP1 to CENP-E is blocked. Thus, an Aurora/PP1 phosphorylation switch modulates CENP-E motor activity as an essential feature of chromosome congression from poles and localized PP1 delivery by CENP-E to the outer kinetochore is necessary for stable microtubule capture by those chromosomes. PMID:20691903

  9. Differentially expressed epigenome modifiers, including Aurora kinase A and B, in immune cells of rheumatoid arthritis

    PubMed Central

    Glant, Tibor T.; Besenyei, Timea; Kádár, András; Kurkó, Júlia; Tryniszewska, Beata; Gál, János; Soós, Györgyi; Szekanecz, Zoltán; Hoffmann, Gyula; Block, Joel A.; Katz, Robert S.; Mikecz, Katalin; Rauch, Tibor A.

    2014-01-01

    Objective The aim of this study was to identify epigenetic factors that are implicated in the pathogenesis of rheumatoid arthritis (RA) and to explore the therapeutic potential of the targeted inhibition of these factors. Methods PCR arrays were utilized to investigate the expression profile of genes that encod key epigenetic regulator enzymes. Mononuclear cells from RA patients and mice were monitored for gene expression changes, in association with arthritis development in murine models of RA. Selected genes were further characterized by quantitative real-time PCR, Western blot and flow cytometry methods. The targeted inhibition of the upregulated enzymes was studied in arthritic mice. Results A set of genes with arthritis-specific expression was identified by the PCR arrays. Aurora kinase A and B, both of which were highly expressed in arthritic mice and treatment naïve RA patients, were selected for detailed analysis. Elevated Aurora kinase expression was accompanied with an increased phosphorylation of histone H3, which promotes proliferation of T lymphocytes. Treatment with VX-680, a pan-Aurora kinase inhibitor, promoted B cell apoptosis, provided significant protection against the onset, and attenuated the inflammatory reactions in arthritic mice. Conclusions Arthritis development is accompanied the changes in the expression of a number of epigenome-modifying enzymes. Drug-induced downregulation of the Aurora kinases, among other targets, seems to be sufficient to treat experimental arthritis. Development of new therapeutics that target the Aurora kinases can potentially improve RA management. PMID:23653330

  10. Rebamipide inhibits gastric cancer growth by targeting survivin and Aurora-B

    SciTech Connect

    Tarnawski, A.; E-mail: andrzej.tarnawski@med.va.gov; Pai, R.; Chiou, S.-K.; Chai, J.; Chu, E.C.

    2005-08-19

    Rebamipide accelerates healing of gastric ulcers and gastritis but its actions on gastric cancer are not known. Survivin, an anti-apoptosis protein, is overexpressed in stem, progenitor, and cancer cells. In gastric cancer, increased and sustained survivin expression provides survival advantage and facilitates tumor progression and resistance to anti-cancer drugs. Aurora-B kinase is essential for chromosome alignment and mitosis progression but surprisingly its role in gastric cancer has not been explored. We examined in human gastric cancer AGS cells: (1) survivin expression, (2) localization of survivin and Aurora-B (3) cell proliferation, and (4) effects of specific survivin siRNA and/or rebamipide (free radical scavenging drug) on survivin and Aurora-B expression and cell proliferation. Survivin and Aurora-B are strongly expressed in human AGS gastric cancer cells and co-localize during mitosis. Survivin siRNA significantly reduces AGS cell viability. Rebamipide significantly downregulates in AGS cell survivin expression, its association with Aurora-B and cell proliferation. Rebamipide-induced downregulation of survivin is at the transcription level and does not involve ubiquitin-proteasome pathway.

  11. Aurora kinase inhibitors reveal mechanisms of HURP in nucleation of centrosomal and kinetochore microtubules

    PubMed Central

    Wu, Jiun-Ming; Chen, Chiung-Tong; Coumar, Mohane Selvaraj; Lin, Wen-Hsin; Chen, Zi-Jie; Hsu, John T.-A.; Peng, Yi-Hui; Shiao, Hui-Yi; Lin, Wen-Hsing; Chu, Chang-Ying; Wu, Jian-Sung; Lin, Chih-Tsung; Chen, Ching-Ping; Hsueh, Ching-Cheng; Chang, Kai-Yen; Kao, Li-Pin; Huang, Chi-Ying F.; Chao, Yu-Sheng; Wu, Su-Ying; Hsieh, Hsing-Pang; Chi, Ya-Hui

    2013-01-01

    The overexpression of Aurora kinases in multiple tumors makes these kinases appealing targets for the development of anticancer therapies. This study identified two small molecules with a furanopyrimidine core, IBPR001 and IBPR002, that target Aurora kinases and induce a DFG conformation change at the ATP site of Aurora A. Our results demonstrate the high potency of the IBPR compounds in reducing tumorigenesis in a colorectal cancer xenograft model in athymic nude mice. Human hepatoma up-regulated protein (HURP) is a substrate of Aurora kinase A, which plays a crucial role in the stabilization of kinetochore fibers. This study used the IBPR compounds as well as MLN8237, a proven Aurora A inhibitor, as chemical probes to investigate the molecular role of HURP in mitotic spindle formation. These compounds effectively eliminated HURP phosphorylation, thereby revealing the coexistence and continuous cycling of HURP between unphosphorylated and phosphorylated forms that are associated, respectively, with microtubules emanating from centrosomes and kinetochores. Furthermore, these compounds demonstrate a spatial hierarchical preference for HURP in the attachment of microtubules extending from the mother to the daughter centrosome. The finding of inequality in the centrosomal microtubules revealed by these small molecules provides a versatile tool for the discovery of new cell-division molecules for the development of antitumor drugs. PMID:23610398

  12. Combined cisplatin and aurora inhibitor treatment increase neuroblastoma cell death but surviving cells overproduce BDNF

    PubMed Central

    Polacchini, Alessio; Albani, Clara; Baj, Gabriele; Colliva, Andrea; Carpinelli, Patrizia

    2016-01-01

    ABSTRACT Drug-resistance to chemotherapics in aggressive neuroblastoma (NB) is characterized by enhanced cell survival mediated by TrkB and its ligand, brain-derived neurotrophic factor (BDNF); thus reduction in BDNF levels represent a promising strategy to overcome drug-resistance, but how chemotherapics regulate BDNF is unknown. Here, cisplatin treatment in SK-N-BE neuroblastoma upregulated multiple BDNF transcripts, except exons 5 and 8 variants. Cisplatin increased BDNF mRNA and protein, and enhanced translation of a firefly reporter gene flanked by BDNF 5′UTR exons 1, 2c, 4 or 6 and 3′UTR-long. To block BDNF translation we focused on aurora kinases inhibitors which are proposed as new chemotherapeutics. NB cell survival after 24 h treatment was 43% with cisplatin, and 22% by cisplatin+aurora kinase inhibitor PHA-680632, while the aurora kinases inhibitor alone was less effective; however the combined treatment induced a paradoxical increase of BDNF in surviving cells with strong translational activation of exon6-3′UTR-long transcript, while translation of BDNF transcripts 1, 2C and 4 was suppressed. In conclusion, combined cisplatin and aurora kinase inhibitor treatment increases cell death, but induces BDNF overproduction in surviving cells through an aurora kinase-independent mechanism. PMID:27256407

  13. Urochordate Ascidians Possess a Single Isoform of Aurora Kinase That Localizes to the Midbody via TPX2 in Eggs and Cleavage Stage Embryos

    PubMed Central

    Hebras, Celine; McDougall, Alex

    2012-01-01

    Aurora kinases are key proteins found throughout the eukaryotes that control mitotic progression. Vertebrate Aurora-A and B kinases are thought to have evolved from a single Aurora-kinase isoform closest to that found in present day urochordates. In urochordate ascidians Aurora binds both TPX2 (a vertebrate AURKA partner) and INCENP (a vertebrate AURKB partner) and localizes to centrosomes and spindle microtubules as well as chromosomes and midbody during both meiosis and mitosis. Ascidian Aurora also displays this localization pattern during mitosis in echinoderms, strengthening the idea that non-vertebrate deuterostomes such as the urochordates and echinoderms possess a single form of Aurora kinase that has properties of vertebrate Aurora-kinase A and B. In the ascidian, TPX2 localizes to the centrosome and the spindle poles also as in vertebrates. However, we were surprised to find that TPX2 also localized strongly to the midbody in ascidian eggs and embryos. We thus examined more closely Aurora localization to the midbody by creating two separate point mutations of ascidian Aurora predicted to perturb binding to TPX2. Both forms of mutated Aurora behaved as predicted: neither localized to spindle poles where TPX2 is enriched. Interestingly, neither form of mutated Aurora localized to the midbody where TPX2 is also enriched, suggesting that ascidian Aurora midbody localization required TPX2 binding in ascidians. Functional analysis revealed that inhibition of Aurora kinase with a pharmacological inhibitor or with a dominant negative kinase dead form of Aurora caused cytokinesis failure and perturbed midbody formation during polar body extrusion. Our data support the view that vertebrate Aurora-A and B kinases evolved from a single non-vertebrate deuterostome ancestor. Moreover, since TPX2 localizes to the midbody in ascidian eggs and cleavage stage embryos it may be worthwhile re-assessing whether Aurora A kinase or TPX2 localize to the midbody in eggs and

  14. Structure-based design of imidazo[1,2-a]pyrazine derivatives as selective inhibitors of Aurora-A kinase in cells.

    PubMed

    Bouloc, Nathalie; Large, Jonathan M; Kosmopoulou, Magda; Sun, Chongbo; Faisal, Amir; Matteucci, Mizio; Reynisson, Jóhannes; Brown, Nathan; Atrash, Butrus; Blagg, Julian; McDonald, Edward; Linardopoulos, Spiros; Bayliss, Richard; Bavetsias, Vassilios

    2010-10-15

    Co-crystallisation of the imidazo[1,2-a]pyrazine derivative 15 (3-chloro-N-(4-morpholinophenyl)-6-(pyridin-3-yl)imidazo[1,2-a]pyrazin-8-amine) with Aurora-A provided an insight into the interactions of this class of compound with Aurora kinases. This led to the design and synthesis of potent Aurora-A inhibitors demonstrating up to 70-fold selectivity in cell-based Aurora kinase pharmacodynamic biomarker assays. PMID:20833547

  15. Selective Disruption of Aurora C Kinase Reveals Distinct Functions from Aurora B Kinase during Meiosis in Mouse Oocytes

    PubMed Central

    Balboula, Ahmed Z.; Schindler, Karen

    2014-01-01

    Aurora B kinase (AURKB) is the catalytic subunit of the chromosomal passenger complex (CPC), an essential regulator of chromosome segregation. In mitosis, the CPC is required to regulate kinetochore microtubule (K-MT) attachments, the spindle assembly checkpoint, and cytokinesis. Germ cells express an AURKB homolog, AURKC, which can also function in the CPC. Separation of AURKB and AURKC function during meiosis in oocytes by conventional approaches has not been successful. Therefore, the meiotic function of AURKC is still not fully understood. Here, we describe an ATP-binding-pocket-AURKC mutant, that when expressed in mouse oocytes specifically perturbs AURKC-CPC and not AURKB-CPC function. Using this mutant we show for the first time that AURKC has functions that do not overlap with AURKB. These functions include regulating localized CPC activity and regulating chromosome alignment and K-MT attachments at metaphase of meiosis I (Met I). We find that AURKC-CPC is not the sole CPC complex that regulates the spindle assembly checkpoint in meiosis, and as a result most AURKC-perturbed oocytes arrest at Met I. A small subset of oocytes do proceed through cytokinesis normally, suggesting that AURKC-CPC is not the sole CPC complex during telophase I. But, the resulting eggs are aneuploid, indicating that AURKC is a critical regulator of meiotic chromosome segregation in female gametes. Taken together, these data suggest that mammalian oocytes contain AURKC to efficiently execute meiosis I and ensure high-quality eggs necessary for sexual reproduction. PMID:24586209

  16. Pten regulates Aurora-A and cooperates with Fbxw7 in modulating radiation-induced tumor development

    PubMed Central

    Kwon, Yong-Won; Kim, Il-Jin; Wu, Di; Lu, Jing; Stock, William A; Liu, Yueyong; Huang, Yurong; Kang, Hio Chung; DelRosario, Reyno; Jen, Kuang-Yu; Perez-Losada, Jesus; Wei, Guangwei; Balmain, Allan; Mao, Jian-Hua

    2012-01-01

    The Aurora-A kinase gene is frequently amplified and/or over-expressed in a variety of human cancers, leading to major efforts to develop therapeutic agents targeting this pathway. Here we demonstrate that Aurora-A is targeted for ubiquitination and subsequent degradation by the F-box protein FBXW7 in a process that is regulated by GSK3β. Using a series of truncated Aurora-A proteins and site directed mutagenesis, we identified distinct FBXW7 and GSK3β binding sites in Aurora-A. Mutation of critical residues in either site substantially disrupts degradation of Aurora-A. Furthermore, we show that loss of Pten results in the stabilization of Aurora-A by attenuating FBXW7-dependent degradation of Aurora-A through the AKT/GSK3β pathway. Moreover, radiation-induced tumor latency is significantly shortened in Fbxw7+/− Pten+/− mice as compared to either Fbxw7+/− or Pten+/− mice, indicating that Fbxw7 and Pten appear to cooperate in suppressing tumorigenesis. Our results establish a novel posttranslational regulatory network in which the Pten and Fbxw7 pathways appear to converge on the regulation of Aurora-A level. PMID:22513362

  17. The Aurora-A inhibitor MLN8237 affects multiple mitotic processes and induces dose-dependent mitotic abnormalities and aneuploidy

    PubMed Central

    Asteriti, Italia Anna; Cesare, Erica Di; Mattia, Fabiola De; Hilsenstein, Volker; Neumann, Beate; Cundari, Enrico; Lavia, Patrizia; Guarguaglini, Giulia

    2014-01-01

    Inhibition of Aurora kinase activity by small molecules is being actively investigated as a potential anti-cancer strategy. A successful therapeutic use of Aurora inhibitors relies on a comprehensive understanding of the effects of inactivating Aurora kinases on cell division, a challenging aim given the pleiotropic roles of those kinases during mitosis. Here we have used the Aurora-A inhibitor MLN8237, currently under phase-I/III clinical trials, in dose-response assays in U2OS human cancer cells synchronously proceeding towards mitosis. By following the behaviour and fate of single Aurora-inhibited cells in mitosis by live microscopy, we show that MLN8237 treatment affects multiple processes that are differentially sensitive to the loss of Aurora-A function. A role of Aurora-A in controlling the orientation of cell division emerges. MLN8237 treatment, even in high doses, fails to induce efficient elimination of dividing cells, or of their progeny, while inducing significant aneuploidy in daughter cells. The results of single-cell analyses show a complex cellular response to MLN8237 and evidence that its effects are strongly dose-dependent: these issues deserve consideration in the light of the design of strategies to kill cancer cells via inhibition of Aurora kinases. PMID:25153724

  18. Two Universities and Two Eras of Catholicism in China: Fu Jen University and Aurora University, 1903-1937

    ERIC Educational Resources Information Center

    Xian, Liu

    2009-01-01

    This paper compares Fu Jen University in Beijing and Aurora University in Shanghai--the two comprehensive Catholic universities located in the two largest cities of China in modern history--and analyzes four aspects: identity, educational idea, curriculum, and campus culture. It was found that the differences between Aurora and Fu Jen resulted…

  19. The Aurora-A inhibitor MLN8237 affects multiple mitotic processes and induces dose-dependent mitotic abnormalities and aneuploidy.

    PubMed

    Asteriti, Italia Anna; Di Cesare, Erica; De Mattia, Fabiola; Hilsenstein, Volker; Neumann, Beate; Cundari, Enrico; Lavia, Patrizia; Guarguaglini, Giulia

    2014-08-15

    Inhibition of Aurora kinase activity by small molecules is being actively investigated as a potential anti-cancer strategy. A successful therapeutic use of Aurora inhibitors relies on a comprehensive understanding of the effects of inactivating Aurora kinases on cell division, a challenging aim given the pleiotropic roles of those kinases during mitosis. Here we have used the Aurora-A inhibitor MLN8237, currently under phase-I/III clinical trials, in dose-response assays in U2OS human cancer cells synchronously proceeding towards mitosis. By following the behaviour and fate of single Aurora-inhibited cells in mitosis by live microscopy, we show that MLN8237 treatment affects multiple processes that are differentially sensitive to the loss of Aurora-A function. A role of Aurora-A in controlling the orientation of cell division emerges. MLN8237 treatment, even in high doses, fails to induce efficient elimination of dividing cells, or of their progeny, while inducing significant aneuploidy in daughter cells. The results of single-cell analyses show a complex cellular response to MLN8237 and evidence that its effects are strongly dose-dependent: these issues deserve consideration in the light of the design of strategies to kill cancer cells via inhibition of Aurora kinases. PMID:25153724

  20. MI Coupling Processes in the Regions of Diffuse Aurora: Ionospheric Outlook

    NASA Astrophysics Data System (ADS)

    Khazanov, George V.; Glocer, Alex; Sibeck, David

    2016-04-01

    The precipitation of high-energy magnetospheric electrons in the diffuse aurora contributes significant energy flux into the Earth's ionosphere. In the diffuse aurora, precipitating electrons initially injected from the plasma sheet via wave-particle interaction processes degrade in the atmosphere toward lower energies and produce secondary electrons via impact ionization of the neutral atmosphere. These initially precipitating electrons of magnetospheric origin can be additionally reflected back into the magnetosphere, leading to a series of multiple reflections that can greatly influence the initially precipitating flux at the upper ionospheric boundary, the resultant population of secondary electrons, and electrons cascading toward lower energies. It is found that magnetosphere-ionosphere coupling is the key element in the formation of electron distribution function in the regions of diffuse aurora at ionospheric altitudes.

  1. Throat aurora: The ionospheric signature of magnetosheath particles penetrating into the magnetosphere

    NASA Astrophysics Data System (ADS)

    Han, D.-S.; Nishimura, Y.; Lyons, L. R.; Hu, H.-Q.; Yang, H.-G.

    2016-03-01

    Throat aurora is suggested to be generated during magnetospheric cold plasma flowing into the magnetopause reconnection site and to be the ionospheric signature of the newly opened flux from reconnection. By examining simultaneous low-altitude satellites and ground observations, we confirm that the throat auroras are associated with low-energy electron and ion precipitation of magnetosheath type and thus provide the first evidence that they occur along open magnetic field lines. Additionally, the observations have important possible implications: (1) solar wind particles can penetrate deep into the magnetosphere and may make significant contributions to the low-energy plasmas often observed in the dayside outer magnetosphere and (2) localized shapes of the magnetopause and the ionospheric open-closed field line boundary may be substantially changed, during generation of the throat aurora.

  2. ATR and a Chk1-Aurora B pathway coordinate postmitotic genome surveillance with cytokinetic abscission

    PubMed Central

    Mackay, Douglas R.; Ullman, Katharine S.

    2015-01-01

    Aurora B regulates cytokinesis timing and plays a central role in the abscission checkpoint. Cellular events monitored by this checkpoint are beginning to be elucidated, yet signaling pathways upstream of Aurora B in this context remain poorly understood. Here we reveal a new connection between postmitotic genome surveillance and cytokinetic abscission. Underreplicated DNA lesions are known to be transmitted through mitosis and protected in newly formed nuclei by recruitment of 53BP1 and other proteins until repair takes place. We find that this genome surveillance initiates before completion of cytokinesis. Elevating replication stress increases this postmitotic process and delays cytokinetic abscission by keeping the abscission checkpoint active. We further find that ATR activity in midbody-stage cells links postmitotic genome surveillance to abscission timing and that Chk1 integrates this and other signals upstream of Aurora B to regulate when the final step in the physical separation of daughter cells occurs. PMID:25904336

  3. Let7a inhibits the growth of endometrial carcinoma cells by targeting Aurora-B.

    PubMed

    Liu, Ping; Qi, Meiyan; Ma, Chengbin; Lao, Guoying; Liu, Yu; Liu, Yan; Liu, Yingzi

    2013-08-19

    MicroRNAs negatively regulate target gene expression at the post-transcriptional level during carcinogenesis. Recent advances revealed that the expression levels of several miRNAs are up- or down-regulated in endometrial carcinoma (EC). Here we identify dysregulated miRNAs in EC and we elucidate the essential role of let-7a. The expression of 86 miRNAs in EC was found to be different from adjacent normal endometrial tissues. Moreover, miR-let-7 members are down-regulated in EC and let-7 miRNAs are highly associated with endometrial cancer. A functional investigation revealed that let-7a suppressed proliferation of HeLa cells by targeting Aurora-B. Let-7a also antagonizes Aurora-B functions in promoting carcinoma cell proliferation by down-regulating Aurora-B protein level. Let-7a could be applied for gene therapy against endometrial carcinogenesis. PMID:23769985

  4. A Multi-wavelength campaign to study the Jovian aurora and the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Murray, Stephen

    2013-09-01

    We request 2 40ks HRC-I observations of Jupiter to be made in Apr 2014 in support of the SPRINT-A mission to study the Jovian aurora and the Io plasma torus. SPRINT-A will make sensitive EUV spectroscopic measurements of the upper atmospheres and magnetospheres of planets in the Solar system. The coordinated multi-wavelength campaign to observe the Jovian auroras and the Io plasma torus will provide an unprecedented study of the plasma content of the Jovian magnetosphere. Our X-ray observations will monitor the flux and morphology of the tens to hundreds of eV thermal plasma in the aurora and magnetosphere, and our coordinated observations will determine whether outflows from Io or interaction with the Solar wind are responsible for creating this hot, X-ray emitting plasma.

  5. Spatial-temporal dynamics of auroras during the magnetic storm main phase

    NASA Astrophysics Data System (ADS)

    Kornilova, T. A.; Kornilov, I. A.

    2009-12-01

    The structure and dynamics of auroras in the midnight sector during substorms, which develop during the magnetic storm main phase as compared to the characteristics of a typical auroral substorm, have been studied using the ground-based and satellite observations. It has been found out that a difference from the classical substorm is observed in auroras during the magnetic storm main phase. At the beginning of the storm main phase, the series of pseudobreakups with the most pronounced jump-like motion toward the equator shifts to lower latitudes. The substorm expansion phase can be observed not only as arc jumps to higher latitudes but also as an explosive expansion of a bright diffuse luminosity in all directions. During the magnetic storm main phase, auroras are mainly characterized by the presence of stable extensive rayed structures and by the simultaneous existence of different auroral forms, typical of different substorm phases, in the TV camera field of view.

  6. ATR and a Chk1-Aurora B pathway coordinate postmitotic genome surveillance with cytokinetic abscission.

    PubMed

    Mackay, Douglas R; Ullman, Katharine S

    2015-06-15

    Aurora B regulates cytokinesis timing and plays a central role in the abscission checkpoint. Cellular events monitored by this checkpoint are beginning to be elucidated, yet signaling pathways upstream of Aurora B in this context remain poorly understood. Here we reveal a new connection between postmitotic genome surveillance and cytokinetic abscission. Underreplicated DNA lesions are known to be transmitted through mitosis and protected in newly formed nuclei by recruitment of 53BP1 and other proteins until repair takes place. We find that this genome surveillance initiates before completion of cytokinesis. Elevating replication stress increases this postmitotic process and delays cytokinetic abscission by keeping the abscission checkpoint active. We further find that ATR activity in midbody-stage cells links postmitotic genome surveillance to abscission timing and that Chk1 integrates this and other signals upstream of Aurora B to regulate when the final step in the physical separation of daughter cells occurs. PMID:25904336

  7. Aurora kinase A controls meiosis I progression in mouse oocytes

    PubMed Central

    Saskova, Adela; Solc, Petr; Baran, Vladimir; Kubelka, Michal; Schultz, Richard M.; Motlik, Jan

    2011-01-01

    Aurora kinase A (AURKA), which is a centrosome-localized serine/threonine kinase crucial for cell cycle control, is critically involved in centrosome maturation and spindle assembly in somatic cells. Active T288 phosphorylated AURKA localizes to the centrosome in the late G2 and also spreads to the minus ends of mitotic spindle microtubules. AURKA activates centrosomal CDC25B and recruits cyclin B1 to centrosomes. We report here functions for AURKA in meiotic maturation of mouse oocytes, which is a model system to study the G2 to M transition. Whereas AURKA is present throughout the entire GV-stage oocyte with a clear accumulation on microtubule organizing centers (MTOC), active AURKA becomes entirely localized to MTOCs shortly before germinal vesicle breakdown. In contrast to somatic cells in which active AURKA is present at the centrosomes and minus ends of microtubules, active AURKA is mainly located on MTOCs at metaphase I (MI) in oocytes. Inhibitor studies using Roscovitine (CDK1 inhibitor), LY-294002 (PI3K inhibitor) and SH-6 (PKB inhibitor) reveal that activation of AURKA localized on MTOCs is independent on PI3K-PKB and CDK1 signaling pathways and MOTC amplification is observed in roscovitine- and SH-6-treated oocytes that fail to undergo nuclear envelope breakdown. Moreover, microinjection of Aurka mRNA into GV-stage oocytes cultured in 3-isobutyl-1-methyl xanthine (IBMX)-containing medium to prevent maturation also results in MOTC amplification in the absence of CDK1 activation. Overexpression of AURKA also leads to formation of an abnormal MI spindle, whereas RNAi-mediated reduction of AURKA interferes with resumption of meiosis and spindle assembly. Results of these experiments indicate that AURKA is a critical MTOC-associated component involved in resumption of meiosis, MTOC multiplication, proper spindle formation and the metaphase I-metaphase II transition. PMID:18677115

  8. Kilometric radiation power flux dependence on area of discrete aurora

    NASA Technical Reports Server (NTRS)

    Saflekos, N. A.; Burch, J. L.; Gurnett, D. A.; Anderson, R. R.; Sheehan, R. E.

    1989-01-01

    Kilometer wavelength radiation, measured from distant positions over the North Pole and over the Earth's equator, was compared to the area of discrete aurora imaged by several low-altitude spacecraft. Through correlative studies of auroral kilometric radiation (AKR) with about two thousand auroral images, a stereoscopic view of the average auroral acceleration region was obtained. A major result is that the total AKR power increases as the area of the discrete auroral oval increases. The implications are that the regions of parallel potentials or the auroral plasma cavities, in which AKR is generated, must possess the following attributes: (1) they are shallow in altitude and their radial position depends on wavelength, (2) they thread flux tubes of small cross section, (3) the generation mechanism in them reaches a saturation limit rapidly, and (4) their distribution over the discrete auroral oval is nearly uniform. The above statistical results are true for large samples collected over a long period of time (about six months). In the short term, AKR frequently exhibits temporal variations with scales as short as three minutes (the resolution of the averaged data used). These fluctuations are explainable by rapid quenchings as well as fast starts of the electron cyclotron maser mechanism. There were times when AKR was present at substantial power levels while optical emissions were below instrument thresholds. A recent theoretical result may account for this set of observations by predicting that suprathermal electrons, of energies as low as several hundred eV, can generate second harmonic AKR. The indirect observations of second harmonic AKR require that these electrons have mirror points high above the atmosphere so as to minimize auroral light emissions. The results provide evidence supporting the electron cyclotron maser mechanism.

  9. Water resources of Aurora and Jerauld Counties, South Dakota

    USGS Publications Warehouse

    Hamilton, L.J.

    1985-01-01

    Large quantities of slightly saline ground water are available for future water requirements in Aurora and Jerauld Counties, 1 ,236 square miles of glaciated, till-covered hills and plains in southeastern South Dakota. More than one million acre-feet of ground water is stored in five major glacial aquifers, outwash sand and gravel, beneath 340 square miles. About 58 million acre-feet is stored in bedrock, in the Niobrara marl aquifer, the Codell sandstone aquifer, and the Dakota sandstone aquifer. Recharge of aquifers by infiltration of precipitation totals 31 ,000 acre-feet annually. Effects of increased ground-water withdrawals generally have been small for glacial aquifers and large for some bedrock aquifers. Water levels declined 0.6 to 4 feet in glacial aquifers during 1978-80 within a mile of irrigation wells pumping 300 to 1,000 gallons per minute. In contrast, water levels declined 40 feet near a well pumping 1 ,500 gallons per minute from the Niobrara aquifer because of small artesian storage. Artesian pressure of the Dakota aquifer declined about 200 feet between 1909 and 1979 because of large withdrawals through flowing wells. The availability of surface water is limited because streams are ephemeral and have large flows only during spring of wet years. Most of the lakes are small, semipermanent, and shallow. Most surface water in the study area contains low concentrations of dissolved solids but most of the ground water is very hard and slightly saline. Some ground water has a very high-salinity hazard for irrigation. Water from the Niobrara and Codell aquifers also has a high sodium hazard and high boron concentrations. (USGS)

  10. Project Aether Aurora: STEM outreach near the arctic circle

    NASA Astrophysics Data System (ADS)

    Longmier, B. W.; Bering, E. A.

    2012-12-01

    Project Aether is a program designed to immerse high-school through graduate students to field research in some of the fields of STEM. The program leaders launch high altitude weather balloons in collaboration with schools and students to teach physics concepts, experimental research skills, and to make space exploration accessible to students. A weather balloon lifts a specially designed payload package that is composed of HD cameras, GPS tracking devices, and other science equipment. The payload is constructed and attached to the balloon by the students with low-cost materials. The balloon and payload are launched with FAA clearance from a site chosen based on wind patterns and predicted landing locations. The balloon ascends over 2 hours to a maximum altitude of 100,000 feet where it bursts and allows the payload to slowly descend using a built-in parachute. The balloon's location is monitored during its flight by GPS-satellite relay. Most of the science and video data are recorded on SD cards using an Arduino digitizer. The payload is located using the GPS device. The science data are recovered from the payload and shared with the students. In April 2012, Project Aether leaders conducted a field campaign near Fairbanks Alaska, sending several student-built experiments to an altitude of 30km, underneath several strong auroral displays. Auroral physics experiments that can be done on ultra small balloons (5 cubic meters) include electric field and magnetic fluctuation observations, full spectrum and narrow band optical imaging, GPS monitoring of the total electron content of the ionosphere, x-ray detection and infrared and UV spectroscopy. The actual undergraduate student experiments will be reviewed and some data presented.; Balloon deployment underneath aurora, Fairbanks Alaska, 2012.

  11. Discovery of a Previously Unrecognised Allusion to the Aurora Borealis in Paradise Lost, and Implications for Edmund Halley Scholarship

    NASA Astrophysics Data System (ADS)

    Cunningham, Clifford J.

    2014-11-01

    This research reveals that John Milton employed an allusion to the aurora borealis in the epic poem Paradise Lost which has not been recognised in more than three centuries of scholarly analysis. It further disproves the long-held belief, made popular by the astronomer Edmund Halley, that no notable aurora was visible in England in the seventeenth century. A study of the personal Latin diary of the Elizabethan historian William Camden shows that the famous aurora of 1621 was visible in England. While Pierre Gassendi has been credited with creation of the term 'aurora borealis' based on his report of the 1621 aurora, this study reaffirms a neglected analysis from 1986 that established the term originated with Galileo in 1619.

  12. Benzimidazole-Based Quinazolines: In Vitro Evaluation, Quantitative Structure-Activity Relationship, and Molecular Modeling as Aurora Kinase Inhibitors.

