Alteraciones en la tasa de respiración de Daphnia magna bajo concentraciones subletales de anatoxina-a

Anatoxina-a es una potente neurotoxina producida por cianobacterias dulceacuícolas que puede representar un riesgo, por sus efectos agudos, para diferentes formas de vida, incluyendo los seres humanos. Aunque se conocen los efectos agudos y crónicos de esta toxina, pocos estudios aportan datos de medidas de efectos subletales sobre la respiración del zooplancton. En este trabajo se cuantifican cambios en la respiración de Daphnia magna bajo una concentración subletal de anatoxina-a, en condiciones experimentales, por medio de un sistema automatizado de medida en continuo de consumo de Oxígeno. Los resultados indican que la presencia de anatoxina-a en dosis subletales reduce significativamente la actividad respiratoria en esta especie, con efectos, dependientes de la edad del organismo.Anatoxin-a is a potent neurotoxin produced by some freshwater cyanobacteria which, because of its acute toxic effects, may represent a hazard to aquatic organisms, and even to human beings. Both the acute and chronic effects of this toxin are rather well known, but few studies provided information about its sublethal effect on the zooplankton respiration. In this paper we have quantified respiration changes in Daphnia magna under sublethal anatoxin-a concentrations in experimental conditions, using an automatic open-flow system of continuous measurement of oxygen consumption. Our results show that the presence of anatoxin-a at sublethal doses reduces significantly the respiratory activity of the animals, being the effects greatly dependent on the individual age

La influencia de las fuentes de información en la elección del consumo turístico: el caso del turismo académico en Santiago de Compostela

Este artigo trata das fontes de informações utilizadas por estudantes brasileiros para conhecer Santiago de Compostela. Elas são as responsáveis por apresentar o destino turístico, além de poder influenciar na sua capacidade de atração. A pesquisa se desenvolve sob uma metodologia mêsta elaborada em duas etapas com entrevistas e modelagem das equações estruturais. Foi assim idealizada para que seja o sujeito quem ofereça as suas impressões sobre o destino, isto é, a ferramenta de medida utilizada na segunda etapa foi criada com base na visão do fenômeno turístico relacionado com a experiência vivida pelo indivíduo. O objetivo principal é identificar as principais fontes de informação utilizadas pelo turista acadêmico. Ademais, também se espera identificar como a mensagem transmitida por estas fontes influencia o processo de formação da imagem do destino. Em quanto ao nível teórico, com este trabalho se espera promover uma discussão sobre a importância da seleção de ferramentas acertadas na estratégia de promoção da imagem turística. Com esta pesquisa se conclui que o uso das novas tecnologias pelo turista durante sua estadia pode aumentar a credibilidade das informações divulgadas, pois o indivíduo, além de consumidor passa a ter um importante papel na produção da informação.This article examines the information sources used by Brazilian students to obtain information about Santiago de Compostela. These sources are responsible for introducing the tourist destination and can influence its attractiveness. The research was performed using a mixed method approach divided into two stages: qualitative (interviews) and quantitative (structural equation modeling). It was designed so that each individual described his or her impressions about the destination. The measuring tool used in the second step of the research was based on the perception of the tourism phenomenon, specifically, the experience of the individual. This article aims to identify the main information sources used by the academic tourist, the credibility of this information and how these sources can influence tourist consumer behavior. As to the theoretical approach, this study seeks to promote a discussion on the importance of the selection of adequate tools for tourism image promotion strategies. It was concluded that the use of new technologies by tourists during their stay can increase the credibility of the information generated. As well as being a consumer, the tourist also plays an important role in the production of information about the tourist destination.Esta investigación trata de las fuentes de informaciones utilizadas por estudiantes brasileños para conocer Santiago de Compostela. Estas fuentes son las responsables de presentar el destino turístico, además de poder influir en su capacidad de atracción. El trabajo se desarrolla bajo una metodología mixta elaborada en dos etapas: cualitativa (entrevistas) y cuantitativa (modelo de ecuaciones estructurales). Se concibión com el objeto de que sea el sujeto quien ofrezca sus impresiones sobre el destino, es decir, la herramienta de medida utilizada en la segunda etapa fue diseñada con base en la visión del fenómeno turístico, exactamente en la experiencia vivida por el individuo. En este artículo se trabajan las fuentes orgánicas y autónomas, la credibilidad de la información y su influencia en el comportamiento del consumidor turístico. En cuanto al nivel teórico, con este trabajo se espera promover una discusión sobre la importancia de la selección de herramientas acertadas en la estrategia de promoción de la imagen turística. Asimismo, se concluye que el uso de las nuevas tecnologías por el turista durante su estadía puede aumentar la credibilidad de las informaciones, dado que el individuo además de consumidor pasa a tener un importante papel en la producción de información

