Diversity across Seasons of Culturable Pseudomonas from a Desiccation Lagoon in Cuatro Cienegas, Mexico.

Cuatro Cienegas basin (CCB) is a biodiversity reservoir within the Chihuahuan desert that includes several water systems subject to marked seasonality. While several studies have focused on biodiversity inventories, this is the first study that describes seasonal changes in diversity within the basin. We sampled Pseudomonas populations from a seasonally variable water system at four different sampling dates (August 2003, January 2004, January 2005, and August 2005). A total of 70 Pseudomonas isolates across seasons were obtained, genotyped by fingerprinting (BOX-PCR), and taxonomically characterized by 16S rDNA sequencing. We found 35 unique genotypes, and two numerically dominant lineages (16S rDNA sequences) that made up 64% of the sample: P. cuatrocienegasensis and P. otitidis. We did not recover genotypes across seasons, but lineages reoccurred across seasons; P. cuatrocienegasensis was isolated exclusively in winter, while P. otitidis was only recovered in summer. We statistically show that taxonomic identity of isolates is not independent of the sampling season, and that winter and summer populations are different. In addition to the genetic description of populations, we show exploratory measures of growth rates at different temperatures, suggesting physiological differences between populations. Altogether, the results indicate seasonal changes in diversity of free-living aquatic Pseudomonas populations from CCB

Ecological perspectives on synthetic biology: insights from microbial population biology

The metabolic capabilities of microbes are the basis for many major biotechnological advances, exploiting microbial diversity by selection or engineering of single strains. However, there are limits to the advances that can be achieved with single strains, and attention has turned toward the metabolic potential of consortia and the field of synthetic ecology. The main challenge for the synthetic ecology is that consortia are frequently unstable, largely because evolution by constituent members affects their interactions, which are the basis of collective metabolic functionality. Current practices in modeling consortia largely consider interactions as fixed circuits of chemical reactions, which greatly increases their tractability. This simplification comes at the cost of essential biological realism, stripping out the ecological context in which the metabolic actions occur and the potential for evolutionary change. In other words, evolutionary stability is not engineered into the system. This realization highlights the necessity to better identify the key components that influence the stable coexistence of microorganisms. Inclusion of ecological and evolutionary principles, in addition to biophysical variables and stoichiometric modeling of metabolism, is critical for microbial consortia design. This review aims to bring ecological and evolutionary concepts to the discussion on the stability of microbial consortia. In particular, we focus on the combined effect of spatial structure (connectivity of molecules and cells within the system) and ecological interactions (reciprocal and non-reciprocal) on the persistence of microbial consortia. We discuss exemplary cases to illustrate these ideas from published studies in evolutionary biology and biotechnology. We conclude by making clear the relevance of incorporating evolutionary and ecological principles to the design of microbial consortia, as a way of achieving evolutionarily stable and sustainable systems

Tissue Localization and Extracellular Matrix Degradation by PI, PII and PIII Snake Venom Metalloproteinases: Clues on the Mechanisms of Venom-Induced Hemorrhage

20 páginas, 4 figuras, 3 tablas y 7 tablas en material suplementario.Snake venom hemorrhagic metalloproteinases (SVMPs) of the PI, PII and PIII classes were compared in terms of tissue localization and their ability to hydrolyze basement membrane components in vivo, as well as by a proteomics analysis of exudates collected in tissue injected with these enzymes. Immunohistochemical analyses of co-localization of these SVMPs with type IV collagen revealed that PII and PIII enzymes co-localized with type IV collagen in capillaries, arterioles and post-capillary venules to a higher extent than PI SVMP, which showed a more widespread distribution in the tissue. The patterns of hydrolysis by these three SVMPs of laminin, type VI collagen and nidogen in vivo greatly differ, whereas the three enzymes showed a similar pattern of degradation of type IV collagen, supporting the concept that hydrolysis of this component is critical for the destabilization of microvessel structure leading to hemorrhage. Proteomic analysis of wound exudate revealed similarities and differences between the action of the three SVMPs. Higher extent of proteolysis was observed for the PI enzyme regarding several extracellular matrix components and fibrinogen, whereas exudates from mice injected with PII and PIII SVMPs had higher amounts of some intracellular proteins. Our results provide novel clues for understanding the mechanisms by which SVMPs induce damage to the microvasculature and generate hemorrhage.This work was performed in partial fulfillment of the requirements for the PhD degree for Cristina Herrera at Universidad de Costa Rica.Peer reviewe

Comparación de tres métodos moleculares para el análisis de procariontes ambientales en el mar del canal de Yucatán, México

