Mecanismos de resiliência à seca em florestas tropicais na Amazônia

Orientador: Rafael Silva OliveiraTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Cenários de mudança climática sugerem que a precipitação e os níveis de umidade do solo mudarão em muitas áreas da bacia amazônica, entretanto ainda há alta incerteza quanto à confiança nas previsões dos modelos. Nesta região, secas severas que causam um grande evento de mortalidade de árvores ocorrem frequentemente durante El-Niño (oscilação climática induzindo eventos de seca). Nesse trabalho, nosso objetivo foi compreender as estratégias de uso da água e do balanço de C que conferem maior ou menor resiliência à seca entre as espécies amazônicas. Esta tese está dividida em três capítulos (C1, C2 e C3). C1) Monitoramos o uso de água de árvores usando sensores de fluxo de seiva em uma floresta fragmentada na Tailândia, Pará. Estávamos interessados em entender os determinantes ambientais que controlam a transpiração da floresta (Tfloresta), também se esses condicionantes atuam de modo diferente durante a estação úmida (EU) versus estação seca (ES) durante um ano de El-Niño (2015). As árvores do dossel contribuíram mais para o Tfloresta do que as árvores do sub-dossel. Em geral, o uso de água pelas árvores foi muito maior durante a ES. Portanto, a floresta pode suportar a ES sem restrição de transpiração causada pela redução da umidade do solo superficial. Houve um efeito primordial do déficit de pressão de vapor (VPD) nos padrões de uso da água em relação à umidade do solo. C2) Avaliamos uma série de atributos hidráulicos estruturais e fisiológicos que determinam as estratégias de tolerância/evasão à seca entre as espécies de árvores da floresta sazonal do Tapajós, PA. Avaliamos a profundidade do enraizamento utilizando isótopos estáveis da água (delta18O e delta²H), medimos o potencial hídrico mínimo foliar na estação seca em um ano normal (2014; Psi normal) e em um ano de seca extrema (2015; PsiEl-Niño). Além disso, medimos os traços hidráulicos do xilema que descrevem a segurança do transporte de água no xilema (P50 e P88). Demonstramos que existe segregação de nicho hidrológico entre as árvores o que permite maior coexistência de espécies. Essa segregação de nicho é definida pelo tamanho das árvores, por diferenças na profundidade das raízes e pela tolerância à potenciais hídricos mais negativos. A profundidade das raízes explicou 49% da variação em P50 e 70% de P88, com maior tolerância ao baixo potencial hídrico em espécies de raízes rasas, enquanto a profundidade radicular explicou 47% e 77% da variação de Psinormal e PsiEl-Niño. C3) Avaliamos o balanço sazonal e interanual (2013-2015) de carboidratos não estruturais (CNE) em folhas, ramos, troncos e raízes de diferentes espécies de árvores com estratégias contrastantes de tolerância à seca na Floresta Nacional do Tapajós , estacional. O esgotamento total de CNE durante as estações foi raro. A concentração média mínima de açúcares solúveis (SS) e amido (ST) variaram de 5% a 80% em relação ao máximo sazonal em todos os órgãos. O ST atingiu a concentração mínima mais do que SS em termos absolutos e relativos principalmente em folhas e ramos. Houve diferenças na magnitude da concentração média e mínima de SS e ST entre os órgãos entre árvores do dossel e sub-dossel. Apesar disso, a flutuação sazonal do CNE ao longo dos anos não foi uniforme, os achados mais consistentes nesta pesquisa foram as altas respostas específicas de espécies na flutuação do CNE em diferentes órgãos. Entretanto, essa flutuação não foi impulsionada pelo déficit hídrico climático na maioria dos casos. O efeito principal dos atributos funcionais hidráulicos foi sobre o