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51.
This work shows that unsaturated fatty acids enhance the epinephrine-stimulated adenylate cyclase activity in bovine retina. The modulating effect on the epinephrine-stimulated formation of cyclic AMP seems to be linked to the degree of unsaturation of the fatty acid. Treatment of the intact retina with docosahexaenoic acid in the concentration range 0.5 X 10(-6)-1 X 10(-3) M does not affect the enzyme activity measured in the absence of the hormone but markedly increases the cyclase activity when the tissue is incubated in the presence of 0.1 mM epinephrine. Docosahexaenoic acid enhances the maximal response to epinephrine without affecting the apparent ED50 value for this effector. Docosahexaenoic acid at 0.5 mM also increases the hormone-stimulated adenylate cyclase activity in retinal cell-free homogenate, whereas it has no effect on the epinephrine-sensitive enzyme solubilized from the membrane fraction with 1% Triton X-305. When docosahexaenoic acid-preincubated intact retina and cell-free homogenate are incubated in the presence of defatted albumin, both the observed activating effect of the fatty acid on the epinephrine-stimulated adenylate cyclase activity and the enhancement of the enzyme response to the hormone significantly diminish.  相似文献   
52.
A case of primary pulmonary non-Hodgkin's lymphoma is presented. On this occasion, the lymphoma invaded the myocardium, an event which has not previously been reported in the literature. These neoplasms spread by proximity, and invasion of the pericardium, thoracic wall and oesophagus have been described. Our patient died from heart failure. Tumour myocardial infiltration may well have been the determinant cause through various mechanisms, including a decrease in myocardial contractility. Spread into the myocardium may be facilitated by bulky tumour infiltrates in the pleural space.  相似文献   
53.
Tachinids are usually considered as koinobionts as none of them kills or paralyzes the host when first entering it. These parasitoids, however, do not fit well into the koinobiont/idiobiont dichotomy because only some species show a high degree of physiological adaptation to the host, whereas the larvae of other species grow quickly following attack and kill the host rapidly, thus behaving more as idiobionts. The in vitro rearing technique provides further evidence for the poor adequacy of the koinobiont/idiobiont dichotomy for tachinids. In fact, while typical koinobionts are known to be difficult to culture on artificial media, some tachinids displaying non-synchronized development with the host have been successfully reared in vitro on insect material-free artificial media, thus behaving similarly to idiobionts. I therefore suggest not to use the koinobiont/idiobiont classification for tachinids and to class them instead only on the basis of the presence or absence of developmental synchrony with their hosts.  相似文献   
54.
Introduction – The cobalt is an essential element for leguminous plants but may be harmful for other species; for that reason determination of Co(II) is very important for the management of polluted areas and for discover plants with capacity for the hyperaccumulation of heavy metals, which has produced a growing necessity of fast, sensitive and selective analytical techniques. Objective – To develop an analytical procedure for the determination of cobalt in plant tissue by coupling the ionic chromatography to the luminol‐based chemiluminescence detection. Methodology – The sample was digested in a mixture of concentrated nitric acid and hydrogen peroxide, using an microwave oven to dissolve the Co(II). The solution containing Co(II) ions was injected to an ionic chromatograph using oxalic acid as the eluent. The detection was based on the catalytic effect of Co(II) on the luminol chemiluminescence using perborate or percarbonate as oxidants. Experimental variables, such as concentrations, pH, flow rates and acid digestion conditions were optimised. Results – Well‐resolved chromatographic peaks were obtained. The height and area showed linear dependences with the Co(II) concentration, which were used to quantify the heavy metal, with recoveries up to 95%. The microwave irradiation (60 s) was sufficient for the complete mineralisation of 200 mg of sample, employing 2 mL of the acid mixture. The method was free from the interferences, requiring less than 12 minutes to complete the analysis. Conclusion – The method was simple and rapid for the determination of cobalt in plant tissue with detection limits comparable to those obtained with more sophisticated and expensive analytical equipments. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
55.
Two wastewater natural reclamation systems (WWNRS) have been compared regarding their efficiencies on faecal bacteria removal and the persistence of enteric pathogens. These WWNRS are constituted of a combination of anaerobic treatment, small sub-surface flow constructed wetland refilled of volcanic ashes and a final pond as water reservoir. Faecal coliforms, enterococci, Escherichia coli, Clostridium perfringens, somatic coliphages, Salmonella sp., Campylobacter sp., Cryptosporidium sp., Giardia sp. and helminth eggs were analyzed in constructed wetlands inlet and outlet and storage pond effluent. Low numbers of protozoan positive samples (4.54% in Albergue de Bolico for both protozoa, and 19.05% in Carrizal Alto for Giardia sp.) and absence of helminth eggs were found. Both systems demonstrated efficient reduction of faecal contamination indicators in the wastewaters (removal rates values of 2 log10). The natural systems for wastewater treatment used to be efficient in Salmonella abatement, this fact was confirmed in the reported systems, since enterobacteriaceae were found in only one of the effluents. Campylobacter species associated with the access of animals to storage ponds were detected in the reclaimed water.  相似文献   
56.
The aerial parts of Genista pichisermolliana Valsecchi (Fabaceae), an endemic plant of Sardinia, were extracted in Soxhlet apparatus and purified by several chromatographic methods. The new compound alpinumisoflavone 4′-O-glucopyranoside (6) was isolated together with nineteen flavonoids, p-coumaric methylester and d-pinitol, while no alkaloids were detected. All the chemical structures were elucidated by spectroscopic analysis. Since flavonoids represent the main constituents of this plant, the total flavonoid content was determined according to the Italian Pharmacopoeia IX Ed. method.  相似文献   
57.
