Evaluación de la expresión constitutiva del gen SchSDD1-like sobre la densidad estomática y su efecto en la respuesta frente a déficit hídrico en plantas heterólogas

142 p.Los estomas desempeñan un papel fundamental en la regulación del intercambio gaseoso y del control del contenido hídrico de las plantas. Los complejos estomáticos se distribuyen en toda la extensión de la epidermis de los tejidos aéreos, aunque en hojas, el patrón de distribución en muy variable entre las especies, pero altamente regulados por un mecanismo que mantienen una distancia mínima, y necesaria, para su correcto funcionamiento. Estudios realizados en Arabidopsis, han permitido identificar una serie de componentes genéticos implicados en este mecanismo, incluyendo ligandos proteicos y receptores de membrana involucrados en la activación de una cascada de señalización de MAP quinasas que actúan de manera negativa sobre los factores de transcripción maestros que controlan secuencialmente las etapas del desarrollo de estomas: SPCH, MUTE y FAMA. Sin embargo, a la fecha, la ruta de desarrollo estomático observada en Arabidopsis no ha sido estudiada en otra especie de plantas. Inicialmente se pensaba que el número de estomas en la superficie de las hojas dependía exclusivamente de factores genéticos, sin embargo, recientes resultados han mostrado que la abundancia estomática varía en respuesta a señales fisiológicas y también frente a factores ambientales, tales como la baja disponibilidad de agua; por lo que intervenir el desarrollo de estomas con el objetivo de modular la densidad estomática y de esta forma, controlar la tasa de pérdida de agua, podría ser una promisoria herramienta para la generación de plantas con un incremento en la tolerancia frente al estrés por déficit hídrico. Entre los genes descritos involucrados en el desarrollo de los complejos estomáticos, existe evidencia de que el gen SDD1 de Arabidopsis thaliana, el cual codifica para una subtilisina, está involucrado en el control del número de estomas. Sin embargo, escaso es el conocimiento respecto de su expresión bajo condiciones de estrés abiótico y tratamiento con ABA. Por otra parte, se ha descrito que en plantas de tomate silvestre (Solanum chilense) –especie tolerante a la sequía- bajo condiciones de estrés salino, reducen el número de estomas en las hojas, y sobre-expresan un gen que codifica para una subtilisina. Estos resultados abren la posibilidad de que un putativo gen homólogo a AtSDD1 en tomate podría estar involucrado en el control del número de estomas, aumentando su probabilidad de supervivencia.Por lo anterior, en esta tesis se determinó el comportamiento transcripcional de AtSDD1 y de los “genes maestros” implicados en el desarrollo estomático en Arabidopsis bajo condiciones de sequía y tratamiento con ABA. Asimismo, se aisló y caracterizó parcialmente al gen SchSDD1-like, el cual comparte una alta homología con secuencias de otros miembros de la familia de serino-proteasas de la familia de las subtilisinas al igual que AtSDD1. El análisis de expresión de este gen en tomate silvestre, indicó que sus transcritos son mayormente acumulados en hojas en desarrollo, lo que estaría relacionado con su función en la abundancia estomática. Análisis experimentales demostraron que la expresión de SchSDD1-like en hojas de tomate silvestre, es inducida en respuesta a estrés salino, sequía y ABA. Así, este gen es un candidato para controlar la frecuencia estomática frente a condiciones de estrés. Para determinar si SchSDD1-like cumple similares funciones que AtSDD1, SDD1-like de S. chilense fue sobreexpresado en plantas mutantes sdd1-3 de Arabidopsis thaliana. Esta mutante presenta un fenotipo que exhibe gran cantidad de estomas y agrupaciones de ellos en la superficie de sus hojas. Sin embargo, las plantas mutantes que sobreexpresan SchSDD1-like, revierten el fenotipo a la condición silvestre de A. thaliana (Col-0), sin afectar ninguna otra característica fenotípica aparente. Por otra parte, la sobreexpresión de SchSDD1-like en plantas de A. thaliana (col-0) produjo una significativa reducción de la densidad estomática en las hojas en comparación a las plantas silvestres. El análisis de los posibles genes afectados por la actividad de SchSDD1-like, mostró una represión de los factores de transcripción maestros que controlan los pasos secuenciales de desarrollo de estomas en Arabidopsis. Además, estas plantas fueron sometidas a deshidratación y estrés por sequía evidenciando un aumento en la tolerancia al estrés comparado con las plantas control (col-0). Para validar la función de SchSDD1-like en la tolerancia a la pérdida de agua en un cultivo de interés agro-económico, SchSDD1-like fue sobre-expresado en plantas de tomate cultivado (“Moneymaker”), las que exhibieron una reducción en la frecuencia estomática en sus hojas y una menor tasa de deshidratación comparado con la planta control. Estos resultados permiten concluir que