Preserving isohydricity: vertical environmental variability explains Amazon forest water-use strategies.

Increases in hydrological extremes, including drought, are expected for Amazon forests. A fundamental challenge for predicting forest responses lies in identifying ecological strategies which underlie such responses. Characterization of species-specific hydraulic strategies for regulating water-use, thought to be arrayed along an 'isohydric-anisohydric' spectrum, is a widely used approach. However, recent studies have questioned the usefulness of this classification scheme, because its metrics are strongly influenced by environments, and hence can lead to divergent classifications even within the same species. Here, we propose an alternative approach positing that individual hydraulic regulation strategies emerge from the interaction of environments with traits. Specifically, we hypothesize that the vertical forest profile represents a key gradient in drought-related environments (atmospheric vapor pressure deficit, soil water availability) that drives divergent tree water-use strategies for coordinated regulation of stomatal conductance (gs) and leaf water potentials (ΨL) with tree rooting depth, a proxy for water availability. Testing this hypothesis in a seasonal eastern Amazon forest in Brazil, we found that hydraulic strategies indeed depend on height-associated environments. Upper canopy trees, experiencing high vapor pressure deficit (VPD), but stable soil water access through deep rooting, exhibited isohydric strategies, defined by little seasonal change in the diurnal pattern of gs and steady seasonal minimum ΨL. In contrast, understory trees, exposed to less variable VPD but highly variable soil water availability, exhibited anisohydric strategies, with fluctuations in diurnal gs that increased in the dry season along with increasing variation in ΨL. Our finding that canopy height structures the coordination between drought-related environmental stressors and hydraulic traits provides a basis for preserving the applicability of the isohydric-to-anisohydric spectrum, which we show here may consistently emerge from environmental context. Our work highlights the importance of understanding how environmental heterogeneity structures forest responses to climate change, providing a mechanistic basis for improving models of tropical ecosystems.

Towards accurate monitoring of water content in woody tissue across tropical forests and other biomes.

Forest ecosystems face increasing drought exposure due to climate change, necessitating accurate measurements of vegetation water content to assess drought stress and tree mortality risks. Although Frequency Domain Reflectometry offers a viable method for monitoring stem water content by measuring dielectric permittivity, challenges arise from uncertainties in sensor calibration linked to wood properties and species variability, impeding its wider usage. We sampled tropical forest trees and palms in eastern Amazônia to evaluate how sensor output differences are controlled by wood density, temperature and taxonomic identity. Three individuals per species were felled and cut into segments within a diverse dataset comprising five dicotyledonous tree and three monocotyledonous palm species on a wide range of wood densities. Water content was estimated gravimetrically for each segment using a temporally explicit wet-up/dry-down approach and the relationship with the dielectric permittivity was examined. Woody tissue density had no significant impact on the calibration, but species identity and temperature significantly affected sensor readings. The temperature artefact was quantitatively important at large temperature differences, which may have led to significant bias of daily and seasonal water content dynamics in previous studies. We established the first tropical tree and palm calibration equation which performed well for estimating water content. Notably, we demonstrated that the sensitivity remained consistent across species, enabling the creation of a simplified one-slope calibration for accurate, species-independent measurements of relative water content. Our one-slope calibration serves as a general, species-independent standard calibration for assessing relative water content in woody tissue, offering a valuable tool for quantifying drought responses and stress in trees and forest ecosystems.

