Proyectos

Microplastics (MPs) are plastic particles that range in size from 0.1 μm to 5 mm. They have received widespread attention in the global environmental science community due to their potential effects on living organisms, ecosystem pollution, low recycling rate, and interaction with organic and inorganic contaminants. Although much research has been focused on MPs in aquatic ecosystems, terrestrial ecosystems have been largely overlooked. Consequently, there is still scarce knowledge on the sources and occurrence of MPs in soils. After being deposited in soil, MPs undergo an aging process that involves the breakdown of their polymeric chains, which promotes the interaction between MPs and organic and inorganic contaminants. This process further increases the toxicity of MPs when they sorb pollutants from the environment, which can be transported to water bodies and living organisms. However, research regarding the aging of MPs and their toxicity is needed since previous studies do not consider realistic soil conditions. Additionally, interactions between MPs and pollutants have been primarily studied for conventional MPs, with scarce research on such topics for degradable MPs, especially concerning interactions with metal(loid)s. In general, the interaction of degradable MPs with other contaminants and their further toxicity have been overlooked. MPs have been shown to negatively affect some physical, chemical, and biological soil properties. However, results varied between studies, which have been associated with the type and shape of MPs, soil aggregate structure, porosity, water and oxygen availability, among others. More research is needed to confirm such relationships in soils. Previous studies have been mainly performed in Europe and Asia, with scarce research in Latin America. In Chile, only one study has been conducted on MPs in soils at field conditions, with other two studies regarding the effect of MPs and metals on soil biochemical properties under controlled environments. Therefore, considerable efforts should be taken to study MPs in Chilean soils. Thus, this study aims to address these gaps by considering some realistic approaches that are missing from current research on MPs. Specifically, this research will: 1) assess MPs in soils from different land uses and examine their association with soil properties; 2) evaluate degradable MPs; 3) study the ageing and adsorption capability of different MPs to metal(loid)s in soils; and 4) investigate the interactive effect of MPs and metal(loid)s under realistic conditions (including a real dose of MPs and metal(loid)s, temperature fluctuations, and soils from different land use types). By taking these steps, this study will provide novel insights into the occurrence of MPs in Chilean soils and shed light on the dynamics of soil microbial communities in the presence of MPs and metal(loid)s. Based on the above, the proposed research aims to evaluate the effect of different types of MPs and their interaction with metal(loid)s on the soil community structure and functionality from different land use types under realistic conditions. The hypothesis is that MPs will negatively affect soil microbiome structure and functionality due to changes in soil physicochemical properties, which will be moderated by changes in the type, doses, ageing of MPs and their interactions with metal(loid)s in soil from different land type uses. This proposal will be conducted in the O’Higgins Region (VI) of Chile. Firstly, in Phase 1, six localities from different land use types will be selected: an urban wetland, agricultural field, and sclerophyll forest. Soil samples will be taken to quantify and characterize the types of MPs in soil. Secondly, in Phase 2, the evaluation of different types of aging of MPs (conventional and degradable) on chemical characteristics of such particles will be performed, which is based on the ability of MPs as carriers of metal(loid)s. With information and soils obtained from Phase 1, a realistic experimental approach will be performed in the Phase 3. These include the evaluation of aged MPs (degradable and non-degradable) on soil physicochemical and biochemical properties, and the study of degradable and non-degradable aged MPs with metal(loid)s on the functionality, structure, and co-occurrence patterns of soil microbial communities. These phases are designed to be performed over three years. This is the first study focused on the evaluation the effect of MPs and metal(loid)s on microbial communities of soils from different land use types in Chile.