    PubMed

    Sharma, Alka; Luxami, Vijay; Saxena, Sanjai; Paul, Kamaldeep

    2016-03-01

    A series of benzimidazole-based quinazoline derivatives with different substitutions of primary and secondary amines at the C2 position (1-12) were evaluated for their Aurora kinase inhibitory activities. All compounds except for 3 and 6 showed good activity against Aurora kinase inhibitors, with IC50 values in the range of 0.035-0.532 μM. The ligand efficiency (LE) of the compounds with Aurora A kinase was also determined. The structure-activity relationship and the quantitative structure-activity relationship revealed that the Aurora inhibitory activities of these derivatives primarily depend on the different substitutions of the amine present at the C2 position of the quinazoline core. Molecular docking studies in the active binding site also provided theoretical support for the experimental biological data acquired. The current study identifies a novel class of Aurora kinase inhibitors, which can further be used for the treatment of cancer. PMID:26773437

  13. Aurora a Overexpression and pVHL Reduced Expression Are Correlated with a Bad Kidney Cancer Prognosis

    PubMed Central

    Ferchichi, Imen; Kourda, Nadia; Sassi, Samia; Romdhane, Khaled Ben; Balatgi, Sarra; Cremet, Jean Yves; Prigent, Claude; Elgaaied, Amel Benammar

    2012-01-01

    We investigate the expression and localization of the tumor suppressor protein pVHL as well as the oncoprotein Aurora A kinase in kidney cancer. Both Aurora A kinase and pVHL protein status were evaluated using immunohistochemistry. The Aurora A expression is correlated with the Fuhrman grade and the TNM stage, while the pVHL expression is correlated with the capsule rupture and the TNM stage. Aurora A kinase expression increases in malignant tissue comparing to the non-malignant one. And there is a decrease in pVHL expression from the adjacent healthy tissues to the tumor`s ones. The two kinds of opposite tumor profiles display significant distribution difference according to TNM stages. It could be proposed that the absence of Aurora A protein associated with a strong expression of pVHL in clear cells kidney carcinoma are of good prognosis for the disease. PMID:23151618

  14. Aurora Flight Sciences' Perseus B Remotely Piloted Aircraft in Flight

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A long, slender wing and a pusher propeller at the rear characterize the Perseus B remotely piloted research aircraft, seen here during a test flight in June 1998. Perseus B is a remotely piloted aircraft developed as a design-performance testbed under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) project. Perseus is one of several flight vehicles involved in the ERAST project. A piston engine, propeller-powered aircraft, Perseus was designed and built by Aurora Flight Sciences Corporation, Manassas, Virginia. The objectives of Perseus B's ERAST flight tests have been to reach and maintain horizontal flight above altitudes of 60,000 feet and demonstrate the capability to fly missions lasting from 8 to 24 hours, depending on payload and altitude requirements. The Perseus B aircraft established an unofficial altitude record for a single-engine, propeller-driven, remotely piloted aircraft on June 27, 1998. It reached an altitude of 60,280 feet. In 1999, several modifications were made to the Perseus aircraft including engine, avionics, and flight-control-system improvements. These improvements were evaluated in a series of operational readiness and test missions at the Dryden Flight Research Center, Edwards, California. Perseus is a high-wing monoplane with a conventional tail design. Its narrow, straight, high-aspect-ratio wing is mounted atop the fuselage. The aircraft is pusher-designed with the propeller mounted in the rear. This design allows for interchangeable scientific-instrument payloads to be placed in the forward fuselage. The design also allows for unobstructed airflow to the sensors and other devices mounted in the payload compartment. The Perseus B that underwent test and development in 1999 was the third generation of the Perseus design, which began with the Perseus Proof-Of-Concept aircraft. Perseus was initially developed as part of NASA's Small High-Altitude Science Aircraft (SHASA) program, which later evolved into the ERAST

  15. Europa's far ultraviolet oxygen aurora from a comprehensive set of HST observations

    NASA Astrophysics Data System (ADS)

    Roth, Lorenz; Saur, Joachim; Retherford, Kurt D.; Strobel, Darrell F.; Feldman, Paul D.; McGrath, Melissa A.; Spencer, John R.; Blöcker, Aljona; Ivchenko, Nickolay

    2016-03-01

    We analyze a large set of far ultraviolet oxygen aurora images of Europa's atmosphere taken by Hubble's Space Telescope Imaging Spectrograph (HST/STIS) in 1999 and on 19 occasions between 2012 and 2015. We find that both brightness and aurora morphology undergo systematic variations correlated to the periodically changing plasma environment. The time variable morphology seems to be strongly affected by Europa's interaction with the magnetospheric plasma. The brightest emissions are often found in the polar region where the ambient Jovian magnetic field line is normal to Europa's disk. Near the equator, where bright spots are found at Io, Europa's aurora is faint suggesting a general difference in how the plasma interaction shapes the aurora at Io and Europa. The dusk side is consistently brighter than the dawnside with only few exceptions, which cannot be readily explained by obvious plasma physical or known atmospheric effects. Brightness ratios of the near-surface OI] 1356 Što OI 1304 Šemissions between 1.5 and 2.8 with a mean ratio of 2.0 are measured, confirming that Europa's bound atmosphere is dominated by O2. The 1356/1304 ratio decreases with increasing altitude in agreement with a more extended atomic O corona, but O2 prevails at least up to altitudes of ˜900 km. Differing 1356/1304 line ratios on the plasma upstream and downstream hemispheres are explained by a differing O mixing ratio in the near-surface O2 atmosphere of ˜5% (upstream) and ≲1% (downstream), respectively. During several eclipse observations, the aurora does not reveal any signs of systematic changes compared to the sunlit images suggesting no or only weak influence of sunlight on the aurora and an optically thin atmosphere.

  16. NuMA Phosphorylation by Aurora-A Orchestrates Spindle Orientation.

    PubMed

    Gallini, Sara; Carminati, Manuel; De Mattia, Fabiola; Pirovano, Laura; Martini, Emanuele; Oldani, Amanda; Asteriti, Italia Anna; Guarguaglini, Giulia; Mapelli, Marina

    2016-02-22

    Spindle positioning is essential for tissue morphogenesis and homeostasis. The signaling network synchronizing spindle placement with mitotic progression relies on timely recruitment at the cell cortex of NuMA:LGN:Gαi complexes, in which NuMA acts as a receptor for the microtubule motor Dynein. To study the implication of Aurora-A in spindle orientation, we developed protocols for the partial inhibition of its activity. Under these conditions, in metaphase NuMA and Dynein accumulate abnormally at the spindle poles and do not reach the cortex, while the cortical distribution of LGN remains unperturbed. FRAP experiments revealed that Aurora-A governs the dynamic exchange between the cytoplasmic and the spindle pole-localized pools of NuMA. We show that Aurora-A phosphorylates directly the C terminus of NuMA on three Ser residues, of which Ser1969 determines the dynamic behavior and the spindle orientation functions of NuMA. Most interestingly, we identify a new microtubule-binding domain of NuMA, which does not overlap with the LGN-binding motif. Our study demonstrates that in metaphase the direct phosphorylation of NuMA by Aurora-A controls its cortical enrichment, and that this is the major event underlying the spindle orientation functions of Aurora-A in transformed and non-transformed cells in culture. Phosphorylation of NuMA by Aurora-A does not affect its affinity for microtubules or for LGN but rather determines the mobility of the protein at the spindle poles. The finding that NuMA can associate concomitantly with LGN and microtubules suggests that its microtubule-binding activity contributes to anchor Dynein-loaded microtubule +TIPs at cortical sites with LGN. PMID:26832443

  17. A High Resolution Magnetohydrodynamic Simulation Study of Kronian Field-Aligned Currents and Aurora

    NASA Astrophysics Data System (ADS)

    Fukazawa, K.; Ogino, T.; Walker, R. J.

    2011-12-01

    Magnetohydrodynamic simulations of the interaction of Saturn's magnetosphere with the solar wind indicate that Kelvin-Helmholtz (K-H) waves can form on the dayside magnetopause when the interplanetary magnetic field (IMF) is northward. Dayside magnetic reconnection occurs at Saturn for northward IMF. The combination of K-H waves and reconnection caused enhanced vorticity in Saturn's magnetosphere. We have used a very high resolution version (grid interval is 0.1 RS) of our simulation code to study the consequences of the vortices and reconnection for the generation of field aligned currents (FAC) and aurorae in Saturn's ionosphere. We found three bands of alternating FAC toward and away from the dawn side of the ionosphere and two sets on the dusk side. The K-H waves generated a series of toward and away currents along the dayside side magnetopause. In the ionosphere they appear as a series of spots of up and down current. The K-H field aligned currents are adjacent to nearly continuous currents located from 1600 LT around past midnight to about 0700 LT The largest currents (jpara> 5×10-8 A /m-2) are found are at the highest latitudes. They map to the magnetopause and to the near-Earth tail region. In analogy with the Earth's ionosphere the field aligned currents away from Saturn can serve as a proxy for discrete aurorae. We used the away current density and the Knight relationship to estimate the energy flux from discrete aurorae and obtained ~1 mW /m-2 in the region with the strongest currents. Similar energy fluxes were found in the K-H related aurorae. This gave approximately 70 GW for the auroral power. We also investigated diffuse aurorae by using the energy flux in the absence of the field aligned currents. We found a region of enhanced thermal energy flux in the region where cusp aurorae are observed.

  18. A review of East Asian reports of aurorae and comets circa AD 775

    NASA Astrophysics Data System (ADS)

    Chapman, J.; Neuhäuser, D. L.; Neuhäuser, R.; Csikszentmihalyi, M.

    2015-08-01

    Given that a strong 14C variation in AD 775 has recently been suggested to be due to the largest solar flare ever recorded in history, it is relevant to investigate whether celestial events observed around that time may have been aurorae, possibly even very strong aurorae, or otherwise related to the 14C variation (e.g. a suggested comet impact with Earth's atmosphere). We critically review several celestial observations from AD 757 to the end of the 770s, most of which were previously considered to be true, and in some cases, strong aurorae; we discuss in detail the East Asian records and their wording. We conclude that probably none among the events after AD 770 was actually an aurora, including the event in AD 776 Jan, which was misdated for AD 774 or 775; the observed white qi phenomenon that happened above the moon in the south-east was most probably a halo effect near the full Moon - too late in any case to be related to the 14C variation in AD 774/5. There is another report of a similar (or identical) white qi phenomenon above the moon, reported just before a comet observation and dated to AD 776 Jan; the reported comet observed by the Chinese was misdated to AD 776, but actually sighted in AD 767. Our critical review of East Asian reports of aurorae circa AD 775 shows some very likely true Chinese auroral displays observed and reported for AD 762; there were also several events prior to AD 771 that may have been aurorae but are questionable.

  19. AT9283, a novel aurora kinase inhibitor, suppresses tumor growth in aggressive B-cell lymphomas.

    PubMed

    Qi, Wenqing; Liu, Xiaobing; Cooke, Laurence S; Persky, Daniel O; Miller, Thomas P; Squires, Matthew; Mahadevan, Daruka

    2012-06-15

    Aurora kinases are oncogenic serine/threonine kinases that play key roles in regulating the mitotic phase of the eukaryotic cell cycle. Auroras are overexpressed in numerous tumors including B-cell non-Hodgkin's lymphomas and are validated oncology targets. AT9283, a pan-aurora inhibitor inhibited growth and survival of multiple solid tumors in vitro and in vivo. In this study, we demonstrated that AT9283 had potent activity against Aurora B in a variety of aggressive B-(non-Hodgkin lymphoma) B-NHL cell lines. Cells treated with AT9283 exhibited endoreduplication confirming the mechanism of action of an Aurora B inhibitor. Also, treatment of B-NHL cell lines with AT9283 induced apoptosis in a dose and time dependent manner and inhibited cell proliferation with an IC(50) < 1 μM. It is well known that inhibition of auroras (A or B) synergistically enhances the effects of microtubule targeting agents such as taxanes and vinca alkaloids to induce antiproliferation and apoptosis. We evaluated whether AT9283 in combination with docetaxel is more efficient in inducing apoptosis than AT9283 or docetaxel alone. At very low doses (5 nM) apoptosis was doubled in the combination (23%) compared to AT9283 or docetaxel alone (10%). A mouse xenograft model of mantle cell lymphoma demonstrated that AT9283 at 15 mg/kg and docetaxel (10 mg/kg) alone had modest anti-tumor activity. However, AT9283 at 20 mg/kg and AT9283 (15 or 20 mg/kg) plus docetaxel (10 mg/kg) demonstrated a statistically significant tumor growth inhibition and enhanced survival. Together, our results suggest that AT9283 plus docetaxel may represent a novel therapeutic strategy in B-cell NHL and warrant early phase clinical trial evaluation. PMID:21796626

  20. Two Types of Aurora on Mars as Observed by MAVEN's Imaging UltraViolet Spectrograph

    NASA Astrophysics Data System (ADS)

    Schneider, N. M.; Deighan, J.; Jain, S.; Stiepen, A.; Stewart, I. F.; Larson, D. E.; Mitchell, D. L.; Mazelle, C. X.; Lee, C.; Lillis, R. J.; Evans, J. S.; Brain, D. A.; Stevens, M. H.; McClintock, W. E.; Chaffin, M.; Crismani, M. M. J.; Holsclaw, G. M.; Lefèvre, F.; Lo, D.; Clarke, J. T.; Montmessin, F.; Jakosky, B. M.

    2015-12-01

    The Imaging UltraViolet Spectrograph (IUVS) on the MAVEN spacecraft has detected two distinct types of auroral emission on Mars. First, we report the discovery of a low altitude, diffuse aurora spanning much of Mars' northern hemisphere coincident with a solar energetic particle outburst. IUVS observed northerly latitudes during late December 2014, detecting auroral emission in virtually all nightside observations for ~5 days spanning virtually all geographic longitudes. The vertical profile showed emission down to ~70 km altitude (1 microbar), deeper than confirmed at any other planet. The onset and duration of emission coincide with the observed arrival of solar energetic particles up to 200 keV precipitating directly and deeply into the atmosphere. Preliminary modeling of the precipitation, energy deposition and spectral line emission yields good matches to the observations. These observations represent a new class of planetary auroras produced in the Martian middle atmosphere. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit aurora more globally than Earth. Second, we confirm the existence of small patches of discrete aurora near crustal magnetic fields in Mars' southern hemisphere, as observed previously by SPICAM on Mars Express (Bertaux et al., Nature, 435, 790-794 (2005)). IUVS observed southern latitudes in July and August 2015, detecting discrete auroral emission in ~1% of suitable observations. Limb scans resolved both vertically and along-slit indicate this type of auroral emission was patchy on the scale of ~40 km, and located at higher altitudes ~140 km. The higher altitudes imply a lower energy of precipitating particles. The mix of spectral emissions also differed signficiantly from the discrete aurora, indicating different excitation and quenching processes. We will discuss the observed properties of the aurora and associated charged particle precipitation, as well as the broader implications of this high

  1. Two Types of Aurora on Mars as Observed by MAVEN's Imaging UltraViolet Spectrograph

    NASA Astrophysics Data System (ADS)

    Schneider, Nicholas M.; Deighan, J.; Jain, S. K.; Stiepen, A.; Larson, D.; Mitchell, D. L.; Lee, C. O.; Lillis, R.; Brain, D.; McClintock, W. E.; Chaffin, M. S.; Crismani, M.; Holsclaw, G. M.; Jakosky, B. M.; Mazelle, C.; Evans, J. S.; Stewart, A. I. F.; Stevens, M. H.; Clarke, J. T.; Montmessin, F.; Lefevre, F.; Lo, D.

    2015-11-01

    The Imaging UltraViolet Spectrograph (IUVS) on the MAVEN spacecraft has detected two distinct types of auroral emission on Mars. First, we report the discovery of a low altitude, diffuse aurora spanning much of Mars’ northern hemisphere coincident with a solar energetic particle outburst. IUVS observed northerly latitudes during late December 2014, detecting auroral emission in virtually all nightside observations for ~5 days spanning virtually all geographic longitudes. The vertical profile showed emission down to ~70 km altitude (1 microbar), deeper than confirmed at any other planet. The onset and duration of emission coincide with the observed arrival of solar energetic particles up to 200 keV precipitating directly and deeply into the atmosphere. Preliminary modeling of the precipitation, energy deposition and spectral line emission yields good matches to the observations. These observations represent a new class of planetary auroras produced in the Martian middle atmosphere. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit aurora more globally than Earth.Second, we confirm the existence of small patches of discrete aurora near crustal magnetic fields in Mars' southern hemisphere, as observed previously by SPICAM on Mars Express (Bertaux et al., Nature, 435, 790-794 (2005)). IUVS observed southern latitudes in July and August 2015, detecting discrete auroral emission in ~1% of suitable observations. Limb scans resolved both vertically and along-slit indicate this type of auroral emission was patchy on the scale of ~40 km, and located at higher altitudes ~140 km. The higher altitudes imply a lower energy of precipitating particles. The mix of spectral emissions also differed signficiantly from the diffuse aurora, indicating different excitation and quenching processes.We will discuss the observed properties of the aurora and associated charged particle precipitation, as well as the broader implications of this high

  2. Polarization of Pc1/EMIC waves and related proton auroras observed at Athabasca

    NASA Astrophysics Data System (ADS)

    Nomura, R.; Shiokawa, K.; Sakaguchi, K.; Otsuka, Y.; Connors, M. G.

    2010-12-01

    Electromagnetic ion cyclotron (EMIC) waves excited in the equatorial region of the magnetosphere by the ion cyclotron instability propagate along magnetic field lines to the ionosphere and are observed as Pc1 geomagnetic pulsations (Pc1) with frequencies at 0.2-5Hz on the ground. These Pc1 waves propagate horizontally through the ionospheric duct. Magnetospheric ions are scattered by the resonance with EMIC waves and precipitate to the ionosphere to cause isolated proton auroras at subauroral latitudes. One-to-one correspondence between isolated proton auroras and Pc1 waves was found by Sakaguchi et al. [JGR, 2008]. The mechanism of ionospheric duct propagation of Pc1 has been studied theoretically for the polarization characteristics [Graifinger, JGR, 1972; Fujita and Tamao, JGR, 1988], and observationally for the possible Pc1 source [e.g., Fraser et al., JATP, 1976] and for the spatial distribution of polarization mode [Hayashi et al., Can J. Phys., 1981] using ground magnetometers. However, comparison between the actual position and size of ionospheric Pc1 sources and the polarization characteristics of Pc1 waves has not been done. In order to investigate this relation, we compare the spectral and polarization parameters of Pc1 waves observed by a 64-Hz sampling induction magnetometer and the position and area of isolated proton auroras observed by an all-sky imager at Athabasca (ATH, 54.7N, 246.7E, magnetic latitude: 61.7N), for 13 one-to-one correspondent events of Pc1 waves and isolated proton auroras reported by Sakaguchi et al. [JGR, 2008]. We found that the major axis direction of Pc1 polarization varies depending on the area of the isolated proton aurora and on the distance from ATH to the aurora. In the presentation, we will discuss these results based on a multi-event study using data from three years of 2005-2008 in the context of the model calculation by Fujita and Tamao [1988].

  3. Aurora-A-Dependent Control of TACC3 Influences the Rate of Mitotic Spindle Assembly

    PubMed Central

    Joseph, Nimesh; Cavazza, Tommaso; Vernos, Isabelle; Pfuhl, Mark; Gergely, Fanni; Bayliss, Richard

    2015-01-01

    The essential mammalian gene TACC3 is frequently mutated and amplified in cancers and its fusion products exhibit oncogenic activity in glioblastomas. TACC3 functions in mitotic spindle assembly and chromosome segregation. In particular, phosphorylation on S558 by the mitotic kinase, Aurora-A, promotes spindle recruitment of TACC3 and triggers the formation of a complex with ch-TOG-clathrin that crosslinks and stabilises kinetochore microtubules. Here we map the Aurora-A-binding interface in TACC3 and show that TACC3 potently activates Aurora-A through a domain centered on F525. Vertebrate cells carrying homozygous F525A mutation in the endogenous TACC3 loci exhibit defects in TACC3 function, namely perturbed localization, reduced phosphorylation and weakened interaction with clathrin. The most striking feature of the F525A cells however is a marked shortening of mitosis, at least in part due to rapid spindle assembly. F525A cells do not exhibit chromosome missegregation, indicating that they undergo fast yet apparently faithful mitosis. By contrast, mutating the phosphorylation site S558 to alanine in TACC3 causes aneuploidy without a significant change in mitotic duration. Our work has therefore defined a regulatory role for the Aurora-A-TACC3 interaction beyond the act of phosphorylation at S558. We propose that the regulatory relationship between Aurora-A and TACC3 enables the transition from the microtubule-polymerase activity of TACC3-ch-TOG to the microtubule-crosslinking activity of TACC3-ch-TOG-clathrin complexes as mitosis progresses. Aurora-A-dependent control of TACC3 could determine the balance between these activities, thereby influencing not only spindle length and stability but also the speed of spindle formation with vital consequences for chromosome alignment and segregation. PMID:26134678

  4. Titan's atomic nitrogen torus - Inferred properties and consequences for the Saturnian aurora

    NASA Astrophysics Data System (ADS)

    Barbosa, D. D.

    1987-10-01

    This paper follows up the lead suggested by Barbosa and Eviatar (1986) that Titanogenic nitrogen ions are a key component of the magnetospheric particle populations and can account for the energetics of the Saturnian aurora without undue assumptions. Nitrogen atoms resulting from electron impact dissociations of N2 (Strobel and Shemansky 1982) escape from Titan and form a large doughnut-shaped ring around the satellite's orbit that is cospatial with the McDonough-Brice (1973) hydrogen cloud. Processes attendant to the ionization and pickup of nitrogen ions include the production of a warm kiloelectronvolt electron population and the excitation of the UV aurora by particle precipitation from the outer magnetosphere.

  5. A lossless compression algorithm for aurora spectral data using online regression prediction

    NASA Astrophysics Data System (ADS)

    Kong, Wanqiu; Wu, Jiaji

    2015-10-01

    Lossless compression algorithms are available for preservation of aurora images. Handling with aurora image compression, linear prediction based method has outstanding compression performance. However, this performance is limited by prediction order and time complexity of linear prediction is relatively high. This paper describes how to solve the conflict between high prediction order and low compression bit rate with an online linear regression with RLS (OLRRLS) algorithm. Experiment results show that OLR-RLS achieves average 7%~11.8% improvement in compression gain and 2.8x speed up in computation time over linear prediction.

  6. BOOK REVIEW: Electron acceleration in the aurora and beyond

    NASA Astrophysics Data System (ADS)

    McClements, K. G.

    1999-08-01

    Duncan Bryant is a retired space plasma physicist who spent most of his career at the Rutherford-Appleton Laboratory in Oxfordshire, England. For many years he has been challenging a widely accepted theory, that auroral electrons are accelerated by double layers, on the grounds that it contains a fundamental error (allegedly, an implicit assumption that charged particles can gain energy from conservative fields). It is, of course, right that models of particle acceleration in natural plasmas should be scrutinized carefully in terms of their consistency with basic physical principles, and I believe that Dr Bryant has performed a valuable service by highlighting this issue. He maintains that auroral electron acceleration by double layers is fundamentally untenable, and that acceleration takes place instead via resonant interactions with lower hybrid waves. In successive chapters, he asserts that essentially the same process can account for electron acceleration observed at the Earth's bow shock, in the neighbourhood of an `artificial comet' produced as part of the Active Magnetospheric Particle Explorers (AMPTE) space mission in 1984/85, in the solar wind, at the Earth's magnetopause, and in the Earth's magneto- sphere. The evidence for this is not always convincing: waves with frequencies of the order of the lower hybrid resonance are often observed in these plasma environments, but in general it is difficult to identify clearly which wave mode is being observed (whistlers, for example, have frequencies in approximately the same range as lower hybrid waves). Moreover, it is not at all clear that the waves which are observed, even if they were of the appropriate type, would have sufficient intensity to accelerate electrons to the extent observed. The author makes a persuasive case, however, that acceleration in the aurora, and in other plasma environments accessible to in situ measurements, involves some form of wave turbulence. In Chapter 2 it is pointed out that

  7. Inhibition of Aurora Kinase B Is Important for Biologic Activity of the Dual Inhibitors of BCR-ABL and Aurora Kinases R763/AS703569 and PHA-739358 in BCR-ABL Transformed Cells

    PubMed Central

    Illert, Anna L.; Seitz, Anna K.; Rummelt, Christoph; Kreutmair, Stefanie; Engh, Richard A.; Goodstal, Samantha; Peschel, Christian; Duyster, Justus; von Bubnoff, Nikolas

    2014-01-01

    ABL tyrosine kinase inhibitors (TKI) like Imatinib, Dasatinib and Nilotinib are the gold standard in conventional treatment of CML. However, the emergence of resistance remains a major problem. Alternative therapeutic strategies of ABL TKI-resistant CML are urgently needed. We asked whether dual inhibition of BCR-ABL and Aurora kinases A-C could overcome resistance mediated by ABL kinase mutations. We therefore tested the dual ABL and Aurora kinase inhibitors PHA-739358 and R763/AS703569 in Ba/F3- cells ectopically expressing wild type (wt) or TKI-resistant BCR-ABL mutants. We show that both compounds exhibited strong anti-proliferative and pro-apoptotic activity in ABL TKI resistant cell lines including cells expressing the strongly resistant T315I mutation. Cell cycle analysis indicated polyploidisation, a consequence of continued cell cycle progression in the absence of cell division by Aurora kinase inhibition. Experiments using drug resistant variants of Aurora B indicated that PHA-739358 acts on both, BCR-ABL and Aurora Kinase B, whereas Aurora kinase B inhibition might be sufficient for the anti-proliferative activity observed with R763/AS703569. Taken together, our data demonstrate that dual ABL and Aurora kinase inhibition might be used to overcome ABL TKI resistant CML. PMID:25426931

  8. Depletion of Aurora A leads to upregulation of FoxO1 to induce cell cycle arrest in hepatocellular carcinoma cells

    PubMed Central

    Lee, Sun-Young; Lee, Gong Rak; Woo, Dong-Hyuk; Park, Neung Hwa; Cha, Hee Jeong; Moon, Yong-Hwan; Han, In-Seob

    2013-01-01

    Aurora A kinase has drawn considerable attention as a therapeutic target for cancer therapy. However, the underlying molecular and cellular mechanisms of the anticancer effects of Aurora A kinase inhibition are still not fully understood. Herein, we show that depletion of Aurora A kinase by RNA interference (RNAi) in hepatocellular carcinoma (HCC) cells upregulated FoxO1 in a p53-dependent manner, which induces cell cycle arrest. Introduction of an RNAi-resistant Aurora A kinase into Aurora A-knockdown cells resulted in downregulation of FoxO1 expression and rescued proliferation. In addition, silencing of FoxO1 in Aurora A-knockdown cells allowed the cells to exit cytostatic arrest, which, in turn, led to massive cell death. Our results suggest that FoxO1 is responsible for growth arrest at the G2/M phase that is induced by Aurora A kinase inhibition. PMID:23255113

  9. Preliminary Results from a Coordinated Hisaki/Chandra/XMM-Newton Study of the Jovian Aurora and Io Plasma Torus

    NASA Technical Reports Server (NTRS)

    Kraft, Ralph; Kimura, Tomoki; Elsner, Ronald; Branduardi-Raymont, Graziella; Gladstone, Randy; Badman, Sarah Victoria; Ezoe, Yuichiro; Murakami, Go; Murray, Stephen S.; Roediger, Elke; Tsuchiya, Fuminori; Yamazaki, Atsushi; Yoshikawa, Ichiro; Yoshioka, Kazuo

    2014-01-01

    We present preliminary results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus. The data were taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument for roughly 12 hours per observation, and twice by XMM-Newton. The goal of this observational campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  10. Identification of Myb-binding protein 1A (MYBBP1A) as a novel substrate for aurora B kinase.

    PubMed

    Perrera, Claudia; Colombo, Riccardo; Valsasina, Barbara; Carpinelli, Patrizia; Troiani, Sonia; Modugno, Michele; Gianellini, Laura; Cappella, Paolo; Isacchi, Antonella; Moll, Jurgen; Rusconi, Luisa

    2010-04-16

    Aurora kinases are mitotic enzymes involved in centrosome maturation and separation, spindle assembly and stability, and chromosome condensation, segregation, and cytokinesis and represent well known targets for cancer therapy because their deregulation has been linked to tumorigenesis. The availability of suitable markers is of crucial importance to investigate the functions of Auroras and monitor kinase inhibition in in vivo models and in clinical trials. Extending the knowledge on Aurora substrates could help to better understand their biology and could be a source for clinical biomarkers. Using biochemical, mass spectrometric, and cellular approaches, we identified MYBBP1A as a novel Aurora B substrate and serine 1303 as the major phosphorylation site. MYBBP1A is phosphorylated in nocodazole-arrested cells and is dephosphorylated upon Aurora B silencing or by treatment with Danusertib, a small molecule inhibitor of Aurora kinases. Furthermore, we show that MYBBP1A depletion by RNA interference causes mitotic progression delay and spindle assembly defects. MYBBP1A has until now been described as a nucleolar protein, mainly involved in transcriptional regulation. The results presented herein show MYBBP1A as a novel Aurora B kinase substrate and reveal a not yet recognized link of this nucleolar protein to mitosis. PMID:20177074

  11. Preliminary Results from a Coordinated Hisaki/Chandra/XMM-Newton Study of the Jovian Aurora and Io Plasma Torus

    NASA Astrophysics Data System (ADS)

    Kraft, R.; Kimura, T.; Elsner, R.; Branduardi-Raymont, G.; Gladstone, R.; Badman, S. V.; Ezoe, Y.; Murakami, G.; Murray, S. S.; Roediger, E.; Tsuchiya, F.; Yamazaki, A.; Yoshikawa, I.; Yoshioka, K.

    2014-12-01

    We present preliminary results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus. The data were taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument for roughly 12 hours per observation, and twice by XMM-Newton. The goal of this observational campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  12. Discrete and diffuse aurora observed from Scotland: the Merry Dancers and the Northern Dawn

    NASA Astrophysics Data System (ADS)

    Simmons, D. A. R.

    1999-12-01

    Two types of aurora are frequently observed from Scotland, the one discrete and the other diffuse. The discrete aurora is a highly active event popularly known as the Merry Dancers. It is a short-lived, rayed arc with a sharp lower border and is usually associated with intense magnetic activity. These features indicate that it is generated by boundary plasma sheet electrons. It is a discrete arc that has migrated south with the discrete auroral oval in response to increased magnetic activity. In contrast, the diffuse aurora is a quiet event popularly known as the Northern Dawn. It is a long-lived, homogeneous arc with a diffuse lower border and is usually associated with weak magnetic activity. These features indicate that it is generated by central plasma sheet electrons. It is an arc of diffuse-continuous aurora that has migrated south with the diffuse oval in response to north/south changes in the interplanetary magnetic field. Thus the Merry Dancers stem from the discrete auroral oval and the Northern Dawn from the diffuse auroral oval.

