Effects of climate change on soil phosphorus pools in drylands. A multiscalar perspective

Programa de Doctorado en Medio Ambiente y SociedadLínea de Investigación: Biodiversidad y Biología de la ConservaciónClave Programa: DAMCódigo Línea: 125Climate change is having significant impacts on biogeochemical cycles, particularly in drylands. Besides that, the global increase in atmospheric nitrogen (N) deposition may destabilize vegetation primary production in terrestrial ecosystems, and phosphorous (P) may become the most limiting nutrient in many of these ecosystems. Hence, clarifying the effects of climate change on the dynamics and availability of P in the soil is essential to forecast its impacts on ecosystem functioning, especially in drylands. However, the effects of climate change and biocrusts on soil P pools in arid and semi-arid ecosystems remain poorly understood. In addition, we do not have sufficient knowledge of the main factors that control soil P pools in coastal dunes ecosystems, which are among the most valued priority conservation areas worldwide and will probably suffer extreme events caused by climate change. Likewise, there are knowledge gaps regarding the interactions between increases in aridity, land-use intensification, and soil P dynamics in drylands. Finally, in the context of increases in aridity driven by climate change, it is essential to have a deeper understanding of how climate and other environmental factors drive P dynamics across terrestrial biomes at a global scale. The main objective of this thesis is to evaluate how major global change drivers (climate change and land-use intensification) will affect the dynamics of the P cycle across terrestrial biomes, with a particular focus on dryland ecosystems. Specifically, we evaluated the role of biological soil crusts, aridity, and livestock grazing on P pools in drylands at different spatial scales: local, regional, and global. Also, I determined the main environmental drivers controlling pools of soil P availability in terrestrial biomes globally. Chapter 1 evaluates how simulated climate change and biocrusts affect P pools in the soil top layer. For this, we used two long-term experiments located in Central (Aranjuez) and Southeast (Sorbas) Spain. Our results highlight the important role of biocrusts in regulating major P pools in dryland soils, and in increasing the resistance of the P cycle to the impacts of simulated climate change. They also show the large impacts of warming on the P pools, with significant increases in major pools, which may be related to both the decomposition of biocrusts tissues and the decrease in the activity of P solubilizing bacteria and fungi responsible for the transfer of mineral to organic P pools. Chapter 2 investigates the combined effects of biological and geochemical drivers on the labile, medium-labile, and recalcitrant P pools along dune ecosystems of the Atlantic coast of the Iberian Peninsula, encompassing a wide aridity gradient. Our results suggest a novel transfer mechanism mediated by microorganisms that transfer medium-lability P forms to the more labile P pool. At the same time, increases in bacterial richness associated with biofilms might be involved in the thickening of the medium-lability P pool in our climosequence. These bacterial-mediated transfers would confer resistance to labile P under a climate change scenario, and reveal the critical role of soil microorganisms as modulators of the P geochemical cycle. Chapter 3 evaluates the joined effects of aridity and livestock grazing pressure on soil P pools along global grazing pressure and climatic gradients using 98 rangelands from all continents except Antarctica. Our findings reveal that both climate change (i.e., increasing aridity) and land-use intensification (i.e., increases in livestock grazing pressure) have a synergistic effect on P availability, increasing concentrations of non-occluded P, which promotes the decoupling of N:P cycles across global drylands. Chapter 4 provides a novel clustering approach to soil P availability across biomes worldwide. Also, the study evaluates the main environmental drivers that determine the spatial distribution and vulnerability to climate change of the soil P pools in terrestrial biomes globally. This study highlights that soil P pools will depend on the biotic factors, ultimately affected by the climate and the amount of soil organic matter, and on geochemical processes influenced by topographic relief. These results also suggest that the predicted increase in temperature caused by ongoing climate change will have a direct negative impact on the reserves of bioavailable P in the short term, limiting primary production in terrestrial ecosystems worldwide. Overall, the findings obtained in this doctoral thesis provide outstanding information about microscale and macroscale mechanisms that control soil P dynamics in terrestrial ecosystems, especially in drylands. Specifically, our results provide novel insights about the increase of soil P availability caused by climate change and land-use intensification, promoting the imbalance between N and P on soils, which will negatively affect dryland ecosystem production. Likewise, they highlight the key role of biocrust and microbial communities control soil P pools in drylands. The information provided at a local and regional scale will be a precious source for the management and conservation strategies of drylands and mitigating the consequences of global change in ecosystem functions. Likewise, this deeper global-scale knowledge about the dynamics of the soil P cycle could be incorporated into Earth system models to understand better the effect of global change on the multifunctionality of ecosystems in the Anthropocene.Universidad Pablo de Olavide de Sevilla. Departamento de Sistemas Físicos, Químicos y Naturale

