121 research outputs found

    Evolución del género Megacricetodon del Aragoniense y Vallesiense (Mioceno) de la Península Ibérica

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    Tesis inédita presentada la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, leída el 11-03-2015Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEunpu

    Early Miocene evolution of the rodent Megacricetodon in Europe and its palaeobiogeographical implications

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    Received 20 June 2014, accepted 15 September 2014, available online 23 October 2014The Megacricetodon material from Aliveri (Isle of Evia, Greece) was previously assigned to M. primitivus, implying palaeobiogeographical relationship between south-eastern and south-western Europe. The material from Aliveri is here assigned to the new species Megacricetodon hellenicus sp. nov. This form has significant morphological differences compared to other Early Miocene species from Europe. This new evolutionary hypothesis of this genus has implications on the Early Miocene paleobiogeography of Europe. This work presents a new interpretation on the earliest European representative of the genus Megacricetodon from Aliveri localities. Analyses of the Megacricetodon material from MN 4 and MN 5 localities enable to propose a new palaeobiogeographical framework in which there are three main migration events of the genus Megacricetodon into Europe, each corresponding to different lineages that evolved independently. The new Greek taxon is considered the first migration wave from Anatolia, representing an endemic lineage different from any other European Megacricetodon.This research was supported by the Spanish MINECO Project No. GL-2008-04200/BTE and CGL2011-28877Peer reviewe

    Large-sized species of ctenodactylidae from the Valley of Lakes (Mongolia): An update on dental morphology, biostratigraphy, and paleobiogeography

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    Our study of the large and medium-sized species of Yindirtemys from the Valley of Lakes in Mongolia yielded three species: Yindirtemys deflexus, Y. suni and Y. birgeri. They differ in size and dental morphology. Yindirtemys suni is the largest and Y. birgeri the smallest species. Yindirtemys deflexus and Y. suni increase in body size but do not change dental morphology within their time range. The medium-sized Yindirtemys birgeri co-occurs in Mongolia with Y. deflexus in the late Oligocene (biozone C1) and is the easternmost occurrence of the species so far. Hitherto, Y. birgeri has been recorded from the Aral region in Kazakhstan only. Both Yindirtemys deflexus and Y. suni are used as biostratigraphic markers. Yindirtemys deflexus is a “key fossil” of the Chinese Land Mammal Age Tabenbulukian and for the Mongolian biozone C1; the latter correlates with the Oligocene. Yindirtemys suni is one of the “key fossils” of the Chinese Land Mammal Age Xiejian. In Mongolia the species ranges from the OligoceneMiocene transition (biozone C1-D) to the earliest Miocene (biozone D). The wide geographic range of Yindirtemys in the Oligocene of Asia suggests that no major physical barriers hampered mammal distribution between Kazakhstan, Mongolia and northern China, but local paleoecological and climatic conditions might have influenced mammal community structures in these areas.Peer Reviewe

    Cochleates derived from Vibrio cholerae O1 proteoliposomes : The impact of structure transformation on mucosal immunisation

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    Cochleates are phospholipid-calcium precipitates derived from the interaction of anionic lipid vesicles with divalent cations. Proteoliposomes from bacteria may also be used as a source of negatively charged components, to induce calcium-cochleate formation. In this study, proteoliposomes from V. cholerae O1 (PLc) (sized 160.7±1.6 nm) were transformed into larger (16.3±4.6 µm) cochleate-like structures (named Adjuvant Finlay Cochleate 2, AFCo2) and evaluated by electron microscopy (EM). Measurements from transmission EM (TEM) showed the structures had a similar size to that previously reported using light microscopy, while observations from scanning electron microscopy (SEM) indicated that the structures were multilayered and of cochleate-like formation. The edges of the AFCo2 structures appeared to have spaces that allowed penetration of negative stain or Ovalbumin labeled with Texas Red (OVA-TR) observed by epi-fluorescence microscopy. In addition, freeze fracture electron microscopy confirmed that the AFCo2 structures consisted of multiple overlapping layers, which corresponds to previous descriptions of cochleates. TEM also showed that small vesicles co-existed with the larger cochleate structures, and in vitro treatment with a calcium chelator caused the AFCo2 to unfold and reassemble into small proteoliposome-like structures. Using OVA as a model antigen, we demonstrated the potential loading capacity of a heterologous antigen and in vivo studies showed that with simple admixing and administration via intragastric and intranasal routes AFCo2 provided enhanced adjuvant properties compared with PLc

