147 research outputs found

    Nanoplastics: From tissue accumulation to cell translocation into Mytilus galloprovincialis hemocytes. resilience of immune cells exposed to nanoplastics and nanoplastics plus Vibrio splendidus combination

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    Plastic litter is an issue of global concern. In this work Mytilus galloprovincialis was used to study the distribution and effects of polystyrene nanoplastics (PS NPs) of different sizes (50 nm, 100 nm and 1 mu m) on immune cells. Internalization and translocation of NPs to hemolymph were carried out by in vivo experiments, while endocytic routes and effects of PS NPs on hemocytes were studied in vitro. The smallest PS NPs tested were detected in the digestive gland and muscle. A fast and size-dependent translocation of PS NPs to the hemolymph was recorded after 3 h of exposure. The internalization rate of 50 nm PS NPs was lower when caveolae and clathrin endocytosis pathways were inhibited. On the other hand, the internalization of larger particles decreased when phagocytosis was inhibited. The hemocytes exposed to NPs had changes in motility, apoptosis, ROS and phagocytic capacity. However, they showed resilience when were infected with bacteria after PS NP exposure being able to recover their phagocytic capacity although the expression of the antimicrobial peptide Myticin C was reduced. Our findings show for the first time the translocation of PS NPs into hemocytes and how their effects trigger the loss of its functional parameters

    Bird conservation and biodiversity research in Mexico: status and priorities

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    This is the peer reviewed version of the following article: Peterson, A. T. and Navarro-SigĂĽenza, A. G. (2016), Bird conservation and biodiversity research in Mexico: status and priorities. J. Field Ornithol.. doi:10.1111/jofo.12146, which has been published in final form at doi:10.1111/jofo.12146. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Mexico holds a megadiverse avifauna that includes many endemic elements, as well as rich sets of species from both farther north and farther south in the Americas. This avifauna, nonetheless, has suffered considerable losses as a consequence of long-term, intensive human activity across the landscape. We review what is known about the Mexican avifauna, specifically its diversity and endemism, and how that knowledge has and has not turned into effective conservation measures to assure the long-term integrity of the avifauna

    Assumption- versus data-based approaches to summarizing species’ ranges

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    This is the peer reviewed version of the following article: Assumption- versus data-based approaches to summarizing species’ ranges, which will be published in final form in Conservation Biology at http://dx.doi.org/10.1111/cobi.12801. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving: http://olabout.wiley.com/WileyCDA/Section/id-828039.html#termsSpecies’ geographic distributions are mapped using various approaches for use in conservation decision-making. Some such mapping efforts have relied on modifications of coarse-resolution extent-of-occurrence maps to downscale them to fine resolutions for conservation planning. This contribution examines (1) the quality of the extent-of-occurrence maps as range summaries, and (2) the utility of refining those maps into fine-resolution distributional hypotheses. In both cases, we found significant problems: the extent-of-occurrence maps are overly simple, omit many known and well-documented populations, and likely frequently include many areas not holding populations. Refinement steps involve typological assumptions about habitat preferences and elevational ranges of species, which can introduce significant error in anticipating species’ true distributional areas; however, as no model evaluation steps are taken to assess predictive ability of models, “bad” models are not noticed. Whereas range summaries derived by these methods may be useful in coarse-grained, global-extent studies, their continued use in on-the-ground conservation challenges at fine resolutions is not advisable. On the other hand, data-driven techniques that integrate primary biodiversity occurrence data with remotely sensed data summarizing environmental dimensions, termed ecological niche modeling or species distribution modeling, with rigorous and quantitative testing of model predictions prior to any use. These data-driven approaches constitute a well-founded, widely accepted alternative with a minimum of assumptions

    A Mexican case study on a centralised database from world natural history museums