Photosynthetic acclamatory response of Panicum antidotale Retz. populations to root zone desiccation stress / Reação fotossintética aclamatória de Panicum antidotale Retz. populações submetidas ao estresse da dessecação da zona radicular

Abstract Growth of plants is severely reduced due to water stress by affecting photosynthesis including photosystem II (PSII) activity and electron transport. This study emphasised on comparative and priority targeted changes in PSII activity due to progressive drought in seven populations of Panicum antidotale (P. antidotale) collected from Cholistan Desert and non-Cholistan regions. Tillers of equal growth of seven populations of P. antidotale grown in plastic pots filled with soil were subjected progressive drought by withholding water irrigation for three weeks. Progressive drought reduced the soil moisture content, leaf relative water content, photosynthetic pigments and fresh and dry biomass of shoots in all seven populations. Populations from Dingarh Fort, Dingarh Grassland and Haiderwali had higher growth than those of other populations. Cholistani populations especially in Dingarh Grassland and Haiderwali had greater ability of osmotic adjustment as reflected by osmotic potential and greater accumulation of total soluble proteins. Maximum H2O2 under water stress was observed in populations from Muzaffargarh and Khanewal but these were intermediate in MDA content. Under water stress, populations from Muzaffargarh and Dingarh Fort had greater K+ accumulation in their leaves. During progressive drought, non-Cholistani populations showed complete leaf rolling after 23 days of drought, and these populations could not withstand with more water stress condition while Cholistani populations tolerated more water stress condition for 31 days. Moreover, progressive drought caused PSII damages after 19 days and it became severe after 23 days in non-Cholistani populations of P. antidotale than in Cholistani populations.

Resumo O crescimento das plantas é severamente reduzido devido ao estresse hídrico, afetando a fotossíntese, incluindo a atividade do fotossistema II (PSII) e o transporte de elétrons. Este estudo enfatizou as mudanças comparativas e prioritárias na atividade do PSII devido à seca progressiva em sete populações de Panicum antidotale (P. antidotale) coletadas no Deserto do Cholistão e regiões fora do Cholistão. Perfilhos de igual crescimento de sete populações de P. antidotale cultivadas em vasos de plástico cheios de solo foram submetidos à seca progressiva, retendo a irrigação com água por três semanas. A seca progressiva reduziu o teor de umidade do solo, teor de água relativo nas folhas, pigmentos fotossintéticos e biomassa fresca e seca dos brotos em todas as sete populações. Populações de Dingarh Fort, Dingarh Grassland e Haiderwali tiveram maior crescimento do que as de outras populações. As populações de Cholistani, especialmente em Dingarh Grassland e Haiderwali, apresentaram maior capacidade de ajuste osmótico, refletido pelo potencial osmótico e maior acúmulo de proteínas solúveis totais. H2O2 máximo sob estresse hídrico foi observado em populações de Muzaffargarh e Khanewal, mas estas foram intermediárias no conteúdo de MDA. Sob estresse hídrico, as populações de Muzaffargarh e Dingarh Fort tiveram maior acúmulo de K+ em suas folhas. Durante a seca progressiva, as populações não cholistanesas mostraram rolagem completa das folhas após 23 dias de seca, e essas populações não conseguiram suportar mais condições de estresse hídrico, enquanto as populações cholistani toleraram mais condições de estresse hídrico por 31 dias. Além disso, a seca progressiva causou danos ao PSII após 19 dias e tornou-se severa após 23 dias em populações não cholistanesas de P. antidotale do que em populações cholistanesas.

Photosynthetic acclamatory response of Panicum antidotale Retz. populations to root zone desiccation stress

Abstract Growth of plants is severely reduced due to water stress by affecting photosynthesis including photosystem II (PSII) activity and electron transport. This study emphasised on comparative and priority targeted changes in PSII activity due to progressive drought in seven populations of Panicum antidotale (P. antidotale) collected from Cholistan Desert and non-Cholistan regions. Tillers of equal growth of seven populations of P. antidotale grown in plastic pots filled with soil were subjected progressive drought by withholding water irrigation for three weeks. Progressive drought reduced the soil moisture content, leaf relative water content, photosynthetic pigments and fresh and dry biomass of shoots in all seven populations. Populations from Dingarh Fort, Dingarh Grassland and Haiderwali had higher growth than those of other populations. Cholistani populations especially in Dingarh Grassland and Haiderwali had greater ability of osmotic adjustment as reflected by osmotic potential and greater accumulation of total soluble proteins. Maximum H2O2 under water stress was observed in populations from Muzaffargarh and Khanewal but these were intermediate in MDA content. Under water stress, populations from Muzaffargarh and Dingarh Fort had greater K+ accumulation in their leaves. During progressive drought, non-Cholistani populations showed complete leaf rolling after 23 days of drought, and these populations could not withstand with more water stress condition while Cholistani populations tolerated more water stress condition for 31 days. Moreover, progressive drought caused PSII damages after 19 days and it became severe after 23 days in non-Cholistani populations of P. antidotale than in Cholistani populations.

