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991.
Patrícia F. Schuck Gustavo C. Ferreira Alana P. Moura Estela N.B. Busanello Anelise M. Tonin Carlos S. Dutra-Filho Moacir Wajner 《Neurochemistry international》2009,54(8):519-525
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most frequent disorder of fatty acid oxidation with a similar prevalence to that of phenylketonuria. Affected patients present tissue accumulation of the medium-chain fatty acids octanoate (OA), decanoate (DA) and cis-4-decenoate. Clinical presentation is characterized by neurological symptoms, such as convulsions and lethargy that may develop into coma and sudden death. The aim of the present work was to investigate the in vitro effect of OA and DA, the metabolites that predominantly accumulate in MCADD, on oxidative stress parameters in rat cerebral cortex homogenates. It was first verified that both DA and OA significantly increased chemiluminescence and thiobarbituric acid-reactive species levels (lipoperoxidation) and decreased the non-enzymatic antioxidant defenses, measured by the decreased total antioxidant capacity. DA also enhanced carbonyl content and oxidation of sulfhydryl groups (protein damage) and decreased reduced glutathione (GSH) levels. We also verified that DA-induced GSH decrease and sulfhydryl oxidation were not observed when cytosolic preparations (membrane-free supernatants) were used, suggesting a mitochondrial mechanism for these actions. Our present data show that the medium-chain fatty acids DA and OA that most accumulate in MCADD cause oxidative stress in rat brain. It is therefore presumed that this pathomechanism may be involved in the pathophysiology of the neurologic symptoms manifested by patients affected by MCADD. 相似文献
992.
For the removal of nutrients from eutrophic stream water polluted by non-point sources, an artificial aquatic food web (AAFW)
system comprising processes of phytoplankton growth and Daphnia magna grazing was developed. The AAFW system was a continuous-flow system constructed with one storage basin of 3 m3 capacity, one phytoplankton tank of 3 m3 capacity, and one zooplankton growth chamber of 1.5 m3 capacity. The system was optimized by setting hydraulic retention time of phytoplankton tank as 3 days and D. magna density as 740–1000 individual l−1. When the system was operated on eutrophic stream water that was delivering 471 g of total nitrogen (TN) and 29 g of total
phosphorus (TP) loadings for 45 days, 250 g (53%) of TN and 16 g (54%) of TP were removed from the water during its passage
through the phytoplankton tank. In addition, 64 g (14%) of TN and 4 g (13%) of TP were removed from the water by harvesting
zooplankton biomass in the zooplankton growth chamber, resulting in significant overall removal rates of TN (69%), nitrate
(78%), TP (73%), and dissolved inorganic phosphorus (94%). While the removal efficiency of the AAFW system is comparable to
those of other ecotechnologies such as constructed wetlands, its operation is less limited by the availability of space or
seasonal shift of temperature. Therefore, it was concluded that AAFW system is a highly efficient, flexible system for reducing
nutrient levels in tributary streams and hence nutrient loading to large aquatic systems receiving the stream water.
Handling editor: J. Padisak 相似文献
993.
It is essential to know the nutrient limitation status of biofilms to understand how they may buffer uptake and export of
nutrients from polluted watersheds. We tested the effects of nutrient additions on biofilm biomass (chlorophyll a, ash free dry mass (AFDM), and autotrophic index (AI, AFDM/chl a)) and metabolism via nutrient-diffusing substrate bioassays (control, nitrogen (N), phosphorus (P), and N + P treatments)
at 11 sites in the Upper Snake River basin (southeast Idaho, USA) that differed in the magnitude and extent of human-caused
impacts. Water temperature, turbidity, and dissolved inorganic N concentrations all changed seasonally at the study sites,
while turbidity and dissolved inorganic N and P also varied with impact level. Chl a and AI on control treatments suggested that the most heavily impacted sites supported more autotrophic biofilms than less-impacted
sites, and that across all sites biofilms were more heterotrophic in autumn than in summer. Nutrient stimulation or suppression
of biofilm biomass was observed for chl a in 59% of the experiments and for AFDM in 33%, and the most frequent response noted across all study sites was N limitation.
P suppression of chl a was observed only at the most-impacted sites, while AFDM was never suppressed by nutrients. When nutrient additions did have
significant effects on metabolism, they were driven by differences in biomass rather than by changes in metabolic rates. Our
study demonstrated that biofilms in southeast Idaho rivers were primarily limited by N, but nutrient limitation was more frequent
at sites with good water quality than at those with poor water quality. Additionally, heterotrophic and autotrophic biofilm
components may respond differently to nutrient enrichment, and nutrient limitation of biofilm biomass should not be considered
a surrogate for metabolism in these rivers.
Handling editor: D. Ryder 相似文献
994.
995.
