Neuronal Responses in the Brainstem and Hypothalamic Nuclei Following Insulin Treatment During the Late Follicular Phase in the Ewe

The aim of this study was to determine the neuronal responses following insulin administration during the late follicular phase. Intact ewes were given either saline or insulin (5 IU/kg, i.v.) at 35 h after progesterone withdrawal and killed 3 h later. There was a marked increase in the number of Fos‐positive noradrenergic neurones in the caudal brainstem of insulin‐treated ewes. In the hypothalamic paraventricular nucleus, insulin treatment increased the presence of Fos‐positive corticotrophin‐releasing hormone neurones (from 2% to 98%) and Fos‐positive arginine vasopressin parvocellular neurones (from 2% to 46%). Interestingly, after insulin treatment, despite a general increase in Fos‐positive neurones in the arcuate nucleus (ARC), there was a marked reduction (from 47% to 1%) in Fos‐positive β‐endorphin neurones. Similarly, colocalized Fos and oestradiol receptor (ER) α‐positive neurones decreased in the ARC after insulin (from 7% to 3%). Conversely, in the ventromedial nucleus, ERα‐positive neurones with Fos increased (from 7% to 22%) alongside a general increase in Fos‐positive neurones. Overall, a complex system of neurones in brainstem and hypothalamus is activated following insulin administration during the late follicular phase.     

Effects of synbiotic-based Bifidobacterium animalis in female rats experimentally infected with Toxoplasma gondii

The aim of this study was to assess the effects of a synbiotic composed of Bifidobacterium animalis and fructooligosaccharides on female rats infected with Toxoplasma gondii. Female Wistar rats, treated or not with dexamethasone, were daily supplemented with synbiotics for 21 days. After 15 days of supplementation, the rats were orally infected with 10⁴T. gondii bradyzoites. Blood samples were collected to measure the levels of IFN-γ, IL-10 and T. gondii antibodies. All synbiotic-supplemented rats survived until the end of the experiment; however, non-supplemented dexamethasone-treated rats died between the fifth and the eighth days after T. gondii infection. Dexamethasone-treated rats supplemented with synbiotics (P < 0.05) were capable of synthesizing IFN-γ, and this immunological response was essential to ensure their survival. In addition, brain cysts were found in one rat not supplemented with synbiotics. Results suggest that the synbiotic composed of B. animalis and fructooligosaccharides may be beneficial to toxoplasmosis control.     

Performance of a distributed semi-conceptual hydrological model under tropical watershed conditions

Conceptual rainfall-runoff models at the watershed scale are useful tools for assisting in managing and planning water resources, making it possible to estimate streamflow and to predict hydrologic impacts due to land-use changes. The objective of this study was to calibrate and to validate the LAvras Simulation of Hydrology (LASH Model) (Beskow, 2009) in a Brazilian Tropical Watershed for daily streamflow. LASH is a continuous, distributed, semi-physically based model for simulation of different hydrologic components on a daily basis. The Shuffled Complex Evolution (SCE-UA) global search method was used with the LASH model in order to optimize model parameters that were found to be the most sensitive or not directly measurable. The LASH model was calibrated over a 2-year period, thereafter, the parameters obtained through the calibration were kept constant for the validation step using a different period of time from that analyzed during the calibration. The Nash–Sutcliffe coefficient (C_NS) values found were 0.820 and 0.764 during calibration and validation, respectively, whereas, the C_NS (log Q) values equal to 0.821 and 0.770 were obtained for the same periods. The SCE-UA method was found to be an efficient algorithm for searching ‘optimal’ model parameter values. It was possible to conclude that the model has a great potential for being applied in generating the long-term streamflow as well as flow-duration curves. Therefore, the model can reliably be applied under tropical conditions of this medium-sized watershed or other similar watersheds, thus making it useful to plan the sustainable development of similar tropical and subtropical watersheds.     