  13. Allosteric inhibition of Aurora-A kinase by a synthetic vNAR domain.

    PubMed

    Burgess, Selena G; Oleksy, Arkadiusz; Cavazza, Tommaso; Richards, Mark W; Vernos, Isabelle; Matthews, David; Bayliss, Richard

    2016-07-01

    The vast majority of clinically approved protein kinase inhibitors target the ATP-binding pocket directly. Consequently, many inhibitors have broad selectivity profiles and most have significant off-target effects. Allosteric inhibitors are generally more selective, but are difficult to identify because allosteric binding sites are often unknown or poorly characterized. Aurora-A is activated through binding of TPX2 to an allosteric site on the kinase catalytic domain, and this knowledge could be exploited to generate an inhibitor. Here, we generated an allosteric inhibitor of Aurora-A kinase based on a synthetic, vNAR single domain scaffold, vNAR-D01. Biochemical studies and a crystal structure of the Aurora-A/vNAR-D01 complex show that the vNAR domain overlaps with the TPX2 binding site. In contrast with the binding of TPX2, which stabilizes an active conformation of the kinase, binding of the vNAR domain stabilizes an inactive conformation, in which the αC-helix is distorted, the canonical Lys-Glu salt bridge is broken and the regulatory (R-) spine is disrupted by an additional hydrophobic side chain from the activation loop. These studies illustrate how single domain antibodies can be used to characterize the regulatory mechanisms of kinases and provide a rational basis for structure-guided design of allosteric Aurora-A kinase inhibitors. PMID:27411893

  14. Allosteric inhibition of Aurora-A kinase by a synthetic vNAR domain

    PubMed Central

    Burgess, Selena G.; Oleksy, Arkadiusz; Cavazza, Tommaso; Richards, Mark W.; Vernos, Isabelle; Matthews, David

    2016-01-01

    The vast majority of clinically approved protein kinase inhibitors target the ATP-binding pocket directly. Consequently, many inhibitors have broad selectivity profiles and most have significant off-target effects. Allosteric inhibitors are generally more selective, but are difficult to identify because allosteric binding sites are often unknown or poorly characterized. Aurora-A is activated through binding of TPX2 to an allosteric site on the kinase catalytic domain, and this knowledge could be exploited to generate an inhibitor. Here, we generated an allosteric inhibitor of Aurora-A kinase based on a synthetic, vNAR single domain scaffold, vNAR-D01. Biochemical studies and a crystal structure of the Aurora-A/vNAR-D01 complex show that the vNAR domain overlaps with the TPX2 binding site. In contrast with the binding of TPX2, which stabilizes an active conformation of the kinase, binding of the vNAR domain stabilizes an inactive conformation, in which the αC-helix is distorted, the canonical Lys-Glu salt bridge is broken and the regulatory (R-) spine is disrupted by an additional hydrophobic side chain from the activation loop. These studies illustrate how single domain antibodies can be used to characterize the regulatory mechanisms of kinases and provide a rational basis for structure-guided design of allosteric Aurora-A kinase inhibitors. PMID:27411893

  15. Development of ortho-Chlorophenyl Substituted Pyrimidines as Exceptionally Potent Aurora Kinase Inhibitors

    PubMed Central

    Lawrence, Harshani R.; Ozcan, Sevil; Zhu, Jin-Yi; Kendig, Robert; Rodriguez, Mercedes; Elias, Roy; Cheng, Jin Q.; Sebti, Saïd M.; Schonbrunn, Ernst; Lawrence, Nicholas J.

    2015-01-01

    The ortho-carboxylic acid substituted bisanilinopyrimidine 1 was identified as a potent hit (Aurora A IC50 = 6.1 ± 1.0 nM) from in-house screening. Detailed structure activity relationship (SAR) studies indicated that polar substituents at the para position of the B-ring are critical for potent activity. X-ray crystallography studies revealed that compound 1 is a type-I inhibitor that binds the Aurora kinase active site in a DFG-in conformation. Structure activity guided replacement of the A-ring carboxylic acid with halogens and incorporation of fluorine at the pyrimidine 5-position led to highly potent inhibitors of Aurora A that bind in a DFG-out conformation. B-ring modifications were undertaken to improve the solubility and cell permeability. Compounds such as 9m with water-solubilizing moieties at the para-position of the B-ring inhibited the autophosphorylation of Aurora A in MDA-MB-468 breast cancer cells. PMID:22803810

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

    PubMed

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

    2016-08-01

    Accurate spindle positioning is essential for error-free cell division. The one-cell Caenorhabditis elegans embryo has proven instrumental for dissecting mechanisms governing spindle positioning. Despite important progress, how the cortical forces that act on astral microtubules to properly position the spindle are modulated is incompletely understood. Here, we report that the PP6 phosphatase PPH-6 and its associated subunit SAPS-1, which positively regulate pulling forces acting on spindle poles, associate with the Aurora A kinase AIR-1 in C. elegans embryos. We show that acute inactivation of AIR-1 during mitosis results in excess pulling forces on astral microtubules. Furthermore, we uncover that AIR-1 acts downstream of PPH-6-SAPS-1 in modulating spindle positioning, and that PPH-6-SAPS-1 negatively regulates AIR-1 localization at the cell cortex. Moreover, we show that Aurora A and the PP6 phosphatase subunit PPP6C are also necessary for spindle positioning in human cells. There, Aurora A is needed for the cortical localization of NuMA and dynein during mitosis. Overall, our work demonstrates that Aurora A kinases and PP6 phosphatases have an ancient function in modulating spindle positioning, thus contributing to faithful cell division. PMID:27335426

  17. Control of Jupiter's Radio Emission and Aurorae by the Solar Wind

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.; Hospodarsky, G. B.; Persoon, A. M.; Zarka, P.; Lecacheux, A.; Bolton, S. J.; Desch, . D.; Farrell, W. W.; Kaiser, M. L.

    2002-01-01

    Radio emissions from Jupiter provided the first evidence that this giant planet has a strong magnetic field and a large magnetosphere. Jupiter also has polar aurorae, which are similar in many respects to Earth's aurorae. The radio emissions are believed to be generated along the high-latitude magnetic field lines by the same electrons that produce the aurorae, and both the radio emission in the hectometric frequency range and the aurorae vary considerably. The origin of the variability, however, has been poorly understood. Here we report simultaneous observations using the Cassini and Galileo spacecraft of hectometric radio emissions and extreme ultraviolet auroral emissions from Jupiter. Our results show that both of these emissions are triggered by interplanetary shocks propagating outward from the Sun. When such a shock arrives at Jupiter, it seems to cause a major compression and reconfiguration of the magnetosphere, which produces strong electric fields and therefore electron acceleration along the auroral field lines, similar to the processes that occur during geomagnetic storms at the Earth.

  18. Undulations on the equatorward edge of the diffuse proton aurora: TIMED/GUVI observations

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Paxton, L. J.; Morrison, D.; Lui, A. T. Y.; Kil, H.; Wolven, B.; Meng, C.-I.; Christensen, A. B.

    2005-08-01

    Undulations on the equatorward edge of the diffuse proton aurora have been identified by using TIMED/GUVI auroral images in the far ultraviolet wavelengths. While undulations have been previously reported on the duskside (Lui et al., 1982), GUVI observations show the undulation also occurs in the dayside, nightside, and morningside. The GUVI proton auroral images provide direct optical evidence that the undulations occur in the proton aurora. It is also the first detection of the undulation in the dayside indicating strong convection shear in the region. The undulation in the nightside, a wavy structure in the whole diffuse proton aurora, is significantly different from those in the duskside and dayside. While almost all of the undulation events are observed during magnetic storms (Dst < -60 nT), one exceptional case shows undulation in the dayside with Dst = 30 nT. However, the case is associated with a large solar wind speed (650 km/s) and a high dynamic pressure (14 nPa). Coincident DMSP SSIES observations suggest that both large ion drift velocity (>1000 m/s) and strong velocity shear (>0.1 s-1) within the diffuse aurora oval are necessary conditions for the undulation to occur. The SSIES data also indicate the areas with large ion drift velocity and shear move to higher latitudes in the MLT sectors toward midnight. This may explain why the undulation is rarely detected in the nightside.

  19. Aurora A orchestrates entosis by regulating a dynamic MCAK–TIP150 interaction

    PubMed Central

    Xia, Peng; Zhou, Jinhua; Song, Xiaoyu; Wu, Bing; Liu, Xing; Li, Di; Zhang, Shuyuan; Wang, Zhikai; Yu, Huijuan; Ward, Tarsha; Zhang, Jiancun; Li, Yinmei; Wang, Xiaoning; Chen, Yong; Guo, Zhen; Yao, Xuebiao

    2014-01-01

    Entosis, a cell-in-cell process, has been implicated in the formation of aneuploidy associated with an aberrant cell division control. Microtubule plus-end-tracking protein TIP150 facilitates the loading of MCAK onto the microtubule plus ends and orchestrates microtubule plus-end dynamics during cell division. Here we show that TIP150 cooperates with MCAK to govern entosis via a regulatory circuitry that involves Aurora A-mediated phosphorylation of MCAK. Our biochemical analyses show that MCAK forms an intra-molecular association, which is essential for TIP150 binding. Interestingly, Aurora A-mediated phosphorylation of MCAK modulates its intra-molecular association, which perturbs the MCAK–TIP150 interaction in vitro and inhibits entosis in vivo. To probe if MCAK–TIP150 interaction regulates microtubule plasticity to affect the mechanical properties of cells during entosis, we used an optical trap to measure the mechanical rigidity of live MCF7 cells. We find that the MCAK cooperates with TIP150 to promote microtubule dynamics and modulate the mechanical rigidity of the cells during entosis. Our results show that a dynamic interaction of MCAK–TIP150 orchestrated by Aurora A-mediated phosphorylation governs entosis via regulating microtubule plus-end dynamics and cell rigidity. These data reveal a previously unknown mechanism of Aurora A regulation in the control of microtubule plasticity during cell-in-cell processes. PMID:24847103

  20. Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence.

    PubMed

    Hallinan, G; Littlefair, S P; Cotter, G; Bourke, S; Harding, L K; Pineda, J S; Butler, R P; Golden, A; Basri, G; Doyle, J G; Kao, M M; Berdyugina, S V; Kuznetsov, A; Rupen, M P; Antonova, A

    2015-07-30

    Aurorae are detected from all the magnetized planets in our Solar System, including Earth. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower atmospheres, these aurorae are powered by processes originating much further out in the magnetosphere of the dwarf star that couple energy into the lower atmosphere. The dissipated power is at least four orders of magnitude larger than what is produced in the Jovian magnetosphere, revealing aurorae to be a potentially ubiquitous signature of large-scale magnetospheres that can scale to luminosities far greater than those observed in our Solar System. These magnetospheric current systems may also play a part in powering some of the weather phenomena reported on brown dwarfs. PMID:26223623

  1. Acetylation of Aurora B by TIP60 ensures accurate chromosomal segregation.

    PubMed

    Mo, Fei; Zhuang, Xiaoxuan; Liu, Xing; Yao, Phil Y; Qin, Bo; Su, Zeqi; Zang, Jianye; Wang, Zhiyong; Zhang, Jiancun; Dou, Zhen; Tian, Changlin; Teng, Maikun; Niu, Liwen; Hill, Donald L; Fang, Guowei; Ding, Xia; Fu, Chuanhai; Yao, Xuebiao

    2016-04-01

    Faithful segregation of chromosomes in mammalian cells requires bi-orientation of sister chromatids, which relies on the sensing of correct attachments between spindle microtubules and kinetochores. Although the mechanisms underlying cyclin-dependent kinase 1 (CDK1) activation, which triggers mitotic entry, have been extensively studied, the regulatory mechanisms that couple CDK1-cyclin B activity to chromosome stability are not well understood. Here, we identified a signaling axis in which Aurora B activity is modulated by CDK1-cyclin B via the acetyltransferase TIP60 in human cell division. CDK1-cyclin B phosphorylates Ser90 of TIP60, which elicits TIP60-dependent acetylation of Aurora B and promotes accurate chromosome segregation in mitosis. Mechanistically, TIP60 acetylation of Aurora B at Lys215 protects Aurora B's activation loop from dephosphorylation by the phosphatase PP2A to ensure a robust, error-free metaphase-anaphase transition. These findings delineate a conserved signaling cascade that integrates protein phosphorylation and acetylation with cell cycle progression for maintenance of genomic stability. PMID:26829474

  2. Drosophila Aurora A regulates mitotic timing in cancer stem cells: Possible therapeutic implications.

    PubMed

    Caous, Renaud; Richard-Parpaillon, Laurent; Giet, Régis

    2016-05-01

    Loss of Aurora A in Drosophila neuroblasts promotes loss of cell fate, leading to brain tumors. We showed that these tumor stem cells are delayed during mitosis and efficiently segregate their chromosomes even without the spindle assembly checkpoint. Here, we discuss the possible relevance of our results to human cancers. PMID:27314090

  3. Bistability of a coupled Aurora B kinase-phosphatase system in cell division

    PubMed Central

    Zaytsev, Anatoly V; Segura-Peña, Dario; Godzi, Maxim; Calderon, Abram; Ballister, Edward R; Stamatov, Rumen; Mayo, Alyssa M; Peterson, Laura; Black, Ben E; Ataullakhanov, Fazly I; Lampson, Michael A; Grishchuk, Ekaterina L

    2016-01-01

    Aurora B kinase, a key regulator of cell division, localizes to specific cellular locations, but the regulatory mechanisms responsible for phosphorylation of substrates located remotely from kinase enrichment sites are unclear. Here, we provide evidence that this activity at a distance depends on both sites of high kinase concentration and the bistability of a coupled kinase-phosphatase system. We reconstitute this bistable behavior and hysteresis using purified components to reveal co-existence of distinct high and low Aurora B activity states, sustained by a two-component kinase autoactivation mechanism. Furthermore, we demonstrate these non-linear regimes in live cells using a FRET-based phosphorylation sensor, and provide a mechanistic theoretical model for spatial regulation of Aurora B phosphorylation. We propose that bistability of an Aurora B-phosphatase system underlies formation of spatial phosphorylation patterns, which are generated and spread from sites of kinase autoactivation, thereby regulating cell division. DOI: http://dx.doi.org/10.7554/eLife.10644.001 PMID:26765564

  4. 76 FR 65216 - Beacon Medical Services, LLC, Aurora, CO; Notice of Negative Determination Regarding Application...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... (76 FR 40401). The workers of Beacon Medical Services are engaged in activities related ] to the... Employment and Training Administration Beacon Medical Services, LLC, Aurora, CO; Notice of Negative... apply for Trade Adjustment Assistance (TAA) applicable to workers and former workers of Beacon...

  5. Tension Sensing by Aurora B Kinase is Independent of Survivin-Based Centromere Localization

    PubMed Central

    Campbell, Christopher S.; Desai, Arshad

    2013-01-01

    Accurate segregation of the replicated genome requires chromosome biorientation on the spindle. Biorientation is ensured by Aurora B kinase, a member of the 4-subunit chromosomal passenger complex (CPC)1,2. Localization of the CPC to the inner centromere is central to the current model for how tension ensures chromosome biorientation—kinetochore-spindle attachments not under tension remain close to the inner centromere and are destabilized by Aurora B phosphorylation, whereas kinetochores under tension are pulled away from the influence of Aurora B, stabilizing their microtubule attachments3–5. Here we show that an engineered truncation of the INCENP/Sli15 subunit of budding yeast CPC that eliminates association with the inner centromere nevertheless supports proper chromosome segregation during both mitosis and meiosis. Truncated INCENP/Sli15 suppresses the deletion phenotypes of the inner centromere-targeting proteins Survivin/Bir1, Borealin/Nbl1, Bub1 and Sgo16. Unlike wildtype INCENP/Sli15, truncated INCENP/Sli15 localizes to pre-anaphase spindle microtubules. Premature targeting of full-length INCENP/Sli15 to microtubules by preventing Cdk1 phosphorylation also suppresses inviability of Survivin/Bir1 deletion. These results suggest that activation of Aurora B/Ipl1 by clustering either on chromatin or on microtubules is sufficient for chromosome biorientation. PMID:23604256

  6. Driver of quasi-periodic modulation of pulsating aurora: Role of cold electron flux and electric field

    NASA Astrophysics Data System (ADS)

    Sato, N.; Kadokura, A.; Tanaka, Y.; Nishiyama, T.

    2013-12-01

    Pulsating auroras are common phenomena, which are observed universally during the recovery phase of substorm in the auroral and subauroral zones. But, even today, generation mechanism of fundamental characteristics of pulsating aurora, such as, their periodicity and shapes are still open to discussion. Simultaneous observations onboard satellites and on the ground are important method to examine such fundamental characteristics of pulsating aurora. In this study we examined some selected pulsating auroral events, which obtained onboard THEMIS spacecraft and the THEMIS ground-based all-sky camera network. THEMIS satellites were located in the post midnight sector near the equatorial plane in the magnetosphere. We found following signatures of particle, field and wave in the magnetosphere at the onset and during pulsating aurora; 1) All pulsating aurora associate with high-energy(>5 keV) electron flux enhancement, 2) There is no evidence to identify a quasi-periodic(QP) modulation of high-energy electron flux, which may be directly corresponding to pulsating aurora observed on the ground, 3) QP modulation of cold electron flux(<10 eV) and electric field often show one-to-one correspondence to QP modulation of ELF wave intensity, both type of electromagnetic lower-band chorus wave and electrostatic ECH(electron cyclotron harmonic) wave, which may be closely relating to visible pulsating aurora observed on the ground, 4) Not all pulsating aurora associate with ELF wave enhancement, 5) Pitch angle distribution of QP modulated cold electrons show field-aligned to ambient magnetic field. In this study we focus on the characteristics of QP modulation of cold electron flux and electric field, which may play the driver of quasi-periodic modulation of pulsating aurora.

  7. Non-centrosomal TPX2-Dependent Regulation of the Aurora A Kinase: Functional Implications for Healthy and Pathological Cell Division

    PubMed Central

    Garrido, Georgina; Vernos, Isabelle

    2016-01-01

    Aurora A has been extensively characterized as a centrosomal kinase with essential functions during cell division including centrosome maturation and separation and spindle assembly. However, Aurora A localization is not restricted to the centrosomes and compelling evidence support the existence of specific mechanisms of activation and functions for non-centrosomal Aurora A in the dividing cell. It has been now well established that spindle assembly involves an acentrosomal RanGTP-dependent pathway that triggers microtubule assembly and organization in the proximity of the chromosomes whether centrosomes are present or not. The mechanism involves the regulation of a number of NLS-containing proteins, generically called SAFS (Spindle Assembly Factors) that exert their functions upon release from karyopherins by RanGTP. One of them, the nuclear protein TPX2 interacts with and activates Aurora A upon release from importins by RanGTP. This basic mechanism triggers the activation of Aurora A in the proximity of the chromosomes potentially translating the RanGTP signaling gradient centered on the chromosome into an Aurora A phosphorylation network. Here, we will review our current knowledge on the RanGTP-dependent TPX2 activation of Aurora A away from centrosomes: from the mechanism of activation and its functional consequences on the kinase stability and regulation to its roles in spindle assembly and cell division. We will then focus on the substrates of the TPX2-activated Aurora A having a role in microtubule nucleation, stabilization, and organization. Finally, we will briefly discuss the implications of the use of Aurora A inhibitors in anti-tumor therapies in the light of its functional interaction with TPX2. PMID:27148480

  8. Geological, geochemical, and operational summary, aurora well, OCS Y-0943-1, Beaufort Sea, Alaska. Final report

    SciTech Connect

    Paul, L.E.; Choromanski, D.R.; Turner, R.F.; Flett, T.O.; Paul, L.E.

    1994-01-01

    The Aurora well is located just off the coast of the Arctic National Wildlife Refuge (ANWR). The well was spudded November 2, 1987, in 68 ft of water and plugged and abandoned 286 days later on August 30, 1988, after drilling to a total depth (TD) of 18,325 ft below the Kelly Bushing (RKB). The report presents our interpretations of the geologic and geochemical information collected from the Aurora well. Additionally, a significant section of the report is devoted to the operational aspects of drilling the Aurora well.

  9. Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations

    SciTech Connect

    Miyoshi, Y.; Oyama, S.; Saito, S.; Kurita, S.; Fujiwara, H.; Kataoka, R.; Ebihara, Y.; Kletzing, C.; Reeves, G.; Santolik, O.; Clilverd, M.; Rodger, C. J.; Turunen, E.; Tsuchiya, F.

    2015-04-21

    Pulsating auroras show quasi-periodic intensity modulations caused by the precipitation of energetic electrons of the order of tens of keV. It is expected theoretically that not only these electrons but also subrelativistic/relativistic electrons precipitate simultaneously into the ionosphere owing to whistler mode wave-particle interactions. The height-resolved electron density profile was observed with the European Incoherent Scatter (EISCAT) Tromsø VHF radar on 17 November 2012. Electron density enhancements were clearly identified at altitudes >68 km in association with the pulsating aurora, suggesting precipitation of electrons with a broadband energy range from ~10 keV up to at least 200 keV. The riometer and network of subionospheric radio wave observations also showed the energetic electron precipitations during this period. During this period, the footprint of the Van Allen Probe-A satellite was very close to Tromsø and the satellite observed rising tone emissions of the lower band chorus (LBC) waves near the equatorial plane. Considering the observed LBC waves and electrons, we conducted a computer simulation of the wave-particle interactions. This showed simultaneous precipitation of electrons at both tens of keV and a few hundred keV, which is consistent with the energy spectrum estimated by the inversion method using the EISCAT observations. This result revealed that electrons with a wide energy range simultaneously precipitate into the ionosphere in association with the pulsating aurora, providing the evidence that pulsating auroras are caused by whistler chorus waves. We suggest that scattering by propagating whistler simultaneously causes both the precipitations of subrelativistic electrons and the pulsating aurora.

  10. Significance of AZD1152 as a potential treatment against Aurora B overexpression in acute promyelocytic leukemia.

    PubMed

    Ghanizadeh-Vesali, Samad; Zekri, Ali; Zaker, Farhad; Zaghal, Azam; Yousefi, Meysam; Alimoghaddam, Kamran; Ghavamzadeh, Ardeshir; Ghaffari, Seyed H

    2016-06-01

    Aurora B kinase as a chromosomal passenger protein plays multiple roles in regulating mitosis and cytokinesis. The function of Aurora B in leukemic cells has made it an important treatment target. In this study, we explored the expressions of Aurora (A, B, and C) kinases in newly diagnosed acute promyelocytic leukemia (APL) patients. In addition, we investigated the effects of AZD1152 as a specific inhibitor of Aurora B on cell survival, DNA synthesis, nuclear morphology, apoptosis induction, cell cycle distribution, and gene expression in an APL-derived NB4 cell line. Our results showed that Aurora B was overexpressed in 88 % of APL patients. AZD1152 treatment of NB4 cells led to viability reduction and G2/M arrest followed by an increase in cell size and polyploidy induction. These giant cells showed morphological evidence of mitotic catastrophe. AZD1152 treatment induced activation of G2/M checkpoint which in turn led to transient G2/M arrest in a p21-independent manner. Lack of functional p53 in NB4 cells might provide an opportunity to escape from G2/M block and to endure repeated rounds of replication and polyploidy. Treated cells were probably eliminated via p73-mediated overexpression of BAX, PUMA, and APAF1 and downregulation of survivin and MCL-1. In summary, AZD1152 treatment led to endomitosis and polyploidy in TP53-mutated NB4 cells. These giant polyploid cells might undergo mitotic catastrophe and p73-mediated apoptosis. It seems that induction of polyploidy via AZD1152 could be a novel form of anti-cancer therapy for APL that may be clinically accessible in the near future. PMID:27091351

  11. Transport-theoretic model for the electron-proton-hydrogen atom aurora. I. Theory

    SciTech Connect

    Basu, B.; Jasperse, J.R; Strickland, D.J.

    1993-12-01

    The first self-consistent transport-theoretic model for the combined electron-proton-hydrogen atom aurora is presented. This is needed for accurate modeling of the diffuse aurora, particularly in the midnight sector, for which a statistical study indicates that the proton contribution to the total auroral energy flux is (on the average) about 20 to 25% of that of the electrons. As a result, the ionization yield as well as the yields of many emission features will be underestimated (on the average) by about the same percentage if the proton-hydrogen atom contributions are neglected. The model presented here can also be used to study a pure electron aurora or a pure proton-hydrogen atom aurora by choosing the appropriate boundary conditions, namely, by setting the incident flux of one or the other particle population equal to zero. In the latter case, the new feature of the present model is the rigorous transport-theoretic treatment of the contributions to ionization rates and to emission rates and yields from the secondary electrons produced by protons and hydrogen atoms. A coupled set of three linear transport equations is presented. Protons and hydrogen atoms are coupled only to each other through charge-changing (charge exchange and stripping) collisions, while the electrons are coupled to both protons and hydrogen atoms through the secondary electrons that they produce. Source functions for the secondary electrons produced by the three primary particle populations are compared and contrasted, and the numerical methods for solving the coupled transport equations are described. Finally, formulas for calculating pertinent aurora-related quantities from the particle fluxes are given. 66 refs., 9 figs., 2 tabs.

  12. Conjugate Observations of Optical Aurora with POLAR Satellite and Ground Based Imagers in Antarctica

    NASA Technical Reports Server (NTRS)

    Mende, S. H.; Frey, H.; Vo, H.; Geller, S. P.; Doolittle, J. H.; Spann, J. F., Jr.

    1998-01-01

    Operation of the ultraviolet imager on the POLAR satellite permits the observation of Aurora Borealis in daylight during northern summer. With optical imagers in the Automatic Geophysical Observatories (AGO-s) large regions of the oval of Aurora Australis can be observed simultaneously during the southern winter polar night. This opportunity permits conducting a systematic study of the properties of auroras on opposite ends of the same field line. It is expected that simultaneously observed conjugate auroras occurring on closed field lines should be similar to each other in appearance because of the close connection between the two hemispheres through particle scattering and mirroring processes. On open or greatly distorted field lines there is no a priori expectation of similarity between conjugate auroras. To investigate the influence of different IMF conditions on auroral behavior we have examined conjugate data for periods of southward IMF. Sudden brightening and subsequent poleward expansions are observed to occur simultaneously in both hemispheres. The POLAR data show that sudden brightening are initiated at various local time regions. When the local time of this region is in the field of view of the AGO station network then corresponding brightening is also found to occur in the southern hemisphere. Large features such as substorm induced westward propagation and resulting auroral brightening seem to occur simultaneously on conjugate hemispheres. The widely different view scales make it difficult to make unique identification of individual auroral forms in the POLAR and in the ground based data but in a general sense the data is consistent with conjugate behavior.

  13. Energetic electron precipitation associated with pulsating aurora: EISCAT and Van Allen Probe observations

    DOE PAGESBeta

    Miyoshi, Y.; Oyama, S.; Saito, S.; Kurita, S.; Fujiwara, H.; Kataoka, R.; Ebihara, Y.; Kletzing, C.; Reeves, G.; Santolik, O.; et al

    2015-04-21

    Pulsating auroras show quasi-periodic intensity modulations caused by the precipitation of energetic electrons of the order of tens of keV. It is expected theoretically that not only these electrons but also subrelativistic/relativistic electrons precipitate simultaneously into the ionosphere owing to whistler mode wave-particle interactions. The height-resolved electron density profile was observed with the European Incoherent Scatter (EISCAT) Tromsø VHF radar on 17 November 2012. Electron density enhancements were clearly identified at altitudes >68 km in association with the pulsating aurora, suggesting precipitation of electrons with a broadband energy range from ~10 keV up to at least 200 keV. The riometermore » and network of subionospheric radio wave observations also showed the energetic electron precipitations during this period. During this period, the footprint of the Van Allen Probe-A satellite was very close to Tromsø and the satellite observed rising tone emissions of the lower band chorus (LBC) waves near the equatorial plane. Considering the observed LBC waves and electrons, we conducted a computer simulation of the wave-particle interactions. This showed simultaneous precipitation of electrons at both tens of keV and a few hundred keV, which is consistent with the energy spectrum estimated by the inversion method using the EISCAT observations. This result revealed that electrons with a wide energy range simultaneously precipitate into the ionosphere in association with the pulsating aurora, providing the evidence that pulsating auroras are caused by whistler chorus waves. We suggest that scattering by propagating whistler simultaneously causes both the precipitations of subrelativistic electrons and the pulsating aurora.« less

  14. Ewing sarcoma EWS protein regulates midzone formation by recruiting Aurora B kinase to the midzone.

    PubMed

    Park, Hyewon; Turkalo, Timothy K; Nelson, Kayla; Folmsbee, Stephen Sai; Robb, Caroline; Roper, Brittany; Azuma, Mizuki

    2014-01-01

    Ewing sarcoma is a malignant bone cancer that primarily occurs in children and adolescents. Eighty-five percent of Ewing sarcoma is characterized by the presence of the aberrant chimeric EWS/FLI1 fusion gene. Previously, we demonstrated that an interaction between EWS/FLI1 and wild-type EWS led to the inhibition of EWS activity and mitotic dysfunction. Although defective mitosis is considered to be a critical step in cancer initiation, it is unknown how interference with EWS contributes to Ewing sarcoma formation. Here, we demonstrate that EWS/FLI1- and EWS-knockdown cells display a high incidence of defects in the midzone, a midline structure located between segregating chromatids during anaphase. Defects in the midzone can lead to the failure of cytokinesis and can result in the induction of aneuploidy. The similarity among the phenotypes of EWS/FLI1- and EWS siRNA-transfected HeLa cells points to the inhibition of EWS as the key mechanism for the induction of midzone defects. Supporting this observation, the ectopic expression of EWS rescues the high incidence of midzone defects observed in Ewing sarcoma A673 cells. We discovered that EWS interacts with Aurora B kinase, and that EWS is also required for recruiting Aurora B to the midzone. A domain analysis revealed that the R565 in the RGG3 domain of EWS is essential for both Aurora B interaction and the recruitment of Aurora B to the midzone. Here, we propose that the impairment of EWS-dependent midzone formation via the recruitment of Aurora B is a potential mechanism of Ewing sarcoma development. PMID:25483190

  15. Characteristics of GPS Scintillation signals in the midst of "Patchy Pulsating" Aurora and Auroral Arcs

    NASA Astrophysics Data System (ADS)

    Mushini, S. C.; Spanswick, E.; Donovan, E.; Jayachandran, P. T.; Langley, R. B.; Prikryl, P.; Jackel, B. J.; Skone, S.

    2015-12-01

    Aurora occurs in different well-known morphologies, or types, including the best-known arcs and patchy-pulsating aurora (PPA). Previous observational studies have demonstrated that the ionospheric effects of auroral precipitation affect the accuracy of Global Navigation Satellite Systems (GNSS), including GPS, but how different types of aurora might affect GNSS differently has not been investigated to date. In an attempt to explore the relationship between auroral type and the resulting effects on GNSS, we have used data from a THEMIS (Time History of Events and Macroscale Interactions during Substorms) All-Sky Imager (ASI) located at Sanikiluaq (~67º geomagnetic latitude), Canada. GPS data was also obtained from a Canadian High Arctic Ionospheric Network (CHAIN) GPS receiver collocated with the THEMIS ASI. This GPS receiver is a custom-made GPS scintillation receiver capable of providing high-rate GPS signal power and phase and as well as scintillation data. A list of patchy pulsating aurora and auroral arc events were catalogued from the ASI data for the years 2008-2013. Corresponding scintillation data for these time periods were obtained from the GPS receiver. In order to determine the effects of PPA and arcs on GPS signals, the number of cycle slips observed during each were calculated. Results suggests PPA affects GPS in a more adverse manner than auroral arcs given its spatial extent. Even though the magnitude of phase scintillation index (σφ) observed in auroral arcs was much higher than in PPA, receiver was able to keep lock on to the signals much better during arcs compared to patchy aurora. Spectral characteristics of GPS scintillation signals during these events were also studied using wavelet derived "spatialograms" obtained from wavelet "scalograms". These studies seems to suggest that for PPA, large sized ionospheric irregularities (around 2 Km) dominate their spectral content compared to auroral arcs, where there is also contribution from smaller

  16. Simultaneous conjugate observations of small-scale structures in Saturn's dayside ultraviolet auroras: Implications for physical origins

    NASA Astrophysics Data System (ADS)

    Meredith, C. J.; Cowley, S. W. H.; Hansen, K. C.; Nichols, J. D.; Yeoman, T. K.