Resumo O crescimento das plantas é severamente reduzido devido ao estresse hídrico, afetando a fotossíntese, incluindo a atividade do fotossistema II (PSII) e o transporte de elétrons. Este estudo enfatizou as mudanças comparativas e prioritárias na atividade do PSII devido à seca progressiva em sete populações de Panicum antidotale (P. antidotale) coletadas no Deserto do Cholistão e regiões fora do Cholistão. Perfilhos de igual crescimento de sete populações de P. antidotale cultivadas em vasos de plástico cheios de solo foram submetidos à seca progressiva, retendo a irrigação com água por três semanas. A seca progressiva reduziu o teor de umidade do solo, teor de água relativo nas folhas, pigmentos fotossintéticos e biomassa fresca e seca dos brotos em todas as sete populações. Populações de Dingarh Fort, Dingarh Grassland e Haiderwali tiveram maior crescimento do que as de outras populações. As populações de Cholistani, especialmente em Dingarh Grassland e Haiderwali, apresentaram maior capacidade de ajuste osmótico, refletido pelo potencial osmótico e maior acúmulo de proteínas solúveis totais. H2O2 máximo sob estresse hídrico foi observado em populações de Muzaffargarh e Khanewal, mas estas foram intermediárias no conteúdo de MDA. Sob estresse hídrico, as populações de Muzaffargarh e Dingarh Fort tiveram maior acúmulo de K+ em suas folhas. Durante a seca progressiva, as populações não cholistanesas mostraram rolagem completa das folhas após 23 dias de seca, e essas populações não conseguiram suportar mais condições de estresse hídrico, enquanto as populações cholistani toleraram mais condições de estresse hídrico por 31 dias. Além disso, a seca progressiva causou danos ao PSII após 19 dias e tornou-se severa após 23 dias em populações não cholistanesas de P. antidotale do que em populações cholistanesas.

Measurement of an evaporation coefficient in tissue sections as a correction factor for 10B determination.

Boron neutron capture therapy (BNCT) is a cancer treatment option that combines preferential uptake of a boron compound in tumors and irradiation with thermal neutrons. For treatment planning, the boron concentration in different tissues must be considered. Neutron autoradiography using nuclear track detectors (NTD) can be applied to study both the concentration and microdistribution of boron in tissue samples. Histological sections are obtained from frozen tissue by cryosectioning. When the samples reach room temperature, they undergo an evaporation process, which leads to an increase in the boron concentration. To take this effect into account, certain correction factors (evaporation coefficients, CEv) must be applied. With this aim, a protocol was established to register and analyze mass variation of tissue sections, measured with a semimicro scale. Values of ambient temperature, pressure, and humidity were simultaneously recorded. Reproducible results of evaporation curves and CEv values were obtained for different tissue samples, which allowed the systematization of the procedure. This study could contribute to a more precise determination of boron concentration in tissue samples through the neutron autoradiography technique, which is of great relevance to make dosimetric calculations in BNCT.

Mortality, metabolic rate, and oviposition of Gryllus (Gryllus) assimilis (Fabricius, 1775) (Orthoptera: Gryllidae) females under constant and fluctuating warm temperatures.

