Caracterización molecular de un nuevo tipo de Peroxidasa lignolítica

Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias Biológicas, leída el 01-03-1999Fac. de Ciencias BiológicasTRUEpu

Tutorial para el reconocimiento de objetos basado en características empleando herramientas Phyton

El reconocimiento de objetos es algo innato en el ser humano. Cuando las personas miramos una fotografía, somos capaces de detectar sin esfuerzo elementos como animales, señales, objetos de interés, etc. En el campo de la visión por computador este proceso se lleva a cabo mediante herramientas de Inteligencia Artificial, con el fin de obtener información sobre el contenido de una imagen. Esta tarea, aunque ampliamente investigada, a un sigue siendo un campo de estudio activo debido a los grandes retos que conlleva: la detección de objetos en distintas condiciones luminosas, con posibles oclusiones, distintos tamaños y perspectivas, etc. Este artículo describe las tareas a completar en el desarrollo de un sistema de reconocimiento de objetos exitoso, y proporciona al lector una serie de directrices prácticas sobre como realizarlas. El trabajo viene acompañado de una serie de scripts Python para experimentar con las diferentes técnicas descritas, pretendiendo servir de apoyo en tareas docentes o de iniciación a cualquier entusiasta en la materia.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Este trabajo se ha desarrollado en el marco del proyecto WISER (DPI2017-84827-R), financiado por el Ministerio de Ciencia e Innovación contando con fondos del Fondo Europeo de Desarrollo Regional (FEDER)

Magnetic influence on water evaporation rate: an empirical triadic model

Over the past decades researchers have described what happens to the water when a polarizing external field is applied to it and changes the bonding forces existing in it. Water evaporation, an essential process in nature, has been targeted in a great number of studies. In this paper, static magnetic fields ranging from 30-to-200 mT were applied to circulating purified water to study their effect on how the evaporation rate changed under different ambient conditions. A statistical approach was employed to verify the significance of the magnetically induced effect. Our results showed that by applying a static magnetic field to the water, the evaporation rate increased at lower temperatures, yielding an evaporation increase for magnetized water of up to at 6 °C. We found too that the circulation of the water did not contribute significantly to the evaporation rate. We used an empirical triadic model to correlate the applied magnetic field with the ambient parameters of temperature and humidity.This work was supported in part by the Ministerio de Ciencia, Innovación y Universidades (ID: PGC2018-096994-B-C22), the Ministerio de Economía y Competitividad -Infraestructura FEDER- (ID: EQC2018-004395-P), and by Funding for open access charge: Universidad de Huelva/ CBUA

Improvement of healthy lifestyles and quality of life in a learning community through community health education programmes

En Andalucía se han venido desarrollando durante los últimos años experiencias participativas llevadas a cabo por centros configurados como Comunidades de Aprendizaje que van consiguiendo, paulatinamente, transformar la realidad socioeducativa de la escuela y su entorno, movilizando la aportación cultural y educativa de muchas personas implicadas en la mejora de la educación. En este artículo se mostrará si a través de dichas aportaciones, y llevando a cabo programas de educación comunitaria sobre salud, mejora la calidad de vida de un centro transformado en comunidad de aprendizaje, donde el 84% del alumnado es de etnia gitana, durante el curso 2018/19. La metodología de investigación utilizada responde al enfoque comunicativo crítico, buscando la descripción y/o interpretación de la realidad, y además pretende ayudar a transformar esa realidad. Dicha metodología está basada en el diálogo igualitario entre la comunidad científica y las personas cuya realidad sea objeto de investigación. A través de las entrevistas en profundidad de orientación comunicativa y los grupos de discusión comunicativos se vislumbrará que el alumnado ha mejorado sus hábitos de vida saludables, manifestándose también que lo aprendido en la escuela se encuentra, a menudo, en conflicto con lo que adquieren en su entorno familiar