SchSDD1-like es el ortólogo a AtSDD1 y sugieren que ambos controlan el número de estomas en las hojas, en respuesta a sequía y ABA en sus respectivas especies; que el modelo descrito para el desarrollo de estomas en Arabidopsis, también es válido para tomate; y que la modulación de la expresión génica de SchSDD1-like sería suficiente para aumentar la tolerancia al déficit hídrico en especies cultivadas de tomate./ABSTRACT: Stomata play a key role in the regulation of gas exchange and control of water content in plants. Stomatal complexes are distributed throughout the extent of the epidermis of the aerial tissues, although in leaves, the distribution pattern varies among species, but highly regulated by a mechanism that maintains a minimum distance, and necessary for appropriate operation. Studies performed in Arabidopsis have identified a set of genetic components involved in this mechanism, including protein ligands and membrane receptors involved in the activation of a signaling cascade of MAP kinases which act negatively on master transcription factors that control sequentially the stages of stomata development: SPCH, MUTE and FAMA. However, the stomatal development pathway observed in Arabidopsis has not been studied in other species of plants to date. Initially it was thought that the number of stomata on the leaf surface depended exclusively on genetic factors, however, recent results have shown that the stomatal abundance changes in response to physiological signals and environmental factors, such as low water availability. In this sense, the tervention of stomatal development in order to modulate their density; and thus control the water loss rate, could be a promising tool to generate plants with increased water deficit stress tolerance. Among the described genes involved in the development of stomatal complex, there is evidence that the SDD1 gene of Arabidopsis thaliana, which encodes a subtilisin, is involved in the control of stomatal number. However, few is the knowledge about its expression under abiotic stress conditions and treatment with ABA. Moreover, it was reported that wild tomato plants (Solanum chilense) – a drought tolerant specie- under salt stress conditions, reduce the stomatal number on the leaves, and overexpress a gene encoding a subtilisin. These results open the possibility that a putative gene homologous to AtSDD1 from tomato may be involved in the control of the stomatal number, increasing its chance of survival. Therefore, in this thesis the transcriptional behavior of AtSDD1 and “master genes” involved in stomatal development in Arabidopsis under drought and ABA treatment conditions was determined. Also, SchSDD1-like gene was isolated and partially characterized, which shares a high sequence homology with other serine proteases members of subtilisin family, similar to AtSDD1. The analysis of expression of this gene in wild tomato, indicated that its transcripts are mostly accumulated in developing leaves, which would be related to its role in stomatal abundance. Experimental analysis showed that SchSDD1-like expression in of wild tomato leaves, is induced in response to salt stress, drought and ABA. Thus, this gene is a candidate to control stomatal frequency to cope with stress conditions. To determine whether SchSDD1-like performs a similar functions that AtSDD1, SDD1-like from S. chilense was overexpressed in sdd1-3 mutant plants of Arabidopsis thaliana. This mutant has a phenotype with lots of stomata and clusters of them on the surface of leaves. However, SchSDD1-likeoverexpressing mutant plants, reversed the phenotype to wild-type condition of A. thaliana (Col-0) without affecting any other apparent phenotypic trait. Moreover, overexpression of SchSDD1-like in A. thaliana plants (col-0), produced a significant reduction in stomatal density in leaves compared to wildtype lants. The analysis of possible genes affected by SchSDD1-like activity showed a down-regulation of master switch transcription factors that control the sequential steps of stomatal development in Arabidopsis. Moreover, these plants were subjected to drought and dehydration stress showing increased stress tolerance compared to control plants (Col-0). To validate the SchSDD1-like function in tolerance to water loss in crops of agro-economic interest, SchSDD1-like was overexpressed in cultivated tomato plants ('Moneymaker'), which showed a reduction in stomatal frequency in its leaves and a lower rate of dehydration compared to control plant. These results allow to conclude that: SchSDD1-like is the orthologue gene to AtSDD1 and suggest that both genes control the stomatal number in leaves in response to drought and ABA in their species. The model described of stomatal development in Arabidopsis is also valid in tomato; and that modulation of gene expression of SchSDD1-like would be sufficient to increase tolerance to water deficit in cultivated species of tomato

