Modelado de las curvas de supervivencia de E.Coli en bebidas refrescantes y en preparados lácteos (modelo Baranyi)

E. coli O157:H7 es un microorganismo perteneciente a la familia Enterobacteriaceae. Forma parte de la flora normal del intestino del hombre y de los animales de sangre caliente; está implicada en una serie de enfermedades transmitidas por los alimentos, causando brotes de colitis hemorrágica y síndrome urémico hemolítico. Entre los alimentos implicados se incluyen carnes elaboradas y cocidas de manera insuficiente, frutas y hortalizas crudas, productos lácteos y zumos de frutas no pasteurizados. Se ha aplicado el modelo matemático de Baranyi y Roberts (1994) para la estimación de los parámetros de supervivencia de Escherichia coli no patógeno CECT 516 (EC) y Escherichia coli O157:H7 CECT 4076 y CECT 4267 (ECO) en Bebidas refrescantes comerciales y Preparados lácteos comerciales pasteurizados a 4 y 20ºC. El modelo permite estimar el tiempo de latencia, la velocidad máxima de decrecimiento y la población final. A 20ºC el tiempo necesario en no detectarse células viables fue de 3-5 días en el caso de las Bebidas refrescantes tipo A y B, y de 6-17 días en el caso de los Preparados lácteos tipo A y B. A 4ºC el tiempo necesario fue de 7 días en el caso de las Bebidas refrescantes tipo A y B y de 11- 24 días en el caso de los Preparados lácteos Tipo A y B. El tiempo necesario para no detectarse células viables es menor a 20ºC que a 4ºC; a su vez es menor en las Bebidas refrescantes que en los Preparados lácteos. Dentro de los distintos tipos de Bebidas refrescantes y Preparados lácteos la inactivación del microorganismo es más rápida en los Tipo A que en los Tipo B. En los Preparados lácteos el tiempo en inactivar EC fue menor que en inactivar ECO mientras que en las Bebidas refrescantes no hubo diferencias significativas en el tiempo empleadoGrado en Nutrición Humana y Dietétic

Biogeographical patterns of species richness, range size and phylogenetic diversity of ferns along elevational-latitudinal gradients in the tropics and its transition zone