Role of surface tryptophan for peroxidase oxidation of nonphenolic lignin

Background: Despite claims as key enzymes in enzymatic delignification, very scarce information on the reaction rates between the ligninolytic versatile peroxidase (VP) and lignin peroxidase (LiP) and the lignin polymer is available, due to methodological difficulties related to lignin heterogeneity and low solubility.Results: Two water-soluble sulfonated lignins (from Picea abies and Eucalyptus grandis) were chemically characterized and used to estimate single electron-transfer rates to the H2O2-activated Pleurotus eryngii VP (native enzyme and mutated variant) transient states (compounds I and II bearing two- and one-electron deficiencies, respectively). When the rate-limiting reduction of compound II was quantified by stopped-flow rapid spectrophotometry, from fourfold (softwood lignin) to over 100-fold (hardwood lignin) lower electron-transfer efficiencies (k 3app values) were observed for the W164S variant at surface Trp164, compared with the native VP. These lignosulfonates have ~20–30 % phenolic units, which could be responsible for the observed residual activity. Therefore, methylated (and acetylated) samples were used in new stopped-flow experiments, where negligible electron transfer to the W164S compound II was found. This revealed that the residual reduction of W164S compound II by native lignin was due to its phenolic moiety. Since both native lignins have a relatively similar phenolic moiety, the higher W164S activity on the softwood lignin could be due to easier access of its mono-methoxylated units for direct oxidation at the heme channel in the absence of the catalytic tryptophan. Moreover, the lower electron transfer rates from the derivatized lignosulfonates to native VP suggest that peroxidase attack starts at the phenolic lignin moiety. In agreement with the transient-state kinetic data, very low structural modification of lignin, as revealed by size-exclusion chromatography and two-dimensional nuclear magnetic resonance, was obtained during steady-state treatment (up to 24 h) of native lignosulfonates with the W164S variant compared with native VP and, more importantly, this activity disappeared when nonphenolic lignosulfonates were used.Conclusions: We demonstrate for the first time that the surface tryptophan conserved in most LiPs and VPs (Trp164 of P. eryngii VPL) is strictly required for oxidation of the nonphenolic moiety, which represents the major and more recalcitrant part of the lignin polymer

Radionuclides in arctic marine macroalgae from Kongsfjorden (Svalbard)

Seaweeds are known to be useful environmental bioindicators since they bioaccumulate radioisotopes at very low environmental concentrations. Levels of natural radionuclides in six ecologically relevant brown and red seaweed species from Arctic coasts (Kongsfjorden, Spitsbergen, Svalbard Islands) were analysed in the present study, in order to characterise the levels of natural radioactivity in this ecosystem and to compare this with previously published data in coastal areas from other latitudes. Thalli were collected by SCUBA divers at different depths in Hansneset in September 2014 and transported immediately to the laboratory. Young thalli, free from macroscopic epibiota, were dried, powdered and confined in a standard geometry before gamma spectrometry measurements. Then, the radioactivity of 7Be, 40K, 208Tl, 210Pb, 212Pb, 226Ra and 228Ra was measured by high-resolution gamma spectrometry using high-purity germanium detectors for 172800 s. Detectors were calibrated using a traceable multi gamma standard source and results are on a dry weight and fresh weight basis and are decay corrected to the date of sampling. Our results revealed the influence of cosmogenic radionuclides in the intertidal zone, as shown by the unique presence of 7Be in the brown macroalga Fucus distichus, the only analysed species inhabiting the intertidal. High concentrations of 40K were observed in all species, as this is one of the essential elements in biota. Remarkably is the high content of 210Pb in the red seaweeds Phycodrys rubens and Ptilota gunneri, suggesting that these species might possess a higher capacity for heavy metals bioaccumulation than the analysed brown seaweeds

Improving the Oxidative Stability of a High Redox Potential Fungal Peroxidase by Rational Design

Ligninolytic peroxidases are enzymes of biotechnological interest due to their ability to oxidize high redox potential aromatic compounds, including the recalcitrant lignin polymer. However, different obstacles prevent their use in industrial and environmental applications, including low stability towards their natural oxidizing-substrate H2O2. In this work, versatile peroxidase was taken as a model ligninolytic peroxidase, its oxidative inactivation by H2O2 was studied and different strategies were evaluated with the aim of improving H2O2 stability. Oxidation of the methionine residues was produced during enzyme inactivation by H2O2 excess. Substitution of these residues, located near the heme cofactor and the catalytic tryptophan, rendered a variant with a 7.8-fold decreased oxidative inactivation rate. A second strategy consisted in mutating two residues (Thr45 and Ile103) near the catalytic distal histidine with the aim of modifying the reactivity of the enzyme with H2O2. The T45A/I103T variant showed a 2.9-fold slower reaction rate with H2O2 and 2.8-fold enhanced oxidative stability. Finally, both strategies were combined in the T45A/I103T/M152F/M262F/M265L variant, whose stability in the presence of H2O2 was improved 11.7-fold. This variant showed an increased half-life, over 30 min compared with 3.4 min of the native enzyme, under an excess of 2000 equivalents of H2O2. Interestingly, the stability improvement achieved was related with slower formation, subsequent stabilization and slower bleaching of the enzyme Compound III, a peroxidase intermediate that is not part of the catalytic cycle and leads to the inactivation of the enzyme.This work was funded by the Commission of the European Communities through the INDOX project (KBBE-2013-7-613549, "Optimized oxidoreductases for medium and large scale industrial biotransformations"), and by the Spanish Ministerio de Economía y Competitividad (MINECO) through the HIPOP project (BIO2011-26694, “Screening and engineering of new high-redoxpotential peroxidases”). VS-J and FJR-D thank the financial support of a research fellowship (Formación de Personal Investigador, FPI) and a Ramón y Cajal contract of the Spanish MINECO, respectively. The authors have no conflict of interest to declare. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer ReviewedPostprint (published version