    2013-09-01

    Conjugacy of Saturn's auroras was studied using unique near-equinox HST images. Dawnside patches are consistent with expectations for second harmonic ULF waves. Dusk transients are strictly non-conjugate, suggesting an open flux tube origin.

  17. Identification of critical chemical features for Aurora kinase-B inhibitors using Hip-Hop, virtual screening and molecular docking

    NASA Astrophysics Data System (ADS)

    Sakkiah, Sugunadevi; Thangapandian, Sundarapandian; John, Shalini; Lee, Keun Woo

    2011-01-01

    This study was performed to find the selective chemical features for Aurora kinase-B inhibitors using the potent methods like Hip-Hop, virtual screening, homology modeling, molecular dynamics and docking. The best hypothesis, Hypo1 was validated toward a wide range of test set containing the selective inhibitors of Aurora kinase-B. Homology modeling and molecular dynamics studies were carried out to perform the molecular docking studies. The best hypothesis Hypo1 was used as a 3D query to screen the chemical databases. The screened molecules from the databases were sorted based on ADME and drug like properties. The selective hit compounds were docked and the hydrogen bond interactions with the critical amino acids present in Aurora kinase-B were compared with the chemical features present in the Hypo1. Finally, we suggest that the chemical features present in the Hypo1 are vital for a molecule to inhibit the Aurora kinase-B activity.

  18. Habitat selection of the channel darter, Percina (Cottogaster) copelandi, a surrogate for the imperiled pearl darter, Percina aurora

    USGS Publications Warehouse

    Schofield, P.J.; Ross, Stephen T.

    2003-01-01

    Percina (Cottogaster) aurora is an imperiled species under consideration for listing by the U.S. Fish and Wildlife Service. To better understand habitat Use of P. aurora, we studied a related and more abundant Cottogaster species, Percina copelandi, from the Ouachita River, Arkansas. We used a laboratory stream system to examine mesohabitat selection (pools versus riffles) and microhabitat selection (substratum particle size) of P. copelandi over three temperature regimes (summer, spring, and winter). Percina copelandi selected pool habitats over riffles and selected pools with coarse substrata (e.g., cobble) over free substrata (e.g., gravel). In riffles, P. copelandi selected large substrata during winter and spring but did not show particle size selection during summer. These data, and various published and unpublished field data for P. aurora, suggest that habitat use of P. aurora is also centered around deep runs and pools, with large substrata likely being more important at low water temperatures.

  19. On the Effect of "Patchy" Aurora and Auroral Arcs on GPS Signals: Initial Investigations

    NASA Astrophysics Data System (ADS)

    Mushini, S. C.; Donovan, E.; Jayachandran, P. T.; Langley, R. B.; Prikryl, P.; Spanswick, E.; Jackel, B. J.

    2014-12-01

    Aurora occurs in different well-known morphologies, or types, including the best-known arcs and patchy-pulsating aurora (PPA). Previous observational studies have demonstrated that the ionospheric effects of auroral precipitation affect the accuracy of global navigation satellite systems, but how different types of aurora might affect GNSS differently has not been investigated to date. In an initial attempt to explore the relationship between auroral type and the resulting effects on GNSS, we have used data from a THEMIS (Time History of Events and Macroscale Interactions during Substorms) All-Sky Imager (ASI) located at Sanikiluaq (~67º geo.mag. lat.), Canada. GPS data was also obtained from a Canadian High Arctic Ionospheric Network (CHAIN) GPS receiver collocated with the THEMIS ASI. This GPS receiver is a commercial GPS scintillation receiver. A list of 140 patchy aurora events and 180 auroral arc events were catalogued from the ASI data for the years 2008-2013. Corresponding scintillation data for these time periods were obtained from the GPS receiver. In order to determine the effects of PPA and arcs on GPS signals, the number of cycle slips observed during each event were calculated. A total number of 197 cycle slips were observed during PPA compared to 16 cycle slips observed during arcs. This result suggests PPA affects GPS in a more adverse manner than auroral arcs. Even though the magnitude of the phase scintillation index (σφ) observed for auroral arcs was much higher than for PPA, the receiver was able to keep lock on to the signals much better during arcs compared to patchy aurora. We have also calculated spectral slopes/spectral index for all events which had σφ > 0.3. We obtained around 1500 spectral slopes for events during auroral arcs and around 600 for events during patchy aurora. Although the histograms for these spectral indices seem to reveal that average spectral index for both of these phenomena was ~3.5, spectral indices for auroral

  20. Aurora Activities Observed by SNPP VIIRS Day-Night Band during St. Patrick's Day, 2015 G4 Level Geomagnetic Storm

    NASA Astrophysics Data System (ADS)

    Liu, T. C.; Shao, X.; Cao, C.; Zhang, B.; Fung, S. F.; Sharma, S.

    2015-12-01

    A G4 level (severe) geomagnetic storm occurred on March 17 (St. Patrick's Day), 2015 and it is among the strongest geomagnetic storms of the current solar cycle (Solar Cycle 24). The storm is identified as due to the Coronal Mass Ejections (CMEs) which erupted on March 15 from Region 2297 of solar surface. During this event, the geomagnetic storm index Dst reached -223 nT and the geomagnetic aurora electrojet (AE) index increased and reached as high as >2200 nT with large amplitude fluctuations. Aurora occurred in both hemispheres. Ground auroral sightings were reported from Michigan to Alaska and as far south as southern Colorado. The Day Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPP represents a major advancement in night time imaging capabilities. The DNB senses radiance that can span 7 orders of magnitude in one panchromatic (0.5-0.9 μm) reflective solar band and provides imagery of clouds and other Earth features over illumination levels ranging from full sunlight to quarter moon. In this paper, DNB observations of aurora activities during the St. Patrick's Day geomagnetic storm are analyzed. Aurora are observed to evolve with salient features by DNB for orbital pass on the night side (~local time 1:30am) in both hemispheres. The radiance data from DNB observation are collected at the night sides of southern and northern hemispheres and geo-located onto geomagnetic local time (MLT) coordinates. Regions of aurora during each orbital pass are identified through image processing by contouring radiance values and excluding regions with stray light near day-night terminator. The evolution of aurora are characterized with time series of the poleward and low latitude boundary of aurora, their latitude-span and area, peak radiance and total light emission of the aurora region in DNB observation. These characteristic parameters are correlated with solar wind and geomagnetic index parameters.

  1. Species boundaries, phylogeography and conservation genetics of the red-legged frog (Rana aurora/draytonii) complex.

    PubMed

    Shaffer, H Bradley; Fellers, G M; Voss, S Randal; Oliver, J C; Pauly, Gregory B

    2004-09-01

    The red-legged frog, Rana aurora, has been recognized as both a single, polytypic species and as two distinct species since its original description 150 years ago. It is currently recognized as one species with two geographically contiguous subspecies, aurora and draytonii; the latter is protected under the US Endangered Species Act. We present the results of a survey of 50 populations of red-legged frogs from across their range plus four outgroup species for variation in a phylogenetically informative, approximately 400 base pairs (bp) fragment of the mitochondrial cytochrome b gene. Our mtDNA analysis points to several major results. (1) In accord with several other lines of independent evidence, aurora and draytonii are each diagnosably distinct, evolutionary lineages; the mtDNA data indicate that they do not constitute a monophyletic group, but rather that aurora and R. cascadae from the Pacific northwest are sister taxa; (2) the range of the draytonii mtDNA clade extends about 100 km further north in coastal California than was previously suspected, and corresponds closely with the range limits or phylogeographical breaks of several codistributed taxa; (3) a narrow zone of overlap exists in southern Mendocino County between aurora and draytonii haplotypes, rather than a broad intergradation zone; and (4) the critically endangered population of draytonii in Riverside County, CA forms a distinct clade with frogs from Baja California, Mexico. The currently available evidence favours recognition of aurora and draytonii as separate species with a narrow zone of overlap in northern California. PMID:15315679

  2. Daurinol Enhances the Efficacy of Radiotherapy in Lung Cancer via Suppression of Aurora Kinase A/B Expression.

    PubMed

    Woo, Jong Kyu; Kang, Ju-Hee; Shin, DongYun; Park, Seong-Hyeok; Kang, Kyungsu; Nho, Chu Won; Seong, Je Kyung; Lee, Sang-Jin; Oh, Seung Hyun

    2015-07-01

    The aurora kinases constitute one family of serine/threonine kinases whose activity is essential for mitotic progression. The aurora kinases are frequently upregulated in human cancers and are associated with sensitivity to chemotherapy in certain ones. In the present study, we investigated whether aurora kinases could be a target to overcome radioresistance or enhance the radiosensitivity of lung cancer. For that purpose, we determined the therapeutic potential of daurinol, an investigational topoisomerase inhibitor, alone and in combination with radiation, by observing its effect on aurora kinases. Daurinol decreased cell viability and proliferation in human colon and lung cancer cells. Gene expression in daurinol-treated human colon cancer cells was evaluated using RNA microarray. The mRNA expression of 18 genes involved in the mitotic spindle check point, including aurora kinase A (AURKA) and aurora kinase B (AURKB), was decreased in daurinol-treated human colon cancer cells as compared with vehicle-treated cells. As expected, radiation increased expression levels of AURKA and AURKB. This increase was effectively attenuated by siRNAs against AURKA and AURKB, which suppressed cell growth and increased apoptosis under radiation. Furthermore, the expression of AURKA and AURKB was suppressed by daurinol in the presence or absence of radiation in colon and lung cancer cells. Daurinol alone or in combination with radiation decreased lung cancer growth in xenograft mouse models. Our data clearly confirm the antitumor and radiosensitizing activity of daurinol in human lung cancer cells through the inhibition of AURKA and AURKB. PMID:25882311

  3. Clks 1, 2 and 4 prevent chromatin breakage by regulating the Aurora B-dependent abscission checkpoint

    PubMed Central

    Petsalaki, Eleni; Zachos, George

    2016-01-01

    When chromatin is trapped at the intercellular bridge, cells delay completion of cytokinesis (abscission) to prevent chromosome breakage. Here we show that inhibition of Cdc-like kinases (Clks) 1, 2 or 4 accelerates midbody resolution in normally segregating cells and correlates with premature abscission, chromatin breakage and generation of DNA damage in cytokinesis with trapped chromatin. Clk1, Clk2 and Clk4 localize to the midbody in an interdependent manner, associate with Aurora B kinase and are required for Aurora B–serine 331 (S331) phosphorylation and complete Aurora B activation in late cytokinesis. Phosphorylated Aurora B–S331 localizes to the midbody centre and is required for phosphorylation and optimal localization of the abscission protein Chmp4c. In addition, expression of phosphomimetic mutants Aurora B–S331E or Chmp4c-S210D delays midbody disassembly and prevents chromatin breakage in Clk-deficient cells. We propose that Clks 1, 2 and 4 impose the abscission checkpoint by phosphorylating Aurora B–S331 at the midbody. PMID:27126587

  4. Aurora inhibitor MLN8237 in combination with docetaxel enhances apoptosis and anti-tumor activity in mantle cell lymphoma.

    PubMed

    Qi, Wenqing; Cooke, Laurence S; Liu, Xiaobing; Rimsza, Lisa; Roe, Denise J; Manziolli, Ann; Persky, Daniel O; Miller, Thomas P; Mahadevan, Daruka

    2011-04-01

    Auroras (A and B) are oncogenic serine/threonine kinases that play key roles in the mitotic phase of the eukaryotic cell cycle. Analysis of the leukemia lymphoma molecular profiling project (LLMPP) database indicates Aurora over-expression correlates with poor prognosis. A tissue microarray (TMA) composed of 20 paired mantle cell lymphoma (MCL) patients demonstrated >75% of patients had high levels Aurora expression. Aurora A and B were also found elevated in 13 aggressive B-NHL cell lines. MLN8237, an Aurora inhibitor induced G2/M arrest with polyploidy and abrogated Aurora A and histone-H3 phosphorylation. MLN8237 inhibited aggressive B-NHL cell proliferation at an IC(50) of 10-50 nM and induced apoptosis in a dose- and time-dependent manner. Low dose combinations of MLN8237+docetaxel enhanced apoptosis by ~3-4-fold in cell culture compared to single agents respectively. A mouse xenograft model of MCL demonstrated that MLN8237 (10 or 30 mg/kg) or docetaxel (10mg/kg) alone had modest anti-tumor activity. However, MLN8237 plus docetaxel demonstrated a statistically significant tumor growth inhibition and enhanced survival compared to single agent therapy. Together, our results suggest that MLN8237 plus docetaxel may represent a novel therapeutic strategy that could be evaluated in early phase trials in relapsed/refractory aggressive B-cell NHL. PMID:21291867

  5. A role for p38 in transcriptional elongation of p21CIP1 in response to Aurora B inhibition

    PubMed Central

    Kumari, Geeta; Ulrich, Tanja; Gaubatz, Stefan

    2013-01-01

    Aurora kinases play important functions in mitosis. They are overexpressed in many cancers and are targets for anticancer therapy. Inhibition of Aurora B results in cytokinesis failure and polyploidization, leading to activation of the p53 tumor suppressor and its target genes, including p21. The pathways that mediate p21 activation after Aurora B inhibition are not well understood. In this study, we identified a role for the p38 MAP kinase in activation of p21 when Aurora B is inhibited. We show that p38 is required for the acute cell cycle arrest in G1 and to prevent endoreduplication when Aurora B is inhibited. Stabilization of p53 occurs independently of p38, and recruitment of p53 to the p21 promoter also does not require p38. Instead, enrichment of the elongating form of RNA PolII at the distal region of the p21 gene is strongly reduced when p38 is blocked, indicating that p38 acts in transcriptional elongation of p21. Thus, our results identify an unexpected role of p38 in cell cycle regulation in response to Aurora B inhibition, by promoting the transcriptional elongation of the cell cycle inhibitor p21. PMID:23759594

  6. Differential regulation of Cdc2 and Aurora-A in Xenopus oocytes: a crucial role of phosphatase 2A.

    PubMed

    Maton, Gilliane; Lorca, Thierry; Girault, Jean-Antoine; Ozon, René; Jessus, Catherine

    2005-06-01

    The success of cell division relies on the activation of its master regulator Cdc2-cyclin B, and many other kinases controlling cellular organization, such as Aurora-A. Most of these kinase activities are regulated by phosphorylation. Despite numerous studies showing that okadaic acid-sensitive phosphatases regulate both Cdc2 and Aurora-A activation, their identity has not yet been established in Xenopus oocytes and the importance of their regulation has not been evaluated. Using an oocyte cell-free system, we demonstrate that PP2A depletion is sufficient to lead to Cdc2 activation, whereas Aurora-A activation depends on Cdc2 activity. The activity level of PP1 does not affect Cdc2 kinase activation promoted by PP2A removal. PP1 inhibition is also not sufficient to lead to Aurora-A activation in the absence of active Cdc2. We therefore conclude that in Xenopus oocytes, PP2A is the key phosphatase that negatively regulates Cdc2 activation. Once this negative regulator is removed, endogenous kinases are able to turn on the activator Cdc2 system without any additional stimulation. In contrast, Aurora-A activation is indirectly controlled by Cdc2 activity independently of either PP2A or PP1. This strongly suggests that in Xenopus oocytes, Aurora-A activation is mainly controlled by the specific stimulation of kinases under the control of Cdc2 and not by downregulation of phosphatase. PMID:15923661

  7. Targeting the interaction of Aurora kinases and SIRT1 mediated by Wnt signaling pathway in colorectal cancer: A critical review.

    PubMed

    Subramaniyan, Boopathi; Jagadeesan, Kaviya; Ramakrishnan, Sabitha; Mathan, Ganeshan

    2016-08-01

    The Aurora kinases belong to the family of serine/threonine kinase, a central regulator of mitosis and their expression increased during G2/M phase. It is classified into Aurora A, B and C, each has distinct roles in cellular processes, which includes regulation of spindle assembly, function of centrosomes, cytoskeleton and cytokinesis. During cancer growth, their rapid increase makes most attractive marker for cancer treatment at present. However Aurora A kinase is known to be a marker for cancer therapy, the most important serine/threonine kinase of Aurora B kinase involvement in cancer is still inadequate. Subsequently, the recent findings revealed that the class III histone deacetylase of SIRT1 is a key regulator to activate Aurora kinases from S phase damaged DNA through Wnt signaling pathway. Even if both Aurora A kinase and SIRT1 serve as a marker for cancer therapy, the present review reveals it is interaction in Wnt signaling pathway that solely for colorectal cancer. PMID:27470380

  8. Long-Term Trends and Gleissberg Cycles in Aurora Borealis Records (1600 - 2015)

    NASA Astrophysics Data System (ADS)

    Vázquez, M.; Vaquero, J. M.; Gallego, M. C.; Roca Cortés, T.; Pallé, P. L.

    2016-02-01

    The long-term spatial and temporal variation of aurora borealis events from 1600 to the present were studied using catalogues and other records of these phenomena. Geographic and geomagnetic coordinates were assigned to approximately 45 000 auroral events with more than 160 000 observations. They were analysed separately for three large-scale areas: i) Europe and North Africa, ii) North America, and iii) Asia. Variations in the cumulative numbers of auroral events with latitude (in both geographic and geomagnetic coordinates) were used to distinguish between the two main solar sources: coronal mass ejections and high-speed streams from coronal holes. We find significant long-term variations in the space-time distribution of auroras. We mainly identify these with four Gleissberg solar activity cycles whose overall characteristics we examine. The Asian observations are crucial in this context, and therefore merit further studies and verifications.

  9. On the Connection Between Solar Activity and Low-Latitude Aurorae in the Period 1715 - 1860

    NASA Astrophysics Data System (ADS)

    Vázquez, M.; Vaquero, J. M.; Curto, J. J.

    2006-11-01

    Observations of aurorae borealis at low latitudes are very rare and are clearly associated with strong geomagnetic storms. Morphologically, they are characterized by a diffuse red colour with no rapid motions. The main aim of this paper is to analyse two hitherto ignored aurorae that were observed at two low-latitude sites, Tenerife (28°N 18°W) and Mexico City (19°N 99°W), in 1770 and 1789, respectively. These observations can give supplementary information about the level of solar activity at those times where direct solar observations were rather scarce. Studying also the behaviour of the heliosphere during this period using different proxies, we find that the open magnetic field better describes auroral occurrences. The variation over time in geomagnetic latitude at the two sites is also calculated.

  10. MI Coupling Processes in the Regions of Diffuse Aurora: Magnetospheric Outlook

    NASA Astrophysics Data System (ADS)

    Khazanov, George V.; Glocer, Alex; Sibeck, David

    2016-04-01

    In this talk we present the solution of the Boltzmann-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora. The calculation includes the affiliated production of secondary electrons and their energy interplay in the magnetosphere and two conjugated ionospheres. This solution starts with the primary injection of plasma sheet electrons via both electron cyclotron harmonic waves and whistler mode chorus waves to the loss cone, and includes their subsequent multiple atmospheric reflections between the two magnetically conjugated ionospheres. It is demonstrated that magnetosphere-ionosphere coupling is the key element in the formation of electron distribution function in the region of diffuse aurora at the magnetospheric altitudes.

  11. Computer control system of the superconducting SR-light source ``Aurora''

    NASA Astrophysics Data System (ADS)

    Yamada, Hironari

    1989-07-01

    The Aurora is a compact SR-light system optimized for x-ray lithography. The system includes a superconducting electron storage ring, a 150-MeV race track microtron as an injector, and light beamlines. The SR-ring features a single magnet body, in which the 650-MeV electron beam orbits a true circular trajectory of 1 m diameter. The computer control system developed for Aurora has a three-level hierarchical architecture. The top level is the Central Intelligence System, and the second an Autonomic Control System (ACS). The bottom is an assembly of distributed local controllers linked to the ACS level through optical fibers. This system provides fully automatic and remote operation, and a powerful machine study capability through the associated man-machine console and the interpretive operation language.

  12. Phosphorylation of EB2 by Aurora B and CDK1 ensures mitotic progression and genome stability

    PubMed Central

    Iimori, Makoto; Watanabe, Sugiko; Kiyonari, Shinichi; Matsuoka, Kazuaki; Sakasai, Ryo; Saeki, Hiroshi; Oki, Eiji; Kitao, Hiroyuki; Maehara, Yoshihiko

    2016-01-01

    Temporal regulation of microtubule dynamics is essential for proper progression of mitosis and control of microtubule plus-end tracking proteins by phosphorylation is an essential component of this regulation. Here we show that Aurora B and CDK1 phosphorylate microtubule end-binding protein 2 (EB2) at multiple sites within the amino terminus and a cluster of serine/threonine residues in the linker connecting the calponin homology and end-binding homology domains. EB2 phosphorylation, which is strictly associated with mitotic entry and progression, reduces the binding affinity of EB2 for microtubules. Expression of non-phosphorylatable EB2 induces stable kinetochore microtubule dynamics and delays formation of bipolar metaphase plates in a microtubule binding-dependent manner, and leads to aneuploidy even in unperturbed mitosis. We propose that Aurora B and CDK1 temporally regulate the binding affinity of EB2 for microtubules, thereby ensuring kinetochore microtubule dynamics, proper mitotic progression and genome stability. PMID:27030108

  13. The effect of the impact of comet Shoemaker Levy-9 on Jupiter's aurorae

    NASA Astrophysics Data System (ADS)

    Miller, S.; Achilleos, N.; Dinelli, B. M.; Lam, H. A.; Tennyson, J.; Jagod, M.-F.; Geballe, T. R.; Trafton, L. M.; Joseph, R. D.; Ballester, G. E.; Baines, K.; Brooke, T. Y.; Orton, G.

    We present infrared spectra and images of the jovian aurorae taken at wavelengths sensitive to the H3+ molecular ion during the period around the impact of Comet Shoemaker Levy-9. The spectra were obtained using CGS4 on the United Kingdom Infrared Telescope and the images using NSFcam on NASA's Infrared Telescope Facility. Comparison with spectra obtained in May, 1993, shows that while the relative intensities of the northern and southern auroral zones prior to and during impact week (July 16-22, 1994) were broadly comparable with those of 1993, a few days after the last collision the northern aurora was considerably enhanced and its southern counterpart somewhat depressed. The north/south auroral ratio was returning to more normal values a week later. The effect of material drifting from the impact sites to the southern auroral zone is discussed in relation to these results.

  14. Computer control system of the superconducting SR-light source ''Aurora''

    SciTech Connect

    Yamada, H.

    1989-07-01

    The Aurora is a compact SR-light system optimized for x-ray lithography. The system includes a superconducting electron storage ring, a 150-MeV race track microtron as an injector, and light beamlines. The SR-ring features a single magnet body, in which the 650-MeV electron beam orbits a true circular trajectory of 1 m diameter. The computer control system developed for Aurora has a three-level hierarchical architecture. The top level is the Central Intelligence System, and the second an Autonomic Control System (ACS). The bottom is an assembly of distributed local controllers linked to the ACS level through optical fibers. This system provides fully automatic and remote operation, and a powerful machine study capability through the associated man--machine console and the interpretive operation language.

  15. Phase-locked coaxial reflex diodes for Aurora and other drivers

    NASA Astrophysics Data System (ADS)

    Phelps, David A.

    1990-04-01

    High power microwave (11PM) experiments with Aurora reflex diodes (ARDs) are analyzed. In particular the multi-wave guide logistics 11PM peak envelope power (PEP) and waveform consistency problems associated with multi-guide radial extraction are reviewed. A novel design involving an outer coaxial cavity to extract power from the ARD cavity via 2535 appropriately placed ports or an equivalently loaded peripheral opening (sideshoot aperture) is described. Tmproved extraction mode selection phase locking frequency stabilization and waveform smoothing via this coaxial ARD (or CARD) is predicted. Staged physics studies and scaling experiments to validate the 11PM operation of a full-scale CARD on a Pocobeam and Aurora are recommended. 1.

  16. Dynamic phosphorylation of Histone Deacetylase 1 by Aurora kinases during mitosis regulates zebrafish embryos development

    PubMed Central

    Loponte, Sara; Segré, Chiara V.; Senese, Silvia; Miccolo, Claudia; Santaguida, Stefano; Deflorian, Gianluca; Citro, Simona; Mattoscio, Domenico; Pisati, Federica; Moser, Mirjam A.; Visintin, Rosella; Seiser, Christian; Chiocca, Susanna

    2016-01-01

    Histone deacetylases (HDACs) catalyze the removal of acetyl molecules from histone and non-histone substrates playing important roles in chromatin remodeling and control of gene expression. Class I HDAC1 is a critical regulator of cell cycle progression, cellular proliferation and differentiation during development; it is also regulated by many post-translational modifications (PTMs). Herein we characterize a new mitosis-specific phosphorylation of HDAC1 driven by Aurora kinases A and B. We show that this phosphorylation affects HDAC1 enzymatic activity and it is critical for the maintenance of a proper proliferative and developmental plan in a complex organism. Notably, we find that Aurora-dependent phosphorylation of HDAC1 regulates histone acetylation by modulating the expression of genes directly involved in the developing zebrafish central nervous system. Our data represent a step towards the comprehension of HDAC1 regulation by its PTM code, with important implications in unravelling its roles both in physiology and pathology. PMID:27458029

  17. The Mars aurora: UV detections and in situ electron flux measurements

    NASA Astrophysics Data System (ADS)

    Gérard, J.-C.; Soret, L.; Lundin, R.; Libert, L.; Stiepen, A.; Radioti, A.; Bertaux, J.-L.; Shematovich, V. I.; Bisikalo, D.

    2015-10-01

    A detailed search through the database of the SPICAM instrument on board Mars Express made it possible to identify 16 signatures of the CO Cameron and CO2+ doublet auroral emissions. These auroral UV signatures are all located in the southern hemisphere in the vicinity of the statistical boundary between open and closed field lines. The energy spectrum of the energetic electrons was simultaneously measured by ASPERA-3/ELS at higher altitude. The UV aurora is generally shifted from the region of enhanced downward electron energy flux by a few to several tens of degrees of latitude, suggesting that precipitation occurs in magnetic cusp like structures along inclined magnetic field lines. The ultraviolet brightness shows no proportionality with the electron flux measured at the spacecraft altitude. The Mars aurora appears as a sporadic short-lived feature. Results of Monte Carlo simulations will be compared with the observed brightness of the Cameron and CO2+ bands.

  18. Time sequence analysis of flickering auroras. I - Application of Fourier analysis. [in atmosphere

    NASA Technical Reports Server (NTRS)

    Berkey, F. T.; Silevitch, M. B.; Parsons, N. R.

    1980-01-01

    Using a technique that enables one to digitize the brightness of auroral displays from individual fields of a video signal, we have analyzed the frequency content of flickering aurora. Through the application of Fourier analysis to our data, we have found that flickering aurora contains a wide range of enhanced frequencies, although the dominant frequency enhancement generally occurs in the range 6-12 Hz. Each incidence of flickering that we observed was associated with increased radio wave absorption. Furthermore, we have found that flickering occurs in bright auroral surges, the occurrence of which is not limited to the 'breakup' phase of auroral substorms. Our results are interpreted in terms of a recently proposed theory of fluctuating double layers that accounts for a number of the observational features.

  19. A general association between discrete auroras and ion precipitation from the tail

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.; Fennell, J. F.; Vampola, A. L.

    1988-01-01

    Observations from the spinning polar-orbiting S3-3 satellite were used to compare the locations of discrete auroral arcs (defined to be regions containing particle distributions consistent with field-aligned potential drops of not less than 0.5 kV) with regions of isotropic ion precipitation. It was found that the regions of discrete aurora are almost exclusively confined to the region of isotropic ion precipitation at all local times studied (polar cap arcs and local times near noon were not considered). It was also found that, throughout the local time interval studied, the discrete aurora was generally associated with spatial structure and boundaries in the precipitating ions, indicating that arc generation may be associated with structure in the particle population within the tail current sheet.

  20. Meridional structures of electric potentials relevant to premidnight discrete auroras: A case study from Akebono measurements

    SciTech Connect

    Yamamoto, Tatsundo; Kaneda, Eisuke; Hayakawa, Hajime

    1993-07-01

    The authors present satellite measurements from Akebono of auroral structures from UV images, from particle measurements, and from electric field measurements made at altitudes near 10000 km over the polar region in a period of geomagnetic activity. The effort is to correlate the auroral data, and in particular what is observed at lower altitudes, with measurements at these altitudes of precipitation properties, and field values, to infer information on the contribution of altitudes above and below the satellite to acceleration processes which produce observed aurorae. The regions of observed discrete aurorae are compared with the regions exhibiting particle precipitation, which are commonly associated with plasma sheet sources, and found to not be in good alignment. Such observations are correlated with field observations to develop an altitude picture of field structures in the disturbed polar ionosphere.

  1. Larval stages of Brachylaima fuscatum in the terrestrial snail Limicolaria aurora from southern Nigeria.

    PubMed

    Awharitoma, A O; Okaka, C E; Obaze, S E

    2003-03-01

    Of 150 specimens of the gastropod snail Limicolaria aurora examined from the Edo and Delta states of Nigeria, 63.4% were infected with larval digeneans comprising mother sporocysts (12.1%) daughter sporocysts (20.4%) cercariae (43.1%) and metacercariae (24.5%). Attempts to experimentally infect three 14-day-old chicks (Gallus domesticus) and two laboratory-bred 4-month-old mice (Mus musculus) by oral feeding and peritoneal injection with cercariae were negative, although experimental infections of chicks via a cloacal drop yielded 62 immature and 37 mature worms from the intestinal caeca and ileum. The worms were identified as Brachylaima fuscatum (Trematoda: Brachylaimidae). The study also revealed that L. aurora acts as an intermediate host for B. fuscatum, in addition to Eulota sp., Helix sp., Helicella sp., Oxychilus sp. and Agrolimax sp. PMID:12590656

  2. Introduction to special section on pulsating aurora and related magnetospheric phenomena

    NASA Astrophysics Data System (ADS)

    Hosokawa, Keisuke; Miyoshi, Yoshizumi; Li, Wen

    2015-07-01

    Pulsating aurora (PsA) is known as one of the major classes of aurora, which almost always appears during the recovery phase of substorm. Since 1960s, PsA has been extensively studied by using ground-based observations combined with rocket and satellite measurements. Still, however, the underlying processes creating auroral pulsations remain to be understood. Because of these, vast numbers of ground-based optical and radio instruments have been employed during the last decade to better observe the dynamic nature of PsA. In addition, there are several ongoing and planned ground-based and satellite collaborations aimed at understanding the electromagnetic coupling between magnetospheric processes (whistler mode chorus and ECH waves) and PsA seen on the ground. This special section focuses on observational (ground-based/satellites), theoretical, and modeling aspects of PsA and related phenomena in the magnetosphere.

  3. Dynamic phosphorylation of Histone Deacetylase 1 by Aurora kinases during mitosis regulates zebrafish embryos development.

