The afterglow photosynthetic luminescence

The afterglow (AG) photosynthetic luminescence is a long-lived chlorophyll fluorescence emitted from PSII after the illumination of photosynthetic materials by FR or white light and placed in darkness. The AG emission corresponds to the fraction of PSII centers in the S2/3QB non-radiative state immediately after pre-illumination, in which the arrival of an electron transferred from stroma along cyclic/chlororespiratory pathway(s) produces the S2/3QB− radiative state that emits luminescence. This emission can be optimally recorded by a linear temperature gradient as sharp thermoluminescence (TL) band peaking at about 45°C. The AG emission recorded by TL technique has been proposed as a simple non-invasive tool to investigate the chloroplast energetic state and some of its metabolism processes as cyclic transport of electrons around PSI, chlororespiration or photorespiration. On the other hand, this emission has demonstrated to be a useful probe to study the effect of various stress conditions in photosynthetic materials.Junta de Andalucía PAIDI BIO-022Ministerio de Economía, Industria y Competitividad BIO2015-64169-

¿Qué es la radiación electromagnética?: usos beneficiosos y efectos perjudiciales

En el presente Trabajo Fin de Grado (TFG) se lleva a cabo una investigación encuadrada en un marco teórico sobre la Radiación Electromagnética, en el cual se recoge información sobre qué es y los tipos de radiaciones que existen además de qué beneficios y efectos perjudiciales tiene cada una de ellas en las vidas diarias y en la salud de los/as niños/as de segundo ciclo de Educación Primaria, teniendo en cuenta las utilidades que le dan en sus vidas a cada uno de estos tiposde radiación.Por otra parte también se recoge una programación didáctica,como propuesta de intervención,en la cual podemos encontrar una justificación y unos objetivos centrados en el aprendizaje de contenidos relacionados con el tema trabajado para hacérselos llegar a los/as niños/as. Para ello se ha realizado una serie de sesiones y actividades originales, dinámicas y motivadoras (recogidas en el trabajo).Universidad de Sevilla. Grado en Educación Primari

Peculiar properties of chlorophyll thermoluminescence emission of autotrophically or mixotrophically grown Chlamydomonas reinhardtii

The microalgae Chlamydomonas reinhardtii and Chlorella sp. CCAP 211/84 were grown autotrophically and mixotrophically and their thermoluminescence emissions were recorded above 0 °C after excitation by 1, 2 or 3 xenon flashes or by continuous far-red light. An oscillation of the B band intensity according to the number of flashes was always observed, with a maximum after 2 flashes, accompanied by a downshift of the B band temperature maximum in mixotrophic compared to autotrophic grown cells, indicative of a dark stable pH gradient. Moreover, new flash-induced bands emerged in mixotrophic Chlamydomonas grown cells, at temperatures higher than that of the B band. In contrast to the afterglow band observed in higher plants, in Chlamydomonas these bands were not inducible by far-red light, were fully suppressed by 2 μM antimycin A, and peaked at different temperatures depending on the flash number and growth stage, with higher temperature maxima in cells at a stationary compared to an exponential growth stage. These differences are discussed according to the particular properties of cyclic electron transfer pathways in C. reinhardtii.Ministerio de Educación y Cultura BFU2007-68107-C02-01/BMCJunta de Andalucía PAIDI CVI-26

Copper effect on cytochrome b559 of photosystem II under photoinhibitory conditions

The definitive version is available at www.blackwell-synergy.comToxic Cu(II) effect on Cytochrome b559 under aerobic photoinhibitory conditions was examined in two different PSII membrane preparations active in oxygen evolution. The preparations differ in the content of Cytochrome b559 redox potential forms. Difference absorption spectra showed that the presence of Cu(II) induced the oxidation of the high-potential form of Cytochrome b559 in the dark. Addition of hydroquinone reduced the total oxidised high-potential form of Cytochrome b559 present in Cu(II)-treated PSII membranes indicating that no conversion to the low-potential form took place. Spectroscopic determinations of Cytochrome b559 during photoinhibitory treatment showed slower kinetics of Cu(II) effect on Cytochrome b559 as compared to the rapid loss of oxygen evolution activity in the same conditions. This result indicates that Cytochrome b559 is affected after PSII centers are photoinhibited. The high-potential form was more sensitive to toxic Cu(II) action than the low-potential form under illumination at pH 6.0. The content of the high-potential form of Cytochrome b559 was completely lost, however the low-potential content was unaffected in these conditions. This loss did not involve cytochrome protein degradation. Results are discussed in terms of different binding properties of the heme iron to the protonated or unprotonated histidine ligand in the high-potential and low-potential forms of Cytochrome b559, respectively.M. Bernal was recipient of an I3P Programme fellowship from Consejo Superior de Investigaciones Científicas. This work was supported by the Dirección General de Investigación (Grant BMC2002-00031) to R.P. and Gobierno de Aragón (Grant P015/2001) to I.Y., and it has been done within GC DGA 2002 Program of Gobierno de Aragón.Peer reviewe

Problemas actuales de los derechos de autor en entornos digitales: su tratamiento en Derecho español y alemán

Este Trabajo Fin de Grado tiene por objeto analizar si en la actualidad se producen vulneraciones de los derechos de propiedad intelectual a través del empleo de las redes P2P desde el prisma del ordenamiento jurídico español y alemá

