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Salgado-Maldonado G.,National University of Costa Rica | Novelo-Turcotte M.T.,National University of Costa Rica | Vazquez G.,Institute Ecologa | Caspeta-Mandujano J.M.,University Autnoma Del Estado Of Morelos | And 2 more authors.

SUMMARY We investigated a basic generalization in parasite community ecology stating that stochastic processes played a major part in determining the composition of helminth communities of freshwater fish, or on the contrary, if these communities are predictable, diverse and structured species assemblages. We determined the species pool of helminth parasites of a tropical freshwater fish Heterandria bimaculata in its heartland, the upper Río La Antigua basin in east-central Mexico. Approaching our data from the metapopulation standpoint we studied the spatial patterns, and examined the variation in composition and richness of the component communities across different locations. We tested the prediction that helminth species may be recognized as common or rare; and also two hypotheses anticipating depauperate communities and decay of similarity between component communities with increasing distance. We found these communities composed by a highly structured and predictable set of specialist autogenic helminth species that are constant and abundant, dominating all components throughout space. The prediction that it is possible to recognize common and rare species was met. Richer than expected communities were found, as well as highly homogeneous component communities, where neighbouring components were more similar than distant ones. We speculated that the processes shaping the development of these component communities include stable, predictable habitats through time, allowing for a slow gradual dispersion process limited by host and parasite species capabilities. Our study suggests that metapopulation theory can assist in the prediction of community composition and in the understanding of spatial and temporal community variability. © 2014 Cambridge University Press . Source

Petricevich V.L.,University Autnoma Del Estado Of Morelos
Mediators of Inflammation

Scorpion venoms consist of a complex of several toxins that exhibit a wide range of biological properties and actions, as well as chemical compositions, toxicity, and pharmacokinetic and pharmacodynamic characteristics. These venoms are associated with high morbility and mortality, especially among children. Victims of envenoming by a scorpion suffer a variety of pathologies, involving mainly both sympathetic and parasympathetic stimulation as well as central manifestations such as irritability, hyperthermia, vomiting, profuse salivation, tremor, and convulsion. The clinical signs and symptoms observed in humans and experimental animals are related with an excessive systemic host inflammatory response to stings and stings, respectively. Although the pathophysiology of envenomation is complex and not yet fully understood, venom and immune responses are known to trigger the release of inflammatory mediators that are largely mediated by cytokines. In models of severe systemic inflammation produced by injection of high doses of venom or venoms products, the increase in production of proinflammatory cytokines significantly contributes to immunological imbalance, multiple organ dysfunction and death. The cytokines initiate a cascade of events that lead to illness behaviors such as fever, anorexia, and also physiological events in the host such as activation of vasodilatation, hypotension, and increased of vessel permeability. © 2010 Vera L. Petricevich. Source

Santiago-Prez D.G.,University Autnoma Del Estado Of Morelos | Santiago-Prez D.G.,University Jose Mart Pe Rez Of Sanctispiritus | Prez-Lvarez R.,University Autnoma Del Estado Of Morelos
Physica B: Condensed Matter

We study the lattice dynamics of the zinc-blende (ZB) allotropic form of bulk group-III nitrides using an approach based on the linear chain model. Supported by the fact that the longitudinal oscillations and the transverse oscillations are effectively decoupled, the relationship between the three dimensional (3D) and linear chain (1D) force constants has been reported. It is possible then to fit the 3D bulk force constants (and consequently the whole dynamical matrix) from the information related to few points, either experimental or theoretical. In particular, we derive the dispersion relation and the corresponding force constants of BN, AlN, GaN and InN. Our results are in good agreement with previous ab initio results. © 2010 Elsevier B.V. All rights reserved. Source

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