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  • 1
    Publication Date: 2011-03-09
    Description: Transporters of the amino acid, polyamine and organocation (APC) superfamily play essential roles in cell redox balance, cancer, and aminoacidurias. The bacterial L-arginine/agmatine antiporter, AdiC, is the main APC structural paradigm and shares the “5 + 5 inverted repeat” fold found in other families like the Na+-coupled neurotransmitter transporters. The available AdiC crystal structures capture two states of its transport cycle: the open-to-out apo and the outward-facing Arg+-bound occluded. However, the role of Arg+ during the transition between these two states remains unknown. Here, we report the crystal structure at 3.0 Å resolution of an Arg+-bound AdiC mutant (N101A) in the open-to-out conformation, completing the picture of the major conformational states during the transport cycle of the 5 + 5 inverted repeat fold-transporters. The N101A structure is an intermediate state between the previous known AdiC conformations. The Arg+-guanidinium group in the current structure presents high mobility and delocalization, hampering substrate occlusion and resulting in a low translocation rate. Further analysis supports that proper coordination of this group with residues Asn101 and Trp293 is required to transit to the occluded state, providing the first clues on the molecular mechanism of substrate-induced fit in a 5 + 5 inverted repeat fold-transporter. The pseudosymmetry found between repeats in AdiC, and in all fold-related transporters, restraints the conformational changes, in particular the transmembrane helices rearrangements, which occur during the transport cycle. In AdiC these movements take place away from the dimer interface, explaining the independent functioning of each subunit.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 426-432 (Aug. 2003), p. 1517-1522 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2011-10-15
    Description: Reflectometry using Global Navigation Satellite Systems signals (GNSSR) has been the focus of many studies during the past few years for a number of applications over different scenarios as land, ocean or snow and ice surfaces. In the past decade, its potential has increased yearly, with improved receivers and signal processors, from generic GNSS receivers whose signals were recorded in magnetic tapes to instruments that measure full Delay Doppler Maps (the power distribution of the reflected GNSS signal over the 2-D space of delay offsets and Doppler shifts) in real time. At present, these techniques are considered to be promising tools to retrieve geophysical parameters such as soil moisture, vegetation height, topography, altimetry, sea state and ice and snow thickness, among others. This paper focuses on the land geophysical retrievals (topography, vegetation height and soil moisture) performed from a ground-based instrument using the Interference Pattern Technique (IPT). This technique consists of the measurement of the power fluctuations of the interference signal resulting from the simultaneous reception of the direct and the reflected GNSS signals. The latest experiment performed using this technique over a maize field is shown in this paper. After a review of the previous results, this paper presents the latest experiment performed using this technique over a maize field. This new study provides a deeper analysis on the soil moisture retrieval by observing three irrigation-drying cycles and comparing them to different depths soil moisture probes. Furthermore, the height of the maize, almost 300 cm, has allowed testing the capabilities of the technique over dense and packed vegetation layers, with high vegetation water content.
    Print ISSN: 0048-6604
    Electronic ISSN: 1944-799X
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Publication Date: 2011-09-24
    Description: Reflectometry using GNSS signals of opportunity (GNSS-R) has stood as a powerful technique for ocean remote sensing. Particularly, the use of these techniques has been proposed to retrieve sea state information (i.e. sea surface roughness) among other applications. Precise knowledge of the sea state is a key issue to process L-band radiometric measurements for sea surface salinity retrieval. It has been recently shown that GNSS-R data can be directly linked to the brightness temperature variations caused by the sea state effect, without the use of emission/scattering models or sea spectra models. In this study, this approach is applied to CoSMOS 2007 flights data. Firstly, the radiometric and GNSS-R data sets are presented. Secondly, measured brightness temperature is corrected using the collocated GNSS-R data. In particular, the area under the normalized waveforms is used to directly compute the required brightness temperature correction. Thirdly, the salinity retrievals are presented (achieving an error reduction from 2.8 psu for the raw measurements down to 0.51 psu). Finally, the obtained results are compared with the WISE correction approach, based on the wind speed correction, and the conclusions of this work are presented.