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    The present contribution is a case study of the possibilities of using data from world scientific collections to understand the distribution and conservation of Mexican birds. Information was gathered on specimens from Mexico housed in 40 scientific collections in Mexico, the United States, Canada, and Europe. This information was compiled in a centralized database and various analyses were developed to address historical patterns of ornithological investigations in Mexico: current and potential distribution areas of the species; patterns of species richness, endemism and seasonality; and conservation applications

    Genetic Variation and Differentiation in Mexican Populations of Common Bush-Tanagers and Chestnut-Capped Brush-Finches

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    Genetic differentiation among four Mexican populations each of Common Bush-tanagers (Chlorospingus ophthalmicus) and Chestnut-capped Brush-finches (Atlapetes brunneinucha) was evaluated using allozyme electrophoresis. In both species, although levels of within-population variation are moderate, among-population variation is extreme, including fixed differences among populations. Genetic variation is significantly reduced in some populations on the smallest habitat islands. Differentiation is apparently unrelated to geographic distance among populations, and effects of habitat island size and isolation on genetic differentiation are not clear. Populations of the Sierra de los Tuxtlas in Veracruz, however, are strongly differentiated in both species

    Dynamic Kinetic Resolution of Hetero biaryl Ketones by Zinc- Catalyzed Asymmetr ic Hydrosil ylation

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    Adiastereo- and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile hetero- biaryl ketones is described. The DKR proceeds by zinc- catalyze dhydrosilylation of the carbonyl group ,thus leading to secondary alcohols bearing axial and central chirality .The strategy relies on the labilization of the stereogenic axis that takes place thanks to aLewis acid–base interaction between anitrogen atom in the heterocycle and the ketone carbonyl group .The synthetic utility of the methodology is demonstrated through stereospecific transformations into either N,N-ligands or appealing axially chiral, bifunctional thiourea organocata- lysts.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P, CTQ2016-76908-C2-2-P, contract RYC-2013-12585)European FEDER FundsJunta de Andalucía (Grant 2012/FQM 10787)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement n 8 8 291780

    A Dynamic Kinetic Asymmetric Heck Reaction for the Simultaneous Generation of Central and Axial Chirality

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    A highly diastereo- and enantioselective, scalable Pd-catalyzed dynamic kinetic asymmetric Heck reaction of heterobiaryl sulfonates with electron-rich olefins is described. The coupling of 2,3-dihydrofuran or N-boc protected 2,3-dihydropyrrole with a variety of quinoline, quinazoline, phthalazine, and picoline derivatives takes place with simultaneous installation of central and axial chirality, reaching excellent diastereo- and enantiomeric excesses when in situ formed [Pd0/DM-BINAP] was used as the catalyst, with loadings reduced down to 2 mol % in large scale reactions. The coupling of acyclic, electron-rich alkenes can also be performed using a [Pd0/Josiphos ligand] to obtain axially chiral heterobiaryl α-substituted alkenes in high yields and enantioselectivities. Products from Boc-protected 2,3-dihydropyrrole can be easily transformed into N,N ligands or appealing axially chiral, bifunctional proline-type organocatalysts. Computational studies suggest that a β-hydride elimination is the stereocontrolling step, in agreement with the observed stereochemical outcome of the reaction.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P; CTQ2016-76908-C2-2-P; CTQ2016-78083-P; RYC-2013-12585)European Commission (FEDER Programme)Junta de Andalucía (Grant 2012/FQM 10787)Universidad de Sevilla (Grant No. 1800511201)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement nº 291780