acúmulo de açúcares solúveis durante a ES do ano de El-Niño. Além disso, houve maior importância para manter um maior armazenamento ST entre as espécies tolerantes à seca que são submetidas por mais estresse hídrico no leste da AmazôniaAbstract: Climate change scenarios suggest that rainfall and soil moisture levels will change in many areas of the Amazon basin. However, still there is high uncertainty related to confidence in the modelling predictions. In this region, severe droughts frequently occur during El-Niño (ENSO; Southern Oscillation inducing drought events) which causes a large tree mortality event. Here, our objective was to understanding the tree strategies that determine drought resilience among Amazon species. This document was divided in three chapters (C1, C2, and C3). C1 - We monitored trees water use using sap flow sensors in an amazon forest at Tailandia, Para. We were interested to understanding the environmental drivers controlling tree stand transpiration (Tstand) and if these drivers exert different controls over tree transpiration during the wet season (WS) versus dry season (DS) during an ENSO year (2015/2016). The canopy trees contributed more to Tstand than subcanopy trees. Overall, trees water use was much higher during DS, thus the forest can withstand the observed DS without restriction on transpiration caused by reduced soil moisture on shallow soil. There was an overriding effect of vapour pressure deficit (VPD) on water use patterns relative to soil moisture. C2 - We evaluated a range of of structural and physiological hydraulic traits that determine the drought tolerance/avoidance strategies among tree species from seasonal Tapajós forest. We assessed rooting depth using water stable isotope ratios (delta18O and delta²H), measured the minimum dry-season leaf water potential in a normal year (2014;Psy non-ENSO) and in an extreme drought year (2015; PsyENSO). Furthermore, we measured xylem hydraulic traits that describe xylem water transport without risking hydraulic failure (P50 and P88). We demonstrate that coexisting trees are largely segregated along a single hydrological niche axis defined by tree size and root depth differences, associated to the tolerance of low water potential. The delta18O of xylem water explained 49% and 70% of the variation in P50 and P88, respectively, and explained 47% and 77% of the variation of minimum Psynon-ENSO and PsyENSO. C3 - We assessed the seasonal and year-to-year (2013-2015) balance of non-structural carbohydrates (NSC) in leaves, branches, trunks and roots among species with contrasting drought tolerance strategies in seasonal Tapajós National Forest. The seasonal depletion of total NSC was rare, the average minimum soluble sugar (SS) and starch (ST) remain between 5% to 80% of seasonal maximum among all organs. The ST reached the minimum concentration more than SS on both absolute and relative terms mainly on leaves and branches. There was differences on the magnitude of average and minimum SS and ST concentration among organs of understory and overstory trees. Despite this, the seasonal NSC fluctuation over the years was not uniform, the most consistent findings in this research was the high specie-specific responses on the NSC fluctuation in different organs. Even though, this fluctuation was not drive by climatic water deficit in the majority of cases. The main effect of functional hydraulic traits was over the soluble sugar accumulation during the DS of ENSO year. Furthermore, there was higher importance of maintain much higher average ST storage in drought-tolerant species which are submitted by more water stress in eastern AmazonDoutoradoEcologiaDoutor em EcologiaCAPE