Candida glabrata’s recurrent infections: biofilm formation during Amphotericin B treatment

Candida species are responsible for recurrent human infections, mostly in immunocompromised patients, due to their high vulnerability. Candida glabrata has a major role in systemic candidiasis and Amphotericin B (AmB), a hospital environment exclusive polyene, is frequently used to treat this disease. Lately, however, clinical evidences of Candida recurrent infections during these treatments are being described, probably due to biofilms (re)formation during this therapy. Thus, this work aims at inferring if C. glabrata biofilms are still being formed during AmB treatment. For that, C. glabrata biofilms were formed in the presence of AmB and analysed by dry weight. Matrix composition was analysed quantifying carbohydrates and, specifically, -1,3 glucans. Results demonstrated that, although in a lesser extent, C. glabrata is able to develop biofilms in the presence of AmB, with a thick extracellular matrix, with an increase on carbohydrates, especially -1,3 glucans. Therefore, it is confirmed that complex biofilms of C. glabrata can be formed during an AmB treatment.This work was supported by the Programa Operacional, Fatores de competitividade – COMPETE and by national funds through FCT – Fundação para a Ciência e a Tecnologia on the scope of the projects FCT PTDC/SAUMIC/119069/2010, RECI/EBB-EBI/0179/2012, PEst-OE/ EQB/LA0023/2013 and C elia F. Rodrigues’ SFRH/BD/ 93078/2013 PhD grant. The authors thank the Project ‘BioHealth - Biotechnology and Bioengineering approaches to improve health quality’, Ref. NORTE-07-0124-FEDER- 000027, co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER

Origin of anomalously long interatomic distances in suspended gold chains

The discovery of long bonds in gold atom chains has represented a challenge for physical interpretation. In fact, interatomic distances frequently attain 3.0-3.6 A values and, distances as large as 5.0 A may be seldom observed. Here, we studied gold chains by transmission electron microscopy and performed theoretical calculations using cluster ab initio density functional formalism. We show that the insertion of two carbon atoms is required to account for the longest bonds, while distances above 3 A may be due to a mixture of clean and one C atom contaminated bonds.Comment: 4 pages, 4 Postscript figures, to be published in Physical Review Letter

Leibnizian, Galilean and Newtonian structures of spacetime

The following three geometrical structures on a manifold are studied in detail: (1) Leibnizian: a non-vanishing 1-form $\Omega$ plus a Riemannian metric \h on its annhilator vector bundle. In particular, the possible dimensions of the automorphism group of a Leibnizian G-structure are characterized. (2) Galilean: Leibnizian structure endowed with an affine connection $\nabla$ (gauge field) which parallelizes $\Omega$ and \h. Fixed any vector field of observers Z ($\Omega (Z) = 1$), an explicit Koszul--type formula which reconstruct bijectively all the possible $\nabla$'s from the gravitational ${\cal G} = \nabla_Z Z$ and vorticity $\omega = rot Z/2$ fields (plus eventually the torsion) is provided. (3) Newtonian: Galilean structure with \h flat and a field of observers Z which is inertial (its flow preserves the Leibnizian structure and $\omega = 0$). Classical concepts in Newtonian theory are revisited and discussed.Comment: Minor errata corrected, to appear in J. Math. Phys.; 22 pages including a table, Late

Dialogic gathering of films. Promoting meaningful online interactions during COVID-19 confinement

