153 research outputs found
El impacto de la nueva legislación en la investigación con animales
The implementation of the European Directive 63/2010 implies an important legal change in Europe affecting research that involves the use of animals. Some of these changes had been implemented already in Spain. Others will require a costly and complex adaptation in a difficult economical scenario with an impact that is difficult to foresee.La entrada en vigor de la Directiva Europea 63/2010 supone un cambio jurídico importante en la investigación con animales realizada en Europa. Parte de esos cambios ya habían sido incorporados en nuestro país. Otros requerirán una adaptación costosa y compleja en el marco económico actual, con un impacto difícilmente predecible
La evaluación en la Universidad. Una aproximación en clave social y vital
¿Cómo pensar la evaluación en la universidad de otra manera?. Esta pregunta parte de un afecto, a saber, la insatisfacción en la que nos sitúa muchas veces el propio proceso de evaluar. Este texto responde a una indagación de dicho afecto, ahondando las razones e intereses que subyacen a este proceso tan social y vital como académico y administrativo. Revisar la evaluación exige, al mismo tiempo, pensar acerca de los fines de la universidad. Por tanto, lo que se requiere no es una discusión metodológica, sino una búsqueda de sentido a un proceso, las más de las veces, trivializado. Pensar la
evaluación es cogerla entre las manos para conocer cómo nos afecta y, con ello, cómo podríamos mejorarl
In vitro and in vivo development of mice morulae after storage in non-frozen conditions
Background Interchange of genetically modified (GM) mice between laboratories using embryos provides several advantages. Not only is transport stress avoided, but also the health status of the recipient colony is not compromised. Embryos do not need to be shipped in frozen stage, which requires expensive packaging in addition to a certain degree of expertise in order to freeze and thaw them correctly. The aim of this study was to examine different storage conditions and their effect on embryo viability in order to establish the feasibility of practical, non-frozen conditions for embryo shipment. Methods Mouse morulae developed in vivo (collected from donors 2.5d post coitum) or in vitro (zygotes cultured until morulae stage) were stored, combining two different media (KSOMeq or KSOM-H) and temperatures (4 degrees C, 15 degrees C and 37 degrees C) throughout 24 or 48 hours. After storage in vitro viability was assessed determining percentage of development to blastocyst and total cell number. In vivo viability was determined based on the number of implantations and living fetuses after embryo transfer of stored embryos. The storage effect at the molecular level was assessed by studying a gene pool involved in early development by quantitative RT-PCR. Results In vivo-produced morulae stored for 24 hours did not show differences in development up to the blastocyst stage, regardless of the storage type. Even though a decrease in the total cell number in vivo was observed, embryo development after embryo transfer was not affected. All 24 hour storage conditions tested provided a similar number of implantations and fetuses at day 14 of pregnancy. Morulae obtained from in vitro embryo culture collected at the 1-cell stage showed a decreased ability to develop to blastocyst after 24 hours of storage at 15degrees C both in KSOMeq and KSOM-H. Concomitantly, a significant decrease of embryo implantation rates after transfer to recipients was also found. In order to further characterize the effect of non-frozen storage combining a molecular approach with the ordinary in vitro culture evaluation, embryos collected at the morula stage were submitted to the same storage conditions described throughout 48 hours. In vitro culture of those embryos showed a significant decrease in their developmental rate to blastocyst in both KSOMeq and KSOM-H at 15degrees C, which also affected the total number of cells. Gene transcription studies confirmed significant alterations in retrotransposons (Erv4 and Iap) after 48 h of storage at 15degrees C. Conclusions Our results show that both KSOMeq and KSOM-H can be equally used, and that several temperature conditions allow good survival rates in vitro and in vivo. Some of these storage conditions can substitute freezing in order to maintain embryo viability for 24–48 hours, providing a reliable and less demanding technical alternative for embryo interchanges.This work was performed as part of, and financed by, Project AGL2004-00332. JDH received a Ph D. grant from the INIA (Ministry of Science and Innovation). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its unit of Information Resources for Research (URICI).Peer Reviewe
