766 resultados para Positive Behavior Support
Resumo:
La Educación Física se muestra, a priori, como un área idónea para trabajar intervenciones educativas para facilitar la inclusión de alumnos con discapacidad. Sin embargo, poco se conoce sobre el potencial que presentan los deportes adaptados y paralímpicos como contenido para fomentar la sensibilización y concienciación del alumnado sin discapacidad, especialmente en situaciones inclusivas de práctica. Por otro lado, la actitud del docente y su formación se presentan como claves en este contexto, ya que es quien en última instancia selecciona los contenidos a trabajar. Entendemos que en EF disponemos de una ocasión única en el curriculum para fomentar la participación activa y efectiva del alumno con discapacidad en clase (especialmente a nivel de desarrollo de la competencia motriz, entre otras), si bien esto depende de factores relacionados con los dos agentes anteriores. Es por todo ello que la Educación Física, como protagonista y como contenido, se muestra como un contexto adecuado para la investigación de los procesos de inclusión de alumnos con discapacidad en el ámbito educativo. Este trabajo de investigación pretende arrojar luz a los interrogantes que condicionan y limitan este contexto, desde una perspectiva multidisciplinar, con distintas metodologías, sobre los tres agentes indicados. La falta de consenso en la literatura en cuanto a las características y tipo de intervenciones eficaces para facilitar esta sensibilización del alumnado, unido a que es un ámbito relativamente reciente como tema de investigación, nos ha impulsado a trabajar en esta línea. El primer objetivo de este trabajo de investigación fue diseñar e implementar un programa de sensibilización y concienciación hacia la discapacidad basado en los deportes adaptados en el área de Educación Física para alumnos de secundaria y bachillerato. Inicialmente, se realizó una búsqueda bibliográfica tanto a nivel nacional como internacional, con el fin de definir las características principales que aporta la literatura científica en este aspecto. Apoyándonos por un lado, en el programa educativo Paralympic School Day (CPI, 2004) y por otro, en la citada revisión, desarrollamos un planteamiento inicial de estructura y fases. Dicho proyecto, fue presentado al Comité Paralímpico Español y a las federaciones deportivas españolas para personas con discapacidad, con la finalidad de recabar su apoyo institucional en forma de aval y recursos no solo a nivel económico sino también como apoyo logístico y de difusión. Tras su aprobación y gracias también al apoyo de la UPM, la Fundación Sanitas y Liberty Seguros, se procedió a diseñar el programa. Para el desarrollo de los materiales didácticos se contactó con expertos en la materia de EF y Actividad Física Adaptada tanto del ámbito educativo (profesores de educación secundaria y profesorado universitario) como del deportivo a nivel nacional. A su vez, se comenzó a difundir entre el profesorado de los centros con el fin de detectar su interés en participar durante el curso académico (2012-2013) en el programa “Deporte Inclusivo en la Escuela”. Con la finalización del desarrollo de los materiales didácticos, se visitó a los centros educativos para presentar el dossier informativo donde se explicaba el programa, así como las características y fases para su implementación. El programa está fundamentado en la Teoría del Contacto (Allport, 1954) y basado en los deportes adaptados y paralímpicos, planteado con una metodología inclusiva, seleccionando la información, la simulación y el contacto directo como estrategias para el fomento de la sensibilización y concienciación hacia la inclusión. En la reunión celebrada en la Facultad de Ciencias de la Actividad Física y del Deporte (INEF-UPM) en febrero de 2013, se coordinó junto con el profesorado la implementación del programa en cada uno de los 13 centros educativos, con acciones concretas como la adecuación de la propuesta didáctica en la planificación anual del profesor, el préstamo de material o la ponencia del deportista paralímpico entre otras cuestiones. Para la consecución del objetivo 2 de este trabajo, analizar el efecto del programa en los distintos agentes implicados en el mismo, alumnos sin discapacidad, profesorado de EF y alumnos con discapacidad, se calendarizó la toma de datos y la administración de las diferentes herramientas metodológicas para antes (pretest) como después de la intervención (posttets). En el caso de los alumnos sin discapacidad (N= 1068), se analizó el efecto de la intervención sobre la actitud hacia la inclusión, utilizando el cuestionario “Children Attitude Integrated Physical Education-Revised” (CAIPE-R; Block, 1995) de carácter cuantitativo tras su validación y adaptación al contexto español. Los resultados mostraron cambios significativos positivos en la actitud el grupo que mantuvo un contacto no estructurado con alumnos con discapacidad. En esta muestra también se midió la actitud hacia el juego cooperativo con compañeros con discapacidad en clases de EF usando el cuestionario “Children's Beliefs Toward Cooperative Playing With Peers With Disabilities in Physical Education” (CBIPPD-MPE; Obrusnikova, Block, y Dillon, 2010). El desarrollo de un sistema de categorías fundamentado en la Teoría del Comportamiento Planificado (Azjen, 1991) sirvió como base para el análisis de las creencias del alumnado sin discapacidad. Tras la intervención, las creencias conductuales emergentes se mantuvieron, excepto en el caso de los factores identificados como obstáculos de la inclusión. En el caso de las creencias normativas también se mantuvieron tras la intervención y respecto a las creencias de control, los alumnos identificaron al profesor como principal agente facilitador de la inclusión. En el caso de los profesores de EF participantes en el programa (N=18), se analizó el efecto del programa en su actitud hacia la inclusión de alumnos con discapacidad en EF con el cuestionario “Attitud toward inclusion of individual with physical disabilities in Physical Education” (ATISDPE-R; Kudláèek, Válková, Sherrill, Myers, y French, 2002). Los resultados mostraron que no se produjeron diferencias significativas tras la intervención en la actitud general, encontrando algunas diferencias en determinados ítems relacionados con los beneficios de la inclusión en los alumnos sin discapacidad relacionados con los docentes con experiencia previa con discapacidad y en EF antes de la intervención. La otra dimensión analizada fue el efecto de la intervención en la autoeficacia del profesor en la enseñanza de la EF en condiciones inclusivas, habiendo utilizado el cuestionario "Self-efficacy in teaching PE under inclusive conditions" (SEIPE; Hutzler, Zach, y Gafni, 2005). Los resultados en este caso muestran diferencias