Sterol

About: Sterol is a research topic. Over the lifetime, 8117 publications have been published within this topic receiving 309926 citations. The topic is also known as: sterols & sterol lipids.

Effect of light and feeding on the fatty acid and sterol composition of zooxanthellae and host tissue isolated from the scleractinian coral Turbinaria reniformis

Abstract: The fatty acid and sterol compositions of zooxanthellae and animal fractions of the scleractinian coral Turbinaria reniformis were investigated under different light and feeding conditions, to study the symbiont-host exchanges. Nubbins were maintained during 6 weeks under two light levels (100 mmol photons m22 s21 and 300 mmol photons m22 s21) and two feeding levels (starved and fed with zooplankton) in a factorial experiment. There were greater proportions of some polyunsaturated fatty acids (PUFA; e.g., C18:4 n-3, C20:5 n-3, C22:6 n-3) in the zooxanthellae than in the host, suggesting that these PUFA were synthesized by the algae and transferred to the animal. Conversely, C20:4 n-6 exhibited a greater proportion in the host and might have been synthesized by the animal. Light affected the chlorophyll content, the rates of photosynthesis, and the lipid production of all coral samples. Corals maintained in high-light conditions had lower relative phytol content but higher concentrations of fatty acids (FA) and sterols than the shaded corals. Feeding also affected coral metabolism, but differently according to the light level and despite the fact that the host did not directly incorporate the zooplankton lipids (PUFA and cholesterol). In low light, feeding resulted in an increase of growth rates and storage lipid concentrations, mainly saturated fatty acids (SAFA) and membrane constituents (PUFA and sterols). In high light, the lipid energy from the food was directed toward an increase in calcification, as well as in chlorophyll content and protein content. This study highlights the importance of feeding in sustaining coral metabolism, especially when light, or stress events, is limiting photosynthesis.

Comparative Effects of Phytosterol Oxides and Cholesterol Oxides in Cultured Macrophage-Derived Cell Lines

Abstract: The cytotoxicity of cholesterol and a mixture of β-sitosterol/campesterol (50%/40%) and their oxides was examined in a cultured-derived macrophage cell line, C57BL/6. Cell numbers, lactate dehydrogenase (LDH) leakage, protein content, lipid uptake, and mitochondria dehydrogenase activity were determined after exposure of cell mononlayers to sterols and sterol oxides at a concentration of 200 μg/mL for up to 120 h. Results indicate that the oxides of cholesterol, β-sitosterol, and campesterol exhibited similar patterns of toxicity as indicated by LDH leakage, cell viability, and mitochondria dehydrogenase activity. Greatest cell damage was associated with treatments containing 5α,6α-epoxide or cholesterol oxides, followed by β-sitosterol/campesterol oxides, cholesterol, and β-sitosterol. The oxides of β-sitosterol/campesterol caused less LDH leakage and less of an effect on protein content. Results of this study demonstrate that phytosterols contained in vegetable oils, when subjected to frying conditions,...

Composition and role of tapetal lipid bodies in the biogenesis of the pollen coat of Brassica napus.

Abstract: The composition of the two major lipidic organelles of the tapetum of Brassica napus L has been determined Elaioplasts contained numerous small (02–06 μm) lipid bodies that were largely made up of sterol esters and triacylglycerols, with monogalactosyldiacylglycerol as the major polar lipid This is the first report in any species of the presence of non-cytosolic, sterol ester-rich, lipid bodies The elaioplast lipid bodies also contained 34- and 36-kDa proteins which were shown by N-terminal sequencing to be homologous to fibrillin and other plastid lipid-associated proteins Tapetosomes contained mainly polyunsaturated triacylglycerols and associated phospholipids plus a diverse class of oleosin-like proteins The pollen coat, which is derived from tapetosomes and elaioplasts, was largely made up of sterol esters and the C-terminal domains of the oleosin-like proteins, but contained virtually no galactolipids, triacylglycerols or plastid lipid-associated proteins The sterol compositions of the elaioplast and pollen coat were almost identical, consisting of stigmasterol > campestdienol > campesterol > sitosterol ≫ cholesterol, which is consistent with the majority of the pollen coat lipids being derived from elaioplasts These data demonstrate that there is substantial remodelling of both the lipid and protein components of elaioplasts and tapetosomes following their release into the anther locule from lysed tapetal cells, and that components of both organelles contribute to the formation of the lipidic coating of mature pollen grains

Differential Properties of the Sterols Cholesterol, Ergosterol, β-Sitosterol, trans-7-Dehydrocholesterol, Stigmasterol and Lanosterol on DPPC Bilayer Order

Abstract: Cholesterol, its precursor lanosterol, the plant sterols β-sitosterol and ergosterol, as well as three further sterols were added up to 50 mol % to vesicles of the phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC). The aim of this study was to investigate the influence of the sterol side chain and ring structure on the acyl chain orientational order of the lipid bilayer by measuring the steady-state fluorescence anisotropy rss of the fluorophore 1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and to establish the molecular basis underlying the changes in order parameter of the lipid bilayer system. Experiments were carried out in the temperature range from 30 to 60 °C, i.e., at temperatures below and above the gel to liquid-crystalline phase transition temperature Tm of DPPC bilayers. In general, the incorporation of the different sterols into the DPPC bilayer enhances the orientational order of TMA-DPH in the liquid-crystalline state of DPPC, whereas the orientationa...