The global average temperature will increase by up to 5.7 °C, under high greenhouse gas emissions, consequently increasing the frequency of heatwaves, according to recent IPCC forecasts. These especially impacts ectotherms, such as insects, which are the most susceptible animals to changes in environmental temperature, affecting their physiology and reproduction. Thus, we investigated the effects of a 96-h exposure to constant temperatures (CT: 27, 30.5, 34, 39, 41, or 43 °C) and fluctuating temperatures (FT: 27/34 °C, 12/12 h) on the survival, metabolic rate, and oviposition of the female cricket Gryllus (Gryllus) assimilis (Orthoptera: Gryllidae). Mortality, body mass and water content of females and males were quantified and compared. It was found that CT27, CT34 and FT27/34 do not cause mortality in females of G. (G.) assimilis. CT30.5 (average temperature between 27 and 34), despite causing mortality of 5.0 ± 3.5%, do not differ from CT27, CT34 or FT27/34. CT39 causes a mortality of 8.3 ± 5.5%. Estimated lethal temperature for 50% of the population of females (LT50Temp) is 40 °C, and 43 °C promotes 100% mortality in 96 h. Comparing mortality between sexes, females present higher LT50Temp and thermotolerance than males. In addition, FT27/34 and CT34 do not differ in the metabolic rate, but both have higher values than CT27. CT34 strongly reduces oviposition in females, however FT27/34 does not. We suggest that CT34 reduces oviposition in females in two ways: by affecting the endocrine system related to egg production, or by causing behavioral egg retention, as a strategy to survive thermal stress. Moreover, females had a higher wet body mass and present a lower average weight loss than males. In conclusion, despite females present a higher mortality at temperatures above 39 °C, they are more thermotolerant than males. Furthermore, CT34 is detrimental to the oviposition of G. (G.) assimilis.

Mass transfer modeling during wet salting of caiman meat (Caiman crocodilus yacare) at different brine temperatures.

Caiman meat is considered exotic and its consumption has significantly increased due to its nutritional quality. This study aimed to evaluate the kinetics of water content (WC) and salt content (SC) at different temperatures (1, 5, 10 and 15 °C) and to evaluate the use of mathematical models to predict the mass transfer kinetics until equilibrium conditions during the wet salting of caiman tail fillets. Moisture and chloride analyses were performed throughout the wet salting process. Four models (Peleg; Weibull; Zugarramurdi and Lupín; Diffusion) were tested to predict WC and SC kinetics in caiman tail fillets subjected to wet salting. The increase in the temperature resulted in a reduction (P < 0.05) in WC and an increase (P < 0.05) in SC. Nonlinear effects on WC and SC kinetics were observed between the different temperatures evaluated. Furthermore, the effective diffusion coefficients (Dw and Ds) increased (P < 0.05) with increasing temperature. Peleg, Weibull, Zugarramurdi and Lupín, and the Diffusion model satisfactorily represented WC and SC rates throughout the process. The kinetic behavior of the parameters of the models corroborated the effects of temperature on those parameters. Peleg was the best model for predicting WC and SC kinetics, and Zugarramurdi and Lupín was the best for predicting the equilibrium conditions of the process (WC∞ SC∞), all parameters which can be used to describe the mass transfer kinetics during wet salting of caiman tail fillets.

Time-domain transmission sensor system for on-site dielectric permittivity measurements in soil: A compact, low-cost and stand-alone solution.

Dielectric-based measurement techniques have been shown to be very effective in determining the properties of various materials. These techniques have been widely used in a variety of fields and applications. Time Domain Transmission (TDT) techniques have grown in popularity because they are practical, non-destructive, provide measurements in real time and produce accurate measurements that are independent of multiple reflections. TDT techniques, on the other hand, are mostly performed with specialized bulky laboratory equipment, such as a Vector Network Analyzer (VNA) which makes TDT measurements prohibitively costly and unpractical. In fact, few works in the literature have reported portable on-site TDT systems. The aim of this paper is to design and implement a dedicated, compact, and low-cost microwave Time Domain Transmission (TDT) sensor for measuring superficial soil dielectric properties on-site. Our sensor uses a time-delay measurement technique over a microstrip transmission line to estimate the dielectric properties of the soil under test. Measurement results show that the computed mean absolute error (MAE) is less than 1.2 when compared to a calibrated dielectric assessment kit (DAK) with soils containing less than 20 % of water ( ε ' r < 5.0 ), implying that our TDT sensor system can obtain on-site measurements in relatively dry soils with acceptable accuracy.