    Molecular systematics and evolution of the Cyanocorax jays

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    Phylogenetic relationships were studied in the genus Cyanocorax (Aves: Corvidae) and related genera, Psilorhinus and Calocitta, a diverse group of New World jays distributed from the southern United States south to Argentina. Although the ecology and behavior of some species in the group have been studied extensively, lack of a molecular phylogeny has precluded rigorous interpretations in an evolutionary framework. Given the diverse combinations of plumage coloration, size, and morphology, the taxonomy of the group has been inconsistent and understanding of biogeographic patterns problematic. Moreover, plumage similarity between two geographically disjuct species, the Tufted Jay (Cyanocorax dickeyi) from western Mexico and the White-tailed Jay (C. mystacalis) from western Ecuador and Peru, has puzzled ornithologists for decades. Here, a phylogeny of all species in the three genera is presented, based on study of two mitochondrial and three nuclear genes. Phylogenetic trees revealed the non-monophyly of Cyanocorax, and the division of the whole assemblage in two groups: “Clade A” containing Psilorhinus morio, both species in Calocitta, Cyanocorax violaceus, C. caeruleus, C. cristatellus, and C. cyanomelas, and “Clade B” consisting of the remaining species in Cyanocorax. Relationships among species in Clade A were ambiguous and, in general, not well resolved. Within Clade B, analyses revealed the monophyly of the “Cissilopha” jays and showed no evidence for a sister relationship between C. mystacalis and C. dickeyi. The phylogenetic complexity of lineages in the group suggests several complications for the understanding biogeographic patterns, as well as for proposing a taxonomy that is consistent with morphological variation. Although multiple taxonomic arrangements are possible, recommendations are for recognizing only one genus, Cyanocorax, with Psilorhinus and Calocitta as synonyms. Se estudiaron las relaciones filogenéticas en los géneros Cyanocorax, Psilorhinus y Calocitta (Aves: Corvidae), un grupo diverso de urracas del Nuevo Mundo cuyas especies se distribuyen desde el sur de los Estados Unidos hasta Argentina. Aunque la ecología y el comportamiento de algunas especies en el grupo han sido estudiadas extensamente, la falta de una filogenia molecular ha impedido la interpretación rigurosa de estos estudios en un marco evolutivo. Dadas las diversas combinaciones de coloración de plumaje, tamaño y morfología presentes en las especies del grupo, su taxonomía ha sido inconsistente y la interpretación de sus patrones biogeográficos ha sido problemática. Mas aún, la similitud de plumaje en especies que están geográficamente distantes, como Cyanocorax dickeyi del oeste de Mexico y C. mystacalis del oeste de Ecuador y Perú, ha sido difícil de interpretar. Se presenta una filogenia para todas las especies en los tres géneros, basada en el estudio de dos genes nucleares y dos genes mitocondriales. Los árboles filogenéticos mostraron la parafilia de Cyanocorax y la división de todas las especies en dos grupos: “Clado A” en el cual se encuentran Psilorhinus morio, ambas especies Calocitta, Cyanocorax violaceus, C. caeruleus, C. cristatellus, y C. cyanomelas, y “Clado B” en el cual se encuentran el resto de las especies de Cyanocorax. Las relaciones entre especies del Clado A fueron ambiguas y, en general, poco resueltas. En el Clado B, los análisis mostraron la monofilia de las especies en “Cissilopha”, pero no indicaron la monofilia de C. mystacalis + C. dickeyi. La complejidad filogenética de los linajes en el grupo sugiere varias complicaciones en el entendimiento de su biogeografía y taxonomía. Con base en los resultados filogenéticos se reconoce un solo género, Cyanocorax, con Psilorhinus y Calocitta como sinónimos

    Fast response and temporal coherent oscillations in small-world networks

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    We have investigated the role that different connectivity regimes play in the dynamics of a network of Hodgkin-Huxley neurons by computer simulations. The different connectivity topologies exhibit the following features: random topologies give rise to fast system response yet are unable to produce coherent oscillations in the average activity of the network; on the other hand, regular topologies give rise to coherent oscillations, but in a temporal scale that is not in accordance with fast signal processing. Finally, small-world topologies, which fall between random and regular ones, take advantage of the best features of both, giving rise to fast system response with coherent oscillations.We acknowledge G. Laurent, A. Bäcker, M. Bazhenov, M. Rabinovich, and H. Abarbanel for insightful discussions. We thank the Dirección General de Enseñanza Superior e Investigación Científica for financial support (PB97-1448), the CAM for financial support to L. F. L., and the CCCFC (UAM) for the use of computation resources
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