RESUMO
Plant atmospheric CO2 fixation depends on the aperture of stomatal pores at the leaf epidermis. Stomatal aperture or closure is regulated by changes in the metabolism of the two surrounding guard cells, which respond directly to environmental and internal cues such as mesophyll-derived metabolites. Sucrose has been shown to play a dual role during stomatal movements. The sucrose produced in the mesophyll cells can be transported to the vicinity of the guard cells via the transpiration stream, inducing closure in periods of high photosynthetic rate. By contrast, sucrose breakdown within guard cells sustains glycolysis and glutamine biosynthesis during light-induced stomatal opening. Here, we provide an update regarding the role of sucrose in the regulation of stomatal movement highlighting recent findings from metabolic and systems biology studies. We further explore how sucrose-mediated mechanisms of stomatal movement regulation could be useful to understand evolution of stomatal physiology among different plant groups.
Assuntos
Estômatos de Plantas/metabolismo , Sacarose/metabolismo , Metabolismo dos Carboidratos/genética , Metabolismo dos Carboidratos/fisiologia , Células do Mesofilo/metabolismo , Fotossíntese/fisiologia , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismoRESUMO
Combining electrochemical methods, in situ scanning tunneling microscopy, and surface x-ray diffraction allowed study of the structure and kinetics of S/Au(111) electrodes in aqueous electrolytes under potential control. Integrated intensities of a particular crystal truncation rod at anti-Bragg conditions were used to trace the sulfur adsorption and desorption as a function of electrode potential in real time. The S desorption is a first order process and the adsorption follows a Langmuir isotherm. A weakly bound S layer is found on the surface before charge transfer, and then specific adsorption occurs.
RESUMO
Histoplasmosis is a fungal disease caused by the dimorphous fungus Histoplasma capsulatum (Hc). Cyclophosphamide (Cy) was used as an immunomodulator capable of modifying the course of the disease, as well as of regulating the mechanisms involved in T-lymphocyte mediated immune response. Rats were subjected to intracardiac inoculation of Hc followed by a fractionated treatment with a 100 mg/kg body weight dose of Cy on days +4, +5, +6, +7 and +11 pi. Until day 26 pi, treatment with Cy caused 85% mortality whereas no mortality was observed among animals only inoculated with Hc. On day 14 pi, the group of Hc animals showed a delayed hypersensitivity test (DH) of 26.60 + 13.96 as determined by the swelling of the leg. Conversely, DH was significantly depressed in rats inoculated with Hc and treated with Cy: 3.88 +/- 1.00 (p < 0.01). Colony forming units count in this group was 2020 CFU/g of spleen, and 24 CFU/g of spleen (p < 0.01) in controls. A macroscopic study of the organs revealed that the animals in the Hc+Cy group had spleenomegaly and lungs with granuloma and hemorrhagic spots. The controls only presented small lung abscesses. These findings lead to the conclusion that Cy causes a deterioration of cell mediated immune response which results in the manifestation of an acute, fatal experimental mycosis.
Assuntos
Ciclofosfamida/uso terapêutico , Histoplasmose/tratamento farmacológico , Imunossupressores/uso terapêutico , Animais , Masculino , Ratos , Ratos Endogâmicos BUF , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologiaRESUMO
The goal of this work was to develop in solid medium a fast method to obtain Paracoccidioides brasiliensis (Pb) with a high yield. Four culture media were assayed: Sabouraud honey-agar, Sabouraud dextrose-agar, tomato -agar-medium (TOM) and a medium based on grape pulp. The most exhuberant growth was observed in medium based on grape pulp. Antigen was prepared in microscale at 6, 10 and 15 days incubation of solid cultures and the crude product concentrated by means of Centriplus tubes (Helena, France). Isolated antigens were subjected to polyacrylamide gel electrophoresis, followed by immunolabelling and detection of the characteristic gp45 antigen employing human and Pb-infected rat sera. Best results were observed after 10 days culture in grape medium. None of the other three media afforded comparable results.
RESUMO
Rope-pumps are now widely promoted as a low cost, easily maintained means to improve water availability in developing countries. However, in some instances their acceptance has been limited by concerns over the microbiological quality of the water. This study looked at the well water quality under a variety of conditions, comparing unimproved bucket and rope wells with wells with a windlass and rope-pump wells with and without a concrete cover. Other factors influencing the water quality were also examined. Results indicate a 62% reduction of the geometric mean of the faecal coliform contamination of the well water as a result of the installation of a rope-pump with or without a concrete cover. Other factors found to influence the level of contamination of water in hand-dug wells were rainfall, number of households using the well, amount of water extracted daily and the distance of the well from the nearest kitchen. The last three factors probably reflect domestic activities with poor hygiene around the well. The installation of a simple rope-pump on family wells improves the water quality and availability at a favourable cost/benefit ratio.
Assuntos
População Rural , Microbiologia da Água , Abastecimento de Água , Enterobacteriaceae/isolamento & purificação , Humanos , Nicarágua , Distribuição Aleatória , Fatores Socioeconômicos , Abastecimento de Água/estatística & dados numéricosRESUMO
The goal of this work was to develop in solid medium a fast method to obtain Paracoccidioides brasiliensis (Pb) with a high yield. Four culture media were assayed: Sabouraud honey-agar, Sabouraud dextrose-agar, tomato -agar-medium (TOM) and a medium based on grape pulp. The most exhuberant growth was observed in medium based on grape pulp. Antigen was prepared in microscale at 6, 10 and 15 days incubation of solid cultures and the crude product concentrated by means of Centriplus tubes (Helena, France). Isolated antigens were subjected to polyacrylamide gel electrophoresis, followed by immunolabelling and detection of the characteristic gp45 antigen employing human and Pb-infected rat sera. Best results were observed after 10 days culture in grape medium. None of the other three media afforded comparable results.
Assuntos
Antígenos de Fungos/isolamento & purificação , Meios de Cultura , Paracoccidioides/imunologia , Ágar , Animais , Meios de Cultura/química , Eletroforese em Gel de Poliacrilamida , Glucose , Humanos , Imunodifusão , Peso Molecular , Paracoccidioides/crescimento & desenvolvimento , Paracoccidioidomicose/sangue , Paracoccidioidomicose/imunologia , RatosRESUMO
The goal of this work was to develop in solid medium a fast method to obtain Paracoccidioides brasiliensis (Pb) with a high yield. Four culture media were assayed: Sabouraud honey-agar, Sabouraud dextrose-agar, tomato -agar-medium (TOM) and a medium based on grape pulp. The most exhuberant growth was observed in medium based on grape pulp. Antigen was prepared in microscale at 6, 10 and 15 days incubation of solid cultures and the crude product concentrated by means of Centriplus tubes (Helena, France). Isolated antigens were subjected to polyacrylamide gel electrophoresis, followed by immunolabelling and detection of the characteristic gp45 antigen employing human and Pb-infected rat sera. Best results were observed after 10 days culture in grape medium. None of the other three media afforded comparable results.