Tobacco plants (Nicotiana tabacum L.) were grown in the field and the apex was removed at the 42-day stage. Shading screens were set up which produced 0, 26, 67, and 90% shade. Plants were grown an additional 25 days before leaves from top, middle, and bottom stalk positions were harvested. Each leaf group was analyzed for free sterol, steryl ester, steryl glycoside, and acylsteryl glycoside. T...

The polyene antibiotic, filipin, by specifically interacting with cholesterol, produces approximately 25-nm protuberances (filipin-sterol complexes) in freeze-fractured membranes, and the addition of filipin to aldehyde fixatives has been recently introduced as a cytochemical technique for the localization of cholesterol in cell membranes. In a previous study we showed that, in fibroblasts fili...

The present studies were undertaken to determine whether mevalonate 5-pyrophosphate decarboxylase (EC 4.1.1.33) is subject to physiological regulation in the intestinal mucosa. Activity was determined in epithelial cells isolated in a villus-to-crypt gradient from chicks fed on different diets in order to vary the sterol flux across the intestinal epithelium. When animals were fed on cholestero...

Pregnenolone (PREG) can be converted to PREG esters (PE) by the plasma enzyme lecithin: cholesterol acyltransferase (LCAT), and by other enzyme(s) with unknown identity. Acyl-CoA:cholesterol acyltransferase 1 and 2 (ACAT1 and ACAT2) convert various sterols to steryl esters; their activities are activated by cholesterol. PREG is a sterol-like molecule, with 3-β-hydroxy moiety at steroid ring A, ...

Trypanosoma brucei (TB) cultured in rat blood, bovine serum, or lipid-depleted serum generated distinct differences in cholesterol availability. Whereas cell proliferation of the parasite was relatively unaffected by cholesterol availability, the ratios of cellular ergostenols to cholesterol varied from close to unity to 3 orders of magnitude different with cholesterol as the major sterol (>99%...

in this study, the oil yield, fatty acid (fa) composition and the physicochemical and quality characteristics of salvia macrosiphon crude seed oil were determined. the main fatty acids ranked in the following order of abundance: α- linolenic acid> linoleic acid> oleic acid. the n3 /n6 fa ratio and polyunsaturated fa/ saturated fa ratio were 1.6 and 7.23, respectively. the fa composition reveale...

in this project, different nettle plants from north regions of iran including tonekabon, amol and gorgan were collected. the oil was extracted using soxhlet extraction apparatus and was subjected to series of physical and chemical tests and determinations consisting of refractive index, melting point, smoke point, nonsaponifiable matter, iodine value, saponification value, peroxide value, totox...

Thus, the content-determination and rhetorical planning functions are not integrated in AlethGen, but separated in two different sub-modules. On one hand, Ale thGen ' s Rhetorical planner produces surface rhetorical representation (not intermediate, as for example in RST [Mann & Thompson 88]). On the need for surface rhetorical representation, see [Coch & David 94]. On the other hand, Rhetorica...

We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5kbar at 30 degrees C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-beta-cyclodextrin were also studied. We found that application of ...