Mobile and wearable computing in patagonian wilderness

Recent advances in mobile and wearable technology in the last few years have made the optimization of data collection processes possible in diverse fields. Users currently have access to small portable devices that are not only sensitive to their activity, but also to their interaction with their environment. These growing technological advances are in constant development , and have given way to the study and redesign of processes that can be tailored to fit any particular needs. Even users that are far from urbanization, without access to electricity can make use of these possibilities. These technologies can substantially improve their productivity, by allowing them to concentrate solely on their own tasks instead of on the interactions with the computational method used to support their activities. This study presents results and indicators relating to the application these tools within the field of Flora information retrieval, in areas far from urban centers.Instituto de Investigación en Informátic

Mobile and wearable computing in patagonian wilderness

Recent advances in mobile and wearable technology in the last few years have made the optimization of data collection processes possible in diverse fields. Users currently have access to small portable devices that are not only sensitive to their activity, but also to their interaction with their environment. These growing technological advances are in constant development , and have given way to the study and redesign of processes that can be tailored to fit any particular needs. Even users that are far from urbanization, without access to electricity can make use of these possibilities. These technologies can substantially improve their productivity, by allowing them to concentrate solely on their own tasks instead of on the interactions with the computational method used to support their activities. This study presents results and indicators relating to the application these tools within the field of Flora information retrieval, in areas far from urban centers.Instituto de Investigación en Informátic

Fungal Endophytes Exert Positive Effects on Colobanthus quitensis Under Water Stress but Neutral Under a Projected Climate Change Scenario in Antarctica

Functional symbiosis is considered one of the successful mechanisms by which plants that inhabit extreme environment improve their ability to tolerate different types of stress. One of the most conspicuous type of symbiosis is the endophyticism. This interaction has been noted to play a role in the adaptation of the native vascular plant Colobanthus quitensis to the stressful environments of Antarctica, characterized by low temperatures and extreme aridity. Projections of climate change for this ecosystem indicate that abiotic conditions will be less limiting due to an increase in temperature and water availability in the soil. Due to this decrease in stress induced by the climate change, it has been suggested that the positive role of fungal endophytes on performance of C. quitensis plants would decrease. In this study, we evaluated the role of endophytic fungi on osmoprotective molecules (sugar production, proline, oxidative stress) and gene expression (CqNCED1, CqABCG25, and CqRD22) as well as physiological traits (stomatal opening, net photosynthesis, and stomatal conductance) in individuals of C. quitensis. Individual plants of C. quitensis with (E+) and without (E−) endophytic fungi were exposed to simulated conditions of increased water availability (W+), having the current limiting water condition (W−) in Antarctica as control. The results reveal an endophyte-mediated lower oxidative stress, higher production of sugars and proline in plants. In addition, E+ plants showed differential expressions in genes related with drought stress response, which was more evident in W− than in W+. These parameters corresponded with increased physiological mechanisms such as higher net photosynthesis, stomatal opening and conductance under presence of endophytes (E+) as well as the projected water condition (W+) for Antarctica. These results suggest that the presence of fungal endophytes plays a positive role in favoring tolerance to drought in C. quitensis. However, this positive role would be diminished if the stress factor is relaxed, suggesting that the role of endophytes could be less important under a future scenario of climate change in Antarctica with higher soil water availability.Fil: Hereme, Rasme. Universidad de Talca; ChileFil: Morales Navarro, Samuel. Universidad de Talca; ChileFil: Ballesteros, Gabriel. Universidad de Talca; ChileFil: Barrera, Andrea. Universidad de Talca; ChileFil: Ramos, Patricio. Universidad de Talca; ChileFil: Gundel, Pedro Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Molina Montenegro, Marco A.. Universidad de Talca; Chil