significativas positivas en cuestiones relacionadas como sentirse capaces de mejorar las condiciones óptimas de enseñanza con alumnos con discapacidad física como movilidad reducida severa y amputación y discapacidad visual tanto en situaciones deportivas, como juegos o actividades fuera del centro educativo a favor de los docentes. En cuanto al género, los hombres obtuvieron valores superiores a las mujeres en relación a sentirse más capaces de incluir a alumnos con discapacidad física tanto en juegos durante el recreo como en la enseñanza de técnica deportiva. Los profesores con menos de 10 años de docencia mostraron valores más positivos en cuanto a sentirse capaces de incluir a un alumno con discapacidad fisica en deportes durante su tiempo libre. El análisis del diario del profesor muestra por un lado, las tendencias emergentes como principales elementos facilitadores u obstaculizadores de la inclusión en EF, identificando al propio alumno sin discapacidad, el propio profesor, los contenidos, los materiales y la organización. Por otro lado, el análisis de los contenidos propuestos en el programa. En el caso de los alumnos con discapacidad (N=22), se analizó el impacto del programa de intervención en el autoconcepto, con el cuestionario "Autoconcepto forma 5" (AF5; F. García y Musitu, 2001). Se encontraron diferencias significativas a favor de las mujeres antes de la intervención en la dimensión familiar, mientras que los hombres obtuvieron valores más altos en las dimensiones social y físico. En cuanto a la edad, se encontraron diferencias significativas antes de la intervención, con valores superiores en los alumnos más jóvenes (12-14 años) en la dimensión físico, mientras que los alumnos mayores (15-17 años) mostraron valores más altos en la dimensión social del cuestionario. Respeto al tipo de discapacidad, los alumnos con discapacidad motórica mostraron mejores valores que los que tienen discapacidad auditiva para la dimensión físico antes de la intervención. En cuanto al autoconcepto general, las diferencias significativas positivas se producen en la dimensión académica. En cuanto al efecto del programa en la autoestima de los alumnos con discapacidad, se utilizó la Escala de "Autoestima de Rosenberg" (Rosenberg, 1989), no obteniendo diferencias significativas en cuanto el género. Apareciendo diferencias significativas antes de la intervención en el caso de la variable edad en los alumnos más jóvenes, en cuanto a que desearían valorarse más, y en los alumnos con discapacidad auditiva en que no se sienten muy orgullosos de ellos mismos. Se produce una mejora en la autoestima general en cuanto a que se sienten menos inútiles tras la intervención. En relación al objetivo 3 de este trabajo, tras el análisis de los resultados y haber discutido los mismos con los autores de referencia, emergió la propuesta de orientaciones tanto para los programa de intervención en EF para la sensibilización y concienciación del alumnado hacia la inclusión como de cara a la formación específica del profesorado, como clave en este tipo de intervenciones. Creemos que el programa “Deporte Inclusivo Escuela” se convierte en un elemento transformador de la realidad, ya que responde a las necesidades detectadas a la luz de esta investigación y que vienen a dar respuesta a los distintos agentes implicados en su desarrollo. Por un lado, atiende la demanda del ámbito educativo en cuanto a las necesidades de formación del profesorado, sensibilización y concienciación del alumnado sin discapacidad, además de facilitar oportunidades de participación activa al alumno con discapacidad en las sesiones de EF. Por otro lado, satisface la demanda por parte de las instituciones deportivas del ámbito de la discapacidad en cuanto a la promoción y difusión de los deportes adaptados y paralímpicos. Por último, desde el ámbito universitario, se muestra como un recurso en la formación del alumnado del grado en Ciencias de la Actividad Física y del Deporte, por su participación directa con la discapacidad. Por estos motivos, este trabajo se muestra como un punto de partida adecuado para seguir avanzando en la investigación en esta área. ABSTRACT Physical Education (PE) seems a priori, as a suitable area to work educational interventions to facilitate the inclusion of students with disabilities. However, little is known about the potential that have adapted and Paralympic sports as content to raise awareness of students without disabilities, especially in inclusive practice context. On the other hand, teachers’ attitude and their training are presented as key in this context because it is who selects the content to work. We understand that PE have a unique opportunity in the curriculum to encourage active and effective participation of students with disabilities in class (especially at motor competence development, etc.), although this depends on factors related to the two agents. For these reasons that the PE, as actors and as content is displayed as a context for investigating the processes of inclusion of students with disabilities in education. This research aims to shed light on the questions that condition and limit this context, from a multidisciplinary perspective, with different methodologies on the three agents mentioned. The lack of accord in the literature regarding the characteristics and type of effective facilitators of awareness of students, and that is a new area as a research topic, has prompted us to work in this topic research. The first aim of this research was to design and implement a program of awareness towards disability based on adapted sports in the area of physical education for middle and high school students. Initially, a literature search was performed both nationally and internationally, in order to define the main features that brings the scientific literature in this area. On the one hand, we supported in the Paralympic School Day (IPC, 2004) educative program and on the other hand, in that review, we developed an initial approach to structure and phases. The project was presented to the Spanish Paralympic Committee and the Spanish Sports Federations for people with disabilities, in order to obtain institutional support in the form of guarantees and resources not only in economic terms but also as logistical support and dissemination. Thanks to the support of Fundación Sanitas, Liberty Seguros and Politechnical University of Madrid, we proceeded to design the program. For the development of teaching resources it was contacted experts in the field of Adapted Physical Activity and physical education and both the field of education (high school teachers and university professors) as the adapted sport national. In turn, it began to spread among the teachers of the schools in order to identify their interest in participating in the academic