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791.
Ponds are recognized worldwide as biodiversity hotspots; nevertheless in Patagonia studies are still needed that reveal the composition and status of their communities. This paper analyses the temporal patterns of aquatic invertebrates and assesses the environmental factors that best predict the variation in community structure at three small intermittent ponds, subjected to ranching practices (summer stocking) in the Patagonian steppe. Variables identified as important in structuring community assemblages were related to environmental conditions (rainfall and water temperature), chemical features (conductivity and pH) and biotic factors (macrophyte coverage). During the connected phase only a small number of invertebrate species were present, in contrast to the 11 taxa that were frequent and abundant during the isolated period (Eucyclops chilensis, Hyalella curvispina and Rhionaeschna sp. were dominant). In this sequence the submersed Myriophyllum quitense and Lilaeopsis macloviana played a crucial role offering habitat and food resources. The present study provides valuable information that can contribute to minimizing the environmental damage and the development of strategies for the conservation of Patagonian wetlands. 相似文献
792.
Raúl Ernesto Campos 《Journal of Natural History》2016,50(13-14):905-921
This study addresses how Diptera assemblages differ in four sympatric phytotelmata. The Eryngium species retain water in their axils forming a phytotelm and this situation leads to the speculation that dipteran assemblages may differ, mainly when the plants begin to grow and retain more water in their axils, and when becoming senescent. Diptera from Eryngium horridum, Eryngium stenophyllum, Eryngium aff. serra and Eryngium elegans were sampled. This study revealed that the Eryngium spp. are used by Diptera differentially and their populations show seasonal changes, with peaks in the autumn. Diptera were represented by immature stages belonging to six aquatic and seven semi-aquatic families. The most important were Chironomidae, Culicidae, Periscelididae and Ceratopogonidae. Two species of Chironomids were the most abundant. Culicidae, Periscelididae and Ceratopogonidae were more selective than Chironomidae. Saprophages were the most abundant where the fine detritus feeders were the dominant group. Periscelididae was the main free-swimming predator. 相似文献
793.
Aquaglyceroporins: implications in adipose biology and obesity 总被引:1,自引:1,他引:0
Ana Madeira Teresa F. Moura Graça Soveral 《Cellular and molecular life sciences : CMLS》2015,72(4):759-771
Aquaporins (AQPs) are membrane water/glycerol channels that are involved in many physiological processes. Their primary function is to facilitate the bidirectional transfer of water and small solutes across biological membranes in response to osmotic gradients. Aquaglyceroporins, a subset of the AQP family, are the only mammalian proteins with the ability to permeate glycerol. For a long time, AQP7 has been the only aquaglyceroporin associated with the adipose tissue, which is the major source of circulating glycerol in response to the energy demand. AQP7 dysregulation was positively correlated with obesity onset and adipocyte glycerol permeation through AQP7 was appointed as a novel regulator of adipocyte metabolism and whole-body fat mass. Recently, AQP3, AQP9, AQP10 and AQP11 were additionally identified in human adipocytes and proposed as additional glycerol pathways in these cells. This review contextualizes the importance of aquaglyceroporins in adipose tissue biology and highlights aquaglyceroporins’ unique structural features which are relevant for the design of effective therapeutic compounds. We also refer to the latest advances in the identification and characterization of novel aquaporin isoforms in adipose tissue. Finally, considerations on the actual progress of aquaporin research and its implications on obesity therapy are suggested. 相似文献
794.
795.
796.
This article examines how Hans G. Gadamer’s philosophical hermeneutics can contribute to contemporary debates on the concept of ‘presentism’. In the field of the history of science, this term is usually employed in two ways. First, ‘presentism’ refers to the kind of historiography which judges the past to legitimate the present. Second, this concept designates the inevitable influence of the present in the interpretation of the past. In this paper, I argue that both dimensions of the relationship between the present and the past are explored by Hans G. Gadamer in Truth and Method and other texts. In the first place, Gadamer’s critique of historicism calls into question the anti-presentist ideal of studying the past for ‘its own sake’. In the second place, Gadamer’s thesis that all understanding inevitably involves some prejudice poses the question of the inherent “present-centredness” of historical interpretations. By examining Gadamer’s hermeneutics, I seek to provide historians with new arguments and perspectives on the question of ‘presentism’. 相似文献
797.
Maria J. Marcaida Inés G. Muñoz Francisco J. Blanco Jesús Prieto Guillermo Montoya 《Cellular and molecular life sciences : CMLS》2010,67(5):727-748
Homing endonucleases (HE) are double-stranded DNAses that target large recognition sites (12–40 bp). HE-encoding sequences
are usually embedded in either introns or inteins. Their recognition sites are extremely rare, with none or only a few of
these sites present in a mammalian-sized genome. However, these enzymes, unlike standard restriction endonucleases, tolerate
some sequence degeneracy within their recognition sequence. Several members of this enzyme family have been used as templates
to engineer tools to cleave DNA sequences that differ from their original wild-type targets. These custom HEs can be used
to stimulate double-strand break homologous recombination in cells, to induce the repair of defective genes with very low
toxicity levels. The use of tailored HEs opens up new possibilities for gene therapy in patients with monogenic diseases that
can be treated ex vivo. This review provides an overview of recent advances in this field. 相似文献
798.
Beatriz Domingo María Gasset Mario Durán-Prado Justo P. Castaño Antonio Serrano Thierry Fischer Juan Llopis 《Cellular and molecular life sciences : CMLS》2010,67(19):3345-3354
Membrane protein function is determined by the relative organization of the protein domains with respect to the membrane.
We have experimentally verified the topology of a protein with diverse orientations arising from a single primary sequence
(the cellular prion protein, PrPC), a novel somatostatin truncated receptor, and the Golgi-associated protein GPBP91. Tagging with fluorescent proteins (FP) allows location of their expression at the plasma membrane or at endomembranes, but
does not inform about their orientation. Exploiting the pH dependency of some FPs, we developed a pH exchange assay in which
extracellularly exposed FPs are quenched by application of low pH buffer. We constructed standards to demonstrate and calibrate
the assay, and the method was adapted for acidic organelle membrane proteins. This method can serve as a proof of concept,
experimentally confirming and/or discriminating in living cells among theoretical topology predictions, providing the proportion
of inside/outside orientation for proteins with multiple forms. 相似文献
799.
800.
Often the data units are described with discrete distributions (work described with citation distribution over time, population pyramid described as age-sex distribution etc.).When the set of such units is very large, appropriate clustering methods can reveal the typical patterns hidden in the data. 相似文献