Photosynthetic cytochrome c550

Cytochrome c550 (cyt c550) is a membrane component of the PSII complex in cyanobacteria and some eukaryotic algae, such as red and brown algae. Cyt c550 presents a bis-histidine heme coordination which is very unusual for monoheme c-type cytochromes. In PSII, the cyt c550 with the other extrinsic proteins stabilizes the binding of Cl− and Ca2 + ions to the oxygen evolving complex and protects the Mn4Ca cluster from attack by bulk reductants. The role (if there is one) of the heme of the cyt c550 is unknown. The low midpoint redox potential (Em) of the purified soluble form (from − 250 to − 314 mV) is incompatible with a redox function in PSII. However, more positive values for the Em have been obtained for the cyt c550 bound to the PSII. A very recent work has shown an Em value of + 200 mV. These data open the possibility of a redox function for this protein in electron transfer in PSII. Despite the long distance (22 Å) between cyt c550 and the nearest redox cofactor (Mn4Ca cluster), an electron transfer reaction between these components is possible. Some kind of protective cycle involving a soluble redox component in the lumen has also been proposed. The aim of this article is to review previous studies done on cyt c550 and to consider its function in the light of the new results obtained in recent years. The emphasis is on the physical properties of the heme and its redox properties. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.Ministerio de Ciencia e Innovación BFU2007-68107-C02-01Junta de Andalucía PADI CVI-26

In vivo reconstitution of a homodimeric cytochrome b559 like structure: The role of the N-terminus a-subunit from Synechocystis sp. PCC 6803

The cytochrome b559 is a heme-bridged heterodimeric protein with two subunits, a and ß. Both subunits from Synechocystis sp. PCC 6803 have previously been cloned and overexpressed in Escherichia coli and in vivo reconstitution experiments have been carried out. The formation of homodimers in the bacterial membrane with endogenous heme was only observed in the case of the ß-subunit (ß/. ß) but not with the full length a-subunit. In the present work, reconstitution of a homodimer (a/. a) cytochrome b559 like structure was possible using a chimeric N-terminus a-subunit truncated before the amino acid isoleucine 17, eliminating completely a short amphipathic a-helix that lays on the surface of the membrane. Overexpression and in vivo reconstitution in the bacteria was clearly demonstrated by the brownish color of the culture pellet and the use of a commercial monoclonal antibody against the fusion protein carrier, the maltoside binding protein, and polyclonal antibodies against a synthetic peptide of the a-subunit from Thermosynechococcus elongatus. Moreover, a simple partial purification after membrane solubilization with Triton X-100 confirmed that the overexpressed protein complex corresponded with the maltoside binding protein-chimeric a-subunit cytochrome b559 like structure. The features of the new structure were determined by UV-Vis, electron paramagnetic resonance and redox potentiometric techniques. Ribbon representations of all possible structures are also shown to better understand the mechanism of the cytochrome b559 maturation in the bacterial cytoplasmic membrane

Carbon dioxide-mediated decomposition of hydrogen peroxide in alkaline solutions

Rapid hydrogen peroxide decomposition in aerated alkaline solutions is described, the maximum rate being attained at pH values between 11.5 and 11.7, where the peroxide (pKa = 11.7) is ca. 50% unprotonated. The reaction proceeds with the release of protons and is strictly dependent upon the continuous presence of carbon dioxide, but not of carbonate anions, in the peroxide solutions. The following two-step mechanism is proposed: (1) formation of percarbonic acid (H2CO4 ) by condensation of C02 with the undissociated peroxide (H202 ) and (2) reduction of the acid by perhydroxyl anions (HO;)

Morbilidad psiquiátrica entre trabajadores de salud mental.

La influencia del medio laboral en la salud mental de los trabajadores es un tema que interesa cada día más en la Medicina del Trabajo y en todas las disciplinas relacionadas con la Salud Mental. Este estudio tiene como objetivo determinar la prevalencia probable de morbilidad psiquiátrica en los trabajadores de un Hospital Psiquiátrico en el nivel 1 descrito por Goldberg y Huxley que representa a la comunidad y que corresponde a la evaluación de poblaciones completas, o bien muestras representativas de poblaciones concretas

The heterologous expression of a plastocyanin in the diatom Phaeodactylum tricornutum improves cell growth under iron-deficient conditions

We have investigated if the heterologous expression of a functional green alga plastocyanin in the diatom Phaeodactylum tricornutum can improve photosynthetic activity and cell growth. Previous in vitro assays showed that a single-mutant of the plastocyanin from the green algae Chlamydomonas reinhardtii is effective in reducing P. tricornutum photosystem I. In this study, in vivo assays with P. tricornutum strains expressing this plastocyanin indicate that even the relatively low intracellular concentrations of holo-plastocyanin detected (≈4 μM) are enough to promote an increased growth (up to 60%) under iron-deficient conditions as compared with the WT strain, measured as higher cell densities, content in pigments and active photosystem I, global photosynthetic rates per cell, and even cell volume. In addition, the presence of plastocyanin as an additional photosynthetic electron carrier seems to decrease the over-reduction of the plastoquinone pool. Consequently, it promotes an improvement in the maximum quantum yield of both photosystem II and I, together with a decrease in the acceptor side photoinhibition of photosystem II—also associated to a reduced oxidative stress—a decrease in the peroxidation of membrane lipids in the choroplast, and a lower degree of limitation on the donor side of photosystem I. Thus the heterologous plastocyanin appears to act as a functional electron carrier, alternative to the native cytochrome c6, under iron-limiting conditions.Junta de Andalucía PAIDI BIO-022Ministerio de Economía y Competitividad BIO2015-64169-