NUTRIÇÃO, OBESIDADE E A BOA ALIMENTAÇÃO NAS FASES INICIAIS DA VIDA

A alimentação adequada é imprescindível em qualquer idade, no entanto,o processo de transição nutricional tem contribuído desfavoravelmente paraa boa alimentação desde as fases iniciais da vida. O projeto de extensão foirealizado na E. E B. Henrique Rupp Junior, com as turmas de educaçãobásica e é fruto de uma parceria com o curso de Nutrição da Unoesc Videiracom a Klaus LTDA - Atacado de frutas e verduras. O objetivo é promover aeducação nutricional nas fases iniciais da vida na forma da boaalimentação, além de proporcionar informações e realizar atividades deeducação nutricional com crianças em idade escolar, visando à promoçãoda saúde, com a aquisição de hábitos alimentares saudáveis, formandoassim, agentes de transformação de uma comunidade sedentária emsaudável.1 INTRODUÇÃ

Ryegrass seed viability in function of phenological stage of herbicides application

O azevém é uma importante planta daninha na cultura do milho e em cereais de inverno. O surgimento de biótipos resistentes ao glyphosate, principal herbicida utilizado no sistema agrícola brasileiro, e a capacidade de ressemeadura natural, tem-se suscitado a necessidade de buscar alternativas para minimizar o reabastecimento do banco de sementes dessa espécie. O objetivo deste trabalho foi avaliar o efeito da aplicação de herbicidas em diferentes estádios fenológicos de plantas de azevém sensível ao glyphosate, sobre a viabilidade das sementes originadas dessas plantas. Para tal, plantas de azevém foram submetidas à aplicação da associação dos herbicidas glyphosate e clethodim (750 g e.a. ha-1 + 120g i.a. ha-1, respectivamente) em 10 diferentes estádios de desenvolvimento. As sementes produzidas foram avaliadas quanto a sua viabilidade em teste de tetrazólio; germinação em câmara de crescimento tipo B.O.D. com posterior teste de tetrazólio e emergência de plantas em substrato de turfa. Os resultados indicam que a época limite de dessecação do azevém para que não produza sementes viáveis é o estádio anterior à antese completa, sendo que neste estádio ocorreu a redução total da viabilidade, germinação e emergência das sementes de azevém expostas a aplicação da associação de glyphosate + clethodim.Ryegrass is an important weed in maize crops and winter cereals. The emergence of glyphosate-resistant biotypes, the main herbicide used in the Brazilian agricultural system, and the ability of natural reseeding, have raised the need to seek alternatives to minimize seed bank replenishment of this species. The objective of this study was to evaluate the effect of herbicide application at different growth stages of glyphosate-sensitive ryegrass plants on the viability of seeds from these plants. To this end, ryegrass plants were submitted to the application of glyphosate and clethodim association (750 g a.e. ha-1 + 120 g a.i. ha-1, respectively) in 10 in different development stages. The seeds produced were evaluated for their viability in tetrazolium test and germination in a B.O.D (Biochemical Oxygen Demand)-type growth chamber, with subsequent tetrazolium test and plants emergence in peat substrate. The results indicate that desiccation time limit for ryegrass to not produce viable seeds is the stage prior to complete anthesis, and at this stage there was complete reduction of viability, germination and emergence of ryegrass seeds exposed to the application of glyphosate + clethodim association

Resveratrol prevents cellular and behavioral sensory alterations in the animal model of autism induced by valproic acid

Autism spectrum disorder (ASD) is characterized by impairments in both social communication and interaction and repetitive or stereotyped behaviors. Although its etiology remains unknown, genetic and environmental risk factors have been associated with this disorder, including the exposure to valproic acid (VPA) during pregnancy. Resveratrol (RSV) is an anti-inflammatory and antioxidant molecule known to prevent social impairments in the VPA animal model of autism. This study aimed to analyze the effects of prenatal exposure to VPA, as well as possible preventive effects of RSV, on sensory behavior, the localization of GABAergic parvalbumin (PV+) neurons in sensory brain regions and the expression of proteins of excitatory and inhibitory synapses. Pregnant rats were treated daily with RSV (3.6 mg/kg) from E6.5 to E18.5 and injected with VPA (600 mg/kg) in the E12.5. Male pups were analyzed in nest seeking behavior and in whisker nuisance task. At P30, the tissues were removed and analyzed by immunofluorescence and western blotting. Our data showed for the first time an altered localization of PV+-neurons in primary sensory cortex and amygdala. We also showed a reduced level of gephyrin in the primary somatosensory area of VPA animals. The treatment with RSV prevented all the aforementioned alterations triggered by VPA. Our data shed light on the relevance of sensory component in ASD and highlights the interplay between RSV and VPA animal model as an important tool to investigate the pathophysiology of ASD

Hydrological niche segregation defines forest structure and drought tolerance strategies in a seasonal Amazon forest

The relationship between rooting depth and above‐ground hydraulic traits can potentially define drought resistance strategies that are important in determining species distribution and coexistence in seasonal tropical forests, and understanding this is important for predicting the effects of future climate change in these ecosystems.We assessed the rooting depth of 12 dominant tree species (representing c. 42% of the forest basal area) in a seasonal Amazon forest using the stable isotope ratios (δ18O and δ2H) of water collected from tree xylem and soils from a range of depths. We took advantage of a major ENSO‐related drought in 2015/2016 that caused substantial evaporative isotope enrichment in the soil and revealed water use strategies of each species under extreme conditions. We measured the minimum dry season leaf water potential both in a normal year (2014; Ψnon‐ENSO) and in an extreme drought year (2015; ΨENSO). Furthermore, we measured xylem hydraulic traits that indicate water potential thresholds trees tolerate without risking hydraulic failure (P50 and P88).We demonstrate that coexisting trees are largely segregated along a single hydrological niche axis defined by root depth differences, access to light and tolerance of low water potential. These differences in rooting depth were strongly related to tree size; diameter at breast height (DBH) explained 72% of the variation in the δ18Oxylem. Additionally, δ18Oxylem explained 49% of the variation in P50 and 70% of P88, with shallow‐rooted species more tolerant of low water potentials, while δ18O of xylem water explained 47% and 77% of the variation of minimum Ψnon‐ENSO and ΨENSO.We propose a new formulation to estimate an effective functional rooting depth, i.e. the likely soil depth from which roots can sustain water uptake for physiological functions, using DBH as predictor of root depth at this site. Based on these estimates, we conclude that rooting depth varies systematically across the most abundant families, genera and species at the Tapajós forest, and that understorey species in particular are limited to shallow rooting depths.Our results support the theory of hydrological niche segregation and its underlying trade‐off related to drought resistance, which also affect the dominance structure of trees in this seasonal eastern Amazon forest.Synthesis. Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/1/jec13022_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/2/jec13022.pd