Selection against spermatozoa with fragmented DNA after postovulatory mating depends on the type of damage
<p>Abstract</p> <p>Background</p> <p>Before ovulation, sperm-oviduct interaction mechanisms may act as checkpoint for the selection of fertilizing spermatozoa in mammals. Postovulatory mating does not allow the sperm to attach to the oviduct, and spermatozoa may only undergo some selection processes during the transport through the female reproductive tract and/or during the zona pellucida (ZP) binding/penetration.</p> <p>Methods</p> <p>We have induced DNA damage in spermatozoa by two treatments, (a) a scrotal heat treatment (42 degrees C, 30 min) and (b) irradiation with 137Cs gamma-rays (4 Gy, 1.25 Gy/min). The effects of the treatments were analyzed 21-25 days post heat stress or gamma-radiation. Postovulatory females mated either with treated or control males were sacrificed at Day 14 of pregnancy, and numbers of fetuses and resorptions were recorded.</p> <p>Results</p> <p>Both treatments decreased significantly implantation rates however, the proportion of fetuses/resorptions was only reduced in those females mated to males exposed to radiation, indicating a selection favoring fertilization of sperm with unfragmented DNA on the heat treatment group. To determine if DNA integrity is one of the keys of spermatozoa selection after postovulatory mating, we analyzed sperm DNA fragmentation by COMET assay in: a) sperm recovered from mouse epididymides; b) sperm recovered from three different regions of female uterine horns after mating; and c) sperm attached to the ZP after in vitro fertilization (IVF). Similar results were found for control and both treatments, COMET values decreased significantly during the transit from the uterine section close to the uterotubal junction to the oviduct, and in the spermatozoa attached to ZP. However, fertilization by IVF and intracytoplasmatic sperm injection (ICSI) showed that during sperm ZP-penetration, a stringent selection against fragmented-DNA sperm is carried out when the damage was induced by heat stress, but not when DNA fragmentation was induced by radiation.</p> <p>Conclusion</p> <p>Our results indicate that in postovulatory mating there is a preliminary general selection mechanism against spermatozoa with low motility and fragmented-DNA during the transport through the female reproductive tract and in the ZP binding, but the ability of the ZP to prevent fertilization by fragmented-DNA spermatozoa is achieved during sperm-ZP penetration, and depends on the source of damage.</p
América del Sur: Un imaginario construido por Disney. El caso de Saludos amigos (Ensayos)
This work explores the construction of imaginaries and representations about the countries of South America, from the cinematographic production of the United States, which later became widespread on television. The study is carried out on a historical moment and with a specific case that are the animated films Saludos amigos produced by Walt Disney in 1942, at the request and financing of the US government, as part of a strategy of consolidation of its world political power. Saludos amigos creates an imaginary of folklore, party, geographical dangers and economic health for investment in the continent. In short, the idea of “friendly neighbors” was projected to visit, do business and as allies against external threats. The commercial and political success of the production made it possible to consolidate a relationship of domination in the cultural industry and in political relations between the United States and South America. Hence, the following research questions were worked on: What is the historical importance of the contents in cinema, which later became widespread on television, for the construction of the imaginary of South America, since the Disney production Saludos Amigos? and What is the geopolitical construction from the cultural logic of the Good Neighbor Policy?Este trabajo explora la construcción de imaginarios y representaciones sobre los países de América del Sur desde la producción cinematográfica de los Estados Unidos, que luego se masificó en la televisión. El estudio se realiza sobre un momento histórico y con un caso específico: los filmes animados Saludos amigos, producidos por Walt Disney en 1942, bajo pedido y financiamiento del Gobierno estadounidense, como parte de una estrategia de consolidación de su poder político mundial. Saludos amigos crea un imaginario de folclore, fiesta, peligros geográficos y salud económica para la inversión en el continente. En definitiva, se proyectó la idea de unos “vecinos amistosos” a los que visitar, con los que hacer negocios y a los que tener como aliados frente a amenazas externas. El éxito comercial y político de la producción permitió consolidar la dominación estadounidense sobre América del Sur en la industria cultural y en las relaciones políticas. Se trabajó con las siguientes preguntas de investigación: ¿cuál es la importancia histórica de los contenidos cinematográficos, que luego se masificaron con la televisión, para la construcción del imaginario de América del Sur desde la producción de Disney Saludos amigos?, y ¿cuál es la construcción geopolítica desde la lógica cultural de la Política de Buena Vecindad