year (2012-2013) in the "Inclusive Sport in School" program. With the completion of the development of educational materials to schools he was visited to present the briefing where the program, as well as features and steps for its implementation are explained. The program is based on the Contact Theory (Allport, 1954) and based on adapted and Paralympic sports, raised with an inclusive approach, selecting strategies for promoting awareness and awareness to inclusion like information, contact and simulation of disability. At the meeting held at the Faculty of Sciences of Physical Activity and Sport (INEF-UPM) in February 2013, it was coordinated with the teachers implementing the program in each of the 13 schools with concrete actions such as adequacy of methodological approach in the annual planning of the teacher, the loan or the presentation of materials Paralympian among other issues. To achieve the objective 2 of this paper, to analyze the effect of the program on the various actions involved it, students without disabilities, PE teachers and students with disabilities, the date for management of the different methodological tools for before (pretest) and after the intervention (posttets). For students without disabilities (N= 1068), the effect of the intervention on the attitude towards inclusion was analyzed, using the quantitative questionnaire "Integrated Physical Education Attitude Children-Revised" (CAIPE-R; Block, 1995), after validation and adaptation to the Spanish context. The results showed significant positive changes in the attitude of the group with no structured contact with students with disabilities. This shows the beliefs towards the cooperative play was with peers with disabilities in PE classes also measured, using the questionnaire "Children's Beliefs Toward Cooperative Playing With Peers With Disabilities in Physical Education" (CBIPPD-MPE; Obrusnikova, Block, and Dillon, 2010). The development of a system of categories based on the Theory of Planned Behavior (Azjen, 1991) served as the basis for analysis of the beliefs of students without disabilities. After surgery, emerging behavioral beliefs remained, except in the case of the factors identified as barriers to inclusion. In the case of normative beliefs also they remained after surgery and regarding control beliefs, students identified the teacher as the main facilitator of inclusion. Regarding PE teachers participating in the program (N = 18), the effect of the program was analyzed their attitude toward inclusion of students with disability in PE with the questionnaire "Toward Attitude inclusion of Individual with in Physical Education "(ATISDPE-R; Kudláèek, Válková, Sherrill, Myers, and French, 2002). The results showed no significant difference occurred after surgery in the general attitude, finding some differences in certain related benefits of inclusion in students without disability relating to teachers with previous experience with disability in PE before intervention. The other dimension was analyzed the effect of the intervention on self-efficacy of teachers in the teaching of PE in inclusive terms, having used the questionnaire "Self-efficacy in PE teaching even under conditions" (SEIPE; Hutzler, Zach, and Gafni, 2005). The results showed significant differences positive in issues like being able to enhance the optimal conditions for teaching students with physical disabilities as amputation and severe visual impairment in both sports situations, such as games or activities outside the school to for teachers. Regard to gender, men earned higher values regarding women about feel more able to include students with physical disabilities in both games during recess and teaching sports technique. Teachers with less than 10 years of teaching showed more positive values as you feel able to include a student with physical disabilities in sports during their leisure time. The analysis of daily teacher shows on the one hand, emerging trends as key facilitators or barrier of the inclusion elements in PE, identifying the students without disabilities themselves, the professor, contents, materials and organization. Furthermore, the analysis of daily teacher about the contents proposed in the program. In the case of students with disabilities (N=22), the impact of the intervention program on self-concept was analyzed, with the questionnaire "Self-concept form 5" (AF5, F. Garcia and Musitu, 2001). The women showed significant differences before the intervention in family dimension, while men scored higher values in the social and physical dimensions were found. In terms of age, significant differences were found before the intervention, with higher values in younger students (12-14 years) in the physical dimension, while older children (15-17 years) showed higher values the social dimension of the questionnaire. Respect disabilities, students with motor disabilities showed better values than those with hearing impairment to the physical dimension before surgery. As for the general self-concept, positive significant differences occur in the academic dimension. As for the effect of the program on self-esteem of students with disabilities Scale "Rosenberg Self-Esteem" (Rosenberg, 1989) was used, not getting significant differences in gender. Only appear significant difference before the intervention in the case of younger students as they wish to be valued more, and students with hearing disabilities who do not feel very proud of themselves. Improved self-esteem generally occurs in that they feel less useless after surgery. With regard to the aim 3 of this research, after analyzing the results and have discussed them with the authors, it emerged the proposal of guidelines for both intervention program EF for sensitization and awareness of students towards inclusion as in the face of specific training for teachers, as key in such interventions. We believe that "Inclusive Sport Schools" program becomes a transforming element of reality, as it responds to the needs identified in the light of this research and come to respond to the various elements involved in its development. On the one hand, it meets the demand of the education sector in terms of the needs of teacher training, awareness of students without disability, and facilitates opportunities for students with disabilities for active participation in PE class. On the other hand, it meets the demand of sports institutions in the field of disability regarding the promotion and dissemination of adapted and Paralympic sports. Finally, it is shown as a resource from the university level for the training of degree in Physical Activity and Sport Science students, by its direct involvement with disability. For these reasons, this work is shown as a good starting point to further advance research in this area.
