Kinetics of the Xanthophyll Cycle and its Role in the Photoprotective Memory and Response

Efficiently balancing photochemistry and photoprotection is crucial for survival and productivity of photosynthetic organisms in the rapidly fluctuating light levels found in natural environments. The ability to respond quickly to sudden changes in light level is clearly advantageous. In the alga Nannochloropsis oceanica we observed an ability to respond rapidly to sudden increases in light level which occur soon after a previous high-light exposure. This ability implies a kind of memory. In this work, we explore the xanthophyll cycle in N. oceanica as a photoprotective memory system. By combining snapshot fluorescence lifetime measurements with a biochemistry-based quantitative model we show that both short-term and medium-term "memory" arises from the xanthophyll cycle. In addition, the model enables us to characterize the relative quenching abilities of the three xanthophyll cycle components. Given the ubiquity of the xanthophyll cycle in photosynthetic organisms the model described here will be of utility in improving our understanding of vascular plant photoprotection with important implications for crop productivity

Deficient Dopamine D2 Receptor Function Causes Renal Inflammation Independently of High Blood Pressure

Renal dopamine receptors participate in the regulation of blood pressure. Genetic factors, including polymorphisms of the dopamine D2 receptor gene (DRD2) are associated with essential hypertension, but the mechanisms of their contribution are incompletely understood. Mice lacking Drd2 (D2−/−) have elevated blood pressure, increased renal expression of inflammatory factors, and renal injury. We tested the hypothesis that decreased dopamine D2 receptor (D2R) function increases vulnerability to renal inflammation independently of blood pressure, is an immediate cause of renal injury, and contributes to the subsequent development of hypertension. In D2−/− mice, treatment with apocynin normalized blood pressure and decreased oxidative stress, but did not affect the expression of inflammatory factors. In mouse RPTCs Drd2 silencing increased the expression of TNFα and MCP-1, while treatment with a D2R agonist abolished the angiotensin II-induced increase in TNF-α and MCP-1. In uni-nephrectomized wild-type mice, selective Drd2 silencing by subcapsular infusion of Drd2 siRNA into the remaining kidney produced the same increase in renal cytokines/chemokines that occurs after Drd2 deletion, increased the expression of markers of renal injury, and increased blood pressure. Moreover, in mice with two intact kidneys, short-term Drd2 silencing in one kidney, leaving the other kidney undisturbed, induced inflammatory factors and markers of renal injury in the treated kidney without increasing blood pressure. Our results demonstrate that the impact of decreased D2R function on renal inflammation is a primary effect, not necessarily associated with enhanced oxidant activity, or blood pressure; renal damage is the cause, not the result, of hypertension. Deficient renal D2R function may be of clinical relevance since common polymorphisms of the human DRD2 gene result in decreased D2R expression and function

Climate mediates the effects of disturbance on ant assemblage structure

Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about howclimate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effectwas manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 98C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. © 2015 The Author(s) Published by the Royal Society. All rights reserved

Estudio de la eficiencia del abono fosfatado

18 páginas, 9 tablas, 5 figuras[EN]Resin ion exchange procedure and E value are used to determine phosphorus content in 24 light texture soils with pH ranging from 5.2 to 7.9 Also, L value and Utilization Coefficient for Ca-superphosphate added at two different levels to pot cultured soils are mesured. Significant correlation coefficients were found between the three values determined for soils phosphorus. Conversely, a negative correlation was obtained between those three values and the Utilization Coefficient for level two of the fertilizer dosis for some of the soils.[ES]Se estudian 24 suelos de pH comprendido entre 5.2 y 7.9, de textura ligera, y en ellos se calcula el valor E y el fósforo por resinas de cambio. Así mismo, se determina el valor L y el Coeficiente de Utilización de superfosfato cálcico añadido a los suelos en dos dosis distintas, por medio de un cultivo en macetas. Se encuentran coeficientes de correlación significativos entre los tres valores citados de fósforo del suelo, y correlación negativa entre dichos valores y el Coeficiente de Utilización del abono en la dosis 2 en algunos suelos.Consejo Superior de Investigaciones CientíficasPeer reviewe

