A mutation in the spindle checkpoint arresting meiosis II in Brachiaria ruziziensis

Genome ◽  
2003 ◽  
Vol 46 (4) ◽  
pp. 724-728 ◽  
Author(s):  
Claudicéia Risso-Pascotto ◽  
Maria Suely Pagliarini ◽  
Cacilda Borges do Valle
Keyword(s):  
Nuclear Envelope ◽  
Spindle Checkpoint ◽  
Low Frequency ◽  
Early Prophase ◽  
Late Prophase ◽  
Brachiaria Ruziziensis ◽  
Sister Chromatids ◽  
Wide Range

Cytological characterization of BRA005568 accession of Brachiaria ruziziensis (2n = 2x = 18) showed a totally unexpected high frequency of abnormal meiotic products, from triads to hexads, and also tetrads with micro nuclei or microcytes. Meiosis I had a low frequency of abnormalities, mainly related to the chiasma terminalization process. In meiosis II, however, frequency of abnormalities increased exceptionally. Early prophase II was normal with the chromosome set enclosed by the nuclear envelope. However, in late prophase II, owing to the breakdown of the nuclear envelope, the chromosomes were scattered in the cytoplasm. Some chromosomes did not reach the metaphase II plate and remained scattered. The behavior of sister cells was inconsistent. While in one cell the chromosomes were totally aligned at the metaphase II plate, in the other they could be found completely scattered, leading to an asynchronous cell division. Cells with scattered chromosomes were unable to progress in meiosis. Thus, anaphase II failed to occur and sister chromatids were not released. Cells with non-aligned chromosomes in the metaphase II plate did not receive the "go ahead" sign to initiate anaphase II. Consequently, the scattered chromosomes produced telophase II nuclei of different sizes in situ. The asynchronous behavior led to the formation of a wide range of meiotic products. Results suggest that the present accession contains a mutation affecting the spindle checkpoint that arrests the second meiotic division.Key words: Brachiaria ruziziensis, meiosis II, microsporogenesis, mutation, spindle checkpoint.

scholarly journals X-Ray Fluorescence Analysis of a Gold Ibex and other Artifacts from Akrotiri

2019 ◽  
Vol 11 ◽  
Author(s):  
A. G. Karydas ◽  
T. Pantazis ◽  
C. Doumas ◽  
A. Vlachopoulos ◽  
P. Nomikos ◽  
...  
Keyword(s):  
Bulk Composition ◽  
Fluorescence Analysis ◽  
Wall Painting ◽  
Inorganic Elements ◽  
X Ray ◽  
Wide Range ◽  
Soldering Technology ◽  
Excavation Area

In-situ X-ray fluorescence analysis (XRF) of ancient artifacts from the excavation area was performed using a novel X-ray instrumentation, composed of a portable silicon PIN thermoelectrically cooled X-ray detector, a miniature X-ray source, and portable data acquisition devices. The main objective of the analyses in Akrotiri was to explore the potential of the technique to provide answers to a wide range of archaeometric questions regarding the bulk composition of metal alloys, especially of gold, the characterization of corrosion products in bronze artifacts, identification of inorganic elements which are fingerprints of the minerals used in wall-painting pigments, and of the painting materials and techniques used for the decoration of clay vase surfaces. Among the analysed artifacts are a unique gold ibex, a bronze dagger and blade, various pigments from the wall paintings of room 3 in Xeste 3, decoration pigments from rosettes of faience, a bichrome jug, and other clay vases. The results of the in-situ XRF survey, primarily those of the bulk composition and soldering technology of the gold ibex, are discussed and compared with literature.

scholarly journals Comparison of Above-Water Seabird and TriOS Radiometers along an Atlantic Meridional Transect

2020 ◽  
Vol 12 (10) ◽  
pp. 1669
Author(s):  
Krista Alikas ◽  
Viktor Vabson ◽  
Ilmar Ansko ◽  
Gavin H. Tilstone ◽  
Giorgio Dall’Olmo ◽  
...  
Keyword(s):  
State Of The Art ◽  
Ocean Color ◽  
Percentage Difference ◽  
Wide Range ◽  
Before And After ◽  
Reference Measurements ◽  
Satellite Ocean Color ◽  
Good Agreement

