Análisis de los patrones instruccionales en las clases de resolución de problemas matemáticos verbales

En este estudio se analizan los patrones instruccionales en las clases de segundo ciclo de enseñanza básica destinados a la resolución de problemas (RP) matemáticos. Se analizan muestras de la Evaluación Docente 2013 identificando las actividades típicas de aula, las estructuras de participación y las ayudas otorgadas por los profesores. Si bien esta investigación se encuentra en curso, se presentan los primeros hallazgos pertenecientes a 10 profesores mediante un análisis del discurso y un análisis cuantitativo de tipo de descriptivo. Los resultados arrojan once actividades típicas de aula, que la estructura de participación recae en los profesores y que son diez las ayudas más utilizadas durante las sesiones de clase de RP

Revised timing of cenozoic atlantic incursions and changing hinterland sediment sources during southern patagonian orogenesis

New detrital zircon U-Pb geochronology data from the Cenozoic Magallanes-Austral Basin in Argentina and Chile ~51° S establish a revised chronostratigraphy of Paleocene-Miocene foreland synorogenic strata and document the rise and subsequent isolation of hinterland sources in the Patagonian Andes from the continental margin. The upsection loss of zircons derived from the hinterland Paleozoic and Late Jurassic sources between ca. 60 and 44Ma documents a major shift in sediment routing due to Paleogene orogenesis in the greater Patagonian-Fuegian Andes. Changes in the proportion of grains from hinterland thrust sheets, comprised of Jurassic volcanics and Paleozoic metasedimentary rocks, provide a trackable signal of long-term shifts in orogenic drainage divide and topographic isolation due to widening of the retroarc fold-thrust belt. The youngest detrital zircon U-Pb ages confirm timing of Maastrichtian-Eocene strata but require substantial age revisions for part of the overlying Cenozoic basinfill during the late Eocene and Oligocene. The upper Río Turbio Formation, previously mapped as middle to late Eocene in the published literature, records a newly recognized latest Eocene-Oligocene (37-27Ma) marine incursion along the basin margin. We suggest that these deposits could be genetically linked to the distally placed units along the Atlantic coast, including the El Huemul Formation and the younger San Julián Formation, via an eastward deepening within the foreland basin system that culminated in a basin-wide Oligocene marine incursion in the Southern Andes. The overlying Río Guillermo Formation records onset of tectonically generated coarse-grained detritus ca. 24.3Ma and a transition to the first fully nonmarine conditions on the proximal Patagonian platform since Late Cretaceous time, perhaps signaling a Cordilleran-scale upper plate response to increased plate convergence and tectonic plate reorganization.Fil: Fosdick, Julie C.. University of Connecticut; Estados UnidosFil: VanderLeest, R. A.. University of Connecticut; Estados UnidosFil: Bostelmann, J. E.. Universidad de Chile; ChileFil: Leonard, J. S.. Arizona State University; Estados UnidosFil: Ugalde, R.. Universidad Mayor; ChileFil: Oyarzún, J. L.. Parque Geo-paleontológico la Cumbre-baguales; ChileFil: Griffin, Miguel. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleozoología Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Connexin and Pannexin-Based Channels in Oligodendrocytes: Implications in Brain Health and Disease

Oligodendrocytes are the myelin forming cells in the central nervous system (CNS). In addition to this main physiological function, these cells play key roles by providing energy substrates to neurons as well as information required to sustain proper synaptic transmission and plasticity at the CNS. The latter requires a fine coordinated intercellular communication with neurons and other glial cell types, including astrocytes. In mammals, tissue synchronization is mainly mediated by connexins and pannexins, two protein families that underpin the communication among neighboring cells through the formation of different plasma membrane channels. At one end, gap junction channels (GJCs; which are exclusively formed by connexins in vertebrates) connect the cytoplasm of contacting cells allowing electrical and metabolic coupling. At the other end, hemichannels and pannexons (which are formed by connexins and pannexins, respectively) communicate the intra- and extracellular compartments, serving as diffusion pathways of ions and small molecules. Here, we briefly review the current knowledge about the expression and function of hemichannels, pannexons and GJCs in oligodendrocytes, as well as the evidence regarding the possible role of these channels in metabolic and synaptic functions at the CNS. In particular, we focus on oligodendrocyte-astrocyte coupling during axon metabolic support and its implications in brain health and disease