Water stress and warming impact nutrient use efficiency of Mombasa grass (Megathyrsus maximus) in tropical conditions

Temperature and other abiotic factors, such water and nutrient availability, play an important role for plants in response to the changing environments. At this regard, both warming and drought might affect the nutrient use efficiency (NUE) and growth of Megathyrsus maximus a C4 forage grass of high interest for cattle feeding. However, the nutrient requirements of this species under climate change are unknown. Therefore, we aimed to evaluate the individual and combined effects of two levels of temperature: ambient and elevated temperature (2°C above ambient temperature), and two levels of soil water availability: irrigated plants and non‐irrigated plants on accumulation of leaf nutrients, NUE and biomass production of M. maximus. Temperature control was performed by a temperature free‐air‐controlled enhancement (T‐FACE) system under field conditions. In general, we observed that warming under well‐irrigated conditions increased the leaf accumulation of most nutrients, improving the NUE of N, P, K, Ca, Mg, Cu, Mn and Zn. Plant growth was also enhanced under warming effects, with higher leaf dry mass accumulation and root development. Meanwhile, drought decreased NUE of K, Ca, B and leaf dry biomass, while root growth was stimulated. The combined effects of warming and drought on nutrient accumulation, NUE and plant growth tended to be greater than the individual effects expected from a single factor; thus, warming mitigated the negative impacts of individual drought. In summary, our findings suggest that warming and drought, both as individual and combined factors, will change the nutrient requirements of M. maximus in tropical ecosystems.     

Elevated [CO2] and warming increase the macronutrient use efficiency and biomass of Stylosanthes capitata Vogel under field conditions

Stylosanthes capitata Vogel is a C3 forage legume widely cultivated in tropical and subtropical pastures. However, the nutrient dynamics of this species under future climate change is unknown. Therefore, this study aimed to evaluate the nutrient content, nutrient accumulation, nutrient use efficiency and growth of S. capitata exposed to increased [CO₂] and temperature under field conditions using two levels of atmospheric [CO₂] (ambient and elevated—600 ppm) and two canopy temperature (ambient and elevated—2°C). Treatments were applied at field conditions, for 30 days, using a free-air carbon dioxide enrichment (FACE) and a free-air temperature-controlled enhancement (T-FACE) systems. Warming showed no effects on macronutrient content, but increased the accumulation of nitrogen, potassium, calcium, magnesium and sulphur, the nutrient use efficiency and root dry mass. Elevated [CO₂] alone had no effect on most of the parameters evaluated. However, the combination of elevated [CO₂] with warming improved the nutrient accumulation, nutrient use efficiency and whole-plant growth more than under isolated conditions of elevated [CO₂] or warming. Based on our short-term results, we concluded that an increment of atmospheric [CO₂] and temperature will benefit S. capitata growth, suggesting no alterations in the actual fertilizer programs for this species.     

Fatty acids as a tool to compare cachara (Pseudoplatystoma reticulatum) (Siluriformes: Pimelodidae) and hybrid (Pseudoplatystoma corruscans?×?Pseudoplatystoma reticulatum) larvae during early development

In this study, we investigated the physiological alterations during ontogeny for cachara (Pseudoplatystoma reticulatum) and their hybrid larvae (Pseudoplatystoma corruscans?×?P. reticulatum) using lipids and fatty acids as physiological tools to elucidate the basis for differences in these groups?? productivity in an industrial setting. Eggs and larvae samples were collected during January and February of 2008 in the city of Bandeirantes, MS, and were divided into three primary phases: phase I (0?C16?h after fertilization); phase II (24?h after fertilization to 6?days after fertilization); and phase III (7?C25?days after fertilization). The larvae of both groups showed a high degree of similarity, suggesting that the hybrid larvae showed a high level of heritability from the cachara broodstock. Analysis of the total lipid content provided evidence that there is no alteration in lipid concentration during ontogeny for both groups (i.e., the cachara and hybrids). However, the fatty acid profile showed that during the endogenous feeding period (phase II), when the larvae must use the energy reserves from the mother, the cachara larvae used mainly monounsaturated fatty acids for development. This is typical for most fish species, though notably, the hybrids preferentially used saturated fatty acids. Furthermore, certain specific changes demonstrate unique patterns of energy utilization and structural substrates, which may aid in elucidating the empirical differences reported by fish farmers (i.e., that the hybrids perform better than cacharas in captivity).     