    PubMed

    Loponte, Sara; Segré, Chiara V; Senese, Silvia; Miccolo, Claudia; Santaguida, Stefano; Deflorian, Gianluca; Citro, Simona; Mattoscio, Domenico; Pisati, Federica; Moser, Mirjam A; Visintin, Rosella; Seiser, Christian; Chiocca, Susanna

    2016-01-01

    Histone deacetylases (HDACs) catalyze the removal of acetyl molecules from histone and non-histone substrates playing important roles in chromatin remodeling and control of gene expression. Class I HDAC1 is a critical regulator of cell cycle progression, cellular proliferation and differentiation during development; it is also regulated by many post-translational modifications (PTMs). Herein we characterize a new mitosis-specific phosphorylation of HDAC1 driven by Aurora kinases A and B. We show that this phosphorylation affects HDAC1 enzymatic activity and it is critical for the maintenance of a proper proliferative and developmental plan in a complex organism. Notably, we find that Aurora-dependent phosphorylation of HDAC1 regulates histone acetylation by modulating the expression of genes directly involved in the developing zebrafish central nervous system. Our data represent a step towards the comprehension of HDAC1 regulation by its PTM code, with important implications in unravelling its roles both in physiology and pathology. PMID:27458029

  4. Pilot Study of Aurora, a Social, Mobile-Phone-Based Emotion Sharing and Recording System

    PubMed Central

    Gay, Geri; Pollak, JP; Adams, Phil; Leonard, John P

    2011-01-01

    Background: Emotion is a ubiquitous aspect of humanity that governs behavior in a number of ways and is linked inextricably with health. Pausing to evaluate one’s emotional state in the face of decisions and reflecting on past patterns of emotion have been shown to improve behaviors. Further, social expression of emotion has been shown to directly improve health outcomes. While the virtual reality research community does not ignore emotion on the whole, there does exist a need to explore what roles emotional awareness and emotion sharing can play in this domain. Methods: A mobile-phone-based social emotion recording and sharing system, Aurora, was developed to provide individuals with a means to pause and evaluate their emotional state, reflect on past emotions, share emotions with others, and participate in socially supportive activities with peers. A study was conducted with 65 subjects to evaluate Aurora as a tool to encourage emotional reflection and awareness as well as social sharing of emotion. Results: Users of Aurora reported an increased comfort in socially expressing emotion and were encouraged to share emotions, even with strangers. Subjects also reported liking reflecting on their emotional state and found it valuable. Subjects’ behavior also suggested that the system encouraged individuals to reach out to one another in acts of social support. Conclusions: The Aurora system offers a tool for encouraging emotional awareness, emotion sharing, and socially supportive behavior. Such a tool could be impactful in numerous health settings where emotion is considered to be an important indicator of or influence on outcome, such as for weight loss, alcohol cessation, or cancer sufferers. PMID:21527101

  5. Ground-based Optical Observations of Geophysical Phenomena: Aurora Borealis and Meteors

    NASA Astrophysics Data System (ADS)

    Samara, Marilia

    2010-10-01

    Advances in low-light level imaging technology have enabled significant improvements in the ground based study of geophysical phenomena. In this talk we focus on two such phenomena that occur in the Earth's ionosphere: aurorae and meteors. Imaging the aurora which is created by the interplay of the Earth's magnetosphere, ionosphere and atmosphere, provides a tool for remote sensing physical processes that are otherwise very difficult to study. By quantifying the intensities, scale sizes and lifetimes of auroral structures, we can gain significant insight into the physics behind the generation of the aurora and the interaction of the magnetosphere with the solar wind. Additionally, the combination of imaging with radars provides complimentary data and therefore more information than either method on its own. Meteor observations are a perfect example of this because the radar can accurately determine only the line-of-sight component of velocity, while imaging provides the direction of motion, the perpendicular velocity and brightness (a proxy for mass), therefore enabling a much more accurate determination of the full velocity vector and mass.

  6. Aurora at quiet magnetospheric conditions: Repeatability and dipole tilt angle dependence. (Reannouncement with new availability information)

    SciTech Connect

    Oznovich, I.; Eastes, R.W.; Huffman, R.E.; Tur, M.; Glaser, I.

    1993-03-01

    Is there a magnetospheric ground state? Do the position and size of the auroral oval depend on the magnetic dipole tilt angle at quiet magnetospheric conditions? In order to address these questions, northern hemisphere images of the aurora at 1356 A, obtained by Polar BEAR at solar minimum (beginning of 1987), were related to high temporal resolution IMP 8 measurements of the interplanetary magnetic field, to solar wind velocity, and to the ground-based activity index Kp. The first problem was addressed by a two-dimensional correlation study of the repeatability of auroral emissions in corrected geomagnetic space at conditions of minimum energy transfer from the magnetosphere. The correlation measure of auroral images was 0.6--0.85. Error simulations indicate that given the uncertainties in pixel position and intensity, the maximum expected value of the correlation measure is 0.65-0.9. The notion of a ground state magnetosphere is therefore supported by this data. Repeatability was found at the same level regardless of time or reconfigurations of the magnetosphere between images and independent of magnetic time sector. The second problem was addressed by relating latitudinal shifts of the aurora with dipole tilt angle without resorting to auroral boundary specification. The authors data indicate that the latitude of the continuous aurora is related to the dipole tilt angle at quiet magnetospheric conditions. In the winter hemisphere a 10 deg increase in the dipole tilt angle causes a 1 deg decrease (increase) in the latitude of auroral emissions at noon (midnight).

  7. Pulsating aurora observed on the ground and in-situ by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Lessard, M.; Cohen, I. J.; Denton, R. E.; Engebretson, M. J.; Kletzing, C.; Wygant, J. R.; Bounds, S. R.; Smith, C. W.; MacDowall, R. J.; Kurth, W. S.

    2013-12-01

    Early observations and theory related to pulsating aurora suggested that the electrons that drive this aurora originate from the equatorial region of the magnetosphere and that a likely process that can scatter these electrons would involve chorus waves. Recent satellite observations during pulsating auroral events have provided important "firsts", including evidence of strong correlations between pulsating auroral patches and in-situ lower-band chorus (THEMIS), as well as correlations with energetic electron precipitation in the vicinity of geosynchronous orbit (GOES). These results provide important information regarding particle dynamics, leading to a question about how the chorus might be driven. We present observations of the Van Allen Probes in conjunction with a pulsating aurora event, as confirmed by observations on the ground. The in-situ data again show the presence of lower-band chorus. However, magnetic and electric field data also show that the wave bursts coincide with an apparent poloidal field-line resonance, begging the question of whether the resonance might be responsible for driving the VLF waves.

  8. Acetylation of Aurora B by TIP60 ensures accurate chromosomal segregation

    PubMed Central

    Mo, Fei; Zhuang, Xiaoxuan; Liu, Xing; Yao, Phil Y.; Qin, Bo; Su, Zeqi; Zang, Jianye; Wang, Zhiyong; Zhang, Jiancun; Dou, Zhen; Tian, Changlin; Teng, Maikun; Niu, Liwen; Hill, Donald L.; Fang, Guowei; Ding, Xia; Fu, Chuanhai; Yao, Xuebiao

    2015-01-01

    Faithful chromosome segregation in mammalian cells requires the bi-orientation of sister chromatids which relies on sensing correct attachments between spindle microtubules and kinetochores. Although the mechanisms underlying cyclin-dependent kinase 1 (CDK1) activation that triggers mitotic entry is extensively studied, the regulatory mechanisms that couple CDK1-cyclin B activity to chromosome stability are not well understood. Here, we identified a signaling axis in which Aurora B activity is modulated by CDK1-cyclin B via acetyltransferase TIP60 (Tat-interactive protein 60 kDa) in human cell division. CDK1-cyclin B phosphorylated Ser90 of TIP60, which elicited TIP60-dependent acetylation of Aurora B and promoted accurate chromosome segregation in mitosis. Mechanistically, TIP60 acetylation of Aurora B at Lys215 protected the phosphorylation of its activation loop from PP2A reactivation-elicited dephosphorylation to ensure a robust, error-free metaphase-anaphase transition. These findings delineated a conserved signaling cascade that integrates protein phosphorylation and acetylation to cell cycle progression for maintenance of genomic stability. PMID:26829474

  9. Interplanetary magnetic field structure at Saturn inferred from nanodust measurements during the 2013 aurora campaign

    NASA Astrophysics Data System (ADS)

    Hsu, H.-W.; Kempf, S.; Badman, S. V.; Kurth, W. S.; Postberg, F.; Srama, R.

    2016-01-01

    Interactions between the solar wind and planetary magnetospheres provide important diagnostic information about the magnetospheric dynamics. The lack of monitoring of upstream solar wind conditions at the outer planets, however, restrains the overall scientific output. Here we apply a new method, using Cassini nanodust stream measurements, to derive the interplanetary magnetic field structure during the 2013 Saturn aurora campaign. Due to the complex dynamical interactions with the interplanetary magnetic field, a fraction of fast nanodust particles emerging from the Saturnian system is sent back into the magnetosphere and can be detected by a spacecraft located within. The time-dependent directionality caused by the variable interplanetary magnetic field enable these particles to probe the solar wind structure remotely. Information about the arrival time of solar wind compression regions (coupled with the heliospheric current sheet crossings) as well as the field direction associated with the solar wind sector structure can be inferred. Here we present a tentative identification of the interplanetary magnetic field sector structure based on Cassini nanodust and radio emission measurements during the 2013 Saturn aurora campaign. Our results show that, the interplanetary magnetic field near Saturn during 2013-080 to 176 was consistent with a two-sector structure. The intensifications of aurora and the radio emission on 2013-095, 112 and 140 coincide with the IMF sector boundaries, indicating that the encounter of the compressed solar wind is the main cause of the observed activities.

  10. Cross-regulation between Aurora B and Citron kinase controls midbody architecture in cytokinesis

    PubMed Central

    McKenzie, Callum; Bassi, Zuni I.; Debski, Janusz; Gottardo, Marco; Callaini, Giuliano; Dadlez, Michal; D'Avino, Pier Paolo

    2016-01-01

    Cytokinesis culminates in the final separation, or abscission, of the two daughter cells at the end of cell division. Abscission relies on an organelle, the midbody, which forms at the intercellular bridge and is composed of various proteins arranged in a precise stereotypic pattern. The molecular mechanisms controlling midbody organization and function, however, are obscure. Here we show that proper midbody architecture requires cross-regulation between two cell division kinases, Citron kinase (CIT-K) and Aurora B, the kinase component of the chromosomal passenger complex (CPC). CIT-K interacts directly with three CPC components and is required for proper midbody architecture and the orderly arrangement of midbody proteins, including the CPC. In addition, we show that CIT-K promotes Aurora B activity through phosphorylation of the INCENP CPC subunit at the TSS motif. In turn, Aurora B controls CIT-K localization and association with its central spindle partners through phosphorylation of CIT-K's coiled coil domain. Our results identify, for the first time, a cross-regulatory mechanism between two kinases during cytokinesis, which is crucial for establishing the stereotyped organization of midbody proteins. PMID:27009191

  11. Novel Aurora/vascular endothelial growth factor receptor dual kinase inhibitor as treatment for hepatocellular carcinoma.

    PubMed

    Nakao, Keisuke; Tanaka, Shinji; Miura, Tomoya; Sato, Kota; Matsumura, Satoshi; Aihara, Arihiro; Mitsunori, Yusuke; Ban, Daisuke; Ochiai, Takanori; Kudo, Atsushi; Arii, Shigeki; Tanabe, Minoru

    2015-08-01

    We previously identified Aurora B kinase as the only independent factor predictive of the aggressive recurrence of hepatocellular carcinoma (HCC). In this preclinical study, JNJ-28841072, a novel Aurora/vascular endothelial growth factor receptor dual kinase inhibitor, was evaluated for treatment of HCC. In vitro and in vivo effects of JNJ-28841072 were analyzed using human HCC cell cultures and xenograft models. An orthotopic liver xenograft model was used for the pharmacobiological effects on Aurora kinase and vascularization in hepatic tumors. JNJ-28841072 suppressed in vitro phosphorylation of histone H3 with induction of cell polyploidy and death in a dose-dependent manner (IC50  = 0.8-1.2 μM). In s.c. human HCC xenografts, remarkable inhibition of tumor growth was observed after JNJ-28841072 treatment (P = 0.0005). In orthotopic liver xenografts, the treatment with JNJ-28841072 significantly suppressed in vivo phosphorylation of histone H3 (P = 0.0008), vessel formation (P = 0.018), normoxic area (P = 0.0001), and hepatoma growth (P = 0.038). Our preclinical studies indicate that JNJ-28841072 is a promising novel therapeutic approach for the treatment of HCC. It might be worthy of evaluation in further studies. PMID:26011703

  12. Inhibition of the Aurora A kinase augments the anti-tumor efficacy of oncolytic measles virotherapy.

    PubMed

    Iankov, I D; Kurokawa, C B; D'Assoro, A B; Ingle, J N; Domingo-Musibay, E; Allen, C; Crosby, C M; Nair, A A; Liu, M C; Aderca, I; Federspiel, M J; Galanis, E

    2015-09-01

    Oncolytic measles virus (MV) strains have demonstrated broad spectrum preclinical anti-tumor efficacy, including breast cancer. Aurora A kinase controls mitotic spindle formation and has a critical role in malignant transformation. We hypothesized that the Aurora A kinase inhibitor MLN8237 (alisertib) can increase MV oncolytic effect and efficacy by causing mitotic arrest. Alisertib enhanced MV oncolysis in vitro and significantly improved outcome in vivo against breast cancer xenografts. In a disseminated MDA-231-lu-P4 lung metastatic model, the MV/alisertib combination treatment markedly increased median survival to 82.5 days with 20% of the animals being long-term survivors versus 48 days median survival for the control animals. Similarly, in a pleural effusion model of advanced breast cancer, the MV/alisertib combination significantly improved outcome with a 74.5 day median survival versus the single agent groups (57 and 40 days, respectively). Increased viral gene expression and IL-24 upregulation were demonstrated, representing possible mechanisms for the observed increase in anti-tumor effect. Inhibiting Aurora A kinase with alisertib represents a novel approach to enhance MV-mediated oncolysis and antitumor effect. Both oncolytic MV strains and alisertib are currently tested in clinical trials, this study therefore provides the basis for translational applications of this combinatorial strategy in the treatment of patients with advanced breast cancer. PMID:26272026

  13. Concurrent observations of ultraviolet aurora and energetic electron precipitation with Mars Express

    NASA Astrophysics Data System (ADS)

    Gérard, J.-C.; Soret, L.; Libert, L.; Lundin, R.; Stiepen, A.; Radioti, A.; Bertaux, J.-L.

    2015-08-01

    The database of the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument between late January 2004 and Mars 2014 has been searched to identify signatures of CO Cameron and CO2+ doublet ultraviolet auroral emissions. This study has almost doubled the number of auroral detections based on SPICAM spectra. Auroral emissions are located in the vicinity of the statistical boundary between open and closed field lines. From a total of 113 nightside orbits with SPICAM pointing to the nadir in the region of residual magnetic field, only nine nightside orbits show confirmed auroral signatures, some with multiple detections along the orbital track, leading to a total of 16 detections. The mean energy of the electron energy spectra measured during concurrent Analyzer of Space Plasma and Energetic Atoms/Electron Spectrometer observations ranges from 150 to 280 eV. The ultraviolet aurora may be displaced poleward or equatorward of the region of enhanced downward electron energy flux by several tens of seconds and shows no proportionality with the electron flux at the spacecraft altitude. The absence of further UV auroral detection in regions located along crustal magnetic field structures where occasional aurora has been observed indicates that the Mars aurora is a time-dependent feature. These results are consistent with the scenario of acceleration of electrons by transient parallel electric field along semiopen magnetic field lines.

  14. Aurora B prevents chromosome arm separation defects by promoting telomere dispersion and disjunction

    PubMed Central

    Reyes, Céline; Serrurier, Céline; Gauthier, Tiphaine

    2015-01-01

    The segregation of centromeres and telomeres at mitosis is coordinated at multiple levels to prevent the formation of aneuploid cells, a phenotype frequently observed in cancer. Mitotic instability arises from chromosome segregation defects, giving rise to chromatin bridges at anaphase. Most of these defects are corrected before anaphase onset by a mechanism involving Aurora B kinase, a key regulator of mitosis in a wide range of organisms. Here, we describe a new role for Aurora B in telomere dispersion and disjunction during fission yeast mitosis. Telomere dispersion initiates in metaphase, whereas disjunction takes place in anaphase. Dispersion is promoted by the dissociation of Swi6/HP1 and cohesin Rad21 from telomeres, whereas disjunction occurs at anaphase after the phosphorylation of condensin subunit Cnd2. Strikingly, we demonstrate that deletion of Ccq1, a telomeric shelterin component, rescued cell death after Aurora inhibition by promoting the loading of condensin on chromosome arms. Our findings reveal an essential role for telomeres in chromosome arm segregation. PMID:25778919

  15. DE 1 observations of theta aurora plasma source regions and Birkeland current charge carriers

    SciTech Connect

    Menietti, J.D.; Burch, J.L. )

    1987-07-01

    The authors have performed detailed analyses of the DE 1 high-altitude plasma instrument (HAPI) electron and ion data for four passes during which theta auroras were observed. The data indicate that the theta auroras occur on what appear to be closed field lines with particle signatures and plasma parameters that are quite similar to those of the magnetospheric boundary plasma sheet. The field-aligned currents computed from particle fluxes in the energy range 18 eV < E < 13 keV above the theta auroras are observed to be generally downward on the dawnside of the arcs with a narrower region of larger (higher density) upward currents on the duskside of the arcs. These currents are carried predominantly by field-aligned beams of accelerated cold electrons. Of particular interest in regions of upward field-aligned current are downward electron beams at energies less than the inferred potential drop above the spacecraft. These beams may be due to atmospheric secondaries or to ionospheric electrons that have convected into a region of field-aligned electric field.

  16. Aurora A inhibition by MNL8054 promotes centriole elongation during Drosophila male meiosis

    PubMed Central

    Gottardo, Marco; Callaini, Giuliano; Riparbelli, Maria G

    2015-01-01

    Aurora A kinase plays an important role in several aspects of cell division, including centrosome maturation and separation, a crucial step for the correct organization of the bipolar spindle. Although it has long been showed that this kinase accumulates at the centrosome throughout mitosis its precise contribution to centriole biogenesis and structure has until now not been reported. It is not surprising that so little is known, due to the small size of somatic centrioles, where only dramatic structural changes may be identified by careful electron microscopy analysis. Conversely, centrioles of Drosophila primary spermatocytes increase tenfold in length during the first prophase, thus making any change easily detectable. Therefore, we examined the consequence of the pharmacological inhibition of Aurora A by MLN8054 on centriole biogenesis during early Drosophila gametogenesis. Here, we show that depletion of this kinase results in longer centrioles, mainly during transition from prophase to prometaphase of the first meiosis. We also found abnormal ciliogenesis characterized by irregularly growing axonemal doublets. Our results represent the first documentation of a potential requirement of Aurora A in centriole integrity and elongation. PMID:25785740

  17. Strong Solar Control of Infrared Aurora on Jupiter: Correlation Since the Last Solar Maximum

    NASA Technical Reports Server (NTRS)

    Kostiuk, T.; Livengood, T. A.; Hewagama, T.

    2009-01-01

    Polar aurorae in Jupiter's atmosphere radiate throughout the electromagnetic spectrum from X ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based spectroscopic measurements of Jupiter's northern mid-IR aurora, acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane emission brightness and solar 10.7 cm radio flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high solar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the Europa Jupiter System Mission. Results of observations at the Infrared Telescope Facility (IRTF) operated by the University of Hawaii under Cooperative Agreement no. NCC5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. This work was supported by the NASA Planetary Astronomy Program.

  18. A low latitude Auroras catalogue from 1766 to 1797 (Padua, Italy)

    NASA Astrophysics Data System (ADS)

    De La Guía, M. C.; Dominguez-Castro, F.; Vaquero, J. M.; Bertolin, C.; Gallego, M. C.; Camuffo, D.

    2015-12-01

    It is presented a long term catalogue of aurorae from the observations done by Joseph Toaldo between 1766-1797 at La Specola (the Observatory) in Padua (Italy, 45º24'07.5''N, 11º52'06.8''E). Toaldo was interested in astrometeorology and was the prime mover and the first director of the Astronomic Observatory where he carried out valuable daily observations on both fields. He also taught astronomy and meteorology at the University of Padua. The data was collected from different historical document sources including the original manuscripts made by Toaldo which also contain meteorological readings. A total of 148 aurorae events were recovered from Toaldo's manuscripts. The data reliability was validated using time and season, percentage of the moon illuminated and aurorae directionality. The data shows a secular maximum of the auroral activity around 1780 that occurred at planetary scale. From 1789 onwards there is a sharp decrease of this activity marking the onset of the Dalton Minimum although the solar activity decreases less rapidly. It has also been collected geomagnetic declination measurements taken in Padua between 1725-1799. These geomagnetic observations are consistent with the geomagnetic model gufm1.

  19. Aurora B prevents chromosome arm separation defects by promoting telomere dispersion and disjunction.

    PubMed

    Reyes, Céline; Serrurier, Céline; Gauthier, Tiphaine; Gachet, Yannick; Tournier, Sylvie

    2015-03-16

    The segregation of centromeres and telomeres at mitosis is coordinated at multiple levels to prevent the formation of aneuploid cells, a phenotype frequently observed in cancer. Mitotic instability arises from chromosome segregation defects, giving rise to chromatin bridges at anaphase. Most of these defects are corrected before anaphase onset by a mechanism involving Aurora B kinase, a key regulator of mitosis in a wide range of organisms. Here, we describe a new role for Aurora B in telomere dispersion and disjunction during fission yeast mitosis. Telomere dispersion initiates in metaphase, whereas disjunction takes place in anaphase. Dispersion is promoted by the dissociation of Swi6/HP1 and cohesin Rad21 from telomeres, whereas disjunction occurs at anaphase after the phosphorylation of condensin subunit Cnd2. Strikingly, we demonstrate that deletion of Ccq1, a telomeric shelterin component, rescued cell death after Aurora inhibition by promoting the loading of condensin on chromosome arms. Our findings reveal an essential role for telomeres in chromosome arm segregation. PMID:25778919

  20. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

    PubMed

    Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T

    2005-02-17

    The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere. PMID:15716946

  1. Aurora B regulates formin mDia3 in achieving metaphase chromosome alignment.

    PubMed

    Cheng, Lina; Zhang, Jiayin; Ahmad, Sana; Rozier, Lorene; Yu, Haiqian; Deng, Haiteng; Mao, Yinghui

    2011-03-15

    Proper bipolar attachment of sister kinetochores to the mitotic spindle is critical for accurate chromosome segregation in mitosis. Here we show an essential role of the formin mDia3 in achieving metaphase chromosome alignment. This function is independent of mDia3 actin nucleation activity, but is attributable to EB1-binding by mDia3. Furthermore, the microtubule binding FH2 domain of mDia3 is phosphorylated by Aurora B kinase in vitro, and cells expressing the nonphosphorylatable mDia3 mutant cannot position chromosomes at the metaphase plate. Purified recombinant mDia3 phosphorylated by Aurora B exhibits reduced ability to bind microtubules and stabilize microtubules against cold-induced disassembly in vitro. Cells expressing the phosphomimetic mDia3 mutant do not form stable kinetochore microtubule fibers; despite they are able to congress chromosomes to the metaphase plate. These findings reveal a key role for mDia3 and its regulation by Aurora B phosphorylation in achieving proper stable kinetochore microtubule attachment. PMID:21397845

  2. Auroras and Space Weather Celebrating the International Heliophysics Year in Classroom

    NASA Astrophysics Data System (ADS)

    Craig, N.; Peticolas, L. M.; Angelopoulos, V.; Thompson, B.

    2007-05-01

    2007 Celebrates the International Heliophysics year and its outreach has a primary objective, to "demonstrate the beauty, relevance and significance of Space and Earth Science to the world." NASA's first five-satellite mission, THEMIS (Time History of Events and Macroscale Interactions during Substorms), was launched on February 17, 2007 and is to investigate a key mystery surrounding the dynamics of the auroras- when, where, and how are they triggered? When the five probes align perfectly over the North American continent- every four days - and with 20 ground stations in Northern Canada and Alaska with automated, all-sky cameras will document the auroras from Earth. To monitor the large-scale local effects of the currents in space, THEMIS Education and Outreach program has installed 10 ground magnetometers, instruments that measure Earth's magnetic field, in competitively selected rural schools around the country and receive data. The THEMIS Education and Outreach Program shares the IHY objective by bringing in this live local space weather data in the classrooms and engaging the teachers and students on authentic research in the classroom. The data are displayed on the school computer monitors as well as on the THEMIS E/PO website providing the local data to the science mission as well as schools. Teachers use the data to teach about the aurora not only in math and science, but also in Earth science, history and art. These students and their teachers are our ambassadors to rural America and share the excitement of learning and teaching with their regional teachers. We will share how authentic space science data related to Earth's magnetic field and auroras can be understood, researched, predicted and shared via the internet to any school around the globe that wished to be part of tracking solar storms. Complimenting IHY, World Space Week will take place from October 4-10th and this year. World Space week is "an international celebration of science and technology

  3. RNA interference-mediated knockdown of Aurora-B alters the metastatic behavior of A549 cells via modulation of the phosphoinositide 3-kinase/Akt signaling pathway

    PubMed Central

    ZHOU, LONG DIAN; XIONG, XU; LONG, XIN HUA; LIU, ZHI LI; HUANG, SHAN HU; ZHANG, WEI

    2014-01-01

    Accumulating evidence has revealed that an elevated expression level of Aurora-B is associated with metastasis in various types of malignant tumor. However, it is currently unclear whether this molecule is involved in non-small lung cancer (NSCLC) metastasis, and the molecular mechanisms associated with Aurora-B and metastasis remain unknown. In the present study, in order to investigate whether Aurora-B is involved in the development and metastasis of NSCLC, the Aurora-B protein expression in NSCLC tissues was detected by immunohistochemistry and its association with metastasis was analyzed. The results revealed that the expression levels of the Aurora-B protein in tissues obtained from NSCLC patients with lymph node metastasis were significantly higher than those without metastatic disease. Furthermore, the effect of Aurora-B inhibition on A549 cell migration and invasion, as well as the activity of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway was evaluated. Aurora-B was inhibited in the A549 cells using short hairpin RNA, and the cell migration and invasion rates were investigated using wound healing and Transwell invasion assays. In addition, the expression of the main proteins in the PI3K/Akt/nuclear factor-κB (NF-κB) signaling pathway, and matrix metalloproteinase (MMP)-2 and -9 were measured by western blot analysis. The results demonstrated that cell migration and invasion were decreased as a result of silencing Aurora-B. Furthermore, the activity of the PI3K/Akt/NF-κB signaling pathway and the expression of MMP-2 and -9 protein were suppressed by silencing Aurora-B. The results of the present study indicate that the knockdown of Aurora-B suppresses A549 cell invasion and migration via the inhibition of the PI3K/Akt signaling pathway in vitro and thus, targeting Aurora-B may present a potential treatment strategy for NSCLC. PMID:25295091

  4. Stereoscopic determination of all-sky altitude map of aurora using two ground-based Nikon DSLR cameras

    NASA Astrophysics Data System (ADS)

    Kataoka, R.; Miyoshi, Y.; Shigematsu, K.; Hampton, D.; Mori, Y.; Kubo, T.; Yamashita, A.; Tanaka, M.; Takahei, T.; Nakai, T.; Miyahara, H.; Shiokawa, K.

    2013-09-01

    A new stereoscopic measurement technique is developed to obtain an all-sky altitude map of aurora using two ground-based digital single-lens reflex (DSLR) cameras. Two identical full-color all-sky cameras were set with an 8 km separation across the Chatanika area in Alaska (Poker Flat Research Range and Aurora Borealis Lodge) to find localized emission height with the maximum correlation of the apparent patterns in the localized pixels applying a method of the geographical coordinate transform. It is found that a typical ray structure of discrete aurora shows the broad altitude distribution above 100 km, while a typical patchy structure of pulsating aurora shows the narrow altitude distribution of less than 100 km. Because of its portability and low cost of the DSLR camera systems, the new technique may open a unique opportunity not only for scientists but also for night-sky photographers to complementarily attend the aurora science to potentially form a dense observation network.

  5. Records of sunspot and aurora during CE 960-1279 in the Chinese chronicle of the Sòng dynasty

    NASA Astrophysics Data System (ADS)

    Hayakawa, Hisashi; Tamazawa, Harufumi; Kawamura, Akito Davis; Isobe, Hiroaki

    2015-05-01

    Records of sunspot and aurora observations in pre-telescopic historical documents can provide useful information about solar activity in the past. This is also true for extreme space weather events, as they may have been recorded as large sunspots observed by the naked eye or as low-latitude auroras. In this paper, we present the results of a comprehensive survey of records of sunspots and auroras in the Sòngshǐ, a Chinese formal chronicle spanning the tenth to the thirteenth century. This chronicle contains a record of continuous observations with well-formatted reports conducted as a policy of the government. A brief comparison of the frequency of observations of sunspots and auroras and the observations of radioisotopes as an indicator of the solar activity during corresponding periods is provided. This paper is the first step of our project in which we survey and compile the records of sunspots and auroras in historical documents from various locations and languages, ultimately providing it to the science community as online data.

  6. The real-time state of the aurora -- a research to operations need with a citizen science solution?

    NASA Astrophysics Data System (ADS)

    Heavner, M.; MacDonald, E.; Case, N.; McCloat, S.

    2015-12-01

    A prototype citizen science application called Aurorasaurus has been developed and launched in 2014. The goal of this platform is crowdsourcing observations of the aurora in real-time in order to assess global visibility of the aurora for the public. Users can submit observations, verify relevant social media observations, learn about the aurora, and receive location-based alerts based on verified reports, all in near real-time. The size and distribution of the citizen scientist community around the world has tremendous potential both for documenting the visible manifestations of global space weather impacts as well as providing quality control on the reported sightings. Information with high spatial and temporal resolution of the largest, most dynamic and mysterious space weather events is made possible by this solution, and this data can be integrated with other ground and space based measures of auroral activity. We will present initial results during the large geomagnetic events of 2015 and comparison to other measures of auroral activity. Our findings indicate the prototype application can be a valuable tool for real-time aurora knowledge and should be included in discussions of real-time aurora nowcasting needs. We will discuss those needs and assess the feasibility of available systems for meeting them.

  7. Aurora-A recruitment and centrosomal maturation are regulated by a Golgi-activated pool of Src during G2

    PubMed Central

    Barretta, Maria Luisa; Spano, Daniela; D'Ambrosio, Chiara; Cervigni, Romina Ines; Scaloni, Andrea; Corda, Daniela; Colanzi, Antonino

    2016-01-01

    The Golgi apparatus is composed of stacks of cisternae laterally connected by tubules to form a ribbon-like structure. At the onset of mitosis, the Golgi ribbon is broken down into discrete stacks, which then undergo further fragmentation. This ribbon cleavage is required for G2/M transition, which thus indicates that a ‘Golgi mitotic checkpoint' couples Golgi inheritance with cell cycle transition. We previously showed that the Golgi-checkpoint regulates the centrosomal recruitment of the mitotic kinase Aurora-A; however, how the Golgi unlinking regulates this recruitment was unknown. Here we show that, in G2, Aurora-A recruitment is promoted by activated Src at the Golgi. Our data provide evidence that Src and Aurora-A interact upon Golgi ribbon fragmentation; Src phosphorylates Aurora-A at tyrosine 148 and this specific phosphorylation is required for Aurora-A localization at the centrosomes. This process, pivotal for centrosome maturation, is a fundamental prerequisite for proper spindle formation and chromosome segregation. PMID:27242098

  8. Selected personal highlights from experimental space studies of the aurora (Hannes Alfvén Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Marklund, Göran

    2013-04-01

    Aurora is a most spectacular and frequently occurring scenery in the winter polar sky, occurring on Earth and many other planets. To further our understanding of the physics of the aurora, numerous sounding rocket and satellite projects have been carried out since the 1960's. Results are presented for a small selection of these where the author and his research team at KTH were strongly engaged in the research, namely a series of rocket experiments and small satellite missions, and the European Space Agency Cluster multi-satellite mission. The electric field plays a fundamental role in the physics of the magnetosphere and of the aurora, such as for the acceleration of electrons and ions producing bright aurora and outflow of energetic plasma. The results include: An arc classification scheme based on the electric field variation across arcs; A method to derive global distributions of electrodynamical parameters for a given auroral oval distribution; The discovery of intense diverging electric fields and of their characteristics in the auroral downward current region; Using Cluster data to reveal how such diverging electric fields evolve in time and are closely tied to the formation of ionospheric density cavities; Reconstruction of an experimentally verified acceleration potential pattern of the aurora, being stable on a 5 min time scale. Finally, acceleration signatures and electrodynamics of large-scale auroral forms, such as spirals, surges, and polar boundary intensifications are discussed based on recent Cluster and DMSP satellite conjunctions.

