465 research outputs found

    Deep-scaled fish (Osteichthyes: Actinopterygii) from the lower Permian (Cisuralian) lacustrine deposits of the Parnaíba Basin, NE Brazil

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    The richly fossiliferous deposits of the Brazilian Pedra de Fogo Formation originated in an extensive aquatic system in tropical Pangaea, and grade from marginal lacustrine into marine deposits at the depocenter in the western part of the Parnaíba Basin. In addition to the well-known tetrapod and macrofloral records from these deposits, the Pedra de Fogo Formation yields extensive fish fossils indicating a diverse and abundant ichthyofauna. Among the actinopterygians, deep-bodied morphotypes are represented by whole fish as well as disarticulated dermal scales found at various localities in the states of Maranhão and Piauí. The gross morphology, ornamentation, and histology of some of these scales is highly distinctive, indicating the presence of a novel taxon (Piratata rogersmithii gen. et sp. nov.). The external surface of a Piratata scale is covered in multiple round-to-slightly elongated tubercles. The scale lacks a ganoin cover and is made up of cellular bone and odontocomplexes of orthodentine composing the tuberculated scale surface. The scale morphology and ornamentation most closely resemble that of Cleithrolepis granulatus from the Triassic of Australia and Cleithrolepis extoni from the Triassic Stormberg Beds of South Africa, but the new taxon differs from previously described species in several diagnostic morphological features. The use of scale characters in the taxonomy of ray-finned fishes and the palaeogeographic, palaeoenvironmental, and geochronological implications of the new taxon are discussed.Fil: Richter, Martha. British Museum (Natural History); Reino UnidoFil: Cisneros, Juan C.. Universidade Federal do Piaui; BrasilFil: Kammerer, Christian. North Carolina Museum Of Natural Sciences; Estados UnidosFil: Pardo, Jason. Field Museum of National History; Estados UnidosFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Frobisch, Jorg. Staatliches Museum fur Naturkunde Stuttgart; AlemaniaFil: Angielczyk, Ken. Field Museum of National History; Estados Unido

    Paleozoic Crown Lungfishes from Gondwana foreshadow the Early Triassic Recovery Fauna

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    Modern lungfishes are renowned for tolerance of extreme environmental variation, which is thought to contribute to their abundance during the recovery from the Permo-Triassic Mass Extinction (PTME). However, the Paleozoic origins of this clade and its biogeographic context remains unclear, with a 60 Ma ghost lineage at the base of the crown lungfish diversification spanning much of the Upper Carboniferous and the entirety of the Permian. This gap is particularly perplexing given the exceptional record of archaic lungfishes within this interval, particularly within paleoequatorial Euramerica, but also within eastern Europe. One possibility is that the assembly of the crown lungfish bauplan from known Carboniferous and Permian archaic lungfish groups occurred rapidly in the recovery from the PTME. However, an alternative explanation is that the crown lungfish bauplan evolved earlier in geographic regions outside the well-sampled Carboniferous and Permian basins of Euramerica, Russia, and South Africa. The sudden appearance of a diverse crown lungfish fauna in the earliest Triassic would then represent a biogeographic release in response to climate or diversity trends associated with the PTME. New lungfish faunas from outside these basins provide an opportunity to test these hypotheses. Here we report a diverse lungfish fauna from the Early Permian Pedra de Fogo Formation (Parnaíba Basin, northeastern Brazil) comprised of abundant lungfish toothplates and rarer associated or articulated skeletal remains. This fauna lacks archaic lungfish taxa (e.g. sagenodontids, ctenodontids, and conchopomatids) characteristic of contemporary localities in equatorial Euramerica. Instead, the Parnaíba fauna preserves a diverse assemblage of derived lungfishes, including a gnathorhizid and several crown lungfishes (ceratodontiforms). The gnathorhizid is represented by abundant toothplates and several partial skulls, and shows similarities to the North American gnathorhizid genera Persephonichthys and Gnathorhiza. The ceratodontiform, which is represented by toothplates as well as several partial skulls and skeletons, shows affinities with Triassic ptychoceratodontids and arganodontids, currently considered early members of the lepidosireniform stem group. Comparison with lungfish toothplate assemblages from the Paraná Basin of southern Brazil shows that the lungfish assemblage from the Parnaíba basin is also present in the Middle Permian of Brazil, likely representing a persistent biogeographic province in western Gondwana. We hypothesize that the lungfish crown group originated early in western Gondwana, but remained biogeographically restricted until the PTME eliminated incumbent competition in better-known biogeographical provinces.Fil: Pardo, Jason. University of Calgary; CanadáFil: Kammerer, Christian. Museum Fur Naturkunde; AlemaniaFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Angielczyk, Kenneth D.. Field Museum of National History; Estados UnidosFil: Fröbisch, Jörg. No especifíca;Fil: Smith, Roger M. H.. University of Cape Town; SudáfricaFil: Cisneros, Juan C.. Universidade Federal do Piaui; BrasilAnnual Meeting Society Vertebrate PaleontologyEstados UnidosSociety of Vertebrate Paleontolog