Valor residual de cinco abonos fosfatados

10 páginas, 4 tablas , 2 figuras[EN]The residual effect of five phosphatic fertilizers was evaluated on five soils and the results are compared with those obtained in a previous trial. The ´L´ value for the five soils and the ´A´ value for these soils with five fertilizers were calculated using P32. It was observed that the ´L´ value had decreased considerably in four soils when compared with those calculated in a previous trial. The decrease in the soil 2 is however less and is attributed to its differential properties. A change in ´A´ value was also observed in some soils. This value is practically null in soil 2, which possesses higher fixation capacity as compared to other soils. Phosphorus fractionation in soils containing residual fertilizers was also studied and the same has been related to fertilizer characteristics.[ES]Se estudia el efecto residual de 5 abonos fosfatados en cinco suelos procedentes de un cultivo previo. Se determina el valor ´L´ de los suelos, y el valor ´A´ de cada suelo y abono, utilizando fósforo-32. Se observa que el valor ´L¨disminuye en cuatro suelos respecto del valor inicial, mientras que en el suelo restante (suelo 2) la disminución es menos acusada. El valor ´A´ también sufre variación, siendo prácticamente nulo en el suelo 2 que tiene mayor capacidad de fijación que el resto de los suelos. Se hace el fraccionamiento de fósforo de los suelos, y se estudia la distribución de cada fracción en relación con cada abono.Peer reviewe

Estudio del coeficiente de utilización del superfosfato cálcico por medio de 32P

Se estudian (con 32p) dos métodos de determinación de fósforo en suelos conocidos como valor L y valor E, y así mismo se determina fósforo en resinas de cambio. Entre ellos existe correlación positiva, significativa al 1 ó 5 % según los casos. Dichos métodos dan correlación negativa con el índice de porción de Bache. Se calcula la eficiencia de dos dosis de superfosfato cálcico añadido al suelo (CU %). Dicho coeficiente da correlación positiva con el índice de porción de fósforo, por lo que este último valor puede orientar sobre la dosis de fertilizante o añadir a un cultivo.Proyecto CAICYT-0054-81C02-00

Determinación del coeficiente de utilización de un abono fosfatado.

6 p.[EN] The L value and K coefficient of superphosphate are studied, jointly with some characteristics of four acid soils of the Salamanca province. The results define K value as the typical value that informs us about the reserves behaviour related to the type of fertilizer. From this study it is deduced that the kfertilizer is similar to k-soil when the pool of P soils in sufficient, and k-fertilizer >k-soil in two soils poor in P, while they can provide enough P to plants when no P is added to the soil.[ES] Se estudia el valor L y el coeficiente K de utilización de un superfosfato cálcico en cuatro suelas ácidas de la provincia de Salamanca, así como otros valores característicos de dichos suelos. De los resultados obtenidos se define el coeficiente K como el valor que conjuga las características del suelo y los factores típicos del abono. Se deduce que el coeficiente de utilización de un superfosfato cálcico es semejante al del fósforo del suelo (K w 1) en dos suelos de contenido medio en fósforo, re@ los análisis químicos, ya que la planta toma este elempnto indistintamente de ambas fuentes suelo y abono. Por el contrario los dos suelos deficientes en fósforo toman dicho elemento preferentemente del abono (K > l), aun cuando el suelo contenga reservas suficiente para suministrar el fósforo requerido por la planta como ocurre cuando no se aporta abono al cultivo.Peer reviewe

Influencia del abono nitrogenado sobre el valor L de fósforo.

13 p.[ESP] Se estudia la acción de distintas dosis de abono nitrogenada sobre el valor L del fósforo del suelo, sobre el fósforo absorbido por la planta, el rendimiento y el porcentaje de nitr6geno en la planta, en cuatro suelos ácidos de la provincia de Salamanca. La acción de nitrógeno sobre las variables antedichas es significativa respecto valor L y fósforo-planta con todas las dosis, excepto la dosis 1 (500 ppm N) y la dosis 2 (1000 ppm N); respecto a rendimiento es también significativa excepto con las dosis 1 y 3 (1500 ppm N), y finalmente es muy significativa con todas las dosis cuando se trata de porcentaje de nitrógeno en plantas.[ENG] The effect of various levels of nitrogenous fertilizer on the L value of the soil phosphorus was studied. Phosphorus uptake, yield and nitrogen content of plant respectively were also measured in plants from four acid soils of the Salamanca province, as affected by the above nitrogen levels. The observed effect was significant in respect of the L value and plantphosphorus at all levels except for levels 1 (500 ppm N) and 2 (1000 ppm N). Significant difference was also observed in respect of yield for levels 1 and 3 (1500 ppm N) respectively, and finally, nitrogen percentage was significant at all levels tested