  9. A Dual Non-ATP Analogue Inhibitor of Aurora Kinases A and B, Derived from Resorcinol with a Mixed Mode of Inhibition.

    PubMed

    Karthigeyan, Dhanasekaran; Surabhi, Sudhevan; Mizar, Pushpak; Soumik, Siddhanta; Banerjee, Amrita; Sinha, Sarmistha Halder; Dasgupta, Dipak; Narayana, Chandrabhas; Kundu, Tapas K

    2016-06-01

    Aurora kinases are the most commonly targeted mitotic kinases in the intervention of cancer progression. Here, we report a resorcinol derivative, 5-methyl-4-(2-thiazolylazo) resorcinol (PTK66), a dual inhibitor of Aurora A and Aurora B kinases. PTK66 is a surface binding non-ATP analogue inhibitor that shows a mixed pattern of inhibition against both of Aurora A and B kinases. The in vitro IC50 is approximately 47 and 40 μm for Aurora A and Aurora B kinases, respectively. In cellular systems, PTK66 exhibits a substantially low cytotoxicity at micromolar concentrations but it can induce aneuploidy under similar dosages as a consequence of Aurora kinase inhibition. This result was corroborated by a drop in the histone H3 (S10) phosphorylation level detected via Western blot analysis using three different cell types. Altogether, our findings indicate that the ligand containing resorcinol backbone is one of the novel scaffolds targeting the Aurora family of kinases, which could be a target for antineoplastic drug development. PMID:26808391

  10. Sub-relativistic and relativistic electron precipitations above diffuse aurora: Conjugate observations of SAMPEX and the all sky TV camera at Syowa Station

    NASA Astrophysics Data System (ADS)

    Kurita, S.; Kadokura, A.; Miyoshi, Y.; Sato, Y.; Misawa, H.; Morioka, A.

    2014-12-01

    It has been widely accepted that diffuse auroras are generated by electron precipitations in the energy range from a few keV to tens keV. Recent simulation results based on the quasi-linear theory showed that the scattering by whistler-mode waves plays an important role in the production of precipitating electrons responsible for diffuse auroras. A test particle simulation on electron-whistler interactions shows that relativistic electrons can be scattered into the loss cone simultaneously with the electrons in the energy range from a few keV to tens keV. Thus, it is expected that relativistic electrons precipitate into the atmosphere in association with diffuse auroras if whistler-mode waves contribute to generation of diffuse auroras. To examine this hypothesis, we investigated conjugate observations of SAMPEX and the all sky camera at Syowa Station on the dawn side, where diffuse auroras are frequently observed. In this study, we show a case study that relativistic electron (> 1 MeV) precipitations observed by SAMPEX are associated with the diffuse aurora observed at Syowa Station. The SAMPEX observation shows that the enhancement of precipitating relativistic electrons is well correlated with that of precipitating > 150 keV and > 400 keV electrons, indicating that electrons in the energy range from a few keV to > 1 MeV precipitate into the atmosphere simultaneously in association with the diffuse aurora. It is observational evidence that whistler mode waves contribute to generation of diffuse auroras.

  11. Drilling Polar Oceans with the European Research Icebreaker AURORA BOREALIS: the IODP Context

    NASA Astrophysics Data System (ADS)

    Lembke-Jene, Lester; Wolff-Boenisch, Bonnie; Azzolini, Roberto; Thiede, Joern; Biebow, Nicole; Eldholm, Olav; Egerton, Paul

    2010-05-01

    Polar oceans are characterized by extreme environmental conditions for humans and materials, and have remained the least accessible regions to scientists of the IODP. DSDP and ODP have for long faced specific technical and logistical problems when attempting to drill in ice-covered polar deep-sea basins. The Arctic Ocean and large areas of the high-latitude Southern Ocean remained largely un-sampled by ODP and remain one of the major scientific and technological challenges for IODP. Drilling in these regions has been discussed and anticipated for decades and the scientific rationales are reflected in the science plans of the international Nansen Arctic Drilling Program (NAD) or the Arctic Program Planning Group (APPG) of ODP/IODP, amongst others. More recently, the rationale to investigate the polar oceans in a holistic approach has been outlined by workshops, leading to strategic assessments of the scientific potential and new drilling proposals. The European Polar Board took the initiative to develop a plan for a novel and dedicated research icebreaker with technical capabilities hitherto unrealised. This research icebreaker will enable autonomous operations in the central Arctic Ocean and the Southern Ocean, even during the severest ice conditions in the deep winter, serving all marine disciplines of polar research including scientific drilling: The European Research Icebreaker and Deep-Sea Drilling Vessel AURORA BOREALIS. AURORA BOREALIS is presently planned as a multi-purpose vessel. The ship can be deployed as a research icebreaker in all polar waters during any season of the year, as it shall meet the specifications of the highest ice-class attainable (IACS Polar Code 1) for icebreakers. During the times when it is not employed for drilling, it will operate as the most technically advanced multi-disciplinary research vessel in the Arctic or polar Southern Ocean. AURORA BOREALIS will be a "European scientific flagship facility" (fully open to non

  12. Ultraviolet aurora on outer planets: morphology and remote sensing of electron precipitation

    NASA Astrophysics Data System (ADS)

    Gerard, Jean-Claude; Bisikalo, Dmitry; Shematovich, Valery; Soret, Lauriane

    2016-07-01

    The aurora is the result of the interaction between energetic particles and the upper atmosphere of a planet. Generally, energetic particles from the magnetosphere penetrate the atmosphere, partly deposit their energy and are partly reflected. Their collisional interactions with the atmospheric atoms and molecules heat the atmosphere and produce auroral emissions. Consequently, the aurora then bears the signature of both the acceleration mechanism and the atmospheric structure and composition. Jupiter's UV auroral H2 and H emissions are generally divided into several components. The main auroral emission at Jupiter is associated with the giant current loop connecting the region of co-rotation breakdown in the middle magnetosphere with the ionosphere. The polar emissions observed inside the main emission are very variable over short timescales. The observed diffuse emission equatorward of the main emission is most likely related to precipitation resulting from wave-particle interactions. Finally, the satellite magnetic footprints are created by accelerated electrons resulting from the interaction between the Galilean moons and the plasma in the Jovian magnetosphere. Saturn's magnetosphere and its aurorae appear to be both solar wind driven as the terrestrial magnetosphere and rotationally dominated, similarly to Jupiter. In addition to the main auroral ring, transient features have been recently identified. Uranus displays aurorae quite different from the other two with faint small-size structures appearing following solar storm activity. These different processes are probably associated with different energy spectra of the precipitated electrons. We present an overview of recent results concerning the relation between morphology, variability and remote sensing of the auroral electron energy in the different components. We show that mapping the UV color ratio is a powerful tool to globally characterize the electron precipitation and the flux-energy relation

  13. A morphological description and statistical classification of dayside diffuse aurora observed at Yellow River Station in Ny-Ålesund, Svalbard

    NASA Astrophysics Data System (ADS)

    Chen, Xiangcai; Han, Desheng; Hu, Zejun

    2013-04-01

    Ground optical observations are best suited to identify morphological characteristics of the dayside diffuse aurora that usually brightens at the equatorward of the auroral oval. Using 7-winter optical auroral observations, we recognized that the dayside diffuse aurora has a variety of temporal and spatial size scales and forms. Mostly dayside diffuse auroral forms have drawn together in a general classification based on their morphological characteristics and occurrence time. Four primary categories of dayside diffuse aurora are classified: (1) Veiling Diffuse Aurora (VDA), which has no obvious morphological structure and clear boundaries, sometimes like a thick cloud covering the entire sky; (2) Patchy Diffuse Aurora (PDA), which usually occurred accompany by pulsating aurora, mostly in spatial scale of 10-100 km diameter width but occasionally to hundreds kilometer; (3) Diffuse Aurora Arc (DAA), which was obviously different from discrete auroral arcs in morphology; (4) Pulsating Aurora (PA), occurred with sparkling forms. The luminosity of PA commonly showed periodic variation with the oscillating appearance. The occurrence rate of each type shows a parabolic distribution with magnetic local time (MLT), and the occurrence peak is found to be mostly near the cusp region. The duration time of pulsating aurora on cusp region was markedly longer than that on nightside. Dayside diffuse aurora more commonly occurred under quiet geomagnetic condition as measured by the Kp index, which indicates almost 92.2% occurrence at the Kp ≤ 3. To investigate whether the interplanetary magnetic field (IMF) controls dayside diffuse aurora occurrence, we present a general bias comparison of IMF three components. Under the IMF condition of negative By accompanied with positive Bz, it could be expected that the dayside diffuse aurora would be easier to observe. We suggest that a negative IMF By associated field-aligned current (FAC) at the lower latitude region in the Northern

  14. Search for Potent and Selective Aurora A Inhibitors Based on General Ser/Thr Kinase Pharmacophore Model

    PubMed Central

    Vasilevich, Natalya I.; Tatarskiy, Victor V.; Aksenova, Elena A.; Kazyulkin, Denis N.; Afanasyev, Ilya I.

    2016-01-01

    Based on the data for compounds known from the literature to be active against various types of Ser/Thr kinases, a general pharmachophore model for these types of kinases was developed. The search for the molecules fitting to this pharmacophore among the ASINEX proprietary library revealed a number of compounds, which were tested and appeared to possess some activity against Ser/Thr kinases such as Aurora A, Aurora B and Haspin. Our work on the optimization of these molecules against Aurora A kinase allowed us to achieve several hits in a 3–5 nM range of activity with rather good selectivity and Absorption, Distribution, Metabolism, and Excretion (ADME) properties, and cytotoxicity against 16 cancer cell lines. Thus, we showed the possibility to fine-tune the general Ser/Thr pharmacophore to design active and selective compounds against desired types of kinases. PMID:27089349

  15. Search for Potent and Selective Aurora A Inhibitors Based on General Ser/Thr Kinase Pharmacophore Model.

    PubMed

    Vasilevich, Natalya I; Tatarskiy, Victor V; Aksenova, Elena A; Kazyulkin, Denis N; Afanasyev, Ilya I

    2016-01-01

    Based on the data for compounds known from the literature to be active against various types of Ser/Thr kinases, a general pharmachophore model for these types of kinases was developed. The search for the molecules fitting to this pharmacophore among the ASINEX proprietary library revealed a number of compounds, which were tested and appeared to possess some activity against Ser/Thr kinases such as Aurora A, Aurora B and Haspin. Our work on the optimization of these molecules against Aurora A kinase allowed us to achieve several hits in a 3-5 nM range of activity with rather good selectivity and Absorption, Distribution, Metabolism, and Excretion (ADME) properties, and cytotoxicity against 16 cancer cell lines. Thus, we showed the possibility to fine-tune the general Ser/Thr pharmacophore to design active and selective compounds against desired types of kinases. PMID:27089349

  16. Plasma in the Jovian magnetosphere: An X-ray and EUV study of the aurora and the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Kraft, Ralph

    2013-09-01

    We propose 4x40 ks Chandra/HRC-I and 2x40 ks XMM-Newton observations of the Jovian aurora and Io plasma torus in conjunction with the Japanese SPRINT-A satellite. SPRINT-A will continuously observe Jupiter from Dec 2013 to Apr 2014, making sensitive EUV spectroscopic observations of the aurora and IPT. We will correlate variations in the X-ray flux from the aurora and IPT with changes in the EUV flux observed by SPRINT-A and with the properties of the solar wind. We will conclusively resolve the puzzle of the origin of the Jovian X-ray emission and determine if the precipitating particles originate from Io or from the solar wind.

  17. AURORA BOREALIS - Icebreaker, Drilling Platform and Multi-Purpose Research Vessel

    NASA Astrophysics Data System (ADS)

    Kunz-Pirrung, M.; Biebow, N.; Lembke-Jene, L.; Thiede, J.; Egerton, P.

    2007-12-01

    In spite of the critical role of the Arctic Ocean in climate evolution, it is the only sub-basin of the world's oceans that has essentially not been sampled by the drill ships of the Deep-Sea Drilling Project (DSDP) or the Ocean Drilling Program (ODP), and its long-term environmental history and tectonic structure is therefore poorly known. Exceptions are the ODP Leg 151 and the more recent very successful ACEX-expedition of the Integrated Ocean Drilling Program (IODP). This lack of data represents one of the largest gaps of information in modern Earth Science. Therefore, the new research icebreaker AURORA BOREALIS will be equipped with drilling facilities to fulfil the needs of the IODP for a -Mission-Specific Platform- to drill in deep, permanently ice-covered ocean basins. This icebreaker must be also powerful enough to maintain station against the drifting sea-ice cover and will have to be equipped with a dynamic positioning system. This new icebreaker would be conceived as an optimized science platform from the keel up and will allow conducting long, international and interdisciplinary expeditions into the central Arctic Ocean during all seasons of the year. In a long-term perspective the AURORA BOREALIS will also be used to address Antarctic research targets, both in its mode as a regular research vessel as well as a polar drill ship. The construction of AURORA BOREALIS requires several new technical implementations, such as advanced dynamic positioning and deep-sea drilling under a closed sea-ice cover and two moon pools (7 x 7 m), and will provide an extended technical potential and knowledge for marine technology. The scientific and technical details will be presented.

  18. The impact of an ICME on the Jovian X-ray aurora

    NASA Astrophysics Data System (ADS)

    Dunn, William R.; Branduardi-Raymont, Graziella; Elsner, Ronald F.; Vogt, Marissa F.; Lamy, Laurent; Ford, Peter G.; Coates, Andrew J.; Gladstone, G. Randall; Jackman, Caitriona M.; Nichols, Jonathan D.; Rae, I. Jonathan; Varsani, Ali; Kimura, Tomoki; Hansen, Kenneth C.; Jasinski, Jamie M.

    2016-03-01

    We report the first Jupiter X-ray observations planned to coincide with an interplanetary coronal mass ejection (ICME). At the predicted ICME arrival time, we observed a factor of ˜8 enhancement in Jupiter's X-ray aurora. Within 1.5 h of this enhancement, intense bursts of non-Io decametric radio emission occurred. Spatial, spectral, and temporal characteristics also varied between ICME arrival and another X-ray observation two days later. Gladstone et al. (2002) discovered the polar X-ray hot spot and found it pulsed with 45 min quasiperiodicity. During the ICME arrival, the hot spot expanded and exhibited two periods: 26 min periodicity from sulfur ions and 12 min periodicity from a mixture of carbon/sulfur and oxygen ions. After the ICME, the dominant period became 42 min. By comparing Vogt et al. (2011) Jovian mapping models with spectral analysis, we found that during ICME arrival at least two distinct ion populations, from Jupiter's dayside, produced the X-ray aurora. Auroras mapping to magnetospheric field lines between 50 and 70 RJ were dominated by emission from precipitating sulfur ions (S7+,…,14+). Emissions mapping to closed field lines between 70 and 120 RJ and to open field lines were generated by a mixture of precipitating oxygen (O7+,8+) and sulfur/carbon ions, possibly implying some solar wind precipitation. We suggest that the best explanation for the X-ray hot spot is pulsed dayside reconnection perturbing magnetospheric downward currents, as proposed by Bunce et al. (2004). The auroral enhancement has different spectral, spatial, and temporal characteristics to the hot spot. By analyzing these characteristics and coincident radio emissions, we propose that the enhancement is driven directly by the ICME through Jovian magnetosphere compression and/or a large-scale dayside reconnection event.

  19. The aurora at quite magnetospheric conditions: Repeatability and dipole tilt angle dependence

    SciTech Connect

    Oznovich, I. ); Eastes, R.W.; Huffman, R.E. ); Tur, M.; Glaser, I. )

    1993-03-01

    Is there a magnetospheric ground state Do the position and size of the auroral oval depend on the magnetic dipole tilt angle at quiet magnetospheric conditions In order to address these questions, northern hemisphere images of the aurora at 1356 [Angstrom], obtained by Polar BEAR at solar minimum (beginning of 1987), were related to high temporal resolution IPM 8 measurements of the interplanetary magnetic field, to solar wind velocity, and to the ground-based activity index Kp. The first problem was addressed by a two-dimensional correlation study of the repeatability of auroral emissions in corrected geomagnetic space at conditions of minimum energy transfer from the magnetosphere. The correlation measure of auroral images was 0.6-0.85. Error simulations indicate that given the uncertainties in pixel position and intensity, the maximum expected value of the correlation measure is 0.65-0.9. The notion of a ground state magnetosphere is therefore supported by this data. Repeatability was found at the same level regardless of time or reconfigurations of the magnetosphere between images and independent of magnetic time sector. The second problem was addressed by relating latitudinal shifts of the aurora with dipole tilt angle without resorting to auroral boundary specification. This data indicate that the latitude of the continuous aurora is related to the dipole tilt angle at quiet magnetospheric conditions. In the winter hemisphere a 10[degrees] increase in the dipole tilt angle causes a 1[degree] decrease (increase) in the latitude of auroral emissions at noon (midnight). The magnetic local time distribution of the latitudinal shifts with dipole tilt angle support a simple model in which the dipole tilt angle determines the position of the center of the auroral circle along the magnetic meridian 1320-0120 MLT (for IMF B[sub y] positive) and does not affect its radius. 22 refs., 8 figs.

  20. A magnetohydrodynamic simulation study of Kronian field-aligned currents and auroras

    NASA Astrophysics Data System (ADS)

    Fukazawa, Keiichiro; Ogino, Tatsuki; Walker, Raymond J.

    2012-02-01

    Magnetohydrodynamic simulations of the interaction of Saturn's magnetosphere with the solar wind indicate that Kelvin-Helmholtz (K-H) waves can form on the dayside magnetopause when the interplanetary magnetic field (IMF) is northward. Dayside magnetic reconnection occurs at Saturn for northward IMF, and the combination of K-H waves and reconnection caused enhanced vorticity in Saturn's magnetosphere. We have used a very high resolution version (Δx = 0.1 RS) of our simulation code to study the consequences of the vortices and reconnection for the generation of field-aligned currents (FACs) and auroras in Saturn's ionosphere. We found three bands of alternating FACs toward and away from the dawn side of the ionosphere and two sets on the dusk side. The K-H waves generated a series of toward and away currents along the dayside magnetopause. In the ionosphere they appear as a series of spots of up and down currents. The K-H field-aligned currents are adjacent to nearly continuous currents located from 16:00 LT, to around past midnight, and to about 07:00 LT. The largest currents densities (j∥ > 5 × 10-8 A m-2) are found at the highest latitudes. They map to the magnetopause and to the near-Saturn tail region. We used the away current density and the Knight relationship to estimate the energy flux related to discrete auroras and obtained ˜1 mW m-2 in the region with the strongest currents. This gives approximately 7 GW for the auroral UV emitted power. We found a region of enhanced thermal energy flux in the region where cusp auroras are observed.

  1. Wide energy electron precipitations and their impact on the middle atmosphere associated with the pulsating aurora

    NASA Astrophysics Data System (ADS)

    Miyoshi, Y.; Oyama, S. I.; Saito, S.; Turunen, E. S.; Kurita, S.; Kero, A.; Verronen, P. T.; Kataoka, R.; Ebihara, Y.; Kletzing, C.; Reeves, G. D.; Santolik, O.; Clilverd, M. A.; Rodger, C. J.; Tsuchiya, F.

    2015-12-01

    The pulsating aurora is caused by intermittent precipitations of tens keV electrons. It is also expected that not only tens keV electrons but also sub-relativistic/relativistic electrons precipitate simultaneously into the polar ionosphere owing to whistler-mode wave-particle interactions. We analyzed a pulsating aurora event in November 2012 using several ground-based observation data from EISCAT radar, riometer, sub-ionospheric radio wave receivers, and the Van Allen Probes satellite. The electron density profile obtained from EISCA Tromsø VHF radar identifies electron density enhancements at >68 km altitudes. The electron energy spectrum derived from the Markov Chain Monte Carlo (MCMC) method indicates the wide energy electron precipitations from 10 - 200 keV, suggesting precipitation of the population from the outer belt. The riometer and network of sub-ionospheric radio wave observations also show energetic electron precipitations coinciding with the electron density enhancements at 68 km altitude. During this period, footprint of the Van Allen Probe-A satellite was very close to Tromsø, and the satellite observed rising tone emissions of the lower-band chorus (LBC) waves near the equatorial plane. Using the satellite-observed LBC and trapped electrons as an initial condition, we conducted a computer simulation of the wave-particle interactions. The simulation showed simultaneous precipitation of electrons at both tens of keV and a few hundred keV. This result is consistent with the energy spectrum estimated with the MCMC method. This result revealed that electrons with a wide energy range from the plasma sheet to the outer belt simultaneously precipitate into the polar ionosphere in association with the pulsating aurora. Using the Sodankylä Ion Chemistry (SIC) model that is a detailed coupled neutral and ion chemistry model of the upper atmosphere, we also discuss the possible impacts on the middle atmosphere due to precipitations of wide energy electrons.

  2. Simultaneous measurement of aurora-related, irregular magnetic pulsations at northern and southern high latitudes

    SciTech Connect

    Arnoldy, R.L.; Rajashekar, R. ); Cahill, L.J. Jr. ); Engebretson, M.J. ); Rosenberg, T.J. ); Mende, S.B. )

    1987-11-01

    A dominant feature of high-latitude magnetic pulsations is large-amplitude irregular pulsations (Pi) which are closely correlated with the movement of the observing station under particle precipitation, producing the dayside auroral and the high-latitude expansion of nightside aurora. The dayside Pi-1 pulsation maximum centered about local magnetic noon has no strong seasonal dependence, indicating that the dayside aurora illuminates both hemispheres independent of the latitude of the subsolar point. The summer noon pulsation maximum has, however, a greater longitudinal extent than the winter noon maximum, as measured at 74{degree}-75{degree} invariant latitude. The nightside magnetic pulsations are bursts of Pi (PiB) having an average duration of 15 min. From Defense Meteorological Satellite Program photos the auroral forms related to the high-latitude PiB can be identified as the poleward discrete arc generally having a large longitudinal extent. If the auroral forms are very similar in both hemispheres, then the large longitudinal extent coupled with movement of the auroral could explain why 85% of the PiB events have onsets within 10 min at opposite hemisphere sites (South Pole, Antarctica, and Sondre Stromfjord, Greenland) separated in local magnetic time by about 1.5 hours. There is no seasonal dependence in the statistical occurrence of PiB, nor in its simultaneity in opposite hemispheres. Apparently, the seasonal distortion of the tail plasma sheet has little effect on the acceleration of high-latitude auroral beams. The actual several minute time difference in opposite hemisphere onsets of PiB is probably due to the westward/poleward motion of the longitudinally extended aurora.

  3. Loss of Survivin influences liver regeneration and is associated with impaired Aurora B function

    PubMed Central

    Hagemann, S; Wohlschlaeger, J; Bertram, S; Levkau, B; Musacchio, A; Conway, E M; Moellmann, D; Kneiseler, G; Pless-Petig, G; Lorenz, K; Sitek, B; Baba, H A

    2013-01-01

    The chromosomal passenger complex (CPC) acts as a key regulator of mitosis, preventing asymmetric segregation of chromosomal material into daughter cells. The CPC is composed of three non-enzymatic components termed Survivin, the inner centromere protein (INCENP) and Borealin, and an enzymatic component, Aurora B kinase. Survivin is necessary for the appropriate separation of sister chromatids during mitosis and is involved in liver regeneration, but its role in regenerative processes is incompletely elucidated. Whether Survivin, which is classified as an inhibitor of apoptosis protein (IAP) based on domain composition, also has a role in apoptosis is controversial. The present study examined the in vivo effects of Survivin ablation in the liver and during liver regeneration after 70% hepatectomy in a hepatocyte-specific knockout mouse model. The absence of Survivin caused a reduction in the number of hepatocytes in the liver, together with an increase in cell volume, macronucleation and polyploidy, but no changes in apoptosis. During liver regeneration, mitosis of hepatocytes was associated with mislocalization of the members of the CPC, which were no longer detectable at the centromere despite an unchanged protein amount. Furthermore, the loss of survivin in regenerating hepatocytes was associated with reduced levels of phosphorylated Histone H3 at serine 28 and abolished phosphorylation of CENP-A and Hec1 at serine 55, which is a consequence of decreased Aurora B kinase activity. These data indicate that Survivin expression determines hepatocyte number during liver development and liver regeneration. Lack of Survivin causes mislocalization of the CPC members in combination with reduced Aurora B activity, leading to impaired phosphorylation of its centromeric target proteins and inappropriate cytokinesis. PMID:23519077

  4. The induction of polyploidy or apoptosis by the Aurora A kinase inhibitor MK8745 is p53-dependent

    PubMed Central

    Ho, Alan L; Schwartz, Gary K

    2012-01-01

    Aurora kinases are mitotic serine/threonine protein kinases and are attractive novel targets for anticancer therapy. Many small-molecule inhibitors of Aurora kinases are currently undergoing clinical trials. Aurora A kinase is essential for successful mitotic transition. MK8745 is a novel and selective small-molecule inhibitor of Aurora A kinase. MK8745 induced apoptotic cell death in a p53-dependent manner when tested in vitro in cell lines of multiple lineages. Cells expressing wild-type p53 showed a short delay in mitosis followed by cytokinesis, resulting in 2N cells along with apoptosis. However, cells lacking or with mutant p53 resulted in a prolonged arrest in mitosis followed by endoreduplication and polyploidy. Cytokinesis was completely inhibited in p53-deficient cells, as observed by the absence of 2N cell population. The induction of apoptosis in p53-proficient cells was associated with activation of caspase 3 and release of cytochrome c but was independent of p21. Exposure of p53 wild-type cells to MK8745 resulted in the induction of p53 phosphorylation (ser15) and an increase in p53 protein expression. p53-dependent apoptosis by MK8745 was further confirmed in HCT 116 p53−/− cells transfected with wild-type p53. Transient knockdown of Aurora A by specific siRNA recapitulated these p53-dependent effects, with greater percent induction of apoptosis in p53 wild-type cells. In conclusion, our studies show p53 as a determining factor for induction of apoptosis vs. polyploidy upon inhibition of Aurora A. PMID:22293494

  5. AURORA BOREALIS - Development of a New Research Icebreaker with Drilling Capability

    NASA Astrophysics Data System (ADS)

    Thiede, J.; Biebow, N.; Egerton, P.; Kunz-Pirrung, M.; Lembke-Jene, L.

    2007-12-01

    Polar research both on land and in the sea cannot achieve the needed progress without novel and state of the art technologies and infrastructure. In addition, we have the obligation to equip the upcoming young and courageous generation of polar researchers with the most modern and safest research platforms the 21st century can provide. This effort will require major investments, both in terms of generating new tools, as well as maintaining and renovating existing infrastructure. There are many different novel tools under development for polar research, we will concentrate on the presently largest one, the planning for a new type of research icebreaker, the AURORA BOREALIS with an all-season capability of operations in permanently ice-covered waters and with the possibility to carry out deep-sea drilling in ice-covered deep-sea basins. AURORA BOREALIS will be the most advanced Polar Research Vessel in the world with a multi-functional role of drilling in deep ocean basins and supporting climate and environmental research and decision support for stakeholder governments for the next 35 to 40 years. The vessel is planned as a large research icebreaker with 44,000 tons displacement and a length of up to 196 m, with about 50 Megawatt propulsion power. Advanced technological features will include azimuth propulsion systems, extensive instrumental and airborne ice- management support, and the routine operation of Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUVs) from two moon-pools. An unique feature of this icebreaker will be the drilling rig that will enable sampling of the ocean floor and sub-sea down to 5000 m water depth and 1000 m penetration at the most inhospitable places on earth. The possibility to flexibly equip the ship with laboratory and supply containers, and the variable arrangement of other modular infrastructure (in particular, winches, cranes, etc.), free deck- space, and separate protected deck areas, will allow the planned

  6. Periodicities in the occurrence of aurora as indicators of solar variability

    NASA Astrophysics Data System (ADS)

    Nian-Zu, D.; Mei-Dong, C.; Zhen-Jin, Z.; Mendillo, M.

    1983-11-01

    A compilation of records of the aurora observed in China from the Time of the Legends (2000 - 3000 B.C.) to the mid-18th century has been used to infer the frequencies and strengths of solar activity prior to modern times. A merging of this analysis with auroral and solar activity patterns during the last 200 years provides basically continuous information about solar activity during the last 2000 years. The results show periodicities in solar activity that contain average components with a long period (approx. 412 years), three middle periods (approx. 38 years, approx. 77 years, and approx. 130 years), and the well known short period (approx. 11 years).

  7. Statistical analysis of post-equinoctial Uranus' aurorae and implications on the role of solar wind

    NASA Astrophysics Data System (ADS)

    Lamy, L.

    2015-10-01

    The re-detection of Uranian Ultraviolet aurorae with the Hubble Space Telescope in 2011, 4 years after equinox, during active solar wind conditions provided a novel opportunity to study the Uranus' asymmetrical magnetosphere and its interaction with the solar wind over the Uranian revolution around the sun. The identified signatures were tentatively attributed to intermittent magnetic reconnexion with the interplanetary magnetic field. I will present more recent HST observations obtained in 2012 and 2014 with variable solar wind conditions. They revealed additional detections which, in turn, seem to indicate a prominent role of the solar wind in driving auroral precipitations.

  8. On the Total Energy Deposition Between Periodically Occurring Activations of the Aurora

    NASA Technical Reports Server (NTRS)

    Spann, James F., Jr.; Germany, G. A.; Parks, G. K.; Brittnacher, M. J.; Winglee, R. W.

    1998-01-01

    Total energy deposition in the northern latitudes is used in models to determine the state of the magnetosphere. It is known that on occasion, a series of intensifications of the aurora occur that are regularly spaced. The energy profile of the total energy deposited reflects this occurance. What can be said of the state of the magnetosphere based on these profiles. We present the result of a study which looks at several of these periods when a series of intensifications occur. Conclusions as to what the magnetosphere may be doing are presented.

  9. A search for nitric oxide gamma band emission in an aurora

    NASA Technical Reports Server (NTRS)

    Beiting, E. J., III; Feldman, P. D.

    1978-01-01

    A strong emission feature at 2150 A has been observed by a rocket-borne spectrophotometer in an IBC II(+) aurora. This feature, commonly identified with the NO gamma (1,0) band, is comparable in intensity to the nearby N2 Vegard-Kaplan bands. Comparison of the observed spectra with a theoretically produced synthetic spectrum allows all but this feature to be assigned to N2 transitions. No bands of the v prime = 0 or 2 progressions or any other bands from v prime = 1 appear, casting serious doubt on the identification of this feature as the NO gamma (1,0) band.