Although elevational-latitudinal patterns of plant and animal diversity have been studied for centuries, factors driving the observed patterns are still controversially discussed. Tropical mountains offer an excellent natural experiment to unravel these drivers of biogeographical patterns and the integration of multiple elevational gradients along an extended latitudinal gradient is an outstanding opportunity to decipher underlying mechanism of large-scale patterns of species richness. In this research the data obtained from Mexico were unified with elevational transects in America spanning 0° to 23°N degrees of latitude, mostly between sea level and mountain tops (200-4000 m a.s.l.). Hereby, the latitudinal gradient covered by this investigation runs from most studied tropics through the transition zone of sub-tropical regions in order to integrate increasingly seasonal and dry climates, which are known to limit the diversity of ferns as humidity-dependent organisms. How the fern and lycophytes (hereafter ferns) richness and species range size patterns change along elevational-latitudinal gradients is poorly explored, as well as the phylogenetic relationships within species assemblages. The objective of this research was to describe such patterns and understand the broad scale distribution of other important components of biodiversity as the phylogenetic diversity and associated metrics, using a standardized methodology that allows the comparison of elevational transects. In order to assess these patterns, I first intensively sampled an elevational gradient in the Sierra de Juárez, Oaxaca, Mexico, known as the “ferns hunter paradise”, a hotspot of biodiversity in a hyperhumid tropical region. Following the uniform sampling protocol of the working group around Michael Kessler (Zurich) and Jürgen Kluge (Marburg), I sampled at each elevation four to eight plots of 20 x 20 m (400m2) and analyzed changes in fern assemblages along this elevational gradient. The plots were established in natural zonal forest, avoiding special structural features and disturbed areas whenever possible. In each plot, DNA samples were taken and all fern species and their abundances were recorded for terrestrials and epiphytes. The results are presented in a series of chapters starting from the analyses of the gradient in Mexico, followed by the central work of this research, where richness and range size patterns of eight elevational transects in Mexico were analyzed together with climatic correlates, and the assessment of the historical component (phylogenetics) of 11 elevational gradients understanding the processes that governs the species richness. In the following the central questions and results of the three studies will be briefly described. In Chapter 2 we analyzed in detail one of the most diverse elevational transect in Mexico with 15 elevational steps in Sierra de Juárez Oaxaca, a hotspot of biodiversity, comparing the richness patterns with central and South America. In 121 plots we found 195 fern species, with the highest species numbers recorded at mid-elevations (1,100–2,200 m) and lower richness at both gradient extremes. This hump-shaped pattern was mainly driven by epiphytes, which contributed about 40% to the total species richness. This species group had wider elevational ranges than terrestrial species, which contributed 38% to the total richness (20 % were recorded within both life forms), and were more or less constant at low to mid elevations about 2,500 m, followed by a gradual decline. Overall, richness per plot was low compared to other elevational gradients within the tropics closer to the Equator. This decline of species richness towards the subtropics and temperate regions appears to be rather abrupt within Central America, but additional data are needed to close the remaining gap of knowledge between Costa Rica and Mexico. This work has been published 2018 in the American Fern Journal (Hernández-Rojas et al. 2018). In the central work of this research (Chapter 3), we assessed the richness and range size patterns of ferns and lycophytes along seven elevational gradients (with in total 658 plots) at different latitudes and searched for predictors of range size from a set of environmental factors. We calculated the latitudinal range using the northern and southern limits of each species and averaged the latitudinal range of all species within assemblages weighted by their abundances. We related climatic factors and the changes with latitude and elevation with range size using linear mixed-effects models. Species richness per plot increased with elevation up to about 1,500-2,000 m, with strong differences in overall species richness between transects and a reduction with increasing latitude. The mean weighted range size of species within assemblages declined with elevation, and increased with latitude. However, we also found marked differences between the Atlantic and Pacific slopes of Mexico, as well as low range size in humid regions. The best models described about 76%–80% of the variability in range size and included the seasonality of both temperature and precipitation, and annual cloud cover. As a conclusion, latitudinal and elevational patterns of range size in fern assemblages are driven by an interplay of factors favoring wide-ranging species (higher latitudes with increasing temperature seasonality and dryer habitat conditions) and those favoring species with restricted ranges (higher elevations with more humid habitat conditions), with additional variation introduced by the specific conditions of individual mountain ranges. Climatically stable, humid habitats apparently provide favorable conditions for small-ranged fern species, and should accordingly be given high priority in regional conservation planning. This work was published 2020 in the Journal of Biogeography (Hernández-Rojas et al. 2020). Finally, phylogenetic approaches should be seen as an integral component of studies of the causal basis of community structure, which permits the understanding of how communities have evolved through time, and a deeper understanding of biogeographical processes. This historical aspect is included as the final part of this research (Chapter 4) that was aimed to unfold the complex changes in the phylogenetic structure along elevation (200-4000 m.a.s.l.) and latitude (0°-23° N). We compiled a comprehensive data set including eleven elevational transects (more than 900 spp. and 868 plots), closing the gap of information observed in Chapter 2. At this point I should highlight the relevance of this research as a product of the work of many researchers that I have the honor to synthesize to get a complete view of biogeographic and phylogenetic patterns. One of the major tasks before analyzing the data was to compile the phylogenetic information of the more than 900 species, of which only 70 % were already present in the most recent dissolved phylogenetic tree, and the remaining 30 % species had to be added on the basis of putative closest relatives due to exhaustive examination of morphological characteristics and expert knowledge. Our results showed that latitude and elevation per se are weak explanatory variables for phylogenetic diversity, but incorporating climatic variables clearly enhance the explanatory power of the models. We used different phylogenetic measures in order to capture different aspects of evolutionary history of this plant group and were thus able to understand, how species groups have evolved to currently form the observed gradients in Central America. Overall, the phylogenetic diversity decreased with increased latitude and elevation, as could be observed by increasingly clustering of closely related species. Additionally, it is worthwhile to look at taxonomic group of ferns separately for the main lifeforms, as they are not only ecologically different, but also not congruent in their evolutionary history. Epiphytic phylogenetic diversity had a positive relationship with humidity, while the phylogenetic diversity of terrestrial was determined by temperature. The general pattern of phylogenetic diversity is mainly driven for the suppression of the old, basal tropical, terrestrial lineages rather than by recent evolutionary history and better explained by climatic variables. This work was submitted to frontiers of biogeography. In continuation of this work and as an outlook to further studies, I am heading for to continue the research in tropical areas, where the deforestation and disturbance, respectively, and general human activities play a central role, which are impacting tremendously the legacy of millions of years of evolution. In the context of the species richness patterns, it is necessary to fill the gaps of knowledge present in America. In this regard, I will intend t

Molecular characterisation of Sardina pilchards larvae diet in Málaga Bay (SW Mediterranean Sea)

The study of predation in the early life stages of fish by direct observation of their stomach content is very difficult, mostly because prey lose all identifiable characteristics. We developed a multiplex-PCR based method, which detected within the gut of the larvae the presence/absence of the five main species of copepods that live in Malaga Bay: Clausocalanus parapergens, Oncaea waldemari, Paracalanus indicus, Temora stylifera and Acartia clausi. A set of five species-specific primers were designed and combined in a single multiplex PCR system, which allowed a time and cost effective screening of the samples. The method detected as little as 0.09 ng/μL of copepod DNA without cross-reactions with Sardina pilchardus DNA

Profesionalización de los servidores públicos municipales, frente a la alternancia política, caso: Chalco, Estado de México 2003, 2006 y 2009

La administración pública debe tener como una de sus principales vertientes la profesionalización de los servidores públicos, esto se ha convertido en la actualidad en un asunto de la agenda político administrativa mexicana, tanto en el ámbito federal, estatal como local, puesto que es un componente de la democracia gubernativa, pues al tener efectos como ineficiencia y baja calidad, tiene como consecuencias dificultades en la toma de decisiones públicas del gobierno en sus tres órdenes. El 10 de abril del 2003, se aprobó y firmó en el ámbito federal la Ley del Servicio Profesional de Carrera de la Administración Pública Federal,1 como un instrumento de estabilización para el manejo del aparato administrativo y reconstrucción de la confianza del gobierno democrático, tener una calidad institucional y regular relaciones entre los poderes públicos, niveles de gobierno y los ciudadanos. En México y principalmente en sus municipios, no existe una preparación de los servidores públicos, capacidad administrativa y gobiernos de calidad. El principal obstáculo es la politización que existe dentro de la administración pública municipal, caracterizado por un alto grado de afiliación partidista, compadrazgo, clientelismo, corporativismo, amiguismo, lealtades y nepotismo, por una ausencia de mecanismos que permita el reconocimiento, ascenso y “premio” al funcionario público