The Fiducial Reference Measurements for Satellite Ocean Color (FRM4SOC) project has carried out a range of activities to evaluate and improve the state-of-the-art in ocean color radiometry. This paper described the results from a ship-based intercomparison conducted on the Atlantic Meridional Transect 27 from 23rd September to 5th November 2017. Two different radiometric systems, TriOS-Radiation Measurement Sensor with Enhanced Spectral resolution (RAMSES) and Seabird-Hyperspectral Surface Acquisition System (HyperSAS), were compared and operated side-by-side over a wide range of Atlantic provinces and environmental conditions. Both systems were calibrated for traceability to SI (Système international) units at the same optical laboratory under uniform conditions before and after the field campaign. The in situ results and their accompanying uncertainties were evaluated using the same data handling protocols. The field data revealed variability in the responsivity between TRiOS and Seabird sensors, which is dependent on the ambient environmental and illumination conditions. The straylight effects for individual sensors were mostly within ±3%. A near infra-red (NIR) similarity correction changed the water-leaving reflectance (ρw) and water-leaving radiance (Lw) spectra significantly, bringing also a convergence in outliers. For improving the estimates of in situ uncertainty, it is recommended that additional characterization of radiometers and environmental ancillary measurements are undertaken. In general, the comparison of radiometric systems showed agreement within the evaluated uncertainty limits. Consistency of in situ results with the available Sentinel-3A Ocean and Land Color Instrument (OLCI) data in the range from (400…560) nm was also satisfactory (−8% < Mean Percentage Difference (MPD) < 15%) and showed good agreement in terms of the shape of the spectra and absolute values.

scholarly journals Applications with a brighter X-ray source and new detectors from Agilent

2014 ◽  
Vol 70 (a1) ◽  
pp. C1734-C1734
Author(s):  
Zoltan Gal ◽  
Tadeusz Skarzynski ◽  
Fraser White ◽  
Oliver Presly ◽  
Adrian Jones ◽  
...  
Keyword(s):  
Data Quality ◽  
Single Crystal ◽  
Measurement System ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Vacuum Technology ◽  
Intelligent Measurement ◽  
Wide Range

Agilent Technologies develop and supply X-ray systems for single-crystal diffraction research, including the SuperNova; a compact, highly reliable and very low maintenance instrument providing X-ray data of the highest quality; and the PX Scanner for testing and characterization of protein crystals in their original crystallization drops (in-situ). The SuperNova and PX Scanner are constantly improving, with recent enhancements including a new range of detectors using an Intelligent Measurement System. The Eos S2, Atlas S2 and Titan S2 detector range employs a smart sensitivity control of the electronic gain and is capable of instantaneously switching its binning modes thus providing unprecedented flexibility in tuning every exposure to provide the highest data quality for a wide range of experiments. We have also developed a completely new micro-focus X-ray source based on Gradient Vacuum technology, with novel filament and target designs. This novel source is an integral part of the new Agilent GV1000 X-ray diffractometer, which has been designed for applications that require even higher brightness of the X-ray beam.

Aberration correction: zooming out to overview

2009 ◽  
Vol 367 (1903) ◽  
pp. 3859-3870 ◽  
Author(s):  
A. Howie
Keyword(s):  
Materials Science ◽  
Complex Structure ◽  
Chromatic Aberration ◽  
Aberration Correction ◽  
Contrast Imaging ◽  
Atomic Column ◽  
Wide Range ◽  
The Many

