Direct determination of the effects of genotype and extreme temperature on the transposition of roo in long-term mutation accumulation lines of Drosophila melanogaster

SummaryRates of transposition and excision of the Drosophila melanogaster retrotransposon elements mdg3, 297, Doc, roo and copia were estimated directly, by in situ hybridization analysis of their cytological insertion sites in 31 replicates of a highly inbred line that had accumulated spontaneous mutations for approximately 160generations. Estimated transposition rates of Doc, roo and copia were, respectively, 4·2 × 10−5, 3·1 × 10−3 and 1·3 − 10−3; no transpositions of 297 nor mdg3 were observed. Rates of transposition of copia varied significantly among sublines. Excisions were only observed for roo elements, at a rate of 9·0 × 10−6 per element per generation. Copy number averaged over these element families increased 5·9 %; therefore, in these lines the magnitude of the forces opposing transposable element multiplication were weaker than transposition rates.

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National Mapping’s Astro-Geodetic Complex

Publications of the Astronomical Society of Australia ◽

10.1017/s132335800001359x ◽

1973 ◽

Vol 2 (4) ◽

pp. 203-206

Author(s):

J. McK. Luck ◽

M. J. Miller ◽

P. J. Morgan

Keyword(s):

Air Force ◽

Continental Drift ◽

Direct Determination ◽

Lunar Laser Ranging ◽

Plate Movement ◽

Cambridge Research ◽

Lunar Laser ◽

Lunar Ephemeris

The Division of National Mapping has received, on long term loan from NASA and in co-operation with the Smithsonian Astrophysical Observatory, a Lunar Laser Ranging instrument consisting of a gigawatt pulsed ruby laser, a 150 cm aspheric Ritchey-Chretien telescope, and associated electronic equipment. The instrument was formerly operated by the Air Force Cambridge Research Laboratories at Mount Lemmon in Arizona. Its principal use by National Mapping will be direct determination of the distance between the telescope and any of the three retro-reflector arrays placed on the Moon at Hadley’s Rille, Fra Mauro and Mare Tranquillitatis by Apollo astronauts. Full scale operation in conjunction with similar instruments well separated in latitude and longitude, in particular at Mount McDonald in Texas and Mount Haleakala in Hawaii, will permit determination of Earth rotation and polar motion, lunar ephemeris and libration, and tectonic plate movement or continental drift, which justifies its use in a geodetic environment.

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Rates of movement of transposable elements on the second chromosome of Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672399004474 ◽

2000 ◽

Vol 75 (3) ◽

pp. 275-284 ◽

Cited By ~ 43

Author(s):

XULIO MASIDE ◽

STAVROULA ASSIMACOPOULOS ◽

BRIAN CHARLESWORTH

Keyword(s):

Drosophila Melanogaster ◽

Transposable Elements ◽

Polytene Chromosomes ◽

Mutation Accumulation ◽

Long Terminal Repeats ◽

Significant Difference ◽

Transposable Element Copy ◽

Excision Rate

The rates of movement of 11 families of transposable elements of Drosophila melanogaster were studied by means of in situ hybridization of probes to polytene chromosomes of larvae from a long-term mutation accumulation experiment. Replicate mutation-accumulation lines carrying second chromosomes derived from a single common ancestral chromosome were maintained by backcrosses of single males heterozygous for a balancer chromosome and a wild-type chromosome, and were scored after 116 generations. Twenty-seven transpositions and 1 excision were detected using homozygous viable and fertile second chromosomes, for a total of 235056 potential sources of transposition events and a potential 252880 excision events. The overall transposition rate per element per generation was 1·15×10−4 and the excision rate was 3·95×10−6. The single excision (of a roo element) was due to recombination between the element's long terminal repeats. A survey of the five most active elements among nine homozygous lethal lines revealed no significant difference in the estimates of transposition and excision rates from those from viable lines. The excess of transposition over excision events is in agreement with the results of other in situ hybridization experiments, and supports the conclusion that replicative increase in transposable element copy number is opposed by selection. These conclusions are compared with those from other studies, and with the conclusions from population surveys of element frequencies.

