beta-sitosterol-sulfate and cholesteryl-sulfate

Cell mortality is a key mechanism that shapes phytoplankton blooms and species dynamics in aquatic environments. Here we show that sterol sulfates (StS) are regulatory molecules of a cell death program in Skeletonema marinoi, a marine diatom-blooming species in temperate coastal waters. The molecules trigger an oxidative burst and production of nitric oxide in a dose-dependent manner. The intracellular level of StS increases with cell ageing and ultimately leads to a mechanism of apoptosis-like death. Disrupting StS biosynthesis by inhibition of the sulfonation step significantly delays the onset of this fatal process and maintains steady growth in algal cells for several days. The autoinhibitory activity of StS demonstrates the functional significance of small metabolites in diatoms. The StS pathway provides another view on cell regulation during bloom dynamics in marine habitats and opens new opportunities for the biochemical control of mass-cultivation of microalgae.

Topics: Cholestadienols; Cholesterol Esters; Diatoms; Ecosystem; Eutrophication; Microalgae; Phylogeny; Phytoplankton; Phytosterols; Signal Transduction; Sitosterols; Sterols; Sulfates; Sulfotransferases

Evidence indicating that there exist in bovine brains hitherto-unrecognized lipophilic conjugates of sterol sulfates is presented. These conjugates are soluble in nonpolar solvents and, when heated in methanol containing pyridine, yield polar sterol conjugates. These polar substances have the chromatographic mobility of sterol sulfates and are cleaved to free sterols when subjected to a solvolytic process known to be specific for sulfate esters. The brain sterols that have been identified in this way are cholesterol and beta-sitosterol.

Topics: Animals; Brain Chemistry; Cattle; Cholesterol Esters; Chromatography; Sitosterols; Solvents

Topics: Animals; Cholesterol Esters; Contraceptive Agents, Female; Drug Implants; Female; Fertility; Rabbits; Sitosterols; Uterus; Vaginal Creams, Foams, and Jellies

A new method is described for the measurement of cholesteryl sulfate (CS) in plasma. Taking advantage of the use of beta-sitosteryl sulfate (SS) as an internal standard it is simpler and more rapid than the methods currently in use. It does not require the use of radioactive isotopes. A potential contamination of the CS band by free cholesterol is excluded by developing the thin-layer chromatography plate on which the sterols are first separated with a second solvent system which pushes free cholesterol to the solvent front without appreciably moving the CS band. The method is sensitive and reproducible and may be advantageous for the screening of large populations. The values obtained for plasma CS concentrations in normal subjects compare well with those measured by more elaborate techniques.

Topics: Cholesterol; Cholesterol Esters; Chromatography, Gas; Chromatography, Thin Layer; Female; Humans; Hydrolysis; Hyperlipoproteinemia Type II; Male; Sitosterols