Bark and sapwood water storage and the atypical pattern of recharge and discharge of water reservoirs indicate low vulnerability to drought in Araucaria araucana.

Stored water in inner tissues influences the plant water economy, which might be particularly relevant for trees facing increasing dry conditions due to climate change. We studied the water storage in the inner bark and the sapwood of Araucaria araucana (Molina) K. Koch. This species has an extremely thick inner bark and thus it can be used as a model system to assess the impact of internal water storage on plant water balance. Specifically, we analyzed the water circulation pathways in and out of the elastic water storages by using simultaneously frequency domain moisture sensors and dendrometers inserted in the inner bark and in the sapwood, and sap flow determinations during the dry season. The daily patterns of water content and expansion and contraction of the stem tissues were similar to the sap flow pattern. The whole-stem water content and diameter increased in the morning and decreased in the afternoon, contrary to the typical pattern observed in most tree species. An osmotic gradient favoring the water influx from sapwood to inner bark was observed in the morning. There were no lags in the onset of sap flow between different stem heights at the time that recharge of reservoirs occurred. Sap flow at 6 m height was higher than basal sap flow in the afternoon, when the sapwood water content started to decline followed by the water content of the inner bark. Inner bark and sapwood contributed 5-11% to total daily transpiration, allowing the maintenance of high water potentials in the dry season. Our results suggest that the stored water in the stems, the atypical dynamic of recharge and discharge of water from reservoirs and the high tissue capacitance may make an important contribution to the survival of A. araucana during drought periods by maintaining the water balance.

Hydraulic conductivity and native embolism of Geneva® Series apple rootstocks measured by the XYL'EM-Plus® embolism meter

Most commercial apple orchards are established on either Marubakaido (Malus prunifolia Borkh.) (high vigor), M-9 (Malus pumila) (low vigor), or a combination of both rootstocks through the intergrafting technique. The Geneva® Series rootstocks were developed as an alternative to orchards modernization. The vigor of rootstocks influences the anatomical xylem formation and, therefore, the canopy cultivar's hydraulic conductivity. When affected by embolism, hydraulic conductivity harms plant metabolism, reducing crop yield and fruit quality. This study aimed to evaluate four Geneva® Series rootstocks with potential use in southern Brazil, in terms of hydraulic conductivity (K) and percentage loss of conductance (PLC), during the winter period in two different years. The G.213 rootstock presented the best performance for the variables analyzed; however, higher values of xylem functionality loss were observed in G.814.

Effect of the Soil Matric Potential on the Germination Capacity of Prosopis chilensis, Quillaja saponaria and Cryptocarya alba from Contrasting Geographical Origins.

As a consequence of the megadrought in Central Chile, it is expected that most of the distribution of woody species will be narrowed in the northern limits because of restrictions imposed by soil matric potential on seed germination. In this study, we analyzed the effect of the soil matric potential on seed germination and initial recruitment of the sclerophyllous species Prosopis chilensis, Quillaja saponaria and Cryptocarya alba from contrasting geographic origins (i.e., seed sources). We evaluated the germination capacity (%) under different matric potentials (i.e., 0, -6, -33, -750 and -1250 kPa) for 100 days. Soil matric potential of -1250 kPa negatively affected the germination capacity of the three species. P. chilensis seeds stopped germinating under soil matric potential close to -1200 kPa, whereas in Q. saponaria and C. alba the complete inhibition of germination was under -1000 kPa. Seed sources also differed in their germination capacity by soil matric potential: northern seed sources of P. chilensis germinated with the lowest soil matric potential. There was no clear trend in Q. saponaria and C. alba, but in general, southern seed sources performed better than the northern ones. The results showed that Ñ°m in the soil played an important role in the germinative capacity against different seed source origins, but not in soils with a north-south gradient.

