The Nucleocapsid Region of HIV-1 Gag Cooperates with the PTAP and LYPXnL Late Domains to Recruit the Cellular Machinery Necessary for Viral Budding

HIV-1 release is mediated through two motifs in the p6 region of Gag, PTAP and LYPXnL, which recruit cellular proteins Tsg101 and Alix, respectively. The Nucleocapsid region of Gag (NC), which binds the Bro1 domain of Alix, also plays an important role in HIV-1 release, but the underlying mechanism remains unclear. Here we show that the first 202 residues of the Bro1 domain (Broi) are sufficient to bind Gag. Broi interferes with HIV-1 release in an NC–dependent manner and arrests viral budding at the plasma membrane. Similar interrupted budding structures are seen following over-expression of a fragment containing Bro1 with the adjacent V domain (Bro1-V). Although only Bro1-V contains binding determinants for CHMP4, both Broi and Bro1-V inhibited release via both the PTAP/Tsg101 and the LYPXnL/Alix pathways, suggesting that they interfere with a key step in HIV-1 release. Remarkably, we found that over-expression of Bro1 rescued the release of HIV-1 lacking both L domains. This rescue required the N-terminal region of the NC domain in Gag and the CHMP4 binding site in Bro1. Interestingly, release defects due to mutations in NC that prevented Bro1 mediated rescue of virus egress were rescued by providing a link to the ESCRT machinery via Nedd4.2s over-expression. Our data support a model in which NC cooperates with PTAP in the recruitment of cellular proteins necessary for its L domain activity and binds the Bro1–CHMP4 complex required for LYPXnL–mediated budding

Erosão hídrica pós-plantio em florestas de eucalipto na bacia do rio Paraná, no leste do Mato Grosso do Sul

Nas regiões tropicais, o desgaste provocado no solo por ação das águas da chuva, ou seja, a erosão hídrica é a mais importante forma de degradação do solo. Visto que os plantios florestais de eucalipto estão inseridos em ecossistemas sensíveis às perturbações antrópicas em razão de ocorrência de plantações em solos com baixos teores de argila, com baixa fertilidade natural e grande parte das plantações estabelecidas em antigas áreas agrícolas e de pastagens degradadas, surge a necessidade do entendimento dos processos que regem a erosão hídrica e suas relações com as perdas de solo e água nos sistemas florestais. Objetivaram-se com este trabalho calcular os valores de erosividade da chuva (fator R - EI30), estimar a tolerância de perda de solo (T) para as classes representativas nas áreas de estudo, avaliar as perdas de solo e água por erosão hídrica e verificar a influência, por meio de análise de componentes principais (ACP), de atributos físicos e matéria orgânica do solo sobre a erosão hídrica em florestas de eucalipto no estádio de pós-plantio. Os tratamentos constituíram de diferentes sistemas de manejo dos resíduos e da disposição de plantio (nível e desnível), em dois biomas distintos, Cerrado e Floresta, e solo descoberto. Os solos foram classificados como Latossolo Vermelho distrófico típico textura média-alta fase floresta (LVd1) e Latossolo Vermelho distrófico típico textura média-baixa fase cerrado (LVd2). O estudo foi realizado em áreas experimentais de plantio de eucalipto localizadas no município de Três Lagoas, na bacia do Rio Paraná, no leste do Mato Grosso do Sul. O índice de erosividade anual obtido foi de 6.792,7 MJ mm ha-1 h-1 ano-1. Os valores de T variaram de 9,0 a 11,0 Mg ha-1 ano-1, para o LVd2 e LVd1, respectivamente. As perdas de solo apresentaram valores em torno de 0 a 0,505 Mg ha-1 no LVd1 e de 0 a 0,853 Mg ha-1, no LVd2. A ACP evidenciou-se eficiente na discriminação dos sistemas de manejo em razão da interação entre os atributos físicos e matéria orgânica do solo e suas relações com a erosão hídrica, possibilitando visualizar de forma clara a influência do manejo sobre esses atributos e a relação de ambos com as perdas de solo e água

Dependence of pancreatic enzyme secretion on extracellular Ca⁺⁺ and its modification by cyclic nucleotides and thyrocalcitonin

Pancreatic enzyme secretion of the same magnitude as that evoked by the hormones pancreozymin or acetylcholine, can be elicited by CaCl2 injections into the pancreatic arteries. Injections of CaCl2 together with dibutyryl adenosine 3'5' cyclic monophosphate (dbcAMP) or dibutyryl guanosine 3'5' cyclic monophosphate (dbcGMP) produces a greater effect on enzyme output than injection of either substance alone. During a background infusion of low doses of acetylcholine plus atropine, injections of the same doses of CaCl2 cause a higher enzyme output than injection of CaCl2 without acetylcholine plus atropine. The effect of CaCl2 injections was also enhanced during theophylline infusion. These findings indicate that cAMP or cGMP, or both are involved in the mechanism of enzyme secretion, and that Ca++ and cyclic nucleotides together have a synergistic action on the target, and are probably the key substances in eliciting enzyme secretion. Thyrocalcitonin inhibits the enzyme secretion induced either by pancreozymin injection, by acetylcholine injection or by rapid elevation of external Ca++. As the effect of CaCl2 injections is more markedly inhibited by thyrocalcitonin than the effect of the hormones, it is suggested that thyrocalcitonin inhibits the passive influx of Ca++ into the cell

Untersuchungen zur Gewaesserbeschaffenheitsentwicklung der Spree. Teilprojekt 5.3: Aufbau eines gekoppelten Oberflaechenwasser-Grundwassermodells und seine Reduktion zu einem konzeptionellen Blockmodellsystem am Beispiel Baerwalde Schlussbericht

SIGLEAvailable from TIB Hannover: F03B844+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Adapting to Climate Change in Urban Water Management: Flood Management in the Rotterdam–Rijnmond Area

Many large coastal cities are located in deltas, which makes them vulnerable to floods. In many cities flood damage has increased due to increases in population and assets, and this process is expected to continue. At the same time, climate change will cause floods to occur more often in many rivers and deltas due to higher discharges and sea level rise. These trends call for the development and implementation of new technologies and strategies in flood risk management. This call is also acknowledged in the Netherlands, a country that has a strong history of relying on structural measures. The city of Rotterdam includes many unembanked areas, large parts of which will be redeveloped in the near future. Current practice is to elevate all unembanked areas to a 1 in 4,000 years flood level. This is not only very costly, but also causes problems when an area is redeveloped in phases, or when existing buildings will remain as both cause unwanted elevation differences and differences in flood protection. Rotterdam is therefore looking for adaptive (non-structural) measures to decrease flood damage in these areas. Such measures are presently little used in the Netherlands. One key question is how these new measures fit in within current policies, laws, and regulations in Rotterdam. This chapter describes measures studied for a case study area in Rotterdam, gives an analysis of the policies, laws, and regulations relating to these measures, and examines the implications for urban flood management. Our research shows that, in principle, the rules do allow for implementation of adaptive measures. It is, however, problematic how these measures can be enforced, and this weakness can cause problems, e.g. when not all waterfront buildings are dry-proofed. Better communication of flood risks is recommended, as this will increase awareness and preparedness, which in turn might lead to a higher implementation rate of adaptive measures.</p