Use a solvent like an alternative to improve the cyclic steam stimulation in a heavy oil reservoir

This research proposes the implementation of a cyclic steam injection improved solvent technique in a colombian heavy oil reservoir and its technical evaluation using the recovery factor as main criteria. Numerical reservoir simulation was used to observe the behavior of cold production in a well, which was subsequently subjected to ten cycles of steam injection and steam-solvent injection. In this procedure, optimizations of operational parameters as the injection times, soaking and production, the concentration of solvent used, the operating pressure and rates of steam and solvent were performed. Analysis results of the application of improved solvent cycles is included at the end, from a technical and financial standpoint.Esta investigación plantea la implementación de una técnica de inyección cíclica de vapor mejorado con solventes en un yacimiento de crudo pesado colombiano y su evaluación técnica usando como criterio el factor de recobro.Para observar el comportamiento de la producción en frío en un pozo, que posteriormente fue sometido diez ciclos de inyección de vapor y solvente, se utilizó simulación numérica de yacimientos. En este procedimiento se realizaron optimizaciones de parámetros operacionales como los tiempos de inyección, remojo y producción, la concentración de solvente a utilizar, la presión de operación y las tasas de vapor y de solvente. Al finalizar, se incluye un análisis de resultados de la aplicación de los ciclos mejorados con solvente, desde un punto de vista técnico y financiero

High-yield halide-assisted synthesis of metal–organic framework UiO-based nanocarriers

The synthesis of nanosized metal–organic frameworks (NMOFs) is requisite for their application as injectable drug delivery systems (DDSs) and other biorelevant purposes. Herein, we have critically examined the role of different synthetic parameters leading to the production of UiO-66 crystals smaller than 100 nm. Of note, we demonstrate the co-modulator role conferred by halide ions, not only to produce NMOFs with precise morphology and size, but also to significantly improve the reaction yield. The resulting NMOFs are highly crystalline and exhibit sustained colloidal stability in different biologically relevant media. As a proof of concept, these NMOFs were loaded with Rhodamine 6G (R6G), which remained trapped in most common biologically relevant media. When incubated with living mammalian cells, the R6G-loaded NMOFs were efficiently internalized and did not impair cell viability even at relatively high doses.The authors acknowledge the financial support of the MCIN/AEI (PID2019-108624RB-I00, RYC-2017-23457, RYC-2019-028238-I), the Xunta de Galicia (ED431F 2017/02, ED431F 2020/11, 2021-CP090, Centro Singular de Investigación de Galicia Accreditation 2019–2022, ED431G 2019/03), the European Union (European RegionalDevelopment Fund – ERDF; H2020-MSCA-ITN grant agreement no. 860942; H2020-FET-Open grant agreement no. 899612; H2020-ICT grant agreement no. 10101694 and INTERREG V-A Spain–Portugal, project 0624_2IQBIONEURO_6_E), and the European Research Council (starting grant no. 950421). M.C.-M. thanks the AEI (FPU19/03155). The authors are grateful for the use of RIAIDT-USC analytical facilities.S