Efecto del flushing energético sobre la población folicular, el número de cuerpos lúteos y calidad ovocitaria en cobayas primerizas
El objetivo de esta investigación fue evaluar el efecto del flushing energético administrado a
cobayas primerizas sobre la población folicular, número de cuerpos lúteos y calidad
ovocitaria. Se utilizaron 64 cobayas primerizas de la línea Perú que fueron distribuidos
aleatoriamente en 4 tratamientos dietéticos con diferentes niveles de energía, T0 (2400
Kcal/kg de MS), T1 (2600 kcal/kg de MS), T2 (2800 kcal/kg de MS) y T3 (3000 kcal/kg de
MS). Las cobayas fueron alimentadas durante 11 días con mezcla forrajera de trébol rojo más
rye-grass y sobrealimento de harina de maíz, afrecho de trigo y melaza. Todos los animales
fueron sometidos a sincronización de celo mediante la aplicación de PGF2α. Al finalizar el
experimento, se sacrificaron a las cobayas y se extrajeron los ovarios. Los COC´s fueron
recuperados mediante el método de slicing y categorizados en tres tipos y para el conteo de
folículos y cuerpos lúteos se realizaron cortes histológicos. No se encontraron diferencias
significativas en el número total de folículos, clasificación folicular ni en el número de cuerpos
lúteos. Sin embargo, el número total de ovocitos recuperados, la cantidad de ovocitos de
categoría A y B fueron (p < 0,05) significativamente mayor en las cobayas del T3 (222
ovocitos), a diferencia de los demás tratamientos. Además, se observó un incremento en el
porcentaje de ovocitos aptos en el T3. En conclusión, aumentar el nivel de energía en la dieta,
no influyó sobre la población folicular ni en el número de cuerpos lúteos, pero sí sobre el
número y calidad de ovocitos.The aim of this research was to evaluate the effect of energy flushing administered in
primiparous guinea pigs on the follicular population, number of corpora lutea and oocyte
quality. Sixty-four primiparous guinea pigs from the Peru line were used and were randomly
distributed in 4 dietary treatments with different energy levels, T0 (2400 Kcal/kg of DM), T1
(2600 kcal/kg of DM), T2 (2800 kcal/kg of DM). DM) and T3 (3000 kcal/kg DM). The guinea
pigs were fed for 11 days with a forage mixture of red clover plus rye-grass and supplemental
feed of corn flour, wheat bran and molasses. All animals were subjected to estrous
synchronization by applying PGF2α. At the end of the experiment, the guinea pigs were
sacrificed and the ovaries were removed. The COCs were recovered using the slicing method
and categorized into three types and histological sections were made to count follicles and
corpora lutea. No significant differences were found in the total number of follicles, follicular
classification or in the number of corpora lutea. However, the total number of oocytes
recovered, the number of category A and B oocytes were (p<0.05) significantly higher in the
T3 guinea pigs (222 oocytes), unlike the other treatments. Furthermore, an increase in the
percentage of suitable oocytes was observed in T3. In conclusion, increasing the energy level
in the diet did not influence the follicular population or the number of corpora lutea, but it did
influence the number and quality of oocytes.0000-0003-2766-702
A Multi-agent System that Searches for Learning Objects in Heterogeneous Repositories
This paper presents the BRENHET application, which introduces a new concept in searching for educational resources by using a learning object paradigm that describes these resources. The application is composed of a complete agent-based architecture that implements the concept of federated search. It can search different repositories in parallel, and is based on abstraction layers between the repositories and the search clients
Uso de Herramientas en Línea en la Enseñanza de Inglés como Lengua Extranjera