Sorption Isotherms, Glass Transition and Bioactive Compounds of Ingredients Enriched with Soluble Fibre from Orange Pomace.

Citrus fruits are one of the main crops worldwide. Its industrialization, primarily juice production, produces large amounts of byproducts, composed of seeds and peels, that can be used to obtain new ingredients. In this study, sorption behaviour, glass transition, mechanical properties, colour and bioactives of four different soluble fibre-enriched powders obtained from orange pomace using green technologies were studied. Powders were equilibrated at water activities between 0.113 and 0.680 for fifteen weeks at 20 °C, and studies were performed to indicate the best storing conditions to ensure the glassy state of the amorphous matrix and higher bioactive stability. By combining the Gordon and Taylor model with the Henderson isotherm, the critical water activity and content for storage in a glassy state were determined. The ingredient obtained after extrusion + hot water is the most stable, which is also the one with the highest dietary fibre content. Powder obtained by jet cooking is the least stable, as it is not in a glassy state at any water activity at room temperature. To increase storage stability, these should be stored at refrigeration temperatures.

Nonlinear models for soil moisture sensor calibration in tropical mountainous soils

Electromagnetic sensors are widely used to monitor soil water content (θ); however, site-specific calibrations are necessary for accurate measurements. This study compares regression models used for calibration of soil moisture sensors and investigates the relation between soil attributes and the adjusted parameters of the specific calibration equations. Undisturbed soil samples were collected in the A and B horizons of two Ultisols and two Inceptisols from the Mantiqueira Range in Southeastern Brazil. After saturation, the Theta Probe ML2X was used to obtain the soil dielectric constant (ε). Several readings were made, ranging from saturation to oven-dry. After each reading, the samples were weighted to calculate θ (m³ m-³). Fourteen regression models (linear, linearized, and nonlinear) were adjusted to the calibration data and checked for their residue distribution. Only the exponential model with three parameters met the regression assumptions regarding residue distribution. The stepwise regression was used to obtain multiple linear equations to estimate the adjusted parameters of the calibration model from soil attributes, with silt and clay contents providing the best relations. Both the specific and the general calibrations performed well, with RMSE values of 0.02 and 0.03 m³ m-³, respectively. Manufacturer calibration and equations from the literature were much less accurate, reinforcing the need to develop specific calibrations.

An Ultrasonic-Capacitive System for Online Characterization of Fuel Oils in Thermal Power Plants.

This paper presents a ultrasonic-capacitive system for online analysis of the quality of fuel oils (FO), which are widely used to produce electric energy in Thermal Power Plants (TPP) due to their elevated heating value. The heating value, in turn, is linked to the quality of the fuel (i.e., the density and the amount of contaminants, such as water). Therefore, the analysis of the quality is of great importance for TPPs, either in order to avoid a decrease in generated power or in order to avoid damage to the TPP equipment. The proposed system is composed of two main strategies: a capacitive system (in order to estimate the water content in the fuel) and an ultrasonic system (in order to estimate the density). The conjunction of the two strategies is used in order to estimate the heating value of the fuel, online, as it passes through the pipeline and is an important tool for the TPP in order to detect counterfeit fuel. In addition, the ultrasonic system allows the estimation of the flow rate through the pipeline, hence estimating the amount of oil transferred and obtaining the total mass transferred as a feature of the system. Experimental results are provided for both sensors installed in a TPP in Brazil.

Identification of Sorghum (Sorghum bicolor (L.) Moench) Genotypes with Potential for Hydric and Heat Stress Tolerance in Northeastern Mexico.