  10. Helium soil-gas survey of the aurora uranium deposit, McDermitt Caldera Complex, Oregon

    SciTech Connect

    Reimer, G.M.

    1986-11-10

    Two soil gas helium surveys were carried out in a section of the McDermitt caldera complex of mineralized volcanic rocks in Oregon. A regional helium anomaly was found and is thought to be associated with uranium-rich tuffaceous fill of the caldera and the Aurora uranium deposit, which occurs near the northeastern rim of the Caldera. Local hydrology may have an effect on the displacement of the helium anomaly from the uranium deposit and be a carrier of helium from sources at depth. This study suggests that helium surveys may be useful in a volcanic environment by helping to select areas for exploratory drilling for uranium deposits.

  11. The TD6 (Aurora Stratum) hominid site. Final remarks and new questions.

    PubMed

    Bermúdez de Castro, J M; Carbonell, E; Cáceres, I; Díez, J C; Fernández-Jalvo, Y; Mosquera, M; Ollé, A; Rodríguez, J; Rodríguez, X P; Rosas, A; Rosell, J; Sala, R; Vergés, J M; van der Made, J

    1999-01-01

    The study of the faunal and lithic assemblage (including almost a hundred human fossil remains) recovered from the Aurora stratum-TD6 level of the Lower Pleistocene cave site of Gran Dolina (Sierra de Atapuerca, Spain) has allowed us to answer some important questions concerning the debate about the earliest evidence for human occupation of Europe. However, it has also started new discussions about some geographical, ecological, and economic aspects of this earliest occupation. The nature (definitive or ephemeral) of the first occupation, as well as the model for the arrival of the Acheulean (Mode 2) in Europe are also issues for discussion. PMID:10497004

  12. Periodicities in the occurrence of aurora as indicators of solar variability

    NASA Technical Reports Server (NTRS)

    Nian-Zu, D.; Mei-Dong, C.; Zhen-Jin, Z.; Mendillo, M.

    1983-01-01

    A compilation of records of the aurora observed in China from the Time of the Legends (2000 - 3000 B.C.) to the mid-18th century has been used to infer the frequencies and strengths of solar activity prior to modern times. A merging of this analysis with auroral and solar activity patterns during the last 200 years provides basically continuous information about solar activity during the last 2000 years. The results show periodicities in solar activity that contain average components with a long period (approx. 412 years), three middle periods (approx. 38 years, approx. 77 years, and approx. 130 years), and the well known short period (approx. 11 years).

  13. An extensive survey of dayside diffuse aurora based on optical observations at Yellow River Station

    NASA Astrophysics Data System (ADS)

    Han, De-Sheng; Chen, Xiang-Cai; Liu, Jian-Jun; Qiu, Qi; Keika, K.; Hu, Ze-Jun; Liu, Jun-Ming; Hu, Hong-Qiao; Yang, Hui-Gen

    2015-09-01

    By using 7 years optical auroral observations obtained at Yellow River Station (magnetic latitude 76.24°N) at Ny-Alesund, Svalbard, we performed the first extensive survey for the dayside diffuse auroras (DDAs) and acquired observational results as follows. (1) The DDAs can be classified into two broad categories, i.e., unstructured and structured DDAs. The unstructured DDAs are mainly distributed in morning and afternoon, but the structured DDAs predominantly occurred around the magnetic local noon (MLN). (2) The unstructured DDAs observed in morning and afternoon present obviously different properties. The afternoon ones are much stable and seldom show pulsating property. (3) The DDAs are more easily observed under geomagnetically quiet times. (4) The structured DDAs mainly show patchy, stripy, and irregular forms and are often pulsating and drifting. The drifting directions are mostly westward (with speed ~5 km/s), but there are cases showing eastward or poleward drifting. (5) The stripy DDAs are exclusively observed near the MLN and, most importantly, their alignments are confirmed to be consistent with the direction of ionospheric convection near the MLN. (6) A new auroral form, called throat aurora, is found to be developed from the stripy DDAs. Based on the observational results and previous studies, we proposed our explanations to the DDAs. We suggest that the unstructured DDAs observed in the morning are extensions of the nightside diffuse aurora to the dayside, but that observed in the afternoon are predominantly caused by proton precipitations. The structured DDAs occurred near the MLN are caused by interactions of cold plasma structures, which are supposed to be originated from the ionospheric outflows or plasmaspheric drainage plumes, with hot electrons from the plasma sheet. We suppose that the cold plasma structures for producing the patchy DDAs are in lumpy and are more likely from the plasmaspheric drainage plumes. The cold plasma structure for

  14. Indole Alkaloids from the Sea Anemone Heteractis aurora and Homarine from Octopus cyanea.

    PubMed

    Shaker, Kamel H; Göhl, Matthias; Müller, Tobias; Seifert, Karlheinz

    2015-11-01

    The two new indole alkaloids 2-amino-1,5-dihydro-5-(1H-indol-3-ylmethyl)-4H-imidazol-4-one (1), 2-amino-5-[(6-bromo-1H-indol-3-yl)methyl]-3,5-dihydro-3-methyl-4H-imidazol-4-one (2), and auramine (3) have been isolated from the sea anemone Heteractis aurora. Both indole alkaloids were synthesized for the confirmation of the structures. Homarine (4), along with uracil (5), hypoxanthine (6), and inosine (7) have been obtained from Octopus cyanea. PMID:26567952

  15. Poleward leaping auroras, the substorm expansive and recovery phases and the recovery of the plasma sheet

    SciTech Connect

    Hones, E.W.

    1992-01-01

    The auroral motions and geomagnetic changes the characterize the substorm's expansive phase, maximum epoch, and recovery phase are discussed in the context of their possible associations with the dropout and, especially, the recovery of the magnetotail plasma sheet. The evidence that there may be an inordinately sudden large poleward excursion or displacement (a poleward leap) of the electrojet and the auroras at the expansive phase-recovery phase transition is described. The close temporal association of these signatures with the recovery of the plasma sheet, observed on many occasions, suggests a causal relationship between substorm maximum epoch and recovery phase on the one hand and plasma sheet recovery on the other.

  16. A simple model for polar cap convection patterns and generation of theta auroras

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1985-01-01

    An addition of the uniform interplanetary magnetic field and the earth's dipole magnetic field is used to evaluate electric field convection patterns over the polar caps that result from solar wind flow across open geomagnetic field lines. The model also accounts for field-aligned patterns within, and auroral arcs across, the polar cap. The qualitative predictions derived from the model express the electric field magnitudes, aurora intensity, sunward and antisunward flow, and the dusk-side reversal of the convection field in terms of the x and y components of the interplanetary magnetic field.

  17. Poleward leaping auroras, the substorm expansive and recovery phases and the recovery of the plasma sheet

    SciTech Connect

    Hones, E.W.

    1992-05-01

    The auroral motions and geomagnetic changes the characterize the substorm`s expansive phase, maximum epoch, and recovery phase are discussed in the context of their possible associations with the dropout and, especially, the recovery of the magnetotail plasma sheet. The evidence that there may be an inordinately sudden large poleward excursion or displacement (a poleward leap) of the electrojet and the auroras at the expansive phase-recovery phase transition is described. The close temporal association of these signatures with the recovery of the plasma sheet, observed on many occasions, suggests a causal relationship between substorm maximum epoch and recovery phase on the one hand and plasma sheet recovery on the other.

  18. Applications of the Aurora parallel Prolog system to computational molecular biology

    SciTech Connect

    Lusk, E.L.; Overbeek, R.; Mudambi, S.; Szeredi, P.

    1993-09-01

    We describe an investigation into the use of the Aurora parallel Prolog system in two applications within the area of computational molecular biology. The computational requirements were large, due to the nature of the applications, and were large, due to the nature of the applications, and were carried out on a scalable parallel computer the BBN ``Butterfly`` TC-2000. Results include both a demonstration that logic programming can be effective in the context of demanding applications on large-scale parallel machines, and some insights into parallel programming in Prolog.

  19. In vitro anti-myeloma activity of the Aurora kinase inhibitor VE-465.

    PubMed

    Negri, Joseph M; McMillin, Douglas W; Delmore, Jake; Mitsiades, Nicholas; Hayden, Patrick; Klippel, Steffen; Hideshima, Teru; Chauhan, Dharminder; Munshi, Nikhil C; Buser, Carolyn A; Pollard, John; Richardson, Paul G; Anderson, Kenneth C; Mitsiades, Constantine S

    2009-12-01

    This study characterized the preclinical anti-myeloma activity of VE465, a low molecular weight pan-Aurora kinase inhibitor. After 96-h drug exposure, several multiple myeloma (MM) cell lines were more sensitive to VE465 compared to non-malignant cells. The anti-MM activity of VE465 was maintained in the presence of interleukin-6 and, interestingly, enhanced by co-culture with stromal cells. However, primary MM cells were less responsive than cell lines. Combinations with dexamethasone (Dex), doxorubicin (Doxo) and bortezomib showed no antagonism. Our study highlights the potential role of the tumour microenvironment in modulating the activity of this drug class. PMID:19751238

  20. Stratospheric temperature and composition of Jupiter's polar aurora from IRTF-TEXES

    NASA Astrophysics Data System (ADS)

    Sinclair, J.; Orton, G. S.; Greathouse, T. K.; Fletcher, L. N.; Irwin, P. G. J.

    2015-10-01

    We perform an analysis of TEXES (Texas Echelon Cross Echelle Spectrograph, 5- to 25- μm,[1]) spectra of Jupiter's high latitudes observed in December 2014 in order to study the jovian polar aurora. The high resolving power (R˜85000) of TEXES allows a large altitude range (10 mbar to 0.01 mbar) in Jupiter's stratosphere to be sounded. Retrievals of temperature and stratospheric composition of these measurements therefore: 1) allow the vertical deposition of auroral energy to be determined and 2) quantify how the auro-ral processes modify the thermal structure and composition of the jovian stratosphere.

  1. Dasatinib suppression of medulloblastoma survival and migration is markedly enhanced by combining treatment with the aurora kinase inhibitor AT9283

    PubMed Central

    Petersen, William; Liu, Jingbo; Yuan, Liangping; Zhang, Hongying; Schneiderjan, Matthew; Cho, Yoon-Jae; MacDonald, Tobey J.

    2014-01-01

    Medulloblastoma (MB) expresses Src kinase, while aurora kinase A overexpression correlates with poor survival. We thus investigated novel combination treatment with dasatinib and AT9283, inhibitors of Src and aurora kinase, respectively, on MB growth in vitro and in vivo. Treatment with each drug significantly reduced cell viability and combined treatment markedly potentiated this response. AT9283 induced p53 expression, autophagy, and G2/M cell-cycle arrest, while combined treatment induced S phase arrest. Dasatinib treatment caused tumor regression in vivo. Activated Src was detected in 44% MB analyzed. We conclude that further evaluation of this combination therapy for MB is highly warranted. PMID:25107642

  2. Long-term Spatial and Temporal Variations of Aurora Borealis Events in the Period 1700 - 1905

    NASA Astrophysics Data System (ADS)

    Vázquez, M.; Vaquero, J. M.; Gallego, M. C.

    2014-05-01

    Catalogues and other records of aurora-borealis events were used to study the long-term spatial and temporal variation of these phenomena in the period from 1700 to 1905 in the Northern Hemisphere. For this purpose, geographic and geomagnetic coordinates were assigned to approximately 27 000 auroral events with more than 80 000 observations. They were analyzed separately in three large-scale areas: i) Europe and North Africa, ii) North America, and iii) Asia. There was a clear need to fill some gaps existing in the records so as to have a reliable proxy of solar activity, especially during the 18th century. In order to enhance the long-term variability, an 11-year smoothing window was applied to the data. Variations in the cumulative numbers of auroral events with latitude (in both geographic and geomagnetic coordinates) were used to discriminate between the two main solar sources: coronal mass ejections and high-speed streams from coronal holes. The characteristics of the associated auroras correlate differently with the solar-activity cycle.

  3. The morphology of the north Jovian ultraviolet aurora observed with the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Gerard, Jean-Claude; Dols, Vincent; Prange, Renee; Paresce, Francesco

    1994-01-01

    A series of six images covering a complete rotation of the north polar region of Jupiter were obtained in February 1993 with the Faint Object Camera on board the Hubble Space Telescope (HST). These images provide the first global picture of the morphology of the Jovian ultraviolet aurora observed from Earth orbit. The camera passband was centered near 153 nm, a region dominated by the H2 Lyman bands and continuum. The successive exposures, taken approximately 90 min apart, are used to construct a polar view of the auroral zone. It is found that the auroral emissions do not exactly follow the footprint of a constant L-shell although the size of the oval and its location agree best with the footprints of the approximately equal to 30 R(sub J) field line in the GSFC O6 model of the Jovian magnetic field. The displacement between the observed auroral zone and the theoretical oval may indicate a possible distortion of the Jovian magnetic field lines near the surface. A comparison with two images at the same wavelength obtained 8 months earlier shows that the main morphological features are persistent, in spite of changes in the detailed emission distribution. Small scale features with characteristic sizes of approximately 1000 km are observed along the auroral oval. The change of morphology observed as a function of the System 3 longitude appears as a persistent characteristic of the morphology of the north polar aurora.

  4. Ndel1 suppresses ciliogenesis in proliferating cells by regulating the trichoplein-Aurora A pathway.

    PubMed

    Inaba, Hironori; Goto, Hidemasa; Kasahara, Kousuke; Kumamoto, Kanako; Yonemura, Shigenobu; Inoko, Akihito; Yamano, Shotaro; Wanibuchi, Hideki; He, Dongwei; Goshima, Naoki; Kiyono, Tohru; Hirotsune, Shinji; Inagaki, Masaki

    2016-02-15

    Primary cilia protrude from the surface of quiescent cells and disassemble at cell cycle reentry. We previously showed that ciliary reassembly is suppressed by trichoplein-mediated Aurora A activation pathway in growing cells. Here, we report that Ndel1, a well-known modulator of dynein activity, localizes at the subdistal appendage of the mother centriole, which nucleates a primary cilium. In the presence of serum, Ndel1 depletion reduces trichoplein at the mother centriole and induces unscheduled primary cilia formation, which is reverted by forced trichoplein expression or coknockdown of KCTD17 (an E3 ligase component protein for trichoplein). Serum starvation induced transient Ndel1 degradation, subsequent to the disappearance of trichoplein at the mother centriole. Forced expression of Ndel1 suppressed trichoplein degradation and axonemal microtubule extension during ciliogenesis, similar to trichoplein induction or KCTD17 knockdown. Most importantly, the proportion of ciliated and quiescent cells was increased in the kidney tubular epithelia of newborn Ndel1-hypomorphic mice. Thus, Ndel1 acts as a novel upstream regulator of the trichoplein-Aurora A pathway to inhibit primary cilia assembly. PMID:26880200

  5. Solar wind-Magnetosphere-Ionosphere Coupling and Aurora at Jupiter and Saturn

    NASA Astrophysics Data System (ADS)

    Bunce, E. J.; Cowley, S. W. H.

    2015-10-01

    Solar wind-magnetosphere-ionosphere coupling is accomplished through the existence of largescale field-aligned currents which are generated in a source region and end in a sink region, and which transfer momentum (and energy) between the regions. Therefore, to move beyond a theoretical picture of how this works at Jupiter and Saturn we require in-situ measurements of these regions primarily in the form of magnetic field measurements, but importantly combined with in-situ plasma, plasma wave data, and remote auroral observations. Since the arrival of Cassini at Saturn in 2004 we have had many opportunities to sample the high-latitude magnetosphere and aurora and have learned a great deal about how this giant magnetosphere works. We also await the "proximal" orbit phase of Cassini where we will obtain information on the high-latitude magnetosphere very close to Saturn. In the case of Jupiter, we eagerly anticipate the first high-latitude observations from the Juno mission, due to arrive in the Jupiter system in 2016. The simultaneous observations from Cassini at Saturn in the final phase of the mission until 2017, and Juno at Jupiter during 2016/17, will be a first in planetary science, and we expect to learn a great deal about both planetary magnetospheres individually and by comparison. Here then, we will give an overview of what we have learned so far from Cassini at Saturn, and how it might apply to Juno at Jupiter. A principal "source" of the field-aligned currents is the planetary neutral atmosphere, that at Saturn imposes both sub-corotation (and is axi-symmetric to a first approximation), as well as an m=1 rotating twin-vortex perturbation of comparable magnitude. The Cassini data have revealed that there are two separate systems in the Northern and Southern hemispheres rotating with slowly-changing separate periods. These have been systematically studied, principally in the pre-equinox (2008) Cassini data on the nightside. The sub-corotation system of field

  6. Phenotypic Screening Approaches to Develop Aurora Kinase Inhibitors: Drug Discovery Perspectives.

    PubMed

    Marugán, Carlos; Torres, Raquel; Lallena, María José

    2015-01-01

    Targeting mitotic regulators as a strategy to fight cancer implies the development of drugs against key proteins, such as Aurora-A and -B. Current drugs, which target mitosis through a general mechanism of action (stabilization/destabilization of microtubules), have several side effects (neutropenia, alopecia, and emesis). Pharmaceutical companies aim at avoiding these unwanted effects by generating improved and selective drugs that increase the quality of life of the patients. However, the development of these drugs is an ambitious task that involves testing thousands of compounds through biochemical and cell-based assays. In addition, molecules usually target complex biological processes, involving several proteins and different molecular pathways, further emphasizing the need for high-throughput screening techniques and multiplexing technologies in order to identify drugs with the desired phenotype. We will briefly describe two multiplexing technologies [high-content imaging (HCI) and flow cytometry] and two key processes for drug discovery research (assay development and validation) following our own published industry quality standards. We will further focus on HCI as a useful tool for phenotypic screening and will provide a concrete example of HCI assay to detect Aurora-A or -B selective inhibitors discriminating the off-target effects related to the inhibition of other cell cycle or non-cell cycle key regulators. Finally, we will describe other assays that can help to characterize the in vitro pharmacology of the inhibitors. PMID:26779442

  7. Ionospheric loop currents and associated ULF oscillations at geosynchronous altitudes during preonset intervals of substorm aurora

    NASA Astrophysics Data System (ADS)

    Saka, O.; Hayashi, K.; Leonovich, A. S.

    2015-04-01

    A substorm aurora was observed at 04:52 UT on 27 January 1986 by an all-sky imager installed at Shamattawa (66.3°N, 336.0° in corrected geomagnetic coordinates) and a magnetometer on board a conjugate satellite (GOES 6) at geosynchronous altitudes. In the preonset intervals lasting for approximately 50 min prior to the expansion onset, an equatorward drift of the auroras beginning from 71°N to 64°N was observed. Meanwhile, GOES 6 observed ULF oscillations in 25-200 s periods at geosynchronous altitudes after about 10 min following the start of the equatorward drift. During the equatorward drift of the arc, the flow reversal occurred, where the auroral arc propagating eastward was replaced by a westward propagation. Simultaneously, the major axes of the ULF oscillations rotated clockwise by ~90° in the equatorial plane. We conclude that the ULF oscillations are azimuthally small-scale Alfvén waves excited in the magnetosphere by field-aligned currents associated with ionospheric loop currents.

  8. The Proton and Electron Aurora as Seen by Image-FUV and FAST

    NASA Technical Reports Server (NTRS)

    Gerard, J.-C.; Hubert, B.; Habraken, S.; Renotte, E.; Jamar, C.; Rochus, P.; Spann, J.; Gladstone, R.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    The Far Ultraviolet (FUV) instrument on IMAGE images the aurora in three different wavelength regions. The Wideband Imaging Camera (WIC) observes the molecular Lyman-Birge-Hopfield (LBH) and atomic Nitrogen emissions at 140-190 nm. The two channels of the Spectrographic Imager (SI) observe the Doppler shifted Lyman Alpha emission of precipitating protons at 121.8 nm (SI 12) and the mostly electron produced emission from oxygen OI at 135.6 nm (SI13). The major advantage of FUV compared to previously flown UV imagers is the simultaneous operation of all three imaging systems without the need for filter changes and the uncertainty of temporal changes of the aurora between exposures. The FAST satellite passes every two hours through FUV images during apogee operations. This enables a comparison between the remotely imaged particle precipitation and the in-situ measurements along the FAST track. The detailed analysis of images from all three systems together with a full simulation of auroral emissions based on in-situ measurements by FAST confirms the laboratory calibrations of FUV. The spatial resolution and image quality of WIC permits the observation of a good correspondence between in-situ and remote measurements of precipitation boundaries. The clear separation between the lower latitude proton precipitation and the more structured higher latitude electron precipitation is obtained with both SI-channels.

  9. Computational approach to the identification of novel Aurora-A inhibitors.

    PubMed

    Morshed, Mohammad Neaz; Cho, Yong Seo; Seo, Seon Hee; Han, Ki-Cheol; Yang, Eun Gyeong; Pae, Ae Nim

    2011-01-15

    Aurora kinase A has been emerging as a key therapeutic target for the design of anticancer drugs. For the purpose of finding biologically active and novel compounds and providing new ideas for drug-design, we performed virtual screening using commercially available databases. A three-dimensional common feature pharmacophore model was developed with the HipHop program provided in the Catalyst software package, and this model was used as a query for screening the databases. A recursive partitioning (RP) model was developed as a filtering system, which was able to classify active and inactive compounds. Eventually, a step-wise virtual screening procedure was conducted by applying the common feature pharmacophore and the RP model in succession to discover novel potent Aurora-A inhibitors. A total of 68 compounds were selected for testing of their in vitro anticancer activities against various human cancer cell lines. Based on the activity data, we have identified fifteen compounds that warrant further investigation. Several compounds have a high inhibition rate (above 80% at 10 μM) and a GI₅₀ lower than 5 μM for the cell lines DU145 and HT29. Enzyme assay for these compounds identified hits with micro molar activity. Compound C11 has the highest activity (IC₅₀ = 5.09 μM). The hits obtained from this screening scheme could be potential drug candidates after further optimization. PMID:21194953

  10. New Auroras on the Roles of the Chromosomal Passenger Complex in Cytokinesis: Implications for Cancer Therapies.

    PubMed

    D'Avino, Pier Paolo; Capalbo, Luisa

    2015-01-01

    The chromosomal passenger complex (CPC), composed of a kinase component, Aurora B, the scaffolding subunit inner centromeric protein, Borealin, and Survivin, is a key regulator of cell division. It controls multiple events, from chromosome condensation in prophase to the final separation or abscission of the two daughter cells. The essential functions of the CPC during metaphase, however, have always hindered an accurate study of its role during cytokinesis. The recent development of small molecule inhibitors against Aurora B and the use of elegant technologies such as chemical genetics have offered new approaches to study the functions of the CPC at the end of cell division. Here, we review the recent findings about the roles of the CPC in controlling the assembly of the cleavage furrow, central spindle, and midbody. We will also discuss the crucial function of this complex in controlling abscission timing in order to prevent abscission when lagging chromatin is present at the cleavage site, thereby avoiding the formation of genetically abnormal daughter cells. Finally, we offer our perspective on how to exploit the potential therapeutic applications of inhibiting CPC activity during cytokinesis in cancer cells. PMID:26528433

  11. Coordinated analysis of data. [all sky photography observations of the ATS 5 satellite of auroras

    NASA Technical Reports Server (NTRS)

    Mende, S. B.

    1974-01-01

    All Sky Cameras (ASCA) observations were made at the field line conjugate of the ATS-5 Satellite. The field of view of these cameras covered the region of the magnetosphere from L=5 to L=ll at the approximate longitude of the ATS field line conjugate. Definite statements are made concerning the correlation of the auroras observed by the ASCA's and the magnetospheric trapped fluxes. No auroras are observed at the field line conjugate, on quiet days when the hot plasma does not penetrate into the magnetosphere far enough to reach the ATS-5 orbit. On more disturbed days, when the ATS-5 enters the plasma sheet containing plasma clouds, an equatorward motion of the lowest latitude auroral arc is observed. Significant qualitative correlation between the ASCA data and the trapped fluxes is observed when a local plasma injection event occurs near ATS-5. The clearest signature of the injection event is magnetic and is most pronounced as a recovery of a negative bay at the ATS-5 magnetometer. The most significant correlations are observed with the intensification of the diffuse uniform glow which intensifies during the injection event.

  12. Aurora Kinases Phosphorylate Lgl to Induce Mitotic Spindle Orientation in Drosophila Epithelia

    PubMed Central

    Bell, Graham P.; Fletcher, Georgina C.; Brain, Ruth; Thompson, Barry J.

    2015-01-01

    Summary The Lethal giant larvae (Lgl) protein was discovered in Drosophila as a tumor suppressor in both neural stem cells (neuroblasts) and epithelia. In neuroblasts, Lgl relocalizes to the cytoplasm at mitosis, an event attributed to phosphorylation by mitotically activated aPKC kinase and thought to promote asymmetric cell division. Here we show that Lgl also relocalizes to the cytoplasm at mitosis in epithelial cells, which divide symmetrically. The Aurora A and B kinases directly phosphorylate Lgl to promote its mitotic relocalization, whereas aPKC kinase activity is required only for polarization of Lgl. A form of Lgl that is a substrate for aPKC, but not Aurora kinases, can restore cell polarity in lgl mutants but reveals defects in mitotic spindle orientation in epithelia. We propose that removal of Lgl from the plasma membrane at mitosis allows Pins/LGN to bind Dlg and thus orient the spindle in the plane of the epithelium. Our findings suggest a revised model for Lgl regulation and function in both symmetric and asymmetric cell divisions. PMID:25484300

  13. Transpolar auroras, their particle precipitation, and IMF B sub y component

    SciTech Connect

    Makita, K. ); Meng, C.I. ); Akasofu, S.I. )

    1991-08-01

    Transpolar auroras, their associated particle precipitation, and their occurrence with respect to the IMF B{sub y} polarity are examined on the basis of DMSP F6 auroral images and the corresponding particle data. It is found that the transpolar arcs are located in the poleward edge of the soft particle precipitation region extending from either the dawn or dusk part of the auroral oval precipitation; they are not embedded in the polar rain region. This finding suggests that the transpolar arcs are located along the poleward boundary of the closed field line region (or the equatorward boundary of the open region) as suggested by Meng. Further, the appearance of the extended precipitation region from the oval depends on the polarity of the IMF B{sub y}, in the northern hemisphere morning sector for IMF B{sub y} < 0 or in the evening sector for IMF B{sub y} > 0. In general, the precipitating particle flux in the extended precipitation region is not high enough to produce appreciable luminosity. Thus only the transpolar arcs (associated with relatively intense precipitation) near the poleward boundary tend to become much more luminous, forming the so-called theta aurora.

  14. Precipitation of relativistic electrons of the Van Allen belts into the proton aurora

    SciTech Connect

    Jordanova, Vania K; Miyoshi, Y; Sakaguchi, K; Shiokawa, K; Evans, D S; Connors, M

    2008-01-01

    The Van Allen electron belts consist of two regions encircling the earth in which relativistic electrons are trapped in the earth's magnetic field. Populations of relativistic electrons in the Van Allen belts vary greatly with geomagnetic disturbance and they are a major source of damage to space vehicles. In order to know when and by how much these populations of relativistic electrons increase, it is important to elucidate not only the cause of acceleration of relativistic electrons but also the cause of their loss from the Van Allen belts. Here we show the first evidence that left-hand polarized electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere, on the basis of results of an excellent set of ground and satellite observations showing coincident precipitation of ions with energies of tens of keV and of relativistic electrons into an isolated proton aurora. The proton aurora was produced by precipitation of ions with energies of tens of keV due to EMIC waves near the plasma pause, which is a manifestation of wave-particle interactions. These observations clarify that ions with energies of tens of keV affect the evolution of relativistic electrons in the Van Allen belts via parasitic resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970's.

  15. New Auroras on the Roles of the Chromosomal Passenger Complex in Cytokinesis: Implications for Cancer Therapies

    PubMed Central

    D’Avino, Pier Paolo; Capalbo, Luisa

    2015-01-01

    The chromosomal passenger complex (CPC), composed of a kinase component, Aurora B, the scaffolding subunit inner centromeric protein, Borealin, and Survivin, is a key regulator of cell division. It controls multiple events, from chromosome condensation in prophase to the final separation or abscission of the two daughter cells. The essential functions of the CPC during metaphase, however, have always hindered an accurate study of its role during cytokinesis. The recent development of small molecule inhibitors against Aurora B and the use of elegant technologies such as chemical genetics have offered new approaches to study the functions of the CPC at the end of cell division. Here, we review the recent findings about the roles of the CPC in controlling the assembly of the cleavage furrow, central spindle, and midbody. We will also discuss the crucial function of this complex in controlling abscission timing in order to prevent abscission when lagging chromatin is present at the cleavage site, thereby avoiding the formation of genetically abnormal daughter cells. Finally, we offer our perspective on how to exploit the potential therapeutic applications of inhibiting CPC activity during cytokinesis in cancer cells. PMID:26528433

  16. Coordinated Cassini and Earth-based Observations of Saturn's Aurora During the 2013 Opposition

    NASA Astrophysics Data System (ADS)

    Crary, F.; Badman, S.; Bunce, E.; Hansen, K.; Kurth, W.; Nichols, J.; Stallard, T.; Pryor, W.

    2013-09-01

    During April and May, 2013, coordinated observations of Saturn's aurora were made by the Cassini spacecraft and several Earth-based telescopes. Here we report on the measurements, geometry and timing of these observations and introduce additional presentations of the results. The observations were made between April 18-23, April 29, May 7 and May 16-22. To the greatest extent possible, times were selected to allow simultaneous observations from Cassini and from Earth. While the Earth-based telescopes had a view of Saturn's north pole, Cassini made observations of both the north and south poles. This permits stereo studies of auroral structure when Cassini viewed the northern hemisphere and investigations of conjugate aurora when Cassini viewed the southern hemisphere. The Cassini remote sensing measurements were made primarily by the Ultraviolet Imaging Spectrometer (UVIS) and the Visible and Infrared Mapping Spectrometer (VIMS) although the Imaging Science Subsystem (ISS) also collected data. In situ measurements of the magnetosphere were also the magnetometer, the Radio and Plasma Wave Science (RPWS) instrument and the Magnetospheric Imaging Instrument (MIMI.) During this campaign the spacecraft was typically between 10 and 23 Saturn radii from the planet, at latitudes up to 61 degrees and in the late afternoon to dusk side of the magnetosphere. Earth-based observations were made in the ultraviolet by the Hubble Space Telescope's Advanced Camera for Survey and in the infrared by the Keck observatory and Infrared Telescope Facility and by the European Southern Observatory's Very Large Telescope.

  17. Simultaneous multi-wavelength observations of Saturn's aurorae : energy budget and magnetospheric dynamics

    NASA Astrophysics Data System (ADS)

    Lamy, L.

