The Changes in Ca2+ Sparks Associated with Measured Modifications of Intra-store Ca2+ Concentration in Skeletal Muscle

In cardiac muscle and amphibian skeletal muscle, the intracellular Ca2+ release that signals contractile activation proceeds by discrete local packets, which result in Ca2+ sparks. The remarkably stereotyped duration of these release events requires a robustly timed termination mechanism. In cardiac muscle the mechanism of spark termination appears to crucially involve depletion of Ca2+ in the lumen of the sarcoplasmic reticulum (SR), but in skeletal muscle, the mechanism is unknown. We used SEER (shifted excitation and emission ratioing of fluorescence) of SR-trapped mag-indo-1 and confocal imaging of fluorescence of cytosolic rhod-2 to image Ca2+ sparks while reversibly changing and measuring [Ca2+] in the SR ([Ca2+]SR) of membrane-permeabilized frog skeletal muscle cells. Sparks were collected in cells immersed in a solution promoting production of events at moderate frequency. Just after permeabilization, event frequency was zero, and in 10 minutes it reached close to a steady value. Controlled interventions modified [Ca2+]SR reversibly between a low value (299 μM on average in 10 experiments) and a high value (433 μM, a 45% average increase). This change increased sparks frequency by 93%, spatial width by 7%, rise time by 10%, and peak amplitude by 38% (provided that it was calculated in absolute terms, rather than normalized by resting fluorescence). The changes in event frequency and amplitude were statistically significant. The “strength” of the effect of [Ca2+]SR on frequency, quantified by decomposition of variance, was <6%. While the average change in [Ca2+]SR was limited, it reached up to 200% in individual fibers, without causing massive Ca2+ release or an increase of >3.5-fold in event frequency. Taken together with existing evidence that depletion is modest during Ca2+ sparks or release elicited by an action potential, the mild effects of [Ca2+]SR reported here do not support a major role of depletion in either the termination of sparks or the strong inactivation that terminates Ca2+ release at the global level in frog skeletal muscle

SOCIEDADE CIVIL E CONTROLE SOCIAL DEMOCRÁTICO: profícuo campo de extensão universitária

RESUMO: O artigo socializa a prática extensionista da Universidade Federal de Santa Catarina – por meio do Núcleo de Estudos da Criança, Adolescente e Família – junto às instâncias de controle social municipal e estadual na área da criança e adolescente em Santa Catarina. O estreitamento das relações, entre universidade e sociedade, acontece por meio da assessoria sistemática à sociedade civil. As principais atividades desenvolvidas foram: a participação nas reuniões mensais do fórum e plenárias mensais dos conselhos de direitos da criança e do adolescente municipal de Florianópolis e estadual de Santa Catarina; desenvolvimento de estudos, elaboração do Plano Decenal, documentos, projetos e pareceres; capacitações de conselheiros. Conclui-se que as ações extensionistas têm contribuído na qualificação e fortalecimento da representação da sociedade civil, contudo ainda existem desafios importantes como o de responsabilizar os representantes governamentais para maior presença nesses espaços democráticos de controle social voltado à política da infância e adolescência

lcc: an R package to estimate the concordance correlation, Pearson correlation and accuracy over time

Background and Objective: Observational studies and experiments in medicine, pharmacology and agronomy are often concerned with assessing whether different methods/raters produce similar values over the time when measuring a quantitative variable. This article aims to describe the statistical package lcc, for are, that can be used to estimate the extent of agreement between two (or more) methods over the time, and illustrate the developed methodology using three real examples. Methods: The longitudinal concordance correlation, longitudinal Pearson correlation, and longitudinal accuracy functions can be estimated based on fixed effects and variance components of the mixed-effects regression model. Inference is made through bootstrap confidence intervals and diagnostic can be done via plots, and statistical tests. Results: The main features of the package are estimation and inference about the extent of agreement using numerical and graphical summaries. Moreover, our approach accommodates both balanced and unbalanced experimental designs or observational studies, and allows for different within-group error structures, while allowing for the inclusion of covariates in the linear predictor to control systematic variations in the response. All examples show that our methodology is flexible and can be applied to many different data types. Conclusions: The lcc package, available on the CRAN repository, proved to be a useful tool to describe the agreement between two or more methods over time, allowing the detection of changes in the extent of agreement. The inclusion of different structures for the variance-covariance matrices of random effects and residuals makes the package flexible for working with different types of databases

Medición de la capacidad de nitrificación mediante la técnica de incubaciones in situ en suelos cultivados con maíz

p.101-114Se realizaron incubaciones de suelo a campo en cilindros con el objeto de mantener la estructura del mismo, recubriéndolos con bolsas de polietileno evitando a sí pérdidas de N por lavado. Se trabajó con suelos de la zona núcleo maicera durante los meses de enero y febrero (Campañas 1982-83 y 1983-84). La producción de nitratos se calculó por diferencia entre la concentración al cabo de un mes de incubación y el contenido inicial. El proceso de mineralización se vio afectado por el tenor hídrico inicial, liberándose del 0,7 al 0,9 por ciento del nitrógeno total. Paralelamente, se realizaron incubaciones de laboratorio en condiciones controladas de temperatura y humedad para los cuales se obtuvieron tasas cuatro veces superiores. No se encontró asociación entre NT, CT, y N hidrolizable con la cantidad de nitratos liberados en condiciones de campo y de laboratorio

Invertebrados edáficos em diferentes sistemas de uso do solo no Município de Quitandinha, PR.