Padrões de aprendizagem no contexto universitário mexicano: revisão sistemática do modelo e suas publicações:

The aim of this review study is to look into the quality and quantity of research on Vermunt’s theoretical and instrumental learning patterns model—with an impact from the perspective of scientific dissemination—and/or those dealing with one or more of its components (learning conceptions, motivational orientations, processing and regulation strategies) in the Mexican context. For this purpose, the researchers carried out a systematic search of publications in indexed journals according to their impact, keywords, a time parameter and their association according to the databases, the authors and their corresponding indexation. The results showed a small amount of research applying the learning patterns model, as well as a limited number of indexed publications in the Social Science Citation Index and Scopus. Finally, the authors concluded that it is necessary to improve the quality and quantity of research carried out in the Mexican territory, in particular, and Latin American in general. Besides, they asked for enhancing the dissemination of results in English.El objetivo del presente estudio de revisión es indagar la calidad y cantidad de investigaciones, con divulgación científica de impacto, sobre el modelo teórico-instrumental de patrones de aprendizaje propuesto por Vermunt y/o de aquellas que abordan uno o varios componentes que definen dicho modelo (concepciones de aprendizaje, orientaciones motivacionales, estrategias de procesamiento y de regulación) en el contexto universitario mexicano. Para ello, se realizó una búsqueda sistemática de publicaciones en revistas científicas indexadas según su impacto, mediante la selección de palabras clave, parámetro temporal y agrupación de acuerdo con las bases de datos, los autores y la indexación correspondiente. De acuerdo con los resultados, los investigadores reportaron una escasa cantidad de investigaciones que aplican el modelo de patrones de aprendizaje, así como un limitado número de publicaciones indexadas en Social Science Citation Index y Scopus. Finalmente, se concluye la necesidad de mejorar la calidad y cantidad de investigaciones que se llevan a cabo en el territorio mexicano en particular, y latinoamericano en general. Asimismo, se pide incrementar la divulgación de los resultados en inglés.O objetivo deste estudo de revisão é investigar a qualidade e quantidade de pesquisas, com divulgação científica do impacto, sobre o modelo teórico-instrumental de padrões de aprendizagem proposto por Vermunt e / ou aqueles que abordam um ou vários componentes que definem o referido modelo (concepções de aprendizagem, orientações motivacionais, estratégias de processamento e regulação) no contexto universitário mexicano. Para isso, foi realizada uma busca sistemática de publicações em periódicos científicos indexados de acordo com o seu impacto, selecionando palavras-chave, parâmetros temporais e agrupamentos de acordo com as bases de dados, autores e a indexação correspondente. De acordo com os resultados, os pesquisadores relataram uma pequena quantidade de pesquisa que aplica o modelo de padrão de aprendizagem, bem como um número limitado de publicações indexadas no Social Science Citation Index e no Scopus. Finalmente, conclui-se a necessidade de melhorar a qualidade e a quantidade de pesquisas realizadas no território mexicano em particular, e na América Latina em geral. Da mesma forma, solicita-se aumentar a divulgação dos resultados em inglês

Climatic vulnerabilities and ecological preferences of soil invertebrates across biomes.

