Structural Stability of the PsbQ Protein of Higher Plant Photosystem II

We have characterized the stability and folding behavior of the isolated extrinsic PsbQ protein of photosystem II (PSII) from a higher plant, Spinacia oleracea, using intrinsic protein fluorescence emission and near- and far-UV circular dichroism (CD) spectroscopy in combination with differential scanning calorimetry (DSC). Experimental results reveal that both chemical denaturation using guanidine hydrochloride (GdnHCl) and thermal unfolding of PsbQ proceed as a two-state reversible process. The denaturation free-energy changes (GD) at 20 C extrapolated from GdnHCl (4.0 ± 0.6 kcal mol-1) or thermal unfolding (4.4 ± 0.8 kcal mol-1) are very close. Moreover, the far-UV CD spectra of the denatured PsbQ registered at 90 C in the absence and presence of 6.0 M GdnHCl superimpose, leading us to conclude that both denatured states of PsbQ are structurally and energetically similar. The thermal unfolding of PsbQ has been also characterized by CD and DSC over a wide pH range. The stability of PsbQ is at its maximum at pH comprised between 5 and 8, being wider than the optimal pH for oxygen evolution in the lumen of thylakoid membranes. In addition, no significant structural changes were detected in PsbQ between 50 and 55 C in the pH range of 3-8, suggesting that PsbQ behaves as a soluble and stable particle in the lumen when it detaches from PSII under physiological stress conditions such as high temperature (45-50 C) or low pH (<5.0). Sedimentation experiments showed that, in solution at 20 C, the PsbQ protein is a monomer with an elongated shape.Spanish Minitry of Science and Technology (PB1998-0480 and AGL2004-00045)This work was funded by the Spanish Ministry of Science and Technology (project references PB1998-0480 and AGL2003-0045). M.B. holds a fellowship from the Spanish Ministry of Science and Technology.Peer reviewe

Bibliografía histórica sobre la ciencia y la técnica en España. 1989

Not available.No disponible

Bibliografía Histórica sobre la Ciencia y la Técnica En España. 1990

Not available.No disponible

Zein-based nanospheres and nanocapsules for the encapsulation and oral delivery of quercetin

In this study, the ability of zein nanospheres (NS) and zein nanocapsules containing wheat germ oil (NC) to enhance the bioavailability and efficacy of quercetin was evaluated. Both types of nanocarriers had similar physico-chemical properties, including size (between 230 and 250 nm), spherical shape, negative zeta potential, and surface hydrophobicity. However, NS displayed a higher ability than NC to interact with the intestinal epithelium, as evidenced by an oral biodistribution study in rats. Moreover, both types of nanocarriers offered similar loading efficiencies and release profiles in simulated fluids. In C. elegans, the encapsulation of quercetin in nanospheres (Q-NS) was found to be two twice more effective than the free form of quercetin in reducing lipid accumulation. For nanocapsules, the presence of wheat germ oil significantly increased the storage of lipids in C. elegans; although the incorporation of quercetin (Q-NC) significantly counteracted the presence of the oil. Finally, nanoparticles improved the oral absorption of quercetin in Wistar rats, offering a relative oral bioavailability of 26% and 57% for Q-NS and Q-NC, respectively, compared to a 5% for the control formulation. Overall, the study suggests that zein nanocarriers, particularly nanospheres, could be useful in improving the bioavailability and efficacy of quercetin

Analytical pyrolysis evidences the presence of granaticins in the violet stains of a Roman tomb

6 páginas.-- 5 figuras.-- 14 referenciasThe walls of the Circular Mausoleum tomb (Roman Necropolis of Carmona, Spain) exhibit an important number of violet stains of unknown origin. Analytical pyrolysis detected in the tomb walls granaticin A, a violet pigment with an isobenzochromanequinone structure, as well as in the extracts of two bacterial strains isolated from the walls. The bacterium was tentatively identified as Streptomyces sp. High performance liquid chromatography confirmed that this Streptomyces synthesized as major pigments dihydrogranaticin A, granaticin A and granaticin B.This research was funded by projects GCL2010-17183 and 201230E125. M.D.H. and A.Z.M. were supported by a JAE Research Fellowship from CSIC, and a Marie Curie Intra-European Fellow-ship of the European Commission’s 7th Framework Programme(PIEF-GA-2012-328689), respectivelyPeer reviewe

The emergence and historical evolution of innovation networks:On the factors promoting and hampering patent collaboration in technological lagging economies

