Association of beta 1 integrin with focal adhesion kinase and paxillin in differentiating Schwann cells

Schwann cells (SCs) differentiate into a myelinating cell when simultaneously adhering to an axon destined for myelination and basal lamina. We are interested in defining the signaling pathway activated by basal lamina. Using SC/sensory neuron (N) cocultures, we identified beta 1 integrin and F-actin as components of a pathway leading to myelin gene expression and myelination (Fernandez-Valle et al., 1994, 1997). Here, we show that focal adhesion kinase (FAK) and paxillin are constitutively expressed by SCs contacting axons in the absence of basal lamina. Tyrosine phosphorylation of FAK and paxillin increases as SCs form basal lamina and differentiate. FAK and paxillin specifically coimmunoprecipitate with beta 1 integrin in differentiating SC/N cocultures but not SC-only cultures. Paxillin coimmunoprecipitates with FAK and fyn kinase in differentiating SC/N cocultures. A subset of tyrosine-phosphorylated b1 integrin, FAK, and paxillin molecules reside in the insoluble, F-actin-rich fraction of differentiating cocultures. Cytochalasin D, an actin depolymerizing agent, decreases tyrosine phosphorylation of FAK and paxillin and their association with b1 integrin and causes a dose-dependent increase in the abundance of insoluble FAK and paxillin complexes. Collectively, our work indicates that b1 integrin, FAK, paxillin, and fyn kinase form an actin-associated complex in SCs adhering to basal lamina in the presence of axons. This complex may be important for initiating the process of SC differentiation into a myelinating cell

Non-Destructive Global and Localized 2D T1/T2 NMR Relaxometry to Resolve Microstructure in Apples Affected by Watercore

Apples can be considered as having a complex system formed by several structures at different organization levels: macroscale (>100 μm) and microscale (>100 μm) and microscale (<100 μm). This work implements 2D T1/T2 global and localized relaxometry sequences on whole apples to be able to perform an intensive non-destructive and non-invasive microstructure study. The 2D T1/T2 cross-correlation spectroscopy allows the extraction of quantitative information about the water compartmentation in different subcellular organelles. A clear difference is found as sound apples show neat peaks for water in different subcellular compartments, such as vacuolar, cytoplasmatic and extracellular water, while in watercore-affected tissues such compartments appear merged. Localized relaxometry allows for the predefinition of slices in order to understand the microstructure of a particular region of the fruit, providing information that cannot be derived from global 2D T1/T2 relaxometry

Updated limits on visibly and invisibly decaying Higgs bosons from LEP

Talk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994, MeribelTalk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994, MeribelTalk presented at the XXIX Rencontres de Moriond, Electroweak Interactions and Unified Theories, March 12-19, 1994, Meribe

Model Independent Higgs Boson Mass Limits at LEP

We derive model-independent constraints on Higgs mass and couplings from associated signals for higher masses, accessible at LEP2. This work is motivated by the fact that, in many extensions of the standard model, the Higgs boson can have substantial "invisible" decay modes, for example, into light or massless weakly interacting Goldstone bosons associated to the spontaneous violation of lepton number below the weak scale.Comment: FTUV/93-19, 13 pag + 2 figures(not included but available upon request), Late

MRI texture analysis as means for addressing rehydration and milk diffusion in cereals

Cereals microstructure is one of the primary quality attributes of cereals. Cereals rehydration and milk diffusion depends on such microstructure and thus, the crispiness and the texture, which will make it more palatable for the final consumer. Magnetic Resonance Imaging (MRI) is a very powerful tomographic tool since acquisition parameter leads to a wide possibility for identifying textures, structures and liquids mobility. It is suited for noninvasive imaging of water and fats. Rehydration and diffusion cereals processes were measured by MRI at different times and using two different kinds of milk, varying their fat level. Several images were obtained. A combination of textural analysis (based on the analysis of histograms) and segmentation methods (in order to understand the rehydration level of each variety of cereals) were performed. According to the rehydration level, no advisable clustering behaviour was found. Nevertheless, some differences were noticeable between the coating, the type of milk and the variety of cereals

