Grain Accumulation of Selenium Species in Rice (Oryza sativa L.)

Efficient Se biofortification programs require a thorough understanding of the accumulation and distribution of Se species within the rice grain. Therefore, the translocation of Se species to the filling grain and their spatial unloading were investigated. Se species were supplied via cut flag leaves of intact plants and excised panicle stems subjected to a +/- stem-girdling treatment during grain fill. Total Se concentrations in the flag leaves and grain were quantified by inductively coupled plasma mass spectrometry. Spatial accumulation was investigated using synchrotron X-ray fluorescence microtomography. Selenomethionine (SeMet) and selenomethylcysteine (SeMeSeCys) were transported to the grain more efficiently than selenite and selenate. SeMet and SeMeSeCys were translocated exclusively via the phloem, while inorganic Se was transported via both the phloem and xylem. For SeMet- and SeMeSeCys-fed grain, Se dispersed throughout the external grain layers and into the endosperm and, for SeMeSeCys, into the embryo. Selenite was retained at the point of grain entry. These results demonstrate that the organic Se species SeMet and SeMeSeCys are rapidly loaded into the phloem and transported to the grain far more efficiently than inorganic species. Organic Se species are distributed more readily, and extensively, throughout the grain than selenite.

Snow depths of volcanic events and accumulation rates of firn cores from the IPY traverse, Antarctica

Volcanic signatures in ice-core records provide an excellent means to date the cores and obtain information about accumulation rates. From several ice cores it is thus possible to extract a spatio-temporal accumulation pattern. We show records of electrical conductivity and sulfur from 13 firn cores from the Norwegian-USA scientific traverse during the International Polar Year 2007-2009 (IPY) through East Antarctica. Major volcanic eruptions are identified and used to assess century-scale accumulation changes. The largest changes seem to occur in the most recent decades with accumulation over the period 1963-2007/08 being up to 25% different from the long-term record. There is no clear overall trend, some sites show an increase in accumulation over the period 1963 to present while others show a decrease. Almost all of the sites above 3200 m above sea level (asl) suggest a decrease. These sites also show a significantly lower accumulation value than large-scale assessments both for the period 1963 to present and for the long-term mean at the respective drill sites. The spatial accumulation distribution is influenced mainly by elevation and distance to the ocean (continentality), as expected. Ground-penetrating radar data around the drill sites show a spatial variability within 10-20% over several tens of kilometers, indicating that our drill sites are well representative for the area around them. Our results are important for large-scale assessments of Antarctic mass balance and model validation.

Estado, industrialização e os espaços de acumulação das Multilatinas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Synchronisation of the EDML and EDC ice cores for the last 52 kyr by volcanic signature matching

A common time scale for the EPICA ice cores from Dome C (EDC) and Dronning Maud Land (EDML) has been established. Since the EDML core was not drilled on a dome, the development of the EDML1 time scale for the EPICA ice core drilled in Dronning Maud Land was based on the creation of a detailed stratigraphic link between EDML and EDC, which was dated by a simpler 1D ice-flow model. The synchronisation between the two EPICA ice cores was done through the identification of several common volcanic signatures. This paper describes the rigorous method, using the signature of volcanic sulfate, which was employed for the last 52 kyr of the record. We estimated the discrepancies between the modelled EDC and EDML glaciological age scales during the studied period, by evaluating the ratio R of the apparent duration of temporal intervals between pairs of isochrones. On average R ranges between 0.8 and 1.2 corresponding to an uncertainty of up to 20% in the estimate of the time duration in at least one of the two ice cores. Significant deviations of R up to 1.4–1.5 are observed between 18 and 28 kyr before present (BP), where present is defined as 1950. At this stage our approach does not allow us unequivocally to find out which of the models is affected by errors, but assuming that the thinning function at both sites and accumulation history at Dome C (which was drilled on a dome) are correct, this anomaly can be ascribed to a complex spatial accumulation variability (which may be different in the past compared to the present day) upstream of the EDML core.

El análisis regional en la Argentina : Enfoque teórico-metodológico y aportes para su profundización

El artículo presenta los principales núcleos del enfoque de análisis regional en la Argentina, realizando distintos aportes a su desarrollo sobre las dinámicas de acumulación y hegemonía. En ese sentido, retomamos a autores como Rofman, de Jong y Levín, para comprender la relación entre territorio y sociedad. Partimos del planteo de construcción de conocimiento sintético y holístico, tratando de integrar las distintas escalas del análisis espacial con sus particularidades y sus interpenetraciones. La relación espacio/modo de producción nos lleva a la pregunta por las transformaciones orgánicas del capital como relación social y, así, al estudio del proceso de reproducción ampliada del capital a partir de conceptos como el de régimen y modelo de acumulación, a diferentes escalas, alcances y niveles de abstracción. Vemos las relaciones de fuerzas a nivel internacional a la luz de la disputa por distintos monopolios estratégicos, que señala Amín, y del lugar de las corporaciones transnacionales como agentes centrales de los regímenes de acumulación actual. En ese punto, continuamos desarrollando el plan de análisis de relaciones de fuerzas gramsciano, desde su nivel estructural hasta el momento de la hegemonía. De esta manera, la construcción del territorio dentro de una formación social nacional lleva a indagar la dinámica del proceso productivo, sus agentes, fracciones y clases, así como el rol del Estado y de la disputa entre distintos proyectos societarios. Estas dimensiones aparecen, asimismo, conjugadas, en una escala menor, en el análisis de los subsistemas espaciales de acumulación y de los circuitos productivos regionales que los constituyen. La explicitación de diversas claves teórico-metodológicas aparece atravesada por el debate en torno a repensar la planificación del espacio social, preguntándonos ¿qué territorio para qué sociedad?

