A metaphylactic treatment with double dose oxytetracycline reduces the risk of bovine respiratory disease in feedlot calves

El objetivo del presente estudio fue evaluar el efecto del tratamiento metafiláctico con oxitetraciclina (OTC), a simple y doble dosis, en bovinos con alto riesgo de padecer enfermedad respiratoria bovina (ERB). El estudio se realizó en un establecimiento de engorde a corral donde se utilizaron 2.754 terneros que fueron considerados de alto riesgo de padecer ERB. Se utilizó un diseño en bloque completamente al azar donde se consideró al animal como la unidad experimental y el corral (n=10) como bloque. Se formaron tres grupos experimentales: 1- control (CTL) el cual permaneció sin tratamiento, 2- recibió OTC 20 mg/kg SC (OTC20) y 3- recibió OTC 40 mg/kg SC (OTC40). El riesgo de ERB fue evaluado a través de una regresión logística. Los animales del grupo CTL tuvieron 2,85 y 7,14 veces más chances de enfermarse de ERB que los animales de los grupos OTC20 y OTC40 respectivamente (

Ribosomal selection of mRNAs with degenerate initiation triplets

To assess the influence of degenerate initiation triplets on mRNA recruitment by ribosomes, five mRNAs identical but for their start codon (AUG, GUG, UUG, AUU and AUA) were offered to a limiting amount of ribosomes, alone or in competition with an identical AUGmRNA bearing a mutation conferring different electrophoretic mobility to the product. Translational efficiency and competitiveness of test mRNAs toward this AUGmRNA were determined quantifying the relative amounts of the electrophoretically separated wt and mutated products synthesized in vitro and found to be influenced to different extents by the nature of their initiation triplet and by parameters such as temperature and nutrient availability in the medium. The behaviors of AUAmRNA, UUGmRNA and AUGmRNA were the same between 20 and 40°C whereas the GUG and AUUmRNAs were less active and competed poorly with the AUGmRNA, especially at low temperature. Nutrient limitation and preferential inhibition by ppGpp severely affected activity and competitiveness of all mRNAs bearing non-AUG starts, the UUGmRNA being the least affected. Overall, our data indicate that beyond these effects exclusively due to the degenerate start codons within an optimized translational initiation region, an important role is played by the context in which the rare start codons are present

Role of the ribosome‐associated protein PY in the cold‐shock response of E scherichia coli

Protein Y ( PY ) is an E scherichia coli cold‐shock protein which has been proposed to be responsible for the repression of bulk protein synthesis during cold adaptation. Here, we present in vivo and in vitro data which clarify the role of PY and its mechanism of action. Deletion of yfiA , the gene encoding protein PY , demonstrates that this protein is dispensable for cold adaptation and is not responsible for the shutdown of bulk protein synthesis at the onset of the stress, although it is able to partially inhibit translation. In vitro assays reveal that the extent of PY inhibition changes with different mRNA s and that this inhibition is related to the capacity of PY of binding 30S subunits with a fairly strong association constant, thus stimulating the formation of 70S monomers. Furthermore, our data provide evidence that PY competes with the other ribosomal ligands for the binding to the 30S subunits. Overall these results suggest an alternative model to explain PY function during cold shock and to reconcile the inhibition caused by PY with the active translation observed for some mRNA s during cold shock. E scherichia coli responds to cold stress by entering an acclimation phase during which protein synthesis slows down considerably with the exception of a specific set of genes (cold‐shock genes) whose expression is stimulated. In this article, we have investigated in vivo and in vitro the role of PY , a protein that is associated with the ribosome throughout the cold acclimation phase. Our data indicate that protein PY can affect translation initiation but is not responsible for turning off bulk protein synthesis during the cold stress.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97494/1/mbo368-sup-0001-FigureS1-S3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97494/2/mbo368.pd

Espectrofotometría infrarroja transformada de Fourier para identificar bacterias uterinas patógenas en vacas lecheras

El objetivo del trabajo fue determinar el grado de acuerdo entre dos métodos de identificación bacteriana, marcha bacteriológica convencional y espectroscopía infrarroja transformada de Fourier (TF-IR), así como determinar si la base de datos construida a partir de bacterias aisladas de úteros de vaca lecheras de Europa podía ser utilizada para identificar bacterias uterinas de vacas lecheras de Argentina. Las muestras bacteriológicas fueron tomadas a vacas post parto (n=64) con distinto grado de descarga vaginal (DV). Inicialmente se efectuó diagnostico bacteriológico por marcha bacteriológica convencional (n=27) y posteriormente por TF-IR. El grado de acuerdo entre ambos métodos de identificación bacteriana fue determinado por el coeficiente kappa y el efecto de la DV sobre el aislamiento de Escherichia coli y Trueperella pyogenes fue analizado por regresión logística. El grado de acuerdo entre ambos métodos tuvo un coeficiente kappa de 0,73 (p<0,001). La probabilidad de aislamiento bacteriano (E. coli y T. pyogenes) tendió a incrementarse junto con el grado de DV (p=0,06), siendo 1,88 veces más alta la probabilidad de encontrar un resultado positivo a E. coli o T. pyogenes en vacas con DV fétida que en vacas con DV normal. En conclusión, TF-IR reveló un buen grado de acuerdo con la marcha  acteriológica convencional. Por otro lado, la base de datos producida a partir de bacterias uterinas de vacas lecheras de Europa pudo ser utilizada para la identificación de bacterias uterinas de vacas lecheras de Argentina