Resumo:
Esta tesis presenta un estudio de la resistencia de interferencia en multicascos, término que engloba las variaciones en la resistencia al avance debidas a la interacción entre cascos. Su característica más notable es que puede ser tanto positiva como negativa, contribuyendo favorablemente en este último caso a la reducción de la resistencia total. Su análisis permanece como un área activa dentro de la comunidad hidrodinámica, si bien se ha detectado una significativa falta de información experimental sobre el flujo entre cascos. En primer lugar se incluye una caracterización de los fenómenos de interferencia, evaluando su impacto en las diferentes componentes de la resistencia al avance. Al igual que la resistencia total, su predicción requiere el uso de técnicas experimentales o numéricas al ser inviable su solución analítica. Ambos procedimientos han sido considerados en esta tesis. El análisis experimental de la resistencia de interferencia supone el núcleo central del trabajo realizado. Se han ensayado dos geometrías diferentes, un catamarán de servicio comercial PESBO junto con un catamarán compuesto por dos Serie 60 (S60) en paralelo. Los ensayos se han llevado a cabo en dos canales de experiencias, CEHINAV y CEHIPAR, midiéndose resistencia al avance, asiento y trimados dinámicos, y cortes de olas en la zona entre cascos. Mención especial a estos últimos, dado que a pesar de ser en la zona central donde ocurren los principales efectos de interferencia, no se encontró información previa publicada en la literatura. Su medición requirió la fabricación de un sistema de soporte especifico para las probetas de medición. Por otro lado, aunque el Serie 60 es una geometría bien conocida en la comunidad hidrodinámica, a conocimiento del autor su comportamiento como multicasco no había sido aun caracterizado experimentalmente. Los bastidores de unión se fabricaron de forma que permitieran variar la separación entre cascos. Además, los multicascos son en general embarcaciones de alta velocidad mostrando asientos y trimados dinámicos significativos. Para cuantificar su efecto en la resistencia total y de interferencia se construyo un sistema de fijación del modelo al carro que los restringiera, posibilitando comparar los resultados en esta condición con los del modelo libre. Como resultado, se han obtenido resultados experimentales de las dos geometrías estudiadas con múltiples separaciones, incluyendo un solo casco, y con modelo fijo y libre. Una de las principales utilidades de los resultados experimentales es servir como referencia para validar modelos de predicción. Como primera aplicación, los datos experimentales obtenidos con el catamarán S60 se han contrastado con las predicciones numéricas de Yeung et al. (2004). El análisis numérico de la resistencia de interferencia se completa con la realización de simulaciones numéricas utilizando dos códigos substancialmente diferentes: Tdynlin y CD--‐Adapco Star--‐CCM+. Los cortes de olas obtenidos en las simulaciones se comparan con los valores experimentales, mostrándose además los campos de presiones y velocidades calculados sobre el casco. La principal aportación de esta tesis es una extensa caracterización experimental de los fenómenos de interferencia, con la intención de servir de referencia para futuros estudios con multicascos. El análisis de los resultados permite comprender mejor el impacto que la interacción entre cascos, así como las variaciones dinámicas de las condiciones de navegación, tienen en las diferentes componentes de la resistencia. Por otro lado, permite apreciar la dependencia de la resistencia de interferencia con la velocidad y separación entre cascos, de cara a su utilización como parámetro de diseño. ABSTRACT This thesis presents a study of the interference resistance in multihulls, which comprises all the variations in the ship resistance due to the interaction between hulls. Its most remarkable characteristic is that it can be positive or negative, contributing in the second case to the reduction of the total ship resistance. Its study remains an active area in the hydrodynamic community, although there is a significant lack of published experimental data regarding the flow between hulls. First of all, the interference phenomena are characterized, evaluating the impact in the different components of the ship resistance. Similar to the total resistance, their prediction requires experimental or numerical techniques, as no analytic solutions are known. Both procedures have been considered in this thesis. The experimental analysis of the interference resistance is the core of the work done. Two different geometries have been tested, a commercial catamaran PESBO and a catamaran composed by two parallel Series 60 (S60). The tests have been carried out in two towing tanks, CEHINAV and CEHIPAR, measuring ship resistance, dynamic sinkage and trim, and wave cuts in--‐between the hulls. Special mention to the wave cuts, as no previous published information was found regarding this zone, even if it is where the main interference effects happen. Their measurement required building a support tripod for the probes, specifically designed for this experimental campaign. In addition, although the Series 60 is a well known hull for experimental and computational analyses, to the author’s knowledge its behavior as a multihull had not yet been experimentally described. The connection frames between the hulls were built so they allowed adjusting the hull spacing. Furthermore, multihulls are usually high--‐speed vessels, acquiring significant dynamic sinkage and trim. To quantify the effect of these dynamic variations of the interference resistance, a clamping system was developed to fixed the model and compare the results with the free model condition. Thus, experimental results have been obtained for various hull separations with the two geometries analyzed, including a single hull, and with free and fixed model. One of the main applications of experimental results is to serve as a reference to validate prediction models. As a first step, the obtained experimental data with the catamaran S60 have been compared with the numerical predictions of Yeung et al. (2004). The numerical analysis of the interference resistance is completed with the inclusion of numerical simulations using two codes substantially different: Tdynlin and CD--‐Adapco Star--‐CCM+. The wave cuts obtained from the simulations are compared with the experimental ones, showing also the pressure and velocity fields over the hulls. The main contribution of this thesis is an extensive experimental characterization of the interference phenomena, aiming to serve as reference for future studies about multihulls. The analysis of the results provides insights into the impact that the interaction between hulls, as well as the dynamic variations of the sailing conditions, have in the different components of the ship resistance. Moreover, it allows us to observe the dependence of the interference resistance on the velocity and hull spacing, useful towards its use as a design parameter.
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Innovation is a process that faces several market failure situations. For this reason and for being considered one of the main drivers of economic growth, a large number of governmental and supranational policies are designed to foster technological progress. Along with these policies, there is an increasing concern with their continuous evaluation aiming at providing valuable feedback for these program?s adaptation and adequacy to the firm?s needs. The paper develops an evaluation of the influence of innovation-focused programs in firm¿s innovation and economic performance by means of a comparative analysis of the results obtained by Spanish firms that have participated in R&D national programmes and those achieved by Spanish firms participating in EUREKA international program. Findings show that the programmes were effective in achieving their objective of promoting technological innovation but, as regards the economic effects, the results were less conclusive since some differences were observed depending on the programme. The EUREKA companies displayed better behaviour, with positive differences in their returns on assets and labour productivity. The results also confirm the importance of designing more detailed and rigorous evaluation processes, taking into account the risk variable, in order to draw a more realistic picture of the impact of national and international programmes.