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Exploring and elucidating the interplays between dissolved organic matter and microbial communities along an aquatic continuum: from the Andes to the ocean

La presente propuesta de investigación busca identificar el impacto de las condiciones políticas en que se llevan a cabo las protestas sobre el apoyo que la población general pudiese brindar al uso de la fuerza por parte de Carabineros en la gestión del orden público durante la crisis de seguridad que enfrenta el país desde marzo de 2022. Así, se espera explorar las condiciones (restricción/facilitación de manifestaciones por parte de las autoridades; cobertura periodística de manifestaciones; empleo de acciones violentas por parte de manifestantes; presencia de manifestantes y carabineros heridos; destrucción de infraestructura pública) que las personas podrían tomar en consideración para (des) legitimar el empleo de la fuerza por parte de Carabineros en tiempos en que la confianza en la principal institución a cargo del orden público en Chile se ha restaurado paulatinamente luego de una actuación marcada por el uso desproporcionado de la fuerza durante el Estallido Social de 2019. Junto con lo anterior, vale la pena señalar que, al momento de elaborar esta propuesta de investigación, se discuten proyectos de ley tendientes a reforzar las atribuciones de Carabineros asociadas al uso de la fuerza para hacer frente tanto a delitos de alta connotación social como a ataques a efectivos policiales durante manifestaciones. Tomando en cuenta lo descrito más arriba, esta investigación espera además ayudar a clarificar los mecanismos psicológicos y políticos que permitirían a las personas lidiar entre la adhesión (o acuerdo) con el derecho a protesta que debe ser resguardado y promovido por las autoridades en un régimen democrático, con la (aparente) necesidad de que Carabineros pueda realizar un mayor uso discrecional de la fuerza para asegurar la gestión del orden y seguridad pública.

En esta propuesta consideramos que la prospección y detección temprana de fitopatógenos constituye una iniciativa altamente necesaria de abordar de una manera colaborativa e integrada con los productores y otros integrantes del sistema olivícola. Lo anterior, debido a que hay escaza información sobre los patógenos bacterianos y virales que atacan al cultivo del olivo en Chile, como así también, de los insectos vectores que se asocian con la diseminación de estos. Por otra parte, la información disponible a nivel nacional se condice con acciones aisladas y reactivas, es decir, que una vez se presenta el problema se actúa en consecuencia.  Realizar prospecciones colaborativas con actores del sistema productivo, periódicas y preventivas serán significativas para aplicar medidas de gestión y/o manejo y cuarentena. En el hecho, la bacteria Xylella fastidiosa (agente causal del síndrome de declive rápido del olivo; OQDS), se encuentra ausente para el cultivo del olivo en Chile, no obstante, existe un alto riesgo de ingreso y propagación de esta bacteria si no se realiza una vigilancia activa, en particular, del material de propagación y en maquinaria agrícola que proviene de países europeos donde el impacto de esta bacteria en olivos centenarios ha sido significativo, como lo ocurrido en la región de Apulia (Italia).  Adquirir mayor información de como el cambio climático acelerado impacta en la incidencia de enfermedades emergentes, y en fitopatogenos que se encuentran en estado de latencia en el cultivo del olivo. En este aspecto, se desconoce el efecto en la distribución e impacto de muchos fitopatógenos, lo que consideramos es de alto riesgo para la seguridad alimentaria y sostenibilidad de la producción, en este caso de la olivicultura y oleicultura.  Proveer de información relevante para sostener una total y profunda vigilancia que permita al SAG asegurar que la maquinaria agrícola que ingresa a territorio nacional, se encuentre exenta de material vegetal contaminado de procedencia. Para labores de cosecha se ha optado por el ingreso de maquinaria agrícola (regulado por normativas vigentes) proveniente de países europeos (principalmente España) donde se ha reportado enfermedades asociadas a virus y bacterias fitopatógenas de carácter cuarentenario para Chile; esta situación involucra un alto riesgo para la sanidad de los olivos de la región y del país.  Contribuir en informar y educar a los productores, asesores técnicos e identidades públicas que forman parte del sistema productivo olivícola de la región de O’Higgins en tópicos de fitosanidad del cultivo del olivo, entregará herramientas y mayor comprensión de los fenómenos asociados a la salud del olivo en condiciones locales. Por otra parte, los desafíos que deben resolver los productores en materia de fitosanidad pueden en algunas oportunidades ser limitadas o deficientes por falta de información, y en consecuencia no determinar la estrategia o táctica más apropiada para el control de enfermedades en plantas.  También, notamos del Diagnostico territorial participativo un gran interés por parte de los productores en proteger la salud de sus olivos, a través de la detección temprana de problemas fitosanitarios que eviten una contaminación masiva en olivos propios y vecinos.

