3,544 research outputs found
The Radio Jet Associated with the Multiple V380 Ori System
The giant Herbig-Haro object 222 extends over 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
Insulin secretion in health and disease: nutrients dictate the pace.
Insulin is a key hormone controlling metabolic homeostasis. Loss or dysfunction of pancreatic β-cells lead to the release of insufficient insulin to cover the organism needs, promoting diabetes development. Since dietary nutrients influence the activity of β-cells, their inadequate intake, absorption and/or utilisation can be detrimental. This review will highlight the physiological and pathological effects of nutrients on insulin secretion and discuss the underlying mechanisms. Glucose uptake and metabolism in β-cells trigger insulin secretion. This effect of glucose is potentiated by amino acids and fatty acids, as well as by entero-endocrine hormones and neuropeptides released by the digestive tract in response to nutrients. Glucose controls also basal and compensatory β-cell proliferation and, along with fatty acids, regulates insulin biosynthesis. If in the short-term nutrients promote β-cell activities, chronic exposure to nutrients can be detrimental to β-cells and causes reduced insulin transcription, increased basal secretion and impaired insulin release in response to stimulatory glucose concentrations, with a consequent increase in diabetes risk. Likewise, suboptimal early-life nutrition (e.g. parental high-fat or low-protein diet) causes altered β-cell mass and function in adulthood. The mechanisms mediating nutrient-induced β-cell dysfunction include transcriptional, post-transcriptional and translational modifications of genes involved in insulin biosynthesis and secretion, carbohydrate and lipid metabolism, cell differentiation, proliferation and survival. Altered expression of these genes is partly caused by changes in non-coding RNA transcripts induced by unbalanced nutrient uptake. A better understanding of the mechanisms leading to β-cell dysfunction will be critical to improve treatment and find a cure for diabetes
Postnatal β-cell maturation is associated with islet-specific microRNA changes induced by nutrient shifts at weaning.
Glucose-induced insulin secretion is an essential function of pancreatic β-cells that is partially lost in individuals affected by Type 2 diabetes. This unique property of β-cells is acquired through a poorly understood postnatal maturation process involving major modifications in gene expression programs. Here we show that β-cell maturation is associated with changes in microRNA expression induced by the nutritional transition that occurs at weaning. When mimicked in newborn islet cells, modifications in the level of specific microRNAs result in a switch in the expression of metabolic enzymes and cause the acquisition of glucose-induced insulin release. Our data suggest microRNAs have a central role in postnatal β-cell maturation and in the determination of adult functional β-cell mass. A better understanding of the events governing β-cell maturation may help understand why some individuals are predisposed to developing diabetes and could lead to new strategies for the treatment of this common metabolic disease
Assessment of the diagnostic accuracy of bacteriological culture and the invA-gen-based PCR for the detection of Salmonella organisms from caecal content from slaughtered pigs through Bayesian approaches
The goal of this study was to determine the accuracy of a culture technique and the invA-gen-based PCR, for the detection of Salmonella spp. From caecal samples from slaughtered pigs. For this purpose a Bayesian approach was used. Two hundred and three pigs were used. Animals were grouped into 2 populations: 96 from small farms and 107 from large farms. Sensitivity was 56% (95% Credible Interval: 40-76) for culture and 91% (95% CI: 81-97) for PCR
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
BIOLOGÍA DE Carcelia reclinata Robineau Desvoidy (DIPTERA: TACHINIDAE) EN CONDICIONES DE LABORATORIO
En México se ha estudiado poco acerca de temas relacionados con la utilización de insectos parasitoides para el control biológico. La mayoría de las investigaciones están enfocadas a hymenópteros, principalmente de la superfamilia Grammatoidea, y se ha dejado de lado a los demás organismos con gran potencial para el control de plagas agrícolas. La familia Tachinidae es de las más grandes del orden Diptera. Los catálogos recientes registran en total 8,200 especies para todas las regiones zoogeográficas. La mayoría de sus miembros presentan hábitos de parasitismo y, casi sin excepción, en su estado larval son endoparásitos de otros insectos, principalmente de los órdenes Lepidoptera y Coleoptera. A la fecha se ha trabajado sólo en el extranjero con especies mexicanas y no existen datos bibliográficos de estudios realizados en nuestro país al respecto. El taquínido Carcelia reclinata (Robinueau Desvoidy) es un parasitoide polífago de Estigmene acraea (Drury) y otros lepidópteros defoliadores. El propósito de este trabajo fue describir cada uno de sus estados biológicos y desarrollar su ciclo biológico
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Comparison of five different RNA sources to examine the lactating bovine mammary gland transcriptome using RNA-Sequencing.
The objective of this study was to examine five different sources of RNA, namely mammary gland tissue (MGT), milk somatic cells (SC), laser microdissected mammary epithelial cells (LCMEC), milk fat globules (MFG) and antibody-captured milk mammary epithelial cells (mMEC) to analyze the bovine mammary gland transcriptome using RNA-Sequencing. Our results provide a comparison between different sampling methods (invasive and non-invasive) to define the transcriptome of mammary gland tissue and milk cells. This information will be of value to investigators in choosing the most appropriate sampling method for different research applications to study specific physiological states during lactation. One of the simplest procedures to study the transcriptome associated with milk appears to be the isolation of total RNA directly from SC or MFG released into milk during lactation. Our results indicate that the SC and MFG transcriptome are representative of MGT and LCMEC and can be used as effective and alternative samples to study mammary gland expression without the need to perform a tissue biopsy
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