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Interaction of the αβ T cell receptor (TCR) with major histocompatibility (MHC) molecules occupied with any of a large collection of peptides derived from self proteins is a critical step in driving T cell “positive” selection in the thymus. Interaction with this same pool of self-peptide/MHC ligands deletes T cells with potential self-reactivity. To examine how T cells survive both of these processes to form a self-tolerant mature repertoire, mice were constructed whose entire class II MHC IEk specific repertoire was positively selected on a single peptide covalently attached to the IEk molecule. In these mice T cells were identified that could respond to a variant of the positively selecting peptide bound to IEk. The affinities of the TCRs from these T cells for the positively selecting ligand were extremely low and at least 10-fold less than those for the activating ligand. These results support the theory that positive selection is driven by TCR affinities lower than those involved in T cell deletion or activation and that, if present at high concentration, even very low affinity ligands can positively select.
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We investigated the defensive behavior of honeybees under controlled experimental conditions. During an attack on two identical targets, the spatial distribution of stings varied as a function of the total number of stings, evincing the classic “pitchfork bifurcation” phenomenon of nonlinear dynamics. The experimental results support a model of defensive behavior based on a self-organizing mechanism. The model helps to explain several of the characteristic features of the honeybee defensive response: (i) the ability of the colony to localize and focus its attack, (ii) the strong variability between different hives in the intensity of attack, as well as (iii) the variability observed within the same hive, and (iv) the ability of the colony to amplify small differences between the targets.
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LINEs are transposable elements, widely distributed among eukaryotes, that move via reverse transcription of an RNA intermediate. Mammalian LINEs have two ORFs (ORF1 and ORF2). The proteins encoded by these ORFs play important roles in the retrotransposition process. Although the predicted amino acid sequence of ORF1 is not closely related to any known proteins, it is highly basic; thus, it has long been hypothesized that ORF1 protein functions to bind LINE-1 (L1) RNA during retrotransposition. Cofractionation of ORF1 protein and L1 RNA in extracts from both mouse and human embryonal carcinoma cells indicated that ORF1 protein binds L1 RNA, forming a ribonucleoprotein particle. Based on UV crosslinking and electrophoretic mobility-shift assays using purified components, we demonstrate here that the ORF1 protein encoded by mouse L1 binds nucleic acids with a strong preference for RNA and other single-stranded nucleic acids. Furthermore, multiple copies of ORF1 protein appear to bind single-stranded nucleic acid in a manner suggesting positive cooperativity; such binding characteristics are likely to be facilitated by the protein–protein interactions detected among molecules of ORF1 polypeptide by coimmunoprecipitation. These observations are consistent with the formation of ribonucleoprotein particles containing L1 RNA and ORF1 protein and provide additional evidence for the role of ORF1 protein during retrotransposition of L1.
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Cancer is a progressive disease culminating in acquisition of metastatic potential by a subset of evolving tumor cells. Generation of an adequate blood supply in tumors by production of new blood vessels, angiogenesis, is a defining element in this process. Although extensively investigated, the precise molecular events underlying tumor development, cancer progression, and angiogenesis remain unclear. Subtraction hybridization identified a genetic element, progression elevated gene-3 (PEG-3), whose expression directly correlates with cancer progression and acquisition of oncogenic potential by transformed rodent cells. We presently demonstrate that forced expression of PEG-3 in tumorigenic rodent cells, and in human cancer cells, increases their oncogenic potential in nude mice as reflected by a shorter tumor latency time and the production of larger tumors with increased vascularization. Moreover, inhibiting endogenous PEG-3 expression in progressed rodent cancer cells by stable expression of an antisense expression vector extinguishes the progressed cancer phenotype. Cancer aggressiveness of PEG-3 expressing rodent cells correlates directly with increased RNA transcription, elevated mRNA levels, and augmented secretion of vascular endothelial growth factor (VEGF). Furthermore, transient ectopic expression of PEG-3 transcriptionally activates VEGF in transformed rodent and human cancer cells. Taken together these data demonstrate that PEG-3 is a positive regulator of cancer aggressiveness, a process regulated by augmented VEGF production. These studies also support an association between expression of a single nontransforming cancer progression-inducing gene, PEG-3, and the processes of cancer aggressiveness and angiogenesis. In these contexts, PEG-3 may represent an important target molecule for developing cancer therapeutics and inhibitors of angiogenesis.
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The high vocal center (HVC) controls song production in songbirds and sends a projection to the robust nucleus of the archistriatum (RA) of the descending vocal pathway. HVC receives new neurons in adulthood. Most of the new neurons project to RA and replace other neurons of the same kind. We show here that singing enhances mRNA and protein expression of brain-derived neurotrophic factor (BDNF) in the HVC of adult male canaries, Serinus canaria. The increased BDNF expression is proportional to the number of songs produced per unit time. Singing-induced BDNF expression in HVC occurs mainly in the RA-projecting neurons. Neuronal survival was compared among birds that did or did not sing during days 31–38 after BrdUrd injection. Survival of new HVC neurons is greater in the singing birds than in the nonsinging birds. A positive causal link between pathway use, neurotrophin expression, and new neuron survival may be common among systems that recruit new neurons in adulthood.