In this study we describe a prokaryotic community from a seawater sample obtained in the Yucatan Channel, using for this purpose three molecular methods: 1) T-RFLPs. 2) Sequencing of amplicons (clone libraries). 3) Metagenome shotgun sequencing; the three are useful for the determination of microbial diversity. We also present a comparison of the scope and limits of each method. The comparison took into account three criteria: the number of taxonomic units detected, the taxonomic assignment accuracy and the cost of the study. The most abundant taxa were Candidatus Portiera OTU 3744 (equivalent to SAR86 clade) and Candidatus Pelagibacter. The results showed that the shotgun sequencing strategy is the most powerful in terms of detected taxonomic units, while the data obtained by T-RFLPs and clone library methods represent only a subsample of the shotgun fragment library. Regarding phylogenetic resolution (taxonomical determination), the more accurate approach is the sequencing of clone libraries. The costs of the three strategies vary considerably, but so does its scope. Therefore, it is important to consider that one, or another methodology, can only specifically answer some ecological and evolutionary questions.En este trabajo describimos la comunidad procarionte de una muestra de agua marina del canal de Yucatán. Para la determinación de la diversidad microbiana se usaron tres métodos moleculares: 1) T-RFLPs. 2) Secuenciación de amplicones (bibliotecas de clones). 3) Secuenciación shotgun de un metagenoma. Como un segundo objetivo, se presenta una comparación de los alcances y los límites de cada uno de estos tres métodos. Para esta comparación, se tomaron en cuenta tres criterios: el número de unidades taxonómicas detectadas, la precisión en la asignación taxonómica y el costo del estudio. Los taxa más abundantes fueron Candidatus Portiera OTU 3744 (equivalente al clado SAR86) y Candidatus Pelagibacter. Los resultados mostraron que la estrategia de secuenciación shotgun de ADN es la más poderosa en términos de unidades taxonómicas detectadas, mientras que los datos que se obtuvieron por T-RFLPs y con la biblioteca de clones, representan sólo una submuestra de la biblioteca de fragmentos generados mediante shotgun. En cuanto a resolución filogenética (determinación taxonómica), la aproximación más precisa fue la secuenciación de bibliotecas de clones. Los costos de las tres estrategias varían considerablemente, pero sus alcances también lo hacen. Por lo tanto, es importante tomar en consideración que algunas preguntas ecológicas y evolutivas sólo pueden ser contestadas específicamente por una u otra metodología

Two nonrecombining sympatric forms of the human malaria parasite Plasmodium ovale occur globally.

BACKGROUND: Malaria in humans is caused by apicomplexan parasites belonging to 5 species of the genus Plasmodium. Infections with Plasmodium ovale are widely distributed but rarely investigated, and the resulting burden of disease is not known. Dimorphism in defined genes has led to P. ovale parasites being divided into classic and variant types. We hypothesized that these dimorphs represent distinct parasite species. METHODS: Multilocus sequence analysis of 6 genetic characters was carried out among 55 isolates from 12 African and 3 Asia-Pacific countries. RESULTS: Each genetic character displayed complete dimorphism and segregated perfectly between the 2 types. Both types were identified in samples from Ghana, Nigeria, São Tomé, Sierra Leone, and Uganda and have been described previously in Myanmar. Splitting of the 2 lineages is estimated to have occurred between 1.0 and 3.5 million years ago in hominid hosts. CONCLUSIONS: We propose that P. ovale comprises 2 nonrecombining species that are sympatric in Africa and Asia. We speculate on possible scenarios that could have led to this speciation. Furthermore, the relatively high frequency of imported cases of symptomatic P. ovale infection in the United Kingdom suggests that the morbidity caused by ovale malaria has been underestimated

Opinion: Urban Resilience Efforts Must Consider Social And Political Forces

Environmental disasters, ranging from catastrophic floods to extreme temperatures, have caused more than 30,000 deaths per year and more than US$ 250–300 billion a year in economic losses, globally, between 1995 and 2015. Improved infrastructure and planning for extreme events is essential in urban areas, where an increasingly greater fraction of the world’s inhabitants reside. In response, international governmental and private initiatives have placed the goal of resilience at the center stage of urban planning. [For example, The 100 Resilient Cities Initiative (www.100resilientcities.org/); the Global Covenant of Mayors (https://www.compactofmayors.org/globalcovenantofmayors/); and the recent UN Habitat III (https://habitat3.org/the-new-urban-agenda)]. In addition, scientific and policy communities alike now recognize the need for “safe-to-fail” infrastructural design, and the potential role of green and blue infrastructure in mediating hydrological and climatic risks in cities

Significaciones de jóvenes acerca del trabajo, capacitación laboral, proyecto de vida y tecnología

A fines del 2009, segúnla OIT81 millones de jóvenes se encontraban desempleados en el mundo. En el contexto en el que vive América Latina, los jóvenes son el grupo que se presenta con mayor fragilidad en lo que respecta al mercado laboral. Las causas son múltiples, y se busca entender la situación actual por la que atraviesa la cohorte de esta edad.

Covalently Cross-Linked Nanoparticles Based on Ferulated Arabinoxylans Recovered from a Distiller’s Dried Grains Byproduct

The purpose of this investigation was to extract ferulated arabinoxylans (AX) from dried distillers’ grains with solubles (DDGS) plus to investigate their capability to form covalently cross-linked nanoparticles. AX registered 7.3 µg of ferulic acid/mg polysaccharide and molecular weight and intrinsic viscosity of 661 kDa and 149 mL/g, correspondingly. Fourier transform infrared spectroscopy (FTIR) was used to confirm the identity of this polysaccharide. AX formed laccase induced covalent gels at 1% (w/v), which registered an elastic modulus of 224 Pa and a content of FA dimers of 1.5 µg/mg polysaccharide. Scanning electron microscopy pictures of AX gels exhibited a microstructure resembling a rough honeycomb. AX formed covalently cross-linked nanoparticles (NAX) by coaxial electrospray. The average hydrodynamic diameter of NAX determined by dynamic light scattering was 328 nm. NAX presented a spherical and regular shape by transmission electron microscopy analysis. NAX may be an attractive material for pharmaceutical and biomedical applications and an option in sustainable DDGS use

Pautas WCAG: métodos y herramientas en el análisis y desarrollo de sitios web

Se resume los logros en la aplicación de métodos y herramientas destinadas a medir las pautas de accesibilidad de los contenidos web (WCAG 1.0 y 2.0) de diversos sitios, enfatizando en aquellos pertenecientes a organizaciones del NE y orientados a diversos dominios del conocimiento. Se consolida la formación de recursos humanos en la temática, incorporando los estudios realizados en el desarrollo de becas otorgadas por la UNNE y tesinas de grado.Eje: Ingeniería de SoftwareRed de Universidades con Carreras en Informática (RedUNCI