Sorghum (Sorghum bicolor (L.) Moench) is cultivated in regions with frequent drought periods and high temperatures, conditions that have intensified in the last decades. One of the most important photosynthetic components, sensible to hydric stress, is maximum quantum yield for photosystem II (PSII, or Fv/Fm). The objective of the present study was to identify sorghum genotypes with tolerance to hydric and heat stress. The treatments were hydric status (hydric stress or non-hydric stress (irrigation)), the plant's developmental stages (pre or post-anthesis), and six genotypes. The response variables were Fv/Fm; photosynthetic rate (PN); stomatal conductance (gs); transpiration rate (E); relative water content (RWC); damage to cell membrane (DCM) at temperatures of 40 and 45 °C; and agronomic variables. The experiment was conducted in pots in open sky in Marín, N.L., in the dry and hot northeast Mexico. The treatment design was a split-split plot design, with three factors. Hydric stress diminished the functioning of the photosynthetic apparatus by 63%, due to damage caused to PSII. Pre-anthesis was the most vulnerable stage to hydric stress as it decreased the weight of grains per panicle (85%), number of grains per panicle (69%), and weight of 100 grains (46%). Genotypes LER 1 and LER 2 were identified as tolerant to hydric stress, as they had lower damage to PSII; LER 1 and LEB 2 for their superior RWC; and LER 1 as a thermo tolerant genotype, due to its lower DCM at 45 °C. It was concluded that LER 1 could have the potential for both hydric and heat stress tolerance in the arid northeast Mexico.

Water Content Monitoring in Water-in-Crude-Oil Emulsions Using an Ultrasonic Multiple-Backscattering Sensor.

This work shows the application of an ultrasonic multiple-scattering sensor for monitoring water-in-petroleum emulsions. The sensor consists of a commercial ultrasonic transducer with an array of cylindrical scatterers placed in the near field. The scatterers are thin metal bars arranged in rows in front of the transducer. The backscattering signals were analyzed by calculating the wave energy and by a cross-correlation between signal segments; they were also used to determine the propagation velocity in the emulsions. The tests performed used emulsions with water volume concentrations from 0% to 50%. The results showed that both the signal energy and propagation velocity strongly depended on the concentration of water in the emulsion. Therefore, the ultrasonic multiple-scattering sensor can be used for on-line and real-time monitoring of the water content in water-in-crude-oil emulsions.

Resveratrol prevents brain edema, blood-brain barrier permeability, and altered aquaporin profile in autism animal model.

Autism spectrum disorder can present a plethora of clinical conditions associated with the disorder, such as greater brain volume in the first years of life in a significant percentage of patients. We aimed to evaluate the brain water content, the blood-brain barrier permeability, and the expression of aquaporin 1 and 4, and GFAP in a valproic acid-animal model, assessing the effect of resveratrol. On postnatal day 30, Wistar rats of the valproic acid group showed greater permeability of the blood-brain barrier to the Evans blue dye and a higher proportion of brain water volume, prevented both by resveratrol. Prenatal exposition to valproic acid diminished aquaporin 1 in the choroid plexus, in the primary somatosensory area, in the amygdala region, and in the medial prefrontal cortex, reduced aquaporin 4 in medial prefrontal cortex and increased aquaporin 4 levels in primary somatosensory area (with resveratrol prevention). Valproic acid exposition also increased the number of astrocytes and GFAP fluorescence in both primary somatosensory area and medial prefrontal cortex. In medial prefrontal cortex, resveratrol prevented the increased fluorescence. Finally, there was an effect of resveratrol per se on the number of astrocytes and GFAP fluorescence in the amygdala region and in the hippocampus. Thus, this work demonstrates significant changes in blood-brain barrier permeability, edema formation, distribution of aquaporin 1 and 4, in addition to astrocytes profile in the animal model of autism, as well as the use of resveratrol as a tool to investigate the mechanisms involved in the pathophysiology of autism spectrum disorder.

Leaf surface water, not plant water stress, drives diurnal variation in tropical forest canopy water content.