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Visibility study of Galileo satellites from a VLBI network

10.5194/egusphere-egu21-5824 ◽

2021 ◽

Author(s):

Helene Wolf ◽

Johannes Böhm ◽

Matthias Schartner ◽

Urs Hugentobler

Keyword(s):

Reference Frames ◽

Direct Determination ◽

Satellite Constellation ◽

Long Baseline ◽

Space Geodetic Techniques ◽

Satellite Scheduling ◽

Observation Geometry ◽

The Impact

<p>Over the last years, ideas have been proposed to install a Very Long Baseline Interferometry (VLBI) transmitter on one or more satellites of the Galileo constellation. Satellites transmitting signals that can be observed by VLBI telescopes provide the opportunity of extending the current VLBI research with observations to geodetic satellites. These observations offer a variety of new possibilities such as high precision tying of space geodetic techniques but also the direct determination of the absolute orientation of the satellite constellation with respect to the International Celestial Reference Frame (ICRF) and have implications on the determination of long-term reference frames.&#160;</p><p>This contribution provides a visibility study of the Galileo satellites from a VLBI network. The newly developed satellite scheduling module in VieSched++ is used to determine the time periods during which a satellite is observable from a VLBI network. The possible satellite observations are evaluated through the number of stations from which a satellite is observable. Moreover, the impact on determining the orientation of the satellite constellation, caused by the observation geometry, is investigated with using the UT1-UTC Dilution of Precision (UDOP) factor.</p>

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New optical sensor based on the immobilization of a triazene ligand in PVC membrane for Hg(II) ion

Journal of the Serbian Chemical Society ◽

10.2298/jsc160520093s ◽

2017 ◽

Vol 82 (3) ◽

pp. 317-328

Author(s):

Homa Shafiekhani ◽

Fahimeh Nezam ◽

Shahriyar Bahar

Keyword(s):

Optical Sensor ◽

Dynamic Range ◽

Direct Determination ◽

Pvc Membrane ◽

Sensing Element ◽

Wide Dynamic Range ◽

Optode Membrane ◽

Term Response

This paper describes the development and creation of a new sensitive optical sensor that is quite selective to Hg(II) ions in aqueous solution. The sensing element, the newly synthesized methyl 2-[3-(3-methylphenyl)-2-triazen- 1-yl]benzoate, incorporated into a plasticized poly(vinyl chloride) membrane, is able to determine Hg(II) ion with a high selectivity over a wide dynamic range from 5.0?115.1 ?g L-1 at pH 7.5 with a lower detection limit of 0.67 ?g L-1. The response of the optode membrane to Hg(II) was fully reversible and revealed a very good selectivity towards Hg(II) ion from a wide variety of other metal ions in solution. The overall performance characteristics of the sensor were evaluated and good reversibility, wide dynamic range, long life span, long-term response stability and high reproducibility were found. The proposed optical sensor gives proper results in applications including direct determination of the Hg(II) ion in real environmental samples.

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Long-term evolution of the roo transposable element copy number in mutation accumulation lines of Drosophila melanogaster

Genetics Research ◽

10.1017/s0016672311000103 ◽

2011 ◽

Vol 93 (3) ◽

pp. 181-187 ◽

Cited By ~ 7

Author(s):

JULIA DÍAZ-GONZÁLEZ ◽

J. FERNANDO VÁZQUEZ ◽

JESÚS ALBORNOZ ◽

ANA DOMÍNGUEZ

Keyword(s):

Drosophila Melanogaster ◽

De Novo ◽

Accumulation Rate ◽

Mutation Accumulation ◽

Fundamental Parameter ◽

Highly Active ◽

Transposition Rate ◽

Transposable Element Copy

SummaryThe rate of insertion of transposable elements (TEs) is a fundamental parameter to understand both their dynamics and role in the evolution of the eukaryotic genome. Nonetheless, direct estimates of insertion rates are scarce because transposition is in general a rare phenomenon. A great deal of our previous work on transposition was based on a set of long-term mutation accumulation (MA) lines of Drosophila melanogaster started in 1987 (Oviedo lines), where roo was found highly active, with a rate of insertion of 7×10−4 insertions per element and generation, as compared with other 15 TE families that presented transposition rates around 10−5. Here, we study the evolution of the roo transposition rate, by in situ hybridization, after 60–75 additional generations of MA in two subsets of the Oviedo lines, O and O′, which had achieved average numbers of roo insertions of 77 and 84, respectively. In the O lines, insertions accumulated at a rate that remained constant (7×10−4 insertions per element and generation); however, the subset of lines O′ showed a lower accumulation rate of 4×10−4 insertions per element per generation, suggesting a regulation of transposition that depends on the number of elements. However, one of the O′ lines reached a number of 103 insertions, departing from the group mean by 4·6 sd, and showing that it escapes regulation. Hence, ‘de novo’ mutations affecting the regulation of transposition are relatively common. These results are discussed in relation to the possible mechanisms of containment of TEs.

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Preparation And elemental analysis of ancient fibers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126846 ◽

1987 ◽

Vol 45 ◽

pp. 410-411

Author(s):

Allen Angel ◽

Kathryn A. Jakes

Keyword(s):

Cross Sections ◽

Physical Structure ◽

Energy Dispersive ◽

Archaeological Sites ◽

X Ray ◽

Long Term Storage ◽

Backscattered Electron ◽

Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

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