The effect of sterols on the kinetics of membrane-bound enzymes was examined. Two strains of the yeast Saccharomyces cerevisiae were used for this purpose: the wild-type haploid strain, S288C, and the lipid auxotroph mutant Ole-3 (Resnick & Mortimer, 1966). The primary lesion in the Ole-3 mutant is the loss of 8-aminolaevulinate synthetase (EC 2.3.1.37) (Woods et al., 1975). Consequently, the m...

LITERATURE is replete with references to the determination of serum cholesterol and its esters. This can probably be attributed to 2 hnain reasons : the difficulty in chemically determining this sterol in serum with any degree of specificity, and the present intense interest in the relationship of cholesterol to atherosclerosis. Several excellent reviews of cholesterol and methods for its deter...

BACKGROUND/AIMS Our previous study confirmed that Aloe sterol stimulates collagen and hyaluronic acid production in human dermal fibroblasts. This study aims to investigate whether Aloe sterol intake affects skin conditions. METHODS We performed a 12-week, randomized, double-blind, placebo-controlled study to evaluate the effects of oral Aloe sterol supplementation on skin elasticity, hydrati...

Following the discovery of ergosterol by Tanret (l), Gerard (2) observed that not only ergot, but fungi in general, contain it. Gerard was the first to recognize ergosterol in yeast, although Nageli (3) had earlier obtained a yeast “cholesterol” in crude form. In traces ergosterol is now known to be widely distributed in both plant and animal kingdoms, but the fungi, and particularly the yeasts...

Transgenic potato (Solanum tuberosum cv Désirée) plants overexpressing a soybean (Glycine max) type 1 sterol methyltransferase (GmSMT1) cDNA were generated and used to study sterol biosynthesis in relation to the production of toxic glycoalkaloids. Transgenic plants displayed an increased total sterol level in both leaves and tubers, mainly due to increased levels of the 24-ethyl sterols isofuc...

Total, free and conjugated forms (steryl esters, steryl glycosides and acyl steryl glycosides) of sterols from three microalgae that are extensively used in mariculture (Tetraselmis chuii, Nannochloropsis salina and Skeletonema costatum) were examined. The results revealed that cholesterol is the only common fraction detected in all investigated species and distributed in free and all conjugate...

In the present study, stigmasterol has been reported from Pedalium murex L. of pedaliaceae family in vivo and in vitro. Quantification data revealed that the total sterol content was higher in callus than leaves. The in vitro studies showed that the maxmium amount of total sterol was found in 6 weeks old tissue and minimum in 2 weeks old callus culture. In vivo studies showed that higher conten...

The relationship between sterol uptake and heme competence in two yeast strains impaired in heme synthesis, namely, G204 and H12-6A, was analyzed. To evaluate heme availability, a heterologous 17alpha-hydroxylase cytochrome P-450 cDNA (P-450c17) was expressed in these strains, and its activity was measured in vivo. Heme deficiency in G204 led to accumulation of squalene and lethality. The heter...

Scavenger receptor class B type I (SR-BI) is expressed in macrophages, but its role in sterol trafficking in these cells remains controversial. We examined the effect of sterol loading on SR-BI expression in human monocytes/macrophages, mouse peritoneal macrophages, and a cultured mouse macrophage cell line (J774 cells). Sterol loading using either acetylated LDL or 25-hydroxycholesterol result...

BACKGROUND Sterols are vital structural and regulatory components in eukaryotic cells; however, their biosynthetic pathways and functional roles in microalgae remain poorly understood. RESULTS In the oleaginous microalga Nannochloropsis oceanica, the sterol biosynthetic pathway produces phytosterols as minor products and cholesterol as the major product. The evidence together with their deduc...