Indoor radon measurements in Ny-Ålesund, the northernmost civilian settlement in the world

Ny-Ålesund is situated at 78° 55´ N, 11° 56´ E on the west coast of Spitsbergen, the largest island in the Svalbard archipelago and is a centre for international Arctic scientific research and environmental monitoring. Since 1916 to 1963 was an old coal mining town. Exposure to indoor radon has been identified as the second leading cause of lung cancer after tobacco smoking. In an indoor environment, there are many factors affecting indoor radon concentrations. Those factors could be different in the Arctic regions. [1] It is well known that the Council Directive 2013/59 / Euratom of 5 December 2013, article 74, says that "Member States shall establish national reference levels for indoor radon concentrations. The reference levels for the annual average activity concentration in air shall not be higher than 300 Bq m -3" so it is important to know the radon concentration in different places. Indoor radon activity measurements were carried out in different locations at Ny-Ålesund: Koldewey base (German base), KingsBay dining room, Marine Laboratory, and Gym facilities with five AlphaE devices from Saphymo GmbH. The AlphaE is an ultra small continuous radon monitor for professional use, based on a silicon diffusion chamber.The calculation of dose is possible due to a user-settable equilibrium factor. Indoor radon measurements were carried out from 3 to 27 September 2014. The values show low average level of indoor radon in the different analyzed buildings, with a geometrical mean of 60 Bq/m3 with a maximun value of 145 Bq/m3 in the Koldewey building. So the radiation exposure levels for workers and scientific personnel represents only a low percentage of the exposure guides for the general population.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

New Insights on Structures Forming the Lignin-Like Fractions of Ancestral Plants

In the present work, lignin-like fractions were isolated from several ancestral plants –including moss (Hypnum cupressiforme and Polytrichum commune), lycophyte (Selaginella kraussiana), horsetail (Equisetum palustre), fern (Nephrolepis cordifolia and Pteridium aquilinum), cycad (Cycas revoluta), and gnetophyte (Ephedra fragilis) species– and structurally characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) and two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy. Py-GC/MS yielded marker compounds characteristic of lignin units, except in the H. cupressiforme, P. commune and E. palustre “lignins, ” where they were practically absent. Additional structural information on the other five samples was obtained from 2D-NMR experiments displaying intense correlations signals of guaiacyl (G) units in the fern and cycad lignins, along with smaller amounts of p-hydroxyphenyl (H) units. Interestingly, the lignins from the lycophyte S. kraussiana and the gnetophyte E. fragilis were not only composed of G- and H-lignin units but they also incorporated significant amounts of the syringyl (S) units characteristic of angiosperms, which appeared much later in plant evolution, most probably due to convergent evolution. The latter finding is also supported by the abundance of syringol derivatives after the Py-GC/MS analyses of these two samples. Regarding lignin structure, β−O−4′ alkyl-aryl ethers were the most abundant substructures, followed by condensed β−5′ phenylcoumarans and β−β′ resinols (and dibenzodioxocins in the fern and cycad lignins). The highest percentages of alkyl-aryl ether structures correlated with the higher S/G ratio in the S. Kraussiana and E. fragilis lignin-like fractions. More interestingly, apart from the typical monolignol-derived lignin units (H, G and S), other structures, assigned to flavonoid compounds never reported before in natural lignins (such as amentoflavone, apigenin, hypnogenol B, kaempferol, and naringenin), could also be identified in the HSQC spectra of all the lignin-like fractions analyzed. With this purpose, in vitro synthesized coniferyl-naringenin and coniferyl-apigenin dehydrogenation polymers were used as standards. These flavonoids were abundant in H. cupressiforme appearing as the only constituents of the moss lignin-like fraction (including 84% of dimeric hypnogenol B) and their abundance decreased in those of S. Kraussiana (with amentoflavone and naringenin representing 14% of the total aromatic units), and the two ancient gymnosperms (0.4–1.2%) and ferns (0–0.7%)