Detección cuantitativa de microorganismos resistentes a la tetraciclina en carne convencional y ecológica de ternera, cerdo y pollo

The use of antimicrobials has increased the number of resistant bacteria to these drugs; however, the organic production has restricted the use of these compounds. The objectives of this work were to assess counts of tetracycline-resistant bacteria using conventional microbiology, to compare these results with those obtained for tet(A) and tet(B) genes by qPCR and to investigate both genes in conventional and organic meat. Counts of mesophilic aerobic bacteria were higher in organic beef, while chicken meat obtained higher counts for Enterobacteriaceae. Only tet(B) was higher in conventional pork and chicken meat than in their organic counterparts. The tet(A) gene was found in almost 100% of samples and tet(B) gene changed according to the type of meat. The presence of tet genes suggests that they are widely distributed, especially tet(A), in food of animal origin, even in organic meat samples obtained from animals in which the use of antimicrobials is restrictedEl uso de los antimicrobianos ha incrementado sustancialmente el número de bacterias resistentes a estos fármacos sin embargo, la producción ecológica, ha limitado el uso de estos medicamentos. Los objetivos del trabajo fueron evaluar los recuentos obtenidos de bacterias resistentes a tetraciclina mediante microbiología convencional, obtener recuentos de bacterias con los genes tet(A) y tet(B)mediante qPCR e investigar la distribución de ambos genes en carne convencional y ecológica. Los recuentos de bacterias aerobias mesófilas fueron significativamente mayores en carne ecológica de ternera, mientras que los recuentos de Enterobacteriaceae fueron superiores en carne convencional de pollo. Sólo el gen tet(B) fue significativamente mayor en carne convencional de cerdo y de pollo que en sus homólogas ecológicas. El gen tet(A) se encontró en casi todas las muestras mientras que el tet(B) varió según la especie. La presencia de los genes tet sugiere que están ampliamente distribuidos, especialmente tet(A), en alimentos de origen animal, incluso en aquellos derivados de animales en los que el uso de antimicrobianos está seriamente restringidoThe authors are grateful to the Institute Pasteur for providing the E. coli BM13 (C600 RifR)/RP4 strain (tet(A)) and to the Health Protection Agency for providing the E. coli NCTC 50365 strain (tet(B)). Xunta de Galicia (project 09MRU010261PR) supported this work. We also thank Carmen Carreira and Rodrigo García for their technical supportS

Caracterización molecular de bacterias ácido-lácticas aisladas a partir de carne de ternera envasada al vacío de modo tradicional y mediante un sistema avanzado

A total of 91 lactic acid bacteria (LAB) were isolated from 50 beef samples, 25 packaged by traditional vacuum packaging and 25 packaged using advanced vacuum skin packaging. The isolated LAB were identified using 16S rRNA sequencing, whereas randomly amplified polymorphic DNA (RAPD-PCR) and cluster analysis were used for typing the LABs. Ten different species of LAB were identified and assigned to the following species: Enterococcus gilvus (22 isolates), Enterococcus faecium (9 isolates), Enterococcus casseliflavus (8 isolates), Enterococcus faecalis (4 isolates), Enterococcus malodoratus (3 isolates), Enterococcus devriessei (3 isolates), Lactobacillus sakei (15 isolates), Carnobacterium divergens (12 isolates), Carnobacterium maltaromaticum (5 isolates), and Leuconostoc mesenteroides (8 isolates). The RAPD profile bands observed were not significantly discriminatory, with exceptions of E. casseliflavus, E. faecalis, and E. faecium, which suggests that the type of packaging system used had no specific effect on the selection of most microbiota in the meat after packagingUn total de 91 bacterias ácido-lácticas (LAB) fueron aisladas a partir de 50 muestras de carne de ternera, de las cuales 25 fueron envasadas al vacío de modo tradicional y 25 fueron envasadas mediante un sistema de vacío avanzado. Los aislamientos fueron identificados a través de la secuenciación del ADN ribosomal 16S, mientras que la caracterización de las LAB se realizó mediante la amplificación al azar del ADN polimórfico (RAPD-PCR) y su posterior análisis cluster. Fueron identificadas cepas pertenecientes a diez especies bacterianas diferentes, en concreto: Enterococcus gilvus (22 aislamientos), E. faecium (9 aislamientos), E. casseliflavus (8 aislamientos), E. faecalis (4 aislamientos), E. malodoratus (3 aislamientos), E. devriessei (3 aislamientos), Lactobacillus sakei (15 aislamientos), Carnobacterium divergens (12 aislamientos), C. maltaromaticum (5 aislamientos) y Leuconostoc mesenteroides (8 aislamientos). Los perfiles de bandas de ADN obtenidas no revelaron diferencias significativas, con las excepciones de E. casseliflavus, E. faecalis y E. faecium, sugiriendo que el tipo de envasado no tiene un efecto específico en la selección de la mayor parte de la microbiota presente en la carne envasadaS