The effects of fresh thalli, culture filtrate, water-soluble extract and dry powder of two species of macroalgae, Ulva pertusa (Chlorophyta) and Gracilaria lemaneiformis (Rhodophyta), on the growth of a bloom-forming microalga, Heterosigma akashiwo, were studied in co-culture under controlled laboratory conditions. Both fresh thalli and culture filtrate of U. pertusa and G. lemaneiformis, particularly in the form of fresh thalli, significantly inhibited microalgal growth; indeed, the microalga was completely
killed during the course of the experiment. A clear concentration-dependent relationship was observed between the initial
concentration of fresh thalli (either U. pertusa or G. lemaneiformis) and its inhibitory effect on H. akashiwo. Simultaneous nutrient assays showed that nitrate and phosphate were almost exhausted in G. lemaneiformis fresh thalli co-culture but remained well above nutrient limitation for microalgal growth in U. pertusa co-culture, in which the microalgal cells were completely killed. However, daily f/2 medium repletion would obviously alleviate
the growth inhibition in G. lemaneiformis co-culture. Since the present study was carried out under controlled conditions, fluctuations in environmental factors (i.e.,
light, temperature, carbon limitation, bacterial presence and pH) were limited during the experiment. We thus concluded that
allelopathy was the most likely explanation for microalgal growth inhibition in U. pertusa co-culture, while the combined roles of allelopathy and nutrient limitation were responsible for growth inhibition in G. lemaneiformis co-culture. Similarly, macroalgal water-soluble extracts and dry powders affected the co-cultured H. akashiwo greatly, with more obvious effects observed in water-soluble extract co-cultures. A dose-dependent relationship was also
observed over the course of the experiment. It can be concluded that macroalgal thalli contain some bioactive compounds. The
results of the present study suggest that U. pertusa and G. lemaneiformis, especially in the form of fresh thalli, effectively inhibit the growth of H. akashiwo and could thus be potential candidates for use in the control and mitigation of H. akashiwo blooms. 相似文献
996.
Nutrient content of tropical edible seaweeds, Eucheuma cottonii, Caulerpa lentillifera and Sargassum polycystum 总被引:2,自引:0,他引:2
Patricia Matanjun Suhaila Mohamed Noordin M. Mustapha Kharidah Muhammad 《Journal of applied phycology》2009,21(1):75-80
The proximate composition, vitamin C, α-tocopherol, dietary fibers, minerals, fatty acid and amino acid profiles of three
tropical edible seaweeds, Eucheuma cottonii (Rhodophyta), Caulerpa lentillifera (Chlorophyta) and Sargassum polycystum (Phaeophyta) were studied. The seaweeds were high in ash (37.15–46.19%) and dietary fibers (25.05–39.67%) and low in lipid
content (0.29–1.11%) on dry weight (DW) basis. These seaweeds contained 12.01–15.53% macro-minerals (Na, K, Ca and Mg) and
7.53–71.53 mg.100 g−1 trace minerals (Fe, Zn, Cu, Se and I). The crude protein content of E. cottonii (9.76% DW) and C. lentillifera (10.41% DW) were higher than that of S. polycystum (5.4% DW), and protein chemical scores are between 20 and 67%. The PUFA content of E. cottonii was 51.55%, C. lentillifera 16.76% and S. polycystum 20.34%. Eicosapentaenoic acid (EPA), accounted for 24.98% of all fatty acids in E. cottonii. These seaweeds have significant vitamin C (∼35 mg.100 g−1) and α-tocopherol (5.85–11.29 mg.100 g−1) contents. 相似文献
997.
Masazumi Kayama Kobayashi Makoto Mutsumi Nomura Kaichiro Sasa Takayoshi Koike 《Trees - Structure and Function》2009,23(1):145-157
Sakhalin spruce (Picea glehnii), a native species typically found in northern Japan, has been used in reforestation on hillsides exposed to strong winds.
In the reforestation areas, there are south-facing (S-slope) and northwest-facing slopes (NW-slope). Climatic conditions are
contrasting between the two slopes, with shallower snow cover on the S-slopes. We compared growth responses of the spruce
to micro-environment between the S- and NW-slopes through soil nutrients, needle longevity, water status, photosynthesis,
and nutrients in the needles. These parameters were measured in needles exposed above the snow in winter and in lower needles
protected by snow cover. High-position needles suffered from drought stress, especially in winter, and needles were shed early
in the year on both slopes. Low-position needles did not suffer from drought stress, and maintained a high photosynthetic
rate on both slopes. However, needle longevity was reduced on the S-slope, and concentrations of nitrogen, phosphorus, and
potassium in the needles decreased with needle age. Soil nutrient concentrations were low on the S-slope, which suggests that
the needles on the S-slope may remobilize nutrients from aged needles to younger needles prior to shedding. This characteristic
is probably an adaptation in Sakhalin spruce to poor soil conditions. 相似文献
998.