    2011-10-01

    Similarly to other magnetized planets, accelerated electrons entering Saturn's auroral regions generate powerful emissions. They divide into Ultraviolet (UV) and Infrared (IR) aurorae, originating from collisions with the upper atmosphere, and Saturn's Kilometric Radiation (SKR), radiated by an electron cyclotron resonance above the atmosphere up a few Saturn's radii (Rs). Previous studies have identified a large scale conjugacy between radio and UV, as well as IR and UV auroral emissions. Here, we investigate two days of observations of Saturn's aurorae at radio, UV and IR wavelengths, by the Cassini RPWS, UVIS and VIMS instruments, and their relationship with a reservoir of equatorial energetic particles mapped by energetic neutral atoms (ENA), as measured by MIMI-INCA (see Figure ??). This interval of time reveals a series of regular SKR modulations at the southern SKR phase, and interestingly includes an unusual (while also regular) enhancement of the auroral activity observed simultaneously at all wavelengths. This event is likely to illustrate a (regular) nightside injection of energetic particles, possibly induced by a plasmoid ejection, then co-rotating with the planet at the southern SKR period, while feeding an extended longitudinal sector of intense auroral emissions. We analyze quantitatively complementary informations brought by these different datasets in terms of energy budget transferred to the southern auroral region, as well as magnetospheric dynamics, in order to address the nature and the scheme of the Saturn's southern rotational modulation.

  18. Drift shells and aurora computed using the O8 magnetic field model for Neptune

    NASA Technical Reports Server (NTRS)

    Paranicas, C.; Cheng, A. F.

    1994-01-01

    Charged particle drift shells are calculated using the O8 magnetic field model for Neptune. Inner drift shell morphologies differ significantly from dipolar drift shells for the parts of drift shells inward of r = 2 R(sub N). Outer drift shells (L approx. greater than 10), when traced down to Neptune's surface following magnetic field lines, are simple closed loops around magnetic poles. Inner drift shells (L approx. less than 4), on the other hand, when traced to the surface, are also single loops but stretched in a previously unknown way: sometimes with a cusp and sometimes into two joined loops. Inner drift shell footprints on R = 1 provide the basis for identifying precipitation L shells, interpreting observed aurora, and predicting additional emissions on that part of Neptune's surface unobserved by the Ultraviolet Spectrometer (UVS). Precipitation in a global magnetic anomaly, `ordinary' auroral precipitation near the south magnetic pole, and precipitation from field lines with no magnetic field minimum above Neptune's exobase collectively appear to account for all of the observed auroral emission regions at Neptune. To the extent that aurora can be understood in this model, it is suggested O8 may be reasonably accurate.

  19. Phenotypic Screening Approaches to Develop Aurora Kinase Inhibitors: Drug Discovery Perspectives

    PubMed Central

    Marugán, Carlos; Torres, Raquel; Lallena, María José

    2016-01-01

    Targeting mitotic regulators as a strategy to fight cancer implies the development of drugs against key proteins, such as Aurora-A and -B. Current drugs, which target mitosis through a general mechanism of action (stabilization/destabilization of microtubules), have several side effects (neutropenia, alopecia, and emesis). Pharmaceutical companies aim at avoiding these unwanted effects by generating improved and selective drugs that increase the quality of life of the patients. However, the development of these drugs is an ambitious task that involves testing thousands of compounds through biochemical and cell-based assays. In addition, molecules usually target complex biological processes, involving several proteins and different molecular pathways, further emphasizing the need for high-throughput screening techniques and multiplexing technologies in order to identify drugs with the desired phenotype. We will briefly describe two multiplexing technologies [high-content imaging (HCI) and flow cytometry] and two key processes for drug discovery research (assay development and validation) following our own published industry quality standards. We will further focus on HCI as a useful tool for phenotypic screening and will provide a concrete example of HCI assay to detect Aurora-A or -B selective inhibitors discriminating the off-target effects related to the inhibition of other cell cycle or non-cell cycle key regulators. Finally, we will describe other assays that can help to characterize the in vitro pharmacology of the inhibitors. PMID:26779442

  20. Scaling of electric field fluctuations associated with the aurora during northward IMF

    NASA Astrophysics Data System (ADS)

    Kozelov, B. V.; Golovchanskaya, I. V.

    2006-10-01

    We present a statistical study of scaling features of the electric field fluctuations measured by the DE2 satellite in the polar region during positive Bz IMF when the theta-aurora was observed by the DE1 satellite. It is demonstrated that the power spectra of the fluctuations have a power-law form at spatial scales from ~0.5 km (the limit of resolution) to several thousands of kilometers, with a break near 100 km. The scaling properties of the field are studied by examining the generalized structure functions (GSFs) and probability density functions (PDFs) of the fluctuations. The observed PDFs have a non-Gaussian shape with heavy tails. We also demonstrate a collapse of the re-scaled PDFs onto a single curve. A relation of PDF shape to solar wind conditions is revealed. The same analysis is performed on the TV observations of the theta-aurora. The scaling characteristics of the field and auroral fluctuations are compared.

  1. Aurora B kinase is a potent and selective target in MYCN-driven neuroblastoma

    PubMed Central

    Azorsa, David O.; Ormanoglu, Pinar; Buehler, Eugen; Guha, Rajarshi; Keller, Jonathan M.; Griner, Lesley A. Mathews; Ferrer, Marc; Song, Young K.; Liao, Hongling; Mendoza, Arnulfo; Gryder, Berkley E.; Sindri, Sivasish; He, Jianbin; Wen, Xinyu; Zhang, Shile; Shern, John F.; Yohe, Marielle E.; Taschner-Mandl, Sabine; Shohet, Jason M.; Thomas, Craig J.; Martin, Scott E.; Ambros, Peter F.; Khan, Javed

    2015-01-01

    Despite advances in multimodal treatment, neuroblastoma (NB) is often fatal for children with high-risk disease and many survivors need to cope with long-term side effects from high-dose chemotherapy and radiation. To identify new therapeutic targets, we performed an siRNA screen of the druggable genome combined with a small molecule screen of 465 compounds targeting 39 different mechanisms of actions in four NB cell lines. We identified 58 genes as targets, including AURKB, in at least one cell line. In the drug screen, aurora kinase inhibitors (nine molecules) and in particular the AURKB-selective compound, barasertib, were the most discriminatory with regard to sensitivity for MYCN-amplified cell lines. In an expanded panel of ten NB cell lines, those with MYCN-amplification and wild-type TP53 were the most sensitive to low nanomolar concentrations of barasertib. Inhibition of the AURKB kinase activity resulted in decreased phosphorylation of the known target, histone H3, and upregulation of TP53 in MYCN-amplified, TP53 wild-type cells. However, both wild-type and TP53 mutant MYCN-amplified cell lines arrested in G2/M phase upon AURKB inhibition. Additionally, barasertib induced endoreduplication and apoptosis. Treatment of MYCN-amplified/TP53 wild-type neuroblastoma xenografts resulted in profound growth inhibition and tumor regression. Therefore, aurora B kinase inhibition is highly effective in aggressive neuroblastoma and warrants further investigation in clinical trials. PMID:26497213

  2. An update on the pharmacokinetics and pharmacodynamics of alisertib, a selective Aurora kinase A inhibitor.

    PubMed

    Durlacher, Cameron T; Li, Zhi-Ling; Chen, Xiao-Wu; He, Zhi-Xu; Zhou, Shu-Feng

    2016-06-01

    Human Aurora kinases, including Aurora kinase A (AURKA), B (AURKB), and C (AURKC), play an essential role in mitotic events such as monitoring of the mitotic checkpoint, creation of bipolar mitotic spindle and alignment of centrosomes on it, also regulating centrosome separation, bio-orientation of chromosomes and cytokinesis. AURKA and AURKB are key regulators of mitosis and centrosome via polymerizing microfilaments and controlling chromatid segregation. In particular, AURKA plays critical roles in the regulation of mitotic entry, centrosome function, bipolar spindle assembly, and chromosome segregation. AURKA has been found to be overexpressed in various solid and haematological cancers and has been linked with poor prognosis. Its important role in cancer initiation, growth, and metastasis has brought the focus to search for potent and selective AURKA inhibitors for cancer treatment. MLN8237, also known as alisertib, is one selective AURKA inhibitor that has shown remarkable anticancer effects in preclinical studies. Alisertib exhibits favourable pharmacokinetic properties. Alisertib has generally showed good partial response rates of 4-52% and good safety profiles in Phase I and II trials when it is solely administered as well as combined with cytotoxic chemotherapeutic drugs. Recently, the multicentre, randomized Phase III study of alisertib in patients with relapsed or refractory peripheral T-cell lymphoma has been discontinued due to unsatisfactory efficacy. The low risk of side effects, accessibility, and effectiveness of alisertib makes it a new promising anticancer therapy and further mechanistic and clinical studies are warranted. PMID:26999067

  3. Imaging-based observations of low-latitude auroras during 2001-2004 at Nayoro, Japan

    NASA Astrophysics Data System (ADS)

    Suzuki, Hidehiko; Chino, Haruka; Sano, Yasuo; Kadokura, Akira; Ejiri, Mitsumu K.; Taguchi, Makoto

    2015-07-01

    Color images of six low-latitude auroral events observed using color digital cameras at Nayoro (142.5° E, 44.4° N), Hokkaido, Japan, from 2001 to 2004, were analyzed to determine the events' locations and times of occurrence. Geographical azimuthal and elevation angles of the images' pixels were determined precisely by using the positions of the stars captured in the images. Horizontal regions covered by these auroral events were directly indicated by mapping the color images onto geographical maps and assuming that the emission layer's altitude is the lowest or highest value of a visible-level red aurora, as determined by the OI 630.0nm emission. The estimated geomagnetic latitudes and L values of these low-latitude auroral events were in the 39-50° range and below L < 2.5, respectively. This investigation indicates that four of the six auroral events were the same as those that were reported previously based on high-sensitivity optical observations at other sites on Hokkaido (Rikubetsu and Moshiri). Although the previous study is lacking information about the maximal brightness level of the red auroral events, the present investigation suggests that these four low-latitude auroral events reached the visible level. In addition, two new events were reported in this study. The present work provides essential information such as the morphology and appearance of visible auroras, which are extremely rare in mid- or low-latitude regions.

  4. Large amplitude undulations of evening site diffuse aurorae. Optical characteristics and conditions of generation

    NASA Astrophysics Data System (ADS)

    Vorobjev, V. G.; Roldugin, V. C.; Yagodkina, O. I.

    2015-01-01

    Optical characteristics of large amplitude undulations (LAU) of diffuse aurorae observed by all-sky cameras at Kola Peninsula on December 28, 2010 were examined. Both interplanetary medium conditions and characteristics of magnetic activity before and during LAU were analyzed. It was shown that the development of undulations could be activated by sharp short-living of ˜20 minutes solar wind dynamic pressure impulse and existence of the undulations during about two hours was supported by electric field of stationary magnetospheric convection originated from large smoothly changed southward IMF Bz component of about -12nT. The altitude of undulation luminosity determined by triangulation method was 120 ± 10 km. The undulations amplitude changed from about 100 to 300 km and the average wavelength was ˜250 km. The undulations were observed moving westward with the average phase velocity of ˜0.7 km/s. The pass of DMSP F16 spacecraft just along "the tongue" of undulations showed that the wave of luminosity was located in the region of the predominantly ion (proton) precipitation with the average energy of particles of ˜18 keV. Rayed auroral structures were observed continuously in the region of diffuse aurorae during time interval of LAU existence. These structures were observed moving westward with the velocity of about 2 km/s that corresponds to the northward electric field of ˜100 mV/m.

  5. How stable is the East Antarctic Craton? Clues from the Aurora, Concordia and Adventure Trenches

    NASA Astrophysics Data System (ADS)

    Cianfarra, P.; Salvini, F.

    2009-12-01

    The East Antarctic craton (EAC) is a fragment of the Gondwanaland Precambrian shield as confirmed from the sea floor geophysical reconstruction. Despite the progress achieved in the last decades for the understanding of the tectonic evolution of the EAC, our knowledge of the subglacial geology mainly derives from geophysical data because the ice sheet (3500m average thickness) prevents from direct investigations. Since the onset of the East Antarctic Ice Sheet (EAIS) (34 Ma), the tectonic activity represents the major modelling agent of the subglacial landscape, due to the dry ice cap-bedrock contact preventing any erosional or sedimentary episodes. Radio echo-sounding (RES) data evidence the existence of an articulated bedrock physiography characterised by elongated valleys. From W to E there are: the Vostok Subglacial Depression, the Aurora Trench, the Concordia Trench and the Adventure Trench. All these valleys have asymmetric shape with the eastern steeper side and the western gentler slope characterised by rounded shape that resemble the morphology observed in the East African rift valleys with half graben geometry. To explore the tectonic origin of the Aurora, Concordia and Adventure depressions a forward modelling approach was followed (Hybrid Cellular Automata technique), in order to best fit the present day bedrock morphology with the topographic expression of normal faults with a given geometry and displacement. The modelling consisted in simulating the development of the present day morphology by the relative movement between the footwall and the hangingwall of faults with normal component. These faults produce the observed asymmetry in their topographic expression. Tuning of fault geometry and displacement allowed to minimise the misfit between the model and the morphology derived from RES data. The Adventure and Aurora Trenches were replicated by the activity of two W dipping, listric faults, both fading into a detachment surface at the depth of 34 km

  6. The Aurora volcanic field, California-Nevada: oxygen fugacity constraints on the development of andesitic magma

    NASA Astrophysics Data System (ADS)

    Lange, R. A.; Carmichael, Ian S. E.

    1996-10-01

    The Aurora volcanic field, located along the northeastern margin of Mono Lake in the Western Great Basin, has erupted a diverse suite of high-K and shoshonitic lava types, with 48 to 76 wt% SiO2, over the last 3.6 million years. There is no correlation between the age and composition of the lavas. Three-quarters of the volcanic field consists of evolved (<4 wt% MgO) basaltic andesite and andesite lava cones and flows, the majority of which contain sparse, euhedral phenocrysts that are normally zoned; there is no evidence of mixed, hybrid magmas. The average eruption rate over this time period was ˜200 m3/km2/year, which is typical of continental arcs and an order of magnitude lower than that for the slow-spreading mid-Atlantic ridge. All of the Aurora lavas display a trace-element signature common to subduction-related magmas, as exemplified by Ba/Nb ratios between 52 and 151. Pre-eruptive water contents ranged from 1.5 wt% in plagioclase-rich two-pyroxene andesites to ˜6 wt% in a single hornblende lamprophyre and several biotite-hornblende andesites. Calculated oxygen fugacities fall within 0.4 and +2.4 log units of the Ni-NiO buffer. The Aurora potassic suite follows a classic, calc-alkaline trend in a plot of FeOT/MgO vs SiO2 and displays linear decreasing trends in FeOT and TiO2 with SiO2 content, suggesting a prominent role for Fe-Ti oxides during differentiation. However, development of the calc-alkaline trend through fractional crystallization of titanomagnetite would have caused the residual liquid to become so depleted in ferric iron that its oxygen fugacity would have fallen several log units below that of the Ni-NiO buffer. Nor can fractionation of hornblende be invoked, since it has the same effect as titanomagnetite in depleting the residual liquid in ferric iron, together with a thermal stability limit that is lower than the eruption temperatures of several andesites (˜1040 1080°C; derived from two-pyroxene thermometry). Unless some progressive

  7. The KLP-7 Residue S546 Is a Putative Aurora Kinase Site Required for Microtubule Regulation at the Centrosome in C. elegans

    PubMed Central

    Han, Xue; Adames, Kelly; Sykes, Ellen M. E.; Srayko, Martin

    2015-01-01

    Regulation of microtubule dynamics is essential for many cellular processes, including proper assembly and function of the mitotic spindle. The kinesin-13 microtubule-depolymerizing enzymes provide one mechanism to regulate microtubule behaviour temporally and spatially. Vertebrate MCAK locates to chromatin, kinetochores, spindle poles, microtubule tips, and the cytoplasm, implying that the regulation of kinesin-13 activity and subcellular targeting is complex. Phosphorylation of kinesin-13 by Aurora kinase inhibits microtubule depolymerization activity and some Aurora phosphorylation sites on kinesin-13 are required for subcellular localization. Herein, we determine that a C. elegans deletion mutant klp-7(tm2143) causes meiotic and mitotic defects that are consistent with an increase in the amount of microtubules in the cytoplasmic and spindle regions of meiotic embryos, and an increase in microtubules emanating from centrosomes. We show that KLP-7 is phosphorylated by Aurora A and Aurora B kinases in vitro, and that the phosphorylation by Aurora A is stimulated by TPXL-1. Using a structure-function approach, we establish that one putative Aurora kinase site, S546, within the C-terminal part of the core domain is required for the function, but not subcellular localization, of KLP-7 in vivo. Furthermore, FRAP analysis reveals microtubule-dependent differences in the turnover of KLP-7(S546A) and KLP-7(S546E) mutant proteins at the centrosome, suggesting a possible mechanism for the regulation of KLP-7 by Aurora kinase. PMID:26168236

  8. San Huang Decoction downregulates Aurora kinase A to inhibit breast cancer cell growth and enhance chemosenstivity to anti-tumor drugs.

    PubMed

    Xu, Yanlei; Chen, Xu; Chen, Xiyan; Bian, Weihe; Yao, Chang; Zhang, Xiaoqing; Zhu, Xiaoshu; Chen, Jiajing; Ye, Xiaozhou

    2016-08-01

    Our study aimed to explore whether San Huang Decoction (SHD) inhibited the development of breast cancer by regulating Aurora A. Human breast cancer cell lines MCF-7 and MDA-MB-231 were cultured and SHD extract was prepared. Cell growth assay and apoptosis analysis were respectively performed to detect the effects of SHD on breast cancer cells. In addition, the effects of SHD on the expression of Aurora A and p53 were determined by RT-PCR and western blot. Besides, we used Aurora A siRNA to knock down Aurora A. We then co-administrated SHD and tamoxifen or epirubicin to detect the effect of SHD on chemosensitivity to tamoxifen or epirubicin. SHD treatment significantly inhibited cell growth in a dose-dependent manner. Moreover, SHD treatment resulted in a marked decrease in Aurora A expression and obvious increase in p53 expression. In addition, knockdown of Aurora A induced cell growth inhibition, which was similar to the effect of SHD treatment. Besides, SHD exerted an additive effect on cell growth inhibition and apoptosis induction when breast cancer cells were co-administration of SHD with tamoxifen or epirubicin. Our study indicates that SHD treatment may inhibit cell growth and enhance chemosenstivity to other anti-tumor drugs in breast cancer via down-regulation of Aurora A. PMID:27461831

  9. In vitro and in vivo characterization of a benzofuran derivative, a potential anticancer agent, as a novel Aurora B kinase inhibitor.

    PubMed

    Xie, Fang; Zhu, Hengrui; Zhang, Haoxing; Lang, Qingyu; Tang, Lisha; Huang, Qiang; Yu, Long

    2015-01-01

    Aurora B is a serine/threonine kinase that has a key role in mitosis and is overexpressed in cancer cells. Aberrations in Aurora B are highly correlated with tumorigenesis and cancer development, so many studies have focused on the development of Aurora B kinase inhibitors. Based on one of our previous high-throughput screening studies, we identified lead compound S6, a small-molecule benzofuran derivative that binds Aurora B and inhibits its kinase activity in vitro. S6 also displayed high selectivity for Aurora B inhibition. The cytotoxicity of S6 was assessed against a panel of 21 cancer cell lines. The cervical cancer cell line HeLa, liver cancer cell line HepG2 and colon cancer cell line SW620 were the most sensitive to S6 treatment. We found that S6 decreased the proliferation and colony formation of these three cell lines and elevated their percentages of cells in the G2/M phase of the cell cycle. S6 also inhibited phospho-histone H3 on Ser 10, a natural biomarker of endogenous Aurora B activity. The growth suppression of liver cancer QGY-7401 xenograft tumors was observed in nude mice after S6 administration, and this effect was accompanied by the in vivo inhibition of phospho-histone H3 (Ser 10). Taken together, we conclude that targeting Aurora B with compound S6 may be a novel strategy for cancer treatment, and additional studies are warranted. PMID:25462247

  10. Cucurbitacin-I inhibits Aurora kinase A, Aurora kinase B and survivin, induces defects in cell cycle progression and promotes ABT-737-induced cell death in a caspase-independent manner in malignant human glioma cells

    PubMed Central

    Premkumar, Daniel R; Jane, Esther P; Pollack, Ian F

    2015-01-01

    Because STAT signaling is commonly activated in malignant gliomas as a result of constitutive EGFR activation, strategies for inhibiting the EGFR/JAK/STAT cascade are of significant interest. We, therefore, treated a panel of established glioma cell lines, including EGFR overexpressors, and primary cultures derived from patients diagnosed with glioblastoma with the JAK/STAT inhibitor cucurbitacin-I. Treatment with cucurbitacin-I depleted p-STAT3, p-STAT5, p-JAK1 and p-JAK2 levels, inhibited cell proliferation, and induced G2/M accumulation, DNA endoreduplication, and multipolar mitotic spindles. Longer exposure to cucurbitacin-I significantly reduced the number of viable cells and this decrease in viability was associated with cell death, as confirmed by an increase in the subG1 fraction. Our data also demonstrated that cucurbitacin-I strikingly downregulated Aurora kinase A, Aurora kinase B and survivin. We then searched for agents that exhibited a synergistic effect on cell death in combination with cucurbitacin-I. We found that cotreatment with cucurbitacin-I significantly increased Bcl-2/Bcl-xL family member antagonist ABT-737-induced cell death regardless of EGFR/PTEN/p53 status of malignant human glioma cell lines. Although >50% of the cucurbitacin-I plus ABT-737 treated cells were annexin V and propidium iodide positive, PARP cleavage or caspase activation was not observed. Pretreatment of z-VAD-fmk, a pan caspase inhibitor did not inhibit cell death, suggesting a caspase-independent mechanism of cell death. Genetic inhibition of Aurora kinase A or Aurora kinase B or survivin by RNA interference also sensitized glioma cells to ABT-737, suggesting a link between STAT activation and Aurora kinases in malignant gliomas. PMID:25482928

  11. Combined inhibition of MEK and Aurora A kinase in KRAS/PIK3CA double-mutant colorectal cancer models.

    PubMed

    Davis, S Lindsey; Robertson, Kelli M; Pitts, Todd M; Tentler, John J; Bradshaw-Pierce, Erica L; Klauck, Peter J; Bagby, Stacey M; Hyatt, Stephanie L; Selby, Heather M; Spreafico, Anna; Ecsedy, Jeffrey A; Arcaroli, John J; Messersmith, Wells A; Tan, Aik Choon; Eckhardt, S Gail

    2015-01-01

    Aurora A kinase and MEK inhibitors induce different, and potentially complementary, effects on the cell cycle of malignant cells, suggesting a rational basis for utilizing these agents in combination. In this work, the combination of an Aurora A kinase and MEK inhibitor was evaluated in pre-clinical colorectal cancer models, with a focus on identifying a subpopulation in which it might be most effective. Increased synergistic activity of the drug combination was identified in colorectal cancer cell lines with concomitant KRAS and PIK3CA mutations. Anti-proliferative effects were observed upon treatment of these double-mutant cell lines with the drug combination, and tumor growth inhibition was observed in double-mutant human tumor xenografts, though effects were variable within this subset. Additional evaluation suggests that degree of G2/M delay and p53 mutation status affect apoptotic activity induced by combination therapy with an Aurora A kinase and MEK inhibitor in KRAS and PIK3CA mutant colorectal cancer. Overall, in vitro and in vivo testing was unable to identify a subset of colorectal cancer that was consistently responsive to the combination of a MEK and Aurora A kinase inhibitor. PMID:26136684

  12. Combined inhibition of MEK and Aurora A kinase in KRAS/PIK3CA double-mutant colorectal cancer models

    PubMed Central

    Davis, S. Lindsey; Robertson, Kelli M.; Pitts, Todd M.; Tentler, John J.; Bradshaw-Pierce, Erica L.; Klauck, Peter J.; Bagby, Stacey M.; Hyatt, Stephanie L.; Selby, Heather M.; Spreafico, Anna; Ecsedy, Jeffrey A.; Arcaroli, John J.; Messersmith, Wells A.; Tan, Aik Choon; Eckhardt, S. Gail

    2015-01-01

    Aurora A kinase and MEK inhibitors induce different, and potentially complementary, effects on the cell cycle of malignant cells, suggesting a rational basis for utilizing these agents in combination. In this work, the combination of an Aurora A kinase and MEK inhibitor was evaluated in pre-clinical colorectal cancer models, with a focus on identifying a subpopulation in which it might be most effective. Increased synergistic activity of the drug combination was identified in colorectal cancer cell lines with concomitant KRAS and PIK3CA mutations. Anti-proliferative effects were observed upon treatment of these double-mutant cell lines with the drug combination, and tumor growth inhibition was observed in double-mutant human tumor xenografts, though effects were variable within this subset. Additional evaluation suggests that degree of G2/M delay and p53 mutation status affect apoptotic activity induced by combination therapy with an Aurora A kinase and MEK inhibitor in KRAS and PIK3CA mutant colorectal cancer. Overall, in vitro and in vivo testing was unable to identify a subset of colorectal cancer that was consistently responsive to the combination of a MEK and Aurora A kinase inhibitor. PMID:26136684

  13. Discovery of 7-aryl-substituted (1,5-naphthyridin-4-yl)ureas as aurora kinase inhibitors.

    PubMed

    Defaux, Julien; Antoine, Maud; Le Borgne, Marc; Schuster, Tilmann; Seipelt, Irene; Aicher, Babette; Teifel, Michael; Günther, Eckhard; Gerlach, Matthias; Marchand, Pascal

    2014-01-01

    As part of our research projects to identify new chemical entities of biological interest, we developed a synthetic approach and the biological evaluation of (7-aryl-1,5-naphthyridin-4-yl)ureas as a novel class of Aurora kinase inhibitors for the treatment of malignant diseases based on pathological cell proliferation. 1,5-Naphthyridine derivatives showed excellent inhibitory activities toward Aurora kinases A and B, and the most active compound, 1-cyclopropyl-3-[7-(1-methyl-1H-pyrazol-4-yl)-1,5-naphthyridin-4-yl]urea (49), displayed IC₅₀ values of 13 and 107 nM against Aurora kinases A and B, respectively. In addition, the selectivity toward a panel of seven cancer-related protein kinases was highlighted. In vitro ADME properties were also determined in order to rationalize the difficulties in correlating antiproliferative activity with Aurora kinase inhibition. Finally, the good safety profile of these compounds imparts promising potential for their further development as anticancer agents. PMID:24273104

  14. Spatiotemporal dynamics of Aurora B-PLK1-MCAK signaling axis orchestrates kinetochore bi-orientation and faithful chromosome segregation

    PubMed Central

    Shao, Hengyi; Huang, Yuejia; Zhang, Liangyu; Yuan, Kai; Chu, Youjun; Dou, Zhen; Jin, Changjiang; Garcia-Barrio, Minerva; Liu, Xing; Yao, Xuebiao

    2015-01-01

    Chromosome segregation in mitosis is orchestrated by the dynamic interactions between the kinetochore and spindle microtubules. The microtubule depolymerase mitotic centromere-associated kinesin (MCAK) is a key regulator for an accurate kinetochore-microtubule attachment. However, the regulatory mechanism underlying precise MCAK depolymerase activity control during mitosis remains elusive. Here, we describe a novel pathway involving an Aurora B-PLK1 axis for regulation of MCAK activity in mitosis. Aurora B phosphorylates PLK1 on Thr210 to activate its kinase activity at the kinetochores during mitosis. Aurora B-orchestrated PLK1 kinase activity was examined in real-time mitosis using a fluorescence resonance energy transfer-based reporter and quantitative analysis of native PLK1 substrate phosphorylation. Active PLK1, in turn, phosphorylates MCAK at Ser715 which promotes its microtubule depolymerase activity essential for faithful chromosome segregation. Importantly, inhibition of PLK1 kinase activity or expression of a non-phosphorylatable MCAK mutant prevents correct kinetochore-microtubule attachment, resulting in abnormal anaphase with chromosome bridges. We reason that the Aurora B-PLK1 signaling at the kinetochore orchestrates MCAK activity, which is essential for timely correction of aberrant kinetochore attachment to ensure accurate chromosome segregation during mitosis. PMID:26206521

  15. 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

  16. Scientific Rationale Supporting the Clinical Development Strategy for the Investigational Aurora A Kinase Inhibitor Alisertib in Cancer

    PubMed Central

    Niu, Huifeng; Manfredi, Mark; Ecsedy, Jeffrey A.

    2015-01-01

    Alisertib (MLN8237) is a selective small molecule inhibitor of Aurora A kinase that is being developed in multiple cancer indications as a single agent and in combination with other therapies. A significant amount of research has elucidated a role for Aurora A in orchestrating numerous activities of cells transiting through mitosis and has begun to shed light on potential non-mitotic roles for Aurora A as well. These biological insights laid the foundation for multiple clinical trials evaluating the antitumor activity of alisertib in both solid cancers and heme-lymphatic malignancies. Several key facets of Aurora A biology as well as empirical data collected in experimental systems and early clinical trials have directed the development of alisertib toward certain cancer types, including neuroblastoma, small cell lung cancer, neuroendocrine prostate cancer, atypical teratoid/rhabdoid tumors, and breast cancer among others. In addition, these scientific insights provided the rationale for combining alisertib with other therapies, including microtubule perturbing agents, such as taxanes, EGFR inhibitors, hormonal therapies, platinums, and HDAC inhibitors among others. Here, we link the key aspects of the current clinical development of alisertib to the originating scientific rationale and provide an overview of the alisertib clinical experience to date. PMID:26380220

  17. Evaluation of the Impact of the 2003 Aurora Leadership Institute--"The Gift That Keeps on Giving"

    ERIC Educational Resources Information Center

    Barney, Kay

    2004-01-01

    As a generation of library leaders in Australia and New Zealand is approaching retirement, the question is "who will take their place?" Leadership programs have become increasingly popular as a way to "grow" future leaders for the profession. This study looks at the impact of the 2003 Aurora Leadership Institute [A6] on participants and mentors:…

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

    PubMed

    Platani, Melpomeni; Trinkle-Mulcahy, Laura; Porter, Michael; Jeyaprakash, A Arockia; Earnshaw, William C

    2015-07-01

    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

  19. 78 FR 23318 - Trust for Professional Managers and Aurora Investment Management L.L.C.; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-18

    ... COMMISSION Trust for Professional Managers and Aurora Investment Management L.L.C.; Notice of Application... application under section 6(c) of the Investment Company Act of 1940 (``Act'') for an exemption from section... Management L.L.C. (the ``Initial Advisor''). Filing Dates: The application was filed January 17, 2013,...

  20. Analysis of electron auroras based on the Monte Carlo method: Application to active electron arc auroras observed by the sounding rocket at Syowa Station

    NASA Astrophysics Data System (ADS)

    Onda, Kunizo; Ejiri, Masaki; Itikawa, Yukikazu

    A downward electron differential number flux, the absolute photoemission rate for the (0, 1) band of the first negative band system of the molecular nitrogen ion, and the number density of thermal electrons were simultaneously measured by the sounding rocket S-310JA-8 launched toward active auroral arcs at a substorm expansion phase on April 4, 1984, from Syowa Station in Antarctica. We apply the Monte Carlo method to analyze these observed results. The MSIS-86 model is employed to represent the atmospheric number density and temperature in the aurora observed by this experiment. Only N2, O, and O2 are taken into account as constituent elements of the atmosphere. Electrons are injected downward into the upper atmosphere at the altitude of 200 km, at which the downward electron differential number flux was measured. An initial electron energy is considered in the range of 0.1-18 keV. It is assumed that an initial pitch angle is uniformly distributed in the range of [0, π/2]. Excitation and ionization rates of N2, O, and O2 are calculated as a function of altitude, the initial pitch angle, and the initial electron energy. Production and emission rates of the N2+ 1N (0, 1) band are deduced by using these calculated rates. Time variation of the observed absolute intensity of this band is reasonably well reproduced by the Monte Carlo method combined with the measured electron number flux.