4,555 research outputs found
Quantitative trait loci and crop performance under abiotic stress: Where do we stand?
No full textNicholas C. Collins, François Tardieu and Roberto Tuberos
Hot orogens and supercontinent amalgamation: A Gondwanan example from southern India
No full textAvailable online 28 November 2014Abstract not availableChris Clark, David Healy, Tim Johnson, Alan S. Collins, Richard J. Taylor, M. Santosh, Nicholas E. Timm
The CC-NB-LRR-Type Rdg2a resistance gene confers immunity to the seed-borne barley leaf stripe pathogen in the absence of hypersensitive cell death
No full textBACKGROUND: Leaf stripe disease on barley (Hordeum vulgare) is caused by the seed-transmitted hemi-biotrophic fungus Pyrenophora graminea. Race-specific resistance to leaf stripe is controlled by two known Rdg (Resistance to Drechslera graminea) genes: the H. spontaneum-derived Rdg1a and Rdg2a, identified in H. vulgare. The aim of the present work was to isolate the Rdg2a leaf stripe resistance gene, to characterize the Rdg2a locus organization and evolution and to elucidate the histological bases of Rdg2a-based leaf stripe resistance. PRINCIPLE FINDINGS: We describe here the positional cloning and functional characterization of the leaf stripe resistance gene Rdg2a. At the Rdg2a locus, three sequence-related coiled-coil, nucleotide-binding site, and leucine-rich repeat (CC-NB-LRR) encoding genes were identified. Sequence comparisons suggested that paralogs of this resistance locus evolved through recent gene duplication, and were subjected to frequent sequence exchange. Transformation of the leaf stripe susceptible cv. Golden Promise with two Rdg2a-candidates under the control of their native 5′ regulatory sequences identified a member of the CC-NB-LRR gene family that conferred resistance against the Dg2 leaf stripe isolate, against which the Rdg2a-gene is effective. Histological analysis demonstrated that Rdg2a-mediated leaf stripe resistance involves autofluorescing cells and prevents pathogen colonization in the embryos without any detectable hypersensitive cell death response, supporting a cell wall reinforcement-based resistance mechanism. CONCLUSIONS: This work reports about the cloning of a resistance gene effective against a seed borne disease. We observed that Rdg2a was subjected to diversifying selection which is consistent with a model in which the R gene co-evolves with a pathogen effector(s) gene. We propose that inducible responses giving rise to physical and chemical barriers to infection in the cell walls and intercellular spaces of the barley embryo tissues represent mechanisms by which the CC-NB-LRR-encoding Rdg2a gene mediates resistance to leaf stripe in the absence of hypersensitive cell death.Davide Bulgarelli, Chiara Biselli, Nicholas C. Collins, Gabriella Consonni, Antonio M. Stanca, Paul Schulze-Lefert and Giampiero Val
Letter to Eliza Ann Collins Edgar
No full textLetter c. 1860 to Eliza Ann Collins Edgar regarding home, family and friends, unknown author. Women. Letter if difficult to read. HL introduction page overlaid by document. Letter in English, handwritten, 4pp/fr
Buffington, Hailman, and Gilbert at Collins Speaker Series
No full textRex Buffington, Executive Director, John C. Stennis Center, John Hailman, author of From Midnight to Guntown, and Dr. Jerry Gilbert, Provost and Executive Vice President MSU during the Collins Speaker Serie
Trust and Trustworthiness in the Fourth and Fifth Estates
No full textThe high contemporary salience in the social sciences of the topics of "trust" and "trustworthiness" has focused attention on the mass media’s putative role in eroding trust. Intrinsically, the absence in the mass media of the dialogic and interactive element to trust building identified by O’ Neill (2002) may suggest that the lack of trust and trustworthiness in the mass media is structural and recent penalties imposed by the UK communication regulator, Ofcom, on UK public service broadcasters including the BBC seem to support such a view. However, drawing on and adapting O’Neill, the author identifies two distinct potential media trust building strategies: one procedural (based in professional norms) and the second dialogic and interactive (nascent in “Web 2.0” applications). Focusing on UK Web 2.0 media sites the author identifies instances where the "dialogic" character of "Web 2.0" has established and enhanced trustworthiness. He argues normatively for a combination of "Web 2.0" interactivity and the adoption and implementation of self-regulatory codes in order to enhance the trustworthiness of the media
