The Extracellular Matrix in the Nervous System: The Good and the Bad Aspects

The study of extracellular matrix (ECM) in the nervous system has longed been focused on the molecules promoting growth and migration. This is well supported by the work in the developing nervous system. However, the discovery of Nogo and chondroitin sulphate proteoglycans (CSPGs) in the injured nervous system in late 1980s has shifted some of the focus to inhibitory molecules. One of the biggest hurdles in neural regeneration is the formation of glial scar and the highly up-regulated inhibitory molecules present in the area. Apart from Nogo and CSPGs, other myelin-associated inhibitors, tenascins and semaphorins have been found associated with neuronal inhibition. Together with the identification of their receptors, we now have a better understanding on the mechanism of how these molecules control and limit regeneration in the central nervous system (CNS). Recent focus has been put on designing strategies in neutralizing these inhibitions for promoting regeneration after injury, and some are showing promising results. Moreover, latest studies also show that rehabilitation in injured animal models demonstrated drastic remodeling of ECM favoring regeneration. This review shall discuss all these different aspects and the importance of matrix remodeling in the CNS and the implication of ECM in some retinal pathologies

Conductance properties of nanotubes coupled to superconducting leads: signatures of Andreev states dynamics

We present a combined experimental and theoretical analysis of the low bias conductance properties of carbon nanotubes coupled to superconducting leads. In the Kondo regime the conductance exhibits a zero bias peak which can be several times larger than the unitary limit in the normal case. This zero bias peak can be understood by analyzing the dynamics of the subgap Andreev states under an applied bias voltage. It is shown that the existence of a linear regime is linked to the presence of a finite relaxation rate within the system. The theory provides a good fitting of the experimental results.Comment: 6 revtex4 pages, 6 figures, to appear in SS

How Do Whales See?

The eyes of two whales Balaenoptera physalus and Baleoptera borealis were studied by our group. In this chapter, we present the anatomical, histological, immunohistochemical and ultrastructural studies of the eyes of both types of whales. Based on the results, we can conclude that at least in these two species, the whales are rod monochromat; their resolution is very limited due to the reduced number of retinal ganglion cells, some of which were giant size (more than 100 micrometers in diameter). The excellent representation of melanopsinic positive retinal ganglion cells suggests an adaptation to the dim light as well as involvement in the circadian rhythms. The large cavernous body located in the back of the eye may provide a mechanism that allows them to move the eye forward and backwords; this may facilitate focusing and provide protection from cold deep-sea temperatures

Differential Distribution of RBPMS in Pig, Rat, and Human Retina after Damage

RNA binding protein with multiple splicing (RBPMS) is expressed exclusively in retinal ganglion cells (RGCs) in the retina and can label all RGCs in normal retinas of mice, rats, guinea pigs, rabbits, cats, and monkeys, but its function in these cells is not known. As a result of the limited knowledge regarding RBPMS, we analyzed the expression of RBPMS in the retina of different mammalian species (humans, pigs, and rats), in various stages of development (neonatal and adult) and with different levels of injury (control, hypoxia, and organotypic culture or explants). In control conditions, RBPMS was localized in the RGCs somas in the ganglion cell layer, whereas in hypoxic conditions, it was localized in the RGCs dendrites in the inner plexiform layer. Such differential distributions of RBPMS occurred in all analyzed species, and in adult and neonatal retinas. Furthermore, we demonstrate RBPMS localization in the degenerating RGCs axons in the nerve fiber layer of retinal explants. This is the first evidence regarding the possible transport of RBPMS in response to physiological damage in a mammalian retina. Therefore, RBPMS should be further investigated in relation to its role in axonal and dendritic degeneration.This research was funded by ELKARTEK KK-2019/00086, Research groups of the UPV/EHU (GIU 2018/50)and MINECO-Retos (PID2019-111139RB-I00) to E.V. Programa de perfeccionamiento de personal InvestigadorDoctor, Gobierno Vasco to X.P

¿Un problema en la oferta?… por el segundo paga la mitad

El presente trabajo, consiste en explorar de qué manera, individuos de diferentes edades, niveles de formación y experiencia, resuelven una actividad que, si bien para algunos puede ser “un problema” y para otros simplemente un “ejercicio de aplicación”, su solución puede encontrarse de distintas maneras utilizando conceptos matemáticos elementales. Se analizan los recursos utilizados y las dificultades evidenciadas por cada uno de los grupos, y se plantean algunos interrogantes que a nuestro entender merecen atención

Profesores de matemática en formación. Simulaciones de prácticas docentes con TICs

Al igual que Chile y Uruguay, Argentina ha puesto en marcha el programa Conectar igualdad, que proporciona a estudiantes y docentes computadoras con este fin. Sin embargo, estos cambios no se reflejan aún en las aulas y, sin lugar a duda, esto se relaciona con que “el profesor enseña cómo fue enseñado”. Por tal motivo, surge la necesidad de intervenir, en este sentido, en el escenario actual de la formación del futuro profesor. El presente trabajo describe una experiencia sobre simulaciones de clases con TICs. La misma se desarrolló en la asignatura Prácticas docentes I de la carrera del profesorado en matemática de la Universidad Nacional de Mar del Plata. Se expone el marco de referencia en el que se basa el trabajo, el encuadre de la asignatura, descripción y evaluación de la experiencia, opiniones de los alumnos sobre lo realizado y las actividades más creativas desarrolladas por ellos

Análisis de algunas dificultades en el aprendizaje en un tema de álgebra en alumnos de primer año de la universidad

El presente trabajo, de carácter exploratorio, es parte de una investigación más amplia tendiente a detectar las dificultades más frecuentes en el aprendizaje del Álgebra en el primer año de las carreras de Profesorado y Licenciatura en Matemática, indagar posibles causas y proponer alternativas de solución. A tal efecto se da tratamiento a las respuestas obtenidas por parte de los alumnos en dos actividades sobre conjuntos, tema inicial de la asignatura, las que han sido analizadas cualitativamente. Por otro lado, se administró un cuestionario de datos personales y laborales a los alumnos participantes. Se presenta aquí una descripción de las dificultades detectadas con mayor frecuencia