The disappearance of frugivorous primates in fragmented forests can potentially lower the rates of seed dispersal and recruitment of endozoochorous tree species, thus altering plant community structure. We quantified seedling density for 7 tree species that are common in the feces of mantled howlers (Alouatta palliata) in 6 rain forest fragments in northern Chiapas, Mexico. Howlers were present in 3 of the fragments and absent in the other 3. We compared seedling density in primate sleeping sites in inhabited fragments with control sites, which were structurally similar to sleeping sites but where we did not find monkey feces, in both inhabited and uninhabited fragments. For each tree species, we determined the relationship between seedling density and the local density of seeds and adult trees. In fragments where howlers were present, seedling density for 4 of the focal tree species (Brosimum alicastrum, Dialium guianense, Manilkara zapota, and Nectandra ambigens) was greater in sleeping sites than in control sites found in the same fragments. Moreover, seedling density of Dialium guianense was greater in the control sites of fragments inhabited by howlers than in fragments where this primate is absent. Seedling density of these 4 species correlates positively with seed density on the forest floor; however, we observed no correlations between seedling density and the density of adult trees. Our results suggest that the diversity of the seedling community of tree species dispersed by howlers may decline in fragments where this seed disperser is absent. These findings, together with the fact that only 5% of the study region is currently covered by forest and 81% of the forest remnants are uninhabited by mantled howlers, suggest that the potential long-term recovery of associated populations of tropical tree species dispersed by this primate species is highly uncertain. Conservation and restoration efforts should be aimed at restoring or replacing the ecological role played by this important seed disperser in the region.  相似文献   
58.
The objective of the present study was to determine the influence of potassium deprivation on the halophyte species Hordeum maritimum grown in hydroponics for 2 weeks. Treatments were with potassium (+K) or without potassium (−K). Growth, water status, mineral nutrition, parameters of oxidative stress [malondialdehyde (MDA), carbonyl groups (C=O), and hydrogen peroxide concentration (H2O2) contents], antioxidant enzyme activities [superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), guaiacol peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate peroxidase (MDHAR, EC 1.6.5.4), dehydroascorbate peroxidase (DHAR, EC 1.8.5.1), and glutathione reductase (GR, EC 1.6.4.2)], and antioxidant molecules [ascorbate (ASC), and glutathione (GSH)] were determined. Results showed that the growth of vegetative organs decreased owing to potassium deficiency with roots (−36%) more affected than shoots (−12%). Water status was only diminished in roots (reduction of 24%). Potassium deprivation decreased potassium concentration in both organs, this decrease was more pronounced in roots (−81%) than in shoots (−55%). In contrast to carbonyl groups, MDA content increased owing to potassium deprivation. Except for CAT activity that remained unaffected; SOD, GPX, APX, GR, MDHAR, and DHAR activities were significantly increased. H2O2 concentration was negatively correlated with the activities of enzymes and the accumulation of non-enzymatic antioxidants implicated in its detoxification. In conclusion, a cooperative process between the antioxidant systems is important for the tolerance of H. maritimum to potassium deficiency.  相似文献   
59.
In the last decade efforts have been carried out by the scientific community aimed at building integrated frameworks to support the decision-making process when sustainability issues are addressed. This paper proposes a further advancement in integrated assessment procedures by setting up an operational multi-scale and transparent framework, which comprises the assessment of European regions in terms of sustainability, and the identification of the impact that policy options might have on the sustainability of these regions. The framework is designed for use in ex ante sustainability impact assessment of policy scenarios on multifunctionality of land use and integrates economic, environmental and social issues across a variety of sectors (agriculture, forestry, transport, tourism and energy). The proposed method provides a conceptual framework applicable at different scales (European, regional), and takes into account the great variability of European regions. The described methodology is based on linear additive models to weight and aggregate selected indicators to a set of land use functions identified to describe the goods and services provided by the different land uses that summarise the most relevant economic, environmental and social issues of a region. The framework is designed to allow the evaluation of impacts at an international scale (e.g. the European Union), or on selected regions.The aggregation framework can be used to evaluate the impact that policy options have on the sustainability of multifunctional land use systems with competing demands. A conceptual envelope, called the “trade-off evaluation space”, delineates all possible developments in the functions of the land. The sustainability limits identify the subset of ‘acceptable’ policy options within the trade-off evaluation space, so that the distance of each land use function from sustainability limits can be estimated and trade-offs between the different functions of the multifunctional land use system can be identified. The proposed methodology is adaptable to different contexts: if the assumption is taken that all land use functions are equally weighted the framework can be used to analyse policy cases and take decisions on policy options at the European or regional level. However, at the local-scale the framework can also be applied through a participatory approach and the distribution of weights can be rediscussed with local stakeholders. In both cases the proposed system can be used as a tool for discussion among all interested parties.  相似文献   
60.
Anthropogenic stress on the earth’s ecosystems has resulted in widespread prevalence of ecosystem distress syndrome, a quantifiable set of signs of ecosystem degradation. At the same time, the planet is witnessing rapid declines in global cultural diversity and in the vitality of the world’s cultures, which closely mirror, and are interrelated with, ecological degradation. As a consequence of this converging crisis of loss of ecosystem and cultural health, global health and sustainability are increasingly under threat. An eco-cultural health perspective based on understanding the linkages between human activities, ecological and cultural disruption, and public health is essential for addressing these threats and achieving global sustainability.  相似文献   
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