ESTUDIO DE SENSIBILIDAD ANTIMICROBIANA DE 183 CEPAS DE STREPTOCOCCUS AGALACTIAE AISLADAS EN REGION VAGINO-PERINEAL DE EMBARAZADAS EN EL TERCER TRIMESTRE

fluctúa entre 1 y 3 por 1000 recién nacidos vivos. Se han entregado pautas dirigidas a reducir las tasas de sepsis precoz con la administración de antibióticos intraparto. Se ha propuesto como antibiótico de primera elección la Penicilina o Ampicilina, y Clindamicina para pacientes alérgicos a las primeras, pero también se ha planteado el uso de Eritromicina o Cefazolina. Se estudia la sensibilidad a estas drogas, en 183 cepas de Streptococcus Grupo B, aisladas en 917 embarazadas, al final del tercer trimestre, en región vaginal y

Integrated methylome and phenome study of the circulating proteome reveals markers pertinent to brain health

Characterising associations between the methylome, proteome and phenome may provide insight into biological pathways governing brain health. Here, we report an integrated DNA methylation and phenotypic study of the circulating proteome in relation to brain health. Methylome-wide association studies of 4058 plasma proteins are performed (N = 774), identifying 2928 CpG-protein associations after adjustment for multiple testing. These are independent of known genetic protein quantitative trait loci (pQTLs) and common lifestyle effects. Phenome-wide association studies of each protein are then performed in relation to 15 neurological traits (N = 1,065), identifying 405 associations between the levels of 191 proteins and cognitive scores, brain imaging measures or APOE e4 status. We uncover 35 previously unreported DNA methylation signatures for 17 protein markers of brain health. The epigenetic and proteomic markers we identify are pertinent to understanding and stratifying brain health

Survey and Molecular Characterization of Sarcocystidae protozoa in Wild Cricetid Rodents from Central and Southern Chile

In Chile, studies of parasites from the family Sarcocystidae (Apicomplexa) have mostly been related to domestic animals. We aimed to assess the presence of Sarcocystidae taxa in cricetid rodents from Central and Southern Chile. We studied 207 rodents, encompassing six species, from 13 localities. We isolated DNA from tissue samples, amplified the Sarcocystidae 18S rRNA gene with polymerase chain reaction, and performed phylogenetic analyses using maximum likelihood and Bayesian inferences. In addition, we examined blood smears and performed histological studies in organs from Sarcocystidae DNA-positive animals. Three specimens were DNA-positive and three genotypes were retrieved and named: Sarcocystis sp. P61, related to Sarcocystis strixi, was detected in two Abrothrix olivacea. Toxoplasmatinae gen. sp. P99 was retrieved from those same two specimens, and was related to Toxoplasma and other genera, although it branched independently. Besnoitia sp. R34 was detected in one Abrothrix hirta, and was clustered with congeneric species associated with rodents. No protozoa were found during microscopic studies; thus, it was not possible to confirm parasitic interactions rather than accidental encounters. However, the close relatedness of the retrieved genotypes to parasites of rodents supports the hypothesis of host–parasite associations. All three genotypes are suggested as potential new taxa, including a putative new genus.This research was funded by the ANID Programa Becas Doctorado Nacional under grant numbers 2019–21190078, 2020–21200182, and 2022-21220118; and Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT) under grant number 11170294.Peer reviewe

Dynamic metabolic control: towards precision engineering of metabolism

Advances in metabolic engineering have led to the synthesis of a wide variety of valuable chemicals in microorganisms. The key to commercializing these processes is the improvement of titer, productivity, yield, and robustness. Traditional approaches to enhancing production use the “push–pull-block” strategy that modulates enzyme expression under static control. However, strains are often optimized for specific laboratory set-up and are sensitive to environmental fluctuations. Exposure to sub-optimal growth conditions during large-scale fermentation often reduces their production capacity. Moreover, static control of engineered pathways may imbalance cofactors or cause the accumulation of toxic intermediates, which imposes burden on the host and results in decreased production. To overcome these problems, the last decade has witnessed the emergence of a new technology that uses synthetic regulation to control heterologous pathways dynamically, in ways akin to regulatory networks found in nature. Here, we review natural metabolic control strategies and recent developments in how they inspire the engineering of dynamically regulated pathways. We further discuss the challenges of designing and engineering dynamic control and highlight how model-based design can provide a powerful formalism to engineer dynamic control circuits, which together with the tools of synthetic biology, can work to enhance microbial production