Analysis of Tetracyclines in Medicated Feed for Food Animal Production by HPLC-MS/MS

The use of medicated feed is a common practice in animal food production to improve animal health. Tetracyclines and β-Lactams are the groups that are most frequently added to this type of feed. The measurement of the concentration of the analytes in these types of samples is sometimes due to the matrix characteristic, and manufacturers are demanding fast, precise and reproducible methods. A rapid confirmatory method based on a simple extraction protocol using acidified methanol and followed by high performance liquid chromatography coupled to a tandem mass spectrometer for the quantification of four tetracyclines in feed is presented. Validation was performed following the guidelines of Decision 2002/657/EC. Results indicated that the four tetracyclines can be identified and quantified in a concentration range between 50 and 500 mg/kg with recoveries between 84% and 109% and RSD for precision under reproducible conditions between 12% and 16%. Satisfactory results were also obtained with interlaboratory studies and by comparing the method with an HPLC-Fluorescent methodThe authors wish to thank the Consellería de Cultura, Educación e Ordenacion Universitaria, Xunta de Galicia (project EM 2012/153) for financial supportS

Determination of the Presence of Three Antimicrobials in Surface Water Collected from Urban and Rural Areas

Due to the continuous release of antimicrobials into the environment, the aim of this study was to compare the frequency of detection of sulfamethazine, sulfamethoxypyridazine and trimethoprim in surface water collected from urban and rural areas in Northwestern Spain. A monitoring study was conducted with 314 river water samples analyzed by high-performance liquid chromatography coupled to tandem mass spectrometry. The results indicated that 37% of the samples contained residues of at least one of the investigated antimicrobials, and every sampling site yielded positive samples. At sites located near the discharge points of wastewater treatment plants and near the collection point of a drinking-water treatment plant, more than 6% of the samples were positive for the presence of antimicrobial residuesThe authors wish to thank the Fondo Europeo Agrícola de Desarrollo Rural (FEADER) and the Consellería de Medio Rural for funding this study through the Project FMR331AS

Influencia del ciclo de cultivo y la conservación frigorífica en el color de la coliflor

La coliflor es un cultivo en aumento en la Región de Murcia, provocado principalmente por el incremento de su producción destinada a la exportación. Para mantener dicha cuota de exportación es necesaria la producción de una coliflor de gran calidad, requisito que cada vez más, aprecian los mercados nacionales. Esta calidad se basa fundamentalmente en su aspecto externo, donde el color de la pella es uno de los parámetros más importantes a tener en cuenta.Este trabajo ha sido financiando por el proyecto Séneca AGR/9/FS/9

Learning Physics with Wolfram Alpha

We believe we are at the beginning of a new Big Bang. This great explosion places us at the dawn of a new era in learning Physics, and we would like to participate in this fascinating process. Mobile devices are exponentially growing amongst our students, so we are convinced that they must be used to promote active learning. In this work, we will focus on several apps from Wolfram Research Company: Wolfram Alpha, Wolfram Alpha Viewer, Physics I and Physics II. All of them have many possibilities to achieve an autonomous and active learning. These apps allow users to select different options from a specific menu, enter values of the required parameters and the app calculates by itself the magnitude involved in the process. In addition, these apps also allow us to study the major laws of Physics, to look for the different units of the International System of Units or even to manage the most common physical constants. We are convinced that there is a necessity of developing more applications for smartphones that will empower a meaningful learning of Physics using apps for the operating systems iOS, Android, Windows Phone and those that arise in the future. This opportunity, which is provided to us by the new technologies, cannot be unexploited. We must strongly engage into this topic to achieve a meaningful learning.AB thanks the “Generalitat Valenciana” of Spain (project PROMETEOII/2015/015) and the "Vicerrectorado de Tecnologías de la Información" of the University of Alicante, Spain (project GITE-09006-UA)

