The Radio Jet Associated with the Multiple V380 Ori System

The giant Herbig-Haro object 222 extends over $\sim$6$'$ in the plane of the sky, with a bow shock morphology. The identification of its exciting source has remained uncertain over the years. A non-thermal radio source located at the core of the shock structure was proposed to be the exciting source. However, Very Large Array studies showed that the radio source has a clear morphology of radio galaxy and a lack of flux variations or proper motions, favoring an extragalactic origin. Recently, an optical-IR study proposed that this giant HH object is driven by the multiple stellar system V380 Ori, located about 23$'$ to the SE of HH 222. The exciting sources of HH systems are usually detected as weak free-free emitters at centimeter wavelengths. Here we report the detection of an elongated radio source associated with the Herbig Be star or with its close infrared companion in the multiple V380 Ori system. This radio source has the characteristics of a thermal radio jet and is aligned with the direction of the giant outflow defined by HH~222 and its suggested counterpart to the SE, HH~1041. We propose that this radio jet traces the origin of the large scale HH outflow. Assuming that the jet arises from the Herbig Be star, the radio luminosity is a few times smaller than the value expected from the radio-bolometric correlation for radio jets, confirming that this is a more evolved object than those used to establish the correlation.Comment: 13 pages, 3 figure

Defects and boundary layers in non-Euclidean plates

We investigate the behavior of non-Euclidean plates with constant negative Gaussian curvature using the F\"oppl-von K\'arm\'an reduced theory of elasticity. Motivated by recent experimental results, we focus on annuli with a periodic profile. We prove rigorous upper and lower bounds for the elastic energy that scales like the thickness squared. In particular we show that are only two types of global minimizers -- deformations that remain flat and saddle shaped deformations with isolated regions of stretching near the edge of the annulus. We also show that there exist local minimizers with a periodic profile that have additional boundary layers near their lines of inflection. These additional boundary layers are a new phenomenon in thin elastic sheets and are necessary to regularize jump discontinuities in the azimuthal curvature across lines of inflection. We rigorously derive scaling laws for the width of these boundary layers as a function of the thickness of the sheet

Scrt1, a transcriptional regulator of β-cell proliferation identified by differential chromatin accessibility during islet maturation.

Glucose-induced insulin secretion, a hallmark of mature β-cells, is achieved after birth and is preceded by a phase of intense proliferation. These events occurring in the neonatal period are decisive for establishing an appropriate functional β-cell mass that provides the required insulin throughout life. However, key regulators of gene expression involved in functional maturation of β-cells remain to be elucidated. Here, we addressed this issue by mapping open chromatin regions in newborn versus adult rat islets using the ATAC-seq assay. We obtained a genome-wide picture of chromatin accessible sites (~ 100,000) among which 20% were differentially accessible during maturation. An enrichment analysis of transcription factor binding sites identified a group of transcription factors that could explain these changes. Among them, Scrt1 was found to act as a transcriptional repressor and to control β-cell proliferation. Interestingly, Scrt1 expression was controlled by the transcriptional repressor RE-1 silencing transcription factor (REST) and was increased in an in vitro reprogramming system of pancreatic exocrine cells to β-like cells. Overall, this study led to the identification of several known and unforeseen key transcriptional events occurring during β-cell maturation. These findings will help defining new strategies to induce the functional maturation of surrogate insulin-producing cells

Small RNAs derived from tRNA fragmentation regulate the functional maturation of neonatal β cells.

tRNA-derived fragments (tRFs) are an emerging class of small non-coding RNAs with distinct cellular functions. Here, we studied the contribution of tRFs to the regulation of postnatal β cell maturation, a critical process that may lead to diabetes susceptibility in adulthood. We identified three tRFs abundant in neonatal rat islets originating from 5' halves (tiRNA-5s) of histidine and glutamate tRNAs. Their inhibition in these islets reduced β cell proliferation and insulin secretion. Mitochondrial respiration was also perturbed, fitting with the mitochondrial enrichment of nuclear-encoded tiRNA-5 <sup>HisGTG</sup> and tiRNA-5 <sup>GluCTC</sup> . Notably, tiRNA-5 inhibition reduced Mpc1, a mitochondrial pyruvate carrier whose knock down largely phenocopied tiRNA-5 inhibition. tiRNA-5 <sup>HisGTG</sup> interactome revealed binding to Musashi-1, which was essential for the mitochondrial enrichment of tiRNA-5 <sup>HisGTG</sup> . Finally, tiRNA-5s were dysregulated in the islets of diabetic and diabetes-prone animals. Altogether, tiRNA-5s represent a class of regulators of β cell maturation, and their deregulation in neonatal islets may lead to diabetes susceptibility in adulthood

Circular RNAs as novel regulators of β-cell functions in normal and disease conditions.