El cuerpo femenino como espacio de lucha y poder en la literatura de habla inglesa : el legado de William Shakespeare en la narrativa de Toni Morrison y Margaret Atwood

Doctorado en Ciencias del Lenguaje con mención en Culturas ComparadasLa corporeidad identitaria femenina es un fenómeno social y cultural que se materializa en los discursos sociales. La construcción identitaria del cuerpo femenino está moldeada por el contexto social y expresa un determinado momento del devenir cultural. El discurso literario, como exponente de lo social, presenta huellas de este moldeado socio-cultural. Los interrogantes que problematizan esta investigación son los siguientes: ¿qué es lo que hace que un hecho social se vierta en un hecho literario?, ¿cómo es que una práctica socio-cultural plasmada en una obra modelizante -la shakesperiana- genera o deviene en prácticas culturales similares o disímiles?, ¿cómo se imprime la huella del legado discursivo de las obras de William Shakespeare en autoras que pertenecen a momentos y espacios culturales que, si bien son de habla inglesa, Toni Morrison y Margaret Atwood, manifiestan marcadamente su heterogeneidad? Las teorías que guían esta investigación son: 1- la teoría literaria: Bajtin y Williams, 2- la teoría del poder y la crítica feminista: Foulcault, Braidotti y Butler; y 3- la sociocrítica y el análisis del discurso crítico: Angenot y Fairclough. Las preguntas que pautan la construcción de la herramienta analítica están relacionadas con: 1-¿cuáles son las distintas huellas o marcas en la superficie textual que constituyen la identidad discursiva del cuerpo femenino en las obras shakespereanas y las de las autoras en cuestión?, 2- ¿existen prácticas discursivas materializadas en textos literarios que adquieren el estatuto de modelos culturales? Y, si las hay: 3- ¿pueden dichas prácticas o construcciones modelizantes trasvasarse de una cultura a otra a través de la producción literaria? Al concluir el estudio se determina que, en las postrimerías de la normatividad, y a pesar de la distancia temporal que separa al período isabelino del posmoderno, la corporeidad identitaria femenina se trasvasa de un estadio a otro. Este vínculo se establece como producto en las obras afroamericanas y canadienses, en tanto que el legado de W. Shakespeare irrumpe como el comienzo de un proceso de resquebrajamiento y se constituye en un legado sine qua non de la cultura posmoderna.Fil: Fernandez, Silvia Lucia del Valle. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina

The KeV Majoron as Dark Matter Particle

We consider a very weakly interacting KeV majoron as dark matter particle (DMP), which provides both the critical density $\rho_{cr} = 1.88 \times 10^{-29} h^{2}$ $g/cm^{3}$ and the galactic scale $M_{gal}$ $\sim m^{3}_{Pl}/m^{2}_{J} \sim 10^{12} M_{\odot} (m_{J}/1 KeV)^{-2}$ for galaxy formation. The majoron couples to leptons only through some new "directly interacting particles", called DIPS, and this provides the required smallness of the coupling constants. If the masses of these DIPS are greater than the scale $V_s$ characterizing the spontaneous violation of the global lepton symmetry they are absent at the corresponding phase transition ($T \sim V_s$) and the majorons are produced during the phase transition, never being in thermal equilibrium during the history of the universe. In the alternative case $m_{DIP} < V_{s}$ the majorons can be for a short period in thermal equilibrium. This scenario is not forbidden by nucleosynthesis and gives a reasonable growth factor for the density fluctuations compatible with COBE. A possible signature is an X-ray line at $E_\gamma = \frac{m_J}{2}$, produced by the decay $J \to \gamma + \gamma$. A model is described which realizes the possibility of the KeV majoron as DMP and may also lead to observable rates for decays such as \mu \ra e \gamma and \mu \ra 3e.Comment: 13 pages, 3 figures available upon request, FTUV/93-35, late