El análisis regional en la Argentina : Enfoque teórico-metodológico y aportes para su profundización

El artículo presenta los principales núcleos del enfoque de análisis regional en la Argentina, realizando distintos aportes a su desarrollo sobre las dinámicas de acumulación y hegemonía. En ese sentido, retomamos a autores como Rofman, de Jong y Levín, para comprender la relación entre territorio y sociedad. Partimos del planteo de construcción de conocimiento sintético y holístico, tratando de integrar las distintas escalas del análisis espacial con sus particularidades y sus interpenetraciones. La relación espacio/modo de producción nos lleva a la pregunta por las transformaciones orgánicas del capital como relación social y, así, al estudio del proceso de reproducción ampliada del capital a partir de conceptos como el de régimen y modelo de acumulación, a diferentes escalas, alcances y niveles de abstracción. Vemos las relaciones de fuerzas a nivel internacional a la luz de la disputa por distintos monopolios estratégicos, que señala Amín, y del lugar de las corporaciones transnacionales como agentes centrales de los regímenes de acumulación actual. En ese punto, continuamos desarrollando el plan de análisis de relaciones de fuerzas gramsciano, desde su nivel estructural hasta el momento de la hegemonía. De esta manera, la construcción del territorio dentro de una formación social nacional lleva a indagar la dinámica del proceso productivo, sus agentes, fracciones y clases, así como el rol del Estado y de la disputa entre distintos proyectos societarios. Estas dimensiones aparecen, asimismo, conjugadas, en una escala menor, en el análisis de los subsistemas espaciales de acumulación y de los circuitos productivos regionales que los constituyen. La explicitación de diversas claves teórico-metodológicas aparece atravesada por el debate en torno a repensar la planificación del espacio social, preguntándonos ¿qué territorio para qué sociedad?

El análisis regional en la Argentina : Enfoque teórico-metodológico y aportes para su profundización

El artículo presenta los principales núcleos del enfoque de análisis regional en la Argentina, realizando distintos aportes a su desarrollo sobre las dinámicas de acumulación y hegemonía. En ese sentido, retomamos a autores como Rofman, de Jong y Levín, para comprender la relación entre territorio y sociedad. Partimos del planteo de construcción de conocimiento sintético y holístico, tratando de integrar las distintas escalas del análisis espacial con sus particularidades y sus interpenetraciones. La relación espacio/modo de producción nos lleva a la pregunta por las transformaciones orgánicas del capital como relación social y, así, al estudio del proceso de reproducción ampliada del capital a partir de conceptos como el de régimen y modelo de acumulación, a diferentes escalas, alcances y niveles de abstracción. Vemos las relaciones de fuerzas a nivel internacional a la luz de la disputa por distintos monopolios estratégicos, que señala Amín, y del lugar de las corporaciones transnacionales como agentes centrales de los regímenes de acumulación actual. En ese punto, continuamos desarrollando el plan de análisis de relaciones de fuerzas gramsciano, desde su nivel estructural hasta el momento de la hegemonía. De esta manera, la construcción del territorio dentro de una formación social nacional lleva a indagar la dinámica del proceso productivo, sus agentes, fracciones y clases, así como el rol del Estado y de la disputa entre distintos proyectos societarios. Estas dimensiones aparecen, asimismo, conjugadas, en una escala menor, en el análisis de los subsistemas espaciales de acumulación y de los circuitos productivos regionales que los constituyen. La explicitación de diversas claves teórico-metodológicas aparece atravesada por el debate en torno a repensar la planificación del espacio social, preguntándonos ¿qué territorio para qué sociedad?

Chronic Morphine Treatment Impaired Hippocampal Long-Term Potentiation and Spatial Memory via Accumulation of Extracellular Adenosine Acting on Adenosine A(1) Receptors