High β‐diversity maintains regional diversity in Brazilian tropical coastal stream fish assemblages

Understanding spatial patterns of species diversity and the variables that structure biological communities is critical to successful ecosystem management. Regional diversity (γ) can be considered a combination of local diversity (α) and among sites variation (β). Using abundance data of fish species in 19 stream stretches, an analysis of diversity partitioning was used to determine the contribution of α‐ and β‐diversity to γ‐diversity. Redundancy analysis was applied to find the contribution of environmental variables and spatial configuration to species composition. Intersite variation contributed significantly to γ‐diversity. Spatial configuration and instream heterogeneity (coarse substrate, channel width, water velocity and shading) and riparian vegetation were related to local fish abundances. Conservation actions should consider that all streams are important, and prioritisation of just a small number of the richest sites is not appropriate.     

Development and application of a simple hydrologic model simulation for a Brazilian headwater basin

Physically based hydrologic models for watersheds are important tools to support water resources management and predict hydrologic impacts produced by land-use change. Grande River Basin is located in southern Minas Gerais State, and the Grande River is the main tributary of Basin which has 2080 km² draining into the Camargos Hydropower Plant Reservoir (CEMIG — “Minas Gerais State Energy Company”). The objectives of this work were: 1) to create a semi-physically based hydrologic model in semi-distributed to sub-basins approach and based on GIS and Remote Sensing tools and, 2) to simulate the hydrologic responses of the Grande River Basin, thus creating an important tool for management and planning of water resources for region. The hydrologic model is based on the SCS Curve Number (SCS-CN) and MGB/IPH models, and structured into three hydrologic components: estimation of the flow components (quick runoff, hortonian and base flows), propagation into the respective soil reservoirs (surface, sub-surface and shallow saturated zone) and propagation into the channels. Precipitation and discharge data sets were obtained from the Brazilian National Water Agency (ANA). Reference evapotranspiration (ETo) data were obtained from the Brazilian National Meteorological Institute (INMET). In order to estimate actual evapotranspiration, crop coefficient, soil moisture and satellite image interpretation of actual land-use were applied. The long-term hydrologic data series were structured for period between 1990 and 2003. The calibration and validation process was carried out by evaluating the behavior of the Nash–Sutcliffe Coefficient (C_NS), obtained from three different combinations of calibration and validation years. This allowed us to evaluate the model performance to simulate years in which El Niño (EN) and La Niña (LN) events were registered (1997–1998 and 1999–2000, respectively). The combinations of calibration and validation years were: the first 7 years to calibrate and remaining 6 years to validate; the first 9 years to calibrate and remaining 4 years to validate; and first 11 years to calibrate and the last 2 years to validate. The statistical precision showed that the model was able to simulate the hydrologic impacts, including years of EN and LN events, with C_NS scores greater than 0.70 in both situations. The evaluation of the C_NS scores showed small variation in the coefficient as the years of validation decreased. In addition, the model was also able to simulate the hydrologic impacts of land-use change in the Grande River Basin, based on the C_NS scores of 0.80 for different combinations of validation periods. The hydrologic impacts in Grande River Basin produced from grassland area converted to eucalyptus under three specific scenarios were evaluated, which predicted annual runoff mean reductions of up to 17.8%, due to an increase in evapotranspiration rate for the eucalyptus plantation.     

Silicon and salicylic acid in the physiology and yield of cotton

Silicon (Si) and salicylic acid (SA) foliar applications can benefit cotton yield especially if there is stress during cultivation. The objective of this study was to evaluate the foliar application of Si and SA on the photosynthetic variables and cotton yield. The experimental design used was randomized complete block, constituted by Si foliar application in potassium and sodium balanced silicate form (0 and 3.6?g L^?1 of Si) and SA (0 and 210?mg L^?1). The treatments were applied in three leaf sprays during the reproductive stage that coincided with water stress in tillage. Therefore, the Si foliar application associated with SA favors the physiological variables, increasing the photosynthesis, stomatal conductance and water use efficiency reflecting on the increase of cotton yield.