The recently awarded Fondecyt Iniciación no. 11241126 (PI Jorge Romero) aims to determine the distribution and geometry of slope instability and its controlling factors (i.e., textural and compositional characteristics of rocks, their mass structure and discontinuities, and their mechanical rock properties) at the San José and Nevados de Chillán Volcanic Complexes. Specific objectives involve encompassing the production of thematic maps to represent the factors contributing to instability (e.g., magmatic intrusions, hydrothermal alteration areas, observed landslides, etc.) and defining and characterizing lithotechnical units based on field observations. In addition, it should determine the mechanical rock properties of natural samples based on laboratory tests that represent different scenarios. Lastly, these results should be incorporated into numerical models to represent unstable areas, failure planes, and conditions for failure.

The brain is an energy intensive organ that requires a robust supply of nutrients and oxygen. The vasculature irrigating the brain is a huge and complex network of blood vessels fulfilling this requirement, while also protecting the neural tissue from blood-borne toxic substances. This regulated nutrient supply is accomplished by the formation of a highly selective molecular barrier, termed the blood-brain barrier (BBB). Dysfunction of the BBB or malformations of the vascular network are associated with pathological conditions that impair brain function, and can lead to death. Thus, appropriate morphogenesis and establishment of the brain vasculature is necessary for a healthy life. The brain vasculature forms during intrauterine development, matching brain growth in this same period. Anatomically, blood vessels grow first surrounding the brain primordium and then penetrate the parenchyma until they vascularize the periventricular zone. The molecular regulation of this patterned growth is not completely understood. Several signaling pathways are known to be involved in brain angiogenesis, including WNT, TGF-β, Hh, and NOTCH, which differentially regulate vascular growth. Recently, cholesterol has been shown to modulate angiogenic growth in other vascular beds by regulating the activity of the NOTCH pathway, suggesting that cholesterol levels could influence developmental angiogenesis in the brain. Interestingly, cholesterol is also required for signal transduction of the Hh pathway. In preliminary in vitro experiments, we have observed that brain endothelial cells activate an angiogenic program after cholesterol depletion. Here, we will extend those studies to in vivo models to determine the role of cholesterol in developmental brain angiogenesis. We propose that an increase in vascular cell cholesterol activates NOTCH and attenuates Hh signaling pathways, restricting sprouting angiogenesis and blood-brain barrier formation in mouse embryo brain vasculature. To test this hypothesis, we will study mouse embryos with altered cholesterol levels by dietary, pharmacological, and genetic manipulations. We expect these manipulations to induce a reduction or an increase in cholesterol levels in the brain vasculature during embryonic development, which we will evaluate by measuring cholesterol content in isolated vascular fragments. In all these models, we will (Specific aim 1) study vascularization in the brain during intrauterine development using immunofluorescence with specific antibodies against endothelium proteins. In addition, we will measure the levels of transcript and proteins of general key regulators of angiogenesis in isolated vascular fragments, using qPCR and Western blot. We will (Specific aim 2) also evaluate the state of the BBB in the brain vasculature of these models at a fetal stage when the barrier is already formed and functional. For this, we will use immunofluorescence to detect the presence of marker proteins of the BBB in vascular fragments, and we will measure their levels by Western blot. Further, we will test the functionality of the barrier by injecting a fluorescent tracer and evaluating its extravasation in the brain. Finally, we will (Specific aim 3) determine the activation of the NOTCH and Hh pathways in the brain vasculature of the models at the stage of maximal angiogenesis. We will use qPCR and Western blot to measure the levels of marker genes and proteins for these two pathways in vascular fragments, and Proximity Ligation In Situ Hybridization in tissue sections to evaluate the transcript levels of those markers in situ. We expect that the different models of dietary, pharmacological, and genetic interventions will increase or reduce cholesterol levels in the brain vasculature. These changes are expected to correlate with opposing effects on angiogenesis in the brain during development (i.e. low cholesterol will increase angiogenesis, while high cholesterol will inhibit it). In the same way, we expect that distinct cholesterol levels will have opposing effects on the integrity of the BBB. These changes in angiogenesis and BBB function are expected to be associated with concomitant disruption of the NOTCH and Hh pathways. In summary, in this proposal we aim to cover a knowledge gap regarding the role of cholesterol in the regulation of developmental angiogenesis in the brain. These experiments may uncover new mechanisms driving vascular growth and barrier establishment in the brain, which could lead to new strategies for the prevention and treatment of pathologies involving the brain vasculature.