Prediction of Cellular Burden with Host--Circuit Models

Heterologous gene expression draws resources from host cells. These resources include vital components to sustain growth and replication, and the resulting cellular burden is a widely recognised bottleneck in the design of robust circuits. In this tutorial we discuss the use of computational models that integrate gene circuits and the physiology of host cells. Through various use cases, we illustrate the power of host-circuit models to predict the impact of design parameters on both burden and circuit functionality. Our approach relies on a new generation of computational models for microbial growth that can flexibly accommodate resource bottlenecks encountered in gene circuit design. Adoption of this modelling paradigm can facilitate fast and robust design cycles in synthetic biology

The Proteome of Biologically Active Membrane Vesicles from Piscirickettsia salmonis LF-89 Type Strain Identifies Plasmid-Encoded Putative Toxins

Piscirickettsia salmonis is the predominant bacterial pathogen affecting the Chilean salmonid industry. This bacterium is the etiological agent of piscirickettsiosis, a significant fish disease. Membrane vesicles (MVs) released by P. salmonis deliver several virulence factors to host cells. To improve on existing knowledge for the pathogenicity-associated functions of P. salmonis MVs, we studied the proteome of purified MVs from the P. salmonis LF-89 type strain using multidimensional protein identification technology. Initially, the cytotoxicity of different MV concentration purified from P. salmonis LF-89 was confirmed in an in vivo adult zebrafish infection model. The cumulative mortality of zebrafish injected with MVs showed a dose-dependent pattern. Analyses identified 452 proteins of different subcellular origins; most of them were associated with the cytoplasmic compartment and were mainly related to key functions for pathogen survival. Interestingly, previously unidentified putative virulence-related proteins were identified in P. salmonis MVs, such as outer membrane porin F and hemolysin. Additionally, five amino acid sequences corresponding to the Bordetella pertussis toxin subunit 1 and two amino acid sequences corresponding to the heat-labile enterotoxin alpha chain of Escherichia coli were located in the P. salmonis MV proteome. Curiously, these putative toxins were located in a plasmid region of P. salmonis LF-89. Based on the identified proteins, we propose that the protein composition of P. salmonis LF-89 MVs could reflect total protein characteristics of this P. salmonis type strain

Consenso salud materna para Chile en el nuevo milenio

Contexto: Chile presenta una tendencia secular hacia una sostenida mejoría en los principales indicadores materno-infantiles. Su situación constituye una experiencia positiva a nivel de la región de Latino-América y el Caribe. Sin embargo, esta tendencia se ha estancado en los últimos diez años lo que produce una situación inestable y preocupante desde el punto de vista de la salud pública materna. Esto motiva una reunión de expertos a nivel nacional e internacional para proponer estrategias para el alto nivel político orientadas a alcanzar los Objetivos 4 y 5 del Milenio. Conclusión: Este documento de consenso sobre mortalidad materna, sugiere un enfrentamiento en dos ejes: primero, enfrentar la nueva realidad epidemiológica desde la etapa pre-concepcional, esto incluye considerar la alta prevalencia de obesidad, hipertensión arterial, diabetes, hiperlipidemias e hipotiroidismo en la población, y por otro lado reforzar la seguridad de la asistencia del embarazo, parto y puerperio en los lugares más alejados y más vulnerables del país. Es necesario focalizar las intervenciones en los grupos de mayor riesgo vital (edades extremas de la vida fértil y portadoras de enfermedades médico-quirúrgicas severas, que se reflejan en el aumento proporcional de las causas indirectas de muerte materna), reforzar las actividades de auditorías de mortalidad/near miss, así como controlar el aumento alarmante de la tasa de partos por cesáreas