An increase in nitric oxide produced by rat peritoneal neutrophils is not involved in cell apoptosis

Polymorphonuclear neutrophils (PMN) obtained from carrageenin-stimulated peritoneal cavities of rats, but not blood PMN, spontaneously produced nitric oxide (NO) when incubated in vitro. Incubation of the cells with the NO synthase inhibitors, L-imino-ethyl-L-ornithine (L-NIO) or NG-monomethyl-L-arginine (L-NMMA), inhibited NO production. This inhibition could be reversed by L-arginine. Incubation of PMN with lipopolysaccharide (LPS) failed to enhance NO production. Pretreatment of the rats with dexamethasone (DEXA) prior to carrageenin injection or incubation of PMN with the glucocorticoid in vitro partially inhibited the spontaneous release of NO. On the other hand, when PMN obtained from DEXA pretreated rats were incubated in vitro with DEXA, NO synthase activity and hence NO generation were almost abolished. A similar inhibition was also observed following the addition of L-NIO or cycloheximide to cultures of carrageenin-elicited PMN. The NO production by PMN did not appear to be related to cell viability or apoptosis. Indeed, neither the blockade of NO generation by L-NIO nor the incubation of the neutrophils with a NO donor, S-nitroso-acetylpenicillamine (SNAP) modified the pattern of LDH release or DNA fragmentation. In summary, it appears that PMN migration triggers a continuous NO synthesis, and that NO produced by these cells is not related to their apoptosis

Remanescentes da Mata Atlântica no Estado do Rio de Janeiro: distribuição dos fragmentos e possibilidades de conexão.

This work is part of the Strategies and Actions for Biodiversity Conservation of Atlantic Forest Project supported by Critical Ecosystem Partnership Fund and was developed in Rio de Janeiro State, Brazil, which has only 20,33% of its area covered by vegetation, in a fragmented landscape The objective is to identify areas in Rio de Janeiro state that the conservation is more propitious or critical. For this, it was applied spatial analysis to know the distribution of vegetation patches and the connection possibilities based on the diversity of the land use matrix and its permeability. It was observed that 25% of the remaining vegetation of the state is isolated of any reserve and the great part of them is in the Semi-deciduous seasonal forest region, where the conditions are more critical due to the smaller size ofpatches and their isolation

Pagamento por serviços ambientais hídricos no Brasil: experiências iniciais e os desafios do monitoramento.

Ao avaliar os projetos de pagamentos por serviços ambientais (PSA) no Brasil, observase dificuldades recorrentes relacionadas à falta de consolidação das metodologias para a seleção de áreas prioritárias e, sobretudo, para o monitoramento das áreas de prestação de serviços. A estratégia de pagamentos por serviços ambientais é cada vez mais presente nas políticas ambientais, a partir de um reconhecimento da necessidade de novos mecanismos de estímulo à conservação e à manutenção de serviços essenciais à vida, como a provisão de água. A partir da análise das experiências vivenciadas em projetos de Pagamento por Serviços Ambientais (PSA) relacionado à água de alguns estados brasileiros, pretende-se proporcionar um panorama destas experiências, de maneira a identificar as tendências, os gargalos e, sobretudo, questões relacionadas às metodologias de monitoramento aplicadas

Pagamento por serviços ambientais hídricos no Brasil: experiências iniciais e os desafios do monitoramento.

Ao avaliar os projetos de pagamentos por serviços ambientais (PSA) no Brasil, observam-se dificuldades recorrentes relacionadas à falta de consolidação das metodologias para a seleção de áreas prioritárias e, sobretudo, para o monitoramento das áreas de prestação dos serviços. A estratégia de pagamentos por serviços ambientais é cada vez mais presente nas políticas ambientais, devido ao reconhecimento da necessidade de novos mecanismos de estímulo à conservação e à manutenção de serviços essenciais à vida, como a provisão de água. A partir da análise das experiências vivenciadas em projetos de Pagamento por Serviços Ambientais (PSA) relacionados à água de alguns estados brasileiros, o trabalho apresenta um panorama destas experiências, de maneira a identificar as tendências, os obstáculos enfrentados e, sobretudo, os aspectos relevantes das metodologias de monitoramento aplicadas

Temperature variation under continuous light restores tomato leaf photosynthesis and maintains the diurnal pattern in stomatal conductance

The response of tomato plants (Solanum lycopersicum L. cv. Aromata) to continuous light (CL) in relation to photosynthesis, abscisic acid (ABA) and reactive oxygen species (ROS) was investigated to improve the understanding of the development and/or alleviation of CL-induced leaf injury in constant and diurnal temperature fluctuations with similar daily light integral and daily mean temperature. The plants were grown in three photoperiodic treatments for 15 days; One treatment with a 16/8 h light/dark period and a light/dark temperature of 27/17°C (Control), two CL treatments with 24 h photoperiods, one with a constant temperature of 24°C (CLCT) and the other one with variable temperature of 27/17°C for 16/8 ho, respectively (CLVT). A diurnal pattern of stomatal conductance (gs) and [ABA] was observed in the plants grown in the control and CLVT conditions, while the plants in CLCT conditions experienced a significant decrease in stomatal conductance aligned with an increase in ABA. The net photosynthesis (A) was significantly reduced in CLCT, aligned with a significant decrease in the maximum rate of Rubisco carboxylation (Vcmax), the maximum rate of electron transport (Jmax) and mesophyll diffusion conductance to CO2 (gm) in comparison to the control and CLVT. An increased production of H2O2 and O2•- linked with increased activities of antioxidative enzymes was seen in both CL treatments, but despite of this, leaf injuries were only observed in the CLCT treatment. The results suggest that the diurnal temperature fluctuations alleviated the CL injury symptoms, probably because the diurnal cycles of cellular mechanisms were maintained. The ROS were shown not to be directly involved in CL-induced leaf injury, since both ROS production and scavenging was highest in CLVT without leaf chlorotic symptoms

Diagnóstico do meio físico das bacias hidrográficas do entorno da Mata do Carvão (BHMC), Noroeste do Estado do Rio de Janeiro.

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