Datos preliminares sobre los efectos crónicos de la radiación ultravioleta en la dinámica poblacional de especies fitoplanctónicas del Canal del Beagle, Argentina

Serious concerns exist that the thinning of stratospheric ozone and the resulting enhancement in the solar UVB radiation, may impair marine primary productivity. Also, UVB may alter food web dynamics and food availability for higher trophic levels in marine ecosystems inducing changes in phytoplankton species composition. The main goal of this study was to examine the responses of different species of marine phytoplankton to solar UVR. Specifically, we compared the UV sensitivity of a phytoplankton natural community isolated from the Beagle Channel (54°52´S, 68°18´W, Ushuaia, Argentina), as well as the response of two taxa which were isolated from that community (i.e., a pennate diatom, Navicula sp., and a phytoflagellate pertaining to the Class Cryptophyceae) to UV radiation. Exposure to UVB or UVA radiation treatments had no significant effects (p > 0.05) on exponential growth rate in Navicula sp. However, when the phytoflagellate [Class Cryptophyceae] was exposed to UVB, the growth rate in the exponential phase was inhibited significantly (p 0.05) en la tasa de crecimiento exponencial cuando Navicula sp. fue expuesta a UVB ó UVA (320-400 nm). Sin embargo, cuando los fitoflagelados [Clase Cryptophyceae] fueron expuestos a UVB, su tasa de crecimiento fue inhibida significativamente (p < 0.01). Al exponer a la comunidad fitoplanctónica se observaron cambios en la abundancia relativa de las especies. El porcentaje de fitoflagelados fue significativamente menor (p < 0.05) al ser expuestos a UVB comparado con PAR (400-700 nm). El porcentaje de diatomeas céntricas, en cambio, aumentó significativamente (p < 0.05). No se observaron diferencias significativas entre los diferentes días de exposición ni entre tratamientos en la respuesta de las diatomeas pennadas. El crecimiento exponencial de la comunidad fue inhibido significativamente (p < 0.01) cuando las algas fueron expuestas a UVB y UVA

Palatosquisis en la especie canina

La palatosquisis o paladar secundario hendido es una de las anomalías congénitas más corrientes que presentan los cachorros alnacimiento. Se describen las técnicas más habituales de corrección y la utilizada por los autores.Paiaiosquisis or secondary cleft palate is one of the most frequent congenital abnormalities shown by newborn pups. Commonly used correction techniques and that used by the authors are described

Electron irradiation induced reduction of the permittivity in chalcogenide glass (As2S3) thin film

We investigate the effect of electron beam irradiation on the dielectric properties of As2S3 Chalcogenide glass. By means of low-loss Electron Energy Loss Spectroscopy, we derive the permittivity function, its dispersive relation, and calculate the refractive index and absorption coefficients under the constant permeability approximation. The measured and calculated results show, to the best of our knowledge, a heretofore unseen phenomenon: the reduction in the permittivity of <40%, and consequently a modification of the refractive index follows, reducing it by 20%, hence suggesting a significant change on the optical properties of the material. The plausible physical phenomena leading to these observations are discussed in terms of the homopolar and heteropolar bond dynamics under high energy absorption.Comment: 22 pages, 7 figures, manuscript in preparation to send to Physical Review

Changes on grape volatile composition after elicitors and nitrogen compounds foliar applications to 'Garnacha', 'Tempranillo' and 'Graciano' vines

Grape volatile compounds determine the wine quality and typicity. The aim of this work was to study the effects of several foliar applications in 'Garnacha', 'Tempranillo', and 'Graciano' grapevines in order to enhance their grape volatile composition. The field trial involved the application of two nitrogen compounds, urea (Ur) and phenylalanine (Phe), and two elicitors, methyl jasmonate (MeJ) and a yeast extract (YE). The analysis of grape volatile compounds was carried out by HS-SPME-GC-MS. For 'Garnacha', most terpenes, and C13 norisoprenoids increased their grape content by applying Ur and Phe, and especially MeJ. For 'Tempranillo', treatments with Ur and MeJ improved the synthesis of most terpenoids. For 'Graciano', a trend to decrease the terpenoids content in grapes with the treatments was observed; however, Phe application increased C13 norisoprenoids content. In conclusion, foliar application of, Phe or Ur, and an elicitor, MeJ, can be a useful tool to improve grape quality

Hydrophobic-electrostatic balance driving the LCST offset aggregation-redissolution behavior of N-alkylacrylamide-based ionic terpolymers