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Insects in the order Plecoptera (stoneflies) use a form of two-dimensional aerodynamic locomotion called surface skimming to move across water surfaces. Because their weight is supported by water, skimmers can achieve effective aerodynamic locomotion even with small wings and weak flight muscles. These mechanical features stimulated the hypothesis that surface skimming may have been an intermediate stage in the evolution of insect flight, which has perhaps been retained in certain modern stoneflies. Here we present a phylogeny of Plecoptera based on nucleotide sequence data from the small subunit rRNA (18S) gene. By mapping locomotor behavior and wing structural data onto the phylogeny, we distinguish between the competing hypotheses that skimming is a retained ancestral trait or, alternatively, a relatively recent loss of flight. Our results show that basal stoneflies are surface skimmers, and that various forms of surface skimming are distributed widely across the plecopteran phylogeny. Stonefly wings show evolutionary trends in the number of cross veins and the thickness of the cuticle of the longitudinal veins that are consistent with elaboration and diversification of flight-related traits. These data support the hypothesis that the first stoneflies were surface skimmers, and that wing structures important for aerial flight have become elaborated and more diverse during the radiation of modern stoneflies.
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Postmitotic hair-cell regeneration in the inner ear of birds provides an opportunity to study the effect of renewed auditory input on auditory perception, vocal production, and vocal learning in a vertebrate. We used behavioral conditioning to test both perception and vocal production in a small Australian parrot, the budgerigar. Results show that both auditory perception and vocal production are disrupted when hair cells are damaged or lost but that these behaviors return to near normal over time. Precision in vocal production completely recovers well before recovery of full auditory function. These results may have particular relevance for understanding the relation between hearing loss and human speech production especially where there is consideration of an auditory prosthetic device. The present results show, at least for a bird, that even limited recovery of auditory input soon after deafening can support full recovery of vocal precision.
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The H-2Ld alloreactive 2C T cell receptor (TCR) is commonly considered as being positively selected on the H-2Kb molecule. Surprisingly, 2C TCR+ CD8+ single-positive T cells emerge in massive numbers in fetal thymic organ culture originating from 2C transgenic, H-2KbDb−/− (2C+KbDb−/−) but not in fetal thymic organ culture from β2-microglobulin−/− 2C transgenic animals. Mature CD8+ T cells are observed in newborn but not in adult 2C+KbDb−/− mice. These CD8+ T cells express the α4β7 integrin, which allows them to populate the intestine, a pattern of migration visualized by intrathymic injection of FITC and subsequent accrual of FITC-labeled lymphocytes in the gut. We conclude that the 2C TCR is reactive not only with H-2Ld and H-2Kb, but also with nonclassical MHC class I products to enable positive selection of 2C+ T cells in the fetal and newborn thymus and to support their maintenance in the intestine.
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Swiftlets are small insectivorous birds, many of which nest in caves and are known to echolocate. Due to a lack of distinguishing morphological characters, the taxonomy of swiftlets is primarily based on the presence or absence of echolocating ability, together with nest characters. To test the reliability of these behavioral characters, we constructed an independent phylogeny using cytochrome b mitochondrial DNA sequences from swiftlets and their relatives. This phylogeny is broadly consistent with the higher classification of swifts but does not support the monophyly of swiftlets. Echolocating swiftlets (Aerodramus) and the nonecholocating "giant swiftlet" (Hydrochous gigas) group together, but the remaining nonecholocating swiftlets belonging to Collocalia are not sister taxa to these swiftlets. While echolocation may be a synapomorphy of Aerodramus (perhaps secondarily lost in Hydrochous), no character of Aerodramus nests showed a statistically significant fit to the molecular phylogeny, indicating that nest characters are not phylogenetically reliable in this group.
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A hierarchy of enzyme-catalyzed positive feedback loops is examined by mathematical and numerical analysis. Four systems are described, from the simplest, in which an enzyme catalyzes its own formation from an inactive precursor, to the most complex, in which two sequential feedback loops act in a cascade. In the latter we also examine the function of a long-range feedback, in which the final enzyme produced in the second loop activates the initial step in the first loop. When the enzymes generated are subject to inhibition or inactivation, all four systems exhibit threshold properties akin to excitable systems like neuron firing. For those that are amenable to mathematical analysis, expressions are derived that relate the excitation threshold to the kinetics of enzyme generation and inhibition and the initial conditions. For the most complex system, it was expedient to employ numerical simulation to demonstrate threshold behavior, and in this case long-range feedback was seen to have two distinct effects. At sufficiently high catalytic rates, this feedback is capable of exciting an otherwise subthreshold system. At lower catalytic rates, where the long-range feedback does not significantly affect the threshold, it nonetheless has a major effect in potentiating the response above the threshold. In particular, oscillatory behavior observed in simulations of sequential feedback loops is abolished when a long-range feedback is present.
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During fertilization in marine invertebrates, fusion between sperm and egg cell membranes occurs at the tip of the sperm acrosomal process. In abalone sperm the acrosomal process is coated with an 18-kDa protein. In situ, this protein has no effect on the egg vitelline envelope, but in vitro it is a potent fusagen of liposomes. Thus, the 18-kDa protein may mediate membrane fusion between the gametes, a step in gamete recognition known to restrict heterospecific fertilization in other species. The cDNA and deduced amino acid sequences of the 18-kDa protein were determined for five species of California abalone. The deduced amino acid sequences exhibit extraordinary divergence; the percent identity varies from 27% to 87%. Analysis of nucleotide substitution shows extremely high frequencies of amino acid-altering substitution compared to silent substitution, demonstrating that positive Darwinian selection promotes the divergence of this protein. However, amino acid replacement is conservative with respect to size and polarity of residue. The data support the developing idea that in free-spawning marine invertebrates, the proteins mediating fertilization may be subjected to intense, and as yet unknown, selective forces. The extraordinary divergence of fertilization proteins may be related to the establishment of barriers to heterospecific fertilization.