Vincenzo Rochira Lucia Zirilli Bruno Madeo Laura Maffei Cesare Carani 《The Journal of steroid biochemistry and molecular biology》2009,113(3-5):189-194
Androgens act on erythropoiesis, but the relative role of testosterone (T) and estradiol (E2) on erythropoietic parameters in men is a poorly investigated issue. In order to evaluate separately the effects on erythropoiesis of high-dose T administration alone and of physiological dose of E2 administration alone two adult men with aromatase deficiency were assessed before and during each treatment. Blood cell count, hemoglobin (Hb), hematocrit (Hct), erythrocyte mean cell volume (MCV), erythrocyte mean corpuscular hemoglobin (MCH), erythrocyte mean corpuscular hemoglobin concentration (MCHC), serum ferritin, iron and total iron-binding capacity (TIBC), serum erythropoietin, serum total testosterone and estradiol were evaluated. Hb, Hct and red cell count rose during testosterone treatment, consistently with the increase in circulating testosterone, but failed to increase during estradiol treatment. A decrease in Hb, Hct and red cell count was recorded in one of the two subjects during estradiol treatment, with a concomitant decrease in serum testosterone. Circulating T alone is capable of and sufficient to influence erythropoiesis, especially at supraphysiological dosage, while circulating E2 have not the same effect on erythropoietic parameters, suggesting the hypothesis that the erythropoietic changes induced by androgens are not mediated via its aromatization to estrogens. 相似文献
999.
The effects of 24-epibrassinolide (EBR) added to nutrient solution on growth of cucumber (Cucumis sativus L.) under root-zone hypoxia were investigated. Cucumber seedlings were hydroponically grown for 8 days in normoxic and hypoxic
nutrient solutions with and without addition of EBR at 1 μg l−1. EBR exerted little influence on plant performance in the normoxic nutrient solution, while the chemical alleviated root-zone
hypoxia-induced inhibition of root and shoot growth and net photosynthetic rate (Pn). EBR added to hypoxic nutrient solution
caused an increase in the concentration of fructose, sucrose, and total soluble sugars in the roots but not in the leaves.
Root-zone hypoxia enhanced the activities of lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), and pyruvate decarboxylase
in the roots. Interestingly, EBR further enhanced ADH activity but lowered LDH activity in hypoxic roots. These results suggest
that EBR added to hypoxic nutrient solution may stimulate the photosynthate allocation down to roots and the shift from lactate
fermentation to alcohol fermentation in hypoxic roots, resulting in the increase in ATP production through glycolysis and
the avoidance of cytosolic acidosis and eventually enhanced tolerance of cucumber plants to root-zone hypoxia. 相似文献
1000.
The Expression of Iron-repressible Outer Membrane Proteins in Helicobacter pylori and Its Association with Iron Deficiency Anemia 总被引:1,自引:0,他引:1
Background: Helicobacter pylori infection is known to be a cause of iron deficiency anemia (IDA) that is unresponsive to iron supplements. H. pylori bind iron to a specific receptor by iron-repressible outer membrane proteins (IROMPs) under conditions of restricted iron.
Materials and Methods: We compared the expression of IROMPs from strains of H. pylori under both iron-restricted and iron-supplemented conditions to determine the difference between strains with and without IDA. One standard strain, two clinical strains, and three IDA strains were cultured; and then the IROMPs were extracted under iron-restricted and iron-supplemented conditions. We used SDS-PAGE to compare the expression of the IROMPs from each strain.
Results: IROMPs were found in IDA strains under iron-restricted conditions and their molecular sizes were estimated to be 56, 48, 41, and 37 kDa. In the iron-repleted media, the IROMPs were no longer present.
Conclusion: In the iron-depleted state, specific H. pylori strains associated with IDA demonstrated an advantage in iron acquisition due to a higher expression of IROMPs. Our results can explain in part why some patients with H. pylori infection are more prone to develop clinical IDA under restricted iron conditions in the host. 相似文献
Materials and Methods: We compared the expression of IROMPs from strains of H. pylori under both iron-restricted and iron-supplemented conditions to determine the difference between strains with and without IDA. One standard strain, two clinical strains, and three IDA strains were cultured; and then the IROMPs were extracted under iron-restricted and iron-supplemented conditions. We used SDS-PAGE to compare the expression of the IROMPs from each strain.
Results: IROMPs were found in IDA strains under iron-restricted conditions and their molecular sizes were estimated to be 56, 48, 41, and 37 kDa. In the iron-repleted media, the IROMPs were no longer present.
Conclusion: In the iron-depleted state, specific H. pylori strains associated with IDA demonstrated an advantage in iron acquisition due to a higher expression of IROMPs. Our results can explain in part why some patients with H. pylori infection are more prone to develop clinical IDA under restricted iron conditions in the host. 相似文献