Clasificación preliminar de especies de jardín según sus requerimientos hídricos en la región de Murcia

El desarrollo económico y social de la Región de Murcia ha conllevado desde la década de los 80 un considerable aumento de la superficie ajardinada, tanto de carácter público como privado. Esta circunstancia, unida a los graves problemas de escasez de agua, pone de manifiesto la importancia del establecimiento de jardines de bajo consumo hídrico.Este trabajo forma parte del proyecto de investigación regional PR02-03-2 financiado por la Dirección General de Investigación y Transferencia Tecnológica

Tuning melatonin receptor subtype selectivity in oxadiazolone-based analogues: Discovery of QR2 ligands and NRF2 activators with neurogenic properties

New multi-target indole and naphthalene derivatives containing the oxadiazolone scaffold as a bioisostere of the melatonin acetamido group have been developed. The novel compounds were characterized at melatonin receptors MT1R and MT2R, quinone reductase 2 (QR2), lipoxygenase-5 (LOX-5), and monoamine oxidases (MAO-A and MAO-B), and also as radical scavengers. We found that selectivity within the oxadiazolone series can be modulated by modifying the side chain functionality and coplanarity with the indole or naphthalene ring. In phenotypic assays, several oxadiazolone-based derivatives induced signalling mediated by the transcription factor NRF2 and promoted the maturation of neural stem-cells into a neuronal phenotype. Activation of NRF2 could be due to the binding of indole derivatives to KEAP1, as deduced from surface plasmon resonance (SPR) experiments. Molecular modelling studies using the crystal structures of QR2 and the KEAP1 Kelch-domain, as well as the recently described X-ray free-electron laser (XFEL) structures of chimeric MT1R and MT2R, provided a rationale for the experimental data and afforded valuable insights for future drug design endeavoursThe authors gratefully acknowledge the following financial supports: Spanish Ministry of Science, Innovation and Universities; Spanish Research Agency; and European Regional Development Funds (grants RTI2018-093955-B-C21 and SAF2015-64948-C2-1-R to M.I.R.-F.; RTI2018-095793-B-I00 to M.G.L., SAF2015-64629-C2- 2-R to F.G.), General Council for Research and Innovation of the Community of Madrid and European Structural Funds (grant B2017/BMD-3827 e NRF24ADCM), Health Institute Carlos III (Miguel Servet II ProgramCP16/00014 and grant PI17/01700 to R.L.). CH-A and P.M. thank their PhD fellowships from Spanish Ministry of Education (MEC, PhD grant FPU16/01704 and mobility grant FPUEST17/00233 to CH-A and FPU13/03737 to P.M.)

A conceptual map about alternating current circuits

Teachers are deeply concerned on how to be more effective in our task of teaching. We must organize the contents of our specific area providing them with a logical configuration, for which we must know the mental structure of the students that we have in the classroom. We must shape this mental structure, in a progressive manner, so that they can assimilate the contents that we are trying to transfer, to make the learning as meaningful as possible. In the generative learning model, the links before the stimulus delivered by the teacher and the information stored in the mind of the learner requires an important effort by the student, who should build new conceptual meanings. That effort, which is extremely necessary for a good learning, sometimes is the missing ingredient so that the teaching-learning process can be properly assimilated. In electrical circuits, which we know are perfectly controlled and described by Ohm's law and Kirchhoff's two rules, there are two concepts that correspond to the following physical quantities: voltage and electrical resistance. These two concepts are integrated and linked when the concept of current is presented. This concept is not subordinated to the previous ones, it has the same degree of inclusiveness and gives rise to substantial relations between the three concepts, materializing it into a law: The Ohm, which allows us to relate and to calculate any of the three physical magnitudes, two of them known. The alternate current, in which both the voltage and the current are reversed dozens of times per second, plays an important role in many aspects of our modern life, because it is universally used. Its main feature is that its maximum voltage is easily modifiable through the use of transformers, which greatly facilitates its transfer with very few losses. In this paper, we present a conceptual map so that it is used as a new tool to analyze in a logical manner the underlying structure in the alternate current circuits, with the objective of providing the students from Sciences and Engineering majors with another option to try, amongst all, to achieve a significant learning of this important part of physics.AB thanks the “Generalitat Valenciana” of Spain (project PROMETEOII/2015/015) and the "Vicerrectorado de Tecnologías de la Información" of the University of Alicante, Spain (project GITE-09006-UA)