Is the Fluorescence Quantum Yield of Tryptophan Independent of Excitation Wavelength?

Tryptophan is a fluorescent amino acid that is commonly used as a probe in protein structure-dynamics studies. It is also widely used as a convenient standard for measurements of fluorescence quantum yields of organic and bioorganic molecules. Literature values of the fluorescence quantum yield range from 0.13 to 0.15 upon excitation of tryptophan at 270 nm in aqueous solution. Even though the fluorescence quantum yield of tryptophan is known with a high degree of accuracy upon excitation at 270 nm (i.e., ca. ± 0.02), this value is being used indiscriminately in the literature for the determination of the fluorescence quantum yield of molecules at other excitation wavelengths. In those studies, the assumption has been made that the magnitude of the fluorescence quantum yield of tryptophan does not change with excitation wavelength. This assumption is based on the so-called Kasha’s rule, which states that fluorescence emission occurs in appreciable yield only from the lowest excited singlet state of an organic molecule. Consequently, the fluorescence quantum yield is typically independent of the excitation wavelength used. However, many molecules are known to not obey the Kasha’s rule. Therefore, in this study, we examine the hypothesis that the fluorescence quantum yield of tryptophan does not depend on the excitation wavelength used. We also investigate if the fluorescence quantum yield of tryptophan varies when the salt concentration of the phosphate buffer solution at a physiological pH of 7.4 is varied. The results demonstrate that the fluorescence quantum yield of tryptophan depends on excitation wavelength. It is, however, independent of the ionic strength of the buffered solution in a salt concentration range from 5 to 100 millimolar. A photophysical relaxation mechanism that satisfactorily explains the excitation wavelength dependence of the fluorescence quantum yield of tryptophan will be presented.https://commons.case.edu/intersections-fa20/1002/thumbnail.jp

Photochemistry of RNA, RNA Monomers, and Plausible Prebiotic Precursors

Sunlight is the primary source of energy to promote change on Earth. In this context, ultraviolet radiation can be thought as a catalyst of chemical change to refine chemical feedstocks and facilitate their transformations into the building blocks of life. To establish reasonable environmental constraints for the chemical origins of life, it is central to understand how the photochemical reactivity or photochemical resistance of prebiotic molecules might have supported the formation of the RNA monomers on the Earth\u27s surface and particularly in aqueous solution. In this chapter, the photochemistry of the RNA monomers and several conceivably important prebiotic precursors are reviewed. The emphasis is on delineating the primary electronic relaxation or photochemical reaction pathways that may have enabled the accumulation and the selection of the RNA monomers as the building blocks of life during prebiotic times. Finally, the moderately investigated photochemistry of RNA is summarized and contrasted to that of DNA. It is surmised that the enhanced structural rigidity and the increased excitation delocalization length in RNA may have conspired during prebiotic times for RNA oligomers to prosper under the otherwise harsh ultraviolet radiation conditions of early Earth

Towards an automated analysis of video-microscopy images of fungal morphogenesis

7 páginas, 6 figuras.[EN] Fungal morphogenesis is an exciting field of cell biology and several mathematical models have been developed to describe it. These models require experimental evidences to be corroborated and, therefore, there is a continuous search for new microscopy and image analysis techniques. In this work, we have used a Canny-edge-detector based technique to automate the generation of hyphal profiles and calculation of morphogenetic parameters such as diameter, elongation rates and hyphoid fitness. The results show that the data obtained with this technique are similar to published data generated with manualbased tracing techniques and that have been carried out on the same species or genus. Thus, we show that application of edge detector-based technique to hyphal growth represents an efficient and accurate method to study hyphal morphogenesis. This represents the first step towards an automated analysis of videomicroscopy images of fungal morphogenesis.[ES] La morfogénesis de los hongos es un área de estudio de gran relevancia en la biología celular y en la que se han desarrollado varios modelos matemáticos. Los modelos matemáticos de procesos biológicos precisan de pruebas experimentales que apoyen y corroboren las predicciones teóricas y, por este motivo, existe una búsqueda continua de nuevas técnicas de microscopía y análisis de imágenes para su aplicación en el estudio del crecimiento celular. En este trabajo hemos utilizado una técnica basada en un detector de contornos llamado “Canny-edge-detector” con el objetivo de automatizar la generación de perfiles de hifas y el cálculo de parámetros morfogenéticos, tales como: el diámetro, la velocidad de elongación y el ajuste con el perfil hifoide, es decir, el perfil teórico de las hifas de los hongos. Los resultados obtenidos son similares a los datos publicados a partir de técnicas manuales de trazado de contornos, generados en la misma especie y género. De esta manera demostramos que la aplicación de esta técnica para el trazado de perfiles en hifas en crecimiento es un método eficaz y preciso para el estudio de la morfogénesis de hifas. Este trabajo representa el primer paso en la automatización de análisis de imágenes de video-microscopía de morfogénesis de hifas.This work was supported in part by the project Flora Micológica Ibérica V (REN2002-04068-C02-01GLO), Ministerio de Ciencia y Tecnología, Spain. Dr. Diéguez-Uribeondo was supported by a NATO postdoctoral fellowship.Peer reviewe

Description of a new species of Perichaena (Myxomycetes) from arid areas of Argentina