Unlike plants and vertebrates, the ecological preferences, and potential vulnerabilities of soil invertebrates to environmental change, remain poorly understood in terrestrial ecosystems globally. We conducted a cross-biome survey including 83 locations across six continents to advance our understanding of the ecological preferences and vulnerabilities of the diversity of dominant and functionally important soil invertebrate taxa, including nematodes, arachnids and rotifers. The diversity of invertebrates was analyzed through amplicon sequencing. Vegetation and climate drove the diversity and dominant taxa of soil invertebrates. Our results suggest that declines in forest cover and plant diversity, and reductions in plant production associated with increases in aridity, can result in reductions of the diversity of soil invertebrates in a drier and more managed world. We further developed global atlases of the diversity of these important soil invertebrates, which were cross-validated using an independent database. Our study advances the current knowledge of the ecological preferences and vulnerabilities of the diversity and presence of functionally important soil invertebrates in soils from across the globe. This information is fundamental for improving and prioritizing conservation efforts of soil genetic resources and management policies

Statistical models to study subtoxic concentrations for some standard mutagens in three colon cancer cell lines

The aim of this work is to propose models to study the toxic effect of different concentrations of some standard mutagens in different colon cancer cell lines. We find estimates and, by means of an inverse regression problem, confidence intervals for the subtoxic concentration, that is the concentration that reduces by thirty percent the number of colonies obtained in the absence of mutagen

La agricultura periurbana multifuncional y sus aportaciones hacia la sustentabilidad regional en la Zona Metropolitana de Guadalajara, Jalisco, México

Un modelo de desarrollo basado en relaciones asimétricas y desequilibradas entre la ciudad y el campo, y entre la sociedad y sus ecosistemas, ha dado como resultado que en la Zona Metropolitana de Guadalajara (ZMG), en Jalisco, México, se generen conflictos ambientales en un entorno de creciente insustentabilidad regional. Algunas expresiones de esta situación se manifiestan en las áreas periurbanas y rurales con el avance descontrolado de la urbanización, la disminución de la superficie agropecuaria, la pérdida de vegetación y agrodiversidad, la deforestación, el agotamiento de los suelos, la disminución y contaminación del agua, la sanidad de los alimentos, las afectaciones a la salud pública y el deterioro del nivel de vida de sus habitantes. La importancia poblacional, económica y política de esta región y el aumento de los conflictos ambientales, demandan a los actores sociales e institucionales, la construcción de alternativas hacia la sustentabilidad regional, y en ellas juegan un papel fundamental la múltiples funciones que desempeña la agricultura periurbana o agricultura de proximidad. En este capítulo se presentan reflexiones y avances del proyecto de investigación e intervención “Agua, agrodiversidad y medio ambiente en la región Guadalajara-Chapala-Santiago” que a partir de una perspectiva de complejidad, ubicada en las ciencias de la sustentabilidad, ha realizado investigación interdisciplinaria en torno a tres procesos relevantes que generan conflictos ambientales en la región: a) uso y manejo del agua, b) relaciones ciudad campo, y c) gestión pública y social. El trabajo de intervención se ha orientado a la vinculación entre grupos y redes, a la formación campesino a campesino, al dialogo de saberes y al impulso de procesos sociales y organizativos, como parte del acompañamiento universitario a los actores locales en la construcción y fortalecimiento de sus alternativas hacia la sustentabilidad regional.ITESO, A.C

Nonsurgical Procedures for Keratoconus Management

Objectives. To describe the past 20 years’ correction modalities for keratoconus and their visual outcomes and possible complications. Methods. A review of the published literature related to the visual outcomes and possible complications in the context of keratoconus management using nonsurgical procedures for the last 20 years (glasses and contact lenses) was performed. Original articles that reported the outcome of any correction modalities of keratoconus management were reviewed. Results. The most nonsurgical procedure used on keratoconus management is the contact lens fitting. Soft contact lenses and soft toric contact lenses, rigid gas-permeable contact lenses, piggyback contact lens system, hybrid contact lenses, and scleral and corneoscleral contact lenses form the contemporary range of available lens types for keratoconus management with contact lenses. All of them try to restore the vision, improve the quality of life, and delay surgical procedures in patients with this disease. Complications are derived from the intolerance of using contact lens, and the use of each depends on keratoconus severity. Conclusions. In the context of nonsurgical procedures, the use of contact lenses for the management of keratoconic patients represents a good alternative to restore vision and improve the quality of live in this population

Micronuclei detection by flow cytometry as a high-throughput approach for the genotoxicity testing of nanomaterials

