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Erdal Karaoz Selda Ayhan Gülçin Gacar Ayça Aksoy Gökhan Duruksu Alparslan Okçu P. Çetinalp Demircan A. Eker Sariboyaci Figen Kaymaz Murat Kasap 《Cytotherapy》2010,12(3):288-302
Background aimsStem cells (SC) in different locations have individual characteristics. Important questions to be answered include how these specialties are generated, what the mechanism underlying their generation is, and what their biologic and clinical merits are. A basic approach to answering these questions is to make comparisons between the differences and similarities among the various SC types. They may focus on aspects of biologic marker discovery, capacity of proliferation and differentiation, along with other characteristics. The aim of this study was to characterize in detail the SC isolated from pancreatic islet (PI) and compare their properties with bone marrow (BM)-derived mesenchymal stromal cells (MSC) of the rat.MethodsImmunophenotypic characteristics, proliferation capacities, telomerase activities, pluripotent-related gene expressions, ultrastructure and the potential for multilineage differentiation of PI SC and BM MSC were studied.ResultsWe found that PI SC expressed markers of embryonic SC (Oct-4, Sox-2 and Rex-1) and had a high proliferation capacity, proven also by high telomerase activities. Surprisingly, markers belonging to differentiated cells were expressed by these cells in a constitutive manner. PI SC ultrastructure showed more developed and metabolically active cells.ConclusionsThe immunocytochemical identification of both PI SC and BM MSC was demonstrated to be typical MSC. Without stimulation of differentiation markers of adipogenic, chondrogenic, neurogenic, myogenic and osteogenic cells in these SC, the expression of those markers might explain their multilineage differentiation potential. We suggest that, by reason of the respectively high telomerase activity in PI SC, they could be better candidates than BM MSC for cell replacement therapy of type 1 diabetes. 相似文献
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Aquatic plants are used as a practical and effective method to remove toxic elements from secondary-treated municipal wastewater. In this study, Lemna gibba was investigated for its capacity to remove uranium, arsenic, and boron from secondary effluents. L. gibba was collected from a natural lake in Elaz??, Turkey, then acclimatized to the effluent in situ. The concentration of toxic elements in the plant material was monitored as a function of time for 7 days. L. gibba significantly accumulated the toxic elements, particularly in the first 2 days. Arsenic, uranium, and boron were accumulated in the highest concentrations (133%, 122%, and 40%, respectively). However, in the following days, accumulation levels showed both increases and decreases, most probably due to L. gibba reaching saturation levels. 相似文献
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JULIEN GRANGIER ALAIN DEJEAN PIERRE-JEAN G. MALÉ PASCAL-JEAN SOLANO JÉRÔME ORIVEL 《Biological journal of the Linnean Society. Linnean Society of London》2009,97(1):90-97
In the understory of pristine Guianese forests, the myrmecophyte Hirtella physophora almost exclusively shelters colonies of the plant-ant Allomerus decemarticulatus in its leaf pouches. We experimentally tested three non-mutually exclusive hypotheses concerning phenomena that can determine the species specificity of this association throughout the foundation stage of the colonies: (1) interspecific competition results in the overwhelming presence of A. decemarticulatus queens or incipient colonies; (2) exclusion filters prevent other ant species from entering the leaf pouches; and (3) host-recognition influences the choice of founding queens, especially A. decemarticulatus . Neither interspecific competition, nor the purported exclusion filters that we examined play a major role in maintaining the specificity of this association. Unexpectedly, the plant trichomes lining the domatia appear to serve as construction material during claustral foundation rather than as a filter. Finally, A. decemarticulatus queens are able to identify their host plant from a distance through chemical and/or visual cues, which is rarely demonstrated in studies on obligatory ant–plant associations. We discuss the possibility that this specific host-recognition ability could participate in shaping a compartmentalized plant-ant community where direct competition between ant symbionts is limited. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 90–97. 相似文献
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The Iberian Peninsula represents a hot spot of cyphophthalmid (mite harvestman) disparity, with four of the eight genera currently recognized in the family Sironidae represented in the region – a generic diversity and morphological disparity not found in any other region of the World so far. From these, two genera (Iberosiro and Odontosiro) are monotypic, and are restricted to the western side of the peninsula. Parasiro is restricted to the north‐east region, from the Catalonian Coastal Ranges and both sides of the Eastern Pyrenees, in areas where the annual rainfall surpasses 1000 mm, and mostly restricted to areas with Paleozoic and Variscan rocks, with other species of the genus extending to Corsica, Sardinia, and the Italian Peninsula. A second species of the genus Paramiopsalis, Paramiopsalis eduardoi sp. nov. from Fragas do Eume, is described here along with a re‐diagnosis of the genus. Paramiopsalis species, together with Odontosiro, inhabit the north‐west corner of the Iberian Peninsula, an area with some of the highest recorded annual rainfall, and with Paleozoic rocks from the Iberian Massif or Variscan granitoid rocks. A phylogenetic analysis of the members of the family Sironidae using four molecular markers, despite not including all of the Iberian genera, clearly shows the non‐monophyly of the Iberian Cyphophthalmi, indicating that the Iberian Peninsula is home to multiple ancient lineages of mite harvestmen. The two Paramiopsalis species form a sister clade to the Balkan genus Cyphophthalmus, whereas Parasiro constitutes the first lineage of the sironids represented. 相似文献
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Katherine ME Turner Elisabeth J Adams Nigel Gay Azra C Ghani Catherine Mercer W John Edmunds 《Theoretical biology & medical modelling》2006,3(1):3-11
Background
A national chlamydia screening programme is currently being rolled out in the UK and other countries. However, much of the epidemiology remains poorly understood. In this paper we present a stochastic, individual based, dynamic sexual network model of chlamydia transmission and its parameterisation. Mathematical models provide a theoretical framework for understanding the key epidemiological features of chlamydia: sexual behaviour, health care seeking and transmission dynamics. 相似文献120.