There is strong evidence for an involvement of different classes of non-coding RNAs, including microRNAs and long non-coding RNAs, in the regulation of β-cell activities and in diabetes development. Circular RNAs were recently discovered to constitute a substantial fraction of the mammalian transcriptome but the contribution of these non-coding RNAs in physiological and disease processes remains largely unknown. The goal of this study was to identify the circular RNAs expressed in pancreatic islets and to elucidate their possible role in the control of β-cells functions. We used a microarray approach to identify circular RNAs expressed in human islets and searched their orthologues in RNA sequencing data from mouse islets. We then measured the level of four selected circular RNAs in the islets of different Type 1 and Type 2 diabetes models and analyzed the role of these circular transcripts in the regulation of insulin secretion, β-cell proliferation, and apoptosis. We identified thousands of circular RNAs expressed in human pancreatic islets, 497 of which were conserved in mouse islets. The level of two of these circular transcripts, circHIPK3 and ciRS-7/CDR1as, was found to be reduced in the islets of diabetic db/db mice. Mimicking this decrease in the islets of wild type animals resulted in impaired insulin secretion, reduced β-cell proliferation, and survival. ciRS-7/CDR1as has been previously proposed to function by blocking miR-7. Transcriptomic analysis revealed that circHIPK3 acts by sequestering a group of microRNAs, including miR-124-3p and miR-338-3p, and by regulating the expression of key β-cell genes, such as Slc2a2, Akt1, and Mtpn. Our findings point to circular RNAs as novel regulators of β-cell activities and suggest an involvement of this novel class of non-coding RNAs in β-cell dysfunction under diabetic conditions

La formación del profesorado de ciencias de nivel medio superior en la provincia de México

El presente trabajo muestra los programas de formación docente de educación en ciencias que la Coordinación de Formación Docente de la Secretaría de Extensión Académica de la Facultad de Química de la Universidad Nacional Autónoma de México ofrece a los profesores de nivel medio superior de los diferentes estados de la República Mexicana con la finalidad de contribuir a mejorar la calidad de la enseñanza y del aprendizaje. Los programas están organizados en diplomados de 180 horas de clase, que constan de una conferencia inaugural motivacional, 8 módulos y una presentación de trabajos finales donde se aplican los conocimientos disciplinares y los enfoques pedagógico-didácticos y socio-filosófico aprendidos en el Diplomado

La Educación Ambiental en el marco de la Extensión

  En el marco de la acción de la Secretaría de Extensión de la Facultad de Ciencias Naturales y Museo de la Universidad Nacional de La Plata, concebimos la extensión como un valioso espacio de articulación y construcción bidireccional entre saberes académicos y populares. A lo largo de los años la Secretaría ha desarrollado numerosas propuestas. Muchas de ellas, por su fuerte identidad, se han instalado en la comunidad y cuentan con gran reconocimiento y participación. Estas raíces nos han guiado para re-pensar nuestras prácticas y abrir nuevos caminos. De este replanteo han surgido los lineamientos estratégicos de la Secretaría, que están concebidos como un instrumento de direccionamiento y orientación que facilite la toma de decisiones en la gestión, apuntando al trabajo en dos ámbitos paralelos, pero fuertemente vinculados: 1) El ámbito académico universitario, tanto a nivel de la Facultad de Ciencias Naturales como de otras unidades académicas de la UNLP y/o de otras universidades. 2) La comunidad en general, organizaciones de la sociedad civil, instituciones, etc. Los lineamientos buscan fortalecer la articulación facultad-comunidad, poniendo el énfasis en la necesidad de atender las diversas problemáticas que configuran la situación ambiental actual de la región, y donde la FCNyM constituye un actor indispensable. Por ello, apuntamos a que las actividades de extensión se alimenten de los planteos epistemológicos, éticos y metodológicos del Saber Ambiental (sensu E. Leff), de manera tal que articule y de coherencia, a manera de eje transversal, a todas las actividades desarrolladas por la Secretaría, alimentándolas y orientándolas. Objetivos Generales. 1) Jerarquizar la Extensión en la FCN y M, apuntando a generar conocimientos a partir de la integración con el medio y aportando al desarrollo social. 2) Conformar un ámbito que apunte a la construcción de un saber ambiental, nacido de una fuerte interacción entre las distintas disciplinas de nuestra Facultad, otras unidades académicas, organizaciones, instituciones, etc. Ejes estratégicos. Proponemos que los objetivos anteriormente mencionados, se plasmen y materialicen a través de los siguientes ejes estratégicos: 1) Fortalecimiento de la Extensión. 2) Construcción de un Saber Ambiental. 3) Vinculación con la comunidad. 4) Formación. 5) Comunicación/Difusión. 6) Planificación/ Gestión. La situación actual se presenta como crítica desde diversas dimensiones. Consideramos que este replanteo ordena, fortalece y enriquece nuestras actividades de extensión y permite posicionarnos mejor frente a la compleja realidad que atraviesa nuestra labor diaria.  

The role of asymmetric interactions on the effect of habitat destruction in mutualistic networks

Plant-pollinator mutualistic networks are asymmetric in their interactions: specialist plants are pollinated by generalist animals, while generalist plants are pollinated by a broad involving specialists and generalists. It has been suggested that this asymmetric ---or disassortative--- assemblage could play an important role in determining the equal susceptibility of specialist and generalist plants under habitat destruction. At the core of the argument lies the observation that specialist plants, otherwise candidates to extinction, could cope with the disruption thanks to their interaction with generalist pollinators. We present a theoretical framework that supports this thesis. We analyze a dynamical model of a system of mutualistic plants and pollinators, subject to the destruction of their habitat. We analyze and compare two families of interaction topologies, ranging from highly assortative to highly disassortative ones, as well as real pollination networks. We found that several features observed in natural systems are predicted by the mathematical model. First, there is a tendency to increase the asymmetry of the network as a result of the extinctions. Second, an entropy measure of the differential susceptibility to extinction of specialist and generalist species show that they tend to balance when the network is disassortative. Finally, the disappearance of links in the network, as a result of extinctions, shows that specialist plants preserve more connections than the corresponding plants in an assortative system, enabling them to resist the disruption.Comment: 14 pages, 7 figure