    Dark photon production through positron annihilation in beam-dump experiments

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    High energy positron annihilation is a viable mechanism to produce dark photons (AA^\prime). This reaction plays a significant role in beam-dump experiments using experiments using multi-GeV electron-beams on thick targets by enhancing the sensitivity to AA^\prime production. The positrons produced by the electromagnetic shower can produce an AA^\prime via non-resonant (e++eγ+Ae^+ + e^- \to \gamma + A^\prime) and resonant (e++eAe^+ + e^- \to A^\prime) annihilation on atomic electrons. For visible decays, the contribution of resonant annihilation results in a larger sensitivity with respect to limits derived by the commonly used AA^\prime-strahlung in certain kinematic regions. When included in the evaluation of the E137 beam-dump experiment reach, positron annihilation pushes the current limit on ε\varepsilon downwards by a factor of two in the range 33 MeV/c2<mA<120^2<m_{A^\prime}<120 MeV/c2^2.Comment: 9 pages, 7 figure

    The LRRK2 G2385R variant is a partial loss-of-function mutation that affects synaptic vesicle trafficking through altered protein interactions.

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    Mutations in the Leucine-rich repeat kinase 2 gene (LRRK2) are associated with familial Parkinson's disease (PD). LRRK2 protein contains several functional domains, including protein-protein interaction domains at its N- and C-termini. In this study, we analyzed the functional features attributed to LRRK2 by its N- and C-terminal domains. We combined TIRF microscopy and synaptopHluorin assay to visualize synaptic vesicle trafficking. We found that N- and C-terminal domains have opposite impact on synaptic vesicle dynamics. Biochemical analysis demonstrated that different proteins are bound at the two extremities, namely \u3b23-Cav2.1 at N-terminus part and \u3b2-Actin and Synapsin I at C-terminus domain. A sequence variant (G2385R) harboured within the C-terminal WD40 domain increases the risk for PD. Complementary biochemical and imaging approaches revealed that the G2385R variant alters strength and quality of LRRK2 interactions and increases fusion of synaptic vesicles. Our data suggest that the G2385R variant behaves like a loss-of-function mutation that mimics activity-driven events. Impaired scaffolding capabilities of mutant LRRK2 resulting in perturbed vesicular trafficking may arise as a common pathophysiological denominator through which different LRRK2 pathological mutations cause diseas

    AN IN VIVO MODEL OF HYPERACUTE REJECTION: CHARACTERIZATION AND EVALUATION OF THE EFFECT OF TRANSGENIC HUMAN COMPLEMENT INHIBITORS