Search as Learning (Dagstuhl Seminar 17092)
No full textThis report describes the program and the results of Dagstuhl Seminar 17092 "Search as Learning", which brought together 26 researchers from diverse research backgrounds. The motivation for the seminar stems from the fact that modern Web search engines are largely engineered and optimized to fulfill lookup tasks instead of complex search tasks. The latter though are an essential component of information discovery and learning. The 3-day seminar started with four perspective talks, providing four different views on the topic of search as learning: interactive information retrieval (IR), psychology, education and system-oriented IR. The remainder of the seminar centered around breakout groups leading to new views on the challenges and issues in search as learning, interspersed with research spotlight talks.Web Information System
Collins effect in single spin asymmetries of the p up arrow p -> pi X process
No full textWe investigate the Collins effect in single spin asymmetries ( SSAs) of the p(up arrow)p -> pi X process by taking into account the transverse momentum dependence of the microscopic sub-process cross sections, with the transverse momentum in the Collins function integrated over. We find that the asymmetries due to the Collins effect can only explain the available data at best qualitatively, by using our choices of quark distributions in the quark-diquark model and a pQCD-based analysis, together with several options of the Collins function. Our results indicate the necessity to take into account contributions from other effects such as the Sivers effect or twist-3 contributions.Physics, Particles & FieldsSCI(E)7ARTICLE163-674
Scaling of oxygen consumption of Lake Magadi tilapia, a fish living at 37 degree C
No full textRates of oxygen consumption were measured in the geothermal, hot spring fish, Oreochromis alcalicus grahami by stopped flow respirometry. At 37 degree C, routine oxygen, consumption followed the allometric relationship: Vo sub(2)=0.738 M super(0.75), where Vo sub(2) is ml O sub(2)/h and M is body mass (g). This represents a routine metabolic rate for a 10 g fish at 37 degree C of 0.415 ml O sub(2)/g/h (16.4 mu mol O sub(2)/g/h). Acutely increasing the temperature from 37 to 42 degree C significantly elevated the rate of O sub(2) consumption from 0.739 to 0.970 ml O sub(2)/g/h (Q sub(10)=1.72). In the field, O. a. grahami was observed to be 'gulping' air from the surface of the water especially in hot springs that exceeded 40 degree C, O. a. grahami may utilize aerial respiration when O sub(2) requirements are high.TR: CS9609969Source type: Electronic(1
Diverging temperature responses of CO(2) assimilation and plant development explain the overall effect of temperature on biomass accumulation in wheat leaves and grains
No full textThere is a growing consensus in the literature that rising temperatures influence the rate of biomass accumulation by shortening the development of plant organs and the whole plant and by altering rates of respiration and photosynthesis. A model describing the net effects of these processes on biomass would be useful, but would need to reconcile reported differences in the effects of night and day temperature on plant productivity. In this study, the working hypothesis was that the temperature responses of CO2 assimilation and plant development rates were divergent, and that their net effects could explain observed differences in biomass accumulation. In wheat (Triticum aestivum) plants, we followed the temperature responses of photosynthesis, respiration and leaf elongation, and confirmed that their responses diverged. We measured the amount of carbon assimilated per "unit of plant development" in each scenario and compared it to the biomass that accumulated in growing leaves and grains. Our results suggested that, up to a temperature optimum, the rate of any developmental process increased with temperature more rapidly than that of CO2 assimilation and that this discrepancy, summarised by the CO2 assimilation rate per unit of plant development, could explain the observed reductions in biomass accumulation in plant organs under high temperatures. The model described the effects of night and day temperature equally well, and offers a simple framework for describing the effects of temperature on plant growth.Iman Lohraseb, Nicholas C. Collins, Boris Paren
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