A series of random terpolymers composed of N-isopropylacrylamide (NIPAAm), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), and N-tert-butylacrylamide (NTBAAm) monomers were synthesized by free radical polymerization. The molar fraction of the negatively charged monomer (AMPS) was maintained constant (0.05) for all studied terpolymer compositions. Turbidity measurements were used to evaluate the influence of the relative amount of NIPAAm and NTBAAm, polymer concentration, and solution ionic strength on the cloud point and redissolution temperatures (macroscopic phase separation). Dynamic light scattering (DLS) was employed to elucidate some aspects regarding the molecular scale mechanism of the temperature-induced phase separation and to determine the low critical solution temperature (LCST). The aqueous solutions of terpolymers remained clear at all studied temperatures; turbidity was only observed in the presence of NaCl. The cloud point temperature (CPT) determined by turbidimetry was found to be systematically much higher than the LCST determined by DLS; nanosized aggregates were observed at temperatures between the LCST and the CPT. Both CPT and LCST decreased when increasing the molar ratio of NTBAAm (increased hydrophobicity). It was found that above a critical molar fraction of NTBAAm (0.25-0.30) the aggregation rate suddenly decreased. Polymers with NTBAAm content lower than 0.25 showed a fast macroscopic phase separation, but the formed large aggregates are disaggregating during the cooling ramp at temperatures still higher than the LCST. On the contrary, polymers withNTBAAmcontents above 0.30 showed a slow macroscopic phase separation, and the formed large aggregates only redissolved when LCST was reached. These differences were explained on the basis of a delicate balance between the electrostatic repulsion and the hydrophobic attractive forces, which contribute cooperatively to the formation of metastable nanosized aggregates.The authors acknowledge funding from EU Marie Curie Actions, Alea Jacta Est (MEST-CT-2004-008104), and Portuguese Foundation For Science and Technology (FCT) (SFRH/BPD/34545/2007). This work was carried out under the scope of the European NoE EXPERTISSUES (NMP3-CT-2004-500283)

Hepatic Spheroid Formation on Carbohydrate-Functionalized Supramolecular Hydrogels

Two synthetic supramolecular hydrogels, formed from bis-urea amphiphiles containing lactobionic acid (LBA) and maltobionic acid (MBA) bioactive ligands, are applied as cell culture matrices in vitro. Their fibrillary and dynamic nature mimics essential features of the extracellular matrix (ECM). The carbohydrate amphiphiles self-assemble into long supramolecular fibers in water, and hydrogels are formed by physical entanglement of fibers through bundling. Gels of both amphiphiles exhibit good self-healing behavior, but remarkably different stiffnesses. They display excellent bioactive properties in hepatic cell cultures. Both carbohydrate ligands used are proposed to bind to asialoglycoprotein receptors (ASGPRs) in hepatic cells, thus inducing spheroid formation when seeding hepatic HepG2 cells on both supramolecular hydrogels. Ligand nature, ligand density, and hydrogel stiffness influence cell migration and spheroid size and number. The results illustrate the potential of self-assembled, carbohydrate-functionalized hydrogels as matrices for liver tissue engineering.</p

Consumo de tabaco y práctica de actividad física en una población melillense

Introduction: Tobacco use is considered a risk factor in the development of multiple pathologies at the pulmonary and cardio-vascular levels, among others. In this sense, the practice of physical activity is considered a factor of protection. Objective: To describe the socio-demographic variables and quality of life in terms of tobacco use and the practice of physical activity in a Melillense population. Material and Method: Research work with quantitative design, descriptive and cross section of a sample of residents in Melilla, about tobacco use and the practice of physical activity. Results: More than three-quarters of the participants said no smoking and three out of ten subjects did not perform any physical activity. Conclusions: We must continue working to strengthen healthy behaviors in the population, in relation to the consumption of harmful substances and the practice of physical activity.Introducción: El consumo de tabaco es considerado factor de riesgo ante el desarrollo de múltiples patologías a nivel pulmonar y cardio-vascular, entre otras. En este sentido, la práctica de actividad física es considerada un factor de protección. Objetivo: Describir las variables socio-demográficas y de calidad de vida en cuanto al consumo de tabaco y la práctica de actividad física en una población Melillense. Material y Método: Trabajo de investigación con diseño cuantitativo, de carácter descriptivo y corte transversal de una muestra de residentes en Melilla, acerca del consumo de tabaco y la práctica de actividad física. Resultados: Más de tres cuartas partes de los participantes manifestaron no fumar tabaco y tres de cada diez sujetos no realizaba ningún tipo de actividad física.&nbsp;Conclusiones: Hay que seguir trabajando por afianzar conductas saludables en la población, en relación al consumo de sustancias nocivas y la práctica de actividad física