919 resultados para INCRASSATA ELLIS LAMOUROUX


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LDL oxidation and oxidative stress are closely related to atherosclerosis. Therefore, natural antioxidants have been studied as promising candidates. In the present study, the LDL oxidation inhibition activity of bioactive compounds from Halimeda incrassata seaweed. associated to antioxidant capacity, was evaluated in vitro. Experimental work was conducted with lyophilized aqueous extract and phenolic-rich fractions of the seaweed and their effect on LDL oxidation was evaluated using heparin-precipitated LDL (hep-LDL) with exposure to Cu2+ ions and AAPH as the free radical generator. H. incrassata had a protective effect for hep-LDL in both systems and the presence of phenolic compounds contributed to the activity where phenolic-rich fractions showed significant capacity for inhibition of oxidation mediated by Cu2+ ions. The observed effect could be related to the antioxidant potential of polar fractions evidenced by reducing activity and DPPH center dot radical scavenging. The results obtained in vitro further support the antioxidant and LDL oxidation inhibition properties of H. incrassata and further knowledge toward future phytotherapeutic application of the seaweed.

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LDL oxidation and oxidative stress are closely related to atherosclerosis. Therefore, natural antioxidants have been studied as promising candidates. In the present study, the LDL oxidation inhibition activity of bioactive compounds from Halimeda incrassata seaweed. associated to antioxidant capacity, was evaluated in vitro. Experimental work was conducted with lyophilized aqueous extract and phenolic-rich fractions of the seaweed and their effect on LDL oxidation was evaluated using heparin-precipitated LDL (hep-LDL) with exposure to Cu2+ ions and AAPH as the free radical generator. H. incrassata had a protective effect for hep-LDL in both systems and the presence of phenolic compounds contributed to the activity where phenolic-rich fractions showed significant capacity for inhibition of oxidation mediated by Cu2+ ions. The observed effect could be related to the antioxidant potential of polar fractions evidenced by reducing activity and DPPH radical scavenging. The results obtained in vitro further support the antioxidant and LDL oxidation inhibition properties of H. incrassata and further knowledge toward future phytotherapeutic application of the seaweed.

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Ocean acidification poses a serious threat to a broad suite of calcifying organisms. Scleractinian corals and cal- careous algae that occupy shallow, tropical waters are vulnerable to global changes in ocean chemistry be- cause they already are subject to stressful and variable carbon dynamics at the local scale. For example, net heterotrophy increases carbon dioxide concentrations, and pH varies with diurnal fluctuations in photosyn- thesis and respiration. Few researchers, however, have investigated the possibility that carbon dioxide con- sumption during photosynthesis by non-calcifying photoautotrophs, such as seagrasses, can ameliorate deleterious effects of ocean acidi fi cation on sympatric calcareous algae. Naturally occurring variations in the density of seagrasses and associated calcareous algae provide an ecologically relevant test of the hypoth- esis that diel fl uctuations in water chemistry driven by cycles of photosynthesis and respiration within seagrass beds create microenvironments that enhance macroalgal calci fi cation. In Grape Tree Bay off Little Cayman Island BWI, we quanti fi ed net production and characterized calci fi cation for thalli of the calcareous green alga Halimeda incrassata growing within beds of Thalassia testudinum with varying shoot densities. Re- sults indicated that individual H . incrassata thalli were ~6% more calci fi ed in dense seagrass beds. On an areal basis, however, far more calcium carbonate was produced by H . incrassata in areas where seagrasses were less dense due to higher rates of production. In addition, diel pH regimes in vegetated and unvegetated areas within the lagoon were not signi fi cantly different, suggesting a high degree of water exchange and mixing throughout the lagoon. These results suggest that, especially in well-mixed lagoons, carbonate pro- duction by calcareous algae may be more related to biotic interactions between seagrasses and calcareous algae than to seagrass-mediated changes in local water chemistry.

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Antioxidant activity and hepatoprotective properties of the aqueous extract and tetrahydrofuran-extracted phenolic fractions of Halimeda opuntia (Linnaeus) Lamouroux were investigated in rats with chemically induced liver injury. Total polyphenols were determined by using the Folin-Ciocalteau reagent. Liver damage was induced by CCl4 and assessed by a histological technique. Reverse transcription/polymerase chain reaction (RT/PCR) analysis showed increased superoxide dismutase (SOD) and catalase (CAT) gene expression and activities in the group treated with free phenolic acid (FPA) fractions of H. opuntia, suggesting inducing effects on both enzymes. In addition, rats treated with FPA fractions displayed lower liver thiobarbituric acid reactive substance (TBARS) levels than those observed for rats in the CCl4-treated group. These data suggest that the phenolic fractions from H. opuntia may protect the liver against oxidative stress-inducing effects of chemicals by modulating its antioxidant enzymes and oxidative status.