Resumo. FERTBIO 2014

Priorización de áreas de intervención mediante análisis morfométrico e índice de vegetación

La caracterización morfométrica y el análisis del Índice de Vegetación de Diferencia Normalizada (NDVI) puede ser una estrategia en los programas de restauración hidrológica ambiental de cuencas, ya que la interrelación entre el área, forma, relieve, sistema de drenaje y los cambios de la cobertura vegetal causada por la alteración antropogénica permite hacer una priorización de subcuencas para su intervención con prácticas productivo-conservacionistas, a fin de reducir el crecimiento de los sistemas de drenaje en zonas con presencia de eventos meteorológicos extremos que causan deslaves y provocan inundaciones en las partes bajas de las cuencas. El estudio se realizó en la cuenca del río Huehuetán, ubicada en la región del Soconusco del estado de Chiapas, México, con el objetivo de estimar los parámetros morfométricos (lineales y de forma) de 16 subcuencas, así como el NDVI para los años 1993 y 2013, para priorizar los cambios en la cobertura vegetal que afectan la degradación del suelo de las subcuencas para la restauración hidrológica. La metodología permitió definir el orden de intervención de las subcuencas con prácticas de conservación del suelo, agua y obras de control de azolves, para reducir los procesos de erosión hídrica, el crecimiento del sistema de drenaje y la capacidad de transporte del flujo superficial en laderas y cauces

Ligand sensitivity of type-1 inositol 1,4,5-trisphosphate receptor is enhanced by the D2594K mutation.

Inositol 1,4,5-trisphosphate receptor (IP3R) and ryanodine receptor (RyR) are homologous cation channels that mediate release of Ca2+ from the endoplasmic/sarcoplasmic reticulum (ER/SR) and thereby are involved in many physiological processes. In previous studies, we determined that when the D2594 residue, located at or near the gate of the IP3R type 1, was replaced by lysine (D2594K), a gain of function was obtained. This mutant phenotype was characterized by increased IP3 sensitivity. We hypothesized the IP3R1-D2594 determines the ligand sensitivity of the channel by electrostatically affecting the stability of the closed and open states. To test this possibility, the relationship between the D2594 site and IP3R1 regulation by IP3, cytosolic, and luminal Ca2+ was determined at the cellular, subcellular, and single-channel levels using fluorescence Ca2+ imaging and single-channel reconstitution. We found that in cells, D2594K mutation enhances the IP3 ligand sensitivity. Single-channel IP3R1 studies revealed that the conductance of IP3R1-WT and -D2594K channels is similar. However, IP3R1-D2594K channels exhibit higher IP3 sensitivity, with substantially greater efficacy. In addition, like its wild type (WT) counterpart, IP3R1-D2594K showed a bell-shape cytosolic Ca2+-dependency, but D2594K had greater activity at each tested cytosolic free Ca2+ concentration. The IP3R1-D2594K also had altered luminal Ca2+ sensitivity. Unlike IP3R1-WT, D2594K channel activity did not decrease at low luminal Ca2+ levels. Taken together, our functional studies indicate that the substitution of a negatively charged residue by a positive one at the channels' pore cytosolic exit affects the channel's gating behavior thereby explaining the enhanced ligand-channel's sensitivity.The authors received the support of research grants from the National Institutes of Health grant/award numbers R01GM111397 to S. R. W. Chen, M. Fill, and J. Ramos‐Franco, R01HL057832 to M. Fill and by the Canadian Institutes of Health Research, grant/award number PJT‐173352. S. R. W. Chen holds the Heart and Stroke Foundation Chair in Cardiovascular Research (END611955). A. Tambeaux was supported by the Graduate College of Rush University Medical Center.S

Covariables Ambientales que Definen los Principales Grupos de Suelo en México

La variabilidad de los suelos depende de la interacción de covariables ambientales que intervienen en su formación. En México, se registran 25 grupos de suelo de los 32 que incluye la Base Referencial Mundial (BRM). Este estudio identifica el orden de importancia de 11 covariables ambientales, utilizando el modelo no paramétrico basado en un algoritmo de aprendizaje automático supervisado denominado random forest, el cual caracteriza 19 grupos de suelo que incluyen el 99.2% del territorio nacional. Las covariables que se incluyeron fueron, curvatura, densidad de drenaje, distancia al cauce más cercano, geología, índice de aridez, índice de humedad topográfica, índice de posición topográfica, índice de vegetación de diferencia normalizada (NDVI), radiación, rugosidad y temperatura. Los resultados mostraron un total de 100 árboles de clasificación, con una precisión global de 81.83% del modelo a través de random forest y un valor de Kappa de 0.80, expresado como muy bueno. La precisión de disminución promedio mostró que, las cinco covariables analizadas más importantes que clasifican los 19 grupos de suelo son, índice de posición topográfica, índice de aridez, curvatura, radiación y densidad de drenaje

Desarrollo, implementación y utilización de modelos para el procesamiento automático de textos

El libro recoge ponencias y talleres seleccionados de JALIMI 2005 (Jornadas Argentinas de Lingüística Informática: Modelización e Ingeniería), y está organizado en nueve capítulos y un apéndice. Si bien hay sustantivas diferencias en los enfoques, las metodologías, las propiedades específicas estudiadas y las aplicaciones propuestas o proyectadas, todos los capítulos comunican resultados de investigaciones que pretenden contribuir a alcanzar el objetivo a largo plazo de la Lingüística Informática, a saber: emular en términos cibernéticos la extraordinaria capacidad humana de producir y comprender textos en lengua natural