Thousands of nanomaterials (NMs)-containing products are currently under development or incorporated in the consumer market, despite our very limited understanding of their genotoxic potential. Taking into account that the toxicity and genotoxicity of NMs strongly depend on their physicochemical characteristics, many variables must be considered in the safety evaluation of each given NM. In this scenario, the challenge is to establish high-throughput methodologies able to generate rapid and robust genotoxicity data that can be used to critically assess and/or predict the biological effects associated with those NMs being under development or already present in the market. In this study, we have evaluated the advantages of using a flow cytometry-based approach testing micronucleus (MNs) induction (FCMN assay). In the frame of the EU NANoREG project, we have tested six different NMs-namely NM100 and NM101 (TiO2NPs), NM110 (ZnONPs), NM212 (CeO2NPs), NM300K (AgNPs) and NM401 (multi-walled carbon nanotubes (MWCNTs)). The obtained results confirm the ability of AgNPs and MWCNTs to induce MN in the human bronchial epithelial BEAS-2B cell line, whereas the other tested NMs retrieved non-significant increases in the MN frequency. Based on the alignment of the results with the data reported in the literature and the performance of the FCMN assay, we strongly recommend this assay as a reference method to systematically evaluate the potential genotoxicity of NMs

Frailty in community-dwelling older adults : association with adverse outcomes

The study of frailty is important to identify the additional needs of medical long-term care and prevent adverse outcomes in community dwelling older adults. This study aimed to determine the prevalence of frailty and its association with adverse outcomes in community dwelling older adults. A cross-sectional study was carried out from April to September 2014. The population sample was 1,252 older adults (≥60 years) who were beneficiaries of the Mexican Institute of Social Security (IMSS) in Mexico City. Data were derived from the database of the "Cohort of Obesity, Sarcopenia and Frailty of Older Mexican Adults" (COSFOMA). Operationalization of the phenotype of frailty was performed using the criteria of Fried et al (weight loss, self-report of exhaustion, low physical activity, slow gait, and weakness). Adverse outcomes studied were limitation in basic activities of daily living (ADLs), falls and admission to emergency services in the previous year, and low quality of life (WHOQOL-OLD). Frailty was identified in 20.6% (n=258), pre-frailty in 57.6% (n=721), and not frail in 21.8% (n=273). The association between frailty and limitations in ADL was odds ratio (OR) =2.3 (95% confidence interval [CI] 1.7-3.2) and adjusted OR =1.7 (95% CI 1.2-2.4); falls OR =1.6 (95% CI 1.2-2.1) and adjusted OR =1.4 (95% CI 1.0-1.9); admission to emergency services OR =1.9 (95% CI 1.1-3.1) and adjusted OR =1.9 (95% CI 1.1-3.4); low quality of life OR =3.4 (95% CI 2.6-4.6) and adjusted OR =2.1 (95% CI 1.5-2.9). Approximately 2 out of 10 older adults demonstrate frailty. This is associated with limitations in ADL, falls, and admission to emergency rooms during the previous year as well as low quality of life

Effect of temperature on RNA silencing of a negative-stranded RNA plant virus: Citrus psorosis virus

Citrus psorosis virus (CPsV), genus Ophiovirus, causes a bark scaling disease of citrus. CPsV virions are kinked filaments with three negative-stranded RNA molecules (vRNA) and a 48 kDa coat protein. The effect of temperature on symptom expression, virus accumulation and RNA silencing was examined in sweet orange seedlings (Citrus sinensis) graft-inoculated with three different CPsV isolates and grown in a glasshouse at 26/18°C or 32/26°C (day/night). Most plants kept in the cooler glasshouse showed a shock reaction in the first flush with shoot necrosis, and then moderate to intense chlorotic flecking and spotting in young leaves, whereas plants incubated at 32/26°C did not exhibit shoot necrosis, and young leaf symptoms were milder. Virus titre estimated by ELISA and by northern and dot blot hybridization paralleled symptom intensity, with significantly higher virus accumulation in plants incubated at 26/18°C. The amount of CPsV-derived small RNAs (CPsV-sRNAs) slightly increased at 32/26°C, with the ratio of CPsV-sRNA/vRNA being higher at 32/26°C than at 26/18°C. These results suggest that (i) CPsV infection induces RNA silencing in citrus plants, (ii) symptom intensity is associated with virus accumulation, and (iii) temperature increase enhances the RNA silencing response of citrus plants and decreases virus accumulation.Facultad de Ciencias Exacta