Collaboration and research networks are nowadays central to innovation because they favor knowledge interactions and complex approaches to challenging problems. This study explores the factors underlying the emergence and evolution of innovation networks in the past, using as example the case of Spain, a backward country regarding R&amp;D performance. Combining, for the first time, historical patent data, social network analysis, and discrete choice regression techniques we test distinct institutional, geographical, and sectoral factors that triggered or hampered collaboration over the long term, i.e., the growth in the connections of individual co-patentees within innovation groups. The findings are relevant and demonstrate, inter alia, that in the Spanish case the length of intellectual monopolies did not foster collaboration, while geographical/technological diversification was key to enhance collaborative patterns in the past. The analysis also demonstrates that the likelihood of increasing collaboration over time depended on the initial level of connections (degree) the patentee had, confirming the existence of preferential attachment, even within the context of an emerging and disconnected network. However, belonging to larger innovation groups (size of the network components) did not promote per se greater interactions, suggesting that institutional weaknesses and backward innovation trends prevented the existence of positive payoffs from increased connectivity. The results have direct R&amp;D policy implications for both nowadays developing countries and innovation leaders.</p

The making and consolidation of the first national trademark system: the diffusion of trademarks across Spanish regions, 1850–1920

This article studies the creation and consolidation of a trademark system tantamount to market integration and commercial specialization of Spanish regions from 1850 to 1920. We analyse the first 47,000 registrations, their geographical distribution and the drivers behind this trademark expansion. By using a lineal probability model, we find that knowledge spillovers across regions are associated with their relative trademark specialization and diversification. We incorporate the role played by transport infrastructure by calculating generalized transport costs. The results clarify the origins and evolution of geographical differences in commercial innovation and regional specialization in the first country to institute modern trademark legislation

Draft Genome Sequences of Two Streptomyces Strains, MZ03-37T and MZ03-48, Isolated from Lava Tube Speleothems

2 páginas.- 1 tabla.- 15 referencias.- Genome SequencesTwo Streptomyces strains were isolated from a lava tube in La Palma, Canary Islands. Genomic analyses suggest that the two strains could belong to the same species. Here, we report the draft genomes for these bacterial strains.Financial support was obtained through project 0483_PROBIOMA_5_E, cofinanced by the European Regional Development Fund within the framework of the Interreg V-A Spain-Portugal program (POCTEP) (2014 to 2020).Peer reviewe

Structural Stability of the PsbQ Protein of Higher Plant Photosystem II

We have characterized the stability and folding behavior of the isolated extrinsic PsbQ protein of photosystem II (PSII) from a higher plant, Spinacia oleracea, using intrinsic protein fluorescence emission and near- and far-UV circular dichroism (CD) spectroscopy in combination with differential scanning calorimetry (DSC). Experimental results reveal that both chemical denaturation using guanidine hydrochloride (GdnHCl) and thermal unfolding of PsbQ proceed as a two-state reversible process. The denaturation free-energy changes (GD) at 20 C extrapolated from GdnHCl (4.0 ± 0.6 kcal mol-1) or thermal unfolding (4.4 ± 0.8 kcal mol-1) are very close. Moreover, the far-UV CD spectra of the denatured PsbQ registered at 90 C in the absence and presence of 6.0 M GdnHCl superimpose, leading us to conclude that both denatured states of PsbQ are structurally and energetically similar. The thermal unfolding of PsbQ has been also characterized by CD and DSC over a wide pH range. The stability of PsbQ is at its maximum at pH comprised between 5 and 8, being wider than the optimal pH for oxygen evolution in the lumen of thylakoid membranes. In addition, no significant structural changes were detected in PsbQ between 50 and 55 C in the pH range of 3-8, suggesting that PsbQ behaves as a soluble and stable particle in the lumen when it detaches from PSII under physiological stress conditions such as high temperature (45-50 C) or low pH (<5.0). Sedimentation experiments showed that, in solution at 20 C, the PsbQ protein is a monomer with an elongated shape.Spanish Minitry of Science and Technology (PB1998-0480 and AGL2004-00045)This work was funded by the Spanish Ministry of Science and Technology (project references PB1998-0480 and AGL2003-0045). M.B. holds a fellowship from the Spanish Ministry of Science and Technology.Peer reviewe

Draft Genome Sequence of a Granaticin-Producing Strain of Streptomyces parvus Isolated from a Roman Tomb in the Necropolis of Carmona, Spain

2 páginas.- 17 referencias.- Data availability. This whole-genome shotgun project has been deposited at DDBJ/ENA/GenBank under the accession number VSZQ00000000. The version described in this paper is the first version, VSZQ01000000. BioProject and raw data are available at the accession numbers PRJNA562075 and SRR10059654, respectively.Streptomyces parvus strain C05 was isolated from the walls of a Roman tomb located in Carmona, Seville, Spain. Subsequent studies determined the capability of this strain for producing granaticins. Here, we report the 8.7-Mbp draft genome sequence for this bacterium.Financial support was obtained through project 0483_PROBIOMA_5_E, cofinanced by the European Regional Development Fund within the framework of the Interreg V-A Spain-Portugal program (POCTEP) 2014 –2020.Peer reviewe