16 research outputs found

    Do we need gastric acid?

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    Evidence from comparative anatomy and physiology studies indicates that gastric acid secretion developed during the evolution of vertebrates approximately 350 million years ago. The cellular mechanisms that produce gastric acid have been conserved over the millennia and therefore proton pump inhibitors have pharmacological effects in almost all relevant species. These observations suggest that gastric acid provides an important selective advantage; however, in modern-day humans the need for gastric acid can be questioned in light of the widespread use of safe and effective pharmacologic acid suppression. The Kandahar Working Group addressed questions concerning the need, production and effects of gastric acid, specifically: (1) motility in the upper gastrointestinal (GI) tract; (2) neuroendocrine factors; (3) digestive and mucosal processes; (4) microbiology, and (5) central processes and psychological involvement. We addressed each topic with the individual models available to answer our questions including animal versus human studies, pharmacologic, surgical as well as pathophysiologic states of acid suppression

    Invasive alien plants in the Pampas grasslands: a tri-national cooperation challenge

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    The challenge of managing biological invasions requires novel approaches and coordinated efforts, especially among countries linked by intense trade routes and sharing common biomes. This is the case in Southern South America, where Argentina, Brazil and Uruguay maintain intense commercial relationships, whilst sharing continuous portions of the Pampas grasslands. Transnational similarities in this case exceed ecological features, including a common colonization history and similar development trends. This study represents a tri-national cooperation effort to describe the alien plant flora invading the Pampas grasslands of Argentina, Brazil and Uruguay and analyses their characteristics in order to detect species and traits that are shared among the three countries and those that have not yet managed to invade the whole region. Furthermore, we highlight the opportunities and needs of a common approach across countries to deal with plant invasions. Information about alien plant species was retrieved from the IABIN Invasives Information Network (I3N) project databases of Argentina, Brazil and Uruguay, complemented with some national herbaria. Three hundred and fifty-six alien plant species were recorded growing in natural or semi-natural habitats of the Pampas. A total of 50 species were found in Pampas grasslands of the three countries. Argentina shared 48 and 36 species with Brazil and Uruguay, respectively, while the Brazilian and the Uruguayan Pampas shared only 20 species. Poaceae, Asteraceae and Fabaceae were the families with the highest number of invasive species, and herbs were the most common life form (75 %). Most invasive plants originated from Europe, Asia and Africa, and almost one-quarter of the species is associated with some human use, especially gardening. We discuss the opportunities and needs for international cooperation, as the prevention of introductions from one country to another through the use of risk analysis tools, definition of priority invasive species, as well as the detection, containment, eradication and control of common invasions. Furthermore, we suggest the establishment of coherent regional legislation and the inclusion of social issues and the public perception in the biological invasion quest.Fil: Fonseca, Carlos. Universidade Federal do Rio Grande do Norte; BrasilFil: Guadagnín, Demetrio Luis. Universidade Federal de Santa Maria; BrasilFil: Emer, Carine. University of Bristol; Reino UnidoFil: Masciadri Bálsamo, Silvana. Universidad de la República; UruguayFil: Germain, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; ArgentinaFil: Zalba, Sergio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Grupo de Estudios en Conservación y Manejo; Argentin

    Metabolism and regulation of canonical histone mRNAs: life without a poly(A) tail

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    The canonical histone proteins are encoded by replication-dependent genes and must rapidly reach high levels of expression during S phase. In metazoans the genes that encode these proteins produce mRNAs that, instead of being polyadenylated, contain a unique 3' end structure. By contrast, the synthesis of the variant, replication-independent histones, which are encoded by polyadenylated mRNAs, persists outside of S phase. Accurate positioning of both histone types in chromatin is essential for proper transcriptional regulation, the demarcation of heterochromatic boundaries and the epigenetic inheritance of gene expression patterns. Recent results suggest that the coordinated synthesis of replication-dependent and variant histone mRNAs is achieved by signals that affect formation of the 3' end of the replication-dependent histone mRNAs
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