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    Hyperacute rejection (HAR) occurring after transplantation within phylogenetically distant species is a severe reaction triggered by preexisting xenoreactive antibodies and complement activation, leading to the destruction of the donor organ. Expression of human complement inhibitors in transgenic pig organs prolongs the survival of xenograft in experimental models. Moreover, the extent of protection from hyperacute rejection is dependent on the level and site of expression of the transgenic molecules and, probably, on the combination of different molecules. In this regard a small animal model to test the efficacy of expression vectors and different human molecules could be very advantageous. A murine model developed in our laboratory was characterized by measurement of several parameters characteristic of HAR in the livers of control and transgenic mice expressing transgenic human DAF (CD55) or MCP (CD46) at the end of 2 h of perfusion with human plasma and after 1 day. The parameters studied were heamatological values of hepatic functions (GOT and GPT), induction of pro-inflammatory molecules and histopathological evaluation. Cytokines (IL-1 alpha, IL-1 beta, IL-6) induction and exposure of P-selectin on the endothelial cell surface, was only observed in control animals after 2 h of perfusion, as an early event. GOT and GPT values increase drammatically after 2 h perfusion and 1 day after the treatment according to the histopathological observation of liver damage. On the contrary, the livers of hDAF or hMCP transgenic mice, under the same treatment were significantly protected although the extent of this protection is dependent on the level of expression of transgenic human molecules

    Avaliação do projeto minibibliotecas no Semiárido do Nordeste e no Vale do Jequitinhonha, MG: uma pesquisa-ação.

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    Introdução; As minibibliotecas no contexto da leitura e do aprendizado; Metodologia; Análise e discussão dos dados.bitstream/item/83404/1/Avaliacao-do-projeto-minibibliotecas.pd

    Cells

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    Via activation of the cannabinoid type-1 (CB1) receptor, endogenous and exogenous cannabinoids modulate important biochemical and cellular processes in adipocytes. Several pieces of evidence suggest that alterations of mitochondrial physiology might be a possible mechanism underlying cannabinoids’ effects on adipocyte biology. Many reports suggest the presence of CB1 receptor mRNA in both white and brown adipose tissue, but the detailed subcellular localization of CB1 protein in adipose cells has so far been scarcely addressed. In this study, we show the presence of the functional CB1 receptor at different subcellular locations of adipocytes from epididymal white adipose tissue (eWAT) depots. We observed that CB1 is located at different subcellular levels, including the plasma membrane and in close association with mitochondria (mtCB1). Functional analysis in tissue homogenates and isolated mitochondria allowed us to reveal that cannabinoids negatively regulate complex-I-dependent oxygen consumption in eWAT. This effect requires mtCB1 activation and consequent regulation of the intramitochondrial cAMP-PKA pathway. Thus, CB1 receptors are functionally present at the mitochondrial level in eWAT adipocytes, adding another possible mechanism for peripheral regulation of energy metabolism. © 2022 by the authors.Role du recepteur CB1 mitocondriel du tissue adipeux dans la regulation de la balance energetiqueVieillissement et démence: un rôle hormonal?Development of pregnenolone derivatives as allosteric inhibitors of CB1 cannabinoid receptors for thetreatment of schizophrenia and psychotic syndrome

    Captorhinid reptiles from the lower Permian Pedra de Fogo Formation, Piauí, Brazil: the earliest herbivorous tetrapods in Gondwana

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    The Pedra de Fogo Formation in the Parnaíba Basin of northeastern Brazil hosts a recently discovered lacustrine fauna and provides the only known record of the Captorhinidae in South America. Here, new captorhinid remains from this unit are described. Two partial mandibles, including one formerly ascribed to the genus Captorhinus, are here referred to Captorhinikos sp. a genus previously described from North America. The natural mould of a large mandible probably represents a new taxon within the captorhinid subclade Moradisaurinae, and a small skull roof is regarded as Captorhinidae indet. Captorhinids are generally considered to have been herbivores or omnivores. The Pedra de Fogo captorhinids likely played an important ecological role as primary consumers in the palaeoenvironment of this geological unit, which is also known for its extensive record of petrified forests. The new finds reinforce the close relationships between the continental faunas of palaeotropical western Gondwana and palaeoequatorial North America during the Cisuralian
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