Reaching the mastery of a foreign language is vital in this globalized world; therefore, the aim of this study is to provide important data that can help teachers choose the most productive online tools to help their students learn English using technology in a dynamic manner. This article presents a literature review that utilizes a qualitative method about the use of online tools for the EFL classroom. To locate the publications that met the researcher's criteria, a search of articles was conducted in the Google Scholar database, with an emphasis on the abstract, results, and conclusions. One of the biggest benefits of using Internet resources for teaching and studying English is their flexibility. The analysis of online resources reveals that they have contributed to the development of supportive and competitive environments that have improved speaking abilities, pronunciation, and fluency. They have also helped people find ideas for sentences more quickly when speaking, increase motivation, encourage peer learning, broaden their vocabulary knowledge through reading, engage in conversation, and lessen their fear. Besides, they demonstrate that using the tools effectively has presented some barriers for students, but practice and instruction have helped them get past these obstacles and achieve learning.Dominar una lengua extranjera es vital en este mundo globalizado; por lo tanto, el objetivo de este estudio es proporcionar información importante para ayudar a los profesores a elegir las herramientas en línea más productivas para que sus estudiantes aprendan inglés utilizando la tecnología de manera dinámica. Este artículo presenta una revisión de la literatura que utiliza un método cualitativo sobre el uso de herramientas en línea para el aula de inglés como lengua extranjera. Para localizar las publicaciones que cumplieron con los criterios del investigador, se realizó una búsqueda de artículos en la base de datos Google Scholar, con énfasis en el resumen, resultados y conclusiones. Uno de los mayores beneficios de utilizar recursos de Internet para enseñar y estudiar inglés es su flexibilidad. El análisis de estos recursos en línea revela que han contribuido al desarrollo de entornos competitivos y de apoyo que han mejorado las habilidades para hablar, la pronunciación y la fluidez. También han ayudado a crear oraciones más rápidamente al hablar, aumentar la motivación, fomentar el aprendizaje entre pares, ampliar el conocimiento de vocabulario mediante la lectura, entablar conversaciones y disminuir su miedo. Además, demuestran que su uso ha presentado algunas barreras para los estudiantes, pero la práctica les ha ayudado a superar estos obstáculos y lograr el aprendizaje
Bovine Spongiform Encephalopathy Induces Misfolding of Alleged Prion-Resistant Species Cellular Prion Protein without Altering Its Pathobiological Features
Bovine spongiform encephalopathy (BSE) prions were responsible for an unforeseen epizootic in cattle which had a vast social, economic, and public health impact. This was primarily because BSE prions were found to be transmissible to humans. Other species were also susceptible to BSE either by natural infection (e.g., felids, caprids) or in experimental settings (e.g., sheep, mice). However, certain species closely related to humans, such as canids and leporids, were apparently resistant to BSE. In vitro prion amplification techniques (saPMCA) were used to successfully misfold the cellular prion protein (PrPc) of these allegedly resistant species into a BSE-type prion protein. The biochemical and biological properties of the new prions generated in vitro after seeding rabbit and dog brain homogenates with classical BSE were studied. Pathobiological features of the resultant prion strains were determined after their inoculation into transgenic mice expressing bovine andhumanPrPC. Strain characteristics of the in vitro-adapted rabbit and dog BSE agent remained invariable with respect to the original cattle BSE prion, suggesting that the naturally low susceptibility of rabbits and dogs to prion infections should not alter their zoonotic potential if these animals became infected with BSE. This study provides a sound basis for risk assessment regarding prion diseases in purportedly resistant species
Hybrid Multiagent System for Automatic Object Learning Classification
The rapid evolution within the context of e-learning is closely linked to international efforts on the standardization of learning object metadata, which provides learners in a web-based educational system with ubiquitous access to multiple distributed repositories. This article presents a hybrid agent-based architecture that enables the recovery of learning objects tagged in Learning Object Metadata (LOM) and provides individualized help with selecting learning materials to make the most suitable choice among many alternatives
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