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Il tatto assume un'importanza fondamentale nella vita quotidiana, in quanto ci permette di discriminare le caratteristiche fisiche di un oggetto specifico, di identificarlo e di eventualmente integrare le suddette informazioni tattili con informazioni provenienti da altri canali sensoriali. Questa è la componente sensoriale-discriminativa del tatto. Tuttavia quotidianamente il tatto assume un ruolo fondamentale durante le diverse interazioni sociali, positive, come quando abbracciamo o accarezziamo una persona con cui abbiamo un rapporto affettivo e negative, per esempio quando allontaniamo una persona estranea dal nostro spazio peri-personale. Questa componente è la cosiddetta dimensione affettiva-motivazionale, la quale determina la codifica della valenza emotiva che l'interazione assume. Questa componente ci permette di creare, mantenere o distruggere i legami sociali in relazione al significato che il tocco assume durante l'interazione. Se per esempio riceviamo una carezza da un familiare, questa verrà percepita come piacevole e assumerà un significato affiliativo. Questo tipo di tocco è comunente definito come Tocco Sociale (Social Touch). Gli aspetti discriminativi del tatto sono stati ben caratterizzati, in quanto storicamente, il ruolo del tatto è stato considerato quello di discriminare le caratteristiche di ciò che viene toccato, mentre gli aspetti affettivi sono stati solo recentemente indagati considerando la loro importanza nelle interazioni sociali. Il tocco statico responsabile dell'aspetto discriminante attiva a livello della pelle le grandi fibre mieliniche (Aβ), modulando a livello del sistema nervoso centrale le cortecce sensoriali, sia primarie che secondarie. Questo permette la codifica a livello del sistema nervoso centrale delle caratteristiche fisiche oggettive degli oggetti toccati. Studi riguardanti le caratteristiche del tocco affiliativo sociale hanno messo in evidenza che suddetta stimolazione tattile 1) è un particolare tocco dinamico che avviene sul lato peloso delle pelle con una velocità di 1-10 cm/sec; 2) attiva le fibre amieliniche (fibre CT o C-LTMRs); 3) induce positivi effetti autonomici, ad esempio la diminuzione della frequenza cardiaca e l'aumento della variabilità della frequenza cardiaca; e 4) determina la modulazione di regioni cerebrali coinvolte nella codifica del significato affiliativo dello stimolo sensoriale periferico, in particolare la corteccia insulare. Il senso del tatto, con le sue due dimensioni discriminativa e affiliativa, è quotidianamente usato non solo negli esseri umani, ma anche tra i primati non umani. Infatti, tutti i primati non umani utilizzano la componente discriminativa del tatto per identificare gli oggetti e il cibo e l'aspetto emotivo durante le interazioni sociali, sia negative come durante un combattimento, che positive, come durante i comportamenti affiliativi tra cui il grooming. I meccanismi di codifica della componente discriminativa dei primati non umani sono simili a quelli umani. Tuttavia, si conosce ben poco dei meccanismi alla base della codifica del tocco piacevole affiliativo. Pur essendo ben noto che i meccanorecettori amilienici C-LTMRs sono presenti anche sul lato peloso della pelle dei primati non umani, attualmente non ci sono studi riguardanti la correlazione tra il tocco piacevole e la loro modulazione, come invece è stato ampiamente dimostrato nell'uomo. Recentemente è stato ipotizzato (Dunbar, 2010) il ruolo delle fibre C-LTMRs durante il grooming, in particolare durante il cosiddetto swepping. Il grooming è costituito da due azioni motorie, lo sweeping e il picking che vengono eseguite in modo ritmico. Durante lo sweeping la scimmia agente muove il pelo della scimmia ricevente con un movimento a mano aperta, per poter vedere il preciso punto della pelle dove eseguire il picking, ovvero dove prendere la pelle a livello della radice del pelo con le unghie dell'indice e del pollice e tirare per rimuovere parassiti o uova di parassiti e ciò che è rimasto incastrato nel pelo. Oltre il noto ruolo igenico, il grooming sembra avere anche una importante funzione sociale affiliativa. Come la carezza nella società umana, cosi il grooming tra i primati non umani è considerato un comportamento. Secondo l'ipotesi di Dunbar l'attivazione delle C-LTMRs avverrebbe durante lo sweeping e questo porta a supporre che lo sweeping, come la carezza umana, costituisca una componente affiliativa del grooming, determinando quindi a contribuire alla sua codifica come comportamento sociale. Fino ad ora non vi è però alcuna prova diretta a sostegno di questa ipotesi. In particolare, 1) la velocità cui viene eseguito lo sweeping è compatibile con la velocità di attivazione delle fibre CT nell'uomo e quindi con la velocità tipica della carezza piacevole di carattere sociale affiliativo (1-10 cm/sec)?; 2) lo sweeping induce la stessa modulazione del sistema nervoso autonomo in direzione della modulazione del sistema vagale, come il tocco piacevole nell'uomo, attraverso l'attivazione delle fibre CT?; 3) lo sweeping modula la corteccia insulare, cosi come il tocco piacevole viene codificato come affiliativo nell'uomo mediante le proiezioni delle fibre CT a livello dell'insula posteriore? Lo scopo del presente lavoro è quella di testare l'ipotesi di Dunbar sopra citata, cercando quindi di rispondere alle suddette domande. Le risposte potrebbero consentire di ipotizzare la somiglianza tra lo sweeping, caratteristico del comportamento affiliativo di grooming tra i primati non umani e la carezza. In particolare, abbiamo eseguito 4 studi pilota. Nello Studio 1 abbiamo valutato la velocità con cui viene eseguito lo sweeping tra scimmie Rhesus, mediante una analisi cinematica