    Immune adjuvant effect of V. cholerae O1 derived Proteoliposome coadministered by intranasal route with Vi polysaccharide from Salmonella Typhi

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    Proteoliposome derived from Vibrio cholerae O1 (PLc) is a nanoscaled structure obtained by detergent extraction process. Intranasal (i.n) administration of PLc was immunogenic at mucosal and systemic level vs. V. cholerae; however the adjuvant potential of this structure for non-cholera antigens has not been proven yet. The aim of this work was to evaluate the effect of coadministering PLc with the Vi polysaccharide antigen (Poli Vi) of S. Typhi by i.n route. The results showed that Poli Vi coadministered with PLc (PLc+Poli Vi) induce higher IgA response in saliva (p0.05) to that induced in a group of mice immunised by parenteral route with the Cuban anti-typhoid vaccine vax-TyVi®, although this vaccine did not induce mucosal response. In conclusion, this work demonstrates that PLc can be used as mucosal adjuvant to potentiate the immune response against a polysaccharide antigen like Poli Vi

    Updated Aragonian biostratigraphy: Small Mammal distribution and its implications for the Miocene European Chronology

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    This paper contains formal definitions of the Early to Middle Aragonian (late Early–Middle Miocene) smallmammal biozones from the Aragonian type area in North Central Spain. The stratigraphical schemes of two of the best studied areas for the Lower and Middle Miocene, the Aragonian type area in Spain and the Upper Freshwater Molasse from the North Alpine Foreland Basin in Switzerland, have been compared. This comparison allows the analysis of the order of shared mammal events in the two countries, and the quantification of the resulting asynchronies based on their temporal correlations. The order of the events is very similar in Spain and Switzerland. In order to estimate the diachrony, two age-model options are used for the Swiss record. Our preferred option yields no discrepancies with SW European paleomagnetic and radiometric calibrations of the Ramblian and Early Aragonian bioevents. All Swiss first taxa occurrences precede those in the Aragonian type area by 0.74Myr on average. The asynchronies (1-2Myr) of the species arriving in the late Middle to early Late Aragonian may be higher than in the Early Aragonian (0-1Myr). The implications for the biochronological mammal Neogene system are discussed. Evidence is given confirming the unfeasibility of a formal European biozonation, since it is realised, that 1) most indicator species and many genera of rodents yielding the most detailed zonations have limited geographical ranges hampering recognition of the mammal Neogene zones; and 2) first and last taxon occurrences are diachronical. Therefore, the mammal Neogene system based on a sequence of time-ordered reference localities is preferred to the one based on selected bioevents “developed in widespread geographic areas”.Peer reviewe

    El suelo y la sostenibilidad. Recurso para una aproximación multidisciplinar en la enseñanza de las Ciencias

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    El proyecto pretende dar a conocer el suelo como recurso natural al alumnado. Se trata de un recurso vital, profundamente desconocido y escasamente trabajado en las aulas. Apenas aparece de forma explícita en el currículo de Secundaria y menos aún en el de Primaria. Muchos organismos internacionales han resaltado la necesidad de que el ciudadano de a pie conozca el suelo, su enorme valor en la alimentación del ser humano y el grave riesgo en el que se encuentra hoy en día pues su fertilidad está descendiendo a un ritmo alarmante debido fundamentalmente a la acción humana. El valorar este recurso pasa por conocerlo y para ello es necesario trabajarlo en las aulas, pero antes hemos de formar a los futuros docentes,esto es lo que nos hemos propuesto desde la Facultad de Educación. Por otro lado nos resulta fundamental el que los ciudadanos conozcan el compostaje, actividad fácil de desarrollar tanto en los centros docentes como en el propio domicilio; compostar permite cuidar el medio ambiente de forma doble, por un lado reduciendo los desechos y por otro produciendo un material (el compost) con muchas ventajas para la agricultura, contribuyendo de esta forma a la sostenibilidad
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