Hydrological niche segregation defines forest structure and drought tolerance strategies in a seasonal Amazon forest

The relationship between rooting depth and above‐ground hydraulic traits can potentially define drought resistance strategies that are important in determining species distribution and coexistence in seasonal tropical forests, and understanding this is important for predicting the effects of future climate change in these ecosystems.We assessed the rooting depth of 12 dominant tree species (representing c. 42% of the forest basal area) in a seasonal Amazon forest using the stable isotope ratios (δ18O and δ2H) of water collected from tree xylem and soils from a range of depths. We took advantage of a major ENSO‐related drought in 2015/2016 that caused substantial evaporative isotope enrichment in the soil and revealed water use strategies of each species under extreme conditions. We measured the minimum dry season leaf water potential both in a normal year (2014; Ψnon‐ENSO) and in an extreme drought year (2015; ΨENSO). Furthermore, we measured xylem hydraulic traits that indicate water potential thresholds trees tolerate without risking hydraulic failure (P50 and P88).We demonstrate that coexisting trees are largely segregated along a single hydrological niche axis defined by root depth differences, access to light and tolerance of low water potential. These differences in rooting depth were strongly related to tree size; diameter at breast height (DBH) explained 72% of the variation in the δ18Oxylem. Additionally, δ18Oxylem explained 49% of the variation in P50 and 70% of P88, with shallow‐rooted species more tolerant of low water potentials, while δ18O of xylem water explained 47% and 77% of the variation of minimum Ψnon‐ENSO and ΨENSO.We propose a new formulation to estimate an effective functional rooting depth, i.e. the likely soil depth from which roots can sustain water uptake for physiological functions, using DBH as predictor of root depth at this site. Based on these estimates, we conclude that rooting depth varies systematically across the most abundant families, genera and species at the Tapajós forest, and that understorey species in particular are limited to shallow rooting depths.Our results support the theory of hydrological niche segregation and its underlying trade‐off related to drought resistance, which also affect the dominance structure of trees in this seasonal eastern Amazon forest.Synthesis. Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/1/jec13022_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146869/2/jec13022.pd

Effects of single-dose antipurinergic therapy on behavioral and molecular alterations in the valproic acid-induced animal model of autism

Autism spectrum disorder (ASD) is characterized by deficits in communication and social interaction, restricted interests, and stereotyped behavior. Environmental factors, such as prenatal exposure to valproic acid (VPA), may contribute to the increased risk of ASD. Since disturbed functioning of the purinergic system has been associated with the onset of ASD and used as a potential therapeutic target for ASD in both clinical and preclinical studies, we analyzed the effects of suramin, a non-selective purinergic antagonist, on behavioral, molecular and immunological in an animal model of autism induced by prenatal exposure to VPA. Treatment with suramin (20 mg/kg, intraperitoneal) restored sociability in the three-chamber apparatus and decreased anxiety measured by elevated plus maze apparatus, but had no impact on decreased reciprocal social interactions or higher nociceptive threshold in VPA rats. Suramin treatment had no impact on VPA-induced upregulation of P2X4 and P2Y2 in hippocampus, and P2X4 in medial prefrontal cortex, but normalized an increased level of interleukin 6 (IL-6). Our results suggest an important role of purinergic modulation in behavioral, molecular, and immunological aberrations described in VPA model, and suggest that purinergic system might be a potential target for pharmacotherapy in preclinical studies of ASD