8 pages, 23 figures.[EN] A new species of the myxomycete genus Perichaena is described in this paper. The new species, named Perichaena calongei, was found during intensive studies of arid areas of the Monte desert in Argentina. It has been found directly in the field from the provinces of Catamarca, La Rioja, Salta and San Juan, in the Northwest of Argentina, and isolated from moist chamber cultures of native plant species collected in Catamarca, Jujuy, Salta and San Juan. The characters that make this species unique in the genus are the combination of the morphology of the sporocarps, the structure and dehiscence of the peridium, and the ornamentation of the capillitium. The morphology of the my xo - mycete specimens was examined using light microscopy with Nomarski interference contrast, and scanning electron microscopy. Micrographs of relevant morphological characters are included. A key to facilitate the identification of the stipitate species of Perichaena is also proposed.[ES] Se describe una nueva especie, Perichaena calongei, que fue encontrada en el desierto de Monte, en las zonas áridas del nor - oeste de Argentina. Los cuerpos fructíferos se encontraron fructificados en el campo, también se obtuvieron por cultivo en cámara húmeda de plantas recolectadas en las provincias de Catamarca, Jujuy, La Rioja, Salta y San Juan. La combinación de caracteres de la morfología del esporocarpo, de la estructura y tipo de dehiscencia del peridio, y de la ornamentación del capilicio, distinguen esta especie del resto de las conocidas en el género. La morfología de la especie se analizó con un microscopio óptico dotado de contraste interferencial de Nomarski y con un microscopio electrónico de barrido, se incluyen ilustraciones de las estructuras observadas. Se propone una clave dicotómica para la identificación, a nivel mundial, de las especies estipitadas del género Perichaena.This research has been supported by the Ministry of Science and Innovation of Spain (grant CGL2005-00320/BOS and CGL2008-00720/BOS).Peer reviewe

An Upgraded Dual-Band Digital Predistorter Model for Power Amplifiers Linearization

Digital predistortion (DPD) based on Volterra models is commonly employed to counteract the nonlinear distortion of power amplifiers. However, when concurrent dual-band signals are transmitted, 2-D DPD models are required. In this work, upgrading of a standard dual-band model is proposed and justified using multinomial theorem. The linearization performance of the current proposal has been compared to the unextended model. Fifth generation (5G) New Radio signals have been generated to compose a dual-band signal, which later was employed as input signal at Chalmers University of Technology's RF WebLab. Using coefficient selection techniques, the most relevant regressors are shown, and the importance of the new extension is proven. Linearization results highlight the benefits of this proposal.Comisión Europea, Fondo Europeo de Desarrollo RegionalMinisterio de Economía y Competitividad TEC2017-82807-

Bioremediazioa: poluitzaileak ezabatzeko oinarri ekologikoak

Azken hamarkadetan ekosistema ugaritan poluitzaileak nabarmen ugaritu dira, maila oso kezkagarrietara iritisi arte. Poluitzaileen isurketa murrizteaz gain, ezinbestekoa dugu ikertzea nola azkar daitekeen hainbat substantzien degradazioa. Bioremediazioa ingurunearen poluzioa murrizteko ahalmen itzela erakutsi du, bakterioen populazioek duten ezberditasun genetikoez eta metabolismo-gaitasunez baliatuz eta kutsagarriak beste produktu kaltegabeetan eraldatuz. Gaur egun, bioremediazioa ingurunea kutsatuta duen edozein leku garbitzeko balio duen teknika berritzat hartzen da baina ingurugiroaren baldintzen arabera eta kutsagarrien berezitasunen arabera ekin behar zaio biodegradazioari kasu bakoitzean

Bioremediazioa: poluitzaileak ezabatzeko oinarri ekologikoak

Azken hamarkadetan ekosistema ugaritan poluitzaileak nabarmen ugaritu dira, maila oso kezkagarrietara iritisi arte. Poluitzaileen isurketa murrizteaz gain, ezinbestekoa dugu ikertzea nola azkar daitekeen hainbat substantzien degradazioa. Bioremediazioa ingurunearen poluzioa murrizteko ahalmen itzela erakutsi du, bakterioen populazioek duten ezberditasun genetikoez eta metabolismo-gaitasunez baliatuz eta kutsagarriak beste produktu kaltegabeetan eraldatuz. Gaur egun, bioremediazioa ingurunea kutsatuta duen edozein leku garbitzeko balio duen teknika berritzat hartzen da baina ingurugiroaren baldintzen arabera eta kutsagarrien berezitasunen arabera ekin behar zaio biodegradazioari kasu bakoitzean

Budget impact analysis of Subcutaneous Belimumab in patients with systemic Lupus Erythematosus in Spain

Objective: To evaluate the budget impact and the direct costs of the introduction of subcutaneous belimumab (SC) into the Spanish National Health Service (NHS) for patients with systemic lupus erythematosus (SLE) in Spain. Methods: This study was conducted from the Spanish NHS perspective with a time horizon of 3 years. The budget impact analysis compared the cost difference between two scenarios: current market (standard therapy (ST) and intravenous belimumab (IV)) and other market in which patients switched from belimumab IV to belimumab SC until reaching 17% of the total market share. The eligible population was calculated to receive treatment with belimumab, applying the EPISER (study of the prevalence of rheumatic diseases in adult population in Spain) prevalence (91 per 100,000 inhabitants), Autoimmune Systemic Diseases Study Group (GEAS) incidence (2 per 100,000 inhabitants), and the risk of annual mortality to the Spanish adult population. Patients with severe active lupus nephritis and with severe active CNS lupus were excluded. Patients' characteristics, flare rates and severity, and healthcare resource consumption were evaluated based on data from the literature and interviews with an expert panel. A sensitivity analysis was performed. Results: Currently, there is an estimated 34,697 adult patients with SLE in Spain and 3849 patients who are eligible to be treated with belimumab. The introduction of belimumab SC into the Spanish NHS could generate savings in direct healthcare costs of 6 million euros over the 3 years. Conclusion: The introduction of belimumab SC shows direct savings for the Spanish NHS. These savings could contribute to sustainability and decision-making