The proposal focuses on understanding the neuro-vascular aging mechanisms associated with alterations in fetal growth by intrauterine hypoxia using molecular biology and physiology as an area. The aim of the study is to demonstrate that impaired fetal growth conditions are associated with epigenetic programming of aging-related DNA methylation, chromatin remodeling, and miRNA-omic profile of junctional complex genes in the neuroendothelium, which can alter BBB integrity and permeability, increasing cerebral damage which impacts the juvenile and adulthood neurocognitive function.

Aplicación de técnicas variacionales y de Ecuaciones Diferenciales Parciales en grafos para problemas de agrupación de datos y para segmentación de imágenes

Esta propuesta está dedicada al estudio de problemas locales y no locales, elípticos y parabólicos, en Ecuaciones en Derivadas Parciales (EDP). Se espera obtener resultados de existencia para los problemas planteados, son 3 los problemas que se quieren estudiar: El primer modelo involucra al Laplaciano Fraccionario con singularidades no lineales (Ecuación Fraccionaria de Burger ver (3)). En este problema queremos probar la existencia y la no unicidad de soluciones débiles de (3), teniendo en cuenta que las soluciones de entropía son soluciones débiles, el primer paso será probar existencia de soluciones de entropía, para esto usaremos el método de sub y supersoluciones, donde probaremos los resultados de los principios de Comparación y L1-Contracción. Una vez teniendo la existencia de solución de entropía, pasaremos a construir una solución débil que no sea solución de entropía, donde esta solución débil se obtendrá como límite de soluciones a problemas regularizados estacionarios, en donde usaremos métodos variacionales para resolver el problema regularizado. El segundo problema, es una extensión al caso no local del problema estudiado en [L. Jeanjean and V. Radulescu, Nonhomogeneous quasilinear elliptic problems: linear and sublinear cases, Journal d'Analyse Mathématique (2021)]. Para probar existencia de soluciones aplicaremos estudios de mínimos locales y el teorema del paso de montaña para el funcional de energía asociado. Para finalizar nuestra propuesta, queremos encontrar soluciones periódicas para sistemas de EDP de cuarto orden (tipo Fisher-Kolmogorov generalizado, ver (9). Siguiendo las técnicas en [P. Smyrnelis, Connecting orbits in Hilbert Spaces and application to PDEs, Comm. Pure Appl Anal 19 (5): 2897--2818 (2020)], usaremos métodos variacionales para probar la existencia de órbitas conectadas en espacios de Hilbert. Construiremos órbitas periódicas usando la construcción desarrollada por Alessio, Montecchiari y Zúñiga en [F. Alessio and P. Montecchiari and A. Zuniga, Prescribed energy connecting orbits for gradient systems, Discr. Cont. Dyn. Systems 39 (8): 4895--4928 (2019].