    Print ISSN: 0048-6604
    Electronic ISSN: 1944-799X
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
    Publication Date: 2013-11-01
    Description: The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humid ecosystems (drylands) because their biological activity is mainly driven by water availability. The increase in aridity predicted for the twenty-first century in many drylands worldwide may therefore threaten the balance between these cycles, differentially affecting the availability of essential nutrients. Here we evaluate how aridity affects the balance between C, N and P in soils collected from 224 dryland sites from all continents except Antarctica. We find a negative effect of aridity on the concentration of soil organic C and total N, but a positive effect on the concentration of inorganic P. Aridity is negatively related to plant cover, which may favour the dominance of physical processes such as rock weathering, a major source of P to ecosystems, over biological processes that provide more C and N, such as litter decomposition. Our findings suggest that any predicted increase in aridity with climate change will probably reduce the concentrations of N and C in global drylands, but increase that of P. These changes would uncouple the C, N and P cycles in drylands and could negatively affect the provision of key services provided by these ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Delgado-Baquerizo, Manuel -- Maestre, Fernando T -- Gallardo, Antonio -- Bowker, Matthew A -- Wallenstein, Matthew D -- Quero, Jose Luis -- Ochoa, Victoria -- Gozalo, Beatriz -- Garcia-Gomez, Miguel -- Soliveres, Santiago -- Garcia-Palacios, Pablo -- Berdugo, Miguel -- Valencia, Enrique -- Escolar, Cristina -- Arredondo, Tulio -- Barraza-Zepeda, Claudia -- Bran, Donaldo -- Carreira, Jose Antonio -- Chaieb, Mohamed -- Conceicao, Abel A -- Derak, Mchich -- Eldridge, David J -- Escudero, Adrian -- Espinosa, Carlos I -- Gaitan, Juan -- Gatica, M Gabriel -- Gomez-Gonzalez, Susana -- Guzman, Elizabeth -- Gutierrez, Julio R -- Florentino, Adriana -- Hepper, Estela -- Hernandez, Rosa M -- Huber-Sannwald, Elisabeth -- Jankju, Mohammad -- Liu, Jushan -- Mau, Rebecca L -- Miriti, Maria -- Monerris, Jorge -- Naseri, Kamal -- Noumi, Zouhaier -- Polo, Vicente -- Prina, Anibal -- Pucheta, Eduardo -- Ramirez, Elizabeth -- Ramirez-Collantes, David A -- Romao, Roberto -- Tighe, Matthew -- Torres, Duilio -- Torres-Diaz, Cristian -- Ungar, Eugene D -- Val, James -- Wamiti, Wanyoike -- Wang, Deli -- Zaady, Eli -- England -- Nature. 2013 Oct 31;502(7473):672-6. doi: 10.1038/nature12670.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Departamento de Sistemas Fisicos, Quimicos y Naturales, Universidad Pablo de Olavide, Carretera de Utrera, kilometro 1, 41013 Sevilla, Spain [2] Area de Biodiversidad y Conservacion, Departamento de Biologia y Geologia, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, Calle Tulipan Sin Numero, 28933 Mostoles, Spain.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24172979" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Silicates/analysis ; Biomass ; Carbon/analysis/metabolism ; Carbon Cycle ; Climate Change ; *Desert Climate ; *Desiccation ; *Ecosystem ; *Geography ; Models, Theoretical ; Nitrogen/analysis/metabolism ; Nitrogen Cycle ; Phosphoric Monoester Hydrolases/analysis/metabolism ; Phosphorus/analysis/metabolism ; Plants/metabolism ; Soil/*chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2012-01-17
    Description: Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3558739/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3558739/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Maestre, Fernando T -- Quero, Jose L -- Gotelli, Nicholas J -- Escudero, Adrian -- Ochoa, Victoria -- Delgado-Baquerizo, Manuel -- Garcia-Gomez, Miguel -- Bowker, Matthew A -- Soliveres, Santiago -- Escolar, Cristina -- Garcia-Palacios, Pablo -- Berdugo, Miguel -- Valencia, Enrique -- Gozalo, Beatriz -- Gallardo, Antonio -- Aguilera, Lorgio -- Arredondo, Tulio -- Blones, Julio -- Boeken, Bertrand -- Bran, Donaldo -- Conceicao, Abel A -- Cabrera, Omar -- Chaieb, Mohamed -- Derak, McHich -- Eldridge, David J -- Espinosa, Carlos I -- Florentino, Adriana -- Gaitan, Juan -- Gatica, M Gabriel -- Ghiloufi, Wahida -- Gomez-Gonzalez, Susana -- Gutierrez, Julio R -- Hernandez, Rosa M -- Huang, Xuewen -- Huber-Sannwald, Elisabeth -- Jankju, Mohammad -- Miriti, Maria -- Monerris, Jorge -- Mau, Rebecca L -- Morici, Ernesto -- Naseri, Kamal -- Ospina, Abelardo -- Polo, Vicente -- Prina, Anibal -- Pucheta, Eduardo -- Ramirez-Collantes, David A -- Romao, Roberto -- Tighe, Matthew -- Torres-Diaz, Cristian -- Val, James -- Veiga, Jose P -- Wang, Deli -- Zaady, Eli -- 242658/European Research Council/International -- New York, N.Y. -- Science. 2012 Jan 13;335(6065):214-8. doi: 10.1126/science.1215442.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Area de Biodiversidad y Conservacion, Departamento de Biologia y Geologia, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, Calle Tulipan Sin Numero, 28933 Mostoles, Spain. fernando.maestre@urjc.es〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22246775" target="_blank"〉PubMed〈/a〉
    Keywords: *Biodiversity ; *Climate ; Climate Change ; Conservation of Natural Resources ; *Ecosystem ; Geography ; Geological Phenomena ; Models, Statistical ; *Plants ; Regression Analysis ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2017-02-22
    Description: Author(s): E. Valencia et al. We investigate the decay of Br 87 , 88 and Rb 94 using total absorption γ -ray spectroscopy. These important fission products are β -delayed neutron emitters. Our data show considerable β γ intensity, so far unobserved in high-resolution γ -ray spectroscopy, from states at high excitation energy. We also fi… [Phys. Rev. C 95, 024320] Published Tue Feb 21, 2017
    Keywords: Nuclear Structure
    Print ISSN: 0556-2813
    Electronic ISSN: 1089-490X
    Topics: Physics
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of natural products 58 (1995), S. 134-137 
    ISSN: 1520-6025
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 31 (1992), S. 255-258 
    ISSN: 0031-9422
    Keywords: Cassia greggii ; Leguminoseae ; anthraquinone derivatives
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 33 (1993), S. 863-866 
    ISSN: 0031-9422
    Keywords: Ferula linkii-TF ; Umbelliferae ; humulene. ; phenyl propanoids ; sesquiterpene alcohol esters ; sesquiterpene coumarin ethers
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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