Chronic exposure to opiates impairs hippocampal long-term potentiation (LTP) and spatial memory, but the underlying mechanisms remain to be elucidated. Given the well known effects of adenosine, an important neuromodulator, on hippocampal neuronal excitability and synaptic plasticity, we investigated the potential effect of changes in adenosine concentrations on chronic morphine treatment-induced impairment of hippocampal CA1 LTP and spatial memory. We found that chronic treatment in mice with either increasing doses (20-100 mg/kg) of morphine for 7 d or equal daily dose (20 mg/kg) of morphine for 12 d led to a significant increase of hippocampal extracellular adenosine concentrations. Importantly, we found that accumulated adenosine contributed to the inhibition of the hippocampal CA1 LTP and impairment of spatial memory retrieval measured in the Morris water maze. Adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine significantly reversed chronic morphine-induced impairment of hippocampal CA1 LTP and spatial memory. Likewise, adenosine deaminase, which converts adenosine into the inactive metabolite inosine, restored impaired hippocampal CA1 LTP. We further found that adenosine accumulation was attributable to the alteration of adenosine uptake but not adenosine metabolisms. Bidirectional nucleoside transporters (ENT2) appeared to play a key role in the reduction of adenosine uptake. Changes in PKC-alpha/beta activity were correlated with the attenuation of the ENT2 function in the short-term (2 h) but not in the long-term (7 d) period after the termination of morphine treatment. This study reveals a potential mechanism by which chronic exposure to morphine leads to impairment of both hippocampal LTP and spatial memory.

Cortical Dynamics of Contextually-Cued Attentive Visual Learning and Search: Spatial and Object Evidence Accumulation

How do humans use predictive contextual information to facilitate visual search? How are consistently paired scenic objects and positions learned and used to more efficiently guide search in familiar scenes? For example, a certain combination of objects can define a context for a kitchen and trigger a more efficient search for a typical object, such as a sink, in that context. A neural model, ARTSCENE Search, is developed to illustrate the neural mechanisms of such memory-based contextual learning and guidance, and to explain challenging behavioral data on positive/negative, spatial/object, and local/distant global cueing effects during visual search. The model proposes how global scene layout at a first glance rapidly forms a hypothesis about the target location. This hypothesis is then incrementally refined by enhancing target-like objects in space as a scene is scanned with saccadic eye movements. The model clarifies the functional roles of neuroanatomical, neurophysiological, and neuroimaging data in visual search for a desired goal object. In particular, the model simulates the interactive dynamics of spatial and object contextual cueing in the cortical What and Where streams starting from early visual areas through medial temporal lobe to prefrontal cortex. After learning, model dorsolateral prefrontal cortical cells (area 46) prime possible target locations in posterior parietal cortex based on goalmodulated percepts of spatial scene gist represented in parahippocampal cortex, whereas model ventral prefrontal cortical cells (area 47/12) prime possible target object representations in inferior temporal cortex based on the history of viewed objects represented in perirhinal cortex. The model hereby predicts how the cortical What and Where streams cooperate during scene perception, learning, and memory to accumulate evidence over time to drive efficient visual search of familiar scenes.

Spatial characterization of salt accumulation in early stage limestone weathering using probe permeametry

This research characterizes the weathering of natural building stone using an unsteady-state portable probe permeameter. Variations between the permeability properties of fresh rock and the same rocks after the early stages of a salt weathering simulation are used to examine the effects of salt accumulation on spatial variations in surface rock permeability properties in two limestones from Spain. The Fraga and Tudela limestones are from the Ebro basin and are of Miocene age. Both stone types figure largely in the architectural heritage of Spain and, in common with many other building limestones, they are prone to physical damage from salt crystallization in pore spaces. To examine feedbacks associated with salt accumulation during the early stages of this weathering process, samples of the two stone types were subjected to simulated salt weathering under laboratory conditions using magnesium sulphate and sodium chloride at concentrations of 5% and 15%. Permeability mapping and statistical analysis (aspatial statistics and spatial prediction) before and after salt accumulation are used to assess changes in the spatial variability of permeability and to correlate these changes with salt movement, porosity change, potential rock deterioration and textural characteristics. Statistical analyses of small-scale permeability measurements are used to evaluate the drivers for decay and hence aid the prediction of the weathering behaviour of the two limestones.

Starch accumulation in cassava roots: spatial and temporal distribution

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Spatial gradients of temperature, accumulation and delta18O-ice in Greenland over a series of Dansgaard-Oeschger events

Air and water stable isotope measurements from four Greenland deep ice cores (GRIP, GISP2, NGRIP and NEEM) are investigated over a series of Dansgaard–Oeschger events (DO 8, 9 and 10), which are representative of glacial millennial scale variability. Combined with firn modeling, air isotope data allow us to quantify abrupt temperature increases for each drill site (1σ = 0.6 °C for NEEM, GRIP and GISP2, 1.5 °C for NGRIP). Our data show that the magnitude of stadial–interstadial temperature increase is up to 2 °C larger in central and North Greenland than in northwest Greenland: i.e., for DO 8, a magnitude of +8.8 °C is inferred, which is significantly smaller than the +11.1 °C inferred at GISP2. The same spatial pattern is seen for accumulation increases. This pattern is coherent with climate simulations in response to reduced sea-ice extent in the Nordic seas. The temporal water isotope (δ18O)–temperature relationship varies between 0.3 and 0.6 (±0.08) ‰ °C−1 and is systematically larger at NEEM, possibly due to limited changes in precipitation seasonality compared to GISP2, GRIP or NGRIP. The gas age−ice age difference of warming events represented in water and air isotopes can only be modeled when assuming a 26% (NGRIP) to 40% (GRIP) lower accumulation than that derived from a Dansgaard–Johnsen ice flow model.