A broad body of scientific literature exists on the effects that COVID-19 related confinement has had on the population: mental health problems, isolation, and problems concerning cohesion and employment, among others. However, there is a gap in the literature on the actions that reverse some of the effects generated during lockdown. This article collects the results of a study conducted with 53 people participating in a dialogic gathering of films (DGF) that was held online during two months of confinement. The data from the survey show that the development of this DGF generated improvements in 1) personal welfare and attitudes concerning the management of confinement, 2) living together and online relationships, 3) motivation and creativity in the professional domain, and 4) openness to a diversity of perspectives and realities, which improves the understanding, argumentation and positioning in social, scientific and ethical debates

Moist and warm conditions in Eurasia during the last glacial of the Middle Pleistocene Transition

The end of the Middle Pleistocene Transition (MPT, ~ 800-670 thousand years before present, ka) was characterised by the emergence of large glacial ice-sheets associated with anomalously warm North Atlantic sea surface temperatures enhancing moisture production. Still, the direction and intensity of moisture transport across Eurasia towards potential ice-sheets is poorly constrained. To reconstruct late MPT moisture production and dispersal, we combine records of upper ocean temperature and pollen-based Mediterranean forest cover, a tracer of westerlies and precipitation, from a subtropical drill-core collected off South-West Iberia, with records of East Asia summer monsoon (EASM) strength and West Pacific surface temperatures, and model simulations. Here we show that south-western European winter precipitation and EASM strength reached high levels during the Marine Isotope Stage 18 glacial. This anomalous situation was caused by nearly-continuous moisture supply from both oceans and its transport to higher latitudes through the westerlies, likely fuelling the accelerated expansion of northern hemisphere ice-sheets during the late MPT. © 2023, The Author(s).This research used samples collected during the Expedition no. 339 “Mediterranean Outflow“ of the Integrated Ocean Drilling Program (IODP). M.F.S.G. acknowledges funding from the GPR Human Past (University of Bordeaux). A.B. thanks Deutsche Forschungsgemeinschaft (DFG), project BA 3809/8. C.Z. acknowledges funding from IODP France and J.M.P.-M. from the Junta de Castilla y León and the European Regional Development Fund (Grant CLU-2019-03). T.R. acknowledges funding from FCT through projects Hydroshift (PTDC/CTA-CLI/4297/2021), WarmWorld (PTDC/CTA-GEO/29897/2017), UIDB/04326/2020, UIDP/04326/2020, LA/P/0101/2020 and EMSO-PT (POCI-01-0145-FEDER-022157). We thank Vincent Hanquiez for drawing Fig. and Ludovic Devaux for pollen sample preparation

Transcriptomic landscape of the kleptoplastic sea slug Elysia viridis

The longevity of kleptoplasts and sea slugs during starvation may be mediated by multiple factors, including the recognition of the plastids during feeding by multiple receptors (e.g. PRRs, CTLRs and SRs) and ROS-quenching proteins using enzymatic and nonenzymatic mechanisms. In particular, in the transcriptome of E. viridis we found that the presence of CDSs corresponds to multiple PRRs that may be involved in the plastid-recognition process; this is despite the fact that this species has a low receptor richness in comparison with other elysoids (Melo Clavijo et al., 2020). In addition, we also detected multiple enzymatic families involved in the ROS-quenching response. In contrast, the production of antioxidant compounds may contribute in only a minor way to the control of oxidative stress. A further enriched GO category in species that sequester chloroplasts corresponded to G protein-coupled receptors, which suggests that these receptors may be required for plastid recognition in Sacoglossan sea slugs, paralleling their role in other symbioses, such as the mutualism between cnidarians and dinoflagellates (Rosset et al., 2020). Sacoglossan sea slugs may also require the presence of iron ions to reduce the oxidative stress generated after plastid acquisition. All this evidence, derived from the transcriptome analysis of E. viridis, sheds interesting new light on the possible mechanisms used by sea slugs to recognize and establish kleptoplasts within their bodies.Xunta de Galicia | Ref. GPC2014/067Xunta de Galicia | Ref. ED481A-2018/30