In the structural characterization of thin specimens by projection (atomic column) imaging, the revolutionary development of aberration-corrected electron microscopy has already brought significant improvements not only in spatial resolution but also in improved image contrast. Some highlights from the symposium are summarized. Despite the purchasing and operating costs as well as the demands they place on operator skills, a staggering number of these new microscopes has already been installed worldwide. Serious challenges, therefore, arise including the need to attract customers from a wide range of disciplines where complex structure problems may require the development of new imaging modes. The ability to image at large scattering angles may be useful in mitigating some of the many as-yet uncorrected delocalization mechanisms that then arise and are systematically identified here. Larger specimen volumes made possible by chromatic aberration correction will benefit the development of more relevant in situ observations, particularly in materials science and catalysis. With additional incorporation of phase shifting electrodes or other devices, these chromatic aberration correctors could also be important for efficient phase contrast imaging in easily damaged biological structures. For many of these formidable problems, earlier experience of the optical microscopy community may teach some lessons.

Particle Size Measurement in Optical Waveguide Manufacturing Torches Using Dynamic Light Scattering

1988 ◽  
Vol 117 ◽  
Author(s):  
J. R. Bautista ◽  
Eugene Potkay ◽  
Daria L. Scatton
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Optical Waveguide ◽  
Low Frequency ◽  
Correlation Spectroscopy ◽  
Industrial Systems ◽  
Deposition Processes ◽  
Flame Hydrolysis Deposition

AbstractThe characterization of silica “sooting” torches used in optical waveguide manufacture by external flame-hydrolysis deposition processes such as Outside Vapor Deposition (OVD) and Vapor-phase Axial Deposition (VAD) prflents a formid.ble high temperature environment at > 2000°C in the presence of > 1012 particles/cm3 of silica. This paper describes the first application of Dynamic Light Scattering (DLS) to probe particle sizes in an actual lightguide burner following the “triple-flame” VAD design. DLS, also termed Photon Correlation Spectroscopy (PCS) or Diffusion Broadening Spectroscopy (DBS), was previously identified as a viable diagnostic tool for in-situ particle measurements in silica-sooting flames by W. L. Flower [1] and through an earlier collaboration between AT&T and the Sandia Combustion Research Facility. In applying DLS, however, our experience with the VAD torch reveals that a specialized experimental method will undoubtedly be required to deal with the inevitable presence of low frequency system instabilities in industrial systems.

Memoirs: The Structure of the Somatic Chromosomes of Alstroemeria and Bomarea

1934 ◽  
Vol s2-77 (305) ◽  
pp. 49-75
Author(s):  
FRANK W. JANE
Keyword(s):  
Early Prophase ◽  
Botanic Gardens ◽  
Botanic Garden ◽  
Metaphase Chromosomes ◽  
Birkbeck College ◽  
Late Prophase ◽  
Sister Chromatids ◽  
Spiral Form ◽  
Friendly Criticism ◽  
The University

1. Investigations have been made on the chromatin throughout mitosis in Alstroemeria and Bomarea, and an attempt has been made to interpret the observations. 2. Anaphase chromosomes contain single or double spirals and often chromomeres. The spiral chromonemata are held to arise from the chromomeres. 3. The resting reticulum is formed partly from the remains of the spirals, partly from the telophasic anastomoses between adjacent chromosomes. The chromomeres form the net-knots. 4. The spiral chromosomes seen in early prophase are not regarded as homologous with the anaphase chromonema. It is not certain that all the chromosomes of a nucleus assume the spiral form during prophase. 5. The paired chromatids arise during prophase by the connecting up of adjacent daughter chromomeres into two strips of chromatin. The chromosomes do not split longitudinally at any stage. 6. Connexions between the sister chromatids are regarded as remnants of the chromonema of the previous anaphase. In this respect the interpretation agrees with Martens theory of bilateral repartition. 7. Chromomeres appear in prophase as the chromatids emerge from the spiral stage. They cease to be visible in late prophase as the chromatids thicken and become densely chromatic. 8. Prolonged destaining of the early metaphase chromosomes shows that the chromomeres are still present. Each has divided to form two daughter chromomeres. Between the chromomeres on opposite sides of the chromatid appear connexions, the new chromonema. This investigation was begun at Birkbeck College, University of London, while I was the recipient of a maintenance grant from the Department of Scientific and Industrial Research. My thanks are due to the Trustees of the Dixon Fund for the loan of a suitable microscope; to the Directors of the Eoyal Botanic Gardens, Kew, the Chelsea Physic Garden, and the University Botanic Garden, Cambridge, for material; and especially to Professor Dame Helen Gwynne-Vaughan, under whose direction the work was carried out and who has encouraged me with friendly criticism and advice.