Overexpression of a SDD1-Like Gene From Wild Tomato Decreases Stomatal Density and Enhances Dehydration Avoidance in Arabidopsis and Cultivated Tomato

Stomata are microscopic valves formed by two guard cells flanking a pore, which are located on the epidermis of most aerial plant organs and are used for water and gas exchange between the plant and the atmosphere. The number, size and distribution of stomata are set during development in response to changing environmental conditions, allowing plants to minimize the impact of a stressful environment. In Arabidopsis, STOMATAL DENSITY AND DISTRIBUTION 1 (AtSDD1) negatively regulates stomatal density and optimizes transpiration and water use efficiency (WUE). Despite this, little is known about the function of AtSDD1 orthologs in crop species and their wild stress-tolerant relatives. In this study, SDD1-like from the stress-tolerant wild tomato Solanum chilense (SchSDD1-like) was identified through its close sequence relationship with SDD1-like from Solanum lycopersicum and AtSDD1. Both Solanum SDD1-like transcripts accumulated in high levels in young leaves, suggesting that they play a role in early leaf development. Arabidopsis sdd1-3 plants transformed with SchSDD1-like under a constitutive promoter showed a significant reduction in stomatal leaf density compared with untransformed sdd1-3 plants. Additionally, a leaf dehydration shock test demonstrated that the reduction in stomatal abundance of transgenic plants was sufficient to slow down dehydration. Overexpression of SchSDD1-like in cultivated tomato plants decreased the stomatal index and density of the cotyledons and leaves, and resulted in higher dehydration avoidance. Taken together, these results indicate that SchSDD1-like functions in a similar manner to AtSDD1 and suggest that Arabidopsis and tomatoes share this component of the stomatal development pathway that impinges on water status

Primer implante coclear exitoso en América Latina después de ototoxicidad severa inducida por aminoglucósidos en un paciente peruano curado de una tuberculosis extremadamente resistente.

Introduction: Multidrug-resistant tuberculosis is a significant public health problem for which drugs are used with many adverse effects. Among the devastating consequences of these diseases, there is a wide variation in the incidence of ototoxicity and hearing loss in patients with multidrug-resistant and extremely resistant tuberculosis. Cochlear implants may be indicated in patients with unilateral/severe bilateral hearing loss with no benefit from conventional hearing aids, but their use in patients with tuberculosis is rare. Case report: We present the first case of a right unilateral cochlear implant performed on a 34-year-old Peruvian patient who presented profound sensorineural hearing loss of cochlear origin. Conclusion: Cochlear implant surgery is an essential milestone in the treatment of patients with auditory sequelae of tuberculosis treatment. Close monitoring of possible complications of tuberculosis treatment should be strengthened in countries with a high incidence of multidrug-resistant and extremely resistant tuberculosis.Introducción: La tuberculosis multidrogorresistente es un importante problema de salud pública para el que se utilizan fármacos con múltiples efectos adversos. Entre las devastadoras consecuencias de estas enfermedades, existe una amplia variación en la incidencia de ototoxicidad y pérdida auditiva en pacientes con tuberculosis multirresistente y extremadamente resistente. Los implantes cocleares pueden estar indicados en pacientes con pérdida auditiva unilateral/bilateral severa sin beneficio de los audífonos convencionales, pero su uso en pacientes con tuberculosis es raro. Reporte de un caso: Presentamos el primer caso de implante coclear unilateral derecho realizado a un paciente peruano de 34 años que presentaba hipoacusia neurosensorial profunda de origen coclear. Conclusión: La cirugía de implante coclear es un hito fundamental en el tratamiento de los pacientes con secuelas auditivas del tratamiento de la tuberculosis. Se debe fortalecer la vigilancia estrecha de las posibles complicaciones del tratamiento de la tuberculosis en los países con una alta incidencia de tuberculosis multirresistente y extremadamente resistente