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In this work, in vitro and in vivo antioxidant properties of the marine algae Halimeda monile were assessed and the levels of some of its compounds likely to be responsible for such properties were determined. The estimated contents of total polyphenols, chlorophylls a and b and carotenoids were 179.5, 356.3, 452.8 and 42.2 mu g/g dry weight seaweed, respectively. The presence of terpenoids and flavonoids was also observed. The antioxidant activity of two polar fractions from H. monile (lyophilized aqueous extract and free phenolic acid fraction) was evaluated using three antioxidant assays: ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl and lipid peroxidation. Treatment of CCl4-induced liver damage in rats with extracts resulted in lower serum thiobarbituric acid-reactive substances levels and higher hepatic glutathione concentrations compared to those observed in the CCl4-treated group. Also, a significant increase in catalase activity was detected after treatment with the extracts. These results suggest that the seaweed H. monile could be a potential source for natural antioxidants.

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This review examines five books in the Oxford Business English Express Series, including "English for telecoms and information technology" by T. Ricca and M. Duckworth; "English for legal professionals" by A. Frost; "English for the pharmaceutical industry" by M. Buchler, K. Jaehnig, G. Matzig, and T. Weindler; "English for cabin crews" by S. Ellis and L. Lansford; and "English for negotiating" by C. Lafond, S. Vine, and B. Welch.

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The herbarium material belonging to the genus Laurencia kept at the Royal Botanical Gardens, Peradeniya together with my collections of material belonging to this genus from various parts of Ceylon have been examined. Most of the material belonging to the genus Laurencia had been incorrectly identified and their true identity has been determined. A key to the Ceylon species of Laurencia is given.

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The chloroplasts, mitochondria, and protoplasm devoid of mature chloroplasts (PMC) of Bryopsis hypnoides Lamouroux were isolated by low-speed and sucrose density centrifugation. The PMC aggregated in artificial seawater, and then protoplasts without mature chloroplasts (PtMCs) were formed. Transmission electron microscopy and cytochemical studies indicated that there were mitochondria, nuclei, vesicles, and other small cell organelles in the PtMCs. Scanning electron microscopy showed that there were holes on the surface of 1-h PtMCs and then fewer holes on the surface of 24-h PtMCs, suggesting that a healing process occurred. The plasma membrane was formed over the surface of the PtMCs. However, the cell wall was not regenerated, and the newly formed PtMCs were ruptured and died in 3 days. Light intensity during alga maintenance before use influenced significantly (one-way ANOVA, P < 0.0001) on the number of PtMCs formed; the highest number of PtMCs was formed at 20A mu mol/(m(2) s). When isolated chloroplasts were transferred into seawater, there were only two or three chloroplasts aggregated together. However, isolated mitochondria and the mixed six layers of cell organelles (separated by sucrose density centrifugation) could not aggregate in the artificial seawater. This indicates that the conjunction of cell organelles is important for their aggregation.

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Tissue culture, SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and spectra analysis were used for studying the aggregation mechanism of protoplasts from Bryopsis hypnoides Lamouroux and the discrepancy between the protoplast-regenerated plants and the wild type. The aggregation of protoplasts from B. hypnoides was observed in natural seawater and artificial seawater with different pH values, and the location and mechanism of the materials causing the aggregation were also studied. Results showed that the protoplasts could aggregate into some viable spheres in natural seawater and subsequently grow into mature individuals. Aggregation of the protoplasts depended exclusively upon the pH value (6-11), and the protoplasts aggregated best at pH 8-9. Some of the extruded protoplasts were separated into two parts by centrifugation: the pellet (PO) and the supernatant (PL). The PO could aggregate in artificial seawater (pH 8.3) but not in PL. No aggregation was found in PO cultured in natural seawater containing nigericin, which can dissipate the proton gradients across the membrane. These experiments suggest that the aggregation of protoplasts is proton-gradient dependent and the materials causing the aggregation were not in the vacuolar sap, but located on the surface or inside the organelles. Furthermore, the transfer of the materials across the membrane was similar to Delta pH-based translocation (Delta pH/TAT) pathway that occurs in the chloroplasts of higher plants and bacteria. Obvious discrepancies in both the total soluble proteins and the ratio of chlorophyll a to chlorophyll b between the regenerated B. hypnoides and the wild type were found, which may be related to the exchange of genetic material during aggregation of the organelles. In the process of development, diatom Amphora coffeaeformis Agardh attached to the protoplast aggregations, retarding their further development, and once they were removed, the aggregations immediately germinated, which showed that diatoms can affect the development of other algae.

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