Small-Group Learning in an Upper-Level University Biology Class Enhances Academic Performance and Student Attitudes Toward Group Work

To improve science learning, science educators' teaching tools need to address two major criteria: teaching practice should mirror our current understanding of the learning process; and science teaching should reflect scientific practice. We designed a small-group learning (SGL) model for a fourth year university neurobiology course using these criteria and studied student achievement and attitude in five course sections encompassing the transition from individual work-based to SGL course design. All students completed daily quizzes/assignments involving analysis of scientific data and the development of scientific models. Students in individual work-based (Individualistic) sections usually worked independently on these assignments, whereas SGL students completed assignments in permanent groups of six. SGL students had significantly higher final exam grades than Individualistic students. The transition to the SGL model was marked by a notable increase in 10th percentile exam grade (Individualistic: 47.5%; Initial SGL: 60%; Refined SGL: 65%), suggesting SGL enhanced achievement among the least prepared students. We also studied student achievement on paired quizzes: quizzes were first completed individually and submitted, and then completed as a group and submitted. The group quiz grade was higher than the individual quiz grade of the highest achiever in each group over the term. All students – even term high achievers –could benefit from the SGL environment. Additionally, entrance and exit surveys demonstrated student attitudes toward SGL were more positive at the end of the Refined SGL course. We assert that SGL is uniquely-positioned to promote effective learning in the science classroom

A novel DSP zebrafish model reveals training- and drug-induced modulation of arrhythmogenic cardiomyopathy phenotypes

Arrhythmogenic cardiomyopathy (AC) is an inherited disorder characterized by progressive loss of the ventricular myocardium causing life-threatening ventricular arrhythmias, syncope and sudden cardiac death in young and athletes. About 40% of AC cases carry one or more mutations in genes encoding for desmosomal proteins, including Desmoplakin (Dsp). We present here the first stable Dsp knock-out (KO) zebrafish line able to model cardiac alterations and cell signalling dysregulation, characteristic of the AC disease, on which environmental factors and candidate drugs can be tested. Our stable Dsp knock-out (KO) zebrafish line was characterized by cardiac alterations, oedema and bradycardia at larval stages. Histological analysis of mutated adult hearts showed reduced contractile structures and abnormal shape of the ventricle, with thinning of the myocardial layer, vessels dilation and presence of adipocytes within the myocardium. Moreover, TEM analysis revealed “pale”, disorganized and delocalized desmosomes. Intensive physical training protocol caused a global worsening of the cardiac phenotype, accelerating the progression of the disease. Of note, we detected a decrease of Wnt/β-catenin signalling, recently associated with AC pathogenesis, as well as Hippo/YAP-TAZ and TGF-β pathway dysregulation. Pharmacological treatment of mutated larvae with SB216763, a Wnt/β-catenin agonist, rescued pathway expression and cardiac abnormalities, stabilizing the heart rhythm. Overall, our Dsp KO zebrafish line recapitulates many AC features observed in human patients, pointing at zebrafish as a suitable system for in vivo analysis of environmental modulators, such as the physical exercise, and the screening of pathway-targeted drugs, especially related to the Wnt/β-catenin signalling cascade

The porin and the permeating antibiotic: A selective diffusion barrier in gram-negative bacteria

Gram-negative bacteria are responsible for a large proportion of antibiotic resistant bacterial diseases. These bacteria have a complex cell envelope that comprises an outer membrane and an inner membrane that delimit the periplasm. The outer membrane contains various protein channels, called porins, which are involved in the influx of various compounds, including several classes of antibiotics. Bacterial adaptation to reduce influx through porins is an increasing problem worldwide that contributes, together with efflux systems, to the emergence and dissemination of antibiotic resistance. An exciting challenge is to decipher the genetic and molecular basis of membrane impermeability as a bacterial resistance mechanism. This Review outlines the bacterial response towards antibiotic stress on altered membrane permeability and discusses recent advances in molecular approaches that are improving our knowledge of the physico-chemical parameters that govern the translocation of antibiotics through porin channel

Rfam: Wikipedia, clans and the “decimal” release

The Rfam database aims to catalogue non-coding RNAs through the use of sequence alignments and statistical profile models known as covariance models. In this contribution, we discuss the pros and cons of using the online encyclopedia, Wikipedia, as a source of community‐derived annotation. We discuss the addition of groupings of related RNA families into clans and new developments to the website. Rfam is available on the Web at http://rfam.sanger.ac.uk