di video registrati tra un gruppo di scimmie Rhesus. Negli Studi 2 e 3 abbiamo valutato gli effetti sul sistema nervoso autonomo dello sweeping eseguito dallo sperimentatore su una scimmia Rhesus di sesso maschile in una tipica situazione sperimentale. La stimolazione tattile è stata eseguita a diverse velocità, in accordo con i risultati dello Studio 1 e degli studi umani che hanno dimostrato la velocità ottimale e non ottimale per l'attivazione delle C-LTMRs. In particolare, nello Studio 2 abbiamo misurato la frequenza cardiaca e la variabilità di questa, come indice della modulatione vagale, mentre nello Studio 3 abbiamo valutato gli effetti dello sweeping sul sistema nervoso autonomo in termini di variazioni di temperatura del corpo, nello specifico a livello del muso della scimmia. Infine, nello Studio 4 abbiamo studiato il ruolo della corteccia somatosensoriale secondaria e insulare nella codifica dello sweeping. A questo scopo abbiamo eseguito registrazioni di singoli neuroni mentre la medesima scimmia soggetto sperimentale dello Studio 2 e 3, riceveva lo sweeping a due velocità, una ottimale per l'attivazione delle C-LTMRs secondo gli studi umani e i risultati dei tre studi sopra citati, ed una non ottimale. I dati preliminari ottenuti, dimostrano che 1) (Studio 1) lo sweeping tra scimmie Rhesus viene eseguito con una velocità media di 9.31 cm/sec, all'interno dell'intervallo di attivazione delle fibre CT nell'uomo; 2) (Studio 2) lo sweeping eseguito dallo sperimentatore sulla schiena di una scimmia Rhesus di sesso maschile in una situazione sperimentale determina una diminuzione della frequenza cardiaca e l'aumento della variabilità della frequenza cardiaca se eseguito alla velocità di 5 e 10 cm/sec. Al contrario, lo sweeping eseguito ad una velocità minore di 1 cm/sec o maggiore di 10 cm/sec, determina l'aumento della frequenza cardiaca e la diminuzione della variabilità di questa, quindi il decremento dell'attivazione del sistema nervoso parasimpatico; 3) (Studio 3) lo sweeping eseguito dallo sperimentatore sulla schiena di una scimmia Rhesus di sesso maschile in una situazione sperimentale determina l'aumento della temperatura corporea a livello del muso della scimmia se eseguito alla velocità di 5-10 cm/sec. Al contrario, lo sweeping eseguito ad una velocità minore di 5 cm/sec o maggiore di 10 cm/sec, determina la diminuzione della temperatura del muso; 4) (Studio 4) la corteccia somatosensoriale secondaria e la corteccia insulare posteriore presentano neuroni selettivamente modulati durante lo sweeping eseguito ad una velocità di 5-13 cm/sec ma non neuroni selettivi per la codifica della velocità dello sweeping minore di 5 cm/sec. Questi risultati supportano l'ipotesi di Dunbar relativa al coinvolgimento delle fibre CT durante lo sweeping. Infatti i dati mettono in luce che lo sweeping viene eseguito con una velocità (9.31 cm/sec), simile a quella di attivazione delle fibre CT nell'uomo (1-10 cm/sec), determina gli stessi effetti fisiologici positivi in termini di frequenza cardiaca (diminuzione) e variabilità della frequenza cardiaca (incremento) e la modulazione delle medesime aree a livello del sistema nervoso centrale (in particolare la corteccia insulare). Inoltre, abbiamo dimostrato per la prima volta che suddetta stimolazione tattile determina l'aumento della temperatura del muso della scimmia. Il presente studio rappresenta la prima prova indiretta dell'ipotesi relativa alla modulazione del sistema delle fibre C-LTMRs durante lo sweeping e quindi della codifica della stimolazione tattile piacevole affiliativa a livello del sistema nervoso centrale ed autonomo, nei primati non umani. I dati preliminari qui presentati evidenziano la somiglianza tra il sistema delle fibre CT dell'uomo e del sistema C-LTMRs nei primati non umano, riguardanti il Social Touch. Nonostante ciò abbiamo riscontrato alcune discrepanze tra i risultati da noi ottenuti e quelli invece ottenuti dagli studi umani. La velocità media dello sweeping è di 9.31 cm / sec, rasente il limite superiore dell’intervallo di velocità che attiva le fibre CT nell'uomo. Inoltre, gli effetti autonomici positivi, in termini di battito cardiaco, variabilità della frequenza cardiaca e temperatura a livello del muso, sono stati evidenziati durante lo sweeping eseguito con una velocità di 5 e 10 cm/sec, quindi al limite superiore dell’intervallo ottimale che attiva le fibre CT nell’uomo. Al contrario, lo sweeping eseguito con una velocità inferiore a 5 cm/sec e superiore a 10 cm/sec determina effetti fisiologici negativo. Infine, la corteccia insula sembra essere selettivamente modulata dallo stimolazione eseguita alla velocità di 5-13 cm/sec, ma non 1-5 cm/sec. Quindi, gli studi sul sistema delle fibre CT nell’uomo hanno dimostrato che la velocità ottimale è 1-10 cm/sec, mentre dai nostri risultati la velocità ottimale sembra essere 5-13 cm / sec. Quindi, nonostante l'omologia tra il sistema delle fibre CT nell'umano deputato alla codifica del tocco piacevole affiliativo ed il sistema delle fibre C-LTMRs nei primati non umani, ulteriori studi saranno necessari per definire con maggiore precisione la velocità ottimale di attivazione delle fibre C-LTMR e per dimostrare direttamente la loro attivazione durante lo sweeping, mediante la misurazione diretta della loro modulazione. Studi in questa direzione potranno confermare l'omologia tra lo sweeping in qualità di tocco affiliativo piacevole tra i primati non umani e la carezza tra gli uomini. Infine, il presente studio potrebbe essere un importante punto di partenza per esplorare il meccanismo evolutivo dietro la trasformazione dello sweeping tra primati non umani, azione utilitaria eseguita durante il grooming, a carezza, gesto puramente affiliativo tra gli uomini.