Variation in canopy water content (CWC) that can be detected from microwave remote sensing of vegetation optical depth (VOD) has been proposed as an important measure of vegetation water stress. However, the contribution of leaf surface water (LWs ), arising from dew formation and rainfall interception, to CWC is largely unknown, particularly in tropical forests and other high-humidity ecosystems. We compared VOD data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and CWC predicted by a plant hydrodynamics model at four tropical sites in Brazil spanning a rainfall gradient. We assessed how LWs influenced the relationship between VOD and CWC. The analysis indicates that while CWC is strongly correlated with VOD (R2  = 0.62 across all sites), LWs accounts for 61-76% of the diurnal variation in CWC despite being < 10% of CWC. Ignoring LWs weakens the near-linear relationship between CWC and VOD and reduces the consistency in diurnal variation. The contribution of LWs to CWC variation, however, decreases at longer, seasonal to inter-annual, time scales. Our results demonstrate that diurnal patterns of dew formation and rainfall interception can be an important driver of diurnal variation in CWC and VOD over tropical ecosystems and therefore should be accounted for when inferring plant diurnal water stress from VOD measurements.

Morphological, molecular and ecological characterization of a native isolate of Steinernema feltiae (Rhabditida: Steinernematidae) from southern Chile.

BACKGROUND: Steinernema feltiae is an entomopathogenic nematode used in biological control programs with a global distribution. Populations of this species show phenotypic plasticity derived from local adaptation and vary in different traits, such as location and host penetration. The aim of this work was to describe a Chilean isolate of this nematode species, using integrative approaches. METHODS: Nematode morphological and morphometric studies were conducted along with molecular analysis of nuclear genes. The symbiotic bacterium was also identified by sequencing the 16S rRNA gene. Some ecological characteristics were described, including the temperature requirements for the nematode life cycle and the effect of soil water content for optimal reproduction. RESULTS: Morphometric characterization revealed a large intra-specific variability. The isolate identity was also corroborated with the analysis of nuclear genes. Based on the 16S gene, its symbiont bacteria, Xenorhabdus bovienii, was identified. The lowest, optimal and highest temperatures found to limit the infestation and reproduction on Galleria mellonella were 10, 20 and 30 °C, respectively; the emergence from the host larvae occurred approximately 10 days after inoculation. Differences were observed in offspring, and 120 infective juveniles (IJ)/larva was the most prolific dose at 20 °C. The soil water content did not affect the number of IJ invaders, penetration efficacy and IJ emergence time or offspring per larva, but it caused a delay in achieving full mortality at the permanent wilting point with respect to saturation and field capacity. CONCLUSIONS: For the first time, a Chilean isolate of S. feltiae is described in detail considering morphological, molecular and ecological aspects. The isolate was shown to be efficient in soil containing water, with optimal temperatures ranging from 15 to 25 °C for host infestation and production of an abundant offspring; these characteristics would allow its potential use as control agents in a wide geographical area of the country.

Measuring land surface temperature, near-infrared and short-wave infrared reflectance for estimation of water availability in vegetation.

The vegetation water status is a crucial variable for modelling of drought impact, vegetation productivity and water fluxes. Methods for spatial estimation of this variable still need to be improved. The integration of remotely sensed data of land surface temperature (LST) and water vegetation indices based on near-infrared (NIR) and short-wave infrared (SWIR) reflectance for estimation of vegetation water content and water available for evapotranspiration require more analysis. This study contains a detailed method and measurements of LST, NIR and SWIR reflectance of soybean, corn and barley taken in field campaigns in central Argentine Pampas and laboratory with a ST PRO Raytek (8-14 µm) and a spectrometer SVC HR-1024i (0.35 and 2.5 µm). Also, relative water content of leaves was measured in laboratory during the dehydration process. This method and dataset could be also used for researching other wavelengths between 0.35 and 2.5 µm as indicator of water vegetation status (e.g. solar-induced chlorophyll fluorescence, photosynthesis).•Procedures useful to measure field spectra of vegetation are presented.•Not only the traditional method to measure leaves spectra in laboratory, but also in field were applied.•The method allows the integration of spectra and thermal data as a proxy of vegetation water status.