scholarly journals Direct Immunosensor Design Based on the Electrochemical Reduction of 4-((4-Nitrophenyl)ethynyl)benzenethiol Monolayers

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Dwight A. Williams ◽  
Wraegen A. M. Williams ◽  
Melissa C. Rhoten ◽  
Charlene D. Crawley ◽  
Suzanne Ruder
Keyword(s):  
Maximal Activity ◽  
Molecular Wires ◽  
Covalent Immobilization ◽  
Igg Antibodies ◽  
Cyclic Voltammetric ◽  
Electrode Surfaces ◽  
Antibody Binding Site ◽  
Wide Range

The synthesis and characterization of novel N-arylhydroxylamine-based molecular wires are described for use in the site-directed covalent immobilization of whole IgG antibodies onto gold electrode surfaces. The hydroxylamine, electrochemically generated in situ from reduction of the corresponding nitrobenzene, is stable under a wide range of solution conditions and reacts selectively with carbohydrate away from the antibody-binding site to allow the development of immunosensors with maximal activity. Cyclic voltammetric responses have shown a direct correlation between the structure and length of the molecular wire and its stability and concentration at the electrode surface.

Preliminary results from interdisciplinary fault characterization in the Bedretto Underground Laboratory

2020 ◽  
Author(s):  
Alexis Shakas ◽  
Hannes Krietsch ◽  
Marian Hertrich ◽  
Nima Gholizadeh ◽  
Katrin Plenkers ◽  
...  
Keyword(s):  
Rock Mass ◽  
Fracture Zone ◽  
Geothermal Energy ◽  
Swiss Alps ◽  
Underground Laboratory ◽  
Data Sets ◽  
Remote Imaging ◽  
Wide Range

&lt;p&gt;Engineered Geothermal Systems (EGS) are gaining increasing popularity as a source of renewable energy without significant CO2 emissions. Fractured crystalline rock masses offer a promising environment for exploitation of geothermal energy. In such a setting, fractures and faults are the main conduits for fluid flow and heat transport. In-situ fracture permeabilities are usually too low at depths where rock mass temperatures are sufficiently high for geothermal energy production. Therefore, a suitable heat exchanger needs to be engineered by hydraulic stimulations. A proper in-situ characterization of the fracture geometry and hydro-mechanical properties is of primary importance for the design of the stimulation operations. This is often the most challenging task, since the majority of the fractures in the reservoir are usually inaccessible for direct characterization.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;The Bedretto Underground Laboratory for Geosciences (BULG) provides a novel and unique environment to study EGS-related processes, such as seismo-hydro-mechanical fault zone response during hydraulic stimulation and subsequent fluid circulation experiments. The laboratory is hosted in an access tunnel from the Bedretto Valley in the Southern Swiss Alps to a railway tunnel from the Matterhorn-Gotthard-Bahn. The overburden of more than 1000 m above the BULG provides conditions that are approaching those of realistic EGS systems. For the rock mass characterization, three boreholes were drilled perpendicular to tunnel axis with lengths ranging from 190 m to 300 m.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We present first data sets from a variety of methodologies, ranging from hydrological tests to geophysical borehole- and remote-imaging. The complementary nature of these data sets allows us to construct a preliminary three dimensional geological model. Notably, the individual measurements yielded information over a multitude of scales, ranging from millimeter-scale core-log information to decameter scale low-frequency Ground Penetrating Radar measurements. Such a wide range of scales is critical for the characterization of EGS reservoirs. The most prominent feature found is a large-scale fracture zone that extends across the entire investigation volume. This fracture zone will be the target for upcoming stimulation experiments.&lt;/p&gt;

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